JP3561813B2

JP3561813B2 - Polyurethane mold molded product with waterproofness

Info

Publication number: JP3561813B2
Application number: JP5411795A
Authority: JP
Inventors: 公一草川; 敏明木村; 忠広岡部
Original assignee: NHK Spring Co Ltd
Current assignee: NHK Spring Co Ltd
Priority date: 1995-03-14
Filing date: 1995-03-14
Publication date: 2004-09-02
Anticipated expiration: 2019-09-02
Also published as: JPH08245742A

Description

【０００１】
【産業上の利用分野】
本発明は、自動車、電車等の輸送車両や建設機械などのように常に振動を伴い、高防水性と耐油性を必要とする部位に、シ−リング材や防音材として好適な防水性を有するポリウレタンモ−ルド成形品に関する。
【０００２】
【従来の技術】
従来から防水性を有するポリウレタン発泡体は、スラブ状の製品として、或いは両面スキン層を有する製品として連続方法で製造され、防水シ−リング材、防音材、防振材として自動車や電車等の輸送車両、建設機械、住宅建築、電気機器などで広く使用されている。
【０００３】
スラブ状の製品は、ベルトコンベア上に混合されたポリウレタン原料を流し出すことによって自由発泡させて製造されるため、スラブ状の製品はスキン層のない成形品として得られ、これを所望の形状に切り出し、貼合わせ、熱圧縮成形しても、全面にわたり発泡体コア部となって、その表面にはスキン層が形成されない。
また、２つのベルトの間に混合されたポリウレタン原料を塗布し、発泡するポリウレタンを上方のベルトで高さ方向を規制して発泡させた発泡体成形品は、上下の両面のスキン層が形成されるが、これより所望の形状に切り出して製品とした場合、その切出し断面にはスキン層がなく、自己スキンのない発泡体コア部となった。
【０００４】
しかし、ポリウレタン発泡体よりなる成形体に自己スキン層を設けると、ポリウレタン発泡体の吸油量（耐油性）、吸水量（吸水性）を減少させると共に、発泡体の保護被覆層として作用し、該発泡体よりシ−リング材を形成した場合、防水面との密着性が向上し、特に振動を伴う自動車等の輸送車両、建設機械のシ−リング材として極めて好適である。また密着性が向上するため、振動防止効果、隙間からの音洩れ防止効果が発揮され防音材としても好適である。従って、従来のポリウレタン発泡体よりなる成形体に自己スキン層を設けることが望まれた。
従来のポリウレタン発泡体にスキン層を形成することが考えられ、例えば、従来のスラブ状の製品の表面にフィルム等を貼着、一体成形すると、フィルム層自体及びフィルム層と発泡体の接合部が硬くなり、防水面との馴染み性や防水面との密着性が劣り、馴染み性、密着性が劣ると、シ−リングされる個所に隙間が発生し、防水性が劣る等の欠点が生じ、十分な効果が発揮できなかった。また、スラブ状の製品より所望の形状のシ−リング材を製造するには切り出しを行うので、発泡体の全面にはスキン層を設けられず、立体的な複雑形状を再現することは難しく製造工程が複雑である等の欠点があった。
【０００５】
また、両面スキン層を有する発泡体よりシ−リング材を熱圧縮成形しても、発泡体の全面には自己スキンが得られないのみならず、熱圧縮成形すると、発泡体が熱劣化し、防水性が低下し、また、自己スキンの開口率が増大し、耐油性及び防水性が低下するという欠点があった。殊に、立体的な複雑形状を成形しようとしても再現出来ないので、防水面との密着性が劣り、密着性や馴染み性が劣ると、隙間が発生し漏水し、その結果、発泡体自身が有する防水性を十分に発揮できなかった。また、両面スキン層を有する発泡体より熱圧縮成形したものは、耐油性及び防水性を考慮した自己スキンとは成っていない。
ところで、近年、立体的な複雑形状をした防水面への対応が望まれるように成った。例えば、ドア−ミラ−とボディの接合部、テ−ルランプとボディの接合部、或いは、エンジンル−ム内等の防水防音材において、防水性の向上したシ−リング材が要求されるようになった。そして、これらのシ−リング材などにおいては、エンジンオイル等の各種オイルが一時的に接触する可能性があり、また、新車納入時に、塗装保護剤を燈油と界面活性剤からなるワックスリムバ−で洗車するため、防水性と共に耐油性をも必要となった。
【０００６】
【発明が解決しようとする課題】
そこで、本発明者は、上述の欠点を改良し、これらの要求を満足すべきシ−リング材や防音材について、種々検討した結果、ポリウレタン発泡体をモ−ルド成形して特定の性質を付与した全面に渡って自己スキン層を有する成形品が、従来技術の欠点を改良し、耐油性と防水性を向上した防水性を有するポリウレタンモ−ルド成形品となることを見出し、本発明を完成したもので、本発明の目的は耐油性と防水性を向上した防水性を有し、全面に渡って自己スキン層を有するポリウレタンモ−ルド成形品を提供するものである。
【０００７】
【課題を解決するための手段】
本願発明の要旨は、ポリイソシアナ−トとポリオ−ルを触媒、発泡剤等の助剤の存在下でモ−ルド内にて発泡硬化させて得た自己スキン層を有する密度０．０４〜０．３ｇ／ｃｍ ³のポリウレタン発泡体よりなる防水性を有するポリウレタンモ−ルド成形品であって、該ポリウレタンモ−ルド成形品は、
（１）水との接触角が８５°以上
（２）コア部１０ｍｍ厚さの通気度が１０ｃｃ／ｃｍ²／ｓｅｃ以下
（３）自己スキンは、厚さ５０μｍ以下、開口率が１０％以下、自己スキン層を有する表面部分の引張り弾性率が５０ｇ／ｍｍ²以下、
であることを特徴とする防水性を有するポリウレタンモ−ルド成形品である。
【０００８】
即ち、本発明においては、ポリウレタン発泡体の水との接触角及び通気度は、防水性を有するポリウレタン発泡体をモ−ルド成形で得る上で重要な要素となるものであり、接触角が８５°以上を有し、コア部１０ｍｍ厚さの通気度が１０ｃｃ／ｃｍ^２／ｓｅｃ以下（以下、単に通気度と言う）であるポリウレタン発泡体を得ることで防水性を向上する。
以下、本発明のそれぞれの特性と該特性を得る方法について説明する。
【０００９】
（１）常温における沸点が２００℃以上、融点或いは軟化点が１５０℃以下である実質的に炭化水素化合物からなる物質をポリウレタン原料中に添加し、特定通気度以下にする。ただ、本発明はモ−ルド成形性（スキン性）であるので、この点を考慮すると添加量の少ないことが好ましく、まったく添加しない場合もある。
（２）気泡生成に必要なシリコ−ン整泡剤として、その分子末端に、ウレタンと反応性を有する水酸基、アミノ基、カルボニル基、メルカプト基等の基を有する反応性シリコ−ン整泡剤を使用することが好ましい。本発明では、モ−ルド成形性（収縮）を考慮すると、低通気度発泡体と成り得る場合は、非反応性シリコ−ンで破泡剤と働くポリジメチルシロキサンオイルを使用することができる。
【００１０】
（３）主原料のポリオ−ル成分として、ポリエ−テルポリオ−ル、ポリブタジェンポリオ−ル、ダイマ−酸エステルポリオ−ル、ヒマシ油ポリオ−ルの単独もしくはこれらの混合物として使用する。本発明では、特にエチレンオキサイドを５モル％以上を含有するポリエ−テルポリオ−ルを使用すると、モ−ルド成形性が良く好ましい。エチレンオキサイドが２０モル％を超えると吸水性が悪化するので好ましくない。エチレンオキサイドが１０モル％を超えると吸水性が上昇する傾向にあり、この場合、イソシアナ−トは、ＭＤＩを使用するか、ＴＤＩとＭＤＩを併用することが好ましい。
（４）発泡体の通気度は、１０ｃｃ／ｃｍ^２／ｓｅｃ以上の時、吸水性が増大する。本発明では、通気度の調整は、ポリオ−ルの種類及び触媒や発泡剤等の助剤の種類や添加量、攪拌条件、溶存エア−量（原料中に溶存するエア−量）、反応温度等において変化するので、これらを調整して、１０ｃｃ／ｃｍ^２／ｓｅｃ以下とする。
【００１１】
本発明において発泡体の自己スキン層は、自己スキンの厚さ、開口率、引張り弾性率の相互のバランスにおいて、高防水性と耐油性とを向上させることと、防水面との馴染み性及び密着性を向上し高防水性を発揮させる等で重要な要素となるものである。自己スキン層は、厚さ５０μｍ以下、開口率が１０％以下、好ましくは０％、引張り弾性率が５０ｇ／ｍｍ²以下とすることによって、所期の目的を達成することができる。
（１）自己スキンの厚さが５０μｍ以上の場合には、厚さが増す程、自己スキンが硬く、防水面との馴染み性が損われポリウレタン発泡体自身が有する防水性能が十分に発揮しできず、漏水の発生が生じやすい。また、開口率が増す程、耐油性と防水性が悪化する。本発明では、自己スキンの厚さの調整は、モ−ルド内への原料注入量（パック率）、成形温度（型温度）、触媒や発泡剤等の助剤の種類や添加量、反応温度等によって調整する。また、開口率の調整は、モ−ルド成形時に使用する離型剤の種類や塗布量、ポリオ−ルのエチレンオキサイド含有量、助剤の種類や添加量等によって行う。
【００１２】
（２）自己スキンの引張り弾性率が５０ｇ／ｍｍ^２以上の場合は、自己スキンが硬いものとなり防水面との馴染み性が損われポリウレタン発泡体自身が有する防水性能を十分に発揮し得ない。後述の馴染み指数で６ｍｍ以上となり好ましくない。
本発明では、引張り弾性率の調整は、自己スキンの厚さ調整とポリオ−ル、イソシアナ−ト、その他助剤の種類や添加量等において変化するので、これらを調整する。
これらの調製により、自己スキンの厚さが５０μｍ以下、開口率が１０％以下、引張り弾性率が５０ｇ／ｍｍ^２以下、（馴染み指数６ｍｍ以下）を満足する場合において、耐油性と防水性が向上するのである。
【００１３】
次に本発明の各特性の測定方法について説明する。
各特性の測定は、厚さ２０ｍｍ×２２０ｍｍ×２２０ｍのモ−ルド成形品を試験片として使用。
▲１▼密度は、ＪＩＳＫ−６４０１に準拠し試験片として測定。
▲２▼通気度は、ＪＩＳＬ−１００４に準拠し、東洋精機社製の通気度試験機Ｎｏ．８６９を用い試験片の自己スキンを上下面各５ｍｍを除去した発泡体コア部１０ｍｍ厚さとして測定。
【００１４】
(3)水との接触角は、試験片の自己スキンを上下面各５ｍｍを除去した発泡体コア部より厚さ１０ｍｍ×５０ｍｍ×５０ｍｍを採取し、アルミ箔に挟み温度１８０〜２００℃、圧力５０〜６０ｋｇ／ｃｍ²で熱プレスすることで表面平滑なフィルム状とし協和科学社製の協和接触角計ＣＡ−Ａを用い測定。
(4)自己スキンの厚さと表面開口率は、走査型電子顕微鏡にて写真撮影して測定する。自己スキンの厚さの測定については、試料１のモ−ルド成形品の中央部を長さ方向に切断し、端部から１０ｍｍ位置を基準に５０ｍｍピッチで自己スキン断面部の拡大写真を５点撮影し、隣合わせのリブ２とリブ３の中心線４に接する自己スキンの厚さ５を測定し５点の平均厚さを求める。図１は走査型電子顕微鏡写真の模式図であって、その測定法を示す。自己スキンの開口率は、モ−ルド成形品の中央部を長さ方向において端部から１０ｍｍ位置を基準に５０ｍｍピッチで自己スキン部の拡大写真を５点撮影し、個々の１ｍｍ角における開口部分の面積比を測定し、５点の平均開口率を求める。
(5)自己スキンの引張り弾性率は、ＪＩＳＫ−７１２７に準拠し、自己スキンを有する表面部分厚さ２ｍｍにスライスしたあと、ダンベル１号打ち抜き試験片をオリエンテック社製のテンシロン万能試験機ＵＣＴ５００を用い引張り速度５０ｍｍ／分で５％伸長した時の引張り応力−ひずみ曲線の初めの直線部分における単位面積当りの荷重を測定。
尚、引張り弾性率は、次式より求める。
引張り弾性率Ｅｍ＝Δδ／Δε
Δδ＝直線上の２点間の元の平均断面積による応力の差（ｇ／ｍｍ²）
Δε＝同じ２点間のひずみの差
(6)馴染み指数は、図２に示すように、鉄板製の試験片保持台６の上に試験片１を載せ、試験片１の表面に直径２ｍｍの鋼球７を乗せた後、５０ｍｍ×５０ｍｍで厚さ１ｍｍのガラス板８を試験片１の表面に置き、その際、鋼球２が圧縮挿入されて発生した空間凹みの直径ｄを５秒後にミリメ−トル単位で測定し、その数値を馴染み指数とする。
【００１５】
▲７▼吸水性は、ＪＩＳＬ−１０９２の撥水試験に準拠した装置を使用して測定する。図３はその装置の概略図であって、４５度に傾けて試験台９に載せた試験片１上に、高さ１５０ｍｍ位置から精製水２５０ｃｃを２５〜３０秒でスプレ−した後、表面に付着した余分な精製水を叩き落とした後の吸水重量を測定、得られた測定値をもって吸水性を表した。スプレ−ノズル１０の形状は図３ａに示すように前面は半径３２ｍｍの曲面であって、その中心部に径０．９ｍｍの孔を１つ、中心円１０ｍｍの位置に径０．９ｍｍの孔を６つ、中心円２１４ｍｍの位置に径０．９ｍｍの孔を１２設けてある。
▲８▼耐油性は、防水性の同様に４５度に傾けた試験台９に載せた試験片１上に、高さ１５０ｍｍ位置からエンジンオイル（１０Ｗ−４０）２５０ｃｃを約３０秒でノズル１１より滴下した後、表面に付着した余分なエンジンオイルをポリエチレン製へらにて軽くかき取った後の吸油重量を測定、その測定値をもって耐油性を表した。使用したノズルの形状は図３ｂに示すように全長５０ｍｍで径が９ｍｍの円筒状であって、ノズル先端部に行くにしたがってその径が絞られ、ノズルの直径は６ｍｍである。
▲９▼実用防水性は、外側に内径２３６ｍｍの半割アクリル製管と内側に外径２００ｍｍの半割アクリル製管の隙間で試験片１が１０％圧縮される様にセットした後、内側の管中央部に設けた直径１０ｍｍの穴に水圧１５ｃｍを５分間かけた後、水の浸透距離が２０ｍｍ以下、吸水性の吸水重量が０．５ｇ以下を満足することを良好と判定。
吸音性はＪＩＳＡ−１４０５の垂直入射法吸音率に準拠し、試験片から打ち抜いた厚さ２０ｍｍの１００ｍｍ丸形として吸音率を測定。
さらに、自己スキンが吸音率に及ぼす影響を比較するための試験片は、測定面の自己スキンをサンドペ−パ−で除去し測定。
【００１６】
【実施例】
以下、本発明を実施例及び比較例により具体的に説明するが本発明はこれら実施例のみに限定されるものではない。部及び％は重量基準とする。
各実施例で使用した原料を列記すると次の通りである。

本発明の防水性を有するポリウレタン発泡体の成形品において、ポリウレタン発泡体は、水との接触角が８５°以上、好ましくは９０°以上を有し、コア部１０ｍｍの通気度１０ｃｃ／ｃｍ^２／ｓｅｃ以下となるように配合し発泡硬化したものを使用するものである。
各配合例及び得られた成形品の物性を表１に示す。
【００１７】
【表１】

【００１８】
実施例１
前記表１の実施例１に記載した配合原料を使用する。他方、アルミ製モ−ルド（厚さ２０ｍｍ×２２０×２２０ｍｍ）にワックス系離型剤（中京油脂（株）製Ｂ−２６９）を塗布、１１０±４℃に加熱して剥離処理した後、４０〜４５℃に温調し、これに前記の配合原料の所定量を移し、該モ−ルド内で発泡硬化を行った。得られた発泡体の密度は０．１ｇ／ｃｍ^３であった。得られた自己スキン付きウレタン発泡体は、接触角９３°、自己スキンは厚さが２０μ、開口率４％、引張り弾性率が２８、かつ馴染み指数３ｍｍと極めて馴染み性の良いものであり、吸水性、耐油性ともに良好な値であった。
【００１９】
実施例２
実施例１と同様にして得たポリウレタン原料を、実施例１と同様の剥離処理を行ったモ−ルド内への充填率を高めて発泡硬化を行った。得られた発泡体の密度は０．２ｇ／ｃｍ^３であった。
得られた自己スキン付きウレタン発泡体は、吸水性、耐油性ともに良好な値であった。
実施例３
実施例１に石油樹脂を添加した以外は、実施例１と同様の処理を施したモ−ルドを使用し、これにポリウレタン原料を注入し、実施例１と同様に発泡硬化を行った。得られた発泡体の密度は０．１ｇ／ｃｍ^３であった。この自己スキン付き発泡体は、吸水性、耐油性ともに良好な値であった。
【００２０】
実施例４
実施例１の配合で、トリレンジイソシアナオ−トを併用した以外は、実施例１と同様に発泡硬化を行った。得られた発泡体の密度は、０．１ｇ／ｃｍ^３であった。この自己スキン付き発泡体は、吸水性、耐油性ともに良好な値であった。
次に本発明の要件を具備しない場合を比較例として示す。比較例の配合例及びそれぞれの物性を表２に示す。
【００２１】
【表２】

【００２２】
比較例１
市販の発泡ポリウレタンシ−リング材として、スラブ状発泡体で自己スキンの無いス−パ−シ−ルＷＢ（日本発条（株）社製）を使用した。この発泡体は、自己スキンが無いため、吸水性、耐油性が劣る結果であった。
比較例２
比較例１の発泡体を厚さ１０ｍｍにスライスしたサンプル上に厚さ５０μのポリウレタンフィルム、シリコ−ン処理したＰＥＴフィルムを順に乗せ、温度１８０〜２００℃、圧力５０ｋｇ／ｃｍ^２、圧縮率５０％で３〜５秒間熱プレスして積層体を作製した。フィルム付き発泡体は、フィルム面に限り吸水性、耐油性があるものの、他の面は発泡体コア部となり、これら面では、比較例１同様に吸水性、耐油性が劣る結果であった。さらにフィルム面は、引張り弾性率が６０、かつ馴染み指数１０ｍｍと極めて馴染み性が悪いため、実用防水性が劣る結果であった。
【００２３】
比較例３
実施例２と同様のポリウレタン原料を使用し、アルミ製モ−ルドを３０〜３５℃に温調を下げた以外は実施例２と同様の条件で発泡した。得られた発泡体の密度は０．２ｇ／ｃｍ^３であった。得られた自己スキン付き発泡体は、接触角９３°、自己スキンは厚さが６０μ、開口率１％であり、引張り弾性率が６０、かつ馴染み指数１０ｍｍと極めて馴染性が悪く、吸水性、耐油性は良いものの実用防水性が劣る結果であった。
【００２４】
比較例４
ポリオ−ル成分としてポリエ−テルポリオ−ルに占めるエチレンオキサイドを２６．５モル％に高めたほかは、実施例１と同様のポリウレタン原料を使用し、同様の処理を施したモ−ルドを使用して同様の条件で発泡した。得られた発泡体の密度は０．１ｇ／ｃｍ^３であった。得られた自己スキン付き発泡体は接触角７４°、自己スキンは厚さが２０μ、開口率３％であり、引張り弾性率が２６、かつ馴染み指数４ｍｍと馴染性が良いにも関わらず、発泡体の疎水性が著しく低下することで吸水性が劣る結果であった。
【００２５】
比較例５
実施例１と同様のポリウレタン原料を使用した。アルミ製モ−ルドにはワックス系離型剤としてコニシ（株）製ＵＲＨ−５１３を用い実施例１と同様の剥離処理を施した。このモ−ルド内に上記のポリウレタン原料を注入し、実施例１と同様の発泡条件で発泡した。得られた発泡体の密度は０．１ｇ／ｃｍ^３であった。得られた自己スキン付き発泡体は、接触角９３°、自己スキンは厚さが２５μ、開口率２０％であり、引張り弾性率が２８、かつ馴染み指数が５ｍｍと馴染み性は良いが吸水性、耐油性が劣る結果であった。
【００２６】
実施例１及び比較例３で得られたウレタン発泡体について吸音試験を行いその結果を図４に示した。図４において実施例１で得られた自己スキン付きウレタン発泡体は、自己スキンの厚さ２０μと薄いため、開口率２％と低いにも関わらず、良好な吸音性を有することが判った。
比較例３で得られた自己スキン付きウレタン発泡体は、自己スキンの厚さ６０μと厚く、吸音性が劣る結果であった。
なお、参考のため、実施例１でえられた自己スキン付きウレタン発泡体の吸音率測定面の自己スキンをサンドペ−パ−にて除去し、スキン無しとしたウレタン発泡体の吸音率を併記した。
【００２７】
【発明の効果】
以上述べた様に本発明によると、防水性を有するポリウレタン発泡体をモ−ルド成形にて、立体的な複雑形状をした防水面との馴染み性及び密着性に優れる自己スキンを全面に形成させてなる耐油性と防水性を兼ね備えた高防水性ポリウレタンモ−ルド成形品が容易に得られる。これらは、優れた耐油性と防水性を有するので、自動車、電車等の輸送車両や建設機械等のような振動を伴う防水シ−ル部位の防水シ−ル材として有用である。
さらに本発明のポリウレタン発泡体は、自己スキンが薄くかつ柔軟であるためにスキンを有していても吸音性に優れる。また、振動面に対し密着性が良いために制振効果が大きいなどの防音材として優れた性能を発揮する。
【図面の簡単な説明】
【図１】自己スキンの厚さ測定法の説明図
【図２】馴染み指数を測定するに使用する装置の斜視図
【図３】吸水性及び吸油性を測定するための装置の説明図で（ａ）は吸水性を測定する際に使用するノズルの形状図、（ｂ）は吸油性を測定する際に使用するノズルの形状図
【図４】実施例１及び比較例３の吸音率の測定結果図
【符号の説明】
１試験片２，３リブ４中心線
５自己スキンの厚さ６試験片保持台７鋼球
８ガラス板９試験台１０スプレ−ノズル
１１耐油性用ノズル[0001]
[Industrial applications]
The present invention always involves vibrations, such as automobiles, transportation vehicles such as trains, construction machines, and the like, and has a waterproof property suitable as a sealing material or a soundproofing material in a portion requiring high waterproofness and oil resistance. It relates to a polyurethane molded article.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a polyurethane foam having waterproofness has been manufactured by a continuous method as a slab-shaped product or a product having a double-sided skin layer, and is used as a waterproof sealing material, a soundproofing material, and a vibrationproofing material for transportation of automobiles and trains. Widely used in vehicles, construction machinery, residential buildings, electrical equipment, etc.
[0003]
Since the slab-like product is manufactured by free-foaming by pouring the mixed polyurethane raw material on a belt conveyor, the slab-like product is obtained as a molded product without a skin layer, and is formed into a desired shape. Even when cutting, laminating, and heat compression molding, the entire surface becomes a foam core portion, and no skin layer is formed on the surface.
In addition, a foam molded product obtained by applying a polyurethane material mixed between two belts and foaming the foamed polyurethane by regulating the height direction with an upper belt has upper and lower skin layers formed thereon. However, when the product was cut out into a desired shape from this, the cut-out cross section did not have a skin layer and became a foam core without a self-skin.
[0004]
However, when a self-skin layer is provided on a molded article made of a polyurethane foam, the oil absorption (oil resistance) and water absorption (water absorption) of the polyurethane foam are reduced, and the polyurethane foam acts as a protective coating layer. When a sealing material is formed from a foam, its adhesion to a waterproof surface is improved, and it is particularly suitable as a sealing material for transportation vehicles such as automobiles and construction machines with vibration. In addition, since the adhesiveness is improved, an effect of preventing vibration and an effect of preventing sound from leaking from a gap are exhibited, which is suitable as a soundproofing material. Therefore, it has been desired to provide a self-skin layer on a molded article made of a conventional polyurethane foam.
It is conceivable to form a skin layer on a conventional polyurethane foam.For example, when a film or the like is pasted on the surface of a conventional slab-like product and integrally molded, the film layer itself and a joint between the film layer and the foam are formed. If it becomes hard, the conformability with the waterproof surface and the adhesion with the waterproof surface are inferior, if the conformability and adhesion are inferior, gaps will occur in the parts to be sealed, and defects such as poor waterproofness will occur, Sufficient effects could not be demonstrated. In addition, since cutting is performed to manufacture a sealing material of a desired shape from a slab-shaped product, a skin layer is not provided on the entire surface of the foam, and it is difficult to reproduce a three-dimensional complicated shape, so manufacturing is difficult. There are drawbacks such as complicated processes.
[0005]
Also, even if the sealing material is thermocompression molded from a foam having a double-sided skin layer, not only the self-skin is not obtained on the entire surface of the foam, but also the foam is thermally degraded when thermocompression molded, There are drawbacks that the waterproofness is reduced, the opening ratio of the self-skin is increased, and the oil resistance and the waterproofness are reduced. In particular, even if you try to mold a three-dimensional complicated shape, it can not be reproduced, so if the adhesion to the waterproof surface is poor, if the adhesion or familiarity is poor, gaps will occur and water will leak, and as a result, the foam itself will The waterproof property which it has cannot be fully exhibited. Further, a foam formed by thermocompression molding from a foam having a double-sided skin layer does not have a self-skin in consideration of oil resistance and waterproofness.
By the way, in recent years, it has been desired to cope with a waterproof surface having a complicated three-dimensional shape. For example, in a joint between a door mirror and a body, a joint between a tail lamp and a body, or a waterproof and soundproofing material in an engine room or the like, a sealing material with improved waterproofness is required. became. Various oils such as engine oil may temporarily come into contact with these sealing materials, and when a new car is delivered, the coating protectant is replaced with a wax rimbar made of kerosene and a surfactant. To wash the car, oil resistance as well as waterproofness was required.
[0006]
[Problems to be solved by the invention]
The present inventor has sought to improve the above-mentioned drawbacks and conduct various studies on sealing materials and soundproofing materials that satisfy these requirements. As a result, the polyurethane foam was molded and given specific properties. It has been found that a molded product having a self-skin layer over the entire surface is a waterproof molded polyurethane molded product having improved oil resistance and waterproofness by improving the disadvantages of the prior art, and completed the present invention. SUMMARY OF THE INVENTION An object of the present invention is to provide a polyurethane mold molded article having a waterproof property with improved oil resistance and waterproof property and having a self-skin layer over the entire surface.
[0007]
[Means for Solving the Problems]
The gist of the present invention is that a polyisocyanate and a polyol have a self-skin layer obtained by foaming and curing in a mold in the presence of an auxiliary agent such as a catalyst and a foaming agent . A waterproof polyurethane molded product made of a polyurethane foam of ³ g / cm ³ , wherein the polyurethane molded product comprises:
(1) The contact angle with water is 85 ° or more. (2) The air permeability of the core portion having a thickness of 10 mm is 10 cc / cm ² / sec or less. (3) The self-skin has a thickness of 50 μm or less and an aperture ratio of 10% or less. The surface portion having the self-skin layer has a tensile modulus of elasticity of 50 g / mm ² or less;
A molded polyurethane mold having waterproofness, characterized in that:
[0008]
That is, in the present invention, the contact angle with water and the air permeability of the polyurethane foam are important factors for obtaining a waterproof polyurethane foam by molding, and the contact angle is 85. ° or more, and the waterproofness is improved by obtaining a polyurethane foam having a core portion having a thickness of 10 mm and a gas permeability of 10 cc / cm ² / sec or less (hereinafter, simply referred to as gas permeability).
Hereinafter, each characteristic of the present invention and a method for obtaining the characteristic will be described.
[0009]
(1) A substance substantially consisting of a hydrocarbon compound having a boiling point of 200 ° C. or higher and a melting point or a softening point of 150 ° C. or lower at ordinary temperature is added to the polyurethane raw material so as to have a specific air permeability or lower. However, since the present invention has mold formability (skin property), it is preferable that the addition amount is small in consideration of this point, and there is a case where no addition is made.
(2) As a silicone foam stabilizer required for bubble generation, a reactive silicone foam stabilizer having a group such as a hydroxyl group, an amino group, a carbonyl group or a mercapto group having a reactivity with urethane at the molecular terminal. It is preferred to use In the present invention, in consideration of mold formability (shrinkage), when a low-permeability foam can be obtained, a polydimethylsiloxane oil that works as a foam-reducing agent with a non-reactive silicone can be used.
[0010]
(3) As a polyol component as a main raw material, a polyether polyol, a polybutadiene polyol, a dimer acid ester polyol, or a castor oil polyol is used alone or as a mixture thereof. In the present invention, the use of a polyetherpolyol containing 5 mol% or more of ethylene oxide is preferred because of good mold formability. If the amount of ethylene oxide exceeds 20 mol%, the water absorption deteriorates, which is not preferable. When the amount of ethylene oxide exceeds 10 mol%, the water absorption tends to increase. In this case, it is preferable to use MDI or a combination of TDI and MDI for the isocyanate.
(4) When the air permeability of the foam is 10 cc / cm ² / sec or more, the water absorption increases. In the present invention, the air permeability is adjusted by adjusting the type of the polyol, the type and the amount of the auxiliary agent such as the catalyst and the foaming agent, the stirring conditions, the amount of dissolved air (the amount of air dissolved in the raw material), and the reaction temperature. And so on, so that these are adjusted to 10 cc / cm ² / sec or less.
[0011]
In the present invention, the self-skin layer of the foam is used to improve the high waterproofness and oil resistance in the mutual balance of the thickness of the self-skin, the opening ratio, and the tensile elasticity, and to make the self-skin layer conformable and adherent to the waterproof surface. It is an important factor for improving water resistance and exhibiting high waterproofness. The intended purpose can be achieved by setting the self-skin layer to a thickness of 50 μm or less, an opening ratio of 10% or less, preferably 0 % , and a tensile modulus of 50 g / mm ² or less.
(1) When the thickness of the self-skin is 50 μm or more, as the thickness increases, the self-skin becomes harder, the adaptability to the waterproof surface is impaired, and the waterproof performance of the polyurethane foam itself can be sufficiently exhibited. And water leakage is likely to occur. In addition, as the aperture ratio increases, oil resistance and waterproofness deteriorate. In the present invention, the thickness of the self-skin is adjusted by adjusting the amount of raw material injected into the mold (pack ratio), the molding temperature (mold temperature), the type and amount of the auxiliary agent such as a catalyst and a foaming agent, and the reaction temperature. Adjust by the following. The opening ratio is adjusted by the type and amount of the release agent used during the molding, the content of ethylene oxide in the polyol, the type and amount of the auxiliary agent, and the like.
[0012]
(2) If the tensile elastic modulus of the self-skin is 50 g / mm ² or more, the self-skin becomes too hard, the adaptability to the waterproof surface is impaired, and the waterproof performance of the polyurethane foam itself cannot be sufficiently exhibited. The familiarity index described later is 6 mm or more, which is not preferable.
In the present invention, the adjustment of the tensile modulus is adjusted because the thickness and thickness of the self-skin and the types and amounts of the polyol, isocyanate and other auxiliaries are changed.
By these preparations, when the thickness of the self-skin satisfies 50 μm or less, the opening ratio is 10% or less, the tensile modulus is 50 g / mm ² or less, and the familiarity index is 6 mm or less, the oil resistance and waterproofness are improved. You do it.
[0013]
Next, a method for measuring each characteristic of the present invention will be described.
For the measurement of each characteristic, a molded molded product having a thickness of 20 mm x 220 mm x 220 m was used as a test piece.
(1) The density is measured as a test piece in accordance with JIS K-6401.
{Circle around (2)} The air permeability conforms to JISL-1004 and is measured by Toyo Seiki Co., Ltd. Using 869, the self-skin of the test piece was measured as a 10 mm thick foam core portion from which each 5 mm of the upper and lower surfaces were removed.
[0014]
(3) The contact angle with water was determined by taking a 10 mm x 50 mm x 50 mm sample from the foam core from which the upper and lower surfaces of the self-skin of the test piece had been removed by 5 mm each, sandwiched between aluminum foils, at a temperature of 180 to 200 ° C and pressure. The film was hot-pressed at 50 to 60 kg / cm ² to form a film with a smooth surface, and measured using a Kyowa contact angle meter CA-A manufactured by Kyowa Science Co., Ltd.
(4) The thickness of the self-skin and the surface aperture ratio are measured by taking a photograph with a scanning electron microscope. Regarding the measurement of the thickness of the self-skin, the central part of the molded product of sample 1 was cut in the length direction, and five enlarged photographs of the cross-section of the self-skin with a pitch of 50 mm based on the position of 10 mm from the end. An image is taken, and the thickness 5 of the self-skin in contact with the center line 4 of the ribs 2 and 3 adjacent to each other is measured to determine the average thickness at five points. FIG. 1 is a schematic diagram of a scanning electron micrograph , showing the measurement method. The aperture ratio of the self-skin is obtained by taking five enlarged photographs of the self-skin portion at a pitch of 50 mm based on the position of 10 mm from the end in the longitudinal direction at the center of the molded product, and opening portions of each 1 mm square. Are measured, and the average aperture ratio at five points is determined.
(5) The tensile elastic modulus of the self-skin is based on JIS K-7127, and after slicing the surface portion having a self-skin to a thickness of 2 mm, a dumbbell No. 1 punched test piece is a Tensilon universal testing machine manufactured by Orientec. The load per unit area at the first linear portion of the tensile stress-strain curve when elongating 5% at a tensile speed of 50 mm / min was measured using UCT500.
In addition, the tensile modulus is obtained by the following equation.
Tensile modulus Em = Δδ / Δε
Δδ = difference in stress due to the original average cross-sectional area between two points on the straight line (g / mm ² )
Δε = difference in strain between the same two points
(6) As shown in FIG. 2, the familiarity index was obtained by placing a test piece 1 on a test piece holding table 6 made of an iron plate, placing a steel ball 7 having a diameter of 2 mm on the surface of the test piece 1, and then measuring 50 mm × A glass plate 8 having a thickness of 50 mm and a thickness of 1 mm is placed on the surface of the test piece 1. At this time, the diameter d of a space dent generated by compression-insertion of the steel ball 2 is measured after 5 seconds in millimeter units. Is the familiar index.
[0015]
{Circle around (7)} The water absorption is measured using an apparatus conforming to the water repellency test of JISL-1092. FIG. 3 is a schematic diagram of the apparatus, in which 250 cc of purified water is sprayed from a height of 150 mm on a test piece 1 placed on a test table 9 at an angle of 45 degrees for 25 to 30 seconds, and then the surface is sprayed. The weight of water absorption after the excess purified water that had adhered was knocked down was measured, and the obtained measured value was used to represent the water absorption. As shown in FIG. 3A, the spray nozzle 10 has a curved surface with a radius of 32 mm at the front surface, one hole with a diameter of 0.9 mm at the center, and a hole with a diameter of 0.9 mm at the position of a central circle 10 mm. Six holes, each having a diameter of 0.9 mm, are provided at a position of a center circle 214 mm.
{Circle around (8)} Oil resistance is measured by applying 250 cc of engine oil (10W-40) from the nozzle 11 to the test piece 1 placed on the test stand 9 inclined at 45 degrees from the nozzle 150 at a height of 150 mm in about 30 seconds. After dripping, excess engine oil adhering to the surface was lightly scraped off with a polyethylene spatula, and the oil absorption weight was measured. The measured value was used to express oil resistance. As shown in FIG. 3B, the shape of the nozzle used was a cylindrical shape having a total length of 50 mm and a diameter of 9 mm, and the diameter was narrowed toward the tip of the nozzle, and the diameter of the nozzle was 6 mm.
(9) The practical waterproof property is set such that the test piece 1 is compressed by 10% in a gap between a half acrylic pipe having an inner diameter of 236 mm on the outer side and a half acrylic pipe having an outer diameter of 200 mm on the inner side. After applying a water pressure of 15 cm to the hole having a diameter of 10 mm provided at the center of the pipe for 5 minutes, it was judged that the water permeation distance was 20 mm or less and the water absorption weight of water absorption was 0.5 g or less.
The sound absorption was measured as a 100 mm round shape with a thickness of 20 mm punched from a test piece in accordance with the sound absorption coefficient of the vertical incidence method of JISA-1405.
Further, the test piece for comparing the effect of the self-skin on the sound absorption coefficient was measured by removing the self-skin on the measurement surface with sandpaper.
[0016]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Parts and percentages are by weight.
The raw materials used in each example are listed below.

In the molded article of the waterproof polyurethane foam of the present invention, the polyurethane foam has a contact angle with water of 85 ° or more, preferably 90 ° or more, and has a core of 10 mm having an air permeability of 10 cc / cm ² /. What is blended so as to be less than sec and foam-cured is used.
Table 1 shows the composition examples and the physical properties of the obtained molded articles.
[0017]
[Table 1]

[0018]
Example 1
The blending raw materials described in Example 1 of Table 1 are used. On the other hand, a wax-based mold release agent (B-269 manufactured by Chukyo Yushi Co., Ltd.) was applied to an aluminum mold (thickness: 20 mm × 220 × 220 mm), and was heated to 110 ± 4 ° C. and peeled off. The temperature was adjusted to -45 ° C, a predetermined amount of the above-mentioned blended raw material was transferred, and foam hardening was performed in the mold. The density of the obtained foam was 0.1 g / cm ³ . The obtained self-skinned urethane foam has a contact angle of 93 °, a self-skin having a thickness of 20 μ, an aperture ratio of 4%, a tensile elasticity of 28, and a familiarity index of 3 mm. The properties and oil resistance were both good.
[0019]
Example 2
The polyurethane raw material obtained in the same manner as in Example 1 was foam-hardened by increasing the filling rate in the mold subjected to the same peeling treatment as in Example 1. The density of the obtained foam was 0.2 g / cm ³ .
The resulting self-skinned urethane foam had good values for both water absorption and oil resistance.
Example 3
A mold treated in the same manner as in Example 1 except that a petroleum resin was added to Example 1 was used. A polyurethane raw material was injected into the mold, and foaming and curing were performed in the same manner as in Example 1. The density of the obtained foam was 0.1 g / cm ³ . This self-skinned foam had good values for both water absorption and oil resistance.
[0020]
Example 4
Foaming and curing were carried out in the same manner as in Example 1 except that tolylene diisocyanate was used in combination in Example 1. The density of the obtained foam was 0.1 g / cm ³ . This self-skinned foam had good values for both water absorption and oil resistance.
Next, a case where the requirements of the present invention are not satisfied will be shown as a comparative example. Table 2 shows formulation examples of the comparative examples and respective physical properties.
[0021]
[Table 2]

[0022]
Comparative Example 1
As a commercially available foamed polyurethane sealing material, Superseal WB (manufactured by Nippon Hajime Co., Ltd.) having a slab-like foam and having no self-skin was used. This foam had no self-skin, resulting in poor water absorption and oil resistance.
Comparative Example 2
On a sample obtained by slicing the foam of Comparative Example 1 to a thickness of 10 mm, a polyurethane film having a thickness of 50 μm and a PET film having been subjected to silicone treatment are sequentially placed, and the temperature is 180 to 200 ° C., the pressure is 50 kg / cm ² , and the compression ratio is 50%. For 3 to 5 seconds to produce a laminate. Although the foam with a film has water absorption and oil resistance only on the film surface, the other surface becomes a foam core portion, and these surfaces have poor water absorption and oil resistance as in Comparative Example 1. Further, the film surface had a tensile elastic modulus of 60 and a familiarity index of 10 mm, which was extremely poor in conformability, resulting in poor practical waterproofness.
[0023]
Comparative Example 3
Using the same polyurethane raw material as in Example 2, foaming was performed under the same conditions as in Example 2 except that the temperature control of the aluminum mold was lowered to 30 to 35 ° C. The density of the obtained foam was 0.2 g / cm ³ . The obtained foam with self-skin has a contact angle of 93 °, a self-skin with a thickness of 60 μ, an aperture ratio of 1%, a tensile elasticity of 60, and a familiarity index of 10 mm. As a result, the oil resistance was good, but the practical waterproofness was poor.
[0024]
Comparative Example 4
Except that the ethylene oxide in the polyether polyol was increased to 26.5 mol% as the polyol component, the same polyurethane raw material as in Example 1 was used, and a mold treated in the same manner was used. And foamed under the same conditions. The density of the obtained foam was 0.1 g / cm ³ . The obtained foam with self-skin has a contact angle of 74 °, the self-skin has a thickness of 20 μ, an aperture ratio of 3%, a tensile elasticity of 26, and a foaming index of 4 mm. As a result, the water absorption was inferior because the body hydrophobicity was significantly reduced.
[0025]
Comparative Example 5
The same polyurethane raw material as in Example 1 was used. An aluminum mold was subjected to the same peeling treatment as in Example 1 using URH-513 manufactured by Konishi Co., Ltd. as a wax-based release agent. The above-mentioned polyurethane raw material was injected into the mold and foamed under the same foaming conditions as in Example 1. The density of the obtained foam was 0.1 g / cm ³ . The obtained foam with a self-skin has a contact angle of 93 °, a self-skin with a thickness of 25 μ, an aperture ratio of 20%, a tensile elasticity of 28, and a familiarity index of 5 mm. The result was poor oil resistance.
[0026]
A sound absorption test was performed on the urethane foams obtained in Example 1 and Comparative Example 3, and the results are shown in FIG. In FIG. 4, the urethane foam with a self-skin obtained in Example 1 was found to have good sound absorption despite the low aperture ratio of 2% because the self-skin was as thin as 20 μm.
The urethane foam with a self-skin obtained in Comparative Example 3 was thick with a self-skin thickness of 60 μm, resulting in poor sound absorption.
For reference, the sound absorption coefficient of the urethane foam without the skin was also shown by removing the self-skin on the sound absorption coefficient measurement surface of the urethane foam with the self-skin obtained in Example 1 using sandpaper. .
[0027]
【The invention's effect】
As described above, according to the present invention, a self-skin having excellent conformability and adhesion with a waterproof surface having a three-dimensional complicated shape is formed on the entire surface by molding a polyurethane foam having waterproofness. A highly waterproof polyurethane molded article having both oil resistance and waterproofness can be easily obtained. Since they have excellent oil resistance and waterproofness, they are useful as a waterproof seal material for a waterproof seal portion with vibration such as a transportation vehicle such as an automobile or a train or a construction machine.
Furthermore, the polyurethane foam of the present invention is excellent in sound absorption even if it has a skin because the self-skin is thin and flexible. In addition, it exhibits excellent performance as a soundproofing material such as a large vibration damping effect due to good adhesion to a vibration surface.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a method for measuring the thickness of a self-skin. FIG. 2 is a perspective view of an apparatus used for measuring a familiarity index. FIG. 3 is an explanatory view of an apparatus for measuring water absorbency and oil absorbency. a) is a shape diagram of a nozzle used when measuring water absorption, and (b) is a shape diagram of a nozzle used when measuring oil absorption. [FIG. 4] Measurement of sound absorption coefficient in Example 1 and Comparative Example 3 Result diagram [Explanation of symbols]
REFERENCE SIGNS LIST 1 test piece 2, 3 rib 4 center line 5 thickness of self-skin 6 test piece holding table 7 steel ball 8 glass plate 9 test table 10 spray nozzle 11 nozzle for oil resistance

Claims

Polyurethane having a density of 0.04 to 0.3 g / cm ³ having a self-skin layer obtained by subjecting a polyisocyanate and a polyol to foam curing in a mold in the presence of an auxiliary agent such as a catalyst and a foaming agent. A polyurethane molded article having waterproofness made of a foam, wherein the polyurethane molded article comprises:
(1) The contact angle with water is 85 ° or more. (2) The air permeability of the core portion having a thickness of 10 mm is 10 cc / cm ² / sec or less. (3) The self-skin has a thickness of 50 μm or less and an opening ratio of 10% or less. The tensile modulus of the surface portion of the self-skin layer having a thickness of 2 mm is 50 g / mm ² or less,
A molded polyurethane molded article having waterproofness, characterized in that: