TW202108700A - Silicone rubber composition for molding and silicone rubber mold - Google Patents

Abstract

The invention relates to a silicone rubber composition for mold manufacturing and a silicone rubber mold. Provided is a silicone rubber composition for imparting a reusable silicone rubber mold havingexcellent heat resistance, comprising: a silicone rubber composition for imparting a silicone rubber mold having excellent heat resistance; (A) organopolysiloxane (1) Vi(3-a)R1aSiO(R12SiO)mSiR1aVi(3-a) (1) (wherein R1 is a monovalent hydrocarbon group not containing an alkenyl group, Vi is a vinyl group, m is a number having a viscosity of 10,000-200,000 mPa*s, and a is 0-2); (B) organopolysiloxane (2) (R13SiO1/2)p(Vi(3-b)R1bSiO1/2)q(SiO4/2)r (2) (R1, Vi are the same as described above, p, q and r meet the conditions that p is greater than 0, q is greater than 0, r is greater than 0,and p + q + r = 1; b is 0-2); (C) silica having a BET specific surface area of 50 m2/g or more; (D) organohydrogenpolysiloxane (3) (R13SiO1/2)s(H(3-c)R1bSiO1/2)2-s(HR11SiO2/2)t(R12SiO2/2)u (3) (R1 is the same as described above, c is 1 or 2, s is 0-2, t and u satisfy the conditions: t > 0, u ≥ 0, 2 ≤ t + u ≤ 100, 0.05 ≤ t/(t + u) ≤ 1.0; and (E) a hydrosilylation reaction catalyst.

Description

Silicone rubber composition for molding and silicone rubber mold

The present invention relates to a silicone rubber composition for molding and a silicone rubber mold. More specifically, it relates to an addition-hardening type silicone rubber composition for molding and a silicone molding master mold formed by hardening the same (Also and female model).

The silicone rubber mold is used as a reversal master mold, filled with resin and hardened to produce multiple products. From interesting mini-models to industrial prototype models, it has been widely used. The silicone rubber used in these is liquid before curing, and can be easily cured by mixing with a curing agent at room temperature or heating, and has the advantage of being a reversal mold. However, on the contrary, because it is rubber, the injected resin adheres to the rubber mold, and there is a problem that it is not easy to demold. As a solution strategy, a mold release agent is generally used, but it has become a problem to shorten the time on the step.

As a means to solve this problem, Patent Document 1 proposes to add a non-crosslinkable polysiloxane polymer having a chain length greater than that of the crosslinked base polymer to improve the release performance. However, with this method, when nylon and other resins with high heat distortion temperature are repeatedly molded by vacuum injection molding by injection molding, etc., the tear strength of the reversal master mold is reduced and it becomes difficult to demold. The problem of flaws such as cracks caused by the mold. As a countermeasure, Patent Document 2 proposes a method of adding fine ceramics such as lithium titanate to the composition, but the effect is not necessarily sufficient. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 7-118534 [Patent Document 2] JP 2016-165802 A

[The problem to be solved by the invention]

The present invention was completed in view of the above circumstances, and its object is to provide a silicone rubber composition for molding that can impart a polysilicone rubber mold with excellent heat resistance and reusability, and a silicone rubber composition using the molding silicone rubber composition Manufacturing method of resin replicas. [Means to solve the problem]

The inventors of the present invention have actively studied to solve the above-mentioned problems, and found that a specific addition-curing silicone rubber composition can provide a silicone rubber mold with excellent heat resistance and reusability, thus completing the present invention.

That is, the present invention provides 1. A silicone rubber composition for molding, characterized by containing: (A) Organopolysiloxane represented by the following average formula (1): 100 parts by mass of Vi _(3-a) R ¹ _a SiO(R ¹ ₂ SiO) _m SiR ¹ _a Vi _(3-a) (1) (In the formula, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group without alkenyl group, Vi represents a vinyl group , M is the number where the viscosity of component (A) becomes 10,000~200,000 mPa·s at 25℃, and a is the number from 0 to 2) (B) Organopolysiloxane represented by the following average formula (2): 5~100 parts by mass (R ¹ ₃ SiO _1/2 ) _p (Vi _(3-b) R ¹ _b SiO _1/2 ) _q (SiO _4/2 ) _r (2) (where R ¹ and Vi represent Same meaning as above, p, q and r satisfy p>0, q>0, r>0, p+q+r=1, b is a number of 0~2), (C) use BET method Silicon oxide with a specific surface area of 50m ² /g or more: 3~50 parts by mass (D) Organohydrogen polysiloxane expressed by the following average formula (3): 0.1~200 parts by mass (R ¹ ₃ SiO _1/2 ) _s (H _(3-c) R ¹ _b SiO _1/2 ) _2-s (HR ¹ ₁ SiO _2/2 ) _t (R ¹ ₂ SiO _2/2 ) _u (3) (where R ¹ represents Same meaning as above, c is 1 or 2, s is the number of 0~2, t and u satisfy t>0, u≧0, and 2≦t+u≦100 and 0.05≦t/(t+u )≦1.0), and (E) Hydrosilylation reaction catalyst. 2. The polysilicone rubber composition for molding as in 1, wherein in the aforementioned component (A), a is a number from 0 to 1.8. 3. The silicone rubber composition for molding as described in 1 or 2, wherein the viscosity of the aforementioned component (A) at 25°C is 20,000-150,000 mPa·s. 4. The silicone rubber composition for molding according to any one of 1 to 3, wherein the specific surface area of the aforementioned component (C) is 150 m ² /g or more. 5. The molding silicone rubber composition of any one of 1 to 4, wherein in the aforementioned (D) component, t and u satisfy t>0, u>0, and 2≦t+u≦70, respectively And 0.2≦t/(t+u)≦0.5. 6. A molding agent, which is made of the silicone rubber composition for molding as described in any one of 1 to 5. 7. A silicone rubber mold, which is made by hardening the silicone rubber composition for molding as described in any one of 1 to 5. 8. A method for manufacturing resin replicas, which uses silicone rubber molds such as 7. [Effects of the invention]

The silicone rubber mold obtained by curing the silicone rubber composition for molding of the present invention has excellent heat resistance, and is particularly useful as a molding material for resins having a high curing temperature such as nylon.

Hereinafter, the present invention will be described in detail. In addition, in the present invention, the so-called silicone rubber composition for molding means that it has fluidity in an uncured state, and is contacted with all or part of the surface of the original mold by injection molding or coating, and cured in this state. The uncured (liquid) composition is formed into a mold (master mold for film formation) that is replicated by resin or the like.

The silicone rubber composition for molding of the present invention contains the following components (A) to (E). _{(A) Organopolysiloxane Vi (3-a)} R ¹ _a SiO(R ¹ ₂ SiO) _m SiR ¹ _a Vi _(3-a) represented by the following average formula (1) (1) (where, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group without alkenyl group, Vi represents a vinyl group, m is the viscosity of component (A) at 25°C, which is a number of 10,000~200,000 mPa·s, and a is 0 ~2) (B) Organopolysiloxane (R ¹ ₃ SiO _1/2 ) _p (Vi _(3-b) R ¹ _b SiO _1/2 ) _q (SiO _4/2 ) _r (2) (In the formula, R ¹ and Vi represent the same meaning as the above, p, q and r satisfy p>0, q>0, r>0, p+q+r=1 The number, b is a number from 0 to 2), (C) ^{Silicon oxide with a specific surface area of 50m 2 /g or more by the BET method (D) Organohydrogen polysiloxane (R 1} ) represented by the following average formula (3) ₃ SiO _1/2 ) _s (H _(3-c) R ¹ _b SiO _1/2 ) _2-s (HR ¹ ₁ SiO _2/2 ) _t (R ¹ ₂ SiO _2/2 ) _u (3) (Eq. Among them, R ¹ means the same meaning as above, c is 1 or 2, s is a number from 0 to 2, t and u satisfy t>0, u≧0, and 2≦t+u≦100 and 0.05≦t. /(t+u)≦1.0), and (E) Hydrosilylation reaction catalyst.

[1] Component (A) The component (A) is an organopolysiloxane represented by the following average formula (1). Vi _(3-a) R ¹ _a SiO(R ¹ ₂ SiO) _m SiR ¹ _a Vi _(3-a) (1)

In the formula (1), R ¹ each independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and Vi represents a vinyl group. The monovalent hydrocarbon group as R ¹ is not particularly limited as long as it does not contain an alkenyl group. It may be any one of linear, branched, or cyclic, but is preferably a monovalent hydrocarbon group with 1 to 20 carbon atoms, more preferably It is a monovalent hydrocarbon group with 1 to 10 carbon atoms, and more preferably a monovalent hydrocarbon group with 1 to 5 carbon atoms. Specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl, and n-hexyl; cyclic alkyl groups such as cyclohexyl; Aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl and phenylethyl. In addition, part or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as F, Cl, and Br, cyano groups, etc. As specific examples of these groups, 3,3,3-trifluoropropyl Halogen substituted hydrocarbyl groups such as, etc.; Cyano substituted hydrocarbyl groups such as 2-cyanoethyl group, etc. Among these, R ^{1 is} preferably a methyl group.

Based on the rational point of view of the silicone rubber composition for molding of the present invention and the point of view of the tear strength and heat resistance of the resulting cured product, the viscosity of component (A) at 25°C is 10,000~200,000 mPa·s, Preferably it is 25,000 to 150,000 mPa·s. However, m in the formula (1) is a number where the viscosity of the component (A) at 25° C. becomes 10,000 to 200,000 mPa·s, but is preferably a number of 200 to 1,300. In addition, the viscosity in the present invention is the measured value using a rotary viscometer. In addition, a in formula (1) is a number of 0 to 2, preferably a number of 0 to 1.8.

As a specific example of (A) component, the organopolysiloxane etc. which are represented by the following average formula are mentioned. Vi ₃ SiO(Me ₂ SiO) ₂₅₀ SiVi ₃ Vi ₃ SiO(Me ₂ SiO) ₇₅₀ SiVi ₃ Vi ₃ SiO(Me ₂ SiO) ₁₀₀₀ SiVi _{3 ViMe 2} SiO(Me ₂ SiO) ₂₅₀ SiMe ₂ Vi ViMe ₂ SiO(Me ₂ SiO) ₇₅₀ SiMe ₂ Vi ViMe ₂ SiO(Me ₂ SiO) ₁₀₀₀ SiMe ₂ Vi (in the formula, Vi means vinyl and Me means methyl (the same hereinafter)).

Moreover, (A) component may be used individually by 1 type, and may use 2 or more types together.

[2] (B) component (B) component is an organopolysiloxane represented by the following average formula (2). (R ¹ ₃ SiO _1/2 ) _p (Vi _(3-b) R ¹ _b SiO _1/2 ) _q (SiO _4/2 ) _r (2)

In the formula (2), R ¹ has the same meaning as in the above formula (1), and its specific examples are also the same as those exemplified above. In this case, it is also preferably a methyl group. p, q, and r are numbers satisfying p>0, q>0, r>0, p+q+r=1, but based on the viewpoint of the mechanical properties of the obtained hardened product, the organopolysiloxane of component (B) In the alkane, the ratio (p+q)/r of the M unit to the Q unit is preferably 0.3 to 2.0, more preferably 0.4 to 1.0. b is a number from 0 to 2.

(B) The molecular weight of the component is not particularly limited, but based on the compatibility with other components and the mechanical properties of the resulting hardened product, it is preferably 1,000 to 50,000, more preferably 2,000 to 10,000. In addition, the molecular weight is the weight average molecular weight in terms of standard polystyrene in gel permeation chromatography (GPC).

As a specific example of (B) component, the organopolysiloxane etc. which are represented by the following formula are mentioned. (Me ₃ SiO _1/2 ) _0.4 (ViMe ₂ SiO _1/2 ) _0.045 (SiO _4/2 ) _0.555 、 (Me ₃ SiO _1/2 ) _0.1 (Vi ₃ SiO _1/2 ) _0.2 (SiO _4/2 ) _0.7 , (Me ₃ SiO _1/2 ) _0.35 (ViMe ₂ SiO _1/2 ) _0.2 (Vi ₃ SiO _1/2 ) _0.1 (SiO _4/2 ) _0.35

The compounding amount of (B) component is 5-100 mass parts with respect to 100 mass parts of (A) component, Preferably it is 10-50 mass parts. (B) If the blending amount of the component is less than 5 parts by mass, the mechanical properties of the resulting hardened product will be insufficient, and if it exceeds 100 parts by mass, the viscosity of the composition will increase, making it difficult to mold. In addition, since the component (B) may become a solid at 25°C, it can also be dissolved in the component (A) and used. Moreover, (B) component may be used individually by 1 type, and may use 2 or more types together.

[3] (C) component (C) component is silica with a specific surface area of 50m ² /g or more by BET method, preferably 50~500 m ² /g, more preferably 150~350m ² /g, used for The cured product obtained from the silicone rubber composition of the present invention is a component that imparts tensile strength, tear strength, and mechanical properties during elongation during cutting. Examples of silica include fuming silica, crystalline silica (quartz powder), sedimentation silica, and silica whose surface has been hydrophobized. These can be used alone or in combination of two. Used above.

Examples of these silicas include Aerosil 130, 200, 300 (manufactured by Japan Aerosil Corporation), Cabosil MS-5, MS-7 (manufactured by Cabot Corporation), Rheorosil QS-102, 103 (TOKUYAMA ( Fuming silica made by Tokusil US-F (manufactured by TOKUYAMA Co., Ltd.), Nipsil LP (manufactured by Nippon Silica Industries Co., Ltd.), etc., as hydrophobic silica, for example: Aerosil R-812, R-812S, R-972, R-974 (manufactured by Aerosil Co., Ltd.), Rheorosil MT-10 (manufactured by TOKUYAMA Co., Ltd.) and other fuming silica; Nipsil SS series (SILICA Industries, Japan) Sedimentary silica such as Crystalite (manufactured by Ronson Co., Ltd.), MIN-U-SIL (manufactured by US Silica Company), Imisil (manufactured by Illinois Mineral Company), etc.

It does not matter if the silica is used directly, but it is preferable to use a surface treatment agent that has been previously hydrophobized, or a surface treatment agent is added during the mixing of component (A) to hydrophobize the surface of the silica. Examples of surface treatment agents include alkyl alkoxy silanes, alkyl hydroxy silanes, alkyl chlorosilanes, alkyl silazanes, silane coupling agents, low-molecular polysiloxanes, titanate-based treatment agents, and fatty acids The ester and the like are preferably alkylsilazane, more preferably hexamethyldisilazane. These surface treatment agents can be used singly, or two or more of them can be used at the same time or at different times. The usage amount of the surface treatment agent is preferably 0.5-50 parts by mass, more preferably 1-40 parts by mass, and still more preferably 2-30 parts by mass relative to 100 parts by mass of silica. If the usage amount of the surface treatment agent is within the above range, the surface treatment agent or its decomposition products will not remain in the composition, fluidity can be obtained, and the viscosity increase over time can be suppressed.

(C) The compounding amount of the component is 3-50 parts by mass, preferably 5-30 parts by mass relative to 100 parts by mass of the component (A), based on the rationality of the composition and the mechanical strength of the hardened product. (C) If the blending amount of the component is less than 3 parts by mass, the mechanical properties of the resulting hardened product will be insufficient, and if it exceeds 50 parts by mass, the viscosity of the composition will increase, making it difficult to mold.

[4] Component (D) The component (D) is an organohydrogenpolysiloxane represented by the following average formula (3). (R ¹ ₃ SiO _1/2 ) _s (H _(3-c) R ¹ _b SiO _1/2 ) _2-s (HR ¹ ₁ SiO _2/2 ) _t (R ¹ ₂ SiO _2/2 ) _u (3 )

In the formula (3), R ¹ has the same meaning as in the above formula (1), and its specific examples are also the same as the groups exemplified above. In this case, it is also preferably a methyl group. c is 1 or 2, and s is a number from 0 to 2. t and u are numbers satisfying t>0, u≧0, and 2≦t+u≦100 and 0.05≦t/(t+u)≦1.0, but t+u is preferably 8~80, t/ (t+u) is preferably 0.2 to 0.8. When t+u is less than 2, the component (D) may volatilize during curing, and when it exceeds 100, the viscosity of the component (D) increases and workability deteriorates. If t/(t+u) is less than 0.05, the rubber properties of the cured product obtained are insufficient.

(D) The molecular weight of the component is not particularly limited, but in consideration of improving the workability of the composition and the mechanical properties of the hardened product, it is preferably 1,000 to 30,000, more preferably 1,500 to 10,000.

As a specific example of the organohydrogenpolysiloxane of component (D), trimethylsiloxy group-terminated methylhydrogenpolysiloxane at both ends of the molecular chain and trimethylsiloxy group-terminated at both ends of the molecular chain Dimethylsiloxane-terminated, methylhydrosiloxane copolymer, trimethylsiloxy-terminated dimethylpolysiloxane, methylhydrosiloxane, methylphenylsiloxane at both ends of the molecular chain Alkyl copolymers, dimethylhydrosiloxy-terminated dimethylpolysiloxane at both ends of the molecular chain, dimethylhydrosiloxy-terminated dimethylpolysiloxane at both ends of the molecular chain, methylhydrosiloxane Alkyl copolymers, dimethylhydrosiloxy-terminated dimethylsiloxane and methylphenylsiloxane copolymers at both ends of the molecular chain, dimethylhydrosiloxy-terminated methylbenzene at both ends of the molecular chain Base polysiloxanes, mixtures of two or more of these organopolysiloxanes, etc. More specifically, the organohydrogen polysiloxane represented by the following formula is exemplified.

(式中，矽氧烷單位之排列為任意)。

(In the formula, the arrangement of siloxane units is arbitrary).

(D) The compounding quantity of component is 0.1-200 mass parts with respect to 100 mass parts of (A) components, Preferably it is 0.3-50 mass parts. (D) If the blending amount of the component is less than 0.1 parts by mass, the crosslinking will be insufficient, and if it exceeds 200 parts by mass, it is easy to cause foaming due to hydrogen generation during curing, and the rubber strength is reduced due to the occurrence of voids in the cured product. . In addition, the number of hydrogen atoms bonded to silicon atoms in the (D) component per vinyl group in the (A) component and (B) component is preferably 0.4 to 4, and more preferably 0.8 to 3. Moreover, (D)component may be used individually by 1 type, and may use 2 or more types together.

[5] (E) Ingredient The (E) component is a hydrosilylation reaction catalyst for promoting the hydrosilylation reaction of the vinyl group in the (A) component and the SiH group in the (B) component. Specific examples include platinum black, platinum chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and monohydric alcohol, complexes of chloroplatinic acid and olefins, platinum diacetyl acetate, etc. Platinum-based catalysts, palladium-based catalysts such as tetrakis(triphenylphosphine) palladium, dichlorobis(triphenylphosphine) palladium, etc., rhodium-based catalysts such as chlorotris(triphenylphosphine) rhodium, tetrakis(triphenylphosphine) rhodium, etc. Catalysts, etc. Moreover, (E) component may be used individually by 1 type, and may use 2 or more types together.

(E) The compounding amount of the component is not particularly limited if it can promote the hardening (hydrosilylation reaction) of the composition. The total mass of each component of the composition is based on the metal atom in the composition. The mass conversion is more preferably in the range of 0.1 to 1,000 ppm, more preferably in the range of 1 to 500 ppm, and still more preferably in the range of 3 to 100 ppm. If it is this range, the reaction rate of an addition reaction will become appropriate.

[6] (F) Ingredient The silicone rubber composition for molding of the present invention is based on the purpose of controlling the reactivity of the hydrosilylation reaction catalyst so as not to cause thickening or gelation during the preparation of the composition or before the heating and curing during molding. , (F) reaction control agent can also be added as needed. Specific examples of the reaction control agent are 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyne- 3-alcohol, 1-ethynylcyclohexanol, ethynylmethyldecylcarbitol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethyl Silyloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, double (2,2-Dimethyl-3-butynyloxy) dimethyl silane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl cyclotetrasiloxane, 1,1,3,3-Tetramethyl-1,3-divinyldisiloxane, etc., these can be used alone or in combination of two or more. Among them, preferred are 1-ethynylcyclohexanol, ethynylmethyldecylcarbitol, and 3-methyl-1-butyn-3-ol.

When using the (F) component, the addition amount is preferably 0.01 to 3.0 parts by mass, more preferably 0.01 to 1.5 parts by mass relative to 100 parts by mass of the total of (A) and (B) components. If it is within this range, the reaction control effect can be fully exhibited.

[7] Other ingredients In the silicone rubber composition for molding of the present invention, in addition to the above-mentioned (A) to (F) components, other components exemplified below may be blended as long as the purpose of the present invention is not impaired. As other ingredients, for example, conductive agents such as iron oxide, carbon black, conductive zinc white, metal powder, etc.; heat-resistant agents such as titanium oxide and cerium oxide; internal mold release agents such as dimethyl silicone oil; Agent; thixotropy imparting agent; coloring agent, etc.

Specific examples of colorants include inorganic pigments such as ultramarine blue, iron oxide, titanium oxide, titanium yellow, carbon black, zinc white, chrome green, etc.; anthraquinone violet, anthraquinone blue, indanthrene blue, alizarin green, Organic pigments such as Pisone Red; metal powder pigments such as aluminum powder, copper powder, bronze powder, tin powder, etc.; light-storing pigments, and dyes that do not hinder hardening, etc., can be appropriately selected in consideration of hue and chroma.

The silicone rubber composition for molding of the present invention can be mixed by conventional methods such as kneaders, planetary mixers, etc., by mixing the above-mentioned (A) to (E) components, the (F) components used as needed, and other components. And modulation. The silicone rubber composition for molding of the present invention can also be prepared as a first agent composed of (A) component, (B) component, (C) component, (E) component, and other components as needed. A two-part composition consisting of (A) component, (D) component, (C) component, and other components as needed, mixed with the first part and the second part before use. In addition, it may have a component commonly used for the first agent and the second agent. By setting the composition into these two dosage forms, storage stability can be further ensured.

The silicone rubber composition for molding of the present invention is injection molded with a specific mold, and a silicone rubber mold can be obtained by hardening. In particular, it is better to use vacuum injection molding for injection molding. As a curing condition, for example, curing at room temperature (5~35℃) can also be performed, but it can also be accelerated by heating. This method is effective when you want to improve mass production. . When heating and hardening, it can usually be carried out at a temperature of 40~60℃ for about 2~20 hours.

The silicone rubber mold obtained from the silicone rubber composition for molding of the present invention can be effectively used for molding resin moldings such as nylon resin, epoxy resin, and urethane resin. It is especially suitable for the molding of nylon resin that requires a heat distortion temperature of 50~200℃, preferably 70~180℃ in melting. [Example]

Examples and comparative examples are given below to describe the present invention in more detail, but the present invention is not limited to these examples.

[Examples 1 to 4, Comparative Example 1] The following components were mixed at the compounding ratio (parts by mass) shown in Table 1 to prepare a silicone rubber composition. Specifically, first use a kneader to mix (A) component, (B) component, (C) component, 1.5 parts by mass of hexamethyldisilazane, and 0.7 parts by mass of water at 25°C for 1 hour, and then raise the temperature to 150 ℃, keep stirring for 2 hours, and cool to 25℃. To the obtained silicone rubber base, add the component (E) so that it becomes 100ppm relative to the whole composition using platinum mass conversion, and use a planetary mixer at 25℃ After stirring and mixing for 15 minutes, the component (D) and the component (F) were added, stirred and mixed using a planetary mixer at 25°C for 15 minutes, and then degassed under reduced pressure at 25°C for 30 minutes to obtain a silicone rubber composition.

[Comparative Example 2] Except that the component (B) was not used, a silicone rubber composition was obtained in the same manner as in Example 1.

[Comparative Example 3] Except that the component (C), hexamethyldisilazane, and water were not used, a silicone rubber composition was obtained in the same manner as in Example 1.

(A) Ingredients: (A-1) Dimethyl polysiloxane with a viscosity of 100,000 mPa·s at 25°C terminated by trivinylsilyl groups at both ends (A-2) Dimethylpolysiloxane with a viscosity of 50,000mPa·s at 25°C terminated by dimethylvinylsilyl groups at both ends (A-3) Dimethyl polysiloxane with a viscosity of 60,000 mPa·s at 25°C terminated by trivinylsilyl groups at both ends (A-4: Comparative Example) Dimethylpolysiloxane with a viscosity of 5,000 mPa·s at 25°C with both ends capped with dimethylvinylsilyl groups

(B) Ingredients: (B-1) _{Organopolysiloxane expressed as (Me 3} SiO _1/2 ) _0.4 (ViMe ₂ SiO _1/2 ) _0.045 (SiO _4/2 ) 0.555 (weight average molecular weight 3,500)

(C) Ingredient: (C-1) Fuming silica (manufactured by Japan Aerosil Co., Ltd., Aerosil R976, BET specific surface area 240m ² /g)

(D) Ingredients: (D-1) Methyl hydrogen polysiloxane expressed by the following average formula

(式中，矽氧烷單位之排列為無規或嵌段)。

(In the formula, the arrangement of siloxane units is random or block).

(D-2) Methyl hydrogen polysiloxane expressed by the following average formula

(式中，矽氧烷單位之排列為無規或嵌段)。

(In the formula, the arrangement of siloxane units is random or block).

(E) Ingredients: (E-1)Chloroplatinic acid octanol complex

(F) Ingredients: (F-1) Ethynyl cyclohexanol

Using the silicone rubber compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3, the following properties were evaluated. The results are shown in Table 2.

[hardness] The composition was poured into a mold so as to be 2 mm thick, and the hardness of the cured product (hardness meter A) was measured in accordance with JIS K 6253-3:2012 and cured at 60°C for 2 hours. In addition, the hardness of the cured product produced in the same manner after being exposed to an environment at 180°C for 150 hours was measured in the same manner as above. [Tensile strength, elongation when cut, tear strength] The composition was poured into a mold with a thickness of 2mm, and a dumbbell-shaped test piece hardened at 60°C for 2 hours. According to JIS K 6249: 2003, the tensile strength (MPa) and the elongation at cut were measured respectively ( %) and tear strength (kN/m). In addition, the dumbbell-shaped test piece produced in the same manner was exposed to an environment at 180°C for 150 hours, and the above-mentioned physical properties were measured. [Number of copies] Flow the silicone rubber composition into a concave mold frame and harden at 60°C for 2 hours to make a concave silicone rubber mold. Repeat the following operations: pour nylon resin (PA3000 manufactured by SLM) into the recess of the silicone rubber mold, harden at 180°C for 1 hour to make a nylon resin replica, and take out the nylon resin replica from the silicone rubber mold. Evaluate the repeatable number of replications until cracks are observed in the silicone rubber mold.

As shown in Table 2, it can be seen that the cured product obtained from the molding silicone rubber composition of the present invention prepared in Examples 1 to 4 has excellent heat resistance, and the nylon resin replica has a good number of replications. On the other hand, in Comparative Example 1 in which the (A) component of the present invention is not used, Comparative Example 2 in which the (B) component is not used, and Comparative Example 3 in which the (C) component is not used, polysilicon is likely to be generated due to poor heat resistance. It can be seen that the cracks of the oxy rubber mold are not suitable for molding.

Claims (8)

A silicone rubber composition for molding, characterized by containing: (A) Organopolysiloxane represented by the following average formula (1): 100 parts by mass of Vi _(3-a) R ¹ _a SiO(R ¹ ₂ SiO) _m SiR ¹ _a Vi _(3-a) (1) (In the formula, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group without an alkenyl group, Vi represents a vinyl group, and m is a temperature at 25°C. (A) The viscosity of the component becomes the number of 10,000~200,000 mPa·s, and a is the number of 0~2) (B) Organopolysiloxane represented by the following average formula (2): 5~100 parts by mass (R ¹ ₃ SiO _1/2 ) _p (Vi _(3-b) R ¹ _b SiO _1/2 ) _q (SiO _4/2 ) _r (2) (In the formula, R ¹ and Vi represent the same meaning as above, p, q and r satisfy the number of p>0, q>0, r>0, p+q+r=1, b is a number of 0~2), (C) the specific surface area by BET method is 50m ² /g The above silicon oxide: 3~50 parts by mass (D) Organohydrogen polysiloxane represented by the following average formula (3): 0.1~200 parts by mass (R ¹ ₃ SiO _1/2 ) _s (H _{(3-c) )} R ¹ _b SiO _1/2 ) _2-s (HR ¹ ₁ SiO _2/2 ) _t (R ¹ ₂ SiO _2/2 ) _u (3) (In the formula, R ¹ has the same meaning as above, and c is 1 Or 2, s is a number from 0 to 2, t and u satisfy t>0, u≧0, and 2≦t+u≦100 and 0.05≦t/(t+u)≦1.0 respectively), and (E) Hydrosilylation reaction catalyst. Such as the silicone rubber composition for molding of claim 1, wherein in the aforementioned component (A), a is a number from 0 to 1.8. Such as claim 1 or 2 of the silicone rubber composition for molding, wherein the viscosity of the aforementioned component (A) at 25°C is 20,000-150,000 mPa·s. The silicone rubber composition for molding of claim 1 or 2, wherein the specific surface area of the aforementioned component (C) is 150 m ² /g or more. Such as claim 1 or 2 of the silicone rubber composition for molding, wherein in the aforementioned (D) component, t and u respectively satisfy t>0, u>0, and 2≦t+u≦70 and 0.2≦t /(t+u)≦0.5 The number. A molding agent composed of the silicone rubber composition for molding according to any one of claims 1 to 5. A silicone rubber mold, which is formed by hardening the silicone rubber composition for molding according to any one of claims 1 to 5. A method for manufacturing a resin replica, which uses the silicone rubber mold of claim 7.