JP3073884B2 - 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 is used in potting materials, coating materials, adhesives, liquid injection molding materials, etc., and is cured by a hydrosilylation reaction.

[0002]

2. Description of the Related Art A heat-curable silicone elastomer composition which is cured by a hydrosilylation reaction has advantages such as curing in a short time and not giving a reaction by-product, and is advantageous in potting materials, coating materials, adhesives, and the like. Used as a material for liquid injection molding. However, since the activity of the catalyst used in the hydrosilylation reaction is difficult to control, the heat-curable silicone elastomer composition has conventionally been used as a two-part composition. When this two-part composition is used for a coating material or the like, the two parts must be mixed at the time of use, and thus there is a problem in terms of workability such as complicated work.

In order to suppress the activity of the catalyst at room temperature, a one-part type heat-curable silicone elastomer composition containing a hydrosilylation reaction control agent has been proposed. As the controlling agent, for example, a nitrile compound; a carboxylate; a metal compound such as stannous or mercury; a sulfur compound; a benzotriazole; an acetylene compound; The one-part composition thus obtained had good stability at room temperature. However, there is a problem that the curability of the composition is remarkably lowered when the storage stability for a long time is to be obtained by adding a reaction control agent. In order to maintain the curability of the composition, the amount of the control agent had to be reduced, and as a result, the composition had low storage stability.

[0004] Therefore, without using a reaction control agent, a thermosetting curable composition obtained by adding a platinum-based catalyst in a silicone resin having a certain softening point (hereinafter referred to as a catalyst-containing resin) to an elastomer composition is added. One-part silicone elastomer compositions have been developed (JP-B-53-41707, JP-A-58-37053). However, in this method, when the platinum-based catalyst is sealed in the silicone resin, a small amount of the catalyst adheres to the surface of the resin. Since the curing of the elastomer composition is promoted even during storage by the catalyst attached to the surface of the catalyst-containing resin, the obtained one-pack type elastomer composition has storage stability (hereinafter, stability at room temperature for a long time and (Which means that the curability at high temperatures does not decrease).

Therefore, a composition has been proposed in which the catalyst-containing resin and the hydrosilylation reaction controlling agent are separately added (Japanese Patent Application Laid-Open No. 4-46962). The one-part heat-curable silicone elastomer composition thus obtained has good long-term stability at room temperature. However, in order to obtain this stability, an excessive amount of a reaction control agent had to be added to the composition. For this reason, since an excessive amount of the reaction control agent permeates the catalyst-containing resin with time, there is a problem that the composition has low storage stability, the curability at a high temperature is reduced with time, and the composition cannot withstand practical use. there were.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-curable silicone which is excellent in storage stability, has good stability at room temperature even when stored for a long period of time, and does not deteriorate its curability at high temperatures. It is to provide an elastomer composition.

[0007]

Means for Solving the Problems The inventors of the present invention have studied to achieve the above object, and as a result, have found that a fine powder of a thermoplastic resin containing a platinum catalyst for a hydrosilylation reaction and a hydrosilylation reaction controlling agent is obtained. Alternatively, when particles are added, surprisingly, the heat-curable silicone elastomer composition having excellent storage stability, that is, stable at room temperature even when stored for a long period of time, but maintains good curability at high temperatures. The inventors have found that an elastomer composition can be obtained, and have reached the present invention.

That is, the present invention relates to (A) a fine powder of a thermoplastic resin containing a platinum-based catalyst for a hydrosilylation reaction and a hydrosilylation reaction controlling agent.
Powder or particles, (B) organopolysiloxane unsaturated aliphatic hydrocarbon groups bonded to silicon atoms having 2 or more in the molecule, and, (C) at least two hydrogen atoms bonded to silicon atoms in the molecule The present invention provides a heat-curable silicone elastomer composition containing an organohydrogenpolysiloxane.

[0009] (A) a thermoplastic resin containing a platinum catalyst and a reaction control agent a platinum-based fine powder or particles (A) component of the thermoplastic resin containing a catalyst and a hydrosilylation reaction retarder fine The powder or particles are added to crosslink the organopolysiloxane having an unsaturated aliphatic hydrocarbon group (B) and the organohydrogenpolysiloxane (C) by a hydrosilylation reaction.

Platinum-based catalyst Platinum-based catalysts include platinum and platinum-based compounds, and any platinum-based catalyst conventionally used in hydrosilylation reactions may be used. Examples thereof include platinum, chloroplatinic acid, platinum sulfide, sodium chloroplatinate, a complex of platinum and an olefin, and a complex of chloroplatinic acid and an alkenyl group-containing organosiloxane. These platinum-based catalysts may be supported on an inorganic compound such as silica, carbon black, alumina, or titanium oxide, or may be used as an alcohol solution. The platinum-based catalyst may be used alone or in combination of two or more. Among these platinum-based catalysts, a complex of chloroplatinic acid and divinylsiloxane is preferably used because of its high catalytic activity.

[0011] The content of the platinum catalyst is preferably 50 parts by weight or less, more preferably 100 parts by weight of the thermoplastic resin.
0.1 to 10 parts by weight. If the content is too large, it is difficult to control the hydrosilylation reaction. If the content is too small, sufficient curability of the composition cannot be obtained.

[0012] The hydrosilylation agent hydrosilylation agent, may be those conventionally known, for example, phosphorus compounds such as triphenylphosphine; tetramethylethylenediamine, nitrogen-containing compounds such as benzotriazole; propargyl alcohol, 1
Ethynylcyclohexanol, 1,1-dimethyl-3-
Acetylene compounds such as butynol; hydroperoxy compounds such as t-butyl hydroperoxide; tin compounds such as dibutyltin dilaurate and tin octylate; mercury compounds such as mercury (I) chloride; These compounds may be used alone or in combination of two or more. Among these compounds, an acetylene-based compound is preferable, and an organic compound having an alkynyl group and an alcoholic hydroxyl group is more preferable.

The content of the hydrosilylation reaction controlling agent is preferably 100 mol or less, more preferably 1 to 10 mol, per 1 mol of platinum atom of the platinum-based catalyst. If the content is too large, a composition having sufficient curability cannot be obtained,
On the other hand, when the amount is too small, it becomes difficult to control the hydrosilylation reaction, and the stability of the obtained composition at room temperature decreases.

Thermoplastic resin Examples of the thermoplastic resin include vinyl polymers such as polyethylene and polystyrene, condensation polymers such as polyamide and polyester, and organic polymers such as silicone resin. These may be used alone or in combination of two or more. Among them, silicone resins are preferable, and more preferably, average composition formula (1): R _a SiO _{(4-a) / 2} (1) (where R is a monovalent organic group, and a is 1 to 3) 1.8, preferably 1 to 1.5). In the formula (1), the monovalent organic group represented by R has 1 to 1 carbon atoms having no aliphatic unsaturated bond.
12, preferably 1-8 substituted or unsubstituted hydrocarbons,
For example, an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, and a part or all of hydrogen atoms of an organic group such as a trifluoropropyl group, a chloromethyl group and a cyanoethyl group are halogenated. And a group substituted with an atom or a cyano group. These organic groups are
One kind alone or two or more kinds may be contained. More preferably, the proportion of phenyl groups in R in the formula is 50 mol% or more.

Preferred examples of the silicone resin represented by the formula (1) include, for example, (MeSiO _3/2 ) _n , (PhSiO _3/2 ) _n , and (CF ₃ C ₂ H ₄₎
SiO _3/2 ) _n , (MeSiO _3/2 ) _p (PhSiO _3/2 ) _q , (Vi
SiO _3/2 ) _p (PhSiO _3/2 ) _q , (Me ₂ SiO) _p (PhSi
O _3/2 ) _q , (MeViSiO) _p (PhSiO _3/2 ) _q , (Me ₃ S
iO _1/2 ) _p (SiO _4/2 ) _q , (Ph ₃ SiO _1/2 ) _p (SiO
_4/2 ) _q , (PhSiO _3/2 ) _x (MeSiO _3/2 ) _y (Ph ₂ SiO)
_z (where p, q, x, y and z are each an integer of 1 or more, and n, p + q and x + y + z are 10
And Me is a methyl group, Ph is a phenyl group, and Vi is a vinyl group. These silicone resins may be used alone or in combination of two or more.

Since the thermoplastic resin is used to prevent a hydrosilylation reaction by enclosing a platinum-based catalyst during storage at room temperature, it must be a stable solid at room temperature. Therefore, the resin preferably has a melting point or softening point of 40 to 150 ° C. If the melting point or softening point is too low, the catalyst will diffuse into the composition during storage at room temperature, causing curing by the hydrosilylation reaction. On the other hand, if the melting point or the softening point is too high, the temperature at which the composition is cured increases, and the required curability cannot be obtained. In addition, the thermoplastic resin must not dissolve into the composition after preparation.

The fine powders or particles of a thermoplastic resin containing a reaction control agent with the above platinum-based catalysts, it is not preferred to be uniformly dispersed in the composition upon its use. The <br/> fine powder or particles, preferably grain size 0.1 μm~1mm, 1μm~100 μm approximately is more preferable. Known methods can be used for producing fine powders or particles. Examples of this known method include a method using a spray dryer.

The amount of fine powder or particles (A) of the thermoplastic resin containing the platinum-based catalyst and the reaction control agent in the composition is such that the platinum content in the composition is more than that of the component (B). And preferably 1 to 1000 ppm, more preferably 10 to 100 ppm.
Is the range.

(B) Ol having an unsaturated aliphatic hydrocarbon group
The organopolysiloxane having two or more unsaturated aliphatic hydrocarbon groups bonded to silicon atoms in the molecule of the ganopolysiloxane (B) component is the main component of the heat-curable silicone elastomer composition of the present invention.

The unsaturated aliphatic hydrocarbon group of the above organopolysiloxane is usually one having 2 to 10 carbon atoms, preferably 2 to 4 carbon atoms, for example, alkenyl group such as vinyl group, allyl group and isopropenyl group. And the like, and preferably a vinyl group. One or more of these may be included. These unsaturated aliphatic hydrocarbon groups may be bonded to a silicon atom located at the terminal of the molecule and / or a silicon atom in the middle of the molecular skeleton, and preferably to a silicon atom at both ends of the molecular chain. I have. As the organic group other than the unsaturated aliphatic hydrocarbon group of the above organopolysiloxane, usually, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, for example,
Methyl group, ethyl group, alkyl group such as propyl group, phenyl group, aryl group such as tolyl group, trifluoropropyl group, chloromethyl group, part or all of the hydrogen atoms of the organic group such as cyanoethyl group is a halogen atom or And a group substituted with a cyano group. The organic group other than the unsaturated aliphatic hydrocarbon group in the organopolysiloxane molecule is not limited to one type.

The structure of the organopolysiloxane includes, for example, linear, branched, and cyclic structures. The structure of the organopolysiloxane is preferably linear. When the structure of the organopolysiloxane is linear, it may have a partially branched or cyclic skeleton.

When the above-mentioned organopolysiloxane is used as a liquid composition, it preferably has a degree of polymerization of 20 to 2,000, more preferably 50 to 500. When the composition is made into a non-liquid rubber, the organopolysiloxane preferably has a degree of polymerization of 2000 or more.

(C) Organohydrogenpolysiloxane In the molecule of the component (C), two hydrogen atoms bonded to a silicon atom are contained.
The organohydrogenpolysiloxane having at least one component is a component that forms a crosslink by a hydrosilylation reaction with the organopolysiloxane of the component (B). As an organic group other than a hydrogen atom of the organohydrogenpolysiloxane, a substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, usually having 1 to 12, preferably 1 to 8 carbon atoms, For example, an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, and a part or all of hydrogen atoms of an organic group such as a trifluoropropyl group, a chloromethyl group and a cyanoethyl group are halogenated. And a group substituted with an atom or a cyano group. The organic group in the organohydrogenpolysiloxane molecule is not limited to one type.

The structure of the organohydrogenpolysiloxane is, for example, linear, branched, or cyclic. The structure of the organohydrogenpolysiloxane is preferably linear. When the structure of the organohydrogenpolysiloxane is linear, it may have a partially branched or cyclic skeleton.

The above-mentioned organohydrogenpolysiloxane preferably has a degree of polymerization of 3 to 300, and more preferably has a degree of polymerization of 5 to 100. Examples of the organohydrogenpolysiloxane include those represented by the following formula. Me represents a methyl group. _{Me 3 SiO- (MeHSiO) m -} (Me 2 SiO) n - SiMe 3, in [wherein, m is an integer of 2 or more, n represents 0 or an integer, m
+ N is in the range of _{3 to} 100] HMe ₂ SiO- (Me ₂ SiO) _p- (MeHSiO) _q -SiHMe ₂ , wherein p is an integer of 0 or more, q is an integer of 0 or more,
p + q is in the range of 3-100.

Embedded image The content of the organohydrogenpolysiloxane in the composition is represented by hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane molecule / unsaturated fat bonded to silicon atoms in the organopolysiloxane molecule of the component (B). The molar ratio of the aromatic hydrocarbon group is preferably 1/10 to 12 /
1, more preferably in the range of 1/1 to 3/1. The component (c) may be used alone or in combination of two or more.

Other Ingredients The composition of the present invention may contain , if necessary, fine particles of silica, a filler such as calcium carbonate, a heat-resistant agent such as iron oxide, a flame retardant such as carbon black, an adhesion-imparting agent, and a thixotropic agent. An imparting agent or the like can be added.

Preparation of Composition The composition of the present invention is prepared , for example, by uniformly adding a predetermined amount of the above-mentioned components (A) to (C) and, if necessary, other compounding agents in a dry atmosphere. By mixing, it is obtained as a heat-curable composition. The preparation of this composition can be easily carried out by a device used for ordinary kneading, such as a kneader mixer or a roll mill.

[0028]

Examples of the present invention will be described below. The present invention is not limited at all by the following Examples. still,
In the following examples, H / Vi refers to a hydrogen atom bonded to a silicon atom in the organohydrogenpolysiloxane molecule used as the component (C) / a silicon atom in the organopolysiloxane molecule used as the component (B). Shows the molar ratio of the vinyl group bonded to. Hereinafter, parts by weight are simply referred to as parts.

(A) Preparation Example of Fine Powder or Particles of Thermoplastic Resin Containing Platinum Catalyst and Reaction Control Agent Catalyst (1) A silicone resin having a softening point of 80 ° C. (phenyltrichlorosilane) was placed in a glass container. 100 g of a mixture obtained by hydrolyzing a mixture of 70 mol%, 25 mol% of methyltrichlorosilane and 5 mol% of diphenyldichlorosilane was added to 50 g of dichloromethane.
Dissolved in 0 g. Then, 10 g of a toluene solution of platinum complex (a mixture obtained by neutralizing a mixture of chloroplatinic acid and divinyltetramethyldisiloxane with sodium hydrogen carbonate) (platinum content: 5% by weight) and 0.5 g of 1-ethynylcyclohexanol
And mixed and left overnight. Using a spray dryer (inlet temperature 90 ° C, outlet temperature 40 ° C), fine particles of silicone resin containing platinum complex etc. (average particle size)
20μ) 60 g were obtained. These fine particles were used as catalyst (1). catalyst
The platinum content of (1) was 0.4%.

Catalyst (2 ) A silicone resin containing a platinum complex or the like was prepared in the same manner as in the preparation of catalyst (1) except that 0.34 g of 1,1-dimethyl-3-butynol was used instead of 1-ethynylcyclohexanol. 60 g of fine particles (average particle size: 20 μ) were obtained. These fine particles were used as catalyst (2). The platinum content of the catalyst (2) was 0.4% by weight.

Catalyst (3 ) In the same manner as in the preparation of catalyst (1) except that 1-ethynylcyclohexanol was not added, 60 g of fine particles (average particle size: 20 μ) of a silicone resin containing a platinum complex were obtained. These fine particles were used as catalyst (3). The platinum content of catalyst (3) was 0.5% by weight.

Example 1 An aerosol obtained by treating 100 parts of α, ω-divinylmethylpolysiloxane having an average degree of polymerization of 500 with hexamethyldisilazane having a specific surface area of 170 m ² / g to make the surface hydrophobic with trimethylsiloxy units. 20 parts of silica were mixed to obtain a base compound. A siloxane represented by the formula: Me ₃ SiO- (MeHSiO) _5- (Me ₂ SiO) ₅ -SiMe ₃ (where Me is a methyl group) in 100 parts of the base compound
2.0 parts (prepared so that H / Vi = 2.7) and 0.5 g of the catalyst (1) obtained in the above preparation example were added and mixed uniformly.
The mixture was kneaded through this roll to obtain a composition I.

Comparative Example 1 A comparative composition i was obtained in the same manner as in Example 1 except that the catalyst (3) was used instead of the catalyst (1).

EXAMPLE 2 100 parts of α, ω-divinyldimethylpolysiloxane having an average degree of polymerization of 450 were treated with hexamethyldisilazane having a specific surface area of 130 m ² / g to render the surface hydrophobic with trimethylsiloxy units. 30 parts of silica was mixed to obtain a base compound. A siloxane represented by the formula: HMe ₂ SiO- (Me ₂ SiO) _5- (MeHSiO) ₃ -SiHMe ₂ (where Me is a methyl group) in 100 parts of the base compound
1.5 parts and formula:

Embedded image (Wherein, Me is a methyl group)
After adding 1.0 part (prepared so that H / Vi = 2.4) and 0.5 g of the catalyst (2) obtained in the above preparation example and mixing uniformly, 3
The mixture was kneaded through this roll to obtain a composition II.

Comparative Example 2 A toluene solution of a platinum complex having divinyltetramethyldisiloxane as a ligand instead of the catalyst (2) (platinum content: 0.5
% By weight) and 0.1 g of 1,1-dimethyl-3-butynol.
Comparative composition ii was obtained in the same manner as in Example 2 except that 8 g was added to the base compound.

Example 3 A polymerization degree of 6000 in which both ends were blocked with a dimethylvinylsilyl group.
100 parts of dimethylpolysiloxane raw rubber (vinyl content = 0.0020 mol / 100 g), 10 parts of α, ω-dihydroxydimethylpolysiloxane having an average degree of polymerization of 20 and specific surface area of 300 m ² / g
Was mixed with a kneader mixer at 160 ° C. for 4 hours to obtain a base compound. A siloxane represented by the formula: HMe ₂ SiO- (Me ₂ SiO) _5- (MeHSiO) ₃ -SiHMe ₂ (where Me is a methyl group) in 100 parts of the base compound
0.5 part (prepared so that H / Vi = 2.6) and 0.5 g of the catalyst (2) obtained in the above preparation example were added and mixed uniformly.
The mixture was kneaded through this roll to obtain a composition III.

Comparative Example 3 Comparative composition iii was prepared in the same manner as in Example 3 except that catalyst (3) and 0.35 g of 1,1-dimethyl-3-butynol were added to base compound instead of catalyst (2). Obtained.

[0038] Evaluation of the compositions obtained in Evaluation Examples and Comparative Examples of the composition was carried out by the following method. Table 1 shows the results. Curing Characteristics The curing characteristics at 150 ° C. of each of the compositions obtained in Examples and Comparative Examples were evaluated with a rheometer. For each composition, the time required to reach a predetermined torque was measured and compared. In Table 1, T10 indicates the maximum torque.
The time required to reach 10%, T90 is the maximum torque of 90
%. The composition after storage at 25 ° C. for a predetermined time was similarly evaluated for curing properties at 150 ° C.

Physical properties were press-cured at 120 ° C. for 5 minutes to prepare a sheet having a thickness of 2 mm, and physical properties were measured based on JIS K6301. The hardness was measured using an A-type spring hardness tester.

[0040]

[Table 1]

As shown in Table 1, there was a remarkable difference in curing properties between the examples and the comparative examples. Composition I exhibited the same curing properties as stored immediately after storage at 25 ° C. for 10 days. On the other hand, the comparative composition i
It gelled just after storage for 24 hours. Also, composition II contains 25
Even after storage at 1 ° C. for one month, the curing properties were the same as those immediately after preparation. In contrast, comparative composition ii gelled only after storage at 25 ° C. for 24 hours.

Composition III exhibited the same curing characteristics as immediately after preparation even after storage at 25 ° C. for 3 months. On the other hand, the comparative composition iii was stored at 25 ° C. for 3 months.
The curing properties at 150 ° C were considerably reduced. In addition, 25
Observation of Comparative Composition iii after storage at 3 ° C. for 3 months showed that the plasticity of the composition increased and a thin gelled film was formed on the surface.

[0043]

According to the present invention, a heat-curable silicone elastomer having excellent storage stability, that is, good stability at room temperature even after long-term storage, and good curability at high temperatures does not decrease. A composition is provided.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeo Yoshida 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Research Laboratory (56) References JP-A-4-46962 ( JP, A) JP-A-55-161851 (JP, A) JP-A-4-41562 (JP, A) JP-A-3-160054 (JP, A) JP-A-4-225066 (JP, A) Hei 2-145650 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/07 C08L 83/05 C09D 183/07 C09J 183/07

Claims (2)

(57) [Claims] 1. A fine powder or particles of a thermoplastic resin containing (A) a platinum-based catalyst for a hydrosilylation reaction and a hydrosilylation reaction controlling agent, (B) an unsaturated bond bonded to a silicon atom in a molecule. A heat-curable silicone elastomer composition comprising: an organopolysiloxane having two or more aliphatic hydrocarbon groups; and (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in a molecule. Stuff. 2. A method for producing a cured product, comprising curing the composition according to claim 1 by heating.