JPH05339472A - Fiber reinforced composite material - Google Patents

Abstract

PURPOSE:To obtain a fiber reinforced composite material excellent in toughness while keeping excellent characteristics of an epoxy resin itself, e.g. high glass transition temperature or mechanical strength. CONSTITUTION:The objective composition is obtained by impregnating a composition obtained by dispersing (b) a crosslinked rubbery copolymer in (a) a compound containing an epoxy group in a granular state into (c) a fibrous filler. As the component (a), a compound containing an epoxy group in the molecule is used without specific limitation. As the concrete examples of the component (a), a bisphenol skeleton-containing polyol type epoxy compound, mention may be made of a polyurethane skeleton-containing epoxy compound, etc. Glass transition temperature is normally <=25 deg.C, preferably <=0 deg.C and further preferably <=-20 deg.C. As the component C, there are usable an inorganic fiber such as a carbon fiber, a graphite fiber, a glass fiber or a silicon carbide fiber or an organic fiber such as an aromatic polyamide fiber or a polyester fiber.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to composite materials and more particularly to fiber reinforced epoxy composite materials having high toughness.

[0002]

2. Description of the Related Art Composite materials reinforced with carbon fibers, glass fibers and the like are used for golf shafts, sports and leisure products such as fishing rods, aircraft parts, vehicle parts and the like. As a matrix resin for a fiber-reinforced composite material, an epoxy resin is often used because it is easy to mold and has excellent adhesiveness to fibers. However, since the epoxy resin forms a brittle cured product, cracks may occur during cooling in the molding process of the composite material, and even if a mold is formed, the residual compressive strength (CAI) of the composite material after impact is low, There are problems such as low punching impact strength,
It was not suitable for applications requiring high toughness. As one of methods for solving the above problems, it has been proposed to mix an epoxy resin, which is a matrix resin of a composite material, with a liquid acrylonitrile-butadiene rubber having a functional group capable of reacting with the epoxy resin in the molecule. There is. However, when a liquid acrylonitrile-butadiene rubber or the like is mixed with an epoxy resin, it has compatibility with the epoxy resin, so that the characteristics of the epoxy resin composite material, such as high glass transition temperature and mechanical strength, can be maintained while maintaining toughness. It was difficult to give.

[0003]

DISCLOSURE OF THE INVENTION The present invention overcomes the problems of the fiber-reinforced epoxy composite material as described above,
An object is to provide a fiber reinforced composite material having high toughness.

[0004]

That is, the present invention is as follows.
A fiber-reinforced composite material comprising (a) a compound having an epoxy group, (b) a crosslinked rubber-like polymer, and (c) a fiber. Hereinafter, the present invention will be described in detail. The component (a) used in the present invention is not particularly limited as long as it is a compound containing an epoxy group in the molecule. Specific examples of the component (a) include, for example, compounds described as "compounds having an epoxy group" in JP-A-2-117948, bisphenol skeleton-containing polyol type epoxy compounds, polyurethane skeleton-containing epoxy compounds. And so on. The composite material of the present invention is
It is characterized in that the component (b) dispersed in the component (a) is a crosslinked rubbery polymer.

The component (b) will be described below.
The crosslinked rubber-like copolymer (hereinafter referred to as "copolymer (b)") as the component (b) has rubber-like elasticity at room temperature, and its glass transition temperature (Tg) is usually 2
The temperature is set to 5 ° C or lower, preferably 0 ° C or lower, and more preferably -20 ° C or lower. The degree of crosslinking of the copolymer (b) can be indicated by the gel content. Here, the "gel content" means the weight ratio of the insoluble matter after about 1 g of the polymer was immersed in 100 ml of methyl ethyl ketone and allowed to stand at room temperature for 24 hours. The gel content of the copolymer (b) is preferably 20% by weight or more, more preferably 40% by weight or more, and particularly preferably 40 to 99% by weight. If the gel content is too low, the dispersibility of the copolymer (b) in the component (a) becomes insufficient,
In addition, it becomes difficult to obtain a composite material having excellent toughness.

The copolymer (b) comprises a crosslinkable monomer (hereinafter referred to as "crosslinkable monomer b ₁ ") and another unsaturated compound copolymerizable therewith (hereinafter referred to as "copolymerizable monomer b ₁ ").
₂ ")). The crosslinkable monomer b ₁ used in the copolymer reaction is a compound having two or more polymerizable double bonds in its molecular structure, and specific examples thereof include divinylbenzene, diallyl phthalate, ethylene glycol di (meth). ) Acrylate and trimethylolpropane tri (meth) acrylate. By using the crosslinkable monomer b ₁ , in the obtained copolymer (b), it is possible to increase the gel content, that is, improve the crosslinkability. The proportion of the crosslinkable monomer b ₁ in the copolymer (b) is usually 0.1 to 20% by weight, preferably 0.5 to 15% by weight.

The copolymerizable monomer b ₂ to be used in the copolymer reaction is not particularly limited as long as it is a compound which can be copolymerized with the above-mentioned crosslinkable monomer b _1, and specific examples thereof include conjugated dienes. For example, butadiene, dimethyl butadiene, isoprene, chloroprene and derivatives thereof, and the like, (meth) acrylic acid derivatives such as (meth) acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, Butyl (meth) acrylate, hexyl (meth) acrylate,
Cyclohexyl (meth) acrylate, lauryl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, urethane (meth) acrylate, and other olefins such as ethylene, propylene, 1-butene, and 2-butene. , Isobutene, 1-pentene and the like, and aromatic vinyl compounds such as styrene and methylstyrene. The proportion of the copolymerizable monomer b _{2 in} the copolymer (b) is usually 60 to 98.5% by weight, preferably 70 to 97.5% by weight.

A functional group capable of reacting with the component (a) may be introduced into the copolymer (b). In order to introduce a functional group into the copolymer (b), a monomer containing a functional group (hereinafter, referred to as “functional group-containing monomer b ₃ ”) together with the crosslinkable monomer b ₁ and the copolymerizable monomer b ₂ is used. ) Is used to copolymerize these monomer mixtures. To introduce a functional group into the copolymer (b), the functional group-containing monomer b ₃ used as required, for example, in JP-A-2-117948 and JP-listed as "monomer I" carboxy Group-containing compound, acid anhydride group-containing compound, epoxy group-containing compound, amino group-containing compound, amide group-containing compound,
Examples thereof include a hydroxy group-containing compound, an isocyanate group-containing compound and a phosphoric acid group-containing compound. Among the functional groups contained in the functional group-containing monomer b ₃ , a carboxyl group, an acid anhydride group and an epoxy group are preferable because they each have a suitable reactivity with the component (a). The proportion of the functional group-containing monomer b ₃ in the copolymer (b), preferably from 0.1 to 20 wt%, more preferably from 0.5 to 15 wt%.

The copolymer (b) used in the present invention can be produced, for example, by an emulsion polymerization method. The emulsion polymerization method uses any of anionic, cationic, nonionic and amphoteric surfactants as an emulsifier, or a mixed system thereof, and in the presence of a molecular weight modifier, a crosslinkable monomer by a radical polymerization initiator. The polymerization reaction between b ₁ and the copolymerizable monomer b ₂ or the polymerization reaction between these and the functional group-containing monomer b ₃ was started, the polymerization reaction was continued at 0 to 70 ° C., and a predetermined polymerization conversion rate was reached. By the way, a method of obtaining a latex of the copolymer (b) by adding a reaction terminator to stop the polymerization reaction and removing unreacted monomers in the system by steam distillation or the like. Here, specific examples of the surfactant and the radical polymerization initiator, details of the emulsion polymerization method, and the like are described in JP-A No. 2-117948. Moreover, the copolymer (b) may be obtained by a suspension polymerization method, a solution polymerization method, or the like.

Copolymer (b) dispersed in component (a)
The shape of is not particularly limited, and may be composed of, for example, seed particles and a copolymer coating the seed particles. Here, the seed particles may be a polymer having a glass transition temperature (Tg) of 25 ° C. or lower. The copolymer for coating the seed particles is obtained by copolymerization (seed polymerization) of a monomer mixture containing at least the above-mentioned crosslinkable monomer b ₁ and giving a copolymer having a glass transition temperature (Tg) of 25 ° C. or lower (seed polymerization). Any copolymer can be obtained. The monomer for forming such a copolymer can be appropriately selected from the group consisting of the above-mentioned crosslinkable monomer b ₁ , copolymerizable monomer b ₂ and functional group-containing monomer b ₃ , and these can be used alone or in 2 A mixture of two or more species can be used. Of these, styrene, butadiene, acrylonitrile, (meth) acrylic acid, alkyl (meth) acrylate, alkoxy (meth) acrylate, polyfunctional vinyl compounds and the like are preferable.

The dispersion of seed particles (hereinafter referred to as "seed latex") has, for example, a glass transition temperature (T
A latex obtained by dissolving a polymer whose g) is 25 ° C. or lower in a solvent and dispersing it in water with an emulsifier using a stirrer such as a homomixer, or a latex obtained by emulsion polymerization can be used. Of these, the seed latex obtained by emulsion polymerization is easy to transfer from the polymerization step of the seed latex to the next copolymerization step, the process can be simplified, and the final obtained copolymer It is preferable because the particle size of the polymer particles can be easily controlled. Preferred seed polymerization methods include:
A method of continuously performing emulsion polymerization in a plurality of stages, that is, the first stage has a glass transition temperature (Tg) of 2 or more.
A seed latex composed of a polymer at 5 ° C. or lower was synthesized by emulsion polymerization, and as a second step, a monomer mixture containing at least a crosslinkable monomer b ₁ in the system of the seed latex obtained in the first step and a necessary Such a method may be used in which emulsion polymerization is continuously carried out by adding various additives. In addition, in the first stage and / or the second stage,
It is also possible to add the monomer in several times.

The copolymer (b) is blended in the component (a) and dispersed in the form of particles. Examples of the dispersion method of the copolymer (b) include a latex of the copolymer (b), a dispersion liquid or a solution (hereinafter referred to as “dispersion system of the copolymer (b)”),
A method of forcibly stirring the component (a) under a shearing force to remove the separated water and / or solvent and drying the component (a), emulsifying or suspending the component in an aqueous system, and adding the copolymer (b) A method of mixing with a dispersion system and then coagulating, removing water and / or a solvent, and drying; mixing a coagulated product of the copolymer (b) before drying with the component (a), and then water and / or Alternatively, the method of removing the solvent and drying, the copolymer (b) is separated by coagulating or desolvating the dispersion system of the copolymer (b), and after drying, the mixture is forcibly stirred again to an organic solvent. Disperse this system and (a)
A method of mixing the components with each other, then removing the solvent and drying the mixture, the coagulated product of the copolymer (b) is pulverized if necessary, and then a conventional hot roll, intermixer, kneader,
Examples thereof include a method of dispersing with an extruder, a high speed shearing stirrer and the like.

In the present invention, the dispersion content of the copolymer (b) per 100 parts by weight of the component (a) is usually 1
To 100 parts by weight, preferably 1 to 50 parts by weight, and more preferably 2 to 30 parts by weight. When the dispersed content of the copolymer (b) is less than 1 part by weight, effects such as toughness are difficult to be exhibited, and when it exceeds 100 parts by weight, the mechanical strength and thermal properties which are the characteristics of the component (a). Is damaged. In addition,
The copolymer (b) dispersed in the component (a) may be composed of two or more kinds of copolymers having different compositions, shapes and particle sizes. In the composite material of the present invention, the particle size of the copolymer (b) dispersed in the component (a) is usually 20.
0 to 500 angstrom, preferably 500
~ 400 angstrom. This particle size is 200
If it is less than angstrom, the viscosity of the composition tends to be high and handling tends to be difficult. On the other hand, if the particle size exceeds 500 angstroms, the toughness of the obtained composite material tends to decrease.

As the component (c) used in the present invention,
Carbon fibers, graphite fibers, glass fibers, silicon carbide fibers, alumina fibers, silica-alumina fibers, titania fibers, inorganic fibers such as silicon nitride fibers, aromatic polyamide fibers,
Organic fibers such as polyester fibers can be used. Furthermore, these fibers can be used in combination of two or more kinds as required. These fibers are continuous tow,
It can be used in the form of short fibers, woven cloth, non-woven cloth or the like, and may be surface-treated in order to enhance wettability. (C)
The ratio of the components is 20 to 100 with respect to (a) + (b) = 100 by volume.

The fiber-reinforced composite material according to the present invention can be manufactured by a known method. For example, the hand layup method,
The rolling table method, filament winding method, pull-through method, autoclave method, press molding method, resin injection method, casting method, etc.
If necessary, additives may be added to the composite material obtained as described above. Examples of such additives include silica, clay, gypsum, calcium carbonate,
Quartz powder, kaolin, mica, sodium silicate, talc, calcium silicate, titanium compounds, fillers such as antimony compounds, coupling agents, pigments, organosilane compounds, coupling agents such as organic titanate compounds, xylene resins, difficult Mention may be made of flamming agents, diluents, stabilizers and antiaging agents.

The composite material of the present invention is mixed with a curing agent and / or a curing accelerator and subjected to a curing treatment,
The cured product has excellent toughness. Such curing agents and / or curing accelerators are epoxy resin curing types,
For example, various types can be selected according to the type such as two-pack type, one-pack type, thermosetting type, and photocuring type. Specifically, in JP-A-2-117948, "Curing agent and And / or curing accelerators. The amount of the curing agent used is usually such that the active hydrogen group of the curing agent and the epoxy group of the component (a) are almost equivalent. In addition, the proper amount of the curing accelerator is selected according to the type and curing conditions.

When a carboxy group is introduced into the copolymer (b) by the combined use of the functional group-containing monomer b _{3 and} the like, the obtained composite material is treated with a curing agent prior to curing treatment with a curing agent. It is preferable to carry out a preliminary reaction in which the carboxyl group on the surface of the dispersed particles which is the polymer (b) is previously reacted with the epoxy group in the component (a). This pre-reaction is carried out without catalyst or with triphenylphosphine, phosphonium halide, triethanolamine,
It is carried out by heating at room temperature to about 200 ° C. for several hours in the presence of a catalyst such as a chromium complex of acetylacetonate, chromium diisopropylsalicylate, tetraethylammonium chloride, triisoamylamine, tributylamine, trisdimethylaminomethylphenol.

(Examples) Examples of the present invention will be described below. The present invention is not limited to these. In the description in the examples, "part" represents part by weight. Examples and Comparative Examples (1) Copolymer No. 1 to 5 Emulsion polymerization was carried out at 20 ° C. in an autoclave according to the formulation shown in the following 3. Monomer (Note) 100 parts Water 250 parts Sodium dodecylbenzenesulfonate 0.1-1.8 parts Tertiary dodecyl mercaptan 0.45 parts Potassium persulfate 0.27 parts Cyanoethylated diethanolamine 0.15 parts Potassium hydroxide 0. 10 parts (Note) The monomer here means the total amount of the monomer b ₂ , the crosslinkable monomer and the monomer b ₃ which have the composition shown in Table 1 after the polymerization. Then, after the polymerization conversion rate reached 90%, 0.2 part of hydroxylamine sulfate was added per 100 parts of the total amount of the monomers to terminate the polymerization. Then, unreacted monomers were removed by steam distillation to obtain latexes of copolymers Nos. 1 to 5. A part of the obtained latex of the copolymer (b) is used as it is for mixing with the component (a), and the rest is added with 1 part of alkylphenol as an antioxidant per 100 parts of the copolymer and coagulated with an aqueous calcium chloride solution. Then, the obtained copolymer solidified product was washed with water and dried in vacuum at 50 ° C.

[0019]

[Table 1]

(2) Copolymer Nos. 6 to 10 Emulsion polymerization was carried out at 60 ° C. in an autoclave using the following emulsion polymerization formulations. Butadiene 8 parts Styrene 11 parts Methacrylic acid 1 part Water 280 parts Sodium dodecylbenzene sulfonate 0.05 parts Sodium persulfate 0.5 parts Dodecyl mercaptan 0.7 parts After the reaction has reached a polymerization conversion rate of 95%, The monomer was added to the autoclave. Butadiene 22 parts Styrene 10 parts Methacrylic acid 1 part Potassium persulfate 0.1 part Polymerization was continued, and when the polymerization conversion rate reached 95%, this was used as a seed latex, and the following monomers were further added to continue the polymerization. It was Butadiene 28 parts Acrylonitrile 12 parts Methacrylic acid 5 parts Divinylbenzene 2 parts Potassium persulfate 0.1 parts

After the polymerization conversion reached 95%, the monomer 1 was added.
Polymerization was terminated by adding 0.2 part of hydroxylamine sulfate per 00 parts. Subsequently, the residual monomer was recovered by steam distillation at 70 ° C. under reduced pressure, and copolymer No. 6
Obtained a latex. Polymerizations shown in Table 2 were carried out in the same manner to obtain latexes of copolymer Nos. 7 to 10. Further, in the example where the polymerization is carried out in three or more steps (Copolymer Nos. 7 and 10), up to the second step is the seed particle synthesis step. A part of the obtained latex of the copolymer was directly used for mixing with the component (a). For the remaining latices, in the case of Copolymer Nos. 6, 7, 9 and 10,
Polyoxyethylene nonyl phenyl ether (Kao Corporation, trade name Emulsion 92) was added to the obtained latex.
8) was added per 100 parts of the copolymer, and 1 part of alkylphenol was added as an antioxidant. Then, this latex was put in a pressure tube and heated to 110 ° C. to solidify the latex. The coagulated copolymer was in the form of fine particles, which were collected by filtration, part of which was only dehydrated, the mixture was directly used for mixing with the component (a), and the rest was vacuum dried at 50 ° C.

[0022]

[Table 2]

Regarding copolymer No. 8, after the polymerization was stopped, alkylphenol 1 was added as an antiaging agent.
Part, and the latex is put into a 1% aqueous solution of calcium chloride to salt out the copolymer, which is then washed.
It was dried. The average particle diameters of the copolymers in Tables 1 and 2 are the latex particles obtained by the above polymerization using a Coulter Submicro Particle Analyzer (Model N-4) manufactured by Nikkaki Co., Ltd. The average particle diameter of is measured. The gel content was 2 at room temperature when 1 g of the coagulated product of the copolymer obtained by the above coagulation and drying was put in 100 ml of methyl ethyl ketone.
The weight of the insoluble matter was measured after standing for 4 hours.

(3) Production of Fiber Reinforced Composite Material (3) -1 Dispersion of Copolymer (b) in Component (a) The copolymer (b) is prepared from the copolymer (b) by the following methods A to D. Dispersed in the components (abbreviated as modified epoxy composition). Method A: The latexes obtained in (1) and (2) are shown in Table 3.
And the ratios shown in Table 4 were added to the epoxy compound Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd., and 1 was added by a shear stirring mixer “Homo Disper” manufactured by Tokushu Kika Kogyo Co., Ltd.
Mix for 0 minutes. After standing, the separated water was removed, and the solidified layer was vacuum dried to obtain a modified epoxy composition. Method B: The amount of the copolymer coagulated product obtained in (1) shown in Table 3 was roughly dispersed in methyl ethyl ketone with stirring to give 4% by weight.
Of the dispersion liquid. The amount of Epicoat 82 shown in Table 3 was added to this.
After adding 8 and mixing with a homodisper for 10 minutes, the solvent was removed by vacuum drying and the modified epoxy composition was obtained. Method C: The amount of the copolymer solidified product obtained in (1) shown in Table 3 was put into Epicoat 828, and mixed for 90 minutes with a mixing and dispersing machine "Plastomill" manufactured by Toyo Seiki Co., Ltd. Then, defoaming was performed under reduced pressure to obtain a modified epoxy composition. Method D: The amount of the copolymer obtained in (2) shown in Table 4 before drying was added to Epicoat 828, and the mixture was stirred with a special mixer "Homomixer" manufactured by Tokushu Kika Kogyo Co., Ltd. After mixing for 30 minutes, water was removed by vacuum drying to obtain a modified epoxy composition.

(3) -2 Molding of Fiber Reinforced Composite Material The modified epoxy composition obtained by the method of (3) -1 was mixed with the curing agents shown in Tables 3 and 4, and the components (a) and (b) were used.
A composition (abbreviated as matrix resin) in which the components were mixed was obtained. In the case of Table 3, the matrix resin was heated to 100 ° C., and a glass fiber mat (WF23 manufactured by Nitto Boseki Co., Ltd.) was used.
0) was impregnated and cooled to obtain a prepreg. Then, pressing was performed at 150 ° C. for 1 hour to adjust the pressure so that the fiber volume content was 50%, and then curing was performed in an oven at 150 ° C. for 14 hours.

[0026]

[Table 3]

In the case of Table 4, the matrix resin is 120
Carbon fiber mat (Toray Co., Ltd., T-30
0) was impregnated and cooled to obtain a prepreg. Subsequently, pressing was performed at 180 ° C. for 1 hour to adjust the pressure so that the fiber volume content was 40%, and then curing was performed at 180 ° C. for 14 hours in an oven.

[0028]

[Table 4]

(4) Characteristic test of fiber reinforced composite material (4) -1 Impact test Using the composite material molded in (3) -2, JIS K-7
According to 110, an Izod impact test was conducted. At this time, the test shape is 63 mm in length, 12 mm in width, and 8 in thickness.
It was mm. The test was conducted without notches. (4) -2 Three-point bending test Using the composite material molded in (3) -2, JIS K-7
In accordance with No. 203, a bending test was conducted to measure bending strength and bending elastic modulus. At this time, the shape of the test piece was 80 mm in length, 10 mm in width, and 4 mm in thickness, the distance between fulcrums was 64 mm, and the test speed was 2 mm / min. (4) -3 Measurement of glass transition temperature of matrix resin Only the matrix resin was carved out from the composite material molded in (3) -2, and DSC (manufactured by Seiko Denshi Kogyo KK, S
DC220C). The heating rate at this time was 10 ° C./min.

[0030]

The fiber reinforced composite material of the present invention has high toughness without impairing the mechanical strength and thermal properties originally possessed by the fiber reinforced epoxy composite material, and is a sports leisure article. It is effectively used for aircraft parts, vehicle parts, etc.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukihiro Okubo 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A compound containing (a) an epoxy group,
A fiber-reinforced composite material comprising (b) a crosslinked rubber-like polymer and (c) a fiber.