JP2014034679A - Curable silicone composition and cured material of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable silicone composition for forming a cured material excellent in heat resistance and to provide the cured material excellent in heat resistance.SOLUTION: A curable silicone composition comprises at least (A) organopolysiloxane represented by average composition formula: RSiO, where R is a halogen substituted or unsubstituted monovalent hydrocarbon group, 0.1 to 2.1 mol% of R is an alkenyl group, and a is a number of 1.9 to 2.4, (B) organopolysiloxane having average 2 silicon atom-bounding hydrogen atoms in a molecule, wherein an amount of silicon atom-bounding hydrogen atoms in the component is 0.1 to 3.0 mol on the basis of 1 mole of the alkenyl group in the component (A), and (C) a platinum-based catalyst, and the content of the (C) component satisfies that the amount of a platinum atom is, by mass unit, 10 to 100 ppm on the basis of the composition and contents of both natrium and potassium are 3 ppm or less by mass unit on the basis of the composition.

Description

  The present invention relates to a curable silicone composition and a cured product thereof.

A siloxane unit represented by the formula: (CH ₃ ) ₂ SiO _2/2 , a siloxane unit represented by the formula: CH ₃ SiO _3/2 , a siloxane unit represented by (CH ₃ ) ₃ SiO _1/2 , and An organopolysiloxane composed of a siloxane unit represented by the formula: (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 , an organopolysiloxane having an average of one or more silicon-bonded hydrogen atoms in one molecule, and A curable silicone composition comprising a platinum-based catalyst cures to form a gel-like cured product having excellent stress relaxation properties, and is therefore used as a protective agent for electronic circuits (see Patent Document 1).
However, this cured product has a problem that its hardness changes significantly when exposed to high temperatures.

Therefore, a siloxane unit represented by the formula: (CH ₃ ) ₂ SiO _2/2 , a siloxane unit represented by the formula: CH ₃ SiO _3/2 , and a siloxane represented by (CH ₃ ) ₃ SiO _1/2 Unit, and organopolysiloxane composed of a siloxane unit represented by the formula: (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 , diorganopolysiloxane having both molecular chain ends blocked with vinyl groups, molecular chain A curable silicone composition comprising diorganopolysiloxane capped with silicon-bonded hydrogen atoms at both ends and a platinum-based catalyst (see Patent Document 2), or represented by the general formula: R ′ ₂ SiO _2/2 siloxane units of the general formula that: siloxane unit represented by R'SiO _3/2, the general formula: R _'3 siloxane units represented by SiO _1/2, and the general formula: R' ₂ R "SiO Organopolysiloxane (wherein consisting _{/ 2} siloxane units represented, R 'is a monovalent hydrocarbon group excluding alkenyl groups, provided that, R' at least one is an aryl group, R "is an alkenyl group And the aryl group content is at least 0.01 mol% based on the sum of R ′ and R ″.), An organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule, and A curable silicone composition comprising a platinum-based catalyst (see Patent Document 3) has been proposed.
However, even with these curable silicone compositions, the heat resistance of the cured product was not sufficient.

JP-A-58-007452 Japanese Patent Laid-Open No. 62-181357 JP 2000-169714 A

  An object of this invention is to provide the curable silicone composition which forms the hardened | cured material which is excellent in heat resistance, and the hardened | cured material which is excellent in heat resistance.

The curable silicone composition of the present invention is
(A) Average composition formula:
R _a SiO _{(4-a) / 2}
(In the formula, R is a halogen-substituted or unsubstituted monovalent hydrocarbon group, provided that 0.1 to 2.1 mol% of R is an alkenyl group, and a is a number of 1.9 to 2.4. .)
An organopolysiloxane represented by
(B) Organopolysiloxane having an average of two silicon-bonded hydrogen atoms in one molecule {The amount of silicon-bonded hydrogen atoms in this component is 0.1 to 0.1 moles per mole of the alkenyl group in component (A). 3.0 mol) and (C) at least a platinum-based catalyst, and the content of the component (C) is such that the platinum unit contains 10 to 100 ppm in terms of mass relative to the present composition. Yes, and the content of sodium and potassium in the composition is 3 ppm or less in terms of mass unit with respect to the composition.

The component (A) is composed of 80.0 to 96.5 mol% of a siloxane unit represented by the general formula: R ¹ ₂ SiO _2/2 , and a siloxane unit represented by the general formula: R ¹ SiO _3/2 . 0 to 10.0 mol%, represented by the general formula: R ¹ ₃ SiO _1/2 siloxane units 1.0 to 6.0 mol%, and the general formula: R ¹ ₂ R ² SiO _1/2 An organopolysiloxane comprising 0.2 to 4.0 mol% of siloxane units (wherein R ¹ is a halogen-substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R ² is It is preferably an alkenyl group.

  The cured product of the present invention is obtained by curing the above-described curable silicone composition, and it is preferable that the penetration specified by JIS K 6249 is 10 to 200.

  The curable silicone composition of the present invention is characterized by forming a cured product having excellent heat resistance. Further, the cured product of the present invention is characterized by excellent heat resistance.

First, the curable silicone composition of the present invention will be described in detail.
The organopolysiloxane of component (A) is the main component of this composition, and the average composition formula:
R _a SiO _{(4-a) / 2}
It is represented by

  In the formula, R is a halogen-substituted or unsubstituted monovalent hydrocarbon group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group; a cyclopentyl group, a cyclohexyl group, or the like; Cycloalkyl group; alkenyl group such as vinyl group, allyl group, butenyl group, pentenyl group, heptenyl group, hexenyl group; aryl group such as phenyl group, tolyl group, xylyl group; aralkyl group such as benzyl group, phenethyl group; -Halogenated alkyl groups such as chloropropyl group and 3,3,3-trifluoropropyl group are exemplified. In addition, 0.1-2.1 mol% of R is an alkenyl group. In the formula, a is a number from 1.9 to 2.4.

Such component (A) is composed of 80.0 to 96.5 mol% of siloxane units represented by the general formula: R ¹ ₂ SiO _2/2 , and siloxane units represented by the general formula: R ¹ SiO _3/2. 2.0 to 10.0 mol%, general formula: 1.0 to 6.0 mol% of a siloxane unit represented by R ¹ ₃ SiO _1/2 , and general formula: R ¹ ₂ R ² SiO _1/2 It is preferable that it is the organopolysiloxane which consists of 0.2-4.0 mol% of the siloxane unit represented.

In the formula, R ¹ is a halogen-substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group; a cyclopentyl group A cycloalkyl group such as a cyclohexyl group; an aryl group such as a phenyl group, a tolyl group and a xylyl group; an aralkyl group such as a benzyl group and a phenethyl group; a 3-chloropropyl group and a 3,3,3-trifluoropropyl group; Illustrative are halogenated alkyl groups. In the formula, R ² is an alkenyl group, and examples thereof include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a heptenyl group, and a hexenyl group.

  The viscosity of the component (A) at 25 ° C. is not limited, but is preferably in the range of 100 to 1,000,000 mPa · s because the handling workability of the composition is excellent.

  Component (B) is a cross-linking agent of the present composition and is an organopolysiloxane having an average of two silicon-bonded hydrogen atoms in one molecule. Specific examples of groups other than hydrogen atoms bonded to silicon atoms in the component (B) include alkyl groups such as methyl, ethyl, propyl, butyl and pentyl groups; cyclopentyl groups such as cyclopentyl groups and cyclohexyl groups. Alkyl group; aryl group such as phenyl group, tolyl group and xylyl group; aralkyl group such as benzyl group and fentyl group; halogenated alkyl group such as 3-chloropropyl group and 3,3,3-trifluoropropyl group, etc. Examples thereof include halogen-substituted or unsubstituted monovalent hydrocarbon groups that do not contain an aliphatic unsaturated bond. The molecular structure of component (B) is not limited, and examples thereof include linear, branched, partially branched linear, cyclic, network, and resinous, and component (B) has these molecular structures. It may be a single polymer or a mixture of polymers having these molecular structures. The viscosity of the component (B) at 25 ° C. is not limited, but is preferably in the range of 1 to 100,000 mPa · s, and particularly preferably in the range of 1 to 5,000 mPa · s.

  The content of the component (B) is an amount such that the silicon-bonded hydrogen atoms in the component are within the range of 0.1 to 3.0 mol with respect to 1 mol of the alkenyl group in the component (A). This is because the composition is sufficiently cured when the content of the component (B) is at least the lower limit of the above range, and on the other hand, the heat resistance of the resulting cured product is at most the upper limit of the above range. This is because it improves.

  Component (C) is a platinum catalyst for promoting the curing of the composition. Examples of such component (C) include chloroplatinic acid, alcohol solution of chloroplatinic acid, platinum olefin complex, platinum alkenylsiloxane complex, and platinum carbonyl complex, preferably platinum alkenylsiloxane complex. Particularly preferred is a 1,3-divinyltetramethyldisiloxane complex of platinum.

  (C) Content of a component is a quantity with which a platinum atom is in the range of 10-100 ppm in a mass unit with respect to this composition. This is because the heat resistance of the resulting cured product is improved when the content of the component (C) is at least the lower limit of the above range, and on the other hand, when the content is less than the upper limit of the above range, This is because coloring is suppressed.

  The present composition comprises at least the above components (A) to (C), and the content of sodium and potassium in the composition is in mass units with respect to the composition, both being 3 ppm or less, preferably Are all 2 ppm or less, and particularly preferably, all are 1 ppm or less. This is because the heat resistance of the resulting cured product is improved when the contents of sodium and potassium in the composition are each not more than the above upper limit. For example, most of the sodium and potassium are derived from the polymerization catalyst used in preparing the organopolysiloxane of component (A). Therefore, in this composition, as a method of setting the content of sodium and potassium below the upper limit, the component (A) that may contain sodium and potassium is washed with water or treated with an ion exchange resin or the like. Or an adsorption filtration method, or a method using organopolysiloxane prepared with a polymerization catalyst containing no sodium or potassium as the component (A). In addition, it is preferable to use the filter medium which has the adsorption effect by zeta potential for adsorption filtration. Examples of this filter medium include Zeta Plus (registered trademark) filters 01A, 05S, and 05H manufactured by Sumitomo 3M Limited.

  The present composition is composed of at least the components (A) to (C), but as other optional components, 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3,5 Alkyne alcohols such as dimethyl-1-hexyn-3-ol and 2-phenyl-3-butyn-2-ol; 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexene-1 -Enein compounds such as -in; N, N, N ', N'-tetramethylethylenediamine, N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dibutylethylenediamine, N, N, N', N Amine compounds such as' -tetraethylethylenediamine; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3, Cyclic siloxane compounds such as 5,7-tetrahexenylcyclotetrasiloxane; in addition, reaction inhibitors such as benzotriazole may be contained. Although content of this reaction inhibitor is not limited, It is preferable that it exists in the range of 1-5,000 ppm with a mass unit with respect to this composition.

  Further, in the composition, as long as the object of the present invention is not impaired, as other optional components, for example, inorganic fillers such as fumed silica, precipitated silica, fumed titanium oxide and the like, these inorganic fillers are added to organic silicon. An inorganic filler hydrophobized with a compound; in addition, a flame retardant imparting agent, a pigment, a dye, a fluorescent dye, a heat-resistant additive, a plasticizer, and an adhesion imparting agent may be contained.

  The composition can be cured rapidly by heating at room temperature or at a temperature of 40 to 200 ° C. to form a gel-like cured product.

Next, the cured product of the present invention will be described in detail.
The cured product of the present invention is obtained by curing the above curable silicone composition. Although the hardness of this hardened | cured material is not specifically limited, It is preferable that the penetration defined by JISK6249: 2003 "Test method of uncured and cured silicone rubber" is in the range of 20-200.

  The curable silicone composition of the present invention and the cured product thereof will be described in detail with reference to examples. The viscosity is a value at 25 ° C. Moreover, the curable silicone composition and the cured product were evaluated as follows.

[Sodium and potassium contents]
2 g each of the curable silicone composition was weighed and dissolved in 60 ml of toluene, 20 g of pure water was added, and then the mixture was placed on a shaker for 2 hours. The aqueous layer was collected with a plastic pipette and used as a measurement sample for ion chromatography.

  An ICS-1500 manufactured by Dionex was used as an ion chromatograph for measuring sodium ions and potassium ions. Ionpac CS-12A / CG-12A was used for the separation column, and 20 mmol / liter-methanesulfonic acid aqueous solution was used as an eluent at 1.0 ml / min. Washed away. An electric folding type CRS-300 was used as the suppressor, and an electric conductivity detector was used as the detector. The detection limit value in this measurement method was 0.1 ppm.

[Penetration]
The curable silicone composition was poured into 40 g and 50 ml glass beakers, respectively, and then cured by heating at 120 ° C. for 60 minutes. The cured product was cooled to 25 ° C., and the penetration specified by JIS K 6249 was measured. This value was defined as the penetration before the heat resistance test.

[Heat resistance test]
The cured product produced as described above was placed in a hot air circulation oven at 200 ° C., and the penetration of the cured product after 500 hours was measured in the same manner as described above. This value was defined as the penetration (1) after the heat test.
Further, the cured product after the heat resistance test was placed in a 200 ° C. hot air circulation oven and further heated for 500 hours, and the penetration of the cured product after heating for a total of 1000 hours was measured in the same manner as described above. This value was defined as the penetration (2) after the heat test.

[Reference example]
formula:
(CH ₃ ) ₂ (CH ₂ ═CH) SiO [(CH ₃ ) ₂ SiO] ₇ Si (CH ₃ ) ₂ (CH ₂ ═CH)
19.7 g of an organopolysiloxane represented by the formula:
[(CH ₃ ) ₂ SiO] _X
(In the formula, X is a number of 4 to 6.)
565.2 g of a cyclic dimethylsiloxane represented by the formula: 7.4 mol% of a siloxane unit represented by the formula: (CH ₃ ) ₃ SiO _1/2 , a siloxane represented by the formula: (CH ₃ ) ₂ SiO _2/2 A mixture of 215.3 g of a liquid organopolysiloxane consisting of 81.8 mol% of the unit and 10.8 mol% of the siloxane unit represented by the formula: CH ₃ SiO _3/2 was purged with N ₂ and 45 mass% as an equilibrium catalyst. An aqueous potassium hydroxide solution (0.1 g) was added, and an equilibrium reaction was performed at 150 ° C. for 4 hours. Thereafter, the reaction product was neutralized with CO ₂ , cooled, and then filtered once with a Zeta Plus (registered trademark) filter 01A manufactured by Sumitomo 3M Limited. The obtained organopolysiloxane (I) had a viscosity of 800 mPa · s and a vinyl group content of 0.19% by mass.

Further, this organopolysiloxane (I) is represented by the formula: (CH ₃ ) ₂ SiO _2/2 siloxane unit 94.6 mol%, the formula: CH ₃ SiO _3/2 from NMR analysis. siloxane units 2.9 mol%, the formula: (CH _{3) 3} siloxane units 2.0 mol% represented by SiO _1/2, and the formula: in _{(CH 3) 2 (CH 2} = CH) SiO 1/2 Consists of 0.5 mol% of siloxane units represented, average composition formula:
_{(CH 3) 1.991 (CH 2} = CH) 0.005 SiO 1.002
It was found that

This organopolysiloxane (I) was further filtered twice with a Zetaplus (registered trademark) filter 01A to obtain organopolysiloxane (II).
Further, organopolysiloxane (III) was obtained by further filtering this organopolysiloxane (I) with a Zetaplus (registered trademark) filter 01A five times.
Further, this organopolysiloxane (I) was further filtered twice with a zeta plus (registered trademark) filter 01A, and then filtered once with a zeta plus (registered trademark) filter 05S manufactured by Sumitomo 3M Limited. IV).

[Examples 1-14, Comparative Examples 1-8]
Using the components shown below, the compositions (parts by mass) shown in Tables 1 to 3 were mixed uniformly to prepare curable silicone compositions of Examples 1 to 14 and Comparative Examples 1 to 8. In addition, SiH / Vi in a table | surface is silicon atom bond hydrogen contained in a component (b-1) with respect to 1 mol in total of the vinyl group contained in the component (a-1)-(a-4) in a composition. The number of moles of atoms is shown.
Component (a-1): Organopolysiloxane (IV) prepared in Reference Example
Component (a-2): Organopolysiloxane (III) prepared in Reference Example
Component (a-3): Organopolysiloxane (II) prepared in Reference Example
Component (a-4): Organopolysiloxane (I) prepared in Reference Example
Component (b-1): Polydimethylsiloxane having a viscosity of 5 mPa · s and both molecular ends blocked with dimethylhydrogensiloxy groups (content of silicon-bonded hydrogen atoms = 0.12% by mass)
Component (c-1): 1,3-divinyltetramethyldisiloxane solution of 1,3-divinyltetramethyldisiloxane complex of platinum having a platinum concentration of 0.5% by mass in terms of platinum atom Component (d-1) : N, N, N ′, N′-tetramethylethylenediamine Component (d-2): 2-phenyl-3-butyn-2-ol

  Since the curable silicone composition of the present invention can form a cured product having excellent heat resistance, it is suitable as a potting agent for electronic parts such as power modules that require heat resistance.

Claims (4)

(A) Average composition formula:
R _a SiO _{(4-a) / 2}
(In the formula, R is a halogen-substituted or unsubstituted monovalent hydrocarbon group, provided that 0.1 to 2.1 mol% of R is an alkenyl group, and a is a number of 1.9 to 2.4. .)
An organopolysiloxane represented by
(B) Organopolysiloxane having an average of two silicon-bonded hydrogen atoms in one molecule {The amount of silicon-bonded hydrogen atoms in this component is 0.1 to 0.1 moles per mole of the alkenyl group in component (A). 3.0 mol) and (C) at least a platinum-based catalyst, and the content of the component (C) is such that the platinum unit contains 10 to 100 ppm in terms of mass relative to the present composition. And a curable silicone composition in which the content of sodium and potassium in the composition is 3 ppm or less in mass units with respect to the composition. The component (A) is a siloxane unit represented by a general formula: R ¹ ₂ SiO _2/2 of 80.0-96.5 mol%, a general formula: a siloxane unit represented by R ¹ SiO _3/2 -1.0 mol%, represented by the general formula: R ¹ ₃ SiO _1/2 siloxane unit 1.0-6.0 mol%, and the general formula: R ¹ ₂ R ² SiO _1/2 Organopolysiloxane composed of 0.2 to 4.0 mol% of siloxane units (wherein R ¹ is a halogen-substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R ² is alkenyl. The curable silicone composition according to claim 1, which is a group.   A cured product obtained by curing the curable silicone composition according to claim 1.   The hardened | cured material of Claim 3 whose penetration degree prescribed | regulated by JISK6249 is 10-200.