JP7107276B2 - Molding agent for glass - Google Patents

Description

TECHNICAL FIELD The present invention relates to a silicone rubber composition for molding, and more particularly to an addition-curing silicone rubber composition for molding used for making a silicone mold (so-called female mold).

Conventionally, silicone rubber has been widely used in various fields, taking advantage of its excellent heat resistance, cold resistance, and electrical properties. ing.
Especially in the fields of electronic equipment, business machines, home appliances, automobile parts, etc., it is effective in improving cost and time required for prototype molding used at the product development stage and product sample production, and workability. Addition reaction type liquid silicone rubber compositions have come to be widely used as molding materials using silicone rubber compositions, because of their excellent properties such as good adhesion.

In addition, as silicone rubber compositions with improved mold releasability, a silicone rubber composition containing a water-in-oil emulsion containing dimethyl silicone oil as an oil layer (Patent Document 1), an oil-bleeding silicone rubber composition (Patent Document 1). Document 2), a silicone rubber composition containing a higher fatty acid or a metal salt of a higher fatty acid (Patent Document 3), a silicone rubber composition containing a dimethylpolysiloxane having an alkoxysilyl group at the molecular end (Patent Document 4), water A compounded silicone rubber composition (Patent Document 5) and the like have been proposed.

However, even when the silicone rubber composition as described above is used as a silicone rubber mold for a glass master, there is a problem of insufficient releasability.
There is also known a method of blending a wax that is solid at room temperature as a release agent (Patent Document 6), but this method results in insufficient dispersibility of the release agent in the liquid silicone rubber composition at room temperature. or the fluidity of the composition is impaired.

Japanese Patent Application Laid-Open No. 2001-098153 Japanese Patent Application Laid-Open No. 2002-188008 Japanese Patent No. 2686903 Japanese Patent No. 5319905 JP-A-9-143372 Japanese Patent Application Laid-Open No. 2004-107373

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silicone rubber composition for molding which gives a silicone rubber cured product which is excellent in releasability from a glass master.

As a result of intensive studies by the present inventors to solve the above problems, the present inventors have found that a silicone rubber composition containing chain saturated hydrocarbons that is liquid at room temperature exhibits releasability from a glass master, and that silicone rubber for mold making. They found that it was suitable as a composition, and completed the present invention.

That is, the present invention
1. (A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule: 100 parts by mass;
(B) Organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: Silicon atom in component (B) per silicon-bonded alkenyl group in component (A) The amount that the number of hydrogen atoms bonded to is 0.5 to 5.0,
(C) a hydrosilylation reaction catalyst; and (D) 0.1 to 10 parts by mass of a linear saturated hydrocarbon that is liquid at 1 atm and 25°C.
2. (E) the silicone rubber composition for molding according to 1, containing 5 to 300 parts by mass of silica per 100 parts by mass of component (A);
3. 1 or 2 silicone rubber composition for molding, wherein the chain saturated hydrocarbon is an alkane represented by C _n H _2n+2 (wherein n is an integer of 5 to 16);
4. A molding agent for glass comprising the silicone rubber composition for molding according to any one of 1 to 3,
5. A silicone rubber mold obtained by curing the silicone rubber composition for mold making according to any one of 1 to 3 is provided.

The silicone rubber mold obtained by curing the silicone rubber composition for mold making of the present invention is excellent in releasability from the glass master, and thus productivity can be improved.

The present invention will be specifically described below.
In the present invention, the silicone rubber composition for molding means that it has fluidity in an uncured state and is brought into contact with the entire surface or a part of the surface of the master by a method such as casting or coating. It refers to an uncured (liquid) composition that is cured in a state to form a mold (mold for molding) that is used for duplication with resin or the like.
In the present invention, the releasability is a term that includes not only the releasability of the hardened mold (mother mold) from the original mold, but also the releasability of the duplicate product from the obtained mold (mother mold). use.

The silicone rubber composition for molding according to the present invention contains the following components (A) to (D).
(A) Organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule (B) Organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule (C) Addition Reaction catalyst (D) chain saturated hydrocarbon liquid at 25°C

[1] Component (A) Component (A) is an organopolysiloxane having at least 2, preferably 2 to 10, more preferably 2 to 5 silicon-bonded alkenyl groups per molecule. If the number is less than 2, curing of the composition will be insufficient. Although the upper limit is not particularly limited, it is preferably 10 or less in order to prevent the cured product from becoming brittle.
The alkenyl group bonded to a silicon atom is not particularly limited, and may be linear, branched, or cyclic. to 8 are preferred, those with 2 to 4 carbon atoms are more preferred, and a vinyl group is even more preferred.
The alkenyl group may be present at either or both of the molecular chain terminal and the molecular chain non-terminal (that is, the molecular chain side chain), but is preferably present at least at both molecular chain terminals.

In the organopolysiloxane of component (A), the organic group other than the alkenyl group bonded to the silicon atom is not particularly limited as long as it does not have an addition-reactive carbon-carbon unsaturated bond. Any of may be used, but a monovalent hydrocarbon group having 1 to 20 carbon atoms is preferable, a monovalent hydrocarbon group having 1 to 10 carbon atoms is more preferable, and a monovalent hydrocarbon group having 1 to 5 carbon atoms is Even more preferable.
Specific examples thereof include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl and n-hexyl groups; cyclic alkyl groups such as cyclohexyl groups; phenyl and tolyl groups. aryl groups such as benzyl; and aralkyl groups such as benzyl and phenylethyl groups.
Further, some 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. Specific examples of such groups include Halogen-substituted hydrocarbon groups such as 3,3,3-trifluoropropyl group; cyano-substituted hydrocarbon groups such as 2-cyanoethyl group;
Among these, a methyl group is preferred.

Component (A) includes, for example, an organopolysiloxane represented by the following average compositional formula (1).
^R2cR3dSiO ₍ 4- _{cd )/2} ⁽ 1)
(In the formula, each R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group having no addition-reactive carbon-carbon unsaturated bond, and each R ³ independently represents an alkenyl group. , c is a number that satisfies 1.9 to 2.1, d is 0.005 to 1.0, and c + d is a number that satisfies 1.95 to 3.0.)

Examples of the monovalent hydrocarbon group for R ² include the same groups as those exemplified above as the silicon-bonded organic group other than the alkenyl group, but the methyl group is preferred.
As the alkenyl group for R ³ , the same groups as those exemplified above as the silicon-bonded alkenyl group can be mentioned, but a vinyl group is preferred.
c is preferably a number of 1.95 to 2.0, d is preferably a number of 0.01 to 0.5, and c+d preferably satisfies 1.96 to 2.5.

Component (A) represented by the average compositional formula (1) includes, for example, organopolysiloxanes represented by the following formulas (3) to (9), but is not limited thereto.
^{ViR22SiO (} _R22SiO ) _e ^SiR22Vi _{( 3} )
ViR ² ₂ SiO(R ² ViSiO) _f (R ² ₂ SiO) _g SiR ² ₂ Vi (4)
_Vi2R2SiO ^{( R22SiO} ) _{e SiR2Vi2 (} ⁵ )
_{Vi3SiO (} ^R22SiO ) _{e SiVi3} (6)
Vi ₂ R ² SiO(R ² ViSiO) _f (R ² ₂ SiO) _g SiR ² Vi ₂ (7)
_Vi3SiO ( ^R2ViSiO ) _f ( ^R22SiO ) _{g SiVi3 (} 8)
^{R23SiO (} _R2ViSiO ) _h ( ^R22SiO ) _{g SiR23} ⁽ ₉ )
(In the formula, Vi means a vinyl group (same below). R ² has the same meaning as above.)

In each of the above formulas, e, f, and g are integers of 0 or more.
In particular, e is preferably an integer satisfying 10≦e≦10,000, more preferably an integer satisfying 50≦e≦2,000.
In addition, f and g are preferably integers satisfying 10≦f+g≦10,000 and 0≦f/(f+g)≦0.2, and more preferably integers satisfying 50≦f+g≦2,000.
h is an integer of 2 or more. )
h is an integer of 2 or more, preferably an integer satisfying 2 ≤ h, 10 ≤ f + g ≤ 10,000, and 0 ≤ h / (g + h) ≤ 0.2, and 50 ≤ g + h ≤ 2,000 A satisfying integer is more preferred.

The viscosity of component (A) at 25° C. is preferably 1 to 100,000 mPa·s, more preferably 5 to 10,000 mPa·s. If the kinematic viscosity is within this range, the fluidity is high and the workability is excellent. Viscosity in the present invention is a value measured using a rotational viscometer.
In addition, (A) component may be used individually by 1 type, or may use 2 or more types together.

[2] Component (B) Component (B) is an organo having at least 2, preferably 2 to 200, more preferably 3 to 100 hydrogen atoms (that is, SiH groups) bonded to silicon atoms per molecule. It is a hydrogenpolysiloxane and acts as a cross-linking agent by hydrosilylation reaction with alkenyl groups in component (A).

Component (B) includes, for example, an organohydrogenpolysiloxane represented by the following average compositional formula (2).
^R1aHbSiO ₍ 4- _{ab )/2} (2)
(In the formula, each R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group having no addition reactive carbon-carbon unsaturated bond, a is 0.7 to 2.1, b is 0.001 to 1.0, and a + b is a number that satisfies 0.8 to 3.0.)

Examples of the monovalent hydrocarbon group for R ¹ include the same groups as those exemplified for R ² of component (A), but a methyl group is preferred.
The number a is preferably from 1.0 to 2.0, the number b is preferably from 0.01 to 1.0, and the number a+b is preferably from 1.1 to 2.6.

The molecular structure of component (B) is not particularly limited, and examples thereof include linear, cyclic, branched, and three-dimensional network structures (resinous), with linear or cyclic being preferred.
In addition, the SiH groups in component (B) may be present at either or both of the molecular chain terminals and the molecular chain non-terminals (that is, the molecular chain side chains).
The content of SiH groups in component (B) is preferably in the range of 0.001 to 0.02 mol, more preferably in the range of 0.002 to 0.017 mol, per 1 g of component (B).

The kinematic viscosity of component (B) at 25° C. is not particularly limited, but is from 1 to 1,000 mm ² /s because the workability of the composition and the mechanical properties of the cured product are more excellent. is preferred, and 5 to 200 mm ² /s is more preferred. Considering that this viscosity range is satisfied, the number (or the degree of polymerization) of silicon atoms in one molecule of component (B) organohydrogenpolysiloxane is preferably 2 to 400, more preferably 3 to 200, More preferably 4 to 100. The kinematic viscosity in the present invention is a value measured using a Canon-Fenske viscometer.

The organohydrogenpolysiloxane of component (B) includes, for example, linear organohydrogenpolysiloxanes represented by the following average formulas (11) to (13), and cyclic organohydrogenpolysiloxanes represented by the following average formula (14). Hydrogenpolysiloxanes are preferred.
_{R13SiO(R12SiO)i [} ^{R1 (} _H )SiO] _j ^SiR13 ₍ ¹¹ )
R12(H)SiO( _R12SiO ) ⁱ [ ^R1 ₍ H)SiO] _j ^Si (H) _{R12 (} ¹² )
R ₁₃ SiO[R ¹ ₍ H)SiO] _k SiR ¹³ ( ¹³ )
[R ¹ (H)SiO] _m (14)
(wherein R ¹ has the same meaning as above, i is an integer of 5 to 40, j is an integer of 5 to 20, k is an integer of 2 to 30, and m is , an integer from 4 to 8.)

Specific examples of the (B) component organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclopolysiloxane, Dimethylsiloxane/methylhydrogensiloxane cyclic copolymer, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both molecular chain ends, trimethyl at both molecular chain ends Siloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer, both molecular chain ends trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane/methylphenylsiloxane copolymer, both molecular chain ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane , dimethylsiloxane/methylhydrogensiloxane copolymer with dimethylhydrogensiloxy group-blocked at both molecular chain ends, dimethylsiloxane/methylphenylsiloxane copolymer with dimethylhydrogensiloxy group-blocked at both molecular chain ends, dimethylhydrogensiloxy at both molecular chain ends group-blocked methylphenylpolysiloxane, a siloxane unit represented by ( _CH3 )2HSiO1 _{/2 ,} a siloxane unit represented by ( _CH3 ) _3SiO1 / ₂ , and a siloxane unit represented by _SiO4/2 ; a copolymer consisting of a siloxane unit represented by (CH ₃ ) ₂ HSiO _1/2 and a siloxane unit represented by SiO _4/2 , and two or more of these organopolysiloxanes A mixture etc. are mentioned.
More specific examples include organohydrogenpolysiloxanes represented by the following formula. In the formula, Me means a methyl group (same below).

（式中、シロキサン単位の配列順は任意である。）

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

The amount of component (B) is such that the number of silicon-bonded hydrogen atoms in component (B) per silicon-bonded alkenyl group in component (A) is 0.5 to 5.0. and preferably 0.7 to 3.0. If the number is less than 0.5, the cross-linking will be insufficient, and as a result, the silicone rubber mold obtained by curing the composition will be tacky, and the releasability from masters and duplicates will be reduced. If the number exceeds 5.0, hydrogen gas is likely to be generated during curing to cause foaming, the surface irregularities of the silicone rubber mold reduce the duplication accuracy, and voids occur inside the cured product to reduce the rubber strength.
In addition, (B) component may be used individually by 1 type, or may use 2 or more types together.

[3] Component (C) Component (C) is a hydrosilylation reaction catalyst for promoting the hydrosilylation reaction between the alkenyl groups in component (A) and the SiH groups in component (B).
Specific examples thereof include simple platinum group _metals such as _{platinum (} including _{platinum black} ), _rhodium , and _{palladium ; 6.nH2O} , _{Na2PtCl6.nH2O} , _{K2PtCl4.nH2O , PtCl4.nH2O , PtCl2 , Na2HPtCl4.nH2O ( wherein n} is ₀ to platinum chloride, chloroplatinic acid and chloroplatinates, such as an integer of 6, preferably 0 or 6; alcohol-modified chloroplatinic acid (see U.S. Pat. No. 3,220,972); Complexes of platinic acid and olefins (see U.S. Pat. Nos. 3,159,601, 3,159,662, and 3,775,452); platinum black, palladium, etc. A platinum group metal supported on a carrier such as alumina, silica, carbon; rhodium-olefin complex; chlorotris(triphenylphosphine) rhodium (Wilkinson catalyst); platinum chloride, chloroplatinic acid or chloroplatinate and vinyl group Platinum group metal-based catalysts such as complexes with containing siloxanes are included.
In addition, (C) component may be used individually by 1 type, or may be used in combination of 2 or more type.

The amount of component (C) is not limited as long as it promotes the curing (hydrosilylation reaction) of the composition. The amount in the range of 0.1 to 1,000 ppm in terms of mass is preferable, the range of 1 to 500 ppm is more preferable, and the range of 3 to 100 ppm is even more preferable. Within this range, the reaction rate of the addition reaction is appropriate, and a cured product having high strength can be obtained.

[4] Component (D) Component (D) is a chain saturated hydrocarbon that is liquid at 1 atmosphere (1.013×10 ⁵ Pa) and 25° C., and cures the silicone rubber composition for molding of the present invention. It is a component that imparts releasability from the glass master to the silicone rubber mold obtained by the above.
Component (D) is not particularly limited as long as it is a chain saturated hydrocarbon that is liquid at 1 atm and 25° C. from the viewpoint of dispersibility and fluidity of the composition, but C _n H _2n+2 (formula where n is an integer of 5 to 16.) Among them, nonane (melting point: -53°C), decane (melting point: -30°C), tetradecane (melting point: 6°C) and the like are preferred. more preferred.

Component (D) is added in an amount of 0.1 to 10 parts by mass, preferably 0.1 to 3.0 parts by mass, per 100 parts by mass of component (A). If it is less than 0.1 parts by mass, the releasability of the cured silicone rubber from the glass master becomes insufficient. flow into minute parts is impaired.
In addition, (D) component may be used individually by 1 type, or may use 2 or more types together.

[5] Component (E) In order to improve physical strength such as hardness and tensile strength, silica may be added as component (E) to the silicone rubber composition for molding of the present invention.
Examples of silica include fumed silica, crystalline silica (quartz powder), precipitated silica, silica obtained by hydrophobizing the surface of these, and the like, and these may be used alone or in combination of two or more. .

Examples of such silica include hydrophilic silica such as Aerosil 130, 200, 300 (manufactured by Nippon Aerosil Co., Ltd.), Cabosil MS-5, MS-7 (manufactured by Cabot), Rheorosil QS-102, 103 (manufactured by fumed silica such as Tokuyama); Tokusil US-F (manufactured by Tokuyama Co., Ltd.); Nipsil LP (manufactured by Nippon Silica Industry Co., Ltd.); Fumed silica such as -812, R-812S, R-972, R-974 (manufactured by Nippon Aerosil Co., Ltd.), Rheorosil MT-10 (manufactured by Tokuyama Co., Ltd.); Nipsil SS series (Nippon Silica Industry Co., Ltd.) crystalline silica such as Crystalite (manufactured by Tatsumori Co., Ltd.), MIN-U-SIL (manufactured by US Silica Company), Imisil (manufactured by Illinois Mineral), etc. be done.

Although these silicas may be used as they are, they may be treated with a surface-treating agent to make the surface hydrophobic in advance, or the silica surface may be hydrophobized by adding a surface-treating agent when component (A) is kneaded. It is preferable to use Examples of surface treatment agents include alkylalkoxysilanes, alkylhydroxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, low-molecular-weight polysiloxanes, titanate-based treatment agents, fatty acid esters, etc., with alkyldisilazane being preferred, and alkyldisilazane being more preferred. is hexamethyldisilazane. These surface treatment agents may be used alone, or two or more of them may be used simultaneously or at different timings.
The amount of the surface treatment agent used is preferably 0.5 to 50 parts by mass, more preferably 1 to 40 parts by mass, and even more preferably 2 to 30 parts by mass with respect to 100 parts by mass of silica. When the amount of the surface treatment agent used is within the above range, no surface treatment agent or its decomposition products remain in the composition, fluidity is obtained, and an increase in viscosity over time can be suppressed.

Component (E) preferably has a BET specific surface area of 50 to 400 m ² /g, more preferably 100 to 350 m ² /g. Within such a range, sufficient rubber strength can be obtained.

When component (E) is used, the amount added is preferably 5 to 300 parts by mass, preferably 20 to 200 parts by mass, based on 100 parts by mass of component (A), from the viewpoint of the handling properties of the composition and the mechanical strength of the cured product. Parts by mass are more preferred.

[6] Component (F) In the silicone rubber composition for molding of the present invention, a hydrosilyl compound is added during preparation of the composition and prior to heat curing such as during molding so as to prevent thickening and gelling. For the purpose of controlling the reactivity of the reaction catalyst, (F) a reaction control agent may be added as necessary.
Specific examples of reaction control agents include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl cyclohexanol, ethynylmethyldecylcarbinol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane and the like can be mentioned, and these may be used alone or in combination of two or more.
Among these, 1-ethynylcyclohexanol, ethynylmethyldecylcarbinol, and 3-methyl-1-butyn-3-ol are preferred.

When component (F) is used, the amount added is preferably 0.01 to 2.0 parts by mass, preferably 0.01 to 0.1 parts by mass, with respect to the total of 100 parts by mass of components (A) and (B). part is more preferred. Within such a range, the effect of reaction control is sufficiently exhibited.

[7] Other Components In addition to the above components (A) to (F), the silicone rubber composition for molding of the present invention may contain other components as exemplified below, as long as the objects of the present invention are not compromised. You may
Other components include conductive agents such as iron oxide, carbon black, conductive zinc oxide, and metal powder; heat-resistant agents such as titanium oxide and cerium oxide; internal release agents such as dimethyl silicone oil; Sex imparting agents and the like can be mentioned.

The silicone rubber composition for molding of the present invention is prepared by mixing the above components (A) to (D), optional components (E) and (F), and other components with a kneader, planetary mixer or the like. It can be prepared by mixing by a known method used.
The silicone rubber composition for molding of the present invention comprises a first agent comprising components (A), (C), (D) and, if necessary, other components, and components (A) and (B). , (D) and, if necessary, a second agent consisting of other ingredients may be separately prepared, and the first agent and the second agent may be mixed before use to form a two-part composition. In addition, there may be a component commonly used in the first agent and the second agent. Storage stability can be further ensured by making the composition into such a two-pack type.

As for the curing conditions of the silicone rubber composition for mold making of the present invention, curing proceeds even at room temperature (5 to 35° C.), but curing can also be accelerated by heating, which is useful when it is desired to improve mass productivity. this method is effective.
In the case of heat curing, it is preferable to cure at 70 to 200° C. for 30 seconds to 60 minutes, particularly at 90 to 120° C. for 1 minute to 30 minutes.

EXAMPLES 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 Examples 1 to 3]
A silicone rubber composition was prepared by mixing the following components at the compounding ratio (parts by mass) shown in Table 1. Specifically, first, 85 parts by mass of component (A), 30 parts by mass of component (E), 5 parts by mass of hexamethyldisilazane, and 2 parts by mass of water were mixed using a kneader at 25°C for 30 minutes, and then heated to 150°C. The temperature is raised, stirring is continued for 4 hours, and after cooling to 25° C., 15 parts by mass of component (A) are mixed to obtain a silicone rubber base. After stirring and mixing with a mixer at 25°C for 15 minutes, component (B) is added, and the mixture is stirred and mixed with a planetary mixer at 25°C for 15 minutes. A composition was obtained.

(A) Component:
(A-1) Dimethylpolysiloxane (vinyl group content: 0.006 mol/100 g) having both ends blocked with dimethylvinylsiloxy groups and having a viscosity of 5,000 mPa·s at 25°C

（式中、シロキサン単位の配列はランダムまたはブロックである。） (B) Component:
(B-1) A dimethylsiloxane-methylhydrogensiloxane copolymer with trimethylsiloxy group-blocked dimethylsiloxane at both molecular chain ends represented by the following average formula (kinematic viscosity at 25°C: 99.0 mm ² /s, containing silicon-bonded hydrogen atoms amount = 0.0037 mol/g)

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

(C) Component:
(C-1) Dimethylsiloxane solution of platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (platinum content 1.0% by mass)

(D) Component:
(D-1) nonane (melting point: -53°C)
(D-2) Decane (melting point: -30°C)
(D-3) Tetradecane (melting point: 6°C)

(E) Component:
(E-1) Fumed silica (Nippon Aerosil Co., Ltd., Aerosil 300, BET specific surface area 300 m ² /g)

(F) Component:
(F-1) ethynylcyclohexanol

Using the obtained composition, each of the following properties was evaluated. Table 2 shows the results.
[Liquidity]
The compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were applied to glass plates at 25° C., and the fluidity of the compositions was visually observed. Those with sufficient fluidity were evaluated as ◯, and those with insufficient fluidity were evaluated as x.
[Peeling force]
The compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were applied to a glass plate and sandwiched between another glass plate so as to have a thickness of 0.2 mm. It was cured under the curing conditions of 10 minutes. The force required to separate two sheets of glass adhered via a cured product in the direction perpendicular to the adhered surface was confirmed.

As shown in Table 2, the silicone compositions for molding of the present invention prepared in Examples 1 to 4 exhibit fluidity, and the cured products obtained from these compositions exhibit releasability from glass. It can be seen that it is superior to
On the other hand, in Comparative Example 1 in which the component (D) was not added and in Comparative Example 2 in which the amount of the component (D) added was less than the range of the present invention, it became difficult to separate from the glass, and the amount of the component (D) added was low. In Comparative Example 3, which is excessive, the fluidity of the composition is lowered, and it is found that it is not suitable for molding.

Claims (3)

(A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule: 100 parts by mass;
(B) Organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: Silicon atom in component (B) per silicon-bonded alkenyl group in component (A) The amount that the number of hydrogen atoms bonded to is 0.5 to 5.0,
(C) a hydrosilylation reaction catalyst; and (D) 0.1 to 3.0 parts by mass of a chain saturated hydrocarbon that is liquid at 1 atm and 25°C. A molding agent for glass consisting of: 2. The molding agent for glass according to claim 1, wherein (E) silica is contained in an amount of 5 to 300 parts by mass per 100 parts by mass of component (A). 3. The molding agent for glass according to claim 1, wherein said chain saturated hydrocarbon is an alkane represented by C _n H _2n+2 (wherein n is an integer of 5 to 16).