JP2014224193A - Adhesion method of silicone rubber composition, and composite molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently and firmly adhering a cured product of a millable silicone rubber composition to a metal substrate without using a primer and without using a self-adhesive silicone rubber composition containing an adhesiveness imparting agent.SOLUTION: A method for adhering a millable silicone rubber composition includes: a step (I) of curing the following millable silicone rubber composition while press-bonding the composition to a metal substrate; and a step (II) of heating the composite molded article of the cured product of the millable silicone rubber composition and the metal substrate obtained in the step (I) to 100°C or higher. The millable silicone rubber composition comprises (A) an organopolysiloxane expressed by formula (I): RSiO(I), where Rrepresents a monovalent hydrocarbon group and a is 1.95 to 2.05, (B) reinforcing silica having a specific surface area of 50 m/g or more by a BET adsorption method, and (C) an organic peroxide, and substantially does not contain an adhesive component.

Description

  In the present invention, after a millable silicone rubber composition substantially free of an adhesive component is cured in contact with a metal substrate (under pressure bonding) or non-contact, the cured product of the silicone rubber composition is converted into a metal group. A method of adhering a millable silicone rubber composition and a metal substrate by contact (or pressure bonding) with the material and heat treatment, and a cured product of the silicone rubber composition bonded by this method and the metal substrate It relates to composite molded products.

  Silicone rubber has excellent weather resistance, electrical properties, low compression set, heat resistance, cold resistance, and other properties, so it can be used in various fields including electrical equipment, automobiles, architecture, medical care and food. Widely used. For example, rubber contacts used as rubber contacts for remote controllers, typewriters, word processors, computer terminals, musical instruments, etc .; architectural gaskets; various rolls such as copier rolls, development rolls, transfer rolls, charging rolls, paper feed rolls, etc. Anti-vibration rubber for audio devices, etc .; use for compact disc packing used in computers, etc. Currently, the demand for silicone rubber is increasing, and the development of silicone rubber having excellent characteristics is desired.

  As a method of bonding the silicone rubber and the metal substrate (metal base material), various methods of applying various primers (Japanese Patent Laid-Open No. 11-209702, Japanese Patent No. 3539167: Patent Documents 1 and 2) or self A method of bringing an adhesive silicone rubber composition into contact with a metal substrate and curing it has been proposed. In this self-adhesive silicone rubber composition, as an adhesion-imparting component, for example, a compound having an epoxy group and a hydrogen atom directly bonded to a silicon atom in one molecule (Japanese Patent No. 4221545: Patent Document 3), etc. It is blended.

  However, the method of contacting with a primer is inferior in workability, such as taking time and effort to apply a primer to a metal surface, and the method of using a self-adhesive silicone rubber cures the self-adhesive silicone rubber. At this time, it must be brought into contact with the metal substrate, which is inferior in productivity, and may adhere to an undesired part such as a mold, resulting in poor yield.

JP-A-11-209702 Japanese Patent No. 3539167 Japanese Patent No. 4221545

  The present invention has been made in order to solve the above-mentioned problems of the prior art, and can be milled without using a primer and without using a self-adhesive silicone rubber composition containing an adhesion-imparting agent. A method for efficiently and firmly bonding a cured product of a silicone rubber composition (silicone rubber) and a metal base material (especially productivity) and particularly a metal that is not originally intended such as a mold during press molding An object of the present invention is to efficiently obtain the above-mentioned adhesion method without adhesion of silicone rubber to a substrate, and a composite molded product in which silicone rubber and a metal substrate are firmly adhered by the method.

  As a result of intensive studies to achieve the above object, the present inventors have used a specific millable silicone rubber composition that does not substantially contain an adhesion-imparting agent, and the millable silicone rubber composition. Is hardened in contact with the metal substrate (under pressure bonding) or in a non-contact state, and then heated to 100 ° C. or higher in the state of contact with the metal substrate, thereby strengthening the millable silicone rubber and the metal substrate. The inventors have found that they can be adhered to each other, and have made the present invention.

Accordingly, the present invention provides a method for bonding the following millable silicone rubber composition and a composite molded product of a silicone rubber and a metal substrate produced by the bonding method.
[1]
(A) The following average composition formula (I)
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) 5 to 100 parts by mass of reinforcing silica having a specific surface area of 50 m ² / g or more according to the BET adsorption method,
(C) an organic peroxide containing an effective amount, and curing (I) a millable silicone rubber composition substantially free of adhesive components while being pressed against a metal substrate; and the step (I) And a step (II) of heating the composite molded product of the millable silicone rubber composition and metal substrate obtained in step 1 to 100 ° C. or higher, and a method for bonding the millable silicone rubber composition.
[2]
In the step (I) in which the millable silicone rubber composition cures the composition, the millable silicone rubber composition does not adhere to the metal substrate even if the millable silicone rubber composition is cured while being pressure-bonded to the metal substrate. The method for adhering a millable silicone rubber composition according to [1], wherein in the step (II) of heating to a metal substrate, the metal base material is adhered.
[3]
(A) The following average composition formula (I)
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) 5 to 100 parts by mass of reinforcing silica having a specific surface area of 50 m ² / g or more according to the BET adsorption method,
(C) Organic peroxide A step (i) of curing a millable silicone rubber composition containing an effective amount and containing substantially no adhesive component in a non-contacting manner with a metal substrate, and the cured millable A step (ii) of heating the mold-type silicone rubber to 100 ° C. or higher in a state where the mold-type silicone rubber is pressure-bonded to the metal base material.
[4]
The organic peroxide as component (C) is at least one selected from alkyl peresters, peroxycarbonates, peroxyketals, and diacyl peroxides. [1] to [3] The millable silicone according to any one of [1] to [3] Method for bonding rubber composition.
[5]
The millable silicone rubber composition according to any one of [1] to [4], wherein the organopolysiloxane of component (A) has a degree of polymerization of 100 or more and contains at least two alkenyl groups per molecule. Bonding method of objects.
[6]
The millable silicone rubber composition further contains an addition reaction type curing agent comprising a combination of (D-1) organohydrogenpolysiloxane and (D-2) hydrosilylation catalyst as component (D) [1] to [5] The method for adhering a millable silicone rubber composition according to any one of [5].
[7]
[1] A composite molded product of a cured product of a silicone rubber composition and a metal substrate bonded by the method according to any one of [6].

  According to the bonding method of the present invention, a cured product (silicone rubber) of a millable silicone rubber composition without using a primer and without using a self-adhesive silicone rubber composition containing an adhesion-imparting agent. ) And metal base material efficiently (excellent productivity) and firmly, and there is no adhesion of silicone rubber to metal bases that are not originally intended such as molds during press molding Therefore, a composite molded product in which the silicone rubber and the metal base material are firmly bonded can be efficiently obtained.

Hereinafter, the present invention will be described in detail.
The millable silicone rubber composition of the present invention comprises:
(A) an organopolysiloxane represented by the following average composition formula (I):
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
(B) Reinforcing silica having a specific surface area by a BET adsorption method of 50 m ² / g or more,
(C) an organic peroxide,
Preferably, it further comprises an addition reaction type curing agent comprising a combination of (D) (D-1) an organohydrogenpolysiloxane and (D-2) a hydrosilylation catalyst, and substantially does not contain an adhesive component. is there.
The millable silicone rubber composition is different from a liquid silicone rubber composition having self-fluidity at room temperature (25 ° C.), and is a raw rubber (non-liquid) having a high viscosity at room temperature (25 ° C.). It means a silicone rubber composition that can be kneaded by applying a shearing force (high shear) with a kneader such as a roll mill.

Below, each component is explained in full detail.
-(A) component-
In the present invention, the component (A) is an organopolysiloxane represented by the following average composition formula (I), preferably having a degree of polymerization of 100 or more.
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)

In the above average composition formula (I), R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, usually having 1 to 12 carbon atoms, particularly preferably having 1 to 8 carbon atoms. Are alkyl groups such as methyl, ethyl, propyl, butyl, hexyl and octyl, cycloalkyl such as cyclopentyl and cyclohexyl, alkenyl such as vinyl, allyl and propenyl, cyclo An aryl group such as an alkenyl group, a phenyl group or a tolyl group, an aralkyl group such as a benzyl group or a 2-phenylethyl group, or a part or all of the hydrogen atoms of these groups is a halogen atom such as fluorine or chlorine or a cyano group For example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group, and the like substituted with a methyl group, a vinyl group, a phenyl group, a trifluoro group, etc. Preferably propyl, especially methyl, vinyl is preferable.

In particular, the organopolysiloxane as the component (A) has 2 or more, usually 2 to 50, particularly about 2 to 20 alkenyl groups, cycloalkenyl groups and other aliphatic unsaturated groups in one molecule. Those having a vinyl group are particularly preferable. In this case, it is preferable all R ¹ in 0.01 to 20 mol%, in particular 0.02 to 10 mol% is an aliphatic unsaturated group. The aliphatic unsaturated group may be bonded to the silicon atom at the molecular chain end, or may be bonded to the silicon atom in the middle of the molecular chain (molecular chain non-terminal), or both. Is preferably bonded to at least a silicon atom at the end of the molecular chain.

Further, in all R ^{1 s} , 80% by mole or more, preferably 90% by mole or more, more preferably 95% by mole or more, and more preferably all R ¹ except aliphatic unsaturated groups are alkyl groups, particularly methyl groups. It is desirable.

  a is a positive number of 1.95 to 2.05, preferably 1.98 to 2.02, more preferably 1.99 to 2.01.

The molecular structure of the organopolysiloxane (A) is preferably linear or linear having a partially branched structure. Specifically, the repeating structure of the diorganosiloxane unit (R ¹ ₂ SiO _2/2 , R ¹ is the same as described above, the same applies hereinafter) constituting the main chain of the organopolysiloxane is repeated from only the dimethylsiloxane unit. Or diphenylsiloxane having a phenyl group, a vinyl group, a 3,3,3-trifluoropropyl group or the like as a substituent as a part of a dimethylpolysiloxane structure composed of repeating dimethylsiloxane units constituting the main chain Those having a diorganosiloxane unit introduced such as a unit, a methylphenylsiloxane unit, a methylvinylsiloxane unit, or a methyl-3,3,3-trifluoropropylsiloxane unit are preferred.

Further, both ends of the molecular chain are, for example, triorganosiloxy groups (R ¹ ₃ SiO _1/2 ) such as trimethylsiloxy group, dimethylphenylsiloxy group, vinyldimethylsiloxy group, divinylmethylsiloxy group, trivinylsiloxy group, hydroxy It is preferably blocked with a hydroxydiorganosiloxy group (R ¹ ₂ (HO) SiO _1/2 ) such as a dimethylsiloxy group.

As described above, the organopolysiloxane of the component (A) has a triorganosiloxy group (R ¹ ₃ SiO _1/2 ) or a hydroxydiorganosiloxy group (R ¹ ₂ (HO) SiO _{1/2 at} both ends of the molecular chain. ) And the main chain is preferably a straight chain composed of repeating diorganosiloxane units (R ¹ ₂ SiO _2/2 ). Particularly preferred are the types of substituents in the molecule (that is, unsubstituted or substituted monovalent hydrocarbon groups bonded to silicon atoms) such as methyl vinyl polysiloxane, methyl phenyl vinyl polysiloxane, methyl trifluoropropyl vinyl. Polysiloxane etc. can be mentioned.

  Such an organopolysiloxane can be obtained by, for example, hydrolyzing and condensing one or more types of organohalogenosilanes, or by making cyclic polysiloxanes (siloxane trimers, tetramers, etc.) alkaline or It can be obtained by ring-opening polymerization using an acidic catalyst.

  The degree of polymerization of the organopolysiloxane is 100 or more (usually 100 to 100,000), preferably 1,000 to 100,000, more preferably 2,000 to 50,000, particularly preferably 3,000 to 3,000. It is preferably 20,000, and is a so-called raw rubber (non-liquid) that does not self-flow at room temperature (25 ° C.). When the degree of polymerization is too small, when the compound (A) and the reinforcing silica (B) described later are uniformly kneaded with a kneader such as a roll mill to form a compound, problems such as sticking to the roll And roll workability deteriorates. The degree of polymerization can be measured, for example, as a weight average degree of polymerization (or weight average molecular weight) in terms of polystyrene by gel permeation chromatography (GPC) analysis using toluene or the like as a developing solvent.

  (A) A component may be used individually by 1 type, or 2 types or 3 or more types of mixtures from which molecular weight (degree of polymerization) and molecular structure differ.

-(B) component-
Component (B), reinforcing silica, is a filler added to obtain a silicone rubber composition having excellent mechanical strength. For this purpose, the specific surface area (BET adsorption method) is 50 m ² / g. It is necessary to be above, preferably 100 to 450 m ² / g, more preferably 100 to 300 m ² / g. When the specific surface area is less than 50 m ² / g, the mechanical strength of the cured product is lowered.

  Examples of such reinforcing silica include fumed silica (fumed silica), precipitated silica (wet silica) and the like, and those whose surfaces are hydrophobized with chlorosilane, hexamethyldisilazane, or the like. Preferably used. Among these, fumed silica excellent in dynamic fatigue characteristics is preferable.

Component (B) may be used alone or in combination of two or more.
(B) The compounding quantity of the reinforcing silica of a component is 5-100 mass parts with respect to 100 mass parts of (A) component organopolysiloxane, and it is preferable that it is 10-50 mass parts. When the blending amount of the component (B) is too small, the reinforcing effect cannot be obtained, and when it is too large, the workability is deteriorated, the mechanical strength is lowered, and the dynamic fatigue durability is also deteriorated. End up.

-(C) component-
As the organic peroxide curing agent of component (C), those selected from alkyl peresters, peroxycarbonates, peroxyketals and diacyl peroxides are preferred. Examples of such organic peroxide curing agents include t-butyl peroxybenzoate. Alkyl peresters such as 1,1-dimethylpropylperoxybenzoate, t-amylperoxy 3,5,5-trimethylhexanoate, t-butylperoxy 3,5,5-trimethylhexanoate, t- Butylperoxy 2-ethylhexyl carbonate, 1,6-bis (t-butylperoxycarbonyloxy) hexane, 1,6-bis (1,1-dimethylpropylperoxycarbonyloxy) hexane, 1,6-bis (1,1-dimethylbutylperoxycarbonyloxy) hexane Peroxycarbonate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-di-t-butylperoxy-3,5,5-trimethylcyclohexane, etc. Diacyl peroxides such as peroxyketal, dibenzoyl peroxide, bis (2-methylbenzoyl) peroxide, bis (4-methylbenzoyl) peroxide, bis (2,4-dichlorobenzoyl) peroxide are preferably used. it can. Even if it is an organic peroxide curing agent, when an organic peroxide curing agent other than the above is used, the cured millable silicone rubber is heated to 100 ° C. or more in a state where it is in contact with the metal substrate. However, there may be a case where a composite molded product in which the silicone rubber and the metal substrate are sufficiently firmly bonded at the contact interface cannot be obtained.

(C) A component may be used individually by 1 type, or may use 2 or more types together.
(C) Although the addition amount of a component is an effective amount, 0.1-10 mass parts is preferable with respect to 100 mass parts of (A) component, and 0.2-5 mass parts is especially preferable. If the blending amount of the component (C) is too small, curing may be insufficient, and if it is too large, the physical properties of the cured silicone rubber may be deteriorated due to the organic peroxide separation residue.

-(D) component-
As the (D) addition reaction type curing agent, a combination of (D-1) an organohydrogenpolysiloxane and (D-2) a hydrosilylation catalyst is used.

As long as the organohydrogenpolysiloxane of component (D-1) contains 2 or more, preferably 3 or more SiH groups in one molecule, linear, cyclic, branched and three-dimensional network. Any of the structures may be used. As the component (D-1), a known organohydrogenpolysiloxane can be used as a crosslinking agent for the addition reaction curable silicone rubber composition. For example, the following average composition formula (II)
R ² _b H _c SiO _{(4-bc) / 2} (II)
Wherein R ² is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and b and c are 0 ≦ b <3, 0 <c ≦ 3 and 0 <b + c. (It is a positive number satisfying ≦ 3.)
The organohydrogen polysiloxane represented by these is mentioned. (D-1) A component may be used individually by 1 type, or may use 2 or more types together.

In the above average composition formula (II), R ² is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms other than aliphatic unsaturated groups. It is preferable. Specific examples of R ² include alkyl groups such as methyl group, ethyl group, and propyl group, cycloalkyl groups such as cyclohexyl group, alkenyl groups such as vinyl group, allyl group, butenyl group, and hexenyl group, phenyl group, and tolyl group. Aryl groups such as benzyl, 2-phenylethyl, aralkyl groups such as 2-phenylpropyl, etc., and groups in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with halogen atoms such as fluorine atoms Examples thereof include a 3,3,3-trifluoropropyl group.

  b and c are positive numbers that preferably satisfy 0.7 ≦ b ≦ 2.4, 0.002 ≦ c ≦ 1, and 0.8 ≦ b + c ≦ 2.7, and more preferably 1 ≦ b ≦ 2. 2, 0.01 ≦ c ≦ 1 and 1.002 ≦ b + c ≦ 2.5.

  The organohydrogenpolysiloxane of component (D-1) has 2 or more (for example, 2 to 300) SiH groups in one molecule, preferably 3 or more (for example, 3 to 200), more preferably 4 to About 100. In the component (D-1), the SiH group may be at the end of the molecular chain, in the middle of the molecular chain (that is, at the non-terminal portion of the molecular chain), or both.

  The number of silicon atoms (or the degree of polymerization) in the organohydrogenpolysiloxane of component (D-1) is preferably 2 to 300, more preferably 3 to 200, and still more preferably about 4 to 100. is there.

  Further, the viscosity of the organohydrogenpolysiloxane of component (D-1) at 25 ° C. is preferably 0.5 to 10,000 mPa · s, more preferably 0.5 to 1,000 mPa · s, particularly preferably 1. ˜300 mPa · s. In the present invention, the viscosity can usually be measured by a rotational viscometer (BL type, BH type, BS type, cone plate type, etc.).

Specific examples of the (D-1) component organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris (hydrogendimethyl). Siloxy) methylsilane, tris (hydrogendimethylsiloxy) phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, trimethylsiloxy group-blocked methylhydrogenpolysiloxane, trimethylsiloxy group at both ends Blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends dimethylhydrogensiloxy group blocked dimethylpolysiloxane, both ends dimethylhydrogensiloxy group blocked methylhydrogenpo Siloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenyl Siloxane / dimethylsiloxane copolymer, both ends trimethylsiloxy-blocked methylhydrogensiloxane / methylphenylsiloxane / dimethylsiloxane copolymer, both ends dimethylhydrogensiloxy-blocked methylhydrogensiloxane / dimethylsiloxane / diphenylsiloxane copolymer , Both ends dimethylhydrogensiloxy group-blocked methylhydrogensiloxane, dimethylsiloxane, methylpheny Copolymer, a copolymer consisting of (CH _{3) 2} HSiO _1/2 units and (CH _{3) 3} SiO _1/2 units and SiO _4/2 units, and (CH _{3) 2} HSiO _1/2 units A copolymer comprising 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; In the exemplified compound, a compound in which part or all of the methyl group is substituted with an alkyl group other than a methyl group such as a propyl group or a butyl group, a phenyl group, a combination thereof, or the like.

（上記式中、ｋは２〜１０の整数であり、ｓ及びｔは０〜１０の整数である。） Specific examples include compounds represented by the following structural formula.

(In the above formula, k is an integer of 2 to 10, and s and t are integers of 0 to 10.)

  (D-1) The compounding quantity of the organohydrogenpolysiloxane of a component has preferable 0.1-40 mass parts with respect to 100 mass parts of (A) component. Further, the number of SiH groups in the component (D-1) is preferably 0.5 to 10 with respect to one aliphatic unsaturated group (for example, an alkenyl group bonded to a silicon atom) in the component (A). It is the quantity which becomes a piece, More preferably, 0.7-5 pieces. When the blending amount is within the above range, crosslinking is easily formed when the resulting composition is cured, and after curing, mechanical strength is likely to be sufficient, and other physical properties, particularly heat resistance and low compression are obtained. Permanent distortion tends to be good.

  The hydrosilylation catalyst of component (D-2) is a catalyst that causes an alkenyl group in component (A) and an SiH group in component (D-1) to undergo an addition reaction. (D-2) A component may be used individually by 1 type, or may use 2 or more types together. Examples of the component (D-2) include a platinum group metal catalyst. Specifically, for example, a platinum group metal simple substance and a compound thereof may be used. As the platinum group metal catalyst, conventionally known catalysts can be used as the catalyst for the addition reaction curable silicone rubber composition. Examples of the platinum group metal catalyst include particulate platinum metal adsorbed on a carrier such as silica, alumina, silica gel, alcohol solution of platinous chloride, chloroplatinic acid, chloroplatinic acid hexahydrate, palladium catalyst, and the like. , Rhodium catalyst and the like, platinum or platinum compounds are preferable.

  The addition amount of the component (D-2) may be an amount that can promote the above addition reaction, and is preferably 1 mass relative to the total amount of the organopolysiloxane of the component (A) in terms of platinum group metal mass. ppm to 1 mass% (10,000 mass ppm), more preferably 2 to 1,000 mass ppm, particularly preferably 10 to 500 mass ppm. When the addition amount is within this range, the addition reaction is easily promoted, curing is likely to be sufficient, and this is economically advantageous.

  In addition to the above catalyst, an addition crosslinking controller may be used for the purpose of adjusting the curing rate. Specific examples thereof include acetylene alcohol-based control agents such as ethynylcyclohexanol, tetracyclomethylvinylpolysiloxane, and the like. An addition crosslinking control agent may be used individually by 1 type, or may use 2 or more types together.

-Other ingredients-
The silicone rubber composition used in the present invention is filled with pulverized quartz, crystalline silica, diatomaceous earth, calcium carbonate, etc. as necessary, in addition to the above components, as long as the object of the present invention is not impaired. Agent, colorant, tear strength improver, heat resistance improver such as iron oxide and cerium oxide, flame retardant improver such as titanium oxide and platinum compound, acid acceptor, heat conductivity improver such as alumina and boron nitride , Various alkoxysilanes as release agents, dispersants for fillers, especially phenyl group-containing alkoxysilanes and their hydrolysates, diphenylsilanediol, carbon functional silanes as surface treatment agents for fillers, silanol group-containing low molecular siloxanes Known fillers and additives in the thermosetting silicone rubber composition may be added. Other components may be used alone or in combination of two or more.

  As a molding method of the millable silicone rubber composition of the present invention, a known molding method may be selected according to the shape and size of the target molded product. For example, methods such as injection molding, compression molding, injection molding, calendar molding, extrusion molding, coating, and screen printing are exemplified. The curing condition may be a known condition in the molding method, and is generally about several seconds to one day at a temperature of 60 to 200 ° C. Further, for the purpose of reducing the compression set of the cured product, reducing the low-molecular siloxane component remaining in the silicone rubber, or removing the decomposition product of the organic peroxide, preferably 100 ° C. or higher, preferably May be post-cured (secondary curing) in an oven at 150 to 250 ° C. for 30 minutes or longer, preferably about 1 to 70 hours, preferably 1 to 10 hours.

Examples of the method for adhering the millable silicone rubber composition of the present invention include the following methods (1) and (2).
(1) A step (I) of curing the millable silicone rubber composition obtained above while being pressure-bonded to a metal substrate, and a cured product (silicone) of the millable silicone rubber composition obtained in the step (I) A step (II) in which a composite molded product of rubber and a metal substrate is heated to 100 ° C. or more to bond the silicone rubber and the metal substrate.
In this case, the millable silicone rubber composition does not adhere to the metal substrate even when the millable silicone rubber composition is cured while being pressed against the metal substrate in the step (I) of curing the composition, In the step (II) of heating to 100 ° C. or higher, it is preferable to adhere to the metal substrate.

  In the method (1), the curing conditions in the step (I) are 60 to 300 ° C., particularly 80 to 200 ° C., more preferably 100 to 180 ° C., 5 seconds to 24 hours, particularly 30 seconds to 30 minutes, Furthermore, it is preferable to set it as 1 to 20 minutes. Moreover, as heating conditions in process (II), it is 100-400 degreeC, Especially 110-300 degreeC, Furthermore, it is 120-250 degreeC, It is preferable to set it as 30 minutes-70 hours, especially 1-10 hours. If it is less than 100 ° C., it takes a very long time for the organic peroxide to decompose and react with the silicone, which is inferior in productivity and uneconomical.

(2) Step (i) of curing the millable silicone rubber composition obtained above in a non-contacting manner with a metal substrate, and contacting (or pressing) the cured millable silicone rubber with a metal substrate. And (ii) the step of heating the millable silicone rubber and the metal base material by heating to 100 ° C. or higher in the state.

  In the method (2), the curing conditions in the step (i) are 60 to 300 ° C., particularly 80 to 200 ° C., further 100 to 180 ° C., 5 seconds to 24 hours, particularly 30 seconds to 30 minutes, Furthermore, it is preferable to set it as 1 to 20 minutes. Moreover, as a heating condition in a process (ii), it is 100-400 degreeC, Especially 110-300 degreeC, Furthermore, it is 120-250 degreeC, It is preferable to set it as 30 minutes-70 hours, especially 1 to 10 hours. If it is less than 100 ° C., it takes a very long time for the organic peroxide to decompose and react with the silicone, which is inferior in productivity and uneconomical.

  In addition, as a metal base material bonded with the silicone rubber composition of this invention, stainless steel, aluminum, iron, copper, etc. can be used.

  By the above method, a composite molded product in which the silicone rubber and the metal substrate are firmly bonded can be efficiently obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to a following example. The polymerization degree is a polystyrene-reduced weight average polymerization degree by GPC analysis using toluene or the like as a developing solvent, and the viscosity is measured by a rotational viscometer.

Adhesion test method The composite member of the cured millable silicone rubber / metal substrate or the composite member of the millable silicone rubber cured / metal substrate obtained below was heat-treated at 200 ° C. for 4 hours. While making a cut with a cutter knife on the adhesive surface between the cured silicone rubber and the metal substrate, a manual peeling test (ie, when the silicone rubber cured product at the cut portion is pulled up by hand in a direction perpendicular to the adhesive surface) (Evaluation of whether the adhesive surface peels or cohesively breaks).

[Preparation of base compound]
100 parts by mass of an organopolysiloxane raw rubber comprising 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units, 0.025 mol% of dimethylvinylsiloxy units and having an average degree of polymerization of about 6,000, BET 35 parts by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g, a silanol group at both ends of the molecular chain as a dispersant, and an average degree of polymerization at 4 and 25 ° C. After adding 6 parts by mass of dimethylpolysiloxane having a viscosity of 15 mPa · s and uniformly kneading at 60 ° C. for 10 minutes, heat treatment is further performed at 170 ° C. for 2 hours to produce a millable silicone rubber compound ( 1) was obtained.

[Example 1]
After adding 0.32 parts by mass of t-amylperoxy 3,5,5-trimethylhexanoate as an alkyl perester to 100 parts by mass of the millable silicone rubber compound (1) and mixing them uniformly, While being pressed against a stainless steel plate having a thickness of 2 mm, press curing was performed at 165 ° C., 10 minutes, and 100 kgf / cm ² for 10 minutes to form a cured silicone rubber layer having a thickness of 2 mm on the stainless steel plate. Thereafter, the cured silicone rubber / stainless steel plate was heat-treated in an oven at 200 ° C. for 4 hours. The adhesiveness between the cured silicone rubber and the stainless steel plate was measured after the press cure and after the heat treatment at 200 ° C. for 4 hours. Table 1 shows the results.

[Example 2]
Instead of t-amylperoxy 3,5,5-trimethylhexanoate, 0.55 parts by mass of 1,6-bis (t-butylperoxycarbonyloxy) hexane was added as a peroxycarbonate. In the same manner as in Example 1, a composite member of a cured silicone rubber / stainless steel plate was produced, and the adhesion was measured in the same manner. Table 1 shows the results.

[Example 3]
0.32 parts by mass of t-amylperoxy 3,5,5-trimethylhexanoate per 100 parts by mass of the millable silicone rubber compound (1) and C25A (Shin-Etsu Chemical Co., Ltd.) as an addition reaction type curing agent ), Platinum catalyst) 0.5 parts by mass and C25B (manufactured by Shin-Etsu Chemical Co., Ltd., organohydrogenpolysiloxane) 2.0 parts by mass were added and mixed uniformly, then 120 ° C., 10 minutes, 100 kgf Press cure was performed for 10 minutes under the conditions of / cm ² to prepare a cured silicone rubber having a thickness of 2 mm. While this cured silicone rubber was brought into contact (pressure bonding) with a stainless steel plate having a thickness of 2 mm as in Example 1, heat treatment was performed in an oven at 200 ° C. for 4 hours. The adhesion between the cured silicone rubber and the stainless steel plate after heat treatment at 200 ° C. for 4 hours was measured. Table 1 shows the results.

[Example 4]
Instead of t-amylperoxy 3,5,5-trimethylhexanoate, except that 0.83 parts by mass of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane was added, A silicone rubber cured product / stainless steel composite member was prepared in the same manner as in Example 1, and the adhesion was measured in the same manner. Table 1 shows the results.

[Example 5]
Instead of t-amylperoxy 3,5,5-trimethylhexanoate, 0.8 parts by mass of bis (4-methylbenzoyl) peroxide as a diacyl peroxide was added, 120 ° C., 10 minutes, 100 kgf / cm ^A cured silicone rubber / stainless steel composite member was prepared in the same manner as in Example 1 except that the press cure was performed for 10 minutes under the condition ² and the adhesion was measured in the same manner. Table 1 shows the results.

[Example 6]
It measured like Example 1 except having replaced with the stainless steel plate and using the aluminum plate of thickness 2mm prescribed | regulated to JISH4000. Table 2 shows the results.

[Example 7]
It measured like Example 3 except having replaced with the stainless steel plate and using the aluminum plate of thickness 2mm prescribed | regulated to JISH4000. Table 2 shows the results.

[Example 8]
It measured like Example 4 except having replaced with the stainless steel plate and using the aluminum plate of thickness 2mm prescribed | regulated to JISH4000. Table 2 shows the results.

[Comparative Example 1]
The measurement was performed in the same manner as in Example 3 except that t-amylperoxy 3,5,5-trimethylhexanoate was not added. Table 3 shows the results.

[Comparative Example 2]
0.8 parts by mass of an organosilicon compound containing a phenylene skeleton represented by the following formula and an SiH group as an adhesive component (adhesion imparting agent) with respect to 100 parts by mass of the millable silicone rubber compound (1), an addition reaction As a mold curing agent, 0.5 parts by mass of C25A (Shin-Etsu Chemical Co., Ltd., platinum catalyst) and 2.0 parts by mass of C25B (Shin-Etsu Chemical Co., Ltd., organohydrogenpolysiloxane) were added. 1. Press-cure at 120 ° C., 10 minutes, 100 kgf / cm ² for 10 minutes while pressing with a 2 mm thick stainless steel plate similar to 1 to form a 2 mm thick silicone rubber cured material layer on the stainless steel plate. Formed. Thereafter, the cured silicone rubber / stainless steel plate was heat-treated in an oven at 200 ° C. for 4 hours. The adhesiveness between the cured silicone rubber and the stainless steel plate was measured after press curing (before heat treatment) and after heat treatment at 200 ° C. for 4 hours. Table 3 shows the results.

[Comparative Example 3]
Measurement was performed in the same manner as in Example 7 except that t-amylperoxy 3,5,5-trimethylhexanoate was not added. Table 4 shows the results.

[Comparative Example 4]
Measurement was performed in the same manner as in Comparative Example 2 except that an aluminum plate having a thickness of 2 mm specified in JIS H 4000 was used instead of the stainless steel plate. Table 4 shows the results.

Claims (7)

(A) The following average composition formula (I)
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) 5 to 100 parts by mass of reinforcing silica having a specific surface area of 50 m ² / g or more according to the BET adsorption method,
(C) an organic peroxide containing an effective amount, and curing (I) a millable silicone rubber composition substantially free of adhesive components while being pressed against a metal substrate; and the step (I) And a step (II) of heating the composite molded product of the millable silicone rubber composition and metal substrate obtained in step 1 to 100 ° C. or higher, and a method for bonding the millable silicone rubber composition.   In the step (I) in which the millable silicone rubber composition cures the composition, the millable silicone rubber composition does not adhere to the metal substrate even if the millable silicone rubber composition is cured while being pressure-bonded to the metal substrate. The method for adhering a millable silicone rubber composition according to claim 1, wherein in the step (II) of heating to a metal substrate, the metal base material is adhered. (A) The following average composition formula (I)
R ¹ _a SiO _{(4-a) / 2} (I)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) 5 to 100 parts by mass of reinforcing silica having a specific surface area of 50 m ² / g or more according to the BET adsorption method,
(C) Organic peroxide A step (i) of curing a millable silicone rubber composition containing an effective amount and containing substantially no adhesive component in a non-contacting manner with a metal substrate, and the cured millable A step (ii) of heating the mold-type silicone rubber to 100 ° C. or higher in a state where the mold-type silicone rubber is pressure-bonded to the metal base material.   The organic peroxide as component (C) is at least one selected from alkyl peresters, peroxycarbonates, peroxyketals, and diacyl peroxides. The millable silicone rubber according to any one of claims 1 to 3. Method for bonding the composition.   The millable silicone rubber composition according to any one of claims 1 to 4, wherein the organopolysiloxane (A) has a polymerization degree of 100 or more and contains at least two alkenyl groups per molecule. Bonding method.   The millable silicone rubber composition further comprises an addition reaction type curing agent comprising a combination of (D-1) organohydrogenpolysiloxane and (D-2) hydrosilylation catalyst as component (D). 6. A method for adhering a millable silicone rubber composition according to any one of 5 above.   The composite molded product of the hardened | cured material of the silicone rubber composition and the metal base material which were adhere | attached by the method of any one of Claims 1-6.