JP2004180733A - Golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball with good extrusion workability, and to improve the resilience of the golf ball. <P>SOLUTION: The golf ball comprises at least 60 % by weight of cis-1,4-bond, 50-95 % by weight of first polybutadiene synthesized by using a rare earth element catalyst whose Mooney viscosity (ML<SB>1+4</SB>(100°C)) is at least 50, and at least 60 % by weight of cis-1,4-bond. The golf ball is made of a vulcanized mold of a rubber composition as a main component comprising 100 parts by weight of a rubber base material including 5-50 % by weight of second polybutadiene synthesized by using a rare earth element catalyst whose Mooney viscosity (ML<SB>1+4</SB>(100°C))is not more than 45, 10-60 parts by weight of unsaturated carboxylic acid and/or its metal salt, 0.1-5 parts by weight of organic sulfur compound, 5-80 parts by weight of inorganic filler, and 0.1-3 parts by weight of organic peroxide. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

（式中、Ｒ^４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、Ｍｅ_３ＳｒＣｌ、Ｍｅ_２ＳｒＣｌ_２、ＭｅＳｒＨＣｌ_２、ＭｅＳｒＣｌ_３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、ＡｌＲ^１Ｒ^２Ｒ^３／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▼Ｒ^５ _ｎＭ′Ｘ_４−ｎ、Ｍ′Ｘ_４、Ｍ′Ｘ_３、Ｒ^５ _ｎＭ′（−Ｒ^６−ＣＯＯＲ^７）_４−ｎ又はＲ^５ _ｎＭ′（−Ｒ^６−ＣＯＲ^７）_４−ｎ（式中、Ｒ^５及びＲ^６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、Ｒ^７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▼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 、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、Ｒ^８〜Ｒ^１６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▼Ｒ^１７ _ｌ Ｍ″（ＯＣＯＲ^１８）_４−ｌ 、Ｒ^１９ _ｌＭ″（ＯＣＯ−Ｒ^２０−ＣＯＯＲ^２１）_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、Ｒ^１７〜Ｒ^２３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及び第２のポリブタジエンとしては、いずれも分子量分布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く、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]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a golf ball having good extrusion workability, excellent resilience, and good flight performance by improving a rubber composition forming a solid core or the like.
[0002]
[Prior art]
Conventionally, in order to impart excellent resilience to golf balls, various improvements have been made to the blending of polybutadiene used as a rubber base material.
[0003]
For example, Japanese Patent Application Laid-Open No. 62-89750 discloses that a rubber base has a polybutadiene having a Mooney viscosity of 70 to 100 synthesized using a Ni or Co catalyst and a Mooney viscosity of 30 to 90 synthesized using a lanthanum catalyst. There has been proposed a rubber composition for a solid golf ball, which comprises a polybutadiene or a polybutadiene having a Mooney viscosity of 20 to 50 synthesized using a Ni, Co catalyst.
However, with respect to 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 with a lanthanide catalyst. However, the resulting golf ball has poor resilience.
[0005]
Japanese Patent Application Laid-Open No. 11-70187 discloses a multi-piece solid golf ball having an intermediate layer formed of polybutadiene having a low Mooney viscosity, and Japanese Patent Application Laid-Open No. 11-319148 uses a Ni, Co catalyst. JP-A-11-164912 discloses a solid golf ball formed of a rubber composition containing 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. , A 1,2-vinyl bond of 2.0% or less, a solid golf ball formed of a rubber composition having a weight average molecular weight to number average molecular weight ratio Mw / Mn of 3.5 or less; JP-A-275356 discloses a golf ball formed of a rubber composition containing high Mooney viscosity polybutadiene. Japanese Patent No. 151985 proposes a golf ball formed of a rubber composition obtained 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.
[0006]
Japanese Patent Application Laid-Open No. 61-71070 discloses that two kinds of organic peroxides are used, and Japanese Patent Application Laid-Open No. 62-112574 discloses that a small amount of organic peroxide is used. However, there is a problem that the resilience is not sufficient, and the crosslinking time is delayed, and the productivity is greatly reduced.
Further, there are proposals in JP-A-2001-149505 to JP-A-2001-149507, but there is still room for improvement in terms of resilience.
[0007]
[Patent Document 1]
JP-A-58-225138 [Patent Document 2]
JP-A-62-89750 [Patent Document 3]
Japanese Patent Application Laid-Open No. 62-112574 [Patent Document 4]
JP-A-63-275356 [Patent Document 5]
JP-A-3-151985 [Patent Document 6]
JP-A-2-268778 [Patent Document 7]
JP-A-11-70187 [Patent Document 8]
JP-A-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]
JP 2001-149507 A
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, has good extrusion workability, can shorten the vulcanization time, improves productivity, has a good hit feeling, has excellent resilience, and has good flight performance. It is an object to provide a golf ball that gives performance.
[0009]
Means for Solving the Problems and Embodiments of the Invention
Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, a polybutadiene containing 60% by weight or more of cis-1,4-bond and synthesized using a rare earth element catalyst, A rubber base material having a viscosity (ML _{1 + 4} (100 ° C.)) of 50 or more and 45 or less is used in a specific ratio, and an unsaturated carboxylic acid and / or 100 parts by weight of the rubber base material is used. 10 to 60 parts by weight of the metal salt, 0.1 to 5 parts by weight of the organic sulfur compound, 5 to 80 parts by weight of the inorganic filler, and 0.1 to 3 parts by weight of the organic peroxide. In this case, preferably, two or more kinds of organic peroxides are (a) the organic peroxide having the shortest half-life at 155 ° C. and (b) the longest organic peroxide, and (a) half-life _a t) of and a _{b t} half-life of (b) If, to the vulcanized molded article components of the blended rubber composition so that the ratio b _{t /} a _t half-life is 7 to 20, in particular, by a solid core of solid golf balls, It has been found that a golf ball having excellent manufacturability and good 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, a rubber composition having good resilience and extrusion workability In the past, when the amount of organic peroxide was reduced, the vulcanization time was extended, the productivity was reduced, and the resilience was not sufficient. The use of polybutadiene synthesized using an organic catalyst and containing a small amount of two or more organic peroxides with significantly different half-lives improve workability, shorten vulcanization time, and improve productivity. Above, it was found that a further improvement in resilience could be achieved, leading to the present invention.
[0011]
Accordingly, the present invention provides the following golf balls.
Claim 1:
50 to 95% by weight of a first polybutadiene synthesized using a rare earth element catalyst containing 60% by weight or more of cis-1,4-bond and having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 50 or more 5 to 50% by weight of a second polybutadiene synthesized using a rare earth element-based catalyst containing 60% by weight or more of cis-1,4-bond and having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 45 or less. % To 100 parts by weight of a rubber base material containing 10% to 60% by weight of an unsaturated carboxylic acid and / or a metal salt thereof, 0.1 to 5 parts by weight of an organic sulfur compound, and 5 to 80 parts by weight of an inorganic filler. And a vulcanized molded product of a rubber composition containing 0.1 to 3 parts by weight of an organic peroxide as a component,
Claim 2:
The golf ball according to claim 1, wherein the first 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 3:
The golf ball according to claim 1 or 2, wherein the first polybutadiene is a modified polybutadiene rubber synthesized using an Nd-based catalyst and subsequently obtained by reacting a terminal modifier.
Claim 4:
4. 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 5:
The golf ball according to any one of claims 1 to 4, wherein the second polybutadiene is a modified polybutadiene rubber synthesized using an Nd-based catalyst and subsequently obtained by reacting a terminal modifier.
Claim 6:
The golf ball according to claim 1, wherein the second polybutadiene rubber has a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 40 or less.
Claim 7:
It contains two or more kinds of organic peroxides, of which the organic peroxide having the shortest half-life at 155 ° C. is (a), the organic peroxide having the longest is (b), and the half-life of (a) is a _t, if the half-life of (b) was _{b t,} the half-life of the ratio _b t / _{a t} 7 to 20 in which any one golf ball according to claims 1 to 6,
Claim 8:
The golf ball according to any one of claims 1 to 7, wherein the total content of the organic peroxide is 0.1 to 0.8 parts by weight based on 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
(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 catalyst are mainly used. Rubber base material,
(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 a constituent element.
[0013]
Here, first, both the first and second polybutadienes of the component (A) have a cis-1,4-bond content of at least 60% (% by weight, hereinafter the same), preferably at least 80%, more preferably at least 80%. It is necessary to have 90% or more, most preferably 95% or more. If the amount of the cis-1,4-bond is too small, the resilience decreases.
Further, the content of the 1,2-vinyl bond is preferably 2% or less, more preferably 1.7% or less, and further preferably 1.5% or less. If the content of the 1,2-vinyl bond is too large, the resilience may decrease.
[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 the upper limit is 140 or less, preferably 120 or less, and furthermore Preferably it is 100 or less, 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 by a Mooney viscometer, which is one type of rotational plasticity meter, and has a unit symbol of ML _{1 + 4} (100 ° C.). ) Is used. M indicates Mooney viscosity, L indicates a large rotor (L type), 1 + 4 indicates a preheating time of 1 minute, and a rotation time of the rotor is 4 minutes, indicating that the measurement was performed at 100 ° C.
[0016]
The polybutadiene used in the present invention needs to be synthesized with a rare earth element-based catalyst, and known rare earth element-based catalysts can be used.
[0017]
For example, a lanthanum series rare earth element compound, an organoaluminum compound, an alumoxane, a halogen-containing compound and, if necessary, a catalyst comprising a combination of a Lewis base can be mentioned.
[0018]
Examples of the lanthanide series rare earth element compounds include metal halides, carboxylate salts, alcoholates, thioalcoholates, and amides having atomic numbers of 57 to 71.
[0019]
Examples of the organoaluminum compound include AlR ¹ R ² R ³ (where R ¹ , R ² and R ³ may be the same or different, and each is hydrogen or a hydrocarbon residue having 1 to 8 carbon atoms. ) Can be used.
[0020]
The alumoxane preferably includes a compound having a structure represented by the following formula (I) or (II). In this case, Fine Chemicals, 23, (9), 5 (1994); Am. Chem. Soc. , 115, 4971 (1993); Am. Chem. Soc. , 117, 6465 (1995).
[0021]
Embedded image

(In the formula, R ⁴ is a hydrocarbon group containing 1 to 20 carbon atoms, and n is an integer of 2 or more.)
[0022]
The halogen-containing _compounds, AlX _{n R 3-n} (wherein, X is a halogen, R represents a hydrocarbon residue having 1 to 20 carbon atoms, for example, an alkyl group, an aryl group, an aralkyl group And n represents 1, 1.5, 2 or 3), a strontium halide such as Me ₃ SrCl, Me ₂ SrCl ₂ , MeSrHCl ₂ , 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 lanthanide 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 the lanthanum series rare earth element compound is superior to polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds. Specific examples of these rare earth element-based catalysts include those described in JP-A-11-35633.
[0025]
When butadiene is polymerized in the presence of a rare earth element-based catalyst using a lanthanum series rare earth element compound, the butadiene / lanthanum series rare earth element compound is used in a molar ratio in order to keep the cis content and Mw / Mn within the above ranges. 1,000～200 ten thousand, and particularly preferably be a 5,000～100 ten thousand, ^also, AlR ^{1 R} 2 R ³ / lanthanum series rare earth element compound, 1 to 1,000 by molar ratio, in particular 3 It is preferably 500. Further, the molar ratio of the halogen compound / lanthanum series rare earth element compound is preferably from 0.1 to 30, particularly preferably from 0.2 to 15. The molar ratio of the Lewis base / lanthanum series rare earth element compound is preferably from 0 to 30, particularly preferably from 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 150C, preferably 10 to 100C.
[0026]
When butadiene is polymerized in the presence of a rare earth element-based catalyst, a solvent may be used, 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 set to 10 to 100 ° C.
[0027]
The polybutadiene of the component (A) of the present invention may be obtained by reacting a terminal modifier with the active terminal of the polymer, following the polymerization with the rare earth element-based catalyst.
[0028]
For the modified polybutadiene rubber, following the above polymerization, the terminal modifiers described in the following (1) to (7) can be used.
(1) It can be 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 a 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, condensate of 3-glycidyloxypropyltrimethoxysilane, condensate of (3-glycidyloxypropyl) methyldimethoxysilane; 3-isocyanatopropyltrimethoxysilane; Isocyanatopropyltriethoxysilane, (3-isocyanatopropyl) methyldimethoxysilane, (3-isocyanatopropyl) methyldiethoxysilane, condensate of 3-isocyanatopropyltrimethoxysilane, (3-isocyanatopropyl) methyl An isocyanate group-containing alkoxysilane compound such as a condensate of dimethoxysilane is exemplified.
[0029]
When the compound having an alkoxysilyl group is reacted with an active terminal, a Lewis acid may be added to accelerate the reaction. The Lewis acid accelerates the coupling reaction as a catalyst, improving the cold flow of the modified polymer and improving the storage stability. Specific examples of Lewis acids include dialkyltin dialkyl malates, dialkyltin dicarboxylates, and aluminum trialkoxides.
[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 are a hydrocarbon group containing 1 to 20 carbon atoms, and R ⁷ is a 1 to 20 carbon atom Which may contain a carbonyl group or an ester group in the side chain, M ′ is a tin atom, a silicon atom, a germanium atom or a phosphorus atom, X is a halogen atom, and n is an integer of 0 to 3. Corresponding to) a halogenated organometallic compound, a metal halide compound or an organometallic compound,
(3) Heterocumulene containing a Y = C = Z bond (wherein Y represents a carbon atom, an oxygen atom, a nitrogen atom or a sulfur atom, and Z represents an oxygen atom, a nitrogen atom or a sulfur atom) in the molecule. Compound,
(4) a hetero three-membered ring compound containing the following bond in the molecule;
Embedded image

(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 represented by the formula, acid halide, ester compound, carbonate compound or acid anhydride,
Embedded image

(In the formula, R ^{8 to} R ¹⁶ may be the same or different, a hydrocarbon group containing 1 to 50 carbon atoms, X is a halogen atom, and m is an integer of 1 to 5.)
_{^{▲ 7 ▼ R 17 l M "}} (OCOR 18) 4-l, R 19 l M" (OCOR 20 -COOR 21) 4-l or metal salt of a carboxylic acid embedded image represented by the following formula,

(In the formula, 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 an integer of 1).
[0031]
Specific examples of the terminal modifier shown above and the method of reacting 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 and second polybutadienes each have 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, and furthermore. It is preferably at least 2.4, most preferably at least 2.6, and the upper limit is at most 6.0, preferably at most 5.0, more preferably at most 4.0, most preferably at most 3.4. When Mw / Mn is too small, workability may be reduced, and when Mw / Mn is too large, resilience may be reduced.
[0033]
In the present invention, the rubber base mainly containing the first and second polybutadienes is used. In this case, the first polybutadiene of the base is 50% or more, preferably 60%, of the rubber base. %, More preferably 70% or more, most preferably 75% or more, 95% or less, preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. On the other hand, the second polybutadiene accounts for 5% or more, preferably 10% or more, more preferably 15% or more, and still more preferably 20% or more, and 50% or less, preferably 40% or less in the rubber base material. It is more preferably at most 30%, further preferably at most 20%. If the amount of the first polybutadiene is too large, extrusion workability cannot be obtained. On the other hand, if the amount of the second polybutadiene is too large, the resilience decreases.
[0034]
The rubber substrate may contain other rubber components in addition to the polybutadiene as long as the effects of the present invention are not impaired. Examples of the rubber component other than the polybutadiene include polybutadiene other than the polybutadiene, for example, polybutadiene obtained using a Group VIII metal compound catalyst, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber. No.
[0035]
Next, examples of the unsaturated carboxylic acid as the component (B) include acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and acrylic acid and methacrylic acid are particularly preferable. Examples of the metal salt of an unsaturated carboxylic acid include a zinc salt and a magnesium salt, and among them, zinc acrylate is preferably used.
[0036]
The compounding amount of the unsaturated carboxylic acid / salt of the component (B) is 10 parts or more, more preferably 15 parts or more, based on 100 parts (parts by weight, the same applies hereinafter) of the rubber base material of the component (A). Preferably it is 20 parts or more, 60 parts or less, more preferably 50 parts or less, further preferably 45 parts or less, most preferably 40 parts or less.
[0037]
Examples of the organic sulfur compound as the component (C) include thiophenol, thiophtol, halogenated thiophenol, and metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol or a zinc salt 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.In particular, zinc salts of pentachlorothiophenol and diphenyl disulfide are preferably used. Can be.
[0038]
The compounding amount is 0.1 part or more, more preferably 0.2 part or more, further preferably 0.4 part or more, and most preferably 0.7 part or more, based on 100 parts of the rubber base material of the component (A). 5 parts or less, more preferably 4 parts or less, still more preferably 3 parts or less, most preferably 2 parts or less, particularly preferably 1.5 parts or less. If the amount is too small, the effect of improving resilience will not be obtained. If the amount is too large, the hardness will be too soft and sufficient resilience will not be obtained.
[0039]
Examples of the inorganic filler of the component (D) include zinc oxide, barium sulfate, and calcium carbonate. The compounding amount is 5 parts or more, more preferably 7 parts or more, and still more preferably 100 parts of the component (A). Is at least 10 parts, most preferably at least 13 parts, at most 80 parts, more preferably at most 65 parts, further preferably at most 50 parts, most preferably at most 40 parts. If the amount is too large or too small, an appropriate weight and a suitable rebound cannot be obtained.
[0040]
As the organic oxide of the component (E), a known organic oxide 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). Diisopropylbenzene and the like. Commercially available organic peroxides can be used, and examples thereof include Parkmill D (manufactured by NOF Corporation), Perhexa 3M (manufactured by NOF Corporation), and Luperco 231XL (manufactured by Atochem Corporation).
[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 terms 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 It is 18 or less, more preferably 16 or less, and most preferably 14 or less. Even if two or more kinds of organic peroxides are used, if they deviate from the above range, the resilience, compression and durability will be 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 And the half-life b _t at 155 ° C. of (b) is 300 seconds or more, more preferably 360 seconds or more, still more preferably 420 seconds or more, and 800 seconds or less, more preferably 700 seconds or less. , More preferably 600 seconds or less. In this case, as the organic peroxide of the component (a), 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane is preferable, and as the organic peroxide of the component (b), Is preferably dicumyl peroxide.
[0043]
The total amount of the organic peroxide is 0.1 part or more, preferably 0.2 part or more, more preferably 0.3 part or more, based on 100 parts of the rubber base material of the component (A). The content is more preferably 0.4 part or more, 3 parts or less, preferably 2 parts or less, more preferably 1 part or less, further preferably 0.8 part or less, particularly preferably 0.6 part or less. If the amount is too small, the time required for crosslinking increases, the productivity is greatly reduced, and the compression is greatly reduced. If the amount is too large, the resilience and durability will be reduced.
[0044]
When two or more of the above (a) and (b) are used, the amount of the component (a) added is preferably 0.05 parts or more, more preferably 0.08 parts or more, per 100 parts of the component (A). More preferably 0.1 part or more, 1.5 parts or less, more preferably 1 part or less, further preferably 0.7 part or less, particularly preferably 0.4 part or less, and component (b). Is added in an amount of 0.05 part or more, more preferably 0.15 part or more, still more preferably 0.2 part or more, 1.5 part or less, more preferably 1 part or less, and even more preferably 0.7 part or less. And particularly preferably 0.4 part or less.
[0045]
Further, if necessary, the antioxidant is added in an amount of 0.05 part or more, more preferably 0.1 part or more, still more preferably 0.2 part or more, and 3 parts or less, based on 100 parts of the component (A). Preferably not more than 2 parts, more preferably not more than 1 part, most preferably not more than 0.5 part. In addition, a commercially available product can be used as the antiaging agent, and examples thereof include Nocrack NS-6 and NS-30 (manufactured by Ouchi Shinko Chemical Co., Ltd., Yoshinox 425 (manufactured by Yoshitomi Pharmaceutical Co., Ltd.)). Can be
[0046]
The vulcanized molded product of the present invention can be obtained by vulcanizing and curing the above rubber composition in the same manner as a known rubber composition for golf balls. The vulcanization 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 usage mode of various golf balls described below, and is not particularly limited, and the cross-sectional hardness is from the center to the surface of the molded product. It may be flat or may have a difference in hardness between the center and the surface of the molded product.
[0048]
Further, the golf ball of the present invention can take various golf ball embodiments described below, particularly when the golf ball is one of a one-piece golf ball or a golf ball having a solid core or solid center, The deflection of the one-piece solid golf ball, solid core or solid center under a load of 980 N (100 kg) is usually 2.0 mm or more, preferably 2.5 mm or more, more preferably 2.8 mm or more, and most preferably 3. It is recommended that the thickness be 2 mm or more, and the upper limit be 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 above vulcanized molded product as a constituent element, and the form of the ball is not particularly limited, and the one-piece golf ball in which the above vulcanized molded product is directly applied to a golf ball A two-piece solid golf ball having a vulcanized molded product as a solid core and a cover formed on the surface thereof; a three-piece or more multi-piece having a vulcanized molded product as a solid core and having two or more layers of covers formed on the outside thereof Various modes such as a solid golf ball, a thread wound golf ball in which the above vulcanized molded product is applied as a center core, and the like can be adopted. In particular, two-piece solid golf balls and multi-piece solid golf using the vulcanized molded product of the present invention as a solid core from the viewpoint of extrudability at the time of production and imparting resilience to a product golf ball by utilizing the properties of the vulcanized molded product. A ball is recommended as a preferred mode of use.
[0050]
In the present invention, when the vulcanized molded product is the solid core, the solid core has a diameter of 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. It is recommended that the upper limit be 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 41.0 mm or less, preferably 40.5 mm or less, more preferably 40.0 mm or less as an upper limit. Hereinafter, the diameter of the solid core of the three-piece solid golf ball is 30.0 mm or less. It is preferably at least 32.0 mm, more preferably at least 34.0 mm, most preferably at least 35.0 mm, and at most 40.0 mm, preferably at most 39.5 mm, more preferably at most 39.0 mm. 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 used as a two-piece solid golf ball or a multi-piece solid golf ball, the vulcanized molded product is formed as a solid core by injection molding or pressure molding a known cover material and an intermediate layer material. be able to.
[0053]
Specific examples of the main material of these cover materials and intermediate layer materials include thermoplastic or thermosetting polyurethane-based elastomers, polyester-based elastomers, ionomer resins, polyolefin-based elastomers, and mixtures thereof. One of these can be used alone or two or more can be used in combination. In particular, a thermoplastic polyurethane elastomer and an ionomer resin can be preferably used.
[0054]
As the thermoplastic polyurethane-based elastomer, commercially available products can be used. For example, diisocyanates such as Pandex T7298, T7295, T7890, TR3080, T8295, T8290, and T8260 (manufactured by Bayer Polymer Co., Ltd.). Are aliphatic or aromatic, and the like. Examples of commercially available ionomer resins include Surlyn 6320, 8120, 9945 (manufactured by Dupont, USA), Himilan 1706, 1605, 1855, 1601, and 1557 (manufactured by Dupont Mitsui Polychemicals). Can be illustrated.
[0055]
Further, a polymer such as a thermoplastic elastomer other than the above can be blended as an optional component with the main material of the cover material or the intermediate layer material. Specific examples of the optional polymer include polyamide-based elastomers, styrene-based block elastomers, hydrogenated polybutadiene, and ethylene-vinyl acetate (EVA) copolymer.
[0056]
The two-piece solid golf ball and the multi-piece solid golf ball of the present invention can be produced by a known method, and are not particularly limited. The vulcanized molded product is disposed as a solid core in a predetermined injection mold, and in the case of a two-piece solid golf ball, the cover material is used. A known method of injecting a material according to a predetermined method can be suitably adopted. 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 3.0 mm or less as an upper limit, preferably 2.5 mm or less, more preferably 2.0 mm or less, and most preferably. It is recommended that it be 1.6 mm or less.
[0058]
Further, the thickness of the cover is 0.7 mm or more, preferably 1.0 mm or more, and 3.0 mm or less as an upper limit, preferably 2.5 mm or less, regardless of whether it is a two-piece solid golf ball or a multi-piece solid golf ball. More preferably, it is recommended to be 2.0 mm or less, and most preferably 1.6 mm or less.
[0059]
The golf ball of the present invention can conform to the Rules of Golf for competition and can be formed to a diameter of not less than 42.67 mm and a weight of not more than 45.93 g. 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, and further preferably 45 mm or less. It is recommended to weigh at least 0.1 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】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[0062]
[Examples 1 to 5, Comparative Examples 1 to 6]
Cores of two-piece golf balls were 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 was injected into the core to form dimples, the surface of which was coated with paint, and having an outer diameter of 42.7 mm and a weight of 45.3 g. A two-piece solid golf ball was obtained. The above-described cores were evaluated for the amount of deflection under a load of 100 kg (980 N), resilience, and flight performance of a golf ball by the following methods. Table 2 shows the results.
[0063]
[Example 6, Comparative Examples 7, 8]
A three-piece golf ball core was prepared by vulcanizing at 155 ° C. for 20 minutes using the rubber composition shown in Table 3. 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 Dynaron 6100P in a weight ratio of 35:35:30 was injection-molded on the 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 at 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 above-described cores were evaluated for the amount of deflection under a load of 100 kg (980 N), resilience, and flight performance of a golf ball by the following methods. Table 3 shows the results.
[0064]
[Example 7, Comparative Examples 9 and 10]
A one-piece golf ball having an outer diameter of 42.7 mm and a weight of 45.3 g was manufactured by vulcanizing the rubber composition shown in Table 4 at 170 ° C. for 30 minutes, and the performance was evaluated. Table 4 shows the results.
Deflection amount under a load of 100 kg With respect to the obtained solid core or one-piece golf ball, the deformation amount (mm) under a load of 100 kg (980 N) was measured.
The resilience The initial speed was measured with an initial speedometer of the same type as that of the official agency USGA, and Examples 1 to 5 and Comparative Examples 1 to 6 were based on Comparative Example 1, and Examples 6 and 7 were used. , 8 are based on Comparative Example 8, and Example 7, and Comparative Examples 9 and 10 represent the difference in initial speed when Comparative Example 10 is used as a reference.
Flying performance Flying performance when hit with a driver (W # 1, Tour Stage X500, Loft 9 °, Shaft X, Bridgestone Sports Co., Ltd.) at a head speed of 45 m / s (HS45) with a hitting machine Was measured.
Evaluation of extrusion workability The slag skin and slag shape after extrusion were evaluated according to the following criteria.
4 Very good and clean slag skin 3 Good but slightly rough slag skin 2 Fluffy slag skin but extrudable 1 Slag slag shape defect occurs and it is difficult to extrude a specified amount of slag
[Table 1]

[0066]
[Table 2]

(Note) Perhexa 3M-40: 40% diluted product (the actual amount added is in parentheses)
[0067]
Comparative Example 1: BR alone polymerized using a Ni-based catalyst has good resilience but very poor workability Comparative Example 2: Addition amount of BR polymerized using a low-repulsion Ni-based catalyst Comparative Example 3: Low rebound resilience Comparative Example 4: low rebound Ni-based catalyst due to BR polymerized using a low resilience Ni-based catalyst Comparative Example 5: Low repulsion due to the large amount of BR polymerized using the same. Comparative Example 6: Pentachlorothio having low resilience due to the addition of BR polymerized using a low-repulsion Ni-based catalyst. Since no zinc salt of phenol was added, the resilience decreased.
[Table 3]

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

[0071]
Comparative Example 9: The resilience was good because of a BR polymerized using a Ni-based catalyst, but the workability was very poor. Comparative Example 10: BR polymerized using a low-repulsion Ni-based catalyst, Low rebound

Claims (8)

50 to 95% by weight of the first polybutadiene synthesized using a rare earth element catalyst containing 60% by weight or more of cis-1,4-bond and having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 50 or more 5 to 50% by weight of a second polybutadiene synthesized using a rare earth element-based catalyst containing 60% by weight or more of cis-1,4-bond and having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 45 or less. % To 100 parts by weight of a rubber base material containing 10% to 60% by weight of an unsaturated carboxylic acid and / or a metal salt thereof, 0.1 to 5 parts by weight of an organic sulfur compound, and 5 to 80 parts by weight of an inorganic filler. And a vulcanized molded product of a rubber composition containing 0.1 to 3 parts by weight of an organic peroxide. The golf ball according to claim 1, wherein the molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of the first polybutadiene is 2.0 to 6.0. 3. The golf ball according to claim 1, wherein the first polybutadiene is a modified polybutadiene rubber synthesized using an Nd-based catalyst and subsequently obtained by reacting a terminal modifier. The golf ball according to any one of claims 1 to 3, 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 any one of claims 1 to 4, wherein the second polybutadiene is a modified polybutadiene rubber synthesized using an Nd-based catalyst and subsequently obtained by reacting a terminal modifier. 6. The golf ball according to claim 1, wherein the second polybutadiene rubber has a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 40 or less. It contains two or more kinds of organic peroxides, of which the organic peroxide having the shortest half-life at 155 ° C is (a), the organic peroxide having the longest is (b), and the half-life of (a) is a _t, golf ball according to any one of claims 1 to 6 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 any one of claims 1 to 7, wherein the total content of the organic peroxide is 0.1 to 0.8 parts by weight based on 100 parts by weight of the rubber substrate.