TWI828912B - Polysilicone rubber composition and polysilicone rubber mold for molding - Google Patents

Abstract

The present invention provides a silicone rubber composition that can provide a reusable silicone rubber mold with excellent heat resistance. The composition contains: (A) Organopolysiloxane (1) Vi _(3-a) R ¹ _a SiO (R ¹ ₂ SiO) _m SiR ¹ _a Vi _(3-a) (1) (R ¹ is not A monovalent hydrocarbon group containing an alkenyl group, Vi is a vinyl group, m is the number at which the viscosity becomes 10,000~200,000mPa·s, a is 0~2) (B) Organopolysiloxane (2) (R ¹ ₃ SiO _{1/ 2} ) _p (Vi _(3-b) R ¹ _b SiO _1/2 ) _q (SiO _4/2 ) _r (2) (R ¹ and Vi are the same as above, p, q, r satisfy p＞0, q＞ 0, r>0, p+q+r=1, b is 0~2), (C) Silicon oxide with a BET specific surface area of more than 50m ² /g, (D) Organohydrogen polysiloxane (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) (R ¹ is the same as above, c is 1 or 2, s is 0~2, t and u satisfy t>0, u≧0, 2≦t+u≦100, 0.05≦t/(t+u)≦1.0 ), (E) Hydrosilylation reaction catalyst.

Description

Polysilicone rubber composition and polysilicone rubber mold for molding

The present invention relates to a silicone rubber composition for molding and a silicone rubber mold. More specifically, it relates to an addition-cured polysilicone rubber composition for molding and a polysilicone molding master mold obtained by hardening the silicone rubber composition. (Also female models).

Using a polysilicone rubber mold as an inverted master mold, filling it with resin and hardening it to produce multiple products, from interesting mini models to industrial trial models, has become widely popular. The polysilicone rubber used in these applications is in liquid form before hardening and can be easily hardened by mixing it with a hardener at room temperature or heating, and has the advantage of being used as a reversible mold. However, on the contrary, since it is rubber, the injected resin adheres closely to the rubber mold, making it difficult to release the mold. As a solution, a release agent is generally used, but this poses a problem in terms of shortening the step time.

As a means to solve this problem, Patent Document 1 proposes to add a non-crosslinked polysiloxane polymer having a chain length longer than that of the crosslinked base polymer, thereby achieving a greater improvement in mold releasability. However, when resins such as nylon and the like that have a high heat deformation temperature are repeatedly molded by vacuum injection molding using this method, the tear strength of the inverted master mold is reduced, making it difficult to demold, and there is a risk of damage to the master mold. The mold causes cracks and other scars. 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 Document]

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

[Problem to be solved by the invention]

The present invention was made in view of the above circumstances, and its object is to provide a silicone rubber composition for molding that can be provided with a silicone rubber mold that is excellent in heat resistance and can be reused, and a product using the silicone rubber composition for molding. Method for manufacturing resin replicas. [Means used to solve problems]

As a result of active examination by the present inventors to solve the above-mentioned problems, the inventors found that a specific addition-cured silicone rubber composition can provide a reusable silicone rubber mold with excellent heat resistance, and thus completed the present invention.

That is, the present invention provides 1. A polysiloxane rubber composition for molding, characterized by containing: (A) Organopolysiloxane represented by the following average formula (1): 100 parts by mass 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, and Vi represents a vinyl group , m is the number at which the viscosity of component (A) becomes 10,000 to 200,000 mPa·s at 25°C, 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 The same meaning as above, p, q and r are numbers that satisfy p>0, q>0, r>0, p+q+r=1, b is a number from 0 to 2), (C) Use the BET method Silicon oxide with a specific surface area of 50 m ² /g or more: 3 to 50 parts by mass (D) Organohydrogen polysiloxane represented by the following average formula (3): 0.1 to 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 The same meaning as above, c is 1 or 2, s is a number from 0 to 2, t and u respectively 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 between 0 and 1.8. 3. The polysilicone rubber composition for molding as in 1 or 2, wherein the viscosity of the aforementioned component (A) at 25°C is 20,000~150,000 mPa·s. 4. The polysiloxane rubber composition for molding according to any one of 1 to 3, wherein the specific surface area of the component (C) is 150 m ² /g or more. 5. The polysiloxane rubber composition for molding according to any one of 1 to 4, wherein in the aforementioned component (D), t and u respectively satisfy t>0, u>0, and 2≦t+u≦70 And the number 0.2≦t/(t+u)≦0.5. 6. A molding agent made of the polysiloxane rubber composition for molding according to any one of 1 to 5. 7. A silicone rubber mold, which is formed by hardening the silicone rubber composition for molding according to any one of 1 to 5. 8. A method of manufacturing a resin replica, which uses a silicone rubber mold as in 7. [Effects of the invention]

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

Hereinafter, the present invention will be described in detail. In addition, in the present invention, the term "silicone rubber composition for molding" refers to a composition that has fluidity in an uncured state and is contacted with the entire surface or part of the surface of the original mold by injection molding or coating, and is cured in this state. This forms an uncured (liquid) composition that is used in a mold (master mold for film formation) that is replicated using resin or the like.

The polysilicone 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) (1) represented by the following average formula (1) (where, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group without an alkenyl group, Vi represents a vinyl group, m is the number at which the viscosity of component (A) at 25°C becomes 10,000~200,000 mPa·s, and a is 0 ~2 number) (B) Organopolysiloxane (R ¹ ₃ SiO _1/2 ) _p (Vi _(3-b ) R ¹ _b SiO _1/2 ) _q (SiO) represented by the following average formula (2) _4/2 ) _r (2) (In the formula, R ¹ and Vi represent the same meaning as above, p, q and r satisfy p＞0, q＞0, r＞0, p+q+r=1 number, b is a number from 0 to 2), (C) Silicon oxide (D) with a specific surface area of 50 m ² /g or more using 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 respectively. /(t+u)≦1.0), and (E) hydrosilylation reaction catalyst.

[1] Component (A) 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 formula (1), R ¹ each independently represents an unsubstituted or substituted monovalent hydrocarbon group without an alkenyl group, and Vi represents a vinyl group. The monovalent hydrocarbon group of R ¹ is not particularly limited as long as it does not contain an alkenyl group. It may be linear, branched, or cyclic, but it is preferably a monovalent hydrocarbon group with 1 to 20 carbon atoms, and more preferably It is a monovalent hydrocarbon group having 1 to 10 carbon atoms, 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, n-hexyl, etc.; cyclic alkyl groups such as cyclohexyl; Aryl groups such as phenyl, tolyl, etc.; aralkyl groups such as benzyl, phenylethyl, etc. In addition, part or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as F, Cl, Br, or cyano groups. Specific examples of these groups include 3,3,3-trifluoropropyl. Such as halogen-substituted hydrocarbon groups; 2-cyanoethyl, etc., cyano-substituted hydrocarbon groups, etc. Among these, R ¹ is preferably methyl.

Based on the processing properties of the polysiloxane rubber composition for molding of the present invention and the tear strength and heat resistance of the resulting hardened product, the viscosity of component (A) at 25°C is 10,000~200,000 mPa·s, Preferably, it is 25,000~150,000 mPa・s. However, m in formula (1) is a number where the viscosity of component (A) at 25°C is 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 a value measured using a rotational viscometer. In addition, a in the formula (1) is a number from 0 to 2, preferably a number from 0 to 1.8.

Specific examples of the component (A) include organopolysiloxane represented by the following average formula. 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 below)).

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

[2] Component (B) The component (B) 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-mentioned formula (1), and its specific examples are also the same as the above-exemplified groups. In this case, a methyl group is also preferred. p, q and r are numbers that satisfy p＞0, q＞0, r＞0 and p+q+r=1 respectively. However, from the viewpoint of the mechanical properties of the obtained hardened material, the organic polysiloxane of component (B) In alkanes, the ratio of M units to Q units (p+q)/r is preferably 0.3 to 2.0, more preferably 0.4 to 1.0. b is a number from 0 to 2.

The molecular weight of component (B) is not particularly limited, but from the viewpoint of the compatibility with other components and the mechanical properties of the obtained hardened material, 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 converted to standard polystyrene by gel permeation chromatography (GPC).

Specific examples of component (B) include organopolysiloxane represented by the following formula. (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 component (B) is 5 to 100 parts by mass, preferably 10 to 50 parts by mass relative to 100 parts by mass of component (A). If the blending amount of component (B) is less than 5 parts by mass, the resulting hardened product will have insufficient mechanical properties. If it exceeds 100 parts by mass, the viscosity of the composition will become high, making it difficult to mold. In addition, since component (B) may become solid at 25°C, it can also be used by being dissolved in component (A). Moreover, (B)component may be used individually by 1 type, or may use 2 or more types together.

[3](C) Component (C) Component is silicon oxide with a specific surface area of 50 m ² /g or more by BET method, preferably 50 to 500 m ² /g, more preferably 150 to 350 m ² /g, and is used for A component that imparts tensile strength, tear strength, and mechanical properties when elongated at the time of cutting to the cured product obtained from the polysiloxane rubber composition of the present invention. Examples of silicon oxide include fumed silicon oxide, crystalline silicon oxide (quartz powder), precipitated silicon oxide, silicon oxide whose surface has been hydrophobized, etc. One type of these can be used alone or two types can be combined. Used above.

As such silicon oxide, examples of hydrophilic silicon oxide include Aerosil 130, 200, and 300 (manufactured by Japan Aerosil Co., Ltd.), Cabosil MS-5, MS-7 (manufactured by Cabot Co., Ltd.), Rheorosil QS-102, 103 (TOKUYAMA (TOKUYAMA) Fumed silicon oxide made by TOKUYAMA Co., Ltd.); precipitated silicon oxide such as Tokusil US-F (manufactured by TOKUYAMA Co., Ltd.), Nipsil LP (manufactured by Nippon SILICA Industrial Co., Ltd.), etc. As hydrophobic silicon oxide, examples are: Aerosil R-812, R-812S, R-972, R-974 (manufactured by Japan Aerosil Co., Ltd.), Rheorosil MT-10 (manufactured by TOKUYAMA Co., Ltd.) and other fumed silicon oxides; Nipsil SS series (Japan SILICA Industrial Sedimentable silicas such as Crystalite (manufactured by Ronsen Co., Ltd.), MIN-U-SIL (manufactured by U.S. Silica Company), Imisil (manufactured by Illinois Mineral Company), etc.

There is no problem in using the silicon oxide as it is, but it is preferable to use a surface treatment agent to hydrophobize the surface of the silicon oxide in advance, or to add a surface treatment agent when kneading component (A) to hydrophobize the silicon oxide surface. Examples of surface treatment agents include alkylalkoxysilane, alkylhydroxysilane, alkylchlorosilane, alkylsilazane, silane coupling agent, low molecular weight polysiloxane, titanate treatment agent, and fatty acid ester, etc., preferably alkylsilazane, more preferably hexamethyldisilazane. One type of these surface treatment agents can be used alone, or two or more types can be used at the same time or at different points in time. The usage amount of the surface treatment agent is preferably 0.5 to 50 parts by mass, more preferably 1 to 40 parts by mass, and still more preferably 2 to 30 parts by mass relative to 100 parts by mass of silicon oxide. If the amount of the surface treatment agent used 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 increase in viscosity over time can be suppressed.

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

[4] Component (D) Component (D) is an organohydrogen polysiloxane 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-mentioned formula (1), and its specific examples are also the same as the above-exemplified groups. In this case, a methyl group is also preferred. c is 1 or 2, and s is a number from 0 to 2. t and u are numbers that satisfy t＞0, u≧0, and 2≦t+u≦100 and 0.05≦t/(t+u)≦1.0 respectively, but t+u is preferably 8~80, t/ (t+u) is preferably 0.2~0.8. When t+u is less than 2, component (D) may volatilize during hardening. When t+u exceeds 100, the viscosity of component (D) becomes high and workability deteriorates. If t/(t+u) is less than 0.05, the rubber physical properties of the obtained hardened product will be insufficient.

The molecular weight of component (D) 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.

Specific examples of the organohydrogen polysiloxane as component (D) include trimethylsiloxy-capped methyl hydrogen polysiloxane at both ends of the molecular chain and trimethylsiloxy-capped both ends of the molecular chain. Terminated dimethylsiloxane, methylhydrogensiloxane copolymer, trimethylsiloxy-terminated dimethylpolysiloxane, methylhydrogensiloxane, methylphenylsiloxane at both ends of the molecular chain Alkane copolymer, dimethylpolysiloxane terminated with dimethylhydrogensiloxy groups at both ends of the molecular chain, dimethylsiloxane and methylhydrogensiloxane terminated with dimethylhydrogensiloxy groups at both ends of the molecular chain Alkane copolymer, dimethylsiloxy-methylphenylsiloxane copolymer terminated with dimethylhydrogensiloxy groups at both ends of the molecular chain, methylbenzene terminated with dimethylhydrogensiloxy groups at both ends of the molecular chain Organic polysiloxanes, mixtures of two or more of these organopolysiloxanes, etc. More specifically, examples thereof include organohydrogen polysiloxane represented by the following formula.

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

The compounding amount of component (D) is 0.1 to 200 parts by mass, preferably 0.3 to 50 parts by mass relative to 100 parts by mass of component (A). If the blending amount of component (D) is less than 0.1 parts by mass, cross-linking will be insufficient. If it exceeds 200 parts by mass, foaming will easily occur due to the generation of hydrogen during hardening, and the rubber strength will decrease due to the generation of voids inside the hardened product. . Furthermore, the number of hydrogen atoms bonded to silicon atoms in component (D) per vinyl group in component (A) and component (B) is preferably 0.4 to 4, more preferably 0.8 to 3. Moreover, (D)component may be used individually by 1 type, or may use 2 or more types together.

[5](E)Component Component (E) is a hydrosilylation reaction catalyst used to promote the hydrosilylation reaction between the vinyl group in component (A) and the SiH group in component (B). Specific examples thereof include platinum black, platinum chloride, chlorinated platinic acid, the reaction product of chlorinated platinic acid and monohydric alcohol, complexes of chlorinated platinic acid and olefins, platinum bisacetyl acetate, etc. Platinum-based catalysts, palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium, etc., rhodium-based catalysts such as tris(triphenylphosphine)rhodium chloride, tetrakis(triphenylphosphine)rhodium, etc. Catalysts, etc. Moreover, (E)component may be used individually by 1 type, or may use 2 or more types together.

The blending amount of component (E) is not particularly limited as long as it can accelerate the hardening (hydrosilylation reaction) of the composition. It is calculated based on the total mass of the components of the composition. The mass conversion ratio is preferably in the range of 0.1~1,000ppm, more preferably in the range of 1~500ppm, and even more preferably in the range of 3~100ppm. If it is within this range, the reaction rate of the addition reaction becomes appropriate.

[6](F)Component In the polysiloxane rubber composition for molding of the present invention, the reactivity of the hydrosilylation reaction catalyst is controlled so as not to cause viscosity increase or gelation before heating and hardening during preparation of the composition or molding. , you can also add (F) reaction control agent as needed. Specific examples of the reaction control agent include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, and 3,5-dimethyl-1-hexyn- 3-alcohol, 1-ethynylcyclohexanol, ethynylmethyldecylcarbitol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethyl Siloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis (2,2-Dimethyl-3-butynyloxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasyloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, etc., one type of these may be used alone, or two or more types may be used in combination. Among these, 1-ethynylcyclohexanol, ethynylmethyldecylcarbitol, and 3-methyl-1-butyn-3-ol are preferred.

When component (F) is used, 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 in total of component (A) and component (B). If it is within this range, the reaction control effect can be fully exerted.

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

Specific examples of the coloring agent 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 pine red; metallic 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 selected appropriately considering the hue and chroma.

The polysiloxane rubber composition for molding of the present invention can be mixed by conventional methods such as the above-mentioned (A) to (E) components, (F) component if necessary, and other components using a kneader, a planetary mixer, etc. And modulation. The polysiloxane rubber composition for molding of the present invention can also be prepared as a first component consisting of component (A), component (B), component (C), component (E) and other components as needed. A two-dose composition consisting of a second dose consisting of component (A), component (D), component (C) and other ingredients as needed, and the first and second doses are mixed before use. In addition, the first agent and the second agent may have components used in common. By configuring the composition into these two-dose forms, storage stability can be further ensured.

The silicone rubber composition for molding of the present invention is injected into a specific mold, and the silicone rubber mold can be obtained by hardening. In particular, it is preferable to use a vacuum injection mold for injection molding. As a hardening condition, hardening at normal temperature (5~35°C) can also be performed. However, hardening can also be promoted by heating. This method is effective when mass productivity is to be improved. . When heating and hardening, it can usually be carried out at a temperature of 40 to 60°C for about 2 to 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 molded articles such as nylon resin, epoxy resin, urethane resin, etc. It is especially suitable for the molding of nylon resin that requires a heat deformation temperature of 50~200℃, preferably 70~180℃ during melting. [Example]

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.

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

[Comparative example 2] A polysilicone rubber composition was obtained in the same manner as in Example 1 except that component (B) was not used.

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

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

(B) Component: (B-1) Organopolysiloxane (weight average molecular weight 3,500) represented by (Me ₃ SiO _1/2 ) _0.4 (ViMe ₂ SiO _1/2 ) _0.045 (SiO _4/2 ) _0.555

(C) Ingredients: (C-1) Fumed silicon oxide (manufactured by Japan Aerosil Co., Ltd., Aerosil R976, BET specific surface area 240m ² /g)

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

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

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

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

(E)Ingredients: (E-1) Platinum chloride octanol complex

(F)Ingredients: (F-1) Ethynylcyclohexanol

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

[hardness] The composition was poured into a mold so that it became 2 mm thick, and the hardness (hardness meter A) of the obtained hardened product was measured in accordance with JIS K 6253-3:2012 after curing at 60°C for 2 hours. And the hardness of the hardened material made in the same way was measured in the same way as above after being exposed to an environment of 180°C for 150 hours. [Tensile strength, elongation at cut, tear strength] The composition was poured into a mold to a thickness of 2 mm, and the dumbbell-shaped test piece was hardened at 60°C for 2 hours. The tensile strength (MPa) and elongation at cut (MPa) were measured in accordance with JIS K 6249: 2003. %) and tear strength (kN/m). Furthermore, the dumbbell-shaped test piece prepared in the same manner was exposed to an environment of 180° C. for 150 hours, and then the above-mentioned physical properties were measured. [Number of copies] The polysilicone rubber composition is poured into the concave mold frame and hardened under hardening conditions of 60°C and 2 hours to produce a concave polysilicone rubber mold. Repeat the following operations: flow nylon resin (PA3000 manufactured by SLM Company) into the recessed part of the silicone rubber mold, and harden at 180° C. for 1 hour to produce a nylon resin replica. The obtained nylon resin replica is taken out from the silicone rubber mold. Evaluate the number of repeatable replicates 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 polysiloxane rubber composition for molding of the present invention prepared in Examples 1 to 4 has excellent heat resistance, and the number of replications of the nylon resin replica is good. On the other hand, Comparative Example 1 that does not use component (A) of the present invention, Comparative Example 2 that does not use component (B), and Comparative Example 3 that does not use component (C) of the present invention have poor heat resistance and are prone to polysilica. The cracks in the oxygen rubber mold indicate that it is not suitable for molding.

Claims (8)

A polysiloxane rubber composition for molding, characterized by containing: (A) Organopolysiloxane represented by the following average formula (1): 100 parts by mass 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 the value at 25°C. (A) The viscosity of the component is a number between 10,000 and 200,000 mPa‧s, a is a number between 0 and 2) (B) Organopolysiloxane represented by the following average formula (2): 5 to 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) (wherein, R ¹ and Vi have the same meaning as above, p, q and r are numbers that satisfy p>0, q>0, r>0, p+q+r=1, b is a number from 0 to 2), (C) the specific surface area using the BET method is 50m ² /g The above silicon oxide: 3 to 14 parts by mass (D) Organohydrogen polysiloxane represented by the following average formula (3): 0.1 to 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 means the same as above, and c is 1 or 2, s is a number between 0 and 2, t and u are numbers that satisfy t>0, u≧0, and 2≦t+u≦100 and 0.05≦t/(t+u)≦1.0 respectively), and (E) Hydrosilylation reaction catalyst. For example, the polysiloxane rubber composition for molding according to claim 1, wherein in the aforementioned component (A), a is a number between 0 and 1.8. For example, the polysiloxane rubber composition for molding in claim 1 or 2, wherein the viscosity of the aforementioned component (A) at 25°C is 20,000~150,000mPa‧s. For example, the polysiloxane rubber composition for molding according to claim 1 or 2, wherein the specific surface area of the component (C) is 150 m ² /g or more. For example, the polysiloxane rubber composition for molding in claim 1 or 2, wherein in the aforementioned component (D), t and u respectively satisfy t>0, u>0, and 2≦t+u≦70 and 0.2≦t /(t+u)≦0.5 number. A molding agent made of the polysiloxane rubber composition for molding in any one of claims 1 to 5. A polysilicone rubber mold is obtained by hardening the polysilicone rubber composition for molding according to any one of claims 1 to 5. A method of manufacturing a resin replica using the polysiloxane rubber mold of claim 7.