JP3158903B2 - Heat-curable silicone elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-curable silicone elastomer composition which exhibits excellent storage stability at around room temperature and is cured by a hydrosilylation reaction having excellent curability at high temperatures.

[0002]

2. Description of the Related Art A heat-curable silicone elastomer composition which is cured by a hydrosilylation reaction has the advantages that the curing reaction can be performed in an extremely short time and that there are no reaction by-products. There are, as potting material, coating material, adhesive,
Alternatively, it is used for liquid injection molding and the like.

[0003] However, this heat-curable silicone elastomer composition has poor storage stability at around room temperature, so that it has to be stored in two components and both components must be mixed at the time of use. .

In order to solve this problem, a compound mainly controlling a hydrosilylation reaction, such as a metal compound such as a nitrile compound, a carboxylate, stannous or mercuric acid, a sulfur compound, Addition of benzotriazole, acetylene compounds, hydroperoxides, phosphorus compounds and the like has been performed. However, when trying to obtain long-term storage stability with these compounds, the curability of the composition becomes significantly worse,
There was a disadvantage that the time required for curing was long.

Further, in the above silicone elastomer composition, a method has been proposed in which the catalyst is physically sealed with a substance which is solid at around room temperature and becomes liquid at high temperature.
For example, Japanese Patent Publication No. 53-41707 discloses a method in which a substance in which a platinum catalyst is confined in a silicone resin having a softening point is added to the composition. However, according to the study of the present inventors, this method causes the dehydration reaction of the silanol group contained in the silicone resin with the hydrogen atom bonded to the silicon atom, so that the storage stability of the composition is prolonged, but the curing property is high. Had the drawback that it became worse.

[0006] Therefore, in a heat-curable silicone elastomer composition which is cured by a hydrosilylation reaction, improvement in storage stability and curability has been desired.

[0007] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a heat-curable silicone elastomer composition which has excellent storage stability at around room temperature and which is cured by a hydrosilylation reaction having excellent curability at high temperatures.

[0008]

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that an organic compound having two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. A heat-curable silicone elastomer composition containing a polysiloxane, an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule, and, if necessary, a hydrosilylation reaction control agent, is subjected to a hydrosilylation reaction. The catalyst has a melting point or softening point of 40 to 150 ° C. and SiO
By blending a thermoplastic silicone resin containing platinum or a platinum-based compound in which the H group is adjusted to 0.3 mol% or less, a dehydrogenation reaction between silanol groups contained in the silicone resin and hydrogen atoms bonded to silicon atoms. It has been found that the curing characteristics at high temperatures can be remarkably improved while maintaining good storage stability at around room temperature, and the present invention has been accomplished.

Accordingly, the present invention provides: (1) an organopolysiloxane having two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and (2) a hydrogen bonded to a silicon atom in one molecule. An organohydrogenpolysiloxane having two or more atoms, and (3) a thermoplastic silicone resin containing platinum or a platinum-based compound, wherein the thermoplastic silicone resin comprises:
R _m SiX _(4-m) (where R is an unsubstituted or substituted monovalent hydrocarbon group, X is a monovalent hydrolyzable group, and m is 0, 1, 2
Or 3) containing one or more of the organosilane compounds represented by R _n SiX _(4-n) (provided that
R and X are the same as described above, and n is from 1 to 1.8).
After condensation, it is obtained by silylating the SiOH group in the resin with a silylating agent to obtain R _n SiO _{(4-n) / 2} (provided that
R and n are the same as those described above) having a melting point or softening point of 40 to 150 ° C. and a SiOH group in the resin of 0.3
Disclosed is a heat-curable silicone elastomer composition comprising a thermoplastic silicone resin in an amount of at most mol%.

Hereinafter, the present invention will be described in more detail. The first component of the heat-curable silicone elastomer composition of the present invention comprises two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. And preferably 2 to 10 organopolysiloxanes. This is a component that is a main component of the composition of the present invention, and any of those known as heat-curable silicone elastomer compositions can be used.

As the organopolysiloxane, those represented by the following average composition formula (1) can be used. R ¹ _a SiO _{(4-a) / 2} ... (1)

In the formula, R ¹ is the same or different and is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10, preferably 1 to 8 carbon atoms, and a is 1.80 to 2.20, preferably It is a positive number in the range of 1.85 to 2.10.

The unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert- Butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group,
Octyl group, nonyl group, alkyl group such as decyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, benzyl group, phenylethyl group, aralkyl group such as phenylpropyl group, vinyl group, allyl group, Alkenyl groups such as propenyl group, isopropenyl group, butenyl group, isobutenyl group, hexenyl group, cyclohexenyl group, and octenyl group, and part or all of the hydrogen atoms of these groups are fluorine, bromine, and halogen atoms such as chlorine; Those substituted with a cyano group and the like, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group and the like can be mentioned.

In this case, at least two, preferably 2 to 10, of R ¹ are, as described above, an aliphatic unsaturated hydrocarbon group, particularly an alkenyl group (preferably one having 2 to 8 carbon atoms, more preferably Is 2 to 6). This aliphatic unsaturated hydrocarbon group may be bonded to a silicon atom at the terminal of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both. From the viewpoints of speed, physical properties of the cured product, and the like, the organopolysiloxane used in the present invention preferably contains at least an aliphatic unsaturated bond bonded to a silicon atom at a molecular chain terminal.

The above-mentioned organopolysiloxane is basically composed of repeating diorganosiloxane units and has a linear structure in which the molecular chain ends are blocked with triorganosiloxy units, but has a partially branched structure ( That is, it may contain a monoorganosiloxane unit) or may have a cyclic structure. In addition, the degree of polymerization, that is, the number of silicon atoms in the molecule is generally 20 or more, but is preferably 20 to 3000, more preferably 2 or more.
00 to 1500.

Next, the second component of the present invention comprises two or more, preferably 2 to 2, hydrogen atoms bonded to a silicon atom in one molecule.
An organohydrogenpolysiloxane having 100, more preferably 3 to 50, which is a component which serves as a crosslinking agent for the first component organopolysiloxane, which can be a known one. .

This organohydrogenpolysiloxa
As the components, those represented by the following average composition formula (2) are used.
Can be. R^Two _b(H )_CSiO_{(4-bc) / 2} … (2)

In the formula, R ² is the same or different and has 1 to 1 carbon atoms.
0, preferably 1 to 8 unsubstituted or substituted monovalent hydrocarbon groups, preferably those having no aliphatic unsaturated bond. b is a positive number of 1.6 ≦ b ≦ 2.2, and c is 0.002
≤ c ≤ 1.0, and 1.6 <b + c ≤ 3.0.

Here, the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ² includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert- Butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group,
Alkyl groups such as octyl group and decyl group, aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group, aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group, and hydrogen atoms of these groups Part or all of which are substituted with a halogen atom such as fluorine, bromine or chlorine, a cyano group or the like, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group and the like.

The organohydrogenpolysiloxane is, for example, basically a bifunctional siloxane unit (= Si
O _2/2 ), and a linear structure having a monofunctional siloxy unit (≡SiO _1/2 ) blocked, and a branched, cyclic, or three-dimensional network structure can be used. Some can be used.

Incidentally, a hydrogen atom (S) bonded to a silicon atom
The iH group) may be located at the terminal of the molecular chain, or may be located in the middle of the molecular chain.

The degree of polymerization of the organohydrogenpolysiloxane, that is, the number of silicon atoms in the molecule is preferably from 3 to 300.

The compounding amount of the organohydrogenpolysiloxane of the second component is determined by the number of hydrogen atoms (ie, SiH groups) bonded to silicon atoms contained in one molecule of the organopolysiloxane and the amount of the organopolysiloxane in the molecule of the first component. The molar ratio of the silicon atom contained to the aliphatic unsaturated hydrocarbon group to be bonded is 10: 1.
１ ： 1: 10, particularly preferably 3: 1 to 1: 3.

In the present invention, platinum or a platinum-based compound is contained as the third component and has a melting point or softening point of 40-1.
At 50 ° C and 0.3% by mole or less of SiOH groups in the resin, preferably 0.01 to 0.3% by mole, especially 0.0% by mole.
A thermoplastic silicone resin of 5 to 0.2 mol% is blended. Platinum or a platinum-based compound in the silicone resin is composed of an aliphatic unsaturated hydrocarbon group bonded to a silicon atom in the organopolysiloxane molecule of the first component and a silicon atom in the organohydrogenpolysiloxane molecule of the second component. It is a component that acts as a catalyst when a hydrogen atom to be bonded is crosslinked by a hydrosilylation reaction.

Here, as the silicone resin,
What is shown by following formula (3) is used suitably. R _nSiO_{(4-n) / 2} … (3)

In the above formula (3), R is an unsubstituted or substituted monovalent hydrocarbon group bonded to a silicon atom, preferably having 1 to 10 carbon atoms, especially 1 to 8 carbon atoms, and having an aliphatic unsaturated bond. Those that do not are preferred. Examples of such monovalent hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, and nonyl. Group, alkyl group such as decyl group, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, hexenyl group, alkenyl group such as cyclohexenyl group, aryl such as phenyl group, tolyl group, xylyl group Groups, benzyl groups, phenylethyl groups, aralkyl groups such as phenylpropyl group, and those in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, and chlorine, and cyano groups, for example, chloro Methyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl And the like. In this case, 50 mol% of R
The above is preferably a phenyl group, and as described above, R preferably has no aliphatic unsaturated bond. Further, in the formula (3), n is a positive number of 1 to 1.8, preferably 1 to 1.5.

The silicone resin has a melting point or softening point of 40 to 150 ° C., preferably 60 to 130 ° C. If the melting point or softening point is lower than 40 ° C., the catalyst component may be contained in the resin during storage of the composition. Therefore, storage stability cannot be maintained. On the other hand, when the temperature exceeds 150 ° C., the resin does not melt or soften effectively and quickly upon heating and curing, so that the catalyst component does not exude and it is difficult to carry out the curing effectively.

The silicone resin has a SiOH group content of 0.3 m with respect to all siloxane units in the resin.
ol% or less, preferably 0.01 to 0.3 mol%, more preferably 0.05 to 0.2 mol%. When the SiOH group content is more than 0.3 mol%, The dehydrogenation reaction between the contained silanol groups and the hydrogen atoms bonded to the silicon atoms in the second component organohydrogenpolysiloxane cannot be suppressed.

The silicone resin of the formula (3) is, for example, R _m SiX _(4-m) (where m is 0, 1, 2, or 3, and R is the same as described above. Is a monovalent hydrolyzable group similar to X in the general formula (4) described below.) The compound represented by the following formula (4) containing one or more of the organosilane compounds represented by the formula (4): After hydrolyzing and condensing the organosilicon compound or its mixture to be used, the compound can be easily produced by silylating the SiOH group in the resin with a silylating agent.

R _n SiX _(4-n) (4)

In the above formula (4), R and n are the same as described above. X is a monovalent hydrolyzable group, for example, a chlorine atom, a halogen atom such as a bromine atom, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methoxyethoxy group, an alkoxy group such as an ethoxyethoxy group, an allyloxy group, Propenyloxy group, alkenyloxy group such as isopropenyloxy group, acetoxy group, acyloxy group such as propionyloxy group, amino group such as dimethylamino group, diethylamino group, methylethylamino group, butylamino group, dimethylacetamide group, etc. Of these, an amide group and the like are preferable, and a chlorine atom or a methoxy group is particularly preferable.

The hydrolysis of the mixture of the organosilicon compound of the formula (4) can be carried out by a usual method using an acid or a basic catalyst. In this case, as the acid or basic catalyst,
Specific examples thereof include acid catalysts such as sulfuric acid, hydrochloric acid, methanesulfonic acid, and trifluoromethanesulfonic acid, and basic catalysts such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. 2% by weight is desirable.

Further, the silylation is carried out so that the content of SiOH groups in the resin is 0.3 mol% or less, for example, hexamethyldisilazane, trimethylfluorosilane,
N, O-bis (trimethylsilyl) acetamide, N-
It is desirable to use a silylating agent such as trimethylsilyl acetamide in the range of 1 to 5 mol based on the SiOH group equivalent in the resin, and to carry out the reaction at 25 to 100 ° C for 1 to 3 hours.

Examples of platinum or platinum compounds contained in the silicone resin include chloroplatinic acid, platinum sulfide, sodium chloroplatinate, alcohol compounds of chloroplatinic acid, complexes of platinum with olefin compounds, and the like. And the like are supported by an inorganic compound such as silica, carbon black, alumina, and titanium oxide. Among them, a complex compound of platinum and divinylsiloxane having high catalytic activity is preferably used. The content of the platinum or platinum-based compound is 50 parts or less, particularly 0.01 to 1 part, per 100 parts (parts by weight, the same applies hereinafter) of the silicone resin.
0 parts is preferable, and if it exceeds 50 parts, it becomes difficult to seal platinum in the resin, and the storage stability of the composition may be rapidly deteriorated.

In order to make the silicone resin contain platinum or a platinum compound, for example, the above-mentioned platinum resin is dissolved in an organic solvent such as dichloromethane (chlorine), toluene (hydrocarbon), acetone or hexane. Alternatively, it can be easily performed by adding and mixing a platinum compound and aging overnight.

The above-mentioned platinum or platinum-based compound-containing silicone resin is desirably used as fine particles. It is preferable that the silicone resin solution containing the above-mentioned platinum or platinum-based compound is made into fine particles by spraying with a spray dryer or the like. The average particle size of the fine particles is 1 to 10
A range of 0 μm, preferably 1 to 50 μm is suitable.

In the composition of the present invention, the amount of the platinum or platinum-containing compound-containing silicone resin is preferably 0.1 to 500 ppm, particularly 1 to 50 ppm, as platinum. , 0.1p
If it is less than pm, the curability of the composition may be poor, and if it exceeds 500 ppm, the preservability of the composition may be adversely affected. The amount of the platinum or platinum-based compound-containing silicone resin is 0.1 to 1000 ppm, preferably 1 to 10 ppm in terms of platinum weight relative to the first component.
The range may be 0 ppm.

In the present invention, it is preferable to add, as the fourth component, a hydrosilylation reaction control agent capable of delaying the onset time of curing of the composition at a high temperature and improving particularly the pot life and mold moldability. . As the hydrosilylation reaction control agent, those conventionally known can be used, for example, nitrogen-containing compounds such as tetramethylenediamine and benzotriazole, acetylene compounds such as propargyl alcohol,
Phosphorus compounds such as hydroperoxide and triphenylphosphine, nitrile compounds, carboxylate,
Examples thereof include metal compounds such as tin and mercury, and sulfur compounds. Among them, acetylene compounds are preferably used.

The amount of the hydrosilylation reaction controlling agent is from 0 to 100 parts by weight of the organopolysiloxane of the first component.
It is desirable to use one copy.

In addition to the above essential components, the composition of the present invention may contain, if necessary, a filler such as silica fine particles, calcium carbonate, a heat-resistant agent such as iron oxide, a flame retardant such as carbon black,
An adhesiveness-imparting agent, a thixotropy-imparting agent, and the like can be optionally added.

[0041]

The heat-curable silicone elastomer composition of the present invention has excellent storage stability at around room temperature and excellent curability at high temperatures, and is useful as a potting material, a coating material, and an adhesive. Alternatively, it can be widely used for liquid injection molding and the like.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. All parts in each example are parts by weight.

[Preparation Example] Preparation of Silicone Resin Containing Platinum Catalyst 70 mol% of phenyltrichlorosilane, 25 mol% of methyltrichlorosilane and 5 mol% of diphenyldichlorosilane were put in a glass container, and after hydrolyzing it, , 10 parts of hexamethyldisilazane,
Time silylated. The volatile components are distilled off under reduced pressure, and basically [C ₆ H ₅ SiO _3/2 ] _0.70 [CH ₃ SiO _3/2 ]
A silicone resin having a composition of _0.25 [(C ₆ H ₅ ) ₂ SiO _2/2 ] _0.05 , a softening point of 83 ° C., and 0.1 mol% of SiOH groups was obtained. 100 g of this silicone resin was dissolved in 500 g of dichloromethane. Next, chloroplatinic acid and tetramethyldivinyldisiloxane are neutralized with sodium hydrogencarbonate, and 25 g of a toluene solution of the platinum complex (platinum content: 2%) is mixed with the silicone resin solution and aged overnight. Was. When this solution was formed into fine particles by a spray drier (inlet temperature 90 ° C., outlet temperature 40 ° C.), 60 g of silicone resin fine particles (fine particle catalyst A) having an average particle diameter of 7 μm and a platinum content of 0.5% were obtained.

For comparison, as a silicone resin, [C ₆ H ₅ SiO _3/2 ] _0.70 [CH ₃ SiO
_3/2 ] _0.25 [(C ₆ H ₅ ) ₂ SiO _2/2 ] A silicone resin having a softening point of 90 ° C. and a SiOH group of 0.4 mol% before silylation with hexamethyldisilazane, having a composition of _0.05. By operating in the same manner as described above except for using the above, 60 g of silicone resin fine particles (fine particle catalyst B) having an average particle size of 8 μm and a platinum content of 0.5% were obtained.

Example 1, Comparative Example 1 Viscosity 10,000c
α, ω-divinyldimethylpolysiloxane 500 g
Was mixed with 150 g of fumed silica whose surface was hydrophobized with hexamethyldisilazane having a specific surface area of 150 m ² / g to obtain a base compound. Next, 2.0 g of methyl hydrogen polysiloxane represented by the following formula (i) was added to 100 g of the base compound, and 0.2 g of the silicone resin fine particle catalyst A obtained in the above Production Example and 0.05 g of ethynyl hexalol were further added. Was added and mixed uniformly, and then passed through a three-roll mill to obtain a silicone elastomer composition 1 (Example 1).

[0046]

Embedded image

For comparison, a silicone elastomer composition 2 was obtained in the same manner as in Example 1 except that the silicone resin fine particle catalyst B was used instead of the silicone resin fine particle catalyst A (Comparative Example 1).

The curing properties of the obtained silicone elastomer composition at 150 ° C. were measured with a rheometer. Here, T10 is a time until the torque becomes 10% of the maximum, and T90 is a time until the torque becomes 90% of the maximum.

Further, the silicone elastomer composition was placed in a closed container, stored at 40 ° C. for a predetermined time, and the time until the plasticity was lost was measured as the pot life.

The results are as shown in Table 1. The pot life was 15 days and the storage stability was good. However, the composition 2 was inferior to the composition 1 in curing properties at 150 ° C. In particular, T90 was found to be slow.

[0051]

[Table 1]

Example 2, Comparative Example 2 500 g of methylvinylpolysiloxane represented by the following formula (ii): 200 g of precipitated silica having a specific surface area of 400 m ² / g;
20 m ² / g of acetylene black 20 g
Heat treatment was performed at 50 ° C. for 2 hours to obtain a base compound.
Next, 100 g of the base compound was added to the following formula (ii)
5.0 g of methyl hydrogen polysiloxane shown in i) was added, and 0.3 g of the silicone resin fine particle catalyst A obtained in the above Production Example, 0.06 g of ethynyl hexalol and 2.5 g of heptane were further added. After mixing, the mixture was passed through a three-roll mill to obtain a silicone elastomer composition 3 (Example 2).

[0053]

Embedded image

For comparison, a silicone elastomer composition 4 was obtained in the same manner as in Example 2 except that the silicone resin fine particle catalyst B was used instead of the silicone resin fine particle catalyst A (Comparative Example 2).

The curing properties and the pot life of the obtained silicone elastomer composition at 150 ° C. were measured. The results are as shown in Table 2. The pot life was 10 days, and the storage stability was good. However, Composition 4 was inferior in curing properties at 150 ° C. as compared with Composition 3; Turned out to be slow.

[0056]

[Table 2]

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-46962 (JP, A) JP-A-4-55471 (JP, A) JP-A-5-247212 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08L 83/07 C08L 83/04 C08L 83/05

Claims (1)

(57) [Claims] 1. An organopolysiloxane having two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and (2) two hydrogen atoms bonded to a silicon atom in one molecule. An organohydrogenpolysiloxane having the above, and (3) a thermoplastic silicone resin containing platinum or a platinum-based compound, wherein the thermoplastic silicone resin comprises:
R _m SiX _(4-m) (where R is an unsubstituted or substituted monovalent hydrocarbon group, X is a monovalent hydrolyzable group, and m is 0, 1, 2
Or 3) containing one or more of the organosilane compounds represented by R _n SiX _(4-n) (provided that
R and X are the same as described above, and n is from 1 to 1.8).
After condensation, it is obtained by silylating the SiOH group in the resin with a silylating agent to obtain R _n SiO _{(4-n) / 2} (provided that
R and n are the same as those described above) having a melting point or softening point of 40 to 150 ° C. and a SiOH group in the resin of 0.3
A heat-curable silicone elastomer composition comprising a thermoplastic silicone resin in an amount of at most mol%.