JPS6227461A - Curable organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To improve the adhesion to a substrate in contact with the compsn. on the way of curing by preventing lowering in adhesion of the compsn. due to deaeration and by preventing the turbidity of the compsn. or interference in the caring reaction of the compsn., by mixing two organopolysiloxanes, a platinum catalyst and a polysiloxane as an adhesion accelerator. CONSTITUTION:An organopolysiloxane (A) contg. at least two alkenyl groups per molecule and having formula I (wherein R is a monovalent hydrocarbon group; and a is an average of 0.8-2.2), an organopolysiloxane (B) contg. at least two hydrogen atoms attached to a silicon atom and no alkenyl group, 0.1-100pts.wt. (in terms of metallic platinum) (per 1,000,000pts.wt. of the combined quantity of components A, B and C) platinum catalyst (C) and a polysiloxane (D) in a quantity of not more than 1/5 of that of component A, are blended in such a proportion as to give a molar ratio of the combined quantity of hydrogen atoms attached to a silicon atom is component B to the combined quantity of alkenyl groups in components A and D of 5/1-3.0/1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 1 This invention relates to a curable organopolysiloxane composition. Specifically, the present invention relates to a curable organopolysiloxane composition that exhibits excellent adhesion to substrates that it comes into contact with during curing.

[Prior Art 1] Many methods have been proposed for imparting adhesive properties to curable organopolysiloxane compositions using an addition reaction between a lower alkenyl group and a silicon-bonded hydrogen atom using a platinum catalyst. They can be roughly divided into a method of adding silane having a lower alkenyl group and a silicon atom-bonded alkoxy group or a partial hydrolyzate thereof (Japanese Patent Publication No. 56
-9183, Japanese Patent Publication No. 51-28309, Japanese Unexamined Patent Publication No. 54-135844, etc.), a method of adding a silane having a silicon-bonded hydrogen atom and a silicon-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 or a silicon-bonded hydrogen atom, a silicon-bonded alkoxy group, and an epoxy group or an ester group in one molecule (
Special Publication No. 53-21026, Special Publication No. 52-4814
Publication No. 6, Japanese Patent Publication No. 55-39258, Japanese Patent Application Publication No. 1983
-58756, JP-A-54-58755, etc.), and a method of adding lower enoxysilane or its partial hydrolyzate (Japanese Patent Publication No. 51-28308).

[Problem with the prior art 1 However, none of the prior art is perfect and always has some drawbacks. In other words, when adding a silane having a lower alkenyl group and a silicon-bonded alkoxy group, a partial hydrolyzate thereof, or a siloxane having a lower alkenyl group and a silicon-bonded alkoxy group, the addition reaction due to the lower alkenyl group is slightly There was a drawback that the curing rate was slow due to inhibition. Furthermore, the method of adding siloxanes having epoxy groups or ester groups has a drawback that the compatibility with the main component of the organopolysiloxane to be added is poor, and the composition after addition becomes cloudy. Trimethoxysilane as disclosed in Japanese Patent Publication No. 57-5836 had the disadvantage of high toxicity. The method of adding lower enoxysilane has the disadvantage that synthesis of the silane takes too much effort and is too expensive.

Additionally, when silanes are added alone, there is also a drawback that the silanes are scattered when the organopolysiloxane composition is depressurized and degassed. moreover,
Methods using these additives generally have the disadvantage that they must be cured at a temperature of 100° C. or higher in order to develop adhesive properties.

Therefore, the inventors conducted intensive research to overcome the drawbacks of the prior art, and as a result, they arrived at the present invention. The purpose of this invention is that the curing reaction is not inhibited by the adhesion promoter added, the composition does not become cloudy, the adhesiveness does not decrease even when the composition is deaerated, and it can be used on many substrates even when cured at room temperature. An object of the present invention is to provide a curable polysiloxane composition which exhibits excellent adhesion to a substrate with which it is in contact during curing.

[Means for solving problems and their effects] The purpose is to: (a) average unit formula RaSiO(42a)/2 (in the formula, R is a monovalent hydrocarbon group, a is an average of 0.8 to 2.2 organopolysiloxane having at least two lower alkenyl groups in one molecule; (b) having at least two silicon-bonded hydrogen atoms in one molecule and having no alkenyl groups; Organopolysiloxane However, the molar ratio of the total amount of silicon-bonded hydrogen atoms in this component to the total amount of all alkenyl groups in (a) T& and (d) r& is (0, S: 1)
(c) 0.1 to 100 parts by weight of platinum metal based on the total of 11 million parts by weight of the platinum-based catalysts (a) to (c), and ) Formula (where R', R2, and R3 are not alkenyl groups and have 1 carbon number)
~3 monovalent hydrocarbon groups, b, d are numbers greater than or equal to 1, C is a number greater than or equal to 0, (b+c)/d is in the ratio of 0.2-2, (b
+C+d)/e is a number of 0.4-4. This is achieved by a curable polysiloxane composition characterized in that the weight ratio of polysiloxane (i) to I & min (e is a number less than 30) does not exceed 15.

To explain this, component (a) is the main component of the curable organopolysiloxane composition according to the present invention, and is crosslinked by addition reaction with component (b) due to the catalytic action of component (c). Examples of the lower alkenyl group include a vinyl group, an allyl group, and a 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. -valent hydrocarbon groups R include alkyl groups such as methyl, ethyl, propyl, and butyl; 7-aryl groups such as phenyl and tolyl; benzyl; chloropropyl; halogenated such as lolobrovir; Alkyl group: The above-mentioned alkenyl group is exemplified.A small amount of hydroxyl group may be included in addition to R.In order to obtain good adhesiveness, it is preferable that 70 mole percent or more of R is a methyl group. In order to obtain good transparency, it is preferable that 90 mole percent or more of R is a methyl group. is preferably a number of 1.95 to 2.05 on average.

The molecular shape of this component is linear, linear including branched chains, cyclic,
The structure may be either a network or a three-dimensional structure, but is preferably a linear structure containing but not a small amount of branching. There is no particular limitation on the molecular weight of this component, which ranges from a liquid with a low viscosity to a raw rubber with a very high viscosity. Considering the workability of mixing and adhesion, the viscosity at 25°C is 50 to io.

The range is preferably 0.00 centivoise.

Such organopolysiloxanes include vinylpolysiloxane, a copolymer of vinylsiloxane and methylsiloxane, dimethylpolysiloxane with dimethylvinylsiloxy groups blocked at both ends, and dimethylsiloxane-methylphenylsiloxane with dimethylvinylsiloxy groups blocked at both ends. Polymer, dimethylsiloxane-methylvinylsiloxane copolymer with both ends blocked with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymer with both ends blocked with dimethylvinylsiloxy groups, dimethyl with both ends blocked with trimethylsiloxy groups Siloxane-methylvinylsiloxane copolymer, dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups blocked at both ends, methyl (3,
3,3-170 loprovir) polysiloxane, dimethylsiloxane-methyl(3,3,3-)su70 loprovir) siloxane copolymer with both ends capped with dimethylvinylsiloxy groups, CHz=Ctl(CH3)2S! A polysiloxane consisting of eight O' units and C)13)3SiO' eight units is exemplified.

For the purpose of improving the strength of the cured product of the organosiloxane composition according to the present invention, (a) diol novolisiloxane with dimethylvinylsiloxy group capped at both ends as r#, and C) 12=CH(Cl13)zsio'/2. Unit, (C
Hs): Polysiloxanes consisting of +SiO'/2 units and 8 Sin' units may be used in combination.

Component (B) is a crosslinking agent for component (A), and due to the catalytic action of component (1), the silicon-bonded hydrogen atoms in this component undergo an addition reaction with the lower alkenyl group in component (A), resulting in curing. It is something. The organic group is typified by a monovalent hydrocarbon group, and the same groups as R mentioned above are exemplified and preferred (excluding alkenyl groups). There is no particular limitation on the molecular structure of this component, and it may be linear, linear with branches, or cyclic. There is no particular limitation on the molecular weight of this component, but (a)
In order to improve the compatibility with the components, the viscosity force ri-so,oo at 25°C.

Preferably, it is centiboise. The amount of this component added is the total amount of silicon-bonded hydrogen atoms in this component and (a)
The amount is such that the molar ratio with the total amount of all alkenyl groups in the component and (d) component is (0,5:1) to (3,0:1). This is because when the ratio is smaller than 0.5:1, the curability is excellent and the curability remains constant, and when it is larger than 3.0:1, foaming tends to occur. If siloxanes containing alkenyl groups are separately added for reinforcement or other purposes, this component containing silicon-bonded hydrogen atoms must be added in an amount corresponding to the alkenyl groups.

Specific examples of this component include methylhydrodienepolysiloxane with both terminals blocked by trimethylsiloxy groups, dimethylsiloxane-methylhydrodienesiloxane copolymer with both terminals blocked with trimethylsiloxy groups, and methyl with both ends blocked with dimethylhydrodienesiloxy groups. Hydrodiene polysiloxane, dimethylsiloxane-methylhydrodienesiloxane copolymer with both terminals blocked with dimethylhydrodienesiloxy groups, dimethylsiloxane-methylhydrodienesiloxane cyclic copolymer, (CH=)2HS!
Copolymer consisting of 0'/2 units and 5i02/4 units, (
CHff)=SiO'/2 units, (Ct13LHSiO
Examples include copolymers consisting of 8 units and 8 units of SiO.

(c) T&min is a catalyst that causes an addition reaction between a silicon-bonded hydrogen atom and an alkenyl group. Specific examples include chloroplatinic acid, its solution in alcohols or ketones, and its solution. complex compounds of chloroplatinic acid and olefins, complex compounds of chloroplatinic acid and alkenylsiloxanes, complex compounds of platinum and diketones, platinum black, and platinum supported on a carrier. The amount of this component added is 0.1 to 100 parts by weight of platinum metal per 1 million parts by weight of the total amount of components (a) to (d), but if it is less than 0.001 parts by weight, the crosslinking reaction will proceed sufficiently. If it exceeds 100 parts by weight, it is not only uneconomical but also the pot life of the olga/polysiloxane composition at room temperature becomes too short. Usually, when used in an adhesive composition, the amount added is preferably 1 to 20 parts by weight.

Component (d) is a characteristic component of the Olga/polysiloxane composition of the present invention, and exhibits good adhesion to the substrate with which the composition is in contact during curing.

This component is a polysiloxane with a three-dimensional structure consisting of 72 SiO'' units as its basic constituent unit, and carbon atoms are
H2=CH(R')2si group, R2, Si group, and R3 group are bonded. The reason why the Sin'/2 unit of this component is less than 30 is because if it is 30 or more, the molecular weight becomes too large and adhesiveness cannot be exhibited. Considering the compatibility between this component and component (a), it is preferable that Sin' is 8 units to 20 or less, and from the viewpoint of preventing volatilization during degassing operation, it is preferably 3 or more.

In the formula, d is a number of 1 or more, but if it is less than 1, good adhesion will not be achieved. C is 0
The value of (b + c) / d is 0.2
-2, but this is also because good adhesion will not be exhibited if it is outside this range. Also, (b+c+
d)/e is a number of 0.4-4, but if it is less than 0.4, good adhesion cannot be obtained, and if it is more than 4, it is practically impossible to manufacture. R1, R2, R
3 is a monovalent hydrocarbon group having 1 to 3 carbon atoms that is not an alkenyl group, and examples thereof include a methyl group, an ethyl group, and a propyl group. Preferably R1 and R2 are methyl groups, and R3 is preferably a methyl group or an ethyl group.

The amount of this component to be added is such that the weight ratio to component (a) does not exceed 115, since adding more than that will impair the original properties of the composition. In addition, the optimum amount to be added to obtain good adhesion varies depending on the structure of the components of the pond, but is approximately 1 part by weight per 100 parts by weight of component (A).
~8 parts by weight.

This component can be synthesized by conventionally known methods, examples of which include dimethylvinylchlorosilane, dimethylvinylacetoxylane, trimethylvinylethoxysilane, divinyltetramethylnosiloxane, trimethylc70silane, and trinotylacetoxysilane. It is obtained by co-hydrolyzing one or more of silane and hexamethyldisiloxane with methyl orthosilicate or ethyl orthosilicate in the presence of a strictly controlled amount of water. Note that at this time, it is recommended to use an acidic catalyst such as hydrochloric acid.

Two or more types of each of the above components may be used in combination.

The curable Ol7y/polysiloxane composition according to the present invention can be obtained by simply mixing components (a) to (d). Any mixing device suitable for stirring liquid or raw rubber, such as a mixer, can be used.

The curable olga/polysiloxane composition according to the present invention contains traces or small amounts of acetylene compounds, hydrazines, doriasols, 7-osphines, mercaptans, etc. as additives to suppress the curing reaction at room temperature. It is recommended that you do so. Further, fine silica powder, fillers such as carbon black, heat resistant agents, coloring agents, flame retardant agents, etc. may be added as long as they do not impair the purpose of the present invention.

[Example] The present invention will be explained below with reference to Examples.
"%" refers to parts by weight, and "percent" regarding content and amount added refers to percent by weight. Viscosity and other properties were measured at 25°C.

Example 1 Dimethylpolysiloxane with dimethylvinylsiloxy groups blocked at both ends (viscosity 2000 centivoise, designated as Polymer A1), dimethylsiloxane-methylhydrodienesiloxane copolymer with both ends blocked with trimethylsiloxy groups (
The molar ratio of the former and the latter is 3:5, the viscosity is 10 centivoise,
(Denoted as Polymer A polysiloxane represented by the formula (indicated as polymer M3) or a polysiloxane represented by the formula % (indicated as polymer M4), 3
- methyl-butyn-3-ol (labeled as additive 1);
Table 1 shows the results of curing in contact with glass at 150°C and measuring the light transmittance and adhesion to glass of the cured product.
It was shown to. The numbers indicating adhesiveness in the table mean the cohesive failure rate (%) of the cured product. Curing time refers to the time it takes for the composition to completely cure. Light transmittance is the thickness of the cured product 10
Measurements were made under the conditions of 500 nm and a light wavelength of 500 nm.

Example 2 100 parts of dimethylpolysiloxane (viscosity 10,000 centivoise) with both ends blocked by trimethylvinylsiloxy groups, dimethylvinylsiloxy group, trimethylsiloxy group and Sin'/2 unit, vinyl group content 1%, softening point 120°C resinous organopolysiloxane 1
0 parts, 30 parts of fumed silica hydrophobized with trimethylsilyl groups, 0.4 parts of tetramethyltetravinylcyclotetrasiloxane, dimethylsiloxane-methylhydrodienesiloxane copolymer with both terminals blocked with trimethylsiloxy groups (the former and the latter) A composition was prepared consisting of 10 parts (mole ratio: 3:1, viscosity: 10 centipoise), and a complex of divinyltetramethyldisiloxane and chloroplatinic acid in an amount such that the total amount of platinum was 10 ppm. Siloxane (indicated as Polymer M5) was added in an amount corresponding to 5% of the total amount and mixed. Then 30
Vacuum defoamed at room temperature for 12 minutes in contact with various substrates.
It was cured under two types of curing conditions: 0° C. for 30 minutes and room temperature for 24 hours, and its light transmittance and adhesion to various substrates were measured.

For comparison, the same operation was carried out by adding vinyltrimethoxysilane in an amount corresponding to 5% of the total amount instead of Polymer M5, and the adhesion state was measured. The results are summarized in Table 2. The numbers indicating adhesion in the table indicate the cohesive failure rate (%).

[Effect of the invention 1] In this invention, a predetermined amount of polysiloxane represented by the formula is added as an adhesion promoter to the addition reaction curable Olga 7 polysiloxane composition.
The curing reaction is not inhibited by the addition of an adhesion promoter, the composition does not become cloudy, the adhesion does not decrease even when the composition is degassed, and it has excellent adhesion to substrates that are in contact with it during curing. It has the characteristic of indicating gender. Therefore, the curable organopolysiloxane composition of the present invention is suitable for use in various industries such as the electrical and electronic industry, the measuring instrument industry, the automobile industry, the machinery industry, the civil engineering and construction industry, the container packaging industry, and the medical industry. It is suitable as an adhesive or coating agent for various base materials such as metal, resin, paper, Wl, and fiber. Mainly, due to its excellent transparency, it is ideal as an adhesive for optical applications.

Patent applicant: Toray Silicone Co., Ltd. Procedures
Amendment dated February 13, 1986, Mr. Michibu Uga, Commissioner of the Patent Office: ~
5. -1.Indication of the case 1985 Patent Application No. 1682722.Name of the invention Curable Olga 7 Polysiloxane Converter3.Relationship with the case Patent applicant Postal code 103 4.Date of amendment order Spontaneous 5, number of inventions increased by amendment 7, description of contents of amendment, page 16, line 11 r CL C1+.

r CL
CH3I I CL Cll,
Correct to J.

Claims (1)

[Claims] (a) Average unit formula RaSiO_(_4_-_a_)_/
_2 (in the formula, R is a monovalent hydrocarbon group, a is an average of 0.8 to 2.
(b) Organopolysiloxanes having at least two silicon-bonded hydrogen atoms in one molecule and having at least two lower alkenyl groups in one molecule; However, the molar ratio of the total amount of silicon-bonded hydrogen atoms in this component to the total amount of all alkenyl groups in components (a) and (d) is from (0.5:1) to (3. 0:1); (c) platinum-based catalysts (a) to (c) in an amount of 0.1 to 100 parts by weight as platinum metal per 1 million parts by weight of the total amount of components (a) to (c); ) Formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1, R^2, and R^3 are monovalent hydrocarbon groups with 1 to 3 carbon atoms that are not alkenyl groups, and b and d are numbers of 1 or more. ,c
is a number greater than or equal to 0, (b+c)/d is in a ratio of 0.2 to 2, and (b+c+d)/e is a number of 0.4 to 4. e is 3
1. A curable organopolysiloxane composition, characterized in that the weight ratio to the polysiloxane component (a) (which is a number less than 0) does not exceed 1/5.