Silicone rubber composition for mold making and silicone rubber mold

Abstract

To provide a silicone rubber composition for mold making that gives a repeatedly usable silicone rubber mold from which a replicated resin having a smooth surface with high glossiness can be obtained.SOLUTION: The silicone rubber composition for mold making contains, for example, (A) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule, (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, (C) silica having a BET specific surface area of 50 m2 / g or more, (D) a hydrosilylation reaction catalyst, and (E) a fatty acid metal salt. A metal in the fatty acid metal salt is one or more selected from Ca, Al, Zn, Zr, Fe, Co, Mn, Ba, Pb, Bi and Ni.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a silicone rubber composition for molding and a silicone rubber mold, and more specifically to an addition-curing silicone rubber composition and a silicone mold for molding (so-called female mold) obtained by curing the composition. [Background technology]

[0002] Using a silicone rubber mold as an inverted mother mold, filling it with liquid resin and hardening it to manufacture multiple products has been widely used in the past, from cultural assets and art and craft items to prototype models of industrial products such as electric and electronic parts and automobile parts. Therefore, this silicone rubber for molding is required to be resistant to deterioration, to be able to form elaborate replicas of complex shapes, and, depending on the part, to produce replicas with a smooth and glossy surface.

[0003] In the past, aiming to improve the releasability of the replication resin and the durability of the silicone rubber, Patent Document 1 reports a method of further treating the hydrophobic silica of the reinforcing material with silazane in order to reduce the interaction between the silica of the reinforcing material contained in the silicone rubber and the replication resin. Patent Document 2 reports a method of adding a diorganopolysiloxane that does not have a hydrosilylation reactive functional group to a silicone rubber composition. Patent Document 3 reports a method of blending a silicone rubber composition with a polyether-modified, alkyl-modified, higher fatty acid ester-modified, fluorine-modified or phenyl-modified silicone oil. However, these methods had problems in that the interface between the silicone rubber mold and the resin became rough as the resin was repeatedly replicated, resulting in a decrease in the gloss of the resin surface, and the modified silicone oil used as the release agent would adhere to the resin interface.

[0004] Meanwhile, Patent Document 4 reports that the durability of silicone rubber molds can be dramatically improved by adding an alkaline substance selected from alkali metal hydroxides, alkali metal oxides, alkali metal fatty acid salts, alkali metal alcoholates, and alkali metal siliconates. However, since alkali metal siliconates are expensive, it has become necessary to search for alternatives. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-70755 [Patent Document 2] Japanese Patent Application Publication No. 7-118534 [Patent Document 3] JP 2000-289034 A [Patent Document 4] Japanese Patent Application Publication No. 4-216864 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above circumstances, and has as its object to provide a silicone rubber composition for molding that can yield a replication resin with a smooth surface and high gloss, and that can provide a silicone rubber mold that can be used repeatedly, a silicone rubber mold, and a method for producing a resin replication product using this silicone rubber mold. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above problems, the inventors discovered that an addition-curing type silicone rubber composition containing a specific fatty acid metal salt provides a silicone rubber mold that can produce a replication resin with high gloss even with repeated use, and thus completed the present invention.

[0008] That is, the present invention provides 1. A silicone rubber composition for molding containing a fatty acid metal salt, wherein the metal in the fatty acid metal salt is one or more selected from the group consisting of Ca, Al, Zn, Zr, Fe, Co, Mn, Ba, Pb, Bi, and Ni; 2. (A) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in each molecule; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in each molecule; (C) BET specific surface area is 50m 2 / g or more of silica, (D) a hydrosilylation reaction catalyst, and (E) Fatty acid metal salt 2. The silicone rubber composition for molding according to claim 1, 3. The silicone rubber composition for molding according to 1 or 2, wherein the metal in the fatty acid metal salt is Zn, Zr or both. 4. The silicone rubber composition for molding according to any one of 1 to 3, wherein the fatty acid in the fatty acid metal salt is 2-ethylhexanoic acid. 5. A silicone rubber mold obtained by curing the silicone rubber composition for molding described in any one of 1 to 4. 6. A method for producing a resin replica using the silicone rubber mold described in 5. to provide. Effect of the Invention

[0009] The silicone rubber mold obtained by curing the silicone rubber composition for molding of the present invention is capable of producing a replica resin with high gloss even when used repeatedly, and is particularly useful as a molding material for urethane resins. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. In the present invention, the silicone rubber composition for molding refers to an uncured (liquid) composition that has fluidity in an uncured state, is brought into contact with the entire surface or a part of the surface of a master by a method such as casting or coating, and is cured in that state to form a mold (mother mold for molding) for use in duplication with resin or the like.

[0011] The silicone rubber composition for molding of the present invention contains a fatty acid metal salt, The silicone rubber composition for molding contains a metal in the fatty acid metal salt, which is one or more metals selected from the group consisting of Ca, Al, Zn, Zr, Fe, Co, Mn, Ba, Pb, Bi, and Ni.

[0012] The silicone rubber composition for molding of the present invention is (A) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in each molecule; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in each molecule; (C) BET specific surface area is 50m 2 / g or more of silica, (D) a hydrosilylation reaction catalyst, and (E) Fatty acid metal salt An addition-curing type silicone rubber composition for molding containing the above is preferred.

[0013] Each component will be described in detail below. [Component (A)] Component (A) is an organopolysiloxane that contains two or more alkenyl groups bonded to silicon atoms in each molecule. The molecular structure of component (A) may be, for example, linear, branched, or cyclic, with the main chain being composed of repeated diorganosiloxane units and with linear diorganopolysiloxanes in which both ends of the molecular chain are blocked with triorganosiloxy groups being preferred. When the molecular structure of the organopolysiloxane of component (A) is linear or branched, the position of the silicon atom to which the alkenyl group is bonded in the organopolysiloxane molecule may be either the end of the molecular chain or in the middle of the molecular chain, or may be either or both, but the end (one end or both ends) is preferred, and both ends are more preferred.

[0014] The number of alkenyl groups bonded to silicon atoms in each molecule of component (A) is 2 or more, but preferably 2-20, and more preferably 2-10.

[0015] The alkenyl group bonded to the silicon atom in component (A) typically has from 2 to 8 carbon atoms, and preferably has from 2 to 4 carbon atoms. Specific examples include vinyl, allyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl groups, with the vinyl group being preferred.

[0016] The groups bonded to silicon atoms in component (A) other than alkenyl groups are not particularly limited, but include monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; and aralkyl groups such as benzyl and phenethyl groups. In addition, some or all of the hydrogen atoms of these hydrocarbon groups may be substituted with halogen atoms such as fluorine, chlorine, bromine, etc., and specific examples thereof include halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups. Among these, an alkyl group having 1 to 3 carbon atoms is preferred, and a methyl group is more preferred.

[0017] The viscosity of component (A) at 25°C is preferably 100 to 500,000 mPa·s, more preferably 1,000 to 200,000 mPa·s, and even more preferably 3,000 to 100,000 mPa·s. If the viscosity is within this range, the resulting composition is easy to handle and the cured silicone rubber has good mechanical properties. The viscosity in the present invention is measured using a rotational viscometer.

[0018] Specific examples of organopolysiloxanes of component (A) include dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, and dimethylsiloxane-methylvinylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups. and mixtures of two or more of these organopolysiloxanes.

[0019] The component (A) is a compound represented by the formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2(CH2=CH)SiO 1 / 2 Siloxane units represented by the formula: SiO 4 / 2 Organopolysiloxanes consisting of siloxane units represented by the formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2(CH2=CH)SiO 1 / 2Siloxane units represented by the formula: CH3SiO 3 / 2 Alternatively, an organopolysiloxane resin that is solid at 25° C. may be used, such as an organopolysiloxane composed of siloxane units represented by the following formula:

[0020] The organopolysiloxane of component (A) may be used alone or in combination of two or more. It is preferable to use two or more types of component (A), and it is more preferable to use a linear diorganopolysiloxane in combination with an organopolysiloxane resin.

[0021] [(B) Component] Component (B) is an organohydrogenpolysiloxane having two or more (usually 2 to 300), preferably three or more (for example, about 3 to 150), and more preferably 3 to 100 hydrogen atoms bonded to silicon atoms (i.e., SiH groups) per molecule, and is used as a crosslinking agent that undergoes a crosslinking reaction with component (A).

[0022] An example of the component (B) is an organohydrogenpolysiloxane represented by the following average composition formula (1). (R 1 3SiO 1 / 2 ) s (H (3-a) R 1 a SiO 1 / 2 ) 2-s (HR 1 SiO 2 / 2 ) t (R 1 2SiO 2 / 2 ) u (1)

[0023] In formula (1), R 1 R each independently represents an unsubstituted or substituted monovalent hydrocarbon group. 1The monovalent hydrocarbon group is not particularly limited as long as it does not have an alkenyl group, and may be linear, branched, or cyclic, but is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, and even more preferably a monovalent hydrocarbon group having 1 to 5 carbon atoms. Specific examples thereof include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, and n-hexyl groups; cyclic alkyl groups such as cyclohexyl groups; aryl groups such as phenyl and tolyl groups; and aralkyl groups such as benzyl and phenylethyl groups. Note that some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine, chlorine, and bromine, or cyano groups, and specific examples of such groups include halogen-substituted hydrocarbon groups such as 3,3,3-trifluoropropyl groups; and cyano-substituted hydrocarbon groups such as 2-cyanoethyl groups. Among these, R 1 is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group.

[0024] a is 1 or 2. s is 0, 1 or 2, preferably 1 or 2. Where t and u are numbers that satisfy t>0, u≧0, and 2≦t+u≦100 and 0.05≦t / (t+u)≦1.0, t+u is preferably a number from 8 to 80, and t / (t+u) is preferably a number from 0.2 to 0.8. If the range is as described above, the (B) component can be prevented from volatilizing during curing, and the viscosity does not become too high, resulting in excellent workability.

[0025] Specific examples of the organohydrogenpolysiloxane of component (B) include methylhydrogenpolysiloxane terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymer terminally blocked with trimethylsiloxy groups, dimethylpolysiloxane terminally blocked with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer terminally blocked with dimethylhydrogensiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymer terminally blocked with dimethylhydrogensiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymer terminally blocked with dimethylhydrogensiloxy groups, methylphenylpolysiloxane terminally blocked with dimethylhydrogensiloxy groups, and mixtures of two or more of these organopolysiloxanes. More specifically, examples of the organohydrogenpolysiloxane include those represented by the following formula:

[0026] [ka] (In the formula, the siloxane units may be arranged in any order.)

[0027] The blend amount of the component (B) is preferably 0.1 to 200 parts by mass, and more preferably 0.3 to 50 parts by mass, per 100 parts by mass of the component (A). Furthermore, the number of hydrogen atoms bonded to silicon atoms in component (B) per alkenyl group in component (A) is preferably 0.4 to 4, and more preferably 0.8 to 3.

[0028] [(C) component] (C) component has a specific surface area of ​​50m2 by the BET method. 2 / g or more, preferably 50 to 500m 2 / g, more preferably 150 to 350 m 2 / g of silica, which is a component that imparts mechanical properties such as tensile strength, tear strength, and elongation at break to the cured product obtained from the silicone rubber composition of the present invention. Examples of silica include fumed silica, crystalline silica (quartz powder), precipitated silica, and silica whose surfaces have been subjected to hydrophobic treatment. These may be used alone or in combination of two or more.

[0029] Examples of such silica include hydrophilic silica such as fumed silica Aerosil 130, 200, 300 (manufactured by Nippon Aerosil Co., Ltd.), Cabosil MS-5, MS-7 (manufactured by Cabot Corporation), Rheorosil QS-102, 103 (manufactured by Tokuyama Corporation), and precipitated silica such as Tokusil US-F (manufactured by Tokuyama Corporation) and Nipsil LP (manufactured by Nippon Silica Industry Co., Ltd.). Examples of hydrophobic silica include fumed silica Aerosil R-812, R-812S, R-972, R-974 (manufactured by Nippon Aerosil Co., Ltd.), Rheorosil MT-10 (manufactured by Tokuyama Corporation), precipitated silica such as Nipsil SS series (manufactured by Nippon Silica Industry Co., Ltd.), and crystalline silica such as Crystallite (manufactured by Tatsumori Co., Ltd.) and MIN-U-SIL (manufactured by US Silica Company).

[0030] These silicas may be used as they are, but it is preferable to use those that have been surface-hydrophobized with a surface treatment agent in advance, or to add a surface treatment agent during kneading with component (A) to hydrophobize the silica surface before use. Examples of surface treatment agents include alkylalkoxysilanes, alkylhydroxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, low molecular weight polysiloxanes, titanate-based treatment agents, fatty acid esters, etc., and alkyldisilazanes are preferred, and hexamethyldisilazanes are more preferred. These surface treatment agents may be used alone, or two or more may be used simultaneously or at different times. The amount of the surface treatment agent used is preferably 0.5 to 50 parts by mass, more preferably 1 to 40 parts by mass, and even more preferably 2 to 30 parts by mass, relative to 100 parts by mass of silica. When the amount of the surface treatment agent used is within the above range, the surface treatment agent or its decomposition products do not remain in the composition, fluidity is obtained, and an increase in viscosity over time can be suppressed.

[0031] The blend amount of the component (C) is preferably 3 to 50 parts by mass, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the component (A), from the standpoints of handleability of the composition and mechanical strength of the cured product.

[0032] [(D) component] Component (D) is a hydrosilylation catalyst for promoting the hydrosilylation reaction between the alkenyl groups in component (A) and the SiH groups in component (B). Specific examples include platinum black, platinous chloride, chloroplatinic acid, reaction products of chloroplatinic acid and monohydric alcohols, complexes of chloroplatinic acid and olefins, vinylsiloxanes or acetylene compounds, platinum-based catalysts such as platinum bisacetoacetate; palladium-based catalysts such as tetrakis(triphenylphosphine)palladium and dichlorobis(triphenylphosphine)palladium; and rhodium-based catalysts such as chlorotris(triphenylphosphine)rhodium and tetrakis(triphenylphosphine)rhodium. Of these, platinum catalysts are preferred, and a complex of chloroplatinic acid and vinylsiloxane is preferred. The component (D) may use either a single type alone, or a combination of two or more types.

[0033] The amount of component (D) is not limited as long as it is an amount that promotes the curing (hydrosilylation) of the composition, and is preferably an amount in which the metal atoms in this component are in the range of 0.1 to 1,000 ppm by mass, more preferably 1 to 500 ppm, and even more preferably 3 to 100 ppm, relative to the total mass of each component of the composition. Within this range, the reaction rate of the addition reaction is appropriate.

[0034] [(E) component] Component (E) is a fatty acid metal salt that imparts mold release durability to the silicone rubber mold obtained from the silicone rubber composition for molding of the present invention, even with repeated use, and makes it possible to obtain a replication resin with a smooth surface and high gloss. Component (E) is generally known to have the following effects: promoting the hardening (drying) of the coating by accelerating oxidative polymerization, acting as an oxidation catalyst, and promoting the hardening of unsaturated polyesters by accelerating the decomposition (radicalization) of organic peroxides. It is presumed that this component accelerates the hardening of the resin at the interface between the resin to be replicated and the silicone molding material, preventing surface roughening of the rubber mold caused by the resin component impregnating the silicone rubber mold, and preventing a decrease in the gloss of the resin surface.

[0035] The metal in the fatty acid metal salt is one or more metals selected from Ca, Al, Zn, Zr, Fe, Co, Mn, Ba, Pb, Bi, and Ni. Zn or Zr is preferred because it causes little coloring when mixed with the silicone composition.

[0036] The type of fatty acid is not particularly limited, and may be either saturated or unsaturated fatty acid, and the structure of the hydrocarbon chain may be either linear or branched, but preferably has 30 or less carbon atoms, more preferably 4 to 26 carbon atoms. Specific examples thereof include caproic acid, caprylic acid, 2-ethylhexanoic acid (octylic acid), capric acid, lauric acid, myristic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, α-linolenic acid, arachidic acid, behenic acid, and lignoceric acid, and generally, 2-ethylhexanoate is preferred because it is commercially available in a form dissolved in toluene, xylene, cyclohexane, or mineral spirits. As the component (E), zinc bis(2-ethylhexanoate) and zirconium bis(2-ethylhexanoate) are more preferable.

[0037] The blend amount of component (E) is preferably from 0.1 to 1,000 ppm by mass, and more preferably from 1 to 300 ppm by mass, based on the combined mass of components (A) to (C). The component (E) may use either a single type alone, or a combination of two or more types.

[0038] [Other ingredients] In addition to the above components (A) to (E), the silicone rubber composition for molding of the present invention may contain other components, such as those exemplified below, as long as the object of the present invention is not impaired. Other components include reaction control agents, conductive agents such as iron oxide, carbon black, conductive zinc oxide, and metal powder; heat resistance agents such as titanium oxide and cerium oxide; internal release agents such as dimethyl silicone oil and dimethyl diphenyl silicone oil; adhesion imparting agents; thixotropy imparting agents; and colorants.

[0039] Specific examples of reaction inhibitors include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclohexanol, ethynylmethyldecylcarbinol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, and the like. These may be used alone or in combination of two or more. Among these, 1-ethynylcyclohexanol, ethynylmethyldecylcarbinol, 3-methyl-1-butyn-3-ol, and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane are preferred.

[0040] When a reaction inhibitor is used, the amount added is preferably 0.01 to 3.0 parts by mass, and more preferably 0.01 to 1.5 parts by mass, per 100 parts by mass of component (A).Within such a range, the reaction control effect is fully exerted.

[0041] The silicone rubber composition for molding of the present invention may be a one-part composition in which the components (A) to (E) and, if necessary, other components are mixed, or a two-part composition in which a first part consisting of the components (A), (C), (D), and (E) and, if necessary, other components, and a second part consisting of the components (A), (B), and, if necessary, other components are separately prepared, and the first part and the second part are mixed before use. There may be a component that is used in common in the first part and the second part. By forming the composition into such a two-part type, storage stability can be further ensured.

[0042] The silicone rubber composition for molding of the present invention is cast into a predetermined mold and cured to obtain a silicone rubber mold. In particular, casting using vacuum casting is preferable, and as for the curing conditions, curing proceeds even at room temperature (5 to 35°C), but curing can also be accelerated by heating, and this method is effective when mass productivity is to be improved. When heat curing is performed, it can usually be performed under conditions of a temperature of 40 to 60° C. for about 2 to 20 hours.

[0043] The silicone rubber mold obtained from the silicone rubber composition for molding of the present invention can be effectively used for molding resin replicas of epoxy resin, urethane resin, etc. When producing these resin replicas, conventionally known conditions may be used, and for example, a urethane resin replica can be obtained by heating and curing at a temperature of 50 to 100°C for 10 to 60 minutes. EXAMPLES

[0044] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the viscosity is a value measured by a rotational viscometer.

[0045] [Examples 1 to 5, Comparative Examples 1 to 3] The following components were mixed to prepare a silicone rubber composition. Specifically, 32 parts by mass of component (A-1), 8 parts by mass of component (A-3), 20 parts by mass of component (C-1), 4 parts by mass of hexamethyldisilazane, and 2 parts by mass of water were mixed at 25°C using a kneader for 1 hour, then the mixture was heated to 160°C and mixed for 4 hours, cooled to 25°C, and then 32 parts by mass of component (A-1) and 4 parts by mass of component (F-1) were added and mixed at 25°C for 1 hour using a kneader. Component (D-1) was added thereto so that the platinum content was 30 ppm relative to the entire composition, and the mixture was stirred and mixed at 25°C for 15 minutes to prepare a first agent. Furthermore, 6.4 parts by mass of the component (A-2), 3.5 parts by mass of the component (B-1), and 0.015 parts by mass of the component (G-1) were stirred and mixed for 15 minutes at 25° C. using a planetary mixer to prepare a second agent. The obtained first agent, second agent, component (E), and, if necessary, components (F-2) and (F-3) were mixed and stirred at 25°C for 15 minutes using a planetary mixer in the compounding ratios (parts by mass) shown in Table 1, and then degassed under reduced pressure at 25°C for 30 minutes to obtain a silicone rubber composition.

[0046] (A) Component: (A-1) Dimethylpolysiloxane with both molecular chain terminals capped with trivinylsilyl groups and a viscosity of 10,000 mPa s at 25°C (A-2) Dimethylpolysiloxane with both molecular chain ends capped with vinyldimethylsilyl groups and a viscosity of approximately 5,000 mPa s at 25°C (A-3)(CH3)3SiO 1 / 2 Unit 40 mol%, (CH3)2(CH2=CH)SiO 1 / 2 Organopolysiloxane resin consisting of 5 mol% of units and 55 mol% of SiO2 units

[0047] (B) Ingredients: (B-1) Methylhydrogenpolysiloxane represented by the following formula: [ka] (In the formula, the arrangement of the siloxane units is random or block.)

[0048] (C) Ingredients: (C-1) Surface treated with dimethyldichlorosilane, specific surface area 200m 2 / g Silica

[0049] (D) Ingredients: (D-1) Complex of chloroplatinic acid and divinyltetramethyldisiloxane

[0050] (E) Ingredients: (E-1) Mineral spirit solution of zinc bis(2-ethylhexanoate) (Zn content: 8% by mass, Hope Pharmaceutical Co., Ltd.) (E-2) Mineral spirit solution of zirconium bis(2-ethylhexanoate) (Zr content: 12% by mass; manufactured by Hope Pharmaceutical Co., Ltd.) (E'-3) 2-Ethylhexanoic acid

[0051] (F) Component: Release agent (F-1) Dimethylsilicone oil with both ends of the molecular chain blocked with trimethylsilyl groups (viscosity at 25°C: 30 mPa s) (F-2) Dimethyldiphenylsilicone oil with both ends of the molecular chain blocked with trimethylsilyl groups (10 mol % of the substituents bonded to silicon atoms are phenyl groups, viscosity at 25°C: 100 mPa s) (F-3) Dimethylsilicone oil with both ends of the molecular chain blocked with trimethylsilyl groups (viscosity at 25°C: 10,000 mPa s)

[0052] (G) Component: Reaction control agent (G-1) 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane

[0053] [Making a silicone rubber mold] A glass plate (5 x 5 cm, 0.5 cm thick) was placed in a PP container measuring 10 x 15 cm in length and width and 3 cm in depth, and the silicone rubber composition was poured to a thickness of approximately 2 cm, degassed under vacuum, and then cured for 16 hours in a dryer set at 40° C. The glass plate was then demolded and further cured for 8 hours in a dryer set at 60° C. to obtain a concave silicone rubber mold.

[0054] [Urethane resin duplication test] Liquid urethane resin (Hicast 3160A / 3160B=100 / 200; manufactured by H&K Corporation) was poured into the concave silicone rubber mold prepared above, and then heated and cured for 45 minutes in a dryer set at 65°C to produce a urethane resin replica. The obtained urethane resin replica was then removed from the silicone rubber mold, and this process was repeated. The gloss (%) of the surface that had been in contact with the silicone rubber mold for the urethane resin replicas demolded for the 1st, 20th, and 40th times was measured using a gloss meter (IG-320; Horiba, Ltd.) and the results are shown in Table 1.

[0055] [Table 1]

[0056] As shown in Table 1, it can be seen that the silicone rubber molds using the silicone rubber molding compositions of Examples 1 to 5 maintained the same surface gloss as the initial value even after repeated duplication of the urethane resin. On the other hand, in the silicone rubber molds prepared using the compositions of Comparative Examples 1 to 3, which did not contain a fatty acid metal salt, the surface glossiness decreased significantly with repeated duplication. When dimethyldiphenylsilicone oil and dimethylsilicone oil were added as release agents (Example 5), the initial gloss level decreased due to the influence of the bleeding oil, but compared to the example that did not contain a fatty acid metal salt (Comparative Example 2), the decrease in gloss level from the initial stage of replication was small, and durability was excellent.

Claims

1. A silicone rubber composition for molding containing a fatty acid metal salt, 1. A silicone rubber composition for molding, wherein the metal in the fatty acid metal salt is one or more selected from the group consisting of Ca, Al, Zn, Zr, Fe, Co, Mn, Ba, Pb, Bi, and Ni.

2. (A) an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in each molecule; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in each molecule; (C) BET specific surface area is 50 m 2 / g or more of silica, (D) a hydrosilylation reaction catalyst, and (E) Fatty acid metal salt The silicone rubber composition for molding according to claim 1, which comprises

3. 2. The silicone rubber composition for molding according to claim 1, wherein the metal in the fatty acid metal salt is Zn, Zr, or both.

4. 2. The silicone rubber composition for molding according to claim 1, wherein the fatty acid in the fatty acid metal salt is 2-ethylhexanoic acid.

5. 5. A silicone rubber mold obtained by curing the silicone rubber composition for molding according to any one of claims 1 to 4.

6. A method for producing a resin replica product using the silicone rubber mold according to claim 5.

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