JPH08269331A - Silicone gel composition and potting material - Google Patents

Abstract

PURPOSE: To obtain the subject composition, comprising an organopolysiloxane containing silanol groups, a hydrolyzable organosilicon compound and a hydrolyzing catalyst comprising an organic complex of tin, etc., capable of providing a cross-linked material and suitable as a potting material for various electrical and electronic parts. CONSTITUTION: This composition comprises (A) 100 pts.wt. organopolysiloxane of formula I [R<1> is a (substituted)1-10C monovalent hydrocarbon; (a) is 1.90-2.05; (t) is 0.00002-0.02; [(a) + (b)] is 1.90002-2.07] containing silanol groups, (B) 0.001-10 pts.wt. organosilicon compound, capable of forming siloxane bonds between the components (A) and (B) by the condensation and having the hydrolyzability or its partial hydrolyzate preferably a compound of the formula R<2> m Si(OR<3> )4-m [R<2> is a 1-8C monovalent hydrocarbon; R<3> is a 1-4C alkyl, etc.; (m) is 0-31 or formula II or III [R<4> is a 1-8C bivalent hydrocarbon; (n) is 0-2; (p) is 0-50] and (C) 0.001-10 pts.wt. hydrolyzing catalyst selected from organic complexes of tin, titanium and aluminum. The resultant composition is capable of forming siloxane bonds and providing a cross-linked and cured silicone gel having 20-150 initial penetration.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silicone gel composition suitable for use as a potting material for various electric / electronic parts.

[0002]

2. Description of the Related Art
Silicone elastomers and silicone gels are widely used as potting materials for electric and electronic parts for the purpose of preventing corrosion of electric and electronic parts.

Among these, in the silicone elastomer potting material, an addition reaction curing type or condensation reaction curing type composition is used as the curing mechanism from the viewpoint of use conditions and workability. On the other hand, with respect to the silicone gel potting material, an addition reaction curable composition or a photo (ultraviolet) curable composition is mainly used in view of workability.

However, a silicone gel cured product obtained by such an addition reaction curing or an ultraviolet curing has sufficient heat resistance under normal use conditions in the atmosphere and exhibits performance such as corrosion prevention. However, in an atmosphere in which an oxidizing gas such as ozone or NO _x is present, especially under high temperature conditions of 100 ° C. or higher, the cured product of the silicone gel is softened or dissolved, and the original performance is not exhibited. . Therefore, when the electric / electronic parts sealed with the silicone gel potting material are placed in the above-mentioned high temperature oxidizing gas atmosphere, for example, around the engine of an automobile, the sealing effect is reduced, and the electric / electronic parts are Corrosion often occurred.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a silicone gel composition and a silicone gel potting material which give a silicone gel cured product excellent in high temperature oxidation resistance.

[0006]

Means for Solving the Problems The present inventors have conducted diligent studies to achieve the above-mentioned object, and as a result, the silicone gel cured product obtained by the above addition reaction curing and ultraviolet curing is easily oxidized in a high temperature oxidizing atmosphere. It was found that the cause of this is the curing mechanism. That is, the addition reaction curable type containing a Si—CH═CH ₂ group and a Si—H group as the functional group of the crosslinking site has a silethylene group, and the ultraviolet curable type has a crosslinked portion or a polymerized portion such as an acrylic functional group. Ozone and N
It has been found that oxidation occurs in an oxidizing atmosphere in which O _x or the like is present, especially at high temperature, and the bond is cleaved, which causes softening and dissolution of the cured silicone gel product. Based on such knowledge, the present inventor has conducted further studies and, as a result, has found that after curing, a bonding group (for example, a C—C bond or a C bond) via a carbon atom.
A curing mechanism that does not generate a -O bond), that is, a siloxane bond (≡Si-O-S) such as a dealcoholization or deketone (for example, acetone) condensation crosslinking or a dehydrogenation condensation mechanism.
By forming i≡), the silicone gel composition having a curing mechanism that functions as a new bond gives a cured product having excellent high temperature oxidation resistance, and for example, potting of electric / electronic parts used around an engine of an automobile. When used as a material, ozone and NO generated during fuel combustion
_The present invention has been completed by discovering that even when exposed to an oxidizing gas such as _x or SO _x , the properties of the gel can be maintained and electric / electronic parts can be protected from corrosion.

That is, the present invention provides (A) 100 parts by weight of silanol group-containing organopolysiloxane represented by the following average composition formula (1): R ¹ _a (HO) _b SiO _{(4-ab) / 2} (1 (In the formula, R ^1's are the same or different from each other and represent a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is 1.90).
˜2.05, b is a positive number from 0.00002 to 0.02, and a + b is 1.90002 to 2.07. ) (B) Hydrolyzable organosilicon compound or a partial hydrolyzate thereof which forms a siloxane bond by condensation with the (A) component 0.001 to 10 parts by weight (C) Organic compounds of tin, titanium and aluminum A silicone gel containing 0.001 to 10 parts by weight of a hydrolysis catalyst selected from a complex, and giving a crosslinked silicone gel cured product with an initial penetration of 20 to 150 by forming a siloxane bond. A composition is provided. The present invention also provides a potting material for electric / electronic parts, which comprises the silicone gel composition.

[0008] In the present invention, the silicone gel is a crosslinked structure having a three-dimensional network structure, and is described in JIS K
6301 has a hardness of 0 or less at 25 ° C., that is, it does not have an effective rubber hardness value, that is, a general silicone rubber or an elastomer cured product (usually JIS K630
1 shows a value of about 5 or more at a rubber hardness of 1), and a silicone gel generally has A
The STM D-1403 (1/4 cone) has a puncture value of 200 or less at 25 ° C., but in the present invention, the initial puncture value is 20 to 1 in particular.
It discloses a composition that gives a gel cured product having a value of 50.

The present invention will be described in more detail below. The first component used in the silicone gel composition of the present invention is a silanol group-containing organosiloxane [component (A)] represented by the following average composition formula (1). , This has at least one silanol group at the end of the molecular chain, especially one at each end of the molecular chain, and one at each end of the molecular chain if there is a branched structure (ie, bonded to a silicon atom). It is preferable that it has a hydroxyl group). R ¹ _a (HO) _b SiO _{(4-ab) / 2} (1)

Here, R ¹ is the same or different from each other, and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, especially 1 to 8 carbon atoms, which does not have an aliphatic unsaturated bond. preferable. Specifically, a methyl group, an ethyl group, a propyl group,
Isopropyl group, butyl group, isobutyl group, tert-
Alkyl groups such as butyl group, hexyl group, cyclohexyl group, octyl group, decyl group, vinyl group, allyl group,
Alkenyl groups such as propenyl group and butenyl group, aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group, aralkyl groups such as benzyl group and phenylethyl group,
Alternatively, a chloromethyl group, a bromoethyl group, a 3,3,3-trifluoropropyl group, a cyanoethyl group or the like in which some or all of hydrogen atoms of these groups are substituted with a halogen atom, a cyano group or the like can be given.

Further, a is 1.90 to 2.05, and particularly 1.
95-2.00 is a positive number, and b is 0.00002-
0.02, particularly a positive number of 0.0001 to 0.01,
a + b is 1.90002 to 2.07, especially 1.9501
~ 2.06.

The silanol group-containing organopolysiloxane can be used either linearly or branchedly, and the viscosity at 25 ° C. is preferably 10 to 100,000 cp, more preferably 100 to 10,000 cp. If the viscosity is out of this range, the workability in casting the electric / electronic component case may be deteriorated.

Specific examples of the silanol group-containing organopolysiloxane include the following compounds. In the following examples, Me represents a methyl group and Ph represents a phenyl group.

[0014]

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The above-mentioned organosiloxane can be produced by carrying out an equilibrium reaction using a desired organocyclopolysiloxane or organopolysiloxane oligomer as a raw material with an alkali or acid catalyst.

Next, the hydrolyzable organosilicon compound or the partial hydrolyzate of the second component [component (B)] of the present invention acts as a curing agent for the component (A). Here, the composition of the present invention, as described above, does not contain a bridge via a carbon atom,
This is a silicone gel having stable softness without causing cleavage of bonds due to an oxidizing gas. Therefore, the crosslinked structure relating to curing of the silicone gel composition has dealcohol condensation, deketone (for example, acetone)
Condensation or dehydrogenative condensation crosslinking is effective. That is, a cross-linking mechanism that functions as a new bond by forming a siloxane bond (≡Si-O-Si≡) is required. In this case, in deamine condensation, hydroxyamine, which is a leaving group, causes corrosion of electric and electronic parts and the like, which is not preferable as a potting material.

From this point of view, the de-alloying is performed as a curing reaction.
When using the Cole condensation reaction or the deketone condensation reaction,
As the component (B), ≡Si—O—R³A small number of groups in the molecule
Organosilicon compound having at least one, preferably at least two
Thing, especially the following general formulas (2) to (4) R² _mSi (OR³)_4-m … (2) R² _nSi (OR³)_3-n-R^Four-Si (OR³)_3-n-R _n … (3) R³ O- [Si (OR³)₂-O]_p-Si (OR³)₃ (4) Organosilane, organosiloxane, or
Existence of ganosil alkylene, organosilarylene, etc.
One or more organic silicon compounds or partial hydrolysates thereof
The above is preferable. Here, the partial hydrolyzate is
≡Si-O-R in the molecule after hydrolysis³At least
It means a product having one, preferably two or more.

Here, R ² is the same or different from each other, and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, which does not have an aliphatic unsaturated bond. Preferred are those mentioned above, and examples thereof include the same groups as R ¹ described above.
R ³ is an alkyl group or alkenyl group having 1 to 4 carbon atoms, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, vinyl group, allyl group, propenyl group. Group, isopropenyl group, butenyl group, isobutenyl group and the like. R ⁴ is a divalent hydrocarbon group having 1 to 8 carbon atoms, preferably 2 to 4, for example, an alkylene group such as a methylene group, an ethylene group, a propylene group, a methylethylene group, a tetramethylene group, a hexamethylene group, a phenylene group, An arylene group such as a methylphenylene group, a combination of these alkylene groups and arylene groups, and the like are preferable, and an alkylene group is particularly preferable.

M is an integer of 0 to 3, and 0, 1 or 2 is particularly preferable. Further, n is independently an integer of 0 to 2, and 0 or 1 is particularly preferable. Furthermore, p is 0
50, especially an integer from 1 to 10.

Specific examples of the organic silicon compound include the following compounds. In the formulas below, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, Ph represents a phenyl group, and Vi represents a vinyl group. R'Si (OMe) ₃ R'Si (OEt) ₃ R'Si (OC (CH ₃ ) = CH ₂ ) ₃ (R '= Me, Et, Pr, Ph or Vi) (MeO) ₃ Si-CH _{2 -CH 2 -Si (OMe) 3 MeO-} (Si (OMe) 2 -O) 5 -Si (OMe) 3

When a dehydrogenative condensation reaction is used as the curing reaction, the hydrolyzable organosilicon compound (B) is an organohydrogen having two or more Si--H groups in one molecule. Polysiloxane can be used. As the organohydrogenpolysiloxane, those represented by the following average composition formula (5) R ⁷ _c (H) _d SiO _{(4-cd) / 2} (5) can be used.

[0022] Here, R ⁷ is from 1 to 10 carbon atoms of the same or different from each other, in particular 1-8 monovalent hydrocarbon group, preferably having no aliphatic unsaturated bond, and R ¹ as described above Similar groups may be mentioned. Also, c is 1.0 ≦ c ≦
2.55, preferably 1.0 ≦ c ≦ 2.4, d is 0.00
5 ≦ d ≦ 1.3, preferably 0.05 ≦ d ≦ 1.0, c +
d is 1 <c + d <2.7, preferably 2 ≦ c + d ≦ 2.4.
Is a positive number that satisfies.

The above organohydrogenpolysiloxane may be any of linear, branched, cyclic, and resinous substances having a three-dimensional network structure, and its viscosity at 25 ° C. is 0.1 to 1000 cp, and particularly 0.1. It is preferably 5 to 500 cp.

The following compounds may be mentioned as specific examples of the organohydrogenpolysiloxane.
In the examples below, Me represents a methyl group.

[0025]

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The blending amount of the component (B) is 0. 100 parts by weight based on 100 parts by weight of the organopolysiloxane of the component (A).
001 to 10 parts by weight, particularly 0.1 to 1 part by weight is suitable. If the compounding amount is less than 0.001 part by weight, curing may not occur, and if it exceeds 10 parts by weight, it may become too hard.

The hydrolysis catalyst [component (C)] which is the third component of the present invention can function as a hydrolysis catalyst for the component (B), and is an organic complex of tin, titanium and aluminum, such as an ester compound. , Alcoholate compounds,
It is selected from acetylacetonate compounds and the like. Specific examples include the following compounds, and tin complexes are preferably used from the viewpoint of workability such as reactivity and pot life. ^{Sn (O-CO-R 5} ) 2 R 5 2 Sn (O-CO-R 5) 2 Ti (OR 6) 4 Al (acac) 3 Al (CH 3 COCOOCOOR 5) 3

In the formula, R ⁵ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 15 which is the same as or different from each other, and examples thereof are the same as those of R ¹ described above. However, an alkyl group is particularly preferable. R ⁶ is an alkyl group having 1 to 10 carbon atoms,
It is preferably an ethyl group, a propyl group or a butyl group.
acac represents an acetylacetonate group.

The blending amount of the above-mentioned component (C) is 0. 100 parts by weight relative to 100 parts by weight of the organopolysiloxane of the above-mentioned component (A).
001 to 10 parts by weight, particularly 0.1 to 2 parts by weight is desirable, and if it is less than 0.001 parts by weight, the catalytic effect may not be sufficiently obtained, and if it exceeds 10 parts by weight, a sufficient pot life is obtained. It may not be obtained and may be economically disadvantageous.

The composition of the present invention may contain other components in addition to the above-mentioned essential components, and if necessary, a filler,
Pigments, adhesion aids and the like can be added. Further, an organopolysiloxane other than the above-mentioned component (A) can be added within a range that does not impair the effects of the present invention.

The silicone gel composition of the present invention can be prepared by uniformly mixing the above-mentioned components (A) to (C) and curing it at room temperature (for example, 10 to 30 ° C.) or under heating.
For example, in the case of dealcoholization or deketone condensation type, it is usually at 10 to 40 ° C. for about 5 minutes to 200 hours, and in the case of dehydrogenation condensation type, 60 to 180 ° C., particularly 80 to 150 ° C.
It is cured under the conditions of about minutes to 2 hours to form a silicone gel cured product. The initial penetration of the cured product of this silicone gel needs to be 20 to 150, preferably 50 to 130 at 25 ° C. When it is less than 20, the gel becomes hard and the sealed electrical / electronic component is If it is larger than 150, the gel is likely to flow out.

The silicone gel composition of the present invention is
It is effectively used as a potting material for electronic parts, particularly for electric / electronic parts placed in an atmosphere in which an oxidizing gas such as ozone, NO _x , SO _x exists, and especially at a high temperature of 100 ° C. or higher.

[0033]

EFFECT OF THE INVENTION The silicone gel composition and potting material of the present invention have excellent high-temperature oxidation resistance, are hard to be oxidized even when exposed to oxidizing gases such as ozone and NO _x , and have stable flexibility for a long period of time. It provides a silicone gel cured product having corrosion resistance.

[0034]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group. In addition, “part” means “part by weight”, and the viscosity, penetration, and rubber hardness are all 25 ° C.
Is the value of.

[Examples 1 to 3 and Comparative Examples 1 and 2] The components of each example shown in Table 1 were mixed and the composition was cured in a glass petri dish under each curing condition shown in Table 1 to obtain a silicone gel. Got Next, the initial penetration of each silicone gel was measured, and the penetration of the gel after the oxidation resistance test was performed by the following method was measured. The penetration is ASTM D-
According to 1403, measurements were made using a 1/4 scale cone. Table 2 shows the results. The rubber hardness according to JIS K6301 of each of these silicone gel cured products was 0 (flexible, showing no finite value). Oxidation resistance test [25 ° C test] (1) Put a sample whose initial penetration was measured in a test container,
Install in a constant temperature room at 25 ° C. (2) The electrodes are energized and sparks between the electrodes cause O ₃ , NO _x.
Is generated (O ₃ ≈200 ppm, NO _x ≈300 pp
m). (3) Discharged for 300 hours and then 2 of the samples after durability test
Measure the penetration at 5 ° C. [130 ° C. test] (1) Put a sample whose initial penetration was measured in a test container,
The test container is heated in a dryer at 130 ° C. (2) The electrodes are energized and sparks between the electrodes cause O ₃ , NO _x.
Is generated (O ₃ ≈200 ppm, NO _x ≈300 pp
m). (3) Discharged for 300 hours and then 2 of the samples after durability test
Measure the penetration at 5 ° C. The test container is 2000 liters in a 3 liter desiccator.
The one provided with an electrode capable of applying an applied voltage of 0 V was used.

[0036]

[Table 1]

[0037]

[Table 2]

From the results shown in Table 2, it is recognized that the cured silicone gel product of the present invention can maintain the original flexibility of the gel even under the conditions of room temperature and high temperature oxidizing atmosphere.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Ikeno, Masayuki Ikeno, 1-person, Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Kazuyasu Sato Matsui, Usui-gun, Gunma Prefecture Tamachi Daiji Hitomi 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (5)

[Claims] 1. A silanol group-containing organopolysiloxane represented by the following average composition formula (1):
100 parts by weight R ¹ _a (HO) _b SiO _{(4-ab) / 2}
(1) (In the formula, R ^1's are the same or different from each other and represent a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is 1.90.
˜2.05, b is a positive number from 0.00002 to 0.02, and a + b is 1.90002 to 2.07. ) (B) Hydrolyzable organosilicon compound or a partial hydrolyzate thereof which forms a siloxane bond by condensation with the (A) component 0.001 to 10 parts by weight (C) Organic compounds of tin, titanium and aluminum A silicone gel containing 0.001 to 10 parts by weight of a hydrolysis catalyst selected from a complex, and giving a crosslinked silicone gel cured product with an initial penetration of 20 to 150 by forming a siloxane bond. Composition. 2. The component (B) is represented by the following general formula (2):
(4) R² _mSi (OR³)_4-m … (2) R² _nSi (OR³)_3-n-R^Four-Si (OR³)_3-n-R _n … (3) R³ O- [Si (OR³)₂-O]_p-Si (OR³)₃ (4) (where R is²Are the same or different, substituted or unsubstituted
A monovalent hydrocarbon group having 1 to 8 carbon atoms, R³Has 1 to 4 carbon atoms
Alkyl group or alkenyl group, R^FourIs a carbon number 1-8
Represents a valent hydrocarbon group, m is an integer of 0 to 3, and n is respectively
Independently, it is an integer of 0 to 2 and p is an integer of 0 to 50. )
Organosilicon compound selected from the group or partial hydrolysates thereof
The silicone gel composition according to claim 1, which is 3. The component (B) comprises two or more S in one molecule.
The silicone gel composition according to claim 1, which is an organohydrogenpolysiloxane having an i-H group. Wherein component (C), the following compound ^{Sn (O-CO-R 5} ) 2 R 5 2 Sn (O-CO-R 5) 2 Ti (OR 6) 4 Al (acac) 3 Al (CH ₃ COCOOCOOR ⁵ ) ₃ (In the formula, R ⁵ is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ⁶ is 1 to 1 carbon atoms.
The alkyl group of 0 and acac represent an acetylacetonate group. 4. The silicone gel composition according to claim 1, which is selected from the group consisting of: 5. A potting material for electric / electronic parts, which comprises the silicone gel composition according to any one of claims 1 to 4.