JPH0641563B2 - Curable organopolysiloxane composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable organopolysiloxane composition. More specifically, the present invention relates to a curable organopolysiloxane composition having excellent adhesiveness to a substrate that is in contact with the substrate during curing.

[Prior Art] A number of methods have been proposed as a technique for imparting adhesiveness to a curable organopolysiloxane composition utilizing an addition reaction of a lower alkenyl group and a silicon atom-bonded hydrogen atom with a platinum catalyst. They are roughly classified into a method of adding a silane having a lower alkenyl group and a silicon atom-bonded alkoxy group or a partial hydrolyzate thereof (Japanese Patent Publication No.
No. 9183, Japanese Patent Publication No. 51-28309, JP-A No. 54-135844, etc.), a method of adding a silane having a silicon atom-bonded hydrogen atom and a silicon atom-bonded alkoxy group or a partial hydrolyzate thereof ( (Japanese Patent Publication No. 57-5836), a method of adding a linear or cyclic polysiloxane having a lower alkenyl group, a silicon atom-bonded hydrogen atom, a silicon atom-bonded alkoxy group, an epoxy group, an ester group, or the like in one molecule ( Japanese Patent Publication No. 53-21026, Japanese Patent Publication No. 52-481
46, JP-B-55-39258, JP-A-5
No. 4-58756, JP-A No. 54-58755, etc.) and a method of adding lower enoxysilane or a partial hydrolyzate thereof (Japanese Patent Publication No. 51-28308).

[Problems of the Prior Art] However, such a conventional technology is not yet perfect and always has some drawbacks. That is, in the method of adding a silane having a lower alkenyl group and a silicon atom-bonded alkoxy group, a partial hydrolyzate thereof, or a siloxane having a lower alkenyl group and a silicon atom-bonded alkoxy group, the addition reaction is slightly dependent on the lower alkenyl group. There is a drawback that it is hindered and the curing speed becomes slow. Further, the method of adding siloxanes having an epoxy group or an ester group has a drawback that the compatibility with the added organopolysiloxane main component is not good and the composition after addition becomes cloudy. Trimethoxysilane as shown in JP-B-57-5836 has a drawback that it is highly toxic. The method of adding lower enoxysilane has the drawback that the synthesis of the silane takes too much time and the cost is too high. In addition, if silanes are added as a simple substance, there is also a drawback that the silanes are scattered when the organopolysiloxane composition is depressurized to perform a deaeration operation. Further, the method using these additives has a drawback that in general, the adhesiveness must be cured at a temperature of 100 ° C. or higher.

Therefore, the inventors of the present invention arrived at the present invention as a result of earnest research to overcome the drawbacks of the prior art. The object of the present invention is to prevent the curing reaction from being inhibited by the adhesion promoter to be added, to prevent the composition from becoming cloudy, to prevent the adhesive property from being deteriorated even when the composition is degassed, and to cure many substrates even at room temperature. Another object of the present invention is to provide a curable organopolysiloxane composition having excellent adhesiveness to a base material which is in contact with the substrate during curing, which is characterized by exhibiting adhesiveness to.

[Means for Solving Problems and Their Actions] This purpose is (a) average unit formula (In the formula, R is a monovalent hydrocarbon group, a is an average number of 0.8 to 2.2) and has at least two lower alkenyl groups in one molecule. Organopolysiloxane having at least 2 silicon-bonded hydrogen atoms in one molecule and not having an alkenyl group, provided that the total amount of silicon-bonded hydrogen atoms in this component and (a) component and (d) component Such that the molar ratio with respect to the total amount of all alkenyl groups is from (0.5: 1) to (3.0: 1), (c) Platinum-based catalyst (a) to (c) Total amount of components 0.1 to 100 parts by weight of platinum metal with respect to 1 million parts by weight and (d) Formula (In the formula, R ¹ , R ² , and R ³ are not alkenyl groups and have 1 to 1 carbon atoms.
3 monovalent hydrocarbon groups, b and d are 1 or more, c is 0 or more, (b + c) / d is in the ratio of 0.2 to 2, and (b + c + d) / e is 0.
It is a number from 4 to 4. (e is a number of less than 30). The curable organopolysiloxane composition is characterized in that the weight ratio of the polysiloxane to the component (a) does not exceed 1/5.

To explain this, the component (a) is the main component of the curable organopolysiloxane composition according to the present invention and undergoes an addition reaction with the component (b) to crosslink by the catalytic action of the component (c). Examples of the lower alkenyl group include vinyl group, allyl group and propenyl group. The lower alkenyl group may be present anywhere in the molecule, but is preferably present at least at the end of the molecule. The monovalent hydrocarbon group R is a methyl group,
Examples thereof include alkyl groups such as ethyl group, propyl group and butyl group; aryl groups such as phenyl group and tolyl group; benzyl group; halogenated alkyl groups such as chloropropyl group and trifluoropropyl group; and the above alkenyl groups. In addition to R, some hydroxyl groups may be contained. In order to obtain good adhesiveness, 70 mol% or more of R is preferably a methyl group, and in order to obtain good transparency, 90 of R is preferable.
It is preferable that the mole percent or more is a methyl group.
Although a is a number of 0.8 to 2.2 on average, it is preferably a number of 1.95 to 2.05 on average in order to obtain good adhesiveness.

The molecular shape of this component is straight chain, straight chain including branched, cyclic,
It may be any of a mesh structure and a three-dimensional structure, but is preferably a linear structure with or without slight branching. The molecular weight of this component is not particularly limited and includes liquids having low viscosity to very high raw rubber. Considering workability of mixing and adhesion, the viscosity at 25 ° C. is preferably in the range of 50 to 100,000 centipoise.

Examples of such an organopolysiloxane include vinyl polysiloxane, a copolymer of vinyl siloxane and methyl siloxane, dimethyl polysiloxane with both ends dimethyl vinyl siloxy group blocked, and dimethyl siloxane-methyl phenyl siloxane with both ends dimethyl vinyl siloxy group blocked. Polymer, dimethylsiloxane-methylvinylsiloxane copolymer with both ends dimethylvinylsiloxy group blocked, dimethylsiloxane with both terminals dimethylvinylsiloxy group blocked, diphenylsiloxane-methylvinylsiloxane copolymer, dimethyl with both ends trimethylsiloxy group blocked Siloxane-methylvinylsiloxane copolymer, dimethylsiloxy group-blocked dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymer at both ends, both-end dimethyl Nirushirokishi group blocked methyl (3,
3,3 trifluoropropyl) polysiloxanes, both ends blocked by dimethylvinylsiloxy groups dimethylsiloxane - methyl (3,3,3-trifluoropropyl) siloxane _{copolymers, CH 2 = CH (CH 3} ) 2 SiO1 / 2 units and (CH ₃ ) ₃ SiO 1/2 units and SiO
An example is polysiloxane composed of 4/2 units.

For the purpose of improving the strength of the cured product of the organosiloxane composition according to the present invention, a diorganopolysiloxane capped with dimethylvinylsiloxy groups at both terminals and CH ₂ are used as the component (a).
_{= CH (CH 3) 2 SiO1} / 2 _{units, (CH 3) 3 SiO1 /} 2 units and SiO4 / 2
You may use combining the polysiloxane which consists of a unit.

The component (b) is a cross-linking agent of the component (a) and is cured by the catalytic action of the component (c) by the addition reaction of the silicon atom-bonded hydrogen atom in this component with the lower alkenyl group in the component (b). Is. The organic group is represented by a monovalent hydrocarbon group, and examples thereof are the same as those described above for R, and are preferable (however, excluding alkenyl group). The molecular structure of this component is not particularly limited, and may be linear, branched-containing linear, or cyclic. The molecular weight of this component is also not particularly limited,
In order to improve the compatibility with the component (a), the viscosity at 25 ° C. is preferably 1 to 50,000 centipoise. The amount of this component added is such that the molar ratio of the total amount of silicon-bonded hydrogen atoms in this component to the total amount of all alkenyl groups in component (a) and component (d) is (0.5:
1) to (3.0 to 1), but if the molar ratio is less than 0.5: 1, good curability cannot be obtained, and if it is more than 3.0: 1. This is because foaming becomes easier. When siloxanes containing an alkenyl group are separately added for the purpose of reinforcement or for other purposes, this component containing silicon atom-bonded hydrogen atoms commensurate with the alkenyl group must be added.

Specific examples of this component are: methyl hydrogen polysiloxane with both ends trimethylsiloxy group blocked, dimethylsiloxane-methylhydrogensiloxane copolymer with both ends trimethylsiloxy group blocked, methyl with both ends dimethylhydrogensiloxy group blocked Hydrogen polysiloxane, dimethyl siloxane-methyl hydrogen siloxane copolymer with both ends dimethyl hydrogen siloxy group blocked, dimethyl siloxane-methyl hydrogen siloxane cyclic copolymer, (CH ₃ ) ₂ HSiO1 / 2 units and SiO2 / 4 A copolymer consisting of units, (CH ₃ ) ₃ SiO1 / 2 units, (C
H ₃ ) ₂ H A copolymer composed of SiO1 / 2 units and SiO4 / 2 units can be mentioned.

The component (c) is a catalyst for addition-reacting a silicon atom-bonded hydrogen atom and an alkenyl group. Specific examples include chloroplatinic acid and its dissolved in alcohols and ketones, and aged solutions thereof. , Complex compounds of chloroplatinic acid and olefins, complex compounds of chloroplatinic acid and alkenylsiloxanes, complex compounds of platinum and diketones,
Examples include platinum black and platinum supported on a carrier.
The addition amount of this component is 0.1 to 100 parts by weight as platinum metal based on 1,000,000 parts by weight of the total amount of the components (a) to (c). This is because it does not proceed sufficiently, and when it is 100 parts by weight or more, not only is it uneconomical, but also the pot life of the organopolysiloxane composition at room temperature becomes too short. Usually, when it is used in an adhesive composition, an addition amount of about 1 to 20 parts by weight is preferable.

The component (d) is a component that is a feature of the organopolysiloxane composition of the present invention, and exhibits good adhesiveness to the base material that is in contact with the composition during curing of the composition.

This component is a polysiloxane having a three-dimensional structure of a basic constituent unit SiO4 / 2 units, CH ₂ = CH via its oxygen atom
The (R ¹ ) ₂ Si group, the R ² ₃ Si group and the R ³ group are bonded. S of this ingredient
The reason why the iO4 / 2 unit is less than 30 is that if it is 30 or more, the molecular weight becomes too large to exhibit adhesiveness. Considering the compatibility between this component and the component (a), the SiO4 / 2 unit is preferably 20 or less, and more preferably 3 or more from the viewpoint of preventing volatilization during the degassing operation.

In the formula, b and d are set to a number of 1 or more, but if this is less than 1, good adhesion is not expressed. c is a number of 0 or more, and the value of (b + c) / d is said to be 0.2 to 2. This is also because if it is outside this range, good adhesiveness is not exhibited. Further, (b + c + d) / e is a number of 0.4 to 4, but if it is less than 0.4, good adhesiveness cannot be obtained, and if it exceeds 4, it is substantially This is because it cannot be manufactured. R ¹ , R ² and R ³ are each a monovalent hydrocarbon group having 1 to 3 carbon atoms which is not an alkenyl group, and examples thereof include a methyl group, an ethyl group and a propyl group. Preferably, R ¹ and R ² are methyl groups, and R ³ is a methyl group or an ethyl group.

The amount of this component added is such that the weight ratio with respect to the component (a) does not exceed 1/5, because the addition of more than that will impair the original properties of the composition. The optimum addition amount for obtaining good adhesiveness varies depending on the structure of other components, but is generally 1 per 100 parts by weight of the component (a).
~ 8 parts by weight.

This component can be synthesized by a conventionally known method, and one example thereof is dimethylvinylchlorosilane, dimethylvinylacetoxylan, dimethylvinylethoxysilane, divinyltetramethyldisiloxane, trimethylchlorosilane, trimethylacetoxysilane, hexamethyl. It is obtained by cohydrolyzing one or more of the disiloxanes with methyl orthosilicate or ethyl orthosilicate in the presence of a strictly controlled amount of water. At this time, it is recommended to use an acidic catalyst such as hydrochloric acid. You may mix and use 2 or more types with each said component.

The curable organopolysiloxane composition according to the present invention can be obtained by simply mixing the components (a) to (d). For mixing, a liquid such as a planetary mixer, a screw mixer, a static mixer, a kneader mixer is used. Alternatively, any mixing device suitable for stirring raw rubber can be used.

The curable organopolysiloxane composition according to the present invention may contain a trace amount or a small amount of an acetylene compound, hydrazines, triazoles, phosphines, mercaptans, etc. as an additive for suppressing the curing reaction at room temperature. Recommended. Further, silica fine powder, a filler such as carbon black, a heat-resistant agent, a colorant, a flame retardant and the like may be added within a range that does not impair the object of the present invention.

[Examples] The present invention will be described below with reference to examples, but "parts" in the examples
The term "parts" means "parts by weight", and the term "percentage" in terms of content and addition amount means percent by weight. Viscosity and other properties are measured at 25 ° C.

Example 1 Dimethylpolysiloxane having both ends dimethylvinylsiloxy group blocked (viscosity 2000 centipoise, indicated as polymer A1), dimethylsiloxy-methylhydrogensiloxane copolymer having both terminals trimethylsiloxy group blocked (the molar ratio of the former to the latter is 3: 5, viscosity 10 centipoise, designated as polymer X1), 1% solution of chloroplatinic acid in 2-ethylhexanol (denoted as catalyst 1), formula A polysiloxane (denoted as polymer M1) represented by the formula A polysiloxane represented by (indicated as polymer M2), a formula Polysiloxane represented by (indicated as polymer M3) or formula Polysiloxane represented by (displayed as polymer M4), 3
A series of organopolysiloxane compositions consisting of -methyl-butyn-3-ol (designated as additive I1),
Table 1 shows the results of measuring the light transmittance of the cured product and the adhesion to glass by curing the cured product at 150 ° C in contact with glass.
It was shown to. The numbers showing the adhesiveness in the table mean the cohesive failure rate (%) of the cured product. The curing time is the time until the composition is completely cured. Light transmittance is the thickness of the cured product 10
mm, and the wavelength of light was 500 nm.

Example 2 100 parts of dimethylpolysiloxane having a dimethylvinylsiloxy group blocked at both ends (viscosity: 10,000 centipoise), a dimethylvinylsiloxy group, a trimethylsiloxy group and
10 parts of a resin-like organopolysiloxane composed of SiO4 / 2 units, having a vinyl group content of 1% and a softening point of 120 ° C., 30 parts of fumed silica hydrophobized with a trimethylsilyl group,
Tetramethyltetravinylcyclotetrasiloxane 0.
4 parts, dimethylsiloxane-methylhydrogensiloxane copolymer with both ends trimethylsiloxy group blocked (molar ratio of the former and the latter is 3: 1, viscosity 10 centipoise) 1
A composition was prepared by formulating 0 part of a complex of divinyltetramethyldisiloxane and chloroplatinic acid to a total amount of platinum of 10 ppm, The polysiloxane represented by (indicated as polymer M5) was added and mixed in an amount corresponding to 5% of the total amount. Then 30
Vacuum degassed at room temperature for 12 minutes and in contact with various substrates 12
It was cured under two different curing conditions of 0 ° C. for 30 minutes and room temperature for 24 hours, and the light transmittance and the state of adhesion to various substrates were measured.

For comparison, vinyl trimethoxysilane was added instead of the polymer M5 in an amount corresponding to 5% of the total amount, and the same operation was performed to measure the adhesion state. The results are summarized in Table 2. In the table, the number indicating the adhesiveness indicates the cohesive failure rate%.

[Advantages of the Invention] In the present invention, in the addition reaction-curable organopolysiloxane composition, the compound of the formula Since a predetermined amount of polysiloxane shown in is added,
The curing reaction is not hindered by the addition of the adhesion promoter, the composition does not become cloudy, the adhesiveness does not decrease even when the composition is degassed, and excellent adhesion to the base material in contact during curing is achieved. It is characterized by showing sex. Therefore, the curable organopolysiloxane composition of the present invention, glass, ceramics, metals in various industries such as electrical and electronic industry, measuring instrument industry, automobile industry, machine industry, civil engineering construction industry, container packaging industry, medical equipment industry, It is suitable as an adhesive or coating agent for various substrates such as resin, paper, and fibers. Moreover, since it is excellent in transparency, it is most suitable as an adhesive for optical applications.

Claims (1)

[Claims] 1. (a) Average unit formula (In the formula, R is a monovalent hydrocarbon group, a is an average number of 0.8 to 2.2) and has at least two lower alkenyl groups in one molecule. Organopolysiloxane having at least 2 silicon-bonded hydrogen atoms in one molecule and not having an alkenyl group, provided that the total amount of silicon-bonded hydrogen atoms in this component and (a) component and (d) component Such that the molar ratio with respect to the total amount of all alkenyl groups is from (0.5: 1) to (3.0: 1), (c) Platinum-based catalyst (a) to (c) Total amount of components 0.1 to 100 parts by weight of platinum metal with respect to 1 million parts by weight and (d) Formula (In the formula, R ¹ , R ² , and R ³ are not alkenyl groups and have 1 to 1 carbon atoms.
3 monovalent hydrocarbon groups, b and d are 1 or more, c is 0 or more, (b + c) / d is in the ratio of 0.2 to 2, and (b + c + d) / e is 0.
It is a number from 4 to 4. Polysiloxane represented by the formula (e is a number less than 30) (a) A curable organopolysiloxane composition characterized in that the weight ratio to the component (a) does not exceed 1/5.