JP2011231275A - Sheet molding compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deformation and generation of crack of a CSMC (Carbon SMC) molding, and to reduce the remaining amount of a styrene monomer in the molding.SOLUTION: The sheet molding compound includes a bisphenol A type vinyl ester resin, a styrene monomer, carbon fiber, and an organic peroxide, wherein the active oxygen concentration in the sheet molding compound is 9.0×10to 25.0×10wt.%. In addition, the subject is solved by using the sheet molding compound.

Description

  The present invention relates to a sheet molding compound (hereinafter abbreviated as “SMC”), a method for producing a molded product using the SMC, and a molded product obtained by the method.

  SMC is a compound that contains thermosetting resin, fiber reinforcement, curing agent, cross-linking agent, filler, etc., and is molded into automotive interior parts, housing-related parts, and household appliance housings. Can do. SMC molded products are used in a wide range of fields because of their excellent mechanical properties, moldability and design.

  However, since the styrene monomer used as a crosslinking agent in SMC remains in the molded product even after molding, its odor is a problem, and it is also known that it may cause sick house syndrome. For this reason, it is necessary to mold SMC at a high temperature to reduce the residual amount of styrene monomer. However, molding at high temperature may deform the molded product. In addition, cracks may occur in the molded product due to the difference in coefficient of linear expansion between the fiber reinforcement and the thermosetting resin.

  In addition, a method of annealing at a high temperature to reduce the residual amount of styrene monomer is also known, but this method requires a long time treatment at a high temperature, resulting in a decrease in productivity.

  Cited Document 1 includes blending styrene monomer and a curing agent into SMC at a specific ratio in order to reduce the amount of styrene monomer remaining in a molded article made of unsaturated polyester resin and the amount of styrene monomer released from the molded article. Is disclosed. Citation 2 discloses that a predetermined amount of a curing agent and a curing retarder are added to the SMC in order to reduce the rate at which volatile organic compounds are emitted from a molded article made of an unsaturated polyester resin.

JP 2006-131759 A JP 2008-127546 A

  When a bisphenol A type vinyl ester resin is blended with SMC as a thermosetting resin, the vinyl ester resin has low heat resistance, so that the molded product is deformed during high temperature molding and after demolding. Therefore, it is necessary to mold at a low temperature, but in that case, a large amount of styrene monomer remains in the molded product.

When carbon fiber is blended as a fiber reinforcement, carbon SMC (hereinafter abbreviated as “CSMC”) has an extremely high elastic modulus compared to SMC blended with glass fiber, so the thickness of the molded product can be reduced. . However, when the thickness is reduced, the amount of heat generation is extremely reduced and the after-curing effect is reduced, so that a large amount of styrene monomer remains in the molded product. Moreover, the linear expansion coefficient of the carbon fiber is −1 × 10 ⁻⁵ / K, and cracking may occur when molded at a high temperature.

  Accordingly, an object of the present invention is to suppress the deformation and cracking of a CSMC molded product and to reduce the residual amount of styrene monomer in the molded product.

  As a result of intensive investigations to solve the above problems, the present inventor has found that the above problems can be solved by causing the CSMC to have a predetermined concentration of active oxygen.

That is, the gist of the present invention is as follows.
(1) A sheet molding compound containing a bisphenol A-type vinyl ester resin, a styrene monomer, carbon fiber and an organic peroxide, wherein the active oxygen concentration in the sheet molding compound is 9.0 × 10 ^{−2 to} 25.0 × 10 ⁻² Said sheet molding compound which is weight%.
(2) A method for producing a sheet molding compound molded article, wherein the sheet molding compound according to (1) is molded at 125 to 145 ° C.
(3) The method according to (2), wherein the whole or part of the molded product has a thickness of 1 to 3 mm.
(4) A sheet molding compound molded product obtained by the method according to (2) or (3).

  According to the present invention, it is possible to suppress the deformation and cracking of a CSMC molded product and reduce the residual amount of styrene monomer in the molded product.

Thermosetting resin As the thermosetting resin in the present invention, a bisphenol A type vinyl ester resin is used. Here, the bisphenol A type vinyl ester resin is a resin having a reactive unsaturated group only at the terminal, which is obtained by adding an α, β-unsaturated carboxylic acid to a bisphenol A type epoxy resin.

  Examples of the bisphenol A type epoxy resin include PIC Corporation's EPICLON 840, EPICLON 840-S, EPICLON 850, EPICLON 850-S, EPICLON EXA-850CRP, EPICLON 850-LC, EPICLON 860, EPICLON 1050, EPICLON 1055, EPICLON 2050, EPICLON 3050, EPICLON 4050, EPICLON 7050, EPICLON HM-091, EPICLON HM-101 and the like can be mentioned.

  Examples of the α, β-unsaturated carboxylic acid include α, β-unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and cinnamic acid. Monoesters of α, β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid and chloromaleic acid can also be added to the bisphenol A type epoxy resin.

  The blending amount of the bisphenol A type vinyl ester resin in the present invention is preferably 30 to 70% by weight, particularly preferably 40 to 60% by weight, based on the weight of CSMC.

Styrene monomer The styrene monomer in the present invention is used as a crosslinking agent for crosslinking a bisphenol A type vinyl ester resin. The blending amount of the styrene monomer in the present invention is preferably 5 to 30% by weight, particularly preferably 10 to 25% by weight, based on the weight of CSMC.

  Since the styrene monomer remaining in the CSMC molded product causes sick house syndrome and the like, the smaller the remaining amount, the better. Therefore, the amount of the styrene monomer remaining in the CSMC molded product of the present invention is preferably 0.10% by weight or less, particularly preferably 0.05% by weight or less, based on the weight of the molded product.

Fiber Reinforcement Material The fiber reinforcement material of the present invention can be improved in mechanical properties by being added to the bisphenol A type vinyl ester resin. Since carbon fiber has a lower specific gravity than glass or metal and is excellent in heat resistance, strength and elastic modulus, carbon fiber is used as a fiber reinforcing material in the present invention.

  The length of the carbon fiber in the present invention is preferably 1/4 to 2 inches, particularly preferably 1/2 to 1 inch.

  The blending amount of the carbon fiber in the present invention is preferably 30 to 70% by weight, particularly preferably 40 to 60% by weight, based on the weight of CSMC.

  Glass fiber, polymer fiber, ceramic fiber, aramid fiber, polyarylate fiber, high strength vinylon fiber, high strength polyethylene fiber, polyester fiber, alumina fiber, silicon carbide fiber and boron fiber may be used in combination as optional components. In this case, the ratio of the optional component / carbon fiber is 50/50 weight ratio, preferably 30/70 weight ratio, so that the molded article obtained can exhibit high rigidity. Only carbon fiber is suitable if it meets the needs for light weight and high rigidity.

Organic peroxide The organic peroxide in the present invention can be used as a curing agent for a bisphenol A type vinyl ester resin. Further, the residual amount of styrene monomer in the CSMC molded product can be reduced by active oxygen derived from the organic peroxide. Since the active oxygen concentration depends on the amount of organic peroxide to be blended with CSMC, it is possible to obtain a desired active oxygen concentration by adjusting the amount of organic peroxide to be blended.

The active oxygen concentration in the present invention can be calculated by the following formula:
Active oxygen concentration (% by weight) = Active oxygen content of curing agent (%) (catalog value) x Curing agent amount (g) / CSMC amount (g)
Here, the active oxygen amount (%) of the curing agent can be determined by a generally known iodination method as described in Japanese Patent No. 4236994. Specifically, it can be obtained by dissolving an organic peroxide in chloroform, adding acetic acid, a saturated potassium iodide solution and methanol, and titrating with sodium thiosulfate. On the other hand, the catalog value means a value measured by an organic peroxide manufacturer and described in a product catalog.

  The organic peroxide that can be used in the present invention is not particularly limited, and various known organic peroxides can be used. For example, diisobutyryl peroxide, cumylperoxyneodecanoate, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-tetramethylbutylperoxy Neodecanoate, di (4-t-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxy Neoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy- 2-ethylhexanoate, succinyl peroxide, 2,5-dimethyl-2 , 5-di (2-ethyhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, t-butylperoxy-2-ethylhexanoate, di ( 3-methylbenzoyl) peroxide, dibenzoyl peroxide, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) cyclohexane, 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, t -Hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropylmonocarbonate, t- Tylperoxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-di- (t- Butylperoxy) butane, t-butylperoxybenzoate, n-butyl 4,4-di- (t-butylperoxy) valerate, di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, di-t-hexyl peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5 -Di (t-butylperoxy) hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxy And 2,3-dimethyl-2,3-diphenyl butane etc. can be used, molding temperatures can be used alone or in combination of two or more curing agents depending on the material life.

The active oxygen concentration in the CSMC of the present invention is 9.0 × 10 ^{−2 to} 25.0 × 10 ⁻² wt%, preferably 11.0 × 10 ^{−2 to} 24.0 × 10 ⁻² wt%, particularly preferably 13.5 based on the weight of CSMC. × 10 ^{−2 to} 22.5 × 10 ⁻² wt%.

Additives The CSMC of the present invention may contain various additives in addition to the above components. For example, a low shrinkage agent, a filler, an internal mold release agent, a polymerization inhibitor, a pigment, a thickener, a curing accelerator, a curing accelerator aid, and the like can be blended.

  The low shrinkage agent is a thermoplastic resin that is usually used to prevent cracking, dimensional stability and surface smoothness of molded products. For example, vinyl chloride, vinyl acetate, ethylene, propylene, methacrylic ester, acrylic Homopolymers or copolymers of acid esters and monomers such as styrene, polycaprolactone, cellulose acetate butyrate, cellulose acetate propionate, thermoplastic polyurethanes, saturated polyesters and vinyls such as styrene-butadiene. Examples thereof include a copolymer of a compound and an olefin. The low shrinkage agent can be used in an amount of 50 parts by weight or less, preferably 30 parts by weight or less based on 100 parts by weight of the thermosetting resin used in CSMC.

  As the filler, various fillers generally used in molding materials can be used. For example, calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, calcium sulfate, aluminum hydroxide, silica, clay, talc, Examples thereof include cinnabar, diatomaceous earth, mica powder, asbestos powder and glass powder, and these can be used alone or in combination of two or more. The filler can be used in an amount of 200 parts by weight or less, preferably 100 parts by weight or less based on 100 parts by weight of the thermosetting resin used in CSMC.

  As the internal mold release agent, internal mold release agents generally used in molding materials can be used, and examples thereof include stearic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, and carnauba wax. These can be used alone or in combination of two or more. The internal mold release agent is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the thermosetting resin used in CSMC.

  Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, p-toluquinone, 2,5-diphenyl-p-benzoquinone, 2,5-diacetoxy-p-benzoquinone, pt-butylcatechol, 2, 5-di-t-butylhydroquinone, di-t-butyl-p-cresol, hydroquinone monomethyl ether, 2,6-di-t-butyl-4-methylphenol, phenothiazine, and the like. More than one species can be used in combination. The polymerization inhibitor is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the thermosetting resin used in CSMC.

  The pigment is used for coloring a molded article, and various inorganic pigments and organic pigments that are usually used in molding materials can be used. The pigment should be used in an appropriate amount depending on the degree of coloring of the molded product, but the internal pigment is 30 parts by weight or less, preferably 15 parts by weight or less, based on 100 parts by weight of the thermosetting resin used in CSMC Can be used in

  As the thickener, polyisocyanates can be used in addition to oxides or hydroxides of divalent metals such as magnesium, calcium and zinc. Examples of the divalent metal oxide or hydroxide include magnesium oxide, calcium oxide, magnesium hydroxide, and calcium hydroxide. As the polyisocyanate, for example, polyisocyanates such as tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), and cyclohexane diisocyanate (CHDI) can be used. In addition, allophanate, burette and trimer forms of these polyisocyanate compounds can be used. A thickener is 0.1-30 weight part with respect to 100 weight part of thermosetting resins currently used for CSMC, Preferably it is 0.5-20 weight part.

  As a hardening accelerator, well-known metal soaps, such as cobalt naphthenate and cobalt octenoate, can be used, for example. The curing accelerator can be used in an amount of 0.5 parts by weight or less, preferably 0.1 parts by weight or less as a metal component with respect to 100 parts by weight of the thermosetting resin used in CSMC.

  As the curing accelerator, known amines are used, and examples thereof include dimethylaniline, diethylaniline, dimethylparatoluidine, triethanolamine, and acetylacetone. The curing accelerating aid can be used in an amount of 1 part by weight or less, preferably 0.5 parts by weight or less, based on 100 parts by weight of the thermosetting resin used in CSMC.

Production of CSMC The CSMC of the present invention composed of the above components can be produced by a usual method using a usual CSMC production apparatus. For example, a CSMC raw material containing each component other than carbon fiber in a predetermined ratio is applied to a carrier film installed on the top and bottom so as to have a uniform thickness, and the carbon fiber cut into a predetermined length is It is sandwiched between the CSMC raw materials applied on the carrier film installed above and below, and then the whole is passed between impregnating rolls, and the carbon fibers are impregnated with the CSMC raw materials by applying pressure, and then wound into a roll. Or it can be folded into spells to obtain CSMC. This is followed by aging as necessary. When a thickener is blended, it is preferable to ripen by heating to a temperature of room temperature to 60 ° C. A polyethylene film, a polypropylene film, etc. can be used as a carrier film.

Production of CSMC molded product The CSMC molding method of the present invention is not particularly limited, and various known molding methods can be used. For example, a compression molding method, a transfer molding method, or the like can be used.

  Since the bisphenol A-type vinyl ester resin used in the present invention has low heat resistance, the molded product is deformed when molded at a high temperature. Furthermore, when carbon fibers are used, cracks may occur when molded at high temperatures. Therefore, the molding of CSMC in the present invention is performed at 125 ° C to 145 ° C, preferably 130 ° C to 140 ° C, particularly preferably 130 ° C to 135 ° C.

  In the present invention, the molding of CSMC can be performed at a pressure of 3 to 20 MPa, preferably 5 to 18 MPa, particularly preferably 7 to 15 MPa.

  If the thickness of the molded product is reduced, the calorific value is drastically reduced, and the after-curing effect is reduced, so that a large amount of styrene monomer remains in the molded product. The residual amount of styrene monomer can be reduced by setting the concentration of. Therefore, in the molding in the present invention, the thickness of all or part of the molded product can be set to 1 to 3 mm, preferably 1.5 to 2.5 mm.

  The smaller the amount of styrene monomer remaining in the CSMC molded product, the better. Therefore, the styrene monomer content in the CSMC molded product of the present invention is preferably 0.10% by weight or less, particularly preferably 0.05% by weight or less, based on the weight of the molded product.

  The CSMC molded product of the present invention can be used in various fields, and can be used as, for example, automobile interior parts, housing-related members, and housings for home appliances.

Production of CSMC Showa Polymer Co., Ltd. Lipoxy R-804 equivalent product (styrene monomer dissolved product, styrene monomer content 45 wt%) 100 parts by weight of bisphenol A type vinyl ester resin, NOF organic peroxide Perbutyl Z 1.5 to 10.5 parts by weight (active oxygen concentration in CSMC 4.5 x 10 ^{-2 to} 31.5 x 10 ^-2 wt%) is added, and carbon fiber equivalent to T-700SC made by Toray Industries, Inc. is 50 wt%. CSMC adjusted to be obtained.

Preparation of flat molded product for evaluation of residual styrene monomer
Using a 320 mm × 220 mm flat plate mold, the amount of CSMC used was adjusted so that the thickness of the molded product was 2 mm, and a flat molded product for residual styrene monomer evaluation was obtained by a compression molding method. The molding conditions of the flat plate molded product were a molding temperature of 130 ° C. and 140 ° C., a molding pressure of 15 MPa, and a holding time of 500 seconds.

Evaluation of amount of residual styrene monomer contained in molded product About 1 g of sample was scraped from the obtained flat plate molded product and immersed in about 9 g of N, N-dimethylformamide, and the residual styrene monomer contained in the sample Extracted. Thereafter, the weight of the residual styrene monomer contained in the solution was determined using gas chromatography and converted to the amount of residual styrene monomer in the molded product.

Claims (4)

A sheet molding compound containing bisphenol A type vinyl ester resin, styrene monomer, carbon fiber and organic peroxide, wherein the active oxygen concentration in the sheet molding compound is 9.0 × 10 ^{−2 to} 25.0 × 10 ⁻² wt% There is a certain sheet molding compound.   A method for producing a sheet molding compound molded article, wherein the sheet molding compound according to claim 1 is molded at 125 to 145 ° C.   The method according to claim 2, wherein the whole or part of the molded article has a thickness of 1 to 3 mm.   A sheet molding compound molded article obtained by the method according to claim 2 or 3.