JP3579942B2 - Ethylene-α-olefin-non-conjugated diene copolymer rubber composition - Google Patents

Description

【０００７】
〔式（１）において、各Ｒ は相互に同一でも異なってもよく、水素原子、炭素数１〜１０の飽和脂肪族炭化水素基、炭素数１〜１０の不飽和脂肪族炭化水素基、炭素数１〜１０の飽和脂環式炭化水素基または炭素数１〜１０の不飽和脂環式炭化水素基を示し、ｎは４〜１６の整数である。〕
このようなα，ω−ジエンの具体例としては、１，７−オクタジエン、１，８−ノナジエン、１，９−デカジエン、１，１１−ドデカジエン、１，１３−テトラデカジエン、１，１５−ヘキサデカジエン、１，１７−オクタデカジエン、１，１９−イコサジエン、３，６−ジメチル−１，７−オクタジエン、４，５−ジメチル−１，７−オクタジエン、５−メチル−１，８−ノナジエン等を挙げることができ、特に１，７−オクタジエン、１，９−デカジエンが好ましい。前記α，ω−ジエンは、単独でまたは２種以上を混合して使用することができる。
（Ａ）共重合ゴムにおける各非共役ジエンの含有量については、エチリデンノルボルネンの含有量は、（Ａ）共重合ゴムのよう素価で２０〜６０となる量、好ましくは２５〜４５となる量である。この場合、エチリデンノルボルネンの含有量がよう素価で２０未満では、共重合ゴム組成物から得られるスポンジゴムの低温における圧縮永久歪が損なわれ、また架橋速度が低くなるため、ガス抜けによる表面肌の悪化および形状保持性の低下を来し、一方よう素価で６０を超えると、混練加工時および押出加工時に“ブツ”、“ゲル”を生じやすく、また架橋速度と発泡速度とのバランスが狂い、共重合ゴム組成物を高発泡させることが困難となり、コストも高くなる。
また、ジシクロペンタジエンの含有量は、（Ａ）共重合ゴムのよう素価で１〜２０となる量、好ましくは４〜１５となる量である。この場合、ジシクロペンタジエンの含有量がよう素価で１未満では、共重合ゴム組成物から得られるスポンジゴムの形状保持性が低下し、一方よう素価で２０を超えると、押出加工性が低下する。
また、α，ω−ジエンの含有量は、全単量体成分の０．０５〜２重量％、好ましくは０．１〜１重量％である。この場合、α，ω−ジエンの含有量が０．０５重量％未満では、スポンジゴムの形状保持性が低下し、一方２重量％を超えると、押出加工性が低下する。
本発明における（Ａ）共重合ゴムは、非共役ジエンが（ａ）エチリデンノルボルネンおよび（ｂ）ジシクロペンタジエンとα，ω−ジエンとのいずれか１種を含有するものであるが、この場合、非共役ジエンが前記（ａ）エチリデンノルボルネンのみでは、形状保持性が著しく低下する。
（Ａ）共重合ゴムのム−ニ−粘度（ＭＬ_１＋４，１００℃）は５０〜１５０、好ましくは６０〜１４０である。この場合、（Ａ）共重合ゴムのム−ニ−粘度（ＭＬ_１＋４，１００℃）が５０未満では、共重合ゴム組成物から得られるスポンジゴムの形状保持性の低下および架橋・発泡時のガス抜けによる表面肌の悪化を来し、また形状保持性、圧縮永久歪、低伸長応力も損なわれ、一方１５０を超えると、高発泡させることが困難となり、また混練加工性、押出加工性も低下する。
本発明において、前記（Ａ）共重合ゴムは、単独でまたは２種以上を混合して使用することができる。
本発明においては、前記（Ａ）共重合ゴムを後述する（Ｂ）エチレン系重合体と組合せて使用することにより、共重合ゴム組成物に対して、高発泡性、形状保持性、混練・押出加工性、架橋速度、圧縮永久歪、低伸長応力、スポンジゴムの表面肌等を含めて、優れた特性バランスを付与することができることとなる。
【０００８】
（Ａ）共重合ゴムは、中・低圧法による通常の重合方法、例えば、適当な溶媒中、遷移金属化合物と有機金属化合物とからなるチーグラー・ナッタ触媒、例えば少なくとも１種の溶媒可溶性バナジウム化合物と少なくとも１種の有機アルミニウム化合物とからなる触媒の存在下で、エチレン、α−オレフィンおよび非共役ジエンを、必要に応じて分子量調節剤として水素を供給しつつ重合する方法により製造することができ、その際の重合は、気相法（流動床あるいは攪拌床）でも液相法（スラリー法あるいは溶液法）でも実施することができる。
前記溶媒可溶性バナジウム化合物としては、ＶＯＣｌ_３ 、ＶＣｌ_４、ＶＯＣｌ_３ あるいは
ＶＣｌ_４の少なくとも１種とアルコールとの反応生成物が好ましい。この場合、前記アルコールとしては、例えばメタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブタノール、ｓｅｃ−ブタノール、ｔ−ブタノール、ｎ−ヘキサノール、ｎ−オクタノール、２−エチルヘキサノール、ｎ−デカノール、ｎ−ドデカノール等を挙げることができ、これらのうち炭素数３〜８のアルコールが好ましい。
また、前記有機アルミニウム化合物としては、例えばトリエチルアルミニウム、トリイソブチルアルミニウム、トリ−ｎ−ヘキシルアルミニウム、ジエチルアルミニウムモノクロリド、ジイソブチルアルミニウムモノクロリド、エチルアルミニウムセスキクロリド、ブチルアルミニウムセスキクロリド、エチルアルミニウムジクロリド、ブチルアルミニウムジクロリド、トリメチルアルミニウムと水との反応生成物であるメチルアルミノキサン等を挙げることができ、特にエチルアルミニウムセスキクロリド、ブチルアルミニウムセスキクロリド、エチルアルミニウムセスキクロリドとブチルアルミニウムセスキクロリドとの混合物、トリイソブチルアルミニウムとブチルアルミニウムセスキクロリドとの混合物が好ましい。
また、前記溶媒としては、通常、炭化水素溶媒が使用され、好ましい炭化水素溶媒は、ｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、ｎ−オクタン、イソオクタン、シクロヘキサン等である。これらの炭化水素溶媒は、単独でまたは２種以上を混合して使用することができる。
【０００９】
（Ｂ）他のエチレン系重合体
次に、本発明の共重合ゴム組成物において使用される（Ｂ）他のエチレン系重合体（以下、「（Ｂ）エチレン系重合体」という。）は、低密度ポリエチレン、融点が６０〜１２０℃のエチレン−α−オレフィン共重合体（以下、「エチレン−α−オレフィン共重合体」という。）および融点が６０〜１２０℃のエチレン−α−オレフィン−非共役ジエン共重合体（以下、「共重合ゴム（ｂ）」という。）の群から選ばれる少なくとも１種からなる。但し、ここでいう融点とは、ＤＳＣ（示差走査熱量計）測定によるものとする。
（Ｂ）エチレン系重合体において、低密度ポリエチレンの密度は、通常、０．９３５ｇ／cm³ 以下であるが、好ましい密度範囲は０．９１０〜０．９３５ｇ／cm³ である。
低密度ポリエチレンとしては、例えば高圧法により得られる低密度ポリエチレン（以下、「ＬＤＰＥ」という。）あるいは中・低圧法により得られる直鎖状低密度ポリエチレン（以下、「Ｌ−ＬＤＰＥ」という。）を挙げることができるが、これらのいずれも使用することができる。
高圧法によるＬＤＰＥは、気相法でもスラリー法（水媒質中あるいは有機媒質中）でも製造することができ、また中・低圧法によるＬ−ＬＤＰＥは、気相法（流動床あるいは攪拌床）でも液相法（スラリー法あるいは溶液法）でも製造することができる。
本発明において、前記低密度ポリエチレンは、単独でまたは２種以上を混合して使用することができる。
さらに、エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）において使用されるαーオレフィンとしては、例えば炭素数３〜１２のα−オレフィン、具体的にはプロピレン、ブテン−１、３−メチルブテン−１、ペンテン−１、３−メチルペンテン−１、４−メチルペンテン−１、３−エチルペンテン−１、ヘキセン−１、オクテン−１、デセン−１、ドデセン−１等を挙げることができ、特にブテン−１が好ましい。これらのα−オレフィンは、単独でまたは２種以上を混合して使用することができる。
また、共重合ゴム（ｂ）において使用される非共役ジエンとしては、例えばエチリデンノルボルネン、ビニルノルボルネン、ジシクロペンタジエン、１，４−ヘキサジエン、１，７−オクタジエン、１，９−デカジエン、１，１１−ドデカジエン、１，１３−テトラデカジエン、１，１５−ヘキサデカジエン、１，１７−オクタデカジエン、１，１９−イコサジエン、３，６−ジメチル−１，７−オクタジエン、４，５−ジメチル−１，７−オクタジエン、５−メチル−１，８−ノナジエン等を挙げることができ、特にエチリデンノルボルネン、ジシクロペンタジエン、１，７−オクタジエン、１，９−デカジエンが好ましい。これらの非共役ジエンは、単独でまたは２種以上を混合して使用することができる。
エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）におけるエチレン／αーオレフィン重量比は、通常、７０／３０〜９０／１０、好ましくは７８／２２〜９０／１０である。この場合、エチレン／αーオレフィン重量比が７０／３０未満では、共重合ゴム組成物から得られるスポンジゴムの低伸長応力が低下する傾向があり、一方９０／１０を超えと、共重合におけるエチレンとαーオレフィンとの反応性の差に起因して、均質なエチレン−α−オレフィン共重合体および共重合ゴム（ｂ）を得ることが困難となる。
また、エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）の融点は、５０℃以上、好ましくは６０〜１２０℃である。この場合、エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）の融点が５０℃未満では、本発明の共重合ゴム組成物から得られるスポンジゴムの低伸長応力が低下する。
なお、共重合ゴム（ｂ）における非共役ジエンの含有量は、共重合ゴム（ｂ）のよう素価で２〜４０となる量が好ましく、特に３〜２０となる量が好ましい。 前記エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）は、中・低圧法による通常の重合方法、例えば、エチレンとα−オレフィンとを、共重合ゴム（ｂ）の場合はさらに非共役ジエンを添加して、前記（Ａ）共重合ゴムの場合と同様にして重合する方法により製造することができる。
本発明において、前記エチレン−α−オレフィン共重合体および共重合ゴム（ｂ）は、それぞれ単独でまたは２種以上を混合して使用することができる。
本発明における（Ｂ）エチレン系重合体の配合量は、（Ａ）共重合ゴム１００重量部に対して、１０〜１００重量部、好ましくは１５〜７０重量部である。この場合、（Ｂ）エチレン系重合体の配合量が１０重量部未満では、共重合ゴム組成物を高発泡させて得られるスポンジゴムの低伸長応力、表面肌や、共重合ゴム組成物の押出加工性が損なわれ、一方１００重量部を超えると、共重合ゴム組成物の高発泡性、混練加工性、押出加工性が損なわれる。
【００１０】
（Ｃ）充填剤
次に、本発明の共重合ゴム組成物において使用される充填剤としては、例えばＳＲＦ、ＦＥＦ、ＨＡＦ、ＩＳＡＦ、ＳＡＦ、ＦＴ、ＭＴ等のカーボンブラック；微粒子けい酸、炭酸カルシウム、炭酸マグネシウム、クレー、タルク等の無機充填剤等を挙げることができる。これらの充填剤は、単独でまたは２種以上を混合して使用することができる。
本発明における充填剤の配合量は、（Ａ）共重合ゴム１００重量部に対して、３０〜２００重量部、好ましくは５０〜１５０重量部である。この場合、充填剤の配合量が３０重量部未満では、共重合ゴム組成物から得られるスポンジゴムの低伸長応力、強度が低下し、一方２００重量部を超えると、共重合ゴム組成物の溶融粘度が高くなり、高発泡性が損なわれる。
（Ｄ）軟化剤
次に、本発明の共重合ゴム組成物において使用される軟化剤としては、ゴムに通常用いられるアロマティック油、ナフテニック油、パラフィン油等のプロセスオイル；やし油等の植物油等を挙げることができる。これらの軟化剤のうち、プロセスオイルが好ましく、特にパラフィン油が好ましい。これらの軟化剤は、単独でまたは２種以上を混合して使用することができる。
本発明における軟化剤の配合量は、（Ａ）共重合ゴム１００重量部に対して、３０〜１５０重量部、好ましくは４０〜１００重量部である。この場合、軟化剤の配合量が３０重量部未満では、共重合ゴム組成物の混練加工性、押出加工性が低下し、一方１５０重量部を超えると、共重合ゴム組成物から得られるスポンジゴムの形状保持性、低伸長応力、強度が低下する。
【００１１】
共重合ゴム組成物の調製
本発明の共重合ゴム組成物は、それぞれ所定量の（Ａ）共重合ゴム、（Ｂ）エチレン系重合体、（Ｃ）充填剤並びに（Ｄ）軟化剤を、必要に応じて添加される添加剤（例えば後述するもの）とともに、通常の混練操作により配合して調製することができる。
共重合ゴム組成物の調製に際しては、バンバリーミキサー、ロールミキサー、押出機等の通常の混練機を用いることができるが、その際、（Ａ）共重合ゴムおよび（Ｂ）エチレン系重合体は、別々にあるいは予め混合して供給することができる。（Ａ）共重合ゴムと（Ｂ）エチレン系重合体とを予め混合する方法としては、例えば（イ）（Ａ）共重合ゴムと（Ｂ）エチレン系重合体とを溶融混練する方法、（ロ）（Ａ）共重合ゴムの溶液と（Ｂ）エチレン系重合体の溶液とを混合したのち、溶媒を除去する方法、（ハ）直列に連結した２つの重合槽を用い、（Ａ）共重合ゴムおよび（Ｂ）エチレン系重合体のいずれか一方の成分を最初の重合槽で製造し、その重合生成物を第二の重合槽に供給し、第二の重合槽で他方の成分を製造したのち、溶媒を除去する方法等を挙げることができる。前記（ロ）および（ハ）の方法は、特に（Ｂ）エチレン系重合体がエチレン−α−オレフィン共重合体および／または共重合ゴム（ｂ）である場合に適当である。
【００１２】
本発明の共重合ゴム組成物は、特にスポンジゴムに有用である。スポンジゴムを製造する際には、共重合ゴム組成物に対し、必要に応じて架橋剤、発泡剤等を配合してゴム配合物としたのち、例えば通常用いられる方法により架橋・発泡を行なう。
前記架橋剤としては、例えば粉末硫黄、沈降硫黄、コロイド硫黄、不溶性硫黄等の硫黄；塩化硫黄、セレン、テルル等の無機系加硫剤；モルホリンジスルフィド類、アルキルフェノールジスルフィド類、チウラムジスルフィド類、ジチオカルバミン酸類等の含硫黄有機化合物；１，１−ジ−ｔ−ブチルパーオキシ−３，３，５−トリメチルシクロヘキサン、ジ−ｔ−ブチルパーオキシド、ジクミルパーオキシド、ｔ−ブチルクミルパーオキシド、２，５−ジメチル−２，５−ジ（ｔ−ブチルパーオキシ）ヘキサン、１，３−ビス（ｔ−ブチルパーオキシ−イソプロピル）ベンゼン等の有機過酸化物類等を挙げることができる。これらの架橋剤は、単独でまたは２種以上を混合して使用することができる。
前記架橋剤の配合量は、架橋剤の種類により変わるが、例えば硫黄の場合、共重合ゴム組成物１００重量部に対して、通常、０．１〜１０重量部、好ましくは０．５〜５重量部である。
架橋剤として硫黄を用いる場合、必要に応じて加硫促進剤、加硫促進助剤をさらに配合することができる。
このような加硫促進剤としては、例えばヘキサメチレンテトラミン、アセトアルデヒドアンモニア等のアルデヒドアンモニア類；ジフェニルグアニジン、ジ（ｏ−トリル）グアニジン、ｏ−トリル−ビグアニド等のグアニジン類；チオカルバニリド、ジ（ｏ−トリル）チオウレア、Ｎ，Ｎ’−ジエチルチオウレア、テトラメチルチオウレア、トリメチルチオウレア、ジラウリルチオウレア等のチオウレア類；メルカプトベンゾチアゾール、ジベンゾチアゾールジスルフィド、２−（４−モルホリノチオ）ベンゾチアゾール、２−（２，４−ジニトロフェニル）メルカプトベンゾチアゾール、Ｎ，Ｎ’−（ジエチルチオカルバモイルチオ）ベンゾチアゾール等のベンゾチアゾール類；Ｎ−ｔ−ブチル−２−ベンゾチアジルスルフェンアミド、Ｎ，Ｎ’−ジシクロヘキシル−２−ベンゾチアジルスルフェンアミド、Ｎ，Ｎ’−ジイソプロピル−２−ベンゾチアジルスルフェンアミド、Ｎ−シクロヘキシル−２−ベンゾチアジルスルフェンアミド等のスルフェンアミド類；テトラメチルチウラムジスルフィド、テトラエチルチウラムジスルフィド、テトラブチルチウラムジスルフィド、テトラメチルチウラムモノスルフィド、ジペンタメチレンチウラムテトラスルフィド等のチウラム類；ジメチルチオカルバミン酸亜鉛、ジエチルチオカルバミン酸亜鉛、ジ−ｎ−ブチルチオカルバミン酸亜鉛、エチルフェニルジチオカルバミン酸亜鉛、ジメチルジチオカルバミン酸ナトリウム、ジメチルジチオカルバミン酸銅、ジメチルチオカルバミン酸テルル、ジメチルチオカルバミン酸鉄等のチオカルバミン酸塩類；ブチルチオキサントゲン酸亜鉛、イソプロピルキサントゲン酸亜鉛等のキサントゲン酸塩類等を挙げることができる。これらの加硫促進剤は、単独でまたは２種以上を混合して使用することができる。
前記加硫促進剤の配合量は、共重合ゴム組成物１００重量部に対して、通常、０．１〜２０重量部、好ましくは０．２〜１０重量部である。
また、前記加硫促進助剤としては、例えば酸化マグネシウム、亜鉛華、リサージ、鉛丹、鉛白等の金属酸化物；ステアリン酸、オレイン酸、ステアリン酸亜鉛等の有機酸類等を挙げることができ、特に亜鉛華、ステアリン酸が好ましい。これらの加硫促進助剤は、単独でまたは２種以上を混合して使用することができる。
前記加硫促進助剤の配合量は、共重合ゴム組成物１００重量部に対して、通常、３〜２０重量部である。
また、架橋剤として有機過酸化物類を用いる場合、必要に応じて架橋助剤をさらに配合することができる。
このような架橋助剤としては、例えば硫黄、ジペンタメチレンチウラムテトラスルフィド等の硫黄あるいは硫黄化合物；ポリエチレンジメタクリレート、ジビニルベンゼン、ジアリルフタレート、トリアリルシアヌレート、メタフェニレンビスマレイミド、トルイレンビスマレイミド等の多官能性モノマー類；ｐ−キノンオキシム、ｐ，ｐ’−ベンゾイルキノンオキシム等のオキシム化合物等を挙げることができる。これらの架橋助剤は、単独でまたは２種以上を混合して使用することができる。
さらに、前記発泡剤としては、例えば炭酸アンモニウム、重炭酸ナトリウム、無水硝酸ナトリウム等の無機発泡剤；ジニトロソペンタメチレンテトラミン、Ｎ，Ｎ’−ジメチル−Ｎ，Ｎ’−ジニトロソテレフタルアミド、ベンゼンスルホニルヒドラジド、ｐ，ｐ’−オキシビス（ベンゼンスルホニルヒドラジド）、３，３’−ジスルホンヒドラジドジフェニルスルホン、アゾイソブチロニトリル、アゾビスホルムアミド等の有機発泡剤を挙げることができる。これらの発泡剤は、単独でまたは２種以上を混合して使用することができる。
また、前記発泡剤とともに、尿素系、有機酸系、金属塩系等の発泡助剤を用いることもできる。
前記発泡剤および発泡助剤の配合量は、それらの種類や所望の発泡度により変わるが、共重合ゴム組成物１００重量部に対して、発泡剤が、通常、０．５〜２０重量部、好ましくは１〜１５重量部であり、また発泡助剤が、通常、１〜２０重量部である。
さらに、本発明の共重合ゴム組成物には、所望により、補強剤、吸湿剤、可塑剤、老化防止剤、酸化防止剤、熱安定剤、紫外線吸収剤、滑剤、離型剤、難燃剤、帯電防止剤、染顔料、防かび剤等の他の添加剤を配合することができ、また、前記以外の重合体、例えば天然ゴム、ポリイソプレンゴム、ポリブタジエンゴム、スチレン−ブタジエンゴム、アクリロニトリル−ブタジエンゴム、ブチルゴム、アクリルゴム、中・高密度ポリエチレン（密度０．９４ｇ／ｃｍ^３ 以上）、ポリプロピレン等を配合することもできる。
スポンジゴムを製造する際の各成分の配合方法および配合順序は特に限定されるものではなく、また混練機や押出機も公知のものを用いることができるが、特に、バンバリーミキサーを用いて、（Ａ）共重合ゴム、（Ｂ）エチレン系重合体、（Ｃ）充填剤、（Ｄ）軟化剤等を混練したのち、ロールミキサーを用いて、架橋剤、発泡剤等を混練することが好ましい。また、押出機を用いて配合する場合は、配合成分の一部をバンバリーミキサー等により予め混練したのち押出機に供給し、残りの配合成分を別途押出機に供給して混練することも、全配合成分を押出機に供給して混練することもできる。このような配合に際しては、前記（Ａ）〜（Ｄ）、架橋剤および発泡剤以外の配合成分は、適宜の混練段階で添加することができる。
次いで、通常のスポンジゴムの製造に使用される手順に従い、例えば、ゴム配合物を公知の架橋・発泡装置の金型内で加熱して架橋・発泡させる方法、あるいはゴム配合物を押出成形機を用いて所望形状に成形したのち架橋槽内で加熱する方法等により、所望のスポンジゴムを製造することができる。架橋・発泡時の加熱温度および加熱時間は、架橋剤や発泡剤の種類、発泡度等によって変わるが、加熱温度は、通常、１５０〜２８０℃、好ましくは１８０〜２５０℃であり、また加熱時間は、通常、２〜１５分、好ましくは３〜１０分である。
【００１３】
【実施例】
以下、実施例および比較例を挙げて、本発明をさらに具体的に説明する。但し、本発明は、これらの実施例に限定されるものではない。
実施例および比較例における各測定・評価は、下記の手順で行なった。
（１）プロピレン含有量およびブテン−１含有量（重量％）
赤外線吸収スペクトル法により測定した。
（２）よう素価
赤外線吸収スペクトル法により測定した。
（３）ム−ニ−粘度（ＭＬ_１＋４，１００℃）
測定温度１００℃、余熱時間１分、粘度を読んだときまでの時間４分で測定した。
（４）押出加工性（ガーベダイ評点）
ＡＳＴＭ−Ｄ２２３０Ａ法に準拠して評価した。
（５）形状保持性（％）
未架橋ゴム配合物を、図１に示す形状の口金を用いて押出した成形物を、２２０℃の雰囲気下で水平に７分間放置したのち、架橋・発泡させたとき、縦寸法Ｌａ と横寸法Ｌｂ との比率（Ｌａ ／Ｌｂ ）×１００により、形状保持性を評価した。
（６）スポンジ物性
▲１▼比重
日本ゴム協会標準規格・膨張ゴムの物理試験法に準拠して測定した。
▲２▼圧縮永久歪
ＪＩＳ Ｋ６３０１に準拠して、図１に示す形状の口金を用いて押出した成形物に、図１の縦方向に５０％の圧縮歪をかけ、７０℃で２００時間後の圧縮歪を測定した。
▲３▼２５％低伸長応力
スポンジゴムを、１００ｍｍ×５ｍｍ×約２ｍｍの試験片に打ち抜き、ＪＩＳ Ｋ６３０１に準拠して、２５％伸長応力を測定した。
▲４▼表面肌
スポンジゴムの表面の平滑性、つや、粘着の有無等を基準とし、目視にて、
優：○、普通：△、不良：×
の３段階で評価した。
【００１４】
実施例１〜４および比較例１〜５
表１に示す共重合ゴムおよび表２に示す（Ｂ）エチレン系重合体を用いて、表３に示す成分〔Ｉ〕を配合し、ＢＲ型バンバリーミキサー（内容量１．７リットル）を用い、回転数６０ｒｐｍ、５０℃で５分間混練して、ゴム配合物（ｉ）を得た。このゴム配合物（ｉ）に対して、表３に示す成分〔ＩＩ〕を配合し、５０℃に保持した１０インチ・ロールミキサーを用い、前ロール回転数（ｒｐｍ）／後ロール回転数（ｒｐｍ）＝２８／２２として、５分間混練して、ゴム配合物（ｉｉ）を得た。
その後、５０ｍｍ押出機にガーベダイ（ＡＳＴＭ−Ｄ２３３０に準拠したもの）を装着し、シリンダー温度６０℃、ダイ温度８０℃、スクリュウ回転数３０ｒｐｍに設定して、ゴム配合物（ｉｉ）の押出しを行って、押出加工性を評価した。
また、５０ｍｍ押出機に図１に示す形状の口金を装着し、シリンダー温度６０℃、ダイ温度８０℃、スクリュウ回転数３０ｒｐｍに設定して、ゴム配合物（ｉｉ）の押出しを行ったのち、２２０℃の熱風槽内で１０分間加熱して、架橋・発泡を行い、スポンジゴムを得た。
各ゴム配合物および各スポンジゴムについての評価結果を、表３に示す。
その結果、本発明の共重合ゴム組成物から得られるゴム配合物は、高発泡性を有し、スポンジ比重が小さく、かつ押出加工性および形状保持性に優れ、しかもそのスポンジゴムは、圧縮永久歪が小さく、低伸長応力が大きく、表面肌も良好であり、優れた特性バランスを有する。
これに対して、比較例１および比較例２に示すように、従来の共重合ゴム組成物を用いて得られるゴム配合物の場合、高発泡させると特に低伸長応力が低くなり、押出加工性および表面肌も劣っている。
また、比較例３のゴム配合物の場合、共重合ゴムのム−ニ−粘度（ＭＬ_１＋４，１００℃）が高く、押出加工性、高発泡性が劣っている。
また、比較例４のゴム配合物の場合、共重合ゴムのム−ニ−粘度（ＭＬ_１＋４，１００℃）が低く、形状保持性、圧縮永久歪、低伸長応力、表面肌がいずれも劣っている。
さらに、比較例５のゴム配合物の場合、エチレン−αーオレフィン−非共役ジエン共重合体の非共役ジエン成分が１種のみであるため、特に形状保持性が劣っている。
【００１５】
【表１】

【００１６】
【表２】

【００１７】
【表３】

【００１８】
表３において、 （＊１） 〜（＊１０） は次のとおりである。
（＊１） 旭カーボン（株）製 旭５０ＨＧ
（＊２） 出光興産（株）製 ダイアナプロセスオイルＰＷ−３８０
（＊３） 井上石灰（株）製 ベスタＰＰ
（＊４） メルカプトベンゾチアゾール
（＊５） ジメチルジチオカルバミン酸亜鉛
（＊６） ジ−ｎ−ブチルジチオカルバミン酸亜鉛
（＊７） ジペンタメチレンチウラムテトラスルフィド
（＊８） テトラエチルチウラムジスルフィド
（＊９） モルホリンジスルフィド（大内新興化学（株）製）
（＊１０） ｐ，ｐ’−オキシビス（ベンゼンスルホニルヒドラジド）
【００１９】
【発明の効果】
本発明の共重合ゴム組成物は、発泡時に高発泡性を有し、高発泡させた場合、特に低伸長応力の低下および圧縮永久歪の悪化がなくシール性能に優れるとともに、混練・押出加工性、架橋・発泡時の形状保持性、スポンジ表面肌等にも優れている。
したがって、本発明の共重合ゴム組成物は、特にスポンジゴムとして、自動車用のドアシール、ルーフサイドレール、トランクシール等のシール部材に極めて好適に使用することができるほか、航空機・船舶用シール部材、土木・建築用シール部材、一般機械・装置用シール部材、電線被覆等を含めた幅広い用途に有用である。
【図面の簡単な説明】
【図１】形状保持性と圧縮永久歪の評価に用いた口金の形状を示す図である。[0001]
[Industrial applications]
The present invention has a high foaming property at the time of foaming, and has excellent sealing performance without lowering of rigidity and deterioration of compression set at the time of high foaming, as well as excellent workability and shape retention, and a sealing member for automobiles. The present invention relates to an ethylene-α-olefin-non-conjugated diene copolymer rubber composition suitable for a wide range of uses including:
[0002]
[Prior art]
Ethylene-α-olefin-non-conjugated diene copolymer rubber is excellent in various properties such as heat resistance, ozone resistance and weather resistance, and is a sponge rubber, particularly a sealing member for a door seal, a roof side rail, a trunk seal, etc. of an automobile. The sponge rubber composed of ethylene-α-olefin-non-conjugated diene copolymer rubber is required to have a high level of performance as the performance of automobiles increases.
For example, noise such as engine noise generated during high-speed driving of automobiles, wind noise around doors, etc., leaks into the room, and rain leakage, etc., depend greatly on the sealing performance of sponge rubber around doors and are used. The sponge rubber requires extremely high sealing performance (generally, the static elastic modulus of the sponge rubber = low elongation stress is used as an index). In addition, when the door of the automobile is closed, the sponge rubber is kept in a compressed state for a long time, and therefore, it is important that the "set" due to the compression (generally expressed by the compression set as an index) is small. It has been. Therefore, the demands for the sealing performance and low "sag" of sponge rubber are becoming increasingly severe.
In recent years, since the cross-sectional shape of sponge rubber for automobile seals has become more complicated, when sponge rubber is manufactured by the normal continuous vulcanization method, it is deformed by its own weight before vulcanization and foaming is completed. Occurs and the desired shape is maintained.ComeSince there is also a problem that there is no sponge rubber, there is a need for a sponge rubber having excellent shape retention as an index of shape collapse.
In addition, cost reduction requirements for sponge rubberYesIn order to achieve this, sponge rubber is highly foamed, that is, while the foaming specific gravity is made small, there is a new demand for a sponge rubber which is excellent in the above-mentioned high sealing performance, low "set" property, shape retention property and the like. . Further, in addition to the above-mentioned various properties, it is necessary that the material has excellent workability such as kneading workability, roll workability, and extrusion workability.
Under such circumstances, for example, JP-A-3-20339 discloses that the ethylene / α-olefin-non-conjugated diene copolymer rubber has an ethylene / α-olefin weight ratio of 73/27 to 40/60, Mooney viscosity (ML _{1 + 4} ,121 ° C.) and a non-conjugated diene content of 10 to 36 in terms of prime value like copolymer rubber, and a method of increasing the molecular weight to improve compression set. However, in such a method, since the molecular weight is high, the compound viscosity becomes high and the foaming of the compound becomes difficult when the compounding amount of carbon black and oil is normal. Moreover, in order to achieve high foaming, a large amount of oil needs to be added, and thus there is a drawback that shape retention is reduced and low elongation stress is reduced.
On the other hand, in a rubber composition comprising an ethylene-α-olefin-non-conjugated diene copolymer rubber, a high molecular weight copolymer rubber component and a low molecular weightCopolymerizationAttempts have also been made to improve the compression set by combining with a rubber component. For example, Japanese Unexamined Patent Publication No. 4-80245 discloses that a copolymer comprising a low molecular weight copolymer and a high molecular weight copolymer has an ethylene / α-olefin weight ratio of 73/27 to 40/60 and a diolefin content of the copolymer. The mixture has an iodine value of 10 to 36, the iodine value ratio of the low-molecular weight copolymer to the high-molecular weight copolymer is 1.1 / 1 to 4/1, and the Muni-viscosity ( ML_{1 + 4}, 121 ° C.) of 50 to 100, and JP-A-3-146531 discloses a rubber composition for a sponge comprising a copolymer rubber A and a copolymer rubber B, wherein the copolymer rubber A is ethylene / α- The olefin weight ratio is 73/27 to 40/60, the content of the non-conjugated diene is 8 to 33 in iodine value, and the Mooney viscosity (ML)_{1 + 4}, 121 ° C.) is 130 to 195, and the copolymer rubber B has an ethylene / α-olefin weight ratio of 73/27 to 40/60 and a non-conjugated diene content of 10 to 36 in iodine value. , And Mooney viscosity (ML_{1 + 4}, 121 ° C.) of 20 to 55 are disclosed, respectively, and the present applicant also discloses that the ethylene / α-olefin weight ratio is 50/50 to 80/20 and that the non-conjugated diene is contained. The amount at which the amount becomes 5 to 40 in iodine value, the Mooney viscosity (ML)_{1 + 4}, 100 ° C.) is from 60 to 300, and the difference in α-olefin content between the low molecular weight side and the high molecular weight side of the copolymer rubber and the difference in iodine value between the low molecular weight side and the high molecular weight side of the copolymer rubber are A specified rubber composition (see JP-A-4-76011) has been proposed. However, these compositions have good compression set, but are not always satisfactory in terms of overall properties as sponge rubber including low elongation stress when highly foamed.
Further, Japanese Patent Publication No. 2-62582 discloses that ethylene, α-olefin, 5-ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB) are used, and the ENB / VNB molar ratio is 1 /. A copolymer rubber having a specific molecular weight and a specific molecular weight distribution is disclosed in which the content of ENB and VNB is 1 to 20/1, and the total content of ENB and VNB is 2 to 40 in elementary value like a copolymer. However, the copolymer rubber has good roll processability and extrusion processability, and in particular, sponge rubber having a smooth surface of the extruded product can be obtained. However, when the foam is highly foamed, the compression set is large and the elongation is low. There is a disadvantage that the stress is small.
That is, in the conventional sponge rubber and sponge rubber composition, when highly foamed, the disadvantage that the low elongation stress, which is an index of the sealing performance, is small, has not been solved. The basic problem of improving low elongation stress without deteriorating other properties such as workability and the like remains unsolved.
[0003]
[Problems to be solved by the invention]
The present invention has high foaming property at the time of foaming, and when highly foamed, ethylene which is excellent in sealing performance without lowering of low elongation stress and deterioration of compression set, and also excellent in processability and shape retention. An object of the present invention is to provide an α-olefin-non-conjugated diene copolymer rubber composition.
[0004]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by combining a specific ethylene-α-olefin-non-conjugated diene copolymer rubber with a specific other ethylene-based polymer, high foaming during foaming has been achieved. Having a foaming property, when highly foamed, it is possible to obtain a rubber composition which is excellent in sealing performance without lowering of low elongation stress and deterioration of compression set, and also excellent in processability and shape retention. As a result, the present invention has been completed.
The present invention
(A) The ethylene / α-olefin weight ratio is 40/60 to 70/30, (a) ethylidene norbornene and (b) dicyclopentadiene as non-conjugated dienes, and α, ω having 8 to 20 main chain carbon atoms. -Diene, and the content of each non-conjugated diene is such that the ethylidene norbornene has an elementary value of 20 to 60 like an ethylene-α-olefin-non-conjugated diene copolymer. The amount of pentadiene to be 1 to 20 in the prime value as in the ethylene-α-olefin-non-conjugated diene copolymer, and the amount of α, ω-diene having 8 to 20 carbon atoms in the main chain is 0.1% of all the monomer components. And a Mooney viscosity (ML)_{1 + 4}, 100 ° C.) 50 to 150 parts by weight of an ethylene-α-olefin-nonconjugated diene copolymer,
(B) Low density polyethylene, melting point60-120 ° CEthylene-α-olefin copolymer having a melting point of60-120 ° CAt least one other ethylene-based polymer selected from the group of ethylene-α-olefin-non-conjugated diene copolymer of 10 to 100 parts by weight,
(C) 30 to 200 parts by weight of a filler, and
(D) 30 to 150 parts by weight of a softener
An ethylene-α-olefin-non-conjugated diene copolymer rubber composition characterized by comprising
Is the gist.
[0005]
Hereinafter, the present invention will be described in detail. This will clarify the objects, configurations and effects of the present invention.
(A) Ethylene-α-olefin-non-conjugated diene copolymer
(A) Ethylene-α-olefin-non-conjugated diene copolymer (A) used in the ethylene-α-olefin-non-conjugated diene copolymer rubber composition of the present invention (hereinafter referred to as “copolymer rubber composition”) Hereinafter, “(A) copolymer rubber”) is composed of ethylene, α-olefin, non-conjugated diene (a) ethylidene norbornene and (b) dicyclopentadiene, and α, having 8 to 20 main chain carbon atoms. It is a copolymer composed of any one of ω-dienes.
(A) In the copolymer rubber, examples of the α-olefin include α-olefins having 3 to 12 carbon atoms, and specifically, propylene, butene-1, 3-methylbutene-1, pentene-1, Examples thereof include 3-methylpentene-1, 4-methylpentene-1, 3-ethylpentene-1, hexene-1, octene-1, decene-1, and dodecene-1, and propylene is particularly preferred. These α-olefins can be used alone or in combination of two or more.
(A) Ethylene / α in copolymer rubber−The olefin weight ratio is between 40/60 and 70/30, preferably between 50/50 and 65/35. In this case, ethylene / α−If the olefin weight ratio is less than 40/60, the filling in the copolymer rubber compositionAgentIs insufficiently dispersed, sponge surface skin is impaired, and the strength of sponge rubber is also reduced. On the other hand, if it exceeds 70/30, compression set of sponge rubber at low temperatures is impaired.
Among non-conjugated dienes, α, ω-diene having a main chain carbon number of 8 to 20 (hereinafter referred to as “α, ω-diene”) is represented by the following formula (1).
[0006]
Embedded image

[0007]
[In the formula (1), each R 1 may be the same or different from each other, and may be a hydrogen atom, a saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, an unsaturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, It represents a saturated alicyclic hydrocarbon group having 1 to 10 carbon atoms or an unsaturated alicyclic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 4 to 16. ]
Specific examples of such α, ω-diene include 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,11-dodecadiene, 1,13-tetradecadiene, and 1,15-diene. Hexadecadienes, 1,17-octadecadienes, 1,19-icosadienes, 3,6-dimethyl-1,7-octadienes, 4,5-dimethyl-1,7-octadienes, 5-methyl-1,8- Nonadiene and the like can be mentioned, and 1,7-octadiene and 1,9-decadiene are particularly preferable. The α, ω-dienes can be used alone or in combination of two or more.
Regarding the content of each non-conjugated diene in the (A) copolymer rubber, the content of ethylidene norbornene is such that the prime value is 20 to 60, preferably 25 to 45 as in the (A) copolymer rubber. It is. In this case, if the content of ethylidene norbornene is less than 20 in iodine value, the compression set at low temperature of the sponge rubber obtained from the copolymer rubber composition is impaired, and the crosslinking speed becomes low, so that the surface texture due to gas release is reduced. When the iodine value exceeds 60, "dust" and "gel" are liable to occur during kneading and extrusion, and the balance between the crosslinking speed and the foaming speed is poor. It is difficult to make the copolymer rubber composition highly foamed, and the cost increases.
The content of dicyclopentadiene is in an amount of 1 to 20, preferably 4 to 15 in elementary value like the copolymer rubber (A). In this case, if the content of dicyclopentadiene is less than 1 in iodine value, the shape retention of the sponge rubber obtained from the copolymer rubber composition is reduced. descend.
The content of α, ω-diene is 0.05 to 2% by weight, preferably 0.1 to 1% by weight of all monomer components. In this case, if the content of α, ω-diene is less than 0.05% by weight, the shape retention of the sponge rubber is reduced, while if it exceeds 2% by weight, the extrudability is reduced.
The non-conjugated diene of the (A) copolymer rubber in the present invention contains (a) ethylidene norbornene and (b) any one of dicyclopentadiene and α, ω-diene. In this case, When only the non-conjugated diene (a) ethylidene norbornene is used, shape retention is significantly reduced.
(A) Mooney viscosity (ML) of copolymer rubber_{1 + 4}, 100 ° C.) is from 50 to 150, preferably from 60 to 140. In this case, (A) the Mooney viscosity (ML) of the copolymer rubber_{1 + 4}, 100 ° C.) is less than 50, the shape retention of the sponge rubber obtained from the copolymer rubber composition is deteriorated, and the surface skin is deteriorated due to outgassing during crosslinking / foaming. On the other hand, if the elongation stress is less than 150, high foaming becomes difficult, and the kneading processability and extrusion processability also deteriorate.
In the present invention, the copolymer rubber (A) can be used alone or in combination of two or more.
In the present invention, by using the (A) copolymer rubber in combination with the (B) ethylene polymer described below, a high foaming property, shape retention, kneading / extrusion can be obtained with respect to the copolymer rubber composition. An excellent property balance can be imparted, including processability, crosslinking speed, compression set, low elongation stress, surface skin of sponge rubber, and the like.
[0008]
(A) The copolymer rubber is prepared by a usual polymerization method using a medium / low pressure method, for example, a Ziegler-Natta catalyst comprising a transition metal compound and an organometallic compound in an appropriate solvent, for example, at least one solvent-soluble vanadium compound. Ethylene, α in the presence of a catalyst comprising at least one organoaluminum compound;−Olefin and non-conjugated diene can be produced by a method in which hydrogen is supplied as a molecular weight regulator, if necessary, by polymerization. The polymerization can be carried out by a gas phase method (fluidized bed or stirred bed) or a liquid phase method. (Slurry method or solution method).
VOCl is used as the solvent-soluble vanadium compound.₃, VCl₄, VOCl₃Or
VCl₄The reaction product of at least one of the above with an alcohol is preferred. In this case, examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, n-hexanol, n-octanol, 2-ethylhexanol, n-decanol, and n-decanol. Dodecanol and the like can be mentioned, among which alcohols having 3 to 8 carbon atoms are preferable.
Examples of the organoaluminum compound include, for example, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride, butylaluminum sesquichloride, ethylaluminum dichloride, butylaluminum Dichloride, methylaluminoxane, which is a reaction product of trimethylaluminum and water, and the like, particularly ethylaluminum sesquichloride, butylaluminum sesquichloride, a mixture of ethylaluminum sesquichloride and butylaluminum sesquichloride, triisobutylaluminum Mixtures with butyl aluminum sesquichloride are preferred.
As the solvent, a hydrocarbon solvent is usually used, and preferable hydrocarbon solvents are n-pentane, n-hexane, n-heptane, n-octane, isooctane, cyclohexane and the like. These hydrocarbon solvents can be used alone or in combination of two or more.
[0009]
(B) Other ethylene polymers
Next, (B) the other ethylene-based polymer (hereinafter referred to as “(B) ethylene-based polymer”) used in the copolymer rubber composition of the present invention is a low-density polyethylene having a melting point.60-120 ° CEthylene-α-olefin copolymer (hereinafter referred to as “ethylene-α-olefin copolymer”) and a melting point of60-120 ° CAt least one selected from the group consisting of ethylene-α-olefin-non-conjugated diene copolymer (hereinafter, referred to as “copolymer rubber (b)”). However, the melting point here is determined by DSC (differential scanning calorimetry) measurement.
(B) In the ethylene polymer, the density of the low-density polyethylene is usually 0.935 g / cm.^ThreeThe following is a preferable density range of 0.910 to 0.935 g / cm.^ThreeIt is.
As the low-density polyethylene, for example, a low-density polyethylene obtained by a high-pressure method (hereinafter, referred to as “LDPE”) or a linear low-density polyethylene obtained by a medium / low-pressure method (hereinafter, referred to as “L-LDPE”). Although any of these can be used.
LDPE by the high-pressure method can be produced by a gas phase method or a slurry method (in an aqueous medium or an organic medium), and L-LDPE by the medium / low pressure method can be produced by the gas-phase method (fluidized bed or stirred bed). It can also be produced by a liquid phase method (slurry method or solution method).
In the present invention, the low-density polyethylene can be used alone or in combination of two or more.
Further, as the α-olefin used in the ethylene-α-olefin copolymer and the copolymer rubber (b), for example, an α-olefin having 3 to 12 carbon atoms, specifically, propylene, butene-1, 3-methylbutene -1, pentene-1, 3-methylpentene-1, 4-methylpentene-1, 3-ethylpentene-1, hexene-1, octene-1, decene-1, dodecene-1, and the like, Particularly, butene-1 is preferred. These α-olefins can be used alone or in combination of two or more.
Examples of the non-conjugated diene used in the copolymer rubber (b) include ethylidene norbornene, vinyl norbornene, dicyclopentadiene, 1,4-hexadiene, 1,7-octadiene, 1,9-decadiene, and 1,11. -Dodecadienes, 1,13-tetradecadienes, 1,15-hexadecadienes, 1,17-octadecadienes, 1,19-icosadienes, 3,6-dimethyl-1,7-octadienes, 4,5-dimethyl Examples thereof include -1,7-octadiene, 5-methyl-1,8-nonadiene, and particularly preferred are ethylidene norbornene, dicyclopentadiene, 1,7-octadiene, and 1,9-decadiene. These non-conjugated dienes can be used alone or in combination of two or more.
The ethylene / α-olefin weight ratio in the ethylene-α-olefin copolymer and the copolymer rubber (b) is usually 70/30 to 90/10, preferably 78/22 to 90/10. In this case, if the ethylene / α-olefin weight ratio is less than 70/30, the low elongation stress of the sponge rubber obtained from the copolymer rubber composition tends to decrease. Due to the difference in reactivity with α-olefin, it is difficult to obtain a homogeneous ethylene-α-olefin copolymer and copolymer rubber (b).
The melting points of the ethylene-α-olefin copolymer and the copolymer rubber (b) are 50 ° C. or higher, preferably 60 to 120 ° C. In this case, when the melting points of the ethylene-α-olefin copolymer and the copolymer rubber (b) are less than 50 ° C., the low elongation stress of the sponge rubber obtained from the copolymer rubber composition of the present invention decreases.
The content of the non-conjugated diene in the copolymer rubber (b) is preferably such that the prime value is 2 to 40, and particularly preferably 3 to 20, as in the case of the copolymer rubber (b). The ethylene-α-olefin copolymer and the copolymer rubber (b) may be prepared by a usual polymerization method using a medium / low pressure method, for example, ethylene and α-olefin may be further unconjugated in the case of the copolymer rubber (b). It can be produced by a method in which a diene is added and polymerization is carried out in the same manner as in the case of the copolymer rubber (A).
In the present invention, the ethylene-α-olefin copolymer and the copolymer rubber (b) can be used alone or in combination of two or more.
The blending amount of the ethylene polymer (B) in the present invention is 10 to 100 parts by weight, preferably 15 to 70 parts by weight, based on 100 parts by weight of the (A) copolymer rubber. In this case, if the blending amount of the (B) ethylene polymer is less than 10 parts by weight, the sponge rubber obtained by highly foaming the copolymer rubber composition has low elongation stress, surface texture, and extrusion of the copolymer rubber composition. If the processability is impaired, on the other hand, if it exceeds 100 parts by weight, the high foamability, kneading processability, and extrusion processability of the copolymer rubber composition will be impaired.
[0010]
(C) Filler
Next, the filling used in the copolymer rubber composition of the present inventionAgentCarbon blacks such as SRF, FEF, HAF, ISAF, SAF, FT, and MT; and inorganic fillers such as fine silica particles, calcium carbonate, magnesium carbonate, clay, and talc.AgentAnd the like. These fillingsAgentCan be used alone or in combination of two or more.
Filling in the present inventionAgentIs from 30 to 200 parts by weight, and preferably from 50 to 150 parts by weight, based on 100 parts by weight of the copolymer rubber (A). In this case, fillingAgentIf the blending amount is less than 30 parts by weight, the low elongation stress and strength of the sponge rubber obtained from the copolymer rubber composition decrease, while if it exceeds 200 parts by weight, the melt viscosity of the copolymer rubber composition increases, High foaming property is impaired.
(D) Softener
Next, examples of the softening agent used in the copolymer rubber composition of the present invention include process oils such as aromatic oils, naphthenic oils, and paraffin oils commonly used for rubber; and vegetable oils such as palm oil. it can. Of these softeners, process oils are preferred, and paraffin oil is particularly preferred. These softeners can be used alone or in combination of two or more.
The compounding amount of the softener in the present invention is 30 to 150 parts by weight, preferably 40 to 100 parts by weight, based on 100 parts by weight of the copolymer rubber (A). In this case, if the compounding amount of the softener is less than 30 parts by weight, the kneading processability and the extruding processability of the copolymer rubber composition are reduced, while if it exceeds 150 parts by weight, the sponge rubber obtained from the copolymer rubber composition is obtained. In shape retention, low elongation stress, and strength.
[0011]
Preparation of copolymer rubber composition
The copolymer rubber composition of the present invention comprises (A) a copolymer rubber, (B) an ethylene-based polymer, and (C)AgentIn addition, it can be prepared by blending (D) a softener together with additives (for example, those described below) which are added as necessary by a usual kneading operation.
In preparing the copolymer rubber composition, a usual kneader such as a Banbury mixer, a roll mixer, and an extruder can be used. In this case, (A) the copolymer rubber and (B) the ethylene-based polymer are They can be supplied separately or premixed. Examples of the method of previously mixing (A) the copolymer rubber and (B) the ethylene polymer include (a) a method of melt-kneading the (A) copolymer rubber and (B) the ethylene polymer, A) a method of mixing a solution of (A) a copolymer rubber and a solution of (B) an ethylene-based polymer and then removing the solvent, (c) using two polymerization tanks connected in series, Either the rubber or the component (B) of the ethylene polymer was produced in the first polymerization vessel, the polymerization product was supplied to the second polymerization vessel, and the other component was produced in the second polymerization vessel. Thereafter, a method of removing the solvent can be used. The methods (b) and (c) are particularly suitable when the (B) ethylene polymer is an ethylene-α-olefin copolymer and / or copolymer rubber (b).
[0012]
The copolymer rubber composition of the present invention is particularly useful for sponge rubber. When producing a sponge rubber, a crosslinking agent, a foaming agent and the like are added to the copolymer rubber composition as needed to form a rubber compound, and then, for example, crosslinking and foaming are performed by a commonly used method.
Examples of the crosslinking agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur; inorganic vulcanizing agents such as sulfur chloride, selenium, and tellurium; morpholine disulfides, alkylphenol disulfides, thiuram disulfides, and dithiocarbamic acids. Sulfur-containing organic compounds such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2, Organic peroxides such as 5-dimethyl-2,5-di (t-butylperoxy) hexane and 1,3-bis (t-butylperoxy-isopropyl) benzene can be exemplified. These crosslinking agents can be used alone or in combination of two or more.
The amount of the crosslinking agent varies depending on the type of the crosslinking agent. For example, in the case of sulfur, the amount is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the copolymer rubber composition. Parts by weight.
When sulfur is used as a cross-linking agent, a vulcanization accelerator and a vulcanization accelerator may be further added as necessary.
Examples of such a vulcanization accelerator include aldehyde ammonias such as hexamethylenetetramine and acetaldehyde ammonia; guanidines such as diphenylguanidine, di (o-tolyl) guanidine and o-tolyl-biguanide; thiocarbanilide and di (o- Thioureas such as tolyl) thiourea, N, N'-diethylthiourea, tetramethylthiourea, trimethylthiourea, dilaurylthiourea; mercaptobenzothiazole, dibenzothiazole disulfide, 2- (4-molEBenzothiazoles such as (linothio) benzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, N, N ′-(diethylthiocarbamoylthio) benzothiazole; Nt-butyl-2-benzothiazylsulfur Sulfonamides such as phenamide, N, N'-dicyclohexyl-2-benzothiazylsulfenamide, N, N'-diisopropyl-2-benzothiazylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide; Phenamides; thiurams such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide; zinc dimethylthiocarbamate, diethylthiocarb Thiocarbamic acid salts such as zinc mitinate, zinc di-n-butylthiocarbamate, zinc ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate and iron dimethylthiocarbamate; butylthio Xanthates such as zinc xanthate and zinc isopropylxanthate may be mentioned. These vulcanization accelerators can be used alone or in combination of two or more.
The compounding amount of the vulcanization accelerator is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the copolymer rubber composition.
Examples of the vulcanization accelerating aid include metal oxides such as magnesium oxide, zinc white, litharge, leadtan, lead white; and organic acids such as stearic acid, oleic acid, and zinc stearate. Particularly preferred are zinc white and stearic acid. These vulcanization accelerators can be used alone or in combination of two or more.
The compounding amount of the vulcanization accelerator is usually 3 to 20 parts by weight based on 100 parts by weight of the copolymer rubber composition.
When organic peroxides are used as a cross-linking agent, a cross-linking aid can be further added as necessary.
Examples of such a crosslinking assistant include sulfur and sulfur compounds such as sulfur and dipentamethylenethiuram tetrasulfide; polyethylene dimethacrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, metaphenylene bismaleimide, toluylene bismaleimide and the like. And oxime compounds such as p-quinone oxime and p, p'-benzoylquinone oxime. These crosslinking aids can be used alone or in combination of two or more.
Examples of the foaming agent include inorganic foaming agents such as ammonium carbonate, sodium bicarbonate, and anhydrous sodium nitrate; dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosoterephthalamide, benzenesulfonyl Organic foaming agents such as hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide), 3,3'-disulfone hydrazide diphenyl sulfone, azoisobutyronitrile, azobisformamide and the like can be mentioned. These foaming agents can be used alone or in combination of two or more.
In addition, a urea-based, organic acid-based, metal salt-based, or other foaming aid can be used together with the foaming agent.
The amount of the foaming agent and the foaming auxiliary varies depending on the type and the desired degree of foaming, but the foaming agent is usually 0.5 to 20 parts by weight, based on 100 parts by weight of the copolymer rubber composition. Preferably it is 1 to 15 parts by weight, and the foaming aid is usually 1 to 20 parts by weight.
Further, the copolymer rubber composition of the present invention may optionally be reinforced.AgentContains other additives such as moisture absorbent, plasticizer, anti-aging agent, antioxidant, heat stabilizer, ultraviolet absorber, lubricant, mold release agent, flame retardant, antistatic agent, dye, pigment and fungicide And polymers other than those described above, for example, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, acrylic rubber, medium / high density polyethylene (density 0.94 g / cm³Above), polypropylene and the like can be blended.
The method and order of compounding each component when producing the sponge rubber are not particularly limited, and a kneader or an extruder can also be a known one. In particular, using a Banbury mixer, A) copolymer rubber, (B) ethylene polymer, (C) fillingAgent, (D) after kneading the softener and the like, it is preferable to knead the crosslinking agent, the foaming agent and the like using a roll mixer. In addition, when compounding using an extruder, it is also possible to knead a part of the compounded components in advance by kneading them with a Banbury mixer or the like, and then supply the extruder, and then separately supply the remaining compounded components to the extruder and knead them. The components can be supplied to an extruder and kneaded. In such compounding, the compounding components other than the above (A) to (D), the crosslinking agent and the foaming agent can be added at an appropriate kneading stage.
Then, according to the procedure used for the production of ordinary sponge rubber, for example, a method of crosslinking and foaming the rubber compound by heating in a mold of a known crosslinking and foaming apparatus, or an extruder for the rubber compound. A desired sponge rubber can be produced by a method of forming the desired sponge rubber into a desired shape and then heating in a crosslinking tank. The heating temperature and the heating time at the time of crosslinking / foaming vary depending on the type of the crosslinking agent and the foaming agent, the degree of foaming, and the like. Is usually 2 to 15 minutes, preferably 3 to 10 minutes.
[0013]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.
Each measurement and evaluation in Examples and Comparative Examples was performed according to the following procedures.
(1) Propylene content and butene-1 content (% by weight)
It was measured by an infrared absorption spectrum method.
(2) Iodine value
It was measured by an infrared absorption spectrum method.
(3) Mooney viscosity (ML_{1 + 4}, 100 ° C)
The measurement was performed at a measurement temperature of 100 ° C., a residual heat time of 1 minute, and a time of 4 minutes until the viscosity was read.
(4) Extrusion processability (Garbe die rating)
The evaluation was performed in accordance with the ASTM-D2230A method.
(5) Shape retention (%)
A molded product obtained by extruding an uncrosslinked rubber compound using a die having the shape shown in FIG. 1 was allowed to stand horizontally in an atmosphere of 220 ° C. for 7 minutes, and then crosslinked and foamed. The shape retention was evaluated by the ratio (La / Lb) × 100 with Lb 2.
(6) Physical properties of sponge
(1) Specific gravity
It was measured in accordance with the Japan Rubber Association Standards and the physical test method for expanded rubber.
(2) Compression set
In accordance with JIS K6301, a molded product extruded using a die having the shape shown in FIG. 1 was subjected to a compressive strain of 50% in the longitudinal direction of FIG. 1, and the compressive strain after 200 hours at 70 ° C. was measured.
(3) 25% low elongation stress
The sponge rubber was punched out into a test piece of 100 mm × 5 mm × about 2 mm, and a 25% elongation stress was measured according to JIS K6301.
▲ 4 ▼ Surface skin
Visually, based on the smoothness of the surface of the sponge rubber, gloss, the presence or absence of adhesion, etc.
Excellent: ○, normal: △, bad: ×
Was evaluated in three steps.
[0014]
Examples 1-4 and Comparative Examples 1-5
Using the copolymer rubber shown in Table 1 and the ethylene-based polymer (B) shown in Table 2, the component [I] shown in Table 3 was blended, and a BR type Banbury mixer (1.7 liters in content) was used. The mixture was kneaded at a rotation speed of 60 rpm at 50 ° C. for 5 minutes to obtain a rubber compound (i). To the rubber compound (i), the component [II] shown in Table 3 was blended, and using a 10-inch roll mixer maintained at 50 ° C., the number of rotations of the front roll (rpm) / the number of rotations of the rear roll (rpm) ) = 28/22, and kneaded for 5 minutes to obtain a rubber compound (ii).
Then, a garbage die (according to ASTM-D2330) was attached to a 50 mm extruder, and the rubber compound (ii) was extruded by setting the cylinder temperature to 60 ° C., the die temperature to 80 ° C., and the screw rotation speed to 30 rpm. And extrudability were evaluated.
A die having the shape shown in FIG. 1 was attached to a 50 mm extruder, the cylinder temperature was set to 60 ° C., the die temperature was set to 80 ° C., and the screw rotation speed was set to 30 rpm. After extruding the rubber compound (ii), 220 The mixture was heated in a hot air bath at a temperature of 10 ° C. for 10 minutes to perform crosslinking and foaming to obtain a sponge rubber.
Table 3 shows the evaluation results for each rubber compound and each sponge rubber.
As a result, the rubber compound obtained from the copolymer rubber composition of the present invention has high foamability, low sponge specific gravity, and excellent extrudability and shape retention, and the sponge rubber is compressed The strain is small, the low elongation stress is large, the surface skin is good, and it has an excellent property balance.
On the other hand, as shown in Comparative Examples 1 and 2, in the case of a rubber compound obtained by using a conventional copolymer rubber composition, when foaming is high, the low elongation stress is particularly low, and the extrusion processability is low. And the surface skin is also inferior.
In addition, in the case of the rubber compound of Comparative Example 3, the Mooney viscosity (ML)_{1 + 4}, 100 ° C), and extrudability and high foaming properties are inferior.
Further, in the case of the rubber compound of Comparative Example 4, the Mooney viscosity (ML)_{1 + 4}, 100 ° C), shape retention, compression set, low elongation stress, and surface skin are all inferior.
Furthermore, in the case of the rubber compound of Comparative Example 5, since the ethylene-α-olefin-nonconjugated diene copolymer has only one non-conjugated diene component, the shape retention property is particularly poor.
[0015]
[Table 1]

[0016]
[Table 2]

[0017]
[Table 3]

[0018]
In Table 3, (* 1) to (* 10) are as follows.
(* 1) Asahi Carbon Co., Ltd. Asahi 50HG
(* 2) Diana Process Oil PW-380 manufactured by Idemitsu Kosan Co., Ltd.
(* 3) Vesta PP manufactured by Inoue Lime Co., Ltd.
(* 4) Mercaptobenzothiazole
(* 5) Zinc dimethyldithiocarbamate
(* 6) Zinc di-n-butyldithiocarbamate
(* 7) Dipentamethylenethiuram tetrasulfide
(* 8) Tetraethylthiuram disulfide
(* 9) moleELindi sulfide (Ouchi Shinko Chemical Co., Ltd.)
(* 10) p, p'-oxybis (benZeNsulfonyl hydrazide)
[0019]
【The invention's effect】
The copolymer rubber composition of the present invention has a high foaming property at the time of foaming, and when highly foamed, particularly has excellent sealing performance without lowering of low elongation stress and deterioration of compression set, and also has excellent kneading and extrusion processability. Also excellent in shape retention during crosslinking and foaming, sponge surface skin, etc.
Therefore, the copolymer rubber composition of the present invention can be used as a sponge rubber, particularly as a seal member for automobile door seals, roof side rails, trunk seals, etc. It is useful for a wide range of applications including seal members for civil engineering and construction, seal members for general machinery and equipment, and wire coating.
[Brief description of the drawings]
FIG. 1 is a view showing the shape of a die used for evaluation of shape retention and compression set.

Claims (5)

(A) The ethylene / α-olefin weight ratio is 40/60 to 70/30, (a) ethylidene norbornene and (b) dicyclopentadiene as non-conjugated dienes, and α, ω having 8 to 20 main chain carbon atoms. -Diene, and the content of each non-conjugated diene is such that the ethylidene norbornene has an elementary value of 20 to 60 like ethylene-α-olefin-non-conjugated diene copolymer. The amount of pentadiene is from 1 to 20 in the prime value like ethylene-α-olefin-non-conjugated diene copolymer, and the amount of α, ω-diene having 8 to 20 carbon atoms in the main chain is 0.1% of all the monomer components. 100 to 50 parts by weight of an ethylene-α-olefin-nonconjugated diene copolymer having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 50 to 150%,
(B) at least one selected from the group consisting of low-density polyethylene, an ethylene-α-olefin copolymer having a melting point of 60 to 120 ° C, and an ethylene-α-olefin-non-conjugated diene copolymer having a melting point of 60 to 120 ° C. 10 to 100 parts by weight of another ethylene-based polymer,
An ethylene-α-olefin-non-conjugated diene copolymer rubber composition comprising (C) 30 to 200 parts by weight of a filler and (D) 30 to 150 parts by weight of a softener. (A) an ethylene / alpha-olefin weight ratio in component 5 0/5 0 according to claim 1, characterized in that a 65/35 ethylene -α- olefin - non-conjugated diene copolymer rubber composition. The ethylene-α-olefin-nonconjugated diene copolymer according to claim 1 or 2, wherein the amount of the component (B) is 10 to 100 parts by weight based on 100 parts by weight of the component (A). Polymerized rubber composition. The ethylene-α-olefin-non-conjugated diene copolymer rubber composition according to any one of claims 1 to 3, wherein the component (b) is 1,9-decadiene. A sponge rubber comprising the ethylene-α-olefin-non-conjugated diene copolymer rubber composition according to any one of claims 1 to 4.

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