JPH0726147A - Thermoplastic silicone elastomer composition - Google Patents

Abstract

PURPOSE:To obtain a composition containing a thermoplastic resin, an organopolysiloxane and an organohydrogenpolysiloxane, excellent in shelf life and durability of excellent high-temperature curing properties and useful as a potting material, etc. CONSTITUTION:The composition contains (A) a thermoplastic resin containing a platinum-based catalyst for a hydrosilylation reaction and a hydrosilylation reaction inhibitor, (B) an organopolysiloxane having two or more unsaturated aliphatic hydrocarbon Groups each bonded to a silicon atom in the molecule and (C) an organohydrogenpolysiloxane having two or more hydrogen atoms each bonded to a silicon atom in the molecule.

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 and the like and which 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 a potting material, a coating material, an adhesive, It is 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 hitherto been used as a two-component composition. When this two-component composition is used as a coating material or the like, the two liquids must be mixed at the time of use, which causes a problem in workability such as complicated work.

Therefore, in order to suppress the activity of the catalyst at room temperature, a one-pack type thermosetting silicone elastomer composition to which a hydrosilylation reaction control agent is added has been proposed. As the control agent, for example, a nitrile compound; a carboxylate; a metal compound such as stannous and mercuric acid; a sulfur compound; a benzotriazole; an acetylene compound; a hydroperoxide and the like were used. The one-pack type composition thus obtained had good stability at room temperature. However, when it is attempted to obtain long-term storage stability by adding a reaction control agent, there has been a problem that the curability of the composition becomes extremely low. In order to maintain the curability of the composition, the amount of the control agent added had to be reduced, and as a result, the composition had low storage stability.

Therefore, a heat-curable resin prepared by encapsulating a platinum-based catalyst in a silicone resin having a certain softening point (hereinafter referred to as a catalyst-containing resin) is added to an elastomer composition without using a reaction control agent. A one-pack type silicone elastomer composition was developed (Japanese Patent Publication No. 53-41707 and Japanese Patent Publication No. 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. The catalyst attached to the surface of the catalyst-containing resin accelerates curing of the elastomer composition even during storage, so that the obtained one-pack type elastomer composition has storage stability (hereinafter, stability at room temperature and It means that the curability at high temperature does not deteriorate).

Therefore, a composition has been proposed in which the catalyst-containing resin and the hydrosilylation reaction control agent are added separately (JP-A-4-46962). The one-pack type heat-curable silicone elastomer composition thus obtained has good stability at room temperature for a long period of time. However, in order to obtain this stability, an excessive amount of reaction control agent had to be added to the composition. Therefore, since an excessive amount of the reaction control agent permeates the catalyst-containing resin over time, the composition has low storage stability, and the curability at high temperature decreases over time, which makes it unusable for practical use. there were.

[0006]

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

[0007]

Means for Solving the Problems As a result of studies to achieve the above object, the inventors have found that when a thermoplastic resin containing a platinum catalyst for a hydrosilylation reaction and a hydrosilylation reaction control agent is added, Surprisingly, it is possible to obtain a heat-curable silicone elastomer composition having excellent storage stability, that is, an elastomer composition which is stable at room temperature even after long-term storage but maintains good curability at high temperatures. This has led to the present invention.

That is, the present invention relates to (A) a thermoplastic resin containing a platinum-based catalyst for a hydrosilylation reaction and a hydrosilylation reaction control agent, (B) an unsaturated aliphatic bond bonded to a silicon atom in a molecule. A heat-curable silicone elastomer composition comprising an organopolysiloxane having two or more hydrocarbon groups, and (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule. provide.

(A) contains a platinum-based catalyst and a reaction control agent
Thermoplastic resin (A) component containing a platinum-based catalyst and a hydrosilylation reaction control agent, a thermoplastic resin containing an unsaturated aliphatic hydrocarbon group (B) component, and (C) component It is added to crosslink the organohydrogenpolysiloxane by a hydrosilylation reaction.

Platinum-based catalysts Platinum-based catalysts include platinum and platinum-based compounds, and any known 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. Further, these platinum-based catalysts may be supported on an inorganic compound such as silica, carbon black, alumina, titanium oxide, or used as an alcohol solution. The platinum-based catalysts 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.

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

Hydrosilylation Reaction Control Agent The hydrosilylation reaction control agent may be any conventionally known one, for example, phosphorus compounds such as triphenylphosphine; nitrogen-containing compounds such as tetramethylethylenediamine and benzotriazole; propargyl alcohol, 1-
Ethynyl cyclohexanol, 1,1-dimethyl-3-
Examples include acetylene compounds such as butynol; hydroperoxy compounds such as t-butyl hydroperoxide; tin compounds such as dibutyltin dilaurate and tin octylate; and mercury compounds such as mercury (I) chloride. You may use these compounds individually by 1 type or in combination of 2 or more types. Among these compounds, an acetylene 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 control agent is preferably 100 mol or less, more preferably 1 to 10 mol, per 1 mol of platinum atom of the platinum catalyst. When the content is too large, a composition having sufficient curability cannot be obtained,
On the other hand, if the amount is too small, it becomes difficult to control the hydrosilylation reaction, and the stability of the resulting 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. You may use these individually by 1 type or in combination of 2 or more types. Among these, silicone resin is preferable, and more preferably, average composition formula (1): _Ra SiO _{(4-a) / 2} (1) (wherein, R is a monovalent organic group, and a is 1 to 1). 1.8, preferably a number from 1 to 1.5). In the formula (1), the monovalent organic group represented by R has 1 to 10 carbon atoms having no aliphatic unsaturated bond.
12, preferably 1 to 8, substituted or unsubstituted hydrocarbons,
For example, part or all of hydrogen atoms of 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, an organic group such as a trifluoropropyl group, a chloromethyl group and a cyanoethyl group are halogenated. Examples include groups substituted with atoms or cyano groups. These organic groups are
They may be contained alone or in combination of two or more. It is more preferable that the ratio of phenyl groups in R in the formula is 50 mol% or more.

Preferred specific examples of the silicone resin represented by the formula (1) include, for example, (MeSiO _3/2 ) _n , (PhSiO _3/2 ) _n , (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 (however, in the above formula, p, q, x, y and z are each an integer of 1 or more, and n, p + q and x + y + z are 10
The above integers, Me is a methyl group, Ph is a phenyl group, and Vi is a vinyl group) and the like. These silicone resins may be used alone or in combination of two or more.

Since the thermoplastic resin is used to prevent the hydrosilylation reaction by encapsulating the platinum-based catalyst during storage at room temperature, it needs to be a stable solid state 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 and the curing due to the hydrosilylation reaction will occur. On the other hand, if the melting point or softening point is too high, the temperature at which the composition is cured becomes high, and the desired curability cannot be obtained. Also, the thermoplastic resin must be one that does not leach into the composition after preparation.

The thermoplastic resin containing the above platinum-based catalyst and the reaction control agent is preferably uniformly dispersed in the composition when it is used. The shape of the thermoplastic resin is not particularly limited, but it is preferably fine powder or particles. The fine powder or particles have a particle size of 0.1 μm to 1 mm.
Is preferable, and about 1 μm to 100 μm is more preferable. As a method for producing fine powder or particles, a known method can be used. Examples of this known method include a method using a spray dryer.

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

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

The unsaturated aliphatic hydrocarbon group of the above-mentioned organopolysiloxane usually has 2 to 10 carbon atoms, preferably 2 to 4 carbon atoms, for example, an alkenyl group such as vinyl group, allyl group and isopropenyl group. And the like, and preferably a vinyl group. These may be contained alone or in combination of two or more. 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, preferably to a silicon atom at both terminals of the molecular chain. There is. The organic group other than the unsaturated aliphatic hydrocarbon group of the above organopolysiloxane is usually a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, for example,
Alkyl group such as methyl group, ethyl group, propyl group, aryl group such as phenyl group, tolyl group, trifluoropropyl group, chloromethyl group, cyanoethyl group, etc. Examples thereof include groups 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.

Examples of the structure of the organopolysiloxane include 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 composition is in a liquid state, the above-mentioned organopolysiloxane preferably has a degree of polymerization of 20 to 2,000, more preferably 50 to 500. Further, when the composition is a non-liquid rubber, the organopolysiloxane preferably has a polymerization degree of 2000 or more.

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

Examples of the structure of the organohydrogenpolysiloxane include linear, branched and cyclic structures. 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, more preferably 5 to 100. Examples of the organohydrogenpolysiloxane include those represented by the following formula. In addition, Me shows a methyl group. Me ₃ SiO- (MeHSiO) _m- (Me ₂ SiO) _n -SiMe ₃ , [wherein m is an integer of 2 or more, n is an integer of 0 or more, m
+ N is in the range of _{3 to} 100] HMe ₂ SiO- (Me ₂ SiO) _p- (MeHSiO) _q -SiHMe ₂ , and [in the formula, p is an integer of 0 or more, q is an integer of 0 or more,
p + q is in the range of 3 to 100]

[Chemical 1] The content of the organohydrogenpolysiloxane in the composition is the hydrogen atom bonded to the silicon atom in the organohydrogenpolysiloxane molecule / (unsaturated fat bonded to the silicon atom in the organopolysiloxane molecule of component (B)). The molar ratio of the group hydrocarbon group is preferably 1/10 to 12 /
The range is 1 and more preferably 1/1 to 3/1. The component (c) may be used alone or in combination of two or more.

Other compounding agents In the composition of the present invention, if necessary, silica fine particles, a filler such as calcium carbonate, a heat-resistant agent such as iron oxide, a flame retardant such as carbon black, an adhesiveness-imparting agent, and thixotropy. An imparting agent or the like can be added.

Preparation of Composition In the composition of the present invention, for example, a predetermined amount of the above-mentioned components (A) to (C), and further other compounding agents which are added as necessary are uniformly mixed in a dry atmosphere. By mixing, a heat-curable composition is obtained. The composition can be easily prepared, for example, by an apparatus used for ordinary kneading such as a kneader mixer or a roll mill.

[0028]

EXAMPLES Examples of the present invention will be illustrated below. The present invention is not limited to the following examples. still,
In the following examples, H / Vi is 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). The molar ratio of vinyl groups bonded to is shown. In addition, hereinafter, parts by weight will be simply referred to as parts.

(A) contains a platinum-based catalyst and a reaction control agent
Preparation Example of Thermoplastic Resin Catalyst (1 ) Hydrolyze a mixture of silicone resin (70 mol% of phenyltrichlorosilane, 25 mol% of methyltrichlorosilane and 5 mol% of diphenyldichlorosilane) having a softening point of 80 ° C. in a glass container. 100 g of dichloromethane)
It dissolved in 0 g. Then, 10 g of a toluene solution of a platinum complex (obtained by neutralizing a mixture of chloroplatinic acid and divinyltetramethyldisiloxane with sodium hydrogencarbonate) (platinum content 5% by weight) and 0.5 g of 1-ethynylcyclohexanol
And were mixed and left overnight. Using a spray dryer (inlet temperature 90 ° C, outlet temperature 40 ° C), fine particles of silicone resin containing platinum complex (average particle size) from the above mixture
20 μ) 60 g was obtained. The fine particles were used as the catalyst (1). catalyst
The platinum content in (1) was 0.4%.

Catalyst (2 ) A silicone resin containing a platinum complex etc. 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 in place of 1-ethynylcyclohexanol. 60 g of fine particles (average particle size 20 μ) were obtained. The fine particles were used as the 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 the catalyst (1) except that 1-ethynylcyclohexanol was not added, 60 g of fine particles of a platinum complex-containing silicone resin (average particle size 20 μm) were obtained. The fine particles were used as the catalyst (3). The platinum content of the catalyst (3) was 0.5% by weight.

Example 1 100 parts of α, ω-divinylmethylpolysiloxane having an average degree of polymerization of 500 was treated with hexamethyldisilazane having a specific surface area of 170 m ² / g to make the surface hydrophobic with trimethylsiloxy units. 20 parts of silica was mixed to form a base compound. 100 parts of this base compound is a siloxane represented by the formula: Me ₃ SiO- (MeHSiO) _5- (Me ₂ SiO) ₅ -SiMe ₃ (wherein Me is a methyl group).
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, and then 3
The mixture was kneaded by passing through a main 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 in place of the catalyst (1).

Example 2 100 parts of α, ω-divinyldimethylpolysiloxane having an average degree of polymerization of 450 was treated with hexamethyldisilazane having a specific surface area of 130 m ² / g to make the surface hydrophobic with trimethylsiloxy units. 30 parts of silica was mixed to form a base compound. 100 parts of this base compound has a siloxane of the formula: HMe ₂ SiO- (Me ₂ SiO) _5- (MeHSiO) ₃ -SiHMe ₂ (wherein Me is a methyl group).
1.5 parts and formula:

[Chemical 2] (In the formula, Me is a methyl group) represented by the siloxane
1.0 part (prepared so that H / Vi = 2.4) and 0.5 g of the catalyst (2) obtained in the above Preparation Example were added and mixed uniformly, and then 3
The mixture was passed through this roll and kneaded to obtain a composition II.

Comparative Example 2 A toluene solution of a platinum complex having divinyltetramethyldisiloxane as a ligand in place of the catalyst (2) (platinum content: 0.5
Weight%) 0.05 g and 1,1-dimethyl-3-butynol 0.
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 Polymerization degree 6000 with both ends blocked with dimethylvinylsilyl groups
Dimethylpolysiloxane raw rubber (vinyl content = 0.0020 mol / 100g) 100 parts, α, ω-dihydroxydimethylpolysiloxane with an average degree of polymerization of 20 and 10 parts specific surface area 300 m ² / g
40 parts of fumed silica of No. 3 was kneaded with a kneader mixer at 160 ° C. for 4 hours to prepare a base compound. 100 parts of this base compound has a siloxane of the formula: HMe ₂ SiO- (Me ₂ SiO) _5- (MeHSiO) ₃ -SiHMe ₂ (wherein Me is a methyl group).
0.5 parts (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, and then 3
This was passed through a main roll and kneaded to obtain a composition III.

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

[0038] Evaluation of the compositions obtained in Evaluation Examples and Comparative Examples of the composition was carried out by the following method. The results are shown in Table 1. Curing characteristics The curability of each composition obtained in Examples and Comparative Examples at 150 ° C was evaluated by a rheometer. For each composition, the time required to reach a predetermined torque was measured and compared. In Table 1, T10 has the maximum torque.
The time required to reach 10%, T90 is the maximum torque of 90
Represents the time required to reach%. Further, the curing property at 150 ° C. was evaluated in the same manner for the composition after stored at 25 ° C. for a predetermined time.

Physical Properties Press-curing was carried out at 120 ° C. for 5 minutes to prepare a sheet having a thickness of 2 mm, and the physical properties were measured according to JIS K6301. The hardness was measured using an A type spring type hardness tester.

[0040]

[Table 1]

As shown in Table 1, in the curing characteristics, a remarkable difference was observed between the examples and the comparative examples. Composition I showed the same curing characteristics as immediately after preparation even after storage at 25 ° C. for 10 days. In contrast, Comparative Composition i at 25 ° C
It gelled only after being stored for 24 hours. Also, composition II is 25
Even after storage for 1 month at 0 ° C., it showed the same curing characteristics as immediately after preparation. On the other hand, the comparative composition ii gelled only after being stored at 25 ° C. for 24 hours.

Composition III also showed 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 shows that after being stored at 25 ° C. for 3 months,
The curing characteristics at 150 ° C were considerably deteriorated. In addition, 25
When the comparative composition iii after storage at 3 ° C. for 3 months was observed, 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 temperature does not deteriorate. A composition is provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeo Yoshida Inventor Takeo Yoshida 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (2)

[Claims] 1. A thermoplastic resin containing (A) a platinum-based catalyst for a hydrosilylation reaction and a hydrosilylation reaction control agent, and (B) an unsaturated aliphatic hydrocarbon group bonded to a silicon atom in a molecule. A heat-curable silicone elastomer composition containing two or more organopolysiloxanes and (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule. 2. A method for producing a cured product, which comprises heating and curing the composition according to claim 1.