WO2017094357A1

WO2017094357A1 - Self-adhesive silicone gel composition and silicone gel

Info

Publication number: WO2017094357A1
Application number: PCT/JP2016/080237
Authority: WO
Inventors: 正荒木
Original assignee: 信越化学工業株式会社
Priority date: 2015-11-30
Filing date: 2016-10-12
Publication date: 2017-06-08
Also published as: JP6465219B2; JPWO2017094357A1

Abstract

Provided are: a self-adhesive silicone gel composition which exhibits excellent adhesiveness to a base that is present in an electronic board and is formed of copper, aluminum or the like, while maintaining the characteristics of conventional sealing materials, and which is capable of suppressing the occurrence of separation or voids after adhesion; and a silicone gel which is composed of a cured product of this composition. According to the present invention, an aliphatic organic compound that contains one or more isocyanate groups in each molecule but does not contain a hydrolyzable group is added in a specific amount into an addition-curable silicone gel composition.

Description

Self-adhesive silicone gel composition and silicone gel

The present invention relates to a silicone gel composition excellent in self-adhesiveness, and a silicone gel comprising a cured product thereof, and particularly has good adhesion to a substrate such as copper and aluminum, and is free from peeling and voids after adhesion. The present invention relates to a self-adhesive silicone gel composition capable of suppressing generation and a silicone gel comprising a cured product of the composition.

The silicone gel composition contains an organohydrogenpolysiloxane having a hydrogen atom (ie, SiH group) bonded to a silicon atom, an organopolysiloxane having an alkenyl group such as a vinyl group bonded to a silicon atom, and a platinum-based catalyst. The addition reaction curable organopolysiloxane composition is obtained by obtaining a cured product by addition reaction of hydrogen atoms bonded to silicon atoms to alkenyl groups. The silicone gel cured product cured by heating this silicone gel composition is excellent in heat resistance, weather resistance, oil resistance, cold resistance, electrical insulation, etc. It is used to protect electronic parts such as parts and consumer electronic parts. The low elastic modulus and low stress characteristic of silicone gel cured products are not found in other elastomer products. In recent years, high adhesiveness with a base material is required for silicone gel materials used for sealing because of demands for high reliability of in-vehicle electronic parts and consumer electronic parts.

In recent years, various demands for improving adhesiveness have been studied because of such demands. Among them, Japanese Patent Publication No. 07-098902, Japanese Patent No. 5025917, Japanese Patent No. 5179302, Japanese Patent No. 5687148, Japanese Patent No. 5602385, Japanese Patent No. 5361964, Japanese Patent Application Laid-Open No. 2002-338833 (Patent Literature). 1 to 7) have adhesive components that exhibit high adhesiveness, that is, have hydrolyzable groups such as methoxy groups and ethoxy groups in the molecule and functional groups such as epoxy groups, isocyanate groups, and isocyanur groups. Adhesion is improved using a silane coupling agent. However, when a substance having a hydrolyzable group as described above is added, by-products generated by hydrolysis with moisture, that is, alcohols such as methanol and ethanol are gasified by heat released from the electronic material. Thus, there has been a problem that peeling occurs from the interface with the base material or voids called voids are generated. Further, depending on the silane coupling agent used, the catalytic ability of the platinum catalyst used as a curing catalyst is lowered, so that there is a problem that the flexibility changes over time or becomes uncured.
In JP-A-63-199276, JP-B 04-077865, JP-B 05-066773, and JP 2741460 (Patent Documents 8 to 11), adhesion due to addition of an organic peroxide is disclosed. Improvement techniques have been introduced, but this also causes a problem that peeling and voids occur due to oxygen generated as a by-product.

Furthermore, in Japanese Patent Application Laid-Open Nos. 2000-309711, 2005-350582, and 4960620 (Patent Documents 12 to 14), the structure of the organopolysiloxane used, the structure of hydrosilyl group (SiH group), etc. are described. Although the technology to improve the adhesiveness by changing it has been introduced, the adhesion with the base material is certainly improved with this method, but the adhesive has not been reached yet, so the adhesiveness will deteriorate with long-term use There was a problem.

Japanese Patent Publication No. 07-098902 Japanese Patent No. 5025917 Japanese Patent No. 5179302 Japanese Patent No. 5587148 Japanese Patent No. 5602385 Japanese Patent No. 563964 JP 2002-338833 A Japanese Unexamined Patent Publication No. 63-199276 Japanese Examined Patent Publication No. 04-077865 Japanese Patent Publication No. 05-066733 Japanese Patent No. 2741460 JP 2000-309711 A JP-A-2005-350582 Japanese Patent No. 4960620

The present invention has been made to solve such problems, and is sufficient for a base material composed of copper, aluminum, etc. existing in an electronic substrate while maintaining the characteristics of a conventional sealing material. An object of the present invention is to provide a self-adhesive silicone gel composition having adhesiveness and capable of suppressing the occurrence of peeling and voids after adhesion, and a silicone gel comprising a cured product of the composition.

As a result of intensive studies to achieve the above object, the present inventors have found that an addition reaction curable silicone gel composition has at least one isocyanate group in one molecule and contains a hydrolyzable group. It has been found that by adding a certain amount of a non-aliphatic organic compound, it can be a self-adhesive silicone gel composition having no adhesion to the substrate and no peeling or voiding after bonding, and has led to the present invention. .

Accordingly, the present invention provides the following self-adhesive silicone gel composition and silicone gel.
[1]
(A) The following average composition formula (1)
R _a R ¹ _b SiO _{(4-ab) / 2} (1)
Wherein R is independently an alkenyl group, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and a is a positive number of 0.0001 to 0.2 And b is a positive number from 1.7 to 2.2, where a + b is 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule: 100 parts by mass,
(B) The following average composition formula (2)
R ² _c H _d SiO _{(4-cd) / 2} (2)
(Wherein R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, c is a positive number of 0.7 to 2.2, and d is 0.001. (It is a positive number of ~ 0.5, where c + d is 0.8 ~ 3.0.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: 0 hydrogen atom bonded to a silicon atom per alkenyl group bonded to a silicon atom in the entire composition .01-3 quantity,
(C) platinum-based catalyst: effective amount,
(D) Aliphatic organic compound having at least one isocyanate group in one molecule and not containing a hydrolyzable group: Self-adhesive comprising 0.001 to 1.0 part by mass as an essential component Silicone gel composition.
[2]
(D) component is the following general formula (3)
X—C _n H _m —NCO (3)
(In the formula, n is an integer of 1 to 10, m is an integer of 2 to 20, provided that n and m are n <m, and X is a functional group other than a hydrolyzable group.)
The self-adhesive silicone gel composition according to [1], which is an aliphatic organic compound represented by the formula:
[3]
The self-adhesive silicone gel composition according to [1] or [2], which is cured to give a cured silicone gel having a penetration of 10 to 80 as defined by JIS K2220.
[4]
[1] A silicone gel comprising a cured product of the self-adhesive silicone gel composition according to any one of [3].

The self-adhesive silicone gel composition of the present invention provides a cured silicone gel with better adhesion than before and less occurrence of peeling and voids after adhesion.

The self-adhesive silicone gel composition of the present invention comprises the following components (A) to (D) as essential components. In the present invention, a silicone gel (silicone gel cured product) is a cured product having an organopolysiloxane as a main component and a low crosslinking density, and has a penetration of 10 to 10 according to JIS K2220 (1/4 cone). 80 means. This is equivalent to a measured value (rubber hardness value) of 0 in rubber hardness measurement according to JIS K6253, which is so low that it does not show an effective rubber hardness value (ie, soft). It is different from a rubber cured product (rubber-like elastic body).

Hereinafter, each component will be described in detail. In addition, in this specification, a viscosity is a value in 25 degreeC.

[(A) Organopolysiloxane]
(A) component of this invention is the main ingredient (base polymer) of a silicone gel composition. The component (A) is an average of alkenyl groups bonded to silicon atoms in one molecule represented by the following average composition formula (1) (referred to herein as “silicon atom-bonded alkenyl groups”). An organopolysiloxane having at least one.
R _a R ¹ _b SiO _{(4-ab) / 2} (1)
Wherein R is independently an alkenyl group, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and a is a positive number of 0.0001 to 0.2 And b is a positive number from 1.7 to 2.2, where a + b is 1.9 to 2.4.)

In the above formula (1), R is independently an alkenyl group usually having 2 to 6, preferably 2 to 4, more preferably 2 to 3 carbon atoms. Specific examples thereof include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and an isobutenyl group, and a vinyl group is preferable. R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and the number of carbon atoms is usually 1 to 10, preferably 1 to 6. Specific examples thereof include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, pentyl groups, hexyl groups, cyclohexyl groups, octyl groups, decyl groups and other alkyl groups; phenyl groups An aryl group such as a tolyl group; an aralkyl group such as a benzyl group or a phenylethyl group; a chloromethyl group in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom such as chlorine, bromine or fluorine; Examples include 3,3-trifluoropropyl group. Among them, a methyl group, a phenyl group, or a 3,3,3-trifluoropropyl group is preferable because synthesis is easy.

Further, a needs to be a positive number from 0.0001 to 0.2, and is preferably a positive number from 0.0005 to 0.1. b needs to be a positive number of 1.7 to 2.2, and is preferably a positive number of 1.9 to 2.02. However, a + b needs to satisfy the range of 1.9 to 2.4, and preferably 1.95 to 2.05.

The component (A) needs to have at least one silicon atom-bonded alkenyl group on average in the molecule as the whole component (A), preferably 2 to 50, more preferably 2 to 10 Have one. What is necessary is just to select the value of said a and b so that the conditions of this silicon atom bond alkenyl group may be satisfy | filled.

The molecular structure of the organopolysiloxane of component (A) is not particularly limited, and even if it is linear, for example, RSiO _3/2 unit, R ¹ SiO _3/2 unit (R and R ¹ are the same as above) , A branched chain containing a SiO ₂ unit or the like may be used.

(Wherein R ³ independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and R ⁴ independently represents an unsubstituted or substituted monovalent radical that does not contain an aliphatic unsaturated bond. A hydrocarbon group or an alkenyl group, provided that at least one, preferably 2 to 50, more preferably 2 to 10, R ⁴ is an alkenyl group, and either R ⁴ at both ends of the molecular chain is an alkenyl group. E is an integer of 40 to 1,200, f is an integer of 0 to 50, g is an integer of 0 to 50, and both R ⁴ at both ends of the molecular chain are alkenyl. When it is not a group, e is an integer of 40 to 1,200, f is an integer of 1 to 50, g is an integer of 0 to 50, provided that f + g is 1 or more.)
Is preferably a linear diorganopolysiloxane in which the main chain basically consists of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. .

In the above formula (1a), the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond represented by R ³ is usually one having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples thereof include those exemplified for R ¹ . Among them, a methyl group, a phenyl group, or a 3,3,3-trifluoropropyl group is preferable because synthesis is easy.

Of the groups represented by R ⁴ , the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond is usually one having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples thereof include those exemplified for R ¹ . Among them, a methyl group, a phenyl group, or a 3,3,3-trifluoropropyl group is preferable because synthesis is easy. Of the groups represented by R ⁴ , the alkenyl group is usually one having 2 to 6, preferably 2 to 4, more preferably 2 to 3 carbon atoms. Specific examples thereof include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and an isobutenyl group, and a vinyl group is preferable.

In the above formula (1a), when either R ⁴ at both ends of the molecular chain is an alkenyl group, e is an integer of 40 to 1,200, f is an integer of 0 to 50, and g is An integer from 0 to 50, preferably e is an integer from 100 to 1,000, f is an integer from 0 to 40, and g is 0. When neither R ⁴ at both ends of the molecular chain is an alkenyl group, k is an integer of 40 to 1,200, f is an integer of 1 to 50, and g is an integer of 0 to 50. However, f + g is 1 or more, preferably k is an integer of 100 to 1,000, f is an integer of 2 to 40, and g is 0.

Examples of the organopolysiloxane represented by the above formula (1a) include dimethylpolysiloxane having both ends dimethylvinylsiloxy group-blocked dimethylpolysiloxane, dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, and both ends dimethylvinylsiloxy. Blocked dimethylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy-blocked methyltrifluoropropylpolysiloxane, both ends dimethylvinylsiloxy Block-capped dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, both ends dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxa・ Methyl vinyl siloxane copolymer, trimethylsiloxy group-blocked dimethylsiloxane at both ends ・ Vinylmethylsiloxane copolymer, trimethylsiloxy group-blocked dimethylsiloxane at both ends ・ Vinylmethylsiloxane ・ diphenylsiloxane copolymer, trimethylsiloxy group-blocked vinyl at both ends Methylsiloxane / methyltrifluoropropylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylpolysiloxane, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group・ Dimethylvinylsiloxy group-blocked dimethylsiloxane ・ diphenylsiloxane copolymer, terminal trimethylsiloxy group ・ dimethylvinylsiloxy group-blocked di Tyrsiloxane / diphenylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped methyltrifluoropropylpolysiloxane, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane copolymer Copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both end methyldivinylsiloxy group-capped dimethylpolysiloxane, both end methyldivinylsiloxy group-capped dimethylsiloxane / methyl Vinylsiloxane copolymer, methyldivinylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer at both ends, Tyrdivinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends methyldivinylsiloxy group-blocked methyltrifluoropropylpolysiloxane, both ends methyldivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane copolymer , Both ends methyldivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both ends trivinylsiloxy group-blocked dimethylpolysiloxane, both ends trivinylsiloxy-blocked dimethylsiloxane / methylvinylsiloxane copolymer Copolymer, Trivinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, both ends trivinylsiloxy group-capped dimethylsiloxane / Tyrvinylsiloxane / diphenylsiloxane copolymer, trivinylsiloxy group-blocked methyltrifluoropropyl polysiloxane at both ends, trivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, trivinylsiloxy group-blocked at both ends Examples thereof include dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer.

The viscosity of the organopolysiloxane of component (A) is not particularly limited, but the viscosity at 25 ° C. is 50 to 100,000 mPa from the point that the handling workability of the composition, the strength of the resulting cured product, and the fluidity are good. S is preferable, and 100 to 10,000 mPa · s is more preferable. The viscosity can be measured with a rotational viscometer (for example, BL type, BH type, BS type, cone plate type, rheometer, etc.) (hereinafter the same). The viscosity range is such that the degree of polymerization (or the number of silicon atoms in the molecule) of the organopolysiloxane (A) is usually 30 to 1,500, preferably 50 to 1,000, more preferably 100 to This is equivalent to about 600. The degree of polymerization (or molecular weight) can be determined, for example, as the number average degree of polymerization (or number average molecular weight) in terms of polystyrene in gel permeation chromatography analysis using toluene or the like as a developing solvent (hereinafter the same).

The organopolysiloxane of component (A) can be used alone or in combination as long as it satisfies the condition that the entire component (A) has at least one silicon-bonded alkenyl group on average in one molecule. A combination of the above may also be used. For example, in the present invention, an organopolysiloxane having two alkenyl groups bonded to silicon atoms in one molecule, particularly at both ends of the molecular chain, and a silicon atom bonded in one molecule, particularly at one end of the molecular chain. Organopolysiloxane having one alkenyl group or organopolysiloxane having less than one (for example, organopolysiloxane having the same average degree of polymerization and distribution of polymerization degree and having one alkenyl group bonded to a silicon atom at one end of the molecular chain) And a uniform mixture of an organopolysiloxane containing no alkenyl group in the molecule, etc.) in a mass ratio of about 100: 0 to 40:60, particularly 100: 0 to 60:40. It is preferable because the composition has good curability and can stably obtain a soft (high penetration) silicone gel cured product. .

[(B) Organohydrogenpolysiloxane]
Next, the component (B) of the present invention reacts with the component (A) and acts as a crosslinking agent (curing agent). The component (B) has the following average composition formula (2)
R ² _c H _d SiO _{(4-cd) / 2} (2)
(Wherein R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, c is a positive number of 0.7 to 2.2, and d is 0.001. (It is a positive number of ~ 0.5, where c + d is 0.8 ~ 3.0.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule. This organohydrogenpolysiloxane has preferably 3 to 500, more preferably 5 to 100, and particularly preferably 10 to silicon-bonded hydrogen atoms (ie, a hydrosilyl group represented by SiH) in one molecule. 60. The SiH group may be bonded to the silicon atom at the end of the molecular chain or may be bonded to the silicon atom at the non-terminal end of the molecular chain (in the middle of the molecular chain). Good.

In the above formula (2), R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and the number of carbon atoms is usually 1 to 10, preferably 1 to 6. is there. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group. An alkyl group such as phenyl group, tolyl group, xylyl group, naphthyl group, etc .; aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group, etc .; And a 3,3,3-trifluoropropyl group substituted with a halogen atom such as bromine and fluorine. Of these, an alkyl group, an aryl group, and a 3,3,3-trifluoropropyl group are preferable, and a methyl group, a phenyl group, and a 3,3,3-trifluoropropyl group are more preferable.

Further, c is a positive number of 0.7 to 2.2, and is preferably a positive number of 1.0 to 2.1. d is a positive number of 0.001 to 0.5, and is preferably a positive number of 0.005 to 0.1. Further, c + d is 0.8 to 3.0, preferably 1.0 to 2.5, and more preferably 1.5 to 2.2.

The molecular structure of the organohydrogenpolysiloxane of component (B) is not particularly limited, and may be any of a linear, cyclic, branched, and three-dimensional network (resinous) structure. The number of silicon atoms (that is, the degree of polymerization) is usually 10 to 1,000, but the workability of the composition and the properties of the resulting cured product (low elastic modulus, low stress) are improved. Therefore, the number is preferably 10 to 500, more preferably 15 to 100, and still more preferably 20 to 60.

Examples of the organohydrogenpolysiloxane represented by the above formula (2) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and methylhydrogensiloxane. Cyclic polymer, tris (dimethylhydrogensiloxy) methylsilane, tris (dimethylhydrogensiloxy) phenylsilane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane, both Terminal dimethylhydrogensiloxy group-blocked methylhydrogen / dimethylsiloxane copolymer, both-end dimethylhydrogensiloxy group-blocked methylhydrogen / diphenylsiloxane copolymer, both-end dimethyl Hydroxysiloxy group-blocked methylhydrogen / dimethylsiloxane / diphenylsiloxane copolymer, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends, trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, trimethyl at both ends Examples thereof include a siloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, a trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer at both ends, and the like.

The (B) component organohydrogenpolysiloxane may be used singly or in combination of two or more. In the present invention, organohydrogenpolysiloxane having 2 or more, particularly 3 or more hydrogen atoms bonded to silicon atoms in the middle of the molecular chain (side chain), and hydrogen atoms bonded to silicon atoms at both ends of the molecular chain It is possible to mix and use organohydrogenpolysiloxane having 2 (only) in a mass ratio of about 100: 0 to 5:95, particularly about 100: 0 to 8:92. A favorable and flexible (high penetration) silicone gel cured product is preferred because it can be stably obtained.

Component (B) is added in an amount of 0.01 to 3 hydrogen atoms bonded to silicon atoms relative to one alkenyl group bonded to silicon atoms in the entire composition (that is, component (A) above), preferably Is in an amount of 0.05 to 2, more preferably 0.2 to 1.5. When the number of hydrogen atoms bonded to silicon atoms from the component (B) is less than 0.01 with respect to one alkenyl group in the whole composition, a cured product cannot be obtained. Moreover, when more than three, the heat resistance of hardened | cured material falls.

[(C) Platinum catalyst]
The component (C) of the present invention is a catalyst (platinum group metal catalyst) for promoting the addition reaction between the silicon atom-bonded alkenyl group of the component (A) and the silicon atom-bonded hydrogen atom in the component (B). It is what is used. The component (C) is a platinum-based catalyst (platinum or a platinum-based compound), and a known one can be used. Specific examples thereof include alcohol-modified products such as platinum black, chloroplatinic acid, and chloroplatinic acid; complexes of chloroplatinic acid and olefins, aldehydes, vinyl siloxanes, acetylene alcohols, and the like.

The compounding amount of the component (C) may be an effective amount, and can be appropriately increased or decreased depending on the desired curing rate. Usually, it is in the range of 0.1 to 1,000 ppm, preferably 1 to 300 ppm. If the amount is too large, the heat resistance of the resulting cured product may decrease.

[(D) Aliphatic organic compound having one or more isocyanate groups in one molecule and containing no hydrolyzable group]
Component (D) of the present invention contains at least one isocyanate group in one molecule and does not contain a hydrolyzable group, and contains an aromatic ring structure such as a benzene ring (for example, a phenylene group) in the molecule. It is an aliphatic organic compound that does not, and is an essential component for imparting excellent adhesiveness to the silicone gel composition of the present invention. The component (D) is preferably an aliphatic organic compound represented by the following general formula (3).
X—C _n H _m —NCO (3)
(In the formula, n is an integer of 1 to 10, m is an integer of 2 to 20, provided that n and m are n <m, and X is a functional group other than a hydrolyzable group.)

In the above formula (3), n is an integer of 1 to 10, preferably an integer of 3 to 8, m is an integer of 2 to 20, preferably 6 to 16, and n and m must always satisfy n < It is preferable to use an aliphatic organic compound that satisfies the relationship of m and has one or more, preferably two, isocyanate groups in one molecule and does not contain a hydrolyzable group. It is essential for this. In the case of n = m or n> m, there are many conjugated or non-conjugated double bonds in the molecule, which may reduce the compatibility with silicone oil.
Moreover, as long as X is a functional group other than a hydrolyzable group, any functional group can be used. Of these, an isocyanate group is particularly effective because the same effect can be obtained even if the amount of component (D) is small.

Specific examples of the aliphatic organic compound having at least one isocyanate group in one molecule of component (D) and not containing a hydrolyzable group include butyl isocyanate, tert-butyl isocyanate, hexyl isocyanate, heptyl isocyanate, X in the formula (3) such as cyclopentyl isocyanate, cyclohexyl isocyanate and other compounds having one isocyanate group in the molecule, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate is an isocyanate group A compound having two isocyanate groups in the molecule, an isocyanate compound having a halogen group as X in formula (3), such as 2-chloroethyl isocyanate, 2-fluoroethyl isocyanate, etc. There are exemplified, compounds wherein X is the isocyanate group of the formula (3) Among them, it is particularly preferred to use hexamethylene diisocyanate.

The amount of component (D) added is in the range of 0.001 to 1.0 part by weight, preferably 0.005 to 0.2 part by weight, more preferably 100 parts by weight of component (A). The range is 0.01 to 0.1 parts by mass. (D) When the addition amount of a component is less than 0.001 mass part, the adhesiveness expected with respect to copper or aluminum cannot be expressed. Moreover, when the addition amount of (D) component exceeds 1.0 mass part, since the platinum-type catalyst of (C) component is stabilized more by the isocyanate group of (D) component, hardening may become slow or obtained. The resulting silicone gel is too soft or in the worst case uncured.

[Other optional ingredients]
In addition to the components (A) to (D), an optional component can be blended in the silicone gel composition of the present invention as long as the object of the present invention is not impaired. As this optional component, for example, reaction inhibitor, inorganic filler, organopolysiloxane containing no silicon atom-bonded hydrogen atom and silicon atom-bonded alkenyl group, heat resistance imparting agent, flame retardancy imparting agent, thixotropic property imparting agent, Examples thereof include pigments and dyes.

The reaction inhibitor is a component for suppressing the reaction of the composition, and specifically includes, for example, acetylene-based, amine-based, carboxylic acid ester-based, phosphite-based reaction inhibitor, and the like. It is done.

Examples of inorganic fillers include fumed silica, crystalline silica, precipitated silica, hollow filler, silsesquioxane, fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, and calcium carbonate. Inorganic fillers such as zinc carbonate, layered mica, carbon black, diatomaceous earth, and glass fiber; these fillers are organic silicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low molecular weight siloxane compounds. Examples thereof include a surface hydrophobized filler. Silicone rubber powder, silicone resin powder, and the like may also be blended.

[Curing the silicone gel composition]
The silicone gel composition of the present invention can be prepared by mixing the above components (A) to (D) (including optional components when optional components are blended) according to a conventional method. At that time, the components to be mixed may be divided into two or more parts and mixed as necessary, for example, (A) part or all of the component and (C) the part consisting of the component and It is also possible to divide and mix the remainder of the component (A) and the part composed of the components (B) and (D). When storing the uncured composition at room temperature, a part consisting of part or all of the component (A) and the component (C), the remainder of the component (A) and the part consisting of the components (B) and (D) It is more preferable to divide into

Thereafter, the silicone gel composition of the present invention is heated at room temperature (25 ° C. ± 10 ° C.) or under a heating temperature according to the application (for example, about 35 to 150 ° C., particularly about 50 to 130 ° C.) for 10 to 120 minutes. In particular, a cured silicone gel can be obtained by curing for about 30 to 60 minutes.

The silicone gel composition of the present invention is preferably used for sealing or filling electric / electronic parts.

The cured product (silicone gel or silicone gel cured product) of the silicone gel composition of the present invention preferably has a penetration of 10 to 80, more preferably 20 to 20 with a 1/4 cone defined by JIS K2220. 70, more preferably 30-60. If the penetration is less than 10, the silicone gel composition may not be able to withstand the stress at the time of curing, and a part of the electronic circuit may be broken or a crack may be generated inside the silicone gel. Moreover, when the penetration exceeds 80, since it is too soft, if the silicone gel cured product is largely deformed, it may be easily peeled off or the adhesion to the substrate may be reduced.

Further, the cured product of the silicone gel composition of the present invention has a loss factor at 25 ° C. and a shear frequency of 1 Hz, preferably 0.1 to 1.0, more preferably 0.12 to 0.8, and still more preferably 0. The loss factor at 25 ° C. and a shear frequency of 10 Hz is preferably 0.3 to 1.5, more preferably 0.35 to 1.2, and still more preferably 0.4 to 1. 0. When the loss factor at 25 ° C. and shear frequency of 1 Hz is less than 0.1, the silicone gel composition cannot withstand the stress at the time of curing, and part of the electronic circuit breaks or cracks are generated inside the silicone gel. Sometimes. In addition, when the loss coefficient at 25 ° C. and a shear frequency of 10 Hz exceeds 1.5, a cured silicone gel having sufficient shape retention ability cannot be obtained, and the adhesion to the substrate is the same as described above. May decrease.

Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the following examples are not intended to limit the present invention. In the examples, “part” represents “part by mass”, “%” represents “mass%”, and “Vi” represents “vinyl group”. Further, the penetration is a penetration with a ¼ cone defined by JIS K2220, and was measured using an automatic penetration meter RPM-101 manufactured by Kouaisha.

[Example 1]
The following average molecular formula (4)

60 parts of a dimethylvinylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer having a viscosity at 25 ° C. of 1,000 mPa · s represented by the following average molecular formula (5)

40 parts of a trimethylsiloxy group / vinyldimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer having a viscosity at 25 ° C. of 700 mPa · s, the following average molecular formula (6)

0.55 parts of a trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity at 25 ° C. of 100 mPa · s at the both ends, the following average molecular formula (7):

5.6 parts of dimethylpolysiloxane blocked with dimethylhydrogensiloxy group-terminated dimethylpolysiloxane having a viscosity at 25 ° C. of 18 mPa · s ((B) per silicon atom-bonded vinyl group in the composition) The number of silicon-bonded hydrogen atoms in the component (hereinafter referred to as H / Vi) was 1.15), and dimethyl chloroplatinate siloxane complex containing 1% platinum atom as component (C). A composition 1 was obtained in which 0.05 part of the polysiloxane solution, 0.02 part of ethynylcyclohexanol, which is an optional component, and 0.01 part of hexamethylene diisocyanate, which is the component (D), were uniformly mixed. When the obtained composition 1 was heat-cured at 80 ° C. for 60 minutes, a cured silicone gel having a penetration of 45 was obtained.
(Hexamethylene diisocyanate; in the above formula (3), n = 6, m = 12, n <m, X = NCO)

[Example 2]
In Example 1, composition 2 was obtained in the same manner except that 0.015 part of hexyl isocyanate was used instead of 0.01 part of hexamethylene diisocyanate. When this composition 2 was heat-cured at 80 ° C. for 60 minutes, a cured silicone gel having a penetration of 42 was obtained.

[Comparative Example 1]
A composition 3 was obtained in the same manner as in Example 1 except that hexamethylene diisocyanate was not used. This composition 3 was cured by heating at 80 ° C. for 60 minutes to obtain a cured silicone gel having a penetration of 40.

[Comparative Example 2]
In Example 1, the composition 4 was obtained similarly except having added 0.01 part of tolylene diisocyanate instead of using 0.01 part of hexamethylene diisocyanate. When this composition 4 was heat-cured at 80 ° C. for 60 minutes, a cured silicone gel having a penetration of 48 was obtained.
(Tolylene diisocyanate; in the above formula (3), n = 7, m = 6, n> m, X = NCO)

[Comparative Example 3]
A composition 5 was obtained in the same manner as in Example 1, except that 0.01 part of γ-glycidoxypropyltrimethoxysilane was added instead of 0.01 part of hexamethylene diisocyanate. When this composition 5 was heat-cured at 80 ° C. for 60 minutes, a cured silicone gel having a penetration of 35 was obtained.

[Comparative Example 4]
A composition 6 was obtained in the same manner as in Example 1, except that 0.01 part of 3-isocyanatopropyltriethoxysilane was added instead of 0.01 part of hexamethylene diisocyanate. When this composition 6 was heat-cured at 80 ° C. for 60 minutes, a cured silicone gel having a penetration of 45 was obtained.

[Comparative Example 5]
A composition 7 was obtained in the same manner as in Example 1 except that the amount of hexamethylene diisocyanate was changed to 1.5 parts. When this composition 7 was heat-cured at 80 ° C. for 60 minutes, it was not cured, so a cured product could not be obtained.

[test]
The following tests were carried out using the silicone gel cured products obtained in Examples 1 and 2 and Comparative Examples 1 to 4. These results are shown in Table 1.

Evaluation of adhesion;
The composition obtained as described above was poured into 80 ° C. so that a shear adhesion test body having an adhesion area of 2.5 mm ² and an adhesion thickness of 2 mm could be produced using oxygen-free copper and aluminum each having a width of 25 mm and a length of 100 mm. And cured by heating for 1 hour. Thereafter, measurement was carried out by a method according to JIS K6249, and the shear adhesive strength and the cohesive failure rate (ratio of the cohesive failure area to the entire area of the fracture surface (%)) were confirmed. In addition, evaluation of a cohesive failure rate makes 80% or more pass.

Void test;
About 5 g of the composition obtained above was poured into an aluminum petri dish having a diameter of 60 mm and a depth of 10 mm, and was cured by heating at 80 ° C. for 1 hour. Then, after being left in an environment of 85 ° C. × 85% RH for 24 hours, it was immediately exposed on a hot plate at 110 ° C., and after 1 hour, it was visually confirmed whether peeling or void occurred at the interface with the aluminum petri dish. Those in which no peeling or void was confirmed were regarded as acceptable.

Evaluation of storage stability;
The Example and Comparative Example are divided into two components, and the uncured liquid is allowed to stand for 12 months in a 25 ° C. environment, and then both are prepared and mixed so as to have the same mixing ratio as in the Example and Comparative Example. In the same manner, the penetration and adhesion were evaluated. In addition, when making it into two components, it divided | segmented as follows and stored in the container which can interrupt | block moisture.
(First component) (A), (C) component (second component) (B), (D) component and optional component

[Evaluation]
It can be seen that the compositions of Examples 1 and 2 satisfy the requirements of the present invention, and the cured product of the composition has good adhesiveness, and no peeling or void has been confirmed after bonding. . Moreover, when the components were divided and the storage stability was evaluated, it was confirmed that there was no change in the penetration and adhesiveness.
On the other hand, since the composition of Comparative Example 1 does not contain the component (D) of the present invention, it can be seen that the cured product of the composition has poor adhesion to oxygen-free copper or aluminum.
Further, the composition of Comparative Example 2 does not satisfy the requirement of the aliphatic organic compound (specifically, n <m in the formula (3)), which is the condition of the component (D) of the present invention. The cured product of the composition has poor adhesion to oxygen-free copper. This is presumed to be because when n> m, that is, since many conjugated or non-conjugated double bonds exist in the molecule, the compatibility with silicone oil decreases.
In the case of the composition of Comparative Example 3, since an epoxy group-containing silane coupling agent is added instead of the component (D) of the present invention, the cured product is free from peeling and voids by a void test. It is confirmed that the result does not reach the expected adhesiveness.
In the case of the composition of Comparative Example 4 in which a compound containing an isocyanate group and a hydrolyzable group was blended, it was the same as above, and the cured product of the composition was confirmed to be peeled or voided by a void test. In addition, the expected adhesiveness is not achieved.
Further, in the case of the composition of Comparative Example 5 in which a large amount of the component (D) of the present invention was added, the platinum catalyst of the component (C) was stabilized by the component (D), and thus cured at a predetermined temperature and time. I couldn't get anything. From this, the effectiveness of the present invention can be confirmed.

The silicone gel cured product obtained by curing the silicone gel composition of the present invention adheres well to a substrate used for an electronic substrate, particularly a substrate such as copper or aluminum, and peels off after bonding. It is possible to manufacture an electronic component with less generation of voids and improved long-term reliability. Therefore, improvement in reliability is expected in the protection application of electronic parts such as IC and hybrid IC.

Claims

(A) The following average composition formula (1)
R a R 1 b SiO (4-ab) / 2 (1)
Wherein R is independently an alkenyl group, R 1 is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and a is a positive number of 0.0001 to 0.2 And b is a positive number from 1.7 to 2.2, where a + b is 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule: 100 parts by mass,
(B) The following average composition formula (2)
R 2 c H d SiO (4-cd) / 2 (2)
(Wherein, R 2 is an unsubstituted or substituted monovalent hydrocarbon group independently contains no aliphatic unsaturated bonds, c is a positive number of 0.7 ~ 2.2, d is 0.001 (It is a positive number of ~ 0.5, where c + d is 0.8 ~ 3.0.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: 0 hydrogen atom bonded to a silicon atom per alkenyl group bonded to a silicon atom in the entire composition .01-3 quantity,
(C) platinum-based catalyst: effective amount,
(D) Aliphatic organic compound having at least one isocyanate group in one molecule and not containing a hydrolyzable group: Self-adhesive comprising 0.001 to 1.0 part by mass as an essential component Silicone gel composition.
(D) component is the following general formula (3)
X—C n H m —NCO (3)
(In the formula, n is an integer of 1 to 10, m is an integer of 2 to 20, provided that n and m are n <m, and X is a functional group other than a hydrolyzable group.)
The self-adhesive silicone gel composition according to claim 1, which is an aliphatic organic compound represented by the formula:
The self-adhesive silicone gel composition according to claim 1 or 2, which is cured to give a cured silicone gel having a penetration of 10 to 80 as defined by JIS K2220.
A silicone gel comprising a cured product of the self-adhesive silicone gel composition according to any one of claims 1 to 3.