JPH0478655B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a silicone rubber composition, and more particularly to a self-adhesive silicone rubber composition that provides strong and durable adhesion. (Prior art) Silicone rubber compositions usually have mold releasability, so they can be bonded to metals, glass, ceramics, plastics, fibers, rubber, etc. under normal vulcanization conditions. When adhering to such substances, the surface of these adherends is usually treated with a primer beforehand and then vulcanized. However, adding primer treatment to the molding process makes the process that much more complicated, and since the primer is usually used as an organic solvent solution, equipment is required to exhaust the organic solvent that evaporates during the molding process. In addition, there are health and safety problems such as inducing internal organ diseases when workers inhale the organic solvent gas or absorb it through their skin. Furthermore, under processing conditions that apply strong shearing forces, such as in-die extension molding, there is a problem of the primer layer flowing out or peeling off.Therefore, there is a need for a silicone rubber composition that has self-adhesive properties that do not require primer treatment. It is being Conventionally, such self-adhesive silicone rubber compositions include, for example, vinyltris(t-butylperoxy)silane, triphenyl(t-butylperoxy)silane, trimethyl(t-butylperoxy)silane as adhesion imparting components. , alkylperoxysilanes such as methylvinyldi(t-butylperoxy)silane, and silane caps such as vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. Silicone rubber compositions containing ring agents are known. (Problems to be Solved by the Invention) However, these self-adhesive silicone rubber compositions do not have sufficient adhesive properties when alkylperoxysilanes are added. Furthermore, when a silane coupling agent is added, there is a problem that the adhesiveness and adhesive durability are insufficient. Therefore, an object of the present invention is to provide a self-adhesive silicone composition that can achieve strong adhesion to various adherends. (Means for Solving the Problems) The present invention provides the following self-adhesive silicone composition as a solution to the above problems. That is, the present invention provides (A) average unit formula (): [In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group; z is a number from 1.98 to 2.01] and has a viscosity of 300 cS or more at 25° C. 100 weight organopolysiloxane part, and (B) general formula () [In the formula, R ² is a hydrogen atom, an alkyl group, or an alkoxy group, R ³ is an alkyl group or a phenyl group, a is an integer of 1 to 3, and b is 0
is an integer of ~2, and a+b=3; c is an integer of 1-3, d is an integer of 0-2, and 1≦c+d≦5, and R ⁴ has 3 to 3 carbon atoms. 10 monovalent hydrocarbon groups or a group represented by the formula -SiR ⁵ ₃ (wherein R ⁵ is a group selected from methyl, ethyl, phenyl, and vinyl) 0.01 10 parts by weight of a silicone rubber composition. (A) constituting the self-adhesive silicone rubber composition of the present invention (hereinafter referred to as "composition of the present invention")
In the average unit formula ( ) representing the component organopolysiloxane, the substituted or unsubstituted hydrocarbon group represented by R ¹ includes, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, and an allyl group. alkenyl groups such as phenyl groups, aryl groups such as tolyl groups, cycloalkyl groups such as cyclohexyl groups, and some or all of the hydrogen atoms bonded to the carbon atoms of these groups, for example, fluorine atoms,
Examples include hydrocarbon groups substituted with one or more types of halogen atoms such as chlorine atoms and bromine atoms, and cyano groups. Specific examples of such substituted hydrocarbon groups include chloromethyl group, trifluoropropyl group, etc. Among these substituted or unsubstituted monovalent hydrocarbon groups, preferred are methyl group, ethyl group, phenyl group, γ-trifluoropropyl group, cyanoethyl group, vinyl group, allyl group, etc. etc. In the component (A) of the composition of the present invention, it is further preferable that at least 50 mol% of the total R ¹ contained in the molecule is a methyl group, and it is preferable that at least 80 mol% is a methyl group. More preferred. If the content of methyl groups in the total R ¹ is less than 50 mol %, the inherent properties of methylpolysiloxane may be impaired, and the raw material cost may become expensive, which is disadvantageous in terms of production cost. In the average unit formula (), z is 1.98 to 2.01, and the organopolysiloxane of component (A) is a substantially linear polymer. Furthermore, the viscosity of the organopolysiloxane as component (A) at 25° C. is preferably 300 cS or more, and more preferably 1×10 ⁴ to 1×10 ⁸ cS. If the viscosity is less than 300 cS, the mechanical strength of the composition after adhesion will be insufficient and will not be suitable for practical use. The organopolysiloxane of component (A) can be produced by a known method of ring-opening polymerization of cyclic polysiloxane, which is well known as an oligomer, in the presence of an acid or alkali catalyst. In the general formula () representing the organic peroxide of component (B) constituting the composition of the present invention, the alkyl represented by R ² is, for example, a methyl group, an ethyl group,
Examples of the alkoxy group represented by ^R2 include a propyl group, a methoxy group, an ethoxy group,
Examples include propoxy group and butoxy group. Among these alkyl and alkoxy groups, R ²
Preferred are methyl group, ethyl group, methoxy group and ethoxy group, and particularly preferred is methyl group. Examples of the alkyl group represented by R ³ include a methyl group, ethyl group, propyl group, and butyl group, and examples of the aryl group represented by R ³ include a phenyl group. Among these groups represented by R ³ , methyl is preferred. In the general formula (), a is an integer of 1 to 3, b
is an integer from 0 to 2, and a+b=3,
Further, c is an integer of 1 to 3, d is an integer of 0 to 2, and 1≦c+d≦5. Preferably 1≦
c+d≦3. Specific examples of the organic peroxide that is component (B) include t
-Butylperoxy-4-vinyldimethylsilylbenzoate, t-butylperoxy-4-divinylmethylsilylbenzoate, t-butylperoxy-2,4-di(vinylmethylsilyl)benzoate, t-butylperoxy-2 ,6-dimethyl-4
-vinylmethylsilylbenzoate, t-butylperoxy-3,5-bis(vinyldimethylsilyl)benzoate, t-butylperoxy-2ethyl-4-vinyldimethylsilylbenzoate, cumylperoxy-4-vinyldimethylsilylbenzoate, trimethylsilyl Peroxy-4-vinyldimethylsilylbenzoate is mentioned. The blending amount of component (B) is in the range of 0.01 to 10 parts by weight per 100 parts by weight of component (A), preferably
It ranges from 0.3 to 10 parts by weight. If the amount of component (B) is less than 0.01 part by weight, sufficient adhesive strength will not be obtained, and furthermore, sufficient vulcanization will not be achieved. If the amount exceeds 10 parts by weight, physical properties such as tensile strength, elongation, and heat resistance properties of the resulting cured product will deteriorate. This organic peroxide (component B is, for example, represented by the formula 1 mol of substituted benzoyl chloride represented by
It can be obtained by reacting 1 mol of an alkyl hydroperoxide represented by HOO-R ⁴ in the presence of a deoxidizing agent such as pyridine or triethylamine as shown in the following formula. In addition to the above components (A) and (B), the composition of the present invention includes:
If necessary, other organic peroxides can be used as long as the desired performance of the resulting cured product is not impaired and for the purpose of adjusting the degree of vulcanization of the composition of the present invention. Examples of the organic peroxide include benzoyl peroxide, 2,2',4,
4'-tetrachlorobenzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl perbenzoate, t-butyl peracetate, 2,5-dimethyl-2,5-di-t-butyl peroxyhexane , t-butylperoxymyristyl carbonate, and the like. The composition of the present invention may be used to increase the viscosity when uncured, to improve workability, or to increase the hardness after curing.
In order to improve physical properties such as tensile strength and elongation, and to improve adhesive strength, various particulate or fibrous fillers can be blended as necessary and within a range that does not impair the results of the present invention. . Fillers that can be used include fumed silica, precipitated silica, quartz powder, diatomaceous earth, hollow glass spheres, iron oxide, zinc oxide, titanium oxide, magnesium oxide, talc, aluminum silicate, alumina, calcium carbonate, and carbon black. , asbestos, glass fiber, carbon fiber, polyester fiber, polytetrafluoroethylene powder, polyvinyl chloride powder, etc. Furthermore, conventionally known modifiers can be added to the composition of the present invention depending on the purpose of use, such as γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, - By mixing various silane coupling agents such as aminopropyltrimethoxysilane and vinyltrialkoxysilane, metal salts of organic carboxylic acids, titanate esters, chloroplatinic acid, heat resistant agents, flame retardants, organic solvents, dispersants, etc. Good too. The composition of the present invention can be easily obtained as a cured product in the form of rubber, resin, or gel by appropriately adjusting the proportions of the above-mentioned components. After the composition of the present invention thus obtained is brought into contact with a different solid surface, such as a surface of metal plastic, rubber, glass, etc. When heated to about 100 to 500°C, it crosslinks, forming the desired silicone rubber, silicone range, or silicone gel, and at the same time, it adheres uniformly and firmly to solid surfaces. Conventional adhesion techniques that involve primer treatment and methods that use conventional self-adhesive rubber compositions require the vulcanization conditions of the composition to be 150°C or higher in order to obtain good adhesion. However, since the composition of the present invention can be vulcanized at a low temperature of 110 to 130°C, it can be easily applied to such adherends. It is possible. The above-mentioned different types of solids include metals such as iron, aluminum, stainless steel, nickel, copper, and chromium, glass, quartz, ceramics, epoxy resin, acrylic resin, polyethylene phthalate resin, unsaturated polyester resin, polyamide resin, and polystyrene terephthalate. Examples include plastics such as resin, various synthetic fibers, natural fibers, inorganic fibers such as glass fiber, natural rubber, and synthetic rubber. The composition of the present invention having the above characteristics is useful as a strong and durable adhesive, sealing agent, coating agent, packaging agent, injection agent, impregnating agent, and the like. [Example] Next, the present invention will be explained in detail with reference to Examples. In the following, "parts" means parts by weight. Example 1 Methylvinylpolysiloxane 100 with an accuracy of 5,000,000 cS, consisting of 99.8 mol% dimethylsiloxane units and 0.2 mol% vinylmethylsiloxane units.
40 parts of hydrophobic fumed silica having a specific surface area of 200 m ² /g were added to the mixture and mixed with a kneader mixer until uniform. The mixture thus obtained is hereinafter referred to as mixture (A). To 100 parts of this mixture (A), 1.5 parts of silicone oil paste containing 50% t-butylperoxy-4-vinyldimethylsilylbenzoate was added and mixed. This mixture was placed on various adherends, sandwiched between molds, and pressed at 165° C. for 10 minutes at a pressure of 20 kgf/cm ² . As a result, a fully vulcanized adhesive sample was obtained. After cooling to room temperature
Rubber bonded according to the method specified in JIS K6301
A peel test was conducted in a 90° direction. The results are shown in Table-1.

[Table] Example 2 Silicone oil paste containing 50% t-butylperoxy-4-vinyldimethylsilylbenzoate in 100 parts of the mixture (A) obtained in Example 1
0.5 part and 1.0 part of silicone oil paste containing 50% of 2,2',4,4'-tetrachlorobenzoyl peroxide were added and mixed. This mixture was placed on stainless steel, sandwiched between molds, and pressure-vulcanized at 165° C. for 10 minutes at a pressure of 20 Kgf/cm ² . Adhesive strength was measured in the same manner as in Example 1. Further, hardness, tensile strength, and elongation were all measured in accordance with JIS K6301 "Vulcanized Rubber Physical Test Method." The results are shown in Table-2.

[Table] Example 3 The viscosity of the end-capped trimethylsilyl group is
1000000cS dimethylvinylpolysiloxane 100
40 parts of precipitated silica having a specific surface area of 300 m ² /g and 3 parts of dimethyldimethoxysilane as a dispersant were mixed in a kneader and heated at 160° C. for 2 hours. To this mixture, 2.0 parts of silicone oil paste containing 50% of cumyl peroxy-4-vinyldimethylsilylbenzoate was mixed, and the resulting composition was vulcanized in the same manner as in Example 1 using stainless steel as an adherend. and glued it. When the adhesive strength was measured in the same manner as in Example 1, it was found to be 8.3 kgf/cm ² , which was satisfactory. Examples 4, 5, 6 Methylvinylpolysiloxane 100 with an accuracy of 5,000,000 cS, consisting of 99.8 mol% dimethylsiloxane units and 0.2 mol% vinylmethylsiloxane units.
40 parts of hydrophobic fumed silica having a specific surface area of 100 m ² /g were added to the mixture and mixed with a kneader mixer until uniform. Table - for 100 parts of this mixture
A vulcanizing agent was blended in the ratio shown in 3, and the resulting composition was vulcanized and bonded in the same manner as in Example 1 using stainless steel as an adherend. The results of testing in the same manner as in Example 1 are shown in Table 3, and all were satisfactory.

[Table] Comparative Examples 1, 2, 3 Silicone oil pastes containing 50% t-butylperoxy-4-vinyldimethylsilylbenzoate in 100 parts of the mixture (A) obtained in Example 1 are shown in Table 4. amount was added and mixed. The obtained composition was vulcanized and bonded in the same manner as in Example 1 using stainless steel as an adherend. Table 4 shows the results of the same test as in the example.
As shown in the figure, the results were unsatisfactory.

〔Effect of the invention〕

As is clear from the results of the Examples, the self-adhesive silicone composition of the present invention has strong and durable adhesive properties and is also excellent in physical properties such as hardness, tensile strength, and elongation. Furthermore, since no primer treatment is required, the vulcanization and adhesion processes are also simplified accordingly.

Claims (1)

[Claims] 1 (A) Average unit formula (): (R ¹ _Z )SiO _4-z/2 [In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group; z is 1.98 2.01] and has a viscosity of 300 cS or more at 25°C, 100 parts by weight of an organopolysiloxane,
and (B) General formula () [In the formula, R ² is a hydrogen atom, an alkyl group, or an alkoxy group, R ³ is an alkyl group or a phenyl group, a is an integer of 1 to 3, and b is 0
is an integer of ~2, and a+b=3; c is an integer of 1-3, d is an integer of 0-2, and 1≦c+d≦5, and R ⁴ has 3 to 3 carbon atoms. 10 monovalent hydrocarbon groups or a group represented by the formula -SiR ⁵ ₃ (where R ⁵ is a group selected from methyl, ethyl, phenyl, and vinyl) 0.01 ~10 parts by weight of a silicone rubber composition.