JP3556100B2 - Resin composition with excellent adhesion to silicone rubber - Google Patents

Description

【００１９】
上記式中、 ａ及びｂは、０＜ａ＜２、１≦ｂ≦２及び、２≦ａ＋ｂ≦３を満たす数である。Ｒ^１は脂肪族不飽和結合を含有しない置換又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。Ｒ^１としては、具体的には、例えば、メチル基、エチル基、プロピル基、ブチル基等のアルキル基；例えば、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；例えば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Ｒ^１は同一でも異なっていてもよい。
【００２０】
珪素含有化合物及び／又はその重合体としては、具体的には、下記式（２）で示される化合物を例示することができる。
【００２１】
【化２】

【００２２】
本発明で用いる（Ｂ）成分の珪素含有化合物及び／又はその重合体の配合量は、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。
【００２３】
本発明で用いられる（Ｃ）フェノール系抗酸化剤は、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としては、２、６ージーｔーブチルーｐークレゾール、２、２’ーメチレンービスー（４ーメチルー６ージーｔーブチルフェノール）、４、４’ーチオビス（３ーメチルーｔーブチルフェノール）、１、１、３ートリス（２ーメチルー４ーヒドロキシー５ーｔーブチルフェニル）ブタン、ペンタエリスリチルーテトラキス［３ー（３、５ージーｔーブチルー４ーヒドロキシフェニル）プロピオネート］、オクタデシルー３ー（３、５ージーｔーブチルー４ー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ー（３、５ージーｔーブチルー４ー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出来る。
【００２４】
本発明で用いられる（Ｃ）フェノール系抗酸化剤の配合量は、ポリブチレンテレフタレート樹脂１００重量部当たり、０．０１〜０．５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。
【００２５】
本発明で用いられることが好ましい成分である（Ｄ）チオエーテル系抗酸化剤は、好ましくはジートリデシルーチオージプロピオネート、テトラキス［メチレンー３ー（ドデシルチオ）プロピオネート］、ビス［２ーメチルー４ー｛３ーｎ−アルキル（Ｃ１２又はＣ１４）チオプロピオニルオキシ｝ー５ーｔーブチルフェニル］スルフィドである。
【００２６】
チオエーテル系抗酸化剤の配合量は、ポリブチレンテレフタレート樹脂１００重量部当たり、０〜０．０５重量部であり、０．０５重量部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物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。
【００２７】
本発明の樹脂組成物には、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、燐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。
【００２８】
【実施例】
以下に実施例を挙げて本発明を具体的に説明する。
【００２９】
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１Ｔ（１０^６ｇ）当たりの当量数である。
【００３０】
［参考例］
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ジ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エンポリシロキサン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製した。
【００３１】
［実施例１〜２、比較例１〜３］
表１に示すポリブチレンテレフタレート（以下、ＰＢＴと略記）、珪素含有化合物及び／又はその重合体、フェノール系抗酸化剤、チオエーテル系抗酸化剤、及びその他充填剤を所定量配合し、均一に混合した。得られた混合物を４４ｍｍ径の２軸押出機でバレル温度２５０℃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。次いで、このペレットを１３０℃で５時間乾燥した後、５オンスの射出成形機に物性用試験片モールドを取り付けてシリンダー温度２６０℃、金型温度４０℃、射出圧力７００Ｋｇ／ｃｍ^２、冷却時間２０秒、全サイクル３５秒の成形条件で引張試験片（ＡＳＴＭ４号）を成形した。
【００３２】
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置き、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、参考例で調製した付加型シリコーンゴムをで塗布した。ついで上型を締め、１２０℃×１０分加圧硬化させた。引張試験片と硬化したシリコーンゴムとを１８０℃方向に引張り、剥離性及び剥離強度を評価した。また、使用条件下でのＰＢＴ樹脂成形物とシリコーンゴムとの接着部のシール性を確保するとともに、保管中の接着性の低下を評価する促進試験として、引張試験片を２３℃の純水中に２４時間浸漬した後、同様な操作で接着し、その剥離性及び剥離強度を評価した。
【００３３】
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を評価した。
【００３４】
結果を表１に示す。本発明の組成物は、良好なシリコーンゴム接着性と耐加水分解性を示すことがわかる。（Ｂ）成分が含まれない場合はシリコーンゴムとの接着性が不十分で、［ＣＯＯＨ］＝３５当量／ＴのＰＢＴでは、ＰＣＴにおける機械的強度の低下が大きい。また、重合触媒としてチタン化合物でない、モノブチル錫オキサイドを用いた場合は、シリコーンゴムの硬化反応が阻害された。
【００３５】
【表１】

【００３６】
［比較例４〜５］
実施例１と同様の方法で表２に示す配合割合からなる組成物について、シリコーンゴムとの接着性を評価した。結果を表２に示す。
【００３７】
【表２】

【００３８】
本発明の組成物は、良好なシリコーンゴム接着性を示した。一方、チオエーテル系の抗酸化剤の配合量が過剰になると、吸湿による影響が大きくなり接着性が低下した。また、リン系の抗酸化剤を用いると、硬化が阻害された。
【００３９】
【発明の効果】
本発明によれば、ポリブチレンテレフタレート樹脂の耐加水分解性を大幅に改良し、且つポリブチレンテレフタレート樹脂とシリコーンゴムとが互いに十分実用に耐えうる接着力を以って接着し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体を提供することができ、かかる一体成形体を確実且つ容易に、しかも短時間で接着することを可能とし、また射出成形によってかかる一体成形体を得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。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a polybutylene terephthalate resin composition which has excellent durability, especially hydrolysis resistance, of a polybutylene terephthalate resin, and which firmly adheres to silicone rubber.
[0002]
[Prior art]
Thermoplastic polyester resins, especially polybutylene terephthalate resins, have excellent chemical resistance, heat resistance, and mechanical properties, and are widely used as industrial resins. In recent years, as the demand for hydrolysis resistance and heat aging resistance has increased, the adhesive has been firmly bonded to silicone rubber which satisfies the above-mentioned required properties in the electric / electronic field and automobile field, and has excellent heat resistance, electric properties and weather resistance. There is a need for polybutylene terephthalate resins.
[0003]
Conventionally, as a method of adhering an addition-curable silicone rubber and a thermoplastic polyester resin molded product, for example, a method of applying a primer to the surface of the molded product, coating and curing an uncured silicone rubber, and then bonding the self-adhesive silicone rubber. A method of directly coating and curing a molded product is known.
[0004]
[Problems to be solved by the invention]
However, the method of bonding using a primer requires a step of taking out a resin molded product once molded from a mold and applying a primer, resulting in poor productivity. Further, in the method of coating and curing the self-adhesive silicone rubber directly on the resin molded product, when forming an integral molded body with the resin and the silicone rubber using a mold or the like, the silicone rubber itself adheres to the mold. There is a major drawback.
[0005]
Furthermore, the resin molded product was left in water for a certain period of time as an accelerated test to evaluate the decrease in adhesion during storage while ensuring the sealing property of the bonded portion between the resin molded product and the silicone rubber under use conditions. Then, they are adhered and their peel strength is evaluated. In order to ensure the sealability of the bonded portion in practice, the inventor of the present invention must have a peel strength of 10 N or more when immersed in water for 24 hours and then measured as a molded body integrally with silicone rubber. Was found to be essential.
[0006]
The present invention significantly improves the hydrolysis resistance, which has been demanded as an industrial resin material of polybutylene terephthalate resin, and has an adhesive force that allows the polybutylene terephthalate resin and silicone rubber to sufficiently withstand practical use. To obtain an integrally molded article of the polybutylene terephthalate resin composition and the silicone rubber adhered by the above-mentioned method, and to make it possible to adhere such an integrally molded article reliably, easily, and in a short time. An object is to provide a polybutylene terephthalate resin composition from which a molded article can be obtained.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve such problems, and obtained a titanium compound as a polymerization catalyst and a polybutylene terephthalate resin having a low terminal carboxyl group concentration, a phenolic antioxidant and a specific silicon-containing compound and And / or by blending the polymer, it is possible to obtain an integrally molded article of the polybutylene terephthalate resin composition and silicone rubber, which can be bonded under a short curing condition and have practically sufficient adhesive strength. Found and arrived at the present invention. In particular, it has been found that when an integrated molded article of the polybutylene terephthalate resin composition and silicone rubber is formed by injection molding, the integrated molded article is released from a molding die with sufficient practicality.
[0008]
That is, the present invention
(A) per 100 parts by weight of polybutylene terephthalate obtained by using a titanium compound as a polymerization catalyst and having a terminal carboxyl group concentration of 15 equivalents / T or less,
(B) 0.01 to 3 parts by weight of a silicon-containing compound having at least one hydrogen atom directly bonded to a silicon atom in one molecule and / or a polymer thereof,
(C) a phenolic antioxidant 0.01 to 0.5 parts by weight,
(D) A polybutylene terephthalate resin composition comprising less than 0.01 part by weight of a thioether-based antioxidant, and a molded article comprising the composition is immersed in pure water at 23 ° C. for 24 hours. A resin composition having excellent adhesion to silicone rubber, having a peel strength of 10 N or more when the peel strength is measured as an integral molded body with the silicone rubber after the peeling.
Further, the present invention comprises the above-mentioned polybutylene terephthalate resin composition, and has a peel strength of 10 N when measured as a molded body integrally with silicone rubber after being immersed in pure water at 23 ° C. for 24 hours. The above-mentioned resin molded products having excellent adhesion to silicone rubber are also included.
[0009]
The polybutylene terephthalate resin as the component (A) of the present invention is obtained using a titanium compound as a polymerization catalyst and does not inhibit the curing reaction of silicone rubber. Preferred titanium compounds include tetrabutoxide titanate.
[0010]
The polybutylene terephthalate resin as the component (A) of the present invention must have a terminal carboxyl group concentration of 15 equivalents / T or less. When the terminal carboxyl group concentration exceeds 15 equivalents / T, a significant improvement in hydrolysis resistance, which is one of the main effects of the present invention, is not observed. In addition, T means 10 ⁶ g.
[0011]
The polybutylene terephthalate resin as the component (A) of the present invention is a polyester containing terephthalic acid as a main acid component and 1,4-butanediol as a main glycol component. Here, “main” means 80 mol% or more, preferably 90 mol% or more, based on all acid components or all glycol components.
[0012]
As the copolymerizable acid component, aromatic dicarboxylic acids other than terephthalic acid, for example, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphexiethanedicarboxylic acid, diphenylketonedicarboxylic acid, diphenylsulfonedicarboxylic acid, etc. 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.
[0013]
Examples of copolymerizable glycol components other than butanediol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, xylylene glycol, and bisphenol A.
[0014]
Polyfunctional compounds such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, and pyromellitic acid may be copolymerized as long as the polyester does not substantially impair moldability.
[0015]
The polybutylene terephthalate resin used in the present invention has an intrinsic viscosity (a value calculated based on a value measured in orthochlorophenol at 35 ° C.) of 0.3 or more, preferably 0.5 or more. preferable. If the intrinsic viscosity is lower than this, the strength is low and it cannot be used.
[0016]
The silicon-containing compound of component (B) and / or its polymer used in the present invention has at least one hydrogen atom directly bonded to a silicon atom in one molecule. The molecular structure is not particularly limited, and any of linear, branched, and cyclic structures can be used. The viscosity at 25 ° C. of the silicon-containing compound and / or its polymer is usually 0.5 to 1000 cSt, preferably 1 to 200 cSt.
[0017]
As the silicon-containing compound and / or the polymer thereof as the component (B), a compound represented by the following average composition formula (1) is preferable.
[0018]
Embedded image

[0019]
In the above formula, a and b are numbers satisfying 0 <a <2, 1 ≦ b ≦ 2, and 2 ≦ a + b ≦ 3. R ¹ is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, usually a group having 1 to 10 carbon atoms, and preferably a group having 1 to 6 carbon atoms. Specific examples of R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, and a benzyl group; and a cyclohexyl group and the like. A chloromethyl group, a cyanoethyl group, a 3,3,3, -trifluoropropyl group or the like in which some or all of the hydrogen atoms of these groups are substituted with a substituent such as a halogen atom or a cyano group; Is exemplified. A plurality of R ¹ may be the same or different.
[0020]
Specific examples of the silicon-containing compound and / or its polymer include a compound represented by the following formula (2).
[0021]
Embedded image

[0022]
The amount of the silicon-containing compound (B) used in the present invention and / or the polymer thereof is 0.01 to 3 parts by weight, preferably 0.01 to 2 parts by weight, per 100 parts by weight of the polybutylene terephthalate resin. It is. When the amount is less than 0.01 part by weight, the effect of improving the adhesiveness is not seen. When the amount exceeds 3 parts by weight, it is difficult to release from the mold, and there is a problem that the product adheres to the mating member when assembled as a product.
[0023]
The phenolic antioxidant (C) used in the present invention is a hindered phenol compound and a derivative thereof. Preferred phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, 2,2′-methylene-bis (4-methyl-6-di-tert-butylphenol), 4,4′-thiobis (3-methyl-tert-butylphenol), 1,3 tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-phenyl) 4-hydroxyphenyl) propionate, particularly preferably pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. One or two or more of these phenolic antioxidants can be used simultaneously.
[0024]
The blending amount of the phenolic antioxidant (C) used in the present invention needs to be 0.01 to 0.5 part by weight, and preferably 0.1 to 0.5 part by weight, per 100 parts by weight of the polybutylene terephthalate resin. 3 parts by weight are preferred. When the amount is less than 0.01 part by weight, the effect of improving the heat resistance is small, and when the amount is more than 0.5 part by weight, the effect of improving the heat aging resistance cannot be expected.
[0025]
The (D) thioether antioxidant, which is a component preferably used in the present invention, is preferably ditridecyl-thiodipropionate, tetrakis [methylene-3- (dodecylthio) propionate], bis [2-methyl-4-}. 3-n-alkyl (C12 or C14) thiopropionyloxy {-5-t-butylphenyl] sulfide.
[0026]
The compounding amount of the thioether-based antioxidant is 0 to 0.05 parts by weight per 100 parts by weight of the polybutylene terephthalate resin. When bonded to silicone rubber, the bonding strength is reduced.
[0027]
In the resin composition of the present invention, within the range not impairing the object of the present invention, glass fiber, fibrous reinforcing material such as carbon fiber, granular, amorphous, plate-like, flake-like inorganic filler, Additives such as nucleating agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, antistatic agents, pigments, and other modifiers such as flame retardants, impact modifiers, and flow improvers. It can be contained.
[0028]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
[0029]
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) is the number of equivalents per 1 T (10 ⁶ g) of the polymer measured by the method of A. Conix (Makromol. Chem, 26, 226 (1958)).
[0030]
[Reference example]
Adjustment of addition type silicone rubber:
100 parts by weight of dimethylpolysiloxane (viscosity at 25 ° C .: 1000 cSt) having two methylvinylsiloxane units in one molecule and terminated with a dimethylvinylsiloxy group, and a hydrogen atom directly bonded to a silicon atom Is added by mixing 4.6 parts by weight of methylhydrogenpolysiloxane having 0.739 mol per 100 g and 0.12 parts by weight of an octyl alcohol-modified chloroplatinic acid solution (platinum content: 0.5%). A rubber was prepared.
[0031]
[Examples 1 and 2, Comparative Examples 1 to 3]
A predetermined amount of polybutylene terephthalate (hereinafter abbreviated as PBT), a silicon-containing compound and / or a polymer thereof, a phenolic antioxidant, a thioether antioxidant, and other fillers shown in Table 1 are blended and uniformly mixed. did. The obtained mixture was melt-kneaded at a barrel temperature of 250 ° C. using a 44 mm-diameter twin-screw extruder, and the thread discharged from the die was cooled and cut to obtain molding pellets. Next, the pellets were dried at 130 ° C. for 5 hours, and then a test piece mold for physical properties was attached to a 5-ounce injection molding machine. The cylinder temperature was 260 ° C., the mold temperature was 40 ° C., the injection pressure was 700 kg / cm ² , and the cooling time was 20 minutes. A tensile test specimen (ASTM No. 4) was molded under molding conditions of 35 seconds and a total cycle of 35 seconds.
[0032]
Adhesion with silicone rubber was measured by placing a tensile test piece in the lower mold of a mold heated to 120 ° C, masking it with a Teflon sheet except for a part of 25 mm width x 15 mm length, and adding silicone prepared in Reference Example. Rubber was applied with. Next, the upper mold was closed, and pressure curing was performed at 120 ° C. × 10 minutes. The tensile test piece and the cured silicone rubber were pulled in the direction of 180 ° C., and the peelability and the peel strength were evaluated. Further, as a test for accelerating the adhesion of the PBT resin molded product and the silicone rubber under the use conditions and evaluating the decrease in the adhesion during storage, a tensile test piece was subjected to 23 ° C. pure water. After being immersed for 24 hours in the same manner, they were adhered by the same operation, and their peelability and peel strength were evaluated.
[0033]
In the test for hydrolysis resistance, the tensile strength of a test piece subjected to a wet heat treatment at 122 ° C. and a humidity of 100% RH for 60 hours was evaluated.
[0034]
Table 1 shows the results. It can be seen that the composition of the present invention exhibits good silicone rubber adhesion and hydrolysis resistance. When the component (B) is not contained, the adhesion to the silicone rubber is insufficient, and the mechanical strength of the PCT in the PBT with [COOH] = 35 equivalents / T is significantly reduced. When monobutyltin oxide, which is not a titanium compound, was used as the polymerization catalyst, the curing reaction of the silicone rubber was inhibited.
[0035]
[Table 1]

[0036]
[Ratio Comparative Examples 4-5]
In the same manner as in Example 1, the composition having the compounding ratio shown in Table 2 was evaluated for adhesion to silicone rubber. Table 2 shows the results.
[0037]
[Table 2]

[0038]
The compositions of the present invention exhibited good silicone rubber adhesion. On the other hand, when the blending amount of the thioether-based antioxidant was excessive, the influence of moisture absorption became large and the adhesiveness was reduced. When a phosphorus antioxidant was used, curing was inhibited.
[0039]
【The invention's effect】
According to the present invention, a polybutylene terephthalate resin composition in which the hydrolysis resistance of the polybutylene terephthalate resin is significantly improved, and the polybutylene terephthalate resin and the silicone rubber are adhered to each other with an adhesive strength sufficient for practical use It is possible to provide an integral molded body of the product and the silicone rubber, to enable the integral molded body to be securely and easily bonded in a short time, and to obtain such an integral molded article by injection molding. A polybutylene terephthalate resin composition can be provided.

Claims (2)

(A) per 100 parts by weight of polybutylene terephthalate obtained by using a titanium compound as a polymerization catalyst and having a terminal carboxyl group concentration of 15 equivalents / T or less,
(B) 0.01 to 3 parts by weight of a silicon-containing compound having at least one hydrogen atom directly bonded to a silicon atom in one molecule and / or a polymer thereof,
(C) a phenolic antioxidant 0.01 to 0.5 parts by weight,
(D) A polybutylene terephthalate resin composition comprising less than 0.01 part by weight of a thioether-based antioxidant, and a molded article comprising the composition is immersed in pure water at 23 ° C. for 24 hours. A resin composition having excellent adhesion to silicone rubber, having a peel strength of 10 N or more when the peel strength is measured as an integral molded article with silicone rubber after the above. The peel strength of the polybutylene terephthalate resin composition according to claim 1, which is 10 N or more when immersed in pure water at 23 ° C. for 24 hours and measured for peel strength as an integral molded body with silicone rubber. , Resin molded products with excellent adhesion to silicone rubber.