JP4107032B2 - Solvent-free moisture-curable hot-melt urethane resin composition, foam, and sheet structure using the same - Google Patents

Description

【００２８】
（但し、一般式［１］中のＲ_１ は、水素原子又はアルキル基、アリール基若しくはアラルキル基より選ばれる一価の有機基を、Ｒ_２ は、ハロゲン原子又はアルコキシル基、アシロキシ基、フェノキシ基、イミノオキシ基若しくはアルケニルオキシ基を表し、また、ｎは０又は１若しくは２なる整数を表す。）
【００２９】
上記加水分解性シリル基の中でも、トリメトキシシリル基、トリエトキシシリル基、（メチル）ジメトキシシリル基、（メチル）ジエトキシシリル基などが架橋が進行し易い点から好ましい。
【００３０】
本発明で使用するイソシアネート基と反応し得る官能基と、加水分解性シリル基とを併有する化合物としては、例えば、γ−（２−アミノエチル）アミノプロピルトリメトキシシラン、γ−（２−ヒドロキシルエチル）アミノプロピルトリメトキシシラン、γ−（２−アミノエチル）アミノプロピルトリエトキシシラン、γ−（２−ヒドロキシルエチル）アミノプロピルトリエトキシシラン、γ−（２−アミノエチル）アミノプロピルメチルジメトキシシラン、γ−（２−アミノエチル）アミノプロピルメチルジエトキシシラン、γ−（２−ヒドロキシルエチル）アミノプロピルメチルジメトキシシラン、γ−（２−ヒドロキシルエチル）アミノプロピルメチルジエトキシシランまたはγ−（Ｎ，Ｎ−ジ−２−ヒドロキシルエチル）アミノプロピルトリエトキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−アミノプロピルメチルジメトキシシラン、γ−アミノプロピルメチルジエトキシシランまたはγ−（Ｎ−フェニル）アミノプロピルトリメトキシシラン等が挙げられる。
【００３１】
更に、本発明では、プレポリマー（Ａ）は、ポリオール成分を２種類以上併用してもよく、又、併用するポリオール成分、ポリイソシアネート成分の種類は特に限定するものではない。
【００３２】
また、プレポリマー（Ａ）の軟化点は、好ましくは３０〜１６０℃の範囲であり、より好ましくは４０〜１００℃の範囲である。プレポリマー（Ａ）の軟化点がかかる範囲であれば、ムラのない安定した均一な発泡体が得られ、また、水で発泡させた発泡セルの冷却固化時間の適切化が図れるため、好ましい。
【００３３】
本発明で使用するプレポリマー（Ａ）の軟化点の調整方法としては、特に制限はなく、例えば、▲１▼分子量による調整方法（ポリオール成分とポリイソシアネート成分とのモル比、高分子量ポリオールの使用、高分子ポリマーの使用等）、▲２▼ポリエステル系ポリオールのエチレン鎖の結晶性による調整方法、▲３▼ポリオール成分やポリイソシアネート成分の芳香族環の構造による調整方法、▲４▼ウレタン結合の量による調整方法等がある。
【００３４】
本発明で使用するプレポリマー（Ａ）を調製するには、公知慣用の種々の方法を用いればよく、特に限定はしない。
【００３５】
一般的には、イソシアネート基末端ウレタンプレポリマー（ａ−１）の場合は、原料イソシアネート成分に水分を除去したポリオール成分を滴下して加熱してポリオール成分の水酸基が無くなるまで反応して得られる。また、加水分解性アルコキシシリル基及びイソシアネート基を有するウレタンプレポリマー（ａ−２）の場合は、上記のようにして得られたイソシアネート基末端ウレタンプレポリマー（ａ−１）に、ＮＣＯ基と反応する基を有するアルコキシシラン化合物を滴下し、必要に応じて加熱して反応して得られる。この反応は無溶剤で行われるが場合によっては有機溶剤中で行い、その後脱溶剤することでも得られる。有機溶剤中で反応させる場合には、酢酸エチル、酢酸ｎ−ブチル、メチルエチルケトン、トルエン等の公知慣用の種々の有機溶剤の使用が可能であり、反応を阻害しない有機溶剤であれば特に限定しない。この場合、反応終了後、減圧加熱に代表される脱溶剤方法により溶剤を除去することが必要である。
【００３６】
次に、本発明で使用するポリイソシアネート成分（Ｂ）としては、例えば、フェニレンジイソシアネート、トリレンジイソシアネート（ＴＤＩ）、４，４’−ジフェニルメタンジイソシアネート、２，４−ジフェニルメタンジイソシアネート、ナフタレンジイソシアネート等の芳香族ジイソシアネートやヘキサメチレンジイソシアネート、リジンジイソシアネート、シクロヘキサンジイソシアネート、イソホロンジイソシアネート、ジシクロヘキシルメタンジイソシアネート、キシリレンジイソシアネート、テトラメチルキシリレンジイソシアネートなどの脂肪族あるいは脂環族ジイソシアネート等のポリイソシアネート成分のうち、１種或いは２種類以上の混合物が使用できる。これらの中で、溶融して使用するホットメルトウレタン樹脂組成物に用いられることを考慮した場合、加熱時の蒸気圧が低いポリイソシアネートを用いることが好ましく、かかるポリイソシアネートの中でもジフェニルメタンジイソシアネート（ＭＤＩ）を用いることが特に好ましい。
【００３７】
これらポリイソシアネート成分（Ｂ）の使用量は、プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）の総重量に対する総ＮＣＯ基含有率が、好ましくは２．０〜１０．０重量％の範囲であり、より好ましくは２．５〜８．０重量％の範囲である。ポリイソシアネート成分（Ｂ）の使用量がかかる範囲であれば、良好な発泡性及び架橋密度向上による耐久性（特に、耐熱性、耐加水分解性）が良好となる。
【００３８】
かかるポリイソシアネート成分（Ｂ）の添加方法としては、プレポリマー（Ａ）の合成のポリイソシアネート添加前にかかる範囲のポリイソシアネート成分（Ｂ）を先に添加すると、プレポリマー（Ａ）の分子量が大きくならないため、初期凝集力が発現せずに、発泡しても泡もち性が良好ではなく、好ましくない。そのため、プレポリマー（Ａ）と活性水素含有化合物（Ｂ）、水（Ｃ）及び／又はアミン系触媒（Ｄ）、整泡剤（Ｅ）と共に、加熱したシリンダー内に個々に供給して高速攪拌するか、プレポリマー（Ａ）の合成後に後添加して、プレポリマー（Ａ）と混合して供給することなどが好ましい。
【００３９】
本発明において、上記プレポリマー（Ａ）を使用するが、必要に応じて本来の湿気硬化性を損なわない範囲で使用時に活性水素を少なくとも２個有する化合物（Ｃ）を鎖伸長剤として使用することも出来る。
【００４０】
本発明で使用する活性水素を少なくとも２個有する化合物（Ｃ）としては、例えば、エチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，３−ブチレングリコール、１，４−ブチレングリコール、２，２−ジメチル−１，３−プロパンジオール、１，６−ヘキサンジオール、３−メチル−１，５−ペンタンジオール、１，８−オクタンジオール、ジエチレングリコール、トリエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、シクロヘキサン−１，４−ジメタノール、ビスフェノールＡのＥＯまたはＰＯ付加物などの１種または２種以上のジオール等のグリコール、グリセリン、トリメチロールエタン、トリメチロールプロパン、ペンタエリスリトール等の多価アルコール、或いは前記ポリエステル系ポリオールを開始剤とするエチレンオキサイド、プロピレンオキサイド、ブチレンオキサイド、スチレンオキサイドなどの単独或いは２種以上の開環重合物、前記ポリエーテル系ジオールのγ−ブチロラクトン、ε−カプロラクトンなどの開環付加重合物等が使用出来る。又、エチレンジアミン、１，３−プロピレンジアミン、１，２−プロピレンジアミン、ヘキサメチレンジアミン、ノルボルネンジアミン、ヒドラジン、ピペラジン、Ｎ，Ｎ’−ジアミノピペラジン、２−メチルピペラジン、４，４’−ジアミノジシクロヘキシルメタン、イソホロンジアミン、ジアミノベンゼン、ジフェニルメタンジアミン、メチレンビスジシクロアニリン、トリエチレンジアミン、テトラメチルヘキサメチレンジアミン、トリエチルアミン、トリプロピルアミン、トリメチルアミノエチルピペラジン、Ｎ−メチルモルフォリン、Ｎ−エチルモルフォリン、ジ（２，６−ジメチルモルフォリノエチル）エーテルなどのポリアミン、及び１種及び２種以上の混合物を使用できる。しかし、加工時のイソシアネート基との反応が緩やかであり架橋速度の制御が行い易い点から加工適性を考慮した場合に、グリコールが好ましい。加工性を損なわない範囲であれば、ウレタン樹脂の原料として使用される上記ポリアミンの単独使用や上記ポリオールとの併用は、特に制限されるものでない。
【００４１】
次に、本発明で使用する水（Ｄ）は、発泡剤として作用する必須成分である。プレポリマー（Ａ）と水（Ｄ）との反応により、炭酸ガスが発生して本発明の目的である発泡体が生成するが、水（Ｄ）の使用量は、炭酸ガスの発生過多による発泡体の厚みむらや面状態の不良発生、あるいはゲル化による加工性の低下等が起こらない範囲で選択されることが好ましい。
【００４２】
本発明で使用する水（Ｄ）は、プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）と活性水素を少なくとも２個有する化合物（Ｃ）を加熱溶融した状態で、混合攪拌して水で発泡させるための必須成分であり、場合によっては、アミン触媒（Ｅ）、整泡剤（Ｆ）を加えてもよい。プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）と活性水素を少なくとも２個有する化合物（Ｃ）のみの場合では、溶融粘度は上昇するが、水で発泡するのに必要な水が不足しており発泡しにくく、また、プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）と水（Ｄ）のみの場合では、発泡は若干するが、発泡した後の溶融粘度が急激に上昇しないため泡が潰れてしまい、泡の固定化が困難である。そのため、本発明では、プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）と活性水素を少なくとも２個有する化合物（Ｃ）と水（Ｄ）の組合せが、溶融粘度の上昇による泡の固定化と水による発泡性のバランスに優れており、場合によりアミン系触媒（Ｅ）、整泡剤（Ｆ）を加えることにより更に良好となる。
【００４３】
上記の活性水素を少なくとも２個有する化合物（Ｃ）及び水（Ｄ）の添加量は、プレポリマー（Ａ）及びポリイソシアネート成分（Ｂ）の総ＮＣＯ基が、活性水素を少なくとも２個有する化合物（Ｃ）及び水（Ｄ）と反応した後の、仕込総重量「（Ａ）＋（Ｂ）＋（Ｃ）＋（Ｄ）」に対する残存ＮＣＯ基含有率が、好ましくは１．５〜９．０重量％の範囲であればよく、より好ましくは２．０〜８．０重量％の範囲である。活性水素を少なくとも２個有する化合物（Ｃ）及び水（Ｄ）の添加量がかかる範囲であれば、良好な増粘効果が得られ、泡もち性が良好であり、また混合攪拌時にゲル化することもなく、好ましい。
【００４４】
また、本発明で使用する活性水素を少なくとも２個有する化合物（Ｃ）と水（Ｄ）の反応基当量の比［反応基当量（ｃ）／反応基当量（ｄ）］が０．５〜１０．０の範囲であり、より好ましくは１．０〜５．０の範囲である。
【００４５】
尚、水（Ｄ）の添加量は、上記プレポリマー（Ａ）及びポリイソシアネート成分（Ｂ）の総ＮＣＯ基が、活性水素を少なくとも２個有する化合物（Ｃ）及び水（Ｄ）と反応した後の残存ＮＣＯ基含有率が、１．５〜９．０重量％の範囲において、上記プレポリマー（Ａ）とポリイソシアネート成分（Ｂ）の総重量が１００重量部に対して、好ましくは０．０５〜５．０重量部、より好ましくは０．１〜２．０重量部とすることができる。水（Ｄ）の添加量がかかる範囲であれば、発泡度が適度となり発泡体の表面状態が良好となり、好ましい。
【００４６】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物には、上記プレポリマー（Ａ）、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、及び水（Ｄ）を必須成分とする他に、加熱溶融した状態で、ウレタン化触媒、整泡剤等を混合攪拌することが好ましく、それぞれの単独若しくは２種以上を添加することが出来る。
【００４７】
本発明で使用するウレタン化触媒としては、例えば、アミン系触媒、有機金属系触媒、アミジン系触媒などをあげることができ、好ましくはアミン系触媒（Ｅ）である。
【００４８】
本発明で使用するアミン系触媒（Ｅ）としては、触媒定数の比であるＫＷ_２／ＫＷ_１が、０．５以上のアミン系触媒であることが好ましい。尚、本発明において、ＫＷ_２は水とトリレンジイソシアネート（ＴＤＩ）との反応の重量当たりの触媒定数であり、ＫＷ_１はジエチレングリコール（ＤＥＧ）とトリレンジイソシアネート（ＴＤＩ）との反応の重量当たりの触媒定数を表すものとする。
【００４９】
かかるアミン系触媒（Ｅ）の触媒定数であるＫＷ_１及びＫＷ_２は、下記のポリウレタンの生成反応式（１）及び（２）の反応速度の測定により得られる定数である。
反応式（１） ＲＮＣＯ ＋Ｒ’ＯＨ→ＲＮＨＣ（＝Ｏ）ＯＯＲ’
反応式（２）２ＲＮＣＯ ＋Ｈ_２Ｏ→ＲＮＨＣ（＝Ｏ）ＮＨＲ＋ＣＯ_２
尚、反応速度の測定方法は、Ａ．Ｆａｒｋａｓの方法〔参考文献：Ｊ．Ａｍ．Ｃｈｅｍ．Ｓｏｃ．８２，６４２（１９６０）〕に従い、３０℃でのベンゼン溶液中で、水とＴＤＩの反応速度定数（Ｋ_２）と、ＤＥＧとＴＤＩの反応速度定数（Ｋ_１）を測定して、便宜上、重量当たりの触媒定数をそれぞれＫＷ_２及びＫＷ_１として表した。
【００５０】
本発明で使用するアミン系触媒（Ｅ）としては、例えば、Ｎ，Ｎ−ジメチルシクロヘキシルアミン（ＤＭＣＨＡ）、Ｎ−メチルジシクロヘキシルアミン（ＭＤＣＨＡ）、Ｎ，Ｎ，Ｎ'，Ｎ'−テトラメチルエチレンジアミン（ＴＭＥＤＡ）、Ｎ，Ｎ，Ｎ'，Ｎ'−テトラメチルプロピレンジアミン（ＴＭＰＤＡ）、Ｎ，Ｎ，Ｎ'，Ｎ'−テトラメチルヘキサメチレンジアミン（ＴＭＨＭＤＡ）、Ｎ，Ｎ，Ｎ'，Ｎ''，Ｎ''−ペンタメチルエチレンプロピレントリアミン（ＰＭＥＰＴＡ）、Ｎ，Ｎ，Ｎ'，Ｎ''，Ｎ''−ペンタメチルジプロピレンテトラアミン（ＰＭＤＰＴＡ）、Ｎ，Ｎ，Ｎ'，Ｎ''，Ｎ'''，Ｎ'''−ヘキサメチルジプロピレンエチレンテトラアミン（ＨＭＡＰＥＤＡ）、Ｎ、Ｎ‘−ジメチルピペラジン（ＤＭＰ）、Ｎ，Ｎ，Ｎ'−トリメチル−Ｎ−アミノエチルピレラジン（ＴＭＮＡＥＰ）、Ｎ−メチルモルフォリン（ＮＭＭＯ）、Ｎ−ヒドロキシエチルモルフォリン（ＨＥＭＯ）、Ｎ，Ｎ，Ｎ'，Ｎ'−テトラメチルジプロピレンエチレングリコールジアミン（ＴＭＥＧＤＡ）、Ｎ、Ｎ、Ｎ’、Ｎ''、Ｎ'''、Ｎ'''−ヘキサメチルテトラアミン（ＨＭＴＥＴＡ）、ジメチルアミノエチルエタノールエーテル（ＤＭＡＥＥ）、トリメチルアミノエチルエタノールアミン（ＴＭＡＥＥＡ）、ビスジメチルアミノエチルエーテル（ＢＤＭＥＥ）、トリエチルアミン（ＴＥＡ）、Ｎ，Ｎ，Ｎ'，Ｎ''，Ｎ''−ペンタメチルジエチレントリアミン（ＰＭＤＥＴＡ）等のアミン系触媒のうち、１種或いは２種類以上の混合物が使用できる。また、上記のアミン系触媒を必須成分とするなら、更に上記以外のウレタン化触媒或いは、有機金属系触媒、アミジン系触媒などを単独あるいは２種以上を併用してもよい。
【００５１】
かかるアミン系触媒（Ｅ）の使用量は、プレポリマー（Ａ）１００重量部に対して、好ましくは０．１〜１０重量部であり、より好ましくは０．５〜５重量部である。アミン系触媒（Ｅ）の使用量がかかる範囲であれば、良好な増粘効果が得られ、泡もち性が良好で、また、混合攪拌時にゲル化することもなく、好ましい。尚、必須成分であるアミン系触媒（Ｅ）と共に（Ｅ）以外の触媒を併用する場合は、アミン系触媒（Ｅ）と（Ｅ）以外の触媒との使用量合計は、プレポリマー（Ａ）１００重量部に対して、好ましくは０．１〜１０重量部であり、より好ましくは０．５〜５重量部である。
【００５２】
更に、本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物には、必要に応じて本来の湿気硬化性を損なわない範囲で使用時に整泡剤（Ｆ）を使用することも出来る。かかる整泡剤（Ｆ）としては、例えば、有機珪素系界面活性剤などに使用される従来公知のポリシロキサン−ポリオキシアルキレン共重合体を含むものが好ましく、ポリシロキサン−ポリオキシアルキレン共重合体を１０重量％以上含むものがより好ましく、具体的には、東レダウコーニング・シリコーン株式会社製の商品名ＳＦ２９６９、ＰＲＸ６０７、ＳＦ２９６４、ＳＲＸ２７４Ｃ、ＳＦ２９６１、ＳＦ２９６２、ＳＦ２９６５、ＳＦ２９０８、ＢＹ１０−１２３、ＳＦ２９０４、ＳＲＸ２９４Ａ、ＢＹ１０−１２４、ＳＦ２９３５Ｆ、ＳＦ２９４５Ｆ、ＳＦ２９４４Ｆ、ＳＦ２９３６Ｆ、ＳＨ１９３、ＳＨ１９２Ｈ、ＳＨ１９２、ＳＦ２９０９、ＳＨ１９４、ＳＨ１９０、ＳＲＸ２９０Ａ、ＳＲＸ２９８、及び日本ユニカー株式会社製の商品名Ｌ−５８０、ＳＺ１１２７、ＳＺ１１１１、ＳＺ１１３６、ＳＺ１９１９、ＳＺ１１０５、ＳＺ１１４２、ＳＺ１１６２、Ｌ３６０１、Ｌ５３０９、Ｌ５３６６、ＳＺ１３０６、ＳＺ１３１１、ＳＺ１３１３、ＳＺ１３４２、Ｌ５３４０、Ｌ５４２０、ＳＺ１６０５、ＳＺ１６２７、ＳＺ１６４２、ＳＺ１６４９、ＳＺ１６７１、ＳＺ１６７５、ＳＺ１９２３などが挙げられる。
【００５３】
これら整泡剤（Ｆ）の使用量は、プレポリマー（Ａ）１００重量部に対して、好ましくは０．１〜２０重量部の範囲であり、より好ましくは０．５〜１０重量部の範囲である。整泡剤の使用量がかかる範囲であれば、整泡力に優れ、熟成後の発泡体の物理的機械強度にも優れる。
【００５４】
また、整泡剤（Ｆ）に、必要に応じてフタル酸ビス（２−エチルヘキシル）（ＤＯＰ）、アジピン酸ジイソノニル（ＤＩＮＡ）、アジピン酸ビス（２−エチルヘキシル）（ＤＯＡ）等の可塑剤、ＥＯ／ＰＯ共重合体等のポリエーテル系界面活性剤などを添加してもよい。
【００５５】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物の架橋反応は、それぞれのプレポリマー中のイソシアネート基や加水分解性アルコキシシリル基が湿気と反応することにより起こる。
【００５６】
本発明の耐久性に優れた無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物は、架橋反応性（即ち、湿気硬化性）とホットメルト性（即ち、常温では固形でありながら加熱により溶融して塗布可能な状態となり、冷却により再度凝集力が出る状態となる性質を云う）を併せ持つ樹脂組成物を云う。
【００５７】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物の加工方法としては、例えば、プレポリマー（Ａ）を加熱して液状又は溶融状態とし、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、水（Ｄ）、及び／又はアミン系触媒（Ｅ）、整泡剤（Ｆ）と混合攪拌して、水で発泡させた後、ホットメルト性と湿気硬化性を利用して発泡状態を固定する方法が適している。また、発泡層のセルの形状を独泡状態から連通化状態まで制御する場合には、不活性気体を混合攪拌させることも可能である。
【００５８】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物は、プレポリマー（Ａ）、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、水（Ｄ）の混合時に必要に応じて、活性水素を含有する鎖伸長剤、アミン系触媒（Ｅ）、整泡剤（Ｆ）、シランカップリング剤、粘着付与剤、架橋触媒、チキソ付与剤、ワックス、可塑剤、安定剤、充填剤、顔料、蛍光増白剤等の添加剤、熱可塑性樹脂等が単独若しくは２種以上添加されてもよい。
【００５９】
本発明でいう発泡層とは、人工皮革や合成皮革を構成する複層構造のうちの皮革としての風合いを付加する重要な層をいう。発泡層を得る方法としては、▲１▼ＤＭＦ溶剤を用いた湿式法、▲２▼発泡剤を用いた方法、▲３▼イソシアネートと水との反応により発生する炭酸ガスを利用する方法、▲４▼強制的なガス混入による機械発泡による方法等が知られている。
【００６０】
本発明の発泡体は、プレポリマー（Ａ）、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、及び水（Ｄ）からなる無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で混合撹拌し、水で発泡した後、湿気硬化せしめて得られることを特徴とする。また、本発明の発泡体は、プレポリマー（Ａ）、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、及び水（Ｄ）の他に、アミン系触媒（Ｅ）、整泡剤（Ｆ）などを含有する無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で混合撹拌し、水で発泡した後、湿気硬化せしめて得られるものであってもよい。
【００６１】
また、本発明の発泡体は、前記無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱して液状又は溶融状態とし、必要に応じて予め不活性気体を混合して水で発泡させた後、ホットメルト性と湿気硬化性を利用して硬化させ、発泡状態を固定する方法が好ましい。不活性気体を混合した場合、水と不活性気体との熱膨張率の差が生じるため、混合比率により発泡セルの大きさが制御できるため有効である。
【００６２】
また、発泡層のセルの形状を独泡状態から連通化状態まで制御する場合には、不活性気体を混合撹拌させることも可能である。かかる不活性気体としては、例えば、窒素、希ガス、二酸化炭素、及びハロゲン化炭化水素等が挙げられる。
【００６３】
本発明の発泡体は、前述の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で混合撹拌して、必要に応じて予め不活性気体を混合撹拌して、水で発泡した後、湿気硬化させて得られる。
【００６４】
かかる発泡体における泡（本発明では、セルとも云う）は、通常ほとんどのものが独泡（独立した泡）の状態であるが、一部に連通した泡（セル）が混在してもよい。その大きさは、適宜制御可能であるが、直径５．０〜２００μｍ程度が好ましい。又、発泡体の厚さは、特に制限されないものの、特に合成皮革や人工皮革に使用される場合には、厚さ０．０５〜１．０ｍｍ程度が好適である。かかる泡の大きさ及び発泡体の厚さは、後述するシート構造体に於ける本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物から得られる発泡層にも適用される。
【００６５】
このようにして調製されるプレポリマー（Ａ）の数平均分子量は、特に限定はしないが、流動性や加工性などの面から、好ましくは５００〜５００,０００の範囲であり、より好ましくは１,０００〜１００,０００の範囲である。
【００６６】
プレポリマー（Ａ）を調製するに際して、必要ならば、ウレタン化触媒或いは安定剤等を使用することも出来る。これらの触媒や安定剤等は、斯かる反応の任意の段階で加えることが出来、特に制限はしない。
【００６７】
上記ウレタン化触媒としては、公知慣用の触媒が使用可能であり、例えば、酢酸カリウム、ステアリン酸亜鉛、又はオクチル酸錫などにより代表されるような種々の金属塩；あるいはジブチル錫ジラウレートなどにより代表されるような種々の有機金属化合物などが挙げられる。これらは単独使用でもよく、２種以上を併用してもよい。
【００６８】
また、上記安定剤としては、例えば、置換ベンゾトリアゾール類などのような紫外線に対する安定剤などであるし、更には置換フェノール誘導体などのような熱酸化に対する安定剤などが挙げられ、これらの各安定剤は、目的に応じて、適宜、選択して加えることが出来、単独使用でもよく、２種以上を併用してもよい。
【００６９】
また、加水分解性のアルコキシシリル基及びイソシアネート基を有するウレタンプレポリマー（ａ−２）の場合も、必要に応じて架橋触媒として、例えば、リンゴ酸、クエン酸等の各種の酸性化合物、水酸化リチウム、水酸化ナトリウム、水酸化カリウム、トリエチレンジアミン等の各種の塩基性化合物類、テトライソプロピルチタネート、ジ−ｎ−ブチル錫ジラウレート、ジ−ｎ−ブチル錫オキサイド、ジオクチル錫オキサイドまたはジ−ｎ−ブチル錫マレエート等の如き、各種の含金属化合物類等の一般的にアルコキシシリル基架橋触媒として用いられるものを添加して使用することが出来る。
【００７０】
上記シランカップリング剤としては、例えば、γ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジエトキシシラン、β−（３，４−エポキシシクロヘキシル）エチルトリメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、ビニルトリメトキシシラン、又はγ−クロロプロピルトリメトキシシラン等が挙げられる。
【００７１】
上記充填材としては、例えば、炭酸カルシウム、硫酸バリウム、カオリン、タルク、カーボンブラック、アルミナ、酸化マグネシウム、無機・有機バルーン等が挙げられる。
【００７２】
また、上記チキソ付与剤としては、例えば、表面処理炭酸カルシウム、微粉末シリカ、ベントナイト、セピオライト等が挙げられる。特に発泡後の泡の安定化の点よりチキソ付与剤の添加は好ましい。
【００７３】
本発明のシート構造体は、上記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で混合撹拌し、水で発泡した後、湿気硬化せしめた発泡体を積層してなることを特徴とする。
【００７４】
本発明のシート構造体は、上記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で、予め不活性気体を混合撹拌し、水で発泡した後、湿気硬化せしめた発泡層を積層してなるものであってもよい。
【００７５】
本発明のシート構造体は、上記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で混合撹拌し、水で発泡した後、湿気硬化せしめた発泡体を積層し、更に皮革様のフィルム層を積層してなることを特徴とする。
【００７６】
本発明のシート構造体は、上記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で、予め不活性気体を混合撹拌し、水で発泡した後、湿気硬化せしめた発泡層を積層し、更に皮革様のフィルム層を積層してなるものであってもよい。
【００７７】
本発明のシート構造体は、皮革様のフィルムと該フィルム上に前記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を、水で発泡した後、硬化せしめた発泡層を有するものであってもよい。
【００７８】
本発明のシート構造体は、皮革様のフィルムと該フィルム上に前記の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物に、予め不活性気体を混合して、水で発泡した後、硬化せしめた発泡層を有するものであってもよい。
【００７９】
本発明の発泡体の発泡度は、その用途に応じて適宜調整することが出来、風合い或いは強度を損なわない範囲であれば、特に制限はない。例えば、人工皮革用途又は合成皮革用途であれば、通常、発泡度は１．５〜３．０倍の範囲が好ましい。尚、ここで云う「発泡度」とは、発泡前の樹脂の体積（Ｖ_１）と発泡後の樹脂の体積（Ｖ_２）の比［Ｖ_２／Ｖ_１］で表される。
【００８０】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物とシート基材からシート構造体をもたらすことができる。即ち、シート基材上に前記樹脂組成物を加熱溶融状態で塗布し、水で発泡した後、湿気硬化させて発泡層を形成することによりシート構造体を得ることができる。勿論、該発泡層の上に更にシート基材を積層したシート構造体や、３枚以上のシート基材間に上記樹脂組成物による発泡層を一体化したシート構造体もできる。
【００８１】
本発明のシート構造体を構成するシート基材としては、例えば、不織布や織布、編布等の一般的に人工皮革や合成皮革に用いられている基布や天然皮革、各種プラスチックシート、フィルム、離型紙付きフィルム、離型紙、紙等であれば何ら限定されるものではない。また、前記基布に対して、溶剤系及び水系のポリウレタン樹脂、アクリル樹脂、ゴム系（ＳＢＲ、ＮＢＲなど）ラテックス等を少なくとも１種以上を含浸させた不織布や織布、編布等の一般的に人工皮革や合成皮革に用いられている基布や天然皮革等であれば何ら限定されるものではない。
【００８２】
本発明で使用するシート基材としてのフィルム及び離型紙付きフィルムは、従来、人工皮革用又は合成皮革用に用いられるポリウレタン樹脂が好ましく、通常溶剤系樹脂、水系樹脂、ホットメルト樹脂などを離型紙上に塗布乾燥して得ることが出来る。
【００８３】
本発明での発泡体及びシート構造体は、本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融した状態で、必要に応じて不活性気体を混合させて水で発泡させた発泡樹脂を、例えば離型紙間、又はシート基材と離型紙の間、又は基布と皮革様のフィルムの間、離型紙と撥水処理布及びフィルムとの間に、均一に積層し冷却固化させた後、架橋させて加工出来る方法であれば特に制限はない。また、かかる発泡体を調整後、シート基材又は／及び皮革様のフィルムと、溶剤系接着剤、水系接着剤、ホットメルト接着剤などを用いて接着加工してもよい。尚、該発泡体の発泡及び硬化を促進させるために、発泡体を貼り合わせた基材の基材表面又は発泡体表面、発泡体を一体化した構造体の基材表面又は発泡体表面に加湿処理を行ってもよい。
【００８４】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を発泡する設備は、必要に応じて不活性気体を所定量混合しながら均一混合可能な設備が望ましく、更に、不活性気体の混合時の攪拌で冷却増粘して均一な発泡が行われない場合や基材やフィルムに発泡層として加工した場合に流動せずに塗布不良や接着不良が起こることを避けるために混合物を加熱保温出来る構造が望ましい。
【００８５】
本発明での発泡体及びシート構造体を製造する際に、本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物を加熱溶融し、水で発泡させるが、その際の加熱温度は、プレポリマー（Ａ）が溶融する温度以上であり、好ましくは６０〜２００℃の範囲である。加熱温度がかかる範囲であれば、該樹脂組成物の発泡の制御が容易であり、均質な発泡体が得られやすく、好ましい。
【００８６】
本発明での発泡体又はシート構造体を製造する装置としては、例えば、工業的にはプレポリマー（Ａ）を加熱溶融するタンクと水や他の添加剤などの貯蔵供給用タンク、各タンクからのそれぞれ材料を混合する槽、離型紙やシート基材を連続的に搬送するベルト、該ベルト上に溶融した樹脂組成物を供給するノズル、発泡体を硬化するための加湿室、必要により加熱室、他のシート基材供給部などからなるものである。上述の装置は、代表的なものであり、種々変更した他のものでも差し支えない。
【００８７】
尚、不活性気体を併用して本発明の樹脂組成物を発泡する場合の設備については、不活性気体を所定量混合しながら均一混合可能な設備であれば特に制限はないが、不活性気体の混合時の撹拌で冷却増粘して均一な発泡が行われない場合や基材及びフィルム、シートに発泡体として加工した場合に流動せずに塗布不良や接着不良が起こることを避けるために混合物を加熱保温出来る構造が望ましい。
【００８８】
本発明で得られる発泡体又はシート構造体への公知慣用のラミネート又はコーティング等による表面加工、或いはバフィング加工等の諸々の加工方法については何ら限定されるものではない。
【００８９】
以上のように、本発明により、特に接着性と発泡性、耐久性（特に、耐加水分解性、耐熱性）に優れる無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物と、該ウレタン樹脂組成物を用いて得られる発泡体、それを用いたシート構造体、及び該シート構造体の製造方法を提供出来る。
【００９０】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物、及びそれを用いた発泡体、シート構成体は、例えば、靴、家具、衣料、自動車などの車両、鞄、ケース等に用いる合成皮革や人工皮革以外にも、接着剤、粘着剤、シーリング剤、塗料、コーティング剤、フィルム、シート、断熱材、保温材、吸音材、クッション材、滑り止め、研磨パッド、電子電器材料、建材、土木、医療部材等々の幅広い用途において、極めて実用性が高い。
【００９１】
【実施例】
以下に、本発明を実施例により具体的に説明するが、本発明は、これらの実施例のみに限定されるものではない。尚、以下において、部及び％は、特にことわりのない限り、全て重量基準であるものとする。又、各種特性は以下の方法に従い測定した。
【００９２】
［表皮フィルム１の作製方法］
合成皮革表皮用の溶剤型ウレタン樹脂であるクリスボンＮＹ３２４（大日本インキ化学工業株式会社製）に、顔料のＤＩＬＡＣ−６００１（大日本インキ化学工業株式会社製）とメチルエチルケトン（ＭＥＫ）とジメチルホルムアミド（ＤＭＦ）とを混合撹拌してナイフコーターを用いて、離型紙上に塗布量が１００ｇ／ｍ^２（ｗｅｔ）になるように均一に塗布した後、７０℃で１分間乾燥後、次いで１２０℃で２分間乾燥させて、厚さ３０μｍの表皮フィルム１を作製した。
【００９３】
［軟化点の測定方法］
実施例及び比較例で得た各プレポリマーの軟化点を示差熱測定装置（ＤＳＣ、マックサイエンス社製）を用いて、窒素雰囲気下、昇温速度５℃／分にて測定した。
【００９４】
［接着性の測定方法］
温度２３℃、相対湿度６５％の環境下で５日間放置した表皮フィルム付きシート構造体の表皮フィルム１に布ホットメルトテープを１３０℃で５秒間熱圧着した後、２００ｍｍ／分のヘッドスピードにてＪＩＳ Ｋ６３１１に準じて、テンシロンを用いて剥離強度を測定し、接着性の評価を行った。
【００９５】
［耐加水分解性の測定方法］
表皮フィルム付きシート構造体を耐加水分解試験（ジャングル試験条件：７０℃、相対湿度９５％、１２週間保持）に供した後、上記の接着性の評価方法と同様に剥離強度を測定して、保持率と、評価後の外観変化を観察し、下記の判定基準に従い評価した。
○：ジャングル試験後の外観変化無し。
×：ジャングル試験後の外観変化有り。
【００９６】
［耐熱性の測定方法］
表皮フィルム付きシート構造体を耐熱試験（試験条件：１２０℃、５００時間保持）に供した後、上記の接着性の評価方法と同様に剥離強度を測定して、保持率と、評価後の外観変化を観察し、下記の判定基準に従い評価した。
○：試験後の外観変化無し。
×：試験後の外観変化有り。
【００９７】
《実施例１》表皮フィルム付きシート構造体１の製造方法
１リットル４ツ口フラスコに数平均分子量が１４００なるポリテトラメチレングリコール（以下、ＰＴＭＧ１４００と略称）の７０部と、アジピン酸（表中ではＡＡと略称）とヘキサンジオール（表中ではＨＧと略称）との数平均分子量が２０００のポリエステルポリオール（表中ではポリエステルポリオール２０００と記載）の３０部を１２０℃に減圧加熱して、水分０．０５％となるまで脱水した。４０℃に冷却後、４，４’−ジフェニルメタンジイソシアネート（ＭＤＩ）を、表１中に示したＮＣＯ含有率（重量％）（以下、ＮＣＯ％と略記）になるように加えた後、９０℃まで昇温して、ＮＣＯ％が一定となるまで３時間反応してプレポリマー１を得た。コーンプレート粘度計での１２５℃の粘度は７０００ｍＰａ・ｓであった。得られたプレポリマー１を１２０℃に加熱して溶融して１２０℃で加温しながら、プレポリマー１の１００部に対して、ＭＤＩを表１に示した総ＮＣＯ基含有率（重量％）になるように、エチレングリコール（ＥＧ）を１．０部、ＰＯＬＹＣＡＴ−８［エアープロダクツジャパン社製；Ｎ，Ｎ−ジメチルシクロヘキシルアミン（ＤＭＣＨＡ）、触媒定数の比；ＫＷ_２／ＫＷ_１＝３．７３］を０．１０部、及び水を０．１２部と共に加えてミキシングして、約２．８倍に発泡したことを体積から確認した。直ちに、表皮フィルム１の上に厚み５０μｍで塗布して、ポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置して、シート状の表面フィルム付き構造体１を得た。本発明のシート状の表皮フィルム付き構造体１の特性評価結果を表１に示したが、発泡性、接着性、耐熱性、及び耐加水分解性に優れていた。
【００９８】
《実施例２》表面フィルム付きシート構造体２の製造方法
１リットル４ツ口フラスコに実施例１で得られたプレポリマー１を１２０℃に加熱して溶融して１２０℃で加温しながら、プレポリマー１の１００部に対して、ＭＤＩを表１に示した総ＮＣＯ基含有率になるように、ＥＧを１．０部、ＰＯＬＹＣＡＴ−８を０．１０部、及び水を０．１２部と共に加えてミキシングして、約３．０倍に発泡したことを体積から確認した。直ちに、表皮フィルム１の上に厚み５０μｍで塗布してポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置し、シート状の表皮フィルム付きシート構造体２を得た。本発明のシート状の表皮フィルム付きシート構造体２の特性評価結果を表１に示したが、発泡性、接着性、耐熱性、及び耐加水分解性に優れていた。
【００９９】
《実施例３》表面フィルム付きシート構造体３の製造方法
１リットル４ツ口フラスコにＰＴＭＧ１４００の７０部と、ポリエステルポリオール２０００の３０部を１２０℃に減圧加熱して、水分０．０５％となるまで脱水した。４０℃に冷却後、４，４’−ジフェニルメタンジイソシアネート（ＭＤＩ）を、表１中に示したＮＣＯ含有率（重量％）になるように加えた後、９０℃まで昇温して、ＮＣＯ％が一定となるまで３時間反応してプレポリマー２を得た。コーンプレート粘度計での１２５℃の粘度は９０００ｍＰａ・ｓであった。得られたプレポリマー２を１２０℃に加熱して溶融して１２０℃で加温しながら、プレポリマー２の１００部に対して、ＭＤＩを表１に示した総ＮＣＯ基含有率になるように、ＥＧを０．１６部、ＰＯＬＹＣＡＴ−８を０．１０部、及び水を０．１０部と共に加えてミキシングして、約２．５倍に発泡したことを体積から確認した。直ちに、表皮フィルム１の上に厚み５０μｍで塗布して、ポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置して、シート状の表面フィルム付き構造体３を得た。本発明のシート状の表皮フィルム付き構造体３の特性評価結果を表１に示したが、発泡性、接着性、耐熱性、及び耐加水分解性に優れていた。
【０１００】
《実施例４》表面フィルム付きシート構造体４の製造方法
実施例１で得られたプレポリマー１を、１２０℃に加熱溶融した後、１２０℃に加熱した数平均分子量が１０００のプロピレングリコール（以下、ＰＰＧ１０００と記載）と、ＭＤＩを表１に示した総ＮＣＯ基含有率になるように、ジブチルジ錫ジラウレート（ＤＢＳＮＤＬ）を、（プレポリマー１＋ＭＤＩ）／ＰＰＧ１０００／ＤＢＳＮＤＬ＝１００／３．０／０．１重量比で混合しながら、ＥＧを１．０部、ＰＯＬＹＣＡＴ−８を０．１０部、及び水０．１２部を共に加えてミキシングして、約２．８倍に発泡したことを体積から確認した。発泡プレポリマー３を得た。直ちに、表皮フィルム１の上に厚み５０μｍで塗布して、ポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置して、シート状の表皮フィルム付きシート構造体４を得た。本発明のシート状の表面フィルム付きシート構造体４の特性評価結果を表１に示したが、発泡青、接着性、耐熱性、及び耐加水分解性に優れていた。
【０１０１】
《比較例１》
１リットル４ツ口フラスコに実施例１で得られたプレポリマー１を１２０℃に加熱して溶融して１２０℃で加温しながら、プレポリマー１の１００部に対して、ＥＧを１．３０部、ＰＯＬＹＣＡＴ−８を０．１０部、及び水０．１５部を加えてミキシングして、約１．０倍に発泡したことを体積から確認した。直ちに、表皮フィルム１の上に厚み５０μｍで塗布してポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置して、シート状の表面フィルム付きシート構造体５を得た。その特性評価結果を表２に示す。本品は、発泡性及び耐熱性に劣るものであった。
【０１０２】
《比較例２》
１リットル４ツ口フラスコに実施例３で得られたプレポリマー２を１２０℃に加熱して溶融して１２０℃で加温しながら、プレポリマー２の１００部のみをミキシングしたが、約１．０倍と殆ど発泡しなかったことを体積から確認した。直ちに、表皮フィルム１の上に厚み５０μｍで塗布してポリウレタン含浸不織布と貼り合せて冷却して、温度２３℃、相対湿度６５％の環境下で５日間放置して、シート状の表面フィルム付きシート構造体６を得た。その特性評価結果を表２に示した。本品は、発泡性及び耐熱性に劣るものであった。
【０１０３】
【表１】

【０１０４】
【表２】

【０１０５】
【発明の効果】
本発明の無溶剤型湿気硬化性ホットメルトウレタン樹脂組成物は、イソシアネート基含有ホットメルトウレタンプレポリマー（Ａ）、ポリイソシアネート成分（Ｂ）、活性水素を少なくとも２個有する化合物（Ｃ）、及び水（Ｄ）からなる樹脂組成物であり、発泡性、接着性及び耐久性（特に、耐熱性、耐加水分解性）に優れる。本発明の樹脂組成物を加熱溶融した状態で混合撹拌し、水で発泡した後、湿気硬化させることにより発泡体を得ることができ、及びそれを用いたシート構造体は、例えば、靴、家具、衣料、自動車などの車両、鞄、ケース等に用いる合成皮革や人工皮革以外にも、接着剤、粘着剤、シーリング剤、塗料、コーティング剤、フィルム、シート、断熱材、保温材、吸音材、クッション材、滑り止め、研磨パッド、電子電器材料、建材、土木、医療部材等々の幅広い用途において、極めて実用性が高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel and useful solvent-free moisture-curable hot melt urethane resin composition, a foam, a sheet structure using the same, and a method for producing the sheet structure.
[0002]
[Prior art]
Conventionally, polyurethane resins have been widely used for artificial leather and synthetic leather. Artificial leather or synthetic leather, in a broad sense, refers to a sheet-like material that is a combination of a polyurethane resin composition and a nonwoven fabric, woven fabric, knitted fabric, etc., but is generally classified as follows: Has been.
[0003]
In other words, “artificial leather” refers to a sheet-like product in which a polyurethane resin composition is filled or laminated into a nonwoven fabric, and the production method thereof is generally dimethylformamide (hereinafter also referred to as DMF) of the polyurethane resin composition. The solution is impregnated into a non-woven fabric or coated, and the polyurethane resin is coagulated in a coagulation bath comprising a water coagulation bath or a mixed solution of DMF-water to form a porous material, followed by washing and drying. It is obtained by a method of passing through a process, so-called wet processing method.
[0004]
The other “synthetic leather” is generally classified into dry synthetic leather and wet synthetic leather, and refers to a sheet-like product in which a polyurethane resin composition is laminated on a woven fabric or a knitted fabric. In general, a dry synthetic leather is produced by impregnating a woven fabric or knitted fabric with a DMF solution of a polyurethane resin composition, or coating it with a water coagulation bath or a DMF-water mixed solution. Among them, a polyurethane resin is solidified to form a porous material, and then a washing process and a drying process are performed, that is, a so-called wet processing method. The dry synthetic leather is made by mixing and agitating polyurethane resin, pigment, solvent, and additives to prepare a coating resin solution for the skin, and then applying it onto the molded release paper and drying the solvent. The two-component polyurethane resin adhesive is applied to the release paper, laminated with a base fabric such as a raised cloth, dried after drying the solvent, and various skins are formed without forming a porous layer. A method for producing a multilayer processed body for leather by laminating a decorative film on a base fabric.
[0005]
Because these processing methods use solvent-type urethane resin, drying of the solvent and extraction of the solvent are indispensable in the middle of the processing process, which causes adverse effects on the human body, environmental pollution problems, and evaporation of the solvent. In recent years, there has been a growing demand for a shift from a solvent type to a solventless resin or a shift to a solventless processing method.
[0006]
As a solvent-free method, water-based methods have been studied, but practical use is limited due to poor water resistance and durability. In addition, the solvent-free liquid cross-linked resin depends on the cross-linking of the cohesive force, so that it is difficult to adjust the cohesive force at the time of processing such as coating and laminating, which makes it difficult to apply the synthetic leather.
[0007]
In addition, a “solvent-free, moisture-curable (reactive) hot-melt urethane resin composition” that is used in an adhesive or a coating material by heating and melting a solid reactive resin at room temperature is well known. Conventionally, as an example of foaming a reactive hot melt urethane resin composition, a method of introducing an inert gas under pressure into a reactive hot melt urethane resin composition in a molten state (Japanese Patent Laid-Open No. 3-6281, published in Europe) Patent No. 405,721) is disclosed, but if the composition is not pressurized and released to ambient pressure, the foam state is inhomogeneous and insufficient in terms of cell shape and mechanical strength. Has the disadvantages.
[0008]
Furthermore, in the reactive hot melt urethane resin composition, there has been a demand for the development of a composition having excellent properties such as foamability, adhesiveness, and durability (particularly hydrolysis resistance and heat resistance).
[0009]
[Problems to be solved by the invention]
The object of the present invention is a solventless, moisture-curable hot, which can provide a high-performance porous layer having excellent adhesion, foaming and durability (particularly hydrolysis resistance and heat resistance) based on a moisture curing reaction. A melt urethane resin composition, a foam, a sheet structure using the same, and a method for producing the sheet structure.
[0010]
[Means for Solving the Problems]
The present invention relates to an isocyanate group-containing hot melt urethane prepolymer (A), a polyisocyanate component (B), and a compound (C) having at least two active hydrogens.,Water (D)And N, N-dimethylcyclohexylamineAnd the total isocyanate (NCO) group content with respect to the total weight of the prepolymer (A) and the polyisocyanate component (B) is in the range of 2.0 to 10.0% by weight, andThe prepolymer (A) with respect to the charged total weight “(A) + (B) + (C) + (D)” after reacting with the compound (C) having at least two active hydrogens and water (D) And the residual NCO group content of the polyisocyanate component (B) is in the range of 1.5 to 9.0% by weight.The present invention provides a solventless moisture-curable hot-melt urethane resin composition.
[0011]
In addition, the present invention provides a foam characterized by being obtained by mixing and stirring the solventless moisture-curable hot melt urethane resin composition in a heated and melted state, foaming with water, and then curing with moisture. To do.
[0012]
Moreover, this invention provides the sheet | seat structure characterized by laminating | stacking the said foam on a sheet | seat base material.
[0013]
Moreover, this invention provides the sheet | seat structure characterized by laminating | stacking the said foam on a sheet | seat base material, and also laminating | stacking a leather-like film layer.
[0014]
In addition, the present invention provides a sheet structure in which the solvent-free moisture-curable hot-melt urethane resin composition is mixed and stirred in a heated and melted state on a sheet base material, laminated with foamed water, and then moisture-cured. A manufacturing method is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The matters necessary for carrying out the present invention are described below.
[0016]
In the present invention, a prepolymer (A), preferably an isocyanate group-terminated urethane prepolymer having a softening point in the range of 30 to 160 ° C., a prepolymer (A) containing an alkoxysilyl group-terminated urethane prepolymer, if necessary, a polyisocyanate component (B), the compound (C) having at least two active hydrogens and water (D), and the total isocyanate group content relative to the total weight of the prepolymer (A) and the polyisocyanate component (B) is 2. The solvent-free moisture-curable hot-melt urethane resin composition characterized by being in the range of 0 to 10.0% by weight is heated and melted, mixed and stirred and foamed with water, and then subjected to moisture curing reaction. In addition to excellent adhesion and durability (especially hydrolysis resistance and heat resistance), a uniform cell shape is obtained by forming a foam based on And high performance of solvent-free porous layer is obtained moisture-curable hot-melt urethane resin composition having both a foamable that the foam using the same, and the sheet structure is obtained.
[0017]
First, the prepolymer (A) which is the main component of the solventless moisture-curable hot melt urethane resin composition will be described.
[0018]
The prepolymer (A) used in the present invention is an isocyanate group-terminated urethane prepolymer (a-1) in which an isocyanate group obtained by reaction of a polyol component and an isocyanate component is left, or a polyol component and a polyisocyanate component. Urethane prepolymer having a hydrolyzable alkoxysilyl group and an isocyanate group, which has at least one active hydrogen atom that reacts with an isocyanate group per molecule and has reacted with a compound having a hydrolyzable silyl group (A-2), preferably an isocyanate group-terminated urethane prepolymer (a-1) or a urethane prepolymer (a-2) having a hydrolyzable alkoxysilyl group and an isocyanate group. It will be.
[0019]
In the isocyanate group-terminated urethane prepolymer (a-1), the polyol component and the polyisocyanate component have an equivalent ratio of the NCO group of the isocyanate to the hydroxyl group of the polyol (NCO group / equivalent ratio of hydroxyl group) exceeding 1, that is, the NCO group. Is obtained by reacting in excess. The equivalent ratio of NCO group / hydroxyl group is usually preferably in the range of 1.1 to 5.0, more preferably in the range of 1.5 to 3.0.
Further, the isocyanate group content in the urethane prepolymer (A) is usually preferably in the range of 1.5 to 8.0% by weight.
If the NCO group / hydroxyl group equivalent ratio and the isocyanate group content in the urethane prepolymer (A) are within such ranges, excellent processing suitability, foam stickiness, and moderate crosslinking density can be obtained.
[0020]
Further, the urethane prepolymer (a-2) having a hydrolyzable alkoxysilyl group and an isocyanate group has at least one active hydrogen atom that reacts with the polyol component, the polyisocyanate component, and the isocyanate group per molecule. And obtained by reacting a compound having a hydrolyzable silyl group. Usually, the above-mentioned polyurethane prepolymer having an isocyanate group is reacted with a compound having both a functional group capable of reacting with an isocyanate group and a hydrolyzable silyl group, whereby a hydrolyzable silyl group is formed at the molecular end. The method of introducing is used. In addition to this, by reacting a polyurethane prepolymer having an isocyanate group with a compound having at least two functional groups capable of reacting with the isocyanate group and a hydrolyzable silyl group, the isocyanate group and the hydrolyzable molecule are reacted in the molecule. An alkoxysilyl group-terminated urethane prepolymer is obtained.
[0021]
Examples of the polyol component constituting the prepolymer (A) used in the present invention include polyester polyols, polyether polyols, polycarbonate polyols, and mixtures or copolymers thereof. Furthermore, acrylic polyol, polyolefin polyol, lactone polyol, castor oil polyol, polyhydric alcohol, etc., or a mixture or copolymer thereof can be used.
[0022]
Examples of the polyester polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1,3- Propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, One or more diols such as cyclohexane-1,4-dimethanol, EO or PO adduct of bisphenol A and succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, Sebacic acid, phthalic acid, Sofutaru acid, terephthalic acid, one or condensates of two or more dicarboxylic acids such as hexahydroisophthalic acid and the like. In addition, ring-opening polymers such as γ-butyrolactone and ε-caprolactone using the above-described glycol component as an initiator can be used. In the present invention, EO means ethylene oxide, and PO means propylene oxide.
[0023]
Examples of the polyether polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1, 3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4- Ethylene alcohol starting with a glycol component such as diol, cyclohexane-1,4-dimethanol, or a polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, or the polyester polyol. Side, propylene oxide, butylene oxide, alone or ring-opening polymerization product of styrene oxide, and the like. Moreover, ring-opening addition polymerization products, such as (gamma) -butyrolactone and (epsilon) -caprolactone, to these polyether type diols are mentioned.
[0024]
Furthermore, known low molecular weight polyols can also be used, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2- Dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane One or two or more diols such as 1,4-diol, cyclohexane-1,4-dimethanol, EO or PO adduct of bisphenol A, and the like can be mentioned.
[0025]
The polyisocyanate component that can be used in the prepolymer (A) in the present invention is not particularly limited. For example, phenylene diisocyanate, tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate, 2,4 -Aliphatic or alicyclic diisocyanates such as aromatic diisocyanates such as diphenylmethane diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, etc. It is done. These polyisocyanate components may be used alone or in combination of two or more. Among these, it is preferable to use diphenylmethane diisocyanate (MDI) having a low vapor pressure at the time of heating, considering that it is used for a hot-melt urethane resin that is melted and used.
[0026]
The urethane prepolymer (a-2) having a hydrolyzable alkoxysilyl group and an isocyanate group used in the present invention has at least one active hydrogen atom that reacts with an isocyanate group per molecule, and The compound having a decomposable silyl group is particularly limited as long as it is a compound having at least one functional group having an active hydrogen atom that reacts with an isocyanate group per molecule and having a hydrolyzable silyl group. It is not a thing. Examples of the functional group having an active hydrogen atom include an amino group, a hydroxyl group, and an SH group. Among these, an amino group is preferable from the viewpoint of excellent reactivity with an isocyanate group. On the other hand, examples of the hydrolyzable silyl group include silyl groups that are easily hydrolyzed, such as a halosilyl group, an alkoxysilyl group, an acyloxysilyl group, a phenoxysilyl group, an iminooxysilyl group, or an alkenyloxysilyl group. More specifically, there can be mentioned those represented by the following general formula [1].
[0027]
[Chemical 1]

[0028]
(However, R in the general formula [1]₁ Represents a monovalent organic group selected from a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, R₂ Represents a halogen atom or an alkoxyl group, an acyloxy group, a phenoxy group, an iminooxy group or an alkenyloxy group, and n represents an integer of 0, 1 or 2. )
[0029]
Among the hydrolyzable silyl groups, a trimethoxysilyl group, a triethoxysilyl group, a (methyl) dimethoxysilyl group, a (methyl) diethoxysilyl group, and the like are preferable because crosslinking is likely to proceed.
[0030]
Examples of the compound having both a functional group capable of reacting with the isocyanate group used in the present invention and a hydrolyzable silyl group include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-hydroxyl). Ethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltriethoxysilane, γ- (2-hydroxylethyl) aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldiethoxysilane, γ- (2-hydroxylethyl) aminopropylmethyldimethoxysilane, γ- (2-hydroxylethyl) aminopropylmethyldiethoxysilane or γ- (N, N -Di-2-hydroxylethyl) aminopropyl Reethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ- (N-phenyl) aminopropyltrimethoxysilane, etc. Is mentioned.
[0031]
Furthermore, in the present invention, the prepolymer (A) may be used in combination of two or more polyol components, and the types of polyol component and polyisocyanate component to be used together are not particularly limited.
[0032]
Moreover, the softening point of prepolymer (A) becomes like this. Preferably it is the range of 30-160 degreeC, More preferably, it is the range of 40-100 degreeC. When the softening point of the prepolymer (A) is within such a range, a uniform foam with no unevenness can be obtained, and the cooling and solidifying time of the foamed cell foamed with water can be optimized, which is preferable.
[0033]
The method for adjusting the softening point of the prepolymer (A) used in the present invention is not particularly limited. For example, (1) a method for adjusting by molecular weight (molar ratio of polyol component to polyisocyanate component, use of high molecular weight polyol) , 2) adjustment method by crystallinity of ethylene chain of polyester polyol, 3) adjustment method by structure of aromatic ring of polyol component or polyisocyanate component, 4) urethane bond There are adjustment methods depending on the amount.
[0034]
In order to prepare the prepolymer (A) used in the present invention, various known and conventional methods may be used, and there is no particular limitation.
[0035]
In general, in the case of an isocyanate group-terminated urethane prepolymer (a-1), a polyol component from which moisture has been removed is added dropwise to a raw material isocyanate component and heated to react until there is no hydroxyl group in the polyol component. In the case of a urethane prepolymer (a-2) having a hydrolyzable alkoxysilyl group and an isocyanate group, the isocyanate group-terminated urethane prepolymer (a-1) obtained as described above is reacted with an NCO group. It is obtained by dropping an alkoxysilane compound having a group to be reacted and heating to react as necessary. This reaction is carried out in the absence of a solvent, but in some cases, the reaction can also be carried out in an organic solvent and then removed. When making it react in an organic solvent, well-known and various organic solvents, such as ethyl acetate, n-butyl acetate, methyl ethyl ketone, and toluene, can be used, and if it is an organic solvent which does not inhibit reaction, it will not specifically limit. In this case, after completion of the reaction, it is necessary to remove the solvent by a solvent removal method represented by heating under reduced pressure.
[0036]
Next, examples of the polyisocyanate component (B) used in the present invention include aromatics such as phenylene diisocyanate, tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, and naphthalene diisocyanate. One or two of polyisocyanate components such as aliphatic or alicyclic diisocyanates such as diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate Mixtures of the above can be used. Among these polyisocyanates, it is preferable to use a polyisocyanate having a low vapor pressure during heating when considering use in a hot-melt urethane resin composition that is used by melting. Among these polyisocyanates, diphenylmethane diisocyanate (MDI) is used. It is particularly preferable to use
[0037]
The amount of these polyisocyanate components (B) used is such that the total NCO group content relative to the total weight of the prepolymer (A) and the polyisocyanate component (B) is preferably in the range of 2.0 to 10.0% by weight. More preferably, it is in the range of 2.5 to 8.0% by weight. If the usage-amount of a polyisocyanate component (B) is this range, durability (especially heat resistance and hydrolysis resistance) by favorable foaming property and crosslinking density improvement will become favorable.
[0038]
As a method for adding such a polyisocyanate component (B), if the polyisocyanate component (B) in such a range is added before the polyisocyanate addition in the synthesis of the prepolymer (A), the molecular weight of the prepolymer (A) is increased. Therefore, the initial cohesive force does not appear, and even if foamed, the foam persistence is not good, which is not preferable. For this reason, the prepolymer (A), active hydrogen-containing compound (B), water (C) and / or amine catalyst (D), and foam stabilizer (E) are individually fed into a heated cylinder and stirred at high speed. Alternatively, it is preferably added after the synthesis of the prepolymer (A), mixed with the prepolymer (A) and supplied.
[0039]
In the present invention, the prepolymer (A) is used, but if necessary, a compound (C) having at least two active hydrogens as a chain extender is used as long as the original moisture curability is not impaired. You can also.
[0040]
Examples of the compound (C) having at least two active hydrogens used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, and 1,4-butylene. Glycol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, A variety of glycols such as tripropylene glycol, cyclohexane-1,4-dimethanol, EO or PO adduct of bisphenol A or two or more diols, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. Alcohol, Or ethylene oxide, propylene oxide, butylene oxide, styrene oxide or the like, or two or more ring-opening polymers such as the above-mentioned polyester-based polyol, γ-butyrolactone, ε-caprolactone, etc. of the polyether diol. A ring-opening addition polymer can be used. Also, ethylenediamine, 1,3-propylenediamine, 1,2-propylenediamine, hexamethylenediamine, norbornenediamine, hydrazine, piperazine, N, N'-diaminopiperazine, 2-methylpiperazine, 4,4'-diaminodicyclohexylmethane , Isophoronediamine, diaminobenzene, diphenylmethanediamine, methylenebisdicycloaniline, triethylenediamine, tetramethylhexamethylenediamine, triethylamine, tripropylamine, trimethylaminoethylpiperazine, N-methylmorpholine, N-ethylmorpholine, di ( Polyamines such as 2,6-dimethylmorpholinoethyl) ether and mixtures of one and two or more can be used. However, glycol is preferable in view of processing suitability because the reaction with the isocyanate group at the time of processing is gradual and the crosslinking rate can be easily controlled. If it is a range which does not impair workability, single use of the said polyamine used as a raw material of a urethane resin and combined use with the said polyol will not be restrict | limited in particular.
[0041]
Next, water (D) used by this invention is an essential component which acts as a foaming agent. Carbon dioxide gas is generated by the reaction of the prepolymer (A) and water (D) to produce a foam which is the object of the present invention. The amount of water (D) used is foaming due to excessive generation of carbon dioxide gas. It is preferable that the thickness is selected within a range that does not cause uneven body thickness, poor surface condition, or decrease in workability due to gelation.
[0042]
The water (D) used in the present invention is mixed with stirring and foamed with water in a state where the prepolymer (A), the polyisocyanate component (B), and the compound (C) having at least two active hydrogens are heated and melted. In some cases, an amine catalyst (E) and a foam stabilizer (F) may be added. In the case of only the prepolymer (A), the polyisocyanate component (B), and the compound (C) having at least two active hydrogens, the melt viscosity increases, but the water necessary for foaming with water is insufficient. It is difficult to foam, and in the case of only the prepolymer (A), the polyisocyanate component (B), and water (D), foaming is slightly, but the melt viscosity after foaming does not increase abruptly so that the foam is crushed. As a result, it is difficult to fix the foam. Therefore, in the present invention, the combination of the prepolymer (A), the polyisocyanate component (B), the compound (C) having at least two active hydrogens, and water (D) is used to fix bubbles and increase water by increasing the melt viscosity. It is excellent in the balance of foaming property, and it is further improved by adding an amine catalyst (E) and a foam stabilizer (F) in some cases.
[0043]
The amount of the compound (C) having at least two active hydrogens and the amount of water (D) is such that the total NCO groups of the prepolymer (A) and the polyisocyanate component (B) have at least two active hydrogens ( The residual NCO group content relative to the total charged weight “(A) + (B) + (C) + (D)” after reacting with C) and water (D) is preferably 1.5 to 9.0. It may be in the range of wt%, and more preferably in the range of 2.0 to 8.0 wt%. If the addition amount of the compound (C) having at least two active hydrogens and water (D) is within such a range, a good thickening effect is obtained, the foam has good stickiness, and gels during mixing and stirring. None is preferred.
[0044]
The ratio of the reactive group equivalent of the compound (C) having at least two active hydrogens used in the present invention and water (D) [reactive group equivalent (c) / reactive group equivalent (d)] is 0.5 to 10 0.0, more preferably 1.0 to 5.0.
[0045]
The amount of water (D) added is such that the total NCO groups of the prepolymer (A) and the polyisocyanate component (B) react with the compound (C) having at least two active hydrogens and water (D). When the residual NCO group content is in the range of 1.5 to 9.0% by weight, the total weight of the prepolymer (A) and the polyisocyanate component (B) is preferably 0.05 to 100 parts by weight. -5.0 weight part, More preferably, it can be 0.1-2.0 weight part. If the amount of water (D) added is within such a range, the degree of foaming becomes appropriate, and the surface state of the foam becomes good, which is preferable.
[0046]
The solventless moisture-curable hot melt urethane resin composition of the present invention includes the prepolymer (A), the polyisocyanate component (B), a compound (C) having at least two active hydrogens, and water (D). In addition to the essential components, it is preferable to mix and stir a urethanization catalyst, a foam stabilizer, etc. in a heated and melted state, and each of them can be added alone or in combination of two or more.
[0047]
Examples of the urethanization catalyst used in the present invention include amine-based catalysts, organometallic catalysts, and amidine-based catalysts, and amine-based catalysts (E) are preferred.
[0048]
The amine catalyst (E) used in the present invention is a catalyst constant ratio of KW.₂/ KW₁Is preferably an amine-based catalyst of 0.5 or more. In the present invention, KW₂Is the catalyst constant per weight of the reaction between water and tolylene diisocyanate (TDI) and is KW₁Represents the catalyst constant per weight of the reaction of diethylene glycol (DEG) and tolylene diisocyanate (TDI).
[0049]
KW which is a catalyst constant of such an amine catalyst (E)₁And KW₂Is a constant obtained by measuring the reaction rate of the following polyurethane production reaction formulas (1) and (2).
Reaction Formula (1) RNCO + R′OH → RNHC (═O) OOR ′
Reaction formula (2) 2RNCO + H₂O → RNHC (= O) NHR + CO₂
The reaction rate was measured by the method A. Farkas' method [reference: Am. Chem. Soc. 82, 642 (1960)], the reaction rate constant of water and TDI (K₂) And the reaction rate constant of DEG and TDI (K₁) And, for convenience, the catalyst constant per weight is KW.₂And KW₁Expressed as:
[0050]
Examples of the amine-based catalyst (E) used in the present invention include N, N-dimethylcyclohexylamine (DMCHA), N-methyldicyclohexylamine (MDCHA), N, N, N ′, N′-tetramethylethylenediamine ( TMEDA), N, N, N ′, N′-tetramethylpropylenediamine (TMPDA), N, N, N ′, N′-tetramethylhexamethylenediamine (TMHMDA), N, N, N ′, N ″ , N ″ -pentamethylethylenepropylenetriamine (PMEPTA), N, N, N ′, N ″, N ″ -pentamethyldipropylenetetraamine (PMDPTA), N, N, N ′, N ″, N ′ ″, N ′ ″-hexamethyldipropyleneethylenetetraamine (HMAPEDA), N, N′-dimethylpiperazine (DMP), N, N, N′-trimethyl-N Aminoethylpyrazine (TMNAEP), N-methylmorpholine (NMMO), N-hydroxyethylmorpholine (HEMO), N, N, N ′, N′-tetramethyldipropyleneethylene glycol diamine (TMEGDA), N, N, N ′, N ″, N ′ ″, N ′ ″-hexamethyltetraamine (HMTETA), dimethylaminoethylethanol ether (DMAEE), trimethylaminoethylethanolamine (TMAEEA), bisdimethylaminoethyl ether Among amine-based catalysts such as (BDMEE), triethylamine (TEA), N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine (PMDETA), one kind or a mixture of two or more kinds can be used. Further, if the amine catalyst is an essential component, a urethanization catalyst other than the above, an organometallic catalyst, an amidine catalyst, or the like may be used alone or in combination of two or more.
[0051]
The amount of the amine catalyst (E) used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the prepolymer (A). When the amount of the amine-based catalyst (E) used is within such a range, a good thickening effect is obtained, the foam stickiness is good, and there is no gelation during mixing and stirring, which is preferable. When the catalyst other than (E) is used in combination with the amine-based catalyst (E), which is an essential component, the total amount used of the amine-based catalyst (E) and the catalyst other than (E) is the prepolymer (A). Preferably it is 0.1-10 weight part with respect to 100 weight part, More preferably, it is 0.5-5 weight part.
[0052]
Furthermore, the solvent-free moisture-curable hot melt urethane resin composition of the present invention can be used with a foam stabilizer (F) at the time of use as long as the original moisture-curing property is not impaired. As the foam stabilizer (F), for example, those containing a conventionally known polysiloxane-polyoxyalkylene copolymer used for an organosilicon surfactant are preferable, and a polysiloxane-polyoxyalkylene copolymer is preferable. Is more preferable, specifically, trade names SF2969, PRX607, SF2964, SRX274C, SF2961, SF2962, SF2965, SF2908, BY10-123, SF2904, SRX294A manufactured by Toray Dow Corning Silicone Co., Ltd. , BY10-124, SF2935F, SF2945F, SF2944F, SF2936F, SH193, SH192H, SH192, SF2909, SH194, SH190, SRX290A, SRX298, and Nihon Unicar Corporation Product names L-580, SZ1127, SZ1111, SZ1136, SZ1919, SZ1105, SZ1142, SZ1162, L3601, L5309, L5366, SZ1306, SZ1311, SZ1313, SZ1342, L5340, L5420, SZ1605, SZ1605, SZ1605, SZ1627, SZ1605, SZ1627 , SZ1923 and the like.
[0053]
The amount of the foam stabilizer (F) used is preferably in the range of 0.1 to 20 parts by weight, more preferably in the range of 0.5 to 10 parts by weight, with respect to 100 parts by weight of the prepolymer (A). It is. As long as the amount of the foam stabilizer used is within the range, the foam regulating power is excellent, and the physical mechanical strength of the foam after aging is also excellent.
[0054]
In addition, a plasticizer such as bis (2-ethylhexyl) phthalate (DOP), diisononyl adipate (DINA), bis (2-ethylhexyl) adipate (DOA), EO, etc. A polyether surfactant such as a / PO copolymer may be added.
[0055]
The crosslinking reaction of the solventless moisture-curable hot-melt urethane resin composition of the present invention occurs when an isocyanate group or a hydrolyzable alkoxysilyl group in each prepolymer reacts with moisture.
[0056]
The solventless moisture-curable hot-melt urethane resin composition having excellent durability according to the present invention has a crosslinking reactivity (that is, moisture-curing property) and hot-melt property (that is, it is solid at room temperature and melts by heating). It means a resin composition having a property that it can be applied and a state where a cohesive force appears again by cooling.
[0057]
As a processing method of the solventless moisture-curable hot melt urethane resin composition of the present invention, for example, the prepolymer (A) is heated to be in a liquid or molten state, and at least 2 of the polyisocyanate component (B) and active hydrogen are added. After mixing and stirring with compound (C), water (D), and / or amine catalyst (E), foam stabilizer (F), and foaming with water, use hot melt and moisture curability Thus, a method of fixing the foamed state is suitable. Further, when the shape of the cell of the foam layer is controlled from the closed cell state to the continuous state, it is possible to mix and stir the inert gas.
[0058]
The solventless moisture-curable hot melt urethane resin composition of the present invention is necessary when mixing the prepolymer (A), the polyisocyanate component (B), the compound (C) having at least two active hydrogens, and water (D). Depending on the chain extender containing active hydrogen, amine-based catalyst (E), foam stabilizer (F), silane coupling agent, tackifier, crosslinking catalyst, thixotropic agent, wax, plasticizer, stabilizer , Fillers, pigments, additives such as fluorescent brighteners, thermoplastic resins, etc. may be used alone or in combination of two or more.
[0059]
The foamed layer in the present invention refers to an important layer for adding a texture as leather in a multilayer structure constituting artificial leather or synthetic leather. As a method for obtaining the foamed layer, (1) a wet method using a DMF solvent, (2) a method using a foaming agent, (3) a method using carbon dioxide gas generated by the reaction between isocyanate and water, (4) A method by mechanical foaming by forced gas mixing is known.
[0060]
The foam of the present invention comprises a solventless moisture-curable hot melt urethane resin composition comprising a prepolymer (A), a polyisocyanate component (B), a compound (C) having at least two active hydrogens, and water (D). It is characterized in that the product is obtained by mixing and stirring in a heated and melted state, foaming with water, and then curing by moisture. The foam of the present invention comprises an amine catalyst (E), a prepolymer (A), a polyisocyanate component (B), a compound (C) having at least two active hydrogens, and water (D), It may be obtained by mixing and stirring a solventless moisture-curable hot-melt urethane resin composition containing a foam stabilizer (F) and the like while being heated and melted, foaming with water, and then moisture-curing. .
[0061]
In addition, the foam of the present invention is obtained by heating the solventless moisture-curable hot melt urethane resin composition to a liquid or molten state, mixing an inert gas in advance and foaming with water as necessary. A method of fixing by using a hot melt property and moisture curable property to fix the foamed state is preferable. When an inert gas is mixed, a difference in coefficient of thermal expansion between water and the inert gas is generated, so that the size of the foam cell can be controlled by the mixing ratio, which is effective.
[0062]
In addition, when the shape of the cell of the foam layer is controlled from the closed cell state to the connected state, it is possible to mix and stir the inert gas. Examples of the inert gas include nitrogen, rare gas, carbon dioxide, and halogenated hydrocarbon.
[0063]
The foam of the present invention was mixed and stirred with the above-mentioned solvent-free moisture-curable hot-melt urethane resin composition heated and melted, mixed with an inert gas as needed, and foamed with water. Thereafter, it is obtained by moisture curing.
[0064]
Most of the bubbles (also referred to as cells in the present invention) in such a foam are normally in the form of single bubbles (independent bubbles), but some of the bubbles (cells) communicating with each other may be mixed. The size can be appropriately controlled, but a diameter of about 5.0 to 200 μm is preferable. Further, the thickness of the foam is not particularly limited, but when used for synthetic leather or artificial leather, a thickness of about 0.05 to 1.0 mm is preferable. The size of the foam and the thickness of the foam are also applied to the foam layer obtained from the solventless moisture-curable hot melt urethane resin composition of the present invention in the sheet structure described later.
[0065]
The number average molecular weight of the prepolymer (A) thus prepared is not particularly limited, but is preferably in the range of 500 to 500,000, more preferably 1 in terms of fluidity and processability. The range is from 100,000 to 100,000.
[0066]
In preparing the prepolymer (A), if necessary, a urethanization catalyst or a stabilizer may be used. These catalysts, stabilizers and the like can be added at any stage of the reaction and are not particularly limited.
[0067]
As the urethanization catalyst, known and commonly used catalysts can be used, for example, various metal salts represented by potassium acetate, zinc stearate, tin octylate and the like; or represented by dibutyltin dilaurate and the like. And various organometallic compounds. These may be used alone or in combination of two or more.
[0068]
Examples of the stabilizer include stabilizers against ultraviolet rays such as substituted benzotriazoles, and further stabilizers against thermal oxidation such as substituted phenol derivatives. The agent can be appropriately selected and added according to the purpose, and may be used alone or in combination of two or more.
[0069]
Further, in the case of the urethane prepolymer (a-2) having a hydrolyzable alkoxysilyl group and an isocyanate group, various acidic compounds such as malic acid and citric acid, hydroxylation can be used as a crosslinking catalyst as necessary. Various basic compounds such as lithium, sodium hydroxide, potassium hydroxide, triethylenediamine, tetraisopropyl titanate, di-n-butyltin dilaurate, di-n-butyltin oxide, dioctyltin oxide or di-n-butyl What is generally used as an alkoxysilyl group crosslinking catalyst such as various metal-containing compounds such as tin maleate can be added and used.
[0070]
Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-methacryloxy. Examples include propyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.
[0071]
Examples of the filler include calcium carbonate, barium sulfate, kaolin, talc, carbon black, alumina, magnesium oxide, and inorganic / organic balloons.
[0072]
Examples of the thixotropic agent include surface-treated calcium carbonate, fine powder silica, bentonite, and sepiolite. In particular, the addition of a thixotropic agent is preferable from the viewpoint of stabilizing the foam after foaming.
[0073]
The sheet structure of the present invention is obtained by mixing and stirring the solventless moisture-curable hot-melt urethane resin composition in the state of being heated and melted, foaming with water, and then laminating a foam that has been moisture-cured. It is characterized by.
[0074]
The sheet structure of the present invention is a foamed layer in which the above-mentioned solventless moisture-curable hot melt urethane resin composition is heated and melted, mixed and stirred in advance with an inert gas, foamed with water, and then moisture-cured. May be laminated.
[0075]
The sheet structure of the present invention is prepared by mixing and stirring the solventless moisture-curable hot-melt urethane resin composition in a state of being heated and melted, foaming with water, laminating a foam-cured moisture, and further leather. It is characterized by laminating various film layers.
[0076]
The sheet structure of the present invention is a foamed layer in which the above-mentioned solventless moisture-curable hot melt urethane resin composition is heated and melted, mixed and stirred in advance with an inert gas, foamed with water, and then moisture-cured. And a leather-like film layer may be further laminated.
[0077]
The sheet structure of the present invention has a leather-like film and a foamed layer obtained by foaming the solventless moisture-curable hot-melt urethane resin composition on the film with water and then curing the foamed layer. Also good.
[0078]
The sheet structure of the present invention comprises a leather-like film and the solvent-free moisture-curable hot-melt urethane resin composition mixed with the inert gas in advance, foamed with water, and then cured. It may have a foam layer.
[0079]
The foaming degree of the foam of the present invention can be appropriately adjusted according to its use, and is not particularly limited as long as the texture or strength is not impaired. For example, in the case of artificial leather or synthetic leather, the foaming degree is usually preferably in the range of 1.5 to 3.0 times. The “degree of foaming” here refers to the volume of resin before foaming (V₁) And the volume of resin after foaming (V₂) Ratio [V₂/ V₁].
[0080]
A sheet structure can be produced from the solventless moisture-curable hot-melt urethane resin composition of the present invention and a sheet substrate. That is, a sheet structure can be obtained by applying the resin composition on a sheet substrate in a heat-melted state, foaming with water, and then curing the moisture to form a foamed layer. Of course, a sheet structure in which a sheet base material is further laminated on the foam layer, or a sheet structure in which a foam layer made of the above resin composition is integrated between three or more sheet base materials can be used.
[0081]
As a sheet base material constituting the sheet structure of the present invention, for example, non-woven fabrics, woven fabrics, knitted fabrics and the like, which are generally used for artificial leather and synthetic leather, natural leather, various plastic sheets, films The film is not limited as long as it is a film with release paper, release paper, paper, and the like. In addition, the base fabric is generally made of nonwoven fabric, woven fabric, knitted fabric or the like in which at least one kind of solvent-based and water-based polyurethane resin, acrylic resin, rubber-based (SBR, NBR, etc.) latex is impregnated. In addition, the base fabric and natural leather used in artificial leather and synthetic leather are not limited at all.
[0082]
The film as a sheet base material and film with release paper used in the present invention is preferably a polyurethane resin conventionally used for artificial leather or synthetic leather, and usually a release resin such as a solvent-based resin, a water-based resin, or a hot-melt resin. It can be obtained by coating and drying on top.
[0083]
The foam and sheet structure of the present invention were foamed with water by mixing an inert gas as necessary in the state where the solventless moisture-curable hot melt urethane resin composition of the present invention was heated and melted. For example, the foamed resin is uniformly laminated between the release paper, or between the sheet base material and the release paper, or between the base cloth and the leather-like film, and between the release paper and the water-repellent treatment cloth and film, and then cooled and solidified. There is no particular limitation as long as it can be processed after being crosslinked. In addition, after the foam is adjusted, it may be bonded using a sheet base material or / and a leather-like film, a solvent-based adhesive, a water-based adhesive, a hot-melt adhesive, or the like. In order to promote foaming and curing of the foam, the substrate surface or the foam surface of the substrate to which the foam is bonded, and the substrate surface or the foam surface of the structure in which the foam is integrated are humidified. Processing may be performed.
[0084]
The equipment for foaming the solventless moisture-curable hot-melt urethane resin composition of the present invention is preferably equipment that can be uniformly mixed while mixing a predetermined amount of inert gas as required. The mixture can be heated and kept warm in order to avoid coating failure and adhesion failure without flowing when the foam is cooled and thickened by stirring and uniform foaming is not performed or when it is processed as a foam layer on a substrate or film A structure is desirable.
[0085]
When producing the foam and the sheet structure in the present invention, the solvent-free moisture-curable hot melt urethane resin composition of the present invention is heated and melted and foamed with water. It is above the temperature at which the polymer (A) melts, and is preferably in the range of 60 to 200 ° C. If it is the range which requires heating temperature, control of foaming of this resin composition is easy, it is easy to obtain a homogeneous foam, and it is preferable.
[0086]
As an apparatus for producing a foam or sheet structure in the present invention, for example, industrially, a tank for heating and melting the prepolymer (A), a tank for storage and supply of water and other additives, etc. A tank for mixing the respective materials, a belt for continuously conveying the release paper and the sheet substrate, a nozzle for supplying a resin composition melted on the belt, a humidifying chamber for curing the foam, and a heating chamber if necessary And other sheet base material supply sections. The above-described apparatus is representative, and various other modifications may be used.
[0087]
The equipment for foaming the resin composition of the present invention in combination with an inert gas is not particularly limited as long as the equipment can be uniformly mixed while mixing a predetermined amount of the inert gas. In order to avoid application failure and adhesion failure without flowing when the foam is cooled and thickened by stirring during mixing and uniform foaming is not performed or when processed as a foam on a substrate, film, or sheet A structure that can heat and maintain the mixture is desirable.
[0088]
Various processing methods, such as surface processing by the well-known usual lamination or coating, etc. to the foam or sheet structure obtained by this invention, or buffing, are not limited at all.
[0089]
As described above, according to the present invention, a solventless moisture-curable hot-melt urethane resin composition that is particularly excellent in adhesiveness, foamability, and durability (particularly hydrolysis resistance and heat resistance), and the urethane resin composition A foam obtained by using the sheet, a sheet structure using the same, and a method for producing the sheet structure can be provided.
[0090]
The solventless moisture-curable hot-melt urethane resin composition of the present invention, and the foam and sheet structure using the same are, for example, synthetic leather used for shoes, furniture, clothing, vehicles such as automobiles, bags, cases, etc. In addition to leather and artificial leather, adhesives, adhesives, sealing agents, paints, coating agents, films, sheets, heat insulating materials, heat insulating materials, sound absorbing materials, cushioning materials, anti-slip, polishing pads, electronic appliance materials, building materials, civil engineering It is extremely practical in a wide range of applications such as medical parts.
[0091]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited only to these examples. In the following, all parts and% are based on weight unless otherwise specified. Various characteristics were measured according to the following methods.
[0092]
[Method for producing skin film 1]
Crisbon NY324 (manufactured by Dainippon Ink & Chemicals, Inc.), which is a solvent-type urethane resin for synthetic leather, and pigments DILAC-6001 (manufactured by Dainippon Ink & Chemicals, Inc.), methyl ethyl ketone (MEK) and dimethylformamide (DMF) ) And stirring with a knife coater, the coating amount on the release paper is 100 g / m²After uniformly coating so as to be (wet), the film was dried at 70 ° C. for 1 minute, and then dried at 120 ° C. for 2 minutes to prepare a skin film 1 having a thickness of 30 μm.
[0093]
[Measurement method of softening point]
The softening point of each prepolymer obtained in Examples and Comparative Examples was measured using a differential calorimeter (DSC, manufactured by Mac Science Co., Ltd.) in a nitrogen atmosphere at a heating rate of 5 ° C./min.
[0094]
[Measurement method of adhesion]
A fabric hot melt tape was thermocompression bonded at 130 ° C for 5 seconds to the skin film 1 of the sheet structure with a skin film that was left for 5 days in an environment of a temperature of 23 ° C and a relative humidity of 65%, and then at a head speed of 200 mm / min. In accordance with JIS K6311, the peel strength was measured using Tensilon and the adhesion was evaluated.
[0095]
[Measurement method of hydrolysis resistance]
After subjecting the sheet structure with a skin film to a hydrolysis resistance test (jungle test conditions: 70 ° C., relative humidity 95%, maintained for 12 weeks), the peel strength was measured in the same manner as the above-described adhesive evaluation method, The retention rate and the appearance change after evaluation were observed and evaluated according to the following criteria.
○: No change in appearance after jungle test.
X: Appearance change after jungle test.
[0096]
[Measurement method of heat resistance]
The sheet structure with a skin film was subjected to a heat resistance test (test condition: 120 ° C., held for 500 hours), and then peel strength was measured in the same manner as the above-described adhesive evaluation method to determine the retention rate and the appearance after evaluation. Changes were observed and evaluated according to the following criteria.
○: No change in appearance after test.
X: Appearance change after test.
[0097]
<< Example 1 >> Manufacturing method of sheet structure 1 with skin film
70 parts of polytetramethylene glycol (hereinafter abbreviated as PTMG1400) having a number average molecular weight of 1400, 1-liter 4-neck flask, adipic acid (abbreviated as AA in the table) and hexanediol (abbreviated as HG in the table) 30 parts of a polyester polyol having a number average molecular weight of 2000 (described as polyester polyol 2000 in the table) was heated under reduced pressure to 120 ° C. and dehydrated to a moisture content of 0.05%. After cooling to 40 ° C., 4,4′-diphenylmethane diisocyanate (MDI) was added so as to have the NCO content (% by weight) shown in Table 1 (hereinafter abbreviated as NCO%), and then to 90 ° C. The temperature was raised and the reaction was continued for 3 hours until NCO% became constant to obtain Prepolymer 1. The viscosity at 125 ° C. with a cone plate viscometer was 7000 mPa · s. While the obtained prepolymer 1 was heated to 120 ° C. and melted and heated at 120 ° C., the total NCO group content (% by weight) shown in Table 1 with respect to 100 parts of the prepolymer 1 1.0 parts of ethylene glycol (EG), POLYCAT-8 [manufactured by Air Products Japan; N, N-dimethylcyclohexylamine (DMCHA), ratio of catalyst constants; KW₂/ KW₁= 3.73] and 0.12 part of water were added and mixed, and it was confirmed from the volume that the foam was about 2.8 times. Immediately, it is applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated nonwoven fabric, cooled, and left for 5 days in an environment of a temperature of 23 ° C. and a relative humidity of 65%, with a sheet-like surface film attached. A structure 1 was obtained. The characteristic evaluation results of the sheet-like structure 1 with a skin film of the present invention are shown in Table 1, and were excellent in foamability, adhesiveness, heat resistance, and hydrolysis resistance.
[0098]
Example 2 Method for Producing Sheet Structure 2 with Surface Film
In a 1 liter four-necked flask, the prepolymer 1 obtained in Example 1 was heated to 120 ° C. and melted and heated at 120 ° C. The mixture was mixed with 1.0 part of EG, 0.10 part of POLYCAT-8, and 0.12 part of water to achieve the total NCO group content shown, and foamed approximately 3.0 times. This was confirmed from the volume. Immediately, it was applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated non-woven fabric, cooled, and allowed to stand in an environment of a temperature of 23 ° C. and a relative humidity of 65% for 5 days to form a sheet structure with a sheet-like skin film. Body 2 was obtained. The characteristic evaluation results of the sheet-like sheet structure 2 with a skin film of the present invention are shown in Table 1, and were excellent in foamability, adhesiveness, heat resistance, and hydrolysis resistance.
[0099]
Example 3 Method for Producing Sheet Structure 3 with Surface Film
In a 1 liter four-necked flask, 70 parts of PTMG 1400 and 30 parts of polyester polyol 2000 were heated to 120 ° C. under reduced pressure, and dehydrated to a moisture content of 0.05%. After cooling to 40 ° C., 4,4′-diphenylmethane diisocyanate (MDI) was added so as to have the NCO content (% by weight) shown in Table 1, and the temperature was raised to 90 ° C. By reacting for 3 hours until it became constant, prepolymer 2 was obtained. The viscosity at 125 ° C. with a cone plate viscometer was 9000 mPa · s. While the obtained prepolymer 2 was heated to 120 ° C. and melted and heated at 120 ° C., 100 parts of the prepolymer 2 had an MDI having the total NCO group content shown in Table 1. , 0.16 part of EG, 0.10 part of POLYCAT-8, and 0.10 part of water were added and mixed, and it was confirmed from the volume that the foam was about 2.5 times. Immediately, it is applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated nonwoven fabric, cooled, and left for 5 days in an environment of a temperature of 23 ° C. and a relative humidity of 65%, with a sheet-like surface film attached. Structure 3 was obtained. The characteristic evaluation results of the sheet-like structure 3 with a skin film of the present invention are shown in Table 1, and were excellent in foamability, adhesiveness, heat resistance, and hydrolysis resistance.
[0100]
Example 4 Method for Manufacturing Sheet Structure 4 with Surface Film
The prepolymer 1 obtained in Example 1 was heated and melted to 120 ° C. and then heated to 120 ° C., and the number average molecular weight of 1000 propylene glycol (hereinafter referred to as PPG1000) and the total MDI shown in Table 1 While mixing dibutylditin dilaurate (DBSNDL) at a (prepolymer 1 + MDI) /PPG1000/DBSNDL=100/3.0/0.1 weight ratio so as to obtain an NCO group content, 1.0 part of EG, It was confirmed from the volume that POLYCAT-8 was mixed with 0.10 parts of water and 0.12 parts of water, and foamed about 2.8 times. A foamed prepolymer 3 was obtained. Immediately, it is applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated nonwoven fabric, cooled, and left for 5 days in an environment at a temperature of 23 ° C. and a relative humidity of 65%, with a sheet-like skin film attached. A sheet structure 4 was obtained. The characteristic evaluation results of the sheet-like sheet structure 4 with a surface film of the present invention are shown in Table 1, and were excellent in foam blue, adhesiveness, heat resistance, and hydrolysis resistance.
[0101]
<< Comparative Example 1 >>
The prepolymer 1 obtained in Example 1 was heated to 120 ° C. in a 1-liter four-necked flask and melted and heated at 120 ° C., while EG was 1.30 with respect to 100 parts of the prepolymer 1. 0.10 parts of POLYCAT-8 and 0.15 parts of water were added and mixed, and it was confirmed from the volume that the foam was about 1.0 times. Immediately, it was applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated non-woven fabric, cooled, and allowed to stand for 5 days in an environment at a temperature of 23 ° C. and a relative humidity of 65%. Structure 5 was obtained. The characteristic evaluation results are shown in Table 2. This product was inferior in foamability and heat resistance.
[0102]
<< Comparative Example 2 >>
In a 1 liter four-necked flask, the prepolymer 2 obtained in Example 3 was heated to 120 ° C. and melted and heated at 120 ° C., and only 100 parts of the prepolymer 2 were mixed. It was confirmed from the volume that foaming was almost zero. Immediately, it was applied to the skin film 1 with a thickness of 50 μm, bonded to a polyurethane-impregnated non-woven fabric, cooled, and allowed to stand for 5 days in an environment at a temperature of 23 ° C. and a relative humidity of 65%. A structure 6 was obtained. The characteristic evaluation results are shown in Table 2. This product was inferior in foamability and heat resistance.
[0103]
[Table 1]

[0104]
[Table 2]

[0105]
【The invention's effect】
The solventless moisture-curable hot melt urethane resin composition of the present invention comprises an isocyanate group-containing hot melt urethane prepolymer (A), a polyisocyanate component (B), a compound (C) having at least two active hydrogens, and water. It is a resin composition comprising (D) and is excellent in foamability, adhesiveness and durability (particularly heat resistance and hydrolysis resistance). The resin composition of the present invention can be mixed and stirred in a heated and melted state, foamed with water, and then cured by moisture to obtain a foam, and a sheet structure using the same can be used for shoes, furniture, for example. In addition to synthetic leather and artificial leather used for clothing, vehicles such as automobiles, bags, cases, etc., adhesives, adhesives, sealing agents, paints, coating agents, films, sheets, heat insulating materials, heat insulating materials, sound absorbing materials, It is extremely practical in a wide range of applications such as cushion materials, anti-slip, polishing pads, electronic electrical materials, building materials, civil engineering, and medical materials.

Claims (12)

An isocyanate group-containing hot melt urethane prepolymer (A), a polyisocyanate component (B), a compound (C) having at least two active hydrogens , water (D) , and N, N-dimethylcyclohexylamine as essential components, Compound (C) having a total isocyanate (NCO) group content in the range of 2.0 to 10.0% by weight based on the total weight of polymer (A) and polyisocyanate component (B), and having at least two active hydrogens And the residual NCO of the prepolymer (A) and the polyisocyanate component (B) with respect to the total charged weight “(A) + (B) + (C) + (D)” after reacting with water (D) solventless moisture curable hot melt urethane resin composition based on content, wherein the range der Rukoto of 1.5 to 9.0 wt%. The solvent-free moisture-curable hot-melt urethane resin composition according to claim 1, wherein the prepolymer (A) has a softening point in the range of 30 to 160 ° C. The solvent-free moisture-curable hot melt urethane resin composition according to claim 1 or 2, wherein the prepolymer (A) is an isocyanate group-terminated urethane prepolymer obtained by reacting a polyol component and a polyisocyanate component. The solvent-free moisture-curable hot according to claim 1 or 2, wherein the total NCO group content relative to the total weight of the prepolymer (A) and the polyisocyanate component (B) is in the range of 2.5 to 8.0% by weight. Melt urethane resin composition. The solvent-free moisture-curable hot-melt urethane resin composition according to claim 1 or 2, wherein the prepolymer (A) has an isocyanate group-terminated urethane prepolymer or a urethane prepolymer having a hydrolyzable alkoxysilyl group and an isocyanate group. object. Reactive group equivalent ratio [reactive group equivalent (c) / reactive group equivalent (d)] of compound (C) having at least two active hydrogens and water (D) is in the range of 0.5 to 10.0. The solventless moisture-curable hot melt urethane resin composition according to claim 1 or 2. The solventless moisture-curable hot melt urethane resin composition according to claim 1 or 2, further comprising a foam stabilizer (F) as an essential component. The solvent-free moisture-curable hot-melt urethane resin composition according to claim 7 , wherein the foam stabilizer (F) comprises a polysiloxane-polyoxyalkylene copolymer. It is obtained by mixing and stirring the solventless moisture-curable hot-melt urethane resin composition according to any one of claims 1 to 8 in a heated and melted state, foaming with water, and then moisture-curing the composition. Foam. A sheet structure obtained by laminating the foam according to claim 9 on a sheet substrate. A sheet structure obtained by laminating the foam according to claim 9 on a sheet substrate and further laminating a leather-like film layer. A solvent-free moisture-curable hot melt urethane resin composition according to any one of claims 1 to 8 is heated and melted on a sheet substrate, foamed with water, laminated, and then moisture-cured. A method for manufacturing a sheet structure.