JP4054942B2 - Silicone adhesive composition - Google Patents

Description

（式中、Ｒ¹は非置換又は置換一価炭化水素基を表し、ｍは２００〜２０００の整数である。）
で表される両末端ヒドロキシル基含有ジオルガノポリシロキサン：１００重量部、
（Ｂ）ＳｉＯ₂単位とＲ² ₃ＳｉＯ_0.5単位（Ｒ²は炭素数３以下の一価炭化水素基を表す）とのモル比が１：０．５〜１：１．５であるオルガノポリシロキサン樹脂：１５０〜３００重量部、
（Ｃ）一分子中に少なくとも２個のケイ素原子結合水素原子を含有するオルガノハイドロジェンポリシロキサン：（Ａ），（Ｂ）成分の合計量１００重量部に対し０．１〜２重量部、
（Ｄ）金属が錫、鉛、鉄及び亜鉛から選ばれる有機カルボン酸金属塩：（Ａ），（Ｂ）成分の合計量１００重量部に対し０．５〜５重量部、
（Ｅ）ホウ素含有ポリシロキサン：（Ａ），（Ｂ）成分の合計量１００重量部に対し０．０５〜５重量部、
（Ｆ）Ｃ ₆Ｈ₅ＳｉＯ_1.5単位と［（ＣＨ₃）₂ＳｉＯ］_n単位（ｎは５〜１００の整数）からなる分岐型オルガノポリシロキサン：（Ａ），（Ｂ）成分の合計量１００重量部に対し０．１〜１０重量部
を必須成分とすることを特徴とするシリコーン接着剤組成物を提供する。
【０００８】
以下、本発明につき更に詳しく説明する。
本発明のシリコーン粘着剤組成物において、上記（Ａ）成分は本発明の接着剤としての皮膜形成成分であり、（Ｃ）成分の架橋剤と（Ｄ）成分の触媒作用により、（Ｂ）成分と脱水縮合して硬化する。該（Ａ）成分は分子鎖の両末端に脱水反応に必要なヒドロキシル基を有することが必要である。
【０００９】
この（Ａ）成分は、下記一般式（１）で表されるものである。
【化３】

【００１０】
ここで、Ｒ^１は非置換又は置換一価炭化水素基であり、炭素数１〜１２、特に１〜８のものが好ましく、具体的には、メチル基、エチル基、プロピル基、ブチル基、ヘキシル基、オクチル基等のアルキル基、ビニル基、アリル基、プロペニル基等のアルケニル基、フェニル基、トリル基等のアリール基、ベンジル基、フェニルエチル基等のアラルキル基や、これらの基の水素原子の一部又は全部をハロゲン原子やシアノ基等で置換した基などが挙げられるが、工業的観点からはメチル基が好ましい。ｍは２００〜２０００の整数であり、このオルガノポリシロキサンの粘度は２５℃において１０〜１００Ｐａ・ｓが好ましく、特に３０〜７０Ｐａ・ｓのものが好ましい。粘度が１０Ｐａ・ｓ未満では接着力及び耐熱性が低くなり、１００Ｐａ・ｓを超えると作業性が悪くなり、接着力も低くなる。
【００１１】
（Ｂ）成分のオルガノポリシロキサン樹脂は本発明の接着剤組成物の主成分であり、実質的にＲ^２ _３ＳｉＯ_０．５単位（Ｍ単位）とＳｉＯ_２単位（Ｑ単位）からなる粘着付与樹脂であり、これは一般的にＭＱレジンと呼ばれている。Ｒ^２は炭素数３以下の一価の炭化水素基を表し、特にメチル基、エチル基、プロピル基等のアルキル基、アリル基等のアルケニル基から選択される有機基であり、全Ｒ^２基の少なくとも９５モル％はメチル基であることが好ましい。また、Ｍ単位とＱ単位のモル比が０．５：１〜１．５：１の範囲内にあるものであるが、特に本発明の接着性組成物の場合には、０．６：１〜１．２：１が好ましい。Ｍ単位が０．５未満になると接着力が低下し、１．５を超えると耐熱性が低下する。該ＭＱレジンの合成法は公知である。
【００１２】
（Ｂ）成分の本発明における配合量は、（Ａ）成分１００重量部に対して１５０〜３００重量部である。１５０重量部未満では十分な接着力が得られず、３００重量部を超えるとタックが殆どなくなるため、基材と被着体の接着が困難となる。
【００１３】
（Ｃ）成分のオルガノハイドロジェンポリシロキサンは、（Ａ）成分と（Ｂ）成分のオルガノポリシロキサンを架橋させるものであり、一分子中にケイ素原子に結合している水素原子を少なくとも２個含有するもの中から適宜選択することができ、直鎖状、分岐状、環状等のいずれであっても良い。
【００１４】
このオルガノハイドロジェンポリシロキサンとしては、下記平均組成式
Ｒ^３ _ａＨ_ｂＳｉＯ_{（４−ａ−ｂ）／２}
（式中、Ｒ^３は上記Ｒ^１と同様の一価炭化水素基、ａは０．７〜２．１、ｂは０．００１〜１．０で、ａ＋ｂ＝０．８〜３．０を満足する正数である。）
で示され、好ましくはケイ素原子数が２〜５００個程度のものを使用することができる。
【００１５】
具体的には、１，１，３，３−テトラメチルジシロキサン、メチルハイドロジェンシクロポリシロキサン、メチルハイドロジェンシロキサン・ジメチルシロキサン環状共重合体、両末端トリメチルシロキシ基封鎖メチルハイドロジェンポリシロキサン、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、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、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シロキサン・メチルハイドロジェンシロキサン共重合体、両末端トリメチルシロキシ基封鎖メチルハイドロジェンシロキサン・ジフェニルシロキサン共重合体、両末端トリメチルシロキシ基封鎖メチルハイドロジェンシロキサン・ジフェニルシロキサン・ジメチルシロキサン共重合体、両末端ジメチルハイドロジェンシロキシ基封鎖メチルハイドロジェンシロキサン・ジメチルシロキサン・ジフェニルシロキサン共重合体、（ＣＨ_３）_２ＨＳｉＯ_１／２単位と（ＣＨ_３）_３ＳｉＯ_１／２単位とＳｉＯ_４／２単位とからなる共重合体、（ＣＨ_３）_２ＨＳｉＯ_１／２単位とＳｉＯ_４／２単位とからなる共重合体、（ＣＨ_３）_２ＨＳｉＯ_１／２単位とＳｉＯ_４／２単位と（Ｃ_６Ｈ_５）_３ＳｉＯ_１／２単位とからなる共重合体などが挙げられる。
【００１６】
該（Ｃ）成分の配合量は、（Ａ）成分と（Ｂ）成分の共重合体１００重量部に対し０．１〜２重量部である。０．１重量部未満では十分な架橋が得られず、２重量部を超えると、過剰であり、いずれも接着力及び耐熱性が低下する。
【００１７】
（Ｄ）成分の有機カルボン酸金属塩は、（Ａ）〜（Ｃ）成分のための硬化触媒であり、例えばジブチル錫ジアセテート、ジブチル錫ジオクトエート、ジブチル錫ジラウレート、錫オクトエート、錫ナフテート、鉛オクトエート、鉄オクトエート、亜鉛オクトエート等を挙げることができるが、これらの中でも特にジブチル錫ジアセテート、ジブチル錫ジオクトエートの錫塩が好ましい。
【００１８】
該（Ｄ）成分の配合量は、（Ａ）成分と（Ｂ）成分の共重合体１００重量部に対し０．５〜５重量部である。０．５重量部未満では硬化性が遅く、５重量部を超えるとポットライフが短くなり、作業性が悪くなる。
【００１９】
（Ｅ）成分のホウ素含有シロキサンは、（Ａ）〜（Ｄ）成分からなる接着剤組成物に、より強力な接着性を付与するための接着助剤である。従来、基材と基材との接着性を改良する目的で、予め基材にプライマー処理を施すことは公知であるが、作業性に劣る欠点がある。本発明は（Ｅ）成分を本接着剤組成物中に添加することにより、かかるプライマー処理は不要となるため作業性が向上する。
【００２０】
（Ｅ）成分のホウ素含有シロキサンはＢ−Ｏ−Ｓｉ結合を有する有機ケイ素化合物であれば特に限定されないが、単量体は加水分解性が高いため、オリゴマー及びポリマーが好ましい。該ホウ素含有シロキサンとしては、例えば下記平均組成式（２）
Ｒ^４ _ｃ（Ｒ^５Ｏ）_ｄＳｉＯ_{（４−ｃ−ｄ）／２} （２）
（式中、Ｒ^４は一価炭化水素基、Ｒ^５は水素原子又は一価炭化水素基を表し、ｃ，ｄは、０＜ｃ＜４、０＜ｄ＜４、かつ０＜ｃ＋ｄ＜４を満足する正数である。）
で示されるオルガノポリシロキサンとホウ酸との反応物を挙げることができる。
【００２１】
ここで、Ｒ^４としては、炭素数１〜１２、特に１〜８の一価炭化水素基が好ましく、具体的にはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基等のアルキル基、フェニル基、トリル基等のアリール基、ビニル基、アリル基等のアルケニル基が例示され、またＲ^５としては、水素原子又は炭素数１〜１２、特に１〜８の一価炭化水素基、具体的にはメチル基、エチル基、プロピル基、イソプロピル基等のアルキル基、ビニル基、アリル基、イソプロペニル基等のアルケニル基が例示されるが、一分子中のＲ^４，Ｒ^５の各々は全て同一である必要はない。またホウ酸の水酸基とＲ^５Ｏ基は特に合わせる必要はないが、等モルあるいはＲ^５Ｏ基過剰の方が本化合物の安定性の面で好ましい。
【００２２】
なお、上記オルガノポリシロキサンとホウ酸との反応物は、該オルガノポリシロキサンとホウ酸とを加熱下に反応させることにより得ることができ、一例を挙げれば、Ｂ（ＯＨ）_３１６重量部、ＣＨ_３Ｓｉ（ＯＣ_２Ｈ_５）_３４６重量部、（ＣＨ_３）_２Ｓｉ（ＯＣ_２Ｈ_５）_２３８重量部とを７０℃で６時間の条件下で反応させることにより得ることができる。
【００２３】
（Ｅ）成分の配合量は、（Ａ）成分と（Ｂ）成分の共重合体１００重量部に対し、０．０５〜５重量部である。０．０５重量部未満では接着性向上の効果に乏しく、５重量部を超えると、耐熱性が低下する。
【００２４】
（Ｆ）成分の分岐型オルガノポリシロキサンは、（Ａ）〜（Ｅ）成分からなる本接着剤組成物の耐熱性向上を目的に使用されるものであり、Ｃ ₆Ｈ₅ＳｉＯ_1.5単位と［（ＣＨ₃）₂ＳｉＯ］_n単位とからなるメチルフェニルポリシロキサンである。具体的には、Ｃ₆Ｈ₅ＳｉＸ₃とＸ−［（ＣＨ₃）₂ＳｉＯ］_n-1（ＣＨ₃）₂ＳｉＸ（ｎは５〜１００の整数、Ｘはアルコキシ基、塩素等の加水分解性基）とを加水分解し、続いて重合してなるオルガノポリシロキサンであり、任意成分としてＣ₆Ｈ₅ＣＨ₃ＳｉＸ₂，（ＣＨ₃）₂ＳｉＸ₂，ＣＨ₃ＳｉＸ₃，（Ｃ₆Ｈ₅）₂ＳｉＸ₂等の加水分解性シランも添加しても良い。さらに具体的には、Ｃ₆Ｈ₅ＣＨ₃ＳｉＣｌ₂，Ｃ₆Ｈ₅ＳｉＣｌ₃及びＣｌ−［（ＣＨ₃）₂ＳｉＯ］₂₀（ＣＨ₃）₂ＳｉＣｌの共加水分解物をアルカリ重合することにより得られる。
【００２５】
（Ｆ）成分の配合量は、（Ａ）成分と（Ｂ）成分の共重合体１００重量部に対し、０．１〜１０重量部である。０．１重量部未満では十分な耐熱性が得られず、１０重量部を超えると十分な接着力が得られない。
【００２６】
一般に、本発明の接着剤組成物を得るには、まず（Ａ）成分と（Ｂ）成分及び（Ｆ）成分をアルカリ縮合触媒の存在下、２５℃〜１２０℃で１時間〜１０時間反応させる。この際トルエン又はキシレンのような希釈溶剤を用いても良い。ついで得られた反応物に（Ｃ），（Ｅ）成分を混合する。
【００２７】
本発明の組成物は、無溶剤下あるいは溶剤で希釈して使用される。塗工性改良や膜厚制御の目的で、トルエン、キシレン、エチルベンゼン、ヘキサン、ヘプタン、オクタン、メチルエチルケトン、酢酸エチル等の溶剤で希釈しても良い。
【００２８】
このようにして得られた本発明のシリコーン接着剤組成物は、（Ｄ）成分を添加してから、種々の基材に塗布し硬化させて接着層を形成させれば、優れた接着特性が得られる。この基材としては、例えば、鉄、銅、アルミニウム等の金属やポリエステル、ポリイミド、ポリアミド、ポリイミドアミド等のプラスチック、ガラスクロス等の布、和紙、合成紙等の紙、一般に接着し難いシリコーンゴムなどが使用できる。
【００２９】
（Ａ）〜（Ｆ）成分を含有する本組成物は、基材に塗布してから２５℃〜５０℃で５分〜３０分風乾した後、貼付してから室温で１時間放置するだけで良好な接着力が得られ、さらに放置することでより強固な接着力を得られる。
【００３０】
【実施例】
以下、実施例及び比較例を示し、本発明を具体的に説明するが、本発明は下記の実施例に制限されるものではない。なお、下記の例において部は重量部を示す。また、実施例中に示した接着力は次の方法により測定した。
【００３１】
（接着力の測定方法）
基材にシリコーン接着剤組成物を所定厚さ（０．８ｇ／ｍ^２）に塗工後、３０分風乾してから、各種被着体に２ｋｇ重のゴムローラーを用いて貼付し、試験片とした。該試験片を２５℃・５５％ＲＨで５時間静置後及び２００℃中で２４時間加熱後、引き剥がし接着力はオートグラフ〔（株）島津製作所製〕を用い、０．３ｍ／ｍｉｎ．のスピードで１８０°Ｐｅｅｌで引き剥がした時の接着力を測定し、ｇｆ／１０ｍｍの単位で表示した。また、剪断接着力はストログラフ〔東洋精機（株）製〕を用い、５０ｍｍ／ｍｉｎ．のスピードで垂直方向に引き剥がしたときの接着力をｇｆ／ｃｍ^２の単位で表示した。その結果を引き剥がし接着力は表１に、剪断接着力は表２に示した。
【００３２】
［実施例１］
両末端ヒドロキシル基封鎖ジメチルポリシロキサン（粘度５０Ｐａ・ｓ）１００部、（ＣＨ_３）_３ＳｉＯ_０．５単位とＳｉＯ_２単位とからなり、そのモル比が０．８：１．０であるメチルポリシロキサン２００部、及びトルエン１３０部の混合物を１１０℃で５時間加熱攪拌した後、冷却して接着剤ベース溶液（固形分７０％）を得た。この溶液１００部に対し、平均組成式（ＣＨ_３）_３ＳｉＯ［（ＣＨ_３）ＨＳｉＯ］_３８Ｓｉ（ＣＨ_３）_３で示されるメチルハイドロジェンポリシロキサン２部、（ＣＨ_３ＳｉＯ_１．５）_０．１［（ＣＨ_３）_２ＳｉＯ］_０．８（ＢＯ_１．５）_０．１で示されるホウ素含有ポリシロキサン１部、平均組成式（Ｃ_６Ｈ_５ＣＨ_３ＳｉＯ）_０．０２（Ｃ_６Ｈ_５ＳｉＯ_１．５）_０．４６［（ＣＨ_３）_２ＳｉＯ］_０．５２で示される分岐型メチルフェニルポリシロキサン２部及びＣＡＴ−ＰＳ−１（ジブチル錫ジアセテート、信越化学製：製品名）３部を混合してシリコーン接着剤組成物−１を得た。
【００３３】
［実施例２］
実施例１の両末端ヒドロキシル基封鎖ジメチルポリシロキサンの粘度を１０Ｐａ・ｓに替えた以外は、実施例１と同様にしてシリコーン接着剤組成物−２を得た。
【００３４】
［実施例３］
実施例１の（ＣＨ_３）_３ＳｉＯ_０．５単位とＳｉＯ_２単位とのモル比が０．８：１．０であるメチルポリシロキサンの配合量を１６０部に替えた以外は、実施例１と同様にしてシリコーン接着剤組成物−３を得た。
【００３５】
［比較例１］
実施例１のホウ素含有ポリシロキサンを全く配合せずに、その他は実施例１と同様にしてシリコーン接着剤組成物−４を得た。
【００３６】
［比較例２］
実施例１の分岐型メチルフェニルポリシロキサンを全く配合せずに、その他は実施例１と同様にしてシリコーン接着剤組成物−５を得た。
【００３７】
［比較例３］
実施例１の両末端ヒドロキシル基封鎖ジメチルポリシロキサンの粘度を５００Ｐａ・ｓに替えた以外は、実施例１と同様にしてシリコーン接着剤組成物−６を得た。
【００３８】
［比較例４］
実施例１の（ＣＨ_３）_３ＳｉＯ_０．５単位とＳｉＯ_２単位とからなり、そのモル比が０．８：１．０であるメチルポリシロキサンの配合量を１３０部に替えた以外は、実施例１と同様にしてシリコーン接着剤組成物−７を得た。
【００３９】
［比較例５］
一般に知られている両末端ヒドロキシル基封鎖ジメチルポリシロキサン（粘度１万Ｐａ・ｓ）１００部とＭ：Ｑ＝０．８５：１．０のＭＱレジン１３０部からなるシリコーン１００部に過酸化ベンゾイル２部を混合して得た粘着剤−１を基材に所定厚に塗工し、１５０℃で１５分硬化させてから、実施例と同様に被着体に貼り合わせ、所定時間静置後接着力を測定した。
【００４０】
【表１】

【００４１】
【表２】

＊１：ＫＥ−９５１Ｕ（信越化学工業（株）製；厚み２ｍｍ）
＊２：ＪＩＳ ＳＨ−７４８−Ｌ（（株）テストピース製；厚み０．３ｍｍ）
＊３：２５℃・５５％ＲＨ×１０時間静置後
＊４：２００℃×２０時間後
＊５：ＪＩＳ ＳＨ−７４１−Ａ（（株）テストピース製；厚み０．３ｍｍ）
＊６：ＪＩＳ ＳＧ−７４３−Ａ（（株）テストピース製；厚み０．３ｍｍ）
＊７：ＫＥ−４６０３Ｕ（信越化学工業（株）製；厚み２ｍｍ）
【００４２】
【発明の効果】
本発明のシリコーン接着剤組成物によれば、シリコーンゴム、金属、ガラス等に対する接着力が改良され、従来のシリコーン粘着剤より大幅に接着力が向上し、かつプライマー処理することなく室温で短時間に硬化することができるため、作業性にも優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a silicone adhesive composition, and more particularly to a silicone adhesive composition having excellent adhesion to silicone rubber / silicone rubber, metal / metal and silicone rubber / metal.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, a copolymer (so-called MQ) comprising a highly polymerized dimethylpolysiloxane having a molecular chain end blocked with a hydroxyl group, a SiO ₂ unit and (CH ₃ ) ₃ SiO _0.5 unit on a film-like support. A silicone pressure-sensitive adhesive obtained by condensing a resin) is known. However, this type of pressure-sensitive adhesive is suitable for applications that require removability, such as pressure-sensitive adhesive tapes, but is not suitable for fields that require strong adhesive strength.
[0003]
In order to apply a pressure-sensitive adhesive as an adhesive, heating at 200 ° C./2 hours or more is required using a metal salt such as lead as a catalyst, and even with that, satisfactory adhesive strength cannot be obtained. It was far from practical use for rubber.
[0004]
Liquid silicone rubber is used in fields that require strong adhesive strength, but has a long curing time and has problems of odor and corrosivity.
[0005]
Accordingly, an object of the present invention is to provide a silicone adhesive composition that adheres well to silicone rubber, metal, and the like.
[0006]
Means for Solving the Problem and Embodiment of the Invention
As a result of diligent studies to achieve the above object, the present inventor has found that MQ resin, hydroxyl group-containing diorganopolysiloxane, organohydrogenpolysiloxane, branched organopolysiloxane, boron-containing polysiloxane, and organic carboxylic acid When a composition comprising a metal salt is used under certain conditions, it can be cured at room temperature and has good adhesion in a short time, and is particularly excellent in adhesion of silicone rubber / silicone rubber, metal / metal, and silicone rubber / metal. It has been found that the adhesiveness is imparted, and the present invention has been made.
[0007]
That is, the present invention
(A) The following general formula (1)
[Chemical 2]

(In the formula, R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group, and m is an integer of 200 to 2000.)
Diorganopolysiloxane having hydroxyl groups at both ends represented by: 100 parts by weight,
(B) Organopoly having a molar ratio of SiO ₂ units to R ² ₃ SiO _0.5 units (R ² represents a monovalent hydrocarbon group having 3 or less carbon atoms) of 1: 0.5 to 1: 1.5 Siloxane resin: 150 to 300 parts by weight,
(C) Organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in one molecule: 0.1 to 2 parts by weight relative to 100 parts by weight of the total amount of components (A) and (B),
(D) Organic carboxylic acid metal salt wherein the metal is selected from tin, lead, iron and zinc: 0.5 to 5 parts by weight relative to 100 parts by weight of the total amount of components (A) and (B),
(E) Boron-containing polysiloxane: 0.05 to 5 parts by weight with respect to 100 parts by weight of the total amount of components (A) and (B),
(F ) Branched organopolysiloxane composed of C ₆ H ₅ SiO _1.5 units and [(CH ₃ ) ₂ SiO] _n units (n is an integer of 5 to 100): total amount of components (A) and (B) 100 A silicone adhesive composition characterized by comprising 0.1 to 10 parts by weight as an essential component with respect to parts by weight is provided.
[0008]
Hereinafter, the present invention will be described in more detail.
In the silicone pressure-sensitive adhesive composition of the present invention, the component (A) is a film-forming component as the adhesive of the present invention, and the component (B) is produced by the crosslinking action of the component (C) and the catalytic action of the component (D). And dehydrated and cured. The component (A) needs to have hydroxyl groups necessary for dehydration reaction at both ends of the molecular chain.
[0009]
This component (A) is represented by the following general formula (1).
[Chemical 3]

[0010]
Here, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group, preferably having 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, Alkyl groups such as hexyl group and octyl group, alkenyl groups such as vinyl group, allyl group and propenyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and phenylethyl group, and hydrogens of these groups A group in which part or all of the atoms are substituted with a halogen atom, a cyano group, or the like can be given, and a methyl group is preferable from an industrial viewpoint. m is an integer of 200 to 2000, and the viscosity of the organopolysiloxane is preferably 10 to 100 Pa · s, particularly preferably 30 to 70 Pa · s at 25 ° C. When the viscosity is less than 10 Pa · s, the adhesive force and heat resistance are lowered, and when it exceeds 100 Pa · s, the workability is deteriorated and the adhesive force is also lowered.
[0011]
The organopolysiloxane resin as component (B) is the main component of the adhesive composition of the present invention, and is substantially a tackifier composed of R ² ₃ SiO _0.5 units (M units) and SiO ₂ units (Q units). It is a resin and is generally called MQ resin. R ² represents a monovalent hydrocarbon group having 3 or less carbon atoms, particularly an organic group selected from an alkyl group such as a methyl group, an ethyl group and a propyl group, and an alkenyl group such as an allyl group, and all R ² groups It is preferable that at least 95 mol% of these are methyl groups. Further, the molar ratio of M unit to Q unit is in the range of 0.5: 1 to 1.5: 1, but particularly in the case of the adhesive composition of the present invention, 0.6: 1. ~ 1.2: 1 is preferred. When the M unit is less than 0.5, the adhesive strength is lowered, and when it exceeds 1.5, the heat resistance is lowered. A method for synthesizing the MQ resin is known.
[0012]
(B) The compounding quantity in this invention of a component is 150-300 weight part with respect to 100 weight part of (A) component. If the amount is less than 150 parts by weight, sufficient adhesive strength cannot be obtained. If the amount exceeds 300 parts by weight, tack is almost eliminated, and adhesion between the substrate and the adherend becomes difficult.
[0013]
Component (C), organohydrogenpolysiloxane, crosslinks component (A) and component (B), and contains at least two hydrogen atoms bonded to silicon atoms in one molecule. It can be appropriately selected from those to be performed, and may be any of linear, branched, cyclic and the like.
[0014]
As this organohydrogenpolysiloxane, the following average composition formula R ³ _a H _b SiO _{(4-ab) / 2}
(In the formula, R ³ is the same monovalent hydrocarbon group as R ¹ above, a is 0.7 to 2.1, b is 0.001 to 1.0, and a + b = 0.8 to 3.0. Satisfactory positive number.)
And preferably having about 2 to 500 silicon atoms.
[0015]
Specifically, 1,1,3,3-tetramethyldisiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, both Terminal trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethyl Siloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / dimethyl Copolymer, both ends endcapped with dimethyl hydrogen siloxy group methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane _{copolymers, (CH} 3) 2 _{HSiO 1/2} units and _{(CH 3) 3 SiO 1/2} units and SiO _A copolymer comprising _4/2 units, a copolymer comprising (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units. And a copolymer comprising (C ₆ H ₅ ) ₃ SiO _1/2 units.
[0016]
The amount of the component (C) is 0.1 to 2 parts by weight with respect to 100 parts by weight of the copolymer of the components (A) and (B). If the amount is less than 0.1 parts by weight, sufficient crosslinking cannot be obtained. If the amount exceeds 2 parts by weight, the amount is excessive, and the adhesive strength and heat resistance are both reduced.
[0017]
The (D) component organic carboxylic acid metal salt is a curing catalyst for the (A) to (C) components, such as dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, tin octoate, tin naphthate, lead octoate. Iron octoate, zinc octoate, and the like. Among these, dibutyltin diacetate and dibutyltin dioctoate are particularly preferable.
[0018]
The blending amount of the component (D) is 0.5 to 5 parts by weight with respect to 100 parts by weight of the copolymer of the component (A) and the component (B). If it is less than 0.5 part by weight, the curability is slow, and if it exceeds 5 parts by weight, the pot life is shortened and workability is deteriorated.
[0019]
The (E) component boron-containing siloxane is an adhesion aid for imparting stronger adhesiveness to the adhesive composition comprising the components (A) to (D). Conventionally, it is well known that a primer treatment is performed on a substrate in advance for the purpose of improving the adhesion between the substrate and the substrate. In the present invention, by adding the component (E) to the present adhesive composition, such primer treatment is not required, so that workability is improved.
[0020]
The boron-containing siloxane as the component (E) is not particularly limited as long as it is an organosilicon compound having a B—O—Si bond, but an oligomer and a polymer are preferred because the monomer is highly hydrolyzable. Examples of the boron-containing siloxane include the following average composition formula (2)
R ⁴ _c (R ⁵ O) _d SiO _{(4-cd) / 2} (2)
(In the formula, R ⁴ represents a monovalent hydrocarbon group, R ⁵ represents a hydrogen atom or a monovalent hydrocarbon group, and c and d are 0 <c <4, 0 <d <4, and 0 <c + d <4. Is a positive number satisfying.)
A reaction product of organopolysiloxane and boric acid represented by
[0021]
Here, as R ⁴ , a monovalent hydrocarbon group having 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms is preferable, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and the like. Examples thereof include aryl groups such as alkyl groups, phenyl groups and tolyl groups, and alkenyl groups such as vinyl groups and allyl groups, and R ⁵ is a hydrogen atom or a monovalent hydrocarbon having 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms. Groups, specifically, alkyl groups such as methyl group, ethyl group, propyl group and isopropyl group, and alkenyl groups such as vinyl group, allyl group and isopropenyl group, but R ⁴ and R ^{5 in} one molecule are exemplified. Each of these need not be identical. Further, it is not necessary to combine the hydroxyl group of boric acid with the R ⁵ O group, but an equimolar amount or an excess of R ⁵ O group is preferred in terms of stability of the present compound.
[0022]
In addition, the reaction product of the organopolysiloxane and boric acid can be obtained by reacting the organopolysiloxane and boric acid under heating. For example, B (OH) ₃ 16 parts by weight, It can be obtained by reacting 46 parts by weight of CH ₃ Si (OC ₂ H ₅ ) ₃ and 38 parts by weight of (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₂ at 70 ° C. for 6 hours.
[0023]
(E) The compounding quantity of a component is 0.05-5 weight part with respect to 100 weight part of copolymers of (A) component and (B) component. If it is less than 0.05 part by weight, the effect of improving the adhesiveness is poor, and if it exceeds 5 parts by weight, the heat resistance is lowered.
[0024]
The branched organopolysiloxane of component (F) is used for the purpose of improving the heat resistance of the adhesive composition comprising the components (A) to (E), and includes C ₆ H ₅ SiO _1.5 units and [ (CH ₃ ) ₂ SiO] A methylphenylpolysiloxane composed of _n units. Specifically, C ₆ H ₅ SiX ₃ and X — [(CH ₃ ) ₂ SiO] _n-1 (CH ₃ ) ₂ SiX (n is an integer of 5 to 100, X is an alkoxy group, hydrolysis of chlorine, etc. The functional group) is hydrolyzed and subsequently polymerized, and is optionally polymerized as C ₆ H ₅ CH ₃ SiX ₂ , (CH ₃ ) ₂ SiX ₂ , CH ₃ SiX ₃ , (C ₆ H ₅₎ a hydrolyzable silane, such as ₂ SiX ₂ may also be added. More _{specifically, C 6 H 5 CH 3 SiCl} 2, C 6 H 5 SiCl 3 and Cl - by alkali polymerization of _{[(CH 3) 2 SiO]} 20 (CH 3) 2 cohydrolyzate of SiCl can get.
[0025]
(F) The compounding quantity of a component is 0.1-10 weight part with respect to 100 weight part of copolymers of (A) component and (B) component. If it is less than 0.1 parts by weight, sufficient heat resistance cannot be obtained, and if it exceeds 10 parts by weight, sufficient adhesive strength cannot be obtained.
[0026]
In general, in order to obtain the adhesive composition of the present invention, the components (A), (B) and (F) are first reacted at 25 ° C. to 120 ° C. for 1 hour to 10 hours in the presence of an alkali condensation catalyst. . At this time, a diluting solvent such as toluene or xylene may be used. Next, the components (C) and (E) are mixed with the obtained reaction product.
[0027]
The composition of the present invention is used in the absence of a solvent or diluted with a solvent. For the purpose of improving coatability and controlling the film thickness, it may be diluted with a solvent such as toluene, xylene, ethylbenzene, hexane, heptane, octane, methyl ethyl ketone, or ethyl acetate.
[0028]
The silicone adhesive composition of the present invention thus obtained has excellent adhesive properties when the component (D) is added and then applied to various substrates and cured to form an adhesive layer. can get. Examples of the base material include metals such as iron, copper, and aluminum, plastics such as polyester, polyimide, polyamide, and polyimide amide, cloth such as glass cloth, paper such as Japanese paper and synthetic paper, and silicone rubber that is generally difficult to adhere. Can be used.
[0029]
This composition containing the components (A) to (F) is applied to a substrate, air-dried at 25 ° C. to 50 ° C. for 5 to 30 minutes, and then applied and then left at room temperature for 1 hour. A good adhesive force can be obtained, and a stronger adhesive force can be obtained by leaving it to stand.
[0030]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples, parts indicate parts by weight. Moreover, the adhesive force shown in the Example was measured with the following method.
[0031]
(Measurement method of adhesive strength)
After the silicone adhesive composition is applied to the substrate to a predetermined thickness (0.8 g / m ² ), it is air-dried for 30 minutes and then affixed to various adherends using a 2 kg heavy rubber roller. It was. The test piece was allowed to stand at 25 ° C./55% RH for 5 hours and heated at 200 ° C. for 24 hours, and then peeled off using an autograph (manufactured by Shimadzu Corporation) at 0.3 m / min. The adhesive strength when peeled at 180 ° Peel at a speed of was measured and displayed in units of gf / 10 mm. The shear adhesive strength was 50 mm / min. Using a strograph [manufactured by Toyo Seiki Co., Ltd.]. The adhesive strength when peeled off in the vertical direction at a speed of was displayed in units of gf / cm ² . The results were peeled off and the adhesive strength was shown in Table 1, and the shear adhesive strength was shown in Table 2.
[0032]
[Example 1]
Methylpolysiloxane comprising 100 parts of dimethylpolysiloxane blocked with hydroxyl groups at both ends (viscosity 50 Pa · s), _0.5 units of (CH ₃ ) ₃ SiO ₂ and ₂ units of SiO ₂ and a molar ratio of 0.8: 1.0 A mixture of 200 parts of siloxane and 130 parts of toluene was heated and stirred at 110 ° C. for 5 hours and then cooled to obtain an adhesive base solution (solid content: 70%). With respect to 100 parts of this solution, 2 parts of methylhydrogenpolysiloxane represented by the average composition formula (CH ₃ ) ₃ SiO [(CH ₃ ) HSiO] ₃₈ Si (CH ₃ ) ₃ , (CH ₃ SiO _1.5 ) _{0 .1} [(CH ₃ ) ₂ SiO] _0.8 (BO _1.5 ) 1 part of a boron-containing polysiloxane represented by _0.1 , average composition formula (C ₆ H ₅ CH ₃ SiO) _0.02 (C ₆ H ₅ SiO _1.5 ) _0.46 [(CH ₃ ) ₂ SiO] 2 parts of branched methylphenylpolysiloxane represented by _0.52 and CAT-PS-1 (dibutyltin diacetate, manufactured by Shin-Etsu Chemical: product name ) 3 parts were mixed to obtain a silicone adhesive composition-1.
[0033]
[Example 2]
A silicone adhesive composition-2 was obtained in the same manner as in Example 1, except that the viscosity of the hydroxyl group-blocked dimethylpolysiloxane of Example 1 was changed to 10 Pa · s.
[0034]
[Example 3]
Example 1 except that the blending amount of methylpolysiloxane in which the molar ratio of (CH ₃ ) ₃ SiO _0.5 unit and SiO ₂ unit in Example 1 is 0.8: 1.0 is changed to 160 parts. In the same manner, a silicone adhesive composition-3 was obtained.
[0035]
[Comparative Example 1]
A silicone adhesive composition-4 was obtained in the same manner as in Example 1 except that the boron-containing polysiloxane of Example 1 was not blended at all.
[0036]
[Comparative Example 2]
A silicone adhesive composition-5 was obtained in the same manner as in Example 1 except that the branched methylphenyl polysiloxane of Example 1 was not blended at all.
[0037]
[Comparative Example 3]
A silicone adhesive composition-6 was obtained in the same manner as in Example 1 except that the viscosity of the both-end hydroxyl group-blocked dimethylpolysiloxane of Example 1 was changed to 500 Pa · s.
[0038]
[Comparative Example 4]
Except that the amount of methylpolysiloxane composed of (CH ₃ ) ₃ SiO _0.5 unit and SiO ₂ unit of Example 1 and having a molar ratio of 0.8: 1.0 was changed to 130 parts, In the same manner as in Example 1, a silicone adhesive composition-7 was obtained.
[0039]
[Comparative Example 5]
Benzoyl peroxide 2 is added to 100 parts of silicone, which is composed of 100 parts of a hydroxyl group-blocked dimethylpolysiloxane (viscosity 10,000 Pa · s) and 130 parts of M: Q = 0.85: 1.0 MQ resin. The pressure-sensitive adhesive-1 obtained by mixing the parts was applied to the substrate to a predetermined thickness, cured at 150 ° C. for 15 minutes, and then adhered to the adherend in the same manner as in the examples, and allowed to stand for a predetermined time and then adhered. The force was measured.
[0040]
[Table 1]

[0041]
[Table 2]

* 1: KE-951U (manufactured by Shin-Etsu Chemical Co., Ltd .; thickness 2 mm)
* 2: JIS SH-748-L (manufactured by Test Piece Co., Ltd .; thickness 0.3 mm)
* 3: After standing at 25 ° C./55% RH × 10 hours * 4: After 200 ° C. × 20 hours * 5: JIS SH-741-A (manufactured by Test Piece Co., Ltd .; thickness 0.3 mm)
* 6: JIS SG-743-A (manufactured by Test Piece Co., Ltd .; thickness: 0.3 mm)
* 7: KE-4603U (manufactured by Shin-Etsu Chemical Co., Ltd .; thickness 2 mm)
[0042]
【The invention's effect】
According to the silicone adhesive composition of the present invention, the adhesive strength to silicone rubber, metal, glass, etc. is improved, the adhesive strength is significantly improved over conventional silicone pressure-sensitive adhesives, and at room temperature for a short time without primer treatment. Since it can be hardened, it is excellent in workability.

Claims (1)

(A) The following general formula (1)

(In the formula, R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group, and m is an integer of 200 to 2000.)
Diorganopolysiloxane having hydroxyl groups at both ends represented by: 100 parts by weight,
(B) Organopoly having a molar ratio of SiO ₂ units to R ² ₃ SiO _0.5 units (R ² represents a monovalent hydrocarbon group having 3 or less carbon atoms) of 1: 0.5 to 1: 1.5 Siloxane resin: 150 to 300 parts by weight,
(C) Organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in one molecule: 0.1 to 2 parts by weight relative to 100 parts by weight of the total amount of components (A) and (B),
(D) Organic carboxylic acid metal salt wherein the metal is selected from tin, lead, iron and zinc: 0.5 to 5 parts by weight relative to 100 parts by weight of the total amount of components (A) and (B),
(E) Boron-containing polysiloxane: 0.05 to 5 parts by weight with respect to 100 parts by weight of the total amount of components (A) and (B),
(F ) Branched organopolysiloxane composed of C ₆ H ₅ SiO _1.5 units and [(CH ₃ ) ₂ SiO] _n units (n is an integer of 5 to 100): total amount of components (A) and (B) 100 A silicone adhesive composition comprising 0.1 to 10 parts by weight as an essential component with respect to parts by weight.