U.S. patent application number 17/059599 was filed with the patent office on 2021-07-22 for highly heat-resistant resin composite including chemically modified, fine cellulose fibers.
This patent application is currently assigned to Asahi Kasei Kabushiki Kaisha. The applicant listed for this patent is Asahi Kasei Kabushiki Kaisha. Invention is credited to Kazufumi Kawahara, Masahiro Ohga, Hirofumi Ono, Ryosuke Ozawa.
Application Number | 20210222006 17/059599 |
Document ID | / |
Family ID | 1000005542171 |
Filed Date | 2021-07-22 |
United States Patent
Application |
20210222006 |
Kind Code |
A1 |
Ono; Hirofumi ; et
al. |
July 22, 2021 |
Highly Heat-Resistant Resin Composite Including Chemically
Modified, Fine Cellulose Fibers
Abstract
Provided is a resin composite having high mechanical properties
which make the resin composite moldable into and usable as members
for use in applications such as vehicle-mounted members and
electrical materials. The resin composite comprises 0.5-40 mass %
chemically modified, fine cellulose fibers and a resin, wherein the
chemically modified, fine cellulose fibers have a pyrolysis
initiation temperature (T.sub.D) of 270.degree. C. or higher, a
number-average fiber diameter of 10 nm or larger but less than 1
.mu.m, and a degree of crystallinity of 60% or higher. In a
preferred embodiment, the chemically modified, fine cellulose
fibers have a coefficient of variation (CV) in DS unevenness ratio,
DSs/DSt, of 50% or less, the DS unevenness ratio being the ratio of
the modification degree (DSs) of the surface layers of the fibers
to the modification degree (DSt) of the whole of the fibers.
Inventors: |
Ono; Hirofumi; (Tokyo,
JP) ; Kawahara; Kazufumi; (Tokyo, JP) ; Ozawa;
Ryosuke; (Tokyo, JP) ; Ohga; Masahiro; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asahi Kasei Kabushiki Kaisha |
Tokyo |
|
JP |
|
|
Assignee: |
Asahi Kasei Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
1000005542171 |
Appl. No.: |
17/059599 |
Filed: |
May 31, 2019 |
PCT Filed: |
May 31, 2019 |
PCT NO: |
PCT/JP2019/021845 |
371 Date: |
November 30, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 77/06 20130101;
C08J 2401/10 20130101; C08J 2377/06 20130101; C08B 3/06 20130101;
C08J 5/06 20130101 |
International
Class: |
C08L 77/06 20060101
C08L077/06; C08B 3/06 20060101 C08B003/06; C08J 5/06 20060101
C08J005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2018 |
JP |
2018-106456 |
Claims
1-33. (canceled)
34. Chemically modified fine cellulose fibers wherein the
weight-average molecular weight (Mw) is 100,000 or higher, the
ratio (Mw/Mn) of the weight-average molecular weight (Mw) and
number-average molecular weight (Mn) is 6 or lower, the
alkali-soluble portion content is 12 mass % or lower and the degree
of crystallinity is 60% or higher.
35. The chemically modified fine cellulose fibers according to
claim 34, wherein the thermal decomposition initiation temperature
(T.sub.D) is 270.degree. C. or higher and the number-average fiber
diameter is 10 nm or greater and less than 1 .mu.m.
36. The chemically modified fine cellulose fibers according to
claim 34, which are esterified fine cellulose fibers.
37. The chemically modified fine cellulose fibers according to
claim 34, wherein the average degree of substitution of hydroxyl
groups is 0.5 or greater.
38. The chemically modified fine cellulose fibers according to
claim 34, wherein the coefficient of variation (CV) of the DS
non-uniformity ratio (DSs/DSt), as the ratio of the degree of
modification (DSs) of the fiber surface with respect to the degree
of modification (DSt) of the entire chemically modified fine
cellulose fibers, is 50% or lower.
39. The chemically modified fine cellulose fibers according to
claim 34, wherein the average content of the acid-insoluble
component per unit specific surface area of the chemically modified
fine cellulose fibers is 1.0 mass %g/m.sup.2 or lower.
40. A method for producing chemically modified fine cellulose
fibers, which includes: defibrating a cellulose starting material
having a weight-average molecular weight (Mw) of 100,000 or
greater, a ratio (Mw/Mn) of weight-average molecular weight (Mw)
and number-average molecular weight (Mn) of 6 or lower and an
alkali-soluble content of 12 mass % or lower, in a dispersion that
includes an aprotic solvent, to obtain fine cellulose fibers, and
adding a modifying agent-containing solution to the dispersion to
modify the fine cellulose fibers, thereby obtaining chemically
modified fine cellulose fibers having a weight-average molecular
weight (Mw) of 100,000 or greater, a ratio (Mw/Mn) of
weight-average molecular weight (Mw) and number-average molecular
weight (Mn) of 6 or lower, an alkali-soluble content of 12 mass %
or lower and a degree of crystallinity of 60% or higher.
41. A resin composite containing 0.5 to 40 mass % of chemically
modified fine cellulose fibers and a resin, wherein the DS
non-uniformity ratio (DSs/DSt), as the ratio of the degree of
modification (DSs) of the fiber surfaces with respect to the degree
of modification (DSt) of the entire chemically modified fine
cellulose fibers, is 1.1 or greater, and the coefficient of
variation (CV) of the DS non-uniformity ratio (DSs/DSt) is 50% or
lower.
42. The resin composite according to claim 41, wherein the
chemically modified fine cellulose fibers have: a thermal
decomposition initiation temperature (T.sub.D) of 270.degree. C. or
higher, a number-average fiber diameter of 10 nm or greater and
less than 1 .mu.m, and a degree of crystallinity of 60% or
higher.
43. The resin composite according to claim 41, wherein the resin is
a thermoplastic resin.
44. The resin composite according to claim 41, wherein the melting
point of the resin is 220.degree. C. or higher.
45. The resin composite according to claim 41, wherein the
weight-average molecular weight (Mw) of the chemically modified
fine cellulose fibers is 100,000 or greater, and the ratio (Mw/Mn)
of the weight-average molecular weight (Mw) and number-average
molecular weight (Mn) is 6 or lower.
46. The resin composite according to claim 41, wherein the average
degree of substitution of hydroxyl groups of the chemically
modified fine cellulose fibers is 0.5 or greater.
47. The resin composite according to claim 41, wherein the
chemically modified fine cellulose fibers are esterified fine
cellulose fibers.
48. The resin composite according to claim 41, wherein the content
of the alkali-soluble portion of the chemically modified fine
cellulose fibers is 12 mass % or lower.
49. The resin composite according to claim 41, wherein the average
content of the acid-insoluble component per unit specific surface
area of the chemically modified fine cellulose fibers is 1.0 mass
%g/m.sup.2 or lower.
50. A resin composite containing 0.5 to 40 mass % of chemically
modified fine cellulose fibers according to claim 34, and a
resin.
51. A method for producing a resin composite containing 0.5 to 40
mass % of chemically modified fine cellulose fibers, and a resin,
wherein the method includes: a defibrating step in which a
cellulose starting material is defibrated in a dispersion that
includes the cellulose starting material and an aprotic solvent but
essentially does not include an ionic liquid or sulfuric acid, to
obtain fine cellulose fibers, a modifying step in which a solution
that includes a modifying agent is added to the dispersion for
chemical modification of the fine cellulose fibers, to obtain
chemically modified fine cellulose fibers, and a kneading step in
which the chemically modified fine cellulose fibers and the resin
are kneaded, the DS non-uniformity ratio (DSs/DSt), as the ratio of
the degree of modification (DSs) of the fiber surfaces with respect
to the degree of modification (DSt) of the entire chemically
modified fine cellulose fibers, is 1.1 or greater, and the
coefficient of variation (CV) of the DS non-uniformity ratio
(DSs/DSt) is 50% or lower.
52. A method for producing a resin composite according to claim 41,
wherein the method includes: a step of defibrating cellulose in a
dispersion containing a cellulose starting material with a
cellulose purity of 85 mass % or greater, and an aprotic solvent,
to obtain fine cellulose fibers, a step of adding a solution
containing a modifying agent to the dispersion to modify the fine
cellulose fibers, thereby obtaining chemically modified fine
cellulose fibers having a thermal decomposition initiation
temperature (T.sub.D) of 270.degree. C. or higher, a number-average
fiber diameter of 10 nm or greater and less than 1 .mu.m, and a
degree of crystallinity of 60% or higher, and a step of mixing the
chemically modified fine cellulose fibers with a resin.
53. The method according to claim 51, wherein the aprotic solvent
is dimethyl sulfoxide, and the modifying agent is vinyl acetate or
acetic anhydride.
54. The method according to claim 52, wherein the aprotic solvent
is dimethyl sulfoxide, and the modifying agent is vinyl acetate or
acetic anhydride.
55. A member for an automobile, comprising a resin composite
according to claim 41.
56. A member for an automobile, comprising a resin composite
according to claim 50.
57. A member for an electronic product, comprising a resin
composite according to claim 41.
58. A member for an electronic product, comprising a resin
composite according to claim 50.
Description
FIELD
[0001] The present invention relates to a resin composite
containing chemically modified fine cellulose fibers and having a
high thermal decomposition initiation temperature.
BACKGROUND
[0002] Resins are light and have excellent processing
characteristics, and are therefore widely used for a variety of
purposes including automobile members, electrical and electronic
parts, business machine housings, precision parts and the like.
With resins alone, however, the mechanical properties and
dimensional stability are often inadequate, and therefore it is
common to use composites of resins with different types of
inorganic materials.
[0003] Resin compositions comprising resins reinforced with
reinforcing materials consisting of inorganic fillers such as glass
fibers, carbon fibers, talc or clay have high specific gravity, and
the obtained molded resins thus have higher weight.
[0004] In recent years, cellulose nanofibers (CNF) have come into
use as new reinforcing materials for resins.
[0005] In terms of simple properties, fine cellulose fibers are
known to have a high elastic modulus similar to aramid fibers, and
a lower linear expansion coefficient than glass fibers. In
addition, they exhibit a low true density of 1.56 g/cm.sup.3, which
is overwhelmingly lighter than glass (density: 2.4 to 2.6
g/cm.sup.3) or talc (density: 2.7 g/cm.sup.3) which are used as
common reinforcing materials for thermoplastic resins.
[0006] Fine cellulose fibers are obtained from a variety of
sources, including those obtained from trees as starting materials,
as well as from hemp, cotton, kenaf and cassava starting materials.
Bacterial celluloses are also known, typical of which is nata de
coco. These natural resources that can serve as starting materials
are abundant throughout the Earth, and a great deal of effort has
been focused on techniques for taking advantage of fine cellulose
fibers as fillers in resins, to allow them to be effectively
utilized.
[0007] PTL 1 describes a technique of impacting wood pulp or the
like in a high-pressure stream jet to obtain fine cellulose fibers,
and then derivatizing the fine cellulose fibers to improve the
compatibility between hydrophobic resins and the fine cellulose
fibers.
[0008] In PTLs 2 to 4 there are described techniques of using an
ionic liquid for chemical modification (derivatization) of fine
cellulose fibers obtained from defibrating treatment of a fiber
starting material, to chemically modify the hydroxyl groups of the
fine cellulose fibers and increase the heat resistance.
[0009] PTL 5 describes a technique for chemically modifying fine
cellulose fibers containing lignin to increase the heat resistance,
while increasing the compatibility between the fine cellulose
fibers and resins due to the lignin.
[0010] In PTLs 6 and 7 there are described techniques of adding
cellulose pulp to a liquid mixture containing an aprotic solvent, a
fine cellulose fiber chemical modifier and a catalyst component
that promotes chemical modification, and carrying out continued
stirring to prepare chemically modified fine cellulose fibers.
CITATION LIST
Patent Literature
[0011] [PTL 1] International Patent Publication No.
WO2016/010016
[0012] [PTL 2] Japanese Unexamined Patent Publication No.
2013-44076
[0013] [PTL 3] Japanese Unexamined Patent Publication No.
2013-43984
[0014] [PTL 4] Japanese Unexamined Patent Publication No.
2010-104768
[0015] [PTL 5] International Patent Publication No.
WO2016/148233
[0016] [PTL 6] International Patent Publication No.
WO2017/073700
[0017] [PTL 7] International Patent Publication No.
WO2017/159823
SUMMARY
Technical Problem
[0018] Using these prior art techniques can be expected to provide
some degree of effect by imparting certain physical properties to
the resins, but from the viewpoint of obtaining heat resistance
that can withstand use for on-vehicle purposes, there is still a
need to provide resin composites with even higher heat
resistance.
[0019] The problem to be solved by one aspect of the present
invention is to provide a resin composite that has high mechanical
properties, and that is able to withstand casting and use for
members to be used for on-vehicle purposes.
Solution to Problem
[0020] Specifically, the present invention encompasses the
following aspects.
[0021] [1] A resin composite containing 0.5 to 40 mass % of
chemically modified fine cellulose fibers, and a resin, wherein the
chemically modified fine cellulose fibers have:
[0022] a thermal decomposition initiation temperature (T.sub.D) of
270.degree. C. or higher,
[0023] a number-average fiber diameter of 10 nm or greater and less
than 1 .mu.m, and
[0024] a degree of crystallinity of 60% or higher.
[0025] [2] The resin composite according to aspect 1, wherein the
chemically modified fine cellulose fibers are dispersed in a resin
composite in the form of a dispersion comprising a dispersion
stabilizer and the chemically modified fine cellulose fibers
dispersed in the dispersion stabilizer, and the content of the
chemically modified fine cellulose fibers in the dispersion is 10
to 99 mass %.
[0026] [3] The resin composite according to aspect 1 or 2, wherein
the dispersion stabilizer is at least one selected from the group
consisting of surfactants and organic compounds with a boiling
point of 160.degree. C. or higher.
[0027] [4] The resin composite according to any one of aspects 1 to
3, wherein the resin is at least one type selected from the group
consisting of thermoplastic resins, thermosetting resins and
photocuring resins.
[0028] [5] The resin composite according to aspect 4, wherein the
resin is a thermoplastic resin.
[0029] [6] The resin composite according to any one of aspects 1 to
5, wherein the resin is at least one selected from the group
consisting of polyolefin-based resins, polyacetate-based resins,
polycarbonate-based resins, polyamide-based resins, polyester-based
resins, polyphenylene ether-based resins and acrylic-based
resins.
[0030] [7] A resin composite according to any one of aspects 1 to
6, wherein the melting point of the resin is 220.degree. C. or
higher.
[0031] [8] The resin composite according to any one of aspects 1 to
7, wherein the linear coefficient of thermal expansion (CTE) of the
resin composite is 80 ppm/k or smaller.
[0032] [9] The resin composite according to any one of aspects 1 to
8, wherein the weight-average molecular weight (Mw) of the
chemically modified fine cellulose fibers is 100,000 or greater,
and the ratio (Mw/Mn) of the weight-average molecular weight (Mw)
and number-average molecular weight (Mn) is 6 or lower.
[0033] [10] The resin composite according to any one of aspects 1
to 9, wherein the average degree of substitution of hydroxyl groups
of the chemically modified fine cellulose fibers is 0.5 or
greater.
[0034] [11] The resin composite according to any one of aspects 1
to 10, wherein the chemically modified fine cellulose fibers are
esterified fine cellulose fibers.
[0035] [12] The resin composite according to any one of aspects 1
to 11, wherein the degree of modification, as defined by the ratio
of the peak intensity of the absorption band of the acyl group
C.dbd.O with respect to the peak intensity of the absorption band
of C--H on the cellulose backbone chain, in total
reflection-infrared absorption spectrometry of the chemically
modified fine cellulose fibers (the IR index 1370), is 0.8 or
greater.
[0036] [13] The resin composite according to any one of aspects 1
to 12, wherein the degree of modification, as defined by the ratio
of the peak intensity of the absorption band of the acyl group
C.dbd.O with respect to the peak intensity of the absorption band
of C--O on the cellulose backbone chain, in total
reflection-infrared absorption spectrometry of the chemically
modified fine cellulose fibers (the IR index 1030), is 0.13 or
greater.
[0037] [14] The resin composite according to any one of aspects 1
to 13, wherein the coefficient of variation (CV) of the DS
non-uniformity ratio (DSs/DSt), as the ratio of the degree of
modification (DSs) of the fiber surface with respect to the degree
of modification (DSt) of the entire chemically modified fine
cellulose fibers, is 50% or lower.
[0038] [15] The resin composite according to any one of aspects 1
to 14, wherein the number-average fiber diameter of the chemically
modified fine cellulose fibers is 50 nm to 300 nm.
[0039] [16] The resin composite according to any one of aspects 1
to 15, wherein the content of the alkali-soluble portion of the
chemically modified fine cellulose fibers is 12 mass % or
lower.
[0040] [17] The resin composite according to any one of aspects 1
to 16, wherein the average content of the acid-insoluble component
per unit specific surface area of the chemically modified fine
cellulose fibers is 1.0 mass %g/m.sup.2 or lower.
[0041] [18] Chemically modified fine cellulose fibers wherein the
weight-average molecular weight (Mw) is 100,000 or higher, the
ratio (Mw/Mn) of the weight-average molecular weight (Mw) and
number-average molecular weight (Mn) is 6 or lower, the
alkali-soluble portion content is 12 mass % or lower and the degree
of crystallinity is 60% or higher.
[0042] [19] The chemically modified fine cellulose fibers according
to aspect 18, wherein the thermal decomposition initiation
temperature (T.sub.D) is 270.degree. C. or higher and the
number-average fiber diameter is 10 nm or greater and less than 1
.mu.m.
[0043] [20] The chemically modified fine cellulose fibers according
to aspect 18 or 19, which are esterified fine cellulose fibers.
[0044] [21] The chemically modified fine cellulose fibers according
to any one of aspects 18 to 20, wherein the average degree of
substitution of hydroxyl groups is 0.5 or greater.
[0045] [22] The chemically modified fine cellulose fibers according
to any one of aspects 18 to 21, wherein the coefficient of
variation (CV) of the DS non-uniformity ratio (DSs/DSt), as the
ratio of the degree of modification (DSs) of the fiber surface with
respect to the degree of modification (DSt) of the entire
chemically modified fine cellulose fibers, is 50% or lower.
[0046] [23] The chemically modified fine cellulose fibers according
to any one of aspects 18 to 22, wherein the average content of the
acid-insoluble component per unit specific surface area of the
chemically modified fine cellulose fibers is 1.0 mass %g/m.sup.2 or
lower.
[0047] [24] A method for producing chemically modified fine
cellulose fibers, which includes: defibrating a cellulose starting
material having a weight-average molecular weight (Mw) of 100,000
or greater, a ratio (Mw/Mn) of weight-average molecular weight (Mw)
and number-average molecular weight (Mn) of 6 or lower and an
alkali-soluble content of 12 mass % or lower, in a dispersion that
includes an aprotic solvent, to obtain fine cellulose fibers, and
adding a modifying agent-containing solution to the dispersion to
modify the fine cellulose fibers, thereby obtaining chemically
modified fine cellulose fibers having a weight-average molecular
weight (Mw) of 100,000 or greater, a ratio (Mw/Mn) of
weight-average molecular weight (Mw) and number-average molecular
weight (Mn) of 6 or lower, an alkali-soluble content of 12 mass %
or lower and a degree of crystallinity of 60% or higher.
[0048] [25] The method according to aspect 24, wherein the thermal
decomposition initiation temperature (T.sub.D) of the chemically
modified fine cellulose fibers is 270.degree. C. or higher and the
number-average fiber diameter is 10 nm or greater and less than 1
.mu.m.
[0049] [26] The method according to aspect 24 or 25, wherein the
aprotic solvent is dimethyl sulfoxide, and the modifying agent is
vinyl acetate or acetic anhydride.
[0050] [27] A resin composite containing 0.5 to 40 mass % of
chemically modified fine cellulose fibers according to any one of
aspects 18 to 23, and a resin.
[0051] [28] A resin composite containing 0.5 to 40 mass % of
chemically modified fine cellulose fibers and a resin, wherein the
DS non-uniformity ratio (DSs/DSt), as the ratio of the degree of
modification (DSs) of the fiber surfaces with respect to the degree
of modification (DSt) of the entire chemically modified fine
cellulose fibers, is 1.1 or greater, and the coefficient of
variation (CV) of the DS non-uniformity ratio (DSs/DSt) is 50% or
lower.
[0052] [29] A method for producing a resin composite containing 0.5
to 40 mass % of chemically modified fine cellulose fibers, and a
resin, wherein the method includes:
[0053] a defibrating step in which a cellulose starting material is
defibrated in a dispersion that includes the cellulose starting
material and an aprotic solvent but essentially does not include an
ionic liquid or sulfuric acid, to obtain fine cellulose fibers,
[0054] a modifying step in which a solution that includes a
modifying agent is added to the dispersion for chemical
modification of the fine cellulose fibers, to obtain chemically
modified fine cellulose fibers, and
[0055] a kneading step in which the chemically modified fine
cellulose fibers and the resin are kneaded,
[0056] the DS non-uniformity ratio (DSs/DSt), as the ratio of the
degree of modification (DSs) of the fiber surfaces with respect to
the degree of modification (DSt) of the entire chemically modified
fine cellulose fibers, is 1.1 or greater, and the coefficient of
variation (CV) of the DS non-uniformity ratio (DSs/DSt) is 50% or
lower.
[0057] [30] A method for producing a resin composite according to
any one of aspects 1 to 17, 27 and 28, wherein the method
includes:
[0058] a step of defibrating cellulose in a dispersion containing a
cellulose starting material with a cellulose purity of 85 mass % or
greater, and an aprotic solvent, to obtain fine cellulose
fibers,
[0059] a step of adding a solution containing a modifying agent to
the dispersion to modify the fine cellulose fibers, thereby
obtaining chemically modified fine cellulose fibers having a
thermal decomposition initiation temperature (T.sub.D) of
270.degree. C. or higher, a number-average fiber diameter of 10 nm
or greater and less than 1 .mu.m, and a degree of crystallinity of
60% or higher, and
[0060] a step of mixing the chemically modified fine cellulose
fibers with a resin.
[0061] [31] The method according to aspect 29 or 30, wherein the
aprotic solvent is dimethyl sulfoxide, and the modifying agent is
vinyl acetate or acetic anhydride.
[0062] [32] A member for an automobile, comprising a resin
composite according to any one of aspects 1 to 17, 27 and 28.
[0063] [33] A member for an electronic product, comprising a resin
composite according to any one of aspects 1 to 17, 27 and 28.
Advantageous Effects of Invention
[0064] The resin composite according to one aspect of the invention
can have high mechanical properties, and can withstand casting and
use for members to be used for on-vehicle purposes.
BRIEF DESCRIPTION OF DRAWINGS
[0065] FIG. 1 is an illustration of methods for measuring thermal
decomposition initiation temperature (T.sub.D) and 1% weight
reduction temperature (T.sub.1%).
[0066] FIG. 2 is an illustration of a method for calculating the IR
index 1370 and IR index 1030.
[0067] FIG. 3 is a SEM image of the chemically modified fine fibers
1-1 obtained in Production Example 1-1 of Example I.
[0068] FIG. 4 is a SEM image of the chemically modified fine fibers
2-1 obtained in Example 2-1 of Example II.
DESCRIPTION OF EMBODIMENTS
[0069] Embodiments for carrying out the invention (hereunder
referred to as "the embodiments") will now be explained in detail.
The present invention is not limited to the embodiments described
below, however, and various modifications may be implemented within
the scope of the gist thereof.
First Embodiment
[0070] The first embodiment, as one aspect of the invention,
provides a resin composite having a thermal decomposition
initiation temperature (T.sub.D) of 270.degree. C. or higher, a
number-average fiber diameter of 10 nm or greater and less than 1
.mu.m, and comprising chemically modified fine cellulose fibers.
According to one aspect, the resin composite comprises the
chemically modified fine cellulose fibers at 0.5 to 40 mass %. Also
according to one aspect, the chemically modified fine cellulose
fibers have a degree of crystallinity of 60% or higher.
[0071] The term "chemically modified fine cellulose fibers" (also
referred to throughout the present disclosure as "chemically
modified fine fibers") means fine cellulose fibers of which at
least some of the hydroxyl groups in the cellulose backbone have
been modified. According to a typical aspect, the cellulose as a
whole is not chemically modified, and the chemically modified fine
fibers retain the crystal structure of the fine cellulose fibers
before chemical modification. The crystalline structure of either
or both type I cellulose and type II cellulose can be confirmed by
analysis of the chemically modified fine fibers by XRD, for
example.
[0072] The resin composite comprises chemically modified fine
fibers and a resin. The resin composite may also include other
components (for example, an inorganic filler). The content of the
chemically modified fine fibers in the resin composite of this
embodiment is 0.5 to 40 mass %, preferably 2 to 30 mass % and more
preferably 3 to 20 mass %, according to one aspect, from the
viewpoint of obtaining a resin composite with excellent heat
resistance.
[0073] The method of removing the chemically modified fine fibers
from the resin composite may be a method of using a resin
solubilizer to extract the resin component, and then carrying out
purification and cleaning to extract the chemically modified fine
fibers in dry form or as an aqueous dispersion, without loss of
their properties. Examples of resin solubilizers include
1,2,4-trichlorobenzene for polyolefins or hexafluoro-2-isopropanol
for 1,2-dichlorobenzene and polyamides, although the resin
solubilizer is not limited to these.
[0074] From the viewpoint of heat resistance of the resin
composite, the number-average fiber diameter of the chemically
modified fine fibers in the resin composite according to one aspect
is 10 nm or greater and less than 1 .mu.m, preferably 10 nm to 800
nm, more preferably 10 nm to 500 nm, even more preferably 20 nm to
300 nm and most preferably 50 nm to 300 nm. The length/diameter
ratio (L/D ratio) of the chemically modified fine fibers, according
to one aspect, is 30 or greater, preferably 100 or greater, more
preferably 200 or greater, even more preferably 300 or greater and
most preferably 500 or greater.
[0075] The weight-average molecular weight (Mw) of the chemically
modified fine fibers of this embodiment, and the chemically
modified fine fibers in the resin composite, is preferably 100,000
or greater and more preferably 200,000 or greater. The ratio
(Mw/Mn) of the weight-average molecular weight and number-average
molecular weight (Mn) of the chemically modified fine fibers of
this embodiment, and the chemically modified fine fibers in the
resin composite, is preferably 6 or lower and more preferably 5.4
or lower. A higher weight-average molecular weight means a lower
number of terminal groups of the cellulose molecules. Since the
ratio (Mw/Mn) of the weight-average molecular weight and
number-average molecular weight represents the width of the
molecular weight distribution, a smaller Mw/Mn means a lower number
of ends of cellulose molecules. Since the ends of the cellulose
molecules are origins for thermal decomposition, a high
weight-average molecular weight is also a more narrow width of
molecular weight distribution, and thus high heat resistance for
the fine cellulose fibers and for the resin composite of the fine
cellulose fibers and resin. The weight-average molecular weight
(Mw) of the chemically modified fine fibers may be 600,000 or
lower, or 500,000 or lower, for example, from the viewpoint of
greater availability of the cellulose starting material. The ratio
(Mw/Mn) of the weight-average molecular weight and number-average
molecular weight (Mn) may be 1.5 or greater or 2 or greater, from
the viewpoint of easier production of the chemically modified fine
fibers. The Mw can be controlled to within this range by selecting
a cellulose starting material having the corresponding Mw, or by
carrying out appropriate physical treatment and/or chemical
treatment of the cellulose starting material. The Mw/Mn ratio can
also be controlled to within this range by selecting a cellulose
starting material having the corresponding Mw/Mn ratio, or by
carrying out appropriate physical treatment and/or chemical
treatment of the cellulose starting material. Examples of physical
treatment for control of both the Mw and Mw/Mn include physical
treatment by application of mechanical force, such as dry grinding
or wet grinding with a microfluidizer, ball mill or disk mill, for
example, or impacting, shearing, sliding or abrasion with a
crusher, homomixer, high-pressure homogenizer or ultrasonic device,
for example, while examples of chemical treatment include
digestion, bleaching, acid treatment and regenerated cellulose
treatment.
[0076] The weight-average molecular weight and number-average
molecular weight of the cellulose referred to here are the values
determined after dissolving the cellulose in lithium chloride-added
N,N-dimethylacetamide, and then performing gel permeation
chromatography with N,N-dimethylacetamide as the solvent.
[0077] The thermal decomposition initiation temperature (T.sub.D)
of the chemically modified fine fibers in the resin composite,
according to one aspect, is 270.degree. C. or higher, preferably
275.degree. C. or higher, more preferably 280.degree. C. or higher
and even more preferably 285.degree. C. or higher, from the
viewpoint of allowing the desired heat resistance and mechanical
strength to be exhibited for on-vehicle purposes. While a higher
thermal decomposition initiation temperature is preferred, it is
also no higher than 320.degree. C. or no higher than 300.degree. C.
from the viewpoint of easier production of the chemically modified
fine fibers.
[0078] For the purpose of the present disclosure, the T.sub.D value
is the value determined from a graph of thermogravimetry (TG)
analysis where the abscissa is temperature and the ordinate is
weight residual ratio %, as shown in the diagram of FIG. 1 (FIG.
1(B) shows a magnified view of FIG. 1(A)). Starting from the weight
of chemically modified fine fibers at 150.degree. C. (with
essentially all of the moisture content removed) (0 wt % weight
reduction) and increasing the temperature, a straight line is
obtained running through the temperature at 1 wt % weight reduction
(T.sub.1%) and the temperature at 2 wt % weight reduction
(T.sub.2%). The temperature at the point of intersection between
this straight line and a horizontal (baseline) running through the
origin at weight reduction 0 wt %, is defined as T.sub.D.
[0079] The 1% weight reduction temperature (T.sub.1%) is the
temperature at 1 wt % weight reduction with the 150.degree. C.
weight as the origin, after continuous temperature increase by the
method for T.sub.D described above.
[0080] The 250.degree. C. weight reduction of the chemically
modified fine fibers in the resin composite (T.sub.250.degree. C.)
is the weight reduction after the chemically modified fine fibers
have been kept for 2 hours at 250.degree. C. under a nitrogen flow,
in TG analysis.
[0081] According to one aspect, the chemically modified fine fibers
of this embodiment have a degree of crystallinity of 60% or higher.
If the degree of crystallinity is within this range, the mechanical
properties of the chemically modified fine fibers themselves
(especially the strength and dimensional stability) will be high,
tending to result in high strength and dimensional stability of the
resin composite comprising the chemically modified fine fibers
dispersed in the resin. A high degree of crystallinity means fewer
amorphous sections, and therefore a high degree of crystallinity is
also preferred from the viewpoint of heat resistance, considering
that amorphous sections can act as origins of deterioration.
[0082] The degree of crystallinity of the chemically modified fine
fibers is preferably 65% or higher, more preferably 70% or higher
and most preferably 80% or higher. Since a higher degree of
crystallinity for the chemically modified fine fibers tends to be
preferable the upper limit is not particularly restricted, but from
the viewpoint of productivity it is preferably an upper limit of
99%.
[0083] When the cellulose is type I cellulose crystals (derived
from natural cellulose), the degree of crystallinity referred to
here is that determined by the following formula, from the
diffraction pattern (20/deg.=10 to 30) obtained by measurement of
the sample by wide-angle X-ray diffraction, based on the Segal
method.
Degree of
crystallinity(%)=[I.sub.(200)-I.sub.(amorphous)]/I.sub.(200).times.100
I.sub.(200): Diffraction peak intensity at 200 plane
(2.theta.=22.5.degree.) of type I cellulose crystal
I.sub.(amorphous): Amorphous halo peak intensity for type I
cellulose crystal, peak intensity at angle of 4.5.degree. lower
than diffraction angle at 200 plane (2.theta.=18.0.degree.).
[0084] When the cellulose is type II cellulose crystals (derived
from regenerated cellulose), the degree of crystallinity is
determined by the following formula, from the absolute peak
intensity h0 at 20=12.6.degree. attributed to the (110) plane peak
of the type II cellulose crystal, and the peak intensity h1 from
the baseline for the plane spacing, in wide-angle X-ray
diffraction.
Degree of crystallinity(%)=h1/h0.times.100
[0085] The known crystalline forms of cellulose include type I,
type II, type III and type IV, among which type I and type II are
most commonly used, whereas type III and type IV are not commonly
used on an industrial scale but have been obtained on a laboratory
scale. The chemically modified fine fibers are preferably
chemically modified fine fibers containing type I cellulose
crystals or type II cellulose crystals, for relatively high
mobility in terms of structure and to obtain a resin composite with
a lower linear coefficient of thermal expansion and more excellent
strength and elongation when subjected to stretching or bending
deformation, by dispersion of the chemically modified fine fibers
in the resin, and more preferably the chemically modified fine
fibers contain type I cellulose crystals and have a degree of
crystallinity of 60% or higher.
[0086] The chemically modified fine fibers of this embodiment have
the hydroxyl groups of the cellulose molecules on the surface of
the fine cellulose fibers chemically modified by a cellulose
modifying agent. The chemical modification is preferably
esterification and more preferably acetylation.
[0087] In the chemically modified fine fibers of this embodiment, a
large amount of acid-insoluble component including lignin may lead
to discoloration by the heat of processing, and therefore the mean
content of the acid-insoluble component in the chemically modified
fine fibers is preferably as low as possible. Specifically, it is
preferably less than 10 mass %, more preferably 8 mass % or lower,
even more preferably 7 mass % or lower, yet more preferably 6 mass
% or lower and most preferably 5 mass % or lower.
[0088] The mean content of the acid-insoluble component is measured
using the Klason method, described in non-patent literature
(Mokushitsu Kagaku Jikken Manual, ed. The Japan Wood Research
Society, pp. 92-97, 2000). The sample is stirred in the sulfuric
acid solution to dissolve the cellulose and alkali-soluble
component, and then filtered with glass fiber filter paper, and the
obtained residue is used as the acid-insoluble component. The
acid-insoluble component content is calculated from the weight of
the acid-insoluble component, and the average of the acid-insoluble
component content calculated for three samples is recorded as the
mean content of the acid-insoluble component.
[0089] The mean content for the acid-insoluble component in the
chemically modified fine fibers of this embodiment can be
calculated from the mean content for the acid-insoluble component
in the cellulose starting material used for production of the
chemically modified fine fibers.
[0090] The mean content for the acid-insoluble component with
respect to the specific surface area of the chemically modified
fine fibers is especially important in terms of the relationship
between the acid-insoluble component and the dynamic properties of
the resin composite. Specifically, a low abundance of
acid-insoluble component at the interface between the cellulose
fiber surfaces and the resin helps to avoid loss of the dynamic
properties of the resin composite that is reinforced by the
chemically modified fine fibers.
[0091] The mean content for the acid-insoluble component per unit
specific surface area of the chemically modified fine fibers is
preferably 1.0 mass %g/m.sup.2 or lower, more preferably 0.6 mass
%g/m.sup.2 or lower, even more preferably 0.5 mass %g/m.sup.2 or
lower, even more preferably 0.4 mass %g/m.sup.2 or lower and most
preferably 0.2 mass %g/m.sup.2 or lower. It is preferred to have a
lower mean content for the acid-insoluble component, and more
preferably it is 0 mass %g/m.sup.2. The specific surface area of
the chemically modified fine fibers can be calculated as the BET
specific surface area obtained using a specific surface area/pore
distribution measuring apparatus (by Quantachrome Instruments) with
the program of the apparatus, after measuring the nitrogen gas
adsorption at the boiling point of liquid nitrogen at five points
(multipoint method) in a relative vapor pressure (P/P.sub.0) range
of 0.05 to 0.2, for a porous sheet sample of the chemically
modified fine fibers.
[0092] According to one aspect, the alkali-soluble portion content
of the chemically modified fine fibers is 12 mass % or lower,
preferably 11 mass % or lower and even more preferably 8 mass % or
lower. The alkali-soluble portion for the present disclosure also
encompasses n-cellulose and .gamma.-cellulose, in addition to
hemicellulose. The alkali-soluble portion is understood by those
skilled in the art to consist of the components that are obtained
as the alkali-soluble portion of holocellulose (that is, the
components other than .alpha.-cellulose in the holocellulose), upon
solvent extraction and chlorine treatment of a plant (such as
wood). Since the alkali-soluble portion consists of hydroxyl
group-containing polysaccharides with poor heat resistance, which
can lead to inconveniences such as decomposition when subjected to
heat, yellowing due to heat aging and reduced strength of the
cellulose fibers, it is preferred to have a lower alkali-soluble
portion content in the chemically modified fine fibers. The
alkali-soluble portion content in the chemically modified fine
fibers is most preferably 0 mass %, but it may be 3 mass % or
greater or 6 mass % or greater from the viewpoint of easier
availability of the cellulose starting material.
[0093] The alkali-soluble portion content can be determined by a
method described in non-patent literature (Mokushitsu Kagaku Jikken
Manual, ed. The Japan Wood Research Society, pp. 92-97, 2000),
subtracting the .alpha.-cellulose content from the holocellulose
content (Wise method). The alkali-soluble portion content in the
chemically modified fine fibers will usually be essentially the
same as the alkali-soluble portion content in the cellulose
starting material used for production of the chemically modified
fine fibers (that is, it may be assumed that there is essentially
no selective removal of the alkali-soluble portion under ordinary
conditions for chemical modification (typically weakly acidic to
neutral pH)). According to one aspect, the value of the
alkali-soluble portion content of the cellulose starting material
may be considered to be the alkali-soluble portion content in the
chemically modified fine fibers.
[0094] The chemically modified fine fibers of this embodiment, and
their production method, as well as the resin composite and its
production method, will now be described.
[0095] The cellulose fibers used as starting material for the
chemically modified fine fibers (also referred to as "cellulose
starting material) may be natural cellulose or regenerated
cellulose. Natural cellulose includes wood pulp obtained from wood
sources (broadleaf trees or conifers), nonwood pulp obtained from
non-wood sources (cotton, bamboo, hemp, bagasse, kenaf, cotton
linter, sisal and straw), and cellulose fiber aggregates obtained
from sources such as animals (such as sea squirts) and algae,
microbes (such as acetic acid bacteria) and microbial products.
Regenerated cellulose for use may be cut yarn of regenerated
cellulose fibers (such as viscose, cupra and Tencel), cut yarn of
cellulose derivative fibers, and superfine yarn of regenerated
cellulose or cellulose derivatives, obtained by electrospinning
methods. These starting materials may have their fiber diameters,
fiber lengths or fibrilization degrees adjusted by beating,
fibrilization or micronization with mechanical force using a
grinder or refiner, or they may be subjected to bleaching and
purification with chemicals, or their non-cellulose contents such
as lignin or hemicellulose may also be adjusted, as necessary.
[0096] The content of acid-insoluble components (especially lignin)
in the cellulose starting material is preferably as low as
possible. The modifying agent used for chemical modification of the
fine cellulose fibers is consumed by secondary reaction with the
acid-insoluble component, often resulting in residue of the
secondary reaction products in the fine cellulose fibers after
chemical modification. This lowers production process yield and
hampers quality control, and also causes yellowing by heat during
production of the resin composite. From this viewpoint, the content
of the acid-insoluble component in the cellulose starting material
is preferably less than 10 mass %, more preferably 8 mass % or
lower, even more preferably 7 mass % or lower, yet more preferably
6 mass % or lower and most preferably 5 mass % or lower. The
content of the acid-insoluble component in the cellulose starting
material is most preferably 0 mass %, but it may be 1 mass % or
greater, greater or 2 mass % or greater, 3 mass % or greater or 4
mass % or greater, from the viewpoint of easier availability of the
cellulose starting material.
[0097] The content of the alkali-soluble portion (especially
hemicellulose) in the cellulose starting material is preferably as
low as possible. The modifying agent used for chemical modification
of the fine cellulose fibers is consumed by secondary reaction with
the alkali-soluble portion, often resulting in residue of the
secondary reaction products in the fine cellulose fibers after
chemical modification. This lowers production process yield and
hampers quality control, and also causes yellowing by heat during
production of the resin composite. From this viewpoint, the content
of the alkali-soluble portion (especially hemicellulose) in the
cellulose starting material is preferably 13 mass % or lower, more
preferably 12 mass % or lower, even more preferably 11 mass % or
lower, yet more preferably 8 mass % or lower and most preferably 5
mass % or lower. The content of the alkali-soluble portion
(especially hemicellulose) in the cellulose starting material is
most preferably 0 mass %, but it may be 3 mass % or greater or 6
mass % or greater from the viewpoint of easier availability of the
cellulose starting material.
[0098] The modifying agent used may be a compound that reacts with
the hydroxyl groups of cellulose, and esterifying agents,
etherifying agents and silylating agents may be mentioned.
Esterifying agents are particularly preferred. Preferred
esterifying agents are acid halides, acid anhydrides and vinyl
carboxylate esters.
[0099] An acid halide may be one or more selected from the group
consisting of compounds represented by the following formula
(1).
R1-C(.dbd.O)--X (1)
(In the formula, R1 represents an alkyl group of 1 to 24 carbon
atoms, an alkylene group of 1 to 24 carbon atoms, a cycloalkyl
group of 3 to 24 carbon atoms or an aryl group of 6 to 24 carbon
atoms, and X is Cl, Br or I.) Specific examples of acid halides
include acetyl chloride, acetyl bromide, acetyl iodide, propionyl
chloride, propionyl bromide, propionyl iodide, butyryl chloride,
butyryl bromide, butyryl iodide, benzoyl chloride, benzoyl bromide
and benzoyl iodide, with no limitation to these. Acid chlorides are
preferably used among these from the viewpoint of reactivity and
handleability. For reaction of an acid halide, one or more alkaline
compounds may also be added to neutralize the acidic by-products,
while simultaneously acting as a catalyst. Specific examples of
alkaline compounds include: tertiary amine compounds such as
triethylamine and trimethylamine; and nitrogen-containing aromatic
compounds such as pyridine and dimethylaminopyridine; with no
limitation to these.
[0100] Any suitable acid anhydride may be used as an acid
anhydride. Examples include saturated aliphatic monocarboxylic
anhydrides of acetic acid, propionic acid, (iso)butyric acid and
valeric acid; unsaturated aliphatic monocarboxylic anhydrides of
(meth)acrylic acid and oleic acid; alicyclic monocarboxylic
anhydrides of cyclohexanecarboxylic acid and tetrahydrobenzoic
acid; aromatic monocarboxylic anhydrides of benzoic acid and
4-methylbenzoic acid; dibasic carboxylic anhydrides, for example:
saturated aliphatic dicarboxylic acid anhydrides such as succinic
anhydride and adipic anhydride, unsaturated aliphatic dicarboxylic
anhydrides such as maleic anhydride and itaconic anhydride,
alicyclic dicarboxylic acid anhydrides such as
1-cyclohexene-1,2-dicarboxylic anhydride, hexahydrophthalic
anhydride and methyltetrahydrophthalic anhydride, and aromatic
dicarboxylic anhydrides such as phthalic anhydride and naphthalic
anhydride; and tribasic or greater polybasic carboxylic anhydrides,
for example: polycarboxylic acid (anhydrides) such as trimellitic
anhydride and pyromellitic anhydride. The catalyst added for
reaction of an acid anhydride may be one or more acidic compounds
such as sulfuric acid, hydrochloric acid or phosphoric acid, or
Lewis acids such as metal chlorides or metal triflates, or alkaline
compounds such as triethylamine or pyridine.
[0101] Preferred vinyl carboxylate esters are vinyl carboxylate
esters represented by the following formula (2):
R--COO--CH.dbd.CH.sub.2: formula (2)
{where R is an alkyl group of 1 to 24 carbon atoms, an alkylene
group of 1 to 24 carbon atoms, a cycloalkyl group of 3 to 24 carbon
atoms or an aryl group of 6 to 24 carbon atoms}. Vinyl carboxylate
esters are more preferably one or more selected from the group
consisting of vinyl acetate, vinyl propionate, vinyl butyrate,
vinyl caproate, vinyl cyclohexanecarboxylate, vinyl caprylate,
vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate,
vinyl stearate, vinyl pivalate, vinyl ocrylate, divinyl adipate,
vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl
ocrylate, vinyl benzoate and vinyl cinnamate. During esterification
reaction with a vinyl carboxylate ester, one or more catalysts may
be added that are selected from the group consisting of alkali
metal hydroxides, alkaline earth metal hydroxides, primary to
tertiary amines, quaternary ammonium salts, imidazole and its
derivatives, pyridine and its derivatives, and alkoxides.
[0102] Alkali metal hydroxides and alkaline earth metal hydroxides
include sodium hydroxide, potassium hydroxide, lithium hydroxide,
calcium hydroxide and barium hydroxide.
[0103] Primary to tertiary amines are primary amines, secondary
amines and tertiary amines, specific examples of which include
ethylenediamine, diethylamine, proline,
N,N,N',N'-tetramethylethylenediamine,
N,N,N',N'-tetramethyl-1,3-propanediamine,
N,N,N',N'-tetramethyl-1,6-hexanediamine,
tris(3-dimethylaminopropyl)amine, N,N-dimethylcyclohexylamine and
triethylamine.
[0104] Imidazole and its derivatives include 1-methylimidazole,
3-aminopropylimidazole and carbonyldiimidazole.
[0105] Pyridine and its derivatives include
N,N-dimethyl-4-aminopyridine and picoline.
[0106] Alkoxides include sodium methoxide, sodium ethoxide and
potassium-t-butoxide.
[0107] Particularly preferred among these esterification reactants
are one or more selected from the group consisting of acetic
anhydride, propionic anhydride, butyric anhydride, vinyl acetate,
vinyl propionate and vinyl butyrate, among which acetic anhydride
and vinyl acetate are especially preferred from the viewpoint of
reaction efficiency.
[0108] According to one aspect, the chemically modified fine
cellulose fibers can be obtained by defibrating a cellulose
starting material, having a weight-average molecular weight (Mw) of
100,000 or greater, a ratio (Mw/Mn) of weight-average molecular
weight (Mw) and number-average molecular weight (Mn) of 6 or lower
and an alkali-soluble portion content of 12 mass % or lower, in a
dispersion containing an aprotic solvent, to obtain fine cellulose
fibers, or adding a solution containing a modifying agent to the
dispersion to modify the fine cellulose fibers, and the obtained
chemically modified fine fibers may have a thermal decomposition
initiation temperature (T.sub.D) of 270.degree. C. or higher, a
number-average fiber diameter of 10 nm or greater and less than 1
.mu.m and a degree of crystallinity of 60% or higher. Chemical
modification after preparation of fine cellulose fibers by
defibrating is advantageous from the viewpoint of lowering the
coefficient of variation of the DS non-uniformity ratio
(DSs/DSt).
[0109] The method for reducing the maximum fiber diameter in order
to convert the cellulose starting material to fine cellulose fibers
is not particularly restricted, but it is preferred for the
defibrating treatment conditions (creation of the shear field or
the size of the shear field) to be as efficient as possible. In
particular, a defibrating solution containing an aprotic solvent is
impregnated with a cellulose starting material with a cellulose
purity of 85 mass % or greater, and swelling of the cellulose is
induced in a short period of time, while merely applying the energy
of a small degree of stirring and shear for micronization of the
cellulose. Also, a cellulose modifying agent may be added
immediately after defibrating, to obtain chemically modified fine
fibers. This method is preferred from the viewpoint of production
efficiency and refining efficiency (i.e. the high purity of the
chemically modified fine fibers), as well as the physical
properties of the resin composite.
[0110] The aprotic solvent may be an alkyl sulfoxide, an alkylamide
or pyrrolidone, for example. Any of these solvents may be used
alone or in combinations of two or more.
[0111] Examples of alkyl sulfoxides include di-C1-4 alkyl
sulfoxides such as dimethyl sulfoxide (DMSO), methylethyl sulfoxide
and diethyl sulfoxide.
[0112] Examples of alkylamides include N,N-di-C1-4 alkylformamides
such as N,N-dimethylformamide (DMF) and N,N-diethylformamide; and
N,N-di-C1-4 alkylacetamides such as N,N-dimethylacetamide (DMAc)
and N,N-diethylacetamide.
[0113] Examples of pyrrolidones include pyrrolidones such as
2-pyrrolidone and 3-pyrrolidone; and N--C1-4 alkylpyrrolidones such
as N-methyl-2-pyrrolidone (NMP).
[0114] Any of these aprotic solvents may be used alone or in
combinations of two or more. Among these aprotic solvents using
DMSO (29.8), DMF (26.6), DMAc (27.8) and NMP (27.3) (the numerals
in parentheses indicating the donor numbers), and especially DMSO,
allows chemically modified fine fibers with a high thermal
decomposition initiation temperature to be more efficiently
produced. While the action mechanism for this is not completely
understood, it is theorized to be due to homogeneous microswelling
of the cellulose starting material in the aprotic solvent.
[0115] When the cellulose starting material for the fine cellulose
fibers swells in the aprotic solvent, the aprotic solvent rapidly
permeates the fibrils composing the starting material and swells
them, such that the microfibrils are converted to a fine defibrated
state. After this state has been created, chemical modification is
carried out to promote chemical modification in a homogeneous
manner throughout all of the microfilaments, by which, presumably,
high heat resistance is obtained. In addition, the microfibrillated
chemically modified fine fibers maintain a high degree of
crystallinity, and allow high mechanical properties and excellent
dimensional stability (especially a very low linear coefficient of
thermal expansion) to be obtained when composited with resins.
[0116] On the other hand, when fine cellulose fibers produced by
defibrating in water or a protic solvent have been chemically
modified by replacement with an aprotic solvent, the improvement in
heat resistance by the chemical modification is somewhat
attenuated. While the action mechanism for this is not completely
understood, it is conjectured that the high liquid-absorbing
property of cellulose hampers complete replacement to the aprotic
solvent, and therefore homogeneous chemical modification does not
proceed due to the residual water or protic solvent.
[0117] According to a preferred aspect, the aprotic solvent is
dimethyl sulfoxide, and the modifying agent is vinyl acetate or
acetic anhydride. From the viewpoint of inhibiting yellowing of the
chemically modified fine fibers or resin composite and reducing
variation in chemical modification, the ionic liquid in the
dispersion is preferably at a content of less than 20 mass %, more
preferably it is essentially absent (specifically, 1 mass % or
lower), and most preferably it is completely absent. In addition,
sulfuric acid is preferably essentially absent (specifically, 1
mass % or lower), and more preferably it is completely absent, in
the dispersion.
[0118] The micronized (defibrated) and chemically modified
microfilaments may be prepared using an apparatus that applies
impact shearing, such as a planetary ball mill or bead mill, an
apparatus that applies a rotating shear field that induces
fibrillation of cellulose, such as a disc refiner or grinder, or an
apparatus that can carry out functions of kneading, agitation and
dispersion in a highly efficient manner, such as any of various
types of kneaders or planetary mixers, or a rotary homogenizing
mixer, with no limitation to these.
[0119] In the attenuated total reflection infrared absorption
spectrum of the chemically modified fine fibers, the peak locations
of the absorption bands vary depending on the type of chemically
modified groups. Based on variation in the peak locations it is
possible to determine on which absorption bands the peaks are
based, allowing identification of modifying groups. It is also
possible to calculate the modification rate from the peak intensity
ratio of peaks attributable to the modifying groups and peaks
attributable to the cellulose backbone.
[0120] For example, if the modifying group is an acyl group, the
peak of the absorption band for the acyl group C.dbd.O appears at
1730 cm.sup.-1, the peak of the absorption band for cellulose
backbone chain C--H groups appears at 1370 cm.sup.-1, and the peak
of the absorption band for cellulose backbone chain C--O groups
appears at 1030 cm.sup.-1 (see FIG. 2).
[0121] When the chemically modified groups of the chemically
modified fine fibers are acyl groups, the degree of modification
(modification rate) (IR index 1370), as defined by the ratio of the
peak intensity of the absorption band of the chemically modified
groups (peak height of absorption band for acyl C.dbd.O groups)
with respect to the peak intensity (height) of the absorption band
for cellulose backbone chain C--H groups (peak height of absorption
band for chemically modified groups/peak height of absorption band
for cellulose backbone chain C--H groups), in the attenuated total
reflection infrared absorption spectrum, is preferably 0.28 to 1.8.
If the IR index 1370 is 0.28 or greater, it will be possible to
obtain a resin composite containing chemically modified fine fibers
with a high thermal decomposition initiation temperature. If it is
1.8 or lower, unmodified cellulose backbone will remain in the
chemically modified fine fibers, making it possible to obtain a
resin composite containing chemically modified fine fibers which
exhibits both the high tensile strength and dimensional stability
of the cellulose and the high thermal decomposition initiation
temperature due to chemical modification. The IR index 1370 is more
preferably 0.44 or greater, even more preferably 0.50 or greater,
yet more preferably 0.56 or greater, especially preferably 0.77 or
greater and most preferably 0.87 or greater, and more preferably
1.68 or lower, even more preferably 1.50 or lower, yet more
preferably 1.31 or lower and most preferably 1.17 or lower.
[0122] The degree of modification (modification rate) (IR index
1030), as defined by the ratio of the peak intensity of the
absorption band for the chemically modified groups (peak height of
absorption band for acyl C.dbd.O groups) with respect to the peak
intensity (height) of the absorption band for cellulose backbone
chain C--O groups (peak height of absorption band for chemically
modified groups/peak height of absorption band for cellulose
backbone chain C--O groups), in the attenuated total reflection
infrared absorption spectrum, is preferably 0.024 to 0.48. If the
IR index 1030 is 0.024 or greater, it will be possible to obtain a
resin composite containing chemically modified fine fibers with a
high thermal decomposition initiation temperature. If it is 0.48 or
lower, unmodified cellulose backbone will remain in the chemically
modified fine fibers, making it possible to obtain a resin
composite containing chemically modified fine fibers, which
exhibits both the high tensile strength and dimensional stability
of the cellulose and the high thermal decomposition initiation
temperature due to chemical modification. The IR index 1030 is more
preferably 0.048 or greater, even more preferably 0.061 or greater,
yet more preferably 0.073 or greater, especially preferably 0.13 or
greater and most preferably 0.15 or greater, and more preferably
0.44 or lower, even more preferably 0.36 or lower, yet more
preferably 0.30 or lower and most preferably 0.25 or lower.
[0123] The peak heights at 1730 cm.sup.-1, 1370 cm.sup.-1 and 1030
cm.sup.-1 used for calculation of the IR index 1370 and IR index
1030 are read off in the following manner. For the peak intensity
at 1730 cm.sup.-1, a baseline connecting locations near 1550
cm.sup.-1 and near 1850 cm.sup.-1 without other peaks is drawn with
a straight line, and the height of the baseline at 1730 cm.sup.-1
is subtracted from the peak height at 1730 cm.sup.-1 as the read
value.
[0124] For the peak intensity at 1370 cm.sup.-1, a baseline
connecting locations near 820 cm.sup.-1 and near 1530 cm.sup.-1
without other peaks is drawn with a straight line, and the height
of the baseline at 1370 cm.sup.-1 is subtracted from the peak
height at 1370 cm.sup.-1 as the read value.
[0125] For the peak intensity at 1030 cm.sup.-1, a baseline
connecting locations near 820 cm.sup.-1 and near 1530 cm.sup.-1
without other peaks is drawn with a straight line, and the height
of the baseline at 1030 cm.sup.-1 subtracted from the peak height
at 1030 cm.sup.-1 as the read value.
[0126] The IR index 1030 can be calculated as the average degree of
substitution of hydroxyl groups of the chemically modified fine
fibers according to the following formula (the average number of
hydroxyl groups replaced per glucose as the basic structural unit
of cellulose, also known as DS).
DS=4.13.times.IR Index 1030
[0127] The average degree of substitution is preferably 0.1 to 2.0.
If DS is 0.1 or greater, it will be possible to obtain a resin
composite containing chemically modified fine fibers with a high
thermal decomposition initiation temperature. If it is 2.0 or
lower, unmodified cellulose backbone will remain in the chemically
modified fine fibers, making it possible to obtain a resin
composite containing chemically modified fine fibers, which
exhibits both the high tensile strength and dimensional stability
of the cellulose and the high thermal decomposition initiation
temperature due to chemical modification. DS is more preferably 0.2
or greater, more preferably 0.25 or greater, even more preferably
0.3 or greater and most preferably 0.5 or greater, and preferably
1.8 or lower, more preferably 1.5 or lower, even more preferably
1.2 or lower and most preferably 1.0 or lower.
[0128] For chemically modified fine fibers of this embodiment, the
DS non-uniformity ratio (DSs/DSt), defined as the ratio of the
degree of modification (DSs) of the fiber surfaces with respect to
the degree of modification (DSt) of the entire fibers, is
preferably 1.05 or greater. A larger value for the DS
non-uniformity ratio corresponds to a more non-uniform structure
similar to a sheath-core structure (that is, while the fiber
surfaces are highly chemically modified, the center sections of the
fibers maintain the original largely unmodified cellulose
structure), which helps to provide the high tensile strength and
dimensional stability of cellulose while improving the affinity
with the resin when used in a resin composite and improving the
dimensional stability of the resin composite. The DS non-uniformity
ratio is preferably 1.1 or greater, more preferably 1.2 or greater
and even more preferably 1.5 or greater, while from the viewpoint
of ease of production of the chemically modified fine fibers, it is
preferably 6 or lower, more preferably 4 or lower and even more
preferably 3 or lower.
[0129] The values of DSs and DSt vary depending on the degree of
modification of the chemically modified fine fibers, but for
example, the preferred range for DSs is 0.5 to 3.0 and the
preferred range for DSt is 0.1 to 2.0.
[0130] In the chemically modified fine fibers of this embodiment, a
lower coefficient of variation (CV) of the DS non-uniformity ratio
is preferred because it corresponds to less variation in the
physical properties of the resin composite. It is preferably 50% or
lower, more preferably 40% or lower, even more preferably 30% or
lower and most preferably 20% or lower. When producing the
chemically modified fine fibers, the coefficient of variation can
be lowered by a method of first defibrating the cellulose starting
material and then carrying out the chemical modification
(sequential method). It can be increased, on the other hand, by a
method of simultaneously defibrating and chemically modifying the
cellulose starting material (simultaneous method). While the action
mechanism for this is not completely understood, it is believed
that in the simultaneous method, chemical modification proceeds
further with the narrow fibers produced by initial defibrating, and
the chemical modification causes reduction in hydrogen bonding
between the cellulose microfibrils, thus promoting further
defibration and resulting in a larger coefficient of variation of
the DS non-uniformity ratio.
[0131] The coefficient of variation (CV) of the DS non-uniformity
ratio is obtained by sampling 100 g of the aqueous dispersion of
the chemically modified fine fibers (solid content: 10 mass %),
using 10 g each of the freeze-shattered substance as measuring
samples, calculating the DS non-uniformity ratio from DSt and DSs
for the 10 samples, and calculating the coefficient of variation
from the standard deviation (a) and arithmetic mean (.mu.) of the
DS non-uniformity ratio between the 10 samples.
[0132] DS Non-uniformity ratio=DSs/DSt
Coefficient of variation(%)=standard deviation .sigma./arithmetic
mean .mu..times.100
[0133] The method of calculating DSt may be subjecting the
freeze-shattered chemically modified fine fibers to .sup.13C solid
NMR measurement, according to the following formula using the area
intensity (Inf) of the signal attributed to one carbon atom of the
modifying group, with respect to the total area intensity (Inp) of
the signals attributed to C1-C6 carbons of the pyranose rings of
cellulose, appearing in the range of 50 ppm to 110 ppm.
DSt=(Inf).times.6/(Inp)
[0134] For example, when the modifying group is acetyl, the signal
at 23 ppm attributed to --CH.sub.3 may be used.
[0135] The conditions in the .sup.13C solid NMR measurement may be
as follows, for example.
Apparatus: Bruker Biospin Avance 500WB
Frequency: 125.77 MHz
[0136] Measuring method: DD/MAS Latency time: 75 sec NMR sample
tube:4 mm.phi. Number of scans: 640 (.about.14 hr)
MAS: 14,500 Hz
[0137] Chemical shift reference: glycine (external reference:
176.03 ppm)
[0138] As the method of calculating DSs, a powder sample of the
chemically modified fine fibers used for .sup.13C solid NMR
measurement is placed on a 2.5 mm.phi. dish-shaped sample stand,
the surface is pressed flat, and measurement is performed by X-ray
photoelectron spectroscopy (XPS). The XPS spectrum reflects the
structural elements and chemically bonded state of the sample
surface layer alone (typically about several nanometers). The
obtained Cls spectrum is analyzed by peak separation, and
calculation is performed by the following formula using the area
intensity (Ixf) of the peak attributed to one carbon atom of the
modifying group, with respect to the area intensity (Ixp) of the
peak attributed to the C2-C6 carbons of the pyranose rings of
cellulose (289 eV, C--C bond).
DSs=(Ixf).times.5/(Ixp)
[0139] For example, when the modifying group is acetyl, the Cls
spectrum is analyzed by peak separation at 285 eV, 286 eV, 288 eV
and 289 eV, and the peak at 289 eV may be used for Ixp while the
peak due to acetyl group O--C.dbd.O bonds (286 eV) may be used for
Ixf.
[0140] The conditions for XPS measurement are the following, for
example.
Device: VersaProbe II by Ulvac-Phi, Inc.
[0141] Excitation source: mono. AlKa 15 kV.times.3.33 mA Analysis
size: .about.200 .mu.m.phi. Photoelectron take-off angle:
45.degree. Capture range Narrow scan: C 1s, O 1s
Pass Energy: 23.5 eV
[0142] For a resin composite according to a typical aspect, the
resin forms a matrix, with the chemically modified fine fibers
dispersed in the resin.
[0143] According to one aspect, the resin composite can be produced
by a production method comprising a step of defibrating cellulose
in a dispersion containing a cellulose starting material at a
purity of 85 mass % or greater, and an aprotic solvent, to obtain
fine cellulose fibers, and then adding a solution containing a
modifying agent to the dispersion to modify the fine cellulose
fibers, thereby obtaining chemically modified fine fibers having a
thermal decomposition initiation temperature (T.sub.D) of
270.degree. C. or higher, a number-average fiber diameter of 10 nm
or greater and less than 1 .mu.m (and with a degree of
crystallinity of 60% or higher, according to one aspect), and a
step of mixing the chemically modified fine fibers with a resin.
Thus, the method of chemical modification after preparation of fine
cellulose fibers by defibrating is advantageous from the viewpoint
of lowering the coefficient of variation of the DS non-uniformity
ratio (DSs/DSt). From the viewpoint of inhibiting yellowing of the
chemically modified fine fibers or resin composite and reducing
variation in chemical modification, the ionic liquid in the
dispersion is preferably at a content of less than 20 mass %, more
preferably it is essentially absent (specifically, 1 mass % or
lower), and most preferably it is completely absent. In addition,
sulfuric acid is preferably essentially absent (specifically, 1
mass % or lower), and more preferably it is completely absent, in
the dispersion.
[0144] Using a cellulose starting material with a purity
(.alpha.-cellulose content) of 85 mass % or greater, as the
starting material for the type I cellulose crystals, is preferred
from the viewpoint of the production efficiency and refining
efficiency of the chemically modified fine fibers (that is, the
purity of the chemically modified fine fibers), and the physical
properties when composited with a resin. The cellulose purity is
more preferably 90 mass % or greater and even more preferably 95
mass % or greater.
[0145] The cellulose purity can be determined by a method for
measuring .alpha.-cellulose content described in non-patent
literature (Mokushitsu Kagaku Jikken Manual, ed. The Japan Wood
Research Society, pp. 92-97, 2000).
[0146] The starting material for the type II cellulose crystals may
exhibit a low cellulose purity when using a method of measuring the
.alpha.-cellulose content (the .alpha.-cellulose content measuring
method is a method originally developed for analysis of type I
cellulose crystal starting materials such as wood). However, a
starting material for type II cellulose crystals is a product
processed and produced using type I cellulose crystals as starting
material (such as viscose rayon, cupra, lyocell or mercerized
cellulose), the original cellulose purity is high. The type II
cellulose crystal starting material is therefore suitable as a
starting material for the chemically modified fine fibers of the
invention even with a cellulose purity of less than 85 mass %.
[0147] The resin composite may also include cellulose whiskers in
addition to the chemically modified fine fibers. Cellulose whiskers
improve the dispersibility of the chemically modified fine fibers
by admixture with the chemically modified fine fibers, resulting in
improved dynamic properties of the resin composite. The major
property of cellulose whiskers is L/D=1 to <30, preferably L/D=1
to 20 and more preferably L/D=1 to 10, without being limited to
this range. The degree of crystallinity of the cellulose whiskers
is 70% or higher, for example, and is preferably 80% or higher. The
degree of polymerization of the cellulose whiskers is 600 or lower
and preferably 300 or lower. The cellulose whiskers used may be a
commercially available product, and for example, it may be obtained
by cutting wood pulp and promoting hydrolysis in an aqueous
hydrochloric acid solution.
[0148] Using a dispersion stabilizer that has the function of
stably dispersing the chemically modified fine fibers, together
with the chemically modified fine fibers, to increase and control
the dispersed state of the chemically modified fine fibers in the
resin, is effective for improving the mechanical properties of the
resin composite. The content ratio of the dispersion stabilizer in
the resin composite is appropriately selected in a range that does
not interfere with the desired effect of the invention, and for
example, it may be 0.01 to 50 mass %, 0.1 to 30 mass %, 0.5 to 20
mass % or 1.0 to 10 mass %.
[0149] According to a more preferred aspect, the chemically
modified fine fibers are dispersed in the resin composite in the
form of a cellulose dispersion containing a dispersion stabilizer.
The chemically modified fine fiber content in the cellulose
dispersion is preferably 10 to 99 mass %, more preferably 10 to 90
mass % and even more preferably 50 to 90 mass %. When the
chemically modified fine fiber content is higher, the dispersion of
the chemically modified fine fibers is poor and the mechanical
properties are insufficiently improved, and when it is lower, the
dispersion stabilizer causes the resin to become too sparse,
resulting in poor mechanical properties. A portion of the
dispersion stabilizer may elute from the cellulose dispersion
during production of the resin composite, and may diffuse in the
matrix resin in the resin composite.
[0150] The dispersion stabilizer may be one or more selected from
the group consisting of surfactants, organic compounds with boiling
points of 160.degree. C. or higher, and resins having chemical
structures that are able to highly disperse the chemically modified
fine fibers, and preferably one or more selected from the group
consisting of surfactants and organic compounds with boiling points
of 160.degree. C. or higher.
[0151] The surfactant may be one having a chemical structure in
which a site with a hydrophilic substituent and a site with a
hydrophobic substituent are covalently bonded, and any ones
utilized for a variety of purposes including consumption and
industrial use may be used. The following, for example, may be
used, either alone or in combinations of two or more.
[0152] The surfactant used may be any anionic surfactant, nonionic
surfactant, zwitterionic surfactant or cationic surfactant, but
from the viewpoint of affinity with cellulose, an anionic
surfactant or nonionic surfactant is preferred, and a nonionic
surfactant is more preferred.
[0153] Among the above, from the viewpoint of affinity with
cellulose, surfactants having polyoxyethylene chains, carboxyl
groups or hydroxyl groups as hydrophilic groups are preferred,
polyoxyethylene-based surfactants with polyoxyethylene chains as
hydrophilic groups (polyoxyethylene derivatives) are more
preferred, and nonionic polyoxyethylene derivatives are even more
preferred. The polyoxyethylene chain length of a polyoxyethylene
derivative is preferably 3 or greater, more preferably 5 or
greater, even more preferably 10 or greater and most preferably 15
or greater. A longer chain length will increase the affinity with
cellulose, but for balance with the properties desired for the
resin composite (for example, the coating property), it is
preferably no greater than 60, as the upper limit, more preferably
no greater than 50, even more preferably no greater than 40,
especially preferably no greater than 30 and most preferably no
greater than 20.
[0154] Of the aforementioned surfactants, it is especially
preferred to use those with alkyl ether-type, alkylphenyl
ether-type, rosin ester-type, bisphenol A-type,
.beta.-naphthyl-type, styrenated phenyl-type or hydrogenated castor
oil-type hydrophobic groups, because of their high affinity with
resins. The alkyl chain length (the number of carbon atoms
excluding the phenyl group in the case of alkylphenyl) is a carbon
chain of preferably 5 or greater, more preferably 10 or greater,
even more preferably 12 or greater and most preferably 16 or
greater carbon atoms. When the resin is a polyolefin-based resin,
for example, a greater number of carbon atoms of the surfactant
increases affinity with the resin, and therefore while there is no
strict upper limit, the upper limit for the number of carbon atoms
is preferably no more than 30 and more preferably no more than
25.
[0155] Preferred among these hydrophobic groups are those having a
cyclic structure and those having bulk and a polyfunctional
structure. Those with a cyclic structure include alkylphenyl
ether-type, rosin ester-type, bisphenol A-type,
.beta.-naphthyl-type and styrenated phenyl-type groups, and those
with a polyfunctional structure include hydrogenated castor
oil-type groups.
[0156] More particularly preferred among these are rosin ester
types and hydrogenated castor oil types.
[0157] Organic compounds with boiling points of 160.degree. C. or
higher are effective as non-surfactant dispersing media, although
this will depend on the type of resin. Specific examples of such
organic compounds that are effective include high-boiling-point
organic solvents such as liquid paraffin and decalin, when the
resin is a polyolefin-based resin. When the resin is a polar resin
such as a polyamide-based resin or polyacetate-based resin, it is
effective to use the same solvent as the aprotic solvent that may
be used for production of the chemically modified fine fibers, such
as dimethyl sulfoxide, for example.
[0158] The resin composite of this embodiment may also include
other components, namely additives including fine fiber filler
components composed of highly heat-resistant organic polymers other
than chemically modified fine fibers (for example, fibrillated
fibers fine fibers obtained from aramid fibers); compatibilizers;
plasticizers; polysaccharides such as starch and alginic acid;
natural proteins such as gelatin, nikawa and casein; inorganic
compounds such as zeolite, ceramics, talc, silica, metal oxides and
metal powders; coloring agents; perfumes; pigments; flow adjusters;
leveling agents; conductive agents; antistatic agents; ultraviolet
absorbers; ultraviolet dispersing agents; and deodorants. The
content ratio of optional additives in the resin composite is
appropriately selected in a range that does not interfere with the
desired effect of the invention, and for example, it may be 0.01 to
50 mass % or 0.1 to 30 mass %.
[0159] With chemically modified fine fibers in the resin composite,
aggregation by hydrogen bonding will be reduced compared to
unmodified fine cellulose fibers. Thus, in the mixing step for the
chemically modified fine fibers and resin, aggregation between
chemically modified fine fibers is minimized, the chemically
modified fine fibers homogeneously disperse in the resin, and a
fiber-reinforced resin complex containing chemically modified fine
fibers can be obtained that has excellent dynamic properties, heat
resistance, surface smoothness and outer appearance.
[0160] The resin composite containing chemically modified fine
fibers according to this embodiment has a satisfactory balance for
its mechanical properties, including its static properties in
bending testing and dynamic properties in impact testing.
[0161] The resin used in the resin composite of this embodiment may
be a thermoplastic resin, a thermosetting resin and/or a
photocuring resin. The resin may also be an elastomer.
[0162] The content of the resin (matrix resin) in the resin
composite may be 60 to 99.5 mass %, and more preferably 80 to 90
mass %. A resin content of 60 mass % or greater is effective for
exhibiting thermal stability (lower linear coefficient of thermal
expansion, and retaining elasticity at high temperature), while a
resin content of 99.5 mass % or lower will allow functions such as
a high elastic modulus and lower coefficient of thermal expansion
to be imparted to the resin composite.
[0163] When the resin is a thermoplastic resin, the melting point
of the thermoplastic resin may be appropriately selected depending
on the purpose of use of the resin composite. For a resin with a
relatively low melting point (such as a polyolefin-based resin),
for example, the melting point of the thermoplastic resin may be
150.degree. C. to 190.degree. C. or 160.degree. C. to 180.degree.
C., while for a resin with a relatively high melting point (such as
a polyamide-based resin), for example, it may be 220.degree. C. to
350.degree. C. or 230.degree. C. to 320.degree. C.
[0164] The thermoplastic resin may be at least one type selected
from the group consisting of polyolefin-based resins,
polyacetate-based resins, polycarbonate-based resins,
polyamide-based resins, polyester-based resins, polyphenylene
ether-based resins and acrylic-based resins.
[0165] Polyolefin-based resins that are preferred as thermoplastic
resins are polymers obtained by polymerizing olefins (such as
.alpha.-olefins) and/or alkenes as monomer units. Specific examples
of polyolefin-based resins include ethylene-based (co)polymers such
as low-density polyethylene (for example, linear low-density
polyethylene), high-density polyethylene, ultralow-density
polyethylene and ultrahigh molecular weight polyethylene,
polypropylene-based (co)polymers such as polypropylene,
ethylene-propylene copolymer and ethylene-propylene-diene
copolymer, and copolymers with .alpha.-olefins such as ethylene,
including ethylene-acrylic acid copolymer, ethylene-methyl
methacrylate copolymer and ethylene-glycidyl methacrylate
copolymer.
[0166] The most preferred polyolefin-based resin is polypropylene.
Particularly preferred is polypropylene, which has a melt mass-flow
rate (MFR) of 3 g/10 min to 30 g/10 min, as measured at 230.degree.
C. with a load of 21.2 N, according to ISO1133. The lower limit for
MFR is more preferably 5 g/10 min, even more preferably 6 g/10 min
and most preferably 8 g/10 min. The upper limit for MFR is more
preferably 25 g/10 min, even more preferably 20 g/10 min and most
preferably 18 g/10 min. The MFR preferably is not above this upper
limit from the viewpoint of increased toughness of the composition,
and it is preferably not less than the lower limit from the
viewpoint of the flow property of the composition.
[0167] An acid-modified polyolefin-based resin may also be suitably
used in order to increase the affinity with cellulose. The acid may
be appropriately selected from among maleic acid, fumaric acid,
succinic acid, phthalic acid and their anhydrides, and
polycarboxylic acids such as citric acid. Preferred among these are
maleic acid or its anhydride, for an increased modification rate.
While the modification method is not particularly restricted, a
common method involves heating to above the melting point in the
presence of or in the absence of a peroxide, for melt kneading. The
polyolefin resin to be acid-modified may be any of the
aforementioned polyolefin-based resins, but polypropylene is most
suitable for use. The acid-modified polypropylene may be used
alone, but it is preferably used in admixture with a non-modified
polypropylene in order to adjust the modification rate of the
entire resin. The proportion of acid-modified polypropylene with
respect to the total polypropylene is 0.5 mass % to 50 mass %. The
lower limit is more preferably 1 mass %, even more preferably 2
mass %, yet more preferably 3 mass %, even yet more preferably 4
mass % and most preferably 5 mass %. The upper limit is more
preferably 45 mass %, even more preferably 40 mass %, yet more
preferably 35 mass %, even yet more preferably 30 mass % and most
preferably 20 mass %. In order to maintain interfacial strength
between the resin and the cellulose it is preferably higher than
the lower limit, and in order to maintain ductility as a resin it
is preferably lower than the upper limit.
[0168] The melt mass-flow rate (MFR) of the acid-modified
polypropylene as measured at 230.degree. C. with a load of 21.2 N
according to ISO1133 is preferably 50 g/10 min or higher, in order
to increase affinity with the cellulose interface. A more preferred
lower limit is 100 g/10 min, with 150 g/10 min being more preferred
and 200 g/10 min being most preferred. There is no particular upper
limit, and it may be 500 g/10 min in order to maintain mechanical
strength. An MFR within this range will provide an advantage of
residing more easily at the interface between the cellulose and the
resin.
[0169] Examples of preferred polyamide-based resins for the
thermoplastic resin include polyamides obtained by polycondensation
reaction of lactams (such as polyamide 6, polyamide 11 and
polyamide 12), and polyamides obtained by copolymerization of
diamines (such as 1,6-hexanediamine, 2-methyl-1,5-pentanediamine,
1,7-heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine,
2-methyl-1,7-heptanediamine, 1,9-nonanediamine,
2-methyl-1,8-octanediamine, 1,10-decanediamine,
1,11-undecanediamine, 1,12-dodecanediamine and m-xylylenediamine)
and dicarboxylic acids (such as butanedioic acid, pentanedioic
acid, hexanedioic acid, heptanedioic acid, octanedioic acid,
nonanedioic acid, decanedioic acid, benzene-1,2-dicarboxylic acid,
benzene-1,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid,
cyclohexane-1,3-dicarboxylic acid and cyclohexane-1,4-dicarboxylic
acid) (such as polyamide 6,6, polyamide 6,10, polyamide 6,11,
polyamide 6,12, polyamide 6,T, polyamide 6,1, polyamide 9,T,
polyamide 10,T, polyamide 2M5,T, polyamide MXD, 6, polyamide 6,C
and polyamide 2M5,C), as well as copolymers obtained by
copolymerization of these (such as polyamide 6,T/6,I).
[0170] More preferred among these polyamide-based resins are
aliphatic polyamides such as polyamide 6, polyamide 11, polyamide
12, polyamide 6,6, polyamide 6,10, polyamide 6,11 and polyamide
6,12, and alicyclic polyamides such as polyamide 6,C and polyamide
2M5,C.
[0171] For increased heat resistance of the resin composite, the
melting point of the polyamide-based resin is preferably
220.degree. C. or higher, more preferably 230.degree. C. or higher,
even more preferably 240.degree. C. or higher, yet more preferably
245.degree. C. or higher and most preferably 250.degree. C. or
higher, while from the viewpoint of easier production of the resin
composite, the melting point is preferably no higher than
350.degree. C., no higher than 320.degree. C. or no higher than
300.degree. C.
[0172] There are no particular restrictions on the terminal
carboxyl group concentration of the polyamide-based resin, but the
lower limit is preferably 20 .mu.mol/g and more preferably 30
.mu.mol/g. The upper limit for the terminal carboxyl group
concentration is preferably 150 .mu.mol/g, more preferably 100
.mu.mol/g and even more preferably 80 .mu.mol/g.
[0173] In the polyamide-based resin, the ratio of carboxyl terminal
groups with respect to the total terminal groups ([COOH]/[total
terminal groups]) is more preferably 0.30 to 0.95. The lower limit
for the carboxyl terminal group ratio is more preferably 0.35, yet
more preferably 0.40 and most preferably 0.45. The upper limit for
the carboxyl terminal group ratio is more preferably 0.90, yet more
preferably 0.85 and most preferably 0.80. The carboxyl terminal
group ratio is preferably 0.30 or higher from the viewpoint of
dispersibility of the chemically modified fine fibers in the resin
composite, and preferably 0.95 or lower from the viewpoint of the
color tone of the resulting resin composite.
[0174] The method used to adjust the terminal group concentration
of the polyamide-based resin may be a publicly known method. For
example, the method may be addition of a terminal group adjuster
that reacts with the terminal groups, such as a diamine compound,
monoamine compound, dicarboxylic acid compound, monocarboxylic acid
compound, acid anhydride, monoisocyanate, monoacid halide,
monoester or monoalcohol, to the polymerization solution, so as to
result in the prescribed terminal group concentration during
polymerization of the polyamide.
[0175] Examples of terminal group adjusters that react with
terminal amino groups include aliphatic monocarboxylic acids such
as acetic acid, propionic acid, butyric acid, valeric acid, caproic
acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid,
palmitic acid, stearic acid, pivalic acid and isobutyric acid;
alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid;
aromatic monocarboxylic acids such as benzoic acid, toluic acid,
.alpha.-naphthalenecarboxylic acid, .beta.-naphthalenecarboxylic
acid, methylnaphthalenecarboxylic acid and phenylacetic acid; and
mixtures of any selected from among the foregoing. Among these,
from the viewpoint of reactivity, stability of capped ends and
cost, one or more terminal group adjusters selected from the group
consisting of acetic acid, propionic acid, butyric acid, valeric
acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid,
myristic acid, palmitic acid, stearic acid and benzoic acid are
preferred, with acetic acid being most preferred.
[0176] Examples of terminal group adjusters that react with
terminal carboxyl groups include aliphatic monoamines such as
methylamine, ethylamine, propylamine, butylamine, hexylamine,
octylamine, decylamine, stearylamine, dimethylamine, diethylamine,
dipropylamine and dibutylamine; alicyclic monoamines such as
cyclohexylamine and dicyclohexylamine; aromatic monoamines such as
aniline, toluidine, diphenylamine and naphthylamine; and any
mixtures of the foregoing. Among these, from the viewpoint of
reactivity, boiling point, capped end stability and cost, it is
preferred to use one or more terminal group adjusters selected from
the group consisting of butylamine, hexylamine, octylamine,
decylamine, stearylamine, cyclohexylamine and aniline.
[0177] The concentration of the amino terminal groups and carboxyl
terminal groups is preferably determined from the integral of the
characteristic signal corresponding to each terminal group,
according to .sup.1H-NMR, from the viewpoint of precision and
convenience. The recommended method for determining the terminal
group concentration is, specifically, the method described in
Japanese Unexamined Patent Publication HEI No. 7-228775. When this
method is used, heavy trifluoroacetic acid is useful as the
measuring solvent. Also, the number of scans in .sup.1H-NMR must be
at least 300, even with measurement using a device having
sufficient resolving power. Alternatively, the terminal group
concentration can be measured by a titration method such as
described in Japanese Unexamined Patent Publication No.
2003-055549. However, in order to minimize the effects of the mixed
additives and lubricant, quantitation is preferably by
.sup.1H-NMR.
[0178] The intrinsic viscosity [.sub.1] of the polyamide-based
resin, measured in concentrated sulfuric acid at 30.degree. C., is
preferably 0.6 to 2.0 dL/g, more preferably 0.7 to 1.4 dL/g, even
more preferably 0.7 to 1.2 dL/g and most preferably 0.7 to 1.0
dL/g. If the aforementioned polyamide having intrinsic viscosity in
the preferred range, or the particularly preferred range, is used,
it will be possible to provide an effect of drastically increasing
the flow property of the resin composite in the die during
injection molding, and improving the outer appearance of molded
pieces.
[0179] Throughout the present disclosure, "intrinsic viscosity" is
synonymous with the viscosity commonly known as the limiting
viscosity. The specific method for determining the viscosity is a
method in which the .eta.sp/c of several measuring solvents with
different concentrations is measured in 96% concentrated sulfuric
acid under temperature conditions of 30.degree. C., the relational
expression between each .eta.sp/c and the concentration (c) is
derived, and the concentration is extrapolated to zero. The value
extrapolated to zero is the intrinsic viscosity.
[0180] The details are described in Polymer Process Engineering
(Prentice-Hall, Inc 1994), p. 291-294.
[0181] The number of measuring solvents with different
concentrations is preferably at least 4, from the viewpoint of
precision. The concentrations of the recommended measuring
solutions with different viscosities are preferably at least four:
0.05 g/dL, 0.1 g/dL, 0.2 g/dL and 0.4 g/dL.
[0182] Polyester-based resins that are preferred as thermoplastic
resins are one or more selected from among polyethylene
terephthalate (hereunder also referred to simply as "PET"),
polybutylene succinate (a polyester resin composed of an aliphatic
polybasic carboxylic acid and an aliphatic polyol (hereunder also
referred to simply as "unit PBS")), polybutylene succinate adipate
(hereunder also referred to simply as "PBSA"), polybutylene adipate
terephthalate (hereunder also referred to simply as "PBAT"),
polyhydroxyalkanoic acids (polyester resins composed of
3-hydroxyalkanoic acids, hereunder also referred to simply as
"PHA"), polylactic acid (hereunder also referred to simply as
"PLA"), polybutylene terephthalate (hereunder also referred to
simply as "PBT"), polyethylene naphthalate (hereunder also referred
to simply as "PEN") and polyallylates (hereunder also referred to
simply as "PAR").
[0183] Preferred polyester-based resins among these include PET,
PBS, PBSA, PBT and PEN, with PBS, PBSA and PBT being more
preferred.
[0184] The terminal groups of the polyester-based resin can be
freely altered by the monomer ratio during polymerization and/or by
the presence or absence and amount of stabilizer at the ends, and
more preferably the ratio of carboxyl terminal groups with respect
to the total terminal groups of the polyester-based resin
([C001-1]/[total terminal groups]) is 0.30 to 0.95. The lower limit
for the carboxyl terminal group ratio is more preferably 0.35, yet
more preferably 0.40 and most preferably 0.45. The upper limit for
the carboxyl terminal group ratio is more preferably 0.90, yet more
preferably 0.85 and most preferably 0.80. The carboxyl terminal
group ratio is preferably 0.30 or greater from the viewpoint of
dispersibility of the microcellulose in the composition, and it is
preferably no greater than 0.95 from the viewpoint of the color
tone of the obtained composition.
[0185] Polyacetal-based resins preferred as thermoplastic resins
are commonly homopolyacetals obtained from formaldehyde starting
materials and copolyacetals with trioxane as the main monomer and
comprising 1,3-dioxolane as a comonomer component, and although
both of these may be used, copolyacetals are preferably used from
the viewpoint of thermal stability during working. The percentage
of structure due to the comonomer component (for example,
1,3-dioxolane) is more preferably in the range of 0.01 to 4 mol %.
The preferred lower limit for the percentage of structure due to
the comonomer component is 0.05 mol %, more preferably 0.1 mol %
and even more preferably 0.2 mol %. The preferred upper limit is
3.5 mol %, more preferably 3.0 mol %, even more preferably 2.5 mol
% and most preferably 2.3 mol %. The lower limit is preferably in
the range specified above from the viewpoint of thermal stability
during extrusion and during molding, and the upper limit is
preferably in the range specified above from the viewpoint of
mechanical strength.
[0186] Specific examples of thermosetting resins include, but are
not particularly limited to, bisphenol-type epoxy resins such as
bisphenol A-type epoxy resin, bisphenol F-type epoxy resin,
bisphenol S-type epoxy resin, bisphenol E-type epoxy resin,
bisphenol M-type epoxy resin, bisphenol P-type epoxy resin and
bisphenol Z-type epoxy resin, novolac-type epoxy resins such as
bisphenol A-novolac-type epoxy resin, phenol-novolac-type epoxy
resin and cresol-novolac-epoxy resin, biphenyl-type epoxy resins,
biphenylaralkyl-type epoxy resins, arylalkylene-type epoxy resins,
tetraphenylolethane-type epoxy resins, naphthalene-type epoxy
resins, anthracene-type epoxy resins, phenoxy-type epoxy resins,
dicyclopentadiene-type epoxy resins, norbornane-type epoxy resins,
adamantane-type epoxy resins, fluorene-type epoxy resins, glycidyl
methacrylate copolymer-based epoxy resins, cyclohexylmaleimide and
glycidyl methacrylate copolymer epoxy resins, epoxy-modified
polybutadiene rubber derivatives, CTBN-modified epoxy resins,
trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether,
biphenyl-4,4'-diglycidyl ether, 1,6-hexanediol diglycidyl ether,
diglycidyl ethers of ethylene glycol or propylene glycol, sorbitol
polyglycidyl ether, tris(2,3-epoxypropyl) isocyanurate,
triglycidyltris(2-hydroxyethyl) isocyanurate, phenol resins,
including novolac-type phenol resins such as phenol-novolac resin,
cresol-novolac resin and bisphenol A-novolac resin, resol-type
phenol resins such as modified resol phenol resins, oil-modified
resol phenol resins modified with China wood oil, linseed oil or
walnut oil, phenoxy resins, urea resins, triazine ring-containing
resins such as melamine resins, unsaturated polyester resins,
bismaleimide resins, diallyl phthalate resins, silicone resins,
benzoxazine ring-containing resins, norbornane-based resins,
cyanate resins, isocyanate resins, urethane resins,
benzocyclobutene resins, maleimide resins, bismaleimidetriazine
resins, polyazomethine resins, and thermosetting polyimides.
[0187] These thermosetting resins may be used alone, or two or more
different types may be used as blends. For a blend, the blend ratio
may be appropriately set depending on the particular use.
[0188] Specific examples of photocuring resins include, but are not
particularly limited to, common publicly known (meth)acrylate
resins, vinyl resins and epoxy resins. These are largely classified
depending on the reaction mechanism, either as radical reactive
types wherein a monomer reacts by radicals generated from light, or
cation reactive types wherein a monomer undergoes cationic
polymerization. Radical reactive monomers include (meth)acrylate
compounds and vinyl compounds (such as certain types of vinyl
ethers). Cation reactive types include epoxy compounds, and certain
types of vinyl ethers. For example, an epoxy compound that can be
used as a cation reactive type can serve as a monomer for both
thermosetting resins and photocuring resins.
[0189] A (meth)acrylate compound is a compound having at least one
(meth)acrylate group in the molecule. Specific examples of
(meth)acrylate compounds include monofunctional (meth)acrylates,
polyfunctional (meth)acrylates, epoxy acrylates, polyester
acrylates, and urethane acrylates.
[0190] Vinyl compounds include vinyl ethers, styrene and styrene
derivatives, and vinyl compounds. Vinyl ethers include ethylvinyl
ether, propylvinyl ether, hydroxyethylvinyl ether and
ethyleneglycol divinyl ether. Styrene derivatives include
methylstyrene and ethylstyrene. Vinyl compounds include triallyl
isocyanurate and trimethallyl isocyanurate.
[0191] Reactive oligomers may also be used as photocuring resin
starting materials. Reactive oligomers include oligomers having any
combination selected from among (meth)acrylate groups, epoxy
groups, urethane bonds and ester bonds in the same molecule,
examples of which are a urethane acrylate having a (meth)acrylate
group and urethane bond in the same molecule, a polyester acrylate
having a (meth)acrylate group and an ester bond in the same
molecule, and an epoxy acrylate derived from an epoxy resin and
having an epoxy group and a (meth)acrylate group in the same
molecule.
[0192] These photocuring resins may be used alone, or two or more
different types may be used as blends. For a blend, the blend ratio
may be appropriately set depending on the particular use.
[Elastomer (Rubber)]
[0193] Specific examples of elastomers (rubbers) include, but are
not particularly limited to, natural rubber (NR), butadiene rubber
(BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber
(IR), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR),
acrylonitrile-styrene-butadiene copolymer rubber, chloroprene
rubber, styrene-isoprene copolymer rubber,
styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene
copolymer rubber, chlorosulfonated polyethylene rubber, modified
natural rubber (such as epoxidated natural rubber (ENR), natural
hydride rubber and deproteinized natural rubber),
ethylene-propylene copolymer rubber, acrylic rubber,
epichlorohydrin rubber, polysulfide rubber, silicone rubber,
fluorine rubber and urethane rubber. These rubber materials may be
used alone, or two or more different types may be used as blends.
For a blend, the blend ratio may be appropriately set depending on
the particular use.
[0194] The resin composite of this embodiment can be produced by
mixing the chemically modified fine fibers with a base resin, and
carrying out heat-fusion kneading, thermosetting, photocuring and
curing. A molded article may also be fabricated by casting the
resin composite. The form in which the chemically modified fine
fibers are added during production of the resin composite is not
particularly restricted, and it may be as a slurry containing not
only the dry powder but also water. Water-containing slurry can be
prepared by a method of halting drying during the drying procedure
in the method for producing the chemically modified fine fibers, or
a method of adding water after first drying.
[0195] According to one aspect, the method for producing a resin
composite when the resin is a thermoplastic resin includes a step
of kneading the chemically modified fine fibers in the form of dry
powder or an aqueous dispersion inside a melt kneading molding
machine, together with the thermoplastic resin, and then casting
the kneaded mixture.
[0196] According to another aspect, the method for producing the
resin composite when the resin is a thermosetting resin or
photocuring resin includes a step of mixing the chemically modified
fine fibers and a thermosetting resin and then casting the mixture
and subjecting it to thermosetting treatment, or a step of mixing
the chemically modified fine fibers and a photocuring resin and
then casting the mixture and subjecting it to photocuring
treatment.
[0197] According to yet another aspect, the method for producing
the resin composite when the resin is an elastomer includes a step
of mixing the chemically modified fine fibers with a rubber
starting material and then casting the mixture and subsequently
vulcanizing it. The method of mixing the chemically modified fine
fibers and the rubber starting material may be a method of kneading
with a kneader such as a bench roll, Banbury mixer, kneader or
planetary mixer; a method of mixing with a stirring blade; or a
method of mixing with a revolving or rotating stirrer.
[0198] More specific methods for producing the resin composite when
the resin is a thermoplastic resin include, but are not limited
to:
1. A method of using a single-screw or twin-screw extruder for melt
kneading of a mixture of the chemically modified fine fibers (dry
powder or aqueous dispersion) and a thermoplastic resin, followed
by:
[0199] (1) extrusion into a strand form and cooling solidification
in a water bath to obtain molded pellets of the resin
composite,
[0200] (2) extrusion and cooling into a rod or tubular form to
obtain an extruded body of the resin composite, or
[0201] (3) extrusion with a T-die to obtain a molded sheet or film
of the resin composite, or
2. A method of mixing the chemically modified fine fibers (dry
powder or aqueous dispersion) with a thermoplastic resin monomer
and conducting polymerization reaction (specifically, solid-phase
polymerization, emulsion polymerization, suspension polymerization,
solution polymerization or bulk polymerization), and extruding the
obtained product by the method of any one of (1) to (3) above, to
obtain a molded resin composite.
[0202] When the resin is a thermoplastic resin, the minimum
processing temperature recommended by the supplier of the
thermoplastic resin is 255 to 270.degree. C. for polyamide 66, 225
to 240.degree. C. for polyamide 6, 170.degree. C. to 190.degree. C.
for a polyacetal resin and 160 to 180.degree. C. for polypropylene.
The heating preset temperature is preferably in a range of
20.degree. C. higher than the recommended minimum processing
temperature. Setting the mixing temperature to within this range
will allow the chemically modified fine fibers and the resin to be
uniformly mixed.
[0203] The moisture content of the resin composite is not
particularly restricted, but for a polyamide, for example, it is
preferably 10 ppm or greater to inhibit increase in molecular
weight of the polyamide during melting, while it is also preferably
1200 ppm or lower, more preferably 900 ppm or lower and most
preferably 700 ppm or lower to inhibit hydrolysis of the polyamide
during melting. The moisture content is the value measured using a
Karl Fischer moisture meter by the method of ISO 15512.
[0204] A resin composite with a thermoplastic resin as the resin
can be utilized for various types of molded resins. The method for
producing the molded resin is not particularly restricted and any
production method may be employed, but the molded resin can be
produced in the form of a sheet, film or fibers by injection
molding (injection compression molding, injection press molding or
gas assist injection molding), as well as by various types of
extrusion (cold runner method or hot runner method), foam molding
(including methods involving injection of supercritical fluids),
insert molding, in-mold coating molding, insulated die molding,
rapid-heating/cooling die molding, profile extrusion methods
(two-color molding, sandwich molding, and injection molding such as
ultra high-speed injection molding), or various types of extrusion
molding methods. Inflation methods, calender methods and casting
methods may also be used for molding into a sheet or film. Molding
into a heat contracted tube is also possible by using a specific
stretching operation. Blow molding products can also be obtained by
rotational molding or blow molding. Injection molding is most
preferred among these from the viewpoint of design and cost.
[0205] The resin composite of this embodiment may be provided in a
variety of different forms. Specifically, resin pellets, sheet
forms, fibrous forms, tabular forms and rod forms may be mentioned.
Resin pellets are more preferred among these for easier
post-processing and facilitated transport. Preferred pellet forms
are round, elliptical or circular columnar. The form of the pellets
can be varied by the cutting method used during extrusion. Pellets
cut by the method known as "underwater cutting" are usually round,
pellets cut by the method known as "hot cutting" are usually round
or elliptical, and pellets cut by the method known as "strand
cutting" are usually cylindrical. The preferred size for round
pellets is 1 mm to 3 mm, as the diameter of the pellets. The
preferred diameter for cylindrical pellets is 1 mm to 3 mm, and the
preferred length is 2 mm to 10 mm. The diameter and length are
preferably above these specified lower limits from the viewpoint of
operational stability during extrusion, and they are preferably
lower than the specified upper limits from the viewpoint of seizing
in the molding machine in post-working.
[0206] The method for producing a resin composite when the resin is
a thermosetting resin or photocuring resin is not particularly
restricted, and examples include methods of adequately dispersing
the chemically modified fine fibers in a resin solution or resin
powder dispersion and drying them, methods of adequately dispersing
the chemically modified fine fibers in a resin monomer solution and
polymerizing them with heat, UV irradiation or a polymerization
initiator, methods of adequately impregnating a molded article
(such as a sheet or molded particle powder) of the chemically
modified fine fibers with a resin solution or resin powder
dispersion and drying it, and methods of adequately impregnating a
molded article of the chemically modified fine fibers with a resin
monomer solution and polymerizing it with heat, UV irradiation or a
polymerization initiator. Any of various polymerization initiators,
curing agents, curing accelerators and polymerization inhibitors
may be added during curing.
[0207] A resin composite with a thermosetting resin or photocuring
resin as the resin can be utilized for various types of molded
resins. The method of producing the molded resin is not
particularly restricted, and any of various production methods may
be used.
[0208] In the case of a thermosetting resin, extrusion molding is
commonly used for production of tabular products, but flat pressing
may also be employed. A profile extrusion method, blow molding
method, compression molding method, vacuum forming method or
injection molding may also be used. Melt extrusion or solution
casting methods may be used for production of a film-like product,
and when a melt method is used, it may be inflation film molding,
cast molding, extrusion lamination molding, calender molding, sheet
forming, fiber molding, blow molding, injection molding, rotational
molding or cover molding.
[0209] After fabricating a sheet, known as the uncured or
semi-cured prepreg, the prepreg may be used as a single layer or
laminated, and pressed and heated for curing and molding of the
resin. Methods of applying heat and pressure include press molding,
autoclave molding, bagging molding, wrapping tape and internal
pressure molding methods, with no limitation to these molding
methods.
[0210] Methods of impregnating filaments or a preform of
reinforcing fibers such as carbon fibers with the resin composite
before resin curing, and then curing the resin to obtain a molded
article (such as RTM, VaRTM, filament winding, RFI or similar
molding methods) may also be used.
[0211] When the resin is a photocuring resin, the molded article
may be produced using any of various curing methods that make use
of an active energy beam.
[0212] The method of producing the resin composite when the resin
is an elastomer, is not particularly restricted, and examples
include a method of dry kneading the chemically modified fine
fibers and rubber starting material, and a method of dispersing or
dissolving the chemically modified fine fibers and rubber starting
material in a dispersing medium and then drying and kneading. The
mixing method used is preferably one using a homogenizer, from the
viewpoint of applying high shearing force and pressure to
accelerate dispersion, but other methods using a propeller-type
stirrer, rotary stirrer, electromagnetic stirrer or manual stirring
may also be used. The obtained resin composite may be molded into
the desired shape and used as a molding material. The form of the
molding material may be a sheet, pellets or powder.
[0213] A resin composite using an elastomer as the resin can be
utilized for various types of molded resins. The method of
producing the molded resin is not particularly restricted, and any
of various production methods may be used. The molding material may
be molded by a desired molding method such as die molding,
injection molding, extrusion molding, blow molding or foam molding
to obtain an unvulcanized molded article of the desired shape. The
unvulcanized molded article may then be vulcanized by heat
treatment as necessary.
[0214] The molded article obtained from the resin composite of this
embodiment may be in any form depending on the purpose, such as a
three-dimensional shape, or a sheet, film or fibrous form. A
portion (for example, several locations) of the molded article may
also be melted by heat treatment and adhered onto a resin or metal
substrate. The molded article may also be a coated film coated onto
a resin or metal substrate, being formed as a laminated body with
the substrate. A molded article in a sheet, film or fibrous form
may also be subjected to secondary processing such as annealing
treatment, etching treatment, corona treatment, plasma treatment,
texture transfer, cutting or surface-polishing.
[0215] In the mixing step for the chemically modified fine fibers
and resin, aggregation between chemically modified fine fibers does
not occur and the chemically modified fine fibers homogeneously
disperse in the resin, and therefore a resin composite and molded
article containing chemically modified fine fibers can be obtained
that has excellent dynamic properties, heat resistance, dimensional
stability, surface smoothness and outer appearance. In addition,
with the resin composite of this embodiment it is possible to
obtain a satisfactory balance for the mechanical properties,
including static properties in bending testing and dynamic
properties in impact testing. In terms of the heat resistance of
the resin composite, the deflection temperature under load can be
increased by several tens of degrees Celsius. With a molded article
that is the final molded product obtained from the resin composite,
the chemically modified fine fibers do not form aggregated masses,
and therefore the surface smoothness and outer appearance are
excellent.
[0216] In terms of the dimensional stability, in particular, when
evaluation is conducted based on the linear coefficient of thermal
expansion (CTE), it is preferably 80 ppm/k or smaller, more
preferably 70 ppm/k or smaller, even more preferably 60 ppm/k or
smaller, yet more preferably 55 ppm/k or smaller and most
preferably 50 ppm/k or smaller, for the resin composite of this
embodiment.
[0217] In terms of the flexural modulus and flexural strength, the
proportion of increase in the flexural modulus of the resin
composite of this embodiment, when evaluated as the proportion of
increase with respect to the resin containing no filler component
(that is, the chemically modified fine fibers and other fillers) is
preferably 1.3 or higher, more preferably 1.4 or higher, even more
preferably 1.5 or higher, yet more preferably 1.6 or higher and
most preferably 1.7 or higher. The proportion of increase in the
flexural strength of the resin composite of this embodiment is
preferably 1.3 or higher, more preferably 1.4 or higher, even more
preferably 1.5 or higher and most preferably 1.6 or higher.
[0218] In terms of the storage modulus, the proportion of increase
in the storage modulus of the resin composite of this embodiment,
when evaluated as the proportion of increase with respect to the
resin containing no filler component (that is, the chemically
modified fine fibers and other fillers) is preferably 1.3 or
higher, more preferably 1.4 or higher, even more preferably 1.5 or
higher, yet more preferably 1.6 or higher and most preferably 1.7
or higher. The proportion of increase in the storage modulus of the
resin composite of this embodiment is preferably 1.3 or higher,
more preferably 1.4 or higher, even more preferably 1.5 or higher
and most preferably 1.6 or higher.
Second Embodiment
[0219] The second embodiment, as one aspect of the invention,
provides chemically modified fine cellulose fibers wherein the
weight-average molecular weight (Mw) is 100,000 or greater, and the
ratio (Mw/Mn) of the weight-average molecular weight (Mw) and
number-average molecular weight (Mn) is 6 or lower. As mentioned
above for the first embodiment, since the ends of the cellulose
molecules act as origins for thermal decomposition, a high
weight-average molecular weight also results in a narrower
molecular weight distribution, resulting in fine cellulose fibers,
as well as a resin composite containing the fine cellulose fibers
and resin, with high heat resistance.
[0220] According to one aspect, the chemically modified fine fibers
of the second embodiment have an alkali-soluble content of 12 mass
% or lower.
[0221] According to one aspect, the chemically modified fine fibers
of the second embodiment have a thermal decomposition initiation
temperature (T.sub.D) of 270.degree. C. or higher, a number-average
fiber diameter of 10 nm or greater and less than 1 .mu.m, and/or a
degree of crystallinity of 60% or higher. The chemically modified
fine fibers of the second embodiment preferably have at least one,
at least two, at least three, or at least four, of the following
properties: being esterified fine cellulose fibers; having an
average degree of substitution of hydroxyl groups of 0.5 or
greater; having a mean content for the acid-insoluble component per
unit specific surface area of 1.0 mass %g/m.sup.2 or lower; and
having a coefficient of variation (CV) for the DS non-uniformity
ratio (DSs/DSt), as the ratio of the degree of modification (DSs)
of the fiber surface with respect to the degree of modification
(DSt) of the entire fibers, of 50% or lower. The other aspects of
the chemically modified fine fibers of the second embodiment are
the same as the preferred aspects for the chemically modified fine
fibers of the first embodiment explained above.
[0222] The second embodiment provides a method for producing
chemically modified fine cellulose fibers, which includes:
[0223] defibrating a cellulose starting material having a
weight-average molecular weight (Mw) of 100,000 or greater, a ratio
(Mw/Mn) of weight-average molecular weight (Mw) and number-average
molecular weight (Mn) of 6 or lower and an alkali-soluble content
of 12 mass % or lower, in a dispersion that includes an aprotic
solvent, to obtain fine cellulose fibers, and
[0224] adding a modifying agent-containing solution to the
dispersion to modify the fine cellulose fibers, thereby obtaining
chemically modified fine cellulose fibers having a weight-average
molecular weight (Mw) of 100,000 or greater, a ratio (Mw/Mn) of
weight-average molecular weight (Mw) and number-average molecular
weight (Mn) of 6 or lower, an alkali-soluble content of 12 mass %
or lower and a degree of crystallinity of 60% or higher. According
to one aspect, the chemically modified fine cellulose fibers
obtained by this method have a thermal decomposition initiation
temperature (T.sub.D) of 270.degree. C. or higher and a
number-average fiber diameter of 10 nm or greater and less than 1
.mu.m. According to another aspect, the aprotic solvent is dimethyl
sulfoxide, and the modifying agent is vinyl acetate or acetic
anhydride. Examples of preferred aspects for defibrating and
modification are the same as explained for the first
embodiment.
[0225] The second embodiment also provides a resin composite
containing the chemically modified fine cellulose fibers and resin,
and a method for producing it. Examples of preferred aspects for
the resin composite, its constituent components and the method for
producing the resin composite, are the same as explained for the
first embodiment.
Third Embodiment
[0226] The third embodiment, as one aspect of the invention,
provides:
[0227] a resin composite containing 0.5 to 40 mass % of chemically
modified fine cellulose fibers and a resin,
[0228] wherein the DS non-uniformity ratio (DSs/DSt), as the ratio
of the degree of modification (DSs) of the fiber surfaces with
respect to the degree of modification (DSt) of the entire
chemically modified fine cellulose fibers, is 1.1 or greater, and
the coefficient of variation (CV) of the DS non-uniformity ratio
(DSs/DSt) is 50% or lower.
[0229] The third embodiment also provides:
[0230] a method for producing a resin composite containing 0.5 to
40 mass % of chemically modified fine cellulose fibers, and a
resin, wherein the method includes:
[0231] a defibrating step in which a cellulose starting material is
defibrated in a dispersion that includes the cellulose starting
material and an aprotic solvent but essentially does not include an
ionic liquid or sulfuric acid, to obtain fine cellulose fibers,
[0232] a modifying step in which a solution that includes a
modifying agent is added to the dispersion for chemical
modification of the fine cellulose fibers, to obtain chemically
modified fine cellulose fibers, and
[0233] a kneading step in which the chemically modified fine
cellulose fibers and the resin are kneaded,
[0234] the DS non-uniformity ratio (DSs/DSt), as the ratio of the
degree of modification (DSs) of the fiber surfaces with respect to
the degree of modification (DSt) of the entire chemically modified
fine cellulose fibers, is 1.1 or greater, and the coefficient of
variation (CV) of the DS non-uniformity ratio (DSs/DSt) is 50% or
lower.
[0235] This method is advantageous for producing a resin composite
containing chemically modified fine fibers having a thermal
decomposition initiation temperature (T.sub.D) of 270.degree. C. or
higher, a number-average fiber diameter of 10 nm or greater and
less than 1 .mu.m and a degree of crystallinity of 60% or higher,
and a resin.
[0236] The other aspects of the resin composite and method for
producing it according to the third embodiment are the same as the
preferred aspects mentioned above for the resin composite and
method for producing it according to the first embodiment.
[Uses of Resin Composite]
[0237] Because the resin composite of this embodiment has high heat
resistance and light weight, it can substitute for steel sheets, or
for fiber-reinforced plastics such as carbon fiber reinforced
plastics or glass fiber reinforced plastics, or for inorganic
filler-containing resin composites. For example, it can serve as a
material for industrial machinery parts (for example,
electromagnetic device housings, roll materials, transport arms or
medical equipment members), common machine parts,
automobile/railway/vehicle parts (for example, outer platings,
chassis, aerodynamic members, seats or friction materials for
transmission interiors), ship members (for example, hulls or
seats), aviation-related parts (for example, fuselages, wings, tail
units, moving vanes, fairings, cowls, doors, seats or interior
finishing materials), spacecraft, artificial satellite members
(motor cases, wings, body frames or antennae), electronic and
electrical components (for example, personal computer cases,
cellular phone cases, OA devices, AV devices, telephone sets,
facsimiles, household electrical appliances, toy parts or printed
circuit boards), construction and civil engineering materials (for
example, reinforcing steel substitute materials, truss structures
or suspension bridge cables), subsistence items, sports and leisure
goods (for example, golf club shafts, fishing rods or tennis and
badminton rackets), and wind power generation housing members, as
well as members of containers and packings, including high-pressure
containers filled with hydrogen gas or the like to be used for fuel
cells.
[0238] Preferred among these are members that can exhibit
superiority through higher heat resistance compared to existing
resin composites (i.e. members necessary for resin molding). From
this viewpoint, automobile members comprising the resin composite
of this embodiment and electronic product members comprising the
resin composite of this embodiment are preferred.
EXAMPLES
[0239] The present invention will now be explained in more specific
detail through examples, with the understanding that the scope of
the invention is in no way limited to the examples.
Example I: First Embodiment
[Production Example 1-1] (Fabrication of Chemically Modified Fine
Fibers 1-1)
[0240] Using 210 g of filter paper 5A (FILTER PAPER by Advantec
Corp.) (mean content for acid-insoluble component: mass %,
alkali-soluble portion content: 10.1 mass %) as the starting
material for chemically modified fine fibers, it was stirred in 5
kg of dimethyl sulfoxide (DMSO) at 500 rpm for 1 hour at ordinary
temperature, using a uniaxial stirrer (DKV-1 (p125 mm dissolver by
Aimex Co.). The mixture was then fed to a bead mill (NVM-1.5 by
Aimex Co.) using a hose pump and circulated for 120 minutes with
DMSO alone, to obtain 5.2 kg of defibrated slurry (defibrating
step). Also, 572 g of vinyl acetate and 85 g of sodium
hydrogencarbonate were added into the bead mill, and then the
mixture was further circulated for 60 minutes to obtain a
defibrated modified slurry (defibrating/acetylating step).
[0241] During the circulation, the rotational speed of the bead
mill was 2500 rpm and the circumferential speed was 12 m/s, while
the beads used were made of zirconia with a size of 02.0 mm and the
fill factor was 70% (the slit gap of the bead mill was 0.6 mm).
During the circulation, the slurry temperature was controlled to
40.degree. C. with a chiller, for absorption of the heat release by
abrasion.
[0242] After then adding 10 L of purified water to the obtained
defibrated and modified slurry and thoroughly stirring, it was
placed in a dehydrator and concentrated. The obtained wet cake was
then re-dispersed in 10 L of purified water and stirred and
concentrated, and this rinsing procedure was repeated a total of 5
times to remove the unreacted reagent solvent. The finally obtained
aqueous dispersion of chemically modified fine fibers 1-1 (solid
content: 10 mass %) was vacuum dried at about 40.degree. C. using a
revolving/rotating stirrer (V-mini300 by EME Co.) to obtain
chemically modified fine fibers 1-1.
[0243] FIG. 3 shows a SEM image (magnification: 10,000.times.) of a
porous sheet fabricated by the method described below for the
chemically modified fine fibers 1-1.
[Production Example 1-2] (Fabrication of Chemically Modified Fine
Fibers 1-2)
[0244] Chemically modified fine fibers 1-2 were obtained in the
same manner as Production Example 1-1, except for using linter pulp
as the starting material, and vacuum drying an aqueous dispersion
of the obtained chemically modified fine fibers 1-2 (solid content:
10 mass %) at 40.degree. C. using a revolving/rotating stirrer.
[Production Example 1-3] (Fabrication of Chemically Modified Fine
Fibers 1-3)
[0245] The same method was used as in Production Example 1-2 up to
the defibrating step, except for using the same linter pulp as
Production Example 1-1 as the starting material, to obtain 5.2 kg
of a defibrated slurry (defibrating step). The obtained defibrated
slurry was loaded into an explosion-proof disperser tank, after
which 572 g of vinyl acetate and 85 g of sodium hydrogencarbonate
were added, the internal temperature of the tank was brought to
40.degree. C., and stirring was carried out for 120 minutes. The
obtained slurry was dispersed and stirred in 10 L of purified
water, and then concentrated with a dehydrator. The obtained wet
cake was then re-dispersed in 10 L of purified water and stirred
and concentrated, and this rinsing procedure was repeated a total
of 5 times to remove the unreacted reagent solvent. Finally, the
rinsed slurry (solid content: 10 mass %) was vacuum dried at
40.degree. C. using the revolving/rotating stirrer mentioned above,
to obtain chemically modified fine fibers 1-3.
[Production Example 1-4] (Fabrication of Chemically Modified Fine
Fibers 1-4)
[0246] Chemically modified fine fibers 1-4 were obtained in the
same manner as Production Example 1-3, except that the stirring
time in the explosion-proof disperser tank was 20 minutes.
[Production Example 1-5] (Fabrication of Chemically Modified Fine
Fibers 1-5)
[0247] Chemically modified fine fibers 1-5 were obtained in the
same manner as Production Example 1-3, except that the stirring
time in the explosion-proof disperser tank was 240 minutes.
[Production Example 1-6] (Fabrication of Chemically Modified Fine
Fibers 1-6)
[0248] After dispersing 4.5 kg of the same linter pulp as
Production Example 1-2 in 300 L of purified water, the dispersion
was stirred for approximately 30 minutes in a disperser tank, and
then the slurry was beaten for 30 minutes using a disc refiner with
the disc blade gap set to about 1 mm, and further beaten for 120
minutes with the disc blade gap set to 0.1 mm, to obtain a beaten
slurry. The obtained beaten slurry was then treated with a
high-pressure homogenizer (corresponding to 10 Pass with an
operating pressure of 100 MPa), to obtain a CNF slurry
(concentration: 1.5 mass %) with a number-average fiber diameter of
about 75 nm. In order to replace the solvent of the CNF slurry from
water to dimethylformamide, the CNF slurry was concentrated to a
solid content of 10 mass % or greater with a dehydrator, after
which the concentrated slurry was loaded into 300 L of
dimethylformamide that had been loaded into an explosion-proof
disperser tank, and after stirring for 20 minutes, it was
concentrated with a dehydrator to a solid content of 10 mass % or
greater. After carrying out this procedure two more times, the
re-concentrated slurry was loaded into 150 L of dimethylformamide
in the explosion-proof disperser tank and stirred for 30 minutes,
after which 15 Kg of acetic anhydride and 5 kg of pyridine were
loaded in, the internal temperature of the tank was brought to
30.degree. C., and stirring was conducted for 120 minutes. The
obtained slurry was dispersed and stirred in 10 L of purified
water, and then concentrated with a dehydrator. The obtained wet
cake was then re-dispersed in 10 L of purified water and stirred
and concentrated, and this rinsing procedure was repeated a total
of 5 times to remove the unreacted reagent solvent. The rinsing
procedure was repeated 3 times, and the obtained aqueous dispersion
of chemically modified fine fibers 1.about.4 (solid content: 10
mass %) was vacuum dried at 40.degree. C. using the
revolving/rotating stirrer mentioned above to produce chemically
modified fine fibers 1-6.
[Production Example 1-7] (Fabrication of Non-Chemically-Modified
Fine Fibers 1-1)
[0249] CELISH KY-100G by Daicel Co. used as non-chemically-modified
fine cellulose fibers were vacuum dried at 40.degree. C. using the
revolving/rotating stirrer mentioned above, to prepare fine fibers
1-1.
[Production Example 1-8] (Fabrication of Chemically Modified Fine
Fibers 1-7)
[0250] After placing 50 g of filter paper 5A (FILTER PAPER by
Advantec) in a 1000 ml flask, and further adding 300 g of
N,N-dimethylacetamide and 300 g of ionic liquid
1-butyl-3-methylimidazolium chloride, the mixture was stirred.
Next, 270 g of acetic anhydride was added and reacted, after which
the mixture was filtered and the solid content was rinsed. After
treatment with a homogenizer, the rinsed slurry (solid content: 10
mass %) was finally vacuum dried at 40.degree. C. using the
revolving/rotating stirrer mentioned above, to prepare chemically
modified fine fibers 1-7.
[Example 1-1] (Fabrication of Resin Composite 1-1)
[0251] Upon adding 2 parts by mass of the obtained chemically
modified fine fibers 1-1 and 98 parts by mass of polyamide 66 resin
(hereunder referred to simply as "PA66") (A226 by Unitika, Ltd.), a
mini kneader ("Xplore", product name of Xplore Instruments) was
used for circulated kneading for 5 minutes at 260.degree. C., 100
rpm (shear rate: 1570 (1/s)), after which it was passed through a
die to obtain a (p1 mm strand of resin composite 1-1. Resin
composite pellets obtained from the strand (after cutting the
strand to 1 cm lengths) were melted at 260.degree. C. with an
accessory injection molding machine, and the resin was used to form
a dumbbell-shaped test piece conforming to JIS K7127, which was
used for evaluations.
[Example 1-2] (Fabrication of Resin Composite 1-2)
[0252] Resin composite 1-2 was obtained in the same manner as
Example 1-1, except that the amount of chemically modified fine
fibers 1-1 was changed to 4 parts by mass and the amount of PA66
was changed to 96 parts by mass.
[Example 1-3] (Fabrication of Resin Composite 1-3)
[0253] Resin composite 1-3 was obtained in the same manner as
Example 1-1, except that the amount of chemically modified fine
fibers 1-1 was changed to 8 parts by mass and the amount of PA66
was changed to 92 parts by mass.
[Example 1-4] (Fabrication of Resin Composite 1-4)
[0254] Resin composite 1-4 was obtained in the same manner as
Example 1-2, except that the fine fibers were changed to chemically
modified fine fibers 1-2.
[Example 1-5] (Fabrication of Resin Composite 1-5)
[0255] Resin composite 1-5 was obtained in the same manner as
Example 1-2, except that the PA66 of Example 1-2 was changed to
acrylonitrile-butadiene rubber (DN003 by Zeon Corp.) (hereunder
referred to simply as "NBR"), and the kneading temperature in the
mini kneader and the molding temperature in the injection molding
machine were changed to 50.degree. C.
[Example 1-6] (Fabrication of Resin Composite 1-6)
[0256] Resin composite 1-6 was obtained in the same manner as
Example 1-2, except that the PA66 of Example 1-2 was changed to PA6
(1013B by Ube Industries, Ltd.) (hereunder referred to simply as
"PA6"), and the kneading temperature in the mini kneader and the
molding temperature in the injection molding machine were changed
to 240.degree. C.
[Example 1-7] (Fabrication of Resin Composite 1-7)
[0257] Resin composite 1-7 in the form of a dumbbell-shaped test
piece was obtained in the same manner as Example 1-1, except that
the chemically modified fine fibers 1-1 of Example 1-1 were changed
to 4 parts by mass of chemically modified fine fibers 1-3, the PA66
was changed to 96 parts by mass of a polypropylene resin (Prime
Polypro J105G by Prime Polymer Co., Ltd.) (hereunder referred to
simply as "PP"), and the kneading temperature in the mini kneader
and the molding temperature in the injection molding machine were
changed to 160.degree. C.
[Example 1-8] (Fabrication of Resin Composite 1-8)
[0258] Resin composite 1-8 in the form of a dumbbell-shaped test
piece was obtained in the same manner as Example 1-1, using a solid
mixture (dispersion) (5 parts by mass) of the chemically modified
fine fibers 1-3 and polyoxyethylene hardened castor oil ether
obtained by adding 1 part by mass of polyoxyethylene hardened
castor oil ether (BLAUNON RCW-20 (hereunder referred to simply as
"RCW-20") by Aoki Oil Industrial Co., Ltd.) as a dispersion
stabilizer with respect to an amount of the chemically modified
fine fibers 1-3 corresponding to 4 parts by mass in an aqueous
dispersion before drying the chemically modified fine fibers 1-3
(solid content: 9 mass %), and using the revolving/rotating stirrer
mentioned above for kneading at 30.degree. C. for 30 minutes
followed by vacuum drying at about 40.degree. C., and 95 parts by
mass of PP, in Production Example 1-3.
[Example 1-9] (Fabrication of Resin Composite 1-9)
[0259] Resin composite 1-9 was obtained in the same manner as
Example 1-8, except that in Example 1-8, the dispersion stabilizer
was changed to 1 part by mass of DMSO.
[Example 1-10] (Fabrication of Resin Composite 1-10)
[0260] Resin composite 1-10 was obtained in the same manner as
Example 1-7, except that in Example 1-7, the amount of chemically
modified fine fibers 1-3 was changed to 8 parts by mass and the
amount of PP was changed to 92 parts by mass.
[Example 1-11] (Fabrication of Resin Composite 1-11)
[0261] Resin composite 1-11 was obtained in the same manner as
Example 1-8, except that in Example 1-8, a solid mixture comprising
8 parts by mass of chemically modified fine fibers 1-3 and 2 parts
by mass of RCW-20 (10 parts by mass) (as a dispersion) was mixed
with 90 parts by mass of PP, and the mixture was melt kneaded.
[Example 1-12] (Fabrication of Resin Composite 1-12)
[0262] Resin composite 1-12 was obtained in the same manner as
Example 1-9, except that in Example 1-9, a solid mixture comprising
8 parts by mass of chemically modified fine fibers 1-3 and 2 parts
by mass of DMSO (10 parts by mass) (as a dispersion) was mixed with
90 parts by mass of PP, and the mixture was melt kneaded.
[Example 1-13] (Fabrication of Resin Composite 1-13)
[0263] Resin composite 1-13 in the form of a dumbbell-shaped test
piece was obtained by melt kneading in the same manner as Example
1-1, using a solid mixture (dispersion) (8 parts by mass) obtained
by adding 4 parts by mass of cellulose whiskers (SC900 by Asahi
Kasei Corp.) and 2 parts by mass of RCW-20 with respect to an
amount of the chemically modified fine fibers 1-2 corresponding to
2 parts by mass in an aqueous dispersion before drying the
chemically modified fine fibers 1-2 (solid content: 10 mass %), and
using the revolving/rotating stirrer mentioned above for kneading
at 30.degree. C. for 30 minutes followed by vacuum drying at about
40.degree. C., and 92 parts by mass of PA66, in Production Example
1-2.
[Example 1-14] (Fabrication of Resin Composite 1-14)
[0264] Resin composite 1-14 was obtained by producing 12 parts by
mass of a solid mixture in the same manner as Example 1-13, except
that 4 parts by mass of a plasticizer (W-260 by DIC Co., Ltd.)
instead of RCW-20, and 88 parts by mass of PA66, were used in
Example 1-13, and then melt kneading the mixture.
[Example 1-15] (Fabrication of Resin Composite 1-15)
[0265] Resin composite 1-15 was obtained by producing 10 parts by
mass of a solid mixture in the same manner as Example 1-13, except
that 4 parts by mass of chemically modified fine fibers 1-3 instead
of chemically modified fine fibers 1-2 and 90 parts by mass of PP
instead of PA66 were used in Example 1-13, and then melt kneading
the mixture.
[Example 1-16] (Fabrication of Resin Composite 1-16)
[0266] Resin composite 1-16 was obtained by producing 12 parts by
mass of a solid mixture in the same manner as Example 1-15, except
that 4 parts by mass of W-260 was used instead of RCW-20 in Example
1-15, and then melt kneading the mixture.
[Example 1-17] (Fabrication of Resin Composite 1-17)
[0267] Resin composite 1-17 was obtained in the same manner as
Example 1-8, except that in Example 1-8, 12 parts by mass of a
solid mixture comprising 10 parts by mass of chemically modified
fine fibers 1-2 and 2 parts by mass of RCW-20, was mixed with 88
parts by mass of PA6, and the mixture was melt kneaded.
[Example 1-18] (Fabrication of Resin Composite 1-18)
[0268] Resin composite 1-18 was obtained by producing 10 parts by
mass of a solid mixture in the same manner as Example 1-15, except
that 90 parts by mass of PA6 was used instead of PP in Example
1-15, and then melt kneading the mixture.
[Example 1-19] (Fabrication of Resin Composite 1-19)
[0269] Resin composite 1-19 was obtained in the same manner as
Example 1-17, except that the chemically modified fine fibers
1.about.4 were used in Example 1-17.
[Example 1-20] (Fabrication of Resin Composite 1-20)
[0270] Resin composite 1-20 was obtained in the same manner as
Example 1-17, except that the chemically modified fine fibers 1-5
were used in Example 1-17.
[Comparative Example 1-1] (Fabrication of Resin Composite 1-A)
[0271] Resin composite 1-A was obtained in the same manner as
Example 1-1, except that the chemically modified fine fibers 1-1
were changed to fine fibers 1-1. The resin composite 1-A underwent
brown discoloration.
[Comparative Example 1-2] (Resin 1-1)
[0272] Resin 1-1 was obtained by casting and cooling PP alone, as a
blank, under the same melt molding conditions as in Example
1-7.
[Comparative Example 1-3] (Resin Composite 1-B)
[0273] Resin composite 1-B was obtained in the same manner as
Comparative Example 1-2, except that 10 parts by mass of talc was
added as a filler component to 90 parts by mass of PP, and the
mixture was melt kneaded.
[Comparative Example 1-4] (Resin 1-2)
[0274] Resin 1-2 was obtained by casting and cooling PA66 alone, as
a blank, under the same melt molding conditions as in Example
1-1.
[Comparative Example 1-5] (Resin Composite 1-C)
[0275] Resin composite 1-C was obtained in the same manner as
Comparative Example 1-4, except that 10 parts by mass of talc was
added as a filler component to 90 parts by mass of PA66, and the
mixture was melt kneaded.
[Comparative Example 1-6] (Resin Composite 1-D)
[0276] Resin composite 1-D was obtained in the same manner as
Example 1-1, except that the chemically modified fine fibers 1-1
were changed to chemically modified fine fibers 1-6. The resin
composite 1-D underwent brown discoloration.
[Comparative Example 1-7] (Resin Composite 1-E)
[0277] Resin composite 1-E was obtained in the same manner as
Example 1-2, except that the chemically modified fine fibers 1-1
were changed to chemically modified fine fibers 1-6. The resin
composite 1-E underwent brown discoloration.
[Comparative Example 1-8] (Resin Composite 1-F)
[0278] Resin composite 1-F was obtained in the same manner as
Example 1-3, except that the chemically modified fine fibers 1-1
were changed to chemically modified fine fibers 1-6. The resin
composite 1-F underwent brown discoloration.
[Comparative Example 1-9] (Resin Composite 1-G)
[0279] Resin composite 1-G was obtained in the same manner as
Example 1-17, except that the chemically modified fine fibers 1-2
were changed to fine fibers 1-1. The resin composite 1-G underwent
brown discoloration.
[Comparative Example 1-10] (Resin Composite 1-H)
[0280] Resin composite 1-H was obtained in the same manner as
Example 1-17, except that the chemically modified fine fibers 1-2
were changed to chemically modified fine fibers 1-6. The resin
composite 1-H underwent brown discoloration.
[Comparative Example 1-11] (Resin Composite 1-I)
[0281] Resin composite 1-I was obtained in the same manner as
Example 1-17, except that the chemically modified fine fibers 1-2
were changed to chemically modified fine fibers 1-7. The resin
composite 1-I underwent brown discoloration.
[0282] Table 1 shows the starting materials and sample compositions
for Example 1-1 to Example 1-20 and Comparative Examples 1-1 to
1-11.
Example II: Second Embodiment
[Example 2-1] (Fabrication of Chemically Modified Fine Fibers
2-1)
[0283] After charging 0.5 kg of linter pulp and 9.5 kg of dimethyl
sulfoxide (DMSO) into a KAPPA VITA.sup.R rotary homogenizing mixer
with a 35 L tank size, operation was carried out for 4 hours at a
rotational speed of 6000 rpm, a peripheral speed of 29 m/s and
ordinary temperature, for defibration of the pulp (defibrating
step). Next, 0.16 kg of sodium bicarbonate and 1.05 kg of vinyl
acetate were added and operation was carried out for 2 hours at a
rotational speed of 6000 rpm, a peripheral speed of 29 m/s and
60.degree. C. (defibrating/modifying step). After then adding 10 L
of purified water to the obtained defibrated and modified slurry
and thoroughly stirring, it was placed in a dehydrator and
concentrated. The obtained wet cake was again dispersed in 10 L of
purified water and stirred and concentrated, and this rinsing
procedure was repeated a total of 5 times to remove the unreacted
reagent solvent, finally obtaining an aqueous dispersion of the
chemically modified fine fibers 2-1 (number-average fiber diameter:
88 nm) (solid content: 10 mass %).
[0284] FIG. 4 is a diagram showing a scanning electron microscope
(SEM) image of the chemically modified fine fibers 2-1. The SEM
image was taken using a JSM-6700F by JEOL Corp., under conditions
with an acceleration voltage of 5 kV, 10,000.times. magnification
(the visual field size in FIG. 4 is 9 .mu.m x 12 .mu.m) and a WD of
7.1 mm.
[Example 2-2] (Fabrication of Chemically Modified Fine Fibers
2-2)
[0285] Chemically modified fine fibers 2-2 (number-average fiber
diameter: 65 nm) were obtained by production in the same manner as
Example 2-1, except that high-purity wood pulp was used as the
starting material instead of the linter pulp of Example 2-1.
[Example 2-3] (Fabrication of Chemically Modified Fine Fibers
2-3)
[0286] Using refined linter pulp as the starting material instead
of the linter pulp of Example 2-1, 0.5 kg of the refined linter
pulp and 9.5 kg of DMSO were charged into a KAPPA VITA.sup.R rotary
homogenizing mixer with a tank size of 35 L, and operation was
carried out for 4 hours at a rotational speed of 6000 rpm, a
peripheral speed of 29 m/s and ordinary temperature, for
defibration of the pulp (defibrating step). Next, 0.16 kg of sodium
bicarbonate and 1.05 kg of vinyl acetate were added and operation
was carried out for 2 hours at a rotational speed of 2500 rpm, a
peripheral speed of 12 m/s and 60.degree. C. (modifying step).
After then adding 10 L of purified water to the obtained defibrated
and modified slurry and thoroughly stirring, it was placed in a
dehydrator and concentrated. The obtained wet cake was again
dispersed in 10 L of purified water and stirred and concentrated,
and this rinsing procedure was repeated a total of 5 times to
remove the unreacted reagent solvent, finally obtaining an aqueous
dispersion of the chemically modified fine fibers 2-3
(number-average fiber diameter: 80 nm) (solid content: 10 mass
%).
[Example 2-4] (Fabrication of Chemically Modified Fine Fibers
2-4)
[0287] Using 210 g of linter pulp as the starting material for
chemically modified fine fibers, stirring was carried out for 1
hour at ordinary temperature with a uniaxial stirrer (DKV-1
.phi.125 mm Dissolver by Aimex Co.) in 5 kg of dimethyl sulfoxide
(DMSO) at 500 rpm. The mixture was then fed to a bead mill (NVM-1.5
by Aimex Co.) using a hose pump and circulated for 2 hours with
DMSO alone, to obtain 5.2 kg of defibrated slurry (defibrating
step). During the circulation, the rotational speed of the bead
mill was 2500 rpm and the circumferential speed was 12 m/s, while
the beads used were made of zirconia with a size of .PHI.2.0 mm and
the fill factor was 70% (the slit gap of the bead mill was 0.6 mm).
Also during the circulation, the slurry temperature was controlled
to 40.degree. C. with a chiller, for absorption of the heat release
by abrasion. The obtained defibrated slurry was then loaded into an
explosion-proof disperser tank, after which 572 g of vinyl acetate
and 85 g of sodium hydrogencarbonate were added, the internal
temperature of the tank was brought to 40.degree. C., and stirring
was carried out for 2 hours (modifying step). The obtained slurry
was dispersed and stirred in 10 L of purified water, and then
concentrated with a dehydrator. The obtained wet cake was again
dispersed in 10 L of purified water and stirred and concentrated,
and this rinsing procedure was repeated a total of 5 times to
remove the unreacted reagent solvent, to obtain chemically modified
fine fibers 2-4 (number-average fiber diameter: 140 nm).
[Example 2-5] (Fabrication of Chemically Modified Fine Fibers
2-5)
[0288] Chemically modified fine fibers 2-5 (number-average fiber
diameter: 79 nm) were obtained by production in the same manner as
Example 2-1, except that filter paper was used as the starting
material instead of the linter pulp of Example 2-1.
[Example 2-6] (Fabrication of Chemically Modified Fine Fibers
2-6)
[0289] Chemically modified fine fibers 2-6 (number-average fiber
diameter: 66 nm) were obtained by production in the same manner as
Example 2-3, except that separate refined linter pulp was used as
the starting material instead of the linter pulp of Example
2-3.
[Comparative Example 2-1] (Fabrication of Chemically Modified Fine
Fibers 2-7)
[0290] Chemically modified fine fibers 2-7 (number-average fiber
diameter: 58 nm) were obtained by production in the same manner as
Example 2-1, except that wood pulp was used as the starting
material instead of the linter pulp of Example 2-1.
[Comparative Example 2-2] (Fabrication of Chemically Modified Fine
Fibers 2-8)
[0291] Chemically modified fine fibers 2-8 (number-average fiber
diameter: 73 nm) were obtained by production in the same manner as
Example 2-1, except that abaca was used as the starting material
instead of the linter pulp of Example 2-1.
[Comparative Example 2-3] (Fabrication of Chemically Modified Fine
Fibers 2-9)
[0292] Chemically modified fine fibers 2-9 (number-average fiber
diameter: 84 nm) were obtained by production in the same manner as
Example 2-3, except that different refined linter pulp from the
refined linter pulp of Example 2-3 was used.
[Comparative Example 2-4] (Fabrication of Chemically Modified Fine
Fibers 2-10)
[0293] Chemically modified fine fibers 2-10 (number-average fiber
diameter: 64 nm) were obtained by production in the same manner as
Example 2-4, except that the circulation time for DMSO alone after
feeding to the bead mill as described in Example 2-4 was changed
from 2 hours to 8 hours.
[Comparative Example 2-5] (Fabrication of Chemically Modified Fine
Fibers 2-11)
[0294] After adding 50 g of filter paper and 300 g of
1-butyl-3-methylimidazolium chloride as an ionic liquid to 300 ml
of N,N-dimethylacetamide, the mixture was stirred. Next, 270 g of
acetic anhydride was added and reacted, after which the mixture was
filtered and the solid content was rinsed with water. It was then
treated with a high-pressure homogenizer to obtain chemically
modified fine fibers 2-11 (number-average fiber diameter: 44
nm).
[Comparative Example 2-6] (Preparation of Non-Chemically-Modified
Fine Fibers 2-1)
[0295] CELISH KY-100G (number-average fiber diameter: 75 nm) by
Daicel were prepared as non-chemically-modified fine cellulose
fibers.
[0296] The following examples are chemically modified fine fibers
of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6, or
complexes with resins using the fine fibers.
[Example 2-7] (Fabrication of Resin Composite 2-1)
[0297] Upon adding 2 parts by mass of the obtained chemically
modified fine fibers 2-1 (as the solid content in the slurry, same
hereunder) and 98 parts by mass of polyamide 66 resin (hereunder
referred to simply as "PA66") (A226 by Unitika, Ltd.) as resin 2-1,
a mini kneader ("Xplore", product name of Xplore Instruments) was
used for circulated kneading for 5 minutes at 260.degree. C., 100
rpm (shear rate: 1570 (1/s)), after which it was passed through a
die to obtain a .phi.1 mm strand of a composite resin composition.
Resin composite pellets obtained from the strand (after cutting the
strand to 1 cm lengths) were melted at 260.degree. C. with an
accessory injection molding machine, and the resin was used to form
a dumbbell-shaped test piece conforming to JIS K7127, which was
used for evaluation. Resin composite 2-1 in the form of the
obtained dumbbell-shaped test piece was used to carry out the
appropriate evaluations.
[Example 2-8] (Fabrication of Resin Composite 2-2)
[0298] Resin composite 2-2 was obtained in the same manner as
Example 2-7, except that the amount of chemically modified fine
fibers 2-1 was changed to 10 parts by mass and the amount of PA66
was changed to 90 parts by mass.
[Example 2-9] (Fabrication of Resin Composite 2-3)
[0299] Resin composite 2-3 was obtained in the same manner as
Example 2-8, except that the PA66 of Example 2-8 was changed to PA6
(1013B by Ube Industries, Ltd.) (hereunder referred to simply as
"PA6") as the resin 2-2, and the kneading temperature in the mini
kneader and the molding temperature in the injection molding
machine were changed to 250.degree. C.
[Example 2-10] (Fabrication of Resin Composite 2-4)
[0300] Resin composite 2-4 in different forms of dumbbell-shaped
test pieces was obtained in the same manner as Example 2-7, except
that the PA66 of Example 2-7 was changed to 96 parts by mass of a
polypropylene resin (Prime Polypro J105G by Prime Polymer Co.,
Ltd.) (hereunder referred to simply as "PP"), as resin 2-3, and the
kneading temperature with the mini kneader and the molding
temperature with the injection molding machine were changed to
160.degree. C.
[Example 2-11] (Fabrication of Resin Composite 2-5)
[0301] Resin composite 2-5 in different forms of dumbbell-shaped
test pieces was obtained in the same manner as Example 2-7, using a
solid mixture (dispersion) (10 parts by mass) of the chemically
modified fine fibers 2-1 and polyoxyethylene hardened castor oil
ether (BLAUNON RCW-20 (hereunder referred to simply as "RCW-20") by
Aoki Oil Industrial Co., Ltd.), obtained by adding 3 parts by mass
of RCW-20 as a dispersion stabilizer, with respect to an amount of
the chemically modified fine fibers 2-1 corresponding to 7 parts by
mass in an aqueous dispersion before drying the chemically modified
fine fibers 2-1 (solid content: 9 mass %), and using the
revolving/rotating stirrer mentioned above for kneading at
30.degree. C. for 30 minutes followed by vacuum drying at about
40.degree. C., and 90 parts by mass of PA6, in Example 2-7.
[Example 2-12] (Fabrication of Resin Composite 2-6)
[0302] Resin composite 2-6 in different forms of dumbbell-shaped
test pieces was obtained in the same manner as Example 2-11, except
that in Example 2-11, 2 parts by mass of cellulose whiskers (SC900,
by Asahi Kasei Corp.) was mixed with the aqueous dispersion of the
chemically modified fine fibers 2-1 prior to drying and RCW-20 to
obtain a solid mixture (12 parts by mass), and then the solid
mixture (12 parts by mass) and 88 parts by mass of PA6 were
used.
[Comparative Example 2-7] (Fabrication of Resin Composite 2-7)
[0303] Resin composite 2-7 was obtained by fabrication in the same
manner as Example 2-9, except that the chemically modified fine
fibers 2-1 were changed to fine fibers 2-1. The resin composite 2-7
underwent brown discoloration.
[Comparative Example 2-8] (Fabrication of Resin Composite 2-8)
[0304] Resin composite 2-8 was obtained by fabrication in the same
manner as Example 2-9, except that the chemically modified fine
fibers 2-1 were changed to chemically modified fine fibers 2-7. The
resin composite 2-8 underwent brown discoloration.
[0305] The compositions of the starting materials and samples for
the Examples and Comparative Examples are shown in Table 4.
<Evaluation of Fine Fibers and Resin Composites>
[0306] The results of evaluating the properties in Examples I and
II are shown below in Tables 2, 3 and 5.
(1) Fabrication of Measuring Samples
[0307] The chemically modified fine fibers or the fine fibers were
evaluated using a porous sheet as the measuring sample. A porous
sample was fabricated in the following manner.
[0308] First, an aqueous dispersion of the chemically modified fine
fibers or the fine fibers was centrifuged to obtain a condensate
(solid content: mass %). Next, the concentrate containing 0.5 g of
the chemically modified fine fibers or the fine fibers was
dispersed in tert-butanol to 0.2 mass %, and dispersion treatment
was carried out by ultrasonic dispersion until it was free of
aggregates. A 100 g portion of the obtained tert-butanol dispersion
was filtered on filter paper (5C, Advantech, Inc., diameter: 90 mm)
and dried at 150.degree. C., and then the filter paper was detached
to obtain a sheet. Sheets with air permeability resistance up to
100 sec/100 ml per 10 g/m.sup.2 basis weight of the sheet were
considered to be porous sheets, and were used as measuring
samples.
[0309] For the air permeability resistance (sec/100 ml) per 10
g/m.sup.2 of basis weight of the sheet, the basis weight W
(g/m.sup.2) of each sample that had been left to stand for 1 day in
an environment of 23.degree. C., 50% RH was measured, and then an
Oken-type air permeability resistance tester (Model EGO1 by Asahi
Seiko Co., Ltd.) was used to measure the air permeability
resistance R (sec/100 ml). The value per 10 g/m.sup.2 basis weight
was calculated by the following formula. Air permeability
resistance (sec/100 ml) per 10 g/m.sup.2 basis weight=R/W x 10
(2) Number-Average Fiber Diameter
[0310] First, three randomly selected locations on the surface of
the porous sheet were observed with a scanning electron microscope
(SEM) at a magnification corresponding to 10,000-100,000x,
according to the fiber diameter of the fine fibers. For each of the
three obtained SEM images, lines were drawn on the image surface in
the weft direction and the warp direction, the number of fibers
crossing the lines and the fiber diameters of each of the fibers
were measured from the magnified image, and the number-average
fiber diameters for the warp/weft rows were calculated for each
image. The number average of the number-average fiber diameter for
the 3 images was recorded as the mean fiber diameter of the
measured sample.
(3) Specific Surface Area
[0311] The BET specific surface area (m.sup.2/g) was calculated
with the program of a specific surface area/pore distribution
measuring apparatus (Nova-4200e, by Quantachrome Instruments),
after drying approximately 0.2 g of the porous sheet sample for 2
hours in a vacuum at 120.degree. C. and measuring the nitrogen gas
adsorption at the boiling point of liquid nitrogen at five points
(multipoint method) in a relative vapor pressure (P/P.sub.0) range
of 0.05 to 0.2.
(4) IR Index
[0312] The infrared spectroscopy spectrum of the porous sheet was
measured by the ATR-IR method, using a Fourier transform infrared
spectrometer (FT/IR-6200 by Jasco Corp.). The infrared spectroscopy
spectrum was measured under the following conditions.
[0313] Number of scans: 64 times,
[0314] wavenumber resolution: 4 cm.sup.-1,
[0315] measuring wavenumber range: 4000 to 600 cm.sup.-1,
[0316] ATR crystal: diamond,
[0317] incident angle: 45.degree.
(4-1) IR index 1370
[0318] Based on the obtained IR spectrum, the IR index 1370 was
calculated according to the following formula (1):
IR index 1370=H1730/H1370 (1).
[0319] In the formula, H1730 and H1370 are the absorbances at 1730
cm.sup.-1 (absorption band for vibration of the cellulose backbone
chain). The respective baselines used were a line connecting 1900
cm.sup.-1 and 1500 cm.sup.-1 (for H1730) and a line connecting 800
cm.sup.-1 and 1500 cm.sup.-1 (for H1370), each baseline being
defined as the absorbance at absorbance=0.
(4-2) IR Index 1030
[0320] Based on the obtained IR spectrum, the IR index 1030 was
calculated according to the following formula (2):
IR index 1030=H1730/H1030 (2).
[0321] In the formula, H1730 and H1030 are the absorbances at 1730
cm.sup.-1 and 1030 cm.sup.-1 (absorption bands for C--O stretching
vibration of the cellulose backbone chain). The respective
baselines used were a line connecting 1900 cm.sup.-1 and 1500
cm.sup.-1 and a line connecting 800 cm.sup.-1 and 1500 cm.sup.-1,
each baseline being defined as the absorbance at absorbance=0. The
average degree of substitution (DS) was calculated from the IR
index 1030 according to the following formula (3):
DS=4.13.times.IR index 1030 (3).
(5) DS Non-Uniformity Ratio and its Coefficient of Variation
(CV)
[0322] A 100 g portion of the aqueous dispersion of the chemically
modified fine fibers (solid content: 10 mass %) was sampled, and 10
g of each was frozen and pulverized to prepare 10 powder samples.
The powder sample mass was 1 g each. The 10 powder samples were
measured by .sup.13C solid NMR and XPS, the DSt and DSs of each was
determined, and the DS non-uniformity ratio was calculated for each
powder sample. The coefficient of variation was calculated using
the standard deviation (.sigma.) and arithmetic mean (.mu.) of the
DS non-uniformity ratio for each of the obtained 10 samples.
DS Non-uniformity ratio=DSs/DSt
Coefficient of variation(%)=standard deviation .sigma./arithmetic
mean .mu..times.100
[0323] The method of calculating DSt may be subjecting the powder
chemically modified fine fibers to .sup.13C solid NMR measurement,
and determining DSt according to the following formula using the
area intensity (Inf) of the signal (23 ppm) attributed to the
carbon atom of --CH3 of the acetyl group, with respect to the total
area intensity (Inp) of the signals attributed to C1-C6 carbons of
the pyranose rings of cellulose, appearing in the range of 50 ppm
to 110 ppm.
DSt=(Inf).times.6/(Inp)
[0324] The conditions used in the .sup.13C solid NMR measurement
may be as follows, for example. Apparatus: Bruker Biospin Avance
500WB
Frequency: 125.77 MHz
[0325] Measuring method: DD/MAS Latency time: 75 sec NMR sample
tube:4 mm.phi. Number of scans: 640 (.about.14 hr)
MAS: 14,500 Hz
[0326] Chemical shift reference: glycine (external reference:
176.03 ppm)
[0327] As the method of calculating DSs, a powder sample of the
chemically modified fine fibers used for .sup.13C solid NMR
measurement was placed on a 2.5 mm.phi. dish-shaped sample stand,
the surface was pressed flat and XPS measurement was performed. The
obtained Cls spectrum was analyzed by peak separation, and DSs was
determined by the following formula using the area intensity (Ixf)
of the peak (286 eV) attributed to the acetyl group O--C.dbd.O bond
with respect to the area intensity (Ixp) of the peak attributed to
the C2-C6 carbons of the pyranose rings of cellulose (289 eV, C--C
bond).
DSs=(I.times.f).times.5/(Ixp)
[0328] The conditions used for XPS measurement were the
following.
Device: VersaProbe II by Ulvac-Phi, Inc.
[0329] Excitation source: mono. AlKa 15 kV.times.3.33 mA Analysis
size: .about.200 pimp Photoelectron take-off angle: 45.degree.
Capture range Narrow scan: C 1s, O 1s
Pass Energy: 23.5 eV
(6) Degree of Crystallinity
[0330] The porous sheet was subjected to X-ray diffraction and the
degree of crystallinity was calculated by the following
formula.
Degree of
crystallinity(%)=[I.sub.(200)-I.sub.(amorphous)]/I.sub.(200).times.100
I.sub.(200): Diffraction peak intensity at 200 plane
(20=22.5.degree.) of type I cellulose crystal I.sub.(amorphous):
Amorphous halo peak intensity for type I cellulose crystal, peak
intensity at angle of 4.5.degree. lower than diffraction angle at
200 plane (20=18.0.degree.).
<X-Ray Diffraction Measuring Conditions>
[0331] Apparatus: MiniFlex (Rigaku Corp.)
[0332] Operating shaft: 2.theta./.theta.
[0333] Source: CuK.alpha.
[0334] Measuring method: Continuous
[0335] Voltage: 40 kV
[0336] Current: 15 mA
[0337] Initial angle: 2.theta.=5.degree.
[0338] Final angle: 2.theta.=30.degree.
[0339] Sampling width: 0.020.degree.
[0340] Scan speed: 2.0.degree./min
[0341] Sample: Porous sheet attached to specimen holder.
(7) Weight-Average Molecular Weight (Mw) and Number-Average
Molecular Weight (Mn)
[0342] After weighing out 0.88 g of the porous sheet of the
chemically modified fine fibers or the fine fibers and chopping it
into small pieces with scissors, the pieces were gently stirred and
allowed to stand for one day after addition of 20 mL of purified
water. The water and solid portion were then separated by
centrifugation. After then adding 20 mL of acetone, the mixture was
gently stirred and allowed to stand for 1 day. The acetone and
solid portion were separated by centrifugation. After then adding
20 mL of N,N-dimethylacetamide, the mixture was gently stirred and
allowed to stand for 1 day. Centrifugal separation was again
carried out to separate the N,N-dimethylacetamide and solid
content, and then 20 mL of N,N-dimethylacetamide was added and the
mixture was gently stirred and allowed to stand for 1 day. The
N,N-dimethylacetamide and solid content were separated by
centrifugation, 19.2 g of a N,N-dimethylacetamide solution prepared
to a lithium chloride content of 8 mass % was added to the solid
portion, and the mixture was stirred with a stirrer while visually
confirming dissolution. The cellulose-dissolving solution was
filtered with a 0.45 .mu.m filter, and the filtrate was supplied as
a sample for gel permeation chromatography. The apparatus and
measuring conditions used were as follows.
[0343] Apparatus: Tosoh Corp. HLC-8120
[0344] Column: TSKgel SuperAWM-H (6.0 mm I.D..times.15
cm).times.2
[0345] Detector: RI detector
[0346] Eluent: N,N-dimethylacetamide (lithium chloride: 0.2%)
[0347] Calibration curve: Based on pullulan
(8) Alkali-Soluble Content
[0348] The alkali-soluble portion was determined by a method
described in non-patent literature (Mokushitsu Kagaku Jikken
Manual, ed. The Japan Wood Research Society, pp. 92-97, 2000),
subtracting the .alpha.-cellulose content from the holocellulose
content (Wise method).
(9) Mean Content for Acid-Insoluble Component and Mean Content for
Acid-Insoluble Component Per Unit Specific Surface Area
[0349] The acid-insoluble component was quantified by the Klason
method, described in non-patent literature (Mokushitsu Kagaku
Jikken Manual, ed. The Japan Wood Research Society, pp. 92-97,
2000). The sample of the absolutely dried chemically modified fine
fibers or the fine fibers was weighed and placed in a prescribed
container, 72 mass % concentrated sulfuric acid was added, and the
mixture was pressed with a glass rod until the contents became
uniform, after which an autoclave was used to dissolve the
cellulose and hemicellulose in the acid solution. The contents that
had been allowed to cool were filtered with glass fiber filter
paper to separate off the acid-insoluble component, which was
quantified to calculate the acid-insoluble component content of the
sample. The mean content was calculated as the number-average value
for 3 samples, and the value was recorded as the mean content for
the acid-insoluble component for the chemically modified fine
fibers. The mean content for the acid-insoluble component per
specific surface area (mass %g/m.sup.2) was calculated from this
calculated value.
(10) Thermal Decomposition Initiation Temperature (T.sub.D) and 1
wt % Weight Reduction Temperature (T.sub.1%)
[0350] Thermal analysis of the porous sheet was conducted by the
following method.
[0351] Apparatus: EXSTAR6000 by SII Co.
[0352] Sample: Circular pieces cut out from the porous sheet were
placed and stacked in an aluminum sample pan, in an amount of 10
mg.
[0353] Sample weight: 10 mg
[0354] Measuring conditions: Temperature increase from room
temperature to 150.degree. C. at a temperature-elevating rate of
10.degree. C./min, in a nitrogen flow of 100 ml/min, and holding at
150.degree. C. for 1 hour, followed by cooling to 30.degree. C.
Subsequent temperature increase from 30.degree. C. to 450.degree.
C. at a temperature-elevating rate of 10.degree. C./min.
[0355] T.sub.D calculation method: Calculation was from a graph
with temperature on the abscissa and weight reduction % on the
ordinate. Starting from the weight of chemically modified fine
fibers at 150.degree. C. (with essentially all of the moisture
content removed) (a weight reduction of 0 wt %) and increasing the
temperature, a straight line was obtained running through the
temperature at 1 wt % weight reduction and the temperature at 2 wt
% weight reduction. The temperature at the point of intersection
between this straight line and a horizontal (baseline) running
through the origin at weight reduction 0 wt %, was recorded as the
thermal decomposition initiation temperature (T.sub.D).
[0356] T.sub.1% calculation method: The temperature at 1 wt %
weight reduction used for T.sub.D calculation was recorded as the 1
wt % weight reduction temperature.
(11) 250.degree. C. Weight Change Rate (T.sub.250.degree. C.)
[0357] Apparatus: EXSTAR6000 by SII Co.
[0358] Sample: Circular pieces cut out from the porous sheet were
placed and stacked in an aluminum sample pan, in an amount of 10
mg.
[0359] Sample weight: 10 mg
[0360] Measuring conditions: Temperature increase from room
temperature to 150.degree. C. at a temperature-elevating rate of
10.degree. C./min, in a nitrogen flow of 100 ml/min, and holding at
150.degree. C. for 1 hour, followed by temperature increase from
150.degree. C. to 250.degree. C. at 10.degree. C./min and holding
at 250.degree. C. for 2 hours.
[0361] T.sub.250.degree. C. calculation method: Starting from
weight WO as the point where 250.degree. C. was reached, the weight
after holding at 250.degree. C. for 2 hours was recorded as W1, and
calculation was performed by the following formula.
T.sub.250.degree. C.(%):(W1-W0)/W0.times.100
(12) Change in YI (.DELTA.YI) after Heat Aging
[0362] The porous sheet was placed in an oven, and operation was
carried out for 3000 hours at 150.degree. C., atmospheric pressure
for heat aging. The degree of yellowing of the porous sheet before
heat aging and after heat aging was evaluated by YI measurement.
The YI measurement was carried out using a CM-700d
spectrocolorimeter by Konica Minolta Holdings, Inc. under
conditions with reflective mode (SCI+SCE), and a measuring diameter
of 3 mm, and the average value for the YI at 5 arbitrary locations
was determined. The YI before heat aging was subtracted from the YI
after heat aging to obtain .DELTA.YI.
(13) Sheet Strength after Heat Aging
[0363] The porous sheet was placed in an oven, and operation was
carried out for 3000 hours at 150.degree. C., atmospheric pressure
for heat aging. A 1 cm-wide, 3 cm-long sample strip was cut out
from the sample after heat aging, and pulled with forceps until it
tore. The sheet strength was evaluated as "Good" if it tore during
pulling and resistance was felt by the hand, the sheet strength was
evaluated as "Acceptable" if it tore during pulling and resistance
was not felt by the hand, and the sheet strength was evaluated as
"Poor" if the sample disintegrated at the location gripped by the
forceps during pulling.
(14) Storage Modulus Change Ratio
[0364] The obtained resin composite dumbbell was cut to 4 mm
width.times.30 mm length as a measuring sample. Using an EXSTAR
TMA6100 viscoelasticity meter (product of SII Nanotechnology,
Inc.), the storage modulus was measured under a nitrogen atmosphere
in tension mode, with a chuck distance of 20 mm and a frequency of
1 Hz. In order to relax distortion during molding of the dumbbell
during the measurement, the temperature was increased from room
temperature to a high temperature at 5.degree. C./min and then
lowered to 25.degree. C. at 5.degree. C./min and again increased
from 25.degree. C. to the high temperature at 5.degree. C./min, as
the temperature profile, and the storage modulus change ratio at
the time of the second temperature increase was measured. The value
of the storage modulus at low temperature divided by the storage
modulus at high temperature was compared, as the storage modulus
change ratio.
[0365] For Example I (first embodiment), the low temperature/high
temperature ratio was 100.degree. C./200.degree. C. for PA66 and
PA6, and 50.degree. C./100.degree. C. for PP and NBR.
[0366] For Example II (second embodiment), the low temperature/high
temperature ratio was 0.degree. C./150.degree. C. for PA66 and PA6,
and -50.degree. C./100.degree. C. for PP.
[0367] Generally, the storage modulus is lower at higher
temperature, and therefore the storage modulus change ratio is
greater than 1. A value closer to 1 may be considered to be lower
change in storage modulus at high temperature, and thus higher heat
resistance.
(15) Outer Appearance
[0368] The outer appearance of a sample obtained after forming a
composite of the kneaded resin was evaluated as "Poor" if there
were clear burnt deposits (browning), "Good" if no discoloration
was visible, or "Acceptable" if there were slight burnt
deposits.
(16) Linear Coefficient of Thermal Expansion (CTE)
[0369] The resin composite or resin was cut to 3 mm width.times.25
mm length as a measuring sample. It was measured using a model SII
TMA6100 in tension mode with a chuck distance of 10 mm and load of
5 g, under a nitrogen atmosphere, raising the temperature from room
temperature to 120.degree. C. at 5.degree. C./min, lowering the
temperature to 25.degree. C. at 5.degree. C./min, and then again
raising the temperature from 25.degree. C. to 120.degree. C. at
5.degree. C./min. The average linear coefficient of thermal
expansion from 30.degree. C. to 100.degree. C. at the time of the
second temperature increase was measured.
(17) Flexural Modulus Increase Ratio
[0370] An injection molding machine was used to mold an 80
mm.times.10 mm.times.4 mm test piece, and the flexural modulus of
each test piece was measured according to ISO178. The obtained
flexural modulus was divided by the flexural modulus of the base
resin containing no filler component (that is, cellulose or other
filler) to calculate the flexural modulus increase ratio. That is,
the value for a test piece with no increase in flexural modulus was
1.0.
(18) Flexural Strength Increase Ratio
[0371] An injection molding machine was used to mold an 80
mm.times.10 mm.times.4 mm test piece, and the flexural strength of
each test piece was measured according to ISO178. The obtained
flexural strength was divided by the flexural strength of the base
resin containing no filler component, to calculate the flexural
strength increase ratio. That is, the value for a test piece with
no increase in flexural strength was 1.0.
TABLE-US-00001 TABLE 1 Cellulose material Resin material Dispersion
stabilizer Parts Parts Parts Sample name Name by mass Name by mass
Name by mass Example 1-1 Resin composite 1-1 Chemically modified
fine fibers 1-1 2 PA66 98 -- -- Example 1-2 Resin composite 1-2
Chemically modified fine fibers 1-1 4 PA66 96 -- -- Example 1-3
Resin composite 1-3 Chemically modified fine fibers 1-1 8 PA66 92
-- -- Example 1-4 Resin composite 1-4 Chemically modified fine
fibers 1-2 4 PA66 96 -- -- Example 1-5 Resin composite 1-5
Chemically modified fine fibers 1-1 4 NBR 96 -- -- Example 1-6
Resin composite 1-6 Chemically modified fine fibers 1-1 4 PA6 96 --
-- Example 1-7 Resin composite 1-7 Chemically modified fine fibers
1-3 4 PP 96 -- -- Example 1-8 Resin composite 1-8 Chemically
modified fine fibers 1-3 4 PP 95 RCW-20 1 Example 1-9 Resin
composite 1-9 Chemically modified fine fibers 1-3 4 PP 95 DMSO 1
Example 1-10 Resin composite 1-10 Chemically modified fine fibers
1-3 8 PP 92 -- -- Example 1-11 Resin composite 1-11 Chemically
modified fine fibers 1-3 8 PP 90 RCW-20 2 Example 1-12 Resin
composite 1-12 Chemically modified fine fibers 1-3 8 PP 90 DMSO 2
Example 1-13 Resin composite 1-13 Chemically modified fine fibers
1-2 2 PA66 92 RCW-20 2 Cellulose whiskers SC900 4 Example 1-14
Resin composite 1-14 Chemically modified fine fibers 1-2 2 PA66 90
W-260 4 Cellulose whiskers SC900 4 Example 1-15 Resin composite
1-15 Chemically modified fine fibers 1-3 4 PP 90 RCW-20 2 Cellulose
whiskers SC900 4 Example 1-16 Resin composite 1-16 Chemically
modified fine fibers 1-3 4 PP 88 W-260 4 Cellulose whiskers SC900 4
Example 1-17 Resin composite 1-17 Chemically modified fine fibers
1-2 10 PA6 88 RCW-20 2 Example 1-18 Resin composite 1-18 Chemically
modified fine fibers 1-3 4 PA6 90 RCW-20 2 Cellulose whiskers SC900
4 Example 1-19 Resin composite 1-19 Chemically modified fine fibers
1-4 10 PA6 88 RCW-20 2 Example 1-20 Resin composite 1-20 Chemically
modified fine fibers 1-5 10 PA6 88 RCW-20 2 Comp. Example 1-1 Resin
composite 1-A Fine fibers 1-1 4 PA66 96 -- -- Comp. Example 1-2
Resin 1-1 -- -- PP 100 -- -- Comp. Example 1-3 Resin composite 1-B
-- -- PP 90 Talc 10 Comp. Example 1-4 Resin 1-2 -- -- PA66 100 --
-- Comp. Example 1-5 Resin composite 1-C -- -- PA66 90 Talc 10
Comp. Example 1-6 Resin composite 1-D Chemically modified fine
fibers 1-6 2 PA66 98 -- -- Comp. Example 1-7 Resin composite 1-E
Chemically modified fine fibers 1-6 4 PA66 96 -- -- Comp. Example
1-8 Resin composite 1-F Chemically modified fine fibers 1-6 8 PA66
92 -- -- Comp. Example 1-9 Resin composite 1-G Fine fibers 1-1 10
PA6 88 RCW-20 2 Comp. Example 1-10 Resin composite 1-H Chemically
modified fine fibers 1-6 10 PA6 88 RCW-20 2 Comp. Example 1-11
Resin composite 1-I Chemically modified fine fibers 1-7 10 PA6 88
RCW-20 2
TABLE-US-00002 TABLE 2 Mean content for acid- Mean insoluble
content for component per Specific IR IR DS Non- Degree of acid-
unit specific Fiber surface Index Index uniformity crystal-
insoluble surface area Material diameter area 1370 1030 DS ratio CV
linity component mass % Name type Nm M.sup.2/g -- -- -- -- % % mass
% g/m.sup.2 Prod. Chemically modified Filter 180 15 1.08 0.21 0.87
1.44 19 75 0.18 0.01 Example 1-1 fine fibers 1-1 paper Prod.
Chemically modified Linter 65 41 1.05 0.20 0.84 1.39 18 65 4.7 0.11
Example 1-2 fine fibers 1-2 Prod. Chemically modified Linter 120 23
1.12 0.22 0.93 1.31 29 75 4.7 0.20 Example 1-3 fine fibers 1-3
Prod. Chemically modified Linter 125 22 0.44 0.05 0.20 1.61 39 81
4.7 0.21 Example 1-4 fine fibers 1-4 Prod. Chemically modified
Linter 115 24 1.44 0.39 1.40 1.14 14 71 4.7 0.20 Example 1-5 fine
fibers 1-5 Prod. Chemically modified Linter 75 36 1.01 0.19 0.79
1.92 51 74 4.7 0.13 Example 1-6 fine fibers 1-6 Prod. Fine fibers
1-1 Celish 100 27 -- -- -- -- -- 82 2.5 0.09 Example 1-7 Prod.
Chemically modified Filter 44 61 1.36 0.31 1.28 1.05 15 71 0.18
0.003 Example 1-8 fine fibers 1-7 paper
TABLE-US-00003 TABLE 3 Thermal 250.degree. C. Storage Outer
Flexural Flexural decomposition 1% Weight Weight modulus appearance
elasticity strength initiation reduction change Resin change Good,
increase increase temperature temperature rate material ratio*
Acceptable, CTE ratio ratio Name .degree. C. .degree. C. % -- --
Poor ppm/k -- -- Example 1-1 Resin composite 1-1 289 307 -1.2 PA66
1.85 Good 68 1.36 1.33 Example 1-2 Resin composite 1-2 289 307 -1.2
PA66 1.70 Good 65 1.46 1.40 Example 1-3 Resin composite 1-3 289 307
-1.2 PA66 1.61 Good 62 1.51 1.40 Example 1-4 Resin composite 1-4
288 307 -1.3 PA66 1.73 Good 66 1.34 1.39 Example 1-5 Resin
composite 1-5 289 307 -1.2 NBR 1.20 Good 63 1.41 1.42 Example 1-6
Resin composite 1-6 289 307 -1.2 PA6 2.12 Good 73 1.44 1.42 Example
1-7 Resin composite 1-7 289 308 -1.1 PP 1.92 Good 56 1.62 1.46
Example 1-8 Resin composite 1-8 289 308 -1.1 PP 1.76 Good 46 1.68
1.51 Example 1-9 Resin composite 1-9 289 308 -1.1 PP 1.79 Good 48
1.80 1.60 Example 1-10 Resin composite 1-10 289 308 -1.1 PP 1.80
Good 50 1.91 1.68 Example 1-11 Resin composite 1-11 289 308 -1.1 PP
1.76 Good 43 2.00 1.72 Example 1-12 Resin composite 1-12 289 308
-1.1 PP 1.80 Good 47 2.10 1.82 Example 1-13 Resin composite 1-13
288 307 -1.3 PA66 1.63 Good 42 1.82 1.60 Example 1-14 Resin
composite 1-14 288 307 -1.3 PA66 1.81 Good 43 1.75 1.55 Example
1-15 Resin composite 1-15 289 308 -1.1 PA66 1.48 Good 41 2.33 2.00
Example 1-16 Resin composite 1-16 289 308 -1.1 PA66 1.69 Good 43
2.18 1.89 Example 1-17 Resin composite 1-17 288 307 -1.3 PA6 1.89
Good 39 1.78 1.70 Example 1-18 Resin composite 1-18 288 307 -1.3
PA6 1.99 Good 45 1.65 1.65 Example 1-19 Resin composite 1-19 271
289 -2.7 PA6 2.01 Acceptable 44 1.43 1.39 Example 1-20 Resin
composite 1-20 293 309 -1.1 PA6 1.75 Good 33 1.68 1.71 Comp. Resin
composite 1-A 225 243 -16.4 PA66 2.39 Poor 80 1.01 0.99 Example 1-1
Comp. Resin 1-1 -- -- -- PP 2.43 Good 110 -- -- Example 1-2 Comp.
Resin composite 1-B -- -- -- PP 2.20 Good 85 1.12 1.04 Example 1-3
Comp. Resin 1-2 -- -- -- PA66 2.50 Good 80 -- -- Example 1-4 Comp.
Resin composite 1-C -- -- -- PA66 2.29 Good 60 1.22 1.10 Example
1-5 Comp. Resin composite 1-D 263 281 -3.0 PA66 2.30 Acceptable 77
1.06 1.03 Example 1-6 Comp. Resin composite 1-E 263 281 -3.0 PA66
2.25 Acceptable 71 1.16 1.11 Example 1-7 Comp. Resin composite 1-F
263 281 -3.0 PA66 2.12 Poor 70 1.22 1.18 Example 1-8 Comp. Resin
composite 1-G 225 243 -16.4 PA6 2.05 Poor 65 1.23 1.16 Example 1-9
Comp. Resin composite 1-H 263 281 -3.0 PA6 2.04 Poor 58 1.27 1.27
Example 1-10 Comp. Resin composite 1-I 269 287 -2.8 PA6 2.02 Poor
63 1.20 1.17 Example 1-11 *Rate of change at 100.degree.
C./200.degree. C. for PA66 and PA6, rate of change at 50.degree.
C./100.degree. C. for PP and NBR
TABLE-US-00004 TABLE 4 Alkali- Specific soluble Degree of surface
portion crystallinity area Mw Mw/Mn (mass %) (%) (m.sup.2/g) DS
Example 2-1 Chemically modified 380,000 4.7 3.6 75 36 0.82 fine
fibers 2-1 Example 2-2 Chemically modified 410,000 3.2 7.1 71 46
0.78 fine fibers 2-2 Example 2-3 Chemically modified 190,000 2.4
6.5 65 42 0.95 fine fibers 2-3 Example 2-4 Chemically modified
340,000 5.4 3.4 75 22 0.90 fine fibers 2-4 Example 2-5 Chemically
modified 320,000 2.5 10.5 80 38 0.87 fine fibers 2-5 Example 2-6
Chemically modified 160,000 2.0 8.3 64 39 0.97 fine fibers 2-6
Comp. Chemically modified 270,000 6.4 18.7 68 49 1.03 Example 2-1
fine fibers 2-7 Comp. Chemically modified 600,000 8.7 12.5 62 44
0.95 Example 2-2 fine fibers 2-8 Comp. Chemically modified 140,000
1.8 12.2 61 44 1.10 Example 2-3 fine fibers 2-9 Comp. Chemically
modified 160,000 4.2 4.1 56 50 1.30 Example 2-4 fine fibers 2-10
Comp. Chemically modified 280,000 2.2 12.1 77 56 0.95 Example 2-5
fine fibers 2-11 Comp. Non-chemically-modi- 240,000 8.6 10 82 27 0
Example 2-6 fied fine fibers 2-1 1% Weight 250.degree. C. reduction
weight CV Td Temperature Rate of Sheet (%) (.degree. C.) (.degree.
C.) change (%) .DELTA.YI strength Example 2-1 19 290 309 -1.6 22
Good Example 2-2 17 273 282 -2.7 29 Good Example 2-3 22 290 309
-1.2 18 Good Example 2-4 29 289 308 -1.1 21 Acceptable Example 2-5
24 289 307 -1.2 36 Acceptable Example 2-6 25 290 308 -1.1 27
Acceptable Comp. 19 258 273 -7.1 42 Poor Example 2-1 Comp. 26 253
266 -3.3 34 Poor Example 2-2 Comp. 31 289 307 -1.1 39 Poor Example
2-3 Comp. 19 266 276 -4.8 47 Poor Example 2-4 Comp. 27 290 309 -1.0
47 Acceptable Example 2-5 Comp. -- 225 243 -16.5 65 Poor Example
2-6
TABLE-US-00005 TABLE 5 Resin Cellulose Additive Cellulose whiskers
Storage Outer Parts Parts Parts Parts modulus appear- CTE Sample
Name by mass Name by mass Name by mass Name by mass change* ance
ppm/K Example 2-7 Resin PA66 98 Chemically 2 7.0 Good 76 composite
2-1 modified fine fibers 2-1 Example 2-8 Resin PA66 90 Chemically
10 4.0 Good 30 composite 2-2 modified fine fibers 2-1 Example 2-9
Resin PA6 90 Chemically 10 4.5 Good 37 composite 2-3 modified fine
fibers 2-1 Example 2-10 Resin PP 96 Chemically 4 7.4 Good 68
composite 2-4 modified fine fibers 2-1 Example 2-11 Resin PA6 90
Chemically 7 RCW-20 3 4.3 Good 33 composite 2-5 modified fine
fibers 2-1 Example 2-12 Resin PA6 88 Chemically 7 RCW-20 3 SC900 2
4.6 Good 35 composite 2-6 modified fine fibers 2-1 Comp. Resin PA6
90 Fine fibers 2-1 10 5.3 Poor 50 Example 2-7 composite 2-7 Comp.
Resin PA6 90 Chemically 10 4.2 Poor 33 Example 2-8 composite 2-8
modified fine fibers 2-7 *Change at 0.degree. C./150.degree. C. for
PA66 and PA6, change at -50.degree. C./100.degree. C. for PP
[0372] Based on the evaluation results for Example I, using
chemically modified fine fibers with a high thermal decomposition
initiation temperature was found to yield a resin composite with
high heat resistance and excellent outer appearance of the resin
composite and excellent mechanical properties (storage modulus,
CTE, flexural modulus and flexural strength). Using chemically
modified fine fibers with a low thermal decomposition initiation
temperature, on the other hand, had a high level of discoloration
and could not yield a resin composite satisfying all of the
physical properties, including outer appearance and mechanical
properties.
[0373] Based on the evaluation results for Example II, using
chemically modified fine fibers with a high Mw, low Mw/Mn, low
alkali-soluble portion and high degree of crystallinity yielded a
resin composite with high heat resistance, and excellent outer
appearance of the resin composite, storage modulus and CTE.
[0374] Both Examples I and II demonstrated that using resins with
high melting points resulted in more excellent outer appearance and
resin composites with excellent mechanical properties.
INDUSTRIAL APPLICABILITY
[0375] The resin composite of the invention can be suitably used as
a resin composite with high heat resistance that is desirable for
on-vehicle use, by using chemically modified fine fibers with a
high thermal decomposition initiation temperature.
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