JP5962599B2 - Silicone gel composition with excellent heat resistance - Google Patents

Description

  The present invention relates to a silicone gel composition that cures to give a cured silicone gel having excellent heat resistance.

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

  In general silicone rubber, as a means for improving heat resistance, it is effective to fill a filler such as carbon and iron oxide. However, as a silicone gel material having low viscosity and requiring transparency, a filler is used. The means by filling is not an easily accepted means because disadvantages such as a decrease in transparency, sedimentation of the filler, and a decrease in workability due to an increase in viscosity occur.

  There is also a means for imparting heat resistance using a metal salt of cerium as described in JP-A-2008-291148 (Patent Document 1), but since cerium is a rare earth element, stable availability Therefore, a new technique for imparting heat resistance has been desired.

JP 2008-291148 A

  This invention is made | formed in view of the said situation, and it aims at providing the silicone gel composition which gives the silicone gel hardened | cured material excellent in the heat resistance in high temperature.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have added (a) an organopolysiloxane having a viscosity at 25 ° C. of 10 to 10,000 mPa · s to the addition reaction curable silicone gel composition. It contains a reaction product obtained by uniformly mixing siloxane and (b) an iron carboxylate represented by the following formula (I) and heat-treating at 120 to 300 ° C., and the iron content is a composition. It discovered that the silicone gel composition which is 1-100 ppm of the whole thing could become a silicone gel hardened | cured material excellent in heat resistance, and came to make this invention.

Accordingly, the present invention provides the following silicone gel composition.
[1]
(A) The following average composition formula (1)
R _a R ¹ _b SiO _{(4-ab) / 2} (1)
(Wherein R is independently an alkenyl group, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and a is a positive number of 0.0001 to 0.2. And b is a positive number from 1.7 to 2.2, where a + b is 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule: 100 parts by mass,
(B) The following average composition formula (2)
R ² _c H _d SiO _{(4-cd) / 2} (2)
(In the formula, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, c is a positive number of 0.7 to 2.2, and d is 0.001. A positive number of .about.0.5, where c + d is 0.8 to 2.5.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: 0 hydrogen atom bonded to a silicon atom per alkenyl group bonded to a silicon atom in the entire composition An amount of 0.01-3,
(C) platinum-based catalyst: effective amount,
(D) (a) having a viscosity at 25 ° C. of 10 to 700 mPa · s, having an alkyl group and / or an aryl group as an organic group bonded to a silicon atom, mainly composed of a diorganopolysiloxane unit, a molecular chain 100 parts by mass of a linear or branched organopolysiloxane whose end is blocked with a trialkylsiloxy group ,
(B) The following formula (I)
(R ³ COO) _f Fe (I)
(In the formula, R ³ is the same or different monovalent hydrocarbon group, and f is a positive number of 3 to 4.)
A reaction product obtained by uniformly mixing an iron carboxylate in an amount of 0.001 to 5 parts by mass of iron and heat-treating at 120 to 300 ° C .: 1 to 50 parts by mass A silicone gel composition excellent in heat resistance, characterized in that the iron content in component (D) is 5 to 50 ppm of the total composition.
[2]
(D) The silicone gel composition according to [1], wherein in the component (a), the organic group bonded to the silicon atom is a methyl group and / or a phenyl group.
[ 3 ]
The penetration of the cured product as defined in JIS K2220 is 10 to 200, and the loss coefficients at 25 ° C. and shear frequencies of 1 Hz and 10 Hz are 0.1 to 1.0 and 0.3 to 1.5, respectively. The silicone gel composition according to [1] or [2] , which is within the range.

  The silicone gel composition of the present invention provides a cured silicone gel that is superior in heat resistance at a higher temperature than before.

  The silicone gel composition of the present invention comprises the following components (A) to (D) as essential components. In addition, in this invention, a silicone gel hardened | cured material is a hardened | cured material with the low crosslinking density which has organopolysiloxane as a main component, Comprising: The penetration by 10-200 by JISK2220 (1/4 cone). means. This corresponds to a rubber hardness measurement according to JIS K6301 having a measured value (rubber hardness value) of 0, which is so low that it does not show an effective rubber hardness value (that is, soft). It is different from a rubber cured product (rubber-like elastic body).

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

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

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

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

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

（式中、Ｒ⁵は独立に脂肪族不飽和結合を含まない非置換又は置換の１価炭化水素基であり、Ｒ⁶は独立に脂肪族不飽和結合を含まない非置換又は置換の１価炭化水素基又はアルケニル基であり、但し少なくとも１個、好ましくは２〜５０個、より好ましくは２〜１０個のＲ⁶はアルケニル基であり、分子鎖両末端のＲ⁶のいずれかがアルケニル基である場合には、ｋは４０〜１，２００の整数であり、ｍは０〜５０の整数であり、ｎは０〜５０の整数であり、分子鎖両末端のＲ⁶のいずれもがアルケニル基でない場合には、ｋは４０〜１，２００の整数であり、ｍは１〜５０の整数であり、ｎは０〜５０の整数であり、但しｍ＋ｎは１以上である。）
で表されるオルガノポリシロキサン、即ち主鎖が基本的にジオルガノシロキサン単位の繰り返しからなり、分子鎖両末端がトリオルガノシロキシ基で封鎖された直鎖状のジオルガノポリシロキサンであることが好ましい。 The molecular structure of the organopolysiloxane of component (A) is not particularly limited, and even if it is linear, for example, RSiO _3/2 unit, R ¹ SiO _3/2 unit (R and R ¹ are the same as above) In addition, a branched structure containing a SiO ₂ unit or the like may be used, but the following general formula (1a):

(In the formula, R ⁵ independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and R ⁶ independently represents an unsubstituted or substituted monovalent group that does not contain an aliphatic unsaturated bond. A hydrocarbon group or an alkenyl group, provided that at least one, preferably 2-50, more preferably 2-10, R ⁶ is an alkenyl group, and either R ⁶ at both ends of the molecular chain is an alkenyl group. , K is an integer from 40 to 1,200, m is an integer from 0 to 50, n is an integer from 0 to 50, and both R ⁶ at both ends of the molecular chain are alkenyl. When it is not a group, k is an integer of 40 to 1,200, m is an integer of 1 to 50, n is an integer of 0 to 50, provided that m + n is 1 or more.
Is preferably a linear diorganopolysiloxane in which the main chain basically consists of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. .

In the above formula (1a), the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond other than the alkenyl group represented by R ⁵ is usually 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. belongs to. Specific examples thereof include those exemplified for R ¹ . Among them, a methyl group, a phenyl group, or a 3,3,3-trifluoropropyl group is preferable because synthesis is easy.

Moreover, the unsubstituted or substituted monovalent hydrocarbon group independently containing an aliphatic unsaturated bond represented by R ⁶ is usually one having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples thereof include those exemplified for R ¹ . Among them, a methyl group, a phenyl group, or a 3,3,3-trifluoropropyl group is preferable because synthesis is easy. The alkenyl group represented by R ⁶ usually has 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms. Specific examples thereof include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and an isobutenyl group, and a vinyl group is preferable.

In the above formula (1a), when either R ⁶ at both ends of the molecular chain is an alkenyl group, k is an integer of 40 to 1,200, m is an integer of 0 to 50, and n is It is an integer of 0-50, Preferably k is an integer of 100-1,000, m is an integer of 0-40, n is 0. Further, when neither R ⁶ at both ends of the molecular chain is an alkenyl group, k is an integer of 40 to 1,200, m is an integer of 1 to 50, and n is an integer of 0 to 50. However, m + n is 1 or more, Preferably k is an integer of 100-1,000, m is an integer of 2-40, and n is 0.

  Examples of the organopolysiloxane represented by the above formula (1a) include dimethylpolysiloxane having both ends dimethylvinylsiloxy group-blocked dimethylpolysiloxane, dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, and both ends dimethylvinylsiloxy. Blocked dimethylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy-blocked methyltrifluoropropylpolysiloxane, both ends dimethylvinylsiloxy Capped dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane at both ends Methyl vinyl siloxane copolymer, Trimethylsiloxy group-capped dimethylsiloxane / vinylmethylsiloxane copolymer, Trimethylsiloxy group-capped dimethylsiloxane / vinylmethylsiloxane / diphenylsiloxane copolymer, Trimethylsiloxy group-capped vinylmethyl Siloxane / methyltrifluoropropylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylpolysiloxane, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group / Dimethylvinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylene Polysiloxane / diphenylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped methyltrifluoropropylpolysiloxane, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane copolymer Copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both end methyldivinylsiloxy group-capped dimethylpolysiloxane, both end methyldivinylsiloxy group-capped dimethylsiloxane / methyl Vinylsiloxane copolymer, both ends methyldivinylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer, both ends methyl Rudivinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends methyldivinylsiloxy group-blocked methyltrifluoropropylpolysiloxane, both ends methyldivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane copolymer , Both ends methyldivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both ends trivinylsiloxy group-blocked dimethylpolysiloxane, both ends trivinylsiloxy-blocked dimethylsiloxane / methylvinylsiloxane copolymer Combined, trivinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, both ends trivinylsiloxy group-capped dimethylsiloxane / medium Ruvinylsiloxane / diphenylsiloxane copolymer, trivinylsiloxy group-blocked methyltrifluoropropyl polysiloxane at both ends, trivinylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, trivinylsiloxy group-blocked at both ends Examples thereof include dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer.

The viscosity of the organopolysiloxane as the component (A) is not particularly limited, but the viscosity at 25 ° C. is 50 to 100,000 mPa from the point that the handling workability of the composition, the strength of the obtained cured product, and the fluidity are good. · It is preferably s, more preferably 100 to 10,000 mPa · s. The viscosity can be measured with a rotational viscometer (hereinafter the same).
The (A) component organopolysiloxane may be used singly or in combination of two or more.

[(B) Organohydrogenpolysiloxane]
Next, (B) component of this invention reacts with the said (A) component, and acts as a crosslinking agent. The component (B) has the following average composition formula (2)
R ² _c H _d SiO _{(4-cd) / 2} (2)
(In the formula, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, c is a positive number of 0.7 to 2.2, and d is 0.001. A positive number of .about.0.5, where c + d is 0.8 to 2.5.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule. The organohydrogenpolysiloxane has preferably 3 to 500, more preferably 5 to 100, and particularly preferably 10 to 80 silicon-bonded hydrogen atoms in one molecule.

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

  C is a positive number of 0.7 to 2.2, preferably 1.0 to 2.1, d is a positive number of 0.001 to 0.5, and A positive number from 005 to 0.1 is preferred. Moreover, c + d is 0.8 to 2.5, preferably 1.0 to 2.5, and more preferably 1.5 to 2.2.

  The number of silicon atoms in one molecule of the organohydrogenpolysiloxane of component (B) (that is, the degree of polymerization) is usually 10 to 1,000, but the handling workability of the composition and the resulting cured product From the point which a characteristic (low elastic modulus, low stress) becomes favorable, Preferably it is 20-500 pieces, More preferably, it is 20-100 pieces.

Examples of the organohydrogenpolysiloxane represented by the above formula (2) include a methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, a dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane, and a dimethylhydrogen terminus at both ends. Siloxy group-blocked methylhydrogen / dimethylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydrogen / diphenylsiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydrogen / dimethylsiloxane / diphenylsiloxane copolymer Combined, trimethylsiloxy group-blocked methylhydrogenpolysiloxane on both ends, trimethylsiloxy group-blocked dimethylsiloxane and methylhydrogensiloxane on both ends Coalescence, both terminals blocked with trimethylsiloxy groups methylhydrogensiloxane-diphenylsiloxane copolymers, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers.
The (B) component organohydrogenpolysiloxane may be used singly or in combination of two or more.

  The amount of the component (B) added is such that the number of hydrogen atoms bonded to the silicon atom is 0 with respect to one alkenyl group bonded to the silicon atom of the entire composition (that is, the component (A) and the component (D) described later). 0.01-3, preferably 0.05-2, more preferably 0.2-1.5. When the number of hydrogen atoms bonded to silicon atoms from the component (B) is less than 0.01 with respect to one alkenyl group in the whole composition, a cured product cannot be obtained. Moreover, when more than three, the heat resistance of hardened | cured material falls.

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

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

[Component (D)]
The component (D) of the present invention is a reaction product of the following (a) organopolysiloxane and the following (b) iron carboxylate.

  The organopolysiloxane of component (a) may be any conventionally known organopolysiloxane, may be the alkenyl group-containing organopolysiloxane of component (A) described above, or may be an organopolysiloxane other than component (A). In the case of organopolysiloxanes other than the component (A), those containing no SiH group are preferred. This is a linear or branched substance that is substantially composed of diorganopolysiloxane units and maintains a liquid at room temperature. Specific examples of the organic group bonded to the silicon atom include alkyl groups such as methyl group, ethyl group, propyl group, and butyl group, alkenyl groups such as vinyl group and allyl group, and aryl groups such as phenyl group and tolyl group. And a cycloalkyl group such as a cyclohexyl group, or a chloromethyl group, a fluoropropyl group, a cyanomethyl group, etc. in which a part or all of the hydrogen atoms bonded to these carbon atoms are substituted with a halogen atom, a cyano group or the like. As the organopolysiloxane, one having a molecular chain terminal blocked with a trialkylsiloxy group, a hydroxyl group, a vinyl group, an alkoxy group or the like can be used. Furthermore, a mixture of these various organopolysiloxanes may be used.

  As the component (a), for example, both terminal trimethylsiloxy group-capped dimethylpolysiloxane, both terminal trimethylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer, both terminal trimethylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, Both ends trimethylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methyltrifluoropropylpolysiloxane, both ends trimethylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, Trimethylsiloxy group-blocked dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer at both ends, trimethylsiloxy group-blocked at both ends Methyl siloxane / methyl trifluoropropyl siloxane / methyl vinyl siloxane / diphenyl siloxane copolymer, both ends dimethyl vinyl siloxy group-blocked dimethyl polysiloxane, both ends dimethyl vinyl siloxy group blocked dimethyl siloxane / methyl vinyl siloxane copolymer, both ends dimethyl Vinylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both ends dimethylvinylsiloxy group-blocked methyltrifluoropropylpolysiloxane, both ends dimethyl Vinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane copolymer, dimethylvinylsiloxy group-capped dimethyl at both ends Loxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylpolysiloxane, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer, terminal Trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane / methylvinylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group Blocked methyl trifluoropropyl polysiloxane, terminal trimethylsiloxy group and dimethylvinylsiloxy group blocked dimethylsiloxane Methyltrifluoropropylsiloxane copolymer, terminal trimethylsiloxy group / dimethylvinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both terminal methyldivinylsiloxy group-capped dimethylpolysiloxane, both terminal methyldivinyl Siloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer, both ends methyldivinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, both ends methyldivinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, both Terminal methyldivinylsiloxy group-blocked methyltrifluoropropyl polysiloxane, both ends methyldivinylsiloxy group-blocked dimethylsiloxane methyltri Fluoropropylsiloxane copolymer, both ends methyldivinylsiloxy group-capped dimethylsiloxane / methyltrifluoropropylsiloxane / methylvinylsiloxane copolymer, both ends trivinylsiloxy group-capped dimethylpolysiloxane, both ends trivinylsiloxy group-capped dimethyl Siloxane / Methylvinylsiloxane Copolymer, Both Ends Trivinylsiloxy Group Blocked Dimethylsiloxane / Diphenylsiloxane Copolymer, Both Ends Trivinylsiloxy Group Blocked Dimethylsiloxane / Methylvinylsiloxane / Diphenylsiloxane Copolymer, Both Ends Trivinylsiloxy Blocked methyl trifluoropropyl polysiloxane, both ends trivinylsiloxy group blocked dimethyl siloxane / methyl trifluoropropyl siloxane copolymer, both ends trivinyl Alkoxy group-blocked dimethylsiloxane-methyl trifluoropropyl siloxane-methyl vinyl siloxane copolymer, and the like.

  Moreover, the viscosity of (a) component is 10-10,000 mPa * s in 25 degreeC, Preferably it is 50-5,000 mPa * s. When the viscosity is less than 10 mPa · s, the amount of siloxane evaporation at a high temperature tends to increase and the mass change tends to increase, so the heat resistance tends to decrease. Moreover, since it will not mix smoothly with the iron compound mentioned later when it exceeds 10,000 mPa * s, heat resistance will also fall easily.

Next, the iron carboxylate of component (b) is represented by the following formula (I).
(R ³ COO) _f Fe (I)
(In the formula, R ³ is the same or different monovalent hydrocarbon group, and f is a positive number of 3 to 4.)

In the above formula (I), R ³ is the same or different, preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably 1 to 18 carbon atoms, specifically, methyl group, ethyl group, propyl group. Group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, heptadecyl group, octadecyl group Alkyl group such as vinyl group, allyl group, propenyl group, alkenyl group such as (Z) -8-heptadecenyl group, aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, naphthalene; benzyl group, phenylethyl An aralkyl group such as a phenylpropyl group; a part or all of the hydrogen atoms of these groups may be substituted with a halo such as chlorine, bromine or fluorine. Chloromethyl group substituted with down atoms, 3,3,3-trifluoropropyl group and the like.

  Specific examples of the iron carboxylate include iron or iron-based metal compound salts such as 2-ethylhexanoic acid, naphthenic acid, oleic acid, lauric acid, and stearic acid.

  The component (a) and the component (b) are those in which the amount of iron in the component (b) is 0.001 to 5 parts by mass with respect to 100 parts by mass of the component (a). Reacts the component (b) at a ratio of 0.005 to 1 part by mass, more preferably 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the component (a). When the amount of the component (b) is too small, the heat resistance of the composition cannot be improved, and when it is too large, the electrical insulation property is lowered.

  The component (D) is obtained by uniformly mixing the components (a) and (b), followed by heat treatment, but it is difficult to obtain a uniform composition when the heating temperature is less than 120 ° C. When the temperature exceeds 300 ° C, the thermal decomposition rate of the component (a) increases, so that the heat treatment is performed at 120 to 300 ° C, preferably 150 to 250 ° C, more preferably 160 to 240 ° C. The reaction time is preferably 1 to 24 hours, particularly 2 to 16 hours.

  (D) The compounding quantity of a component is 0.01-200 mass parts with respect to 100 mass parts of (A) component, Preferably it is 0.05-50 mass parts. When the amount of the component (D) is too small, improvement in heat resistance is not observed, and when it is too large, the insulating property is lowered.

  In addition, the composition of this invention needs to be the quantity from which the iron content in (D) component will be 1-100 ppm of the whole composition, Preferably it is 3-80 ppm, More preferably, it is 5-50 ppm. When the content of iron in the component (D) is less than 1 ppm, the effect of improving the heat resistance at high temperatures is not seen, and conversely, when it exceeds 100 ppm, the insulation properties are significantly reduced.

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

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

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

[Curing composition]
The composition of the present invention can be prepared by mixing the above components (A) to (D) (including optional components when optional components are blended) according to a conventional method. At that time, the components to be mixed may be divided into two or more parts and mixed as necessary. For example, it comprises a part of component (A) and components (C) and (D). It is also possible to divide and mix the part into a part composed of the remainder of the component (A) and the part composed of the component (B).

Thereafter, the silicone gel cured product is obtained by curing the composition of the present invention under normal temperature or a temperature condition according to the application.
The silicone gel composition of the present invention is preferably used for sealing or filling electrical / electronic components.

The cured product of the silicone gel composition of the present invention preferably has a penetration of 10 to 200 by 1/4 cone as defined in JIS K2220, more preferably 20 to 100, still more preferably 30 to 80. Moreover, the loss factor at 25 ° C. and a shear frequency of 1 Hz is preferably 0.1 to 1.0, more preferably 0.15 to 0.8, still more preferably 0.2 to 0.8, and 25 ° C. The loss factor at a shear frequency of 10 Hz is preferably 0.3 to 1.5, more preferably 0.4 to 1.2, and still more preferably 0.5 to 1.0.
If the penetration is less than 10 or the loss factor is less than 0.1, the silicone gel cannot withstand the stress when it hardens, part of the electronic circuit breaks, or a crack is generated inside the silicone gel. There is a case to do. Also, if the penetration exceeds 200 or the loss factor exceeds 1.5, a silicone gel with sufficient shape retention ability cannot be obtained, and the filled and cured silicone gel may flow out of the circuit. is there.

  EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example demonstrate this invention concretely, the following Example does not restrict | limit this invention at all. In the examples, “part” represents “part by mass”, “%” represents “mass%”, and “Vi” represents “vinyl group”. Further, the penetration is a penetration with a ¼ cone defined by JIS K2220, and was measured using an automatic penetration meter RPM-101 manufactured by Koiso Co., Ltd. Furthermore, the iron content in the composition was measured by ICP emission spectrometry.

で表され、２５℃での粘度が７００ｍＰａ・ｓの両末端トリメチルシロキシ基封鎖ジメチルポリシロキサン・ジフェニルポリシロキサン共重合体１００部に対し、２−エチルヘキサン酸塩鉄（III）溶液（鉄元素含有量８％）２部を添加したところ、褐色の分散液が得られた。これに空気を少量流通させながら、２３０℃で８時間加熱したところ、濃赤褐色で透明なシリコーンオイル１（鉄含有量１，６００ｐｐｍ）が得られた。 [Synthesis Example 1]
Following formula (3)

2-ethylhexanoate iron (III) solution (containing iron element) with respect to 100 parts of a dimethylpolysiloxane / diphenylpolysiloxane copolymer blocked at both ends with a trimethylsiloxy group-blocked dimethylpolysiloxane having a viscosity at 25 ° C. of 700 mPa · s When 2 parts (amount 8%) were added, a brown dispersion was obtained. When this was heated at 230 ° C. for 8 hours with a small amount of air flowing through it, a dark reddish brown and transparent silicone oil 1 (iron content 1,600 ppm) was obtained.

[Synthesis Example 2]
When 0.1 part of 2-ethylhexanoate iron (III) solution (iron element content 8%) is added to 100 parts of trimethylsiloxy group-blocked dimethylpolysiloxane having a viscosity at 25 ° C. of 100 mPa · s. A brown dispersion was obtained. When heated at 200 ° C. for 8 hours while passing a small amount of air through this, reddish brown and transparent silicone oil 2 (iron content 80 ppm) was obtained.

[Synthesis Example 3]
In Synthesis Example 1, instead of heat treatment at 230 ° C. for 8 hours, heat treatment was performed at 80 ° C. for 16 hours. As a result, dark reddish brown and slightly turbid silicone oil 3 (iron content 1,500 ppm) was obtained.

[Synthesis Example 4]
In Synthesis Example 1, instead of heat treatment at 230 ° C. for 8 hours, when heat treatment was performed at 320 ° C. for 8 hours, a viscous gel-like material (iron content 1,500 ppm) was obtained.

で示される２５℃での粘度が１，０００ｍＰａ・ｓの両末端ジメチルビニルシロキシ基封鎖ジメチルシロキサン・ジフェニルシロキサン共重合体を６０部、下記式（５）

で示され、２５℃での粘度が７００ｍＰａ・ｓのトリメチルシロキシ基・ビニルジメチルシロキシ基封鎖ジメチルシロキサン・ジフェニルシロキサン共重合体を４０部、下記式（６）

で示され、２５℃での粘度が１００ｍＰａ・ｓの両末端トリメチルシロキシ基封鎖ジメチルシロキサン・メチルハイドロジェンシロキサン共重合体を０．５５部、下記式（７）

で示され、２５℃での粘度が１８ｍＰａ・ｓの両末端ジメチルハイドロジェンシロキシ基封鎖ジメチルポリシロキサンを５．６部（このとき、組成物中のケイ素原子結合アルケニル基１個あたりの（Ｂ）成分中のケイ素原子結合水素原子の個数（以下、Ｈ／Ｖｉという）は１．１５であった。）、及び白金原子を１％含有する塩化白金酸ビニルシロキサン錯体のジメチルポリシロキサン溶液を０．０５部、エチニルシクロヘキサノールを０．０２部、及び上記シリコーンオイル１を１部均一に混合した混合物１（鉄含有量１６ｐｐｍ）を得た。得られた混合物１を８０℃で６０分間加熱硬化したところ、針入度４０の硬化物を得た。 [Example 1]
Following formula (4)

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

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

0.55 parts of a trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity of 100 mPa · s at 25 ° C.

5.6 parts of dimethylpolysiloxane blocked with dimethylhydrogensiloxy group at both ends having a viscosity at 25 ° C. of 18 mPa · s ((B) per silicon atom-bonded alkenyl group in the composition) The number of silicon atom-bonded hydrogen atoms in the component (hereinafter referred to as H / Vi) was 1.15), and a dimethylpolysiloxane solution of a chloroplatinic acid vinylsiloxane complex containing 1% of platinum atoms was reduced to 0.00. 05 parts, 0.02 part of ethynylcyclohexanol, and 1 part of the above silicone oil 1 were uniformly mixed to obtain a mixture 1 (iron content 16 ppm). When the obtained mixture 1 was heated and cured at 80 ° C. for 60 minutes, a cured product having a penetration of 40 was obtained.

[Example 2]
In Example 1, instead of using 1 part of silicone oil 1, a mixture 2 (iron content 8 ppm) was obtained in the same manner except that 10 parts of silicone oil 2 was used. When this mixture 2 was cured by heating at 80 ° C. for 60 minutes, a cured product having a penetration of 48 was obtained.

[Comparative Example 1]
A mixture 3 (iron content 0 ppm) was obtained in the same manner as in Example 1 except that the silicone oil 1 was not used. When this mixture was cured by heating at 80 ° C. for 60 minutes, a cured product having a penetration of 41 was obtained.

[Comparative Example 2]
In Example 1, instead of using 1 part of silicone oil 1, a mixture was obtained in the same manner except that 0.15 part of 2-ethylhexanoate solution (iron element content 8%) containing iron as a main component was added. 4 (iron content 120 ppm) was obtained. When this mixture was cured, a cured product with a penetration of 38 was obtained.

[Comparative Example 3]
In Example 1, a mixture 5 (iron content 15 ppm) was obtained in the same manner except that 1 part of silicone oil 3 was used instead of 1 part of silicone oil 1. When this mixture was cured by heating at 80 ° C. for 60 minutes, a cured product having a penetration of 43 was obtained.

[test]
The following tests were conducted using the cured products obtained in Examples 1 and 2 and Comparative Examples 1 to 3. These results are shown in Table 1.

Evaluation of volume resistivity:
The volume resistivity of the cured products obtained in the above examples and comparative examples was measured by the method described in JIS K6249.

Evaluation of loss factor:
About the composition obtained by the said Example and comparative example, it heated and hardened | cured for 60 minutes at 80 degreeC with the slit shear method in RheoGelE4000 made from UBM. After the obtained cured product was cooled to 25 ° C., loss factors at 1 Hz and 10 Hz were measured.

Evaluation of heat resistance:
About the hardened | cured material obtained by the said Example and comparative example, the penetration and the presence or absence of a crack after a heat-resistant test of 215 degreeC * 1,000 hours and 250 degreeC * 200 hours were evaluated visually.

[Evaluation]
The compositions of Examples 1 and 2 satisfy the requirements of the present invention, and a cured silicone gel having good rubber properties can be obtained, and the penetration is not reduced even under long-term heat resistance of 215 ° C or 250 ° C. The stability was confirmed without any abnormal appearance such as cracks.
In contrast, the compositions of Comparative Examples 1 to 3 do not contain the component (D) of the present invention. In particular, the compositions of Comparative Examples 1 and 2 satisfy the requirements of the present invention for iron content. The heat resistance is lowered or the insulation is greatly lowered. Further, in the component (D), the composition of Comparative Example 3 whose treatment method did not satisfy the requirements of the present invention also showed a decrease in insulation and a decrease in penetration in a long-term heat test.

  The silicone gel cured product obtained by curing the silicone gel composition of the present invention maintains the low elastic modulus and low stress that are the characteristics of the silicone gel cured product even when kept for a long time in an atmosphere of 200 ° C. Therefore, long-term durability is expected to be improved in applications for protecting electronic parts such as ICs and hybrid ICs.

Claims (3)

(A) The following average composition formula (1)
R _a R ¹ _b SiO _{(4-ab) / 2} (1)
(Wherein R is independently an alkenyl group, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and a is a positive number of 0.0001 to 0.2. And b is a positive number from 1.7 to 2.2, where a + b is 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule: 100 parts by mass,
(B) The following average composition formula (2)
R ² _c H _d SiO _{(4-cd) / 2} (2)
(In the formula, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, c is a positive number of 0.7 to 2.2, and d is 0.001. A positive number of .about.0.5, where c + d is 0.8 to 2.5.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: 0 hydrogen atom bonded to a silicon atom per alkenyl group bonded to a silicon atom in the entire composition An amount of 0.01-3,
(C) platinum-based catalyst: effective amount,
(D) (a) having a viscosity at 25 ° C. of 10 to 700 mPa · s, having an alkyl group and / or an aryl group as an organic group bonded to a silicon atom, mainly composed of a diorganopolysiloxane unit, a molecular chain 100 parts by mass of a linear or branched organopolysiloxane whose end is blocked with a trialkylsiloxy group ,
(B) The following formula (I)
(R ³ COO) _f Fe (I)
(In the formula, R ³ is the same or different monovalent hydrocarbon group, and f is a positive number of 3 to 4.)
A reaction product obtained by uniformly mixing an iron carboxylate in an amount of 0.001 to 5 parts by mass of iron and heat-treating at 120 to 300 ° C .: 1 to 50 parts by mass A silicone gel composition excellent in heat resistance, characterized in that the iron content in component (D) is 5 to 50 ppm of the total composition.   (D) The silicone gel composition according to claim 1, wherein in the component (a), the organic group bonded to the silicon atom is a methyl group and / or a phenyl group. The penetration of the cured product as defined in JIS K2220 is 10 to 200, and the loss coefficients at 25 ° C. and shear frequencies of 1 Hz and 10 Hz are 0.1 to 1.0 and 0.3 to 1.5, respectively. The silicone gel composition according to claim 1 or 2 , which is within a range.