JPH11106734A - Adhesive polyorganosiloxane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can be cured at low temperatures within a short time and adheres to a plastic substrate by including a polyorganosiloxane selected among alkenyl-containing polyorganosiloxanes, linear and branched polyorganohydrogensiloxanes, a platinum compound, a specified organosilicon compound and an organoaluminum compound. SOLUTION: This composition comprises an Si-bonded-H-containing polyorganosiloxane selected among an Si-bonded-alkenyl-containing polyorganosiloxane, a linear polyorganohydrogensiloxane of formula I and a branched polyorganohydrogensiloxane comprising (CH3 )2 HSiO1/2 units and SiO2 units, a platinum compound, an organosilicon compound having at least one Si-bonded H atom and a group of formula II, etc., and an organoalumninum compound. In the formulas, p is 3-100, q is 0-100; Q<1> and Q<2> are each a linear or branched alkylene; and R' is a 1-4C alkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyorganosiloxane composition, in particular, which cures in a short time at a low temperature of 90 ° C. or less and can be firmly applied to a plastic substrate such as polycarbonate without using a primer. Adhesive, adhesive polyorganosiloxane compositions.

[0002]

A disadvantage of organosiloxane compositions which cure by a hydrosilylation reaction is their inability to adhere strongly to many substrates, especially plastics. One way to overcome this drawback is
The use of a primer composition or adhesion promoter comprising a silane or organosiloxane having a plurality of silicon-bonded hydrolyzing groups and at least one organic functional substituent bonded to silicon by at least one carbon atom. The primer composition is applied to the substrate to be bonded prior to application of the curable organosiloxane composition. An adhesion promoter is one component of the curable organosiloxane composition. In the prior art, a combination of an epoxy compound and an organoaluminum compound is described in JP-A-60-101146 in order to obtain strong adhesion to plastic. In this patent, polyphenylene oxide (PPO) and polybutylene terephthalate (PBT) showed good adhesion, but polycarbonate (PC)
Was not obtained. Also, JP-A-56-15
In Japanese Patent No. 1758, at least one hydrogen atom bonded to a silicon atom in a molecule is represented by the general formula (II):

[0003]

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Wherein Q ¹ and Q ² represent a linear or branched alkylene group, and R ¹ represents an alkyl group having 1 to 4 carbon atoms in the molecule. A silicon compound and a general formula

[0005]

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(Wherein, R ² is a substituted or unsubstituted monovalent hydrocarbon group, and e is a number represented by 0 to 2). Exemplifies adhesiveness to a PC. However, in this patent, when the compound of the formula (III) is added in an amount of 50 parts or more, the physical properties of the cured product are remarkably deteriorated, and the heating conditions are not higher than 90 ° C. for 3 hours, which is not practical. Japanese Patent Application Laid-Open No. 62-240361 also exemplifies the adhesiveness to a PC board by using a combination of γ-methacryloxypropyltrimethoxysilane and aluminum acetylacetonate.
Since a long time h is required, adverse effects on the PC board such as deformation of the PC board are feared. Other proposals for improving the adhesiveness using an alkoxysilane containing an unsaturated group or an alkoxysilane containing an epoxy group include JP-A-50-26855, JP-A-54-34362, and JP-A-2-28280. However, none of them require heating at 100 ° C. or higher or curing conditions at 70 ° C. × 6 hours, and are not intended for PC bonding.

[0007]

An object of the present invention is to solve the problems of the prior art and to provide an addition-reaction type polyorganosiloxane composition which shows rapid self-adhesion to PC at a low temperature of 90 ° C. or less and in a short time. Aim.

[0008]

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that the type of polyorganohydrogensiloxane, which is a crosslinking agent for the addition-reaction type polyorganosiloxane composition, and the SiH content in the composition. The present inventors have found that it is extremely effective to limit the ratio of the group to the alkenyl group to 0.7 to 1.5, and to use an organosilicon compound or an organoaluminum compound containing an alkoxy group in combination. That is, the present invention relates to (A) a polyorganosiloxane containing an alkenyl group bonded to a silicon atom in a molecule.
Parts by weight, (B) general formula (I)

[0009]

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Wherein p is an integer of 3 to 100 and q is an integer of 0 to 100, and (CH ₃ ) ₂ HSiO _1/2 and SiO ₂ units A branched polyorganohydrogensiloxane comprising
A polyorganosiloxane containing a hydrogen atom bonded to a silicon atom in a molecule selected from the group consisting of: an amount of hydrogen atom bonded to a silicon atom per one alkenyl group in the composition;
(C) Platinum compound, (A)
(D) one or more organosilicon compounds selected from the group consisting of the following (a) to (c), in which the amount of platinum atom is 1 to 200 ppm based on the component, 0.1 to 20 parts by weight (a) At least one bonded hydrogen atom in the molecule is represented by the general formula (II):

[0011]

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Wherein, in the formula, Q ¹ and Q ² represent a linear or branched alkylene group, and R ¹ represents an alkyl group having 1 to 4 carbon atoms; An organosilicon compound having at least two alkoxy groups bonded to an atom and at least one epoxy group in the molecule; and (c) at least one alkoxy group bonded to a silicon atom in the molecule and unsaturated. At least one double bond in the molecule
An adhesive polyorganosiloxane composition containing (E) an organoaluminum compound and 0.01 to 5 parts by weight.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The alkenyl group-containing polyorganosiloxane of the component (A) used in the present invention has an alkenyl group directly bonded to a silicon atom, and the siloxane skeleton may be either linear or branched, or a mixture thereof. Good. Examples of the alkenyl group include vinyl, allyl, 1-butenyl, 1-hexenyl, and the like, but a vinyl group is preferable because of ease of synthesis. Substituents bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl and dodecyl; aryl groups such as phenyl; 2-phenylethyl;
Aralkyl groups such as 2-phenylpropyl; substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl; Of these, a methyl group is most preferable because it is easy to synthesize, has a degree of polymerization necessary for maintaining good physical properties after curing, and maintains a low viscosity before curing. When cold resistance or special optical properties are required for the cured composition, a phenyl group is included in the molecule, and when oil resistance is required, a 3,3,3-trifluoropropyl group is contained. , Can be arbitrarily selected. Further, the component (A) serves as a base polymer of an addition-reaction type curable polyorganosiloxane, and accounts for 0.05 mol% of all organic groups bonded to silicon atoms.
It is necessary that the above is an alkenyl group. The viscosity is not particularly limited, but is preferably 20 cP or more at 25 ° C., and particularly preferably 700 cP or more when a rubber-like elastic body having particularly good mechanical properties is intended. 25
Desirable ones are less than 0,000 cP.

The polyorganohydrogensiloxane of the component (B) used in the present invention is crosslinked by an addition reaction with the component (A) to form a rubber-elastic body or a gel-like substance. An essential component having at least two hydrogen atoms per silicon atom and at most one silicon atom per silicon atom. Organic groups bonded to silicon atoms other than hydrogen atoms include alkyl groups having 1 to 6 carbon atoms, phenyl groups and
It is a group selected from the group consisting of a 3,3,3-trifluoropropyl group, and a methyl group is most preferable in terms of easy synthesis. Such a polyorganohydrogensiloxane may have a siloxane skeleton that is linear, branched or cyclic. Specific examples of the component (B) include the following. (a) General formula (I)

[0015]

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(Wherein p represents an integer of 3 to 100 and q represents an integer of 0 to 100). Linear polyorganohydrogensiloxane (b) (CH ₃ ) ₂ HSiO _1/2 and SiO ₂ units A branched polyorganohydrogensiloxane comprising the general formula (IV)

[0017]

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(Wherein p represents an integer of 1 to 100 and q represents an integer of 0 to 100), such as a linear polyorganohydrogensiloxane having hydrogen atoms at both ends, and the like. If used, the cause is unknown, but foaming is considered to be caused by the dehydrogenation reaction at the contact interface with PC, which is not preferable. The amount of component (B) is such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.7 to 1.5, preferably 0.9, per alkenyl group in the composition. It is an amount that becomes ~ 1.2 pieces.
(B) If the amount of the component is too small than the above amount,
90 ° C if the curing of the composition does not proceed sufficiently and is too much
Adhesion development in the following is significantly reduced.

The component (C) used in the present invention is a hydrosilylation catalyst. Examples of the platinum-based catalyst used here include Lamorrow's catalyst (platinum-octanol complex, US Pat. No. 474337).
No. 7), Ashby's catalyst (platinum-vinyl group-containing cyclic siloxane complex, U.S. Pat. No. 4,288,345),
Examples thereof include Karstedt's catalyst (a platinum-vinyl group-containing disiloxane complex, U.S. Pat. No. 3,814,730). The amount of the component (C) in the present invention is 1 to 200 ppm as platinum atom with respect to the component (A), and preferably 3 to 100 ppm in consideration of curability and physical properties after curing.

The organosilicon compound of the component (D) used in the present invention is at least one selected from the group consisting of the following components (a), (b) and (c). The organosilicon compound as the component (a) is usually a silane derivative or a polysiloxane derivative. However, for ease of synthesis, the Si-H bond and the group represented by the general formula (II) are separated into separate siloxane units. Preferably, it has a polysiloxane skeleton contained therein. Here, Q ¹ is a hydrocarbon group having a carbon chain of 2 or more carbon atoms, particularly a general formula:

[0021]

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(Wherein R ³ represents a hydrogen atom or a methyl group). Q ² is preferably a hydrocarbon group having a carbon chain of 3 or more carbon atoms, particularly a propylene group, from the viewpoint of hydrolysis resistance. Examples of the alkyl group having 1 to 4 carbon atoms for R ^{1 in} the general formula (II) include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. A methyl group and an ethyl group are preferred because they exhibit excellent adhesion. Such a siloxane unit containing a side chain can be synthesized by a method such as adding a trialkoxysilylpropyl ester of acrylic acid or methacrylic acid to a partial Si-H bond in the molecule. The siloxane skeleton of such an organosilicon compound may be cyclic or chain-like, or a mixture thereof. However, those having a cyclic polysiloxane skeleton are most preferable because of ease of synthesis. In the case of a ring, the number of silicon atoms forming a siloxane ring is 3 to 6, preferably 4, for ease of synthesis. In the case of a chain, if the molecular weight is large, the viscosity becomes high and the synthesis and handling become inconvenient. Therefore, 2 to 20, preferably 4 to 10 silicon atoms forming the siloxane chain are used.

The organosilicon compound as the component (b) is an alkoxysilane or siloxane containing an epoxy group. In order to improve the adhesion to a substrate, the organosilicon compound must have at least three alkoxy groups bonded to a silicon atom. Is more preferred. Examples of such a compound include silanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-glycidoxypropylmethyldiethoxysilane. And the following formula:

[0024]

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Examples are siloxanes, and γ-glycidoxypropyltrimethoxysilane is most preferred.

The organosilicon compound as the component (c) is an alkoxysilane or siloxane having an unsaturated double bond,
In order to improve the adhesion to the substrate, it is more preferable that there are three or more alkoxy groups bonded to the silicon atom. Examples of the unsaturated double bond include alkenyl groups such as vinyl group and allyl group; acryloyl group, methacryloyl group,
Examples include groups such as an acryloxypropyl group and a methacryloxypropyl group. Such organosilicon compounds include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxyprolmethyldimethoxysilane, and the following formula:

[0027]

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The silane represented by the following formula is exemplified, and γ-methacryloxypropyltrimethoxysilane is most preferred.

These organosilicon compounds of the components (a), (b) and (c) are all useful as an adhesion-imparting agent for an addition-reaction composition and can be used alone.
In order to further improve the adhesion to the base material, two or more of the components (a), (b) and (c) may be used in combination. The amount of the component (D) is 0.1 to 20 parts by weight based on 100 parts by weight of the component (A). If the amount is less than 0.1 part by weight, a sufficient adhesive strength cannot be obtained, and if it exceeds 20 parts by weight, the mechanical properties of the cured elastic body deteriorate.

The component (E) used in the present invention comprises (MeO) ₃ Al, (E
(tO) ₃ Al, aluminum alcoholates such as (s-PrO) ₃ Al, aluminum salts such as naphthenic acid, stearic acid, octylic acid or benzoic acid, and the reaction of aluminum alcoholates with acetoacetic esters or dialkyl malonates. Can be

[0031]

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Examples thereof include an aluminum chelate, an organic acid salt of aluminum osakiide, and aluminum acetylacetonate. Of these, aluminum chelate or aluminum alcoholate is preferred from the viewpoint of hydrolysis. Further, bisethyl acetoacetate aluminum monoacetylacetonate or acetoalkoxyaluminum diisopropylate is preferred because it is liquid and convenient to handle. Component (E) is added in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, per 100 parts by weight of component (A). If the amount is less than 0.01 part by weight, good adhesiveness cannot be obtained, and if it exceeds 5 parts by weight, heat resistance becomes poor.

In addition to the components (A) to (E), various inorganic or organic fillers may be used to improve physical properties. Examples of the filler include fumed silica, silica airgel, pulverized silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, calcium carbonate, carbon black, and the like. The amount of these fillers and the like used is arbitrary as long as the object of the present invention is not impaired. Further, in the composition of the present invention, known reaction regulators, for example, 1,3,5,7-tetravinyl-1,3,5,7-tetramethyloctacyclosiloxane, acetylene alcohol,
Triallyl isocyanurate, acetylene group-containing silane or siloxane may be blended. Further, in practicing the present invention, the composition of the present invention may be used by dispersing or dissolving it in a suitable organic solvent such as toluene or xylene depending on the use.

[0034]

The polyorganosiloxane composition of the present invention is cured by heating at a relatively low temperature and for a short time, and exhibits adhesiveness. Therefore, the composition of the present invention is useful as an adhesive for plastics to which high temperatures cannot be applied. Moreover, the cured product formed by heating exhibits excellent adhesive strength to the substrate, and does not peel off from the substrate even when left in high temperature and high humidity or in hot water for a long time.

[0035]

Examples of the present invention will be described below. In the following Examples and Comparative Examples, all parts are parts by weight. The following abbreviations are used to simplify the description. Me: Methyl group Et: Ethyl group Vi: Vinyl group The additives used in Examples and Comparative Examples and methods for evaluating adhesiveness are shown below.

[0036]

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Two polycarbonate plates of 80 mm × 25 mm × 2 mm are placed in parallel with their long sides overlapping by 10 mm, and a thickness of 1 mm is placed between the two polycarbonate plates so as to be in contact with two opposing surfaces of the overlapped portion. Further, a layer of the composition obtained by the following Examples or Comparative Examples was formed, heated at 80 ° C. for 1 hour, and allowed to cool to prepare a sample. A sample was similarly prepared for the PBT plate. The sample thus obtained was mounted on a tensile tester, and an adhesion test was performed at a tensile speed of 10 mm / min.

Example 1 100 parts of α, ω-divinylpolydimethylsiloxane having a viscosity of 350 cP at 25 ° C., a viscosity of 40 cSt at 25 ° C., the end of which is blocked with a trimethylsilyl group, 50 mol% of dimethylsiloxy units and 1.23 parts of polymethylhydrogensiloxane consisting of gen units, 2% by weight
Of Karlstedt's platinum-containing catalyst, 0.1 part of the additives shown in Table 1, and 0.03 part of 1-ethynyl-1-cyclohexanol were uniformly mixed to prepare a composition. Example 2 1.95 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Example 3 2.6 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Example 4 1.88 parts of the aforementioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Example 5 2.6 parts of the aforementioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Example 6 3.45 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Comparative Example 1 3.61 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Comparative Example 2 4.34 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Comparative Example 3 5.78 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Comparative Example 4 5.06 parts of the above-mentioned polymethylhydrogensiloxane,
A composition was prepared in the same manner as in Example 1 except that the additives shown in Table 1 were used. Table 1 shows the evaluation results of the adhesiveness.

[0039]

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI (C08L 83/07 83:05)

Claims (1)

[Claims] (A) 100 parts by weight of a polyorganosiloxane containing an alkenyl group bonded to a silicon atom in a molecule, (B) a compound represented by the following general formula (I): (Wherein p represents an integer of 3 to 100 and q represents an integer of 0 to 100), and a branch comprising (CH ₃ ) ₂ HSiO _1/2 and SiO ₂ units. Polyorganohydrogensiloxane, a polyorganosiloxane containing a hydrogen atom bonded to a silicon atom in a molecule selected from the group consisting of: a hydrogen atom bonded to a silicon atom with respect to one alkenyl group in the composition; 1.5
(C) Platinum-based compound, Platinum atomic weight is 1 to component (A).
(D) at least one organosilicon compound selected from the group consisting of (a) to (c) below, 0.1 to 20 parts by weight (a) at least hydrogen atoms bonded to silicon atoms in the molecule One and the general formula (II): Wherein Q ¹ and Q ² represent a linear or branched alkylene group, and R ¹ represents an alkyl group having 1 to 4 carbon atoms; (b) a bond to a silicon atom An organosilicon compound having at least two alkoxy groups in the molecule and at least one epoxy group in the molecule; (c) at least one alkoxy group bonded to the silicon atom in the molecule and an unsaturated double bond At least one in the molecule
An adhesive polyorganosiloxane composition comprising (E) an organoaluminum compound having 0.01 to 5 parts by weight.