JP4547169B2 - Organopolysiloxane composition - Google Patents

Description

  The present invention relates to an organopolysiloxane composition having excellent adhesion to a cured silicone rubber.

  Currently, organopolysiloxane compositions are widely used mainly in the electrical / electronic industry, the construction industry, the dentist industry, and the like. However, this material has a problem of poor adhesion to cured silicone rubber, and is very difficult to use for material joining and repair. As one method for solving this problem, there is a method of improving the adhesiveness by constituting all of the main chain of the organohydrogenpolysiloxane as a crosslinking agent with methylhydrogensiloxane units. There are problems that a dehydrogenation reaction tends to occur as a side reaction at the time of curing of the composition, and the curing rate at room temperature decreases.

  An object of the present invention is to provide an organopolysiloxane composition that suppresses a dehydrogenation reaction, which is a side reaction at the time of curing, and has a fast curing property at room temperature, and adheres well to a cured silicone rubber even at room temperature. Is to provide.

In order to achieve the above object, the present invention
(A) Diorganopolysiloxane having an alkenyl group at both ends of the molecular chain, containing 0.02 to 0.4 mol% of methylvinylsiloxane units, and having a viscosity at 23 ° C. of 100 to 150,000 mPa · s: 100 parts by weight
(B) Organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule: 0.1 to 30 parts by weight
(C) Platinum-based catalyst: effective amount,
and
(D) Filler: 1 to 300 parts by weight,
In particular, an organopolysiloxane composition suitably applied for adhesion to silicone rubber is provided.

  The present invention is described in detail below.

  The cured product of the organopolysiloxane composition of the present invention exhibits good adhesion to the cured silicone rubber as the substrate. Therefore, the organopolysiloxane composition can be used as a material having good adhesive strength after curing for jointing and repair. The composition of the present invention also suppresses the dehydrogenation reaction at the time of curing and maintains the rapid curability at room temperature. Therefore, application to the electrical / electronic industry, the construction industry, the dentist industry, etc. is also possible.

  The organopolysiloxane composition according to the present invention comprises the following components (A) to (D).

[(A) Diorganopolysiloxane]
The diorganopolysiloxane of the component (A) is a base polymer of the present composition, and is basically a straight chain in which the main chain is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. Having an alkenyl group at both ends of the molecular chain, methylvinylsiloxane units in the main chain, 0.02 to 0.4 mol%, preferably 0.04 to 0.2 mol%, based on all siloxane units in the molecule, The content is particularly preferably 0.1 to 0.2 mol%. When the methyl vinyl siloxane unit is less than 0.02 mol%, the adhesiveness to silicone rubber is weakened, and when it exceeds 0.4 mol%, the curing rate is lowered due to the control effect of the methyl vinyl siloxane unit.

Specific examples of the alkenyl group bonded to the silicon atoms at both ends of the molecular chain of the diorganopolysiloxane include, for example, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, pentenyl group, hexenyl group and the like. These are usually those having 2 to 6 carbon atoms, preferably vinyl groups. Usually, alkenyl groups bonded to silicon atoms at both ends of the molecular chain are dialkylalkenylsiloxy groups such as vinyldimethylsiloxy group, vinylmethylphenylsiloxy group, vinyldiphenylsiloxy group, allyldimethylsiloxy group, alkylarylalkenylsiloxy groups. And diorganoalkenylsiloxy groups such as diarylalkenylsiloxy groups.
Specific examples of the group bonded to the silicon atom other than the above alkenyl group include, for example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group; phenyl group, tolyl Aryl groups such as a group, xylyl group and naphthyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aralkyl groups such as benzyl group and phenethyl group; halogenated alkyl groups such as 3,3,3-trifluoropropyl group; Such as an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10, preferably 1 to 6 carbon atoms and not having an aliphatic unsaturated bond, preferably a methyl group and a phenyl group, Particularly preferred is a methyl group.

  The main chain may contain siloxane units other than methylvinylsiloxane units as siloxane units. Examples of such other siloxane units include dimethylsiloxane units, diphenylsiloxane units, and methylphenylsiloxane units. Or 2 or more types are preferable. In particular, the other siloxane units are preferably dimethylsiloxane units, dimethylsiloxane units and diphenylsiloxane units, or dimethylsiloxane units and methylphenylsiloxane units. When the other siloxane units are a dimethylsiloxane unit and a diphenylsiloxane unit, the diphenylsiloxane unit is 5 mol% or more, preferably 5 to 20 mol%, particularly preferably 7 to 5 mol% of the total siloxane units in the component (A). When the other siloxane unit is a dimethylsiloxane unit and a methylphenylsiloxane unit, the methylphenylsiloxane unit is 10 mol% or more, preferably 10 to 40 mol% of the total siloxane units in the component (A), Especially preferably, it is 14-30 mol%.

  The viscosity of the polydiorganosiloxane at 23 ° C. is 100 to 150,000 mPa · s, preferably 2,000 to 100,000 mPa · s, particularly preferably 3,000 to 10,000 mPa · s. If the viscosity at 23 ° C is less than 100 mPa · s, the physical properties such as elongation, tensile strength and tear strength after curing of this composition will be significantly reduced, and if it exceeds 150,000 mPa · s, this composition The handling workability is significantly reduced. The molecular structure of such a polydiorganosiloxane is preferably basically linear, but may be partially branched as long as the rubber elasticity of the cured product of the present composition is not impaired.

[(B) Organohydrogenpolysiloxane]
The (B) component organohydrogenpolysiloxane is a component that acts as a cross-linking agent and causes a hydrosilylation reaction with the (A) component to contribute to the curing of the composition. The organohydrogenpolysiloxane has at least two silicon-bonded hydrogen atoms (that is, SiH groups) in one molecule, preferably 3 to 500, more preferably 3 to 200, and particularly preferably 3 Have ~ 100. The number of silicon atoms (or the degree of polymerization) in one molecule is preferably 2 to 1,000, more preferably 3 to 300, and particularly preferably 4 to 150. The SiH group may be located at either the molecular chain end or the molecular chain non-terminal, or may be located at both.

  Specific examples of the group bonded to the silicon atom in the organohydrogenpolysiloxane include, for example, alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; a cyclopentyl group and a cyclohexyl group. A cycloalkyl group such as a group; an aryl group such as a phenyl group, a tolyl group and a xylyl group; an aralkyl group such as a benzyl group and a phenethyl group; a halogenation such as a 3,3,3-trifluoropropyl group and a 3-chloropropyl group Examples thereof include an unsubstituted or substituted monovalent hydrocarbon group which does not have an aliphatic unsaturated bond and is the same as those exemplified in the component (A), such as an alkyl group, preferably an alkyl group and an aryl group Particularly preferred are a methyl group and a phenyl group.

Such an organohydrogenpolysiloxane is preferably an average composition formula (1):
R ⁴ _b H _c SiO _{(4-b-c) / 2} (1)
Is used.

R ⁴ in the above formula (1) is preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms and having no aliphatic unsaturated bond bonded to a silicon atom. Examples of the unsubstituted or substituted monovalent hydrocarbon group represented by R ⁴ include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a neopentyl group. Alkyl groups such as hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, etc. And those obtained by substituting some or all of the hydrogen atoms of these groups with halogen atoms such as fluorine, bromine and chlorine, such as chloromethyl, chloropropyl, bromoethyl and trifluoropropyl groups. The unsubstituted or substituted monovalent hydrocarbon group represented by R ⁴ is preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group.

  In the above formula (1), b is a positive number of 0.7 to 2.1 and c is a positive number of 0.001 to 1.0, provided that b + c is a positive number of 0.8 to 3.0, preferably b is 1.0 to 2.0 and c is 0.01. It is a positive number of ˜1.0, where b + c is a positive number of 1.5 to 2.5.

The viscosity of component (B) at 23 ° C. is preferably 0.5 to 100,000 mPa · s, and particularly preferably 10 to 5,000 mPa · s. The molecular structure of such an organohydrogenpolysiloxane is not limited, and examples thereof include linear, branched, partially branched linear, cyclic, and three-dimensional network. The organohydrogenpolysiloxane may be a homopolymer composed of a single type of siloxane unit, a copolymer composed of two or more types of siloxane units, or a mixture thereof. Examples of the organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogensiloxane cyclic polymer, and methylhydrogensiloxane.・ Dimethylsiloxane cyclic copolymer, molecular chain both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane, methylhydrogen Siloxane copolymer, dimethylhydrogensiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer with both ends of the molecular chain, trimethylsiloxy group-capped methylhydrogensiloxane / dipheny with both ends Copolymer, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers, both end dimethylhydrogensiloxy group-blocked methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymers, (CH ₃ ) A copolymer comprising ₂ HSiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, and comprising (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units. And a copolymer comprising (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units, and (C ₆ H ₅ ) ₃ SiO _1/2 units. Among these, those containing 1 mol% or more of dimethylsiloxane units in the total amount of siloxane units in component (B) are preferred, and those containing 1 to 60 mol% are more preferred.

  In the present composition, the content of component (B) is 0.1 to 30 parts by weight, preferably 0.5 to 10 parts by weight, particularly preferably 1 to 7 parts by weight, based on 100 parts by weight of component (A). When the content of component (B) is less than 0.1 parts by weight, the composition is not sufficiently cured, and when it exceeds 30 parts by weight, the composition becomes excessively hard due to curing, and many cracks are formed on the surface. May occur. In addition, the compounding quantity of this (B) component is the silicon atom bond hydrogen atom in (B) component with respect to the total amount of the silicon atom bond alkenyl group in all the alkenyl group containing organopolysiloxane in this composition for said reason. (I.e., SiH group) molar ratio-when the component other than the component (A) does not have the alkenyl group, the silicon atom bonded hydrogen in the component (B) to the silicon atom bonded alkenyl group in the component (A) It can also be blended so that the molar ratio of atoms is 0.1 to 4.0 mol / mol, preferably 0.5 to 2.5 mol / mol, particularly preferably 0.8 to 2.0 mol / mol.

[(C) Platinum catalyst]
The platinum-based catalyst of component (C) is a catalyst for accelerating the curing of the present composition, and examples thereof include platinum and a platinum compound. Specific examples thereof include chloroplatinic acid, an alcohol solution of chloroplatinic acid, Examples include platinum olefin complexes, platinum alkenylsiloxane complexes, platinum carbonyl complexes, and the like. The content of the component (C) in the present composition may be an effective amount. Specifically, the platinum metal component in the component (C) is preferably converted on a weight basis with respect to the component (A) on a weight basis. The amount is 0.01 to 1000 ppm, more preferably 0.1 to 500 ppm.

[(D) filler]
The filler of the component (D) is an additive for reinforcing the cured product of the present composition. For example, fumed silica, wet fine powder silica, crystalline silica, carbon black, bengara, cerium oxide, Examples thereof include reinforcing fillers such as titanium oxide, calcium carbonate, aluminum hydroxide and titanate or non-reinforcing fillers, and fillers obtained by hydrophobizing the surface of these fillers with an organosilicon compound. Among these, fine powder silica or crystalline silica is preferable.

  The content of component (D) is 1 to 300 parts by weight, preferably 5 to 150 parts by weight, particularly preferably 20 to 150 parts by weight, based on 100 parts by weight of component (A). This is because if the content of the component (D) is less than 1 part by weight, the reinforcing effect on the cured composition is not sufficient, and if it exceeds 300 parts by weight, the cured composition becomes brittle.

[Other optional ingredients]
This composition contains at least the above-mentioned components (A) to (D), and is optionally added to the addition-curable silicone rubber composition as an optional component as long as the object of the present invention is not impaired. Known additives, for example, addition reaction inhibitors such as acetylene compounds, hydrazine compounds, phosphine compounds, mercaptan compounds, flame retardancy imparting agents, plasticizers, adhesion imparting agents, polyether chains You may contain a compound etc. Various cured silicone rubbers can be added by adding adhesion aids such as silane coupling agents such as methacryloxypropyltrimethoxysilane and organohydrogenpolysiloxane modified with allyl glycidyl ether and vinyltrimethoxysilane. In addition to this, it exhibits better adhesion to the cured product of the composition itself according to the present invention.

[Adhesive silicone rubber]
The composition of the present invention is particularly preferably used for adhesion to silicone rubber. Such silicone rubber is not limited in any way, for example, addition curing type, organic peroxide curing type, condensation curing type, etc. The silicone rubbers are particularly preferable, and addition-curable silicone rubbers are particularly preferable.

  The method for curing the composition in a state where it is adhered to the cured silicone rubber is not limited, for example, after molding the composition, contacting the cured silicone rubber and leaving it at room temperature (for example, 23 ° C.), the composition Examples include a method in which a product is molded and then brought into contact with cured silicone rubber and heated to 50 to 200 ° C.

  Thus, the properties of the silicone rubber obtained by curing the present composition are not limited, and examples thereof include a high hardness rubber shape to a low hardness rubber shape, that is, a gel shape. The resulting silicone cured product is obtained in a state where it is sufficiently adhered to the cured silicone rubber as the base material and has good handleability, so that the type A durometer hardness specified in JIS K6253 is within the range of 5 to 90. It is preferable that it is in the range of 10-60.

  Hereinafter, the present invention will be described in detail using examples and comparative examples. These do not limit the invention.

<Examples 1-5>
The following components (A) to (D) and reaction inhibitors as optional components were blended in a weight ratio as shown in Table 1, respectively. Numerical values indicating the amount of each component in Table 1 represent parts by weight. An organopolysiloxane composition was prepared by uniformly mixing them using a Shinagawa stirrer.

-Component (A)-
・ Base polymer A-1:
Molecular-chain-end vinyldimethylsiloxy-blocked dimethylsiloxane / methylvinylsiloxane copolymer
(Viscosity 5,000 mPas (23 ° C), methylvinylsiloxane unit content 0.11 mol%)

・ Base polymer A-2:
Molecular-end-chain vinyldimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane / methylvinylsiloxane copolymer
(Viscosity 30,000 mPas (23 ° C), methylvinylsiloxane unit content 0.2 mol%, diphenylsiloxane unit 10 mol%)

・ Base polymer A-3:
Molecular-chain-end vinyldimethylsiloxy-blocked dimethylpolysiloxane
(Viscosity 600mPa ・ s (23 ℃))

-(B) component-
・ Crosslinking agent B-1:
A trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity of 12 mPa · s at 23 ° C. (content of silicon-bonded hydrogen atoms = 0.43 wt%)

-(C) component-
・ Platinum catalyst:
Toluene solution of platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex with a platinum content of 0.5% by weight

-(D) component-
・ R-972 (Nippon Aerosil): Fine powder silica ・ Crystallite VX-S2 (manufactured by Tatsumori): Quartz powder

-Other optional components-
・ Reaction inhibitor: methylvinylcyclotetrasiloxane

  These obtained organopolysiloxane compositions were processed as follows, and evaluated and measured according to the evaluation criteria shown below. The results are shown in Table 1.

<Evaluation criteria>
[Curing property]
Curability was measured by the finger touch method. That is, an organopolysiloxane composition was molded, held in an atmosphere at 23 ° C., the center part of the surface of the composition was touched with a finger, and the time until the surface was free from stickiness was measured.

〔Hardness〕
Hardness was measured using a type A durometer hardness meter specified in JIS K6253 after molding an organopolysiloxane composition and curing it by holding it at 23 ° C. for 24 hours. did.

〔Adhesiveness〕
Pour the addition reaction curable silicone rubber composition as a base material into an aluminum petri dish with a diameter of 60 mm and a depth of 10 mm to a thickness of 10 mm, and cure at 23 ° C for 24 hours or more to form a silicone rubber layer (base material) Formed. Next, the organopolysiloxane composition prepared in Examples 1 to 5 was applied to this substrate to a thickness of 2 mm, and cured at 23 ° C. for 24 hours to be bonded. By pulling the end of the cured product layer of the organopolysiloxane composition adhered onto the substrate in a direction (vertical direction) of 90 degrees with respect to the cured product layer, the cured product of the organopolysiloxane composition and The adhesiveness with the cured silicone rubber as the base material was judged according to the following criteria.
○: The cured layer of the organopolysiloxane composition was destroyed (cohesive failure)
X: The cured product layer of the organopolysiloxane composition and the substrate peeled at the adhesive interface (interface peeling)

(成分の数値：重量部で配合量を示す)
^＊(Ａ)成分中のケイ素原子結合ビニル基に対する(Ｂ)成分中のケイ素原子結合水素原子のモル比を示す。

(Numerical values of ingredients: Indicate parts by weight)
^* Shows the molar ratio of silicon atom-bonded hydrogen atoms in component (B) to silicon-bonded vinyl groups in component (A).

<Comparative Examples 1-4>
In addition to the above components, the following components A-4 and B-2 were also used as necessary. Each was blended in a weight ratio as described in Table 2. Numerical values indicating the amount of each component in Table 2 represent parts by weight. An organopolysiloxane composition was prepared by uniformly mixing them using a Shinagawa stirrer.

-Component (A)-
・ Base polymer A-4:
Molecular-chain-end vinyldimethylsiloxy-blocked dimethylsiloxane / methylvinylsiloxane copolymer
(Viscosity 20,000 mPa · s (23 ° C), methylvinylsiloxane unit content 2 mol%)

-(B) component-
・ Crosslinking agent B-2:
Molecular hydrogen both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane with viscosity at 23 ° C of 5 mPa · s
(Content of silicon atom-bonded hydrogen atoms = 1.56 wt%)

  These obtained organopolysiloxane compositions were processed as described above, and evaluated and measured according to the evaluation criteria shown above. The results are shown in Table 2.

(成分の数値：重量部で配合量を示す)
^＊(Ａ)成分中のケイ素原子結合ビニル基に対する(Ｂ)成分中のケイ素原子結合水素原子のモル比を示す。

(Numerical values of ingredients: Indicate parts by weight)
^* Shows the molar ratio of silicon atom-bonded hydrogen atoms in component (B) to silicon-bonded vinyl groups in component (A).

[Evaluation]
As in Comparative Example 1, when the base polymer A-4 containing a specified amount or more of methylvinylsiloxane units in the main chain is used as the component (A), a composition having insufficient quick curability and hardness is obtained. As in Comparative Example 2, when the base polymer A-3 having no methylvinylsiloxane unit in the main chain is used as the component (A), a composition having poor adhesion to the cured silicone rubber is obtained. As in Comparative Example 3, when both the base polymer A-3 having no methylvinylsiloxane unit in the main chain and the base polymer A-4 containing the unit in a specified amount or more are used as the component (A), The fast curability is insufficient, and the composition takes a long time to cure. As in Comparative Example 4, in addition to the base polymer A-3 having no methylvinylsiloxane unit in the main chain as the component (A), a crosslinking agent of the component (B) not containing a dimethylsiloxane unit in the molecule When used, it becomes a composition having insufficient fast curability and hardness.

Claims (2)

Silicone rubber ,
(A) Diorganopolysiloxane having alkenyl groups at both ends of the molecular chain, containing 0.02 to 0.4 mol% of methylvinylsiloxane units, and having a viscosity at 23 ° C. of 100 to 150,000 mPa · s: 100 parts by weight
(B) Organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule: 0.1 to 30 parts by weight
(C) Platinum-based catalyst: effective amount,
and
(D) Filler: 1 to 300 parts by weight,
Method of bonding a cured product of organopolysiloxane and a polysiloxane composition wherein the curing and bonding at room temperature, the silicone rubber and the organopolysiloxane composition containing. Bonding method according to claim 1, characterized in that the organohydrogenpolysiloxane of the component (B) in the organopolysiloxane composition contains dimethylsiloxane units than 1 mol%.