JP3696427B2 - Plastic molded product - Google Patents

Description

【００２２】
（上記式中、ａ及びｂは、０＜ａ＜２、1≦ｂ≦３、及び２≦ａ＋ｂ≦３を満たす数である。Ｒ¹は脂肪族不飽和結合を含有しない置換または非置換の一価炭化水素基であり、通常、炭素原子数１〜１０の基であり、好ましくは、炭素原子１〜６の基である。Ｒ¹としては、具体的には、メチル基、エチル基、プロピル基、ブチル基等のアルキル基；フェニル基、トリル基、キシリル基、ベンジル基等のアリール基；シクロヘキシル基等のシクロアルキル基；これらの基の水素原子の一部または全部をハロゲン原子、シアノ基等の置換基で置換した、クロロメチル基、シアノエチル基、３，３，３−トリフルオロプロピル基等が例示される。なお複数のＲ¹は同一でも異なっていてもよい。）で表されるものが好適に使用される。
【００２３】
珪素含有化合物及び／又はその重合体（Ｂ）は、それ自体公知の方法で製造することができる。製造方法を例示すれば、Ｒ¹SｉＨＣｌ₂、Ｒ¹ ₃SｉＣｌ、Ｒ¹ ₂SｉＣｌ₂、Ｒ¹ ₂SｉＨＣｌ、（各式中、Ｒ¹は前記の通りである。）等のクロロシランを加水分解する方法、このように加水分解して得られたシロキサンを平衡化する方法により製造することができる。
【００２４】
珪素含有化合物及び／又はその重合体（Ｂ）の配合量は、ポリブチレンテレフタレート樹脂１００重量部当たり、０．０１〜３重量部、好ましくは、０．０１〜２重量部である。０．０１重量部未満では接着性の改良効果が見られず、３重量部を越えると金型から離型しにくくなり、製品として組み付けた時相手部材に固着してしまう問題が生じる。
【００２５】
フェノール系抗酸化剤（Ｃ）は、例えばヒンダートフェノール化合物及びその誘導体である。好ましいフェノール系抗酸化剤（Ｃ）としては、２，６−ジ−ｔ−ブチル−ｐ−クレゾール、２，２’−メチレン−ビス−（４−メチル−６−ジ−ｔ−ブチルフェノール）、４，４’−チオビス（３−メチル−ｔ−ブチルフェノール）、１，１，３−トリス（２−メチル−４−ヒドロキシ−５−ｔ−ブチルフェニル）ブタン、ペンタエリスリチルーテトラキス［３−（３，５−ジ−ｔ−ブチル−４−）プロピオネート］、オクタデシル−３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネートであり、特に好ましくは、ペンタエリスリチルーテトラキス［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］が挙げられる。これらのフェノール系抗酸化剤は１種類、又は２種類以上を同時に用いる事ができる。
【００２６】
フェノール系抗酸化剤（Ｃ）の配合量は、ポリブチレンテレフタレート（Ａ）１００重量部当たり、０．０１〜０．５重量部であることが必要であり、０．１〜０．３重量部が好ましい。０．０１重量部より少ない場合は、耐熱性の改良効果が少なく、０．５重量部より多く配合しても耐熱老化性の改良効果は望めない。
【００２７】
本発明のポリブチレンテレフタレート樹脂組成物は、１，３，５，７−テトラメチル−シクロテトラシロキサンを特定量含有する必要がある。実用上十分な接着力を再現良く確保するために必要な、１，３，５，７−テトラメチル−シクロテトラシロキサンの含有量は、全ポリブチレンテレフタレート樹脂組成物あたり１ｐｐｍ以上である。この量は、好ましくは５ｐｐｍ以上、さらに好ましくは１０ｐｐｍ以上であり、上限は珪素含有化合物及び／又はその重合体（Ｂ）の配合量である。ポリブチレンテレフタレート樹脂組成物中の１，３，５，７−テトラメチル−シクロテトラシロキサンの含有量は、ペレットあるいは成形品からの揮発ガスとしてガスクロマトグラフィーで定量した値である。
【００２８】
本発明における接着再現性とは、試験片の保存状態やシリコーンゴムの塗布・硬化条件によらず実用上十分な接着力を発現することをいう。
【００２９】
本発明のポリブチレンテレフタレート樹脂組成物には、チオエーテル系抗酸化剤（Ｄ）を配合することが好ましい。チオエーテル系抗酸化剤（Ｄ）が配合される場合、チオエーテル系抗酸化剤（Ｄ）は、好ましくはジ−トリデシル−チオ−ジプロピオネート、テトラキス［メチレン−３−（ドデシルチオ）プロピオネート］、ビス［２−メチル−４−｛３−ｎ−アルキル（Ｃ１２又はＣ１４)チオプロピオニルオキシ｝−５−ｔ−ブチルフェニル］スルフィドである。
【００３０】
チオエーテル系抗酸化剤（Ｄ）が配合される場合、その配合量は全ポリブチレンテレフタレート樹脂組成物１００重量％あたり０〜０．０５重量％、好ましくは０．００１〜０．０５重量％である。０．０５重量％より多く配合するとポリブチレンテレフタレート樹脂成形品を長期間保管した後シリコーンゴムと接着させた場合に接着強度が低下する。
【００３１】
本発明のポリブチレンテレフタレート樹脂組成物には、本発明の目的を損なわない範囲で、ガラス繊維、炭素繊維等のごとき繊維状の強化材、粒状、無定形、板状、鱗片状等の無機充填剤、核剤、滑剤、酸化防止剤、紫外線吸収剤、光安定剤、熱安定剤、帯電防止剤、顔料等の添加剤、更に又難燃剤、衝撃改良剤、流動性改良剤等の改質剤を含有せしめることができる。
【００３２】
本発明のポリブチレンテレフタレート樹脂組成物の製造方法は、ポリブチレンテレフタレート樹脂（Ａ）と珪素含有化合物及び／又はその重合体（Ｂ）とを均一にブレンドし、更にフェノール系抗酸化剤（Ｃ）、チオエーテル系抗酸化剤（Ｄ）等を加えてブレンドした後、単軸又は多軸押出機等を用いて熔融混練することにより製造することができる。また、射出成形機又は押出成形機で直接混練、成形してもよい。ただし、１，３，５，７−テトラメチル−シクロテトラシロキサンの発生量は、樹脂の温度と、樹脂が溶融状態でいる時間（以下、滞留時間と表記）に左右される。
【００３３】
押出機、成形機を問わず、溶融時の樹脂温度が２４５〜２７０℃かつ滞留時間は１００〜４００秒が必要であり、更に好ましくは樹脂温度が２５５〜２６５℃かつ滞留時間が１００〜３００秒である。これよりも樹脂温度が高い場合や滞留時間が長い場合には、 生成した１，３，５，７−テトラメチル−シクロテトラシロキサンが様々な副反応により発生量が減少するため好ましくない。また、樹脂温度が高く、滞留時間が長い場合は、ＰＢＴの劣化が進行し、耐加水分解性が低下するため好ましくない。樹脂温度が低く、滞留時間が短いと、１，３，５，７−テトラメチル−シクロテトラシロキサンが生成されにくく好ましくない。
【００３４】
押出時の滞留時間は、ホッパーから着色させたペレットを投入し、吐出している樹脂の色が変化するまでの時間を計測することにより求めることができ、成形時の滞留時間は、シリンダー容量を物性試験片モールドの樹脂量（金型容量）で割り、１サイクルの時間を掛けることにより見積もることができる。
【００３５】
あらかじめ上記樹脂組成物を溶融混練することなく、射出成形機又は押出成形機で熔融混練して成形する場合は、上記の条件を満たし、かつ樹脂組成物の成分量比にむらがないようにすることが好ましい。樹脂組成物の成分比にむらがあると、接着性にむらを生ずるのみならず、他の樹脂の特性にばらつきを生じるため好ましくない。成分比のむらをなくすには、スクリューの形状、スクリューの回転数、背圧などをコントロールすることが重要である。背圧は５Ｋｆ／ｃｍ²以上かけるのが好ましいが、計量時間を短くするために背圧を大きくするとともにスクリューの回転数を高くすることが好ましく、１００ｒｐｍ以上であることが好ましい。
【００３６】
【実施例】
以下、実施例を挙げて本発明をさらに具体的に説明する。
実施例中、部とあるのは重量部を表す。ポリマーの固有粘度［η］はオルソクロロフェノール中２５℃で測定した溶液粘度から算出した値である。また、末端カルボキシル基濃度［ＣＯＯＨ］はエイ・コニックス（Ａ．Ｃｏｎｉｘ）の方法｛Ｍａｋｒｏｍｏｌ．Ｃｈｅｍ，２６，２２６（１９５８）｝によって測定したポリマー１０⁶gあたりの当量数である。
【００３７】
射出成形時の樹脂温度は、射出率３ｃｍ³／ｓｅｃでゆっくり射出した時のノズルから出てくる樹脂の中に直接温度計を挿入して測定した。
【００３８】
１，３，５，７−テトラメチル−シクロテトラシロキサンの含有量は、試料（ペレットあるいは成形品を約５×５×１〜３ｍｍの大きさに切断したもの）３ｇを２２ｍｌのバイアルに取り、１５０℃で６０分間熱処理したときの揮発ガスと標準品として１，３，５，７−テトラメチル−シクロテトラシロキサンのガスをガスクロマトグラフィーで比較測定することにより求めた。
【００３９】
ガスクロマトグラフィーにはヘッドスペースガスクロマトグラフィー（（株）島津製作所製ＨＳ−ＧＣ：ＧＣ−９Ａ ＨＳＳ−２ＡとＣＲ−４Ａ）を用いた。
【００４０】
また、標準品としての１，３，５，７−テトラメチル−シクロテトラシロキサンは、チッソ社製のものを用いた。
【００４１】
分析条件は以下の通りである。

【００４２】
［参考例１］付加型シリコーンゴムの調整
１分子中にメチルビニルシロキサン単位を２個有し、末端がジメチルビニルシロキシ基で停止している時メチルポリシロキサン（２５℃における粘度：１０００ｃＳｔ）１００重量部、珪素原子に直接結合している水素原子が１００ｇあたり０．７３９モル有するメチルハイドロジェンポリシロキサン４．６重量部、及び塩化白金酸のオクチルアルコール変性溶液（白金含有量：０．５％）０．１２重量部を配合して付加型シリコーンゴムを調整した。
【００４３】
［実施例１〜３、比較例１〜３］
表１に示すポリブチレンテレフタレート（実施例中、ＰＢＴと略記することがある）、珪素含有化合物及びその重合体、フェノール系抗酸化剤、チオエーテル系抗酸化剤、及びその他充填材を所定量配合し、均一に混合した。得られた混合物を４４ｍｍφ二軸押出機でバレル温度：２５０℃、吐出量：５０Ｋｇ／ｈ、回転数：１６０ｒｐｍにて溶融混練し、ダイから吐出されるスレッドを冷却、切断して成形用ペレットを得た。滞留時間を測定する目的で、ホッパーからカーボンブラックを２０％含有したＰＢＴを投入し、スレッドが黒く着色するまでの時間を計測したところ１４０秒程度であった。ついでこのペレットを１３０℃で５時間乾燥した後、４オンスの射出成形機（シリンダー容量：１５４ｇ（ＰＢＴ））に物性試験片モールド（樹脂量（金型容量）：２２ｇ（ＰＢＴ））を取り付けて、シリンダー温度２６０℃、金型温度４０℃、射出圧力７００Ｋｇ／ｃｍ²、射出時間６秒、冷却時間１０秒、全サイクル２５秒の成形条件をとることによって、樹脂の滞留時間を１７５秒として、引張試験片（ＡＳＴＭ４号片）を成形した。ただし、滞留時間は、シリンダー容量を物性試験片モールドの樹脂量（金型容量）で割り、１サイクルの時間を掛けることにより求めた。
【００４４】
シリコーンゴムとの接着性は、１２０℃に加熱した金型の下型に引張試験片を敷き、幅２５ｍｍ×長さ１５ｍｍの部分を残してテフロンシートでマスキングし、参考例で調整した付加型シリコーンゴムを塗布した。次いで上型を締め、１２０℃×１０分間加圧下で硬化させた。引張試験片と硬化したシリコーンゴムとを１８０°方向に引張、剥離性及び剥離強度を評価した。
【００４５】
耐加水分解性の試験は、１２２℃、湿度１００％ＲＨの条件で６０時間の湿熱処理を行った試験片について引張強度及び破断伸度を測定することによって行った。
【００４６】
【表１】

【００４７】
［比較例４］
実施例１の組成物について、成形条件をシリンダー温度２７０℃、金型温度４０℃、射出圧力７００Ｋｇ／ｃｍ²、射出時間１０秒、冷却時間３０秒、全サイクル５０秒に変え滞留時間を３５０秒とした以外は、実施例１と同様に引張試験片を得、同じ条件でシリコーンゴムとの接着性を評価した。
【００４８】
［比較例５］
実施例１の組成物について、５オンスの射出成形機（シリンダー容量：１９２ｇ（ＰＢＴ））に物性試験片モールド（樹脂量（金型容量）：１８ｇ）を取り付けて、シリンダー温度２６０℃、金型温度８０℃、射出圧力７００Ｋｇ／ｃｍ²、射出時間１０秒、冷却時間２５秒、全サイクル４２秒の成形条件をとることによって、樹脂の滞留時間を４４８秒として、引張試験片（ＡＳＴＭ４号片）を成形した。
【００４９】
【表２】

【００５０】
本発明の樹脂組成物は、シリコーンゴムに対して良好な接着性を示した。押出条件や成形条件を高い温度でかつ長い時間加熱ことになる条件をとると、１，３，５，７−テトラメチル−シクロテトラシロキサンの生成量が少なくなり、シリコーンゴムに対する接着強度が低下した。
【００５１】
【発明の効果】
本発明によれば、優れた耐加水分解性を備え、シリコーンゴムに対して高い接着力で再現性よく接着することのできるポリブチレンテレフタレート樹脂組成物を提供することができる。その結果、相互の高い接着力で接合されたポリブチレンテレフタレート樹脂組成物とシリコーンゴムとの一体成形品を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polybutylene terephthalate resin composition that is excellent in durability of polybutylene terephthalate resin, in particular, hydrolysis resistance, and adheres firmly to silicone rubber with good reproducibility.
[0002]
[Prior art]
Thermoplastic polyester resins, especially polybutylene terephthalate (hereinafter sometimes abbreviated as PBT) resins are excellent in chemical resistance, heat resistance and mechanical properties, and are widely used as industrial resins. In recent years, with increasing demands for hydrolysis resistance and heat aging resistance, it firmly adheres to silicone rubber that satisfies the above required characteristics in the electric / electronic field and automobile field, and is excellent in heat resistance, electrical characteristics, and weather resistance. There is a need for polybutylene terephthalate resins.
[0003]
Conventionally, as a method of adhering addition-curable silicone rubber and thermoplastic polyester resin, for example, a method of applying a primer on the surface of a molded article and then coating and curing an uncured silicone rubber material on the surface, or self-adhesive silicone A method is known in which a rubber material is coated and cured from above a molded product.
[0004]
Japanese Patent Publication No. 2-34311 discloses a method of adding an organopolysiloxane containing 30% mol or more of hydrogen atoms directly bonded to silicon atoms to an organic resin and bonding it to an addition-curable silicone rubber. JP-A-165516 proposes a method in which polybutylene terephthalate containing a thermoplastic resin containing a 30% molar aliphatic unsaturated group and silicone rubber are integrated. JP-A-9-164634 discloses a compound containing a hydrogen atom bonded directly to a silicon atom with respect to polybutylene terephthalate polymerized with a titanium-based catalyst at a terminal carboxyl group of 15 equivalents / 10 ⁶ g or less. Has been proposed as an integral molded body with silicone rubber.
[0005]
However, the method of adhering using a primer requires a complicated work process of taking out the resin composition once molded from the mold and applying the primer.
[0006]
The method of curing the self-adhesive silicone rubber material on the resin molded product is that the silicone rubber itself adheres to the mold and is removed when a molded body of resin and silicone rubber is formed using a mold or the like. There is a big difficulty that becomes difficult. Furthermore, when applying and curing to synthetic resin moldings, many of the self-adhesive addition-type silicone rubber materials have sufficient adhesive strength to be used as integral moldings for polybutylene resins. Absent.
[0007]
The method of adding a thermoplastic resin containing an aliphatic unsaturated group is not preferable because the unsaturated group is easily oxidized and causes discoloration, and heat resistance is impaired.
[0008]
In addition, a compound containing a hydrogen atom directly bonded to a silicon atom, etc., blended with a polybutylene terephthalate resin may not satisfy the adhesive strength, and there is a problem that it does not have necessary and sufficient adhesion reproducibility. .
[0009]
[Problems to be solved by the invention]
The present invention greatly improves the hydrolysis resistance, which has been increasingly demanded as an industrial resin material for polybutylene terephthalate resin, and has an adhesive strength sufficient to allow the polybutylene terephthalate resin and silicone rubber to withstand practical use. In order to obtain an integrally molded product of a polybutylene terephthalate resin composition and a silicone rubber bonded together, and to obtain such an integrally molded product, a polybutylene terephthalate resin and a silicone rubber are necessary and sufficient in a short time. It is an object of the present invention to provide a polybutylene terephthalate resin composition that can be bonded with excellent bond reproducibility and that can be obtained by injection molding.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to solve such problems, the present inventors have found that the content of 1,3,5,7-tetramethyl-cyclotetrasiloxane derived from the silicon-containing compound and / or polymer thereof in the resin composition Has been found to be able to adhere reliably and easily in a short time regardless of the storage conditions of the resin molded product and the application / curing conditions of the silicone rubber, when the measured value of the molded product is 5 ppm or more. Reached. In particular, it has been found that an integral molded product of the polybutylene terephthalate resin composition and silicone rubber can be obtained by injection molding, and that the silicone rubber itself is peeled from the molding die with sufficient practicality.
[0011]
That is, the present invention provides (A) a titanium compound as a polymerization catalyst, and the terminal carboxyl group concentration is 15 equivalents / ton or less per 100 parts by weight of polybutylene terephthalate.
(B) 0.01 to 3 parts by weight of a silicon-containing compound having a hydrogen atom directly bonded to at least one silicon atom and / or a polymer thereof in one molecule and (C) a phenol-based antioxidant 0.01 A polybutylene terephthalate resin composition comprising ~ 0.5 parts by weight,
1,3,5,7-tetramethyl-cyclotetrasiloxane derived from the silicon-containing compound and / or polymer (B) present in the polybutylene terephthalate resin composition is 5 ppm or more as a measured value of the molded product A molded article and a silicone comprising a polybutylene terephthalate resin composition, a resin temperature at melting of 245 to 270 ° C., and a time in which the resin is in a molten state is in the range of 100 to 400 seconds It is a molded product joined with a molded product made of rubber .
[0012]
Polybutylene terephthalate (A) is obtained using a titanium compound as a polymerization catalyst. Since polybutylene terephthalate (A) is obtained using a titanium compound as a polymerization catalyst, it does not inhibit the curing reaction of silicone rubber. Preferred titanium compounds include alkoxide titanate, with tetrabutoside titanate and tetraisopropoxide titanate being particularly preferred.
[0013]
The polybutylene terephthalate (A) needs to have a terminal carboxyl group concentration of 15 equivalents / ton or less. When the terminal carboxyl group concentration exceeds 15 equivalents / ton, no significant improvement in hydrolysis resistance, which is one of the main effects of the present invention, is observed.
[0014]
The polybutylene terephthalate (A) is a polyester having terephthalic acid as a main acid component and 1,4-butanediol as a main glycol component. Here, “main” refers to 80 mol% or more, preferably 90 mol% or more, based on the total acid component or total glycol component.
[0015]
Examples of the copolymerizable acid component include aromatic dicarboxylic acids other than terephthalic acid, such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, dipheneethane dicarboxylic acid, diphenyl ketone dicarboxylic acid, diphenyl sulfone dicarboxylic acid. And aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, tetralindicarboxylic acid and decalindicarboxylic acid.
[0016]
Examples of copolymerizable glycol components other than butanediol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexane dimethanol, xylylene glycol, and bisphenol A.
[0017]
Further, a polyfunctional compound such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, pyromellitic acid and the like may be copolymerized as long as the polyester does not substantially impair the moldability.
[0018]
The polybutylene terephthalate (A) used in the present invention has an intrinsic viscosity (value calculated based on a measured value in orthochlorophenol at 35 ° C.), preferably 0.3 or more, more preferably 0. .5 or more. If the intrinsic viscosity is lower than this, the strength is low and it is difficult to use.
[0019]
The silicon-containing compound of component (B) and / or a polymer thereof used in the present invention has at least one hydrogen atom bonded directly to a silicon atom in one molecule. The silicon-containing compound and / or polymer (B) thereof can be used in any structure such as linear, branched or cyclic as its molecular structure. Moreover, the viscosity at 25 ° C. of the silicon-containing compound and / or the polymer (B) is preferably 0.5 to 1000 cSt, and more preferably 1 to 200 cSt. If the viscosity is lower than this, it tends to bleed out on the surface of the resin molded article, and if it is higher than this, the adhesiveness is inferior, which is not preferable.
[0020]
As a silicon containing compound and / or its polymer (B), the compound shown to the following average compositional formula (1) can be illustrated, for example.
[0021]
[Chemical 1]

[0022]
(In the above formula, a and b are numbers satisfying 0 <a <2, 1 ≦ b ≦ 3, and 2 ≦ a + b ≦ 3. R ¹ is a substituted or unsubstituted group that does not contain an aliphatic unsaturated bond. It is a monovalent hydrocarbon group, usually a group having 1 to 10 carbon atoms, and preferably a group having 1 to 6 carbon atoms, specifically, R ¹ includes a methyl group, an ethyl group, Alkyl groups such as propyl group and butyl group; aryl groups such as phenyl group, tolyl group, xylyl group and benzyl group; cycloalkyl groups such as cyclohexyl group; some or all of hydrogen atoms of these groups are halogen atoms, cyano And a chloromethyl group, a cyanoethyl group, a 3,3,3-trifluoropropyl group, etc. substituted with a substituent such as a group, etc., wherein a plurality of R ¹ may be the same or different. Those are preferably used.
[0023]
The silicon-containing compound and / or the polymer (B) thereof can be produced by a method known per se. To illustrate the production method, chlorosilane such as R ¹ SiHCl ₂ , R ¹ ₃ SiCl, R ¹ ₂ SiCl ₂ , R ¹ ₂ SiHCl (wherein R ¹ is as described above) is hydrolyzed. It can be produced by a method, a method of equilibrating the siloxane thus obtained by hydrolysis.
[0024]
The compounding quantity of a silicon containing compound and / or its polymer (B) is 0.01-3 weight part per 100 weight part of polybutylene terephthalate resin, Preferably, it is 0.01-2 weight part. If it is less than 0.01 part by weight, the effect of improving the adhesiveness is not seen, and if it exceeds 3 parts by weight, it becomes difficult to release from the mold, and there arises a problem that it adheres to the mating member when assembled as a product.
[0025]
The phenolic antioxidant (C) is, for example, a hindered phenol compound and a derivative thereof. Preferred phenolic antioxidants (C) include 2,6-di-t-butyl-p-cresol, 2,2′-methylene-bis- (4-methyl-6-di-t-butylphenol), 4 , 4′-thiobis (3-methyl-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, pentaerythrityl-tetrakis [3- (3 , 5-di-t-butyl-4-) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, particularly preferably pentaerythrityl-tetrakis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate]. These phenolic antioxidants can be used alone or in combination of two or more.
[0026]
The blending amount of the phenolic antioxidant (C) needs to be 0.01 to 0.5 parts by weight per 100 parts by weight of the polybutylene terephthalate (A), and 0.1 to 0.3 parts by weight. Is preferred. When the amount is less than 0.01 part by weight, the effect of improving the heat resistance is small, and even when the amount is more than 0.5 part by weight, the effect of improving the heat aging resistance cannot be expected.
[0027]
The polybutylene terephthalate resin composition of the present invention needs to contain a specific amount of 1,3,5,7-tetramethyl-cyclotetrasiloxane. The content of 1,3,5,7-tetramethyl-cyclotetrasiloxane necessary for ensuring practically sufficient adhesive strength with good reproducibility is 1 ppm or more per total polybutylene terephthalate resin composition. This amount is preferably 5 ppm or more, more preferably 10 ppm or more, and the upper limit is the blending amount of the silicon-containing compound and / or polymer (B) thereof. The content of 1,3,5,7-tetramethyl-cyclotetrasiloxane in the polybutylene terephthalate resin composition is a value determined by gas chromatography as a volatile gas from pellets or molded articles.
[0028]
The adhesive reproducibility in the present invention means that a practically sufficient adhesive force is expressed regardless of the storage state of the test piece and the application / curing conditions of the silicone rubber.
[0029]
The polybutylene terephthalate resin composition of the present invention preferably contains a thioether antioxidant (D). When the thioether antioxidant (D) is blended, the thioether antioxidant (D) is preferably di-tridecyl-thio-dipropionate, tetrakis [methylene-3- (dodecylthio) propionate], bis [2- Methyl-4- {3-n-alkyl (C12 or C14) thiopropionyloxy} -5-t-butylphenyl] sulfide.
[0030]
When the thioether antioxidant (D) is blended, the blending amount is 0 to 0.05% by weight, preferably 0.001 to 0.05% by weight per 100% by weight of the total polybutylene terephthalate resin composition. . If it is added in an amount of more than 0.05% by weight, the adhesive strength is lowered when the polybutylene terephthalate resin molded product is stored for a long time and then bonded to silicone rubber.
[0031]
In the polybutylene terephthalate resin composition of the present invention, inorganic fillers such as glass fibers, carbon fibers and the like, granular reinforcing materials such as glass fibers and carbon fibers, granular shapes, plate shapes, scale shapes, and the like are included within the scope of the present invention. Agents, nucleating agents, lubricants, antioxidants, UV absorbers, light stabilizers, heat stabilizers, antistatic agents, additives such as pigments, and further modification of flame retardants, impact modifiers, fluidity improvers, etc. An agent can be included.
[0032]
In the method for producing a polybutylene terephthalate resin composition of the present invention, a polybutylene terephthalate resin (A) and a silicon-containing compound and / or a polymer (B) thereof are uniformly blended, and further a phenol-based antioxidant (C). Then, after adding and blending a thioether-based antioxidant (D) or the like, it can be produced by melt-kneading using a single-screw or multi-screw extruder or the like. Further, it may be directly kneaded and molded by an injection molding machine or an extrusion molding machine. However, the amount of 1,3,5,7-tetramethyl-cyclotetrasiloxane generated depends on the temperature of the resin and the time that the resin is in a molten state (hereinafter referred to as residence time).
[0033]
Extruder, regardless of the molding machine, the resin temperature is two hundred forty-five to two hundred and seventy ° C. and the residence time during melt is required 100 to 400 seconds, more preferably a resin temperature of two hundred fifty-five to two hundred and sixty-five ° C. and the residence time is 100 to 300 seconds It is. When the resin temperature is higher than this, or when the residence time is long, the generated 1,3,5,7-tetramethyl-cyclotetrasiloxane is not preferable because the generation amount is reduced by various side reactions. Moreover, when the resin temperature is high and the residence time is long, the deterioration of the PBT proceeds and the hydrolysis resistance is lowered, which is not preferable. If the resin temperature is low and the residence time is short, 1,3,5,7-tetramethyl-cyclotetrasiloxane is not easily produced, which is not preferable.
[0034]
The residence time at the time of extrusion can be determined by charging the colored pellets from the hopper and measuring the time until the color of the resin being discharged changes. It can be estimated by dividing by the amount of resin (mold capacity) of the physical property test piece mold and taking one cycle time.
[0035]
When melt-kneading with an injection molding machine or extrusion molding machine without melt-kneading the resin composition in advance, satisfy the above-mentioned conditions and ensure that the resin composition has no uneven component ratio. It is preferable. Unevenness in the component ratio of the resin composition is not preferable because not only unevenness in adhesion is caused, but also the characteristics of other resins are varied. In order to eliminate unevenness in the component ratio, it is important to control the shape of the screw, the rotational speed of the screw, the back pressure, and the like. The back pressure is preferably 5 Kf / cm ² or more, but in order to shorten the measurement time, it is preferable to increase the back pressure and increase the number of rotations of the screw, and preferably 100 rpm or more.
[0036]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
In the examples, “parts” means “parts by weight”. The intrinsic viscosity [η] of the polymer is a value calculated from the solution viscosity measured at 25 ° C. in orthochlorophenol. The terminal carboxyl group concentration [COOH] was determined by the method of A. Conix {Makromol. Chem, 26, 226 (1958)}, the number of equivalents per 10 ⁶ g of polymer.
[0037]
The resin temperature at the time of injection molding was measured by inserting a thermometer directly into the resin coming out of the nozzle when it was slowly injected at an injection rate of 3 cm ³ / sec.
[0038]
As for the content of 1,3,5,7-tetramethyl-cyclotetrasiloxane, 3 g of a sample (a pellet or molded product cut into a size of about 5 × 5 × 1 to 3 mm) was taken in a 22 ml vial, The volatile gas when heat-treated at 150 ° C. for 60 minutes and the gas of 1,3,5,7-tetramethyl-cyclotetrasiloxane as a standard product were obtained by comparative measurement by gas chromatography.
[0039]
Head space gas chromatography (HS-GC: GC-9A HSS-2A and CR-4A manufactured by Shimadzu Corporation) was used for gas chromatography.
[0040]
Further, as a standard product, those manufactured by Chisso Corporation were used as 1,3,5,7-tetramethyl-cyclotetrasiloxane.
[0041]
The analysis conditions are as follows.

[0042]
[Reference Example 1] Preparation of addition-type silicone rubber Methyl polysiloxane (viscosity at 25 ° C .: 1000 cSt) 100 weight when having two methylvinylsiloxane units in one molecule and terminated with dimethylvinylsiloxy group Part, 4.6 parts by weight of methylhydrogenpolysiloxane having 0.739 moles of hydrogen atoms directly bonded to silicon atoms, and octyl alcohol-modified solution of chloroplatinic acid (platinum content: 0.5%) Addition type silicone rubber was prepared by blending 0.12 parts by weight.
[0043]
[Examples 1-3, Comparative Examples 1-3]
A predetermined amount of polybutylene terephthalate shown in Table 1 (may be abbreviated as PBT in the examples), a silicon-containing compound and a polymer thereof, a phenol-based antioxidant, a thioether-based antioxidant, and other fillers. And mixed uniformly. The obtained mixture was melt kneaded at a barrel temperature of 250 ° C., a discharge amount of 50 Kg / h, and a rotation speed of 160 rpm with a 44 mmφ twin-screw extruder, and the threads discharged from the die were cooled and cut to form molding pellets. Obtained. For the purpose of measuring the residence time, PBT containing 20% carbon black was introduced from the hopper, and the time until the thread was colored black was measured. The pellets were then dried at 130 ° C. for 5 hours, and a physical property test piece mold (resin amount (mold capacity): 22 g (PBT)) was attached to a 4 ounce injection molding machine (cylinder capacity: 154 g (PBT)). By taking the molding conditions of cylinder temperature 260 ° C., mold temperature 40 ° C., injection pressure 700 Kg / cm ² , injection time 6 seconds, cooling time 10 seconds, total cycle 25 seconds, the resin residence time was set to 175 seconds. A tensile test piece (ASTM No. 4 piece) was molded. However, the residence time was determined by dividing the cylinder capacity by the resin amount (mold capacity) of the physical property test piece mold and taking one cycle time.
[0044]
Adhesion with silicone rubber is an addition type silicone prepared by laying a tensile test piece on the lower mold heated to 120 ° C. and masking it with a Teflon sheet leaving a 25 mm wide x 15 mm long part. Rubber was applied. The upper mold was then clamped and cured under pressure at 120 ° C. for 10 minutes. The tensile test piece and the cured silicone rubber were pulled in the 180 ° direction, and peelability and peel strength were evaluated.
[0045]
The hydrolysis resistance test was performed by measuring the tensile strength and elongation at break for a test piece that had been wet-heat treated for 60 hours under the conditions of 122 ° C. and humidity 100% RH.
[0046]
[Table 1]

[0047]
[Comparative Example 4]
For the composition of Example 1, the molding conditions were changed to a cylinder temperature of 270 ° C., a mold temperature of 40 ° C., an injection pressure of 700 kg / cm ² , an injection time of 10 seconds, a cooling time of 30 seconds, and a total cycle of 50 seconds, and a residence time of 350 seconds. Except that, a tensile test piece was obtained in the same manner as in Example 1, and the adhesion with silicone rubber was evaluated under the same conditions.
[0048]
[Comparative Example 5]
Regarding the composition of Example 1, a physical property test piece mold (resin amount (mold capacity): 18 g) was attached to a 5-ounce injection molding machine (cylinder capacity: 192 g (PBT)), a cylinder temperature of 260 ° C., and a mold A tensile test piece (ASTM No. 4 piece) with a resin residence time of 448 seconds by taking molding conditions of a temperature of 80 ° C., an injection pressure of 700 kg / cm ² , an injection time of 10 seconds, a cooling time of 25 seconds, and a total cycle of 42 seconds. Was molded.
[0049]
[Table 2]

[0050]
The resin composition of the present invention showed good adhesion to silicone rubber. When extrusion conditions and molding conditions were set to high temperature and for a long time, the amount of 1,3,5,7-tetramethyl-cyclotetrasiloxane produced was reduced and the adhesive strength to silicone rubber was reduced. .
[0051]
【The invention's effect】
According to the present invention, it is possible to provide a polybutylene terephthalate resin composition that has excellent hydrolysis resistance and can be adhered to a silicone rubber with high adhesive force and good reproducibility. As a result , it is possible to provide an integrally molded product of the polybutylene terephthalate resin composition and the silicone rubber bonded with high mutual adhesive strength.

Claims (1)

(A) per 100 parts by weight of polybutylene terephthalate obtained using a titanium compound as a polymerization catalyst and having a terminal carboxyl group concentration of 15 equivalents / ton or less,
(B) 0.01 to 3 parts by weight of a silicon-containing compound having a hydrogen atom directly bonded to at least one silicon atom and / or a polymer thereof in one molecule and (C) a phenol-based antioxidant 0.01 A polybutylene terephthalate resin composition comprising ~ 0.5 parts by weight,
1,3,5,7-tetramethyl-cyclotetrasiloxane derived from the silicon-containing compound and / or polymer (B) present in the polybutylene terephthalate resin composition is 5 ppm or more as a measured value of the molded product A molded article and a silicone comprising a polybutylene terephthalate resin composition, a resin temperature at melting of 245 to 270 ° C., and a time in which the resin is in a molten state is in the range of 100 to 400 seconds Molded product joined with a molded product made of rubber.