JP4615112B2

JP4615112B2 - Rubber foam

Info

Publication number: JP4615112B2
Application number: JP2000340418A
Authority: JP
Inventors: 豊栗生
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2000-11-08
Filing date: 2000-11-08
Publication date: 2011-01-19
Anticipated expiration: 2020-11-08
Also published as: JP2002146072A

Description

【０００１】
【発明の技術分野】
本発明は、柔軟でかつ低圧縮にても止水性に優れる低密度のＥＰＤＭ系発泡体であり、シール用途等に好適なゴム系発泡体に関する。
【０００２】
【従来の技術】
従来、各種のＥＰＤＭ系加硫発泡体が知られており、その優れたクッション性や圧縮性等に基づいて止水等の各種シール材として多用されている。その止水用途では曲げ部の形成性等の点より柔軟性に優れることが有利である。しかしながら従来の発泡体では軟化剤を多用して柔軟性を向上させた場合、圧縮応力の低下で止水性能が低下する問題点があった。
【０００３】
【発明の技術的課題】
本発明は、作業に有利な柔軟性をもたせつつ止水性能にも優れる低密度なＥＰＤＭ系発泡体を形成できるゴム系加硫発泡組成物の開発を課題とする。
【０００４】
【課題の解決手段】
本発明のゴム系発泡体は、ＥＰＤＭ、加硫剤、発泡剤及びＥＰＤＭ１００重量部あたり１０〜３５重量部の、ロウ状のエチレン・プロピレン系共重合体からなる軟化剤を少なくとも成分とする混和物からなるゴム系加硫発泡組成物にて形成した密度０．２００ｇ／ｃｍ^３以下の加硫発泡体からなることを特徴としている。
また、本発明のゴム系発泡体では、止水用シール材として用いられ、５０〜６０％の圧縮状態で漏水を生じないことが好適である。
【０００５】
【発明の効果】
本発明によれば、軟化剤にて軟化させたことにより気泡サイズの細かい低密度発泡を可能としつつＥＰＤＭ系発泡体のゴム物性によるクッション性や圧縮性等の性能を保持して作業に有利な柔軟性をもたせることができ、かつ発泡体に良好な取扱性を維持した微粘着性をもたせてその微粘着力を介し被シール材に圧着でき、その圧着にて被シール材とシール材の界面が良密着して高度の止水性能を示し、５０〜６０％程度の低い圧縮状態にても高度なシール性能を示すＥＰＤＭ系発泡体を得ることができる。
【０００６】
【発明の実施形態】
本発明によるゴム系加硫発泡組成物は、ＥＰＤＭ、加硫剤、発泡剤及びＥＰＤＭ１００重量部あたり１０〜３５重量部の軟化剤を少なくとも成分とする混和物からなる。そのＥＰＤＭとしては、適宜なエチレン・プロピレン・ジエンゴムの１種又は２種以上を用いることができ、その種類について特に限定はない。ゴム物性による圧縮性等の性能の調節性や混和性等の点よりはムーニー粘度（ＭＬ１＋４、１００℃）が５〜３０、就中８〜２５のＥＰＤＭが好ましく用いうる。
【０００７】
加硫剤についても適宜なものを１種又は２種以上用いることができ、特に限定はない。ちなみにその例としては、硫黄や硫黄化合物類、セレンや酸化マグネシウム、一酸化鉛や酸化亜鉛、有機過酸化物類やポリアミン類、Ｐ−キノンジオキシムやＰ，Ｐ'-ジベンゾイルキノンジオキシムの如きオキシム類やＰ−ジニトロソベンジンの如きニトロソ化合物類、アルキルフェノール・ホルムアルデヒド樹脂、メラミン・ホルムアルデヒド縮合物の如き樹脂類や安息香酸アンモニウムの如きアンモニウム塩類などがあげられる。
【０００８】
得られる発泡体の加硫性や発泡性による耐久性等の物性などの点よりは、硫黄や硫黄化合物類、特に硫黄が好ましく用いうる。加硫剤の使用量は、その種類に基づく加硫効率などに応じて適宜に決定することができる。ちなみに硫黄系の場合、ＥＰＤＭ１００重量部あたり通例０．１〜１０重量部、就中０．５〜５重量部が用いられる。
【０００９】
また発泡剤としても適宜なものを１種又は２種以上用いることができ、特に限定はない。ちなみにその例としては、炭酸アンモニウムや炭酸水素アンモニウム、炭酸水素ナトリウムや亜硝酸アンモニウム、水素化ホウ素ナトリウムやアジド類などの無機系発泡剤があげられる。またトリクロロモノフルオロメタンやジクロロモノフルオロメタンの如きフッ化アルカン、アゾビスイソブチロニトリルやアゾジカルボン酸アミド（ＡＤＣＡ）、バリウムアゾジカルボキシレートの如きアゾ系化合物等の有機系発泡剤もあげられる。
【００１０】
さらにパラトルエンスルホニルヒドラジドやジフェニルスルホン−３，３'−ジスルホニルヒドラジド、４，４'−オキシビス（ベンゼンスルホニルヒドラジド）、アリルビス（スルホニルヒドラジド）の如きヒドラジン系化合物、ρ−トルイレンスルホニルセミカルバジドや４，４'−オキシビス（ベンゼンスルホニルセミカルバジド）の如きセミカルバジド系化合物、５−モルホリル−１，２，３，４−チアトリアゾールの如きトリアゾール系化合物、Ｎ，Ｎ'−ジニトロソペンタメチレンテトラミンやＮ，Ｎ'−ジメチル−Ｎ，Ｎ'−ジニトロソテレフタルアミドの如きＮ−ニトロソ系化合物などの有機発泡剤もあげられる。
【００１１】
就中、無害性などの点よりＡＤＣＡが好ましく用いうる。用いる発泡剤は、加熱膨脹性の物質がマイクロカプセル内に封入された熱膨脹性微粒子などであってもよい。その熱膨脹性微粒子にはマイクロスフェア（商品名、松本油脂社製）などの市販物もある。発泡剤の使用量は、目的とする発泡体の物性などに応じて適宜に決定することができる。一般には、ＥＰＤＭ１００重量部あたり０．１〜１００重量部、就中０．５〜５０重量部、特に１〜３０重量部の発泡剤が用いられる。
【００１２】
軟化剤としては、粘着性を有するロウ状のエチレン・プロピレン系共重合体が、混和性などの点より、用いられる。斯かる軟化剤の配合量は、ＥＰＤＭ１００重量部あたり１０〜３５重量部とされる。その配合量が１０重量部未満では粘着性の付与力に乏しくて低圧縮状態での止水性能が低下し、３５重量部を超えると混和物の粘度低下で発泡の気泡サイズが大きくなり発泡密度の低い発泡体の形成が困難となる。
【００１３】
混和物の調製は、少なくともＥＰＤＭ、加硫剤、発泡剤及び前記の軟化剤からなる配合成分を、例えばニーダやミキシングロール等の混練機を介して混合する方式などの適宜な方式で混合することにより行うことができる。その際、加硫が進行する程度に温度上昇する混合方式は好ましくない。混和物の調製に際しては粘度や加硫性の調節、得られる発泡体の強度等の物性の調節などを目的に従来に準じた適宜な配合剤を必要に応じて添加することができる。
【００１４】
ちなみに加硫の促進を目的に例えばグアニジン類やチアゾール類、スルフェンアミド類やチューラム類、ジチオカルバミン酸類やキサントゲン酸類、アルデヒドアンモニア類やアルデヒドアミン類、チオウレア類などからなる１種又は２種以上の加硫促進剤、さらには加硫促進助剤を配合することができる。加硫促進剤の使用量は、ＥＰＤＭ１００重量部あたり０．１〜１０重量部が適当であるが、これに限定されない。
【００１５】
また前記の加硫促進剤とは反対に、成形加工性の調節等を目的に加硫を遅らせうる例えば無水フタル酸や安息香酸やサリチル酸の如き有機酸、Ｎ−ニトロソ−ジフェニルアミンやＮ−ニトロソ−フェニル−β−ナフチルアミンの如きアミン類などからなる１種又は２種以上の加硫遅延剤を配合することもできる。
【００１６】
さらに混和物には尿素系やサリチル酸系や安息香酸系等の発泡助剤、タルクやクレー、炭酸カルシウムや雲母粉、亜鉛華やベントナイト、カーボンブラックやシリカ、アルミナやアルミニウムシリケート、アセチレンブラックやアルミニウム粉の如き充填剤、パラフィン類や石油系オイル類の如き加工油、ステアリン酸やそのエステル類の如き滑剤、水酸化アルミニウムや水酸化マグネシウムの如き無機系難燃剤ないし有機系難燃剤、その他、老化防止剤や酸化防止剤、顔料や着色剤、防カビ剤などの適宜な配合剤の１種又は２種以上を必要に応じて添加することができる。
【００１７】
加えて前記した亜鉛華は安定剤として、カーボンブラックは補強剤などとしても有用で、従って各種の安定剤や補強剤も配合しうる成分の例としてあげられる。なお前記した加工油や滑剤は、軟化剤として機能することもあることよりその配合量は、上記した粘着性ポリマーからなる軟化剤による特性を維持する点よりそれら軟化作用を示す薬剤の合計量に基づいてＥＰＤＭ１００重量部あたり１５０重量部以下、就中１００重量部以下、特に８０重量部以下とすることが好ましい。
【００１８】
またさらに混和物には、得られる発泡体の強度等の物性の調節を目的に非ゴム系ポリマーやＥＰＤＭ以外のゴム系ポリマーの１種又は２種以上を必要に応じ配合することもできる。その非ゴム系ポリマーやゴム系ポリマーについては適宜なものを用いることができ、特に限定はない。ちなみに前記非ゴム系ポリマーの例としては、ポリ（メタ）アクリル酸アルキルエステルの如きアクリル系ポリマーやウレタン系ポリマー、ポリエチレンやポリプロピレン、エチレン・酢酸ビニル共重合体やポリ酢酸ビニル、ポリアミドやポリエステル、スチレン系ポリマーやシリコーン系ポリマー、エポキシ系樹脂などがあげられる。その使用量は、発泡体のゴム的性質を維持する点などよりＥＰＤＭの５０重量％以下、就中３０重量％以下、特に１５重量％以下が好ましい。
【００１９】
一方、前記したＥＰＤＭ以外のゴム系ポリマーの例としては、ブテン−１の如きα−オレフィン・ジシクロペンタジエンやエチリデンノルボルネンの如き非共役二重結合を有する環状又は非環状のポリエンを成分とするゴム系共重合体やエチレン・プロピレンゴム、エチレン・プロピレンターポリマーやシリコーンゴム、ポリウレタン系ゴムやポリアミド系ゴム、天然ゴムやポリイソブチレン、ポリイソプレンやクロロプレンゴム、ブチルゴムやニトリルブチルゴム、スチレン・ブタジエンゴムやスチレン・ブタジエン・スチレンゴム、スチレン・イソプレン・スチレンゴムやスチレン・エチレン・ブタジエンゴム、スチレン・エチレン・ブチレン・スチレンゴムやスチレン・イソプレン・プロピレン・スチレンゴム、アクリルゴムなどがあげられる。ＥＰＤＭ以外のゴム系ポリマーの配合量は、前記非ゴム系ポリマーの場合に準じうる。
【００２０】
ゴム系発泡体の形成は、上記した混和物を加熱して加硫発泡処理することにより行いうる。その形成に際しては必要に応じ混和物を例えばシート等の所定の形態に成形してその成形体を加熱処理して加硫発泡体とすることもできる。その場合、成形体は適宜な方式にて任意な形態に成形したものであってよく、その形態について特に限定はない。従って加硫発泡処理の対象物は、混和物を例えばミキシングロールやカレンダーロールや押出成形等による適宜な方式でシート状やその他の形態に成形したものであってもよいし、所定の型を介して射出成形やプレス成形等による適宜な方式で凹凸等を有する所定の形態に成形したものなどであってもよい。
【００２１】
前記において凹凸形状を有する発泡体の形成では、未加硫シートを凹凸を有する型の上に配置して加熱しその型の凹凸に前記未加硫シートを形成する混和物を流動侵入させて加硫発泡処理する方式なども採ることができる。かかる方式は、ヒダ構造を有する複雑で深い凹凸構造を有する型の場合にもその凹凸形状を精度よく形成できる利点などを有している。よって成形体の寸法は任意であり、目的とする加硫発泡体の形態などに応じて適宜に決定することができる。シート等の場合、その厚さは１００mm以下、就中１μm〜８０mm、特に１０μm〜５０mmが一般的である。
【００２２】
上記した加硫発泡処理は、用いた加硫剤や発泡剤などによる加硫開始温度や発泡温度などにより従来に準じた適宜な条件で行うことができる。一般的な加硫発泡温度は、４５０℃以下、就中１００〜３５０℃、特に１２０〜３００℃である。かかる加硫発泡処理で通例、混和物が軟化して発泡剤が膨脹し発泡構造を形成しつつ加硫が進行して目的の加硫発泡体が形成される。
【００２３】
前記において発泡処理と加硫処理は、異なる温度条件で行うこともでき、適宜な処理条件を採ることができる。また加硫発泡処理は、発泡倍率の調節などを目的に加圧下に行うこともできる。その加圧条件は、従来に準じることができる。形成する加硫発泡体の発泡倍率（発泡前後の密度比）は、使用目的などに応じて適宜に決定されるが一般には１．１〜２５倍、就中１．５倍以上、特に５〜２０倍とされる。
【００２４】
シール材、就中、止水用途のシール材などとして好ましく用いうるゴム系発泡体は、発泡の気泡サイズが１〜１．５mm程度で密度が０．２００ｇ／cm³以下、就中０．１０〜０．１５ｇ／cm³となるように加硫発泡処理したものである。なお密度は、前記した発泡倍率等にて調節でき、その発泡倍率は上記した発泡剤の配合量や加硫発泡の処理時間や温度などにより制御することができる。発泡倍率の調節等にて得られる加硫発泡体の独立や連続、それらの混在等の発泡構造を制御することもできる。
【００２５】
本発明によるゴム系加硫発泡組成物ないしそれを用いたゴム系発泡体は、例えば気密や防水等の各種目的のシール材、クッション材やパッド材、断熱材、防音や制振等の振動低減材などとして、家電等の室内用品や自動車等の屋外用品、住宅等の建築物などの各種の分野において従来に準じた種々の用途に好ましく用いうる。就中、柔軟性による作業性ないし施工性と圧着性による低圧縮状態でのシール性能に優れることより漏水防止等を目的とした止水用シール材として好ましく用いうる。
【００２６】
【実施例】
実施例１
ムーニー粘度が２１のＥＰＤＭ１００部（重量部、以下同じ）、粘着性ポリマー（宇部レキセン社製、ＵＴ３５３５：エチレン・プロピレン共重合体からなる粘着性を有する非晶質ポリマーで、１９０℃での溶融粘度が１５００cpsのもの、以下同じ）１０部、炭酸カルシウム１３０部、加工油（出光興産社製、ＰＷ３８０）３０部、ＳＦＲカーボン１０部、亜鉛華５部及び粉末ステアリン酸３部をバンバリーミキサーにて１３０〜１４０℃で１２分間混練し、その混練物に微粉硫黄１．５部、加硫促進剤３．５部（大内新興化学社製、ノクセラーＥＺ：２部、ノクセラーＭ：１．５部）、ＡＤＣＡ１５部、尿素系発泡助剤１０部を加えミキシングロールにてさらに混練して混和物を得、それを押出し機で成形して厚さ５mmの未加硫未発泡シートを得、それを１６０℃の乾燥機中で３０分間加熱して加硫発泡処理し、連続気泡と独立気泡が混在した発泡シートを得、その表面のスキン層をスライスして、発泡の気泡サイズが１〜１．５mmで密度が０．１１ｇ／cm^３のゴム系加硫発泡体を得た。
【００２７】
実施例２
粘着性ポリマーの配合量を２０部とし、炭酸カルシウムの配合量を１８０部としたほかは実施例１に準じて発泡の気泡サイズが１〜１．５mmで密度が０．１１ｇ／cm^３のゴム系加硫発泡体を得た。
【００２８】
実施例３
粘着性ポリマーの配合量を３０部とし、炭酸カルシウムの配合量を１８０部としたほかは実施例１に準じて発泡の気泡サイズが１〜１．５mmで密度が０．１２ｇ／cm^３のゴム系加硫発泡体を得た。
【００２９】
比較例１
粘着性ポリマーを配合しないほかは実施例１に準じて発泡の気泡サイズが１〜１．５mmで密度が０．１０ｇ／cm^３のゴム系加硫発泡体を得た。
【００３０】
比較例２
粘着性ポリマーの配合量を５部としたほかは実施例１に準じて発泡の気泡サイズが１〜１．５mmで密度が０．１０ｇ／cm^３のゴム系加硫発泡体を得た。
【００３１】
比較例３
粘着性ポリマーの配合量を４０部としたほかは実施例１に準じて発泡の気泡サイズが１．５〜２．０mmで密度が０．２３ｇ／cm^３のゴム系加硫発泡体を得た。
【００３２】
比較例４
粘着性ポリマーの配合量を５０部としたほかは実施例１に準じて発泡の気泡サイズが１．５〜２．０mmで密度が０．２８ｇ／cm^３のゴム系加硫発泡体を得た。
【００３３】
評価試験
実施例１〜３、比較例１、２で得たゴム系加硫発泡体をＵ字防水試験に供して止水性能を評価した。これは実施例１〜３、比較例１、２で得たゴム系加硫発泡体がその気泡サイズや密度、柔軟性がほぼ均等で外観的には同程度のシール性能を示すと判断されることによる。なお比較例３、４で得たものは混和物の粘度が低くて発泡の気泡サイズが大きくなり、密度も高くて他の例のものよりも品質に劣るため試験には供さなかった。
【００３４】
前記のＵ字防水試験では、厚さ１０mmのゴム系加硫発泡体より幅１０mmのＵ字形の試料を打ち抜き形成し、それをアクリル板間にスペーサを介し所定の圧縮率となるように固定したのち試料のＵ字部に水頭高さが５０mmとなるように水を注入して２４時間以内に漏水するか否かを目視観察し、漏水を生じない最低圧縮率を調べた。この圧縮率が低いほど止水性能に優れることを意味する。
【００３５】
前記の結果を次表に示した。表より実施例３では５０％、実施例１、２では６０％の低い圧縮状態で漏水を防止できることがわかる。

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rubber- based foam that is a low-density EPDM-based foam that is flexible and excellent in water-stopping performance even at low compression, and is suitable for sealing applications.
[0002]
[Prior art]
Conventionally, various types of EPDM vulcanized foams are known, and are widely used as various sealing materials such as waterstops based on their excellent cushioning properties and compressibility. In the water stop application, it is advantageous to have excellent flexibility from the viewpoint of the formability of the bent portion. However, the conventional foam has a problem that when the softness is increased by using a lot of softeners, the water stoppage performance is lowered due to a decrease in compressive stress.
[0003]
[Technical Problem of the Invention]
An object of the present invention is to develop a rubber-based vulcanized foam composition capable of forming a low-density EPDM-based foam having excellent flexibility and water-stopping performance.
[0004]
[Means for solving problems]
The rubber foam of the present invention is an admixture containing at least a softening agent comprising 10 to 35 parts by weight of EPDM, a vulcanizing agent, a foaming agent and 100 parts by weight of EPDM as a waxy ethylene / propylene copolymer . It is characterized by comprising a vulcanized foam having a density of 0.200 g / cm ³ or less formed of a rubber-based vulcanized foam composition .
Moreover, in the rubber-type foam of this invention, it is used as a sealing material for water stop, and it is suitable that it does not produce a water leak in a 50 to 60% compression state.
[0005]
【The invention's effect】
According to the present invention, by softening with a softening agent , it is possible to achieve low density foaming with a fine bubble size while maintaining performance such as cushioning property and compressibility due to rubber physical properties of the EPDM foam, which is advantageous for work. Flexibility can be imparted, and the foam can be made to have a slightly adhesive property that maintains good handleability, and can be crimped to the material to be sealed via its slightly adhesive force. It is possible to obtain an EPDM foam that exhibits good sealing performance and exhibits high water-stopping performance and exhibits high sealing performance even in a low compression state of about 50 to 60%.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Rubber vulcanized foam composition according to the invention, EPDM, vulcanizing agents, consisting of admixture to the blowing agent and at least components a softening agent 10 to 35 parts by weight per EPDM100 parts. As the EPDM, one or more suitable ethylene, propylene, and diene rubbers can be used, and the type is not particularly limited. EPDM having a Mooney viscosity (ML1 + 4, 100 ° C.) of 5 to 30, especially 8 to 25, can be preferably used from the viewpoint of adjustability of performance such as compressibility due to rubber properties and miscibility.
[0007]
As the vulcanizing agent, one or more suitable ones can be used, and there is no particular limitation. Examples include sulfur and sulfur compounds, selenium and magnesium oxide, lead monoxide and zinc oxide, organic peroxides and polyamines, P-quinonedioxime and P, P'-dibenzoylquinonedioxime. Examples thereof include oximes such as nitroso compounds such as P-dinitrosobenzidine, resins such as alkylphenol / formaldehyde resins and melamine / formaldehyde condensates, and ammonium salts such as ammonium benzoate.
[0008]
Sulfur and sulfur compounds, particularly sulfur, can be preferably used from the viewpoint of physical properties such as vulcanizability and foaming durability of the obtained foam. The amount of the vulcanizing agent used can be appropriately determined according to the vulcanization efficiency based on the type. By the way, in the case of a sulfur type, usually 0.1 to 10 parts by weight, especially 0.5 to 5 parts by weight are used per 100 parts by weight of EPDM.
[0009]
Further, one or more suitable foaming agents can be used, and there is no particular limitation. Examples thereof include inorganic foaming agents such as ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride and azides. Organic foaming agents such as fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azo compounds such as azobisisobutyronitrile, azodicarboxylic acid amide (ADCA), and barium azodicarboxylate are also included. .
[0010]
Furthermore, hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, 4,4′-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide), ρ-toluylene sulfonyl semicarbazide, 4, Semicarbazide compounds such as 4′-oxybis (benzenesulfonyl semicarbazide), triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole, N, N′-dinitrosopentamethylenetetramine and N, N ′ Organic foaming agents such as N-nitroso compounds such as dimethyl-N, N′-dinitrosoterephthalamide are also included.
[0011]
In particular, ADCA can be preferably used from the viewpoint of harmlessness. The foaming agent used may be heat-expandable fine particles in which a heat-expandable substance is enclosed in microcapsules. The thermally expandable fine particles include commercially available products such as microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.). The amount of the foaming agent used can be appropriately determined according to the physical properties of the target foam. In general, 0.1 to 100 parts by weight, especially 0.5 to 50 parts by weight, especially 1 to 30 parts by weight, of foaming agent is used per 100 parts by weight of EPDM.
[0012]
As the softening agent, waxy ethylene-propylene copolymer having an adhesive property, from the viewpoint of miscibility, Ru are have use. The amount of斯or that softening agent is 10 to 35 parts by weight per EPDM100 parts. If the blending amount is less than 10 parts by weight, the tackiness is poor and the water stop performance in a low compression state is lowered, and if it exceeds 35 parts by weight, the foaming bubble size is increased due to the decrease in the viscosity of the admixture, and the foaming density. It is difficult to form a low-foam foam.
[0013]
The admixture is prepared by mixing at least a blending component composed of at least EPDM, a vulcanizing agent, a foaming agent and the above-mentioned softening agent by an appropriate method such as a method of mixing via a kneader such as a kneader or a mixing roll. Can be performed. At that time, a mixing method in which the temperature rises to such an extent that vulcanization proceeds is not preferable. In preparing the admixture, an appropriate compounding agent according to the prior art can be added as necessary for the purpose of adjusting the viscosity and vulcanizability, and adjusting the physical properties such as strength of the resulting foam.
[0014]
Incidentally, for the purpose of promoting vulcanization, for example, one or more guanidines, thiazoles, sulfenamides, turums, dithiocarbamic acids, xanthogenic acids, aldehyde ammonias, aldehyde amines, thioureas and the like are added. Sulfur accelerators, and further vulcanization accelerators can be blended. The amount of the vulcanization accelerator used is suitably 0.1 to 10 parts by weight per 100 parts by weight of EPDM, but is not limited thereto.
[0015]
Contrary to the above vulcanization accelerator, for example, organic acids such as phthalic anhydride, benzoic acid and salicylic acid, N-nitroso-diphenylamine, N-nitroso- One or more vulcanization retarders composed of amines such as phenyl-β-naphthylamine can be blended.
[0016]
Furthermore, the admixtures include foaming aids such as urea, salicylic acid and benzoic acid, talc and clay, calcium carbonate and mica powder, zinc white and bentonite, carbon black and silica, alumina and aluminum silicate, acetylene black and aluminum powder. Fillers, processing oils such as paraffins and petroleum oils, lubricants such as stearic acid and its esters, inorganic or organic flame retardants such as aluminum hydroxide and magnesium hydroxide, and other anti-aging agents One or more suitable compounding agents such as an agent, an antioxidant, a pigment, a colorant, and an antifungal agent can be added as necessary.
[0017]
In addition, the above-described zinc white is useful as a stabilizer, and carbon black is useful as a reinforcing agent. Therefore, examples of components in which various stabilizers and reinforcing agents can be blended are given. Since the processing oils and lubricants described above may function as a softening agent, the blending amount thereof is the total amount of chemicals exhibiting a softening action from the viewpoint of maintaining the characteristics of the softening agent composed of the above-mentioned adhesive polymer. Based on 100 parts by weight of EPDM, it is preferably 150 parts by weight or less, in particular 100 parts by weight or less, particularly preferably 80 parts by weight or less.
[0018]
Further, in the admixture, one or more of non-rubber polymers and rubber polymers other than EPDM can be blended as necessary for the purpose of adjusting physical properties such as strength of the foam obtained. Any suitable non-rubber polymer or rubber polymer can be used without any particular limitation. Incidentally, examples of the non-rubber polymers include acrylic polymers such as poly (meth) acrylic acid alkyl esters, urethane polymers, polyethylene and polypropylene, ethylene / vinyl acetate copolymers, polyvinyl acetate, polyamides and polyesters, and styrene. Examples thereof include silicone polymers, silicone polymers, and epoxy resins. The amount used is preferably not more than 50% by weight of EPDM, more preferably not more than 30% by weight, especially not more than 15% by weight, from the viewpoint of maintaining the rubbery properties of the foam.
[0019]
On the other hand, examples of rubber-based polymers other than the above-mentioned EPDM include rubbers containing as a component a cyclic or non-cyclic polyene having a non-conjugated double bond such as α-olefin dicyclopentadiene such as butene-1 or ethylidene norbornene. Copolymers, ethylene / propylene rubber, ethylene / propylene terpolymers and silicone rubber, polyurethane rubber and polyamide rubber, natural rubber and polyisobutylene, polyisoprene and chloroprene rubber, butyl rubber and nitrile butyl rubber, styrene / butadiene rubber and styrene・ Butadiene / styrene rubber, styrene / isoprene / styrene rubber, styrene / ethylene / butadiene rubber, styrene / ethylene / butylene / styrene rubber, styrene / isoprene / propylene / styrene rubber, acrylic rubber, etc. It is. The blending amount of the rubber-based polymer other than EPDM can be based on the non-rubber-based polymer.
[0020]
Formation of the rubber-based foam can be performed by heating the above-mentioned mixture and subjecting it to a vulcanization foaming treatment. In forming the mixture, if necessary, the admixture can be formed into a predetermined form such as a sheet, and the molded body can be heat-treated to obtain a vulcanized foam. In that case, the molded body may be molded into an arbitrary form by an appropriate method, and the form is not particularly limited. Therefore, the object of vulcanization and foaming treatment may be a mixture obtained by molding the admixture into a sheet or other form by an appropriate method such as a mixing roll, a calender roll, or extrusion molding, or through a predetermined mold. Further, it may be formed into a predetermined form having irregularities by an appropriate method such as injection molding or press molding.
[0021]
In the formation of the foam having an uneven shape in the above, an unvulcanized sheet is placed on an uneven mold and heated, and the mixture that forms the unvulcanized sheet flows into the unevenness of the mold and added. A method of sulfur foaming treatment can also be adopted. Such a method has an advantage that the concavo-convex shape can be accurately formed even in the case of a mold having a complex and deep concavo-convex structure. Therefore, the size of the molded body is arbitrary, and can be appropriately determined according to the form of the target vulcanized foam. In the case of a sheet or the like, the thickness is generally 100 mm or less, in particular, 1 μm to 80 mm, particularly 10 μm to 50 mm.
[0022]
The vulcanization foaming treatment described above can be performed under appropriate conditions according to the prior art depending on the vulcanization start temperature, foaming temperature, and the like using the vulcanizing agent and the foaming agent used. A typical vulcanization foaming temperature is 450 ° C. or lower, especially 100 to 350 ° C., particularly 120 to 300 ° C. In general, the vulcanization and foaming treatment softens the admixture and expands the foaming agent to form a foam structure, and vulcanization proceeds to form the desired vulcanized foam.
[0023]
In the above, the foaming treatment and the vulcanization treatment can be performed under different temperature conditions, and appropriate treatment conditions can be taken. The vulcanization foaming treatment can also be performed under pressure for the purpose of adjusting the foaming ratio. The pressurizing condition can be based on the conventional one. The expansion ratio (density ratio before and after foaming) of the vulcanized foam to be formed is appropriately determined according to the purpose of use, etc., but is generally 1.1 to 25 times, especially 1.5 times or more, particularly 5 to 5. 20 times.
[0024]
A rubber foam which can be preferably used as a sealing material, especially a sealing material for water-stopping, has a foamed cell size of about 1 to 1.5 mm and a density of 0.200 g / cm ³ or less, especially 0.10. Vulcanized and foamed so as to be ˜0.15 g / cm ³ . The density can be adjusted by the above-mentioned foaming ratio and the like, and the foaming ratio can be controlled by the blending amount of the foaming agent described above, the processing time and temperature of vulcanization foaming, and the like. It is also possible to control the foam structure such as the independence and continuity of the vulcanized foam obtained by adjusting the foaming ratio, and the mixture thereof.
[0025]
The rubber-based vulcanized foam composition according to the present invention or the rubber-based foam using the same is, for example, a sealing material for various purposes such as airtightness and waterproofing, a cushioning material, a pad material, a heat insulating material, and vibration reduction such as soundproofing and vibration damping. As a material, etc., it can be preferably used in various applications according to the prior art in various fields such as indoor products such as home appliances, outdoor products such as automobiles, and buildings such as houses. In particular, it can be preferably used as a sealing material for water-stopping for the purpose of preventing water leakage and the like because it is excellent in workability due to flexibility or workability and sealing performance in a low compression state due to press-bonding properties.
[0026]
【Example】
Example 1
100 parts of EPDM having a Mooney viscosity of 21 (parts by weight, the same applies hereinafter), an adhesive polymer (manufactured by Ube Lexen, UT3535: an amorphous polymer having an adhesive composed of an ethylene / propylene copolymer, melt viscosity at 190 ° C. 10 parts, the same applies hereinafter), 130 parts of calcium carbonate, 30 parts of processing oil (manufactured by Idemitsu Kosan Co., Ltd., PW380), 10 parts of SFR carbon, 5 parts of zinc white and 3 parts of powdered stearic acid in a Banbury mixer. Kneaded for 12 minutes at ˜140 ° C., 1.5 parts of fine powder sulfur, 3.5 parts of vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd., Noxeller EZ: 2 parts, Noxeller M: 1.5 parts) , 15 parts of ADCA and 10 parts of urea foaming aid were added and further kneaded with a mixing roll to obtain an admixture, which was molded with an extruder and unvulcanized unfoamed sheet having a thickness of 5 mm. Is heated in a drier at 160 ° C. for 30 minutes and vulcanized and foamed to obtain a foam sheet in which open cells and closed cells are mixed, and the skin layer on the surface is sliced to obtain the foam size of the foam A rubber-based vulcanized foam having a density of 1 to 1.5 mm and a density of 0.11 g / cm ³ was obtained.
[0027]
Example 2
A rubber having a foamed cell size of 1 to 1.5 mm and a density of 0.11 g / cm ³ according to Example 1 except that the amount of the adhesive polymer is 20 parts and the amount of calcium carbonate is 180 parts. A system vulcanized foam was obtained.
[0028]
Example 3
A rubber having a foamed cell size of 1 to 1.5 mm and a density of 0.12 g / cm ³ according to Example 1, except that the amount of the adhesive polymer is 30 parts and the amount of calcium carbonate is 180 parts. A system vulcanized foam was obtained.
[0029]
Comparative Example 1
A rubber-based vulcanized foam having a foam cell size of 1 to 1.5 mm and a density of 0.10 g / cm ³ was obtained in the same manner as in Example 1 except that no adhesive polymer was blended.
[0030]
Comparative Example 2
A rubber-based vulcanized foam having a foam cell size of 1 to 1.5 mm and a density of 0.10 g / cm ³ was obtained in the same manner as in Example 1 except that the amount of the adhesive polymer was changed to 5 parts.
[0031]
Comparative Example 3
A rubber-based vulcanized foam having a foam cell size of 1.5 to 2.0 mm and a density of 0.23 g / cm ³ was obtained in the same manner as in Example 1 except that the amount of the adhesive polymer was 40 parts. .
[0032]
Comparative Example 4
A rubber-based vulcanized foam having a foam cell size of 1.5 to 2.0 mm and a density of 0.28 g / cm ³ was obtained in the same manner as in Example 1 except that the amount of the adhesive polymer was 50 parts. .
[0033]
The rubber-based vulcanized foams obtained in Evaluation Test Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to a U-shaped waterproof test to evaluate the water stop performance. This is determined that the rubber-based vulcanized foams obtained in Examples 1 to 3 and Comparative Examples 1 and 2 have almost the same bubble size, density, and flexibility, and have the same level of sealing performance in appearance. It depends. The samples obtained in Comparative Examples 3 and 4 were not subjected to the test because the viscosity of the mixture was low, the foam bubble size was large, the density was high, and the quality was inferior to those of the other examples.
[0034]
In the U-shaped waterproof test, a U-shaped sample having a width of 10 mm was formed by punching from a rubber-based vulcanized foam having a thickness of 10 mm, and the sample was fixed to a predetermined compressibility through a spacer between acrylic plates. After that, water was poured into the U-shaped part of the sample so that the water head height was 50 mm, and whether or not the water leaked within 24 hours was visually observed, and the minimum compression rate at which no water leaked was examined. It means that it is excellent in water stop performance, so that this compression rate is low.
[0035]
The results are shown in the following table. It can be seen from the table that water leakage can be prevented in a low compression state of 50% in Example 3 and 60% in Examples 1 and 2.

Claims

EPDM, a vulcanizing agent, a foaming agent, and a rubber-based vulcanized foaming composition comprising 10 to 35 parts by weight per 100 parts by weight of EPDM and an admixture containing at least a softening agent comprising a waxy ethylene / propylene copolymer . A rubber-based foam characterized by comprising a vulcanized foam having a density of 0.200 g / cm ³ or less formed by the method described above .

The rubber-based foam according to claim 1, wherein the rubber-based foam is used as a sealing material for still water and does not cause water leakage in a compressed state of 50 to 60%.