JP2004269818A - Room temperature-curable polyorganosiloxane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a room temperature-curable polyorganosiloxane composition exhibiting excellent properties after cured and having improved adhesive properties. <P>SOLUTION: This room temperature-curable polyorganosiloxane composition comprises (A) 100 pts.wt. of a polyorganosiloxane having both ends blocked with a dialkoxymonoorganosilyl group or a trialkoxysilyl group as a base polymer, (B) 1-50 pts.wt. of a siloxane oil having a lower viscosity than the component (A), (C) 1-50 pts.wt. of a silica powder having a specific surface area of at least 50 m<SP>2</SP>/g, (D) 0.5-15 pts.wt. of a specific alkoxysilane compound, and (E) 0.1-10 pts.wt. of a titanium chelate catalyst. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００１１】
（式中、Ｒ^１は１価炭化水素基、ハロゲン化炭化水素基およびシアノアルキル基から選ばれる基、Ｒ^２はアルキル基、Ｘは酸素原子または２価炭化水素基、ｎは２５℃における粘度が２０〜１，０００，０００ｃＰとなるような正数を表す。）及び／又は
【００１２】
【化５】

【００１３】
（式中、Ｒ^１は１価炭化水素基、ハロゲン化炭化水素基およびシアノアルキル基から選ばれる基、Ｒ^２はアルキル基、Ｘは酸素原子または２価炭化水素基、ｎは２５℃における粘度が２０〜１，０００，０００ｃＰとなるような正数を表す。）で示されるジオルガノポリシロキサン １００重量部、
（Ｂ） 一般式
【００１４】
【化６】

【００１５】
（式中、Ｒ^３は１価炭化水素基、ｍは２５℃における粘度が２０〜１，０００，０００ｃＰとなり、且つ成分（Ａ） の粘度未満となるような正数を表す。）
で示されるジオルガノポリシロキサン １〜５０重量部、
（Ｃ） 比表面積が５０ｍ^２／ｇ以上のシリカ粉 １〜５０重量部、
（Ｄ） 一般式
Ｒ^４ _ａＳｉ（ＯＲ^５）_４−ａ
（式中、Ｒ^４は１価炭化水素基、Ｒ^５はアルキル基又はアルコキシ置換アルキル基、ａは０、１または２である。）
で示されるアルコキシシランまたはその部分加水分解縮合物 ０．５〜１５重量部、
（Ｅ） チタンキレート触媒 ０．１〜１０重量部
からなる室温硬化性ポリオルガノシロキサン組成物である。
【００１６】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１７】
本発明で用いる（Ａ） 成分のジオルガノポリシロキサンは、本組成物のベースポリマーとなるもので、両末端がジアルコキシモノオルガノシリル基で封鎖されたポリオルガノシロキサンあるいは両末端がトリアルコキシシリル基で封鎖されたポリオルガノシロキサンであり、両者を併用してもよい。
【００１８】
（Ａ） 成分において、Ｒ^１の１価炭化水素基としては、アルキル基、シクロアルキル基、アルケニル基、アリール基、アラルキル基等が挙げられ、ハロゲン化炭化水素基としてはクロロメチル基、トリフロロメチル基等が挙げられ、シアノアルキル基としてはβ−シアノエチル基、γ−シアノプロピル基等が挙げられる。
【００１９】
また、（Ａ） 成分の粘度は、２５℃における粘度が２０〜１，０００，０００ｃＰであることが好ましい。より好ましくは１００〜１００，０００ｃＰである。
【００２０】
（Ａ） 成分は、シラノール基末端ポリオルガノシロキサンと、該ポリオルガノシロキサンのシラノール基に対して過剰モルのトリアルコキシシランあるいはテトラアルコキシシランとを触媒の存在下または不存在下で縮合させることにより得られるものである。
【００２１】
触媒としては、公知のアミン、カルボン酸、亜鉛、錫、鉄等の金属カルボン酸塩等が用いられる。触媒の不存在下で縮合反応を行う時は、反応混合物をテトラアルコキシシランの還流温度に加熱することが好ましい。
【００２２】
縮合反応におけるトリアルコキシシラン・テトラアルコキシシラン／ＳｉＯＨのモル比は、５〜１５程度が好ましい。
【００２３】
また、（Ａ） 成分は、ビニル基末端ポリオルガノシロキサンに、メチルジアルコキシシランあるいはトリアルコキシシランを付加させたり、水素基末端ポリオルガノシロキサンに、ビニルメチルジアルコキシシランあるいはビニルトリアルコキシシランを付加させたりすることでも得られる。
【００２４】
本発明に用いられる（Ｂ） 成分のジオルガノポリシロキサンは、組成物の接着性を顕著に向上させる成分である。（Ｂ） 成分のＲ^３としては、Ｒ^１で例示したものと同様の１価炭化水素基が挙げられるが、メチル基であることが特に好ましい。このようなジメシルシリコーンオイルは、その粘度が２５℃における粘度が２０〜１，０００，０００ｃＰ、好ましくは５０〜１００，０００ｃＰであることが必要であり、且つ成分（Ａ） の粘度より低いものであることが必須である。より好ましくは、（Ａ） 成分の粘度を１としたとき、（Ｂ） 成分の粘度が０．９以下となる場合である。
【００２５】
より具体的な組合せとしては、（Ａ） 成分として粘度１００〜１００，０００ｃＰ程度のものを使用し、（Ｂ） 成分として粘度５０〜５０，０００ｃＰ程度のものを使用する場合である。
【００２６】
この（Ｂ） 成分は、系中では反応せず、また基材とも反応しないため、通常は接着向上剤とはならないものであるが、本発明の（Ａ） 、（Ｃ） 、（Ｄ） 成分と組み合わせることにより、基材とのぬれ性が増し、接着性を向上させる。
【００２７】
（Ｂ） 成分の配合量は、（Ａ） 成分１００重量部に対して１〜５０重量部、より好ましくは５〜３０重量部である。１重量部未満では効果が得られず、５０重量部を超えるとブリードすることがあり、逆効果となる。
【００２８】
本発明に用いられる（Ｃ） 成分のフィラーは比表面積が５０ｍ^２／ｇ以上のシリカ粉であり、煙霧質シリカ、焼成シリカ、あるいはこれらの表面をオルガノクロロシラン類、ポリオルガノシロキサン類、オルガノシラザン類等の従来公知の処理剤で表面処理したものが挙げられる。ここで言う比表面積は、ＢＥＴ法によるものである。
【００２９】
次に、本発明で用いる（Ｄ） 成分の架橋剤は、一般式
Ｒ^４ _ａＳｉ（ＯＲ^５）_４−ａ
（式中、Ｒ^４は１価炭化水素基、Ｒ^５はアルキル基又はアルコキシ置換アルキル基、ａは０、１または２である。）
で示されるアルコキシシランまたはその部分加水分解縮合物であり、具体的にはメチルトリメトキシシラン、ビニルトリメトキシシラン、デシルトリメトキシシラン、メチルトリエトキシシラン、フェニルトリメトキシシラン、メチルトリ（エトキシメトキシ）シラン、テトラメトキシシラン、テトラエトキシシラン、ジメチルジメトキシシラン、ジメチルジエトキシシラン、ジフェニルジメトキシシラン等が例示される。
【００３０】
（Ｄ） 成分は、（Ａ） １００重量部に対し、０．５〜１５重量部程度が用いられる。
【００３１】
本発明で用いられる（Ｅ） 成分のチタンキレート触媒としては、ジイソプロポキシビス（アセト酢酸エチル）チタン、ジイソプロポキシビス（アセト酢酸メチル）チタン、ジイソプロポキシビス（アセルアセトン）チタン、ジブトキシビス（アセト酢酸エチル）チタン、ジメトキシビス（アセト酢酸エチル）チタン等の公知の各種チタンキレート化合物が挙げられる。
【００３２】
（Ｅ） 成分は、（Ａ） １００重量部に対し、０．１〜１０重量部程度が用いられる。
【００３３】
本発明の組成物は上記のような（Ａ） 〜（Ｅ） 成分からなるものであるが、本発明の（Ａ） 〜（Ｅ） 成分に、（Ｆ） 成分として１分子中にケイ素原子に直結したアルコキシ基と窒素原子とを有する有機ケイ素化合物や、１分子中にケイ素原子に直結したアルコキシ基とＣ＝Ｏ基とを有する有機ケイ素化合物を（Ａ） 成分１００重量部に対し０．０１〜５重量部添加すると、接着性がより良くなる。更に、上記の成分に加えて、石英微粉末、カーボンブラック、炭酸カルシウムなどの無機充填剤やそれらを疎水化処理したもの、チクソトロピー性付与剤、粘度調整剤、流動性調整剤、顔料、耐熱剤、難燃剤、有機溶媒、防かび剤、抗菌剤、紫外線吸収剤、耐熱向上剤、難燃化剤、接着向上剤など、各種の添加剤を加えることは本発明の目的を損なわない限り差し支えない。
【００３４】
【実施例】
以下において実施例をあげ、本発明を具体的に説明するが、本発明は以下の実施例に限定されるものではない。なお、実施例中、部とあるのはいずれも重量部を表す。
実施例１〜３
下記するポリマーＡ（ベースポリマー）、ポリマーＢ（ジメチルオイル）、ＢＥＴ法による比表面積が１１０ｍ^２／ｇでヘキサメチルジシラザンで表面処理された乾式シリカ（シリカＡ）を表１に示す割合で配合し、室温で３０分間混合し、更に１５０℃に加熱しながら４０ｍｍＨｇの減圧下で２時間混合した。この混合物にジイソプロポキシビス（アセト酢酸エチル）チタン１．５部及びメチルトリメトキシシラン４部を加え、湿気遮断下で均一になるまで混合した。
【００３５】
得られた組成物について、エポキシガラス製のテストピースで剪断試験を行い、その時の凝集破壊率を測定した。結果を表１に示す。
・ポリマーＡ
【００３６】
【化７】

【００３７】
（ｑは正数で２５℃の粘度が１２００ｃＰ）
・ポリマーＢ
（ｐは正数で２５℃の粘度が３００ｃＰ）
【００３８】
【化８】

【００３９】
実施例４
下記するポリマーＣ（ベースポリマー）、ポリマーＤ（ジメチルオイル）、ＢＥＴ法による比表面積が１３０ｍ^２／ｇの乾式シリカ（シリカＢ）を表１に示す割合で配合し、室温で１時間混合し、更に１５０℃に加熱しながら４０ｍｍＨｇの減圧下で４時間混合した。この混合物にジイソプロポキシビス（アセト酢酸エチル）チタン１．５部、メチルトリメトキシシラン３部及びトリス（３−トリメトキシシリルプロピル）イソシアヌレート０．５部を加え、湿気遮断下で均一になるまで混合した。
【００４０】
得られた組成物について、上記と同様にして凝集破壊率を測定した。結果を表１に示す。
・ポリマーＣ
（ｑは正数で２５℃の粘度が５０００ｃＰ）
【００４１】
【化９】

【００４２】
・ポリマーＤ
（ｐは正数で２５℃の粘度が５００ｃＰ）
【００４３】
【化１０】

【００４４】
実施例５
下記するポリマーＥ（ベースポリマー）、ポリマーＦ（ジメチルオイル）、ＢＥＴ法による比表面積が１３０ｍ^２／ｇの乾式シリカ（シリカＢ）を表１に示す割合で配合し、室温で１時間混合し、更に１５０℃に加熱しながら４０ｍｍＨｇの減圧下で４時間混合した。この混合物にジイソプロポキシビス（アセト酢酸エチル）チタン１．５部及びメチルトリメトキシシラン４部を加え、湿気遮断下で均一になるまで混合した。
【００４５】
得られた組成物について、上記と同様にして凝集破壊率を測定した。結果を表１に示す。
・ポリマーＥ
（ｑは正数で２５℃の粘度が１５０００ｃＰ）
【００４６】
【化１１】

【００４７】
・ポリマーＦ
（ｐは正数で２５℃の粘度が８００ｃＰ）
【００４８】
【化１２】

【００４９】
比較例１
実施例１において、ポリマーＢを配合しない以外は同様にして組成物を調製し、凝集破壊率を測定した。結果を表１に示す。
比較例２
実施例１において、ポリマーＢに代えて同一骨格のポリマーＧ（粘度２０００ｃＰ）を用いた以外は同様にして組成物を調製し、凝集破壊率を測定した。結果を表１に示す。
【００５０】
【表１】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composition which cures at room temperature into a silicone elastomer, and more particularly to a room temperature-curable organopolysiloxane composition having excellent properties after curing and improved adhesion.
[0002]
[Prior art]
Among the polyorganosiloxane compositions that cure at room temperature to form a rubber-like elastic material, those that cause a curing reaction when they come into contact with moisture in the air, have a body (base polymer) or cross-linking just before use. There is no need to weigh or mix agents or catalysts, and there is no mistake in formulation, and it has excellent adhesiveness, so it has elastic adhesives and coatings in the electric and electronic industries. It is widely used as a material and as a building sealing material. Such a composition is generally obtained by blending a silanol-terminated polydiorganosiloxane having a molecular end blocked with a hydroxyl group with a cross-linking agent having more than two hydrolyzable groups in the molecule. Depending on the type, carboxylic acids such as acetic acid, organic amines, amides, organic hydroxylamines, oxime compounds, alcohols, acetone and the like are released upon curing.
[0003]
Among them, the alcohol-free type is advantageous in that not only the alkoxysilane as a cross-linking agent can be obtained at a low cost, but also since the substance to be released is an alcohol such as methanol or ethanol, which is easily volatilized and has no odor problem. It is widely used as a coating material for electric and electronic equipment because of the advantage that it does not have the problem.
[0004]
However, the dealcoholized type is said to have poor storage stability because the curing is slow and the alcohol generated by hydrolysis of the cross-linking agent due to a small amount of water present in the system during storage cuts the base polymer. There were difficulties, and there was a demand for overcoming them. In order to solve this problem, Patent Documents 1 and 2 disclose a polyorganosiloxane in which both terminals are blocked with a dialkoxymonoorganosilyl group or a polyorganosiloxane in which both terminals are blocked with a trialkoxysilyl group. The storage stability and the curing speed (surface film formation speed) are improved by selectively combining silica with a surface treatment as a filler, alkoxysilane as a crosslinking agent and a titanium chelate catalyst as a filler.
[0005]
However, according to additional tests by the present inventors, according to the techniques of Patent Documents 1 and 2, although a composition excellent in storage stability and curing speed to some extent can be obtained, its adhesiveness is not yet satisfactory. Was.
[0006]
[Patent Document 1]
Japanese Patent Publication No. 5-72424 [Patent Document 2]
Japanese Patent Publication No. 5-88866
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a room-temperature-curable organopolysiloxane composition having excellent physical properties after curing and improved adhesiveness.
[0008]
[Means for Solving the Problems]
The present inventors have studied the techniques of Patent Documents 1 and 2 in detail in order to obtain a room-temperature-curable organopolysiloxane composition having excellent physical properties after curing and improved adhesiveness. It has been found that by adding a small amount of siloxane oil, the adhesiveness of the composition is significantly improved, and the present invention has been completed.
[0009]
That is, the present invention
(A) General formula
Embedded image

[0011]
(Wherein, R ¹ is a group selected from a monovalent hydrocarbon group, a halogenated hydrocarbon group and a cyanoalkyl group, R ² is an alkyl group, X is an oxygen atom or a divalent hydrocarbon group, and n is a viscosity at 25 ° C.) Represents a positive number such that is 20 to 1,000,000 cP.) And / or
Embedded image

[0013]
(Wherein, R ¹ is a group selected from a monovalent hydrocarbon group, a halogenated hydrocarbon group and a cyanoalkyl group, R ² is an alkyl group, X is an oxygen atom or a divalent hydrocarbon group, and n is a viscosity at 25 ° C.) Represents a positive number such that is 20 to 1,000,000 cP.) 100 parts by weight of a diorganopolysiloxane represented by the formula:
(B) General formula
Embedded image

[0015]
(In the formula, R ³ represents a monovalent hydrocarbon group, and m represents a positive number such that the viscosity at 25 ° C. becomes 20 to 1,000,000 cP and is lower than the viscosity of the component (A).)
1 to 50 parts by weight of a diorganopolysiloxane represented by
(C) 1 to 50 parts by weight of silica powder having a specific surface area of 50 m ² / g or more;
(D) formula _{^{R 4 a Si (OR 5)}} 4-a
(In the formula, R ⁴ is a monovalent hydrocarbon group, R ⁵ is an alkyl group or an alkoxy-substituted alkyl group, and a is 0, 1 or 2.)
0.5 to 15 parts by weight of an alkoxysilane or a partially hydrolyzed condensate thereof represented by
(E) Titanium chelate catalyst A room temperature curable polyorganosiloxane composition comprising 0.1 to 10 parts by weight.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
The diorganopolysiloxane of the component (A) used in the present invention is a base polymer of the present composition, and is a polyorganosiloxane in which both ends are blocked with a dialkoxymonoorganosilyl group or a trialkoxysilyl group having both ends. And may be used in combination.
[0018]
In the component (A), examples of the monovalent hydrocarbon group for R ¹ include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an aralkyl group. Examples of the halogenated hydrocarbon group include a chloromethyl group and a trifluoromethyl group. Examples include a methyl group and the like, and examples of the cyanoalkyl group include a β-cyanoethyl group and a γ-cyanopropyl group.
[0019]
The viscosity of the component (A) is preferably 20 to 1,000,000 cP at 25 ° C. More preferably, it is 100 to 100,000 cP.
[0020]
The component (A) is obtained by condensing a silanol-terminated polyorganosiloxane with an excess mole of trialkoxysilane or tetraalkoxysilane with respect to the silanol group of the polyorganosiloxane in the presence or absence of a catalyst. It is something that can be done.
[0021]
As the catalyst, known amines, carboxylic acids, metal carboxylate salts of zinc, tin, iron and the like are used. When performing a condensation reaction in the absence of a catalyst, it is preferable to heat the reaction mixture to the reflux temperature of the tetraalkoxysilane.
[0022]
The molar ratio of trialkoxysilane / tetraalkoxysilane / SiOH in the condensation reaction is preferably about 5 to 15.
[0023]
The component (A) is obtained by adding methyldialkoxysilane or trialkoxysilane to a vinyl-terminated polyorganosiloxane, or adding vinylmethyldialkoxysilane or vinyltrialkoxysilane to a hydrogen-terminated polyorganosiloxane. Or you can also get.
[0024]
The diorganopolysiloxane of the component (B) used in the present invention is a component that significantly improves the adhesiveness of the composition. Examples of R ³ of the component (B) include the same monovalent hydrocarbon groups as those exemplified for R ¹ , with a methyl group being particularly preferred. Such a dimesyl silicone oil must have a viscosity at 25 ° C. of 20 to 1,000,000 cP, preferably 50 to 100,000 cP, and have a viscosity lower than that of the component (A). Is essential. More preferably, when the viscosity of the component (A) is 1, the viscosity of the component (B) is 0.9 or less.
[0025]
As a more specific combination, a component having a viscosity of about 100 to 100,000 cP is used as the component (A) and a component having a viscosity of about 50 to 50,000 cP is used as the component (B).
[0026]
Since the component (B) does not react in the system nor reacts with the base material, it does not usually serve as an adhesion enhancer. However, the components (A), (C) and (D) of the present invention By combining with, the wettability with the base material is increased and the adhesiveness is improved.
[0027]
The compounding amount of the component (B) is 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the component (A). If the amount is less than 1 part by weight, no effect can be obtained, and if it exceeds 50 parts by weight, bleeding may occur, which has an adverse effect.
[0028]
The filler of the component (C) used in the present invention is a silica powder having a specific surface area of 50 m ² / g or more. And the like, which have been surface-treated with a conventionally known treating agent. The specific surface area mentioned here is based on the BET method.
[0029]
Next, the crosslinking agent of the component (D) used in the present invention is represented by the general formula R ⁴ _a Si (OR ⁵ ) _4-a
(In the formula, R ⁴ is a monovalent hydrocarbon group, R ⁵ is an alkyl group or an alkoxy-substituted alkyl group, and a is 0, 1 or 2.)
Or a partially hydrolyzed condensate thereof, specifically, methyltrimethoxysilane, vinyltrimethoxysilane, decyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, methyltri (ethoxymethoxy) silane , Tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and the like.
[0030]
The component (D) is used in an amount of about 0.5 to 15 parts by weight based on 100 parts by weight of the component (A).
[0031]
The titanium chelate catalyst of component (E) used in the present invention includes diisopropoxybis (ethyl acetoacetate) titanium, diisopropoxybis (methyl acetoacetate) titanium, diisopropoxybis (acelacetone) titanium, dibutoxybis ( Various known titanium chelate compounds such as (ethyl acetoacetate) titanium and dimethoxybis (ethyl acetoacetate) titanium are exemplified.
[0032]
The component (E) is used in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the component (A).
[0033]
The composition of the present invention comprises the components (A) to (E) as described above. The component (A) to (E) of the present invention and the component (F) include a silicon atom in one molecule. An organosilicon compound having a directly bonded alkoxy group and a nitrogen atom, or an organosilicon compound having an alkoxy group directly bonded to a silicon atom and a CＯO group in one molecule is added in an amount of 0.01 to 100 parts by weight of the component (A). Addition of up to 5 parts by weight improves the adhesiveness. Furthermore, in addition to the above-mentioned components, inorganic fillers such as quartz fine powder, carbon black, calcium carbonate and the like, which have been subjected to a hydrophobic treatment, a thixotropic agent, a viscosity modifier, a fluidity modifier, a pigment, a heat-resistant agent Adding various additives such as a flame retardant, an organic solvent, a fungicide, an antibacterial agent, an ultraviolet absorber, a heat resistance improver, a flame retardant, and an adhesion improver, as long as the object of the present invention is not impaired. .
[0034]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples. In the examples, “parts” means “parts by weight”.
Examples 1-3
The following polymer A (base polymer), polymer B (dimethyl oil), and dry silica (silica A) having a specific surface area of 110 m ² / g by BET method and surface-treated with hexamethyldisilazane are blended in the proportions shown in Table 1. Then, the mixture was mixed at room temperature for 30 minutes, and further mixed at a reduced pressure of 40 mmHg for 2 hours while heating to 150 ° C. 1.5 parts of diisopropoxybis (ethyl acetoacetate) titanium and 4 parts of methyltrimethoxysilane were added to the mixture, and mixed until the mixture became uniform under the exclusion of moisture.
[0035]
The obtained composition was subjected to a shear test with a test piece made of epoxy glass, and the cohesive failure rate at that time was measured. Table 1 shows the results.
・ Polymer A
[0036]
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[0037]
(Q is a positive number and the viscosity at 25 ° C is 1200 cP)
・ Polymer B
(P is a positive number and the viscosity at 25 ° C is 300 cP)
[0038]
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[0039]
Example 4
The following polymer C (base polymer), polymer D (dimethyl oil), and dry silica (silica B) having a specific surface area of 130 m ² / g according to the BET method were blended at the ratio shown in Table 1, and mixed at room temperature for 1 hour. The mixture was further mixed for 4 hours under reduced pressure of 40 mmHg while heating to 150 ° C. 1.5 parts of diisopropoxybis (ethyl acetoacetate) titanium, 3 parts of methyltrimethoxysilane and 0.5 part of tris (3-trimethoxysilylpropyl) isocyanurate are added to the mixture, and the mixture is made uniform while keeping out moisture. Until mixed.
[0040]
About the obtained composition, the cohesive failure rate was measured similarly to the above. Table 1 shows the results.
・ Polymer C
(Q is a positive number and the viscosity at 25 ° C is 5000 cP)
[0041]
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[0042]
・ Polymer D
(P is a positive number and the viscosity at 25 ° C is 500 cP)
[0043]
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[0044]
Example 5
The following polymer E (base polymer), polymer F (dimethyl oil), and dry silica (silica B) having a specific surface area of 130 m ² / g according to the BET method are blended in the ratio shown in Table 1, and mixed at room temperature for 1 hour. The mixture was further mixed for 4 hours under reduced pressure of 40 mmHg while heating to 150 ° C. 1.5 parts of diisopropoxybis (ethyl acetoacetate) titanium and 4 parts of methyltrimethoxysilane were added to the mixture, and mixed until the mixture became uniform under the exclusion of moisture.
[0045]
About the obtained composition, the cohesive failure rate was measured similarly to the above. Table 1 shows the results.
・ Polymer E
(Q is a positive number and the viscosity at 25 ° C is 15000 cP)
[0046]
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[0047]
・ Polymer F
(P is a positive number and the viscosity at 25 ° C. is 800 cP)
[0048]
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[0049]
Comparative Example 1
A composition was prepared in the same manner as in Example 1 except that the polymer B was not blended, and the cohesive failure rate was measured. Table 1 shows the results.
Comparative Example 2
A composition was prepared in the same manner as in Example 1 except that Polymer G (viscosity: 2000 cP) having the same skeleton was used instead of Polymer B, and the cohesive failure rate was measured. Table 1 shows the results.
[0050]
[Table 1]

Claims (1)

(A) General formula

(Wherein, R ¹ is a group selected from a monovalent hydrocarbon group, a halogenated hydrocarbon group and a cyanoalkyl group, R ² is an alkyl group, X is an oxygen atom or a divalent hydrocarbon group, and n is a viscosity at 25 ° C.) Represents 20 to 1,000,000 cP.) And / or

(Wherein, R ¹ is a group selected from a monovalent hydrocarbon group, a halogenated hydrocarbon group and a cyanoalkyl group, R ² is an alkyl group, X is an oxygen atom or a divalent hydrocarbon group, and n is a viscosity at 25 ° C.) Represents a positive number such that is 20 to 1,000,000 cP.) 100 parts by weight of a diorganopolysiloxane represented by the formula:
(B) General formula

(In the formula, R ³ represents a monovalent hydrocarbon group, and m represents a positive number such that the viscosity at 25 ° C. becomes 20 to 1,000,000 cP and is lower than the viscosity of the component (A).)
1 to 50 parts by weight of a diorganopolysiloxane represented by
(C) 1 to 50 parts by weight of silica powder having a specific surface area of 50 m ² / g or more;
(D) formula _{^{R 4 a Si (OR 5)}} 4-a
(In the formula, R ⁴ is a monovalent hydrocarbon group, R ⁵ is an alkyl group or an alkoxy-substituted alkyl group, and a is 0, 1 or 2.)
0.5 to 15 parts by weight of an alkoxysilane or a partially hydrolyzed condensate thereof represented by
(E) Titanium chelate catalyst A room temperature curable polyorganosiloxane composition comprising 0.1 to 10 parts by weight.