JP3985153B2 - Golf ball - Google Patents

Description

（式中、Ｒ⁴は、炭素数１〜２０の炭素原子を含む炭化水素基、ｎは２以上の整数である。）
【００２２】
ハロゲン含有化合物としては、ＡｌＸ_nＲ_3-n（ここで、Ｘはハロゲンを示し、Ｒは、炭素数が１〜２０の炭化水素残基であり、例えば、アルキル基、アリール基、アラルキル基であり、ｎは、１、１．５、２又は３を示す）で示されるアルミニウムハライド、Ｍｅ₃ＳｒＣｌ、Ｍｅ₂ＳｒＣｌ₂、ＭｅＳｒＨＣｌ₂、ＭｅＳｒＣｌ₃などのストロンチウムハライド、その他、四塩化ケイ素、四塩化スズ、四塩化チタンなどの金属ハライド等が用いられる。
【００２３】
ルイス塩基は、ランタン系列希土類元素化合物を錯化するのに用いることができ、例えば、アセチルアセトン、ケトンアルコールなどを挙げることができる。
【００２４】
本発明においては、特に、ランタン系列希土類元素化合物としてネオジウム化合物を用いたネオジウム系触媒の使用が、１，４−シス結合が高含量、１，２−ビニル結合が低含量のポリブタジエンゴムを優れた重合活性で得られるので好ましく、これらの希土類元素系触媒の具体例は、特開平１１−３５６３３号公報に記載されているものを好適に挙げることができる。
【００２５】
また、ランタン系列希土類元素化合物を用いた希土類元素系触媒の存在下でブタジエンを重合させる場合、シス含量及びＭｗ／Ｍｎを上記範囲とするために、ブタジエン／ランタン系列希土類元素化合物は、モル比で１，０００〜２００万、特には５，０００〜１００万とすることが好ましく、また、ＡｌＲ¹Ｒ²Ｒ³／ランタン系列希土類元素化合物は、モル比で１〜１，０００、特には３〜５００とすることが好ましい。更に、ハロゲン化合物／ランタン系列希土類元素化合物は、モル比で０．１〜３０、特に０．２〜１５であることが好ましい。ルイス塩基／ランタン系列希土類元素化合物は、モル比で０〜３０、特に１〜１０とすることが好ましい。重合にあたっては、溶媒を使用しても、溶媒を使用せずにバルク重合或いは気相重合してもよい。重合温度は、通常、−３０〜１５０℃、好ましくは１０〜１００℃である。
【００２６】
希土類元素系触媒の存在下でブタジエンを重合させる場合、溶媒を使用しても、溶媒を使用せずにバルク重合或いは気相重合してもよく、重合温度は通常−３０〜１５０℃、好ましくは１０〜１００℃とすることができる。
【００２７】
本発明の（Ａ）成分のポリブタジエンは、上記の希土類元素系触媒による重合に引き続き、ポリマーの活性末端に末端変性剤を反応させることにより得られるものであってもよい。
【００２８】
変性ポリブタジエンゴムは、上記の重合に引き続き、下記▲１▼〜▲７▼に記載した末端変性剤を使用することができる。
▲１▼ポリマーの活性末端にアルコキシシリル基を持つ化合物を反応させることにより得られる。アルコキシシリル基を持つ化合物としては、エポキシ基又はイソシアナート基を分子内に少なくとも１個有するアルコキシシラン化合物が好適に使用される。具体例としては、３−グリシジルオキシプロピルトリメトキシシラン、３−グリシジルオキシプロピルトリエトキシシラン、（３−グリシジルオキシプロピル）メチルジメトキシシラン、（３−グリシジルオキシプロピル）メチルジエトキシシラン、β−（３，４−エポキシシクロヘキシル）トリメトキシシラン、β−（３，４−エポキシシクロヘキシル）トリエトキシシラン、β−（３，４−エポキシシクロヘキシル）メチルジメトキシシラン、β−（３，４−エポキシシクロヘキシル）エチルジメトキシシラン、３−グリシジルオキシプロピルトリメトキシシランの縮合物、（３−グリシジルオキシプロピル）メチルジメトキシシランの縮合物などのエポキシ基含有アルコキシシラン；３−イソシアナートプロピルトリメトキシシラン、３−イソシアナートプロピルトリエトキシシラン、（３−イソシアナートプロピル）メチルジメトキシシラン、（３−イソシアナートプロピル）メチルジエトキシシラン、３−イソシアナートプロピルトリメトキシシランの縮合物、（３−イソシアナートプロピル）メチルジメトキシシランの縮合物などのイソシアナート基含有アルコキシシラン化合物が挙げられる。
【００２９】
また、上記アルコキシシリル基を持つ化合物を活性末端に反応させる際、反応を促進させるためにルイス酸を添加することもできる。ルイス酸が触媒としてカップリング反応を促進させ、変性ポリマーのコールドフローが改良され貯蔵安定性がよくなる。ルイス酸の具体例としては、ジアルキルスズジアルキルマレート、ジアルキルスズジカルボキシレート、アルミニウムトリアルコキシドなどが挙げられる。
【００３０】
▲２▼Ｒ⁵ _nＭ′Ｘ_4-n、Ｍ′Ｘ₄、Ｍ′Ｘ₃、Ｒ⁵ _nＭ′（−Ｒ⁶−ＣＯＯＲ⁷）_4-n又はＲ⁵ _nＭ′（−Ｒ⁶−ＣＯＲ⁷）_4-n（式中、Ｒ⁵及びＲ⁶は、同一でも異なっていてもよく、炭素数１〜２０の炭素原子を含む炭化水素基、Ｒ⁷は炭素数１〜２０の炭素原子を含む炭化水素基であり、側鎖にカルボニル基又はエステル基を含んでいてもよく、Ｍ′はスズ原子、ケイ素原子、ゲルマニウム原子又はリン原子、Ｘはハロゲン原子、ｎは０〜３の整数を示す）に対応するハロゲン化有機金属化合物、ハロゲン化金属化合物又は有機金属化合物、
▲３▼分子中に、Ｙ＝Ｃ＝Ｚ結合（式中、Ｙは炭素原子、酸素原子、チッ素原子又はイオウ原子、Ｚは酸素原子、チッ素原子又はイオウ原子を示す）を含有するヘテロクムレン化合物、
▲４▼分子中に下記結合を含有するヘテロ３員環化合物、
【化２】

（式中、Ｙは、酸素原子、チッ素原子又はイオウ原子を示す。）
▲５▼ハロゲン化イソシアノ化合物、
▲６▼Ｒ⁸−（ＣＯＯＨ）_m 、Ｒ⁹（ＣＯＸ）_m 、Ｒ¹⁰−（ＣＯＯ−Ｒ¹¹）_m 、Ｒ¹²−ＯＣＯＯ−Ｒ¹³、Ｒ¹⁴−（ＣＯＯＣＯ−Ｒ¹⁵）_m 、又は下記式で示されるカルボン酸、酸ハロゲン化物、エステル化合物、炭酸エステル化合物又は酸無水物、
【化３】

（式中、Ｒ⁸〜Ｒ¹⁶は、同一でも異なっていてもよく、炭素数１〜５０の炭素原子を含む炭化水素基、Ｘはハロゲン原子、ｍは１〜５の整数を示す。）
▲７▼Ｒ¹⁷ _l Ｍ″（ＯＣＯＲ¹⁸）_4-l 、Ｒ¹⁹ _lＭ″（ＯＣＯ−Ｒ²⁰−ＣＯＯＲ²¹）_4-l、又は下記式で示されるカルボン酸の金属塩
【化４】

（式中、Ｒ¹⁷〜Ｒ²³は、同一でも異なっていてもよく、炭素数１〜２０の炭素原子を含む炭化水素基、Ｍ″はスズ原子、ケイ素原子又はゲルマニウム原子、ｌは０〜３の整数を示す。）等を挙げることができる。
【００３１】
以上に示される末端変性剤の具体例及び反応させる方法は、例えば、特開平１１−３５６３３号公報，特開平７−２６８１３２号公報、特開２００２−２９３９９６号公報等に記載されているもの及び方法を挙げることができる。
【００３２】
本発明において、上記第１のポリブタジエンとしては、分子量分布Ｍｗ／Ｍｎ（Ｍｗ：重量平均分子量、Ｍｎ：数平均分子量）が、２．０以上、好ましくは２．２以上、更に好ましくは２．４以上、最も好ましくは２．６以上であり、上限としては３．４以下である。一方、第２のポリブタジエンとしては、分子量分布Ｍｗ／Ｍｎが、２．０以上、好ましくは２．２以上、更に好ましくは２．４以上、最も好ましくは２．６以上であり、上限としては６．０以下、好ましくは５．０以下、更に好ましくは４．０以下、最も好ましくは３．４以下であることが好ましい。Ｍｗ／Ｍｎが小さすぎると作業性が低下し、大きすぎると反発性が低下する場合がある。
【００３３】
本発明は、上記第１及び第２のポリブタジエンを主材としたゴム基材を用いるものであるが、この場合、この主材の第１ポリブタジエンはゴム基材中、５０％以上、好ましくは６０％以上、更に好ましくは７０％以上、最も好ましくは７５％以上であり、９５％以下、好ましくは９０％以下、より好ましくは８５％以下、更に好ましくは８０％以下である。一方、第２のポリブタジエンは、ゴム基材中、５％以上、好ましくは１０％以上、より好ましくは１５％以上、更に好ましくは２０％以上であり、また５０％以下、好ましくは４０％以下、より好ましくは３０％以下、更に好ましくは２０％以下である。第１のポリブタジエン量が多すぎると押し出し作業性が得られない。一方、第２のポリブタジエン量が多すぎると反発性が低下してしまう。
【００３４】
なお、ゴム基材には、上記ポリブタジエン以外に他のゴム成分を本発明の効果を損なわない範囲で配合し得る。上記ポリブタジエン以外のゴム成分としては、上記ポリブタジエン以外のポリブタジエン、例えばＶＩＩＩ族金属化合物触媒を用いて得られたポリブタジエン、その他のジエンゴム、例えばスチレンブタジエンゴム、天然ゴム、イソプレンゴム、エチレンプロピレンジエンゴム等が挙げられる。
【００３５】
次に、（Ｂ）成分の不飽和カルボン酸としては、アクリル酸、メタクリル酸、マレイン酸、フマル酸等が挙げられ、特にアクリル酸、メタクリル酸が好ましい。不飽和カルボン酸の金属塩としては、亜鉛塩、マグネシウム塩等が挙げられ、中でもアクリル酸亜鉛が好適に用いられる。
【００３６】
上記（Ｂ）成分の不飽和カルボン酸／塩の配合量は、上記（Ａ）成分のゴム基材１００部（重量部、以下同じ）に対し、１０部以上、より好ましくは１５部以上、更に好ましくは２０部以上であり、６０部以下、より好ましくは５０部以下、更に好ましくは４５部以下、最も好ましくは４０部以下とすることが好ましい。
【００３７】
（Ｃ）成分の有機硫黄化合物としては、例えば、チオフェノール、チオフトール、ハロゲン化チオフェノール又はそれらの金属塩が挙げられる。より具体的には、ペンタクロロチオフェノール、ペンタフルオロチオフェノール、ペンタブロモチオフェノール、パラクロロチオフェノール又はそれらの亜鉛塩、硫黄数が２〜４のジフェニルポリスルフィド、ジベンジルポリスルフィド、ジベンゾイルポリスルフィド、ジベンゾチアゾイルポリスルフィド、ジチオベンゾイルポリスルフィド、アルキルフェニルジスルフィド類、フラン環を有する硫黄化合物類、チオフェン環を有する硫黄化合物類が挙げられるが、特に、ペンタクロロチオフェノールの亜鉛塩、ジフェニルジスルフィドを好適に用いることができる。
【００３８】
その配合量は、（Ａ）成分のゴム基材１００部に対し、０．１部以上、より好ましくは０．２部以上、更に好ましくは０．４部以上、最も好ましくは０．７部以上で、５部以下、より好ましくは４部以下、更に好ましくは３部以下、最も好ましくは２部以下、特に好ましくは１．５部以下であることが必要である。その配合量が少なすぎると、反発性を向上させる効果がなく、多すぎると、硬度が軟らかくなりすぎ、十分な反発性が得られない。
【００３９】
（Ｄ）成分の無機充填剤としては、酸化亜鉛、硫酸バリウム、炭酸カルシウム等が挙げられ、その配合量は（Ａ）成分１００部に対し、５部以上、より好ましくは７部以上、更に好ましくは１０部以上、最も好ましくは１３部以上で、８０部以下、より好ましくは６５部以下、更に好ましくは５０部以下、最も好ましくは４０部以下とする。配合量が多すぎたり、少なすぎたりすると、適正な重量及び好適な反発性を得ることができない。
【００４０】
（Ｅ）成分の有機酸化物としては、公知のものを使用することができる。有機過酸化物として具体的には、ジクミルパーオキサイド、１，１−ビス（ｔ−ブチルパーオキシ）−３，５，５−トリメチルシクロヘキサン、α，α’−ビス（ｔ−ブチルパーオキシ）ジイソプロピルベンゼン等が挙げられる。これら有機過酸化物は市販品を用いることができ、例えば、パークミルＤ（日本油脂社製）、パーヘキサ３Ｍ（日本油脂社製）、Ｌｕｐｅｒｃｏ ２３１ＸＬ（アトケム社製）等が挙げられる。
【００４１】
ここで、有機過酸化物としては、単独でも２種以上を組み合わせてもよいが、特に反発性の点で２種以上を使用することが好ましい。この場合、１５５℃における半減期が一番短い有機過酸化物を（ａ）、１５５℃における半減期が一番長い有機過酸化物を（ｂ）とし、（ａ）の半減期をａ_t、（ｂ）の半減期をｂ_tとした場合、半減期の比ｂ_t／ａ_tが７以上、好ましくは８以上、より好ましくは９以上、更に好ましくは１０以上で、２０以下、より好ましくは１８以下、更に好ましくは１６以下、最も好ましくは１４以下である。２種以上の有機過酸化物を用いても、上記範囲を逸脱した場合、反発性、コンプレッション、耐久性に劣ってしまう。
【００４２】
この場合、（ａ）の１５５℃における半減期ａ_tは、５秒以上、より好ましくは１０秒以上、更に好ましくは１５秒以上で、１２０秒以下、より好ましくは９０秒以下、更に好ましくは６０秒以下であることが好ましく、（ｂ）の１５５℃における半減期ｂ_tは、３００秒以上、より好ましくは３６０秒以上、更に好ましくは４２０秒以上で、８００秒以下、より好ましくは７００秒以下、更に好ましくは６００秒以下であることが好ましい。この場合、上記（ａ）成分の有機過酸化物としては、１，１−ビス（ｔ−ブチルパーオキシ）−３，５，５−トリメチルシクロヘキサンが好ましく、（ｂ）成分の有機過酸化物としては、ジクミルパーオキサイドが好ましい。
【００４３】
また、上記有機過酸化物の総配合量は、上記（Ａ）成分のゴム基材１００部に対して０．１部以上、好ましくは０．２部以上、より好ましくは０．３部以上、更に好ましくは０．４部以上であり、３部以下、好ましくは２部以下、より好ましくは１部以下、更に好ましくは０．８部以下、特に好ましくは０．６部以下である。配合量が少なすぎると、架橋に要する時間が長くなり、生産性の低下が大きく、コンプレッションも大きく低下してしまう。配合量が多すぎると、反発性、耐久性が低下してしまう。
【００４４】
上記（ａ），（ｂ）の２種以上を使用する場合、（ａ）成分の添加量は、（Ａ）成分１００部に対し、０．０５部以上、より好ましくは０．０８部以上、更に好ましくは０．１部以上で、１．５部以下、より好ましくは１部以下、更に好ましくは０．７部以下、特に好ましくは０．４部以下であることが好ましく、（ｂ）成分の添加量は０．０５部以上、より好ましくは０．１５部以上、更に好ましくは０．２部以上で、１．５部以下、より好ましくは１部以下、更に好ましくは０．７部以下、特に好ましくは０．４部以下であることが好ましい。
【００４５】
なおまた、必要に応じ、老化防止剤を（Ａ）成分１００部に対し、０．０５部以上、より好ましくは０．１部以上、更に好ましくは０．２部以上で、３部以下、より好ましくは２部以下、更に好ましくは１部以下、最も好ましくは０．５部以下を配合することができる。なお、老化防止剤としては市販品を用いることができ、例えば、ノクラックＮＳ−６、同ＮＳ−３０（大内新興化学工業（株）製、ヨシノックス４２５（吉富製薬（株）製）等が挙げられる。
【００４６】
本発明の加硫成形物は、上述したゴム組成物を、公知のゴルフボール用ゴム組成物と同様の方法で加硫・硬化させることによって得ることができる。加硫条件は、例えば、加硫温度１００〜２００℃、加硫時間１０〜４０分にて実施することができる。
【００４７】
本発明において、上記加硫成形物の硬度は、後述する各種ゴルフボールの使用態様に応じて適宜調整することができ、特に制限されるものではなく、断面硬度は、中心から成形物表面までが平坦であっても中心と成形物表面までに硬度差があってもいずれの場合であってもよい。
【００４８】
また、本発明のゴルフボールは、後述する種々のゴルフボール態様を採ることができるが、特にゴルフボールがワンピースゴルフボール又はソリッドコア若しくはソリッドセンターを具備してなるゴルフボールのいずれかである場合、上記ワンピースソリッドゴルフボール、ソリッドコア又はソリッドセンターの９８０Ｎ（１００ｋｇ）荷重負荷時のたわみ量が、通常２．０ｍｍ以上、好ましくは２．５ｍｍ以上、更に好ましくは２．８ｍｍ以上、最も好ましくは３．２ｍｍ以上、上限としては６．０ｍｍ以下、好ましくは５．５ｍｍ以下、更に好ましくは５．０ｍｍ以下、最も好ましくは４．５ｍｍ以下であることが推奨され、変形量が少なすぎると、打感が悪くなると共に、特にドライバーなどのボールに大変形が生じるロングショット時にスピンが増えすぎて飛ばなくなり、軟らかすぎると、打感が鈍くなると共に、反発が十分でなくなり飛ばなくなる上、繰り返し打撃による割れ耐久性が悪くなる場合がある。
【００４９】
本発明のゴルフボールは、上記加硫成形物を構成要素として具備するもので、ボールの態様は、特に制限されるものではなく、上記加硫成形物がゴルフボールに直接適用されるワンピースゴルフボール、加硫成形物をソリッドコアとしかつその表面にカバーが形成されたツーピースソリッドゴルフボール、加硫成形物をソリッドコアとしかつその外側に２層以上のカバーが形成された３ピース以上のマルチピースソリッドゴルフボール、上記加硫成形物がセンターコアとして適用された糸巻きゴルフボール等の種々の態様を採ることができる。特に、加硫成形物の特性を活かし、製造時の押出し性、製品ゴルフボールに対する反発性付与の観点から、本発明の加硫成形物をソリッドコアとして使用するツーピースソリッドゴルフボール、マルチピースソリッドゴルフボールであることが好適な使用態様として推奨される。
【００５０】
本発明において、加硫成形物を上記ソリッドコアとする場合、ソリッドコアの直径は３０．０ｍｍ以上、好ましくは３２．０ｍｍ以上、更に好ましくは３５．０ｍｍ以上、最も好ましくは３７．０ｍｍ以上であり、上限として４１．０ｍｍ以下、好ましくは４０．５ｍｍ以下、更に好ましくは４０．０ｍｍ以下、最も好ましくは３９．５ｍｍ以下とすることが推奨され、特に、ツーピースソリッドゴルフボールのソリッドコアの直径は、３７．０ｍｍ以上、好ましくは３７．５ｍｍ以上、更に好ましくは３８．０ｍｍ以上、最も好ましくは３８．５ｍｍ以上であり、上限として４１．０ｍｍ以下、好ましくは４０．５ｍｍ以下、更に好ましくは４０．０ｍｍ以下、スリーピースソリッドゴルフボールのソリッドコアの直径は、３０．０ｍｍ以上、好ましくは３２．０ｍｍ以上、更に好ましくは３４．０ｍｍ以上、最も好ましくは３５．０ｍｍ以上であり、上限として４０．０ｍｍ以下、好ましくは３９．５ｍｍ以下、更に好ましくは３９．０ｍｍ以下とすることが推奨される。
【００５１】
上記ソリッドコアの比重は、通常０．９以上、好ましくは１．０以上、更に好ましくは１．１以上、上限として１．４以下、好ましくは１．３以下、更に好ましくは１．２以下であることが推奨される。
【００５２】
本発明のゴルフボールをツーピースソリッドゴルフボール、マルチピースソリッドゴルフボールとする場合には、上記加硫成形物をソリッドコアとして公知のカバー材、中間層材を射出成形又は加圧成形して形成することができる。
【００５３】
これらカバー材、中間層材の主材として、具体的には、熱可塑性又は熱硬化性のポリウレタン系エラストマー、ポリエステル系エラストマー、アイオノマー樹脂、ポリオレフィン系エラストマー又はこれらの混合物等を挙げることができる。これらは、１種を単独で又は２種以上を混合して用いることができ、特に、熱可塑性ポリウレタン系エラストマー、アイオノマー樹脂を好適に挙げることができる。
【００５４】
上記熱可塑性ポリウレタン系エラストマーとしては、市販品を用いることができ、例えばパンデックスＴ７２９８，同Ｔ７２９５，同Ｔ７８９０、同ＴＲ３０８０、同Ｔ８２９５、同Ｔ８２９０、同Ｔ８２６０（ＤＩＣ・バイエルポリマー社製）などのジイソシアネートが脂肪族又は芳香族であるもの等が挙げられる。また、アイオノマー樹脂の市販品としては、サーリン６３２０、同８１２０、同９９４５（米国デュポン社製）、ハイミラン１７０６、同１６０５、同１８５５、同１６０１、同１５５７（三井・デュポンポリケミカル社製）等を例示できる。
【００５５】
更に、上記カバー材又は中間層材の主材に対しては、任意成分として、上記以外の熱可塑性エラストマー等のポリマーを配合することができる。任意成分のポリマーとして、具体的には、ポリアミド系エラストマー、スチレン系ブロックエラストマー、水添ポリブタジエン、エチレン−酢酸ビニル（ＥＶＡ）共重合体等を配合し得る。
【００５６】
なお、本発明のツーピースソリッドゴルフボール、マルチピースソリッドゴルフボールは、公知の方法で製造することができ、特に制限されるものではないが、ツーピースやマルチピースソリッドゴルフボールとする場合には、上記加硫成形物をソリッドコアとして所定の射出成形用金型内に配備し、ツーピースソリッドゴルフボールの場合には上記カバー材を、マルチピースソリッドゴルフボールの場合には、順に上記中間層材、カバー材を所定の方法に従って射出する公知の方法を好適に採用できる。場合によっては、上記カバー材を加圧成形によって製造することもできる。
【００５７】
マルチピースソリッドゴルフボールの中間層の厚さは、０．５ｍｍ以上、好ましくは１．０ｍｍ以上、上限として３．０ｍｍ以下、好ましくは２．５ｍｍ以下、更に好ましくは２．０ｍｍ以下、最も好ましくは１．６ｍｍ以下であることが推奨される。
【００５８】
また、カバーの厚さは、ツーピースソリッドゴルフボール、マルチピースソリッドゴルフボールのいずれであっても０．７ｍｍ以上、好ましくは１．０ｍｍ以上、上限として３．０ｍｍ以下、好ましくは２．５ｍｍ以下、更に好ましくは２．０ｍｍ以下、最も好ましくは１．６ｍｍ以下であることが推奨される。
【００５９】
本発明のゴルフボールは、競技用としてゴルフ規則に従うものとすることができ、直径４２．６７ｍｍ以上、重量４５．９３ｇ以下に形成することができる。直径の上限として好ましくは４４．０ｍｍ以下、更に好ましくは４３．５ｍｍ以下、最も好ましくは４３．０ｍｍ以下、重量の下限として好ましくは４４．５ｇ以上、特に好ましくは４５．０ｇ以上、更に好ましくは４５．１ｇ以上、最も好ましくは４５．２ｇ以上であることが推奨される。
【００６０】
【発明の効果】
本発明のゴルフボールは、押し出し作業性が良好で、反発性に優れたものである。
【００６１】
【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。
【００６２】
［実施例１〜５、比較例１〜６］
表１に示すポリブタジエンを使用し、表２に示すゴム組成物を用いて、１５５℃で２０分間加硫することにより、ツーピースゴルフボールのコアを作成した。この場合、コアの外径は３８．９ｍｍ、コアの重量は３６．０ｇであった。このコアにハイミラン１６０１とハイミラン１５５７との重量比１：１の混合物からなるカバー材を射出して、ディンプルを形成し、その表面をペイントで被覆し、外径４２．７ｍｍ、重量４５．３ｇのツーピースソリッドゴルフボールを得た。上記コアの１００ｋｇ（９８０Ｎ）荷重たわみ量、反発性及びゴルフボールの飛び性能を下記方法により評価した。結果を表２に示す。
【００６３】
［実施例６、比較例７，８］
表３に示すゴム組成物を用いて、１５５℃で２０分間加硫することにより、スリーピースゴルフボールのコアを作成した。この場合、コアの外径は３６．４ｍｍ、重量は２９．７ｇであった。このコアに、サーリン９９４５とハイミラン１６０５とダイナロン６１００Ｐとの重量比３５：３５：３０の混合物を射出成形して、厚さ１．６５ｍｍの中間層を形成した。
更に、パンデックスＴ８２６０とパンデックスＴ８２９５との重量比１：１の混合物からなるカバー材を射出して、外径４２．７ｍｍ、重量４５．５ｇのスリーピースソリッドゴルフボールを得た。
上記コアの１００ｋｇ（９８０Ｎ）荷重たわみ量、反発性及びゴルフボールの飛び性能を下記方法により評価した。結果を表３に示す。
【００６４】
［実施例７、比較例９，１０］
表４に示すゴム組成物を用いて、１７０℃で３０分間加硫することにより、外径４２．７ｍｍ、重量４５．３ｇのワンピースゴルフボールを製造し、その性能を評価した。結果を表４に示す。
１００ｋｇ荷重たわみ量
得られたソリッドコア又はワンピースゴルフボールに対し、１００ｋｇ（９８０Ｎ）荷重負荷時の変形量（ｍｍ）を計測した。
反発性
公認機関ＵＳＧＡと同タイプの初速度計で初速度を測定し、実施例１〜５、比較例１〜６については比較例１を基準にし、実施例６、比較例７，８については比較例８を基準にし、実施例７、比較例９，１０については比較例１０を基準にしたときの初速度の差を表した。
飛び性能
打撃マシンにてドライバー（Ｗ＃１，Ｔｏｕｒ Ｓｔａｇｅ Ｘ５００，ロフト９°、シャフトＸ，ブリヂストンスポーツ社製）にて、ヘッドスピード４５ｍ／ｓ（ＨＳ４５）で打撃したときの飛び性能を測定した。
押出し作業性の評価
押出し後のスラグ肌及びスラグ形状について下記基準で評価した。
４ スラグ肌がきれいで非常に良好
３ スラグ肌にややざらつきがあるが良好
２ スラグ肌に毛羽立ちがあるが押し出し可能
１ スラグの形状不良が起こり、所定量の押し出しが困難
【００６５】
【表１】

【００６６】
【表２】

（注）パーヘキサ３Ｍ−４０：４０％希釈品（実質添加量は括弧内）
【００６７】
比較例１：Ｎｉ系触媒を用いて重合したＢＲ単体のため、反発性は良好であるが、作業性が非常に悪い
比較例２：低反発のＮｉ系触媒を用いて重合したＢＲの添加量が多いため、作業性は良好であるが、反発性が低い
比較例３：低反発のＮｉ系触媒を用いて重合したＢＲのため、反発性が低い
比較例４：低反発のＮｉ系触媒を用いて重合したＢＲの添加量が多いため、反発性が低い
比較例５：低反発のＮｉ系触媒を用いて重合したＢＲを添加しているため、反発性が低い
比較例６：ペンタクロロチオフェノールの亜鉛塩を無添加のため、反発性低下
【００６８】
【表３】

【００６９】
比較例７：Ｎｉ系触媒を用いて重合したＢＲ単体のため、反発性は良好であるが、作業性が非常に悪い
比較例８：低反発のＮｉ系触媒を用いて重合したＢＲのため、反発性が低い
【００７０】
【表４】

【００７１】
比較例９：Ｎｉ系触媒を用いて重合したＢＲ単体のため、反発性は良好であるが、作業性が非常に悪い
比較例１０：低反発のＮｉ系触媒を用いて重合したＢＲのため、反発性が低い[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a golf ball that has good extrusion workability, excellent resilience, and good flying performance by improving a rubber composition that forms a solid core or the like.
[0002]
[Prior art]
Conventionally, in order to impart excellent resilience to golf balls, various improvements have been made in the composition of polybutadiene used as a rubber base material.
[0003]
For example, JP-A-62-89750 discloses a polybutadiene having a Mooney viscosity of 70 to 100 synthesized using a Ni or Co catalyst as a rubber substrate and a Mooney viscosity of 30 to 90 synthesized using a lanthanum catalyst. A rubber composition for solid golf balls has been proposed which is blended with polybutadiene synthesized with a polybutadiene or a Ni, Co catalyst and having a Mooney viscosity of 20 to 50.
However, regarding the above proposal, further improvement in resilience is required.
[0004]
JP-A-2-268778 proposes a golf ball formed by blending a polybutadiene having a Mooney viscosity of less than 50 synthesized with a Group VIII catalyst and a polybutadiene having a Mooney viscosity of less than 50 synthesized using a lanthanide catalyst. However, the resilience of the resulting golf ball is poor.
[0005]
Further, JP-A-11-70187 discloses a multi-piece solid golf ball in which an intermediate layer is formed of polybutadiene having a low Mooney viscosity, and JP-A-11-319148 uses a Ni, Co catalyst. A solid golf ball formed of a rubber composition comprising a polybutadiene having a Mooney viscosity of 50 to 69 and a polybutadiene having a Mooney viscosity of 20 to 90 synthesized using a lanthanoid catalyst, Japanese Patent Application Laid-Open No. 11-164912 A solid golf ball formed of a rubber composition having a 1,2-vinyl bond of 2.0% or less and a ratio Mw / Mn of weight average molecular weight to number average molecular weight of 3.5 or less, Japanese Patent No. 275356 discloses a golf ball formed of a rubber composition containing a polybutadiene having a high Mooney viscosity. Japanese Patent No. 151985 proposes a golf ball formed of a rubber composition formed by blending a polybutadiene having a high number average molecular weight and a polybutadiene having a low number average molecular weight. I can't say that.
[0006]
JP-A-61-71070 describes the use of two kinds of organic peroxides, and JP-A-62-112574 describes the use of a small amount of organic peroxides. However, there is a problem that the resilience is not sufficient, the crosslinking time is delayed, and the productivity is greatly reduced.
Further, Japanese Patent Laid-Open Nos. 2001-149505 to 2001-149507 have proposals, but there is still room for improvement in terms of resilience.
[0007]
[Patent Document 1]
JP 58-225138 A [Patent Document 2]
JP-A-62-89750 [Patent Document 3]
JP-A-62-112574 [Patent Document 4]
JP-A 63-275356 [Patent Document 5]
Japanese Patent Laid-Open No. 3-151985 [Patent Document 6]
JP-A-2-268778 [Patent Document 7]
Japanese Patent Laid-Open No. 11-70187 [Patent Document 8]
Japanese Patent Laid-Open No. 11-164912 [Patent Document 9]
JP-A-11-319148 [Patent Document 10]
JP-A-61-71070 [Patent Document 11]
JP 2001-149505 A [Patent Document 12]
JP 2001-149506 A [Patent Document 13]
Japanese Patent Laid-Open No. 2001-149507
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and has good extrusion workability, shortens the vulcanization time, improves productivity, has a good hit feeling, has excellent resilience, and has a good jump. An object of the present invention is to provide a golf ball that provides performance.
[0009]
Means for Solving the Problem and Embodiment of the Invention
As a result of intensive studies to achieve the above object, the present inventor is polybutadiene containing 60% by weight or more of cis-1,4-bond and synthesized using a rare earth element-based catalyst, Using a rubber base material having a viscosity (ML _{1 + 4} (100 ° C.)) of 50 or more and 45 or less in a specific ratio, the unsaturated carboxylic acid and 100 parts by weight of the rubber base material / Or 10 to 60 parts by weight of the metal salt, 0.1 to 5 parts by weight of organic sulfur compound, 5 to 80 parts by weight of inorganic filler, and 0.1 to 3 parts by weight of organic peroxide In this case, preferably, two or more kinds of organic peroxides, of which the organic peroxide having the shortest half-life at 155 ° C. is (a) and the longest organic peroxide is (b), the half-life of (a) a _t, when the b _t half-life of (b), half It is a vulcanized molded article of the components of the rubber composition ratio b _t / a _t the reduction period was formulated to be 7 to 20, in particular, by a solid core of solid golf balls, manufacturability It was found that a golf ball excellent in repulsion and good in resilience can be obtained.
[0010]
That is, by blending polybutadiene synthesized using the high Mooney viscosity rare earth metal catalyst and polybutadiene synthesized using the low Mooney viscosity rare earth metal catalyst, the rubber composition has good resilience and extrusion workability. In the past, when the amount of the organic peroxide was reduced, the vulcanization time was prolonged, the productivity was lowered, and the rebound was not sufficient. Using polybutadiene synthesized using a catalyst and containing a small amount of two or more organic peroxides with greatly different half-lives, workability can be improved, vulcanization time can be shortened, and productivity can be improved. Furthermore, it has been found that further improvement in resilience can be achieved, and has led to the present invention.
[0011]
Accordingly, the present invention provides the following golf balls.
Claim 1:
It contains 60% by weight or more of cis-1,4-bond, Mooney viscosity (ML _{1 + 4} (100 ° C.)) is 50 or more , and molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight). The first polybutadiene synthesized using a rare earth element catalyst of 2.0 to 3.4 is contained in an amount of 50 to 95% by weight, cis-1,4-bond is contained in an amount of 60% by weight or more, and Mooney viscosity (ML _{1 +4} (100 ° C.)) with respect to 100 parts by weight of the rubber base material containing 5 to 50% by weight of the second polybutadiene synthesized using a rare earth element-based catalyst having 45 or less, unsaturated carboxylic acid and / or Rubber composition containing 10 to 60 parts by weight of the metal salt, 0.1 to 5 parts by weight of organic sulfur compound, 5 to 80 parts by weight of inorganic filler, and 0.1 to 3 parts by weight of organic peroxide Characterized by comprising a vulcanized molded product of ball.
Claim 2:
The golf ball according to claim 1, wherein the first polybutadiene is a modified polybutadiene rubber synthesized by using an Nd-based catalyst and subsequently obtained by reacting with a terminal modifier.
Claim 3:
The golf ball according to claim 1 , wherein the second polybutadiene has a molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of 2.0 to 6.0.
Claim 4:
The golf ball according to claim 1 , wherein the second polybutadiene is a modified polybutadiene rubber obtained by synthesis using an Nd-based catalyst and subsequently reacting with a terminal modifier.
Claim 5:
The golf ball according to claim 1, wherein the Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the second polybutadiene rubber is 40 or less.
Claim 6:
Including two or more organic peroxides, of which the organic peroxide having the shortest half-life at 155 ° C. is (a), the longest organic peroxide is (b), and the half-life of (a) is a _t, golf ball of any one of claims 1 to 5 the half-life case of a b _t, the ratio b _t / a _t half-life of 7 to 20 or less (b).
Claim 7:
The golf ball according to claim 1 , wherein the total content of the organic peroxide is 0.1 to 0.8 parts by weight with respect to 100 parts by weight of the rubber base material.
[0012]
Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention is
(A) First and second polybutadienes containing 60% by weight or more of cis-1,4-bonds and having different Mooney viscosities (ML _{1 + 4} (100 ° C.)) synthesized using a rare earth element-based catalyst A rubber base material mainly composed of
(B) an unsaturated carboxylic acid and / or a metal salt thereof,
(C) an organic sulfur compound,
(D) Inorganic filler (E) A vulcanized molded product of a rubber composition containing an organic peroxide is used as a constituent element.
[0013]
Here, first, the first and second polybutadienes of the component (A) both have a cis-1,4-bond of 60% (weight%, the same shall apply hereinafter) or more, preferably 80% or more, more preferably It is necessary to have 90% or more, most preferably 95% or more. If there are too few cis-1,4-bonds, the resilience will decrease.
Further, the content of 1,2-vinyl bonds is preferably 2% or less, more preferably 1.7% or less, and still more preferably 1.5% or less. If the content of 1,2-vinyl bond is too large, the resilience may be lowered.
[0014]
The first polybutadiene has a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 50 or more, preferably 51 or more, more preferably 52 or more, most preferably 54 or more, and an upper limit of 140 or less, preferably 120 or less. More preferably, it is 100 or less, and most preferably 80 or less.
On the other hand, the second polybutadiene has a Mooney viscosity of 45 or less, preferably 40 or less, more preferably 38 or less, still more preferably 36 or less, preferably 10 or more, more preferably 15 or more, still more preferably 20 or more, particularly Preferably it is 25 or more.
[0015]
The Mooney viscosity referred to in the present invention is an industrial viscosity index (JIS K6300) measured with a Mooney viscometer, which is a kind of rotational plasticity meter, and ML _{1 + 4} ( 100 ° C.). Further, M is Mooney viscosity, L is a large rotor (L type), 1 + 4 is a preheating time of 1 minute, and a rotor rotation time is 4 minutes, which is measured at 100 ° C.
[0016]
The polybutadiene used in the present invention needs to be synthesized with a rare earth element-based catalyst, and a known one can be used as the rare earth element-based catalyst.
[0017]
For example, a lanthanum series rare earth element compound, an organoaluminum compound, an alumoxane, a halogen-containing compound, and a catalyst comprising a combination of Lewis bases as required can be mentioned.
[0018]
Examples of the lanthanum series rare earth element compounds include metal halides having an atomic number of 57 to 71, carboxylates, alcoholates, thioalcolates, and amides.
[0019]
Examples of the organoaluminum compound include AlR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ may be the same or different, and each represents hydrogen or a hydrocarbon residue having 1 to 8 carbon atoms. Can be used.
[0020]
Preferred examples of the alumoxane include compounds having a structure represented by the following formula (I) or the following formula (II). In this case, Fine Chemicals, 23, (9), 5 (1994), J. Am. Am. Chem. Soc. 115, 4971 (1993); Am. Chem. Soc. 117, 6465 (1995).
[0021]
[Chemical 1]

(In the formula, R ⁴ is a hydrocarbon group containing a carbon atom having 1 to 20 carbon atoms, and n is an integer of 2 or more.)
[0022]
Examples of the halogen-containing compound include AlX _n R _3-n (where X represents halogen, R is a hydrocarbon residue having 1 to 20 carbon atoms, such as an alkyl group, an aryl group, and an aralkyl group. And n represents 1, 1.5, 2 or 3), strontium halides such as Me ₃ SrCl, Me ₂ SrCl ₂ , MeSrHCl ₂ and MeSrCl ₃ , and others, silicon tetrachloride, tetrachloride Metal halides such as tin and titanium tetrachloride are used.
[0023]
The Lewis base can be used to complex a lanthanum series rare earth element compound, and examples thereof include acetylacetone and ketone alcohol.
[0024]
In the present invention, in particular, the use of a neodymium-based catalyst using a neodymium compound as a lanthanum series rare earth element compound is excellent in polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds. Since it is obtained by polymerization activity, it is preferable, and specific examples of these rare earth element-based catalysts include those described in JP-A No. 11-35633.
[0025]
Further, when butadiene is polymerized in the presence of a rare earth element-based catalyst using a lanthanum series rare earth element compound, in order to make the cis content and Mw / Mn within the above ranges, the butadiene / lanthanum series rare earth element compound has a molar ratio. It is preferably 1,000 to 2,000,000, particularly 5,000 to 1,000,000, and the AlR ¹ R ² R ³ / lanthanum series rare earth element compound has a molar ratio of 1 to 1,000, particularly 3 to 3. 500 is preferable. Furthermore, the molar ratio of the halogen compound / lanthanum series rare earth element compound is preferably 0.1 to 30, and particularly preferably 0.2 to 15. The Lewis base / lanthanum series rare earth element compound is preferably in a molar ratio of 0 to 30, particularly 1 to 10. In the polymerization, a solvent may be used, or bulk polymerization or gas phase polymerization may be performed without using a solvent. The polymerization temperature is usually −30 to 150 ° C., preferably 10 to 100 ° C.
[0026]
When butadiene is polymerized in the presence of a rare earth element-based catalyst, a solvent may be used, or bulk polymerization or gas phase polymerization may be performed without using a solvent, and the polymerization temperature is usually −30 to 150 ° C., preferably It can be 10-100 degreeC.
[0027]
The polybutadiene as the component (A) of the present invention may be obtained by reacting a terminal modifier with the active terminal of the polymer subsequent to the polymerization using the rare earth element-based catalyst.
[0028]
For the modified polybutadiene rubber, the terminal modifiers described in the following (1) to (7) can be used following the above polymerization.
(1) Obtained by reacting a compound having an alkoxysilyl group at the active terminal of the polymer. As the compound having an alkoxysilyl group, an alkoxysilane compound having at least one epoxy group or isocyanate group in the molecule is preferably used. Specific examples include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, (3-glycidyloxypropyl) methyldimethoxysilane, (3-glycidyloxypropyl) methyldiethoxysilane, β- (3 , 4-epoxycyclohexyl) trimethoxysilane, β- (3,4-epoxycyclohexyl) triethoxysilane, β- (3,4-epoxycyclohexyl) methyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyldimethoxy Epoxy group-containing alkoxysilanes such as silane, 3-glycidyloxypropyltrimethoxysilane condensate, (3-glycidyloxypropyl) methyldimethoxysilane condensate; 3-isocyanatopropyltrimethoxysilane, 3 Isocyanatopropyltriethoxysilane, (3-isocyanatopropyl) methyldimethoxysilane, (3-isocyanatopropyl) methyldiethoxysilane, condensate of 3-isocyanatopropyltrimethoxysilane, (3-isocyanatopropyl) methyl Examples include isocyanate group-containing alkoxysilane compounds such as dimethoxysilane condensates.
[0029]
In addition, when the compound having an alkoxysilyl group is reacted with the active terminal, a Lewis acid can be added to accelerate the reaction. The Lewis acid acts as a catalyst to promote the coupling reaction, improving the cold flow of the modified polymer and improving the storage stability. Specific examples of the Lewis acid include dialkyl tin dialkyl malate, dialkyl tin dicarboxylate, aluminum trialkoxide and the like.
[0030]
(2) R ⁵ _n M′X _4-n , M′X ₄ , M′X ₃ , R ⁵ _n M ′ (—R ⁶ —COOR ⁷ ) _4-n or R ⁵ _n M ′ (—R ⁶ — COR ⁷ ) _4-n (wherein R ⁵ and R ⁶ may be the same or different and each represents a hydrocarbon group containing 1 to 20 carbon atoms, R ⁷ is a carbon atom having 1 to 20 carbon atoms) Which may contain a carbonyl group or an ester group in the side chain, M ′ is a tin atom, silicon atom, germanium atom or phosphorus atom, X is a halogen atom, and n is an integer of 0 to 3 A halogenated organometallic compound, a halogenated metal compound or an organometallic compound,
(3) Heterocumlene containing Y = C = Z bond in the molecule (wherein Y represents a carbon atom, oxygen atom, nitrogen atom or sulfur atom, and Z represents an oxygen atom, nitrogen atom or sulfur atom) Compound,
(4) Hetero 3-membered ring compound containing the following bond in the molecule,
[Chemical 2]

(In the formula, Y represents an oxygen atom, a nitrogen atom or a sulfur atom.)
(5) Halogenated isocyano compound,
^{▲ 6 ▼ R 8 - (COOH} ) m, R 9 (COX) m, R 10 - (COO-R 11) m, R 12 -OCOO-R 13, R 14 - (COOCO-R 15) m, or the following Carboxylic acid, acid halide, ester compound, carbonate compound or acid anhydride represented by the formula:
[Chemical 3]

(In formula, R < ⁸ > -R < ¹⁶ > may be same or different, The hydrocarbon group containing a C1-C50 carbon atom, X is a halogen atom, m shows the integer of 1-5.)
(7) R ¹⁷ _l M ″ (OCOR ¹⁸ ) _4-l , R ¹⁹ _l M ″ (OCO-R ²⁰ -COOR ²¹ ) _4-l or a metal salt of a carboxylic acid represented by the following formula:

(Wherein R ^{17 to} R ²³ may be the same or different, a hydrocarbon group containing a carbon atom having 1 to 20 carbon atoms, M ″ is a tin atom, a silicon atom or a germanium atom, and l is 0 to 3) And the like.) And the like.
[0031]
Specific examples of terminal modifiers shown above and the method of reacting them are described in, for example, JP-A-11-35633, JP-A-7-268132, JP-A-2002-293996, and the like. Can be mentioned.
[0032]
In the present invention, the first polybutadiene has a molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of 2.0 or more, preferably 2.2 or more, more preferably 2.4. As described above, most preferably 2.6 or more, and the upper limit is 3.4 or less. On the other hand, as the second polybutadiene, the molecular weight distribution Mw / Mn is 2.0 or more, preferably 2.2 or more, more preferably 2.4 or more, most preferably 2.6 or more, and the upper limit is 6 0.0 or less, preferably 5.0 or less, more preferably 4.0 or less, and most preferably 3.4 or less. When Mw / Mn is too small, workability may be reduced, and when Mw / Mn is too large, resilience may be reduced.
[0033]
The present invention uses a rubber base material mainly composed of the first and second polybutadienes. In this case, the first polybutadiene of the main material is 50% or more, preferably 60% in the rubber base material. % Or more, more preferably 70% or more, most preferably 75% or more, 95% or less, preferably 90% or less, more preferably 85% or less, and further preferably 80% or less. On the other hand, the second polybutadiene is 5% or more, preferably 10% or more, more preferably 15% or more, still more preferably 20% or more, and 50% or less, preferably 40% or less, in the rubber substrate. More preferably, it is 30% or less, More preferably, it is 20% or less. If the amount of the first polybutadiene is too large, the extrusion workability cannot be obtained. On the other hand, if the amount of the second polybutadiene is too large, the resilience is lowered.
[0034]
In addition, the rubber base material can be blended with other rubber components in addition to the polybutadiene as long as the effects of the present invention are not impaired. Examples of rubber components other than the above polybutadiene include polybutadienes other than the above polybutadiene, such as polybutadiene obtained using a Group VIII metal compound catalyst, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, ethylene propylene diene rubber, and the like. Can be mentioned.
[0035]
Next, as unsaturated carboxylic acid of (B) component, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. are mentioned, Acrylic acid and methacrylic acid are especially preferable. Examples of the metal salt of the unsaturated carboxylic acid include a zinc salt and a magnesium salt. Among them, zinc acrylate is preferably used.
[0036]
The amount of the unsaturated carboxylic acid / salt of the component (B) is 10 parts or more, more preferably 15 parts or more, and more preferably 15 parts or more, based on 100 parts (parts by weight) of the rubber base material of the component (A) The amount is preferably 20 parts or more, 60 parts or less, more preferably 50 parts or less, still more preferably 45 parts or less, and most preferably 40 parts or less.
[0037]
(C) As an organic sulfur compound of a component, thiophenol, thiofitol, halogenated thiophenol, or those metal salts are mentioned, for example. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol or zinc salts thereof, diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzo Examples include thiazoyl polysulfide, dithiobenzoyl polysulfide, alkylphenyl disulfides, sulfur compounds having a furan ring, and sulfur compounds having a thiophene ring. Can do.
[0038]
The blending amount is 0.1 part or more, more preferably 0.2 part or more, still more preferably 0.4 part or more, and most preferably 0.7 part or more with respect to 100 parts of the rubber base material of component (A). And 5 parts or less, more preferably 4 parts or less, still more preferably 3 parts or less, most preferably 2 parts or less, and particularly preferably 1.5 parts or less. If the blending amount is too small, there is no effect of improving the resilience, and if it is too much, the hardness becomes too soft and sufficient resilience cannot be obtained.
[0039]
(D) As an inorganic filler of a component, zinc oxide, barium sulfate, calcium carbonate, etc. are mentioned, The compounding quantity is 5 parts or more with respect to 100 parts of (A) component, More preferably, 7 parts or more, More preferably Is 10 parts or more, most preferably 13 parts or more, 80 parts or less, more preferably 65 parts or less, still more preferably 50 parts or less, and most preferably 40 parts or less. If the amount is too large or too small, an appropriate weight and suitable resilience cannot be obtained.
[0040]
(E) As an organic oxide of a component, a well-known thing can be used. Specific examples of the organic peroxide include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, α, α′-bis (t-butylperoxy). Examples include diisopropylbenzene. Commercially available products can be used as these organic peroxides, and examples include Park Mill D (manufactured by NOF Corporation), Perhexa 3M (manufactured by NOF Corporation), Luperco 231XL (manufactured by Atchem Corporation) and the like.
[0041]
Here, the organic peroxides may be used alone or in combination of two or more, but it is particularly preferable to use two or more in view of resilience. In this case, the half-life shortest organic peroxide at 155 ° C. (a), the half-life is longest organic peroxide and (b) at 155 ° C., the half-life of (a) a _t, If the half-life of (b) was b _t, the ratio b _t / a _t half-life of at least 7, preferably 8 or more, more preferably 9 or more, more preferably 10 or more, 20 or less, more preferably 18 or less, more preferably 16 or less, and most preferably 14 or less. Even when two or more organic peroxides are used, if they deviate from the above range, the resilience, compression, and durability are poor.
[0042]
In this case, the half-life a _t at 155 ° C. of (a) is 5 seconds or more, more preferably 10 seconds or more, more preferably at least 15 seconds, 120 seconds or less, more preferably 90 seconds or less, more preferably 60 The half-life b _t at 155 ° C. of (b) is preferably 300 seconds or longer, more preferably 360 seconds or longer, still more preferably 420 seconds or longer, 800 seconds or shorter, more preferably 700 seconds or shorter. More preferably, it is 600 seconds or less. In this case, the organic peroxide as the component (a) is preferably 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, and the organic peroxide as the component (b) Is preferably dicumyl peroxide.
[0043]
The total amount of the organic peroxide is 0.1 parts or more, preferably 0.2 parts or more, more preferably 0.3 parts or more, relative to 100 parts of the rubber base material of the component (A). More preferably, it is 0.4 parts or more, 3 parts or less, preferably 2 parts or less, more preferably 1 part or less, still more preferably 0.8 parts or less, and particularly preferably 0.6 parts or less. If the blending amount is too small, the time required for crosslinking becomes long, the productivity is greatly reduced, and the compression is also greatly reduced. If the amount is too large, the resilience and durability will decrease.
[0044]
When using 2 or more types of said (a) and (b), the addition amount of (a) component is 0.05 parts or more with respect to 100 parts of (A) component, More preferably, 0.08 parts or more, More preferably, it is 0.1 parts or more, 1.5 parts or less, more preferably 1 part or less, further preferably 0.7 parts or less, particularly preferably 0.4 parts or less, and component (b) Is added in an amount of 0.05 part or more, more preferably 0.15 part or more, further preferably 0.2 part or more, 1.5 part or less, more preferably 1 part or less, still more preferably 0.7 part or less. Particularly preferably, it is preferably 0.4 parts or less.
[0045]
In addition, if necessary, the anti-aging agent is 0.05 parts or more, more preferably 0.1 parts or more, still more preferably 0.2 parts or more, and 3 parts or less, based on 100 parts of the component (A). Preferably 2 parts or less, more preferably 1 part or less, and most preferably 0.5 parts or less can be blended. In addition, a commercial item can be used as an anti-aging agent, for example, Nocrack NS-6, NS-30 (Ouchi Shinsei Chemical Co., Ltd. product, Yoshinox 425 (Yoshitomi Pharmaceutical Co., Ltd. product)) etc. are mentioned. It is done.
[0046]
The vulcanized molded product of the present invention can be obtained by vulcanizing and curing the rubber composition described above in the same manner as a known golf ball rubber composition. The vulcanization conditions can be carried out, for example, at a vulcanization temperature of 100 to 200 ° C. and a vulcanization time of 10 to 40 minutes.
[0047]
In the present invention, the hardness of the vulcanized molded product can be appropriately adjusted according to the use mode of various golf balls described later, and is not particularly limited, and the cross-sectional hardness ranges from the center to the molded product surface. Even if it is flat, there may be a difference in hardness between the center and the surface of the molded product.
[0048]
In addition, the golf ball of the present invention can take various golf ball modes described later, particularly when the golf ball is a one-piece golf ball or a golf ball having a solid core or a solid center. The deflection amount of the one-piece solid golf ball, solid core or solid center when a load of 980 N (100 kg) is applied is usually 2.0 mm or more, preferably 2.5 mm or more, more preferably 2.8 mm or more, and most preferably 3. 2 mm or more, and the upper limit is 6.0 mm or less, preferably 5.5 mm or less, more preferably 5.0 mm or less, and most preferably 4.5 mm or less. Long shots that worsen and cause large deformations, especially on balls such as drivers The spin is no longer fly by too many, and too soft, with the feel is dull, on the rebound will not fly no longer enough, there is a durability to cracking with repeated impact is poor.
[0049]
The golf ball of the present invention comprises the vulcanized molded product as a constituent element, and the mode of the ball is not particularly limited, and the one-piece golf ball in which the vulcanized molded product is directly applied to the golf ball. A two-piece solid golf ball having a vulcanized molding as a solid core and a cover formed on the surface thereof, and a three-piece or more multi-piece having a vulcanized molding as a solid core and having two or more layers on the outside Various modes such as a solid golf ball and a wound golf ball in which the vulcanized molded product is applied as a center core can be adopted. In particular, two-piece solid golf balls and multi-piece solid golfs that use the vulcanized molding of the present invention as a solid core from the viewpoint of imparting resilience to the product golf ball by utilizing the characteristics of the vulcanized molded product. A ball is recommended as a preferred mode of use.
[0050]
In the present invention, when the vulcanized product is the above-mentioned solid core, the diameter of the solid core is 30.0 mm or more, preferably 32.0 mm or more, more preferably 35.0 mm or more, and most preferably 37.0 mm or more. The upper limit is 41.0 mm or less, preferably 40.5 mm or less, more preferably 40.0 mm or less, and most preferably 39.5 mm or less. In particular, the diameter of the solid core of the two-piece solid golf ball is 37.0 mm or more, preferably 37.5 mm or more, more preferably 38.0 mm or more, most preferably 38.5 mm or more, and the upper limit is 41.0 mm or less, preferably 40.5 mm or less, more preferably 40.0 mm. The three-piece solid golf ball has a solid core diameter of 30.0 mm or less. , Preferably 32.0 mm or more, more preferably 34.0 mm or more, most preferably 35.0 mm or more, and the upper limit is 40.0 mm or less, preferably 39.5 mm or less, more preferably 39.0 mm or less. Is recommended.
[0051]
The specific gravity of the solid core is usually 0.9 or more, preferably 1.0 or more, more preferably 1.1 or more, and the upper limit is 1.4 or less, preferably 1.3 or less, more preferably 1.2 or less. It is recommended that there be.
[0052]
When the golf ball of the present invention is a two-piece solid golf ball or a multi-piece solid golf ball, a known cover material and intermediate layer material are formed by injection molding or pressure molding using the vulcanized molded product as a solid core. be able to.
[0053]
Specific examples of the cover material and the main material of the intermediate layer material include thermoplastic or thermosetting polyurethane elastomers, polyester elastomers, ionomer resins, polyolefin elastomers, and mixtures thereof. These can be used individually by 1 type or in mixture of 2 or more types, Especially, a thermoplastic polyurethane-type elastomer and an ionomer resin can be mentioned suitably.
[0054]
Commercially available products can be used as the thermoplastic polyurethane elastomer, for example, diisocyanates such as Pandex T7298, T7295, T7890, TR3080, T8295, T8290, T8290 (DIC Bayer Polymer). In which is aliphatic or aromatic. As commercially available products of ionomer resins, Surlyn 6320, 8120, 9945 (made by DuPont, USA), Himiran 1706, 1605, 1855, 1601, 1557 (made by Mitsui, DuPont Polychemical), etc. It can be illustrated.
[0055]
Furthermore, a polymer such as a thermoplastic elastomer other than the above can be blended as an optional component in the main material of the cover material or intermediate layer material. Specifically, as an optional polymer, a polyamide-based elastomer, a styrene-based block elastomer, a hydrogenated polybutadiene, an ethylene-vinyl acetate (EVA) copolymer, or the like can be blended.
[0056]
The two-piece solid golf ball and the multi-piece solid golf ball of the present invention can be manufactured by a known method, and are not particularly limited. The vulcanized product is provided as a solid core in a predetermined injection mold, and in the case of a two-piece solid golf ball, the cover material is arranged in the order, and in the case of a multi-piece solid golf ball, the intermediate layer material and the cover are sequentially arranged. A known method of injecting the material according to a predetermined method can be suitably employed. In some cases, the cover material can be manufactured by pressure molding.
[0057]
The thickness of the intermediate layer of the multi-piece solid golf ball is 0.5 mm or more, preferably 1.0 mm or more, and the upper limit is 3.0 mm or less, preferably 2.5 mm or less, more preferably 2.0 mm or less, most preferably It is recommended that it is 1.6 mm or less.
[0058]
In addition, the cover has a thickness of 0.7 mm or more, preferably 1.0 mm or more, and an upper limit of 3.0 mm or less, preferably 2.5 mm or less, regardless of whether the cover is a two-piece solid golf ball or a multi-piece solid golf ball. It is recommended that the thickness is 2.0 mm or less, and most preferably 1.6 mm or less.
[0059]
The golf ball of the present invention can be used in competition and comply with the golf rules, and can be formed with a diameter of 42.67 mm or more and a weight of 45.93 g or less. The upper limit of the diameter is preferably 44.0 mm or less, more preferably 43.5 mm or less, most preferably 43.0 mm or less, and the lower limit of the weight is preferably 44.5 g or more, particularly preferably 45.0 g or more, more preferably 45. It is recommended that it be at least 1 g, most preferably at least 45.2 g.
[0060]
【The invention's effect】
The golf ball of the present invention has good extrusion workability and excellent resilience.
[0061]
【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.
[0062]
[Examples 1-5, Comparative Examples 1-6]
A core of a two-piece golf ball was prepared by using the polybutadiene shown in Table 1 and vulcanizing at 155 ° C. for 20 minutes using the rubber composition shown in Table 2. In this case, the outer diameter of the core was 38.9 mm, and the weight of the core was 36.0 g. A cover material made of a mixture of HiMilan 1601 and HiMilan 1557 in a weight ratio of 1: 1 is injected onto this core to form dimples, and the surface is coated with paint. The outer diameter is 42.7 mm and the weight is 45.3 g. A two-piece solid golf ball was obtained. The core 100 kg (980 N) load deflection, resilience and golf ball flight performance were evaluated by the following methods. The results are shown in Table 2.
[0063]
[Example 6, Comparative Examples 7 and 8]
Using the rubber composition shown in Table 3, the core of a three-piece golf ball was created by vulcanization at 155 ° C. for 20 minutes. In this case, the outer diameter of the core was 36.4 mm, and the weight was 29.7 g. A mixture of Surlyn 9945, HiMilan 1605, and Dynalon 6100P in a weight ratio of 35:35:30 was injection molded onto this core to form an intermediate layer having a thickness of 1.65 mm.
Further, a cover material made of a mixture of Pandex T8260 and Pandex T8295 in a weight ratio of 1: 1 was injected to obtain a three-piece solid golf ball having an outer diameter of 42.7 mm and a weight of 45.5 g.
The core 100 kg (980 N) load deflection, resilience and golf ball flight performance were evaluated by the following methods. The results are shown in Table 3.
[0064]
[Example 7, Comparative Examples 9 and 10]
A rubber composition shown in Table 4 was used for vulcanization at 170 ° C. for 30 minutes to produce a one-piece golf ball having an outer diameter of 42.7 mm and a weight of 45.3 g, and its performance was evaluated. The results are shown in Table 4.
Deflection amount under 100 kg load The deformation amount (mm) when a 100 kg (980 N) load was applied to the obtained solid core or one-piece golf ball was measured.
In resilience <br/> initial velocity meter accredited institutions USGA the same type measured initial velocity, Examples 1-5, based on the Comparative Example 1 for Comparative Examples 1-6, Example 6, Comparative Example 7 , 8 is based on the comparative example 8 and Example 7, and Comparative Examples 9 and 10 are represented by the difference in the initial speed when the comparative example 10 is the standard.
Flying performance Flying performance when hitting at a head speed of 45m / s (HS45) with a driver (W # 1, Tour Stage X500, Loft 9 °, Shaft X, manufactured by Bridgestone Sports) with a hitting machine Was measured.
Evaluation of extrusion workability Slag skin and slag shape after extrusion were evaluated according to the following criteria.
4 Slag skin is clean and very good 3 Slag skin is slightly rough, but good 2 Slag skin is fluffy but can be extruded 1 Slag shape failure occurs, making it difficult to extrude a predetermined amount [0065]
[Table 1]

[0066]
[Table 2]

(Note) Perhexa 3M-40: 40% diluted product (actual addition amount in parentheses)
[0067]
Comparative Example 1: Since BR is polymerized using a Ni-based catalyst, the resilience is good, but the workability is very poor. Comparative Example 2: Addition amount of BR polymerized using a low-resilience Ni-based catalyst Comparative Example 3: Low Rebound Ni-based catalyst polymerized using a low-rebound Ni-based catalyst Comparative Example 4: Low rebound-reduced Ni-based catalyst Comparative Example 5 with low resilience because of the large amount of BR polymerized using: Comparative Example 6 with low resilience because of the addition of BR polymerized using a low-resilience Ni-based catalyst: Pentachlorothio Reduced resilience due to the absence of phenol zinc salt
[Table 3]

[0069]
Comparative Example 7: Because BR is polymerized using a Ni-based catalyst, the resilience is good, but the workability is very poor. Comparative Example 8: Because BR is polymerized using a low-resilience Ni-based catalyst, Low resilience [0070]
[Table 4]

[0071]
Comparative Example 9: Since BR is polymerized using a Ni-based catalyst, the resilience is good, but the workability is very poor. Comparative Example 10: Because BR is polymerized using a low-resilience Ni-based catalyst, Low resilience

Claims (7)

It contains 60% by weight or more of cis-1,4-bond, Mooney viscosity (ML _{1 + 4} (100 ° C.)) is 50 or more , and molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight). The first polybutadiene synthesized using a rare earth element catalyst of 2.0 to 3.4 is contained in an amount of 50 to 95% by weight, cis-1,4-bond is contained in an amount of 60% by weight or more, and Mooney viscosity (ML _{1 +4} (100 ° C.)) with respect to 100 parts by weight of the rubber base material containing 5 to 50% by weight of the second polybutadiene synthesized using a rare earth element-based catalyst having 45 or less, unsaturated carboxylic acid and / or Rubber composition containing 10 to 60 parts by weight of the metal salt, 0.1 to 5 parts by weight of organic sulfur compound, 5 to 80 parts by weight of inorganic filler, and 0.1 to 3 parts by weight of organic peroxide Characterized by comprising a vulcanized molded product of ball. The golf ball according to claim 1, wherein the first polybutadiene is a modified polybutadiene rubber synthesized by using an Nd-based catalyst and subsequently obtained by reacting with a terminal modifier. The golf ball according to claim 1 , wherein the second polybutadiene has a molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of 2.0 to 6.0. The golf ball according to claim 1 , wherein the second polybutadiene is a modified polybutadiene rubber obtained by synthesis using an Nd-based catalyst and subsequently reacting with a terminal modifier. The golf ball according to claim 1, wherein the Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the second polybutadiene rubber is 40 or less. Including two or more organic peroxides, of which the organic peroxide having the shortest half-life at 155 ° C. is (a), the longest organic peroxide is (b), and the half-life of (a) is a _t, golf ball of any one of claims 1 to 5 the half-life case of a b _t, the ratio b _t / a _t half-life of 7 to 20 or less (b). The golf ball according to claim 1 , wherein the total content of the organic peroxide is 0.1 to 0.8 parts by weight with respect to 100 parts by weight of the rubber base material.