TW202204518A - Silicone gel composition, its cured body and use thereof - Google Patents

Abstract

The present invention provides a silicone gel composition, which can be formed with excellent storage stability, heat resistance at high temperature and transparency. In particular, when the member is only exposed to high temperature conditions in one direction and used for a long time, it can maintain low elastic modulus, low stress and high transparency, and is difficult to produce a cured silicone gel such as cracks and peelings. The present invention relates to a silicone gel composition and use thereof. The silicone gel composition contains: (A) a branched organopolysiloxane having an alkenyl group bonded to a silicon atom, and (B-1) a molecule Branched organohydrogenpolysiloxanes having at least 3 silicon atoms bonded to hydrogen atoms and containing at least 20 mol% or more of T units or Q units in all siloxane units, (B-2) 1 molecule A chain organohydrogenpolysiloxane having two silicon-bonded hydrogen atoms, (C) a platinum-based addition reaction catalyst, and (D) a cerium salt reaction product.

Description

Silicone gel composition, hardened product thereof, and use of the same

The invention relates to a silicone gel composition, which can be hardened to form a silicone gel cured product with excellent transparency, heat resistance, and especially crack resistance when a temperature difference occurs inside a component at high temperature. Furthermore, the present invention relates to an electronic component including an electronic component sealant including the silicone gel composition, and the silicone gel cured product.

The silicone gel composition contains organohydrogenpolysiloxanes having hydrogen atoms bonded to silicon atoms (ie, SiH groups), organopolysiloxanes having alkenyl groups such as vinyl groups bonded to silicon atoms, and A platinum-based catalyst that forms an addition reaction-hardening organopolysiloxane composition with a low crosslink density and a gel-like hardened product by the addition reaction of the hydrogen atom bonded to the silicon atom to the alkenyl group ( For example, Patent Documents 1 to 3). The cured silicone gel composition heated and hardened has excellent heat resistance, weather resistance, oil resistance, cold resistance and electrical insulation, low elastic modulus and low stress, so it is suitable for protecting automotive electronics Electronic parts such as parts and electronic parts for people's livelihood. The characteristics of silicone gel hardened products, ie, low elastic modulus and low stress, are not found in other elastomer products. In addition, in recent years, the requirements for high reliability of automotive electronic parts and electronic parts for people's livelihood have been increasing, and the heat resistance of silicone gel materials composed of cured silicone gel materials used for sealing has been increasing.

In recent years, with the popularization of the use of electronic components called power components, the operating temperature of these electronic components, especially silicon wafers, has increased from about 150°C in the past to about 175°C, and with the popularization of SiC semiconductors, the operating temperature is required. There are many cases at 200°C or higher. Therefore, a method of adding various heat resistance additives to improve the heat resistance of the silicone gel has been proposed (for example, Patent Documents 3 to 5). The silicone gel cured product made of these silicone gel compositions has heat resistance, and can maintain its low elastic modulus even when exposed to the temperature of over 200°C for a long time.

However, the power semiconductor modules used for power components generate heat during the driving period, and the heat source comes from the bottom surface of the module. According to the shape or structure of the components, it is used to protect the required silicone gel cured material, only near the bottom surface of the module Partial exposure to high heat conditions may result in large temperature differences within the same component. The temperature gradient caused by the temperature difference in such a component causes a difference in the expansion rate inside the silicone gel hardened material, resulting in internal stress, especially with the passage of time/thermal cycle, the silicone gel hardened material may develop cracks (turtles cracking, cracking), resulting in the deterioration of its protective function and other problems. The silicone gel composition described in Patent Document 3 etc. can form a cured silicone gel with excellent elastic properties even at a high temperature of over 200°C, but it is a technical problem to prevent the occurrence of cracks caused by the temperature difference in the member. , there is still room for improvement. [ Prior Art Documents ] [Patent Documents]

[Patent Document 1] Japanese Patent Laid-Open No. 48-17847 [Patent Document 2] Japanese Patent Laid-Open No. 56-143241 [Patent Document 3] International Publication Manual WO2015/034029 [Patent Document 4] International Publication Manual WO2015/111409 [Patent Document 5] Japanese Patent Laid-Open No. 2018-53015

[The problem to be solved by the invention]

The present invention has been developed in view of the above circumstances, and an object of the present invention is to provide a silicone gel composition which is excellent in storage stability and can form a cured silicone gel as described below, that is, heat resistance and transparency at high temperatures Excellent, it can maintain low elastic modulus, low stress and high transparency under high temperature for a long time When the temperature difference is large, the crack resistance is also excellent, and the gel is not easily deteriorated. Further, an object of the present invention is to provide an electronic component including an electronic component sealant composed of the silicone gel composition and a cured silicone gel obtained by curing the silicone gel composition. [Technical means to solve the problem]

The inventors of the present invention have found that, in order to solve the above-mentioned problems, branched organohydrogenpolysiloxanes having a fixed amount or more of branched siloxane units in the molecule are more effective as crosslinking agents after earnest research. That is, the inventors of the present invention found that the above problems can be solved by using a silicone gel composition as follows, and completed the present invention, and completed the present invention, that is, a molecular Branched organopolysiloxane containing on average at least 2 alkenyl groups, (B-1) Branched organohydrogenpolysiloxane containing branched siloxane units accounting for more than 20 mol% of the whole, (B-2 ) Chain organohydrogen polysiloxane with 2 silicon atoms bonded to hydrogen atoms in the molecule, (C) platinum-based addition curing catalyst and (D) reaction of a specific amount of alkali metal silanolate compound and cerium salt product. In addition, the use of the above-mentioned component (B-2) is optional, and preferably the component (B-2) is a linear organohydrogenpolysiloxane having only a silicon-bonded hydrogen atom at the end of the molecular chain. Furthermore, it was found that the above-mentioned problems can be solved by an electronic part including an electronic component sealant composed of the silicone gel composition and a cured silicone gel obtained by curing the silicone gel composition, and the completion of the this invention. [Inventive effect]

Regarding the composition of the present invention, the silicone gel composition has excellent storage stability, and can form a silicone gel cured product as described below after curing, that is, excellent in heat resistance and transparency at high temperatures over 200 degrees, It can also maintain low elastic modulus, low stress and high transparency under high temperature for a long time, and the heat source above 200°C is only set on the bottom surface of the silicone gel hardened material, which will cause a large amount of damage inside the component for a long time. When the temperature is different, it is difficult to produce cracks. Furthermore, according to this invention, the electronic component provided with the electronic component sealant which consists of the said silicone gel composition, and the said silicone gel cured product can be provided.

When the cured silicone gel composition of the present invention is used for the protection of electronic components such as ICs or hybrid ICs, transparency can be maintained at a high temperature of 200°C or higher, which is required by SiC semiconductors. , and excellent heat resistance and cold resistance, it is not only expected to improve long-term durability, but also difficult to produce cracks and other problems under the conditions of use where there is a large temperature difference inside the cured silicone gel due to heat source configuration, etc. Deteriorated over time, it can provide electronic components with high reliability and high durability.

By using the silicone gel composition and its cured product of the present invention, a method for protecting a semiconductor chip can be provided. The semiconductor chip has a high degree of freedom in circuit design including heat source configuration and internal temperature gradient of components, especially Semiconductor chips that are required to have heat resistance and cold resistance and are used in harsh environments. When the semiconductor chip obtained by the above protection method is used under conditions such as space, high latitude and extreme environment, compared with the existing protection method of silicone gel, it can also be used as a highly reliable and durable electronic device. Parts function.

Hereinafter, each component will be described in detail. In addition, the viscosity in this specification is the value measured at 25 degreeC using a Brookfield viscometer in accordance with JIS K7117-1.

[Silicone gel composition] (A) Organopolysiloxane having an alkenyl group The organopolysiloxane having an alkenyl group of component (A) is characterized in that it is one of the main ingredients (matrix polymer) of the silicone gel composition, and has a viscosity in the range of 10 to 10,000 mPa･s, and the molecular On average contain at least 2 alkenyl groups bonded to silicon atoms. More specifically, (A) component is any one of the following (A-1) components and (A-2) components or a mixture of these, and further, (A-3) alkenyl group-containing organic Polysiloxane resin. In particular, it is preferable to use the mixture of (A-1) component and (A-2) component from the viewpoint of both the cold resistance and the mechanical strength of the cured silicone gel. These (A) components are cross-linked using a cross-linking agent containing the below-mentioned (B-1) component, and a cured silicone gel that hardly causes cracks due to a large temperature difference in the member can be formed. (A-1) Branched organopolysiloxane

The branched organopolysiloxane of the component (A-1) is characterized in that it is one of the main ingredients (matrix polymer) of the silicone gel composition, and has a viscosity in the range of 10 to 10,000 mPa･s, and the molecular It contains on average at least two alkenyl groups bonded to silicon atoms, and preferably has a structure branched by a fixed amount of RSiO _3/2 (in the formula, R is a monovalent hydrocarbon group) unit.

By using this component, the silicone gel composition of the present invention can form a cured silicone gel as described below, that is, in addition to the above-mentioned crack resistance, especially cold resistance at low temperatures below -40°C Sex is also excellent. In addition, by using it together with the component (D), it is possible to form silicon oxide with excellent heat resistance and transparency at high temperatures over 200°C, and maintain low elastic modulus, low stress and high transparency even when used at high temperatures for a long time. Gel hardening.

(A-1) The branched organopolysiloxane can be represented by the following average structural formula (1): (R ₃ SiO _1/2 ) _l (R ₂ SiO _2/2 ) _m (RSiO _3/2 ) _n (1 ) In formula 1, R represents a monovalent hydrocarbon group, and l, m, and n are each a number of 1 or more, preferably, l+m+n+p is 200 or less.

(A-1) The branched organopolysiloxane preferably has a branched structure in a specific amount in order to impart good cold resistance to the cured polysiloxane of the present invention. Specifically, it is preferable that 80.0 to 99.8 mol % of all siloxane units constituting the branched organopolysiloxane molecule are R ₂ SiO _2/2 units, and 0.1 to 10.0 mol % are RSiO _3/2 units, and 0.1 to 10.0 mol % are R ₃ SiO _1/2 units. That is, the ratio of m:n:l in Formula 1 is preferably 80.0 to 99.8:0.1 to 10.0:0.1 to 10.0. m:n:l is more preferably 80.0 to 98.9:1.0 to 10.0:0.1 to 10.0, still more preferably 80.0 to 96.9:3.0 to 10.0:0.1 to 10.0. (A-1) The branched organopolysiloxane has such a branched structure, so that a cured silicone gel having excellent cold resistance especially at low temperature can be obtained. In addition, the molar ratio of R ₂ SiO _2/2 unit, RSiO _3/2 unit, and R ₃ SiO _1/2 unit in all siloxane units of branched organopolysiloxane (A-1) was determined by The value obtained by nuclear magnetic resonance (NMR) measurement.

(A-1) In branched organopolysiloxane, as the side chain or terminal group of the main chain or branched chain, that is, the monovalent hydrocarbon group (that is, the above R) bonded to the silicon atom in the polysiloxane structural unit, can be Listed are unsubstituted or substituted monovalent hydrocarbon groups or monovalent alkenyl groups that do not contain aliphatic unsaturated bonds. When the monovalent hydrocarbon group R bonded to the silicon atom is an unsubstituted or substituted monovalent hydrocarbon group that does not contain aliphatic unsaturated bonds, it is preferable that the number of carbon atoms is usually 1 to 10, preferably 1 to 6. Methyl, phenyl or 3,3,3-trifluoropropyl.

(A-1) The branched organopolysiloxane has an average of at least two alkenyl groups bonded to silicon atoms in the molecule (hereinafter also referred to as "silicon atom-bonded alkenyl groups"). Such an alkenyl group is usually an alkenyl group having 2 to 6 carbon atoms, preferably 2 to 4, more preferably 2 to 3, and particularly preferably a vinyl group.

(A-1) Of all the monovalent hydrocarbon groups R bonded to silicon atoms in the above average structural unit of the branched organopolysiloxane, preferably 0.10 to 4.00 mol % are silicon atom-bonded alkenyl groups, more preferably It is 0.25 to 4.00 mol % of a silicon atom-bonded alkenyl group, particularly preferably 0.50 to 2.00 mol % of a silicon atom-bonded alkenyl group. By (A-1) the branched organopolysiloxane containing this amount of silicon atom-bonded alkenyl groups, it is possible to obtain a softness in the range of 10 to 150 with a direct reading value of 1/4 of the consistency specified in JIS K 2220 Silicone gel hardened product. In addition, the amount of alkenyl groups in the branched organopolysiloxane (A-1) is a value quantified using a Fourier transform near-infrared spectrometer.

(A-1) The branched organopolysiloxane has a viscosity in the range of 10 to 10,000 mPa･s at 25°C. (A-1) The viscosity of the branched organopolysiloxane is preferably in the range of 10 to 5,000 mPa･s at 25°C, more preferably in the range of 10 to 1,000 mPa･s. The (A-1) branched organopolysiloxane having such a viscosity can ensure good workability and fluidity of the composition, and good strength of the obtained cured product.

(A-1) The branched organopolysiloxane can be synthesized by a known method with a desired viscosity and designed structure. For example, according to the description of the examples of Japanese Patent Laid-Open No. Sho 61-16295, in the presence of potassium silanolate, for a compound having RSiO _3/2 units, R ₂ SiO _2/2 units and R ₃ SiO _1/ The hydrolyzate of each siloxane unit of ₂ units, ViR ₂ SiOSiR ₂ Vi and cyclic polysiloxane (R ₂ SiO) _n (in each formula, R is a monovalent hydrocarbon group such as an alkyl group, and Vi is an alkene such as a vinyl group. base) for heating and equilibrium polymerization to prepare. (A-2) Linear organopolysiloxane

(A-2) One of the main ingredients (matrix polymer) of the linear organopolysiloxane-based silicone gel composition of component (A-2), has a viscosity in the range of 10 to 10,000 mPa･s, and contains on average at least 2 alkenyl groups bonded to silicon atoms.

(A-2) Linear organopolysiloxane can be represented by the following average structural formula (2): (R ₃ SO _1/2 ) _p (R ₂ SiO _2/2 ) _q (2) In formula 2, R represents the same group as the monovalent hydrocarbon group in the general formula (1) of the component (A), p and q each represent an integer of 1 or more, and preferably p+q is 500 or less.

Among all the siloxane units constituting (A-2) linear organopolysiloxane, 90.0 to 99.9 mol % are R ₂ SiO _2/2 units, and 0.1 to 10.0 mol % are R ₃ SO _1/2 unit. That is, the ratio of q:p is preferably 90.0 to 99.9:0.1 to 10.0. q:p is more preferably 95.0 to 99.5:0.5 to 5.0, particularly preferably 97.0 to 99.0:1.0 to 3.0. By (A2) the linear organopolysiloxane having such a structure, a hardened silicone gel with flexibility in the range of 10 to 150 with a direct reading value of 1/4 consistency specified in JIS K 2220 can be obtained . In addition, the molar ratio of R ₂ SiO _2/2 unit and R ₃ SiO _1/2 unit in all siloxane units of (A2) linear organopolysiloxane was measured by nuclear magnetic resonance (NMR) and the resulting value.

The organopolysiloxane represented by the above average structural formula (2) may be, for example, dimethylpolysiloxane terminated with dimethylvinylsiloxane groups at both ends, Siloxane-terminated dimethylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-vinylmethylsilicon end-capped with trimethylsiloxane groups Oxane copolymer, dimethylpolysiloxane terminated with trimethylsiloxyl-dimethylvinylsiloxane, terminated with trimethylsiloxyl-dimethylvinyl Siloxane-terminated dimethylsiloxane-methylvinylsiloxane copolymer, dimethylpolysiloxane end-capped with methyldivinylsiloxane, both ends Methyldivinylsiloxane-terminated dimethylsiloxane-methylvinylsiloxane copolymer, Dimethylpolysiloxane terminated with trivinylsiloxane at both ends, A so-called dimethylpolysiloxane such as a dimethylsiloxane-methylvinylsiloxane copolymer in which both ends are capped with trivinylsiloxane groups. These components cannot impart cold resistance to the silicone gel composition like the above-mentioned (A-1) component, but have the effect of improving mechanical strength. Therefore, dimethylpolysiloxane can be used alone as the component (A), or it can be used together with the component (A-1) or a phenyl group-containing polysiloxane described later, so as to achieve both cold resistance and mechanical strength.

On the other hand, as the component (A), it is also possible to design to use only an organopolysiloxane containing a phenyl group, that is, a dimethylsiloxane-dimethysiloxane-dimethysiloxane-dimethysiloxane-dimethysiloxane-dimethysiloxane-dimethylsiloxane-dimethysiloxane-blocked with dimethylvinylsiloxane groups at both ends. Phenylsiloxane copolymer, dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane copolymer terminated with dimethylvinylsiloxane groups at both ends, Trimethylsiloxane-terminated dimethylsiloxane-vinylmethylsiloxane-diphenylsiloxane copolymer, terminated by trimethylsiloxane-dimethylvinylsiloxane Oxyalkyl-terminated dimethylsiloxane-diphenylsiloxane copolymer, dimethylsiloxane terminated with trimethylsiloxyl-dimethylvinylsiloxane - Diphenylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-diphenylsiloxane copolymer terminated with methyldivinylsiloxane groups at both ends, two Dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane copolymer end capped with methyldivinylsiloxane, both ends capped with trivinylsiloxane dimethylsiloxane-diphenylsiloxane copolymer, dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane terminated by trivinylsiloxane groups at both ends In the so-called organopolysiloxane containing phenyl groups such as alkane copolymers, it is preferable to control the content of phenyl groups within the range described below, so that the composition of the silicone gel can be made without using the above-mentioned (A-1) component as required. The material imparts cold resistance.

When an organopolysiloxane containing a phenyl group is used as part or all of the component (A), the content of the phenyl group is preferably in the range of 1 to 10 mol % relative to the entire functional group bonded to the silicon atom, more preferably is in the range of 3 to 7 mol%. On the other hand, if the content of phenyl groups exceeds the upper limit, the phenyl groups in the cured product will increase the hardness of the silicone gel, which may impair the flexibility of the gel. Low hardness silicone gel for stress relaxation properties. Further, if the phenyl content is less than the lower limit, sufficient cold resistance may not be imparted to the silicone gel having a dimethylpolysiloxane skeleton.

In addition, the silicone gel composition of the present invention can be cured by adding the above-mentioned dimethylpolysiloxane with organopolysiloxane containing a phenyl group as the main agent as in the above-mentioned component (A-1). And the mechanical strength of the obtained silicone gel is improved. In this case, the phenyl content is also preferably within the range. In particular, when the phenyl content exceeds the above upper limit, it becomes difficult to dissolve with the dimethylpolysiloxane simultaneously used, and the uniformity of the entire composition may be impaired.

(A-2) Of all the monovalent hydrocarbon groups R bonded to silicon atoms in the structural unit of the linear organopolysiloxane, preferably 0.25 to 4.00 mol % are silicon atom-bonded alkenyl groups, more preferably 0.50 to 3.00 mol % are silicon atom-bonded alkenyl groups, more preferably 1.00 to 2.00 mol % are silicon atom-bonded alkenyl groups. By (A-2) the linear organopolysiloxane containing this amount of silicon atom-bonded alkenyl groups, the 1/4 consistency direct reading value specified in JIS K 2220 can be obtained with softness in the range of 10 to 150. Sexual silicone gel hardening. In addition, the amount of alkenyl groups in the linear organopolysiloxane (A-2) is a value quantified using a Fourier transform near-infrared spectrometer.

(A-2) The viscosity of the linear organopolysiloxane at 25°C is in the range of 1.0 to 10,000 mPa･s, preferably in the range of 1.0 to 1000 mPa･s, more preferably in the range of 5.0 to 500 mPa･s within the range. The (A-2) linear organopolysiloxane having such a viscosity can impart good workability and fluidity to the composition, and can impart good strength to the obtained cured product.

The quantitative relationship between the component (A-1) and the component (A-2) is as described above, and they can be used individually or simultaneously. From the viewpoint that the obtained silicone gel can take both cold resistance and mechanical strength into consideration, The amount of the dimethylpolysiloxane-based (A-2) component is 2 to 150 parts by mass, more preferably 2 to 100, relative to 100 parts by mass of the (A-1) component or the (A-2) component containing a phenyl group parts by mass. By adopting the ratio in the quantitative range, the cold resistance of the obtained silicone gel can be improved, the physical properties of the obtained cured silicone gel can be improved, and the stability and workability of the composition can be further improved. , and help reduce costs. (A-3) Organopolysiloxane resin

The component (A-3) is an organopolysiloxane resin, which contains on average at least 2 alkenyl groups in the molecule, and contains at least 20 mol% or more of all siloxane units selected from RSiO _3/2 (wherein , R is a siloxane unit represented by a monovalent organic group) and a siloxane unit in the siloxane unit represented by SiO _4/2 .

The alkenyl group in the component (A-3) has hydrosilylation reactivity, so it can be used in the cross-linking reaction to form a silicone gel, and is expected to improve the mechanical strength of the obtained gel. Such an alkenyl group is the same as that described above, and particularly preferably a vinyl group or a hexenyl group.

Examples of groups other than the hydrosilylation reactive group in the component (A-3) bonded to silicon atoms include alkyl groups having 1 to 20 carbon atoms, halogen-substituted alkyl groups having 1 to 20 carbon atoms, Aryl group with 6 to 20 carbon atoms, halogen-substituted aryl group with 6 to 20 carbon atoms, aralkyl group with 7 to 20 carbon atoms, alkoxy group and hydroxyl group, from the interaction with other components contained in the composition From the viewpoint of solubility, an alkyl group is preferable, and a methyl group is particularly preferable.

The addition amount of the component (A-3) is arbitrary, and can be added in the range of 0.0 to 10.0 mass % with respect to the entire composition, preferably 0.1 to 7.5 mass %, and particularly preferably 0.1 to 5.0 mass %. In addition to the above components (A-1) and (A-2), the mechanical strength of the obtained silicone gel can be improved by making the amount of the component (A-3) within this range. When the addition amount of the component (A-3) is less than 0.10 mass %, the effect of improving the mechanical strength cannot be obtained; on the contrary, when it exceeds 10.0 mass %, not only the cured silicone gel will become too hard, but also the obtained composition The viscosity at 25°C will become too high, which is not good in actual use. (B-1) Branched organohydrogenpolysiloxane

The branched organohydrogenpolysiloxane of the component (B-1) is one of the characteristic components of the present invention. It reacts with the above-mentioned component (A) and acts as a crosslinking agent of the composition, thereby effectively suppressing the obtained It is a component of the crack resistance of the cured silicone gel (especially the crack and breakage caused by the internal stress caused by the internal temperature difference of the component). This branched organohydrogenpolysiloxane has a viscosity in the range of 2 to 1000 mPa･s, has at least 3 hydrogen atoms bonded to silicon atoms in the molecule, and contains at least 20 mol% of all siloxane units Siloxane units represented by R´SiO _3/2 or SiO _4/2 above.

(B-1) The organohydrogen polysiloxane has at least three hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule. The number of silicon atom-bonded hydrogen atoms (SiH groups) in one molecule of the branched organohydrogenpolysiloxane is preferably 3 to 500, more preferably 4 to 200, and still more preferably 5 to 100 number, preferably 10 to 80. In addition (B) the amount of hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane can be measured by an infrared spectrometer.

(B-1) The branched organohydrogenpolysiloxane needs to contain at least 20 mol% of all siloxane units in its molecule, the siloxane unit represented by R´SiO _3/2 or SiO _4/2 , If the amount of these branch units is less than the lower limit, sufficient crack resistance may not be achieved.

Preferably, the component (B-1), that is, organohydrogen polysiloxane, has the following average unit formula: (R' ₃ SiO _1/2 ) _q (R' ₂ SiO _2/2 ) _r (R' SiO _3/2 ) _s (SiO _4/2 ) _t (R''O _1/2 ) _u represents a branched organohydrogen polysiloxane.

In the formula, each R' is the same or different monovalent hydrocarbon group or hydrogen atom having 1 to 10 carbon atoms without aliphatic unsaturated carbon bonds, wherein at least 3 R' in a molecule are hydrogen atoms. From an industrial viewpoint, R' other than a hydrogen atom, that is, a monovalent hydrocarbon group is preferably a methyl group or a phenyl group.

On the other hand, R'' is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, a hydrogen atom, a methyl group or an ethyl group, and as OR'', a hydroxyl group, a methoxy group or an ethoxy group is formed.

In the formula, q, r, s, t and u are numbers satisfying the following relations: 0.1≤q≤0.80, 0≤r≤0.5, 0≤s≤0.8, 0≤t≤0.6, 0≤u≤0.05, where , s+t≥0.2 and 1+m+n+p=1. Here, when the present composition is used in the molding process, the organohydrogenpolysiloxane resin as a part of the component (d2) is specifically, preferably ^MHMT resin, ^{MHMTTTH resin} , ^MHMTQ resin , ^MH MQ resin, ^MH MTT ^H Q, ^MH Q resin.

The organohydrogenpolysiloxane of the component (B-1) is preferably a MHQ resin represented by ( ^H (CH ₃ ) ₂ SiO _1/2 ) _l1 (SiO _4/2 ) _p1 . Here, preferably l1+p1=1, 0.1≤l1≤0.80 and 0.20≤p1≤0.90.

The content of the branched organopolysiloxane of the component (B-1) is preferably 0.1 to 0.8 hydrogen atoms bonded to the silicon atom, more preferably 0.2, relative to one alkenyl group of the component (A) to 0.75 pieces. By making the content of (B-1) branched organohydrogenpolysiloxane in the silicone gel composition within this range, it is possible to improve the resistance to internal stress generated by the temperature gradient in the silicone gel. cracking. With respect to one alkenyl group of the (A) component, when the number of hydrogen atoms bonded to the silicon atom derived from the (B-1) component is less than the lower limit, sufficient crack resistance cannot be obtained. Moreover, when it exceeds the said upper limit, the crosslinking density of the silicone gel obtained will become too high, and crack resistance will fall.

(B-1) The viscosity of the organohydrogenpolysiloxane at 25°C is in the range of 2.0 to 1,000 mPa･s, preferably in the range of 2.0 to 500 mPa･s, more preferably in the range of 2.0 to 150 mPa･s . The (B) organohydrogenpolysiloxane having such a viscosity ensures good workability and fluidity of the composition, and good strength of the obtained cured product. (B-2) Chain Organohydrogen Polysiloxane

The chain organohydrogenpolysiloxane of the component (B-2) reacts with the component (A) above together with the component (B-1), and functions as a crosslinking agent of the present composition. This chain-like organohydrogenpolysiloxane has a viscosity in the range of 2 to 1000 mPa･s and has 2 hydrogen atoms bonded to silicon atoms.

(B-2) The organohydrogen polysiloxane has a chain-like, preferably straight-chain structure, and contains two hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule. The positions of the SiH groups are preferably at both ends of the chain.

Such (B-2) chain organopolysiloxane is preferably represented by the following average structural formula 4: (HR ₂ SiO _1/2 ) ₂ (R ₂ SiO _2/2 ) _v (Formula 4) Formula 4 In the above, R represents the same group as a monovalent hydrocarbon group with 1 to 10 carbon atoms that does not have an aliphatic unsaturated carbon bond in the component (B-1), and from an industrial point of view, preferably a methyl group or a phenyl group . In addition, in the formula, v is a number of 1 or more, preferably 2+v is 500 or less.

(B-2) The viscosity of linear organohydrogenpolysiloxane at 25°C is in the range of 2.0 to 1,000 mPa･s, preferably in the range of 2.0 to 500 mPa･s, more preferably in the range of 2.0 to 150 mPa･s s range. The (B) organohydrogenpolysiloxane having such a viscosity ensures good workability and fluidity of the composition, and good strength of the obtained cured product.

Examples of such (B-2) chain organohydrogenpolysiloxane include (H(Me) ₂ SiO _1/2 )(Me ₂ SiO _2/2 ) _v1 (SiO _1/2 (Me) ₂ ) H) Dimethyl polysiloxane in which both ends of the indicated molecular chain are capped with dimethyl hydrosiloxane groups. Here, v1 is a number within a range of 2.0 to 500 mPa･s, more preferably within a range of 2.0 to 150 mPa･s, with a viscosity at 25°C, and Me is a methyl group.

As another (B-2) component, the following chain organohydrogenpolysiloxanes can also be mentioned. In addition, in the formula, Me and Ph represent a methyl group and a phenyl group, respectively, v2 is an integer of 1 to 100, and v3 is an integer of 1 to 50. HMe ₂ SiO(Ph ₂ SiO) _v2 SiMe ₂ H HMePhSiO(Ph ₂ SiO) _v2 SiMePhH HMePhSiO(Ph ₂ SiO) _v2 (MePhSiO) _v3 SiMePhH HMePhSiO(Ph ₂ SiO) _v2 (Me ₂ SiO) _v3 SiMePhH

With respect to one alkenyl group of (A) component, the content of (B-2) chain organohydrogenpolysiloxane in the silicone gel composition is preferably 0 to 0.9 hydrogen atoms bonded to silicon atoms The amount is more preferably 0.1 to 0.9.

The use of the component (B-2) is optional, but is mainly used to secure approximately 1.0 hydrogen atoms bonded to the silicon atom relative to one alkenyl group of the component (A) in the composition. As described above, when the component monomer (B-1) is used, if the ratio of the alkenyl group to the SiH group in the composition is close to 1.0:1.0, the crosslinking density will be too high, and the crack resistance will tend to decrease. It is used together with the component (B-2) and adjusted to the following content, so that a cured silicone gel with excellent heat resistance and physical properties can be obtained. The content is: the whole silicone gel composition and silicon atoms The total number of hydrogen atoms bonded to the silicon atom is 0.7 to 1.2 per bonded alkenyl group. When the number of hydrogen atoms bonded to the silicon atoms derived from the component (B-2) exceeds the upper limit relative to 1.0 alkenyl groups in the component (A), the heat resistance of the cured product may decrease. In addition, if the component (B-2) is not used, and when the upper limit of the usage amount is exceeded, the curability or physical properties of the obtained silicone gel cured product may be significantly deteriorated and become unsatisfactory.

From the viewpoint that the cured silicone gel obtained by curing the silicone gel composition of the present invention includes physical properties of heat resistance, cold resistance and crack resistance, the alkenyl group contained in the entire composition is 1.0 The total number of hydrogen atoms bonded to silicon atoms in the components (B-1) and (B-2) is within the range of 0.7 to 1.2, preferably within the range of 0.8 to 1.0.

(C) Platinum-based addition reaction catalyst The component (C) of the present invention is used as a catalyst for promoting the bonding between the silicon atom in the component (A) and the alkenyl group in the component (B-1) and the silicon atom in the component (B-2). Addition reactions of hydrogen atoms (ie, hydrosilylation reactions). As such component (C), a known compound can be used as a platinum-based (platinum or a compound containing platinum) compound, and a platinum-alkenylsiloxane complex is preferred from the viewpoint of a better effect of promoting the hydrosilylation reaction. compound, especially platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex. These catalysts for hydrosilylation reaction may be used individually by 1 type, and may use 2 or more types together. In addition, in order to improve the stability of the platinum-alkenylsiloxane complex, the component (C) can also be dissolved in organosiloxane oligomers such as alkenylsiloxane oligomers and dimethylsiloxane oligomers. polymer and use.

From the viewpoint of improving workability and pot life of the composition, the platinum-based addition reaction catalyst as component (C) may be dispersed in thermoplastic resins such as silicone resins, polycarbonate resins, and acrylic resins or formed into capsules. The catalyst is a thermoplastic resin particle containing a platinum-containing hydrosilylation catalyst. In addition, a part or the whole of the platinum-based addition reaction catalyst as the component (C) may be used for the hydrosilylation reaction which does not show activity unless irradiated with high-energy ray, but shows activity in the composition by irradiating high-energy ray The catalyst can also be a high-energy ray-activated catalyst represented by (methylcyclopentadienyl)trimethylplatinum (IV), bis(2,4-pentanedionate)platinum (II), etc. Photoactivated catalyst.

The blending amount of component (C) can be an effective amount, and can be appropriately increased or decreased according to the desired hardening rate. Generally, the amount of platinum group metals is usually 0.1 to 1,000 ppm, preferably 1 to 300 ppm, relative to the mass of the entire composition. in the ppm range. Even if the blending amount exceeds the upper limit of the range, there is no advantage in the hardening speed, and in consideration of the price (cost) of platinum, it is not conducive to cost reduction. (D) Reaction product of at least one cerium salt selected from (d1) alkali metal silicon alkoxide and (d2) cerium chloride or cerium carboxylate

(D) component is used for improving the heat resistance of this composition. The reaction product of the component (D) preferably contains 0.5 to 5.0 mass % of cerium (metal). In addition, (d1) alkali metal silicon alkoxide is preferably produced by a reaction obtained by subjecting (d1-2) alkali metal hydroxide to a ring-opening reaction of (d1-1) one or more cyclic organopolysiloxanes It is an alkali metal silicon alkoxide compound obtained by reacting with (d1-3) organopolysiloxane with a viscosity in the range of 10 to 10000 mPa･s at 25°C.

Although it does not specifically limit as a cyclic organopolysiloxane of (d1-1) component, For example, the cyclic organopolysiloxane which has the following general formula (3) is mentioned.

(3)[Chemical formula 1]

(3)

In formula 3, R represents the same group as the monovalent hydrocarbon group in the general formula (1) of the component (A) above, s and t are integers from 0 to 8, respectively, wherein 3≤m+n≤8.

Examples of the (d1-1) cyclic organopolysiloxane include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). ), dodecamethylcyclohexasiloxane (D6), 1,1-diethylhexamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, 1,1-diphenylhexa Methylcyclotetrasiloxane, 1,3,5,7-Tetravinyltetramethylcyclotetrasiloxane, 1,3,5,7-Tetramethylcyclotetrasiloxane, 1,3,5 ,7-tetracyclohexyltetramethylcyclotetrasiloxane, 3,3,3-trifluoropropyl)trimethylcyclotrisiloxane, 1,3,5,7-tetrakis(3-methylcyclotrisiloxane) Acryloyloxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetrakis(3-acrylooxypropyl)tetramethylcyclotetrasiloxane, 1,3,5 ,7-Tetra(3-carboxymethyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(3-vinyloxypropyl)tetramethylcyclotetrasiloxane, 1,3 ,5,7-tetrakis(p-vinylphenyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra[3-(p-vinylphenyl)propyl]tetramethyl ring Tetrasiloxane, 1,3,5,7-Tetrakis(N-acryloyl-N-methyl-3-aminopropyl)tetramethylcyclotetrasiloxane, 1,3,5,7- Tetrakis(N,N-bis(lauryl)-3-aminopropyl)tetramethylcyclotetrasiloxane, etc. Moreover, the mixture of these various organopolysiloxanes may be sufficient.

Although it does not specifically limit as an alkali metal hydroxide of a (d1-2) component, For example, sodium hydroxide, potassium hydroxide, etc. are mentioned. The amount of such a component (d1-2) is not particularly limited, but is generally 0.1 to 10.0 parts by mass relative to 100 parts by mass of the component (d1-1).

The organopolysiloxane of the component (d1-3) is a well-known organopolysiloxane whose viscosity at 25°C is in the range of 100 to 1,000,000 mPa･s, and is essentially composed of two organopolysiloxane units. The repeating (straight-chain structure) is the main body, and it remains a liquid straight-chain or branched substance at room temperature. The organic group (ie, unsubstituted or substituted monovalent hydrocarbon group) bonded to the silicon atom may be the same group as the group exemplified as R in the general formula (1) of the component (A), preferably is methyl, phenyl or 3,3,3-trifluoropropyl. Examples of the organopolysiloxane include trialkylsiloxane groups such as trimethylsiloxane groups and alkenyldialkylsiloxane groups such as vinyldimethylsiloxane groups at the ends of the molecular chain. , Divinyl alkyl siloxane such as divinyl methyl siloxane, trienyl siloxane such as trivinyl siloxane and other triorganosiloxane groups and hydroxyl, alkoxy, etc. End-capped substances.

The viscosity of the organopolysiloxane of the component (d1-3) at 25°C is in the range of 10 to 10,000 mPa･s, preferably in the range of 50 to 1,000 mPa･s. When the viscosity of the component (d1-3) is 10 mPa･s or less, there is a problem that the evaporation amount of siloxane tends to increase at high temperature, and the quality change becomes large. The amount of the component (d1-3) is not particularly limited, but is generally 0.1 to 10 parts by mass relative to 100 parts by mass of the component (d1-1).

The cerium salt of the component (d2) is cerium chloride or cerium carboxylate, and the cerium carboxylate is represented by the general formula: (R ⁴ COO) _n M ¹ . Here, R ⁴ is the same or different monovalent hydrocarbon group, M ¹ is cerium or a mixture of rare earth elements mainly composed of cerium, 2-ethylhexanoic acid, naphthenic acid, oleic acid, lauric acid, stearic acid can be mentioned. Cerium salts such as acids. In addition, from the viewpoint of ease of handling, the cerium carboxylate can be used as an organic solvent solution. Examples of the organic solvent include standard solvents, mineral spirits, benzine, petroleum-based solvents such as petroleum ether, toluene, xylene, and the like. Aromatic solvent.

The amount of cerium salt of the component (d2) is not particularly limited, but the amount of cerium is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the total amount of the above (d1) component .

With respect to 100 parts by mass of (A) component, 0.20 to 10.0 parts by mass of component (D) is added, preferably 0.2 to 5.0 parts by mass, particularly preferably 0.20 to 0.5 parts by mass, more specifically, 0.2 Parts by mass, 0.3 parts by mass, and a small amount of about 0.4 parts by mass. Furthermore, the addition amount of the component (D) is preferably an amount of 0.005 to 0.15 mass % of the cerium metal content in the (D) component, more preferably an amount of 0.01 to 0.1 mass % with respect to the entire composition. By making the amount of the (D) component within this range, the obtained silicone gel composition is advantageous in terms of heat resistance. When the addition amount of the component (D) is less than 0.20 parts by mass, the effect of improving heat resistance at high temperature cannot be exhibited. On the contrary, when it exceeds 15 parts by mass, not only the transparency of the cured silicone gel will decrease, but the composition of the silicone gel will be reduced. The cost of goods also increases, which is not conducive to reducing costs.

After mixing the components (d1) and (d2), the components (D) can be obtained by performing heat treatment at a temperature of 150° C. or higher. The heating temperature of the heat treatment is preferably 150 to 310°C, more preferably 200 to 305°C, and particularly preferably 250 to 300°C. When the heating temperature is lower than 150°C, it is difficult to obtain a uniform composition, and if it exceeds 310°C, for example, the thermal decomposition rate of the component (d1-3) may be increased.

(any other ingredients) In addition to the above-mentioned components (A) to (D), arbitrary components may be blended in the composition of the present invention within a range that does not impair the purpose of the present invention. Examples of the optional components include reaction inhibitors, inorganic fillers, organopolysiloxanes not containing silicon-bonded hydrogen atoms and silicon-bonded alkenyl groups, adhesion imparting agents, heat resistance imparting agents, flame retardants Properties imparting agent, thixotropy imparting agent, pigment, dye, etc.

The adhesion imparting agent is a component used to improve the adhesion to silicone gel substrates, etc., for example, it may contain silane coupling agents; tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, titanium Titanium compounds such as tetrakis(2-ethylhexyl) acid, titanium ethyl titanate, titanium acetylacetonate, etc.; Alkyl acetate, aluminum diisopropoxide, aluminum bis(acetoacetate), aluminum bis(ethylacetate) monoacetate, and other aluminum compounds; zirconium acetonate, butoxyethyl acetate Zirconium compounds such as zirconium acyl pyruvate, zirconium diacetyl pyruvate, zirconium acetoacetate ethyl acetate; organosilicon compounds in silanes and their partially hydrolyzed condensates disclosed in Japanese Patent Laid-Open No. 2002-322364. When the cured silicone gel containing the adhesion-imparting agent involved in the present invention is evaluated by the method described in the embodiment of this case, it can be formed to be substantially transparent, and the direct reading value of 1/4 of the consistency specified in JIS K2220 can be obtained. These adhesiveness imparting agents can be arbitrarily used within the range of the silicone gel composition within the range of 200 or less. The type and amount of the adhesion-imparting agent are preferably selected to use an adhesion-imparting agent or a range of amounts that will not reduce the transparency of the silicone gel cured product and will not inhibit curing. Silane and its partially hydrolyzed condensate or a combination thereof disclosed in Japanese Patent Laid-Open No. 2002-322364. Here, although content of the said adhesiveness imparting agent is not limited, It is preferable to exist in the range of 0.001-5.0 mass % with respect to the whole composition.

The reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the silicone gel composition, and specific examples thereof include acetylenes such as ethynylcyclohexanol, amines, carboxylates, phosphites, etc. reaction inhibitor. The addition amount of the reaction inhibitor is usually 0.001 to 5 mass % of the entire silicone gel composition.

Examples of inorganic fillers include fumed silica, crystalline silica, precipitated silica, hollow fillers, sesquioxane, fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, and aluminum hydroxide. , magnesium carbonate, calcium carbonate, zinc carbonate, layered mica, carbon black, diatomaceous earth, glass fiber and other inorganic fillers; organic alkoxysilane compounds, organic chlorosilane compounds, organic silicon nitrogen compounds, low molecular weight silicon oxides Organosilicon compounds, such as alkane compounds, are fillers after surface hydrophobization treatment is performed on these fillers. Moreover, polysiloxane rubber powder, polysiloxane resin powder, etc. may be blended. However, if low viscosity and transparency are required for the silicone gel composition, it is preferable not to mix the inorganic filler, and even if it is mixed, the amount of the composition is preferably 20 mass % or less, especially 10 mass % or less. .

[Preparation of silicone gel composition] The silicone gel composition of the present invention can be prepared by mixing the above-mentioned components (A) to (D) (if any component is to be blended, it also includes any component) according to a conventional method. At that time, the ingredients to be mixed can be divided into two or more parts and mixed according to needs, for example, it can be divided into a part consisting of (A) component, the part consisting of (C) and (D) components, and the remaining component (A) component. The part and the part constituted by the component (B) are mixed separately, and then the two parts are mixed and prepared. In particular, it is preferable to include the reaction inhibitor as an optional component in any part.

The mixing method of each component of the polysiloxane composition can be a well-known method, which is not particularly limited. Usually, a homogeneous mixture is formed by simple stirring. In addition, when a solid component such as an inorganic filler is contained as an optional component, mixing using a mixing device is more preferable. It does not specifically limit as such a mixing apparatus, One-shaft or two-shaft continuous mixers, two-roll mills, Ross mixers, Hobart mixers, dental mixers, and planetary mixers can be exemplified. A planetary mixer, a kneading mixer, a Henschel mixer, and the like.

The silicone gel composition thus obtained is excellent in storage stability, and is suitable for use as a sealant for electronic parts. In particular, by using the silicone gel composition as an encapsulant for semiconductor chips, even in harsh environments requiring excellent heat resistance, cracks will not occur against heat sources or local heating, and semiconductors can be effectively protected. wafer.

[Hardening of silicone gel composition] The cured silicone gel is silicone gel, which can be prepared by curing the silicone gel composition of the present invention at room temperature or at a temperature corresponding to the application. The temperature conditions for curing the polysiloxane composition are not particularly limited, but are usually in the range of 60°C to 150°C.

[Silicone gel cured product] Silicone gel hardened product has the following characteristics: excellent heat resistance and transparency at high temperatures over 200 degrees, low elastic modulus, low stress and high transparency can be maintained under high temperature for a long time, and only set the high temperature heat source The case of one side (for example, the bottom surface) of the cured silicone gel is represented by the case where the cured silicone gel is left exposed to high temperature in only one direction for a long time, and it is also difficult to be damaged due to the temperature difference and internal stress inside the component. Defects such as cracks are generated in the hardened silicone gel. Furthermore, it has the following advantages: when used for the protection of electronic parts such as semiconductor wafers, SiC semiconductor wafers, ICs, hybrid ICs, power components, etc., transparency can be maintained at high temperatures, and heat resistance is excellent. It is expected to improve long-term durability and low temperature. It is also difficult to deteriorate, so it can provide electronic components with high reliability and high durability even under severe conditions of use with large temperature differences. In particular, electronic parts with silicone gel cured products as sealants have high reliability and high durability even when used under severe conditions of use with large temperature differences. In addition, the semiconductor wafer includes light-emitting semiconductor elements such as LEDs.

(1/4 consistency) The hardened silicone gel is preferably 1/4 of the direct reading value of the consistency specified in JIS K2220 (the reading unit is 1/10 mm) and meets the range of 10 to 150, more preferably meets the range of 20 to 120, especially Satisfy the range of 30 to 100. The cured silicone gel with the direct reading value of 1/4 of the consistency specified in JIS K2220 in this range has the characteristics of low elastic modulus and low stress of the cured silicone gel. If the penetration is less than 10, it is difficult to exhibit the characteristics of the cured silicone gel such as low elastic modulus and low stress; if it exceeds 150, it is difficult to maintain the shape of the cured silicone gel and flow occurs. In addition, "1/4 consistency direct reading value" refers to using the 1/4 consistency meter of JIS K2220, which is the same as the penetration test of the 1/4 cone specified in JIS K2220, and the 1/4 cone is dropped from the surface of the sample. , read the value of the entry depth of the cone. (transparency)

The cured silicone gel is substantially transparent. "Substantially transparent" means that, for example, a silicone gel composition with a thickness of 10 mm is quietly injected into an aluminum cup, and then heated to prepare a cured silicone gel with a thickness of 10 mm. The silicone gel hardening is visually observed from the upper surface. It is so transparent that the bottom surface of the aluminum cup can be seen with the naked eye. The cured silicone gel has such transparency, and can be used as a sealing agent for semiconductors such as power devices. [Example]

Hereinafter, the silicone gel composition and the polysiloxane cured product of the present invention will be described in detail by way of examples. In addition, the present invention is not limited to the description of the following examples unless it exceeds the gist. In addition, the viscosity in an Example is the value at 25 degreeC.

[Synthesis of Ingredient D] Ingredient D was synthesized according to the following method. The mixture of hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane was subjected to ring-opening reaction by potassium hydroxide, and the viscosity of 20 mPa·s was added to 60 g of the prepared potassium silanolate compound, and both ends of the molecular chain were added. 120 g of dimethylpolysiloxane capped with a trimethylsiloxane group and 0.5 g of hexamethylphosphamide were reacted under nitrogen flow at 115° C. for 2 hours to prepare a potassium silanolate compound. 100 g of this potassium silanolate compound was dissolved in 150 g of isopropanol, and a mixture of 2.5 g of anhydrous cerium chloride, 50 g of ethanol, and 50 g of methanol was added dropwise while stirring the mixture to react. After filtering the reaction mixture, the filtrate was heated to 40 to 50° C. under reduced pressure, and ethanol and methanol were distilled off. Next, this was filtered again to prepare a pale yellow liquid reaction product. The cerium concentration in the reaction product was 1.4% by weight.

[Evaluation of Silicone Gel Composition and Silicone Gel Cured Product] The storage stability of the silicone gel composition of the present invention and the transparency, 1/4 consistency, heat resistance and crack resistance of the cured silicone gel were measured as follows.

(1/4 the consistency of hardened silicone gel) The silicone gel composition was quietly poured into a 50 ml glass beaker to a height of 3 cm from the bottom of the beaker, and then heated at 80°C for 1 hour to prepare a silicone gel hardened product. According to the method specified in JIS K 2220, the 1/4 consistency of the cured silicone gel was measured. In addition, as mentioned above, the 1/4 consistency of the silicone gel cured product is the direct reading value of 1/4 consistency specified in JIS K2220 (the reading unit is 1/10 mm).

(Heat resistance of cured silicone gel) The silicone gel cured product hardened according to the above method was placed in an oven at 225°C, taken out after 1000 hours, and cooled to 25°C at room temperature. Then, according to the method specified in JIS K 2220, the 1/4 consistency of the cured silicone gel was measured. In addition, as mentioned above, the 1/4 consistency of the silicone gel cured product is the direct reading value of 1/4 consistency specified in JIS K2220 (the reading unit is 1/10 mm).

(Crack resistance of cured silicone gel) The silicone gel cured product cured by the above method was placed on a hot plate heated to 225°C, and the appearance of the silicone gel was continuously observed through a beaker for 1000 hours. If the occurrence of cracks was visually confirmed within 1000 hours, the time was recorded.

[Examples 1 to 11 and Comparative Examples 1 to 5] The following components were uniformly mixed with the compositions (parts by weight) shown in Table 1 to prepare 16 kinds of silicone gel compositions. These silicone gel compositions were hardened according to the methods described in the respective evaluation methods, and the obtained cured silicone gel compositions were evaluated for their 1/4 consistency, heat resistance, and crack resistance. The results are summarized below. in Table 1 and Table 2.

In addition, SiH (B-1), SiH (B-2), and SiH/SiCH=CH ₂ in the table respectively represent 1 mol of vinyl groups contained in (A) -2) Component and the number of moles of hydrogen atoms bonded to silicon atoms in the total of components (B-1) and (B-2). In addition, about (C)component, in the table|surface, the platinum metal content in a composition is shown in ppm.

Component A-1: The viscosity obtained by the method described is 680 mPa·s, 94.5 mol% of (CH ₃ ) ₂ SiO _2/2 unit, 2.3 mol % of CH ₃ SiO _3/2 unit, (CH _{3 )} ) ₃ SiO _1/2 unit 2.3 mol % and (CH ₃ ) ₂ (CH ₂ =CH)SiO _1/2 unit 0.9 mol % branched organopolysiloxane (vinyl content=0.21 wt %)

Component A-2-1: Viscosity of 2,200 mPa·s, represented by (formula) ((CH ₃ ) ₂ (CH ₂ =CH)SiO _1/2 ) ₂ ((CH ₃ ) ₂ SiO _2/2 ) ₃₀₀ Dimethyl polysiloxane terminated with dimethyl vinyl siloxane at both ends of the linear molecular chain (vinyl content = 0.22% by weight)

Component A-2-2: Viscosity of 2,000 mPa·s, (Formula) ((CH ₃ ) ₂ (CH ₂ =CH)SiO _1/2 ) ₂ ((CH ₃ ) ₂ SiO _2/2 ) ₂₅₀ ((CH ₃ ) Dimethyl polysiloxane terminated by dimethyl vinyl siloxane groups at both ends represented by (C ₆ H ₆ )SiO _2/2 ) ₃₀ (vinyl content=0.18% by weight)

Component B-1: A branched organopolysiloxane represented by ((CH ₃ )HSiO _1/2 ) _0.67 (SiO _4/2 ) _0.33 with a viscosity of 25 mPa/s (silicon atoms bonded to hydrogen atoms) Content = 0.96% by weight) Ingredient B-2: dimethylpolysiloxane with a viscosity of 16 mPa･s linear molecular chain terminated with dimethylhydrosiloxane groups at both ends (silicon atom-bonded hydrogen Atomic content = 0.13% by weight) Component B-3: dimethylsiloxane-methylhydrosiloxane with a linear molecular chain having a viscosity of 4 mPa･s and both ends capped with trimethylsiloxane groups Copolymer (content of silicon-bonded hydrogen atoms = 0.70% by weight) Component C: platinum with a platinum content of 0.5% by weight and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane Complex (vinyl content = 2.48% by weight) Ingredient D: the reactant of alkali metal silicon alkoxide and cerium chloride prepared as described;

Component A-3: White solid at 25°C, based on the average unit formula: (Me ₂ ViSiO _{1/2) 0.05} (Me ₃ SiO _{1/2) 0.39} (SiO _4/2 ) _0.56 (HO _1/2 ) _0.02 Indicated branched organopolysiloxane (vinyl content = 1.9% by weight)

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 A-1 98.9 54.1 95.6 91.2 85.5 86.7 A-2-1 40 5 10 5 A-2-2 A-3 3 B-2 5.3 3.6 2.9 3.7 4.4 B-1 0.6 0.1 0.3 0.4 0.3 0.4 B-3 C Pt metal content [ppm] 10 10 10 10 10 10 D 0.5 0.5 0.5 0.5 0.5 0.5 SiH(b-1) 0.75 0.13 0.39 0.51 0.39 0.41 SiH(b-2) 0 0.87 0.60 0.48 0.61 0.59 SiH/Vi 0.75 1.00 0.99 0.99 1.00 1.00 1/4 consistency 60 53 51 40 57 twenty four 1/4 consistency (after 225C/1000 hours) 53 48 43 38 51 twenty two Cracking resistance 900hrs 730hrs 810hrs ＞1000hrs ＞1000hrs ＞1000hrs Example 7 Example 8 Example 9 Example 10 Example 11 A-1 A-2-1 98.86 93.88 95.45 A-2-2 95.05 89.8 A-3 0.875 3.5 B-2 5.52 4.5 4.35 6.1 B-1 0.64 0.1 0.3 0.1 0.1 B-3 C [ppm] 10 10 10 10 10 D 0.5 0.5 0.5 0.5 0.5 SiH(b-1) 0.75 0.12 0.34 0.15 0.11 SiH(b-2) 0 0.88 0.65 0.85 0.90 SiH/Vi 0.75 1.00 0.99 1.00 1.01 1/4 consistency 25 twenty one 15 58 31 1/4 consistency (after 225C/1000 hours) twenty two 20 13 37 19 Cracking resistance ＞1000hrs ＞1000hrs ＞1000hrs 780hrs ＞1000hrs

[Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 A-1 53.45 98.43 98.7 82.51 76.1 A-2-1 40 6.5 9.75 A-2-2 A-3 3.5 5.25 B-2 6.05 6.85 8.4 B-1 0.1 0.8 B-3 0.97 0.14 C Pt metal content [ppm] 10 10 10 10 10 D 0.5 0.5 0.5 0.5 0.5 SiH(b-1) 0 0.13 1.00 0 0 SiH(b-2) 1.00 0 0 0.90 1.00 SiH/Vi 1.00 1.01 1.00 1.01 1.00 1/4 consistency 72 twenty three 31 78 75 1/4 consistency (after 225C/1000 hours) 51 18 19 58 55 Cracking resistance 250hrs 170hrs 350hrs 350hrs 280hrs [Summarize]

In Examples 1 to 11 of the present invention, the obtained silicone gel has good heat resistance and crack resistance when heated from one direction at 225°C for a long time, and the consistency changes by 1/4 after 1000 hours at high temperature Not much.

On the other hand, in the experimental examples of the compositions (Comparative Examples 1 to 5) in which the amount and type of the organohydrosiloxane used as the crosslinking agent were not within the scope of the present invention, the heat resistance and crack resistance were insufficient, especially It was confirmed that cracks were generated within 400 hours when heated from one direction at 225°C for a long time.

without

without

Claims (15)

A silicone gel composition comprising: (A) an organopolysiloxane having a viscosity in the range of 10 to 10,000 mPa･s at 25°C and having an average of at least 2 alkenyl groups bonded to silicon atoms in the molecule : 100 parts by mass; (B-1) The viscosity at 25°C is in the range of 2 to 1,000 mPa･s, the molecule has more than 3 silicon atoms bonded to hydrogen atoms, and contains at least 20 moles of all siloxane units % or more R'SiO _3/2 (wherein R' is a monovalent hydrocarbon group) or branched organohydrogen polysiloxane of siloxane unit represented by SiO _4/2 : bonded to silicon atoms in the entire composition The amount of hydrogen atoms bonded to silicon atoms is 0.1 to 0.8 per alkenyl group; (B-2) The viscosity at 25°C is in the range of 2 to 1,000 mPa･s, and there are 2 hydrogen atoms in one molecule. Chain organohydrogen polysiloxane with silicon-bonded hydrogen atoms: in every alkenyl group bonded to a silicon atom in the entire composition, the amount of hydrogen atoms bonded to a silicon atom is 0 to 0.9; (C ) platinum-based addition reaction catalyst: the amount of platinum-based metal in the range of 0.01 to 1000 ppm relative to the entire composition; and (D) selected from (d1) alkali metal silicon alkoxide and (d2) cerium chloride and at least one or more cerium salt reaction products in cerium carboxylates: 0.2 to 10.0 parts by mass; In every alkenyl group bonded to a silicon atom in the whole composition, (B-1) component and (B-2) ) component in the amount of 0.7 to 1.2 hydrogen atoms bonded to silicon atoms in total. The silicone gel composition of claim 1, wherein (A) component is the following (A-1) branched organopolysiloxanes having at least two alkenyl groups bonded to silicon atoms in the molecule, and (A-2) Linear organopolysiloxane having a viscosity in the range of 1.0 to 10,000 mPa･s at 25°C and having at least 2 alkenyl groups bonded to silicon atoms in the molecule any one or a mixture of, and, (B-2) The component is a linear organohydrogenpolysiloxane with only silicon-bonded hydrogen atoms at both ends of the molecular chain and a viscosity in the range of 2 to 200 mPa･s at 25°C. The silicone gel composition of claim 1 or 2, wherein, in the total siloxane units of the branched organopolysiloxane molecules constituting the component (A-1), 80.0 to 99.8 mol% is R ₂ SiO _2/2 units, 0.1 to 10.0 mol % are RSiO _3/2 units, and 0.1 to 10.0 mol % are R ₃ SiO _1/2 units (the R all represent monovalent hydrocarbon groups bonded to silicon atoms). The silicone gel composition of claim 3, wherein in all the monovalent hydrocarbon groups bonded to the silicon atom in the component (A-1), 0.25 to 4.00 mol% are alkenyl groups bonded to the silicon atom. . The silicone gel composition according to any one of claims 1 to 4, wherein the component (D) contains 0.5 to 5.0 mass % of cerium metal. The silicone gel composition according to any one of claims 1 to 5, wherein the component (d1) is composed of (d1-2) alkali metal hydroxide to (d1-1) one or more cyclic organic compounds The reaction product obtained by the ring-opening reaction of polysiloxane is further reacted with (d1-3) an organopolysiloxane with a viscosity of 10 to 10,000 mPa･s at 25°C, an alkali metal silicon alkoxide compound obtained. The silicone gel composition according to any one of claims 1 to 6, wherein the blending amount of the component (D) is relative to the entire composition, and the content of cerium metal in the component (D) is 0.005 to 0.15 mass % amount. A hardened silicone gel, which is obtained by hardening the silicone gel composition of any one of claims 1 to 7. The silicone gel cured product of claim 8 is substantially transparent, and the direct reading value of 1/4 consistency specified in JIS K2220 is in the range of 10 to 150. An electronic part sealant comprising the silicone gel composition of any one of claims 1 to 7. The sealant for electronic parts according to claim 10, which is a substantially transparent sealant for power components. An electronic component provided with the cured silicone gel of claim 8 or 9. The electronic component of claim 12 is a power component. An optical semiconductor device having a structure in which an optical semiconductor element is sealed by the cured silicone gel of claim 8 or 9. A general lighting fixture, optical member or optoelectronic member, comprising the cured silicone gel of claim 8 or 9.