JP2004144206A - Sealing material for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material for a vehicle that can prevent entrainment of air bubble even when a connected part has an irregular surface shape and does not cause appearance failure or coating defect. <P>SOLUTION: The sealing material is formed of meltable-curable molded body of a thermosetting resin composition and has a width and length enough to substantially cover discrete connected part. A plurality of communication grooves oriented in one predetermined direction and disposed mutually in parallel are formed in a surface contacting with the connected part. The starting end of each communication groove is one side of the molded body, and the terminal end thereof is another end facing it. <P>COPYRIGHT: (C)2004,JPO

Description

を含む高分子材料について言及したものであり、また、このような材料は熱可塑の処理特性を備えている。すなわち、この材料は加熱により軟らかくなって流動して形状が付与されるようになり、冷却により固まる。さらに、この材料は、再加熱により再び軟らかくなる。この熱可塑性のポリアミド成分は、エポキシ含有材料との望ましい混合を実現するだけでなく、エポキシ含有材料の硬化を促進しない他の樹脂組成物の成分とも、そのような混合を実現することが可能である。また、熱可塑性のポリアミド成分は、シーラント組成物の優れた低温特性、特に可撓性にも寄与する。
【００３７】
望ましい熱可塑性のポリアミド成分は、溶融相においてエポキシ含有材料と混合（すなわち、溶融−混合）し、かつ、好ましくは、エポキシ含有材料を硬化させないとき、均一な単一の相の混合物を形成する。均一な単一の相の形成は、かかる混合物（溶融−混合物）が透明になることで明らかになる。好適には、１００重量部の前記エポキシ含有材料に対して、約９０〜約３５０重量部のポリアミド成分が含まれている。ポリアミド成分が約９０重量部もしくはそれより少なく含まれていると、硬化した樹脂組成物が脆くなる傾向にある。他方、ポリアミド成分が約３５０重量部もしくはそれより多く含まれていると、硬化した樹脂組成物が十分な架橋をしておらず、再加熱により流動しやすい傾向にある。エポキシ含有材料が硬化した場合は、多数の相又は分離した相の組成物が結果として生じる。一方の相は硬化したエポキシ含有材料に起因し、他方の相は熱可塑性のポリアミド成分から結果として生じる。しかし、両相は、エポキシ含有材料と熱可塑性のポリアミド成分とからなる単一の均一な相から形成されるので、たとえ上述のようにエポキシ含有材料が硬化しても、両相が偏って分布することはない。したがって、樹脂組成物にはエポキシ含有材料及び熱可塑性のポリアミド成分に起因した特性が付与されることとなる。ブレンドされた熱可塑性のポリアミド成分において、樹脂組成物に対して所望の特性が付与されるのであるならば、ある程度の不均一性は許容可能である。
【００３８】
また、望ましい熱可塑性のポリアミド成分は、樹脂組成物を所望の表面で加熱し、シールするときにエポキシ含有材料が硬化するのを防止するため、エポキシ含有材料の硬化温度以下の軟化点を有している。また、樹脂組成物が加熱により溶融して不連続部に容易に浸入することができる。通常、自動車産業で樹脂組成物が用いられるとき、熱可塑性のポリアミド成分は約１８０℃以下の軟化点を有している。
【００３９】
この樹脂組成物には、エポキシ含有材料を硬化するための硬化剤が含まれている。好適には、この硬化剤は熱的に活性化されて、熱の影響下でエポキシ含有材料の硬化をもたらす。例えば、熱的に活性化される有用な硬化剤は、アミンを含むアミド基又はイミダゾールを含んでいる。好適には、アミド基をもった硬化剤としてはジシアンジアミドが代表的である。また、イミダゾールをもった硬化剤としてはトリアジン誘導体が代表的である。ジシアンジアミドの硬化剤は、例えばエー・シー・アール社から「ＥＨ３６３６」という製品名で市販されている。また、トリアジン誘導体の硬化剤は、例えば四国化成（株）から「２ＭＺＡ」という製品名で市販されている。
【００４０】
さらに、この樹脂組成物は、必要に応じて、例えば炭酸カルシウムやシリカの粉体からなる充填材、例えばチバ・ガイギー社から「イルガノックス１０１０」という製品名で市販されている酸化防止剤、例えばチバ・ガイギー社から「ＴＩＮＵＶＩＮ　（登録商標）Ｐ　」という製品名で市販されている紫外線吸収剤又は３Ｍ社から「ＦＣ３６」という製品名で市販されている界面活性剤のような添加剤を含んでいてもよい。
【００４１】
熱硬化性樹脂組成物は、室温では固体である。この樹脂組成物は、室温又はそれよりわずかに低い温度では若干のタックがあることが望ましい。このようなタックは、樹脂組成物を含む部材の位置決めを初めに実施して、例えば車両のルーフディッチにあるジョイントやシームを被覆することができるからである。しかし、樹脂組成物がロープ、テープ、ストリップ又は同様の形状になっていると、迅速な据え付けが可能となり、施工後の材料を熟練や手間をかけて処置すること（例えば、適用したシーリング材に許容し得る外観を与えること）の必要性をも取り除くことができる。
【００４２】
また、本発明の実施に好適な別の熱硬化性樹脂組成物は、例えば、
低吸湿性エポキシ化熱可塑性樹脂を含むエポキシ含有材料、
前記エポキシ含有材料の硬化剤、及び
充填剤
を含む樹脂組成物である。
【００４３】
さらに詳しく述べると、この熱硬化性樹脂組成物において第１の成分として用いられるエポキシ含有材料は、低吸湿性エポキシ化熱可塑性樹脂を含み、さらに、エポキシ樹脂及び必要に応じて相溶化剤を含む。
（１）低吸湿性エポキシ化熱可塑性樹脂
エポキシ化熱可塑性樹脂はエポキシ基を有する熱可塑性樹脂である。一般に、熱可塑性樹脂は熱硬化性樹脂組成物に一定の形状を付与することができる。また、エポキシ化熱可塑性樹脂は、エポキシ基の存在により熱硬化反応に寄与する。その結果、熱硬化性樹脂組成物が硬化したときに、その硬化物が耐熱性や耐久性を備えるようになる。また、自動車のルーフディッチ用シーラー用途においては、このエポキシ基により、硬化物が自動車用塗料（例えば、有機溶剤系アクリル塗料や有機溶剤系アルキッド塗料）及びカチオン電着塗装された自動車鋼板と密着しやすくなる。また、当該シーラーは自動車の塗装工程前に車体に組み付けられるので、車体の塗装時にシーラー上に塗装を施して、車体の色と同一にすることができる。その結果、モール等のカバー材が必要とされず、車体の外観・見栄えがよくなる。また、鋼板と密着することは、シーラーの耐久性、密閉性を向上させることにもなる。
【００４４】
さらに、熱硬化樹脂性組成物においては、このエポキシ化熱可塑性樹脂の吸湿性はできるだけ低いこと、すなわち低吸湿性であることが必要とされる。なぜならば、かかる低い吸湿性により、熱硬化性組成物への水分の吸収を防止し、その結果、自動車の塗装工程に有利になるからである。また、熱硬化性樹脂組成物の保管等の取り扱いも簡素化される。尚、この「低吸湿性」とは、エポキシ化熱可塑性樹脂が、３５℃、８０％ＲＨの相対湿度の下で、０．２ｗｔ　％以下の飽和吸水率を有することを意味する。このようなエポキシ化熱可塑性樹脂は、通常、約９以下の溶解度パラメータ（ＳＰ）を有する。本明細書では、この溶解度パラメータはスモールの式（文献Ｐ．Ａ．Ｓｍａｌｌ，　Ｊ．Ａｐｐｌ．Ｃｈｅｍ．，　３，　７１　（１９５３）　に記載）で定義されるものである。
【００４５】
通常、このようなエポキシ化熱可塑性樹脂は、成形加工時及び熱溶融時の流れ性を考慮して１，０００　〜１０，０００の分子量を有する。また、エポキシ化熱可塑性樹脂は、耐熱性、耐久性、塗膜密着性及び吸水性を考慮すると、一般に、２００　〜１５，０００のエポキシ当量を有している。
【００４６】
上述したエポキシ化熱可塑性樹脂の典型的な一例は、エポキシ化エチレン系熱可塑性樹脂である。この樹脂は、エチレン部分の存在によって低吸湿性を示す。エポキシ化エチレン系熱可塑性樹脂としては、エチレン−グリシジル（メタ）アクリレート共重合体が好ましい。このエチレン−グリシジル（メタ）アクリレート共重合体は、特開平９−１３７０２８号公報や特開平１０−３１６９５５号公報において接着剤及びホットメルト組成物の一成分として開示されているように、ポリエチレンをエポキシ化したものであって、通常は、エチレンとグリシジルメタクリレートの共重合により得られる。その結果、エチレン−グリシジル（メタ）アクリレート共重合体は、エチレン部分とグリシジル（メタ）アクリレート部分によって構成される。このような場合、エチレン部分は熱硬化性組成物の低吸湿性に寄与し、また、グリシジル（メタ）アクリレート部分は後述する自動車用塗料及びカチオン電着塗装された自動車鋼板の密着性に寄与する。
【００４７】
エチレン−グリシジル（メタ）アクリレート共重合体は、エチレンとグリシジル（メタ）アクリレートのモノマー重量比を５０：５０〜９９：１の範囲にして構成されていることが望ましい。上限を超えたエチレンを含んで構成されたエチレン−グリシジル（メタ）アクリレート共重合体は、硬化物に所望の機械的強度及び耐久性が付与し難く傾向にある。逆に、下限を下回ったエチレンを含むエチレン−グリシジル（メタ）アクリレート共重合体は所望の低吸湿性を得ることができない傾向にあるからである。
【００４８】
また、典型的なエチレン−グリシジル（メタ）アクリレート共重合体は、約１２０　℃以下の比較的低温でも溶融し易く、それを含む熱硬化性樹脂組成物を加熱流動させてシールする際に高流動性が得られ、結果として均一性及び平滑性の高い外観となる。また、シーラー作製時の加熱混合プロセスにおいて比較的低温で混練することができるため、熱硬化成分と硬化剤の反応を混練中に起こすおそれが少なく、さらに、反応性がより高い硬化剤を選択することもできる。
【００４９】
本発明の効果を損なわない限り、エポキシ化熱可塑性樹脂として、エチレン、グリシジル（メタ）アクリレート以外の第三の成分を共重合又はグラフト重合した三元のエチレン−グリシジル（メタ）アクリレート共重合体を使用してもよい。このような三元共重合体の一例は、アルキル（メタ）アクリレート及び酢酸ビニルなどを共重合したもの、また、グラフト重合体としては、ポリスチレン、ポリアルキル（メタ）アクリレート及びアクリルニトリル−スチレン共重合体などをグラフトしたものである。
【００５０】
エポキシ化熱可塑性樹脂のもう一つの典型的な例はエポキシ化スチレン系熱可塑性樹脂であり、共役ジエンの存在によって低吸湿性を示す。このエポキシ化スチレン系熱可塑性樹脂は、例えば、ポリスチレンからなるハードセグメントと、エポキシ化されたポリブタジエンからなってゴム弾性をそのエラストマーに付与するソフトセグメントと有するブロック共重合体である。あるいは、エポキシ化されたポリブタジエンの代わりに、又は、エポキシ化されたポリブタジエンと共に、エポキシ化されたポリイソプレンを使用することができる。
【００５１】
通常、エポキシ化スチレン系熱可塑性樹脂のガラス転移温度（Ｔｇ）は、−７０〜−５０℃と非常に低く、このとき、熱硬化性樹脂組成物の硬化物に約−３０℃までの低温における耐久性（特に振動耐久性を）強化することができる。その結果、このエポキシ化スチレン系熱可塑性樹脂は、低温でも応力が繰り返し負荷される部分のシーラー用途、例えば、上記のような自動車のルーフディッチのシーラー用途に非常に有利である。また、自動車のルーフディッチのシーラー用途においては、エポキシ化スチレン系熱可塑性樹脂のスチレン部分及びエポキシ基により、硬化物が自動車用塗料（例えば、有機溶剤系アクリル塗料や有機溶剤系アルキッド塗料）及びカチオン電着塗装された自動車鋼板と密着することになる。
【００５２】
かかるエポキシ化スチレン系熱可塑性樹脂の一例は、スチレン−エポキシ化ブタジエン−スチレン共重合体及びスチレン−エポキシ化イソプレン−スチレン共重合体である。いずれの場合も、エポキシ化は共役ジエンの不飽和結合をエポキシ化することで行なわれる。
【００５３】
以上のような低吸湿性エポキシ化熱可塑性樹脂は、熱硬化性樹脂組成物中に１０〜９０重量％の量で含まれることが好ましい。約１０重量％未満では耐熱性、低吸湿性が低下し、約９０重量％超では充填剤が相対的に低下し低線膨張率が得られないことがあるからである。
（２）エポキシ樹脂
エポキシ含有材料には、前述したエポキシ化熱可塑性樹脂のほか、例えばビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、ノボラック型エポキシ樹脂、グリシジルアミン型エポキシ樹脂のような液状又は固体状のエポキシ樹脂を含ませ、熱硬化性樹脂組成物の硬化物の耐熱性、耐久性及び上記の自動車用塗料との密着性をさらに強化する。望ましいエポキシ樹脂は、例えば水添ビスフェノールＡ型エポキシ樹脂、脂環式エポキシ樹脂、ブタジエン骨格エポキシ樹脂等の線状脂肪族エポキシ樹脂、又はダイマー酸変性エポキシ樹脂等のグリシジルエステル型エポキシ樹脂のように、極性が比較的低いエポキシ樹脂である。なぜなら、前記のエポキシ化熱可塑性樹脂に含まれる低吸水成分、例えば、エチレン部分及びブタジエン部分との相溶性が優れているからである。さらに、硬化物への水分の吸収を防止し、上記のように自動車の塗装工程に有利になるからである。このエポキシ樹脂の量は、（１）の成分、すなわち低吸湿性エポキシ化熱可塑性樹脂１００重量部に対し、通常は０〜５００重量部、好ましくは５〜４００重量部である。
（３）相溶化剤
必要に応じて、エポキシ含有材料には相溶化剤がさらに含まれてもよい。詳細に述べると、この相溶化剤は、１００重量部の低吸湿性エポキシ化熱可塑性樹脂に対して通常は０〜３００重量部、好ましくは１〜１００重量部含まれており、低吸湿性エポキシ化熱可塑性樹脂とエポキシ樹脂との相溶性を高めることができる。上記の相溶ができる限り、本発明で相溶化剤は特に限定されないけれども、好適にはポリエステル樹脂又はエチレン酢酸ビニル共重合体（ＥＶＡ）を含んでいる。特に、ポリエステル樹脂が、低吸湿性エポキシ化熱可塑性樹脂と所定の割合で配合されている場合に、低吸湿性エポキシ化熱可塑性樹脂とエポキシ樹脂との分離を防止するだけでなく、熱硬化性組成物の硬化温度（１００〜１６０℃）における流動性も大幅に向上させることができるからである。
【００５４】
上記したエポキシ含有材料に組み合わせて、この材料のための硬化剤が使用される。硬化剤は、エポキシ化熱可塑樹脂及びエポキシ樹脂に含まれるエポキシ基を硬化させて熱硬化性樹脂組成物に架橋構造を設け、硬化物を得ることができる。
【００５５】
本発明によれば、硬化物を得ることができる限り硬化剤は限定されない。したがって、硬化剤は、例えばジシアンジアミドのようなアミン化合物、分子内にカルボキシル基（酸無水物も含む）をもったアクリル化合物若しくはロジン、イミダゾール誘導体、ＢＦ３錯体類、有機酸ヒドラジド、ジアミノマレオニトリル類若しくはメラミン類又はそれらの混合物を含んでもよい。また、硬化剤の極性の高低も問わない。しかし、エチレン−グリシジル（メタ）アクリレート共重合体のグリシジル基の硬化には、特開平９−１３７０２８号公報及び特開平１０−３１６９５５号公報に開示されているように、分子内にカルボキシル基を含有するアクリル化合物やロジンを含む硬化剤の使用が要求される。極性の高い硬化剤がエチレン−グリシジル（メタ）アクリレート共重合体と相溶せず、実質反応できないのと比較して、かかる硬化剤はエチレン−グリシジル（メタ）アクリレート共重合体と相溶し易く、エチレン−グリシジル（メタ）アクリレート共重合体のグリシジル基を硬化するからである。
【００５６】
硬化剤は硬化促進剤と併用してもよい。特に、カルボキシル基を有する硬化剤とエポキシとの反応には、フェノール含有物、イミダゾール誘導体又は三級アミンを含む硬化促進剤が有利に使用可能である。
【００５７】
熱硬化性樹脂組成物には、例えば炭酸カルシウム若しくはシリカ又はそれらの混合物を含有した充填剤がさらに添加されている。充填剤は、硬化物の線膨張係数を低下させることができる。その結果、そのような硬化物は、特に上記の低温における温度変化において、線膨張係数が低下し、低温下での収縮量が減少し、その上に上記自動車用塗料を塗布して形成された塗膜に応力を与え難くなる。かくして、この形成された塗膜は低温でも割れ難くなる。
【００５８】
このように充填剤が添加されていると、一般に、熱硬化性樹脂組成物が加熱−溶融時において好ましくない流動性を伴うおそれがある。従って、本発明の熱硬化性樹脂組成物は可塑剤を含むことが好ましい。可塑剤を含むことにより、本発明の熱硬化性樹脂組成物は所望の流動性が保持される。なぜならば、この可塑剤は一般的に粘度が低く、組成物の流動性の向上に寄与することができるからである。
【００５９】
本発明の熱硬化性樹脂組成物に含めてもよい可塑剤は、例えば、フタル酸ジ−２−エチルヘキシルもしくはフタル酸ジイソノニルのようなフタル酸エステル類、アジピン酸エステル類、エポキシ化脂肪酸エステル類、エポキシ化大豆油、エポキシ化アマニ油、液状テルペン樹脂、液状テルペンフェノール共重合体もしくは液状テルペンスチレン共重合体、アゼライン酸エステル類、セバシン酸エステル類、エポキシヘキサフタル酸エステル類又はそれらの混合物を含有した可塑剤が含まれる。かかる可塑剤は、熱硬化性樹脂組成物の硬化物に可撓性を与えることができる。また、硬化物はガラス転移温度を下げて、−２０〜−４０℃の低温でも弾性率を低くすることができる。その結果、硬化物がそのような低温での大きく伸びることができ、振動耐久性のような動的耐久性を向上させることができる。
【００６０】
このような熱硬化性樹脂組成物を成形して形成されたシート、テープ、ロープ又はストラップのような一定の形状をもったシーリング材は、例えば継ぎ手等の不連続部上に配置する。それから、シーリング材は加熱により熱溶融−流動可能になって、不連続部をシールすることができる。すなわち、不連続部を被覆した状態で加熱されたとき軟化して、不連続部の表面になじみ、それにより捕捉された空気を押し出す。その後、シーリング材は加熱により硬化し（すなわち共有結合でもって架橋し）、引き続いて冷却及び再加熱しても流動することを妨げる。
【００６１】
自動車産業では、この不連続部は例えばルーフディッチにおいて見出され、シーリング材はそこに適用される。このようなシーリング材は、ルーフディッチの底面のみならず側壁にも拘束される。ルーフディッチは、それを構成するパネルの偏倚や撓みにより、シーリング材に側壁から応力を及ぼすことがある。しかし、このシーリング材は上述した熱硬化性樹脂組成物の弾性により、約−３０℃の比較的低い温度で側壁からの応力を受けても、柔軟に追従することができ割れ難くい。その結果、塵埃、水分及びその他の望ましくない成分の侵入を防止することができる。
【００６２】
自動車産業では、また、ルーフディッチのシーリング材を加熱によって溶融・流動した後の塗装工程でシーリング材の上に塗膜を設ける間に、加熱工程で硬化を行う。この塗膜は、シーリング材と同様にルーフディッチの側壁に拘束されるほか、シーリング材からも拘束される。その結果、塗膜とシーリング材との間に界面応力が一般に生じる。通常、この界面応力は低温下で観察されることが多い。低温下において、典型的なシーリング材は収縮を受け易いからである。この界面応力（Ｐ）　は、通常、シーリング材のガラス転移温度（Ｔｇ）以上の温度で緩和されるという仮定に基づき、シーリング材のガラス転移温度以下の温度（Ｔ）　において次の式で表される。
【００６３】
Ｐ＝　ΔＴ・Ｅ・Δα
ここで、ΔＴ：Ｔ−Ｔｇ、Ｅ：シーリング材の弾性率、Δα：塗膜とシーリング材の線膨張係数差である。
【００６４】
本発明のシーリング材の場合、上述したように弾性率が低く、かつ、線膨張係数差が小さくなっている。その結果、本発明のシーリング材のガラス転移温度（具体的には−３０〜−１０℃）以下の−４０〜−２０℃のような低温では、その応力が低減され塗膜の割れを防止することができるようになる。
【００６５】
また、本発明のシーリング材は、上述したように硬化の前後で水分を低減されている。その結果、シーリング材を塗装工程の前に、高温・高圧下に数日放置した後に、塗装工程を施しても、水分が発泡により膨張することにより、シーリング材が不連続部と接着せずに層間剥離を起こしたり又は浮き上がったりすることを防止することができて、塵埃、水分及びその他の望ましくない成分の侵入を回避することができる。また、このようなシーリング材は塗膜と十分に接着し、又は、塗膜に好ましい外観も提供することができる。
【００６６】
さらに、上述の熱硬化性樹脂組成物には、微小粒金属、無機粒子、結晶性高分子、有機顔料からなる結晶化剤が含まれてもよい。このような結晶化剤は、熱硬化性組成物にポリエステルのような結晶性樹脂が含まれている場合に、この結晶性樹脂の結晶化を促進することができ、その結果、熱硬化性樹脂組成物及びその成形品たるシーリング材の性能の経時変化を防止することができる。
【００６７】
また、本発明の効果を損なわない範囲において、熱硬化性樹脂組成物が、その上に設けられる塗膜との密着性を向上させるための改質剤をさらに含んでもよい。このような改質剤は、テルペン系樹脂のような粘着性付与剤又は比較的極性の高い成分を共重合したオレフィン共重合体等である。
【００６８】
上記のような熱硬化性樹脂組成物を使用して、本発明のシーリング材はいろいろな成形法で製造することができる。得られる成形体は、そのまま使用してもよく、所定のサイズに裁断してもよく、あるいはロールの形に巻き取ってもよい。
【００６９】
【実施例】
引き続いて、本発明をその実施例を参照して説明する。なお、これらの実施例によって本発明が限定されるものでないことは言うまでもない。
実施例１
シーリング材の製造：
下記の成分を記載の量で均一に混合して熱硬化性樹脂組成物を調製した。

これらの成分を二軸押出し成形機に投入して均一になるまで混練した。次いで、得られた樹脂組成物を押出し成形機から押出し、厚さ１００μｍのＰＥＴフィルムのシリコーン処理面にホットナイフコーター（コンマコータータイプ）を用いて塗布し、乾燥させた。厚さ４ｍｍの樹脂シートが得られた。
【００７０】
得られた樹脂シートを直角二等辺三角形（底辺１ｍｍ、２等辺０．７１ｍｍ）の鋸歯状突起群を１ｍｍピッチで連続して有する２液シリコーン樹脂製薄板成形型上に載置し、１２０℃のヒートプレスにかけて成形型の突起群を樹脂シートに転写した。樹脂シートを成形型から剥離すると、Ｖ字形の細溝が片面に連続して形成されたシーリング材が得られた。
【００７１】
次いで、得られたシーリング材を自動車のルーフディッチの模擬試験に供するため、ルーフディッチのＵ字形の溝にあわせて幅７ｍｍ×長さ１５０ｍｍのストリップに裁断した。このストリップ状のシーリング材は、図２を参照して先に説明したような形態を有し、その片面には、Ｖ字形の連通溝が長手方向に直角に連続して配置されていた。それぞれの連通溝のサイズは、図７及び図８を参照して説明すると、角度θ_１＝９０度、ピッチｐ＝１ｍｍ、角度θ_２＝９０度、そして溝の一辺１５ａ＝０．７１ｍｍであった。
実施例２
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝９０度、ピッチｐ＝２ｍｍ、角度θ_２＝９０度、そして溝の一辺１５ａ＝１．４ｍｍに変更した。
実施例３
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝６０度、ピッチｐ＝１ｍｍ、角度θ_２＝９０度、そして溝の一辺１５ａ＝０．７１ｍｍに変更した。すなわち、本例のシーリング材は、連通溝のパターンを図９（Ａ）に示すように変更した。
実施例４
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝３０度、ピッチｐ＝１ｍｍ、角度θ_２＝９０度、そして溝の一辺１５ａ＝０．７１ｍｍに変更した。すなわち、本例のシーリング材は、連通溝のパターンを図９（Ｂ）に示すように変更した。
実施例５
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝９０度、ピッチｐ＝２ｍｍ、角度θ_２＝１２０度、そして溝の一辺１５ａ＝１．２ｍｍに変更した。
実施例６
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝９０度、ピッチｐ＝１ｍｍ、角度θ_２＝１２０度、そして溝の一辺１５ａ＝０．６ｍｍに変更した。
実施例７
前記実施例１に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝９０度、ピッチｐ＝１ｍｍ、角度θ_２＝６０度、そして溝の一辺１５ａ＝１ｍｍに変更した。
実施例８
前記実施例１に記載の手法を繰り返したが、本例では、得られたシーリング材を自動車のルーフディッチの模擬試験に供する際、下記の評価試験の項で説明する予備乾燥（プレキュア）工程の条件を１２０℃／１５分（物温）から１４０℃／３０分（物温）に変更した。
比較例１
前記実施例１に記載の手法を繰り返したが、本例では、比較のため、シーリング材の表面からＶ字形の連通溝を省略した。すなわち、本例では、得られた樹脂シートを平板状の成形型上で熱成形し、表面が平坦なシーリング材を製造した。
比較例２
前記実施例１に記載の手法を繰り返したが、本例では、比較のため、シーリング材の長手方向に平行となるように連通溝を形成した。すなわち、本例のシーリング材は、図１０に示すような連通溝のパターンを有し、それぞれの連通溝１５のサイズは、角度θ_１＝０度、ピッチｐ＝１ｍｍ、角度θ_２＝９０度、そして溝の一辺１５ａ＝０．７１ｍｍであった。
比較例３
前記比較例２に記載の手法を繰り返したが、本例では、シーリング材の連通溝のサイズを、角度θ_１＝０度、ピッチｐ＝１ｍｍ、角度θ_２＝１２０度、そして溝の一辺１５ａ＝０．６ｍｍに変更した。
比較例４
前記比較例２に記載の手法を繰り返したが、本例では、得られたシーリング材を自動車のルーフディッチの模擬試験に供する際、下記の評価試験の項で説明する予備乾燥（プレキュア）工程の条件を１２０℃／１５分（物温）から１４０℃／３０分（物温）に変更した。
模擬試験
上述の実施例及び比較例で製造したシーリング材を使用して、下記の手順に従い自動車のルーフディッチの模擬試験を実施した。この模擬試験は、シーリング材を実際にルーフディッチの封止に使用した時に、気泡の巻き込みを伴うことなく高品質のシールを提供できるか否かを評価するためのものである。
（試験片の作製）
自動車のルーフディッチを模擬するため、図３に示したルーフディッチに類似の形態を有する試験片を厚さ０．８ｍｍの冷間圧延鋼板からなるパネルから作製した。２枚のパネルをクランク上で図示のように折り曲げた後、それぞれのパネルの端面どうしを重ね合わせ、スッポト溶接し、最後にパネルの全体に自動車グレードのカチオン電着塗装を施した。得られたＵ字形の溝をもった試験片のサイズは、長さＬ＝４００ｍｍ、溝の幅ｗ＝９ｍｍ、深さｄ＝７ｍｍ、段差Ａの高さｈ＝０．８ｍｍ、幅ａ＝３ｍｍであった。
（模擬試験）
作製した試験片の溝の部分に、図３に示すように、シーリング材の連通溝が試験片の段差を覆うようにしてシーリング材を装着した。次いで、試験片を恒温オーブンに入れて１２０℃で１５分間にわたって放置（物温放置）した。これは、自動車塗装ラインにおいて通常実施されているシーリング材の予備乾燥を模したものであり、プレキュアと呼ばれるものである。このプレキュア工程では、固形のシーリング材が加熱によって溶融流動せしめられ、溝の両側の縦壁を覆うようにして溝を充填した。
【００７２】
引き続いて、自動車塗装ラインで通常実施している塗装工程を模して、次のような加熱工程を順次実施した。なお、これらの加熱工程では実際に塗装を行っていないが、これは、シーリング材の硬化によって形成されたシールの表面に塗料の皮膜があった場合、シール表面の巻き込み気泡の直径等を測定しにくいためである。
第１加熱工程：
通常アクリル系ソリッド塗料を静電塗装して行われる中塗り塗装工程を模して、試験片を恒温オーブンに入れて１４０℃で３０分間にわたって加熱（物温）し、シーリング材を硬化させた。
第２加熱工程：
通常アクリル系ソリッド塗料を静電塗装して行われる上塗り塗装工程を模して、試験片を恒温オーブンに入れて１４０℃で３０分間にわたって加熱（物温）し、シーリング材を硬化させた。
【００７３】
以上の加熱工程が完了した後、試験片を室温で一昼夜放置し、得られたシールの表面を目視で観察し、認められた気泡の数をカウントした。それぞれの試験片について測定された気泡の数（５回の測定の平均値）を下記の第１表に示す。
【００７４】
次いで、それぞれのシールの気泡をキーエンス社製のマイクロスコープ（型番ＶＨ−６３００）で倍率２０倍で観察し、それぞれの気泡の直径Ｄをモニター上から計測した。気泡の直径Ｄ（５回の測定の平均値）を次式（球の体積式）にあてはめた。
【００７５】
球の体積Ｖ＝（４／３）×π×（Ｄ／２）^３
そして、試験片ごとに球の体積Ｖの合計を求め、それを平均して試験片当たりの気泡換算体積（シール中に巻き込まれていると推測される気泡の体積）を算出した。得られた気泡換算体積を下記の第１表に示す。
【００７６】
【表１】

上記第１表の評価結果から理解できるように、実施例１〜８では、シーリング材が溶融−硬化の際、シーリング材の下に巻き込まれた気泡が凹凸状の連通溝を通じて逃出可能であったので、試験片当たりの気泡の巻き込み個所が少なく、また、たとえ気泡の巻き込みがあったとしても、体積的に小さいため、許容可能な範囲に収めることができた。よって、これらの実施例のシーリング材は、合格（○）と判定できた。
【００７７】
これに対して、比較例１のようにシーリング材の接着面（シール面）が未処理で平滑なままである場合には試験片当たりに気泡の巻き込み個所が非常に多く、気泡換算体積も大であった。さらに、比較例２〜４のようにシーリング材の長手方向に関して平行に連通溝を付与したのでは、気泡どうしが集積するため、大きな欠陥が発生した。よって、これらの比較例のシーリング材は、不合格（×）としか判定できなかった。
【００７８】
【発明の効果】
以上に詳細に説明したように、本発明によれば、取り扱いが容易であり、環境に有害なガスを発生することがなく、接合部が不規則な面形状の場合などでも気泡の巻き込みを防止でき、よって、外観不良や塗膜欠陥が発生することのない車両用シーリング材を提供することができる。本発明のシーリング材は、特に車両の不連続な接合部、例えばルーフディッチなどの封止に適用した時に、その作用効果を十分に発揮することができる。
【図面の簡単な説明】
【図１】従来の溶融−流動型のシーリング材における気泡の発生を説明した断面図である。
【図２】本発明による車両用シーリング材の好ましい１形態を示した斜視図である。
【図３】図２に示すシーリング材のルーフディッチにおける使用を示した斜視図である。
【図４】図３に示すルーフディッチにおける気泡の巻き込み防止の原理を示した斜視図である。
【図５】図３に示すルーフディッチにおける気泡の逃出ルートを模式的にしめした断面図である。
【図６】図３に示すルーフディッチにおける気泡の逃出ルートを模式的にしめした断面図である。
【図７】図２に示すシーリング材における連通溝の配置を示す長手方向の底面図である。
【図８】図２に示すシーリング材の連通溝の形状を示す長手方向の断面図である。
【図９】本発明のシーリング材における連通溝の別の配置パターンを示す底面図である。
【図１０】比較例で使用したシーリング材における連通溝の配置パターンを示す底面図である。
【符号の説明】
１０…シーリング材
１１…気泡
１５…連通溝
２０…ルーフディッチ
２１…ルーフパネル
２２…サイドパネル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing material for vehicles, and more particularly, to a sealing material for sealing discontinuous joints found in vehicles such as automobiles, for example, lap joints, steps, joints, welds, and the like. The present invention relates to a curable sealing material.
[0002]
[Prior art]
2. Description of the Related Art Vehicles such as automobiles and trucks have discontinuous joints formed by overlapping metal steel plates. Discontinuous joints are formed in vehicles for various purposes, a typical example of which can be found in the roof ditch of a motor vehicle. The roof ditch is formed in the front-rear direction of the vehicle by bending the side edges of the roof panel and the side panel of the vehicle to overlap each other. This roof ditch has a U-shaped groove, and can collect moisture and the like and discharge it to the outside of the vehicle.
[0003]
The discontinuous joint is usually sealed with a sealing material to prevent intrusion of water, dust, and the like, prevent water leakage, improve the appearance, and further improve the painting effect. Further, the sealing material may be used in a liquid state or a solid state depending on the requirements of construction. For example, in the automotive industry, a liquid or paste-like plastisol consisting of a plasticizer and polyvinyl chloride (PVC) particles dispersed therein is generally used for roof ditch construction as described above. However, this sealing material may generate dioxin, which is a highly toxic and hardly decomposable chlorine compound, when burning, and often uses a phthalic acid-based plasticizer suspected of being an environmental hormone. . In addition, as a sealing material that can eliminate these disadvantages and improve the design property after construction, a sealing material composition containing a curable resin such as a urethane resin or a silicone resin and cured sealing material particles. Is known (see Patent Document 1).
[0004]
By the way, since the joints of vehicles have irregular surface shapes (steps, spots, welding marks such as lasers, distortions, etc.), when the sealing material is a liquid or a paste, it may be difficult to construct the joints. Often. Therefore, it has been proposed to use a sealing material having a certain shape, such as a sheet or a tape. For example, as a sealer tape formed into a tape shape for sealing a steel plate joint portion of an automobile body or the like, a bead portion having minute irregularities is provided on an adhesive surface of the sealer tape to the steel plate, and a sealer tape longitudinal portion of the bead portion is provided. 2. Description of the Related Art A sealer tape is known in which flat portions extending parallel to a steel plate are provided on both sides in a direction (see Patent Document 2). However, this sealer tape is expected to be effective in preventing turning up (peeling) at both ends, since it only needs to be in close contact with the steel plate joint. There is room for further improvements in terms of proper maintenance, coating efficiency with sealer tape, and conformability to irregular surface shapes of the joints.
[0005]
In order to solve these problems, the applicant has set solid sealing material in a form that can be melted and flowed, that is, after sealing material is applied, it is made to flow by heating and completely adhered to the joint. It has been found that it is desirable to have a form that can be cured again after it has been formed, and that one or more polymers which are semi-crystalline, thermoplastic and melt-flowable at room temperature, and Invented a sheet material having at least one layer consisting essentially of one or more non-reactive fillers.
[0006]
[Patent Document 1]
JP 2001-115142 A (paragraph numbers 0005 to 0009)
[Patent Document 2]
Japanese Utility Model Publication No. 61-176232 (FIG. 1)
[Patent Document 3]
Japanese Patent Publication No. 9-505335 (Claims 1 to 22, FIGS. 1a and 1b)
)
[0007]
[Problems to be solved by the invention]
Melt-flowable sealants are useful for forming paintable seals in the production line of vehicles such as automobiles. However, this type of sealing material still has problems to be solved. That is, there are problems such as poor appearance due to entrapment of air bubbles and occurrence of defects in a coating film further formed on the seal.
[0008]
FIG. 1 shows the occurrence of a problem caused by the entrapment of air bubbles in order, taking a roof ditch of an automobile as an example. The roof ditch is obtained by bending the two steel plates 21 and 22 and overlapping and joining a part thereof. The roof ditch can collect water and the like in the formed U-shaped groove and discharge it to the outside of the vehicle. A seal is formed by embedding a melt-flowable sealing material 50 for preventing rust and improving the appearance in the groove portion. Further, although not shown, the seal is painted to further enhance the appearance quality. Can be.
[0009]
First, as shown in FIG. 1A, a strip-shaped melt-flowable sealing material 50 is formed in a U-shaped groove portion of a roof ditch so as to cover a discontinuous joint (step) A on a bottom surface. Attach.
[0010]
Next, as shown in FIG. 1B, the sealing material 50 is heated to start melting. The sealing material 50 starts to melt from the surface in contact with the panel and starts to flow before completely filling the step A. When the heating is further continued, as shown in FIG. 1C, most of the grooves are filled with the melt of the sealing material 50. At this time, even if the heating operation is performed with care, it is not possible to prevent the small bubbles (air) 51 from being entrained. Entrapment of air bubbles occurs remarkably when there is a panel step as shown in the figure, spots, welding marks such as lasers, and distortion of the panel.
The air bubbles 51 entrained in the sealing material 50 may be acceptable as long as they are taken in the seal (cured material) as they are, but in fact, as shown in FIG. Since the melt viscosity of the sealing material 50 is low, it gradually floats. When the floating bubbles 51 reach the surface of the molten sealing material 50 as shown in FIG. 1E, when the sealing material 50 is cured to form a seal, dents, pinholes, craters, and the like are formed on the seal surface. They remain as defects and cause poor appearance. Further, if there is such a surface defect, even if the coating is performed on the seal, the defect is reproduced as it is, and the adhesion of the paint is not satisfactory.
[0011]
An object of the present invention is therefore to seal discontinuous joints in vehicles, which are easy to handle, do not generate environmentally harmful gases, and have irregular joints. It is an object of the present invention to provide a sealing material that can prevent the entrapment of air bubbles even in the case of a planar shape and thus does not cause poor appearance or coating film defects.
[0012]
[Means for Solving the Problems]
The object described above, according to the present invention, is a vehicle sealing material for sealing a discontinuous joint,
A thermosetting resin composition comprising a melt-curable molded body,
Having a width and length sufficient to substantially cover the junction;
A surface of the molded body, which is in contact with the bonding portion, is provided with a plurality of communication grooves that are oriented in one predetermined direction and arranged in parallel with each other, and
The communication groove can be achieved by a vehicle sealing material, wherein one end of the molded body is a start end and the other end is opposed to the other end.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The vehicle sealing material of the present invention can be advantageously implemented in various forms. Hereinafter, the sealing material of the present invention will be described particularly for use in a roof ditch of an automobile, but it is needless to say that the sealing material is not limited to such an application.
[0014]
The sealing material of the present invention is for sealing a discontinuous joint of an article, particularly a vehicle, that is, for forming a seal. Here, the “article” is typically a vehicle in a broad sense such as an automobile, a truck, a train, a ship, or the like, but may be a building or a bridge if necessary. In addition, the “discontinuous joint” includes, as described above, a joint having an irregular surface form, for example, a lap joint, a step, a joint, a weld, and the like. If such a discontinuous portion is included, the joining process does not have to be actually performed.
[0015]
In the practice of the present invention, the discontinuous joint is preferably a joint of two long steel plates with their long sides overlapped. More preferably, the joint defines a bottom surface of the groove of the long grooved steel plate. Such a grooved steel sheet is typically the roof ditch of an automobile.
[0016]
The sealant of the present invention is generally solid and provided in a shaped, ie, molded, form. Although the form of the molded body can be widely changed depending on the use of the sealing material, it usually includes a rope, a tape, a ribbon, a sheet and the like. These molded articles may be cut into strips of a predetermined length in consideration of handling properties, etc. Otherwise, a long object may be wound into a roll and the required length is used each time. It may be made to cut by the way.
[0017]
The sealing material of the present invention is made of a thermosetting resin composition and is melt-curable. That is, the sealing material is solid at room temperature, but melts when heated to a predetermined temperature, and develops a fluid state. The fluidized sealing material is hardened by cooling thereafter and does not melt again.
[0018]
More specifically, it can be considered that the thermosetting resin composition constituting the sealing material of the present invention can be melt-flowable. That is, when the sealing material containing the resin composition covers and heats the discontinuous joint of the article and is heated, the sealing material first softens and conforms to the surface of the discontinuous part, thereby pushing out the air captured thereby. . Further, during the heat cycle, the resin composition becomes hot, has a tack, and adheres to the surface of the article. Because the sealant composition is thermosetting, it hardens by heating (eg, cross-links by covalent bonds) and is prevented from flowing upon subsequent cooling and reheating.
[0019]
Once cured, the thermosetting resin compositions of the present invention exhibit excellent flexibility, preferably at low temperatures, and are easily bent around a mandrel without cracking or breaking. Preferably, but not limited to, each cured resin composition has an elongation of at least 10% when tested at −20 ° C. Basically, the cured resin composition has an elongation of at least 2% when tested at -20C. In such cases, paints used in vehicles, especially automotive paints, will exhibit about the same or lower elongation when tested at -20 ° C as the cured resin composition. As a result, even if the above-mentioned paint is coated on the surface where the cured resin composition is exposed, it is possible to prevent cracking or breaking prior to the paint. Thus, the sealant can maintain a discontinuous joint coverage to avoid ingress of moisture, dust, snow and other undesirable components into the joint. The composition of the thermosetting resin composition and the like will be described in detail after the form and the like of the sealing material of the present invention are described below.
[0020]
The sealing material of the present invention is particularly characterized by its form. That is, this sealing material
(1) having sufficient width and length to substantially cover the discontinuous joint of the article to which the sealant is to be applied;
(2) The surface of the sealing material in contact with the joint of the article is provided with a plurality of communication grooves arranged in parallel with each other and oriented in one predetermined direction.
(3) Each of the communication grooves has one side of the sealing material as a start end and ends with another side opposite to the one side;
It is characterized by. Hereinafter, these features will be described with reference to a roof ditch sealing material of FIG. 2 which is a typical example of the present invention.
[0021]
FIG. 2 is a perspective view showing a preferred embodiment of a vehicle sealing material according to the present invention. Sealant 10 is in the form of a strip having a length and width sufficient to cover the discontinuous joint of the roof ditch after its melt-cure. The dimensions of the sealing material can be changed in a wide range according to the usage of the sealing material, the form of provision, and the like. However, when the sealing material is in the form of a strip as shown in the drawing, it is usually about 50 to 3,000 mm long. It is about 3 to 50 mm wide and about 1 to 10 mm thick.
[0022]
The sealing material 10 has a large number of regularly arranged communication grooves 15 on one main surface thereof (the surface that is in close contact with the roof ditch). As shown in FIG. 7, the communication grooves 15 are arranged in parallel with each other with a pitch p, which is the interval between the peaks, and each of the communication grooves 15 is oriented in one predetermined direction. I have. In the illustrated example, the angle θ is set with respect to the longitudinal direction.₁The communication grooves 15 are arranged such that That is, in this example, the angle θ₁Is 90 degrees, each communication groove 15 is orthogonal to the sealing material 10. In addition, each communication groove 15 starts at one side of the sealing material 10 and ends at the other side opposite thereto, and therefore, air bubbles trapped between the sealing material 10 and the roof ditch during construction. Can be discharged to the outside without staying on the way. Although the communication grooves 15 are arranged continuously in the illustrated example, they may be arranged at intervals if necessary. This is because the number of surfaces in contact with the roof ditch increases, thereby facilitating construction work.
[0023]
In the illustrated sealing material 10, the communication hole 15 has a V-shaped cross section (sawtooth cross section) as shown in FIG.₂Is about 80 degrees. Naturally, this apex angle θ₂And the aforementioned pitch p and orientation angle θ₁Can be arbitrarily changed according to the desired effect of the sealing material 10 or the like. For example, the orientation angle θ₁Is usually in the range of 20 to 90 degrees, and can be arbitrarily changed within the range. Specifically, the orientation angle θ₁Is 60 degrees, the result is as shown in FIG. 9A, and if it is 30 degrees, the result is as shown in FIG. 9B. Also, the apex angle θ₂Is usually in the range of 30 to 150 degrees, and preferably in the range of 60 to 120 degrees. The pitch p is usually in the range of 0.1 to 4 mm, preferably in the range of 0.3 to 2.1 mm.
[0024]
FIG. 8 shows the communication groove 15 having a V-shaped cross section, but the shape of the communication groove is not limited to this. For example, the communication groove may have a cross-sectional shape such as a rectangle, a semicircle, a U-shape, and a trapezoid, and two or more cross-sectional shapes may be arbitrarily combined if necessary.
[0025]
Further, although the sealing material in which the communication grooves are regularly arranged in a certain direction is shown in the figure, the communication grooves may be arranged in other patterns. For example, a second communication groove group including a plurality of communication grooves arranged in parallel with each other and oriented in one predetermined direction may intersect the communication groove group as described above. May be configured. That is, by forming the lattice-shaped communication grooves by making the communication grooves orthogonal to each other, the discharge of bubbles can be promoted.
[0026]
FIG. 3 is a perspective view showing a roof ditch of an automobile to which the sealing material 10 shown in FIG. 2 is applied. The roof ditch 20 is manufactured by processing two panels, the roof panel 21 and the side panel 22, at right angles, and has a U-shaped groove serving as a flow passage for rainwater or the like. By sealing the step A formed by the splicing of the two panels with the sealing material 10, as described above with reference to FIG. It is also possible to prevent water, dust and the like or other undesired components from entering the lap joint and causing corrosion.
[0027]
It can be easily understood from FIGS. 4 to 6 that the entrapment of air bubbles can be prevented when the sealing material of the present invention is used.
[0028]
For example, as shown in FIG. 4, when there is a possibility that large air bubbles of the air 11 may be trapped and trapped at the step A of the joint between the roof panel 21 and the side panel 22, the conventional sealing material may discharge the air bubbles. However, according to the present invention, a group of communication grooves 15 is provided on the lower surface of the sealing material 10, so that it is possible to escape from the roof panel 21 side as shown by an arrow. That is, as shown in FIG. 5, the air bubbles 11 are discharged to the outside along a wall of the roof panel 21 through a communication groove (not shown) which is not closed. Further, even if the wall surface of the roof panel 21 is closed by the sealing material 10, as shown in FIG. The air bubbles 11 left on the roof panel 21 can escape through the wall surface of the side panel 22.
[0029]
In the sealing material of the present invention, the thermosetting resin composition may be any resin as long as it can exhibit the above-described solid-heat-melt-fluidization-curing behavior and does not adversely affect the operation and effect of the present invention. The composition can be used. Suitable thermosetting resin compositions are typically those containing an epoxy-containing material as a major component.
[0030]
Thermosetting resin compositions suitable for the practice of the present invention, for example,
Thermosetting epoxy-containing materials,
A thermoplastic polyamide component having a softening point below the curing temperature of the epoxy-containing material, and
Curing agent for the epoxy-containing material
It is a resin composition containing.
[0031]
More specifically, in the above thermosetting resin composition, the epoxy-containing material contributes to the ultimate strength and heat resistance of the resin composition, while the thermoplastic polyamide component has shape-following properties, flexibility and Flexibility is imparted, especially at low temperatures. Further, the curing agent enables the curing of the resin composition. Preferably, the curing agent is thermally activated and acts to cure the resin composition upon exposure to a suitable heat source at a suitable time.
[0032]
Useful epoxy-containing materials are epoxy resins having at least one oxirane ring polymerizable by a ring opening reaction. Such materials, broadly referred to as epoxides, include both unimolecular and polymeric epoxides and can be aliphatic, cycloaliphatic or aromatic. Such materials generally have on average at least two epoxy groups per molecule, preferably more than two. Such materials are also referred to as polyepoxides, and include epoxy-containing materials having an epoxy functionality of slightly less than 2.0, for example, 1.8. The "average" number of epoxy groups per molecule is defined as the number of epoxy groups in the epoxy-containing material divided by the total number of epoxy molecules. Polymeric epoxides include a linear polymer having an epoxy group at the terminal (eg, diglycidyl ether of polyalkylene glycol), a polymer having a skeleton of oxirane (eg, polybutadiene polyepoxide), and an epoxy group having an epoxy group as a side chain. (Eg, glycidyl methacrylate polymer or copolymer). The molecular weight of the epoxy-containing material may vary from 58 to about 100,000 or more. Also, mixtures of various epoxy-containing materials can be used.
[0033]
Useful epoxy-containing materials include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylic acid ester, 3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexanecarboxylic acid Esters and those containing a cyclohexene oxide group such as epoxycyclohexane carboxylate represented by bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate are included. Particularly useful epoxy-containing materials are glycidyl ethers of polyhydric phenols obtained by reacting polyhydric phenol with chlorohydrin such as epichlorohydrin in excess (eg, 2,2-bis- (2,3- It is a monomer of diglycidyl ether such as epoxypropoxyphenol) (diglycidyl ether of propane).
[0034]
Many epoxy-containing materials are commercially available and can be used in the practice of the present invention. That is, it is commercially available from Yuka Shell under the product names EPIKOTE 1001, EPIKOTE 1002, EPIKOTE 1003, EPIKOTE 1004, EPIKOTE 828 or EPIKOTE 154.
[0035]
The thermosetting resin composition of the present invention also contains a thermoplastic polyamide component. The thermoplastic polyamide component has an amide moiety represented by the following general formula:
[0036]
Embedded image

References are made to polymeric materials including, and such materials have thermoplastic processing properties. That is, the material is softened by heating and flows to give a shape, and is solidified by cooling. Further, the material softens again upon reheating. This thermoplastic polyamide component can not only achieve the desired mixing with the epoxy-containing material, but can also achieve such mixing with components of other resin compositions that do not promote curing of the epoxy-containing material. is there. The thermoplastic polyamide component also contributes to the excellent low-temperature properties of the sealant composition, especially flexibility.
[0037]
The desired thermoplastic polyamide component mixes (i.e., melt-mixes) with the epoxy-containing material in the melt phase, and preferably forms a uniform single-phase mixture when the epoxy-containing material is not cured. The formation of a homogeneous single phase is evident in such a mixture (melt-mix) becoming transparent. Preferably, from about 90 to about 350 parts by weight of the polyamide component is included per 100 parts by weight of the epoxy-containing material. When the polyamide component is contained at about 90 parts by weight or less, the cured resin composition tends to become brittle. On the other hand, when the polyamide component is contained in an amount of about 350 parts by weight or more, the cured resin composition is not sufficiently crosslinked and tends to flow by reheating. If the epoxy-containing material cures, a multi-phase or separate phase composition results. One phase results from the cured epoxy-containing material and the other phase results from the thermoplastic polyamide component. However, since both phases are formed from a single homogeneous phase consisting of an epoxy-containing material and a thermoplastic polyamide component, even if the epoxy-containing material cures as described above, both phases will be unevenly distributed. I will not. Therefore, the properties resulting from the epoxy-containing material and the thermoplastic polyamide component are imparted to the resin composition. Some degree of non-uniformity is acceptable if the blended thermoplastic polyamide component imparts the desired properties to the resin composition.
[0038]
In addition, a desirable thermoplastic polyamide component has a softening point not higher than the curing temperature of the epoxy-containing material, in order to prevent the epoxy-containing material from being cured when the resin composition is heated on a desired surface and sealed. ing. Further, the resin composition can be melted by heating and easily penetrate into the discontinuous portion. Typically, when the resin composition is used in the automotive industry, the thermoplastic polyamide component has a softening point of about 180 ° C or less.
[0039]
The resin composition contains a curing agent for curing the epoxy-containing material. Preferably, the curing agent is thermally activated to effect curing of the epoxy-containing material under the influence of heat. For example, useful thermally activated curing agents include amide groups, including amines, or imidazole. Preferably, dicyandiamide is typical as a curing agent having an amide group. As a curing agent having imidazole, a triazine derivative is typical. A dicyandiamide curing agent is commercially available, for example, from AC R under the product name "EH3636". Further, a curing agent for a triazine derivative is commercially available, for example, from Shikoku Chemicals Co., Ltd. under the product name of "2MZA".
[0040]
Further, if necessary, the resin composition may be, for example, a filler made of powder of calcium carbonate or silica, for example, an antioxidant commercially available from Ciba-Geigy under the product name "Irganox 1010", for example, Including additives such as UV absorbers marketed by Ciba Geigy under the product name "TINUVIN® P" or surfactants marketed by 3M under the product name of "FC36". It may be.
[0041]
The thermosetting resin composition is solid at room temperature. The resin composition desirably has some tack at room temperature or slightly below. This is because such a tack can firstly perform positioning of a member containing the resin composition to cover a joint or a seam in a roof ditch of a vehicle, for example. However, if the resin composition is in the form of a rope, tape, strip, or the like, quick installation becomes possible, and the material after construction must be treated with skill and effort (for example, when the applied sealing material is used). (Giving an acceptable appearance) can also be eliminated.
[0042]
Further, another thermosetting resin composition suitable for the practice of the present invention, for example,
An epoxy-containing material, including a low hygroscopic epoxidized thermoplastic resin,
A curing agent for the epoxy-containing material, and
filler
It is a resin composition containing.
[0043]
More specifically, the epoxy-containing material used as the first component in the thermosetting resin composition contains a low hygroscopic epoxidized thermoplastic resin, and further contains an epoxy resin and, if necessary, a compatibilizer. .
(1) Low moisture absorption epoxidized thermoplastic resin
Epoxidized thermoplastic resin is a thermoplastic resin having an epoxy group. Generally, a thermoplastic resin can impart a certain shape to a thermosetting resin composition. Further, the epoxidized thermoplastic resin contributes to the thermosetting reaction due to the presence of the epoxy group. As a result, when the thermosetting resin composition is cured, the cured product has heat resistance and durability. In automotive roof ditch sealer applications, this epoxy group allows the cured product to adhere to automotive paints (eg, organic solvent-based acrylic paints and organic solvent-based alkyd paints) and to automotive steel sheets coated with cationic electrodeposition. It will be easier. Further, since the sealer is assembled to the vehicle body before the painting process of the automobile, the color of the vehicle body can be made the same as the color of the vehicle body by painting the sealer at the time of painting the vehicle body. As a result, a cover material such as a mall is not required, and the appearance and appearance of the vehicle body are improved. In addition, the close contact with the steel plate also improves the durability and sealing performance of the sealer.
[0044]
Further, in the thermosetting resin composition, it is necessary that the epoxidized thermoplastic resin has as low hygroscopicity as possible, that is, low hydration. This is because such low hygroscopicity prevents absorption of moisture into the thermosetting composition, and as a result, is advantageous in the automotive coating process. Further, handling such as storage of the thermosetting resin composition is also simplified. The term "low hygroscopicity" means that the epoxidized thermoplastic resin has a saturated water absorption of 0.2 wt% or less at 35 ° C. and a relative humidity of 80% RH. Such epoxidized thermoplastic resins typically have a solubility parameter (SP) of about 9 or less. In this specification, this solubility parameter is defined by Small's equation (described in the document PA Small, {J. Appl. Chem., {3, {71} (1953)}).
[0045]
Usually, such an epoxidized thermoplastic resin has a molecular weight of 1,000 to 10,000 in consideration of flowability during molding and hot melting. The epoxidized thermoplastic resin generally has an epoxy equivalent of 200 to 15,000 in consideration of heat resistance, durability, coating film adhesion and water absorption.
[0046]
A typical example of the epoxidized thermoplastic resin described above is an epoxidized ethylene-based thermoplastic resin. This resin exhibits low hygroscopicity due to the presence of the ethylene moiety. As the epoxidized ethylene-based thermoplastic resin, an ethylene-glycidyl (meth) acrylate copolymer is preferable. This ethylene-glycidyl (meth) acrylate copolymer is obtained by converting polyethylene into an epoxy as disclosed in JP-A-9-137028 and JP-A-10-316955 as one component of an adhesive and a hot melt composition. And usually obtained by copolymerization of ethylene and glycidyl methacrylate. As a result, the ethylene-glycidyl (meth) acrylate copolymer is composed of an ethylene portion and a glycidyl (meth) acrylate portion. In such a case, the ethylene portion contributes to the low hygroscopicity of the thermosetting composition, and the glycidyl (meth) acrylate portion contributes to the adhesion of the later-described automotive paint and the automotive steel plate coated with the cationic electrodeposition. .
[0047]
It is desirable that the ethylene-glycidyl (meth) acrylate copolymer is configured so that the monomer weight ratio of ethylene to glycidyl (meth) acrylate is in the range of 50:50 to 99: 1. Ethylene-glycidyl (meth) acrylate copolymers containing ethylene exceeding the upper limit tend not to impart desired mechanical strength and durability to the cured product. Conversely, ethylene-glycidyl (meth) acrylate copolymers containing ethylene below the lower limit tend to be unable to obtain the desired low hygroscopicity.
[0048]
Further, a typical ethylene-glycidyl (meth) acrylate copolymer is easily melted even at a relatively low temperature of about 120 ° C. or less, and has a high flow rate when a thermosetting resin composition containing the same is heated and fluidized to seal. , Resulting in an appearance with high uniformity and smoothness. In addition, since it is possible to knead at a relatively low temperature in the heating and mixing process at the time of producing the sealer, there is little possibility that a reaction between the thermosetting component and the curing agent occurs during kneading, and further, a curing agent having higher reactivity is selected. You can also.
[0049]
As long as the effects of the present invention are not impaired, a ternary ethylene-glycidyl (meth) acrylate copolymer obtained by copolymerizing or graft-polymerizing a third component other than ethylene and glycidyl (meth) acrylate is used as the epoxidized thermoplastic resin. May be used. Examples of such a terpolymer include copolymers of alkyl (meth) acrylate and vinyl acetate, and examples of the graft polymer include polystyrene, polyalkyl (meth) acrylate, and acrylonitrile-styrene copolymer. It is obtained by grafting coalescence.
[0050]
Another typical example of an epoxidized thermoplastic resin is an epoxidized styrenic thermoplastic resin, which exhibits low hygroscopicity due to the presence of a conjugated diene. The epoxidized styrene-based thermoplastic resin is, for example, a block copolymer having a hard segment made of polystyrene and a soft segment made of epoxidized polybutadiene and imparting rubber elasticity to the elastomer. Alternatively, epoxidized polyisoprene can be used instead of, or in conjunction with, epoxidized polybutadiene.
[0051]
Usually, the glass transition temperature (Tg) of the epoxidized styrene-based thermoplastic resin is as very low as −70 to −50 ° C. At this time, the cured product of the thermosetting resin composition at a low temperature of about −30 ° C. Durability (particularly, vibration durability) can be enhanced. As a result, the epoxidized styrene-based thermoplastic resin is very advantageous for use in a sealer where a stress is repeatedly applied even at a low temperature, for example, a sealer for a roof ditch of an automobile as described above. In the case of a roof ditch sealer for an automobile, the styrenic portion and the epoxy group of the epoxidized styrene-based thermoplastic resin allow the cured product to be coated with an automobile paint (for example, an organic solvent-based acrylic paint or an organic solvent-based alkyd paint) and a cationic resin. It comes into close contact with the electrodeposited automotive steel sheet.
[0052]
Examples of such an epoxidized styrene-based thermoplastic resin are a styrene-epoxidized butadiene-styrene copolymer and a styrene-epoxidized isoprene-styrene copolymer. In either case, the epoxidation is performed by epoxidizing the unsaturated bonds of the conjugated diene.
[0053]
It is preferable that the low moisture-absorbing epoxidized thermoplastic resin is contained in the thermosetting resin composition in an amount of 10 to 90% by weight. If the amount is less than about 10% by weight, the heat resistance and the low hygroscopicity decrease, and if the amount exceeds about 90% by weight, the filler is relatively reduced and a low linear expansion coefficient may not be obtained.
(2) Epoxy resin
As the epoxy-containing material, in addition to the epoxidized thermoplastic resin described above, for example, a liquid or solid epoxy resin such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolak type epoxy resin, and a glycidylamine type epoxy resin may be used. Incorporation further enhances the heat resistance and durability of the cured product of the thermosetting resin composition and the adhesion with the above-mentioned automotive paint. Desirable epoxy resins, for example, hydrogenated bisphenol A type epoxy resin, alicyclic epoxy resin, linear aliphatic epoxy resin such as butadiene skeleton epoxy resin, or glycidyl ester type epoxy resin such as dimer acid modified epoxy resin, Epoxy resin with relatively low polarity. This is because the epoxidized thermoplastic resin has excellent compatibility with low water absorption components, for example, an ethylene portion and a butadiene portion. Further, the absorption of moisture into the cured product is prevented, which is advantageous in the automobile coating process as described above. The amount of the epoxy resin is usually 0 to 500 parts by weight, preferably 5 to 400 parts by weight, based on 100 parts by weight of the component (1), that is, the low hygroscopic epoxidized thermoplastic resin.
(3) Compatibilizer
If desired, the epoxy-containing material may further include a compatibilizer. More specifically, the compatibilizer is usually contained in an amount of 0 to 300 parts by weight, preferably 1 to 100 parts by weight, based on 100 parts by weight of the low moisture-absorbing epoxidized thermoplastic resin. The compatibility between the thermoplastic resin and the epoxy resin can be increased. In the present invention, the compatibilizer is not particularly limited as long as the above-mentioned compatibility can be achieved, but preferably includes a polyester resin or an ethylene-vinyl acetate copolymer (EVA). In particular, when the polyester resin is blended with the low-hygroscopic epoxidized thermoplastic resin in a predetermined ratio, not only does the separation of the low-hygroscopic epoxidized thermoplastic resin and the epoxy resin be prevented, but also the thermosetting This is because the fluidity at the curing temperature (100 to 160 ° C.) of the composition can be significantly improved.
[0054]
In combination with the epoxy-containing material described above, a curing agent for this material is used. The curing agent cures an epoxy group contained in the epoxidized thermoplastic resin and the epoxy resin to provide a crosslinked structure in the thermosetting resin composition, thereby obtaining a cured product.
[0055]
According to the present invention, the curing agent is not limited as long as a cured product can be obtained. Therefore, the curing agent is, for example, an amine compound such as dicyandiamide, an acrylic compound or rosin having a carboxyl group (including an acid anhydride) in a molecule, an imidazole derivative, a BF3 complex, an organic acid hydrazide, diaminomaleonitrile, or Melamines or mixtures thereof may be included. Further, the polarity of the curing agent is not limited. However, the curing of the glycidyl group of the ethylene-glycidyl (meth) acrylate copolymer involves the inclusion of a carboxyl group in the molecule, as disclosed in JP-A-9-137028 and JP-A-10-316955. It is required to use a curing agent containing an acrylic compound or rosin. Compared to a highly polar curing agent that is not compatible with the ethylene-glycidyl (meth) acrylate copolymer and cannot react substantially, such a curing agent is easily compatible with the ethylene-glycidyl (meth) acrylate copolymer. This is because the glycidyl group of the ethylene-glycidyl (meth) acrylate copolymer is cured.
[0056]
The curing agent may be used in combination with a curing accelerator. In particular, for the reaction between the curing agent having a carboxyl group and the epoxy, a curing accelerator containing a phenol-containing substance, an imidazole derivative or a tertiary amine can be advantageously used.
[0057]
A filler containing, for example, calcium carbonate or silica or a mixture thereof is further added to the thermosetting resin composition. The filler can reduce the coefficient of linear expansion of the cured product. As a result, such a cured product was formed by applying the above-mentioned automotive paint thereon, in which the linear expansion coefficient was reduced, and the amount of shrinkage at a low temperature was reduced, especially at the above-mentioned temperature change at a low temperature. It becomes difficult to apply stress to the coating film. Thus, the formed coating film is hard to crack even at a low temperature.
[0058]
When the filler is added as described above, generally, the thermosetting resin composition may be accompanied by undesired fluidity during heating and melting. Therefore, the thermosetting resin composition of the present invention preferably contains a plasticizer. By including a plasticizer, the thermosetting resin composition of the present invention maintains desired fluidity. This is because the plasticizer generally has a low viscosity and can contribute to improving the fluidity of the composition.
[0059]
Plasticizers that may be included in the thermosetting resin composition of the present invention include, for example, phthalates such as di-2-ethylhexyl phthalate or diisononyl phthalate, adipic esters, epoxidized fatty acid esters, Contains epoxidized soybean oil, epoxidized linseed oil, liquid terpene resin, liquid terpene phenol copolymer or liquid terpene styrene copolymer, azelaic esters, sebacic esters, epoxy hexaphthalic esters or mixtures thereof Plasticizer. Such a plasticizer can impart flexibility to a cured product of the thermosetting resin composition. Further, the cured product can lower the glass transition temperature and lower the elastic modulus even at a low temperature of −20 to −40 ° C. As a result, the cured product can greatly expand at such a low temperature, and dynamic durability such as vibration durability can be improved.
[0060]
A sealing material having a predetermined shape such as a sheet, tape, rope or strap formed by molding such a thermosetting resin composition is disposed on a discontinuous portion such as a joint. The sealant can then be melted and flowed by heating to seal discontinuities. That is, when heated in a state where the discontinuous portion is covered, it softens and adapts to the surface of the discontinuous portion, thereby pushing out the trapped air. Thereafter, the sealant cures upon heating (ie, crosslinks by covalent bonds) and prevents flow upon subsequent cooling and reheating.
[0061]
In the automotive industry, this discontinuity is found, for example, in the roof ditch, where the sealant is applied. Such a sealing material is restrained not only on the bottom surface of the roof ditch but also on the side walls. The roof ditch may exert a stress on the sealing material from the side wall due to the deflection or deflection of the panel constituting the roof ditch. However, due to the elasticity of the above-described thermosetting resin composition, the sealing material can flexibly follow even when subjected to stress from the side wall at a relatively low temperature of about -30 ° C, and is not easily cracked. As a result, intrusion of dust, moisture and other undesired components can be prevented.
[0062]
In the automotive industry, curing is performed in a heating process while a coating film is provided on the sealing material in a coating process after the sealing material of the roof ditch is melted and flowed by heating. This coating film is constrained by the side walls of the roof ditch similarly to the sealing material, and also constrained by the sealing material. As a result, interfacial stress generally occurs between the coating and the sealant. Usually, this interfacial stress is often observed at low temperatures. At low temperatures, typical sealants are susceptible to shrinkage. This interfacial stress (P) is expressed by the following equation at a temperature (T) below the glass transition temperature of the sealing material, based on the assumption that the interface stress (P) is usually relaxed at a temperature higher than the glass transition temperature (Tg) of the sealing material. You.
[0063]
P = ΔT · E · Δα
Here, ΔT: T−Tg, E: elastic modulus of the sealing material, Δα: difference in linear expansion coefficient between the coating film and the sealing material.
[0064]
In the case of the sealing material of the present invention, as described above, the elastic modulus is low and the difference in linear expansion coefficient is small. As a result, at a low temperature such as −40 to −20 ° C. below the glass transition temperature (specifically −30 to −10 ° C.) of the sealing material of the present invention, the stress is reduced and cracks of the coating film are prevented. Will be able to do it.
[0065]
Further, the sealing material of the present invention has reduced moisture before and after curing as described above. As a result, even if the sealing material is left under high temperature and high pressure for several days before the painting process and then subjected to the painting process, the sealing material does not adhere to the discontinuous portion because the water expands due to foaming. Delamination or lifting can be prevented, and intrusion of dust, moisture and other undesirable components can be avoided. In addition, such a sealing material can sufficiently adhere to a coating film or provide a favorable appearance to the coating film.
[0066]
Further, the above-mentioned thermosetting resin composition may contain a crystallization agent composed of fine metal particles, inorganic particles, crystalline polymers, and organic pigments. Such a crystallization agent can promote crystallization of the crystalline resin when the thermosetting composition contains a crystalline resin such as polyester, and as a result, the thermosetting resin It is possible to prevent the performance of the composition and the sealing material as a molded product thereof from changing over time.
[0067]
In addition, the thermosetting resin composition may further include a modifier for improving adhesion to a coating film provided thereon, as long as the effects of the present invention are not impaired. Such a modifier is a tackifier such as a terpene-based resin or an olefin copolymer obtained by copolymerizing a component having a relatively high polarity.
[0068]
Using the thermosetting resin composition as described above, the sealing material of the present invention can be produced by various molding methods. The obtained molded body may be used as it is, may be cut into a predetermined size, or may be wound into a roll.
[0069]
【Example】
Subsequently, the present invention will be described with reference to examples thereof. Needless to say, the present invention is not limited by these examples.
Example 1
Production of sealing materials:
The following components were uniformly mixed in the amounts described to prepare a thermosetting resin composition.

These components were charged into a twin-screw extruder and kneaded until uniform. Next, the obtained resin composition was extruded from an extruder, applied to a silicone-treated surface of a PET film having a thickness of 100 μm using a hot knife coater (comma coater type), and dried. A resin sheet having a thickness of 4 mm was obtained.
[0070]
The obtained resin sheet is placed on a two-liquid silicone resin sheet molding die having a group of sawtooth-shaped protrusions of a right-angled isosceles triangle (1 mm at the base and 0.71 mm at the isosceles) continuously at a pitch of 1 mm. The group of protrusions of the mold was transferred to a resin sheet by heat pressing. When the resin sheet was peeled off from the mold, a sealing material having V-shaped narrow grooves continuously formed on one surface was obtained.
[0071]
Next, the obtained sealing material was cut into a strip having a width of 7 mm and a length of 150 mm to fit a U-shaped groove of the roof ditch in order to be subjected to a simulation test of a roof ditch of an automobile. This strip-shaped sealing material had the form described above with reference to FIG. 2, and on one side thereof, a V-shaped communication groove was continuously arranged at right angles to the longitudinal direction. The size of each communication groove will be described with reference to FIGS.₁= 90 degrees, pitch p = 1mm, angle θ₂= 90 degrees, and one side of the groove 15a = 0.71 mm.
Example 2
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 90 degrees, pitch p = 2 mm, angle θ₂= 90 degrees, and the side 15a of the groove was changed to 1.4 mm.
Example 3
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 60 degrees, pitch p = 1mm, angle θ₂= 90 degrees and one side of the groove 15a = 0.71 mm. That is, in the sealing material of this example, the pattern of the communication groove was changed as shown in FIG.
Example 4
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 30 degrees, pitch p = 1mm, angle θ₂= 90 degrees and one side of the groove 15a = 0.71 mm. That is, in the sealing material of this example, the pattern of the communication groove was changed as shown in FIG. 9B.
Example 5
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 90 degrees, pitch p = 2 mm, angle θ₂= 120 degrees, and the side of the groove 15a was changed to 1.2 mm.
Example 6
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 90 degrees, pitch p = 1mm, angle θ₂= 120 degrees, and one side of the groove 15a was changed to 0.6 mm.
Example 7
Although the method described in the first embodiment was repeated, in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 90 degrees, pitch p = 1mm, angle θ₂= 60 degrees, and one side of the groove 15a = 1 mm.
Example 8
The method described in Example 1 was repeated. In this example, when the obtained sealing material is subjected to a simulation test of a roof ditch of an automobile, a preliminary drying (precuring) process described in the following evaluation test section is performed. The conditions were changed from 120 ° C / 15 minutes (material temperature) to 140 ° C / 30 minutes (material temperature).
Comparative Example 1
The method described in Example 1 was repeated, but in this example, a V-shaped communication groove was omitted from the surface of the sealing material for comparison. That is, in this example, the obtained resin sheet was thermoformed on a flat mold to produce a sealing material having a flat surface.
Comparative Example 2
The method described in Example 1 was repeated, but in this example, for comparison, a communication groove was formed so as to be parallel to the longitudinal direction of the sealing material. That is, the sealing material of this example has a pattern of communication grooves as shown in FIG. 10, and the size of each communication groove 15 is the angle θ.₁= 0 degree, pitch p = 1mm, angle θ₂= 90 degrees, and one side of the groove 15a = 0.71 mm.
Comparative Example 3
The method described in Comparative Example 2 was repeated, but in this example, the size of the communication groove of the sealing material was changed to the angle θ.₁= 0 degree, pitch p = 1mm, angle θ₂= 120 degrees, and one side of the groove 15a was changed to 0.6 mm.
Comparative Example 4
The method described in Comparative Example 2 was repeated. In this example, when the obtained sealing material was subjected to a simulation test of a roof ditch of an automobile, a preliminary drying (precuring) process described in the following evaluation test section was performed. The conditions were changed from 120 ° C / 15 minutes (material temperature) to 140 ° C / 30 minutes (material temperature).
Practice exam
Using the sealing materials manufactured in the above Examples and Comparative Examples, a simulation test of a roof ditch of an automobile was performed according to the following procedure. This simulation test is for evaluating whether or not a high-quality seal can be provided without entrainment of air bubbles when a sealing material is actually used for sealing a roof ditch.
(Preparation of test pieces)
In order to simulate the roof ditch of an automobile, a test piece having a form similar to the roof ditch shown in FIG. 3 was produced from a panel made of a cold-rolled steel plate having a thickness of 0.8 mm. After the two panels were bent on a crank as shown in the figure, the end faces of the respective panels were overlapped with each other, spot-welded, and finally the entire panel was subjected to an automotive-grade cationic electrodeposition coating. The size of the obtained test piece having a U-shaped groove is as follows: length L = 400 mm, groove width w = 9 mm, depth d = 7 mm, height A of step A = 0.8 mm, width a = 3 mm. Met.
(Practice exam)
As shown in FIG. 3, a sealing material was attached to the groove portion of the manufactured test piece such that the communication groove of the sealing material covered the step of the test piece. Next, the test piece was placed in a constant temperature oven at 120 ° C. for 15 minutes (leave at material temperature). This simulates pre-drying of a sealing material usually performed in an automobile painting line, and is called pre-cure. In this pre-curing step, the solid sealing material was melted and flowed by heating, and the groove was filled so as to cover the vertical walls on both sides of the groove.
[0072]
Subsequently, the following heating steps were sequentially performed to simulate the coating steps normally performed in an automobile coating line. The coating was not actually performed in these heating steps.However, when there is a coating film on the surface of the seal formed by curing the sealing material, the diameter of the entrained bubbles on the seal surface is measured. Because it is difficult.
First heating step:
The test piece was placed in a constant-temperature oven and heated (material temperature) at 140 ° C. for 30 minutes to simulate the intermediate coating process usually performed by electrostatically applying an acrylic solid paint to cure the sealing material.
Second heating step:
The test piece was placed in a constant-temperature oven and heated (material temperature) at 140 ° C. for 30 minutes to harden the sealing material, simulating a topcoating process usually performed by electrostatically applying an acrylic solid paint.
[0073]
After the above heating step was completed, the test piece was left at room temperature for 24 hours, and the surface of the obtained seal was visually observed, and the number of air bubbles observed was counted. The number of air bubbles measured for each test piece (average value of five measurements) is shown in Table 1 below.
[0074]
Next, the bubbles in each of the seals were observed with a microscope manufactured by KEYENCE CORPORATION (model number VH-6300) at a magnification of 20 times, and the diameter D of each bubble was measured from the monitor. The bubble diameter D (average of five measurements) was applied to the following equation (sphere volume equation).
[0075]
Volume of sphere V = (4/3) × π × (D / 2)³
Then, the total volume V of the spheres was obtained for each test piece, and the sum was averaged to calculate the bubble-converted volume per test piece (the volume of the bubbles presumed to be involved in the seal). The resulting bubble-converted volume is shown in Table 1 below.
[0076]
[Table 1]

As can be understood from the evaluation results in Table 1 above, in Examples 1 to 8, when the sealing material was melted and hardened, air bubbles trapped under the sealing material could escape through the uneven communication groove. As a result, the number of places where bubbles were trapped per test piece was small, and even if bubbles were trapped, the volume was small and could be kept within an acceptable range. Therefore, the sealing materials of these examples were determined to be acceptable (O).
[0077]
On the other hand, when the adhesive surface (seal surface) of the sealing material is untreated and smooth as in Comparative Example 1, the number of air bubbles involved in each test piece is extremely large, and the air bubble equivalent volume is large. Met. Furthermore, when the communication grooves were provided in parallel with respect to the longitudinal direction of the sealing material as in Comparative Examples 2 to 4, large defects occurred because bubbles were accumulated. Therefore, the sealing materials of these comparative examples could only be judged as failed (x).
[0078]
【The invention's effect】
As described in detail above, according to the present invention, handling is easy, no gas harmful to the environment is generated, and even when the joint has an irregular surface shape, the entrapment of air bubbles is prevented. Thus, it is possible to provide a sealing material for vehicles that does not cause appearance defects or coating film defects. The sealing material of the present invention can sufficiently exhibit its function and effect particularly when applied to sealing of a discontinuous joint portion of a vehicle, for example, a roof ditch.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating generation of bubbles in a conventional melt-flow type sealing material.
FIG. 2 is a perspective view showing a preferred embodiment of a vehicle sealing material according to the present invention.
FIG. 3 is a perspective view showing the use of the sealing material shown in FIG. 2 in a roof ditch.
FIG. 4 is a perspective view showing a principle of preventing air bubbles from being trapped in the roof ditch shown in FIG. 3;
FIG. 5 is a cross-sectional view schematically showing an escape route of bubbles in the roof ditch shown in FIG.
FIG. 6 is a cross-sectional view schematically showing a bubble escape route in the roof ditch shown in FIG.
FIG. 7 is a longitudinal bottom view showing the arrangement of communication grooves in the sealing material shown in FIG. 2;
FIG. 8 is a longitudinal sectional view showing a shape of a communication groove of the sealing material shown in FIG. 2;
FIG. 9 is a bottom view showing another arrangement pattern of the communication grooves in the sealing material of the present invention.
FIG. 10 is a bottom view showing an arrangement pattern of communication grooves in a sealing material used in a comparative example.
[Explanation of symbols]
10. Sealing material
11 ... air bubbles
15… Communication groove
20 ... Roof ditch
21 ... Roof panel
22 ... Side panel

Claims (9)

A vehicle sealing material for sealing discontinuous joints,
A thermosetting resin composition comprising a melt-curable molded body,
Having a width and length sufficient to substantially cover the joint;
The surface of the molded body, which is in contact with the joint, is provided with a plurality of communication grooves that are oriented in one predetermined direction and are arranged in parallel with each other, and the communication groove is formed by the molded body. A sealing material for a vehicle, characterized in that one side of the sealing material is a starting end and the other end facing the other is ending. 2. The vehicle sealing material according to claim 1, wherein the joining portion is a joining portion of two long steel plates in which long sides are overlapped with each other. 3. The vehicle sealing material according to claim 1, wherein the joint defines a bottom surface of the groove of the long grooved steel plate. The sealing material for a vehicle according to claim 3, wherein the grooved steel plate is a roof ditch of an automobile. The vehicle according to any one of claims 1 to 4, wherein the communication groove has a cross-sectional shape selected from the group consisting of a rectangle, a semicircle, a V shape, a U shape, and a trapezoid. Sealing material. The thermosetting resin composition,
Thermosetting epoxy-containing materials,
The vehicle according to any one of claims 1 to 5, further comprising a thermoplastic polyamide component having a softening point equal to or lower than a curing temperature of the epoxy-containing material, and a curing agent for the epoxy-containing material. Sealing material. The thermosetting resin composition,
An epoxy-containing material, including a low hygroscopic epoxidized thermoplastic resin,
The vehicle sealing material according to claim 1, further comprising a curing agent for the epoxy-containing material and a filler. The sealing material according to claim 7, wherein the thermosetting resin composition further contains a plasticizer. 8. The low hygroscopic epoxidized thermoplastic resin is at least one thermoplastic resin selected from the group consisting of an epoxidized ethylene-based thermoplastic resin and an epoxidized styrene-based thermoplastic resin. Or the sealing material for vehicles according to 8.

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