JP2013234282A - Silicone rubber mold making-up material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone rubber mold making-up material capable of forming a silicone rubber mold having transparency suitable for fabrication of mold parting and having excellent mold making-up durability.SOLUTION: By blending a linear organopolysiloxane containing 4 to 16 mol% of a phenyl group, a three-dimensional network-structured organopolysiloxane containing 4 to 16 mol% of a phenyl group, an organohydrogenpolysiloxane containing a phenyl group of ≥4 mol% of the total amount of a silicon atom-bonded hydrogen atom and a silicon atom-bonded organic group, a silica micropowder and a platinum-based compound in predetermined blend amounts, a cured material can be obtained which is excellent in transparency relevant to visibility of a master in mold parting, and which allows to increase the number of times of mold making-up when duplicate products are manufactured using an urethane resin or an epoxy resin.

Description

  The present invention relates to an addition-curing type silicone rubber molding material, and more specifically, is used for molding that requires a high degree of releasability, such as molding of a prototype model, that is, prototype molding, by curing to a rubber shape. The present invention relates to a silicone rubber molding material that is excellent in releasability from molded products such as urethane resins and epoxy resins, and in particular provides a silicone rubber matrix in which the transparency of a cured product is remarkably improved.

  Conventionally, silicone rubber has been widely used in various fields by taking advantage of its excellent heat resistance, cold resistance, electrical characteristics, etc. Especially, since it has good releasability, it is used as a silicone rubber mold (matrix). Has been used. Molding materials using silicone rubber composition improve cost and required time in prototype molding used in the product development stage and product sample preparation in the fields of electronic equipment, office machines, home appliances, automobile parts, etc. In view of workability, an addition reaction type liquid silicone rubber composition has been frequently used.

  Although the addition reaction type silicone rubber composition has preferable molding characteristics as a molding material, a general silicone rubber has a refractive index of dimethylpolysiloxane as a polymer and silica used for high strength. Due to the difference, the appearance is translucent, especially in the thick part of the silicone rubber molding material, the visibility of the master (original) inside becomes poor, and silicone rubber molding material is used for the production of the split mold. When cutting, there is a problem that the master (original) is damaged or a part different from the predetermined position is cut.

  In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2003-192898 (Patent Document 1) discloses a method of adding a blue to purple or black cobalt compound to a liquid addition-curable polyorganosiloxane composition. Although described, there are compounds suspected of showing carcinogenicity in the cobalt compound, which is problematic in terms of safety. Actually, cobalt compounds are exemplified, but there is no description in terms of safety, and no specific application examples are described.

  Japanese Patent Laid-Open No. 2005-325158 (Patent Document 2) describes a method of adding ultramarine blue to a liquid addition-curable polyorganosiloxane composition, but the difference in refractive index is not changed. At first glance, the transparency seems to improve, but the thick part of the silicone rubber has a problem with the visibility of the master (original) inside, so it is not optimal as a silicone rubber mold material. .

JP-A-2-045561 (Patent Document 3) discloses methylphenylpolysiloxane having a phenyl group of 5 to 30 mol%, fumed silica having a specific surface area of 130 m ² / g or more, diphenyl dialkoxysilane, A silicone compound composition composed of diphenyldichlorosilane, Japanese Patent Application Laid-Open No. 61-246292 (Patent Document 4), has a specific surface area of 130 m ² / g or more in methylphenyl polysiloxane containing 5 to 20 mol% of phenyl groups. Silicone grease compositions are also described in combination with fumed silica, double bond or alkoxysilane containing an epoxy group, but it is only described that the grease is transparent, The application of the mold base material that requires transparency and mold durability is described. There.

JP 2003-192898 A JP 2005-325158 A JP-A-2-045561 Japanese Patent Laid-Open No. 61-246292

  The present invention has been made in view of the above circumstances, and provides a silicone rubber mold molding material capable of forming a silicone rubber mold (matrix) having transparency suitable for mold part production and excellent mold molding durability. With the goal.

  As a result of intensive studies to achieve the above object, the present inventors have a large reduction in workability and the like, such as the above-described transparency being poor and the master (original) being damaged at the time of mold division. It is found that the cause is the difference in refractive index between the resin part and silica, and further, as a composition constituting the silicone rubber molding material, a monovalent aliphatic unsaturated hydrocarbon group bonded to a silicon atom and a phenyl group By using the organopolysiloxane and the phenyl group-containing organohydrogenpolysiloxane, the difference in refractive index between the resin part and silica in the cured silicone rubber is eliminated, and the master (original model) at the time of mold splitting is visible. In addition to realizing a cured product with excellent transparency related to its properties, it has excellent mechanical strength and releasability. As a result, high-performance urethane resins and epoxy resins can be used. There are cured product can increase the templating number in the production of reproductions found that can be a (silicone rubber mother mold), the present invention has been accomplished.

Accordingly, the present invention provides the following silicone rubber molding material.
[1] (A) The viscosity at 25 ° C. is 10 to 100,000 mPa · s, the molecule has two or more monovalent aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and has a phenyl group. 100 parts by mass of a linear organopolysiloxane containing 4 to 16 mol%,
(B) SiO ₂ unit and (R ¹ ) ₃ SiO _0.5 unit (wherein R ¹ is independently a monovalent hydrocarbon group containing no vinyl group, allyl group or aliphatic unsaturated bond). 0 to 100 parts by mass of an organopolysiloxane having a three-dimensional network structure in which 4 to 16 mol% of R ¹ is a phenyl group
(C) The hydrogen atom bonded to the silicon atom has 3 or more hydrogen atoms in one molecule, and the monovalent organic group bonded to the silicon atom is an unsubstituted or halogen-substituted alkyl group or aryl group, 0.1 to 30 parts by mass of an organohydrogenpolysiloxane in which the number of moles of phenyl groups is 4 mol% or more with respect to the total number of moles of atoms and silicon atom-bonded organic groups;
(D) 10 to 50 parts by mass of silica fine powder having a specific surface area of 50 m ² / g or more,
(E) Platinum compound 0.1 to 1,000 ppm in terms of platinum atom mass
A silicone rubber molding material comprising a composition containing
[2] The (R ¹ ) ₃ SiO _0.5 unit of the component (B) is (R ¹¹ ) ₃ SiO _0.5 unit (R ¹¹ is an alkyl group having 1 to 4 carbon atoms) and R ¹¹ PhR ¹² SiO _0.5 unit. (R ¹¹ is an alkyl group having 1 to 4 carbon atoms, Ph is phenyl group, R ¹² is vinyl or allyl.) consisting of a (1) silicone rubber mold removal material according.
[3] (D) The silicone rubber molding material according to [1] or [2], wherein the silica fine powder is fumed silica whose surface is treated with organosilazanes.
[4] The silicone rubber molding according to any one of [1] to [3], wherein the difference in refractive index between the organopolysiloxane of component (A) and the fine silica powder of component (D) is within ± 0.02. material.
[5] The silicone rubber mold molding material according to any one of [1] to [4], wherein the cured product of the silicone rubber mold molding material has a total light transmittance of 90% or more in accordance with JIS K7105-1981.

  According to the silicone rubber molding material of the present invention, at least a linear organopolysiloxane and fine silica powder are blended in a predetermined amount, so that a cured product having excellent mechanical strength and releasability is obtained, and silicon atoms By using a monovalent aliphatic unsaturated hydrocarbon group and a phenyl group-containing organopolysiloxane and a phenyl group-containing organohydrogenpolysiloxane, the resin portion and the refractive index of silica in the cured silicone rubber Therefore, the cured product is excellent in transparency. As a result, the silicone rubber mold (matrix) has excellent master (original) visibility, which can greatly improve the workability at the time of mold splitting. And the number of times of mold making when producing a replica using epoxy resin can be improved. The total light covers the wavelength range of visible light, and the high total light transmittance of the heat insulating laminate of the present invention means that the transparency of visible light is excellent.

Hereinafter, an embodiment of the silicone rubber molding material according to the present invention will be described.
In the present invention, the mold material is fluid in an uncured state, and is brought into contact with the entire surface or a part of the original surface by a method such as casting or coating, and is cured in that state. This refers to an uncured (liquid) material that forms a mold (mould for mold making) to be replicated with a resin or the like. Further, in the present invention, the releasability is a term including not only the releasability from the original mold of the hardened mold (matrix) but also the releasability of the replicated product from the obtained mold (matrix). Use.

The silicone rubber mold material of the present invention comprises a composition containing the following components (A) to (E), is excellent in transparency, and has a total light transmittance of 90% or more of the cured product. is there.
(A) The viscosity at 25 ° C. is 10 to 100,000 mPa · s, has two or more monovalent aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in one molecule, and has 4 to 16 phenyl groups. Linear organopolysiloxane containing mol%,
(B) SiO ₂ unit and (R ¹ ) ₃ SiO _0.5 unit (wherein R ¹ is independently a monovalent hydrocarbon group containing no vinyl group, allyl group or aliphatic unsaturated bond). An organopolysiloxane having a three-dimensional network structure in which 4 to 16 mol% of R ¹ is a phenyl group,
(C) The hydrogen atom bonded to the silicon atom has 3 or more hydrogen atoms in one molecule, and the monovalent organic group bonded to the silicon atom is an unsubstituted or halogen-substituted alkyl group or aryl group, An organohydrogenpolysiloxane in which the number of moles of phenyl groups is 4 mol% or more with respect to the total number of moles of atoms and silicon-bonded organic groups;
(D) fine silica powder having a specific surface area of 50 m ² / g or more,
(E) Platinum compounds

[(A) Organopolysiloxane]
The component (A) that is a base component in the silicone rubber composition of the present invention has two or more aliphatic unsaturated bonds in one molecule, and has a viscosity at 25 ° C. of 10 to 100,000 mPa · s, It is a linear organopolysiloxane containing 4 to 16 mol%, preferably 7 to 13 mol% of phenyl groups in all substituents bonded to silicon atoms. Even if the phenyl group content is less than 4 mol% or more than 16 mol%, the difference in refractive index between the resin part of the cured silicone rubber and silica is increased, and the transparency required for the cured product cannot be ensured.

  As such an organopolysiloxane, a linear diorganopolysiloxane having a main chain composed of repeating diorganosiloxane units and having both molecular chain ends blocked with triorganosiloxy groups is preferably used.

  Further, the viscosity at 25 ° C. of the component (A) is 10 to 100,000 mPa · s from the viewpoint of workability and curability of the composition according to the present invention. The viscosity in the present invention is a value measured with a rotational viscometer. The component (A) can be used alone or in combination of two or more.

  The aliphatic unsaturated group of component (A) may be bonded to either the silicon atom at the end of the molecular chain or the silicon atom at the non-end of the molecular chain (in the middle of the molecular chain), or bonded to both of these. However, it is preferable to have an aliphatic unsaturated group bonded to at least silicon atoms at both ends of the molecular chain, and the content of the aliphatic unsaturated group is based on the total silicon atoms in the molecule. It is desirable that the amount be 0.001 to 20 mol%, particularly about 0.01 to 10 mol%.

（式中、Ｒ²は同一又は異種の非置換もしくは置換の１価炭化水素基であり、Ｒ³はフェニル基以外の同一又は異種の非置換もしくは置換の１価炭化水素基であり、Ｒ⁴は独立にフェニル基であり、Ｌ及びｍは各々０又は正の整数であり、ただし、Ｌ＋ｍは２５℃における粘度が１０〜１００，０００ｍＰａ・ｓとなる数であり、シロキサン結合を形成する酸素原子以外の置換基の４〜１６モル％がフェニル基である。）
で表されるオルガノポリシロキサンが挙げられる。 As a preferable example of the component (A), the following general formula (1)

Wherein R ² is the same or different unsubstituted or substituted monovalent hydrocarbon group, R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group other than phenyl group, and R ⁴ Is independently a phenyl group, L and m are each 0 or a positive integer, provided that L + m is a number with a viscosity at 25 ° C. of 10 to 100,000 mPa · s, and forms an oxygen atom that forms a siloxane bond 4-16 mol% of the substituents other than are phenyl groups.)
The organopolysiloxane represented by these is mentioned.

In the general formula (1), R ² is, for example, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group or an allyl group; Groups, tolyl groups, aryl groups such as xylyl groups; aralkyl groups such as benzyl groups; and groups obtained by substituting some or all of the hydrogen atoms of these hydrocarbon groups with halogen atoms, cyano groups, etc., for example, chloromethyl groups , A cyanoethyl group, a 3,3,3-trifluoropropyl group, and the like. Among these, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferable.

R ³ includes, for example, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; a cycloalkyl group other than a cyclohexyl group such as a cyclopentyl group; an alkenyl group such as a vinyl group and an allyl group; a tolyl group; An aryl group other than a phenyl group such as a xylyl group; an aralkyl group such as a benzyl group; and a group in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with a halogen atom, a cyano group, or the like, such as a chloromethyl group, A cyanoethyl group, a 3,3,3-trifluoropropyl group, etc. are mentioned. Among these, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferable, and a methyl group is particularly preferable.

  Further, L and m are 0 or a positive integer, and are particularly numbers such that the viscosity of the component (A) at 25 ° C. falls within the above-described range. L and m are preferably integers satisfying 1 ≦ L + m ≦ 10,000, more preferably 8 ≦ L + m ≦ 2,000, still more preferably 10 ≦ L + m ≦ 1,200, and The number satisfies 0 ≦ m / (L + m) ≦ 1, preferably 0.05 ≦ m / (L + m) ≦ 0.8, and more preferably 0.1 ≦ m / (L + m) ≦ 0.4.

  Specific examples of the component (A) include, but are not limited to, organopolysiloxanes represented by the following formulas.

（上記の各式中、Ｌ及びｍは上記と同様であり、ｎは、正の整数であり、かつ０＜ｎ／（Ｌ＋ｎ）≦１を満足する整数である点を除いて、ｍと同様である。）

(In each of the above formulas, L and m are the same as above, and n is a positive integer and is the same as m except that 0 <n / (L + n) ≦ 1) .)

[(B) Organopolysiloxane having a three-dimensional network structure]
The component (B) is composed of SiO ₂ units and (R ¹ ) ₃ SiO _0.5 units (wherein R ¹ is independently a vinyl group, an allyl group or an aliphatic unsaturated bond-free monovalent hydrocarbon group, provided that 4 to 16 mol%, preferably 7 to 13 mol% of the total R ¹ is a phenyl group.) Organopolysiloxane having a three-dimensional network structure (also referred to as a resin structure). Even if the phenyl group content is less than 4 mol% or more than 16 mol%, the difference in refractive index between the resin part of the silicone rubber cured product and silica is increased, and the transparency required for the cured product cannot be ensured. The (R ¹ ) ₃ SiO _0.5 unit is composed of (R ¹¹ ) ₃ SiO _0.5 unit (R ¹¹ is an alkyl group having 1 to 4 carbon atoms) and R ¹¹ PhR ¹² SiO _0.5 unit (R ¹¹ is carbon number). 1 to 4 alkyl groups, Ph is a phenyl group, and R ¹² is a vinyl group or an allyl group.

Here, with respect to SiO ₂ units (R ¹⁾ ₃ molar ratio of SiO _0.5 units ^{_{((R 1) 3 SiO 0.5}} / SiO 2) is 0.5 to 1.2, are especially 0.6 to 0.9 It is preferable in terms of reinforcement. In this case, if necessary, R ¹ SiO _1.5 units and (R ¹ ) ₂ SiO units may be contained (where R ¹ is as described above), but R ¹ SiO _1.5 units and (R ¹ ) ₂ SiO units are in total. The organopolysiloxane having a three-dimensional network structure preferably has a content of 0 to 20 mol%, particularly 0 to 10 mol%.

In addition, when R ¹ is a monovalent hydrocarbon group containing no aliphatic unsaturated bond, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferred. Examples thereof include a methyl group, an ethyl group, and a propyl group. Alkyl groups such as butyl groups; cycloalkyl groups such as cyclohexyl groups; aryl groups such as phenyl groups, tolyl groups and xylyl groups; aralkyl groups such as benzyl groups; and some or all of hydrogen atoms of these hydrocarbon groups Are substituted with a halogen atom, a cyano group or the like, for example, a chloromethyl group, a cyanoethyl group, a 3,3,3-trifluoropropyl group, or the like.

The content of vinyl group or allyl group is usually all 0-50 mol% of R ^1, preferably from 1 to 30 mol%, more preferably be on the order of 3 to 20 mol%, also component (B) The resin structure is preferably a vinyl or allyl group-containing resin structure organopolysiloxane.

  Moreover, the weight average molecular weight of the component (B) measured by gel permeation chromatography is preferably in the range of 500 to 10,000 in terms of polystyrene. Component (B) can be used alone or in combination of two or more.

  The component (B) is blended into the composition in order to improve the physical strength and surface tackiness of the cured product obtained from the composition according to the present invention. 0 to 100 parts by mass, preferably 20 to 80 parts by mass, and more preferably 30 to 60 parts by mass. If the amount of component (B) is too large, the cured product of the composition may become brittle.

[(C) Organohydrogenpolysiloxane]
In the organohydrogenpolysiloxane of component (C), the monovalent hydrocarbon group bonded to the silicon atom is an unsubstituted or halogen-substituted alkyl group or aryl group, and the hydrogen atom bonded to the silicon atom in one molecule ( 4 mol% or more of the total of hydrogen atoms bonded to silicon atoms and all organic groups bonded to silicon atoms (that is, unsubstituted or substituted monovalent hydrocarbon groups) having 3 or more SiH groups) It is a phenyl group, and the SiH group in the molecule acts as a curing agent for curing the composition by crosslinking with the alkenyl group bonded to the silicon atom of the component (A) by a hydrosilyl addition reaction. It is.

As the organohydrogenpolysiloxane of component (C), the following average composition formula (2)
R ⁵ _c H _d SiO _{(4-cd) / 2} (2)
(In the formula, R ⁵ is a monovalent hydrocarbon group selected from an unsubstituted or halogen-substituted alkyl group having 1 to 10 carbon atoms and an aryl group. Also, c is preferably 0.7 to 2.1, d. Is preferably 0.001 to 1.0, and c + d is preferably a positive number satisfying 0.8 to 3.0.)
Can be used, and 3 or more (usually 3 to 200), preferably 6 to 100, more preferably 10 to 50, and still more preferably 20 to 50 silicon atoms per molecule. Those having a bonded hydrogen atom (SiH group) are preferably used.

Here, in the formula (2), the monovalent hydrocarbon group selected from the unsubstituted or halogen-substituted alkyl group and aryl group of R ⁵ is the same group as exemplified for R ¹ except for the alkenyl group ( In other words, it has no aliphatic unsaturated bond such as an alkenyl group.), But a hydrogen atom bonded to a silicon atom and an all organic group bonded to a silicon atom (for example, R ² unsubstituted) Or 4 mol% or more of the total of substituted monovalent hydrocarbon groups) is essential, preferably 4 mol% or more and 30 mol% or less, more preferably 5 mol% or more and 25 mol% or less, More preferably, 10 mol% or more and 20 mol% or less is a phenyl group. When the phenyl group content is less than 4 mol%, the compatibility with the organopolysiloxane of component (A) is lowered, and the required transparency cannot be ensured. C is preferably 0.8 to 2.0, d is preferably 0.01 to 1.0, and c + d is preferably 1.0 to 2.5.

  The molecular structure of the organohydrogenpolysiloxane of component (C) may be any of linear, cyclic, branched, and three-dimensional network structures. In this case, the number (or degree of polymerization) of silicon atoms in one molecule is preferably 3 to 300, more preferably 10 to 200, still more preferably 15 to 100, and is liquid at room temperature (25 ° C.). Those are preferably used. In addition, the hydrogen atom couple | bonded with a silicon atom may be located in any of the molecular chain terminal and the middle of a molecular chain, and may be located in both.

Examples of the organohydrogenpolysiloxane of component (C) include tris (dimethylhydrogensiloxy) phenylsilane, trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, trimethylsiloxy group-blocked methyl at both ends. Hydrogensiloxane / methylphenylsiloxane copolymer, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane / diphenylsiloxane copolymer, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane / methylphenylsiloxane copolymer Combined, dimethylhydrogensiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, dimethylhydrogen diterminated at both ends Nyloxy group-blocked methylhydrogensiloxane / methylphenylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer, Dimethylsiloxane / methylhydrogensiloxane / diphenylsiloxane copolymer blocked with dimethylhydrogensiloxy group at both ends, dimethylsiloxane / methylhydrogensiloxane / methylphenylsiloxane copolymer blocked with dimethylhydrogensiloxy group at both ends, methylhydrogensiloxane / Diphenylsiloxane cyclic copolymer, methylhydrogensiloxane / methylphenylsiloxane cyclic copolymer, dimethyl Siloxane-methylhydrogensiloxane-diphenylsiloxane cyclic copolymers, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane cyclic copolymers, and (CH _{3) 2} HSiO _1/2 units and SiO _4/2 units (C ₆ A copolymer comprising H ₅ ) SiO _3/2 units, a copolymer comprising (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) ₂ SiO _2/2 units. A copolymer comprising (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) a copolymer comprising ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) SiO _3/2 units, (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ HSiO copolymers consisting of _1/2 units, and SiO _4/2 units _{(C 6 H 5) 2 SiO} 2/2 units (CH _{3) 3} SiO _1/2 units and (CH _{3) 2} HSiO _1/2 units and SiO _4/2 units and (C ₆ H ₅₎ consisting of SiO _3/2 units, copolymers composed, and the like.

  The content of silicon atom-bonded hydrogen atoms (SiH groups) in the organohydrogenpolysiloxane of component (C) is preferably 0.006 to 0.015 mol / g, more preferably 0.007 to 0.013 mol / g. If it is less than 0.006 mol / g, adhesion may be insufficient. On the other hand, when it exceeds 0.015 mol / g, a structure in which two or more hydrogen atoms are bonded to one silicon atom is required, and the organohydrogenpolysiloxane molecule becomes a very unstable substance. May end up.

  (C) The compounding quantity of the organohydrogenpolysiloxane of a component is 0.1-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 0.3-15 mass parts. When the amount is less than 0.1 parts by mass, crosslinking is insufficient, resulting in a sticky rubber. When the amount is more than 30 parts by mass, rubber physical properties are deteriorated and it is uneconomical. In addition, SiH group in (C) component with respect to the alkenyl group couple | bonded with the silicon atom in (A) component and (B) component is 0.8-5.0 by molar ratio, Preferably it is 1.0-4.0. (C) component can also be mix | blended with the quantity used as follows.

[(D) Silica fine powder]
The silica fine powder of component (D) in the present invention imparts mechanical properties to the cured product of the composition. Examples of such silica fine powder include fumed silica, precipitated silica, fused silica and the like, organosilazanes such as hexamethyldisilazane, octamethyltrisilazane, divinyltetramethyldisilazane, dimethyltetravinyldisilazane, organo Using surface treatment agents such as alkoxysilanes, organohalogenosilanes, linear or cyclic low-polymerization organopolysiloxanes, etc., hydrophobic methods such as reflux method, suspension method, atmospheric pressure fluidized bed method, pressure method, etc. What was processed is illustrated. In order to obtain good mechanical properties, fumed silica is preferred, and fumed silica surface-treated with organosilazanes such as hexamethyldisilazane is more preferred.

Further, silica fine powder used in the present invention has a specific surface area by the BET method is not less 50 m ² / g or more, 50 to 400 m ² / g, it is particularly preferably 100 to 250 m ² / g. If the specific surface area is less than 50 m ² / g, sufficient reinforcement cannot be obtained. Moreover, when the specific surface area is too large, the viscosity of the composition becomes very high, and workability may be impaired.

  The amount of component (D) is 10 to 50 parts by weight, preferably 15 to 45 parts per 100 parts by weight of component (A) because it gives good mechanical properties to the silicone rubber mold obtained by curing. Part by mass. If the amount is less than 10 parts by mass, sufficient reinforcing properties cannot be obtained, and if it exceeds 50 parts by mass, the viscosity of the composition increases and workability is impaired.

[(E) Platinum compound]
The platinum-based compound of component (E) used in the present invention comprises a monovalent aliphatic unsaturated hydrocarbon group in component (A) and a vinyl group or allyl group in component (B) and component (C). It is a catalyst for promoting an addition reaction with a hydrosilyl group and has a good catalytic ability for a curing reaction at around room temperature.

  Examples of such platinum compounds include platinum black, chloroplatinic acid, complexes obtained by reacting chloroplatinic acid and alcohol, platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-ketone complexes, platinum-aldehyde complexes, etc. Is exemplified. Among these, a reaction product of chloroplatinic acid and alcohol, a platinum-vinylsiloxane complex, and the like are preferable from the viewpoint of good solubility in (A) component, (B) component, and (C) component and catalytic activity. Further, it may be encapsulated with a resin such as a thermoplastic silicone resin.

  (E) The compounding quantity of a component is 0.1-1,000 ppm in conversion of platinum atom (mass) with respect to (A) component, Preferably it is 1-200 ppm, More preferably, it is 2-50 ppm. If it is less than 0.1 ppm, the curing speed is slow and the curing is not completely completed. Therefore, the silicone rubber mold is sticky, and the releasability of the silicone rubber mold from the original mold and the replica of the silicone rubber mold. The releasability decreases. If it exceeds 1,000 ppm, the curing rate becomes excessively fast, so the workability after blending each component is impaired, and it is also uneconomical.

  In the composition which can be the silicone rubber mold material of the present invention, other components can be blended depending on the purpose within a range not impairing the characteristics of the present invention. That is, the silicone rubber mold material of the present invention is cured such as acetylene compound, diallyl maleate, triallyl isocyanurate, nitrile compound or organic peroxide in order to lengthen the curing time at room temperature and improve workability. A retarder may be blended. Furthermore, you may mix | blend a mold release agent, a pigment, a plasticizer, a flame retardance imparting agent, a thixotropy imparting agent, an antibacterial agent, an antifungal agent, etc. as needed. Moreover, you may mix | blend powder, such as a calcium carbonate, aluminum silicate, a titanium oxide, a zinc oxide, iron oxide, carbon black, in the range which does not impair the effect of this invention.

(Transparency of cured silicone rubber)
Silicone rubber molding material with excellent transparency by reducing the difference in refractive index between the organopolysiloxane (A) and the silica fine powder (D) (preferably within ± 0.02). It can be. For example, in visible light having a wavelength of 589 nm, the refractive index of the component (A) is 1.43 to 1.47, the refractive index of the silica fine powder is about 1.45, and the difference in refractive index between the two is ± 0.02. Within. The refractive index in the present invention is a value measured by an Abbe refractometer.

  Thus, by reducing the difference in refractive index between the resin part and the silica fine powder in the cured silicone rubber (preferably within ± 0.02), the cured silicone rubber has a total light transmittance of 90% or more. Can do. The total light transmittance is an index indicating the transparency of the cured product of the silicone rubber molding material. For example, JIS K 7105-1981 using a haze measuring instrument “NDH-2000” manufactured by Nippon Denshoku Industries Co., Ltd. It is a measured value based on. This total light transmittance substantially coincides with the visible light transmittance.

  As described above, the silicone rubber mold material of the present invention eliminates the difference in refractive index between the resin part and silica as a cured silicone rubber and has almost the same refractive index. Since the master's visibility is very excellent, the workability at the time of mold splitting can be greatly improved. The total light covers the wavelength range of visible light, and the high total light transmittance of the silicone rubber molding material of the present invention means that the visible light has excellent transparency. .

(How to use silicone rubber molding material)
The silicone rubber mold molding material of the present invention is divided into a silicone compound containing at least (A), (optionally (B)), (D), (E) components and a compound containing at least (C) components. When stored in multiple containers, they are uniformly mixed and degassed, and when stored in a single container, they are extruded as they are to wrap the master (original), or one surface of the master (original). A silicone rubber mold is produced by casting or applying to the part and curing. Here, curing can be performed at room temperature to slight heating of about 60 ° C., but curing may be accelerated by heating up to 150 ° C. depending on conditions. After curing, remove the rubber mold from the master (original mold), cast molding resin such as urethane resin and epoxy resin, cure at the curing temperature according to each resin, and remove the mold to obtain a replica be able to.

  EXAMPLES Hereinafter, although a preparation example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to the following Example. In addition, in the following examples, a part represents a mass part and a viscosity shows the value in 25 degreeC measured with the Toki Sangyo Co., Ltd. rotational viscometer "RB80H". A refractive index shows the value (wavelength 589nm) in 25 degreeC measured with the Abago refractometer "NAR-3T" by an Atago Co., Ltd. product. The total light transmittance of the cured product was measured with a haze measuring instrument “NDH-2000” manufactured by Nippon Denshoku Industries Co., Ltd.

(1) Preparation of silicone compound According to the following preparation examples 1-1 to 1-6, silicone compounds (1) to (6) were prepared.

[Preparation Example 1-1]
(A) A linear vinylphenylmethylpolysiloxane having a viscosity of 5,000 mPa · s having both ends blocked with dimethylvinylsiloxy groups and modified with 5 mol% of phenyl groups in the side chain (vinyl group content = 0. 0072 mol / 100 g, refractive index at 25 ° C. 1.43) 100 parts, (B) SiO ₂ unit 50 mol%, (CH ₃ ) ₃ SiO _0.5 unit 42.5 mol% and MePhViSiO _0.5 unit (Me is a methyl group, Ph is a phenyl group, and Vi is a vinyl group. The same applies hereinafter.) Resin-structured vinylphenylmethylpolysiloxane composed of 7.5 mol% (vinyl group content = 0.043 mol / 100 g), 50 parts, (D) 40 parts of fumed silica (specific surface area by BET method 200 m ² / g, refractive index 1.45 at 25 ° C.), 5 parts of hexamethyldisilazane, water 2.5 parts were mixed in a kneader for 1 hour at room temperature. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (1) was obtained.

[Preparation Example 1-2]
(A) A linear vinylphenylmethylpolysiloxane having a viscosity of 3,000 mPa · s having both ends blocked with dimethylvinylsiloxy groups and modified with 10 mol% of phenyl groups in the side chain (vinyl group content = 0. 010 mol / 100 g, refractive index 1.45 at 25 ° C. 100 parts, (B) SiO ₂ unit 50 mol%, (CH ₃ ) ₃ SiO _0.5 unit 42.5 mol% and MePhViSiO _0.5 unit 7.5 mol% Resin structure vinyl phenylmethyl polysiloxane (vinyl group content = 0.043 mol / 100 g) 50 parts, (D) fumed silica (specific surface area 200 m ² / g by BET method, refractive index 1.45 at 25 ° C.) 40 parts, 5 parts of hexamethyldisilazane, and 2.5 parts of water were mixed in a kneader at room temperature for 1 hour. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (2) was obtained.

[Preparation Example 1-3]
(A) A linear vinylphenylmethylpolysiloxane having a viscosity of 5,000 mPa · s having both ends blocked with dimethylvinylsiloxy groups and 15 mol% of phenyl groups modified in the side chain (vinyl group content = 0. 0072 mol / 100 g, refractive index 1.47 at 25 ° C. 100 parts, (B) SiO ₂ unit 50 mol%, (CH ₃ ) ₃ SiO _0.5 unit 42.5 mol% and MePhViSiO _0.5 unit 7.5 mol% Resin structure vinyl phenylmethyl polysiloxane (vinyl group content = 0.043 mol / 100 g) 50 parts, (D) fumed silica (specific surface area 200 m ² / g by BET method, refractive index 1.45 at 25 ° C.) 40 parts, 5 parts of hexamethyldisilazane, and 2.5 parts of water were mixed in a kneader at room temperature for 1 hour. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (3) was obtained.

[Preparation Example 1-4 (for comparison)]
(A) Linear dimethylpolysiloxane having a viscosity of 5,000 mPa · s blocked at both ends with dimethylvinylsiloxy groups (vinyl group content = 0.006 mol / 100 g, refractive index 1.41 at 25 ° C.) 100 40 parts of (D) fumed silica (specific surface area 200 m ² / g by BET method, refractive index 1.45 at 25 ° C.), 5 parts of hexamethyldisilazane, and 2.5 parts of water in a kneader At room temperature for 1 hour. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (4) was obtained.

[Preparation Example 1-5 (for comparison)]
(A) A linear vinylphenylmethylpolysiloxane having a viscosity of 1,000 mPa · s having both ends blocked with dimethylvinylsiloxy groups and modified with 3 mol% of phenyl groups in the side chain (vinyl group content = 0. 011 mol / 100 g, refractive index at 25 ° C. 1.42) 100 parts, (B) SiO ₂ units 50 mol%, (CH ₃ ) ₃ SiO _0.5 units 42.5 mol% and MePhViSiO _0.5 units 7.5 mol% Resin structure vinyl phenylmethyl polysiloxane (vinyl group content = 0.043 mol / 100 g) 50 parts, (D) fumed silica (specific surface area 200 m ² / g by BET method, refractive index 1.45 at 25 ° C.) 40 parts, 5 parts of hexamethyldisilazane, and 2.5 parts of water were mixed in a kneader at room temperature for 1 hour. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (5) was obtained.

[Preparation Example 1-6 (for comparison)]
(A) A linear vinylphenylmethylpolysiloxane having a viscosity of 4,000 mPa · s having both ends blocked with dimethylvinylsiloxy groups and 22 mol% of phenyl groups modified in the side chains (vinyl group content = 0. 009 mol / 100 g, refractive index 1.48 at 25 ° C. 100 parts, (B) SiO ₂ units 50 mol%, (CH ₃ ) ₃ SiO _0.5 units 42.5 mol% and MePhViSiO _0.5 units 7.5 mol% Resin structure vinyl phenylmethyl polysiloxane (vinyl group content = 0.043 mol / 100 g) 50 parts, (D) fumed silica (specific surface area 200 m ² / g by BET method, refractive index 1.45 at 25 ° C.) 40 parts, 5 parts of hexamethyldisilazane, and 2.5 parts of water were mixed in a kneader at room temperature for 1 hour. Next, the temperature inside the kneader was raised to 160 ° C. over 60 minutes, and the mixing was continued for 4 hours while maintaining the temperature. After cooling to room temperature, (E) complex of chloroplatinic acid and vinylsiloxane Is uniformly mixed with 0.3 parts of a catalyst dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. (in this composition, the amount of platinum metal in the catalyst is 5 ppm). Thus, a silicone compound (6) was obtained.

(2) Preparation of curing agent Curing agents (7) and (8) were prepared according to Preparation Examples 2-1 and 2-2 below.

[Preparation Example 2-1]
(A) 100 parts of a linear vinylphenylmethylpolysiloxane having a viscosity of 5,000 mPa · s having a phenyl group modified by 5 mol% in the side chain (vinyl group content = 0.007 mol / 100 g), (C) silicon 10 mol% of phenyl groups with respect to the total of hydrogen atoms, phenyl groups and methyl groups bonded to the atoms, containing 6 silicon-bonded hydrogen atoms in one molecule, and a hydrogen gas generation rate of 180 ml / g Yes, 18 parts of an organohydrogenpolysiloxane having a viscosity of 10 mPa · s was uniformly mixed to prepare a curing agent (7).
The hydrogen gas generation amount is obtained by measuring the amount of hydrogen gas generated by dissolving 0.1 g of this organohydrogenpolysiloxane in 20 g of n-butanol and dropping a 20% by mass sodium hydroxide solution thereto. is there.

[Preparation Example 2-2]
(A) 100 parts of dimethylpolysiloxane blocked with dimethylvinylsiloxy group at both ends of molecular chain having a viscosity of 5,000 mPa · s (vinyl group content = 0.0053 mol / 100 g), (C) containing a phenyl group bonded to a silicon atom. First, 16 parts of organohydrogenpolysiloxane having a hydrogen gas generation amount of 200 ml / g and a viscosity of 30 mPa · s was uniformly mixed to prepare a curing agent (8).

[Example 1]
The silicone compound (1) and the curing agent (7) were mixed with a planetary mixer at a ratio of 100: 10 (mass ratio) to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

[Example 2]
The silicone compound (2) and the curing agent (7) were mixed by a planetary mixer at a ratio of 100: 10 (mass ratio) to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

[Example 3]
The silicone compound (3) and the curing agent (7) were mixed with a planetary mixer at a ratio of 100: 10 (mass ratio) to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

[Comparative Example 1]
The silicone compound (4) and the curing agent (8) were mixed at a ratio of 100: 10 (mass ratio) by a planetary mixer to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

[Comparative Example 2]
The silicone compound (5) and the curing agent (7) were mixed with a planetary mixer at a ratio of 100: 10 (mass ratio) to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

[Comparative Example 3]
The silicone compound (6) and the curing agent (7) were mixed with a planetary mixer at a ratio of 100: 10 (mass ratio) to prepare a silicone rubber composition. Next, the silicone rubber composition is heated in a heating oven at 60 ° C. for 4 hours, and the cured product is a silicone rubber mold (50 mm × 50 mm × 50 mm, shape: concave) and a silicone rubber plate (50 mm × 50 mm). × 10 mm, shape: flat plate) was prepared, and the number of times of die-molding for urethane resin and the total light transmittance were measured according to the following measurement method.

<Measurement method>
(1) Endurance of molds for urethane resin (Procedure 1) Urethane resin is injected into a silicone rubber mold (mould for molding).
(Procedure 2) Next, the injected urethane resin is cured at 70 ° C. for 30 minutes.
(Procedure 3) Next, the cured urethane resin is removed from the silicone rubber mold.
The above steps 1 to 3 were repeated, and the number of times until the silicone rubber mold could not be used due to the adhesion between the urethane resin cured product and the silicone rubber mold was counted.

(2) Total light transmittance The total light transmittance of the silicone rubber plate was measured based on JIS K 7105-1981 using a Nippon Denshoku Industries Co., Ltd. haze measuring device "NDH-2000". This total light transmittance substantially coincides with the visible light transmittance.

The measurement results in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[Evaluation]
As is apparent from the above results, a composition comprising a linear organopolysiloxane containing a phenyl group, a resin-structured organopolysiloxane containing a phenyl group, an organohydrogenpolysiloxane containing a phenyl group, silica, etc. In Examples 1 to 3, which have excellent transparency, as well as excellent releasability and mechanical strength, while maintaining the same molding durability as the comparative example, than the comparative example The result was good transparency.
On the other hand, in Comparative Example 1 using a composition comprising a linear organopolysiloxane not containing a phenyl group, an organohydrogenpolysiloxane not containing a phenyl group, silica, etc., the transparency is much greater than in Examples 1-3. It was inferior to. Moreover, in Comparative Examples 2 and 3 using compositions in which the phenyl group content in the component (A) deviated from the specified value of the present invention, the transparency was significantly inferior to Examples 1 to 3.

  As described above, the present invention has been described with the embodiments. However, the present invention is not limited to the above-described embodiments, and those skilled in the art will conceive other embodiments, additions, changes, deletions, and the like. It can be changed within the range that can be performed, and any embodiment is included in the scope of the present invention as long as the effects of the present invention are exhibited.

Claims (5)

(A) The viscosity at 25 ° C. is 10 to 100,000 mPa · s, has two or more monovalent aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in one molecule, and has 4 to 16 phenyl groups. 100 parts by mass of a linear organopolysiloxane containing mol%,
(B) SiO ₂ unit and (R ¹ ) ₃ SiO _0.5 unit (wherein R ¹ is independently a monovalent hydrocarbon group containing no vinyl group, allyl group or aliphatic unsaturated bond). 0 to 100 parts by mass of an organopolysiloxane having a three-dimensional network structure in which 4 to 16 mol% of R ¹ is a phenyl group
(C) The hydrogen atom bonded to the silicon atom has 3 or more hydrogen atoms in one molecule, and the monovalent organic group bonded to the silicon atom is an unsubstituted or halogen-substituted alkyl group or aryl group, 0.1 to 30 parts by mass of an organohydrogenpolysiloxane in which the number of moles of phenyl groups is 4 mol% or more with respect to the total number of moles of atoms and silicon atom-bonded organic groups;
(D) 10 to 50 parts by mass of silica fine powder having a specific surface area of 50 m ² / g or more,
(E) Platinum compound 0.1 to 1,000 ppm in terms of platinum atom mass
A silicone rubber molding material comprising a composition containing The (R ¹ ) ₃ SiO _0.5 unit of the component (B) is composed of (R ¹¹ ) ₃ SiO _0.5 unit (R ¹¹ is an alkyl group having 1 to 4 carbon atoms) and R ¹¹ PhR ¹² SiO _0.5 unit (R ¹¹ 2. The silicone rubber molding material according to claim 1, comprising: an alkyl group having 1 to 4 carbon atoms, Ph is a phenyl group, and R ¹² is a vinyl group or an allyl group.   (D) The silicone rubber molding material according to claim 1 or 2, wherein the silica fine powder is fumed silica surface-treated with organosilazanes.   The silicone rubber molding material according to any one of claims 1 to 3, wherein a difference in refractive index between the organopolysiloxane (A) and the silica fine powder (D) is within ± 0.02.   The silicone rubber molding material according to any one of claims 1 to 4, wherein the cured product of the silicone rubber molding material has a total light transmittance of 90% or more in accordance with JIS K 7105-1981.