JP4004938B2 - Suede-like artificial leather - Google Patents
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- JP4004938B2 JP4004938B2 JP2002371326A JP2002371326A JP4004938B2 JP 4004938 B2 JP4004938 B2 JP 4004938B2 JP 2002371326 A JP2002371326 A JP 2002371326A JP 2002371326 A JP2002371326 A JP 2002371326A JP 4004938 B2 JP4004938 B2 JP 4004938B2
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Description
【0001】
【発明の属する技術分野】
本発明は、発色性および外観が極めて良好でかつ機械的物性に優れ、軽量で柔軟なスエード調人工皮革およびその製造方法に関する。
【0002】
【従来の技術】
人工皮革の各分野で、機械的諸物性に優れ、軽量で柔軟な製品が求められている。従来から、海成分が溶出可能な海島構造の多成分繊維、例えば海成分がポリエチレンからなる海島構造の繊維を用いて不織布とし、それを用いて人工皮革とすることは公知である。かかる海島構造繊維は最終製品となるまでのいずれかの工程で海成分を除去して繊維を極細化し極細繊維を得る。このような製品は極細繊維特有の風合いと良好なスエード外観を有し、市場での一定の評価を得ている。しかし極細繊維化時のシートとしての厚み減少による比重の上昇は避け難く、軽量化性能を兼ね備えたものではなかった。
また異種の繊維を目的にあわせて混合し、絡合不織布とすることは従来から行われている方法である。2種類以上のウェッブ、シート類を積層および、または混合して絡合させた交絡体およびこれらの交絡体に高分子弾性体溶液を含浸、凝固する方法がある(例えば、特許文献1参照。)。これらは皮革ライクで機械的物性に優れているものもあるが、良好なスエード外観及び軽量化性能を兼ね備えたものではなかった。
また、衣料製品などに軽量、保温性等の観点からポリエステル、ナイロンの中空繊維が一般的に用いられている。合成皮革、人工皮革の分野においては、中空繊維を用いた軽量で通気性の良好な合成皮革がある(例えば、特許文献2、特許文献3参照。)。また微小中空粒子を混合して軽量化と保温性の向上をはかった合成皮革がある(例えば、特許文献4参照。)。
これらのように中空構造を持つ繊維を合成皮革、人工皮革に用い軽量化を図る技術は公知であるが、スエードとしての外観が不十分なものであり、また軽量性と必要な機械的性能をもつものであっても近年強く要求される柔軟性および表面の外観に関しては不十分であり、これらすべてを併せもつものではなかった。
【0003】
【特許文献1】
特公昭48−11925号公報(第2頁)
【特許文献2】
特開昭47−28104号公報(第2頁)
【特許文献3】
特開昭50−5502号公報(第1頁)
【特許文献4】
特開平1−292188号公報(第2頁)
【0004】
【発明が解決しようとする課題】
人工皮革の各分野では一般的に0.5〜1.3mmの厚みの基体が用いられている。この厚みの範囲のなかでより軽く、機械的物性に優れた、柔軟な製品が求められており、特にスエード調人工皮革において機械的物性に優れていることと、軽量で柔軟なスエード感に優れていることとは裏腹の関係にあり、これらすべてを満足する人工皮革基体は未だ開発されていない。
このように人工皮革の各分野では、高級感の向上が求められ、その中でも、外観の高級感と軽量性能はもっとも強く望まれているものである。その一方で、用途に応じた機械的物性と製品としての軽くて、優れた外観を併せもつことが極めて重要となる。
【0005】
その課題解決の方策として、抽出等で極細化可能な多成分繊維からなる、例えば海島構造繊維シートから抽出等で除去する成分の比率を増加させる方法が知られているが、製造工程でのテンションやプレス処理によって厚みが低下し、軽量化出来ず、機械的物性も不足することとなる。また、人工皮革製品の繊維量自体を減ずる方法では、軽量化は出来るが、諸物性が不足する問題点がある。
また、中空繊維のステープルの嵩高さを利用して人工皮革にこれらの中空繊維を用いて基体とする方法は、確かに軽量化は達成出来るが、繊維中に中空を形成させるため、必然的に繊維デシテックスが大きくなり表面の平滑性に欠け、特にスエード用途としての外観が確保出来ず、また風合いも柔軟ではない。
本発明の目的は、このような問題を解決し、発色性および外観が極めて良好でかつ機械的物性に優れ、軽量で柔軟なスエード調人工皮革を提供することにある。
【0006】
【課題を解決するための手段】
前述の目的を達成するために本発明者らは鋭意研究を行い、その結果、6デシテックス以下の繊維横断面に5個以上の中空部を特定の条件を満たしながら有する繊維を三次元絡合されている不織布を用いることで、外観が極めて良好でかつ軽量で柔軟なスエード調人工皮革にすることができることを見いだした。
すなわち本発明は、5個以上の中空部を有する単繊維繊度6デシテックス以下の中空繊維が三次元絡合された不織布および該不織布の内部に高分子弾性体が含浸されてなる基体の少なくとも片面に該中空繊維が2本以上に割繊されて形成される最大径6μm以下の極細繊維からなる立毛部分が存在することを特徴とするスエード調人工皮革であり、好ましくは、中空繊維の断面状態が下記式を満足する請求項1に記載のスエード調人工皮革である。
25≦(sm/S)×100≦65
(s/S)×100≦5
s:中空繊維断面の中空部1個の平均面積
m:中空繊維断面の中空部の個数
S:中空繊維断面の外周で囲まれた面積
さらに本発明のスエード調人工皮革は以下の(1)〜(4)の工程を順次行うことにより製造することができる。
(1)5個以上の中空部を有する単繊維繊度6デシテックス以下の中空繊維を発生させる複合繊維より不織布を製造する工程、
(2)不織布に高分子弾性体を含浸させる工程、
(3)複合繊維から中空部を発生させる処理を行い、5個以上の中空部を有する中空繊維を発生させる工程、
(4)少なくとも片面の中空繊維を2個以上に割繊し、横断面の最大径を6μm以下に極細繊維化し、立毛を形成させる工程。
【0007】
【発明の実施の形態】
本発明における繊維の横断面に5個以上の中空部を有する繊維は、2種のポリマーを所定の混合比で混合して、同一溶融系で溶融し紡糸する方法、または島成分を構成するポリマーと海成分ポリマーとを、別々の溶融系で溶融し、紡糸頭部で接合−分割を複数回繰り返して両者の混合系を形成して紡糸する方法、あるいは両者を紡糸口金構造で繊維形状を規定して合流させて紡糸するいわゆる海島型繊維から、島成分を除去することにより得られる。本発明においては、2種のポリマーを所定の混合比で混合して、同一溶融系で溶融し紡糸するチップブレンド方法では、除去すべき島成分単位が細い径になり、除去しにくく、また、島状態の径、島間距離が不規則になり、島間の小さい部分は島除去後の中空部と中空部が接近した状態になり、その部分が潰れて扁平化、または破壊されやすく、中空部としての効果がなくなる。
本発明においては別々の溶融系で溶融し、紡糸頭部で接合−分割を複数回繰り返して両者の混合系を形成して紡糸する方法、あるいは両者を紡糸口金構造で繊維形状を規定して合流させて紡糸する方法が中空部となる島径、島間距離が均一になりやすい点で適している。
【0008】
本発明の中空繊維の横断面中に占める島成分(中空発生部)の総面積比率(sm/S)は25≦(sm/S)×100≦65であることが好ましい。
この様な中空繊維を得るためには中空部発生型繊維形態を持つ複合繊維を製造する必要がある。中空部発生型繊維の形態は一般的に海島型の複合繊維とすることが多く、極細繊維を得る方法としては、海成分が溶出可能な海島構造の繊維とし、その後海成分を抽出除去して極細繊維を得る方法が用いられている。本発明では、この方法で島成分が溶出可能な海島型の繊維とし、その後島成分を抽出除去して中空部を有する繊維とするが、島成分が連続相状の海成分に囲まれているため、島成分の除去が困難な状態となるので特に島成分ポリマーの選択には構成する海成分ポリマーとの溶解性、分解性に注意を払うことが重要である。
【0009】
本発明の中空部発生型繊維の島成分(中空部発生)ポリマーとしては、海成分ポリマーよりも溶融粘度が高く、海成分との溶解性、分解性を異にし、島成分ポリマーの溶解、除去に用いられる溶剤または分解剤等への溶解性が大きく、海成分ポリマーとの相溶性の小さいポリマーが好ましいが、特に海島型繊維から島成分を除去するにあたり、島成分ポリマーの除去に用いられる溶剤または分解剤への溶解性が大きいものを選択することが必要である。例えばポリエチレン、変性ポリエチレン、ポリスチレン、変性ポリエステル、水可溶性のポリエステル共重合体、水溶性かつ熱可塑性の変性ポリビニールアルコールなどが好適に用いられる。
本発明での除去される島成分としては、例えば、エチレン単位を5〜10モル%含有し、重合度が200〜500、鹸化度が90〜99モル%である水溶性かつ熱可塑性の変性ポリビニルアルコールは、50〜100℃の熱水に容易に溶解する性質があり、品質上のみならず環境に配慮したプロセス設計の面からも特に好ましい。
【0010】
また、中空部を有する繊維を構成するポリマーとしては、溶融紡糸時に繊維形成能があり、中空部を発生させるための溶剤または分解剤などで溶解または分解除去されない成分、例えばポリエチレンテレフタレート、ポリブチレンテレフタレート等で代表されるポリエステル系ポリマー、およびこれを主体とする共重合体、6−ナイロン、66−ナイロン等で代表されるポリアミド系ポリマー、およびこれを主体とする共重合体等が適しているが、これらのポリマーは、単一ポリマーのみならず、2成分以上の混合物としたものでもよく、顔料粒子、紫外線吸収剤等の公知の各種添加剤を含むものであってもよい。
【0011】
本発明で重要な点は、繊維の横断面における中空部1個の占める面積(s)が中空繊維断面の外周で囲まれた面積(S)に対して、(s/S)×100≦5であることが好ましく、5を超える場合には、島部除去工程のテンション、プレス処理工程によって繊維断面の中空部分の潰れが顕著になり易く、また製品では屈曲・圧縮時の中空部の潰れ、変形がおきやすい傾向がある。また繊維中の1個の島部分(中空部分)の面積が少なすぎると、中空部を発生させる島成分を除去する際のテンション、プレス工程によって、島成分を除去したにもかかわらず、中空部が潰れてなくなり易いため、好ましくは2以上である。
また繊度6デシテックス以下の中空繊維の横断面中に占める島成分(中空発生部)の総面積比率(sm/S)は25≦(sm/S)×100≦65であることが好ましい。島成分の面積比率が25未満では軽量化の効果が不十分になるばかりか、スエード調人工皮革とするために表面の中空繊維をバフィングで割繊する際、中空間の壁の厚みが大きくなるため、割繊困難となる。また、65を超える場合は島部除去後の中空間の壁の厚みが薄くなるため、表面の多中空繊維をバフィングで割繊し、ミクロファイバー化し易くなるが、工程のテンション、プレス処理工程によって繊維断面の中空部分の潰れが顕著になり、基体の比重が上がり軽量な基体が得られにくい。
一般に島部分の太さとしては、2.5〜8.0μmの範囲が島成分除去後の中空部を有する繊維の形状安定性の点で好ましい。
また、中空率は中空繊維となる海部分と中空部を発生さす島部分の海島体積比率、島部除去時の海成分の形態維持性で異なるので、適宜組み合わせをするのが好ましい。一般的に海比率が少ない場合、また島繊度が細すぎると島成分除去時に中空部分の潰れが顕著になり、また表面繊維の割繊が困難になる傾向にある。
【0012】
本発明では繊維横断面中での1個の中空部分の占める面積と、中空部総面積の下式を両立することにより製品としての使用時の屈曲により、中空部が潰れて扁平化、または破壊したりすることなく、軽量性能をだし、形状の回復性に優れた性能を持つことができるとともに、表面繊維の割繊、ミクロファイバー化が容易になる。
25≦(sm/S)×100≦65
(s/S)×100≦5
s:中空繊維断面の中空部1個の平均面積
m:中空繊維断面の中空部の個数
S:中空繊維断面の外周で囲まれた面積
【0013】
すなわち、1本の繊維に同じ(sm/S)が25の総中空率を持つ繊維であっても中空部が1個(繊維断面中1個の中空率(s/S)が25%)である場合と、3個(繊維断面中1個の中空率(s/S)が8.3%)である場合、5個(繊維断面中1個の中空率(s/S)が5%)である場合、10個(繊維断面中1個の中空率(s/S)が2.5%)である場合では、使用時の屈曲による中空部の扁平化、または破壊度が大きく異なり、中空部1個あたりの面積(s/S)を5%以下で分散させることで、屈曲時の中空部の扁平化、破裂が極度に減少し回復性能に優れたものとなるとともに、表面の中空繊維の割繊、ミクロファイバー化との両立が可能になるため好ましい。
また1個の中空部分が繊維中に占める面積が少なすぎると、屈曲時の角度が大きくなった時、中空部が潰れてしまい、また軽量性能を維持するため中空部数を多くすると繊維物性の低下を招く。また、中空部が5個に満たない場合には、割繊によるミクロファイバー化が難しくなり、更に軽量性との両立をし難い傾向がある。そして中空部が50個を超えると極度に繊維物性が低下する傾向にある。従って、一個の中空率(s/S)は好ましくは1〜4%であり、繊維中の中空部数は5個である必要があり、50個以下にすることが好ましい。
【0014】
基体層の中空繊維の繊度は6デシテックス以下である必要があり、好ましくは4デシテックス以下である。人工皮革などの繊維質シート製品では、一般的に繊維の太さが細いほど地合いがよく柔軟な製品が得られるが、本発明の中空繊維においても6デシテックスを超える場合には基体の風合いが硬くゴワゴワとした触感が強調され適当でない。また太さが細すぎると基体中の繊維が過密充填になるので、中空繊維は本発明の軽量化を達成する点で2.0デシテックス以上が好ましい。
【0015】
本発明のスエード調人工皮革は、3次元絡合して形成された中空繊維からなる基体層の少なくとも片面、特に好ましくは表面において、該中空繊維が2本以上に割繊されてフィブリル化して枝分かれした極細繊維からなる立毛を有する。
該極細繊維は中空繊維が割繊されてフィブリル化して得られるものであるから、その細さは中空繊維の太さや繊維中の中空部の数や、中空のサイズと関係する。本発明では、このような中空繊維の非中空部がフィブリル化して得られるもので、同じフィブリルが得られることは少ないが、中空繊維が2本以上に割繊された後の繊維断面の最大径は6μm以下であることがスエード調外観の高級感を出すために必要である。好ましくは、4μm以下である。
なお、本発明の中空繊維が2本以上に割繊された後の繊維断面の最大径とは、フィブリル化後の繊維断面それぞれの面積からそれらの平均面積を求めた後、円の面積とした場合の該円の直径と定義する。
【0016】
中空繊維の繊度が大きい場合は、基体表面に発生させるフィブリル繊維の比重が小さく、中空部の数および中空率が少ないと太い繊度にフィブリル化し表面ライティングを悪くする傾向にあるため中空繊維の繊度は6デシテックス以下であることが必要であり、2〜4デシテックスが好ましい。中空部の数は10〜40個、総中空率は40〜50%が表面のライティングを美しくする点で効果的である。
【0017】
基体層の表面の中空繊維を割繊、フィブリル化するには、サンドペーパーまたは針布でバフィングして表面に繊維立毛を形成しながらフィブリル化する。繊維立毛は均一でスエード調のライティングのある優美な外観のものが好ましい。このため、使用するペーパーは目の細かいもの、特に240番以上であることが好ましい。極細繊維の立毛の立毛長はバフィング時の接触圧力および回転数で調整する。あるいは、研磨用サンドの粒子条件を設定することで達成できる。
【0018】
基体層の表面の繊維立毛状態すなわち繊維立毛長はその製品の用途および要求される外観によって変わるが、通常繊度の太いものは長めに、また繊度の細いものは短くするのが、表面のライティングを美しくする点で効果的である。
横断面の最大径が6μm以下の細い繊維に割繊、フィブリル化、起毛し、繊維長を短くする場合は、繊維の根元を止めてからバフする方法が好ましい。繊維の根元を止めるには、基体を構成する高分子弾性体と親和性のある溶剤を塗布するのが好ましい。高分子弾性体と親和性のある溶剤とは、高分子弾性体を溶解または膨潤させる溶剤であり、この溶剤としては、たとえば該高分子弾性体がポリウレタンの場合、ジメチルホルムアミド、ジメチルスルホオキシド、テトラヒドロフラン、シクロヘキサノンなどの単独溶剤または2種以上の混合溶剤が挙げられる。
【0019】
本発明の中空部発生型繊維には例えばシリコン系などの油剤を繊維に付与するのが好ましい。その油剤の種類としては、繊維間の摩擦を下げる効果のあるポリオルガノシロキサンや各種の変性されたシリコン系の油剤、および繊維間をまとめ対金属間の摩擦を下げる効果のある鉱物油系の油剤、その他帯電防止剤等の公知の油剤を繊維の特質を考慮しながらブレンドして付与する。付与する工程としては繊維の紡糸後、捲縮前、捲縮後のいずれでもよい。特にバフィング工程でフィブリル化しにくい繊維には鉱物油系、フィブリル化し易い繊維にはシリコン系を多くブレンドすると、フィブリル状態を調整し易い傾向にある。
【0020】
中空部発生型繊維のステープルに本発明を損なわない範囲内で極細繊維発生型繊維を混綿してもよい。極細繊維のポリマーは本発明の中空繊維と同質の方が同染色工程で処理できるので好ましく、また極細繊維を発生さす際に除去するポリマーも中空部発生型繊維の島成分と同質のポリマーが、処理工程上好ましい。 該ステープルはブレンダーなど公知の方法で混綿、開繊する。続いて公知の方法でカード、ウェッバーを通してランダムウェッブまたはクロスラップウェッブとし、これらのウェッブを積層する。
【0021】
次に該ウェブを公知の方法で三次元絡合し不織布とする。例えば本発明におけるニードルパンチのフェルト針は公知の物が用いられるが、ウェッブの厚さ方向への交絡を確実に行うためには、繊維切れの起きにくい1バーブ針が好適に用いられる。また不織布の表面の比重を上げるためには3バーブ、6バーブ、9バーブ等の多バーブの針が使用できる。目的によってこれらの針を組み合わせて良い。
【0022】
ニードルパンチ工程におけるパンチ数は使用する針の形状や、ウェッブの厚みにより異なるが、一般に200〜2500パンチ/cm2の範囲で設定される。一般的に中空部発生型繊維のニードルパンチにおいては、ニードルパンチ条件が強すぎる場合には中空部発生型繊維の切断や繊維割れがおこり、絡合が向上せず、またニードルパンチ条件が弱すぎる場合には厚み方向に並ぶ繊維数の不足をまねき絡合が向上しない。
【0023】
ニードルパンチされた不織布は次に表面を平滑化し、厚みを規制するため、厚さ方向にプレスする。プレスの方法は、複数の加熱ロール間を通す方法、予熱した不織布を冷却ロール間に通す方法等従来公知の方法が利用でき、後処理の割繊立毛化を損なわない範囲において中空部発生型繊維中の海成分などの融点成分の溶融・圧着により、より不織布の平滑化を達成することが出来る。なおこの工程の際に、テンションやプレス等による工程の形態変化を抑制する目的でポリビニルアルコールやデンプン、樹脂エマルジョン等のバインダーを添加することは差し支えない。プレスすることにより不織布の厚みが5〜25%減少する程度のプレス条件が好ましい。
【0024】
表面を平滑化した不織布に次に高分子弾性体の溶液または分散液を含浸し、凝固させる。高分子弾性体としては、従来から皮革様シートの製造に用いられている樹脂が好適に用いられる。すなわち、ポリウレタン系樹脂、ポリ塩化ビニル樹脂、ポリアクリル酸系樹脂、ポリアミノ酸系樹脂、シリコン系樹脂、およびこれらの共重合、これらの混合物等が好適である。これらの樹脂は、有機溶剤溶液または水系エマルジョンとして前記不織布に含浸した後、湿式または、乾式法により凝固ゲル化させる。
【0025】
高分子弾性体の溶液または分散液を含浸凝固させた繊維質基体は、次に、中空部を有する繊維および高分子弾性体の非溶剤であり、中空部発生型繊維の中空部を構成する1成分(例えば島成分)の溶剤または分解剤である液により該成分を溶解または分解除去することにより、5〜50個の中空部を有する6.0デシテックス以下の繊維の絡合不織布と高分子弾性体からなる人工皮革基体を得る。
【0026】
人工皮革基体の厚みは、用途に応じて任意に選択でき、特に限定されるものではないが、好ましくは0.3〜3mm、特に好ましくはスポーツ靴分野においては0.7〜1.8mmの範囲である。また5個以上の中空部を有する繊維からなる繊維質材料と高分子弾性体との量比としては、質量比で35:65〜65:35が好ましい。この範囲を外れると繊維と弾性重合体とのバランスが低下する傾向にあり、製品としての充実感や柔軟性が得られ難くなる。
【0027】
この基体層を前述した方法で少なくとも片面をバフィング処理し所望のフィブリル化繊維とした繊維立毛面を形成させる。得られたスエード調人工皮革は、公知の方法にて染色処理することも可能である。
次に染色したスエード調繊維質基体に対して、もみ、柔軟化処理、ブラッシングなどの仕上げ処理を行うことにより、例えば、比重が0.3g/cm3以下、表面摩擦堅牢度(マーチンデール5万回後の摩耗減量)70mg以下、剥離強力が7kg/2.5cm以上、厚み1mmあたりの引裂強力が4kg以上という機械物性に優れ、優美な外観であり、かつ軽量なスエード調人工皮革が得られる。
【0028】
【実施例】
次に本発明を具体的に実施例で説明するが、本発明はこれらの実施例に限定されるものではない。なお、実施例中の部及び%はことわりのない限り質量に関するものである。以下の実施例および比較例において比重の測定、機械的物性その他の評価は以下の方法に従った。
【0029】
[マーチンデール法の摩耗減量の測定]
JIS L 1096(6.17.5E法 マーチンデール法)にて測定。押圧荷重12kPa(gf/cm2)、摩耗回数5万回、測定数4回の平均値で表す。
【0030】
[人工皮革基体の剥離強力測定方法]
表面を削った巾2.5cmのゴム板に接着剤を均一に塗布し、100℃2分熱処理した後、たて方向23cm、巾2.5cmの試験片を貼り合わせる。貼り合わせた試験片を2〜4kg/cm2圧力でプレスし、室温にて1昼夜放置する。貼り合わせた試験片のゴム板先端部を一方のチャックに、サンプル先端部を他方のチャックに挟む。引張試験機にて速度100mm/分でゴム板とサンプル接着部分の剥離強力を測定、記録する。得られたSS曲線から剥離強力の平坦な部分の平均値を求める。試験片3個の平均値で表す。
【0031】
[人工皮革基体の引裂強力測定方法]
たて10cm×よこ4cmの試験片を切り取り、短辺の中央に辺と直角に5cmの切れ目をいれ、各舌片をチャックに挟み引張試験機で100mm/分の速度で引裂く。引裂最大荷重を求め、あらかじめ求めた試験片の厚みで除し試験片3個の平均値で表す。
【0032】
[比重の測定]
人工皮革基体の単位面積あたりの質量(g/cm2)を厚み(cm)で除した数字を比重(g/cm3)とする。
【0033】
[繊維の横断面における中空部の占める面積の測定方法]
電子顕微鏡にて基体中の多孔中空孔繊維断面を2000倍で撮影し、コンピュータに取り込んだ画像を画像解析用ソフトで解析し、前記したような方法で繊維断面積全体に対する中空部の面積の比を計算で求めた。
【0034】
実施例1
2基のエクストルーダ溶融系で溶融したポリマー流を多芯鞘型複合紡糸装置を用いて、芯鞘型部分の芯成分がエチレン単位を8モル%含有し、重合度が380、鹸化度が98モル%である水溶性かつ熱可塑性の変性ポリビニルアルコール、鞘成分がポリエステルとし、芯部/鞘部=40/60、島数15の海島型繊維からなる中空部発生型繊維を紡糸し、単糸デシテックスが、14デシテックスの未延伸糸を得た。この未延伸糸を60℃の温水中で3倍に延伸、シリコン系の油剤を付与し、さらにクリンプ、カットし、3.5デシテックス、カット長さ51mmの中空部発生型繊維のステープルを得た。
【0035】
このステープルをカードに通し、クロスラッパー方式によりウエッブとし、積層した。次に針に1箇所のバーブのついたフェルト針を用いて1200P/cm2の針刺し比重でニードルパンチして目付290g/m2の不織布を得た。この不織布にポリビニールアルコールの水溶液を固形分で8%/不織布となるように含浸し、140℃で乾燥後、160℃の加熱ロールでプレスして厚さ85%にし、表面の平滑な厚み1.6mm、比重0.25の不織布を得た。その後に13%のポリウレタンのジメチルホルムアミド(DMF)溶液を含浸し、DMF水溶液中に浸漬して凝固、湯洗した後、基体を95℃の温水で30分間液流染色機で処理し、厚み1.1mm、目付290g/m2、比重0.263の中空部を有するポリエステル繊維とポリウレタンからなる人工皮革用基体を得た。
【0036】
この繊維質シートの一面に200メッシュのグラビアロールを使用して、DMFとシクロヘキサノンの50対50混合溶剤を18g/m2塗布し、乾燥した。この混合溶剤塗布面を粒度400番のサンドペーパーでバフィングを行い、表面の繊維を起毛して、中空繊維が割繊された繊維からなる極細繊維立毛が形成された立毛繊維質シートを得た。
次に高圧液流染色機を用いて濃い茶色の分散染料により130℃の温水で60分間染色し温水洗浄後、還元処理、酸化処理、中和処理後さらに温水洗浄した後乾燥することによって深みのある色合いで優美な外観であり、かつ軽量なスエード調人工皮革を得た。
【0037】
基体中の繊維とポリウレタンの質量比を測定したところ40/60であった。またこの基体中の繊維の中空部を有するポリエステル繊維は15の中空部を有し、中空繊維の横断面中に占める島成分(中空発生部)の総面積比率(sm/S)は40%であり、1個の中空率(s/S)は2.5%であった。
また、表面のフィブリル化繊維を電子顕微鏡で観察すると最大径が3μmで1本の中空繊維が約15本以上割繊されていた。この基体の厚みは1.0mm、比重0.26と非常に軽く、また剥離強力は9.0kg/2.5cm、引裂強力は5kgあり、また表面強度もマーチンデール5万回後の摩耗減量が50mgと非常に強く、軽く、柔軟なものであり、カーシート、インテリア用およびスポーツシューズ用として極めて優れたものであった。
【0038】
実施例2
実施例1の中空部発生型繊維の島数を64個とし、以降は実施例1と同様の操作を行い人工皮革基体を得た。この基体の中空部を有するポリエステル繊維は64個の中空部を有し、中空繊維の横断面中に占める島成分(中空発生部)の総面積比率(sm/S)は40%であり1個の中空率(s/S)は0.6%であった。
またこの基体の厚みは1.0mm比重0.26と非常に軽く、また表面のフィブリル化繊維を電子顕微鏡で観察すると平均2、5μmと細く表面のラィティングおよび表面のタッチも良好であったが、剥離強力5.0kg/2.5cm、引裂強力3kgと強度面で若干劣るものであったが通常の使用に耐えうるものであった。
【0039】
比較例1
実施例1の中空部発生型繊維の島数を3個とし、以降は実施例1と同様の操作を行い人工皮革基体を得た。この基体の中空部を有するポリエステル繊維は3個の中空部を有し、中空繊維の横断面中に占める島成分(中空発生部)の総面積比率(sm/S)は40%であり1個の中空率(s/S)は13.3%であった。またこの基体の厚みは1.0mmで比重0.26と非常に軽く、また離強力9.0kg/2.5cm、あり、表面強度もマーチンデール5万回で45mgと非常に強く、軽く、柔軟なもであったが、表面のフィブリル化繊維を電子顕微鏡で観察すると最大径が7μmあり表面のラィティングに乏しく、表面のタッチ感もゴワゴワした悪いものであった。
【0040】
【発明の効果】
本発明によればカーシート、インテリア、スポーツシューズ等の用途に耐えうる機械的物性を持ち、軽量で柔軟なスエード調人工皮革基体が得られるものである。また本発明により得られた人工皮革基体の表面層に皮革様フィルムの接着や樹脂エマルジョン、樹脂溶液、溶融樹脂のコート、グラビア、エンボス、等を組み合わせて仕上げを行い銀付調人工皮革に仕上げることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lightweight and flexible suede-like artificial leather having a very good color development and appearance, excellent mechanical properties, and a method for producing the same.
[0002]
[Prior art]
In various fields of artificial leather, lightweight, flexible products with excellent mechanical properties are demanded. Conventionally, it has been known that a non-woven fabric is formed using a multi-component fiber having a sea-island structure from which sea components can be eluted, for example, a fiber having a sea-island structure in which the sea component is made of polyethylene, and is used as an artificial leather. Such a sea-island structure fiber is obtained by removing sea components in any process until it becomes a final product, thereby obtaining a very fine fiber. Such products have a unique texture of fine fibers and a good suede appearance, and have a certain reputation in the market. However, an increase in specific gravity due to a decrease in thickness as a sheet at the time of forming ultrafine fibers is unavoidable, and it does not have light weight performance.
Further, mixing different types of fibers according to the purpose to form an entangled nonwoven fabric is a conventional method. There are entangled bodies in which two or more kinds of webs and sheets are laminated and / or mixed and entangled with each other, and a method of impregnating and solidifying these entangled bodies with a polymer elastic body solution (for example, see Patent Document 1). . Some of them are leather-like and have excellent mechanical properties, but they do not have good suede appearance and light weight performance.
Further, polyester and nylon hollow fibers are generally used for clothing products and the like from the viewpoints of light weight and heat retention. In the field of synthetic leather and artificial leather, there are synthetic leathers that are lightweight and have good breathability using hollow fibers (see, for example, Patent Document 2 and Patent Document 3). In addition, there is a synthetic leather in which minute hollow particles are mixed to reduce weight and improve heat retention (see, for example, Patent Document 4).
The technology to reduce the weight by using fibers with a hollow structure in these materials for synthetic leather and artificial leather is known, but the appearance as suede is insufficient, and the light weight and necessary mechanical performance are also achieved. Even if it has, the flexibility and surface appearance that are strongly required in recent years are insufficient, and not all of them are combined.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 48-11925 (2nd page)
[Patent Document 2]
JP 47-28104 A (2nd page)
[Patent Document 3]
Japanese Patent Laid-Open No. 50-5502 (first page)
[Patent Document 4]
JP-A-1-292188 (page 2)
[0004]
[Problems to be solved by the invention]
In each field of artificial leather, a substrate having a thickness of 0.5 to 1.3 mm is generally used. Within this range of thickness, there is a demand for flexible products that are lighter and have excellent mechanical properties. Especially in suede-like artificial leather, they have excellent mechanical properties and light and flexible suede. Therefore, an artificial leather substrate that satisfies all of these requirements has not been developed yet.
As described above, in each field of artificial leather, an improvement in luxury is demanded, and among them, a high-quality appearance and lightweight performance are most strongly desired. On the other hand, it is very important to combine mechanical properties according to the application and light and excellent appearance as a product.
[0005]
As a measure for solving the problem, there is known a method of increasing the ratio of components made of multi-component fibers that can be made ultrafine by extraction or the like, for example, from sea-island structure fiber sheets by extraction or the like. And the thickness is reduced by the press treatment, the weight cannot be reduced, and the mechanical properties are insufficient. In addition, the method of reducing the fiber amount itself of the artificial leather product can reduce the weight, but there is a problem that physical properties are insufficient.
Moreover, although the method of using these hollow fibers as a base material for artificial leather using the bulk of staples of hollow fibers can certainly achieve weight reduction, it is inevitably necessary to form a hollow in the fibers. The fiber decitex becomes large and the surface is not smooth. Especially, the appearance as a suede application cannot be secured, and the texture is not flexible.
The object of the present invention is to solve such problems and to provide a suede-like artificial leather that is light and flexible, has excellent color development and appearance, is excellent in mechanical properties, and is excellent in mechanical properties.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors have conducted intensive research, and as a result, three-dimensionally entangled fibers having 5 or more hollow portions in a fiber cross section of 6 dtex or less while satisfying specific conditions. It has been found that by using a non-woven fabric, it is possible to make a suede-like artificial leather that has a very good appearance and is lightweight and flexible.
That is, the present invention provides a nonwoven fabric in which hollow fibers having a single fiber fineness of 6 dtex or less having 5 or more hollow portions are three-dimensionally entangled, and at least one surface of a substrate in which the nonwoven fabric is impregnated with a polymer elastic body. A suede-like artificial leather characterized by the presence of napped portions made of ultrafine fibers having a maximum diameter of 6 μm or less formed by splitting the hollow fibers into two or more fibers, preferably, the cross-sectional state of the hollow fibers is The suede-like artificial leather according to claim 1, which satisfies the following formula.
25 ≦ (sm / S) × 100 ≦ 65
(S / S) × 100 ≦ 5
s: Average area of one hollow part of the hollow fiber cross section
m: The number of hollow portions of the hollow fiber cross section
S: Area surrounded by the outer periphery of the cross section of the hollow fiber
Furthermore, the suede-like artificial leather of the present invention can be produced by sequentially performing the following steps (1) to (4).
(1) The process of manufacturing a nonwoven fabric from the composite fiber which produces | generates the hollow fiber of the single fiber fineness 6 decitex or less which has a 5 or more hollow part,
(2) impregnating a non-woven fabric with a polymer elastic body,
(3) A step of generating a hollow fiber having 5 or more hollow portions by performing a treatment for generating a hollow portion from the composite fiber,
(4) A step of splitting at least one hollow fiber into two or more, making the maximum cross-sectional diameter 6 μm or less, and forming raised fibers.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the fiber of the present invention, the fiber having 5 or more hollow portions in the cross section of the fiber is a method of mixing two polymers at a predetermined mixing ratio and melting and spinning them in the same melt system, or a polymer constituting an island component. And sea component polymer are melted in separate melt systems and spun at the spinning head to repeat the joining and splitting multiple times to form a mixed system of both, or to form the fiber shape with a spinneret structure. Then, it is obtained by removing island components from so-called sea-island type fibers that are joined and spun. In the present invention, in the chip blend method in which two kinds of polymers are mixed at a predetermined mixing ratio and melted and spun in the same melt system, the island component unit to be removed has a small diameter, and is difficult to remove. The diameter of the island state and the distance between the islands become irregular, and the small part between the islands is in a state where the hollow part and the hollow part after the island removal are close to each other, and the part is crushed and flattened or broken easily, as a hollow part No effect.
In the present invention, the melt is melted in separate melt systems, and the method of spinning by joining and dividing at the spinning head a plurality of times to form a mixed system of the two, or the two are defined by the spinneret structure and the fiber shape is joined. The spinning method is suitable in that the island diameter and the distance between the islands that become hollow portions are likely to be uniform.
[0008]
It is preferable that the total area ratio (sm / S) of the island component (hollow generation | occurrence | production part) which occupies in the cross section of the hollow fiber of this invention is 25 <= (sm / S) * 100 <= 65.
In order to obtain such a hollow fiber, it is necessary to manufacture a composite fiber having a hollow portion generating fiber form. The form of the hollow part generation type fiber is generally a sea-island type composite fiber, and as a method of obtaining ultrafine fibers, it is a sea-island structure fiber from which sea components can be eluted, and then the sea components are extracted and removed. A method of obtaining ultrafine fibers has been used. In this invention, it is set as the sea-island type fiber from which an island component can be eluted by this method, and then the island component is extracted and removed to form a fiber having a hollow portion. However, the island component is surrounded by a continuous-phase sea component. Therefore, since it is difficult to remove the island component, it is important to pay attention to the solubility and decomposability with the constituent sea component polymer, particularly in selecting the island component polymer.
[0009]
The island component (hollow portion generation) polymer of the hollow portion generating fiber of the present invention has a higher melt viscosity than the sea component polymer, and has different solubility and decomposability with the sea component, so that the island component polymer is dissolved and removed. A polymer having a high solubility in a solvent or a decomposing agent used in the above and a low compatibility with a sea component polymer is preferable. In particular, when removing an island component from sea-island type fibers, a solvent used for removing the island component polymer. Alternatively, it is necessary to select one having high solubility in the decomposition agent. For example, polyethylene, modified polyethylene, polystyrene, modified polyester, water-soluble polyester copolymer, water-soluble and thermoplastic modified polyvinyl alcohol, and the like are preferably used.
Examples of the island component to be removed in the present invention include water-soluble and thermoplastic modified polyvinyl which contains 5 to 10 mol% of ethylene units, has a polymerization degree of 200 to 500 and a saponification degree of 90 to 99 mol%. Alcohol has a property of easily dissolving in hot water at 50 to 100 ° C., and is particularly preferable not only from the viewpoint of quality but also from the viewpoint of process design considering the environment.
[0010]
In addition, the polymer constituting the fiber having a hollow part is a component that has fiber forming ability during melt spinning and is not dissolved or decomposed and removed by a solvent or a decomposing agent for generating the hollow part, for example, polyethylene terephthalate. Talay Polyester polymers typified by polybutylene terephthalate, etc., and copolymers based on these, polyamide polymers typified by 6-nylon, 66-nylon, etc., and copolymers based on this, etc. However, these polymers may be not only a single polymer but also a mixture of two or more components, and may contain various known additives such as pigment particles and ultraviolet absorbers. .
[0011]
The important point in the present invention is that the area (s) occupied by one hollow part in the cross section of the fiber is (s / S) × 100 ≦ 5 with respect to the area (S) surrounded by the outer periphery of the cross section of the hollow fiber. It is preferable that if it exceeds 5, the tension of the island part removal process, the crushing of the hollow part of the fiber cross section tends to be prominent due to the pressing process, and in the product, the hollow part is crushed during bending and compression, There is a tendency to deform easily. In addition, if the area of one island part (hollow part) in the fiber is too small, the hollow part is removed even though the island component is removed by the tension and pressing process when the island component generating the hollow part is removed. Is preferably 2 or more, because it is easy to prevent crushing.
Moreover, it is preferable that the total area ratio (sm / S) of the island component (hollow generation | occurrence | production part) which occupies in the cross section of the hollow fiber of the fineness 6 decitex or less is 25 <= (sm / S) * 100 <= 65. When the area ratio of the island component is less than 25, not only the effect of weight reduction is insufficient, but also the wall thickness of the medium space increases when splitting the hollow fibers on the surface with buffing to make a suede-like artificial leather. Therefore, it becomes difficult to split. In addition, if it exceeds 65, the wall thickness of the intermediate space after the island part removal becomes thin, so that the multi-hollow fiber on the surface is split by buffing and is easily converted into microfiber, but depending on the process tension and press processing process The hollow portion of the fiber cross section is crushed significantly, the specific gravity of the substrate is increased, and it is difficult to obtain a lightweight substrate.
In general, the thickness of the island portion is preferably in the range of 2.5 to 8.0 μm from the viewpoint of the shape stability of the fiber having the hollow portion after removal of the island component.
Moreover, since the hollow ratio differs depending on the sea-island volume ratio of the sea part that becomes the hollow fiber and the island part that generates the hollow part, and the form maintainability of the sea component when the island part is removed, it is preferable to appropriately combine them. In general, when the sea ratio is small, or when the island fineness is too small, the hollow portion is crushed significantly when the island components are removed, and splitting of the surface fibers tends to be difficult.
[0012]
In the present invention, the hollow portion is crushed and flattened or broken by bending when used as a product by satisfying both the area occupied by one hollow part in the cross section of the fiber and the following formula of the total area of the hollow part Therefore, it is possible to achieve light weight performance and excellent shape recovery performance, and to easily split the surface fibers into microfibers.
25 ≦ (sm / S) × 100 ≦ 65
(S / S) × 100 ≦ 5
s: Average area of one hollow part of the hollow fiber cross section
m: The number of hollow portions of the hollow fiber cross section
S: Area surrounded by the outer periphery of the cross section of the hollow fiber
[0013]
That is, even if the same fiber (sm / S) has a total hollowness of 25, one hollow part (one hollowness (s / S) in the fiber cross section is 25%) In some cases, and 3 (one hollow ratio (s / S) in the fiber cross section is 8.3%), five (one hollow ratio (s / S) in the fiber cross section is 5%). In the case of 10 (one hollow ratio (s / S) in the fiber cross section is 2.5%), the hollow portion is flattened by bending during use, or the degree of fracture is greatly different. By dispersing the area per part (s / S) at 5% or less, flattening and rupturing of the hollow part at the time of bending are extremely reduced and the recovery performance is excellent, and the hollow fiber on the surface It is preferable because it is possible to achieve both split fiber and microfiber.
Also, if the area occupied by one hollow part in the fiber is too small, the hollow part will be crushed when the angle at the time of bending is increased, and if the number of hollow parts is increased in order to maintain lightweight performance, the fiber physical properties will deteriorate. Invite. In addition, when the number of hollow portions is less than 5, it becomes difficult to make microfibers by splitting, and it tends to be difficult to achieve both lightness and lightness. And when a hollow part exceeds 50 pieces, it exists in the tendency for a fiber physical property to fall extremely. Accordingly, the single hollow ratio (s / S) is preferably 1 to 4%, and the number of hollow portions in the fiber needs to be 5, and is preferably 50 or less.
[0014]
The fineness of the hollow fiber of the base layer needs to be 6 dtex or less, and preferably 4 dtex or less. In the fiber sheet product such as artificial leather, generally, the finer the fiber thickness, the better the texture and the more flexible product can be obtained. However, even in the hollow fiber of the present invention, the texture of the substrate is hard when it exceeds 6 dtex. The tactile sensation is emphasized and is not appropriate. Further, if the thickness is too thin, the fibers in the substrate are densely packed, so that the hollow fibers are preferably 2.0 dtex or more in terms of achieving the weight reduction of the present invention.
[0015]
In the suede-like artificial leather of the present invention, at least one side, particularly preferably the surface, of a base layer composed of hollow fibers formed by three-dimensional entanglement, the hollow fibers are split into two or more fibers to form fibrils and branches. Napped fibers made of ultrafine fibers.
Since the ultrafine fibers are obtained by splitting hollow fibers into fibrils, the fineness is related to the thickness of the hollow fibers, the number of hollow portions in the fibers, and the hollow size. In the present invention, the non-hollow portion of such a hollow fiber is obtained by fibrillation, and the same fibril is rarely obtained, but the maximum diameter of the fiber cross section after the hollow fiber is split into two or more fibers Is 6μm The following is necessary to give a high-class feeling of suede-like appearance. Preferably, 4μm It is as follows.
The maximum diameter of the fiber cross section after the hollow fiber of the present invention has been split into two or more fibers is the area of the circle after obtaining the average area from the area of each fiber cross section after fibrillation. It is defined as the diameter of the circle in the case.
[0016]
When the fineness of the hollow fiber is large, the specific gravity of the fibril fiber generated on the surface of the substrate is small, and if the number of hollow parts and the hollowness ratio are small, the fineness of the hollow fiber tends to fibrillate and deteriorate the surface lighting. It needs to be 6 dtex or less, and 2 to 4 dtex is preferable. The number of hollow portions is 10 to 40, and the total hollow ratio is 40 to 50%, which is effective in that the surface lighting is beautiful.
[0017]
In order to split and fibrillate the hollow fibers on the surface of the base layer, fibrillation is performed while buffing with sandpaper or a needle cloth to form fiber napping on the surface. The fiber napping preferably has an elegant appearance with uniform and suede-like lighting. For this reason, it is preferable that the paper to be used is a fine paper, especially 240 or more. The length of the nap of the extra fine fiber is adjusted by the contact pressure and the number of rotations during buffing. Alternatively, it can be achieved by setting the particle condition of the polishing sand.
[0018]
The fiber napping state of the surface of the substrate layer, i.e., the fiber nap length, varies depending on the use of the product and the required appearance, but usually the thicker ones are longer and the shorter ones are shorter. It is effective in making it beautiful.
In the case of splitting, fibrillating, raising, and shortening the fiber length to a thin fiber having a maximum cross-sectional diameter of 6 μm or less, a method of buffing after stopping the fiber base is preferable. In order to stop the base of the fiber, it is preferable to apply a solvent having an affinity for the elastic polymer constituting the substrate. The solvent having an affinity for the polymer elastic body is a solvent for dissolving or swelling the polymer elastic body. Examples of the solvent include dimethylformamide, dimethyl sulfoxide, tetrahydrofuran when the polymer elastic body is polyurethane. , A single solvent such as cyclohexanone or a mixed solvent of two or more.
[0019]
It is preferable that the hollow part generating fiber of the present invention is provided with, for example, a silicone-based oil agent. The types of oils include polyorganosiloxane, which has the effect of reducing the friction between fibers, various modified silicon-based oils, and the mineral oil-based oils that have the effect of reducing the friction between metals by combining the fibers. In addition, a known oil agent such as an antistatic agent is blended and applied in consideration of the properties of the fiber. The step of imparting may be any of after fiber spinning, before crimping and after crimping. In particular, when a fiber that is difficult to be fibrillated in the buffing process is blended with a mineral oil type and a silicon type is blended with a fiber that is easily fibrillated, the fibril state tends to be easily adjusted.
[0020]
Ultrafine fiber-generating fibers may be blended with the hollow portion-generating fiber staple within a range not impairing the present invention. The polymer of the ultrafine fiber is preferably the same as the hollow fiber of the present invention because it can be processed in the same dyeing process, and the polymer removed when generating the ultrafine fiber is also a polymer of the same quality as the island component of the hollow part-generating fiber, It is preferable in terms of processing steps. The staple is blended and opened by a known method such as a blender. Subsequently, a random web or a cross wrap web is passed through a card and a webb by a known method, and these webs are laminated.
[0021]
Next, the web is three-dimensionally entangled by a known method to obtain a nonwoven fabric. For example, a well-known felt needle is used for the needle punch in the present invention. However, in order to surely entangle the web in the thickness direction, a 1 barb needle that is less likely to cause fiber breakage is preferably used. Moreover, in order to raise the specific gravity of the surface of a nonwoven fabric, the needle | hook of multiple barbs, such as 3 barb, 6 barb, and 9 barb, can be used. These needles may be combined depending on the purpose.
[0022]
The number of punches in the needle punching process varies depending on the shape of the needle used and the thickness of the web, but is generally 200 to 2500 punches / cm. 2 It is set in the range. Generally, in the needle punch of hollow part generation type fiber, when the needle punch condition is too strong, the hollow part generation type fiber is cut or broken, and the entanglement is not improved, and the needle punch condition is too weak. In such a case, the entanglement is not improved due to insufficient number of fibers arranged in the thickness direction.
[0023]
The needle punched nonwoven fabric is then pressed in the thickness direction to smooth the surface and regulate the thickness. As a pressing method, a conventionally known method such as a method of passing between a plurality of heating rolls, a method of passing a preheated nonwoven fabric between cooling rolls, and the like can be used. Smoothening of the nonwoven fabric can be achieved by melting and pressure-bonding the melting point component such as the sea component therein. In this step, it is possible to add a binder such as polyvinyl alcohol, starch, or resin emulsion for the purpose of suppressing a change in the shape of the step due to tension or pressing. Pressing conditions that reduce the thickness of the nonwoven fabric by 5 to 25% by pressing are preferred.
[0024]
The nonwoven fabric having a smooth surface is then impregnated with a solution or dispersion of a polymer elastic body and solidified. As the polymer elastic body, a resin conventionally used for producing a leather-like sheet is preferably used. That is, a polyurethane resin, a polyvinyl chloride resin, a polyacrylic acid resin, a polyamino acid resin, a silicon resin, a copolymer thereof, a mixture thereof, and the like are preferable. These resins are impregnated into the nonwoven fabric as an organic solvent solution or an aqueous emulsion, and then solidified and gelled by a wet or dry method.
[0025]
The fibrous base material impregnated and solidified with the solution or dispersion of the polymer elastic body is then a fiber having a hollow part and a non-solvent of the polymer elastic body, and constitutes a hollow part of the hollow part generating fiber 1 By dissolving or decomposing and removing the component with a liquid that is a solvent or decomposing agent of the component (for example, island component), the entangled non-woven fabric of the fiber of 6.0 decitex or less having 5 to 50 hollow portions and polymer elasticity An artificial leather substrate consisting of a body is obtained.
[0026]
The thickness of the artificial leather substrate can be arbitrarily selected according to the use and is not particularly limited, but is preferably 0.3 to 3 mm, particularly preferably in the range of 0.7 to 1.8 mm in the field of sports shoes. It is. Further, the mass ratio of the fibrous material composed of fibers having five or more hollow portions and the polymer elastic body is preferably 35:65 to 65:35 in mass ratio. Outside this range, the balance between the fiber and the elastic polymer tends to decrease, and it becomes difficult to obtain a sense of fulfillment and flexibility as a product.
[0027]
The base layer is buffed on at least one side by the above-described method to form a fiber raised surface having a desired fibrillated fiber. The obtained suede-like artificial leather can be dyed by a known method.
Next, the dyed suede-like fibrous substrate is subjected to finishing treatment such as firping, softening treatment, and brushing, for example, a specific gravity of 0.3 g / cm. 3 Surface friction fastness (weight loss after 50,000 cycles of Martindale) is 70 mg or less, peel strength is 7 kg / 2.5 cm or more, and tear strength per 1 mm thickness is 4 kg or more. A lightweight, suede-like artificial leather can be obtained.
[0028]
【Example】
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In addition, unless otherwise indicated, the part and% in an Example are related with mass. In the following examples and comparative examples, specific gravity measurement, mechanical properties and other evaluations were performed according to the following methods.
[0029]
[Measurement of wear loss by Martindale method]
Measured with JIS L 1096 (6.17.5E method Martindale method). Press load 12 kPa (gf / cm 2 ), Expressed as an average value of 50,000 wears and 4 measurements.
[0030]
[Method of measuring peel strength of artificial leather substrate]
An adhesive is evenly applied to a rubber plate having a width of 2.5 cm whose surface has been cut and heat-treated at 100 ° C. for 2 minutes, and then a test piece having a length of 23 cm and a width of 2.5 cm is bonded. 2 to 4 kg / cm 2 Press with pressure and leave at room temperature for 1 day. The rubber plate tip of the bonded test piece is sandwiched between one chuck and the sample tip is sandwiched between the other chuck. The peel strength between the rubber plate and the sample adhesion portion is measured and recorded with a tensile tester at a speed of 100 mm / min. From the obtained SS curve, the average value of the flat part of the peel strength is obtained. Expressed as the average value of three specimens.
[0031]
[Method of measuring tear strength of artificial leather base]
A test piece of 10 cm long × 4 cm wide is cut out, a 5 cm cut is made in the center of the short side at right angles to the side, each tongue piece is sandwiched between chucks, and teared at a speed of 100 mm / min with a tensile tester. The maximum tearing load is obtained and divided by the thickness of the test piece obtained in advance, and is expressed as an average value of three test pieces.
[0032]
[Specific gravity measurement]
Mass per unit area of artificial leather substrate (g / cm 2 ) Divided by thickness (cm), specific gravity (g / cm 3 ).
[0033]
[Measurement method of area occupied by hollow portion in cross section of fiber]
The cross section of the hollow hollow fiber in the substrate was photographed with an electron microscope at a magnification of 2000, the image taken in the computer was analyzed with image analysis software, and the ratio of the area of the hollow portion to the entire fiber cross section by the method described above Was calculated.
[0034]
Example 1
Using a multi-core sheath type composite spinning device, a polymer stream melted by two extruder melt systems contains 8 mol% of ethylene units in the core component of the core-sheath type portion, the degree of polymerization is 380, and the degree of saponification is 98 mol. % Of water-soluble and thermoplastic modified polyvinyl alcohol, the sheath component is polyester, the core portion / sheath portion = 40/60, and hollow portion-generating fibers made of sea-island type fibers with 15 islands are spun and single yarn decitex However, an undrawn yarn of 14 dtex was obtained. This unstretched yarn was stretched 3 times in warm water at 60 ° C., and a silicone-based oil agent was applied, and further crimped and cut to obtain hollow portion generating fiber staples of 3.5 dtex and a cut length of 51 mm. .
[0035]
The staple was passed through a card, made into a web by a cross wrapper method, and laminated. Next, using a felt needle with one barb on the needle, 1200 P / cm 2 Needle punch with a needle stick specific gravity of 290g / m 2 A non-woven fabric was obtained. This nonwoven fabric is impregnated with an aqueous solution of polyvinyl alcohol so that the solid content becomes 8% / nonwoven fabric, dried at 140 ° C., and then pressed with a heating roll at 160 ° C. to a thickness of 85%. A nonwoven fabric having a thickness of 0.6 mm and a specific gravity of 0.25 was obtained. Thereafter, it was impregnated with a 13% polyurethane dimethylformamide (DMF) solution, dipped in an aqueous DMF solution, solidified and washed with hot water, and then the substrate was treated with warm water at 95 ° C. for 30 minutes with a liquid dyeing machine to obtain a thickness of 1 .1mm, basis weight 290g / m 2 A base for artificial leather comprising a polyester fiber having a hollow portion with a specific gravity of 0.263 and polyurethane was obtained.
[0036]
Using a 200 mesh gravure roll on one side of this fiber sheet, a 50:50 mixed solvent of DMF and cyclohexanone was 18 g / m. 2 Applied and dried. The mixed solvent-coated surface was buffed with sandpaper having a particle size of No. 400, and the fibers on the surface were raised to obtain a napped fiber sheet on which ultrafine fiber nappings composed of fibers obtained by splitting hollow fibers were formed.
Next, using a high-pressure liquid dyeing machine, dye it with a dark brown disperse dye for 60 minutes with warm water at 130 ° C., wash with warm water, reduce, oxidize, neutralize, and then wash with warm water and then dry. A suede-like artificial leather with a certain hue and an elegant appearance was obtained.
[0037]
It was 40/60 when the mass ratio of the fiber in a base | substrate and a polyurethane was measured. Further, the polyester fiber having hollow portions of fibers in the substrate has 15 hollow portions, and the total area ratio (sm / S) of island components (hollow generation portions) in the cross section of the hollow fibers is 40%. Yes, the single hollowness (s / S) was 2.5%.
When the fibrillated fibers on the surface were observed with an electron microscope, the maximum diameter was 3 μm, and about 15 or more hollow fibers were split. The substrate has a very light thickness of 1.0 mm and a specific gravity of 0.26, a peel strength of 9.0 kg / 2.5 cm, a tear strength of 5 kg, and a surface strength of less than 50,000 cycles of Martindale. It was very strong at 50 mg, light and flexible, and extremely excellent for car seats, interiors and sports shoes.
[0038]
Example 2
The number of islands of the hollow part-generating fiber of Example 1 was set to 64, and thereafter, the same operation as in Example 1 was performed to obtain an artificial leather base. The polyester fiber having the hollow portion of the substrate has 64 hollow portions, and the total area ratio (sm / S) of the island component (hollow generation portion) in the cross section of the hollow fiber is 40%, one piece. The hollowness (s / S) was 0.6%.
Further, the thickness of the substrate was very light as 1.0 mm specific gravity 0.26, and when the surface fibrillated fiber was observed with an electron microscope, the average was 2, 5 μm, and the surface lighting and surface touch were good. Although the peel strength was 5.0 kg / 2.5 cm and the tear strength was 3 kg, the strength was slightly inferior, but it could withstand normal use.
[0039]
Comparative Example 1
The number of islands of the hollow part generating fiber of Example 1 was set to 3, and thereafter, the same operation as in Example 1 was performed to obtain an artificial leather base. The polyester fiber having the hollow portion of the substrate has three hollow portions, and the total area ratio (sm / S) of the island component (hollow generation portion) in the cross section of the hollow fiber is 40%, one piece. The hollowness (s / S) of the product was 13.3%. The thickness of the substrate is 1.0mm and the specific gravity is 0.26, and the peel strength is 9.0kg / 2.5cm. The surface strength is 45mg at 50,000 times in Martindale, light and flexible. However, when the fibrillated fiber on the surface was observed with an electron microscope, the maximum diameter was 7 μm, surface lighting was poor, and the touch feeling on the surface was also very bad.
[0040]
【The invention's effect】
According to the present invention, a lightweight and flexible suede-like artificial leather substrate having mechanical properties that can withstand uses such as car seats, interiors, and sports shoes can be obtained. In addition, the surface layer of the artificial leather substrate obtained by the present invention is finished by combining leather-like film adhesion, resin emulsion, resin solution, melted resin coating, gravure, embossing, etc., and finishing with silver-finished artificial leather Can do.
Claims (3)
25≦(sm/S)×100≦65
(s/S)×100≦5
s:中空繊維断面の中空部1個の平均面積
m:中空繊維断面の中空部の個数
S:中空繊維断面の外周で囲まれた面積The suede-like artificial leather according to claim 1, wherein a cross-sectional state of the hollow fiber satisfies the following formula.
25 ≦ (sm / S) × 100 ≦ 65
(S / S) × 100 ≦ 5
s: Average area of one hollow part of the hollow fiber cross section m: Number of hollow parts of the hollow fiber cross section S: Area surrounded by the outer periphery of the hollow fiber cross section
(1)5個以上の中空部を有する単繊維繊度6デシテックス以下の中空繊維を発生させる複合繊維より不織布を製造する工程、
(2)不織布に高分子弾性体を含浸させる工程、
(3)複合繊維から中空部を発生させる処理を行い、5個以上の中空部を有する中空繊維を発生させる工程、
(4)少なくとも片面の中空繊維を2個以上に割繊し、横断面の最大径を6μm以下に極細繊維化し、立毛を形成させる工程、A method for producing a suede-like artificial leather, which is performed in the following order: (1) (2) (3) (4) or (1) (3) (2) (4).
(1) The process of manufacturing a nonwoven fabric from the composite fiber which produces | generates the hollow fiber of the single fiber fineness 6 decitex or less which has a 5 or more hollow part,
(2) impregnating a non-woven fabric with a polymer elastic body,
(3) A step of generating a hollow fiber having 5 or more hollow portions by performing a treatment for generating a hollow portion from the composite fiber,
(4) splitting at least one hollow fiber into two or more, making the maximum cross-sectional diameter 6 μm or less, and forming raised fibers,
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JP5443296B2 (en) * | 2010-07-30 | 2014-03-19 | 株式会社クラレ | Non-woven fabric and method for producing base material for artificial leather |
JP6623646B2 (en) * | 2015-09-29 | 2019-12-25 | 東レ株式会社 | Sheet |
KR102620337B1 (en) * | 2017-09-22 | 2024-01-02 | 주식회사 쿠라레 | Napped Artificial Leather |
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