U.S. patent application number 13/658945 was filed with the patent office on 2013-02-21 for cellulose-based masterbatch with networked structure, application thereof and method for preparing the same.
This patent application is currently assigned to TAIWAN TEXTILE RESEARCH INSTITUTE. The applicant listed for this patent is Taiwan Textile Research Institute. Invention is credited to Su-Chen Chen, Nai-Yun Liang, Sheng-Jen Lin, Wei-Peng Lin, Chao-Huei Liu.
Application Number | 20130046071 13/658945 |
Document ID | / |
Family ID | 44243584 |
Filed Date | 2013-02-21 |
United States Patent
Application |
20130046071 |
Kind Code |
A1 |
Chen; Su-Chen ; et
al. |
February 21, 2013 |
Cellulose-Based Masterbatch with Networked Structure, Application
Thereof and Method for Preparing the Same
Abstract
Disclosed herein is a thermoplastic cellulosic composition for
preparing a cellulose-based masterbatch and/or a cellulose-based
fiber with a networked structure. In one example, the thermoplastic
cellulosic composition includes an esterified cellulose present in
a range of about 80 wt % to about 95 wt %, polyethylene glycol
present in a range of about 4.5 wt % to about 12 wt %, a
tri-functional cross-linking agent present in a range of about 0.01
wt % to about 3 wt %, an initiator present in a range of about 0.01
wt % to about 0.15 wt %, and a dispersing agent present in a range
of about 0.01 wt % to about 5 wt %.
Inventors: |
Chen; Su-Chen; (Tu-Chen
City, TW) ; Lin; Sheng-Jen; (Tu-Chen City, TW)
; Liang; Nai-Yun; (Taipei City, TW) ; Liu;
Chao-Huei; (Taipei City, TW) ; Lin; Wei-Peng;
(Sijhih City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Textile Research Institute; |
Tu-Chen City |
|
TW |
|
|
Assignee: |
TAIWAN TEXTILE RESEARCH
INSTITUTE
Tu-Chen City
TW
|
Family ID: |
44243584 |
Appl. No.: |
13/658945 |
Filed: |
October 24, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12814677 |
Jun 14, 2010 |
8329837 |
|
|
13658945 |
|
|
|
|
Current U.S.
Class: |
527/312 ;
264/176.1 |
Current CPC
Class: |
C08K 5/053 20130101;
C08K 5/053 20130101; C08L 1/10 20130101; C08K 5/053 20130101; C08L
1/12 20130101; C08L 1/14 20130101; C08K 5/053 20130101; C08L 1/10
20130101; C08L 2666/14 20130101 |
Class at
Publication: |
527/312 ;
264/176.1 |
International
Class: |
C08F 251/02 20060101
C08F251/02; D01D 5/10 20060101 D01D005/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2010 |
TW |
99109671 |
Claims
1. A thermoplastic cellulosic composition, comprising: an
esterified cellulose in a range of about 80 wt % to about 95 wt %;
polyethylene glycol in a range of about 4.5 wt % to about 12 wt %;
a tri-functional cross-linking agent in a range of about 0.01 wt %
to about 3 wt %; an initiator in a range of about 0.01 wt % to
about 0.15 wt %; and a dispersing agent in a range of about 0.01 wt
% to about 5 wt %.
2. The composition of claim 1, wherein the esterified cellulose is
cellulose acetate, cellulose acetate propionate, cellulose acetate
butyrate, cellulose acetate pentanoate, cellulose propionate
n-butyrate, cellulose acetate laurate, cellulose acetate stearate
or the esterified cellulose.
3. The composition of claim 1, wherein the esterified cellulose is
cellulose acetate propionate having an esterification ratio of at
least about 50%.
4. The composition of claim 1, wherein the polyethylene glycol has
a molecular weight of about 600-10,000 Da.
5. The composition of claim 1, wherein the tri-functional
cross-linking agent is triallyl amine, triallyl trimesate (TAM),
triallyl cyanurate (TAC), triallyl isocynaurate (TAIC),
triallyl-ammoniumcyanurate or triacryloylhexahydro-1,3,5-triazine
(TAT).
6. The composition of claim 1, wherein the initiator is potassium
persulfate, azobisisobutyronitrile, potassium peroxide, or benzyl
dimethyl ketal.
7. The composition of claim 1, wherein the dispersing agent is
selected from a group consisting of C.sub.15-38 alkanes,
C.sub.15-38 esters, C.sub.15-38 organic acids, and a mixture
thereof.
8. A method for preparing a cellulose-based fiber with a networked
structure, comprising: preparing a cellulose-based masterbatch; and
melt spinning the cellulose-based masterbatch at a spinning
temperature of about 220-280.degree. C. and a spinning speed of
about 500-3000 m/min, wherein the cellulose-based masterbatch
comprises: an esterified cellulose in a range of about 80 wt % to
about 95 wt %; polyethylene glycol in a range of about 4.5 wt % to
about 12 wt %; a tri-functional cross-linking agent in a range of
about 0.01 wt % to about 3 wt %; an initiator in a range of about
0.01 wt % to about 0.15 wt %; and a dispersing agent in a range of
about 0.01 wt % to about 5 wt %, wherein each of the tri-functional
cross-linking agent has three functional groups, and at least part
of the tri-functional cross-linking agent has its three functional
groups respectively connected to the molecular chain of the
esterified cellulose molecule or the polyethylene glycol molecule,
thereby forming the networked structure.
9. A cellulose-based fiber with a networked structure which is
prepared from a masterbatch comprising: an esterified cellulose in
a range of about 80 wt % to about 95 wt %; polyethylene glycol in a
range of about 4.5 wt % to about 12 wt %; a tri-functional
cross-linking agent in a range of about 0.01 wt % to about 3 wt %;
an initiator in a range of about 0.01 wt % to about 0.15 wt %; and
a dispersing agent in a range of about 0.01 wt % to about 5 wt %,
wherein each of the tri-functional cross-linking agent has three
functional groups, and at least part of the tri-functional
cross-linking agent has its three functional groups respectively
connected to the molecular chain of the esterified cellulose
molecule or the polyethylene glycol molecule, thereby forming the
networked structure.
10. The cellulose-based fiber of claim 9, wherein the
cellulose-based fiber has a breaking tenacity no less than about
0.7-1.4 gf/den.
Description
RELATED APPLICATIONS
[0001] This is a divisional application of patent application Ser.
No. 12/814,677 filed on Jun. 14, 2010, now allowed. The prior
application Ser. No. 12/814,677 claims the benefit of Taiwan Patent
Application 99109671, filed Mar. 30, 2010, the disclosures of which
are incorporated herein by reference in their entirety.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to cellulose-based fibers.
More particularly, the present invention relates to cellulose-based
fibers with a networked structure.
[0004] 2. Description of Related Art
[0005] Cellulose fibers, or cellulosic fibers, are artificial
fibers which were developed as early as the end of the 19.sup.th
century. For example, natural celluloses are treated with a
complicated process known as "cuprammonium process" to produce the
purified (or regenerated) cellulose; alternatively, natural
celluloses are chemically modified to yield the esterified
celluloses such as cellulose acetate, and then, cellulose fibers
are prepared from the resulting celluloses or cellulose
derivatives. In the beginning of the 20.sup.th century, artificial
fibers including rayon and acetate fibers have gained their
positions in the market.
[0006] However, owing to the soaraway progress of the petrochemical
technology, the low-cost and easy-to-produce synthetic fibers, such
as nylons and polyester fibers, took the place of the artificial
fibers as the mainstream products of the textile industry, by the
middle of the 20.sup.th century.
[0007] Recently, the depleting reserves and rising prices of
petroleum drive the textile industry to seek fibers other than
synthetic fibers. Hence, cellulose-based fibers once again attract
the research and development attention.
[0008] Conventional methods for preparing cellulose-based fibers
include wet spinning, dry spinning and melt spinning.
[0009] Both wet spinning and dry spinning processes will use
organic solvents such as carbon disulfide and dichloromethane. To
prevent those organic solvents from damaging the environment, the
solvents must be recycled and thereby inevitably increases the
complexity and cost of the processes.
[0010] Melt spinning process involves in adding a great amount of a
low molecular weight plasticizer (molecular weight no greater than
1000 D) in the esterified cellulose to obtain a melt-spinnable
composition (masterbatch) which is later melt spun into
cellulose-based fibers. Generally, the amount of the plasticizer in
the melt-spinnable composition may be 50-90 wt %. However,
low-molecular weight plasticizer usually cannot withstand the high
spinning temperature, and hence the conventional spinning
temperature is controlled under 260.degree. C.; otherwise, the
cellulose molecules would become yellowish-brown.
[0011] During the melt spinning process, spinning temperature is
positively related to the flowability of the molten which, in turn,
is positively related to the spinning speed. Therefore, owing to
the limitation of the spinning temperature, the spinning speed of
the cellulose-based fiber is less than commercially desirable. In
addition, large amount of the plasticizer (about 50-90 wt %) often
results in the phase separation between the plasticizer and the
cellulose, thereby worsening the breaking tenacity of the resultant
fiber. The above mentioned disadvantages hinder the melt spun
cellulose-based fiber from commercialization.
[0012] In view of the foregoing, there exists an urgent need in the
related art to provide a novel cellulose-based fiber capable of
withstanding a higher spinning temperature and a method for
preparing the same.
SUMMARY
[0013] The following presents a simplified summary of the
disclosure in order to provide a basic understanding to the reader.
This summary is not an extensive overview of the disclosure and it
does not identify key/critical elements of the present invention or
delineate the scope of the present invention. Its sole purpose is
to present some concepts disclosed herein in a simplified form as a
prelude to the more detailed description that is presented
later.
[0014] In one aspect, the present invention is directed to a
thermoplastic cellulosic composition. According to embodiments of
the present invention, the amount of the plasticizer of such
composition is substantially lower than that of the conventional
art, which may facilitate in improving the physical property of the
cellulose-based fiber thus-obtained. Moreover, the masterbatch
prepared from such composition has a higher activation energy of
pyrolysis and hence a better heat-resistance. Accordingly, the
masterbatch is suitable for use in a melt spinning process with a
higher spinning temperature and spinning speed.
[0015] According to embodiments of the present invention, the
thermoplastic cellulosic composition comprises an esterified
cellulose present in a range of about 80 wt % to about 95 wt %,
polyethylene glycol present in a range of about 4.5 wt % to about
12 wt %, a tri-functional cross-linking agent present in a range of
about 0.01 wt % to about 3 wt %, an initiator present in a range of
about 0.01 wt % to about 0.15 wt %, and a dispersing agent present
in a range of about 0.01 wt % to about 5 wt %.
[0016] In another aspect, the present invention is directed to a
cellulose-based masterbatch with a cellulose-based masterbatch with
a networked structure. The cellulose-based masterbatch is prepared
from the thermoplastic cellulosic composition according to the
aspect and/or embodiment(s) described hereinabove, and is suitable
for use in a melt spinning process with a higher spinning
temperature and spinning speed.
[0017] According to one embodiment of the present invention, the
cellulose-based masterbatch comprises about 80 wt % to about 95 wt
% of an esterified cellulose, about 4.5 wt % to about 12 wt % of
polyethylene glycol, about 0.01 wt % to about 3 wt % of a
tri-functional cross-linking agent, about 0.01 wt % to about 0.15
wt % of an initiator and about 0.01 wt % to about 5 wt % of a
dispersing agent. Each of the a tri-functional cross-linking agent
molecule has three functional groups, and at least part of the a
tri-functional cross-linking agent has its three functional groups
respectively cross-linked with the molecular chain of the
esterified cellulose molecule(s) and the polyethylene glycol
molecule(s), thereby forming a networked structure.
[0018] According to embodiments of the present invention, the
cellulose-based masterbatch is prepared by a method comprising the
steps as follows. First, a thermoplastic cellulosic composition
according to the aspect/embodiment(s) described hereinabove is
prepared. Then, the composition is compounded at a temperature of
about 160-220.degree. C. The compounded composition is granulized
to form the cellulose-based masterbatch.
[0019] In yet another aspect, the present invention is directed to
a cellulose-based fiber with a networked structure. The networked
structure may improve the polymer rigidity; accordingly, the
cellulose-based fiber may exhibit better breaking tenacity.
[0020] According to optional embodiments of the present invention,
the cellulose-based fiber with a networked structure has a breaking
tenacity of about 0.7-1.4 gf/den.
[0021] According to various embodiments of the present invention,
the cellulose-based fiber with a networked structure is prepared
from the masterbatch according to the above-mentioned
aspect/embodiment(s) of the present invention, and/or prepared by
the method according to the above-mentioned aspect/embodiment(s) of
the present invention.
[0022] Many of the attendant features will be more readily
appreciated as the same becomes better understood by reference to
the following detailed description.
DETAILED DESCRIPTION
[0023] The detailed description provided below in connection with
the appended drawings is intended as a description of the present
examples and is not intended to represent the only forms in which
the present example may be constructed or utilized. The description
sets forth the functions of the example and the sequence of steps
for constructing and operating the example. However, the same or
equivalent functions and sequences may be accomplished by different
examples.
[0024] During the melt spinning process, the spinning temperature
often depends on the heat-resistance of the masterbatch, whereas
the spinning speed depends on the flowability of the molten. As
discussed in the background section, the heat-resistance of the
conventional cellulose-based masterbatch is less desirable, and
hence it is inoperable to increase the spinning temperature of the
masterbatch. Since the spinning temperature is positively related
to the flowability of the molten, the lower spinning temperature
may impose limitations on the spinning speed. Hence, improving the
heat resistance of the cellulose-based masterbatch may assist in
attaining the commercialization of the cellulose-based fiber.
[0025] It is for the above-mentioned purpose, and with that
objective in view, in one aspect, the present invention is directed
thermoplastic cellulosic compositions and methods for preparing a
cellulose-based masterbatch with a networked structure therefrom.
Such cellulose-based masterbatch with a networked structure has a
higher activation energy of pyrolysis (no less than 180 kJ/mol),
thereby improving the heat resistance of the cellulose-based
masterbatch during the spinning process. Accordingly, the spinning
temperature may be increased, which in turn facilitates improvement
in the flowability of the molten, and hence, the spinning
speed.
[0026] According to embodiments of the present invention, the
thermoplastic cellulosic composition comprises an esterified
cellulose present in a range of about 80 wt % to about 95 wt %,
polyethylene glycol present in a range of about 4.5 wt % to about
12 wt %, a tri-functional cross-linking agent present in a range of
about 0.01 wt % to about 3 wt %, an initiator present in a range of
about 0.01 wt % to about 0.15 wt %, and a dispersing agent present
in a range of about 0.01 wt % to about 5 wt %.
[0027] According to embodiments of the present invention, a method
for preparing a masterbatch using such thermoplastic cellulosic
composition includes the steps as follows. First, a thermoplastic
cellulosic composition according to the aspect/embodiment(s)
described hereinabove is prepared. Then, the composition is
compounded at a temperature of about 160-220.degree. C. The
compounded composition is granulized to form the cellulose-based
masterbatch with a networked structure.
[0028] Specifically, the constituents of the composition are mixed
in accordance with the specified weight ratio. Then, the mixed
composition is compounded. According to various embodiments of the
present invention, the compounding temperature should be carefully
controlled in the range of about 160.degree. C. to about
220.degree. C.; preferably, in the range of about 180-200.degree.
C. Afterwards, the compounded composition is pelletized to obtain
the cellulose-based masterbatch.
[0029] As discussed hereinabove, the heat resistance of the
polyethylene glycol is not satisfactory. Therefore, compounding the
thermoplastic cellulosic composition at a temperature higher than
220.degree. C. may imperil the processability of the resultant
masterbatch. For example, the compounding temperature may be about
160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215 or
200.degree. C.
[0030] Generally, the compounding step is carried at a compounding
temperature of about 180-220.degree. C.; preferably, at about
180-200.degree. C. For example, the compounding temperature can be
about 180, 185, 190, 195, 200, 205, 210, 215 or 200.degree. C.
[0031] In some embodiments, the mixing, compounding and pelletizing
steps are all carried out in an extruder. Any customary extruders
and extrusion techniques for preparing masterbatches may be
employed according to the embodiments of the present invention. A
well-known compounding apparatus may include, but is not limited
to, a single screw extruder, a twin screw extruder, a multi screw
extruder, a brabender, and a kneader.
[0032] Alternatively, the mixing, compounding and/or pelletizing
steps can be carried out in separate equipments. In one example,
the mixing step may be done in any suitable container or mixer, and
then, the mixed composition is fed into an extruder for the
compounding and pelletizing.
[0033] According to the principles and spirits of the present
invention, the thermoplastic cellulosic composition adopts a
tri-functional cross-linking agent. During the compounding step,
the three functional groups (such as ally groups) of the
tri-functional cross-linking agent may react with the functional
groups of the esterified cellulose molecule and/or the polyethylene
glycol molecule thereby forming a networked structure having the
cross-linked esterified cellulose and polyethylene glycol.
Regarding the polymers for use in melt spinning process, such
networked structure may be an advantageous property, for it may
improve the heat-resistance of the polymer
[0034] In the conventional art, unsatisfactory problems such as
agglomeration of the plasticizer (polyethylene glycol) and phase
separation between the polyethylene glycol and the esterified
cellulose are commonly seen. The method for preparing a masterbatch
according to the present invention may advantageously ameliorate
such problems. Generally, in the masterbatch with a networked
structure provided herein, part of the plasticizer molecules would
connect to the molecular chain(s) of the esterified cellulose
molecule(s) via the cross-linking agent. Without being bound to any
theory, it is believed that by connecting part of the plasticizer
molecules to the esterified cellulose molecule(s), the possibility
of the phase separation and agglomeration can be reduced. In
addition, lesser amount plasticizer is necessary to achieve the
desired thermal processability of the masterbatch, as compared with
the conventional art. For example, according to embodiments of the
present invention, the amount of the plasticizer in the
thermoplastic cellulosic composition may be about 4.5, 5, 5.5, 6,
6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12 wt %.
[0035] It should be noted that in the masterbatch with a networked
structure provided herein, the molecular chains of molecules within
the polymer are connected to one another, thereby resulting in a
discontinuous phase across the polymer. Accordingly, the mobility
of the plasticizer (polyethylene glycol) within the polymer is
limited. Therefore, the plasticizer according to embodiments of the
present invention may have a lower molecular weight.
[0036] For example, polyethylene glycol having a molecular weight
of about 600-10,000 Da may be used. For the plasticizer having a
molecular weight greater than 10,000 Da, the plasticizer may not
evenly distribute across the polymer. More specifically, the
molecular weight of polyethylene glycol may be about 600, 700, 800,
900, 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000
or 10,000 Da.
[0037] According to the principles and spirits of the present
invention, any suitable esterified cellulose may be used in the
composition. Examples of the esterified cellulose include, but are
not limited to: cellulose acetate, cellulose acetate propionate
(CAP), cellulose acetate butyrate (CAB), cellulose acetate
pentanoate, cellulose propionate n-butyrate, cellulose acetate
laurate and cellulose acetate stearate. In addition, the
composition may comprise a mixture consisting of at least two
esterified celluloses.
[0038] According to one embodiment of the present invention, the
esterified cellulose may be cellulose acetate propionate having an
esterification ratio that is no less than about 50%. Cellulose
acetate propionate is a cellulose ester wherein the hydroxyl groups
of cellulose are substituted with acetyl and propionyl. The term
"esterification ratio that is no less than about 50%" means that
the acetyl and propionyl groups together substitute at least about
50% of the hydroxyl groups. Esterified cellulose having an
esterification ratio no less than about 50% is suitable for use in
thermal processing. Preferably, the esterification ratio of the
esterified cellulose is at least about 75%; more preferably, at
least about 90%. For example, the esterification ratio of the
esterified cellulose may be about 50, 55, 60, 65, 70, 75, 80, 85,
90, 95, 98% or higher.
[0039] According to the principles and spirits of the present
invention, the thermoplastic cellulosic composition may include any
cross-linking agent having three functional groups capable of
connecting cellulose molecule(s) and/or polyethylene glycol
molecule(s). Illustrative examples of bifunctional chain extender
include, but are not limited to, triallyl amine, triallyl trimesate
(TAM), triallyl cyanurate (TAC), triallyl isocynaurate (TAIC),
triallyl-ammoniumcyanurate and triacryloylhexahydro-1,3,5-triazine
(TAT). For example, triallyl isocynaurate is used in working
examples presented hereinafter.
[0040] One problem faced by the conventional cross-linking
technique is that the cross-linking level of the resultant
masterbatch cannot be controlled in a repeatable way. Hence, during
the melt spinning process, the molten of the conventional
masterbatch would become very thick such that the spinning process
cannot proceed. The novel cross-linking process according to
embodiments of the present invention, on the other hand, provides a
solution to the above-mentioned problem at least by carefully
controlling the amount of the tri-functional cross-linking agent.
Specifically, the masterbatch prepared by the compounding method
provided herein, would exhibit a stable spinning pressure of about
40-50 bar during the melt spinning process.
[0041] According to embodiments of the present invention, the
amount of the tri-functional cross-linking agent in the composition
may be about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09,
0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4,
1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8,
2.9 or 3 wt %.
[0042] The choice of the initiator often depends on the
trifunctional cross-linking agent to be used. Illustrative examples
of initiators include, but are not limited to, potassium
persulfate, azobisisobutyronitrile, potassium peroxide, and benzyl
dimethyl ketal (BDK).
[0043] Generally, only a small amount of the initiator is operable
to initiate the cross-linking reaction. Specifically, the weight
percent of the initiator of the thermoplastic cellulosic
composition is about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07,
0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15 wt %.
[0044] The dispersing agent may assist in uniformally distributing
the constituents within the thermoplastic cellulosic composition.
Generally, the dispersing agent may be C.sub.15-38 alkanes,
C.sub.15-38 esters, C.sub.15-38 organic acids, or a mixture
thereof. In the working examples presented hereinafter, the
composition comprises about 0.01 wt % to about 5 wt % of paraffin
as the dispersing agent. Specifically, the weight percent of the
dispersing agent of the thermoplastic cellulosic composition is
about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9,
3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3,
4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5 wt %.
[0045] According to the principles and spirits of the present
invention, the amount of the plasticizer used in the composition
and/or method presented herein is much lower than that of the
conventional art. Also, the problems such as phase separation and
agglomeration can be reduced. Accordingly, the physical properties
of the masterbatch/cellulose-based fiber can be improved. For
example, the cellulose-based fiber according to one embodiment of
the present invention is no less than about 1.2 g/den.
[0046] In another aspect, the present invention is directed to a
cellulose-based masterbatch with a networked structure. The
cellulose-based masterbatch is prepared from the thermoplastic
cellulosic composition according to the aspect and/or embodiment(s)
described hereinabove, and is suitable for use in a melt spinning
process using a higher spinning temperature and spinning speed for
preparing a cellulose-based fiber with a networked structure.
[0047] According to embodiments of the present invention, the
cellulose-based masterbatch comprises about 80 wt % to about 95 wt
% of an esterified cellulose, about 4.5 wt % to about 12 wt % of
polyethylene glycol, about 0.01 wt % to about 3 wt % of a
tri-functional cross-linking agent, about 0.01 wt % to about 0.15
wt % of an initiator and about 0.01 wt % to about 5 wt % of a
dispersing agent.
[0048] In the cellulose-based masterbatch with a networked
structure, each of the a tri-functional cross-linking agent
molecule has three functional groups, and during the compounding
process, at least part of the a tri-functional cross-linking agent
has its three functional groups respectively cross-linked with the
free radicals of the molecular chain of the esterified cellulose
molecule(s) and the polyethylene glycol molecule(s), thereby
forming a networked structure.
[0049] According to embodiments of the present invention, the
cellulose-based masterbatch with a networked structure has an
activation energy of pyrolysis higher than that of a conventional
cellulose-based masterbatch (i.e., the those without the networked
structure). In one working example, the cellulose-based masterbatch
with a networked structure has an onset temperature of pyrolysis
higher than about 240.degree. C. In another working example, the
cellulose-based masterbatch with a networked structure has an
activation energy of pyrolysis higher than about 190 kJ/mol.
[0050] In yet another aspect, the present invention is directed to
a melt spinning process for preparing a cellulose-based fiber with
a networked structure. According to the principles and spirits of
the present invention, the cellulose-based masterbatch of the
above-mentioned aspect/embodiment(s) of the present invention is
subjected to a melt spinning process, and thereby forms a
cellulose-based fiber with a networked structure.
[0051] Specifically, in the melt spinning process, suitable
spinning temperature is about 220-280.degree. C., for example,
about 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275 or
280.degree. C.; whereas suitable spinning speed is about 500-3000
M/min, for example, about 500, 600, 700, 800, 900, 1000, 1100,
1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200,
2300, 2400, 2500, 2600, 2700, 2800, 2900 or 3000 M/min.
[0052] Generally, a spinning temperature of about 220.degree. C. is
sufficient for the spinning process to proceed. However, it is also
well known that spinning temperature is positively related to the
spinning speed. As described in the background section, the
conventional spinning temperature is controlled under 260.degree.
C.; otherwise, the cellulose molecules would become
yellowish-brown.
[0053] However, cellulose-based masterbatch with a networked
structure according to embodiments of the present invention have a
relatively high activation energy of pyrolysis (greater than 190
kJ/mol) and a relatively high onset temperature of pyrolysis
(greater than 240.degree. C.), and hence, the masterbatch is
suitable for use in a melt spinning process with a relatively high
spinning temperature. The results show that the spinning process
may go on even when the spinning temperature is maintained at about
280.degree. C.
[0054] Moreover, according to embodiments of the present invention,
when the spinning temperature is set at about 230-240.degree. C.,
the apparent viscosity of the molten is about 22-78 Pas. Generally,
during the melt spinning process, if the molten achieved an
apparent viscosity greater than 40 Pas, the spinning apparatus may
be damaged due to the pressure caused by the molten. To the
contrary, if the molten could not achieve an apparent viscosity of
at least 20 Pas, the spinning pressure may be too low to proceed
with the spinning. However, according to one embodiment of the
present invention, since the heat resistance of the cellulose-based
masterbatch with a networked structure is better than the
conventional ones, it is possible to carry out the spinning process
at a spinning temperature higher than 240.degree. C., in which
case, the apparent viscosity of the molten would be lowered to
about 20-40 Pas.
[0055] Also, the apparent viscosity of the cellulose-based
masterbatch with a networked structure is higher than that of the
conventional cellulose-based masterbatch (apparent viscosity of
which at 230.degree. C. is about 16-48 Pas); hence, the flowability
of the molten under the spinning condition is better. Accordingly,
the cellulose-based masterbatch with a networked structure is
suitable for use in a melt spinning process with a relatively high
spinning speed. According to embodiments of the present invention,
the spinning process may go on at a spinning speed of about 3000
m/min without filament break. By comparison, the maximum spinning
speed for preparing the cellulosed-based fiber of the conventional
art is 1000 m/min. In view of the foregoing, the cellulose-based
masterbatch with a networked structure and the melt spinning
process provided herein are suitable for use in mass production of
the cellulosed-based fiber.
[0056] Also, the melt spinning process may enhance the production
yield of the cellulose-based fibers.
[0057] In still another aspect, the present invention is directed
to a cellulose-based fiber with a networked structure. The
cellulose-based fiber may be prepared from the masterbatch, by the
method and/or the melt spinning process according to
aspects/embodiments of the present invention. Since the plasticizer
within the cellulose-based fiber may be connected to the molecular
chain of the cellulose molecule via the cross-linking agent, the
plasticizer can be evenly distributed across the polymer. Also,
phase separation between the cellulose molecules and the
plasticizer may be reduced. Accordingly, the resultant
cellulose-based fiber may exhibit a better mechanical strength. For
example, in one working example, the cellulose-based fiber with a
networked structure may have a breaking tenacity that is no less
than about 1.2 g/den.
[0058] According to embodiments of the present invention,
constituents of the cellulose-based fiber with a networked
structure are similar to those of the cellulose-based masterbatch.
That is, the cellulose-based fiber may comprise about 80 wt % to
about 95 wt % of an esterified cellulose, about 4.5 wt % to about
12 wt % of polyethylene glycol, about 0.01 wt % to about 3 wt % of
a tri-functional cross-linking agent, about 0.01 wt % to about 0.15
wt % of an initiator and about 0.01 wt % to about 5 wt % of a
dispersing agent, wherein each of the tri-functional cross-linking
agent has three functional groups, and at least part of the
tri-functional cross-linking agent has its three functional groups
respectively connected to the molecular chain of the esterified
cellulose molecule or the polyethylene glycol molecule, thereby
forming the networked structure
[0059] Some working examples according to embodiments of the
present invention are provided hereinafter so as to illustrate the
properties of the masterbatch and fiber provided herein. In a twin
screw extruder, constituents were mixed with the weight ratios
specified in Table 1 to obtain thermoplastic cellulosic
compositions of various working examples. Then, the thermoplastic
cellulosic compositions were compounded in the twin screw extruder
at a temperature of about 160-220.degree. C. to allow the
tri-functional cross-linking agent to react with the esterified
cellulose molecules. After the compounding step, the compounded
composition may be granulized to form a plurality cellulose-based
masterbatch.
[0060] For example, in working example 1, about 92 wt % of
cellulose acetate propionate (CAP), about 3.5 wt % of polyethylene
glycol (PEG) having a molecular weight of about 600 Da, about 3.5
wt % of PEG having a molecular weight of about 1,000 Da, about 0.5
wt % of triallyl isocynaurate (TAIC), about 0.45 wt % of paraffin
and about 0.05 wt % of benzyl dimethyl ketal (BDK) were mixed to
obtain the thermoplastic cellulosic composition. The composition
were than compounded and granulized to produce the masterbatch of
working example 1.
[0061] In order to investigate whether or not the resultant
masterbatch is suitable for use in the melt spinning process, the
masterbatch was subjected to thermogravimetric analysis to
determine the onset temperature of the pyrolysis (Onset Temp,). In
addition, the activation energy of pyrolysis (Activation Energy) of
each masterbatch is calculated based on the onset temperature of
the pyrolysis. Result of the thermogravimetric analysis is
summarized in Table 1.
[0062] In addition, cellulose-based fibers were prepared from the
masterbatch of the working examples with a melt spinning process,
where the spinning temperature is about 240.degree. C. or
250.degree. C., and the spinning speed is about 1000 M/min or 1500
M/min.
[0063] The fibers were further tested by a tensile strength tester
in accordance with the procedure set forth in ASTM D2256 (Standard
Test Method for Tensile Properties of Yarns by the Single-Strand
Method) to determine the breaking elongation (Elongation) and
breaking tenacity (Tenacity) of the fibers. Results of the analysis
are summarized in Table 1.
TABLE-US-00001 TABLE 1 Working Working Working Working Working
Working Working Compar. example 1 example 2 example 3 example 4
example 5 example 6 example 7 example CAP (wt %) 92 91.5 91.3 88.3
86.3 86.0 85.4 87.5 PEG (wt %) 600 0 0 0 0 0 0 6 1000 7 7 10 12 12
12 6 8000 0 0 0 0 0 0 0 TAIC (wt %) 0.5 1.0 1.2 1.2 1.2 1.5 2.1 0
Paraffin (wt %) 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 BDK (wt %)
0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Onset Temp. -- -- 260 260
260 -- 280 170 (.degree. C.) Act. energy -- -- -- -- 189.6 193.8
258.3 177.6 (kJ/mol) Spinning Temp. 240 240 240 240 250 -- -- 240
(.degree. C.) Spinning speed 1000 1000 1000 1000 1000 -- -- 1500
(M/min) Apparent -- -- -- -- 27-78 -- -- 16-48 viscosity (Pas)
Denier (den) 150 150 153 152 299.8 -- -- 150 Tenacity (g/den) 1.21
1.14 0.91 1.13 0.77 -- -- 0.72 Elongation (%) 20 16 15 18 27 -- --
17
[0064] As table 1 shows, the cellulose-based masterbatch with a
networked structure according to embodiments of the present
invention has an activation energy of pyrolysis higher than that of
a conventional, non-cross-linked cellulose-based masterbatch. That
is, the cellulose-based masterbatch with a networked structure has
a better heat resistance.
[0065] Specifically, the cellulose-based masterbatch of the
comparative example has an activation energy of pyrolysis of about
177.6 kJ/mol, and an onset temperature of pyrolysis of about
170.degree. C.; in comparison, the cellulose-based masterbatch with
a networked structure of working example 5 has an activation energy
of pyrolysis of about 189.6 kJ/mol, and an onset temperature of
pyrolysis of about 260.degree. C., both of which are substantially
higher than that of the masterbatch of the comparative example.
[0066] Moreover, by comparing working examples 5-7, it is found
that as the amount of the tri-functional cross-linking agent
increases, the activation energy of pyrolysis of the resultant
masterbatch also increases. During the melt spinning process, if
the masterbatch to be used was more resistant to heat, it is
possible to increase the spinning temperature, and hence the
spinning speed. That is, the masterbatch according to the present
invention is suitable for use in commercial mass production. For
example, according to one working example of the present invention,
the onset temperature of pyrolysis of the cellulose-based
masterbatch with a networked structure is about 260-280.degree. C.;
and hence, the masterbatch can be used in a spinning process with a
spinning temperature of about 240.degree. C.-250.degree. C.
[0067] As shown in Table 1, the cellulose-based fibers with a
networked structure of the working examples the may have a breaking
tenacity (about 0.77-1.21 g/den) better than the tenacity of the
conventional cellulose-based fiber (about 0.72 g/den). Regarding
the breaking elongation, cellulose-based fibers of working examples
1, 4, and 5 are also better than the conventional one (about 18-27%
versus about 17%). In view of the foregoing, the physical
properties of the cellulose-based fiber prepared by the spinning
method provided herein may comply with the properties required by
the textile and weaving industry.
[0068] To further investigate the spinnability of the fiber and the
physical properties of the resultant fiber using a spinning process
with a high spinning temperature and a high spinning speed,
cellulose-based masterbatch of the working example 5 were melt-spun
under different conditions as illustrated in Table 2. Also, the
breaking elongation (Elongation) and breaking tenacity (Tenacity)
of the fibers were determined in accordance with the procedure set
forth in ASTM D2256. Results of the analysis are summarized in
Table 2.
TABLE-US-00002 TABLE 2 Working Working Working Working Working
Working Working Working example example example example example
example example example 5-1 5-2 5-3 5-4 5-5 5-6 5-7 5-8 Spinning
Temp. 240 250 260 270 280 260 260 260 (.degree. C.) Spinning speed
800 1000 1000 2000 1500 2000 2500 3000 (m/min) Denier (den) 336 300
280 193 185 145 115 97 Tenacity (g/den) 0.75 0.77 0.9 0.76 0.79
0.84 0.9 0.83 Elongation (%) 24 27 15 17 18 16 17 12
[0069] As can be seen in table 2, in working example 5-5, the
cellulose-based fiber with a networked structure can be melt-spun
at a spinning temperature of about 280.degree. C. Moreover, in
working example 5-8, the spinning speed can be set at about 3000
M/min. All the weaving processes listed in table 2 continued for
more than half an hour without filament break.
[0070] The appearance of the fibers of working example 5-1 to 5-8
are quite similar; that is, different spinning speed as set forth
in table 2 would not substantially affect the appearance of the
resultant fiber.
[0071] In sum, the masterbatch with a networked structure provided
herein is suitable for use in a melt spinning process where the
spinning temperature is about 220-280.degree. C. and the spinning
speed is about 500-3000 m/min. Moreover, the resultant
cellulose-based fiber with a networked structure may have a
tenacity of about 0.75 g/den to about 1.21 g/den.
[0072] Conventional masterbatch of the comparative example is
further melt-spun at a spinning temperature of about 260.degree.
C., and the CIE value of the resultant fiber is about 8. In
comparison, the CIE value of the cellulose-based fiber of the
working example 5-8 is about 35. CIE value is a relative value, and
a sample having a higher CIE value is whiter in color. It is
believed that owing to the more heat-resistant nature of the
cellulose-based masterbatch with the networked structure, the
present masterbatch, upon being heat under a relatively high
spinning temperature (about 260.degree. C.), would not be burned.
Hence, the resultant fiber is whiter than the conventional
ones.
[0073] It will be understood that the above description of
embodiments is given by way of example only and that various
modifications may be made by those with ordinary skill in the art.
The above specification, examples and data provide a complete
description of the structure and use of exemplary embodiments of
the invention. Although various embodiments of the invention have
been described above with a certain degree of particularity, or
with reference to one or more individual embodiments, those with
ordinary skill in the art could make numerous alterations to the
disclosed embodiments without departing from the spirit or scope of
this invention.
* * * * *