U.S. patent application number 13/917969 was filed with the patent office on 2013-10-24 for resin composition for fiber-reinforced composite material, cured product thereof, fiber-reinforced composite material, molding of fiber-reinforced resin, and process for production thereof.
The applicant listed for this patent is DIC Corporation. Invention is credited to Atsuko Kobayashi, Ichirou Ogura.
Application Number | 20130281576 13/917969 |
Document ID | / |
Family ID | 43606971 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130281576 |
Kind Code |
A1 |
Kobayashi; Atsuko ; et
al. |
October 24, 2013 |
RESIN COMPOSITION FOR FIBER-REINFORCED COMPOSITE MATERIAL, CURED
PRODUCT THEREOF, FIBER-REINFORCED COMPOSITE MATERIAL, MOLDING OF
FIBER-REINFORCED RESIN, AND PROCESS FOR PRODUCTION THEREOF
Abstract
The present invention provides a resin composition for a
fiber-reinforced composite material, which has excellent fluidity
and impregnation into a fiber base material and which produces a
cured product having excellent heat resistance. A resin composition
for a fiber-reinforced composite material contains, as essential
components, a poly(glycidyloxyaryl) compound (A), a polymerizable
monomer (B) which is an unsaturated carboxylic acid or an anhydride
thereof and has a molecular weight of 160 or less, an aromatic
vinyl compound or a (meth)acrylate (C), and a radical
polymerization initiator (D), wherein an equivalent ratio
[glycidyloxy group/acid group] of a glycidyloxy group in the
component (A) to an acid group in the component (B) is 1/1 to
1/0.48, and a molar ratio [(B)/(C)] of the component (B) to the
component (C) is in the range of 1/0.55 to 1/2.
Inventors: |
Kobayashi; Atsuko;
(Ichihara-shi, JP) ; Ogura; Ichirou;
(Ichihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIC Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
43606971 |
Appl. No.: |
13/917969 |
Filed: |
June 14, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13389692 |
Jun 19, 2012 |
8487052 |
|
|
PCT/JP2010/063369 |
Aug 6, 2010 |
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13917969 |
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Current U.S.
Class: |
523/468 ;
264/257; 264/571 |
Current CPC
Class: |
C08L 63/10 20130101;
C08J 2363/02 20130101; B29C 70/48 20130101; B29C 2945/7605
20130101; B29K 2023/06 20130101; Y10T 428/31511 20150401; B29K
2995/0088 20130101; C08G 59/1466 20130101; C08G 59/08 20130101;
C08L 63/00 20130101; C08F 283/10 20130101; C08L 33/02 20130101;
C08J 5/24 20130101; C08L 2205/05 20130101; C08L 63/00 20130101;
C08L 25/04 20130101 |
Class at
Publication: |
523/468 ;
264/257; 264/571 |
International
Class: |
C08L 63/10 20060101
C08L063/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2009 |
JP |
2009-188469 |
Claims
1-8. (canceled)
9. A fiber-reinforced plastic molding material comprising, as
essential components, reinforcing fibers and a resin composition
for a fiber-reinforced plastic molding, wherein the composition
comprises, as essential components, a poly(glycidyloxyaryl)
compound (A) selected from the group consisting of bisphenol epoxy
resins and novolac epoxy resins, a polymerizable monomer (B)
selected from the group consisting of acrylic acid, methacrylic
acid and anhydrides thereof, an aromatic vinyl compound or a
(meth)acrylate (C), and a radical polymerization initiator (D),
wherein an equivalent ratio [glycidyloxy group/acid group] of a
glycidyloxy group in the component (A) to an acid group in the
component (B) is 1/1 to 1/0.48, and a molar ratio [(B)/(C)] of the
component (B) to the component (C) is in the range of 1/0.55 to
1/2.
10. The fiber-reinforced plastic molding material according to
claim 9, wherein the volume content of the reinforcing fibers is in
the range of 40 to 85%.
11. A fiber-reinforced plastic molding comprising, as essential
components, reinforcing fibers and a cured product of the resin
composition for a fiber-reinforced plastic molding according to
claim 9.
12. The fiber-reinforced plastic molding according to claim 11,
wherein the volume content of the reinforcing fibers is in the
range of 40 to 85%.
13. A method for producing a fiber-reinforced plastic molding, the
method comprising impregnating, by injection, a base material,
which is composed of reinforcing fibers and disposed in a mold,
with the resin composition for a fiber-reinforced plastic molding
according to claim 9, and then curing the resin composition by an
in-situ polymerization reaction.
14. The method for producing a fiber-reinforced plastic molding
according to claim 13, wherein the method uses a vacuum RTM molding
method including reducing the pressure in a cavity of a mold in
which a base material composed of reinforcing fibers is disposed,
and impregnating the base material with the resin composition for a
fiber-reinforced plastic molding by injecting into the cavity using
a differential pressure between the reduced pressure in the cavity
and outside pressure.
15. (canceled)
16. A fiber-reinforced plastic molding material comprising, as
essential components, reinforcing fibers and a resin composition
for a fiber-reinforced plastic molding, wherein the composition
comprising, as essential components, bisphenol epoxy resins as a
poly (glycidyloxyaryl) compound (A), a polymerizable monomer (B)
selected from the group consisting of acrylic acid, methacrylic
acid and anhydrides thereof, an aromatic vinyl compound or a (meth)
acrylate (C), and a radical polymerization initiator (D), wherein
an equivalent ratio [glycidyloxy group/acid group] of a glycidyloxy
group in the component (A) to an acid group in the component (B) is
1/1 to 1/0.48, and a molar ratio [(B)/(C)] of the component (B) to
the component (C) is in the range of 1/0.55 to 1/2.
17. The fiber-reinforced plastic molding material according to
claim 16, wherein the volume content of the reinforcing fibers is
in the range of 40 to 85%.
18. A fiber-reinforced plastic molding comprising, as essential
components, reinforcing fibers and a cured product of the resin
composition for a fiber-reinforced plastic molding according to
claim 16.
19. A method for producing a fiber-reinforced plastic molding, the
method comprising impregnating, by injection, a base material,
which is composed of reinforcing fibers and disposed in a mold,
with the resin composition for a fiber-reinforced plastic molding
according to claim 16, and then curing the resin composition by an
in-situ polymerization reaction.
20. A method for producing a fiber-reinforced plastic molding
comprising impregnating, by injection, a base material, which is
composed of reinforcing fibers and disposed in a mold, with the
resin composition for a fiber-reinforced plastic molding of claim
16, and then curing the resin composition by an in-situ
polymerization reaction, wherein the method uses a vacuum RTM
molding method including reducing the pressure in a cavity of a
mold in which a base material composed of reinforcing fibers is
disposed, and impregnating the base material with the resin
composition for a fiber-reinforced plastic molding by injecting
into the cavity using a differential pressure between the reduced
pressure in the cavity and outside pressure.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fiber-reinforced
composite material suitable for aircraft members, spacecraft
members, automobile members, and the like because they exhibit
excellent fluidity and produce cured products having excellent heat
resistance and mechanical strength, a method for producing the
materials, and matrix resin materials of the fiber-reinforce
composite materials.
BACKGROUND ART
[0002] In view of excellent physical properties such as high heat
resistance, moisture proof, dimensional stability, etc., epoxy
resin compositions each containing an epoxy resin and a curing
agent therefor as essential components are widely used for
electronic components such as a semiconductor encapsulate, a
printed circuit board, a build-up substrate, and resist ink, a
conductive adhesive such as a conductive paste and other adhesives,
a liquid sealing material such as an underfill, a liquid crystal
sealing material, a cover lay for a flexible substrate, an adhesive
film for build up, a coating material, a photoresist material, a
color developing material, a fiber-reinforced composite material,
and the like.
[0003] Among these, particularly, fiber-reinforced resin moldings
produced by impregnating reinforcing fibers with an epoxy resin and
a curing agent as matrix components and then curing the resin are
highly required in general industrial fields such as automobile
industry and aerospace industry from the viewpoint of various
excellent performances such as high heat resistance, strength, low
curing contraction percentage, chemical resistance, high elastic
modulus, etc. in addition to properties such as light weight and
high strength.
[0004] However, epoxy resins are generally high-viscosity fluids or
solids at normal temperature, and thus in a step of impregnating
fiber reinforcements with the resins, it is necessary to heat resin
components in order to secure a practical level of fluidity of the
epoxy resins, thereby causing the problem of accelerating curing of
the epoxy resins by heating and rather bringing about higher
viscosity and impregnation failure. In particular, in a molding
technique by a resin transfer molding (RTM) method which has
recently been being popularized in the field of carbon
fiber-reinforced thermosetting plastics (CFRP) because of the
overwhelming cycle time and low equipment cost, low viscosity and
high fluidity are important problems for thermosetting resin
materials from the viewpoint of higher-cycle molding.
[0005] As means for improving fluidity of an epoxy resin material
for a CFRP matrix, there has been known a technique of preparing a
liquid composition by mixing an aliphatic epoxy compound such as
3,4-epoxycyclohexymethyl-3,4-epoxycyclohexane carboxylate or
polyglycidylamine such as
N,N,N',N'-tetraglycidyldiaminodiphenylmethane with acrylic acid,
styrene, and a radical polymerization initiator, impregnating a
carbon fiber substrate with the liquid composition, and then
effecting reaction between epoxy groups and acrylic acid and
radical polymerization by heating, producing a molded product
(refer to PTL 1 below).
[0006] However, when the aliphatic epoxy compound is used for the
liquid composition described in PTL 1, a cured product become
brittle and thus does not exhibit satisfactory strength, while when
the polyglycidylamine is used, heat resistance is not
satisfactorily exhibited. In addition, the epoxy resin is a special
epoxy resin having excellent curability with acrylic acid and is
difficult to produce on an industrial scale and is lack of
practicability.
[0007] On the other hand, there has been known a technique for
improving CFRP productivity by the RTM method, in which as an epoxy
resin material suitable for the RTM method for CFRP application, a
bisphenol F epoxy resin having an epoxy equivalent of, for example,
200 g/eq. or less, is used as a base resin, and aromatic polyamine,
which is liquid at room temperature, and a complex of a Lewis acid
and a base are used as curing agent components, thereby improving
fluidity of a thermosetting resin component and further improving
low-temperature curability (refer to PTL 2).
[0008] However, in the thermosetting resin material containing the
bisphenol F epoxy resin having an epoxy equivalent of 200 g/eq. or
less, the aromatic polyamine which is liquid at room temperature,
and the complex of a Lewis acid and a base, the viscosity of the
epoxy resin is decreased, but the viscosity of the whole
composition is still high, thereby necessitating heating at about
100.degree. C. for resin injection in, for example, RTM molding.
Therefore, the possibility of thickening by curing reaction
remains, the running cost is increased in terms of energy, and the
molding cycle time cannot be sufficiently shortened. In addition, a
cured product has unsatisfactory heat resistance and has difficulty
in applying to the automobile industry and the aerospace
industry.
CITATION LIST
Patent Literature
[0009] PTL 1: Japanese Unexamined Patent Application Publication
No. 55-110115 [0010] PTL 2: Japanese Unexamined Patent Application
Publication No. 2006-265434
SUMMARY OF INVENTION
Technical Problem
[0011] Accordingly, a problem to be solved by the invention is to
provide a resin composition for a fiber-reinforced composite
material which has excellent fluidity and the excellent
impregnation in a fiber base material and which imparts excellent
heat resistance and strength to a cured product, a cured product
thereof, a fiber-reinforced composite material which imparts
excellent heat resistance to a molding, a fiber-reinforced resin
molding having excellent heat resistance and strength, and a method
for producing the fiber-reinforced resin molding with high
productivity.
Solution to Problem
[0012] As a result of intensive research for solving the problem,
the inventors found that as a thermosetting resin component to be
impregnated in a fiber reinforcement and cured, a composition
containing a poly(glycidyloxyaryl) compound (A), a polymerizable
monomer (B) which is an unsaturated carboxylic acid or an anhydride
thereof and has a molecular weight of 160 or less, an aromatic
vinyl compound or a (meth)acrylate (C), and a radical
polymerization initiator (D) is used, in which an equivalent ratio
[glycidyloxy group/acid group] of a glycidyloxy group in the
component (A) to an acid group in the component (B) is 1/1 to
1/0.48, and a molar ratio [(B)/(C)] of the component (B) to the
component (C) is in the range of 1/0.55 to 1/2, and the composition
is continuously or simultaneously cured by so-called in-situ
polymerization reaction, to react the acid group in the acid
group-containing polymerizable monomer (B) with the glycidyloxy
group in the poly(glycidyloxyaryl) compound (A) and to polymerize a
radical polymerizable group caused by the acid group-containing
polymerizable monomer (B), so that excellent fluidity is exhibited
before curing even in a low-temperature region, for example, normal
temperature of 25.degree. C., excellent heat resistance is
exhibited after curing, and strength comparable to conventional
epoxy resin cured products is exhibited, leading to the completion
of the present invention.
[0013] That is, the present invention relates to a resin
composition for a fiber-reinforced composite material, the resin
composition containing, as essential components, a
poly(glycidyloxyaryl) compound (A), a polymerizable monomer (B)
which is an unsaturated carboxylic acid or an anhydride thereof and
has a molecular weight of 160 or less, an aromatic vinyl compound
or a (meth)acrylate (C), and a radical polymerization initiator
(D), in which an equivalent ratio [glycidyloxy group/acid group] of
a glycidyloxy group in the component (A) to an acid group in the
component (B) is 1/1 to 1/0.48, and a molar ratio [(B)/(C)] of the
component (B) to the component (C) is in the range of 1/0.55 to
1/2.
[0014] The present invention further relates to a cured product
produced by in-situ polymerization reaction of the resin
composition for a fiber-reinforced composite material.
[0015] The present invention further relates to a fiber-reinforced
composite material containing reinforcing fibers and the resin
composition for a fiber-reinforced composite material and as
essential components.
[0016] The present invention further relates to a fiber-reinforced
resin molding containing reinforcing fibers and a cured product of
the resin composition for a fiber-reinforced composite material as
essential components.
[0017] The present invention further relates to a method for
producing a fiber-reinforced resin molding, the method including
impregnating, by injection, a base material, which is composed of
reinforcing fibers and disposed in a mold, with the resin
composition for a fiber-reinforced composite material, and then
curing the resin composition by an in-situ polymerization
reaction.
Advantageous Effects of Invention
[0018] According to the present invention, it is possible to
provide a resin composition for a fiber-reinforced composite
material which has excellent fluidity and the excellent
impregnation in a fiber base material and which imparts excellent
heat resistance and high strength to a cured product, a cured
product thereof, a fiber-reinforced composite material which
imparts excellent heat resistance and strength to a molding, a
fiber-reinforced resin molding having excellent heat resistance and
strength, and a method for producing the fiber-reinforced resin
molding with good productivity.
[0019] Therefore, by using the resin composition for a
fiber-reinforced composite material of the present invention, a
higher cycle rate can be achieved in a method for producing CFRP
and glass fiber-reinforced thermosetting plastics (GFRP), and a
fiber-reinforced resin molding having excellent heat resistance and
strength can be produced.
DESCRIPTION OF EMBODIMENTS
[0020] The present invention is described in detail below.
[0021] A resin composition for a fiber-reinforced composite
material of the present invention contains, as thermosetting resin
components, a poly(glycidyloxyaryl) compound (A), a polymerizable
monomer (B) which is an unsaturated carboxylic acid or an anhydride
thereof and has a molecular weight of 160 or less (hereinafter
abbreviated as an "acid group-containing polymerizable monomer
(B)"), an aromatic vinyl compound or a (meth)acrylate (C), and a
radical polymerization initiator (D) at a predetermined ratio. A
fiber reinforcing material is impregnated with the composition and
then reacted at a time, i.e., both a reaction between a glycidyloxy
group and an acid group and a polymerization reaction of a radical
polymerizable group are simultaneously or continuously performed
without being particularly distinguished as reaction steps.
Therefore, while fluidity before curing is significantly increased,
the heat resistance and mechanical strength of a cured product can
be significantly improved by during through the in-situ
polymerization reaction. Further explaining this point in detail,
in the present invention, the viscosity of vanish which is the
resin composition for a fiber-reinforced composite material can be
significantly decreased by adapting curing system of the in-situ
polymerization reaction, and thus, for example, a higher-cycle RTM
method can be realized. On the other hand, the cured product
obtained by the in-situ polymerization reaction can be further
increased in heat resistance and improved in mechanical strength as
compared with a case where the poly(glycidyloxyaryl) compound (A)
and the acid group-containing polymerizable monomer (B) are
previously reacted to form a vinyl ester, followed by radical
polymerization. Consequently, excellent fluidity is exhibited
before curing, and unconventional heat resistance and mechanical
strength are exhibited after curing.
[0022] The present invention is characterized by realizing a curing
system by the in-situ polymerization reaction using, as an epoxy
resin component, commonly used poly(glycidyloxyaryl) compound such
as a bisphenol epoxy resin or novolac epoxy resin. In particular,
in producing a large molding, it is difficult to industrially use a
large amount of a special epoxy resin such as an aliphatic epoxy
compound. Therefore, it is a significant point that as in the
present invention, in spite of using of a commonly used epoxy
resin, high fluidity and high strength and high heat resistance
after curing were given.
[0023] The poly(glycidyloxyaryl) compound (A) used herein is,
specifically, an epoxy resin having, in its molecular structure, a
glycidyloxyaryl structure produced by glycidyl-etherifying a
polyhydric phenol compound or a phenol resin. Examples thereof
include bisphenol epoxy resins such as bisphenol A epoxy resins,
bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol AD
epoxy resins, and the like; novolac epoxy resins such as
ortho-cresol novolac epoxy resins, phenol novolac epoxy resins,
naphthol novolac epoxy resins, bisphenol A novolac epoxy resins,
brominated phenol novolac epoxy resins, alkylphenol novolac epoxy
resins, bisphenol S novolac epoxy resins, alkoxy group-containing
novolac epoxy resins, brominated phenol novolac epoxy resins, and
the like; and other epoxy resins such as phenol aralkyl epoxy
resins (commonly named "epoxy compounds of Xylok resin"), resorcin
diglycidyl ether, hydroquinone diglycidyl ether, catechol
diglycidyl ether, biphenyl epoxy resins, tetramethylbiphenyl epoxy
resins, sulfur-containing epoxy resins, bifunctional epoxy resins
such as stilbene epoxy resins, triglycidyl isocyanurate,
triphenylmethane epoxy resins, tetraphenylethane epoxy resins,
dicyclopentadiene-phenol addition reaction-type epoxy resins,
biphenyl-modified novolac epoxy resins (epoxy compounds of
polyhydric phenol resins each containing phenol nuclei connected
through a bismethylene group), alkoxy group-containing novolac
epoxy resins, alkoxy group-containing phenyl aralkyl resins,
tetrabromobisphenol A epoxy resins, brominated phenol novolac epoxy
resins, and the like. These epoxy resins may be used alone or as a
mixture of two or more.
[0024] Among these epoxy resins, the bisphenol epoxy resins or the
novolac epoxy resins are particularly preferred from the viewpoint
that the epoxy resins have low viscosity and excellent impregnation
into reinforcing fibers, and cured products have a good physical
property balance between heat resistance and strength. As the
bisphenol epoxy resins, those having an epoxy equivalent of 500
g/eq. or less are preferred particularly from the viewpoint of
excellent fluidity at normal temperature and good impregnation into
reinforcing fibers, and particularly the bisphenol A epoxy resins
are preferred from the viewpoint that cured products have a good
balance between rigidity and moisture and heat resistance. The
epoxy equivalent of the bisphenol epoxy resins is particularly
preferably in the range of 100 to 300 g/eq. in view of fluidity of
the composition.
[0025] On the other hand, as the novolac epoxy resins, those having
a melt viscosity at 150.degree. C. in the range of 0.1 to 40 dPas
are particularly preferred in view of good fluidity of the
composition. In the present invention, the melt viscosity at
150.degree. C. is a value of ICI viscosity (150.degree. C.)
measured according to "ASTM D4287". Among the novolac epoxy resins,
an epoxy resin produced by reacting an ortho-cresol novolac resin
or phenol novolac resin with epihalohydrin is particularly
preferred from the viewpoint of fluidity.
[0026] In the present invention, as described above, the bisphenol
epoxy resin or novolac epoxy resin can be preferably used as the
poly(glycidyloxyaryl) compound (A). In the present invention, the
bisphenol epoxy resin or novolac epoxy resin may be combined with
another epoxy resin according to purposes. However, in this case,
the ratio of another epoxy resin is 5 to 80 parts by mass relative
to 100 parts by mass of the bisphenol epoxy resin or novolac epoxy
resin from the viewpoint that the performance of the bisphenol
epoxy resin or novolac epoxy resin can be sufficiently
exhibited.
[0027] In the present invention, among the bisphenol epoxy resin
and the novolac epoxy resin, the bisphenol epoxy resin,
particularly the bisphenol epoxy resin having an epoxy equivalent
of 500 g/eq. or less, is particularly preferred from the viewpoint
that the composition exhibits excellent fluidity and very high heat
resistance and mechanical strength.
[0028] Next, the polymerizable monomer (B) which has a molecular
weight of 160 or less and which is an unsaturated carboxylic acid
or an anhydride thereof used in the present invention reacts with
the poly(glycidyloxyaryl) compound (A) and polymerizes at acryloyl
groups by radical polymerization. In the present invention, curing
by the in-situ reaction can significantly improve the heat
resistance of a cured product. Specifically, the unsaturated
carboxylic acid (B) is preferably selected from the group
consisting of acrylic acid, methacrylic acid, maleic acid, fumaric
acid, crotonic acid, itaconic acid, and anhydrides thereof from the
viewpoint of the significant effect of improving fluidity of the
composition.
[0029] In particular, from the viewpoint of the effect of
decreasing viscosity and the excellent heat resistance of the cured
product, acrylic acid and methacrylic acid are preferred, and
methacrylic acid is particularly preferred.
[0030] Next, the aromatic vinyl compound or (meth)acrylate (C)
(hereinafter abbreviated as the "radical polymerization polymer
(C)") used in the present invention is an essential component for
decreasing the viscosity of the resin composition for a
fiber-reinforced composite material and exhibiting excellent
curability. In the radical polymerization polymer (C), examples of
the aromatic vinyl compound include styrene, methylstyrene,
halogenated styrene, and divinylstyrene.
[0031] On the other hand, as the (meth)acrylate, various
monofunctional (meth)acrylates and polyfunctional (meth)acrylates
can be used. Examples of the monofunctional (meth)acrylates include
(meth)acrylates having substituents such as methyl, ethyl, propyl,
butyl, 3-methoxybutyl, amyl, isoamyl, 2-ethylhexyl, octyl,
isooctyl, nonyl, isononyl, decyl, isodecyl, dodecyl, tridecyl,
hexadecyl, octadecyl, stearyl, isostearyl, cyclohexyl, benzyl,
methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl,
glycidyl, dimethylaminoethyl, diethylaminoethyl, isobornyl,
dicyclopentanyl, dicyclopentenyl, dicyclopentenyloxyethyl, and the
like.
[0032] Examples of the polyfunctional (meth)acrylates include
di(meth)acrylates of 1,3-butylene glycol, 1,4-butanediol,
1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol,
neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, tricyclodecane
dimethanol, ethylene glycol, polyethylene glycol, propylene glycol,
dipropylene glycol, tripropylene glycol, polypropylene glycol, and
the like; di(meth)acrylate of tris(2-hydroxyethyl)isocyanurate; a
diol di(meth)acrylate produced by adding 2 moles or more of
ethylene oxide or propylene oxide to 1 mole of 1,6-hexanediol; a
diol di(meth)acrylate produced by adding 4 moles or more of
ethylene oxide or propylene oxide to 1 mole of neopentyl glycol; a
diol di(meth)acrylate produced by adding 2 moles of ethylene oxide
or propylene oxide to 1 mole of bisphenol A; a triol di- or
tri(meth)acrylate produced by adding 3 moles or more of ethylene
oxide or propylene oxide to 1 mole of trimethylolpropane; a diol
di(meth)acrylate produced by adding 4 moles or more of ethylene
oxide or propylene oxide to 1 mole of bisphenol A;
trimethylolpropane tri(meth)acrylate; pentaerythritol
tri(meth)acrylate; pentaerythritol tetra(meth)acrylate;
dipentaerythritol poly(meth)acrylate; ethylene oxide-modified
phosphoric acid (meth)acrylate; ethylene oxide-modified alkylated
phosphoric acid (meth)acrylate; and the like.
[0033] Among these, styrene, methylstyrene, halogenated styrene,
divinylbenzene, monofunctional (meth)acrylates are preferred from
the viewpoint that the viscosity of vanish can be further
decreased. In particular, styrene or the monofunctional
(meth)acrylates, particularly styrene, is preferred from the
viewpoint of excellent compatibility with the poly(glycidyloxyaryl)
compound (A) and significant decrease in viscosity.
[0034] The poly(glycidyloxyaryl) compound (A), the polymerizable
monomer (B) which is an unsaturated carboxylic acid or an anhydride
thereof and which has a molecular weight of 160 or less, and the
aromatic vinyl compound or (meth)acrylate (C), which are described
above in detail, are mixed at such a ratio that the equivalent
ratio [glycidyloxy group/acid group] of glycidyloxy group in the
poly(glycidyloxyaryl) compound (A) to acid group in the component
(B) is 1/1 to 1/0.48, and the molar ratio [(B)/(C)] of the
polymerizable monomer (B) having a molecular weight of 160 or less
to the aromatic vinyl compound or (meth)acrylate (C) is in the
range of 1/0.55 to 1/2. When the equivalent ratio [glycidyloxy
group/acid group] is smaller than 1/1 (excess of the acid group
over the glycidyloxy group), the remaining component (B) acts as a
plasticizer and thus decreases heat resistance. On the other hand,
when the equivalent ratio [glycidyloxy group/acid group] is larger
than 1/0.48 (smaller amount of acid group), crosslinking is not
sufficiently produced, and thus heat resistance is not sufficiently
exhibited. On the other hand, when the molar ratio [(B)/(C)] is
higher than 1/0.55 (larger amount of component (B)), a cured
product has low heat resistance due to low curability. On the other
hand, when the molar ratio [(B)/(C)] is lower than 1/2 (smaller
amount of component (B)), the effect of improving heat resistance
is low.
[0035] The radical polymerization initiator (D) used in the present
invention may be any polymerization initiator as long as it is used
as a thermal radical polymerization initiator. Examples thereof
include methyl ethyl ketone peroxide, methylcyclohexanone peroxide,
methylacetoacetate peroxide, acetylacetone peroxide,
1,1-bis(tert-butylperoxy)3,3,5-trimethylcyclohexane,
1,1-bis(tert-hexylperoxy)cyclohexane,
1,1-bis(tert-hexylperoxy)3,3,5-trimethylcyclohexane,
1,1-bis(tert-butylperoxy)cyclohexane,
2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane,
1,1-bis(tert-butylperoxy)cyclododecane, n-butyl
4,4-bis(tert-butylperoxy)valerate, 2,2-bis(tert-butylperoxy)butane,
1,1-bis(tert-buylperoxy)-2-methylcyclohexane, tert-butyl
hydroperoxide, P-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl
hydroperoxide, tert-hexyl hydroperoxide.sub.r dicumyl peroxide,
2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane,
.alpha.,.alpha.'-bis(tert-butylperoxy) diisopropylbenzene,
tert-butylcumyl peroxide, di-tert-butyl peroxide,
2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3, isobutyryl
peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide,
lauroyl peroxide, cinnamoyl peroxide, m-toluoryl peroxide, benzoyl
peroxide, diisopropyl peroxydicarbonate,
bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-3-methoxybutyl
peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-sec-butyl
peroxydicarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate,
di(4-t-butylcyclohexyl) peroxydicarbonate,
.alpha.,.alpha.'-bis(neodecanoylperoxy) diisopropylbenzene, cumyl
peroxyneodecanoate, 1,1,3,3,-tetramethylbutyl peroxyneodecanoate,
1-cyclohexyl-1-methylethyl peroxyneodecanoate, tert-hexyl
peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-hexyl
peroxypivalate, tert-butyl peroxypivalate,
2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane,
1,1,3,3-tetramethylbutylperoxy-2-ethyl hexanoate,
1-cyclohexyl-1-methylethylperoxy-2-ethyl hexanoate,
tert-hexylperoxy-2-ethyl hexanoate, tert-butylperoxy-2-ethyl
hexanoate, tert-butyl peroxyisobutylate, tert-butyl peroxymaleic
acid, tert-butyl peroxylaurate, tert-butylperoxy-3,5,5-trimethyl
hexanoate, tert-butylperoxyisopropyl monocarbonate,
t-butylperoxy-2-ethylhexyl monocarbonate,
2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl
peroxyacetate, tert-hexyl peroxybenzoate, tert-butyl
peroxy-m-toluoryl benzoate, tert-butyl peroxybenzoate,
bis(tert-butylperoxy) isophthalate, tert-butylperoxyally
monocarbonate,
3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and the
like. The radical polymerization initiator (D) is preferably
contained at a ratio of 0.001% by mass or more and 5% by mass or
less relative to the total mass of the radical polymerizable
components and the radical polymerization initiator (D).
[0036] The resin composition for a fiber-reinforced composite
material of the present invention may further appropriately contain
a reaction catalyst for reacting the poly(glycidyloxyaryl) compound
(A) and the acid group-containing polymerizable monomer (B).
Examples of the reaction catalyst include tertiary amines such as
triethylamine, N,N-benzyldimethylamine, N,N-dimethylphenylamine,
N,N-dimethylaniline, and diazabicyclooctane; quaternary ammonium
salts such as trimethylbenzyl ammonium chloride, triethylbenzyl
ammonium chloride, methyltriethyl ammonium chloride, and the like;
phosphines such as triphenylphosphine, tributylphosphine, and the
like; imidazoles such as 2-methylimidazole, 1,2-dimethylimidazole,
2-ethyl-4-methylimidazole, and the like; triphenylstibine; anion
exchange resins; and the like. The amount of the catalyst used in
the resin composition for a fiber-reinforced composite material,
which is vanish, is preferably in the range of 0.01% to 5% by mass,
particularly 0.05% to 3% by mass, in view of excellent
reactivity.
[0037] The above-detailed resin composition for a fiber-reinforced
composite material of the present invention may further contain a
flame retardant from the viewpoint of imparting flame retardancy to
a cured product. Examples of the flame retardant used include
halogen-based flame retardants such as poly(brominated diphenyl
ether), poly(brominated biphenyl), tetrabromobisphenol A,
tetrabromobisphenol A epoxy resins, and the like; and
non-halogen-based flame retardants such as phosphorus-based flame
retardants, nitrogen-based flame retardants, silicone-based flame
retardants, inorganic flame retardants, organic metal salt-based
flame retardants, and the like. Among these, the non-halogen flame
retardants are particularly preferred because of the recent high
requirement for the non-halogen type.
[0038] If required, various compounding agents such as a silane
coupling agent, a release agent, an ion trapping agent, a pigment,
and the like can be added to the resin composition for a
fiber-reinforced composite material of the present invention.
[0039] The resin composition for a fiber-reinforced composite
material of the present invention can be easily prepared as a
liquid composition by uniformly stirring the above-described
components.
[0040] The resin composition for a fiber-reinforced composite
material of the present invention can be prepared as vanish with
using no organic solvent or using a very small amount of organic
solvent. Examples of the organic solvent include acetone, methyl
ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl
acetate, ethylene glycol monomethyl ether, N,N-dimethylformamide,
methanol, ethanol, and the like. The amount of the organic solvent
used is preferably 10% by mass or less in the composition, and
particularly substantially no organic solvent is preferably
used.
[0041] The resin composition for a fiber-reinforced composite
material of the present invention, i.e., vanish for impregnation of
reinforcing fibers, has high fluidity and exhibit excellent heat
resistance after curing as compared with usual vanish. However,
viscosity (E-type viscometer) at a temperature condition for
impregnating reinforcing fibers and curing, particularly a
temperature condition for molding by the RTM method, is preferably
500 mPas or less. In the present invention, from the viewpoint of
significantly exhibiting this performance, the vanish produced by
uniformly mixing the above-described components preferably has a
viscosity of 500 mPas or less, specifically 5 to 500 mPas, which is
measured with an E-type viscometer ("TV-20 type" cone-plate type,
manufactured by Toki Sangyo Co., Ltd.) at 25.degree. C. after the
elapse of 1 hour from preparation of the vanish. Since the vanish
of the present invention has such lower viscosity than usual vanish
for CFRP, the heating temperature for impregnating a fiber
reinforcement with the vanish can be suppressed to be low, or
impregnation can be performed at the normal temperature range of
5.degree. C. to 40.degree. C. Further, the vanish has excellent
storage stability and thus is slightly thickened and can maintain a
viscosity condition of 5 to 500 mPas at 25.degree. C. even after
the elapse of 1 week from the preparation of the vanish. On the
other hand, it is a significant point that a molding produced by
impregnating the fiber reinforcement with the vanish having such
low viscosity and curing by the in-situ polymerization reaction has
strength not inferior to conventional CFRP moldings and is rather
significantly improved in heat resistance. From the viewpoint of
significantly exhibiting this characteristic performance of the
present invention, the viscosity is particularly preferably 300
mPas or less, and particularly when a bisphenol epoxy resin having
an epoxy equivalent of 500 g/eq. or less is used, the viscosity is
preferably 200 mPas or less. In this case of using a bisphenol
epoxy resin having an epoxy equivalent of 500 g/eq. or less, even
when the viscosity is adjusted to a very low value of 200 mPas or
less, a cured product and molding having excellent heat resistance
and strength can be produced.
[0042] As described above, the cured product of the resin
composition for a fiber-reinforced composite material of the
present invention is produced by the in-situ polymerization
reaction. Here, as described above, the in-situ polymerization
reaction represents that both the reaction between the glycidyloxy
group and the acid group and the polymerization reaction of radical
polymerizable group are simultaneously or continuously performed
without being particularly distinguished as separate reaction
steps.
[0043] Specifically, the curing temperature for the in-situ
polymerization reaction is preferably in the temperature range of
50 to 250.degree. C., and particularly preferably, curing is
performed at 50 to 100.degree. C. to form a tack-free cured
product, followed by further treatment under a temperature
condition of 120.degree. C. to 200.degree. C.
[0044] In addition, a fiber-reinforced composite material of the
present invention contains the above-described resin composition
for a fiber-reinforced composite material and reinforcing fibers as
essential components, and specifically the fiber-reinforced
composite material is produced by impregnating a reinforcing base
material composed of reinforcing fibers with the vanish prepared by
uniformly mixing the components, i.e., the resin composition for a
fiber-reinforced composite material.
[0045] Therefore, the cured product is produced by impregnating a
reinforcing base material composed of reinforcing fibers with the
resin composition for a fiber-reinforced composite material and
then performing the in-situ polymerization reaction.
[0046] Herein, the reinforcing fibers may be any one of a twist
yarn, an untwisted yarn, and a zero-twist yarn, but the untwisted
yarn and the zero-twist yarn are preferred because both moldability
and mechanical strength of a fiber-reinforced plastic member are
satisfied. Further, as a form of the reinforcing fibers, fibers
aligned in one direction or a fabric can be used. The fabric can be
freely selected from a plain fabric, a satin fabric, and the like
according to the place and purpose of use. Specifically, carbon
fibers, glass fibers, aramid fibers, boron fibers, alumina fibers,
silicon carbide fibers, and the like can be used because of
excellent mechanical strength and durability. These may be used in
combination of two or more types. Among these, the carbon fibers or
the glass fibers are particularly preferred from the viewpoint of
good strength of a molding. As the carbon fibers, various types
such as polyacrylonitrile-based, pitch-based, and rayon-based
fibers can be used. In particular, the polyacrylonitrile-based
carbon fibers are preferred because high-strength carbon fibers can
be easily produced. On the other hand, a glass soft mat, a glass
cloth, a strong cloth, and the like can be used as the glass
fibers.
[0047] In addition, in producing the fiber-reinforced composite
material by impregnating the reinforcing base material composed of
the reinforcing fibers with the vanish, the amount of the
reinforcing fibers used is preferably such that the volume content
of the reinforcing fibers in the fiber-reinforced composite
material is in the range of 40% to 85%.
[0048] A fiber-reinforced resin molding of the present invention is
a molding including reinforcing fibers and a cured product of the
resin composition for a fiber-reinforced composite material, and
specifically the amount of the reinforcing fibers in the
fiber-reinforced resin molding is preferably in the range of 40 to
85%, particularly from the viewpoint of strength, in the range of
50 to 70%, in terms of volume content.
[0049] Examples of a method for producing the fiber-reinforced
resin molding include a hand lay-up method or spray-up method
including spreading a fiber aggregate in a mold and then laminating
the vanish in multiple layers; a vacuum impregnation method (VaRTM
method) in which a base material composed of reinforcing fibers is
stacked while being impregnated with the vanish using one of male
and female molds to form a molded product, and the molded product
is covered with a flexible mold capable of applying pressure to the
molded product, airtight-sealed, and then vacuum
(reduced-pressure)-molded; a SMC press method in which the vanish
containing reinforcing fibers is formed into a sheet and then
compression-molded with a mold; a RTM method including injecting
the vanish into a combined mold having a fiber bed; and a method
including producing a prepreg by impregnating reinforcing fibers
with the vanish and then baking the prepreg in a large autoclave.
Among these methods, the RTM method and the VaRTM method can be
preferably applied to the present invention in view of excellent
fluidity of the vanish.
[0050] A specific example of the method for producing the
fiber-reinforced resin molding by the RTM method is a method in
which a base material composed of reinforcing fibers is disposed in
a mold and impregnated with the resin composition for a
fiber-reinforced composite material by injecting the resin
composition, followed by curing by the in-situ polymerization
reaction.
[0051] Examples of the base material composed of reinforcing fibers
include a fabric, a knit, a mat, and a blade, which are composed of
reinforcing fibers. Any one of these materials may be further
laminated, shaped, and fixed by means such as a binder or stitching
and used as a preform.
[0052] In addition, a closed mold made of a material such as iron,
steel, aluminum, FRP, wood, gypsum, or the like can be used as the
mold.
[0053] The fiber-reinforced resin molding produced by the RTM
method is preferably produced by a vacuum RTM molding method
including reducing the pressure in a cavity of the mold in which
the base material composed on reinforcing fibers is disposed, and
injecting the resin composition for a fiber-reinforced composite
material into the cavity by way of a differential pressure between
the reduced pressure in the cavity and external pressure to
impregnate the base material with the resin composition.
Specifically, the method includes shaping the base material
composed of reinforcing fibers along the mold surface of a lower
mold, clamping the base material with the upper and lower molds,
reducing the pressure in the cavity of the mold, impregnating the
base material with the resin composition for a fiber-reinforced
composite material, and then in-situ curing the resin composition
under the above-described curing temperature condition. In this
case, before the base material composed of reinforcing fibers is
disposed on the mold surface of the lower mold, a gel coating is
preferably applied to the mold surface from the viewpoint of good
appearance of the molding. After curing, the intended
fiber-reinforced resin molding can be obtained by removal from the
mold. In the present invention, after the removal from the mold,
post-curing may be further performed at a higher temperature.
[0054] In addition, besides the reinforcing fiber base material, a
foam core, a honeycomb core, or a metal component may be disposed
in the mold to produce a composite material integrated with this
member. In particular, a sandwich structure produced by disposing
carbon fiber base materials on both sides of the foam core and then
molding is useful as, for example, an outside plate material for an
automobile or an aircraft, because it is lightweight and has large
flexural rigidity.
[0055] On the other hand, a specific example of the method for
producing the fiber-reinforced resin molding by the vacuum
impregnation method (VaRTM method) is a method in which the
reinforcing fiber base material is laminated on either the male
mold or the female mold and is further covered with a plastic film,
and the vanish is injected under vacuum pressure attained by vacuum
suction to impregnate the reinforcing fiber base material with the
vanish, and is then cured by the in-situ polymerization
reaction.
[0056] The vacuum impregnation method (VaRTM method) is a RTM
method, and a usable mold material is substantially the same as in
the RTM method. In addition, the reinforcing fiber base material is
preferably composed of carbon fibers or glass fibers from the
viewpoint of strength of the resultant molding. In particular, a
large blade such as a wind-power generation blade is preferably
produced by the vacuum impregnation method (VaRTM method) from the
viewpoint that the blade is required to have high strength and
rigidity and is produced with a large area and a large thickness.
In addition, reinforcing fibers for such a wind-power generation
blade are preferably glass fibers in view of easy response to an
increase in size of the molding. The wind-power generation blade
tends to be significantly increased in size, and low viscosity and
long working life of vanish are important factors for producing
glass fiber-reinforced plastic (GFRP) having a low void content and
high quality. The fiber-reinforced resin composition of the present
invention complies with these requirements and thus is particularly
suitable for a resin material for a wind-power generation
blade.
[0057] Examples of application of the fiber-reinforced resin
molding produced as described above include sporting goods such as
a fish pole, a golf shaft, a bicycle frame, and the like; frames or
body materials of automobiles and aircrafts; spacecraft members; a
wind-power generation blade; and the like. In particular, an
automobile member, an aircraft member, and a spacecraft member are
required to have high heat resistance and strength, and thus the
fiber-reinforced resin molding of the present invention is suitable
as a CFRP molding for these applications, and particularly suitable
for automobile members, e.g., automobile structural members such as
an underbody, a monocoque, a platform, and the like; a bumper; a
fender; a front door; panel members such as a door inner panel, a
door outer panel, a hood panel, and the like; and interior parts
such as an instrument panel and the like. Further, the
fiber-reinforced resin molding can be used as members of not only
gasoline automobiles but also diesel vehicles, bio-diesel vehicles,
fuel-cell vehicles, hybrid vehicles, electric cars, and the like.
On the other hand, the resin composition for a fiber-reinforced
composite material is particularly suitable for large moldings such
as a wind-power generation blade because the vanish has very
excellent fluidity.
EXAMPLES
[0058] Although the present invention is specifically described
below with reference to examples and comparative examples, "parts"
and "%." below are on a weight basis unless otherwise specified.
Each of the physical properties was measured under conditions
described below.
[0059] 1) Vanish viscosity: measured at 25.degree. C. using an
E-type viscometer ("TV-20 type" cone-plate type, manufactured by
Toki Sangyo Co., Ltd.).
[0060] 2) Softening point: measured according to "JIS K7234
(ring-and-ball method)".
[0061] 3) Melt viscosity at 150.degree. C. (ICI viscosity)
[0062] Melt viscosity at 150.degree. C. was measured according to
"ASTM D4287".
[0063] 4) Melt kinetic viscosity at 60.degree. C.
[0064] Measured at 60.degree. C. according to "JIS K-2283".
[0065] 5) Glass transition point (dynamic viscoelasticity
measurement (DMA method): A cured product was cut into a width of 5
mm and a length of 50 mm with a cutter and measured with respect to
dynamic viscoelasticity using "DMS6100" manufactured by SII
Nanotechnology Inc. in a double cantilever bending mode within the
measurement temperature range of room temperature to 260.degree. C.
at a heating rate of 3.degree. C./min, a frequency of 1 Hz (sine
wave), and a strain amplitude of 10 .mu.m. The temperature at
maximum tan 8 was regarded as Tg.
[0066] 6) Flexural strength and flexural elastic modulus of resin
plate: according to JIS 6911
[0067] 7) Flexural strength of carbon fiber-reinforced composite
material: according to JIS K7074
Examples 1 to 5 and Comparative Examples 1 to 5
[0068] 1. Mixing of Epoxy Resin Composition
[0069] According to each of the compositions shown in Table 1
below, an epoxy resin, a carboxylic acid, a polymerizable compound,
a radical polymerization initiator, a curing promoter, etc. were
mixed with a stirrer to prepare an epoxy resin composition. After
the elapse of 1 hour from the preparation of the epoxy resin
composition, vanish viscosity was evaluated.
[0070] 2. Formation of Epoxy Resin Cured Plate
[0071] A resin cured plate was formed under curing conditions A or
B below and subjected to various evaluation tests. The results are
shown in Table 1. The curing conditions used in each of the
examples and comparative examples are shown in Table 1.
[Curing conditions A]
[0072] The epoxy resin composition was poured into a space of a
mold including a spacer (silicone tube) having a thickness of 2 mm
and held between glass plates and then cured at 170.degree. C. for
10 minutes in an oven, and a cured product was removed from the
mold to produce a resin cured plate.
[Curing Conditions B]
[0073] The epoxy resin composition was poured into a space of a
mold including a spacer (silicone tube) having a thickness of 2 mm
and held between glass plates and then cured at 170.degree. C. for
1 hour in an oven, and a cured product was removed from the mold to
produce a resin cured plate.
[0074] 3. Preparation of Carbon Fiber-Reinforced Composite
Material
[0075] Four carbon fiber fabrics (carbon fiber: CO.sub.6343, fabric
weight 198 g/cm.sup.2, manufactured by Toray Co., Ltd.) cut into
150 mm.times.150 mm were stacked on a SUS sheet of 200 mm.times.200
mm.times.3.5 mm coated with
polytetrafluoroethylene/perfluoroalkylvinyl ether copolymer, and
the epoxy resin composition was cast and pressed with a roller to
impregnate the carbon fibers with the resin composition. Further,
another SUS sheet coated with
polytetrafluoroethylene/perfluoroalkylvinyl ether copolymer was
placed. Then, curing was performed at 100.degree. C. for 1 hour in
an oven, and then after curing was performed at 170.degree. C. for
1 hour to produce a fiber-reinforced composite material having a
thickness of 1.5 mm. According to visual observation, voids such as
bubbles were not observed in the fiber-reinforced composite
material. The composite material was used as a test piece for
various evaluation tests. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5 1 2 3
4 5 Composition Epoxy resin BPA-type liquid epoxy 33.2 24.9 2.5
22.6 18.6 (A) resin Phenol novolac epoxy 29.5 resin A Phenol
novolac epoxy 22.2 31 resin B BPA novolac epoxy 26.2 resin
Alicyclic epoxy resin 25 Polyglycidylamine 20 Acid group-
Methacrylic acid 7 7.6 11.4 11.5 10.8 15 6.5 12.4 8.6 12 containing
polymerizable monomer (B) Aromatic vinyl Styrene 13.6 4.6 6.9 13.9
13 10 13 15 22.8 13 compound or Isobornyl methacrylate 4.6 6.9
(meth)acrylate (C) Other Radical polymerization 0.5 0.5 0.5 0.5 0.5
-- -- 0.5 0.5 -- components initiator A Radical polymerization --
-- -- -- -- -- 0.5 -- -- -- initiator B 2-Methylimidazole 0.5 0.5
0.5 0.5 0.5 -- -- 0.5 0.5 -- 2-Ethyl-4- -- -- -- -- -- -- 0.5 -- --
-- methylimidazole Glycerin 0.5 0.5 0.5 0.5 0.5 -- -- -- -- --
Epoxy group in component (A)/acid group in 1/0.5 1/0.5 1/1 1/1 1/1
1/0.9 1/0.46 1/1.2 1/1 1/0.8 component (B) [equivalent ratio]
Component (B)/component (C) [molar ratio] 1/1.6 1/0.7 1/0.6 1/1 1/1
1/0.45 1/1.7 1/1 1/2.2 1/1.25 Composition viscosity mPaS 25.degree.
C. 100 99 23 97 116 1 484 7 4 7 Viscosity 24 hr after 238 202 41
156 196 48 635 15 7 8 Curing conditions A A A B B A A A A A
Physical properties of resin DMA Tg 170.degree. C./ 180 174 179 197
204 198 172 174 156 164 cured plate 10 min Flexural strength 121
135 140 133 125 120 115 113 118 120 (MPa) Flexural modulus 3350
3210 3350 3280 3300 3800 3300 2900 2890 3370 (MPa) Flexural strain
(%) 4.2 5.9 6.1 4.2 4.3 2.5 2.8 3.6 3.5 4.2 CFRP physical
properties Fiber mass content (%) 43 45 42 49 44 42 45 44 48 42
Flexural strength 450 460 420 450 440 460 380 420 406 430 (MPa) In
Table 1, "A" and "B" in "Curing conditions" correspond to "Curing
conditions A" and "Curing conditions B", respectively, described
above.
Comparative Examples 6 to 8
[0076] According to each of the compositions shown in Table 2
below, components were mixed with a stirrer to prepare a resin
composition. After 1 hour elapsed from the preparation of the resin
composition, vanish viscosity was evaluated, and then after 1 week
further elapsed, vanish viscosity was measured. Next, as in Example
1, the resin composition was poured into a space of a mold
including a spacer (silicone tube) having a thickness of 2 mm and
held between glass plates and then cured at 100.degree. C. for 4
hours in an oven to produce a resin cured plate having a thickness
of 2 mm. The resin cured plate was used as a test piece for various
evaluation tests. In addition, a carbon fiber-reinforced composite
material was formed by the same method as in Example 1 and
evaluated. The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Comparative Example 6 7 8 Composition
BPF-type liquid epoxy 77.5 77.5 resin Vinyl ester resin 72.5
Aromatic polyamine 21.8 21.8 Lewis acid catalyst A 0.7 Lewis acid
catalyst B 0.7 Styrene 27.5 Radical polymerization 1 initiator A
Composition viscosity (mPaS, 25.degree. C.) 23000 20000 320
Viscosity 24 hr after Solidified Solidified 630 Physical DMA Tg 115
114 150 properties of Flexural strength 138 121 117 resin cured
(MPa) plate Flexural modulus 3370 3300 3500 (MPa) CFRP physical
Fiber mass content (%) -- -- 42 properties Flexural strength -- --
350 (MPa)
[0077] The components used for the epoxy resin compositions of the
examples and the comparative examples are as follows.
[0078] "BPA-type liquid epoxy resin": bisphenol A liquid epoxy
resin (trade name "EPICLON 850S" manufactured by DIC Corporation,
epoxy equivalent of 188 g/eq.)
[0079] "Cresol novolac epoxy resin": cresol novolac epoxy resin
(trade name "EPICLON N-695" manufactured by DIC Corporation, epoxy
equivalent of 212 g/eq., melt viscosity at 150.degree. C. of 28
dPas, softening point of 95.degree. C.)
[0080] "Phenol novolac epoxy resin A": phenol novolac epoxy resin
(trade name "EPICLON N-740" manufactured by DIC Corporation, epoxy
equivalent of 178 g/eq., melt dynamic viscosity at 60.degree. C. of
8500 centistokes)
[0081] "Phenol novolac epoxy resin B": phenol novolac epoxy resin
(trade name "EPICLON N-770" manufactured by DIC Corporation, melt
viscosity at 150.degree. C. of 4.8 dPas, epoxy equivalent of 186
g/eq., softening point of 68.degree. C.)
[0082] "BPA novolac epoxy resin": bisphenol A novolac epoxy resin
(trade name "EPICLON N-865" manufactured by DIC Corporation, melt
viscosity at 150.degree. C. of 2.7 dPas, epoxy equivalent of 208
g/eq., softening point of 67.degree. C.)
[0083] "BPF-type liquid epoxy resin B": bisphenol F liquid epoxy
resin (trade name "EPICLON 830" manufactured by DIC Corporation,
epoxy equivalent of 171 g/eq.)
[0084] "Alicyclic epoxy resin":
(3,4-epoxycyclohexane)-methyl-3',4'-epoxycyclohexyl carboxylate
("CELLOXIDE 2021P" manufactured by Daicel Chemical Industries,
Ltd.)
[0085] "Polyglycidylamine": N,N,N',N'-tetraglycidyldiaminodiphenyl
methane ("ARALDITE MY721CH" manufactured by Huntsman Advanced
Materials Co., Ltd.)
[0086] "2-Ethyl-4-methylimidazole": 2-ethyl-4-methylimidazole
("CURESOLE 2E4MZ" manufactured by Shikoku Chemicals Corp.)
[0087] "Isobornyl methacrylate": isobornyl methacrylate ("LIGHT
ESTER IB-X" manufactured by Kyoeisha Chemical Co., Ltd.)
[0088] "Vinyl ester resin": bisphenol A epoxy methacrylate
(reaction product of "EPICLON 850S" with methacrylic acid)
[0089] "Aromatic polyamine": diethyltoluenediamine (trade name
"ETHACURE-100" amine-based curing agent, manufactured by PTI Japan
Co., Ltd.)
[0090] "Lewis acid catalyst A": boron trifluoride tetrahydrofuran
complex
[0091] "Lewis acid catalyst B": boron trifluoride diethyl ether
complex
[0092] "Radical polymerization initiator A":
1,1-di(tert-hexylperoxy)cyclohexane (polymerization initiator
"PERHEXA HC" manufactured by NOF Corporation)
[0093] "Radical polymerization initiator B": cumene hydroperoxide
("PERCUMYL H-80" manufactured by NOF Corporation)
[0094] "2-Methyl imidazole": 2-methylimidazole ("CURESOLE 2MZ"
manufactured by Shikoku Chemicals Corp.)
* * * * *