U.S. patent application number 13/195989 was filed with the patent office on 2015-12-10 for prepreg and carbon fiber reinforced composite materials.
The applicant listed for this patent is Nobuyuki ARAI, Junko Kawasaki, Norimitsu Natsume, Hiroshi Takezaki, Kenichi Yoshioka. Invention is credited to Nobuyuki ARAI, Junko Kawasaki, Norimitsu Natsume, Hiroshi Takezaki, Kenichi Yoshioka.
Application Number | 20150353697 13/195989 |
Document ID | / |
Family ID | 39032951 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150353697 |
Kind Code |
A9 |
ARAI; Nobuyuki ; et
al. |
December 10, 2015 |
PREPREG AND CARBON FIBER REINFORCED COMPOSITE MATERIALS
Abstract
A prepreg containing a carbon fiber [A] and a thermosetting
resin [B], and in addition, satisfying at least one of the
following (1) and (2). (1) a thermoplastic resin particle or fiber
[C] and a conductive particle or fiber [D] are contained, and
weight ratio expressed by [compounding amount of [C] (parts by
weight)]/[compounding amount of [D] (parts by weight)] is 1 to
1000. (2) a conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E] is
contained.
Inventors: |
ARAI; Nobuyuki; (Ehime,
JP) ; Natsume; Norimitsu; (Ehime, JP) ;
Yoshioka; Kenichi; (Ehime, JP) ; Kawasaki; Junko;
(Ehime, JP) ; Takezaki; Hiroshi; (Nagoya-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ARAI; Nobuyuki
Natsume; Norimitsu
Yoshioka; Kenichi
Kawasaki; Junko
Takezaki; Hiroshi |
Ehime
Ehime
Ehime
Ehime
Nagoya-shi |
|
JP
JP
JP
JP
JP |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110287246 A1 |
November 24, 2011 |
|
|
Family ID: |
39032951 |
Appl. No.: |
13/195989 |
Filed: |
August 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13038674 |
Mar 2, 2011 |
8075988 |
|
|
13195989 |
|
|
|
|
12376763 |
Feb 6, 2009 |
7931958 |
|
|
PCT/JP2007/065390 |
Aug 7, 2007 |
|
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13038674 |
|
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Current U.S.
Class: |
252/500 ;
252/511; 264/347; 428/300.1; 428/327 |
Current CPC
Class: |
Y10T 428/25 20150115;
D06M 2101/40 20130101; Y10T 442/645 20150401; B32B 2264/105
20130101; B32B 2605/18 20130101; B32B 2264/108 20130101; B32B
2262/106 20130101; B32B 2264/0214 20130101; C08J 2363/00 20130101;
D06M 15/53 20130101; B32B 2307/202 20130101; Y10T 428/249948
20150401; Y10T 428/24994 20150401; B32B 2260/046 20130101; B32B
5/022 20130101; B32B 2305/076 20130101; B32B 2305/08 20130101; Y10T
428/254 20150115; Y10T 442/2418 20150401; C08L 63/00 20130101; B32B
2603/00 20130101; B32B 27/12 20130101; D06M 15/63 20130101; Y10T
428/249942 20150401; C08J 5/24 20130101; D06M 11/74 20130101; Y10T
428/24995 20150401; B32B 2255/26 20130101; Y10T 442/2426 20150401;
B32B 5/26 20130101; C08J 2477/00 20130101; D06M 11/83 20130101;
B32B 2255/02 20130101; B32B 2307/558 20130101; Y10T 428/249949
20150401; B29C 70/882 20130101; B32B 2260/021 20130101; C08L
2201/02 20130101; Y10T 428/24 20150115; B32B 5/22 20130101; D06M
2200/00 20130101 |
International
Class: |
C08J 5/24 20060101
C08J005/24; H01B 1/20 20060101 H01B001/20; B32B 27/38 20060101
B32B027/38; B32B 27/18 20060101 B32B027/18; B32B 27/12 20060101
B32B027/12; C08L 63/00 20060101 C08L063/00; B32B 5/22 20060101
B32B005/22; B29C 71/02 20060101 B29C071/02; B32B 5/28 20060101
B32B005/28 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2006 |
JP |
2006-214398 |
Nov 20, 2006 |
JP |
2006-312531 |
Feb 20, 2007 |
JP |
2007-038974 |
Claims
1. An epoxy resin composition for a carbon fiber reinforced
composite material containing an epoxy resin [B], and satisfying at
least one of the following conditions (1) and (2), wherein the
epoxy resin composition is used to make a laminate with
conductivity in a thickness direction by being laminated between
two sheet like carbon fiber layers containing carbon fiber [A], and
the conditions are as follows: (1) thermoplastic resin particles or
fibers [C] and conductive particles or fibers [D] are contained in
the epoxy resin [B], wherein a weight ratio expressed by [content
of [C] (parts by weight)]/[content of [D] (parts by weight)] is 1
to 1000; and (2) conductive particles or fibers having a
thermoplastic resin nucleus or core coated with a conductive
substance [E] are contained in the epoxy resin [B].
2. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein the conductive
particles or fibers [D] have an average particle or fiber diameter
equal to or larger than an average particle or fiber diameter of
the thermoplastic resin particles or fibers [C] and the average
particle or fiber diameter is at most 150 .mu.m.
3. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein each of the
thermoplastic resin particles or fibers [C], the conductive
particles or fibers [D] and the conductive particles or fibers [E]
have an average diameter of 1 to 150 .mu.m.
4. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein the conductive
particles [D] are at least one conductive particle selected from
the group consisting of carbon particles, particles having a
nucleus of inorganic material coated with a conductive substance
and particles having a nucleus of organic material coated with a
conductive substance.
5. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein the resin of the
thermoplastic resin particles or fibers [C] is a polyamide
resin.
6. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, further comprising a
thermoplastic resin dissolved in the epoxy resin [B].
7. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 6, wherein the thermoplastic
resin dissolved in the epoxy resin [B] is a polyethersulfone.
8. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein the epoxy resin
[B] is at least one resin selected from the group consisting of a
glycidyl amine type epoxy resin and a glycidyl ether type epoxy
resin.
9. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 8, wherein the glycidyl amine
type epoxy resin is at least one resin selected from the group
consisting of a tetraglycidyldiaminodiphenylmethane and a
triglycidylaminophenol.
10. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 8, wherein the glycidyl ether
type epoxy resin is at least one resin selected from the consisting
of a bisphenol A type epoxy resin and a bisphenol F type epoxy
resin.
11. An epoxy resin composition for a carbon fiber reinforced
composite material according to claim 1, wherein the prepreg
further contains a diaminodiphenyl sulfone as a hardener of the
epoxy resin.
12. A prepreg having two sheet like carbon fiber layers containing
a carbon fiber [A], and an inter-formative layer sandwiched between
the carbon fiber layers containing the epoxy resin composition
according to any one of claims 1 to 11.
13. A carbon fiber reinforced composite material produced by curing
a prepreg according to claim 12.
Description
CROSS REFERENCE WITH PCT APP
[0001] The present application is a 37 C.F.R. .sctn.1.53(b)
divisional of, and claims priority to, U.S. application Ser. No.
13/038,674, filed Mar. 2, 2011. Application Ser. No. 13/038,674 is
the national phase under 35 U.S.C. .sctn.371 of International
Application No. PCT/JP2007/065390, filed on Aug. 7, 2007.
Application Ser. No. 13/038,674 claims benefit under 35 USC
.sctn.120 to U.S. application Ser. No. 12/376,763 filed on Feb. 6,
2009 and granted as U.S. Pat. No. 7,931,958 B2 on Apr. 26, 2011.
Priority is also claimed to Japanese Application No. 2006-214398
filed on Aug. 7, 2006; Japanese Application No. 2006-312531 filed
on Nov. 20, 2006; and Japanese Application No. 2007-038974 filed on
Feb. 20, 2007. The entire contents of each of these applications is
hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a prepreg and carbon fiber
reinforced composite material having an excellent impact resistance
and conductivity together.
BACKGROUND ART
[0003] Carbon fiber reinforced composite materials are useful since
they are excellent in strength, stiffness, conductivity, etc., and
widely used for an aircraft structural member, a windmill wing, an
automotive outer panel and computer uses such as an IC tray or a
housing of notebook computer and their needs are increasing year by
year.
[0004] The carbon fiber reinforced composite material is generally
an inhomogeneous material obtained by molding a prepreg of which
essential constituting elements are a carbon fiber which is a
reinforcing fiber and a matrix resin, and accordingly, there is a
big difference between physical properties of arranging direction
of the reinforcing fiber and physical properties of other
direction. For example, it is known that an impact resistance
expressed by a resistance to drop impact is, since it is determined
by delamination strength which is quantitatively measured as
interlayer edge peel strength, not resulted in a drastic
improvement only by increasing strength of the reinforcing fiber.
In particular, carbon fiber reinforced composite materials of which
matrix resin is a thermosetting resin has, in reflection of a low
toughness of the matrix resin, a property to be broken easily by a
stress from other than the arranging direction of the reinforcing
fiber. Accordingly, various means are proposed for the purpose of
improving physical properties of composite material capable of
resisting to the stress from other than the arranging direction of
the reinforcing fiber.
[0005] As one of them, a prepreg provided with a resin layer, in
which resin particles are dispersed, on surface region of the
prepreg is proposed. For example, a method for providing a high
toughness composite material excellent in heat resistance, by using
a prepreg provided with a resin layer in which particles consisting
of a thermoplastic resin such as nylon are dispersed in surface
region of the prepreg, is proposed (refer to Patent reference 1).
And, other than that, a method for developing a high toughness of
composite material by a combination of a matrix resin of which
toughness is improved by adding a polysulfone oligomer and a
particle consisting of a thermosetting resin is proposed (refer to
Patent reference 2). However, these methods give a high impact
resistance to carbon fiber reinforced composite material on one
hand, but on the other hand, result in producing a resin layer to
become an insulating layer in the interlayer. Accordingly, there is
a defect that the conductivity in thickness direction, among
conductivities which are one of characteristics of the carbon fiber
reinforced composite material, significantly decreases, and it was
difficult to make an excellent impact resistance and conductivity
compatible in the carbon fiber reinforced composite material.
[0006] Furthermore, as methods for improving conductivity of the
interlayer, a method of compounding a metal particle to a matrix
resin of carbon fiber reinforced composite material (refer to
Patent reference 3), or a method of compounding a carbon particle
(refer to Patent reference 4) can be considered, but in these
references, no reference is made to a compatibility of an excellent
impact resistance and conductivity.
[0007] [Patent reference 1] specification of U.S. Pat. No.
5,028,478
[0008] [Patent reference 2] JP-H3-26750A
[0009] [Patent reference 3] JP-H6-344519A
[0010] [Patent reference 4] JP-H8-34864A
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0011] In such a circumstance, the purpose of the present invention
is to provide a prepreg and carbon fiber reinforced composite
material having an excellent impact resistance and conductivity in
thickness direction together.
Means for Solving the Problems
[0012] The prepreg of the present invention has the following
constitution to achieve the above-mentioned purpose. That is, a
prepreg containing a carbon fiber [A] and a thermosetting resin [B]
and in addition, satisfying at least any one of the following (1)
and (2).
[0013] (1) A thermoplastic resin particle or fiber [C] and a
conductive particle or fiber [D] are contained, and a weight ratio
expressed by [compounding amount of [C] (parts by
weight)]/[compounding amount of [D] (parts by weight)] is 1 to
1000.
[0014] (2) A conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E] is
contained.
[0015] Furthermore, the carbon fiber reinforced composite material
of the present invention has the following constitution to achieve
the above-mentioned purpose. That is, a carbon fiber reinforced
composite material containing a carbon fiber [A] and a
thermosetting resin [B] and in addition, satisfying at least any
one of the following (1) and (2).
[0016] (1) A thermoplastic resin particle or fiber [C] and
conductive particle or fiber [D] are contained, and a weight ratio
expressed by [compounding amount of [C] (parts by
weight)]/[compounding amount of [D] (parts by weight)] is 1 to
1000.
[0017] (2) A conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E] is
contained.
Effect of the Invention
[0018] By the present invention, it is possible to obtain a carbon
fiber reinforced composite material having an excellent impact
resistance and conductivity together. By conventional arts, only a
carbon fiber reinforced composite material which is low in
conductivity when its impact resistance is high or which is low in
impact resistance when its conductivity is high, but by the present
invention, it became possible to provide a carbon fiber reinforced
composite material simultaneously satisfying the impact resistance
and the conductivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] [FIG. 1] An example of cross-sectional view of a
representative prepreg.
[0020] [FIG. 2] A graph which shows compressive strength after
impact and volume resistivity in relation to the weight ratio
expressed by [compounding amount of [C] (parts by
weight)]/[compounding amount of [D] (parts by weight)].
EXPLANATION OF REFERENCES
[0021] 1: carbon fiber layer (intralayer)
[0022] 2: inter-formative layer (interlayer)
[0023] 3: thermoplastic resin particle
[0024] 4: conductive particle
[0025] 5: carbon fiber
[0026] 6: thermosetting resin
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] The inventors surprisingly found that, as a result of
investigating hard on conductivity mechanism in thickness direction
of a carbon fiber reinforced composite material consisting of a
carbon fiber and a thermosetting resin, a carbon fiber reinforced
composite material having in a high level an excellent impact
resistance and conductivity together can be obtained without
decreasing carbon fiber content by, in addition to the
thermoplastic resin particle or fiber which imparts a high impact
resistance to the interlayer part on one hand but results in
producing a resin layer to become an insulating layer in the
interlayer, further compounding a conductive particle or fiber in a
specified weight ratio, or compounding a conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance in the interlayer part, and conceived a
prepreg capable of obtaining such a carbon fiber reinforced
composite material.
[0028] Prepreg is an intermediate base material for molding made by
impregnating with a matrix resin to a reinforcing fiber, and in the
present invention, carbon fiber is used as the reinforcing fiber
and a thermosetting resin is used as the matrix resin. In such a
prepreg, the thermosetting resin is in an uncured state, and by
laying-up the prepreg and by curing, a carbon fiber reinforced
composite material is obtained. As a matter of course, even by
curing a single layer prepreg, a carbon fiber reinforced composite
material can be obtained. In a carbon fiber reinforced composite
material obtained by laying-up a plural of prepregs and by curing,
a surface portion of the prepreg becomes to an interlayer part of
the carbon fiber reinforced composite material and an inner part of
the prepregs become to an intralayer part of the carbon fiber
reinforced composite material.
[0029] The prepreg of the present invention is a prepreg containing
the carbon fiber [A] and the thermosetting resin [B] and in
addition, satisfying at least any one of the following (1) and
(2).
[0030] (1) A thermoplastic resin particle or fiber [C] and a
conductive particle or fiber [D] are contained, and a weight ratio
expressed by [compounding amount of [C] (parts by
weight)]/[compounding amount of [D] (parts by weight)] is 1 to
1000.
[0031] (2) A conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E] is
contained.
[0032] In an embodiment satisfying the item (1), the prepreg or the
carbon fiber reinforced composite material obtainable from the
prepreg contains the carbon fiber [A], the thermosetting resin [B],
the thermoplastic resin particle or fiber [C] and the conductive
particle or fiber [D]. In this embodiment, it is preferable to use
a thermoplastic resin particle as the [C] and a conductive particle
as the [D]. It is because a case where both of the [C] and the [D]
are made into particle configuration is, compared to a case where
one of them is in fiber configuration or both of them are in fiber
configuration, better in flow characteristics of the thermosetting
resin and excellent in impregnating property to the carbon fiber.
And, by using the thermoplastic resin particle and the conductive
particle in combination, when a drop impact (or a localized impact)
is added to the carbon fiber reinforced composite material, since
an interlayer delamination caused by the localized impact is
reduced, in case where a stress is loaded to the carbon fiber
reinforced composite material after such an impact, delamination
parts generated by the above-mentioned localized impact which would
be starting points of breakage by stress concentration are not
many, and since a probability of contact of the conductive particle
with the carbon fiber in the laminate layer is high to make it easy
to form a conductive path, a carbon fiber reinforced composite
material which exhibits a high impact resistance and conductivity
cay be obtained.
[0033] On the other hand, in an embodiment satisfying the item (2),
the prepreg or the carbon fiber reinforced composite material
obtainable from the prepreg contains the carbon fiber [A], the
thermosetting resin [B] and the conductive particle of which
thermoplastic resin nucleus is coated with a conductive substance
or the conductive fiber of which core of thermoplastic resin is
coated with a conductive substance [E]. Here, the [E] is, among the
above-mentioned [D], that having a specific embodiment where a
conductive particle of which thermoplastic resin nucleus is coated
with a conductive substance or where a conductive fiber of which
core of thermoplastic resin is coated with a conductive substance.
By using the [E] having such a specific embodiment, the effect
obtained by using the above-mentioned [C] and the [D] in
combination, can be obtained only by the [E].
[0034] The embodiment satisfying the item (1) is, compared to the
embodiment satisfying the item (2), due to an effect of excellent
toughness by the thermoplastic resin particle or fiber [D] in the
interlayer part, it is excellent in viewpoint that a delamination
strength is high and an impact resistance is still high when a drop
impact is added to the carbon fiber reinforced composite material.
On the other hand, the embodiment satisfying the item (2) is,
compared to the embodiment satisfying the item (1), since
components to be used are not many, excellent in viewpoint of
expectation of cost reduction and productivity improvement.
[0035] It is preferable that the carbon fiber [A] used in the
present invention is, in view of exhibiting a higher conductivity,
a carbon fiber having a tensile modulus of at least 260 GPa, but in
view of compatibility with the impact resistance, it is preferable
to be a carbon fiber having a tensile modulus of at most 440 GPa.
In view of such a point, it is especially preferable that the
tensile modulus is in the range of 280 to 400 GPa, since
conductivity and impact resistance can be compatible at a high
level.
[0036] In addition, in view of impact resistance, since it is
possible to obtain a composite material excellent in impact
resistance and having a high stiffness and mechanical strength, it
is preferable to be a high-strength high-elongation carbon fiber of
which tensile strength is 4.4 to 6.5 GPa and tensile strain is 1.7
to 2.3%. Accordingly, in view of compatibility of conductivity and
impact resistance, a carbon fiber having all characteristics of a
tensile modulus of at least 280 GPa, a tensile strength of at least
4.4 GPa and a tensile strain of at least 1.7% is most appropriate.
The tensile modulus, the tensile strength and the tensile strain
can be determined by the strand tensile test described in JIS
R7601-1986.
[0037] The thermosetting resin [B] used in the present invention is
not especially limited, as far as it is a resin capable of forming
a three-dimensional cross-linked structure at least partially by
progressing a cross-linking reaction by heat. As such a
thermosetting resin, for example, an unsaturated polyester resin, a
vinyl ester resin, an epoxy resin, a benzoxazine resin, a phenol
resin, an urea-formaldehyde resin, a melamine formaldehyde resin
and a polyimide resin, etc., are mentioned, and denaturations
thereof and resins in which 2 kinds or more of them are blended can
also be used. And, these thermosetting resins may be self-curable
by heat or a hardener or a curing accelerator or the like may be
compounded therein.
[0038] Among these thermosetting resins, epoxy resin excellent in a
balance of heat resistance, mechanical characteristics and adhesion
with carbon fiber is preferably used. In particular, amines,
phenols or an epoxy resin of which precursor is a compound having a
carbon-carbon double bond are preferably used. Concretely, as
glycidyl amine type epoxy resins of which precursor is an amine,
tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol and
various isomers of triglycidylaminocresol are mentioned.
Tetraglycidyldiaminodiphenyl methane is preferable as a resin for
composite material of aircraft structural material since it is
excellent in heat resistance.
[0039] Furthermore, as a thermosetting resin, a glycidyl ether type
epoxy resin of which precursor is phenol is also preferably used.
As such epoxy resins, bisphenol A type epoxy resin, bisphenol F
type epoxy resin, bisphenol S type epoxy resin, phenol novolac type
epoxy resin, cresol novolac type epoxy resin and resorcinol type
epoxy resin are mentioned.
[0040] Since a bisphenol A type epoxy resin, bisphenol F type epoxy
resin and resorcinol type epoxy resin of liquid state are low in
viscosity, it is preferable to use them with other epoxy resin in
combination.
[0041] Furthermore, since a bisphenol A type epoxy resin which is
solid at room temperature (about 25.degree. C.) gives a cured resin
of a structure of lower cross-linking density compared to a
bisphenol A type epoxy resin which is liquid at room temperature
(about 25.degree. C.), said cured resin becomes lower in heat
resistance, but becomes higher in toughness, and accordingly, it
preferably is used in combination with a glycidyl amine type epoxy
resin, a liquid bisphenol A type epoxy resin or a bisphenol F type
epoxy resin.
[0042] An epoxy resin having a naphthalene skeleton gives a cured
resin of low water absorption, and in addition, of high heat
resistance. And, a biphenyl type epoxy resin, a dicyclopentadiene
type epoxy resin, a phenolaralkyl type epoxy resin and a
diphenylfluorene type epoxy resin also give cured resins of low
water absorption, and are preferably used.
[0043] A urethane modified epoxy resin and an isocyanate modified
epoxy resin give cured resins high in fracture toughness and
strain, and they are preferably used.
[0044] These epoxy resins may be used singly or may be used by
compounding appropriately. It is preferable to use them by
compounding with at least a difunctional epoxy resin and an epoxy
resin of trifunctional or more, since resin flowability and heat
resistance after curing can be made compatible. In particular, a
combination of a glycidyl amine type epoxy and a glycidyl ether
type epoxy makes it possible that heat resistance and water
resistance are compatible. And, compounding at least an epoxy resin
which is liquid at room temperature and an epoxy resin which is
solid at room temperature is effective to make tackiness properties
and draping properties of prepreg appropriate.
[0045] The phenol novolac type epoxy resin or cresol novolac epoxy
resin gives a cured resin excellent in heat resistance and water
resistance, since they are excellent in heat resistance and low in
water absorption. By using these phenol novolac type epoxy resin or
cresol novolac epoxy resin, it is possible to control tackiness
properties and draping properties of prepreg while improving heat
resistance and water resistance.
[0046] As a hardener of the epoxy resin, it can be used if it is a
compound having an active group capable of reacting with the epoxy
group. As the hardener, a compound having amino group, acid
anhydride group or azido group is suitable. As the hardener, more
concretely, for example, dicyandiamide, diaminodiphenyl methane or
various isomers of diaminodiphenyl sulfone, aminobenzoic acid
esters, various acid anhydrides, a phenol novolac resin, a cresol
novolac resin, a poly phenol compound, an imidazole derivative, an
aliphatic amine, tetramethylguanidine, a thiourea addition amine,
carboxylic acid anhydrides such as methylhexahydrophthalic acid
anhydride, a carboxylic hydrazide, a carboxylic amide, a poly
mercaptan and Lewis acid complexes such as BF.sub.3 ethylamine
complex, etc., are mentioned. These hardeners may be used alone or
in combination.
[0047] By using an aromatic diamine as a hardener, a cured resin
excellent in heat resistance can be obtained. In particular,
various isomers of diaminodiphenyl sulfone are most appropriate for
obtaining a cured resin excellent in heat resistance. As to an
amount of addition of the aromatic diamine as a hardener, it is
preferable to add in stoichiometrically equivalent amount, but in
certain circumstances, for example, by using approximately 0.7 to
0.8 to the equivalent amount, a high modulus cured resin can be
obtained.
[0048] Furthermore, by using a combination of dicyandiamide with a
urea compound, for example, with
3,4-dichlorophenyl-1,1-dimethylurea, or by using an imidazole as a
hardener, a high heat resistance and water resistance are achieved,
even though being cured at a relatively low temperature. A curing
by using an acid anhydride gives, compared to a curing by an amine
compound, a cured resin of lower water absorption. Other than that,
by using a latent hardener of them, for example, a
microencapsulated hardener, storage stability of the prepreg is
improved and, especially, tackiness properties or draping
properties hardly change even when being left at room
temperature.
[0049] Furthermore, it is also possible to compound these epoxy
resin and hardener, or a prereaction product of a part of them in
the composition. This method is effective for viscosity control or
improvement of storage stability in some cases.
[0050] It is also preferable to use by mixing and dissolving a
thermoplastic resin into the above-mentioned thermosetting resin.
As such thermoplastic resins, in general, it is preferable to be a
thermoplastic resin having, in the main chain, a bond selected from
carbon-carbon bond, amide bond, imide bond, ester bond, ether bond,
carbonate bond, urethane bond, thioether bond, sulfone bond and
carbonyl bond, but a cross-linked structure may partially be
contained. And, it may have crystallinity or may be amorphous. In
particular, it is preferable that at least 1 kind resin selected
from the group consisting of a polyamide, a polycarbonate, a
polyacetal, polyphenyleneoxide, poly phenylene sulfide, a
polyarylate, a polyester, a polyamideimide, a polyimide, a
polyetherimide, a polyimide having phenyltrimethylindane structure,
a polysulfone, a polyethersulfone, a polyetherketone, a
polyetheretherketone, a polyaramid, a polyethernitrile and a
polybenzimidazole is mixed and dissolved into the thermosetting
resin.
[0051] As such thermoplastic resins, a commercially available
polymer may be used, or a so-called oligomer of which molecular
weight is lower than the commercially available polymer may be
used. As the oligomer, an oligomer having, on its end or in
molecular chain, a functional group capable of reacting with the
thermosetting resin is preferable.
[0052] In case where a mixture of the thermosetting resin and the
thermoplastic resin is used, a better result is obtained than a
case where they are used alone. Brittleness of the thermosetting
resin is covered by toughness of the thermoplastic resin, and in
addition, difficulty of molding of the thermoplastic resin is
covered by the thermosetting resin, and a base resin in good
balance is obtained. A using ratio (parts by weight) of the
thermosetting resin and the thermoplastic resin is, in view of the
balance, preferably in the range of 100:2 to 100:50, and more
preferably, in the range of 100:5 to 100:35.
[0053] Furthermore, in the above-mentioned thermosetting resin, for
the purpose of improving conductivity of the carbon fiber
reinforced composite material by increasing contact probability of
the carbon fiber with each other, it is preferable to use by mixing
a conductive filler. As such conductive fillers, a carbon black, a
carbon nanotube, a vapor-grown carbon fiber (VGCF), a fullerene, a
metal nanoparticle, etc., are mentioned, and they may be used alone
or in combination. Among them, a carbon black which is cheap and
high in effect is preferably used, and as such carbon blacks, for
example, a furnace black, an acetylene black, a thermal black, a
channel black, a ketjen black, etc., can be used, and a carbon
black in which 2 kinds or more of them are blended is also
preferably used. The conductive filler mentioned here is a
conductive particle or fiber having an average diameter smaller
(generally 0.1 times or less) than the average diameters of the
conductive particle or fiber [D] and a conductive particle or fiber
of which thermoplastic resin nucleus or core is coated with a
conductive substance [E].
[0054] In an embodiment satisfying the item (1) of the present
invention, since the thermoplastic resin particle or fiber [C] is
used as an essential component, an excellent impact resistance can
be realized. As materials for the thermoplastic resin particle or
fiber [C] of the present invention, the same materials as the
various thermoplastic resins above-exemplified as the thermoplastic
resins to be used by mixing and dissolving into the thermosetting
resin can be used. Among them, polyamide which can greatly improve
impact resistance by its excellent toughness is most preferable.
Among the polyamides, Nylon 12, nylon 11 or nylon 6/12 copolymer
are preferable, since they are especially good in adhesion strength
with the thermosetting resin [B], and delamination strength of the
carbon fiber reinforced composite material at the time of drop
impact is high, and effect of impact resistance improvement is
high.
[0055] In case where a thermoplastic resin particle is used as the
[C], as the thermoplastic resin particle shape, spherical,
nonspherical, porous, spicular, whisker-like or flaky shape may
also be acceptable, but spherical shape is preferable since it is
excellent in impregnating property to carbon fibers because it does
not lower flow ability of the thermosetting resin, or since an
interlayer delamination, generated by a localized impact when a
drop impact (or localized impact) is added to the carbon fiber
reinforced composite material, is more reduced, and the
delamination parts, caused by the above-mentioned localized impact,
which are starting points of breakage by stress concentration in
case where a stress is added to the carbon fiber reinforced
composite material, are not many, and a carbon fiber reinforced
composite material which realizes a high impact resistance can be
obtained.
[0056] In case where a thermoplastic resin fiber is used as the
[C], as a shape of the thermoplastic resin fiber, both of short
fiber or long fiber can be used. In case of short fiber, a method
in which short fibers are used in the same way as particles as
shown in JP-02-69566A, or a method in which short fibers are used
after processed into a mat is possible. In case of long fiber, a
method in which long fibers are arranged in parallel on a prepreg
surface as shown in JP-04-292634A, or a method in which they are
arranged randomly as shown in WO94/016003 is possible. Furthermore,
it can be used after processed into sheet-like base materials such
as a woven fabric as shown in JP-H02-32843A, a non-woven fabric as
shown in WO94016003A, or a knitted fabric. And, a short fiber chip,
a chopped strand, a milled fiber, or a method in which short fibers
are made into a spun yarn and arranged in parallel or random, or
processed into a woven fabric or a knitted fabric can also be
employed.
[0057] In the present invention, in case where a conductive
particle is used as the [D], the conductive particle may be at
least a particle which acts as an electrically good conductor, and
it is not limited to those consisting only of a conductor.
Preferably, it is a particle of which volume resistivity is 10 to
10.sup.-9 .OMEGA.cm, more preferably 1 to 10.sup.-9 .OMEGA.cm and
still more preferably 10.sup.-1 to 10.sup.-9.OMEGA.. When the
volume resistivity is too high, in the carbon fiber reinforced
composite material, a sufficient conductivity may not be obtained.
As the conductive particles, for example, a metal particle,
conductive polymer particles such as polyacetylene particle,
polyaniline particle, polypyrrole particle, polythiophene particle,
polyisothianaphthene particle or polyethylenedihydroxythiophene
particle, or a carbon particle, and other than that, a particle of
which nucleus of inorganic material is coated with a conductive
substance or a particle of which nucleus of organic material is
coated with a conductive substance can be used. Among them, since
they exhibit a high conductivity and stability, the carbon
particle, the particle of which nucleus of inorganic material is
coated with a conductive substance or the particle of which nucleus
of organic material is coated with a conductive substance are
especially preferably used.
[0058] In particular, like the embodiment satisfying the item (2)
of the present invention which is mentioned later, when a
thermoplastic resin is used as the organic material and the
particle of which thermoplastic resin nucleus is coated with a
conductive substance is used, it is preferable since a still more
excellent impact resistance can be realized in the carbon fiber
reinforced composite material to be obtained.
[0059] In case where a conductive fiber is used as the [D] in the
present invention, the conductive fiber may be at least a fiber
which acts as an electrically good conductor, and it is not limited
to those consisting only of a conductor. Preferably, it is a fiber
of which volume resistivity is 10 to 10.sup.-9 .OMEGA.cm, more
preferably 1 to 10.sup.-9 .OMEGA.cm, and still more preferably
10.sup.-1 to 10.sup.-9.OMEGA.. When the volume resistivity is too
high, a sufficient conductivity may not be obtained in the carbon
fiber reinforced composite material. As the conductive fiber, for
example, a metal fiber, a carbon fiber, a fiber of which core of
inorganic material is coated with a conductive substance or a fiber
of which core of organic material is coated with a conductive
substance, etc., can be used. In particular, like the embodiment
satisfying the item (2) of the present invention which is mentioned
later, when a thermoplastic resin is used as the organic material,
and a fiber of which core of thermoplastic resin is coated with a
conductive substance is used, a still more excellent impact
resistance can be realized in the carbon fiber reinforced composite
material to be obtained.
[0060] As to the volume resistivity mentioned here, a sample is set
to a cylindrical cell having 4 probe electrode, thickness and
resistivity value of the sample are measured in the condition in
which a pressure of 60 MPa is added to the sample, and a value
calculated from them is taken as the volume resistivity.
[0061] In the conductive particle or fiber [D] of the type coated
with the conductive substance, the conductive particle or fiber is
constituted with the inorganic material or organic material which
is the nucleus or core and the conductive layer consisting of the
conductive substance, and as desired, an adhesive layer which is
mentioned later may be provided between the nucleus or core and the
conductive layer.
[0062] In the conductive particle or fiber [D] of the type coated
with the conductive substance, as the inorganic material to be used
as the nucleus or core, an inorganic oxide, an inorganic-organic
complex, and carbon, etc., can be mentioned.
[0063] As the inorganic oxide, for example, a single inorganic
oxide and a complex inorganic oxide of 2 kinds or more such as of
silica, alumina, zirconia, titania, silicaalumina or silicazirconia
are mentioned.
[0064] As the inorganic-organic complex, for example,
polyorganosiloxane obtainable by hydrolysis of metal alkoxide
and/or metal alkylalkoxide or the like are mentioned.
[0065] Furthermore, as the carbon, a crystalline carbon or an
amorphous carbon is preferably used. As the amorphous carbon, for
example, "Bellpearl" (trademark) C-600, C-800, C-2000 (produced by
Kanebo, Ltd.), "NICABEADS" (trademark) ICB, PC, MC (produced by
Nippon Carbon Co. Ltd.) or the like are concretely mentioned.
[0066] In the conductive particle or fiber [D] of a type coated
with a conductive substance, in case where an organic material is
used as a nucleus or core, as the organic material used as the
nucleus or core, thermosetting resins such as an unsaturated
polyester resin, a vinyl ester resin, an epoxy resin, a benzoxazine
resin, a phenol resin, an urea-formaldehyde resin, a melamine
formaldehyde resin and a polyimide resin, thermoplastic resins such
as a polyamide resin, a phenol resin, an amino resin, an acrylic
resin, an ethylene polyvinyl acetate resin, a polyester resin, an
urea-formaldehyde resin, a melamine formaldehyde resin, an alkyd
resin, a polyimide resin, an polyurethane resin, and divinylbenzene
resin are mentioned. And, 2 kinds or more of the materials
mentioned here may be complexed and used. Among them, an acrylic
resin or divinylbenzene resin having an excellent heat resistance,
and a polyamide resin having an excellent impact resistance are
preferably used.
[0067] In the embodiment satisfying the item (2) of the present
invention, since the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E] is used as an essential component, even when the
thermoplastic resin particle or fiber [C] is not added, it is
possible to impart a high impact resistance and conductivity to the
carbon fiber reinforced composite material. As the thermoplastic
resin used as a material of the nucleus or core of the conductive
particle or fiber [E] used in the present invention, it is possible
to use the same ones as the above-exemplified various kinds of
thermoplastic resin which are used as the thermoplastic resin by
mixing and dissolving in the thermosetting resin. Among them, it is
preferable to use a thermoplastic resin of strain energy release
rate (G.sub.1c) of 1500 to 50000 J/m.sup.2 as the material of
nucleus or core. More preferably, it is 3000 to 40000 J/m.sup.2,
still more preferably, 4000 to 30000 J/m.sup.2. When the strain
energy release rate (G.sub.1c) is too small, an impact resistance
of the carbon fiber reinforced composite material may be
insufficient, and when it is too large, a stiffness of the carbon
fiber reinforced composite material may decrease. As such
thermoplastic resins, for example, a polyamide, a polyamideimide, a
polyethersulfone, a polyetherimide, etc., are preferably used, and
a polyamide is especially preferable. Among polyamides, nylon12,
nylon11 or nylon6/12 copolymer is preferably used. The evaluation
of G.sub.1c is, by using a resin plate prepared by molding the
thermoplastic resin which is the material of nucleus or core of the
[E], carried out according to the compact tension method or the
double tension method prescribed in ASTM D 5045-96.
[0068] In case where a conductive particle of which thermoplastic
resin nucleus is coated with a conductive substance is used as the
[E], as the thermoplastic resin particle shape, spherical,
nonspherical, porous, spicular, whisker-like, or flaky shaped may
also be acceptable, but spherical shape is preferable since it is
excellent in impregnating property to carbon fibers because it does
not lower flow ability of the thermosetting resin. And, since an
interlayer delamination, generated by a localized impact when a
drop impact (or localized impact) is added to the carbon fiber
reinforced composite material, is more reduced, the delamination
parts, caused by the above-mentioned localized impact, which are
starting points of breakage by stress concentration in case where a
stress is added to the carbon fiber reinforced composite material,
are not many, and since a contact probability with the carbon
fibers in the laminate layer is high to make a conductive paths
easy to be formed, it is preferable since it is possible to obtain
a carbon fiber reinforced composite material which realizes a high
impact resistance and conductivity.
[0069] In case where the conductive fiber of which thermoplastic
resin core is coated with a conductive substance is used as the
[E], as a shape of the core of thermoplastic resin fiber, either of
short fiber or long fiber can be used.
[0070] In case of the short fiber, as shown in JP-H02-69566A, a
method of using the short fiber like a particle, or a method of
using it by processing it into a mat is possible. In case of the
long fiber, as shown in JP-H04-292634A, a method of arranging long
fibers in parallel on a prepreg surface, or as shown in WO94016003,
a method of arranging in random is possible. Furthermore, it is
also possible to use it by processing it into sheet-like bases such
as a woven fabric as shown in JP-H02-32843A, or a non-woven or
knitted fabric as shown in WO94016003. And, methods of using as a
short fiber chip, a chopped strand, a milled fiber, or using by
making the short fiber into a spun yarn, by arranging in parallel
or random, or by processing into a woven or knitted fabric, can
also be employed.
[0071] At coating the core of thermoplastic resin fiber with the
conductive substance, a method of coating with the conductive
substance after the core of thermoplastic resin fiber is processed
into the above-mentioned shape, or a method of processing into the
above-mentioned shape after the core of thermoplastic resin fiber
is coated with the conductive substance, are mentioned. Either
method is preferably employed to the short fiber, long fiber,
chopped strand, and milled fiber. In case of the woven fabric,
knitted fabric or non-woven fabric, a method of processing them
into the above-mentioned shape after the core of thermoplastic
resin fiber is coated with the conductive substance is preferably
used. It is because, in case of the woven fabric, knitted fabric or
non-woven fabric, when the core of thermoplastic resin particle is
coated with the conductive substance after processed into such
shapes, a coating unevenness is generated and a conductivity of the
[E] may decrease, and it is not employed preferably.
[0072] In the conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E], as
the above-mentioned conductive material to coat the nucleus or
core, a metal or carbon can be mentioned. And, in such [E], a
conductive layer is constituted with the above-mentioned conductive
substance on surface of the thermoplastic resin nucleus or core,
but such conductive layer may be a continuous film of metal or
carbon, or may be an aggregate of fibrous or particulate conductive
substance such as a conductive fiber, a carbon black or a metal
fine particle. And, an adhesion layer which is mentioned later may
be provided between the thermoplastic resin which is the nucleus or
core and the conductive layer.
[0073] As the conductive substance constituting the conductive
layer in the conductive particle or fiber [D] of the type coated
with a conductive substance, and in the conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance [E], materials which act as an electrically
good conductor are acceptable and not limited to those consisting
only of a conductor. Preferably, it is a material of which volume
resistivity is 10 to 10.sup.-9 .OMEGA.cm, more preferably 1 to
10.sup.-9 .OMEGA.cm, still more preferably 10.sup.-1 to
10.sup.-9.OMEGA.. When the volume resistivity is too high, in the
carbon fiber reinforced composite material, a sufficient
conductivity may not be obtained. For example, carbon or metal are
mentioned, and such a conductive layer may be a continuous film of
a carbon or metal, or an aggregate of fibrous or particulate
conductive substances.
[0074] In case where a carbon is used as the conductive substance,
carbon blacks such as a channel black, a thermal black, a furnace
black, a ketjen black, and a hollow carbon fiber, etc., are
preferably used. Among them, a hollow carbon fiber is preferably
used, and its outer diameter is preferably 0.1 to 1000 nm, more
preferably 1 to 100 nm. When the outer diameter of the hollow
carbon fiber is too small or too large, it may be difficult to
produce such hollow carbon fibers.
[0075] The above-mentioned hollow carbon fiber may have a graphite
layer formed on its surface. At that time, a total number of the
constituting graphite layer is, preferably 1 to 100 layers, more
preferably 1 to 10 layers, still more preferably, 1 to 4 layers,
and especially preferable one has 1 to 2 layers.
[0076] In case where a metal is used as the conductive substance,
any metal is acceptable, but preferably, its normal electrode
potential is -2.0 to 2.0V, and more preferably -1.8 to 1.8V. When
the normal electrode potential is too low, it is unstable and may
not be preferable in view of safety, and when it is too high, the
processability or productivity may decrease. Here, the normal
electrode potential is expressed by difference between the
electrode potential when a metal is immersed in a solution
containing its metal ion and the normal hydrogen electrode
(platinum electrode immersed in 1 N HCl solution which contact with
hydrogen at 1 atm.) potential. For example, Ti: -1.74V, Ni: -0.26V,
Cu: 0.34V, Ag: 0.80V and Au: 1.52V.
[0077] In case where the above-mentioned metal is used, it is
preferable to be a metal used by plating. As preferable metals,
since a corrosion based on potential difference with carbon fiber
can be prevented, platinum, gold, silver, copper, tin, nickel,
titanium, cobalt, zinc, iron, chromium, aluminum, etc., are used
and among them, since a high conductivity of volume resistivity 10
to 10.sup.-9 .OMEGA.cm and stability are exhibited, platinum, gold,
silver, copper, tin, nickel, or titanium are especially preferably
used. Whereas, these metals may be used alone, or may be used as an
alloy of which main components are these metals.
[0078] As methods for carrying out metal plating by using the
above-mentioned metal, a wet plating and a dry plating are
preferably used. As the wet plating, methods such as electroless
plating, displacement plating and electroplating can be employed,
but among them, since it is possible to carry out plating to a
nonconductor, a method by the electroless plating is preferably
used. As the dry plating, methods such as vacuum vapor deposition,
plasma CVD (chemical vapor deposition), optical chemical vapor
deposition, ion plating and sputtering can be employed, but since
it is possible to obtain an excellent close contactness at a low
temperature, a method by the sputtering is preferably employed.
[0079] Furthermore, the metal plating may be a coating film of a
single metal or a coating film of a plurality of layers of a
plurality of metals. In case where metal plating is carried out, it
is preferable that the outermost surface is formed with a plating
film of a layer consisting of gold, nickel, copper or titanium. By
making the outermost surface with the above-mentioned metal, it is
possible to reduce a connection resistance value or to stabilize
the surface. For example, when a gold layer is formed, a method in
which a nickel layer is formed by electroless nickel plating, and
after that, a gold layer is formed by a displacement gold plating
is preferably employed.
[0080] Furthermore, it is also preferable to use a metal fine
particle as the conductive substance constituting the conductive
layer. In this case, as a metal to be used as the metal fine
particle, in order to prevent a corrosion due to potential
difference with the carbon fiber, platinum, gold, silver, copper,
tin, nickel, titanium, cobalt, zinc, iron, chromium, aluminum, or
an alloy containing these metals as main components, or tin oxide,
indium oxide, indiumtin oxide (ITO), etc., are preferably used.
Among them, because of high conductivity and stability, platinum,
gold, silver, copper, tin, nickel, titanium or an alloy containing
them as main components are especially preferably used. Whereas, at
this time, the fine particle means, a particle having an average
diameter smaller (usually 0.1 times or less is meant) than the
average diameter of the conductive particle or fiber [D] or of the
conductive particle or fiber of which thermoplastic resin nucleus
or core is coated with a conductive substance [E].
[0081] As a method of coating the nucleus or core with the
above-mentioned metal fine particle, a mechanochemical bonding
technique is preferably used. The mechanochemical bonding is a
method of creating a composite fine particle in which a plural of
different material particles are mechanochemically bonded in a
molecular level by adding a mechanical energy to create a strong
nano bond in their interface, and in the present invention, the
metal fine particle is bonded to the inorganic material or the
nucleus or core of organic material, to coat said nucleus or core
with the metal fine particle.
[0082] In case where the metal fine particle is coated to the
nucleus of inorganic material or organic material (including
thermoplastic resins), a particle diameter of this metal fine
particle is preferably 1/1000 to 1/10 times of average particle
diameter of the nucleus, more preferably 1/500 to 1/100 times. A
metal fine particle of a too small particle diameter is difficult
to be produced in some cases, and on the contrary, when the
particle diameter of metal fine particle is too large, a coating
unevenness arises in some cases. Furthermore, in case where a metal
fine particle is coated to a core of inorganic material or organic
material, a particle diameter of this metal fine particle is
preferably 1/1000 to 1/10 times of average fiber diameter of the
core, more preferably 1/500 to 1/100 times. A metal fine particle
of a too small particle diameter is difficult to be produced in
some cases, and on the contrary, when the particle diameter of
metal fine particle is too large, a coating unevenness arises in
some cases.
[0083] In the conductive particle or fiber [D] and the conductive
particle or fiber of which thermoplastic resin nucleus or core is
coated with a conductive substance [E] which are types coated with
a conductive substance, an adhesive layer may not be present
between the nucleus or core and the conductive layer, but it may be
present in case where the nucleus or core and the conductive layer
are easy to be peeled off. As main component of the adhesive layer
of this case, a vinyl acetate resin, an acrylic resin, a vinyl
acetate-acrylic resin, a vinyl acetate-vinyl chloride resin, an
ethylene polyvinyl acetate resin, an ethylene polyvinyl acetate
resin, an ethylene-acrylic resin, a polyamide, a polyvinyl acetal,
a polyvinyl alcohol, a polyester, a polyurethane, a urea resin,
melamine formaldehyde resin, a phenol resin, a resolcinol resin, an
epoxy resin, a polyimide, a natural rubber, a chloroprene rubber, a
nitrile rubber, an urethane rubber, an SBR, a regenerated rubber, a
butyl rubber, an aqueous vinylurethane, an .alpha.-olefin, a
cyanoacrylate, a modified acrylic resin, an epoxy resin, an
epoxy-phenol, a butylal-phenol, a nitrile-phenol, etc., are
preferable, and among them, a vinyl acetate resin, an acrylic
resin, an vinyl acetate-acrylic resin, a vinyl acetate-vinyl
chloride resin, an ethylene polyvinyl acetate resin, an ethylene
polyvinyl acetate resin, an ethylene-acrylic resin and epoxy resin
or the like are mentioned.
[0084] In the conductive particle or fiber [D] which is the type
coated with a conductive substance and the conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance [E], as the conductive particle or fiber which
is coated with the conductive substance, it is good to use those of
which volume ratio expressed by [volume of nucleus or core]/[volume
of conductive layer] is preferably 0.1 to 500, more preferably 1 to
300, still more preferably 5 to 100. When such a volume ratio is
less than 0.1, not only a weight of the obtained carbon fiber
reinforced composite material increases, but also, in the resin
compounding, a uniform dispersion may be impossible, and on the
contrary, when it exceeds 500, in the obtained carbon fiber
reinforced composite material, a sufficient conductivity may not be
obtained.
[0085] It is preferable that a specific gravity of the conductive
particle or fiber used in the present invention (the conductive
particle or fiber [D] and the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E]) is at most 3.2. When the specific gravity of the
conductive particle or fiber exceeds 3.2, not only a weight of the
obtained carbon fiber reinforced composite material increases, but
also, in the resin compounding, a uniform dispersion may be
impossible. From such a viewpoint, the specific gravity of the
conductive particle or fiber is preferably, 0.8 to 2.2. When the
specific gravity of the conductive particle or fiber is less than
0.8, in the resin compounding, a uniform dispersion may be
impossible.
[0086] As the conductive particle or fiber [D] and the conductive
particle or fiber of which thermoplastic resin nucleus or core is
coated with a conductive substance [E], in case where a particle is
used, its shape may be spherical, nonspherical, porous, spicular,
whisker shaped or flaky, but a spherical one is more excellent in
impregnating property into the carbon fiber since it does not
impair flow ability of the thermosetting resin. And, since an
interlayer delamination, generated by a localized impact when a
drop impact (or localized impact) is added to the carbon fiber
reinforced composite material, is more reduced, the delamination
parts, caused by the above-mentioned localized impact, which would
be starting points of breakage by stress concentration in case
where a stress is added to the carbon fiber reinforced composite
material, are not many, and since a contact probability with the
carbon fibers in the laminate layer is high to make a conductive
paths easy to be formed, it is preferable in view of capability of
obtaining a carbon fiber reinforced composite material which
realizes a high impact resistance and conductivity.
[0087] In case where a fiber is used as the conductive particle or
fiber [D] and the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E], as its shape, both of short fiber or long fiber can
be used. In case of short fiber, a method of using the short fiber
in the same way as particle as shown in JP-H02-69566A or a method
of using it by processing it into a mat, is possible. In case of
long fiber, a method of arranging long fibers in parallel on a
prepreg surface as shown in JP-H04-292634A, or a method of
arranging randomly as shown in WO94016003 is possible. Furthermore,
it can also be used by processing it into sheet-like bases such as
a woven fabric as shown in JP-H02-32843A, a non-woven fabric, or
knitted fabric as shown in WO94016003. And, a short fiber chip, a
chopped strand, a milled fiber, or a method in which short fibers
are made into a spun yarn and arranged in parallel or random, or
processed into a woven fabric or a knitted fabric can also be
employed.
[0088] In the conductive fiber [D] and the conductive fiber of
which core of thermoplastic resin fiber is coated with a conductive
substance [E] which is a type coated with a conductive substance, a
method in which, at coating a material of the core with the
conductive substance, after the core of conductive fiber is
processed into the above-mentioned shape, the conductive substance
is coated, or a method in which, after coating the core of
conductive fiber with the conductive substance, it is processed
into the above-mentioned shape, are mentioned. For the short fiber,
long fiber, chopped strand, milled fiber, etc., both methods are
preferably employed. For the woven fabric, knitted fabric or
non-woven fabric, a method in which, after the conductive substance
is coated to the core of conductive fiber, it is processed into the
above-mentioned shape, is preferably employed. A method in which,
after the conductive fiber core is processed into the
above-mentioned shape, it is coated with the conductive substance
is not preferable since a coating unevenness arises and a
conductivity of the conductive fiber used as the [D] and [E] may
decrease.
[0089] In the embodiment the present invention satisfying the item
(1) (use of the thermoplastic resin particle or fiber together with
the conductive particle or fiber), a weight ratio expressed by
[compounding amount of thermoplastic resin particle or fiber (parts
by weight)]/[compounding amount of conductive particle or fiber
(parts by weight)] is 1 to 1000, preferably 10 to 500 and more
preferably 10 to 100. It is because, when the weight ratio becomes
less than 1, a sufficient impact resistance cannot be obtained in
the obtained carbon fiber reinforced composite material, and when
the weight ratio becomes more than 1000, a sufficient conductivity
cannot be obtained in the obtained carbon fiber reinforced
composite material.
[0090] In the embodiment of the present invention satisfying the
item (1) (use of the thermoplastic resin particle or fiber together
with the conductive particle or fiber), it is preferable that an
average diameter of the conductive particle or fiber [D] (average
particle diameter or average fiber diameter) is same or more than
an average diameter of the thermoplastic resin particle or fiber
[C] (average particle diameter or average fiber diameter), and the
average diameter is at most 150 .mu.m. In case where the average
diameter of the conductive particle or fiber [D] is smaller than
the average diameter of the thermoplastic resin particle or fiber
[C], the conductive particle or fiber [D] is buried in interlayer
of the thermoplastic resin particle or fiber [C] which is
insulative, and a conductive path between the carbon fiber in the
layer and the conductive particle or fiber [D] is difficult to be
formed, and a sufficient improving effect of conductivity may not
be obtained.
[0091] Furthermore, in the present invention, it is preferable that
average diameters of the thermoplastic resin particle or fiber [C],
the conductive particle or fiber [D] and the conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance [E] are at most 150 .mu.m. When the average
diameter exceeds 150 .mu.m, since arrangement of the reinforcing
fibers is disturbed, or, in case where a particle layer is formed
around the prepreg surface, the interlayer of the obtained
composite material becomes thicker than necessary as mentioned
later, physical properties may decrease when it is formed into a
composite material. The average diameter is, preferably 1 to 150
.mu.m, more preferably 3 to 60 .mu.m, especially preferably 5 to 30
.mu.m. When the average diameter is too small, the particle
penetrates between fibers of the reinforcing fiber and not
localizes in the interlayer portion of the prepreg laminate, and an
effect of the presence of particle is not sufficiently obtained,
and an impact resistance may decrease.
[0092] Here, method of determination of the average diameters in
case of the particle or in case of the fiber are explained
respectively.
[0093] As to the average diameter of the particle (average particle
diameter), for example, it can be determined as the average value
(n=50) of the particle diameter by photographing the particle at a
magnification of 1000 times or more by a microscope such as a
scanning electron microscope, selecting a particle arbitrarily, and
taking a diameter of circumscribed circle of the particle as the
particle diameter. And, when the volume ratio expressed by [volume
of nucleus]/[volume of conductive layer] of the conductive particle
coated with a conductive substance is determined, at first, an
average particle diameter of nucleus of the conductive particle is
determined by the above-mentioned method, or an average diameter of
the conductive particle (average particle diameter) is determined
by the above-mentioned method. After that, a cross-section of the
conductive particle coated with a conductive substance is
photographed by a scanning type microscope at a magnification of
10,000 times, the thickness of conductive layer is measured (n=10),
and its average value is calculated. Such a determination is
carried out for the above-mentioned arbitrarily selected conductive
particles (n=50). The average particle diameter of nucleus of the
conductive particle and 2 times of the average value of thickness
of the conductive layer are added together and taken as the average
diameter of conductive particle (average particle diameter), or the
average diameter of conductive particle (average particle diameter)
minus 2 times of the average value of thickness of the conductive
layer is taken to determine the average diameter of nucleus of the
conductive particle (average particle diameter). And, by using the
average diameter of nucleus of the conductive particle (average
particle diameter) and the average diameter of conductive particle
(average particle diameter), it is possible to calculate a volume
ratio expressed by [volume of nucleus]/[volume of conductive
layer].
[0094] As to the average diameter of fiber (average fiber
diameter), for example, by a microscope such as a scanning electron
microscope, a fiber cross-section is photographed at a
magnification of 1000 times or more, a fiber cross-section is
arbitrarily selected, a diameter of circumscribed circle of the
fiber cross-section is take as the fiber diameter, and it is
possible to obtain an average value (n=50) of the fiber diameter.
And, when the volume ratio expressed by [volume of core]/[volume of
conductive layer] of the conductive fiber coated with the
conductive substance is determined, first, the average fiber
diameter of core of the conductive fiber is measured by the
above-mentioned means, or the average diameter of the conductive
fiber (average fiber diameter) is measured by the above-mentioned
means. After that, a cross-section of the conductive fiber coated
with the conductive substance is photographed by a scanning
electron microscope at a magnification of 10,000 times, a thickness
of conductive layer is measured (n=10), and its average value is
calculated. Such a measurement is carried out for the
above-mentioned arbitrarily selected conductive fibers (n=50). The
average diameter of core of the conductive fiber (average fiber
diameter) and 2 times of the average value of thickness of the
conductive layer are added and taken as the average diameter of the
conductive fiber (average fiber diameter), or the average diameter
of the conductive fiber (average fiber diameter) minus 2 times of
the average value of thickness of the conductive layer is taken to
determine the average diameter of core of the conductive fiber
(average fiber diameter). And, based on the average diameter of
core of the conductive fiber (average fiber diameter) and the
average diameter of the conductive fiber (average fiber) diameter,
it is possible to calculate the volume ratio expressed by [volume
of core]/[volume of conductive layer].
[0095] In the prepreg of the present invention, the carbon fiber
weight ratio is preferably 40 to 90%, more preferably 50 to 80%.
When the carbon fiber weight ratio is too low, a weight of the
obtained composite material becomes too heavy, an advantage of the
fiber reinforced composite material that is excellent in specific
strength and specific modulus may be impaired, and when the carbon
fiber weight ratio is too high, a defective impregnation of resin
occurs, the obtained composite material may have many voids, and
its mechanical characteristics may significantly decrease.
[0096] In the prepreg of the present invention, it is preferable
that every one of the thermoplastic resin particle or fiber [C],
conductive particle or fiber [D] and the conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance [E] localizes around surface portion of the
prepreg. In other words, it is preferable that a layer abundant in
the particles or fibers of the above-mentioned [C], [D] and [E],
that is, a layer in which, when the cross-section is observed, a
condition capable of confirming clearly that the particles or
fibers of the above-mentioned [C], [D] and [E] localizes
(hereafter, may be referred to as inter-formative layer.), is
formed around the surface portion of the prepreg. By this, in case
where prepregs are made into a carbon fiber reinforced composite
material by laying-up and by curing the matrix resin, an interlayer
in which the particles or fibers of the above-mentioned [C], [D]
and [E] are localized between carbon fiber layers is formed, and by
that, since toughness of the carbon fiber interlayer increases, and
simultaneously, the particles or fibers of the above-mentioned [D]
and [E] contained in the inter-formative layer can form a
conductive path in the carbon fiber interlayer, high level impact
resistance and conductivity are exhibited in the obtained carbon
fiber reinforced composite material.
[0097] FIG. 1 is an example of a cross-sectional view of a
representative prepreg of the present invention. The present
invention is explained in more detail with reference to FIG. 1.
[0098] The prepreg of the present invention shown in FIG. 1 has,
between two of the carbon fiber layer 1 constituted with the carbon
fiber 5 and the thermosetting resin 6, the inter-formative layer 2
containing the thermosetting resin 6, the thermoplastic resin
particle 3 and the conductive particle 4. By forming the
inter-formative layer 2, since toughness of the carbon fiber
interlayer increases, and simultaneously, the conductive particle 4
contained in the inter-formative layer 2 can form a conductive path
in the carbon fiber interlayer, a high level impact resistance and
conductivity are exhibited in the obtained carbon fiber reinforced
composite material.
[0099] From such a viewpoint, it is preferable that the
above-mentioned inter-formative layer is present, with respect to
the prepreg thickness 100%, in the range of 20% thickness from at
least one side surface of the prepreg, more preferably, in the
range of 10% thickness. And, it is preferable that the
above-mentioned inter-formative layer is present, in view of
improving convenience at producing the carbon fiber reinforced
composite material, on both of front and back sides of the
prepreg.
[0100] It is preferable that 90 to 100 wt %, preferably 95 to 100
wt % of the particles or fibers of the above-mentioned [C], [D] and
[E], with respect to the respective total amounts, localize in the
above-mentioned inter-formative layer.
[0101] The thickness of the above-mentioned inter-formative layer
with respect to the prepreg and the containing ratio of the
particles or fibers of the above-mentioned [C], [D] and [E]
contained in said inter-formative layer can be evaluated, for
example, by the following method.
[0102] As to the thickness of the inter-formative layer with
respect to the prepreg, a plural of laid-up prepregs are contacted
closely by holding between 2 smooth surface polytetrafluoroethylene
resin plates, and gelled and cured by gradually raising temperature
to curing temperature in 7 days to prepare a platy cured prepreg
product. By using this cured prepreg, a magnified photograph of the
cross-section is taken. By using this cross-section photograph, a
thickness of the inter-formative layer with respect to the prepreg
is measured. In concrete, on a photograph such as shown in FIG. 1,
it is measured at arbitrarily selected at least 10 positions of the
inter-formative layer 2 between the carbon fiber layers 1, and
their average is taken as a thickness of the inter-formative
layer.
[0103] As to the containing ratio of particles or fibers of the
above-mentioned [C], [D] and [E] contained in the inter-formative
layer, a single layer prepreg is closely contacted by holding
between 2 smooth surface polytetrafluoroethylene resin plates,
gelled and cured by gradually raising temperature to curing
temperature in 7 days to prepare a platy cured prepreg product. On
both sides of this prepreg, 2 lines which are parallel to the
surface of cured product of the prepreg are drawn at positions of
20% depth, with respect to the thickness, from the surface of the
cured product. Next, a total area of the above-mentioned particle
or fiber present between the prepreg surface and the
above-mentioned lines, and a total area of the particle or fiber
present throughout the thickness of prepreg are determined, and
calculate the containing ratio of the particle or fiber present in
20% depth range from the prepreg surface, with respect to the
prepreg thickness 100%. Here, the total area of the above-mentioned
particle or fiber is determined by clipping the particle or fiber
portion from the cross-section photograph and weighing its weight.
In case where a distinction of particles dispersed in the resin
after taking a photograph is difficult, a means of dyeing the
particle can also be employed.
[0104] Furthermore, in the present invention, it is preferable that
a total amount of the thermoplastic resin particle or fiber [C],
the conductive particle or fiber [D] and the conductive particle or
fiber of which thermoplastic resin nucleus or core is coated with a
conductive substance [E] is, with respect to the prepreg, in the
range of 20 wt % or less. When the total amount of the particles or
fibers of the above-mentioned [C], [D] and [E] exceeds, with
respect to the prepreg, 20 wt %, not only it becomes difficult to
mix with the base resin, but also tack and draping properties of
the prepreg may decrease. That is, in order to impart impact
resistance while maintaining characteristics of the base resin, it
is preferable that the total amount of the particles or fibers of
the above-mentioned [C], [D] and [E] is, with respect to the
prepreg, 20 wt % or less, more preferably 15 wt % or less. In order
to make handling of the prepreg still more excellent, it is more
preferable to be 10 wt % or less. It is preferable that the total
amount of the particles or fibers of the above-mentioned [C], [D]
and [E] is, in order to achieve a high impact resistance and
conductivity, with respect to the prepreg, 1 wt % or more, more
preferably 2 wt % or more.
[0105] In the present invention, among the conductive particle or
fiber [D] and the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E], there are some of which adhesion with the
thermosetting resin [B] are low, but when those subjected to a
surface treatment are used, it is possible to realize a strong
adhesion with the thermosetting resin, and a further improvement of
impact resistance becomes possible. From such a viewpoint, it is
preferable to use those subjected to at least one kind of treatment
selected from the group consisting of a coupling treatment, an
oxidation treatment, an ozonation, a plasma treatment, a corona
treatment, and a blast treatment. Among them, those subjected to a
surface treatment of a coupling treatment, an oxidation treatment
or a plasma treatment which is capable of forming a chemical bond
or hydrogen bond with the thermosetting resin is preferably used
since a strong adhesion with the thermosetting resin can be
realized.
[0106] Furthermore, at the above-mentioned surface treatment, in
order to shorten the surface treatment time or to assist the
dispersion of the conductive particle or fiber [D] and the
conductive particle or fiber of which thermoplastic resin nucleus
or core is coated with a conductive substance [E], it is possible
to carry out the surface treatment while applying heat and
ultrasonic wave. It is preferable that the heating temperature is
at most 200.degree. C., preferably 30 to 120.degree. C. That is,
when the temperature is too high, a bad smell may be generated to
worsen the environment or operation cost may increase.
[0107] As a coupling agent used for the coupling treatment, a
silane-based, a titanium-based or an aluminum-based one is used,
and these coupling agent may be used alone or in combination. When
a coupling agent is not appropriate, since adhesion with the
treated particle or fiber and the thermosetting resin becomes
insufficient, impact resistance may decrease. In order to avoid
such a problem, it is preferable to use a coupling agent having a
strong affinity to, or capable of chemical bonding to realize a
strong adhesion with a thermosetting resin to be used. In order to
increase the affinity to the thermosetting resin, it is preferable
to select a coupling agent having a substituted group of which
molecular structure or polarity is similar to the molecular
structure or polarity of a thermosetting resin to be used.
[0108] In order to surely increase adhesion further, it is
preferable to use a coupling agent capable of forming a chemical
bond with the thermosetting resin which is the matrix resin. In
case where a resin capable of radical polymerization such as an
unsaturated polyester resin, a diallyl phthalate resin or a
maleimide resin is the matrix resin, a coupling agent having a
substituted group with a double bond such as vinyl group, allyl
group, acryloyl group, methacryloyl group, cyclohexenyl group, in
case where an epoxy resin is the matrix resin, a coupling agent
having epoxy group, phenolic hydroxyl group, carboxyl group,
mercapto group, amino group or a monosubstituted amino group, in
case where a phenol resin is the matrix resin, a coupling agent
having epoxy group or phenolic hydroxyl group, in case where a
polyurethane resin is the matrix resin, a coupling agent having
hydroxyl group, amino group or a monosubstituted amino group, in
case where a melamine formaldehyde resin or a urea-formaldehyde
resin is the matrix resin, a coupling agent having amide group,
ureido group, amino group or a monosubstituted amino group, in case
where a maleimide resin is the matrix resin, other than a coupling
agent having a double bond, a coupling agent having amino group or
a monosubstituted amino group, in case where a cyanate resin is the
matrix resin, a coupling agent having carboxyl group, epoxy group,
hydroxyl group, amino group or a monosubstituted amino group, can
preferably be used.
[0109] As a coupling treatment, silane coupling treatment is
preferable since coupling agents having various functional groups
are easily available. As concrete examples of the silane coupling
agent, as aminosilanes, 3-aminopropyl trimethoxysilane,
3-aminopropyl triethoxysilane, 3-(2-aminoethyl)aminopropyl
trimethoxysilane, 3-(phenylamino)propyl trimethoxysilane,
3-(2-aminoethyl)amino-3-(2-aminoethyl)aminopropylmethyl
dimethoxysilane, etc., as epoxysilanes, 3-glycidoxypropyl
trimethoxysilane, 3-glycidoxypropyl triethoxysilane,
3-glycidoxypropylmethyl dimethoxysilane,
2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
.gamma.-methacryloxypropyl trimethoxysilane, etc., as vinylsilanes,
vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane,
vinyltris(2-methoxyethoxy)silane, vinyltriacetoxysilane, etc., can
be mentioned. In particular, a silane coupling agent having an
epoxy group, amino group or a monosubstituted amino grouping in
molecule is especially preferably used since it is applicable to a
wide range of resin and its reactivity is also high.
[0110] In the present invention, in case where the conductive
particle or fiber [D] and the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E] (hereafter, may be referred to as substance to be
treated) are subjected to a coupling treatment, it is preferable to
compound a coupling agent, with respect to these particle or fiber
100 parts by weight, preferably 0.01 to 30 parts by weight, more
preferably 0.1 to 10 parts by weight. When the compounding amount
of the coupling agent is too small, an adhesion with the
thermosetting resin may not be sufficiently exhibited, and on the
contrary, when it is too large, mechanical properties of cured
product may decrease.
[0111] In the present invention, a coupling treatment may be
carried out by attaching a coupling agent to the substance to be
treated and heat treating directly, or the coupling agent and the
substance to be treated are added to the thermosetting resin
beforehand, and the coupling treatment may also be carried out by a
heat treatment at curing the prepreg.
[0112] As the oxidation treatment, it is not especially limited as
far as the surface of the substance to be treated can be oxidized,
but it is possible to employ a chemical liquid oxidation treatment
and an electrolytic oxidation treatment. Among them, a chemical
liquid oxidation treatment is preferably used.
[0113] The chemical liquid oxidation treatment is a method of
oxidation treatment in an acidic aqueous solution. As the acidic
aqueous solution, for example, an aqueous solution containing
sulfuric acid, fuming sulfuric acid, nitric acid, fuming nitric
acid, hydrochloric acid, phosphoric acid, carbonic acid, boric
acid, oxalic acid, fluoric acid, formic acid, butyric acid, acetic
acid, boric acid-sulfuric acid, chlorosulfuric acid, chloroacetic
acid, sulfosalicylic acid, sulfoacetate, maleic acid, chromic
anhydride, hypochlorous acid, acrylic acid, sulfonic acid,
fluorosulfonic acid, trifluoromethane sulfuric acid,
trifluoromethane sulfonic acid, ammonium sulfate, ammonium formate,
ammonium dihydrogen phosphate, ammonium oxalate, ammonium hydrogen
sulfate, etc., may be used alone or in combination. By subjecting
to the oxidation treatment, a functional group such as hydroxyl
group or carboxyl group is chemically generated on the substance to
be treated, and a strong adhesion is realized by letting the
functional group make a chemical bond and/or hydrogen bond with the
matrix resin. Among them, sulfuric acid, nitric acid or mixed acid
thereof which shows strong acidity are preferably used.
[0114] As to a concentration of the acidic aqueous solution, it is
preferably 0.01 wt % or more, more preferably 10 wt % or more and
still more preferably 50 wt % or more. As the concentration becomes
higher, the treatment time becomes shorter or there is more effect
of loosening an aggregation of the substance to be treated. When an
oxidant such as ozone, hydrogen peroxide, lead dioxide is added to
the acidic aqueous solution, it is preferable since the oxidizing
power increases.
[0115] As the surface treatment by ozone, in general, a method in
which the substance to be treated is heat treated by introducing
ozone into a chamber having a heater is preferably used. In this
case, surface of the above-mentioned particle or fiber is modified
to an activated surface, and surface wettability with the matrix
resin is greatly improved, to enable to realize a strong adhesion.
Furthermore, a method in which the substance to be treated is
subjected to a photo oxidation treatment by an ultraviolet light
irradiation under an ozone atmosphere is preferably employed.
[0116] As the surface treatment by plasma, a method of subjecting
to a plasma treatment under reduced pressure by introducing a
reactive gas into a chamber is preferably employed. As the reactive
gas, helium, neon, argon, nitrogen, ammonia, oxygen, nitrous oxide,
nitrogen monooxide, nitrogen dioxide, carbon monooxide, carbon
dioxide, cyanogen bromide, hydrogen cyanide, hydrogen, steam, air,
sulfur dioxide gas, hydrogen sulfide, etc., may be used alone or in
combination. By carrying out a plasma treatment to the substance to
be treated, it is modified to an activated surface, and surface
wettability with the matrix resin is greatly improved, to enable to
realize a strong adhesion.
[0117] As discharge frequencies (alternating current) of the
plasma, a high frequency wave, a low frequency wave or a microwave
can be used, and a direct current can also be used. As treating
apparatuses, there are an internal electrode system in which an
electrode is installed inside a vacuum apparatus and an external
electrode system in which an electrode is installed outside the
vacuum apparatus, but in the present invention, both systems can be
used. As to the electrode shape, a platy, rod-like, cylindrical can
be used in combination depending on its purpose, but when, as a
discharge electrode, a metal rod of its surface is coated with a
glass, and as an earth electrode, a metal, for example, stainless
steel plate or drum are used in an interval between electrodes of,
preferably 0.5 to 30 cm, more preferably 2 to 10 cm, it is
preferable since there is no discharge unevenness, to enable a
uniform treatment. It is preferable that the electrode is cooled
with water or the like, if necessary.
[0118] As the surface treatments by the corona treatment, for
example, methods disclosed in JP-S48-5043B, JP-S47-51905B,
JP-S47-28067A, JP-S49-83767A, JP-S51-41770A, JP-S51-131576A, etc.,
can be employed. By carrying out the corona treatment to the
substance to be treated, it is modified into an activated surface,
and surface wettability with the matrix resin is greatly improved,
to enable to realize a strong adhesion.
[0119] As surface treatments by the blast treatment, there are a
wet method and a dry method, and they are carried out by blasting a
fine particle projectile material contained in water or compressed
air flow to surface of the conductive particle or fiber [D] and the
conductive particle or fiber of which thermoplastic resin nucleus
or core is coated with a conductive substance [E] and they are
treating methods preferably employed to the conductive fibers [D]
and [E]. By this way, the surface area is enlarged by forming fine
unevenness on its surface, and it is possible to increase adhesion
power between the matrix resin and the substance to be treated. As
kinds of the projectile material, for example, glass beads, silicic
anhydride, alumina, diamond, red iron oxide, etc., are mentioned.
And, as a particle diameter of the projectile material,
approximately 100 to 5000 .mu.m is used in many cases. Generally
saying, by selecting kind of the projectile material, particle
diameter and ejecting pressure of the projectile material according
to its purpose, it is possible to carry out the surface treatment
into the most appropriate surface roughness.
[0120] The prepreg of the present invention can be produced by
applying publicly known methods such as disclosed in JP-H01-26651A,
JP-S63-170427A or JP-S63-170428A.
[0121] In concrete, the following 3 methods can be exemplified.
[0122] First method is a method in which, by putting and pressing a
resin film, of the thermosetting resin [B] coated on a release
paper or the like, to both sides or one side of the carbon fiber
[A] paralleled in sheet like, to impregnate with the thermosetting
resin [B], to prepare a primary impregnate prepreg, and a separate
resin film containing at least one of the following (1) and (2) in
the thermosetting resin [B] is sticked on its both sides or one
side.
[0123] (1) the thermoplastic resin particle or fiber [C] and the
conductive particle or fiber [D]
[0124] (2) the conductive particle or fiber of which thermoplastic
resin nucleus or core is coated with a conductive substance [E]
[0125] Here, instead of putting the separate resin film containing
at least any one of the items (1) and (2) in the thermosetting
resin [B], it is also possible to scatter or put at least any one
of the items (1) and (2) only on the above-mentioned primary
impregnate prepreg.
[0126] Second method is a method in which, to the primary
impregnate prepreg prepared by the first method, a separate resin
film of the thermosetting resin [B] coated on a release paper or
the like of which surface at least any one of the above-mentioned
(1), (2) is scattered or sticked, is sticked to both sides or one
side of the above-mentioned primary impregnate prepreg.
[0127] Third method is a method in which a resin film, in which the
thermosetting resin [B] containing at least any one of the
above-mentioned (1), (2) is coated on a release paper or the like,
is put and pressed to both sides or one side of the carbon fiber
[A] paralleled in sheet like, to impregnate with the thermosetting
resin [B] containing at least any one of the above-mentioned (1),
(2), to prepare a prepreg.
[0128] The carbon fiber reinforced composite material of the
present invention can be produced by laying-up the above-mentioned
prepreg of the present invention, and by heat.cndot.pressing to
cure the heat curable resin [B]. Here, as a method for imparting
heat.cndot.pressing, a press forming, an autoclave molding, a bag
molding method, a wrapping tape method and an internal pressure
molding method, etc., are employed, and especially the autoclave
molding is preferably employed.
[0129] The carbon fiber reinforced composite material of the
present invention is, since it is excellent in strength, stiffness,
impact resistance and conductivity, etc., widely used in aerospace
application and in general industrial application, etc. In more
concrete, in the aerospace application, it is preferably used for
an aircraft primary structural member application such as main
wing, tail wing and floor beam, for an aircraft secondary
structural member application such as flap, aileron, cowl, fairing
and interior material, and for rocket motor case and artificial
satellite structural material application, etc. Among such
aerospace applications, especially aircraft primary structural
material applications in which impact resistance and lightning
protection are necessary, especially for fuselage skin, main wing
skin and tail wing skin, the carbon fiber reinforced composite
material by the present invention is especially preferably used.
And, in general industrial applications, it is preferably used for
structural material of mobiles such as cars, ships and railway
vehicles, and for a driveshaft, a leaf spring, a windmill blade, a
pressure vessel, a flywheel, a roller for paper making, a roofing
material, a cable, a reinforcing bar, an application for computer
such as an IC tray or kyotai (housing) of notebook computer and for
a civil engineering/building application such as a
repairing/reinforcing material, etc. Among them, for an automotive
outer panel, an outer panel of ship, an outer panel of railway
vehicle, a windmill blade and an IC tray or kyotai (housing) of
notebook computer, the carbon fiber reinforced composite material
by the present invention is especially preferably used.
EXAMPLES
[0130] Hereafter, the present invention is explained in more detail
with reference to the examples. In order to obtain the prepreg of
each example, the following materials were used.
<Carbon Fiber>
[0131] "Torayca (trademark)" T800S-24K-10E (carbon fiber, number of
fiber 24,000 fibers, tensile strength 5.9 GPa, tensile modulus 290
GPa, tensile strain 2.0%, produced by Toray Industries, Inc.)
[0132] "Torayca (trademark)" T700S-24K-50C (carbon fiber, number of
fiber 24,000 fibers, tensile strength 4.9 GPa, tensile modulus 230
GPa, tensile strain 2.1%, produced by Toray Industries, Inc.)
<Thermosetting Resin>
[0133] Bisphenol A type epoxy resin, "Epikote (trademark)" 825
(produced by Japan Epoxy Resins Co., Ltd.)
[0134] Tetraglycidyldiaminodiphenylmethane, ELM434 (produced by
Sumitomo Chemical Co., Ltd.)
[0135] Polyethersulfone having hydroxyl group on its ends
"Sumikaexcel (trademark)" PES5003P (produced by Sumitomo Chemical
Co., Ltd.)
[0136] 4,4'-Diaminodiphenyl sulfone (produced by Mitsui Fine
Chemical Inc.)
<Thermoplastic Resin Particle>
[0137] Nylon12 particle SP-10 (produced by Toray Industries, Inc.,
shape: true sphere)
[0138] Epoxy modified nylon particle A obtained by the following
production method
[0139] A transparent polyamide ("Grilamid (trademark)" -TR55,
produced by EMSER WERKE AG) 90 parts by weight, epoxy resin
(product name "Epikote (trademark)" 828, produced by Yuka-Shell
Epoxy Co., Ltd.) 7.5 parts by weight and a hardener (product name
"Tohmide (trademark)" #296, produced by Fuji Kasei Kogyo Co., Ltd.)
2.5 parts by weight were added to a mixed solvent of chloroform 300
parts by weight and methanol 100 parts by weight, to obtain a
uniform solution. Next, the obtained uniform solution was misted by
a spray gun for painting, well stirred and sprayed to liquid
surface of n-hexane of 3000 parts by weight, to precipitate the
solute. The precipitated solid was filtered, and after fully washed
by n-hexane, vacuum dried at a temperature of 100.degree. C. for 24
hours, to obtain a true spherical epoxy modified nylon particle
A.
[0140] After the epoxy modified nylon particle A was press-molded
into a resin plate, in accordance with ASTM D 5045-96, when
G.sub.1c value was determined by compact tension method, it was
found to be 4420 J/m.sup.2.
<Thermoplastic Resin Fiber>
[0141] TR-55 short fiber obtained by the following production
method
[0142] A transparent polyamide (product name "Grilamid
(trademark)"--TR55, produced by EMSER WERKE AG) fiber extruded from
a spinneret equipped with one orifice was cut and a TR-55 short
fiber (fiber length 1 mm) of which cross-sectional shape is perfect
circle was obtained.
[0143] After the TR-55 was press-molded into a resin plate, when
G.sub.1c value by compact tension method was determined in
accordance with ASTM D 5045-96, it was found to be 4540
J/m.sup.2.
<Conductive Particle>
[0144] "Micropearl (trademark)" AU215 (produced by Sekisui Chemical
Co., Ltd., shape: true sphere, specific gravity: 1.8 g/cm.sup.3,
thickness of conductive layer: 110 nm, [volume of nucleus]/[volume
of conductive layer]: 22.8) which is a particle in which a
divinylbenzene polymer particle is plated by nickel and further
plated by gold thereon
[0145] "Micropearl (trademark)" AU225 (produced by Sekisui Chemical
Co., Ltd., shape: true sphere, specific gravity: 2.4 g/cm.sup.3,
thickness of conductive layer: 200 nm, [volume of nucleus]/[volume
of conductive layer]: 20.2) which is a particle in which a
divinylbenzene polymer particle is plated by nickel and further
plated by gold thereon
[0146] Glassy carbon particle "Bellpearl (trademark)" C-2000
(produced by Air Water Inc., shape: true sphere, specific gravity:
1.5 g/cm.sup.3)
[0147] Conductive particle B (shape: true sphere, specific gravity:
1.3 g/cm.sup.3) obtained by the following production method
[0148] Ferrous acetate (produced by Sigma-Aldrich Co.) 0.01 g and
cobalt acetate tetrahydrate (produced by Nacalai Tesque, Inc.) 0.21
g were added to ethanol (produced by Nacalai Tesque, Inc.) 40 ml,
and suspended for 10 minutes by an ultrasonic washer. To this
suspension, crystalline titanosilicate powder (produced by N.E.
Chemcat Corp. "Titanosilicate (trademark)") (TS-1) 2.0 g was added,
and treated by the ultrasonic washer for 10 minutes, and by
removing the methanol under a constant temperature of 60.degree.
C., a solid catalyst in which the above-mentioned metal acetate is
supported by TS-1 crystal surface was obtained.
[0149] The solid catalyst 1.0 g prepared in the above-mentioned was
put on a quartz boat in center portion of a quartz tube of inner
diameter 32 mm, and argon gas fed at 600 cc/min. The quartz tube
was placed in an electric furnace and its center temperature was
heated to a temperature of 800.degree. C. (heating time 30
minutes). When the temperature arrived at 800.degree. C., after a
high purity acetylene gas (produced by Koatsu Gas Kogyo Co., Ltd.)
was fed at 5 cc/min for 30 minutes, the feed of acetylene gas was
stopped and the temperature was cooled down to room temperature,
and a composition containing a hollow carbon nanofiber was taken
out. The composition containing the obtained hollow carbon
nanofiber 0.4 g was put in an electric furnace and heated to
400.degree. C. (heating time 40 minutes) under an atmospheric
environment. After keeping at a temperature of 400.degree. C. for
60 minutes, it was cooled down to room temperature. Furthermore,
after this composition containing the hollow carbon nanofiber was
thrown into 2.5 mol/L aqueous solution of sodium hydroxide 200 ml,
the solution was stirred for 5 hours while keeping at a temperature
of 80.degree. C. After that, it was suction-filtered by a membrane
filter of 10 .mu.m diameter, to carry out a solid/liquid
separation. After washing the obtained solid by distilled water 1
L, it was thrown into 5.1 mol/L concentration sulfuric acid 50 ml,
and stirred for 2 hours while keeping at a temperature of
80.degree. C. After that, the solid substance was separated by
using a filter paper (produced by Toyo Roshi Kaisha, Ltd.), Filter
Paper No. 2 of 125 mm. After the solid substance on the filter
paper was washed by distilled water 500 ml, it was dried at a
temperature of 60.degree. C., to obtain a hollow carbon nanofiber
at a recovery yield of 90%.
[0150] In ethanol 100 ml, the hollow carbon fiber obtained in the
above-mentioned 5 g and the epoxy modified nylon particle A
obtained in the item of the above-mentioned thermoplastic resin
particle 23 g were added, and stirred for 1 hour to obtain a
suspended liquid. The obtained suspended liquid was concentrated
under reduced pressure. Subsequently, by curing by heating to a
temperature of 200.degree. C. under argon atmosphere, a conductive
particle B 25 g was obtained. When a cross-section of this
conductive particle B was observed by a scanning electron
microscope, it was fount that a conductive layer was formed in a
thickness of 300 nm. [Volume of nucleus]/[volume of conductive
layer] was 7.0.
[0151] Conductive Particle C Obtained by the Following Production
Method
[0152] By using sputtering apparatus CFS-4ES-231 (produced by
Shibaura Mechatronics Corp.), the epoxy modified nylon particle A
10 g was put on a base plate and a sputtering was carried out in a
condition in which target was copper, gas component was argon, gas
pressure was 2.0.times.10.sup.-1 Pa, base plate temperature was
80.degree. C. and electric power was 500 W, to prepare a conductive
particle C of which thickness of conductive layer was 110 nm. It
was found that the shape of conductive particle was true sphere,
the specific gravity was 1.4 g/cm.sup.3 and the [volume of
nucleus]/[volume of conductive layer] was 18.6.
[0153] Conductive Particle D Obtained by the Following Production
Method
[0154] By using sputtering apparatus CFS-4ES-231(produced by
Shibaura Mechatronics Corp.), the epoxy modified nylon particle A
10 g was put on a base plate and a sputtering was carried out in a
condition in which target was titanium, gas component was argon,
gas pressure was 3.0.times.10.sup.-1 Pa, base plate temperature was
80.degree. C. and electric power was 500 W, to prepare a conductive
particle D of which thickness of conductive layer was 130 nm. It
was found that the shape of conductive particle was true sphere,
the specific gravity was 1.3 g/cm.sup.3 and the [volume of
nucleus]/[volume of conductive layer] was 15.7.
[0155] Conductive Particle E Obtained by the Following Production
Method
[0156] The epoxy modified nylon particle A 100 g was added to 1000
ml of electroless copper plating liquid MK-430 (produced by
Muromachi Chemical Inc.), and subsequently a plating treatment was
carried out at 50.degree. C. for 45 minutes, to prepare a
conductive particle E. It was found that the shape of conductive
particle E was true sphere, the specific gravity was 1.4
g/cm.sup.3, the thickness of conductive layer was 120 nm, and the
[volume of nucleus]/[volume of conductive layer] was 17.0.
[0157] Conductive Particle F Obtained by the Following Production
Method
[0158] The epoxy modified nylon particle A 100 g was added to 1000
ml of electroless nickel plating liquid NLT-PLA (produced by Nikko
Metal Plating Co., Ltd.), and subsequently a plating treatment was
carried out at 50.degree. C. for 60 minutes, to prepare a
conductive particle F. It was found that the shape of conductive
plate F was true sphere, the specific gravity was 1.4 g/cm.sup.3,
the thickness of conductive layer was 180 nm, and the [volume of
nucleus]/[volume of conductive layer] was 11.2.
[0159] Conductive Particle G Obtained by the Following Production
Method
[0160] Transparent polyamide (product name "Grilamid
(trademark)"--TR55, produced by EMSER WERKE AG) 60 parts by weight,
epoxy resin (product name "Epikote (trademark)" 828, produced by
Japan Epoxy Resins Co., Ltd.) 30 parts by weight and a hardener
(product name "Tohmide (trademark)" #296, produced by Fuji Kasei
Kogyo Co., Ltd.) 10 parts by weight were added to a mixed solvent
of chloroform 300 parts by weight and methanol 100 parts by weight,
to obtain a uniform solution. Next, the obtained uniform solution
was misted by a spray gun for painting, well stirred and sprayed to
liquid surface of n-hexane of 3000 parts by weight, to precipitate
the solute. The precipitated solid was separated by filtration, and
after fully washed by n-hexane, vacuum dried at a temperature of
100.degree. C. for 24 hours, to obtain a true spherical epoxy
modified nylon particle H.
[0161] The epoxy modified nylon particle H 100 g was added to 1000
ml electroless copper plating liquid MK-430 (produced by Muromachi
Chemical Inc.), subsequently a plating treatment was carried out at
50.degree. C. for 45 minutes, to prepare conductive particle G. It
was found that the shape of conductive plate G was true sphere, the
specific gravity was 2.2 g/cm.sup.3, the thickness of conductive
layer was 320 nm, and the [volume of nucleus]/[volume of conductive
layer] was 6.2.
[0162] After the epoxy modified nylon particle H was press-molded
into a resin plate, when G.sub.1c value by compact tension method
was determined in accordance with ASTM D 5045-96, it was found to
be 1210 J/m.sup.2.
[0163] Surface treated article I of "Micropearl (trademark)" AU215
obtained by the following production method
[0164] 3-(phenylamino)propyltrimethoxysilane 2 parts by weight was
sprayed, while being stirred by a mixer, to "Micropearl
(trademark)" AU215 100 parts by weight, subsequently heat treated
at 100.degree. C. for 12 hours, to obtain a surface treated article
I of "Micropearl (trademark)" AU215.
[0165] Surface treated article J of "Bellpearl (trademark)" C-2000
obtained by the following production method
[0166] "Bellpearl (trademark)" C-2000 100 g was added to 98 wt %
sulfuric acid solution 150 ml and 60 wt % nitric acid solution 50
ml, subsequently stirred at 120.degree. C. for 20 minutes and after
separated by a filter, fully washed with water, to obtain a surface
treated article J of "Bellpearl (trademark)" C-2000.
<Conductive Fiber>
[0167] "Torayca (trademark)" milled fiber MLD-30 (produced by Toray
Industries, Inc., cross-sectional shape: perfect circle, specific
gravity: 1.8 g/cm.sup.3, fiber length 30 .mu.m)
[0168] "Torayca (trademark)" chopped fiber T008-3 (produced by
Toray Industries, Inc., cross-sectional shape: perfect circle,
specific gravity: 1.8 g/cm.sup.3, fiber length 3 mm)
[0169] Conductive fiber A obtained by the following production
method
[0170] TR-55 short fiber (fiber length 1 mm) 100 g was added to
electroless copper plating liquid MK-430 (produced by Muromachi
Chemical Inc.) 1000 ml, subsequently a plating treatment was
carried out at 50.degree. C. for 45 minutes, to obtain a conductive
fiber A. It was found that cross-sectional shape of the conductive
fiber A was perfect circle, specific gravity was 1.6 g/cm.sup.3,
the thickness of conductive layer was 100 nm, the [volume of
core]/[volume of conductive layer] was 13.3.
[0171] Whereas, determination of average diameter of the
thermoplastic resin particle or fiber [C], the conductive particle
or fiber [D] and the conductive particle or fiber of which
thermoplastic resin nucleus or core is coated with a conductive
substance [E], containing ratio of the particles or fibers of the
above-mentioned [C], [D] and [E] present in the depth range of 20%
of prepreg thickness, compressive strength after impact and
conductivity of fiber reinforced composite material were carried
out in the following conditions. Except where it is explicitly
stated otherwise, the determinations were carried out in an
environment of a temperature of 23.degree. C. and a relative
humidity of 50%.
[0172] (1) Determinations of average diameters of particles [C],
[D] and [E] and volume ratio expressed by [volume of
nucleus]/[volume of conductive layer] of conductive particle coated
with conductive substance
[0173] As to the average diameter of the particle, for example, it
was determined as the average value (n=50) of particle diameters by
photographing particles at a magnification of 1000 times or more by
a microscope such as scanning electron microscope, selecting a
particle arbitrarily, and taking diameter of circumscribed circle
of the particle as the particle diameter. And, when a volume ratio
expressed by [volume of nucleus]/[volume of conductive layer] of
conductive particle coated with a conductive substance is
determined, at first, an average particle diameter of nucleus of
the conductive particle (average particle diameter) is measured by
the above-mentioned method, and after that, a cross-section of the
conductive particle coated with a conductive substance is
photographed by a scanning type microscope at a magnification of
10,000 times, the thickness of conductive layer was measured
(n=10), and its average value was calculated. Such a determination
was carried out for the above-mentioned arbitrarily selected
conductive particles (n=50). The average particle diameter of
nucleus of the conductive particle and 2 times of the average value
of thickness of the conductive layer were added together and taken
as the average diameter of conductive particle (average particle
diameter). And, based on the average diameter of nucleus of the
conductive particle (average particle diameter) and the average
diameter of conductive particle (average particle diameter), a
volume ratio expressed by [volume of nucleus]/[volume of conductive
layer] was calculated. Whereas, in case where a particle was
nonspherical, supposing circumscribed sphere of the nucleus, a
calculated value calculated by supposing a sphere coated on the
circumscribed sphere with the conductive layer measured by the
above-mentioned method was taken as a volume ratio.
[0174] Determination results of average particle diameter of each
particle of the thermoplastic resin particle and the conductive
particle were as follows.
<Thermoplastic Resin Particle>
[0175] Nylon 12 particle SP-10 (produced by Toray Industries, Inc.)
.cndot. .cndot. .cndot. 10.2 .mu.m [0176] Epoxy modified nylon
particle A .cndot. .cndot. .cndot. 12.5 .mu.m
<Conductive Particle>
[0176] [0177] "Micropearl" AU215 .cndot. .cndot. .cndot. 15.5 .mu.m
[0178] "Micropearl" AU225 .cndot. .cndot. .cndot. 25.0 .mu.m [0179]
"Bellpearl" C-2000 .cndot. .cndot. .cndot. 15.3 .mu.m [0180]
Conductive particle B .cndot. .cndot. .cndot. 13.8 .mu.m [0181]
Conductive particle C .cndot. .cndot. .cndot. 12.7 .mu.m [0182]
Conductive particle D .cndot. .cndot. .cndot. 12.9 .mu.m [0183]
Conductive particle E .cndot. .cndot. .cndot. 12.7 .mu.m [0184]
Conductive particle F .cndot. .cndot. .cndot. 13.0 .mu.m [0185]
Conductive particle G .cndot. .cndot. .cndot. 13.1 .mu.m [0186]
Surface treated article I of "Micropearl" AU215 .cndot. .cndot.
.cndot. 15.5 .mu.m [0187] Surface treated article J of
"Bellpearl"C-2000 .cndot. .cndot. .cndot. 15.3 .mu.m
[0188] (2) Determination of average fiber diameter the fiber of
[C], [D] and [E] and the volume ratio expressed by [volume of
core]/[volume of conductive layer] of the conductive fiber coated
with the conductive substance
[0189] As to the average diameter of the fiber (average fiber
diameter), for example, it was determined as the average value
(n=50) of fiber diameters by photographing fibers at a
magnification of 1000 times or more by a microscope such as
scanning electron microscope, selecting a fiber cross-section
arbitrarily, and taking diameter of circumscribed circle of the
fiber as the fiber diameter. And, when a volume ratio expressed by
the [volume of nucleus]/[volume of conductive layer] of conductive
fiber coated with a conductive substance is determined, at first,
an average fiber diameter of nucleus of the conductive fiber
(average fiber diameter) is measured by the above-mentioned method.
And after that, a cross-section of the conductive fiber coated with
a conductive substance is photographed by a scanning type
microscope at a magnification of 10,000 times, the thickness of
conductive layer was measured (n=10), and its average value was
calculated. Such a determination was carried out for the
above-mentioned arbitrarily selected conductive fibers (n=50). The
average fiber diameter of nucleus of the conductive fiber and 2
times of the average value of thickness of the conductive layer
were added together and taken as the average diameter of conductive
fiber (average fiber diameter). And, by using the average diameter
of nucleus of the conductive fiber and the average diameter of
conductive fiber, a volume ratio expressed by the [volume of
nucleus]/[volume of conductive layer] was calculated. Whereas,
determination result of average fiber diameter of each fiber of the
thermoplastic resin fiber and of the conductive fiber was as
follows.
<Thermoplastic Resin Fiber>
[0190] TR-55 short fiber .cndot. .cndot. .cndot. 5.4 .mu.m
<Conductive Fiber>
[0190] [0191] "Torayca" milled fiber MLD-30 .cndot. .cndot. .cndot.
7.2 .mu.m [0192] "Torayca" chopped fiber T008-3 .cndot. .cndot.
.cndot. 6.9 .mu.m [0193] Conductive fiber A .cndot. .cndot. .cndot.
5.6 .mu.m
[0194] (3) Containing ratio of the particle or fiber of [C], [D]
and [E] present in depth range of 20% of prepreg thickness
[0195] A prepreg was held and closely contacted between 2 smooth
surface polytetrafluoroethylene resin plates, and gelled and cured
by gradually raising temperature up to 150.degree. C. in 7 days to
prepare a platy cured prepreg product. After the curing, it was cut
in a direction perpendicular to the closely contacted surface, and
after the cross-section was polished, it was magnified 200 times or
more by an optical microscope and photographed such that the upper
and lower surfaces of the prepreg were into view. By the same
procedure, distance between the polytetrafluoroethylene resin plate
were measured at 5 positions in horizontal direction of the
cross-section photograph and their average value (n=10) was taken
as the thickness of prepreg.
[0196] On both sides of the photograph of this cured product of the
prepreg, 2 lines which are parallel to the surface of the prepreg
are drawn at positions of 20% depth from the surface of the cured
product of prepreg. Next, a total area of the above-mentioned
particle or fiber present between the prepreg surface and the
above-mentioned line, and a total area of the particle or fiber
present throughout the thickness of the prepreg are determined, and
calculate the containing ratio of the particle or fiber present in
20% depth range from the prepreg surface, with respect to the
prepreg thickness 100%. Here, the total area of the above-mentioned
particle or fiber is determined by clipping the particle or fiber
portion from the cross-section photograph and weighing its weight.
In case where a distinction of particles dispersed in the resin
after taking a photograph was difficult, the particle was
photographed after dyeing, appropriately.
[0197] (4) Determination of volume resistivity of conductive
particle or fiber
[0198] By using MCP-PD51 type powder resistance measurement system
produced by Dia Instruments Co., Ltd., a sample was set to a
cylindrical cell having a 4 probe electrode, and its thickness and
resistivity values were measured in condition where a pressure of
60 MPa was added to the sample, and from those values, volume
resistivity was calculated.
[0199] Whereas, volume resistivity of the conductive particles or
fibers were as follows.
<Conductive Particle>
[0200] "Micropearl" AU215 .cndot. .cndot. .cndot.
1.4.times.10.sup.-3 .OMEGA.cm [0201] "Micropearl" AU225 .cndot.
.cndot. .cndot. 1.6.times.10.sup.-3 .OMEGA.cm [0202] "Bellpearl"
C-2000 .cndot. .cndot. .cndot. 2.0.times.10.sup.-2 .OMEGA.cm [0203]
Conductive particle B .cndot. .cndot. .cndot. 5.0.times.10.sup.-2
.OMEGA.cm [0204] Conductive particle C .cndot. .cndot. .cndot.
3.5.times.10.sup.-2 .OMEGA.cm [0205] Conductive particle D .cndot.
.cndot. .cndot. 5.2.times.10.sup.-2 .OMEGA.cm [0206] Conductive
particle E .cndot. .cndot. .cndot. 4.5.times.10.sup.-4 .OMEGA.cm
[0207] Conductive particle F .cndot. .cndot. .cndot.
4.0.times.10.sup.-2 .OMEGA.cm [0208] Conductive particle G .cndot.
.cndot. .cndot. 6.1.times.10.sup.-4 .OMEGA.cm [0209] "Micropearl"
AU215surface treated article I .cndot. .cndot. .cndot.
1.4.times.10.sup.-3 .OMEGA.cm [0210] "Bellpearl" C-2000surface
treated article J 2.0.times.10.sup.-2 .OMEGA.cm
<Conductive Fiber>
[0210] [0211] "Torayca" milled fiber MLD-30 .cndot. .cndot. .cndot.
6.6.times.10.sup.-2 .OMEGA.cm [0212] "Torayca" chopped fiber T008-3
.cndot. .cndot. .cndot. 9.3.times.10.sup.-2 .OMEGA.cm [0213]
Conductive fiber A .cndot. .cndot. .cndot. 7.1.times.10.sup.-3
.OMEGA.cm
[0214] (5) Determination of compressive strength after impact of
fiber reinforced composite material
[0215] 24 plies of unidirectional prepreg were laid-up
quasi-isotropically in
[+45.degree./0.degree./-45.degree./90.degree.].sub.3s constitution,
and molded in an autoclave at a temperature of 180.degree. C. for 2
hours under a pressure of 0.59 MPa and at a heating speed of
1.5.degree. C./min priot to the 2 hour cure, to prepare 25 pieces
of laminate. From each of these laminates, a sample of length 150
mm.times.width 100 mm was cut out and, in accordance with SACMA SRM
2R-94, compressive strength after impact was determined by adding a
drop impact of 6.7 J/mm on its center portion.
[0216] (6) Determination of conductivity of fiber reinforced
composite material
[0217] 24 plies of unidirectional prepreg were laid-up
quasi-isotropically in
[+45.degree./0.degree./-45.degree./90.degree.].sub.3s constitution,
and molded in an autoclave at a temperature of 180.degree. C. for 2
hours under a pressure of 0.59 MPa and at a heating speed of
1.5.degree. C./min prior to the 2 hour cure, to prepare 25 pieces
of laminate. From each of these laminates, a sample of length 50
mm.times.width 50 mm was cut out and coated on both sides with a
conductive paste "Dotite" (trademark) D-550 (produced by Fujikura
Kasei Co., Ltd.), to prepare a sample. For these samples, by using
R6581 digital multimeter produced by Advantest Corp., resistivity
in laminate direction was measured by four probe method to obtain a
volume resistivity.
Example 1
[0218] By a kneader, 10 parts by weight of PES5003P was compounded
and dissolved in 50 parts by weight of "Epikote (trademark)" 825
and 50 parts by weight of ELM434, and then 19.98 parts by weight of
epoxy modified nylon particle A and 0.02 parts by weight of
"Micropearl (trademark)" AU215 were kneaded, and furthermore, 40
parts by weight of 4,4'-diaminodiphenyl sulfone which is a hardener
was kneaded, to prepare a thermosetting resin composition.
[0219] The prepared thermosetting resin composition was coated on a
release paper by using a knife coater, to prepare 2 sheets of resin
film of 52 g/m.sup.2. Next, on carbon fiber (T800S-24K-10E)
arranged into a unidirectional sheet, 2 sheets of the resin film
prepared in the above-mentioned were superposed on both sides of
the carbon fiber, and impregnated with the resin by heat and
pressure, to prepare a unidirectional prepreg of which carbon fiber
areal weight was 190 g/m.sup.2 and weight ratio of matrix resin was
35.4%.
[0220] By using the prepared unidirectional prepreg, containing
ratio of particle present in 20% depth range of prepreg thickness,
compressive strength after impact and conductivity of the fiber
reinforced composite material were determined. The obtained results
are shown in Table 1.
Examples 2 to 24 and Comparative Examples 1 to 7
[0221] Prepreg were prepared in the same way as Example 1 except
changing the kinds of carbon fiber, thermoplastic resin particle or
conductive particle or the compounding amounts as shown in Tables 1
to 4. By using the prepared unidirectional prepreg, containing
ratio of particle present in 20% depth range of prepreg thickness,
compressive strength after impact and conductivity of the fiber
reinforced composite material were determined.
Example 25
[0222] By a kneader, after 10 parts by weight of PES5003P was
compounded and dissolved in 50 parts by weight of "Epikote
(trademark)" 825 and 50 parts by weight of ELM434, and furthermore,
40 parts by weight of 4,4'-diaminodiphenyl sulfone which is a
hardener was kneaded, to prepare a thermosetting resin composition.
This matrix resin was taken as primary resin.
[0223] By a kneader, 10 parts by weight of PES5003P was compounded
and dissolved in 50 parts by weight of "Epikote (trademark)" 825
and 50 parts by weight of ELM434, and then, 62.5 parts by weight of
epoxy modified nylon particle A and 1.3 parts by weight of
"Micropearl (trademark)" AU215 were kneaded, and furthermore, 40
parts by weight of 4,4'-diaminodiphenyl sulfone which is a hardener
was kneaded, to prepare a thermosetting resin composition. This
matrix resin was taken as secondary resin.
[0224] The prepared primary resin was coated on a release paper by
using a knife coater, to prepare 2 sheets of resin film of 31.5
g/m.sup.2. Next, on carbon fiber (T800S-24K-10E) arranged into a
unidirectional sheet, 2 sheets of the resin film prepared in the
above-mentioned were superposed on both sides of the carbon fiber,
and impregnated with the resin by heat and pressure, to prepare a
unidirectional prepreg of which carbon fiber areal weight was 190
g/m.sup.2 and weight ratio of matrix resin was 24.9%.
[0225] Next, the prepared secondary resin was coated on a release
paper by using a knife coater, to prepare 2 sheets of resin film of
20.5 g/m.sup.2. Next, between these secondary resin films facing
each other, the above prepared primary impregnate prepreg was
inserted, and impregnated with the resin by heat and pressure in
the same way as the primary impregnate prepreg, to prepare a
secondary impregnate prepreg. This prepreg of which carbon fiber
areal weight was 190 g/m.sup.2 and weight ratio of matrix resin was
35.4% was prepared as a secondary impregnate prepreg. Matrix resin
composition of this secondary impregnate prepreg is shown in Table
4.
[0226] By using the prepared secondary impregnate prepreg,
containing ratio of particle present in 20% depth range of prepreg
thickness, compressive strength after impact and conductivity of
the fiber reinforced composite material were determined. The
obtained results are shown in Table 4.
Example 26
[0227] By a kneader, 10 parts by weight of PES5003P was compounded
and dissolved in 50 parts by weight of "Epikote (trademark)" 825
and 50 parts by weight of ELM434, and then 40 parts by weight of
4,4'-diaminodiphenyl sulfone which is a hardener was kneaded, to
prepare a thermosetting resin composition.
[0228] The prepared thermosetting resin composition was coated on a
release paper by using a knife coater, to prepare 2 sheets of resin
film of 45 g/m.sup.2. Next, on carbon fiber (T800S-24K-10E)
arranged into a unidirectional sheet, 2 sheets of the resin film
prepared in the above-mentioned were superposed on both sides of
the carbon fiber, and impregnated with the resin by heat and
pressure. Furthermore, on both sides thereof, TR-55 short fiber
which is a thermoplastic resin fiber and "Torayca" milled fiber
MLD-30 which is a conductive fiber were scattered. The scattered
amounts were 6.5 g/m.sup.2 and 0.5 g/m.sup.2, respectively. In this
way, a unidirectional prepreg of which carbon fiber areal weight
was 190 g/m.sup.2 and weight ratio of matrix resin was 35.4% was
prepared.
[0229] By using the prepared unidirectional prepreg, containing
ratio of particle present in 20% depth range of prepreg thickness,
compressive strength after impact and conductivity of the fiber
reinforced composite material were determined. The obtained results
are shown in Table 5.
Examples 27 to 29
[0230] Prepregs were prepared in the same way as Example 25 except
changing the kinds of conductive particle or fiber as shown in
Tables 5 and changing the scattered amount of the thermoplastic
resin particle or fiber to 6.5 g/m.sup.2, and the scattered amount
of the conductive particle or fiber to 0.5 g/m.sup.2. By using the
prepared unidirectional prepreg, containing ratio of particle
present in 20% depth range of prepreg thickness, compressive
strength after impact and conductivity of the fiber reinforced
composite material were determined.
Example 30, Comparative Examples 8 and 9
[0231] Prepregs were prepared in the same way as Example 25 except
changing the kinds of thermoplastic resin fiber or conductive fiber
as shown in Tables 5 and changing the scattered amount of those to
7.0 g/m.sup.2. By using the prepared unidirectional prepreg,
containing ratio of the above-mentioned particle or fiber in 20%
depth range of prepreg thickness, compressive strength after impact
and conductivity of the fiber reinforced composite material were
determined.
[0232] The obtained results are summarized in Tables 1 to 5.
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 Carbon fiber T800S T800S
T800S T800S T800S T800S Thermosetting Thermosetting resin resin
Composition Epikote 825 50 50 50 50 50 50 ELM434 50 50 50 50 50 50
4,4'-diaminodiphenyl sulfone 40 40 40 40 40 40 PES5003P 10 10 10 10
10 10 Thermoplastic resin particle SP-10 0 0 0 0 0 0 Epoxy modified
nylon particle A 19.98 19.8 19.6 18 15 10 Conductive particle
"Micropearl" AU215 0.02 0.2 0.4 2 5 10 "Micropearl" AU225 0 0 0 0 0
0 "Bellpearl" C-2000 0 0 0 0 0 0 Conductive particle B 0 0 0 0 0 0
Conductive particle C 0 0 0 0 0 0 Conductive particle D 0 0 0 0 0 0
Conductive particle E 0 0 0 0 0 0 Conductive particle F 0 0 0 0 0 0
Conductive particle G 0 0 0 0 0 0 Surface treated article I of
"Micropearl" AU215 0 0 0 0 0 0 Surface treated article J of
"Bellpearl" C-2000 0 0 0 0 0 0 Compounding amount of [C] (pts by
wt)/ 999.0 99.0 49.0 9.0 3.0 1.0 compounding amount of [D] (pts by
wt) Characteristics of prepreg Containing ratio of particle present
in 20% 97 98 97 96 97 100 depth range Characteristics of
Compressive strength after impact (MPa) 290 288 289 287 280 265
composite material Volume resistivity (.OMEGA.cm) 1.1 .times.
10.sup.5 1.5 .times. 10.sup.4 5.0 .times. 10.sup.3 4.2 .times.
10.sup.3 4.0 .times. 10.sup.3 4.2 .times. 10.sup.3
TABLE-US-00002 TABLE 2 Example Comparative example 7 1 2 3 4 Carbon
fiber T700S T800S T800S T800S T800S Thermosetting Thermosetting
resin resin composition Epikote 825 50 50 50 50 50 ELM434 50 50 50
50 50 4,4'-diaminodiphenyl sulfone 40 40 40 40 40 PES5003P 10 10 10
10 10 Thermoplastic resin particle SP-10 0 0 0 0 0 Epoxy modified
nylon particle A 19.6 20 0 19.99 8 Conductive particle
"Micropearl"AU215 0.4 0 20 0.01 12 "Micropearl"AU225 0 0 0 0 0
"Bellpearl"C-2000 0 0 0 0 0 Conductive particle B 0 0 0 0 0
Conductive particle C 0 0 0 0 0 Conductive particle D 0 0 0 0 0
Conductive particle E 0 0 0 0 0 Conductive particle F 0 0 0 0 0
Conductive particle G 0 0 0 0 0 Surface treated article I of
"Micropearl" AU215 0 0 0 0 0 Surface treated article J of
"Bellpearl" C-2000 0 0 0 0 0 Compounding amount of [C] (pts by wt)/
9.0 -- -- 1999.0 0.7 compounding amount of [D] (pts by wt)
Characteristics of prepreg Containing ratio of particle present in
20% 97 97 97 97 96 depth range Characteristics of Compressive
strength after impact (MPa) 287 289 235 289 219 composite material
Volume resistivity (.OMEGA.cm) 5.7 .times. 10.sup.3 1.5 .times.
10.sup.6 3.8 .times. 10.sup.3 1.1 .times. 10.sup.6 4.2 .times.
10.sup.3
TABLE-US-00003 TABLE 3 Example Comparative example 8 9 10 11 12 13
5 6 7 Carbon fiber T800S T800S T800S T800S T800S T800S T800S T800S
T800S Thermo- Thermosetting resin setting Epikote 825 50 50 50 50
50 50 50 50 50 resin ELM434 50 50 50 50 50 50 50 50 50 composition
4,4'-diaminodiphenyl 40 40 40 40 40 40 40 40 40 sulfone PES5003P 10
10 10 10 10 10 10 10 10 Thermoplastic resin particle SP-10 19.98
19.8 19.6 18 15 10 20 19.99 8 Epoxy modified nylon 0 0 0 0 0 0 0 0
0 particle A Conductive particle "Micropearl" AU215 0.02 0.2 0.4 2
5 10 0 0.01 12 "Micropearl" AU225 0 0 0 0 0 0 0 0 0 "Bellpearl"
C-2000 0 0 0 0 0 0 0 0 0 Conductive particle B 0 0 0 0 0 0 0 0 0
Conductive particle C 0 0 0 0 0 0 0 0 0 Conductive particle D 0 0 0
0 0 0 0 0 0 Conductive particle E 0 0 0 0 0 0 0 0 0 Conductive
particle F 0 0 0 0 0 0 0 0 0 Conductive particle G 0 0 0 0 0 0 0 0
0 Surface treated article I of 0 0 0 0 0 0 0 0 0 "Micropearl" AU215
Surface treated article J of 0 0 0 0 0 0 0 0 0 "Bellpearl" C-2000
Compounding amount of 999.0 99.0 49.0 9.0 3.0 1.0 -- 1999.0 0.7 [C]
(pts by wt)/ compounding amount of [D] (pts by wt) Charac-
Containing ratio of particle 96 97 97 98 96 97 97 98 97 teristics
of present in 20% depth range Prepreg Charac- Compressive strength
345 343 343 335 328 298 343 344 258 teristics of after impact (MPa)
Composite Volume resistivity (.OMEGA.cm) 9.8 .times. 10.sup.4 1.3
.times. 10.sup.4 4.8 .times. 10.sup.3 4.0 .times. 10.sup.3 3.9
.times. 10.sup.3 3.8 .times. 10.sup.3 1.4 .times. 10.sup.6 1.0
.times. 10.sup.6 3.8 .times. 10.sup.3 material
TABLE-US-00004 TABLE 4 Example 14 15 16 17 18 19 Carbon fiber T800S
T800S T800S T800S T800S T800S Thermosetting Thermosetting resin
resin composition Epikote 825 50 50 50 50 50 50 ELM434 50 50 50 50
50 50 4,4'-diaminodiphenyl sulfone 40 40 40 40 40 40 PES5003P 10 10
10 10 10 10 Thermoplastic resin particle SP-10 0 0 0 0 0 0 Epoxy
modified nylon particle A 19.6 19.6 19.6 19.6 19.6 19.6 Conductive
particle "Micropearl"AU215 0 0 0 0 0 0 "Micropearl"AU225 0 0 0 0 0
0 "Bellpearl"C-2000 0.4 0 0 0 0 0 Conductive particle B 0 0.4 0 0 0
0 Conductive particle C 0 0 0.4 0 0 0 Conductive particle D 0 0 0
0.4 0 0 Conductive particle E 0 0 0 0 0.4 0 Conductive particle F 0
0 0 0 0 0.4 Conductive particle G 0 0 0 0 0 0 Surface treated
article I of "Micropearl"AU215 0 0 0 0 0 0 Surface treated article
J of "Bellpearl"C-2000 0 0 0 0 0 0 Compounding amount of [C] (pts
by wt)/ 49.0 49.0 49.0 49.0 49.0 49.0 compounding amount of [D]
(pts by wt) Characteristics of Containing ratio of particle present
in 20% 96 97 98 97 98 98 prepreg depth range Characteristics of
Compressive strength after impact (MPa) 285 290 301 297 303 291
composite Volume resistivity (.OMEGA.cm) 2.8 .times. 10.sup.3 3.7
.times. 10.sup.4 1.1 .times. 10.sup.4 3.5 .times. 10.sup.4 4.8
.times. 10.sup.3 2.2 .times. 10.sup.4 material Example 20 21 22 23
24 25 Carbon fiber T800S T800S T800S T800S T800S T800S
Thermosetting Thermosetting resin resin composition Epikote 825 50
50 50 50 50 50 ELM434 50 50 50 50 50 50 4,4'-diaminodiphenyl
sulfone 40 40 40 40 40 40 PES5003P 10 10 10 10 10 10 Thermoplastic
resin particle SP-10 0 0 0 0 0 0 Epoxy modified nylon particle A
19.6 19.6 0 0 19.6 19.6 Conductive particle "Micropearl"AU215 0 0 0
0 0 0.4 "Micropearl"AU225 0 0 0 0 0.4 0 "Bellpearl"C-2000 0 0 0 0 0
0 Conductive particle B 0 0 0 0 0 0 Conductive particle C 0 0 0 0 0
0 Conductive particle D 0 0 0 0 0 0 Conductive particle E 0 0 20 0
0 0 Conductive particle F 0 0 0 0 0 0 Conductive particle G 0 0 0
20 0 0 Surface treated article I of "Micropearl"AU215 0.4 0 0 0 0 0
Surface treated article J of "Bellpearl"C-2000 0 0.4 0 0 0 0
Compounding amount of [C] (pts by wt)/ 49.0 49.0 -- -- 49.0 49.0
compounding amount of [D] (pts by wt) Characteristics of Containing
ratio of particle present in 20% 97 97 97 97 98 99 prepreg depth
range Characteristics of Compressive strength after impact (MPa)
299 296 294 267 290 308 composite Volume resistivity (.OMEGA.cm)
5.3 .times. 10.sup.3 2.6 .times. 10.sup.3 2.7 .times. 10.sup.3 3.3
.times. 10.sup.3 2.1 .times. 10.sup.3 2.0 .times. 10.sup.3
material
TABLE-US-00005 TABLE 5 Example Comparative example 26 27 29 30 8 9
Carbon fiber T800S T800S T800S T800S T800S T800S T800S
Thermosetting Thermosetting resin resin composition Epikote 825 50
50 50 50 50 50 50 ELM434 50 50 50 50 50 50 50 4,4'-diaminodiphenyl
sulfone 40 40 40 40 40 40 40 PES5003P 10 10 10 10 10 10 10
Thermoplastic resin fiber TR-55 TR-55 -- TR-55 -- TR-55 -- short
fiber short fiber short fiber short fiber Thermoplastic resin
particle -- -- SP-10 -- -- -- -- Conductive fiber MLD-30 T008-3
MLD-30 -- Conductive -- MLD-30 fiber A Conductive particle -- -- --
Conductive -- -- -- particle E Compounding amount of [C] (pts by
wt)/ 13.0 13.0 13.0 13.0 -- -- -- compounding amount of [D] (pts by
wt) Characteristics of Containing ratio of particle present in 97
97 98 96 96 97 98 prepreg 20% depth range Characteristics of
Compressive strength after impact (MPa) 271 269 283 273 268 273 207
Composite Volume resistivity value (.OMEGA.cm) 4.1 .times. 10.sup.4
4.7 .times. 10.sup.4 8.3 .times. 10.sup.3 3.9 .times. 10.sup.3 9.1
.times. 10.sup.3 1.8 .times. 10.sup.6 5.3 .times. 10.sup.3
material
[0233] By comparison between Examples 1 to band Comparative
examples 1 to 4, it is found that the carbon fiber reinforced
composite material of the present invention peculiarly realizes a
high compressive strength after impact and a low volume
resistivity, and satisfies a high level impact resistance and
conductivity together. And, a relation between these results and
the scope of claim of the present invention is summarized in FIG.
2. In FIG. 2, the weight ratio expressed by the [compounding amount
of thermoplastic resin particle (parts by weight)]/[ compounding
amount of conductive particle (parts by weight)] is shown in the
horizontal line and, ".largecircle." denotes the value of
compressive strength after impact shown in the left vertical line
and ".tangle-solidup." denotes the volume resistivity shown in the
right vertical line. Usually, when the weight ratio expressed by
the [compounding amount of thermoplastic resin particle (parts by
weight)]/[compounding amount of conductive particle (parts by
weight)] is large, an impact resistance is excellent, but a volume
resistivity also becomes large, and when the weight ratio expressed
by the [compounding amount of thermoplastic resin particle (parts
by weight)]/[compounding amount of conductive particle (parts by
weight)] is small, a volume resistivity is small, but an impact
resistance is poor. It is found that, in the present invention, the
scope of Claim 1 is a scope where a low volume resistivity and a
high compressive strength after impact can be achieved, and it is
the range where conductivity and impact resistance can be
compatible.
[0234] As to these results, the same can be said by comparison
between Examples 7 to 30 and Comparative examples 5 to 9.
Furthermore, by comparison between Example 3 and Example 7, it is
found that Example 3 in which T800S-24K-10E which is a carbon fiber
having a tensile modulus of 290 GPa was used is more excellent
compared to Example 7 in which T700S-24K-50C which is a carbon
fiber having a tensile modulus of 230 GPa was used. And, as shown
in Examples 14 to 30, in the present invention, various combination
of thermoplastic resin particle or fiber and conductive particle or
fiber can be used.
[0235] It is found that, compared to Examples 3 and 14, surface
treated articles of conductive particle as shown in Examples 20 and
21 can realize a strong adhesion with the thermosetting resin, and
has achieved a higher compressive strength after impact.
[0236] Furthermore, in Examples 22, 23, without using a
thermoplastic resin particle, by using the conductive particle E or
G only of which thermoplastic resin nucleus is coated with a
conductive substance, or in Example 30, too, without using a
thermoplastic resin fiber, by using the conductive fiber A only of
which core of thermoplastic resin is coated with the conductive
substance, a low volume resistivity and a high compressive strength
after impact can be achieved, and it is found that conductivity and
impact resistance can be compatible. And, when the conductive
particles E and G of Examples 22 and 23 are compared, it is found
that the conductive particle E having a higher G.sub.1c has
achieved a higher compressive strength after impact.
[0237] In Example 25 in which the secondary impregnate prepreg was
used, the containing ratio of particle present in 20% depth is
higher than Example 3, and it is found that a higher conductivity
and impact resistance can be obtained.
INDUSTRIAL APPLICABILITY
[0238] The prepreg and the carbon fiber reinforced composite
material of the present invention has an excellent impact
resistance and conductivity together, and can be widely applied to
an aircraft structural member, a blade of windmill, an automotive
outer panel and computer applications such as an IC tray or a
kyotai (housing) of notebook computer, etc., and it is useful.
* * * * *