JP4390302B2 - Non-woven fabric for molding having biodegradability, method for producing the same, and container-shaped product using the nonwoven fabric - Google Patents
Non-woven fabric for molding having biodegradability, method for producing the same, and container-shaped product using the nonwoven fabric Download PDFInfo
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- JP4390302B2 JP4390302B2 JP30465298A JP30465298A JP4390302B2 JP 4390302 B2 JP4390302 B2 JP 4390302B2 JP 30465298 A JP30465298 A JP 30465298A JP 30465298 A JP30465298 A JP 30465298A JP 4390302 B2 JP4390302 B2 JP 4390302B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
- Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics
Description
【０００１】
【発明の属する技術分野】
本発明は、深絞り成型に有用な生分解性を有する成型用不織布、その製造方法、同不織布を用いてなる容器形状品に関するものである。
【０００２】
【従来の技術】
この種の成型用不織布としては、従来から、未延伸ポリエチレンテレフタレート繊維からなる不織布が検討されている（特開昭５１−４０４７５号公報）。しかし、加熱成型時に繊維に熱劣化を生じてその物性が低下するために、十分満足するものが得られていない。
【０００３】
その改良として、半延伸状態のポリエチレンテレフタレート繊維からなる成型用不織布が提案されている。この種の成型性不織布としては、例えば、特開昭５９−１７９８５６号公報、特開昭６０−１９９９５７号公報、特開昭６０−１９９９６１号公報、特開昭６３−１２０１５４号公報などに記載されたものがある。
【０００４】
しかし、これらは、いずれもポリエチレンテレフタレートの単一成分からなる長繊維にて構成されているため、成型時の不織布の延展性、保形性に難点がある。このため、成型直前に基布を予熱したり、成型用金型の加熱温度を高くしたりするなどの処方を取り入れても、成型時の張力が高く、品質の安定した成型物が得られにくいという問題点がある。またヒートシール性に乏しく、このため成型品の適用範囲がきわめて狭くなるという問題点もある。
【０００５】
また、これらの成型品は、使用後自然界に放置されると分解されにくいため、いろいろな問題を生じている。したがって、使用後は土中に埋められたり焼却することが必要となるが、生分解性が低いため、土中に埋められるとその土地の利用に制限が生じている。
【０００６】
このような問題を解決するためには、自然界で分解される素材すなわち生分解性重合体を用いることが考えられる。このような生分解性重合体としては、セルロース、セルロース誘導体、キチン、キトサン等の多糖類、微生物により作られるポリ３−ヒドロキシブチレートや３−ヒドロキシブチレート及び３−ヒドロキシバリレートの共重合体、ポリラクチド、ポリカプロラクトン、ポリブチレンサクシネート、ポリエチレンサクシネート等の脂肪族ポリエステルが知られている。
【０００７】
しかしながら、主に使用されるセルロース系のコットンや再生セルロースは、安価であるが、熱可塑性でないため加工成型ができない。またバインダー繊維としてポリオレフィン、ポリエステル繊維等を用いると、これらの繊維は生分解されにくいため問題となる。微生物により作られるポリ３−ヒドロキシブチレートや３−ヒドロキシブチレート及び３−ヒドロキシバリレートの共重合体は、高価であり用途が限定されるという問題がある。ポリカプロラクトンは、比較的安価な生分解性ポリマーであるが、融点が約６０℃と低く、この温度は流通段階で生じ得る温度であり、耐熱性の点で問題がある。
【０００８】
また、ポリブチレンサクシネート、ポリエチレンサクシネート等は、比較的安価な生分解性ポリマーであり、融点も１００℃を超える温度を有しているが、結晶化が遅く、したがって紡糸時に繊維糸条間で密着が生じやすく、高伸度の繊維や不織布が得られにくいといった問題がある。
【０００９】
【発明が解決しようとする課題】
本発明は、前記問題点を解決し、不織布によって容易に深絞り成型品を得ることができ、しかも成型品にヒートシール性を具備させることができ、また成型品に生分解性を付与できるようにすることを目的とする。
【００１０】
【課題を解決するための手段】
本発明者らは、前記問題点を解決すべく鋭意検討した結果、本発明に到達したものである。すなわち、本発明は、
（１）熱プレス成型により容器状に形成するための成型用不織布であり、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体よりなる２種成分の芯鞘型複合長繊維にて構成され、前記ポリ乳酸とポリ乳酸を主体とする熱可塑性重合体とは融点が１００℃以上であり、鞘成分の融点は芯成分の融点よりも低く、芯成分の複屈折率は０．００１〜０．０１２であり、鞘成分の複屈折率は芯成分の複屈折率よりも低く、前記繊維が集積され、これら繊維相互間が鞘成分の軟化又は溶融によって融着された部分熱融着領域が散点状に設けられ、乾熱９０℃雰囲気下で測定した縦方向破断伸度と横方向破断伸度との和が１８０％以上であることを特徴とする生分解性を有する成型用不織布と、
（２）ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体であって、融点が１００℃以上でありかつ相互に異なる２種のものを用いて、高融点成分を芯部に配しかつ低融点成分を鞘部に配して芯鞘型複合長繊維を紡糸し、得られた糸条を冷却固化させ、次にこの糸条を３０００ｍ／分以下で牽引・開繊して、芯成分の複屈折率が０．００１〜０．０１２であり、かつ鞘成分の複屈折率が芯成分の複屈折率よりも低い芯鞘型複合長繊維からなる繊維ウェブとし、その後、前記鞘成分を軟化させて繊維ウェブの繊維相互間を疑似接着させ、引き続いて前記鞘成分を軟化又は溶融させて繊維相互間を部分熱融着させた融着区域を散点状に形成することで、前記繊維ウェブを一体化することを特徴とする生分解性を有する成型用不織布の製造方法と、
（３）上記成型用不織布のプレス成型により容器状に形成されていることを特徴とする容器形状品と、
（４）上記成型用不織布を予熱して構成繊維の鞘成分を軟化溶融させ、その後に、加熱された金型によって前記成型用不織布をプレス成型することを特徴とする容器形状品の製造方法と、を要旨とするものである。
【００１１】
したがって本発明によれば、ポリ乳酸とポリ乳酸を主体とする熱可塑性重合体との融点が１００℃以上であり、鞘成分の融点は芯成分の融点よりも低く、芯成分の複屈折率は０．００１〜０．０１２であり、鞘成分の複屈折率は芯成分の複屈折率よりも低いという特定の繊維にて形成された不織布を成型用基布として用いるので、低温での深絞り成型性が良好で、かつ熱劣化も生じない。この成型用不織布は、成型加工に伴う温度条件の幅が広く、成型品の品質が極めて安定であり、成型加工における操業上も問題なく、また使用後の廃棄についても生分解性を有しているため問題とならない。特に、生分解性を有する重合体として、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体を用いているため、他の生分解性樹脂に比べ紡糸性が良く、熱安定性も優れているという利点がある。また、芯鞘型複合繊維の鞘成分として、芯成分に比べ融点が低い重合体を配しているので、成型後においてもヒートシール性が良好であり、食品型容器、各種生活資材用通気通液成型容器、自動車内装用各種成型材、育苗用成型容器、インテリア寝装材、フィルターなど汎用に展開できるものである。
【００１２】
【発明の実施の形態】
次に、本発明を詳細に説明する。本発明の生分解性を有する成型用不織布の構成繊維に用いられる重合体は、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体であって、融点が１００℃以上のものである。このようなポリ乳酸としては、ポリ（Ｄ−乳酸）、ポリ（Ｌ−乳酸）、Ｄ−乳酸とＬ−乳酸との共重合体などが挙げられる。このようなポリ乳酸は、乳酸の脱水縮合、又は乳酸の環状エステルの開環重合により得ることができる。ポリ乳酸を主体とする熱可塑性重合体としては、乳酸に、ε−カプロラクトン類、α−ヒドロキシ酪酸、α−ヒドロキシイソ酪酸、α−ヒドロキシ吉草酸等のα−オキシ酸類、エチレングリコール、１，４−ブタンジオール等のグリコール類、コハク酸、セバチン酸等のジカルボン酸類、ラウリン酸、ステアリン酸等の脂肪族カルボン酸類が一種又は二種以上共重合されたものを用いることができる。共重合することにより融点が低下するようにコントロールすることができる。
【００１３】
このように本発明は、生分解性を有する成型用不織布の構成繊維に用いられる重合体として、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体を用いているため、生分解性を有する重合体として上述のポリカプロラクトンやポリブチレンサクシネートやポリエチレンサクシネートなどを用いた場合に比べ、結晶化が速く紡糸性が良いだけでなく、熱安定性にも優れているという利点を得ることができる。
【００１４】
これらポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体の数平均分子量は、１００００以上１５００００以下が好ましい。より好ましくは３００００以上１２００００以下である。１００００以下では、繊維として十分な強力が得られない。また１５００００を超えると紡糸時に高粘度となり、製糸性が低下することになる。
【００１５】
不織布を構成するための、生分解性を有する繊維は、上述のポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体であって、融点が１００℃以上のもの２種よりなる芯鞘型複合長繊維で、繊維の鞘成分の融点は芯成分の融点よりも低く、芯成分の複屈折率が０．００１〜０．０１２であり、鞘成分の複屈折率が芯成分の複屈折率よりも低いものである。この繊維は、伸度が１００％以上である高伸度繊維である。
【００１６】
この繊維を用いて不織布を製造するために熱接着を行い、また熱接着後にある程度の強度を維持するためには、上述のように、この繊維の融点が１００℃以上であることが必要である。また不織布によって容器形状品を成型加工する際に、ある程度の耐熱性が要求される。例えば乾燥工程や成型工程等の加工工程を通過させることや、製品の流通段階において夏期には８０℃程度のところに保管されることなどから、熱安定性を考慮して、製品が軟化したり変形したりするおそれを生じないようにするためには、繊維の融点は少なくとも１００℃が必要となる。
【００１７】
この繊維においては、上述のように芯成分よりも鞘成分の方が融点が低いことが必要であるが、その融点差が５℃以上であることが好適である。このように芯成分と鞘成分との融点差を５℃以上とすることで、後述のように繊維相互間を鞘成分の軟化又は溶融により融着させて不織布化を行うときに、芯成分が溶融せずに繊維形態を維持させることが可能となる。また、この不織布を用いて容器形状品を成型するための熱処理の際に許容される温度範囲を広くすることができ、しかも得られる成型品の品質を安定させることができる。
【００１８】
重合体の複屈折率については、できるだけ配向を抑える観点から、低いことが好ましい。特に芯成分の複屈折率が鞘成分のそれよりも高く、また芯成分の複屈折率が０．００１〜０．０１２であることが必要である。芯成分の複屈折率が０．０１５を超えると、芯成分の軸方向における分子配向の程度が過度となって、成型時の応力に応じきれなくなり、深絞り成型ができなくなる恐れが生じる。一方繊維が全く配向していないと紡糸時に密着が生じたり製糸性が低下することがあるため好ましくない。芯成分の複屈折率の好ましい範囲は、０．００３〜０．０１０、より好ましい範囲は０．００３〜０．００８である。
【００１９】
鞘成分の複屈折率が芯成分のそれよりも低い理由は、分子配向の程度を下げてバインダー特性としての効果をより発揮させるためである。したがって鞘成分の複屈折率は０．０１０以下であることが好適であり、できるかぎり低い方が不織布の接着強力を上げる観点から好ましい。また、鞘成分よりも芯成分の複屈折率を高くすることで、成型時の熱安定性を具備させることができる。しかし、鞘成分の配向が全く進んでいないと、繊維を紡糸した際に糸条間の密着が生じ、開繊性の良い均一な地合いの不織布が得られにくいといった問題が生ずることがあり、好ましくない。したがって、鞘成分の複屈折率のより好ましい範囲は０．００１〜０．０１０である。
【００２０】
この芯鞘型複合長繊維は１００％以上の高伸度であることが必要であり、１００％未満では熱変形を行い難くなって成型加工用に適さない。この繊維の伸度を１００％以上とするためには、繊維の芯成分の複屈折率を０．００１〜０．０１２とするとともに、その鞘成分の複屈折率を０．００１〜０．０１０とすることが必要である。このように繊維の伸度が１００％以上であることで、この繊維によって構成される成型用不織布の９０℃雰囲気下での縦伸度と横伸度の和を１８０％以上にすることができ、またこの不織布によって成型される容器形状品を成型斑のない良好なものとすることができる。
【００２１】
本発明の繊維は、長繊維が最も好ましいが、更にこの繊維を用いて機械的な捲縮を付与した後に適当な長さにカッティングした短繊維、あるいはショートカット綿のいずれでも良く、使用目的によって適宜選択できる。この場合の長繊維は、後述の成型用長繊維不織布に適用したり、あるいは、長繊維を編織物とした後、成型用基布としたりすることが可能である。また、短繊維として形成した場合も、ニードルパンチ短繊維不織布、流体交絡短繊維不織布、エンボス加工不織布等に形成したものを成型加工用基布として展開することが可能である。
【００２２】
芯鞘型複合長繊維の繊度は、３０デニール以下、特に１５デニール以下であることが好ましい。繊度が３０デニールを超えると、長繊維の剛性が高くなって、粗硬感が強くなり、汎用的な用途に使用しにくくなるので好ましくない。また溶融紡糸工程において、紡出糸条の冷却固化に支障を来したりするので好ましくない。
【００２３】
芯鞘型複合長繊維中における、芯成分と鞘成分との重量比は、芯成分１重量部に対して鞘成分が０．１〜５重量部であるのが好ましく、特にこれが０．２〜４重量部であるのが最も好ましい。鞘成分は、融着区域において複合長繊維相互間を融着させる成分であるため、その重量割合が０．１重量部未満になると、繊維同士の融着が不十分となって、不織布の引張強力が低くなる恐れがある。一方鞘成分が５重量部を超えると、融着区域における融着が激しくなって、融着区域中において繊維形態を維持している箇所の割合が少なくなり、このため風合いが硬くなると共に不織布強力が低下する恐れがある。
【００２４】
芯鞘型複合長繊維は、芯成分と鞘成分とが同心であっても構わないし、やや偏心していても特に構わない。なお、上記繊維の芯、鞘成分中には、必要に応じて、艶消し剤、顔料、光安定剤、熱安定剤、酸化防止剤、結晶化促進剤等の各種添加剤を、本発明の目的を損なわない範囲で添加しても良い。
【００２５】
本発明に係る生分解性を有した成型用不織布は、上述のような特定の芯鞘型複合長繊維を構成繊維とするものである。この芯鞘型複合長繊維は、上述のように、芯成分よりも融点の低いポリ乳酸又はポリ乳酸を主体とする熱可塑性重合体であって融点が１００℃以上のものが鞘成分として採用されるものである。この理由は、不織布に低温ヒートシール性を保有するためであり、これにより鞘成分の融点付近の低温で他素材とのヒートシールが可能となるためである。
【００２６】
長繊維不織布中には、芯鞘型複合長繊維相互間が融着された融着区域が、散点状に多数設けられていることが必要である。この融着区域は、熱圧着によって、複合長繊維間が鞘成分の軟化又は溶融によって融着したものである。この鞘成分に対し芯成分は、軟化または溶融は行わずに、繊維形態を維持したままあるいは繊維形態が若干変形した状態で存在する。その散点状に多数設けられた融着区域の形態は、丸型、楕円型、スリット型、十字型、十葉型、三角型、三葉型、四角型、五角型、六角型、八角型、ひし形、Ｔ型、井型、長方形四葉型、五葉型、六葉型、八葉型、卍型等の任意の形態を採用できる。この散点状に多数設けられた融着区域は、圧着面積率で示し測定されるものである。
【００２７】
この圧着面積率は、不織布の全体面積に対する融着区域の面積によって表されるものであるが、３〜５０％であるのが好ましい。圧着面積率が３％未満であると、不織布の柔軟性は向上するが、不織布強力の低下をきたしたり、不織布が擦れた場合に毛羽が発生し易くなったりして、実用面から問題が生じる。また、圧着面積率が５０％を超えると、不織布自体が極めて硬くなり、ハンドリング性が悪くなる。また成型時の応力が高くなり、成型性の観点からも問題となることがある。したがって、圧着面積率は、４〜４０％であることがより好ましい。これらの点圧着部で融着されることによって不織布が形態保持されるのであり、しかも、その他の部分は熱圧着されないため、不織布の曲げ易さ、ハンドリングのよさ、延展性などが付与されるのである。また一つの融着区域の大きさは、０．１〜２．０ｍｍ２程度であることが好ましい。
【００２８】
圧着点の密度は、６〜１５０個／ｃｍ２が好ましい。６個／ｃｍ２未満であると、不織布の柔軟性は向上するが、不織布強力が低下しやすくなったり、また不織布が擦れた場合に毛羽が発生し易くなったりして、実用面から問題が生じる。また、圧着点の密度が１５０個／ｃｍ２を超えると、不織布自体が極めて硬くなり、ハンドリング性が悪くなる。したがって、圧着部の密度が８〜１２０個／ｃｍ２であるのがより好ましい。さらに、圧着点の密度が１０〜１００個／ｃｍ２であるのが最も好ましい。
【００２９】
本発明の成型用不織布を９０℃の乾熱雰囲気下で引張った時の縦方向の破断伸度と横方向の破断伸度との和は、１８０％以上であることが必要である。これは、容器形状品の成型時の基布の延展は縦方向と横方向との両方に寄与し、その結果これらの和が深絞り成型性に良否を与えるためである。そして成型時においては、深絞り比すなわち成型金型における成型品の深さ／相当口径が０．３を超えるものでは、少なくともこの値が１６０％必要となるからである。このように縦方向と横方向との破断伸度の和を１８０％以上とするためには、１００％以上の破断伸度を有する繊維で不織布を構成することが必要である。
本発明は、この深絞り比が０．４以上、好ましくは、０．５以上、最も好ましくは、０．６以上となるような成型が可能な、成型用長繊維不織布やその製造方法などを目指したものである。したがって、本発明の不織布ではこの破断伸度を１８０％以上とするが、好ましくは２００％以上である。
【００３０】
本発明の成型用不織布を９０℃の乾熱雰囲気下で１分間熱処理した際の面積収縮率は、５％以下であることが好適である。この面積収縮率が大き過ぎると、この不織布を用いて容器形状品を成型する直前の予熱の際や、成型時の金型による加熱の際に、不織布が幅入りして、成型金型に見合った目標の成型物が得られなくなる問題や、成型物の品質管理上の問題が生じやすくなる。
【００３１】
本発明の不織布の目付は、特に限定しない。比較的低目付の不織布は、通気性や排水性を重視した分野、例えば排水口フィルターや水切りネット用の成型品の用途に適している。これに対し比較的高目付の不織布は、育苗用ポットやフィルターなどの、広範囲の用途に展開できる。
【００３２】
本発明の容器形状品は、上述の生分解性を有する成型用不織布のプレス成型により容器状に形成されたものである。このプレス成型により形成された容器形状品は、フランジ部と、このフランジ部から３次元方向に突出した容器部とを有するようにするのが好適である。
【００３３】
次に、本発明の生分解性を有する高伸度繊維と、生分解性を有する成型用不織布と、この不織布を用いた容器形状品との製造方法について説明する。なお、本発明の成型用不織布は、他の方法によって製造されたものであっても差し支えない。
【００３４】
本発明の生分解性を有する高伸度繊維は、通常の芯鞘型複合紡糸口金を用いて溶融紡糸し、延伸することなく熱処理することで製造できる。溶融紡糸の温度は、重合体の分子量により異なるが、１５０〜２３０℃とすることが好ましい。熱処理は、余りリラックスを取らず、かつ延伸されない条件下で、鞘成分のガラス転移温度以上かつ融点よりも５０℃低い温度以下で行うのが好適である。そして熱処理した後巻き取ることで、所望の繊維を製造できる。
【００３５】
次に、この生分解性を有する高伸度繊維の詳細な製造方法とともに、本発明の成型用長繊維不織布の製造方法について説明する。この不織布を製造するためには、一般に公知の溶融複合紡糸によるスパンボンド法を適用することができる。すなわち、まずポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体よりなる融点の異なる２種の重合体であって、融点が１００℃以上のものを個別に１５０〜２３０℃で溶融計量し、高融点成分を芯成分とするとともに低融点成分を鞘成分とした芯鞘型複合紡糸を行う。この場合の複合紡糸口金は、通常の芯鞘型複合口金装置のものを使用することができる。引き続いて、紡出された複合繊維を、吹付装置で冷却固化し、さらにエアーサッカーなどの引き取り手段で３０００ｍ／分以下の速度で牽引−開繊させる。
【００３６】
本発明においては、繊維糸条をエアーサッカーなどにより牽引する際には、糸切れが生じない範囲内でできるだけ低紡速にすることが望ましい。なぜなら、このように低紡速とすることで、上述のように芯成分の複屈折率を０．００１〜０．０１２とし、かつ鞘成分の複屈折率を芯成分の複屈折率よりも低くし、繊維の配向つまり結晶化を低め、成型加工の観点から熱変形しやすくさせるためである。
【００３７】
すなわち、低融点成分を鞘成分に用いた芯鞘構造の複合繊維を紡糸する際には、鞘部の成分の紡糸応力が殆ど芯部に集中するため、本発明の場合における芯部の高融点成分は、繊維の配向が鞘部よりも幾分高くなる。これに対し鞘部の低融点成分は、バインダー成分として寄与するため、より配向が少なくてよいのであるが、その通りの性状となる。このようにすることで、芯成分がある程度配向され、かつその周囲を鞘成分が覆った構成となるため、熱劣化をきわめて少なくすることができる。こうするために、上述のように牽引速度は３０００ｍ／分以下とするが、好ましくは２８００ｍ／分以下、より好ましくは２５００ｍ／分以下である。なお、この牽引速度は、１５００ｍ／分程度の低速であっても、繊維及び不織布自体の熱劣化は生じない。
【００３８】
また本発明では、繊維糸条に十分な延伸を施さずに３０００ｍ／分以下で引き取ることで、伸度が１００％以上の高伸度繊維を製造することができる。高伸度繊維を最終製品とする場合は、上述の工程のみで処理を終わる。これに対し成型用の長繊維不織布を製造する場合には、得られた繊維糸条を移動するコンベヤネット上に堆積させて繊維ウェブとする。
【００３９】
本発明では、成型用不織布を製造するに際し、ウェブを形成した後の熱処理によって、芯鞘型複合長繊維の鞘成分を軟化させて繊維ウェブ表層の繊維相互間を疑似接着させる。そして、引き続き熱圧着処理を施して、この芯鞘型複合長繊維の鞘成分の軟化又は溶融によって繊維相互を融着させて、融着区域を散点状に設ける。これにより繊維ウェブを一体化させ、その後に捲取機で巻き取って不織布を製造することができる。
【００４０】
本発明においては、繊維ウェブとした後に、上述のように芯鞘型複合長繊維の鞘成分を軟化させることによって繊維ウェブ表層の繊維相互間を疑似接着させるが、その理由は次の通りである。すなわち、上述のように芯成分の複屈折率が０．００１〜０．０１２であり、鞘成分の複屈折率は芯成分の複屈折率よりも低く、したがってウェブを構成する長繊維自体の結晶化が余り進んでいないことで、熱収縮率が高く、したがって直接に次の熱圧着処理工程に導入すると、ウェブの収縮乱れや大幅な幅入りが生じ、品位の悪い不織布しか得られない、という問題の発生を防ぐためである。また、このようにウェブ表層の繊維相互間を疑似接着させることで、コンベヤネットから熱圧着処理工程へのウェブ移行がスムーズとなり、操業性の向上を図ることが可能となる。
【００４１】
繊維ウェブ表層の繊維相互間を良好に疑似接着させるためには、温度条件を、芯鞘型複合長繊維の鞘成分の融点よりも７０℃低い温度からこの融点よりも３０℃低い温度までの範囲とし、かつ線圧として、０．１〜５ｋｇ／ｃｍ程度の圧力を付与するのが好適である。
【００４２】
次に、この繊維ウェブに対し、芯鞘型複合長繊維の鞘成分の軟化又は溶融によって融着された融着区域を散点状に形成する。その際には、乾式不織布用に一般に使用されている公知の熱エンボス加工機や超音波溶着機などの装置を適用することができる。
【００４３】
例えば、熱エンボス加工機を適用する場合は、加工温度として、一般的には、熱接着成分すなわち鞘成分の融点よりも６０℃低い温度から、この鞘成分の融点よりも５℃低い温度までの範囲を好適に適用できる。鞘成分の融点よりも５℃低い温度を超えた温度とすると、不織布の風合いが硬くなって、ハンドリングが悪く、不織布化のための操業性が低下しやすくなる。また、深絞り成型時の加工性も悪くなりやすくなる。一方、鞘成分の融点よりも６０℃低い温度未満の温度とすると、ウェブが熱圧着されにくく不織布の形態保持性が低下しやすくなる。また熱エンボス加工温度が低いとウェブが彫刻ロールに取られ、操業性良く不織布を製造することができにくくなる。上述のように加工温度はいずれも融点以下の温度であるが、鞘成分の軟化点がその加工温度の範囲内にあり、しかも彫刻ロールの圧着ポイント部で圧力が付与されることにより、確実に融着された状態となる。
【００４４】
また、不織布を製造する上では、この不織布における上述の点圧着の形態すなわち模様が、不織布強力、柔軟性、風合いなどに影響するため重要であり、彫刻ロールの彫刻面積やその形状が一つのポイントとなる。彫刻面積の基準は、熱圧着させる時の圧着面積率で示すことができ、この圧着面積率の好ましい範囲は上述の通りである。
【００４５】
一方、超音波溶着機を用いて融着区域を散点状に形成する際には、彫刻ロールと超音波溶着機構をもった支持体との間に繊維ウェブを通布し、２０ｋＨｚ程度の超音波を発振すればよい。溶着状態を変更する場合には、用いる素材によって超音波の波長を適宜変更すればよい。この場合の線圧としては、熱エンボス加工機の場合とは異なって０．５〜２ｋｇ／ｃｍ程度を用いればよい。また、圧着面積率は４〜５０％が好ましい。この超音波溶着により点圧着を施す方法は、点圧着部以外の繊維が殆ど熱の影響を受けず、風合いが硬くならないため、より好ましい。
【００４６】
本発明においては、このようにして得られた不織布のプレス成型によって、容器形状品が得られる。この容器形状品は、フランジ部と、このフランジ部から３次元方向に突出した容器部とを有するように構成するのが好適である。
【００４７】
このような容器形状品を製造する際には、上述の成型用不織布をまず予熱し、その後に金型を用いてプレス成型する。この予熱によって、互いに接触する繊維の鞘成分どうしを軟化溶融させ、その後の融着によって最終成型品に耐摩耗性や撥水性を付与することができる。また構成繊維の接触部のみが鞘成分どうしによって融着し、接触部以外では融着は生じないため、最終成型品に通気性を付与することもできる。
【００４８】
この予熱の際には、不織布を構成する繊維の鞘成分の軟化温度以上かつ鞘成分が溶融しない温度以下の範囲で処理を行うことで、繊維の鞘成分どうしが良好に融着する。この処理温度が鞘成分の軟化温度未満であると、処理温度が低過ぎて、鞘成分どうしを良好に融着させにくくなる。また鞘成分の溶融温度を越えると、鞘成分のみならず芯成分もが軟化しすぎて、所要の繊維形態を維持させにくくなる。
【００４９】
金型を用いたプレス成型に際し、その金型の温度は、芯成分のガラス転移温度以上かつ鞘成分の融点未満とするのが好適である。金型の温度が芯成分のガラス転移温度よりも低いと、プレス成型性が悪化しやすくなって、所要の深絞り加工を行いにくくなる。反対に金型が鞘成分の融点を越えた温度となると、この鞘成分が溶融してしまって、やはりプレス成型性が悪化しやすくなる。
【００５０】
上述のように、プレス成型を行う材料としての不織布を構成する芯鞘型複合長繊維の芯成分の複屈折率を０．００１〜０．０１２とし、鞘成分の複屈折率を芯成分の複屈折率よりも低くして、繊維の配向すなわち結晶化を低めることで、プレス成型加工の際に熱変形しやすく、したがって良好な成型性を確保することができる。また、上記不織布における乾熱９０℃雰囲気下で測定した縦方向破断伸度と横方向破断伸度との和を１６０％以上としたことで、上述のようにプレス成型時に良好に深絞り加工することができる。さらに、上述のように不織布の構成繊維における芯成分と鞘成分とに融点差をもたせることで、予熱時およびプレス成型時に許容される温度範囲を広くすることができ、また得られる成型品の品質を安定させることができる。
【００５１】
本発明によれば、プレス成型を行う材料としての不織布を構成する芯鞘型複合長繊維の芯成分よりも鞘成分の融点が低いため、プレス成型によって得られた容器形状品にヒートシール性を付与することができる。
【００５２】
また、予熱の段階とプレス成型の段階とにおいて材料としての不織布を加熱するため、構成繊維に熱収縮応力が付与される。このため、得られた容器形状品は、プレス加工されたにもかかわらず、良く目が詰まっており、極端な延伸点が存在しないものとすることができる。したがって、たとえば育苗用の容器に適用した場合には、良好な根切り性を付与することができる。
【００５３】
【実施例】
次に、実施例に基づいて本発明を具体的に説明する。なお、以下の実施例および比較例における各種特性の測定及び評価は、次の方法により実施した。
【００５４】
（１）重合体の融点：パーキンエルマ社製の示差走査型熱量計 ＤＳＣ−２型を用い、昇温速度２０℃／分で測定した融解吸収曲線の極値を与える温度を融点とした。
【００５５】
（２）繊維の芯成分および鞘成分の複屈折率：カールツアイスイエナ社製の干渉顕微鏡 インタファコを用い、封入剤として流動パラフィンとα−ブロムナフタリンとの混合液を用いた。そして、芯部と鞘部との繊維の太さを考慮して繊維を径方向に多層に分割し、表層からの２層の複屈折率の平均値を鞘成分の複屈折率とし、中心部からの２層の複屈折率の平均値を芯成分の複屈折率とした。
【００５６】
（３）繊維の伸度：東洋ボールドウイン社のテンシロンＵＴＭ−４−１−１００を用い、ＪＩＳ Ｌ １０６９にしたがい測定した。
（４）不織布の強力、伸度：東洋ボールドウイン社製の テンシロンＵＴＭ−４−１−１００を用い、ＪＩＳ Ｌ−１０９６に記載のストリップ法にしたがい測定した。すなわち、試料幅５ｃｍ、試料長１５ｃｍの、不織布の縦方向（ＭＤ）の試料と横方向（ＣＤ）の試料とを各々１０個準備し、掴み間隔１０ｃｍ、引張速度１０ｃｍ／分で測定した。その場合の最大の個々の引張強力を平均化した値をもって不織布の引張強力とした。また、その時の破断時の伸度を平均化した値をもって不織布の引張伸度とした。
【００５７】
（５）圧着面積率：不織布の小片を走査型電子顕微鏡で拡大撮影し、最小繰返単位の面積に対する点圧着されている部分の面積の総和の比率を個々に１０回測定したときの平均値で、不織布の圧着面積率を測定した。
【００５８】
（６）不織布の乾熱雰囲気下の面積収縮率：１ｍ×１ｍの大きさの試料の中に、不織布の縦方向が５ｃｍかつ横方向が５ｃｍとなる大きさの枠を４か所記載した。その後、四フッ化エチレン樹脂製のシートのうえに上記試料を置き、熱風循環型熱処理機を用いて、加熱温度９０℃、熱処理時間１分で処理した。その後に放冷し、上記枠の個々の長さを測定し、最初に記載した元の面積から熱処理後の面積を減算して、その差についての元の面積に対する割合を算出して、面積収縮率（％）とした。なお、それらを平均化して、ＨＷＳで示した。
【００５９】
（７）加熱雰囲気下の破断伸度：インストロン社製の加熱雰囲気下引張試験機 ＭＯＤＥＬ１１２２を用い、ＪＩＳ Ｌ−１０９６に記載のストリップ法にしたがい測定した。すなわち、試料幅５ｃｍ、試料長１５ｃｍの、不織布の縦方向（ＭＤ）の試料と横方向（ＣＤ）の試料とを各々１０個準備し、掴み間隔１０ｃｍ、引張速度１０ｃｍ／分、内部の雰囲気温度９０℃、温度保持時間１分で測定した。その時の破断時の伸度を平均化して、不織布の破断伸度とした。
【００６０】
（８）耐摩耗性：縦２０ｃｍ×横３ｃｍの試験片を作成し、摩擦試験機（学振型）を用いて測定した。すなわち、ＪＩＳ Ｌ−０８０３の綿布３号を摩擦布として用いて、荷重５００ｇで１００往復摩擦させた。その後、試験片の外観変化を下記の判定基準に照らして判定し、耐摩耗性を評価した。
【００６１】
３級：全く毛羽立ちがない
２級：少し毛羽立ちがあるが目立たない
１級：毛羽立ちが目立つ
（９）生分解性能：試料片を土中に埋設し、１年、２年及び３年経過後に取り出してその形態を観察し、以下の３段階で評価した。
【００６２】
○：試料片が埋設後２年経過するまでは不織布の形態を保持し、３年経過時点では崩壊していた。
△：試料片が埋設後２年経過するまでに不織布の形態を崩壊させていた。
【００６３】
×：試料片が埋設後３年を経過しても不織布の形態を保持していた。
（１０）成型性：クランプに保持した不織布を鞘成分の融点よりも３０℃高い温度の雰囲気下で１０秒予熱し、次に直ちに加熱金型上に移動させて、容器形状にプレス成型を行った。金型は、上径５０ｍｍφ、下径４０ｍｍφ、深さ４０ｍｍ、底部の隅部の曲率半径３ｍｍであった。またプラグとのクリアランスは０．５ｍｍとし、金型及びプラグの温度は共に７０℃に保持させた。成型後は冷却し、成型物を取り出して深さを測り、金型との深さの比による熱セット率を求め、下記の基準で判定を行った。また成型物の外観検査を行い、下記の基準で成型性の判定を行った。
【００６４】
熱セット率
○：熱セット率が９０％以上
△：熱セット率が７０％以上９０％未満
×：熱セット率が７０％未満
外観検査
◎：成型物に異常が全く認められない
○：成型物はおおむね良好
△：成型斑がややある
×：成型斑が目立つまたは穴あきがある
（実施例１）
鞘成分として融点が１４０℃、ＡＳＴＭ−１２３８Ｅの処方で測定したメルトインデックス値（１９０℃）が３５ｇ／１０分、Ｄ−乳酸／Ｌ−乳酸のモル比（Ｄ／Ｌ比）が４／９６であるポリ乳酸を用い、芯成分として融点が１６８℃、前記メルトインデックス値（１９０℃）が４５ｇ／１０分、Ｄ／Ｌのモル比が１／９９であるポリ乳酸を用いた。これら鞘成分と芯成分とを個別に溶融計量し、通常の丸孔を有する芯鞘型複合紡糸用口金装置（温度２１０℃）を用い、単孔吐出量を０．８８ｇ／分（芯鞘複合比は重量比で１：１）として紡出した。
【００６５】
その後、冷却装置を介してエアーサッカーで紡出糸条を２２００ｍ／分で牽引し、開繊し、移動するコンベヤネット上に堆積して、繊度が３．６デニールの繊維ウェブを得た。この繊維の芯成分の複屈折率は０．０１１、また鞘部の複屈折率は０．００９であった。この繊維ウェブを、加熱回転ロール（温度が８０℃、線圧が０．５ｋｇ／ｃｍ）に接触させ、ウェブの表層を疑似接着させた。その後、圧着面積率が１５％、圧着部密度が２２個／ｃｍ２、圧着部面積が０．７ｍｍ２の彫刻ロールと、フラットロールとを備えた熱エンボス加工機で、加工温度を１１５℃、線圧を４０ｋｇ／ｃｍとして、上述の表層疑似接着ウェブを点圧着した。これにより、目付が約１００ｇ／ｍ２の長繊維不織布を製造した。また、上述のようにして不織布の特性を測定した。
【００６６】
その不織布を成型加工用基布とし、上述の（１０）の条件で成型加工を行って成型性を評価した。以上の結果を表１に示す。
表１から明らかなように、安定した操業状態で長繊維不織布を得ることができた。得られた不織布は、生分解性能及び熱安定性を持ち、成型加工のために必要な基本性能を有するものであって、成型性が良好で深絞り成型に好適であることが分かった。
【００６７】
【表１】
（実施例２）
鞘成分として融点が１２０℃、ＡＳＴＭ−１２３８Ｅの処方で測定したメルトインデックス値（１９０℃）が３５ｇ／１０分、Ｄ−乳酸／Ｌ−乳酸のモル比（Ｄ／Ｌ比）が８／９２であるポリ乳酸を用い、芯成分には実施例１同じ重合体を用いた。また、紡糸時の単孔吐出量を１．７９ｇ／分、紡糸速度を２３００ｍ／分、単糸繊度を７デニール、芯鞘複合比を重量比で芯／鞘：１．５／１とした。そして、それ以外は実施例１と同じ処方として、目付が約１００ｇ／ｍ２の長繊維不織布を製造した。また、その不織布を成型加工用基布とし、成型加工を行って、成型性を評価した。その結果を表１に示す。
【００６９】
表１から明らかなように、得られた成型用不織布は、常温下での引張伸度はやや低いものの、加熱雰囲気下の破断伸度（ＭＤ＋ＣＤ）は高い状態にあるため、成型性が良好であり、深絞り成型に好適であることが分かった。
【００７０】
（比較例１）
紡糸時の単孔吐出量を１．１７ｇ／分、紡糸速度を３５００ｍ／分とした。そして、それ以外は実施例１と同じ処方で、単糸繊度が３デニール、目付が１００ｇ／ｍ２の長繊維不織布を製造し、その特性を測定した。また得られた不織布を成型加工用基布とし、成型加工を行って、成型性を評価した。その結果を表１に示す。
【００７１】
表１から明らかなように、得られた長繊維不織布は、芯部と鞘部の複屈折率が共に比較的高く、加熱雰囲気下の破断伸度（ＭＤ＋ＣＤ）がやや低い状態にあるため、成型性がやや劣る傾向にあった。
【００７２】
（比較例２）
紡糸時の単孔吐出量を１．６０ｇ／分、紡糸速度を４０００ｍ／分とした。そして、それ以外は実施例１と同じ処方で、目付が約１００ｇ／ｍ２の長繊維不織布を製造し、その特性を測定した。また、その不織布を成型加工用基布とし、成型加工を行って、成型性を評価した。その結果を表１に示す。
【００７３】
表１から明らかなように、得られた長繊維不織布は、生分解性能を有し、通常の機械的特性は優れているものの、複屈折率が高過ぎたために加熱雰囲気下の引張伸度（ＭＤ＋ＣＤ）が低く、成型用不織布としては不適であり、成型性が劣っていた。
【００７４】
（比較例３）
通常の単軸型溶融押し出し機を適用し、融点が２５６℃、固有粘度が０．７０（フェノール：テトラクロルエタン＝１：１の混合溶媒中、２０℃で測定）のポリエチレンテレフタレートを２９０℃で溶融計量し、丸孔を有する単一型紡糸用口金装置（温度２９０℃）を用い、単孔吐出量を１．６７ｇ／分として紡出した。その後、冷却装置を介してエアーサッカーで５０００ｍ／分で牽引し、開繊し、移動するコンベヤネット上に堆積して、繊度が３デニールの繊維ウェブを得た。この繊維ウェブを、圧着面積率が１５％、圧着部密度が２２個／ｃｍ２、圧着部面積が０．７ｍｍ２の彫刻ロールと、フラットロールとからなる熱エンボス加工機で、加工温度が２３０℃、線圧が４０ｋｇ／ｃｍの条件で点圧着し、目付が約１００ｇ／ｍ２の長繊維不織布を製造した。またその不織布の特性を測定した。さらに、その不織布を成型加工用基布とし、成型加工を行って、成型性を評価した。その結果を表１に示す。
【００７５】
表１から明らかなように、得られた長繊維不織布は、通常の機械的特性は優れているものの、その構成繊維が本発明品のようなポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体よりなる２種成分の芯鞘型複合長繊維を用いたものではなく、また牽引速度も高過ぎたため、生分解性を有しないばかりか、加熱雰囲気下の引張伸度（ＭＤ＋ＣＤ）が低く、成型用不織布としては不適であり、成型性は著しく劣っていた。
【００７６】
（比較例４）
紡糸時の単孔吐出量を０．８３ｇ／分、紡糸速度を２５００ｍ／分、熱エンボス加工温度を１５０℃とした。そして、それ以外は比較例３と同じ処方で、目付が約１００ｇ／ｍ２の長繊維不織布を製造し、その特性を測定した。また、その不織布を成型加工用基布とし、成型加工を行って、成型性を評価した。その結果を表１に示す。
【００７７】
表１から明らかなように、得られた長繊維不織布は、加熱雰囲気下の引張伸度（ＭＤ＋ＣＤ）が高いものの、その構成繊維は本発明品のようなポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体よりなる２種成分の芯鞘型複合長繊維ではなく、かつ面積収縮率が高いため、生分解性を有しないばかりか、耐摩耗性が悪く、成型用不織布としては不適であり、成型性は著しく劣っていた。
【００７８】
【発明の効果】
本発明によれば、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体よりなる融点が１００℃以上の２種成分の芯鞘型複合長繊維にて構成され、しかも構成繊維の複屈折率すなわち配向度が制御されるとともに、高温での縦方向と横方向との破断伸度の和が１６０％以上であるように構成された特定の長繊維不織布を成型用基布として用いるので、低温での深絞り成型性が良好で、かつ熱劣化も生じない。この成型用不織布は、成型加工に伴う温度条件の幅が広く、成型品の品質が極めて安定であり、成型加工における操業上も問題なく、また使用後の廃棄についても生分解性を有しているため問題とならない。特に、生分解性を有する重合体として、ポリ乳酸及び／又はポリ乳酸を主体とする熱可塑性重合体を用いているため、他の生分解性樹脂に比べ結晶化が速く紡糸性が良いだけでなく、熱安定性も優れているという利点がある。また、芯鞘型複合繊維の鞘成分として、芯成分に比べ融点が低い重合体を配しているので、成型後においてもヒートシール性が良好であり、食品型容器、各種生活資材用通気通液成型容器、自動車内装用各種成型材、育苗用成型容器、インテリア寝装材、フィルターなど汎用に展開できるものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-woven fabric for molding having biodegradability useful for deep drawing, a method for producing the same, and a container-shaped product using the non-woven fabric.
[0002]
[Prior art]
Conventionally, as this type of non-woven fabric for molding, a non-woven fabric made of unstretched polyethylene terephthalate fibers has been studied (Japanese Patent Laid-Open No. 51-40475). However, since the fiber is thermally deteriorated at the time of heat molding and its physical properties are lowered, a sufficiently satisfactory product is not obtained.
[0003]
As an improvement, a non-woven fabric for molding made of a semi-stretched polyethylene terephthalate fiber has been proposed. Examples of this type of non-woven fabric are described in JP-A-59-179856, JP-A-60-199957, JP-A-60-199961, JP-A-63-120154, and the like. There is something.
[0004]
However, since these are all composed of long fibers made of a single component of polyethylene terephthalate, they have difficulties in the spreadability and shape retention of the nonwoven fabric during molding. For this reason, even if a prescription such as preheating the base fabric immediately before molding or increasing the heating temperature of the molding die is incorporated, the molding tension is high and it is difficult to obtain a molded product with stable quality. There is a problem. In addition, the heat sealability is poor, and there is a problem that the application range of the molded product becomes very narrow.
[0005]
In addition, since these molded products are difficult to be decomposed when left in nature after use, various problems have occurred. Therefore, it is necessary to be buried in the soil or incinerated after use, but because of its low biodegradability, use of the land is limited when buried in the soil.
[0006]
In order to solve such a problem, it is conceivable to use a material that is decomposed in nature, that is, a biodegradable polymer. Examples of such biodegradable polymers include cellulose, cellulose derivatives, polysaccharides such as chitin and chitosan, and poly-3-hydroxybutyrate or 3-hydroxybutyrate and 3-hydroxyvalylate copolymers produced by microorganisms. Aliphatic polyesters such as polylactide, polycaprolactone, polybutylene succinate and polyethylene succinate are known.
[0007]
However, mainly used cellulose-based cotton and regenerated cellulose are inexpensive, but cannot be processed and molded because they are not thermoplastic. Further, when polyolefin, polyester fiber or the like is used as the binder fiber, these fibers are difficult to biodegrade, which causes a problem. Poly-3-hydroxybutyrate or a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate produced by microorganisms is expensive and has a problem that its use is limited. Polycaprolactone is a relatively inexpensive biodegradable polymer, but has a melting point as low as about 60 ° C., which is a temperature that can occur in the distribution stage, and is problematic in terms of heat resistance.
[0008]
Polybutylene succinate, polyethylene succinate, and the like are relatively inexpensive biodegradable polymers, and have a melting point exceeding 100 ° C., but are slow to crystallize, and therefore, during fiber spinning, However, there is a problem that adhesion is likely to occur and it is difficult to obtain highly stretched fibers and nonwoven fabrics.
[0009]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, makes it possible to easily obtain a deep-drawn molded product with a nonwoven fabric, and to provide the molded product with heat sealability, and to impart biodegradability to the molded product. The purpose is to.
[0010]
[Means for Solving the Problems]
The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems. That is, the present invention
(1)It is a nonwoven fabric for molding for forming into a container shape by hot press molding,It is composed of two-component core-sheath composite long fibers made of polylactic acid and / or a thermoplastic polymer mainly composed of polylactic acid, and the melting point of the polylactic acid and the thermoplastic polymer mainly composed of polylactic acid is 100 ° C. or higher, the melting point of the sheath component is lower than the melting point of the core component, and the birefringence of the core component is0.001 to 0.012The birefringence of the sheath component is lower than the birefringence of the core component, and the fibers are accumulated, and the partially heat-sealed regions where the fibers are fused together by softening or melting of the sheath component are scattered points. The sum of the longitudinal direction breaking elongation and the transverse direction breaking elongation measured in a dry heat 90 ° C. atmosphere is180% or moreA non-woven fabric for molding having biodegradability characterized by being,
(2) A thermoplastic polymer mainly composed of polylactic acid and / or polylactic acid having a melting point of 100 ° C. or higher and different from each other, and a high melting point component is arranged in the core. In addition, a low melting point component is arranged in the sheath, and a core-sheath type composite continuous fiber is spun, and the obtained yarn is cooled and solidified.3000 m / min or lessThe birefringence of the core component0.001 to 0.012The sheath component has a birefringence lower than that of the core component, and is made of a core-sheath type composite continuous fiber, and then the sheath component is softened to pseudo-bond the fibers of the fiber web to each other. Biodegradation characterized in that the fiber web is integrated by forming a fusion zone in which the sheath component is subsequently softened or melted and partially heat-sealed between the fibers in the form of scattered dots A method for producing a non-woven fabric for molding,
(3) a container-shaped product characterized by being formed into a container shape by press molding of the molding nonwoven fabric;
(4) A method for producing a container-shaped product, wherein the molding nonwoven fabric is preheated to soften and melt the sheath component of the constituent fibers, and then the molding nonwoven fabric is press-molded with a heated mold. Is the gist.
[0011]
Therefore, according to the present invention, the melting point of the polylactic acid and the thermoplastic polymer mainly composed of polylactic acid is 100 ° C. or higher, the melting point of the sheath component is lower than the melting point of the core component, and the birefringence of the core component is0.001 to 0.012Since the non-woven fabric formed of specific fibers whose birefringence of the sheath component is lower than the birefringence of the core component is used as the molding base fabric, the deep drawability at low temperature is good, and There is no thermal degradation. This non-woven fabric for molding has a wide range of temperature conditions associated with the molding process, the quality of the molded product is extremely stable, there is no problem in operation in the molding process, and it is biodegradable when discarded after use. Because it is not a problem. In particular, as a polymer having biodegradability, polylactic acid and / or a thermoplastic polymer mainly composed of polylactic acid is used, so that spinnability is better than other biodegradable resins and thermal stability is also excellent. There is an advantage that. In addition, as the sheath component of the core-sheath type composite fiber, a polymer having a melting point lower than that of the core component is provided. Therefore, the heat sealability is good even after molding. It can be used for general purposes such as liquid molding containers, various molding materials for automobile interiors, molding containers for raising seedlings, interior bedding materials, and filters.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail. The polymer used for the constituent fiber of the non-woven fabric for biodegradability of the present invention is a thermoplastic polymer mainly composed of polylactic acid and / or polylactic acid, and has a melting point of 100 ° C. or higher. Examples of such polylactic acid include poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, and the like. Such polylactic acid can be obtained by dehydration condensation of lactic acid or ring-opening polymerization of a cyclic ester of lactic acid. The thermoplastic polymer mainly composed of polylactic acid includes lactic acid, α-oxy acids such as ε-caprolactones, α-hydroxybutyric acid, α-hydroxyisobutyric acid, α-hydroxyvaleric acid, ethylene glycol, 1, 4 A glycol obtained by copolymerizing a glycol such as butanediol, a dicarboxylic acid such as succinic acid or sebacic acid, or an aliphatic carboxylic acid such as lauric acid or stearic acid may be used. It can control so that melting | fusing point falls by copolymerizing.
[0013]
As described above, the present invention uses polylactic acid and / or a thermoplastic polymer mainly composed of polylactic acid as the polymer used in the constituent fiber of the molding nonwoven fabric having biodegradability. Compared to the case of using the above-mentioned polycaprolactone, polybutylene succinate, polyethylene succinate, etc. as the polymer having, there is an advantage that not only the crystallization is fast and the spinnability is good, but also the thermal stability is excellent. Can do.
[0014]
The number average molecular weight of the polylactic acid and / or thermoplastic polymer mainly composed of polylactic acid is preferably 10,000 or more and 150,000 or less. More preferably, it is 30000 or more and 120,000 or less. If it is 10,000 or less, sufficient strength as a fiber cannot be obtained. On the other hand, if it exceeds 150,000, the viscosity becomes high at the time of spinning and the spinning property is lowered.
[0015]
The fiber having biodegradability for constituting the nonwoven fabric is a core-sheath type comprising the above-mentioned polylactic acid and / or thermoplastic polymer mainly composed of polylactic acid and having two melting points of 100 ° C. or higher. In composite long fiber, the melting point of the sheath component of the fiber is lower than the melting point of the core component, and the birefringence of the core component is0.001 to 0.012And the birefringence of the sheath component is lower than the birefringence of the core component. This fiber is a high elongation fiber having an elongation of 100% or more.
[0016]
In order to perform thermal bonding in order to produce a nonwoven fabric using this fiber, and to maintain a certain level of strength after thermal bonding, the melting point of this fiber needs to be 100 ° C. or higher as described above. . In addition, a certain degree of heat resistance is required when a container-shaped product is molded using a nonwoven fabric. For example, the product may be softened in consideration of thermal stability because it is passed through processing steps such as a drying process and a molding process, and is stored at about 80 ° C. in the summer of the product distribution stage. In order to prevent the possibility of deformation, the melting point of the fiber needs to be at least 100 ° C.
[0017]
In this fiber, the sheath component needs to have a lower melting point than the core component as described above, but the difference in melting point is preferably 5 ° C. or more. In this way, when the melting point difference between the core component and the sheath component is 5 ° C. or more, when the nonwoven fabric is made by fusing the fibers together by softening or melting the sheath component as described later, the core component is It becomes possible to maintain the fiber form without melting. Moreover, the temperature range permitted in the heat treatment for molding the container-shaped product using this nonwoven fabric can be widened, and the quality of the obtained molded product can be stabilized.
[0018]
The birefringence of the polymer is preferably low from the viewpoint of suppressing orientation as much as possible. In particular, the birefringence of the core component is higher than that of the sheath component, and the birefringence of the core component is0.001 to 0.012It is necessary to be. When the birefringence of the core component exceeds 0.015, the degree of molecular orientation in the axial direction of the core component becomes excessive, and it becomes impossible to respond to the stress at the time of molding, and deep drawing may not be possible. On the other hand, if the fibers are not oriented at all, adhesion may occur during spinning, and the spinning performance may be reduced.A preferable range of the birefringence of the core component is 0.003 to 0.010, and a more preferable range is 0.003 to 0.008.
[0019]
The reason why the birefringence of the sheath component is lower than that of the core component is to lower the degree of molecular orientation and to further exert the effect as the binder property. Therefore, the birefringence of the sheath component is0.010The following is preferable, and the lower one is preferable from the viewpoint of increasing the adhesive strength of the nonwoven fabric. Moreover, the thermal stability at the time of shaping | molding can be provided by making birefringence of a core component higher than a sheath component. However, if the sheath component is not oriented at all, adhesion between the yarns may occur when the fiber is spun, which may cause a problem that it is difficult to obtain a non-woven fabric with good spread and uniform texture. Absent. Therefore, the more preferable range of the birefringence of the sheath component is 0.001 to 0.010.
[0020]
This core-sheath type composite continuous fiber needs to have a high elongation of 100% or more. If it is less than 100%, it is difficult to perform thermal deformation and it is not suitable for molding. In order to make the elongation of this fiber 100% or more, the birefringence of the core component of the fiber is 0.001 to 0.001.0.012And the birefringence of the sheath component is 0.001 to 0.001.0.010Is necessary. Thus, when the elongation of the fiber is 100% or more, the sum of the longitudinal elongation and the transverse elongation of the nonwoven fabric for molding constituted by this fiber in a 90 ° C. atmosphere is obtained.180% or moreIn addition, the container-shaped product molded by this nonwoven fabric can be made good without molding spots.
[0021]
The fiber of the present invention is most preferably a long fiber, but it may be either a short fiber cut to an appropriate length after mechanical crimping using this fiber, or a short cut cotton, depending on the purpose of use. You can choose. The long fiber in this case can be applied to a long fiber nonwoven fabric for molding described later, or can be used as a molding base fabric after the long fiber is made into a knitted fabric. In addition, even when formed as a short fiber, a needle punched short fiber nonwoven fabric, a fluid entangled short fiber nonwoven fabric, an embossed nonwoven fabric, or the like can be developed as a molding base fabric.
[0022]
The fineness of the core-sheath type composite continuous fiber is preferably 30 denier or less, particularly preferably 15 denier or less. If the fineness exceeds 30 denier, the rigidity of the long fibers becomes high, the coarseness becomes strong, and it becomes difficult to use for general purposes. Further, in the melt spinning process, it is not preferable because it may hinder the cooling and solidification of the spun yarn.
[0023]
The weight ratio of the core component to the sheath component in the core-sheath type composite continuous fiber is preferably 0.1 to 5 parts by weight of the sheath component with respect to 1 part by weight of the core component, particularly 0.2 to Most preferred is 4 parts by weight. Since the sheath component is a component that fuses the composite long fibers with each other in the fusion zone, when the weight ratio is less than 0.1 parts by weight, the fusion between the fibers becomes insufficient, and the nonwoven fabric is stretched. There is a risk that power will be low. On the other hand, when the sheath component exceeds 5 parts by weight, the fusion in the fusion zone becomes intense, and the proportion of the portion maintaining the fiber form in the fusion zone is reduced. May decrease.
[0024]
In the core-sheath type composite continuous fiber, the core component and the sheath component may be concentric or may be slightly decentered. In the fiber core and sheath components, various additives such as a matting agent, a pigment, a light stabilizer, a heat stabilizer, an antioxidant, and a crystallization accelerator are added according to the present invention. You may add in the range which does not impair the objective.
[0025]
The nonwoven fabric for molding according to the present invention has a specific core-sheath composite long fiber as described above as a constituent fiber. As described above, this core-sheath type composite continuous fiber is a thermoplastic polymer mainly composed of polylactic acid having a melting point lower than that of the core component or polylactic acid, and a melting point of 100 ° C. or more is adopted as the sheath component. Is. This is because the nonwoven fabric has low-temperature heat sealability, which enables heat sealing with other materials at a low temperature near the melting point of the sheath component.
[0026]
In the long-fiber non-woven fabric, it is necessary that a large number of fusion areas in which the core-sheath type composite long fibers are fused together are provided in the form of dots. The fusion zone is a region in which the composite long fibers are fused by softening or melting the sheath component by thermocompression bonding. The core component with respect to the sheath component is not softened or melted, and remains in the fiber form or in a state where the fiber form is slightly deformed. The shape of the fusion area provided in a large number of scattered dots is round, oval, slit, cross, ten-leaf, triangle, trilobe, square, pentagon, hexagon, octagon Any shape such as a rhombus, a T shape, a well shape, a rectangular four leaf shape, a five leaf shape, a six leaf shape, an eight leaf shape, or a saddle shape can be adopted. A large number of fused areas provided in the form of scattered dots are measured by the crimping area ratio.
[0027]
Although this crimping | compression-bonding area ratio is represented by the area of the fusion | melting area with respect to the whole area of a nonwoven fabric, it is preferable that it is 3 to 50%. If the crimping area ratio is less than 3%, the flexibility of the nonwoven fabric is improved. . On the other hand, when the pressure-bonding area ratio exceeds 50%, the nonwoven fabric itself becomes extremely hard and handling properties are deteriorated. Moreover, the stress at the time of shaping | molding becomes high and it may become a problem also from a viewpoint of moldability. Therefore, the crimping area ratio is more preferably 4 to 40%. Since the nonwoven fabric is held in shape by being fused at these point crimping portions, and the other portions are not thermocompression bonded, the nonwoven fabric is easy to bend, easy to handle, spreadability, etc. is there. The size of one fused area is 0.1 to 2.0 mm.2It is preferable that it is a grade.
[0028]
The density of crimping points is 6 to 150 / cm2Is preferred. 6 / cm2If it is less than 1, the flexibility of the nonwoven fabric is improved, but the strength of the nonwoven fabric tends to be reduced, and fluff is likely to occur when the nonwoven fabric is rubbed, causing problems in practical use. Also, the density of crimping points is 150 / cm2If it exceeds 1, the non-woven fabric itself becomes extremely hard and the handling property is deteriorated. Therefore, the density of the crimping part is 8 to 120 pieces / cm.2It is more preferable that Furthermore, the density of the crimping points is 10 to 100 / cm2Most preferably.
[0029]
The sum of the longitudinal breaking elongation and the transverse breaking elongation when the nonwoven fabric for molding of the present invention is pulled in a dry heat atmosphere of 90 ° C. is as follows:180% or moreIt is necessary to be. This is because the extension of the base fabric at the time of molding the container-shaped product contributes to both the vertical direction and the horizontal direction, and as a result, the sum of these gives good or bad deep drawability. At the time of molding, if the deep drawing ratio, that is, the depth / equivalent diameter of the molded product in the molding die exceeds 0.3, at least 160% of this value is required. In this way, the sum of the elongation at break in the vertical and horizontal directions180% or moreIn order to achieve this, it is necessary to form a nonwoven fabric with fibers having a breaking elongation of 100% or more.
The present invention provides a long-fiber nonwoven fabric for molding, a method for producing the same, and the like that can be molded such that the deep drawing ratio is 0.4 or more, preferably 0.5 or more, and most preferably 0.6 or more. Aimed. Therefore, in the nonwoven fabric of the present invention, this breaking elongation is180% or more, but preferably 200% or moreIt is.
[0030]
The area shrinkage rate when the non-woven fabric for molding of the present invention is heat-treated in a dry heat atmosphere at 90 ° C. for 1 minute is preferably 5% or less. If this area shrinkage rate is too large, the nonwoven fabric enters the width during preheating immediately before molding the container-shaped product using this nonwoven fabric, or when heating with the mold during molding, and it matches the molding mold. The problem that the target molded product cannot be obtained and the quality control of the molded product are likely to occur.
[0031]
The basis weight of the nonwoven fabric of the present invention is not particularly limited. The nonwoven fabric having a relatively low basis weight is suitable for a field in which air permeability and drainage are important, for example, a molded product for a drain filter or a draining net. In contrast, a relatively high weight nonwoven fabricNursery potCan be used in a wide range of applications such as filters and filters.
[0032]
The container-shaped product of the present invention is formed into a container shape by press molding of the above-described non-woven fabric for biodegradability. The container-shaped product formed by the press molding preferably has a flange portion and a container portion protruding in a three-dimensional direction from the flange portion.
[0033]
Next, the manufacturing method of the high elongation fiber which has the biodegradability of this invention, the nonwoven fabric for shaping | molding which has biodegradability, and the container shape goods using this nonwoven fabric is demonstrated. The molding nonwoven fabric of the present invention may be manufactured by other methods.
[0034]
The high elongation fiber having biodegradability of the present invention can be produced by melt spinning using a normal core-sheath type composite spinneret and heat-treating without stretching. The melt spinning temperature varies depending on the molecular weight of the polymer, but is preferably 150 to 230 ° C. The heat treatment is preferably performed at a temperature not lower than the glass transition temperature of the sheath component and not higher than 50 ° C. below the melting point under conditions that do not take much relaxation and are not stretched. And a desired fiber can be manufactured by winding up after heat-processing.
[0035]
Next, the manufacturing method of the long fiber nonwoven fabric for shaping | molding of this invention is demonstrated with the detailed manufacturing method of this high elongation fiber which has biodegradability. In order to produce this nonwoven fabric, a generally known spunbond method by melt compound spinning can be applied. That is, first, two types of polymers having different melting points made of polylactic acid and / or thermoplastic polymer mainly composed of polylactic acid and having a melting point of 100 ° C. or higher are individually melt-metered at 150 to 230 ° C. Then, core-sheath type composite spinning is carried out using the high melting point component as the core component and the low melting point component as the sheath component. In this case, the composite spinneret can be an ordinary core-sheath type composite die apparatus. Subsequently, the spun composite fiber is cooled and solidified by a spraying device, and then taken up by air soccer or other take-up means.3000 m / min or lessPull-open at a speed of.
[0036]
In the present invention, when the fiber yarn is pulled by air soccer or the like, it is desirable to make the spinning speed as low as possible within a range where yarn breakage does not occur. Because of this low spinning speed, the birefringence of the core component is reduced as described above.0.001 to 0.012In addition, the birefringence of the sheath component is made lower than the birefringence of the core component, the orientation of the fiber, that is, crystallization is lowered, and thermal deformation is facilitated from the viewpoint of molding.
[0037]
That is, when spinning a composite fiber having a core-sheath structure using a low melting point component as a sheath component, the spinning stress of the component of the sheath portion is mostly concentrated on the core portion, so that the high melting point of the core portion in the case of the present invention The component has a somewhat higher fiber orientation than the sheath. On the other hand, the low melting point component of the sheath part contributes as a binder component, so that the orientation may be less, but the property is as it is. By doing so, the core component is oriented to some extent and the sheath component is covered around the core component, so that thermal degradation can be extremely reduced. To do this, the traction speed isAlthough it is 3000 m / min or less, it is preferably 2800 m / min or less, more preferably 2500 m / min or less.. In addition, even if this pulling speed is a low speed of about 1500 m / min, thermal deterioration of the fiber and the nonwoven fabric itself does not occur.
[0038]
In the present invention, the fiber yarn is not sufficiently stretched.3000 m / min or lessIt is possible to produce a high elongation fiber having an elongation of 100% or more. When a high elongation fiber is used as a final product, the processing is completed only with the above-described steps. On the other hand, when producing a long-fiber nonwoven fabric for molding, the obtained fiber yarn is deposited on a moving conveyor net to form a fiber web.
[0039]
In the present invention, when the nonwoven fabric for molding is manufactured, the sheath component of the core-sheath composite long fiber is softened by heat treatment after forming the web, and the fibers on the surface layer of the fiber web are pseudo-bonded to each other. Subsequently, a thermocompression treatment is performed, and the fibers are fused to each other by softening or melting the sheath component of the core-sheath-type composite long fiber, thereby providing the fused areas in the form of dots. Thereby, a fiber web can be integrated and it can wind up with a winder after that and can manufacture a nonwoven fabric.
[0040]
In the present invention, after forming the fiber web, the sheath component of the core-sheath composite long fiber is softened as described above to pseudo-bond the fibers of the fiber web surface layer for the following reasons. . That is, as described above, the birefringence of the core component is0.001 to 0.012The birefringence of the sheath component is lower than the birefringence of the core component, and therefore, the crystallization of the long fibers constituting the web is not advanced so much that the heat shrinkage rate is high. This is to prevent the occurrence of the problem that when introduced into the thermocompression treatment process, the web contracts and the width is greatly increased, and only a non-woven fabric with poor quality can be obtained. In addition, by pseudo-bonding the fibers on the web surface layer in this manner, the web can be smoothly transferred from the conveyor net to the thermocompression treatment process, and the operability can be improved.
[0041]
In order to achieve good pseudo-adhesion between the fibers of the fiber web surface layer, the temperature condition ranges from a temperature 70 ° C. lower than the melting point of the sheath component of the core-sheath composite long fiber to a temperature 30 ° C. lower than this melting point. In addition, it is preferable to apply a pressure of about 0.1 to 5 kg / cm as the linear pressure.
[0042]
Next, fusion areas fused by the softening or melting of the sheath component of the core-sheath composite long fiber are formed in a dotted shape on the fiber web. In that case, apparatuses, such as a well-known hot embossing machine and an ultrasonic welding machine generally used for dry nonwoven fabrics, can be applied.
[0043]
For example, when a hot embossing machine is applied, the processing temperature is generally from 60 ° C. lower than the melting point of the thermal bonding component, that is, the sheath component, to 5 ° C. lower than the melting point of the sheath component. The range can be suitably applied. If the temperature exceeds a temperature 5 ° C. lower than the melting point of the sheath component, the texture of the nonwoven fabric becomes hard, the handling becomes poor, and the operability for making the nonwoven fabric tends to decrease. Moreover, the workability at the time of deep drawing tends to deteriorate. On the other hand, if the temperature is lower than the temperature 60 ° C. lower than the melting point of the sheath component, the web is difficult to be thermocompression bonded, and the form retainability of the nonwoven fabric tends to decrease. Further, when the heat embossing temperature is low, the web is taken by the engraving roll, and it becomes difficult to manufacture the nonwoven fabric with good operability. As described above, the processing temperatures are all below the melting point, but the softening point of the sheath component is within the processing temperature range, and the pressure is applied at the crimping point portion of the engraving roll, so that It is in a fused state.
[0044]
Also, in the production of non-woven fabrics, the above-mentioned form of point compression in the non-woven fabric, that is, the pattern, is important because it affects the strength, flexibility, texture, etc. of the non-woven fabric. It becomes. The standard of the engraving area can be indicated by a pressure-bonding area ratio when thermocompression bonding is performed, and a preferable range of the pressure-bonding area ratio is as described above.
[0045]
On the other hand, when forming the fusion zone in the form of dots using an ultrasonic welding machine, a fiber web is passed between the engraving roll and a support having an ultrasonic welding mechanism, What is necessary is just to oscillate a sound wave. When the welding state is changed, the wavelength of the ultrasonic wave may be appropriately changed depending on the material to be used. The linear pressure in this case may be about 0.5 to 2 kg / cm, unlike the case of the hot embossing machine. Further, the crimping area ratio is preferably 4 to 50%. This method of performing point bonding by ultrasonic welding is more preferable because fibers other than the point bonding portion are hardly affected by heat and the texture does not become hard.
[0046]
In the present invention, a container-shaped product is obtained by press molding of the nonwoven fabric thus obtained. This container-shaped product is preferably configured to have a flange portion and a container portion protruding in a three-dimensional direction from the flange portion.
[0047]
When manufacturing such a container-shaped product, the above-mentioned non-woven fabric for molding is first preheated and then press-molded using a mold. By this preheating, the sheath components of the fibers that are in contact with each other can be softened and melted, and then the final molded product can be given wear resistance and water repellency by fusion. Further, since only the contact portion of the constituent fibers is fused by the sheath components and no fusion occurs except for the contact portion, it is possible to impart air permeability to the final molded product.
[0048]
In this preheating, the sheath components of the fibers are well fused by performing the treatment in a range not less than the softening temperature of the sheath component of the fibers constituting the nonwoven fabric and not more than the temperature at which the sheath components do not melt. If the treatment temperature is lower than the softening temperature of the sheath component, the treatment temperature is too low and it becomes difficult to fuse the sheath components well together. If the melting temperature of the sheath component is exceeded, not only the sheath component but also the core component will be too soft, making it difficult to maintain the required fiber form.
[0049]
In press molding using a mold, the temperature of the mold is preferably set to be equal to or higher than the glass transition temperature of the core component and lower than the melting point of the sheath component. When the temperature of the mold is lower than the glass transition temperature of the core component, the press moldability is liable to deteriorate and it becomes difficult to perform the required deep drawing. On the contrary, when the temperature of the mold exceeds the melting point of the sheath component, the sheath component is melted, and the press moldability is easily deteriorated.
[0050]
As mentioned above, the birefringence of the core component of the core-sheath type composite continuous fiber constituting the nonwoven fabric as the material for press molding is determined.0.001 to 0.012By making the birefringence of the sheath component lower than the birefringence of the core component and lowering the fiber orientation, that is, crystallization, it is easily deformed by heat during press molding, thus ensuring good moldability. can do. In addition, by making the sum of the longitudinal direction breaking elongation and the transverse direction breaking elongation measured in a dry heat 90 ° C. atmosphere in the non-woven fabric to be 160% or more, as described above, a good deep drawing process is performed at the time of press molding. be able to. Furthermore, by providing a melting point difference between the core component and the sheath component in the constituent fibers of the nonwoven fabric as described above, the temperature range allowed during preheating and press molding can be widened, and the quality of the obtained molded product Can be stabilized.
[0051]
According to the present invention, since the melting point of the sheath component is lower than the core component of the core-sheath type composite continuous fiber constituting the nonwoven fabric as the material for press molding, the container-shaped product obtained by press molding has heat sealability. Can be granted.
[0052]
Moreover, in order to heat the nonwoven fabric as a material in the preheating stage and the press molding stage, heat shrinkage stress is applied to the constituent fibers. For this reason, although the obtained container shape goods are press-processed, they are clogged well and it can be set as the extreme stretch point does not exist. Therefore, for example, when applied to a container for raising seedlings, good root cutting properties can be imparted.
[0053]
【Example】
Next, the present invention will be specifically described based on examples. In addition, measurement and evaluation of various characteristics in the following examples and comparative examples were performed by the following methods.
[0054]
(1) Melting point of polymer: A differential scanning calorimeter manufactured by Perkin Elma Co., Ltd. DSC-2 type was used, and the temperature giving the extreme value of the melting absorption curve measured at a heating rate of 20 ° C./min was defined as the melting point.
[0055]
(2) Birefringence of fiber core component and sheath component: Interferoscope manufactured by Carl Zeiss Jena, Inc. Interfaco was used, and a liquid mixture of liquid paraffin and α-bromonaphthalene was used as an encapsulant. Then, considering the fiber thickness of the core and the sheath, the fiber is divided into multiple layers in the radial direction, and the average birefringence of the two layers from the surface layer is defined as the birefringence of the sheath component, The average value of the birefringence of the two layers was taken as the birefringence of the core component.
[0056]
(3) Fiber elongation: Measured according to JIS L 1069 using Tensilon UTM-4-1-100 manufactured by Toyo Baldwin.
(4) Strength and elongation of nonwoven fabric: Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co. was used and measured according to the strip method described in JIS L-1096. That is, ten samples each of a longitudinal direction (MD) sample and a transverse direction (CD) sample of a nonwoven fabric having a sample width of 5 cm and a sample length of 15 cm were prepared and measured at a gripping interval of 10 cm and a tensile speed of 10 cm / min. The value obtained by averaging the maximum individual tensile strengths in that case was taken as the tensile strength of the nonwoven fabric. Moreover, the value which averaged the elongation at the time of a fracture | rupture at that time was made into the tensile elongation of a nonwoven fabric.
[0057]
(5) Crimp area ratio: An average value obtained by magnifying a small piece of non-woven fabric with a scanning electron microscope and measuring the ratio of the sum of the area of the point-bonded portion to the area of the minimum repeating unit individually 10 times. Then, the crimping area ratio of the nonwoven fabric was measured.
[0058]
(6) Area shrinkage ratio of nonwoven fabric in dry heat atmosphere: In a sample having a size of 1 m × 1 m, four frames having a size in which the longitudinal direction of the nonwoven fabric is 5 cm and the lateral direction is 5 cm are described. Then, the said sample was set | placed on the sheet | seat made from a tetrafluoroethylene resin, and it processed with the heating temperature of 90 degreeC, and heat processing time for 1 minute using the hot-air circulation type heat processing machine. Then, let cool down, measure the individual length of the frame, subtract the area after heat treatment from the original area described first, calculate the ratio of the difference to the original area, area shrinkage rate(%)Was. In addition, they were averaged and indicated by HWS.
[0059]
(7) Elongation at break in heating atmosphere: Measured according to the strip method described in JIS L-1096 using a tensile tester MODEL1122 manufactured by Instron. That is, 10 pieces each of a longitudinal (MD) sample and a transverse (CD) sample of a nonwoven fabric having a sample width of 5 cm and a sample length of 15 cm are prepared, the grip interval is 10 cm, the tensile speed is 10 cm / min, and the internal ambient temperature. The measurement was performed at 90 ° C. and a temperature holding time of 1 minute. The elongation at break at that time was averaged to obtain the elongation at break of the nonwoven fabric.
[0060]
(8) Abrasion resistance: A test piece of 20 cm long × 3 cm wide was prepared and measured using a friction tester (Gakushin type). That is, 100 reciprocating rubs were performed at a load of 500 g using cotton cloth 3 of JIS L-0803 as a friction cloth. Thereafter, the appearance change of the test piece was judged in light of the following judgment criteria, and the wear resistance was evaluated.
[0061]
Grade 3: No fuzz at all
Second grade: Slightly fuzzy but not noticeable
1st grade: Fluff is conspicuous
(9) Biodegradation performance: Sample pieces were embedded in the soil, taken out after 1 year, 2 years and 3 years, and their forms were observed and evaluated in the following three stages.
[0062]
○: The shape of the nonwoven fabric was maintained until 2 years after the sample piece was embedded, and the sample piece had collapsed after 3 years.
(Triangle | delta): The form of the nonwoven fabric was destroyed by two years after the sample piece was embedded.
[0063]
X: The shape of the nonwoven fabric was maintained even after 3 years had passed since the sample piece was embedded.
(10) Moldability: The non-woven fabric held in the clamp is preheated for 10 seconds in an atmosphere at a temperature 30 ° C. higher than the melting point of the sheath component, and then immediately moved onto a heating mold to perform press molding into a container shape. It was. The mold had an upper diameter of 50 mmφ, a lower diameter of 40 mmφ, a depth of 40 mm, and a curvature radius of 3 mm at the bottom corner. The clearance between the plug and the plug was 0.5 mm, and the mold and plug temperature were both maintained at 70 ° C. After molding, it was cooled, the molded product was taken out, the depth was measured, the heat set rate was determined by the ratio of the depth to the mold, and the determination was made according to the following criteria. Further, the appearance of the molded product was inspected, and the moldability was determined according to the following criteria.
[0064]
Heat set rate
○: Heat set rate is 90% or more
Δ: Heat setting rate is 70% or more and less than 90%
X: Heat set rate is less than 70%
Visual inspection
A: No abnormality is observed in the molded product
○: Molding is generally good
Δ: There are some molding spots
X: Molding spots are conspicuous or have holes
Example 1
The melting point is 140 ° C. as the sheath component, the melt index value (190 ° C.) measured by ASTM-1238E is 35 g / 10 minutes, and the molar ratio of D-lactic acid / L-lactic acid (D / L ratio) is 4/96. A polylactic acid was used, and a polylactic acid having a melting point of 168 ° C., a melt index value (190 ° C.) of 45 g / 10 min, and a D / L molar ratio of 1/99 was used as a core component. The sheath component and the core component are melted and measured separately, and a single-sheath discharge rate of 0.88 g / min (core-sheath composite) is used using a core-sheath type composite spinning die having a normal round hole (temperature 210 ° C.). The ratio was spun as 1: 1) by weight.
[0065]
Thereafter, the spun yarn was pulled at 2200 m / min with air soccer through a cooling device, opened, and deposited on a moving conveyor net to obtain a fiber web having a fineness of 3.6 denier. The birefringence of the core component of this fiber was 0.011, and the birefringence of the sheath was 0.009. This fiber web was brought into contact with a heated rotating roll (temperature: 80 ° C., linear pressure: 0.5 kg / cm), and the surface layer of the web was pseudo-bonded. Thereafter, the crimping area ratio is 15%, and the crimping part density is 22 pieces / cm.2, Crimp area is 0.7mm2The surface layer pseudo-adhesive web was subjected to point pressure bonding with a hot embossing machine equipped with a sculpture roll and a flat roll at a processing temperature of 115 ° C. and a linear pressure of 40 kg / cm. As a result, the basis weight is about 100 g / m.2A long fiber nonwoven fabric was produced. Moreover, the characteristic of the nonwoven fabric was measured as mentioned above.
[0066]
The nonwoven fabric was used as a molding base fabric, and molding was performed under the condition (10) described above to evaluate moldability. The results are shown in Table 1.
As is apparent from Table 1, a long fiber nonwoven fabric could be obtained in a stable operating state. The obtained non-woven fabric has biodegradability and thermal stability, has basic performance necessary for molding, and has good moldability and is suitable for deep drawing.
[0067]
[Table 1]
(Example 2)
The melting point is 120 ° C. as the sheath component, the melt index value (190 ° C.) measured by ASTM-1238E is 35 g / 10 minutes, and the molar ratio of D-lactic acid / L-lactic acid (D / L ratio) is 8/92. A certain polylactic acid was used, and the same polymer as in Example 1 was used as the core component. In addition, the single hole discharge rate during spinning was 1.79 g / min, the spinning speed was 2300 m / min, the single yarn fineness was 7 denier, and the core-sheath composite ratio was core / sheath: 1.5 / 1 in weight ratio. Other than that, the basis weight is about 100 g / m as the same formulation as in Example 1.2A long fiber nonwoven fabric was produced. Moreover, the nonwoven fabric was used as a base fabric for molding, and the molding was performed to evaluate the moldability. The results are shown in Table 1.
[0069]
As is apparent from Table 1, the obtained nonwoven fabric for molding had a slightly low tensile elongation at room temperature, but had a high elongation at break (MD + CD) in a heated atmosphere, and therefore had good moldability. It was found that it is suitable for deep drawing.
[0070]
(Comparative Example 1)
The single-hole discharge rate during spinning was 1.17 g / min, and the spinning speed was 3500 m / min. And other than that, it is the same prescription as Example 1, a single yarn fineness is 3 deniers, and a fabric weight is 100 g / m.2The long fiber nonwoven fabric was manufactured and the characteristic was measured. Moreover, the obtained nonwoven fabric was used as a base fabric for molding processing, and molding processing was performed to evaluate moldability. The results are shown in Table 1.
[0071]
As is apparent from Table 1, the obtained long fiber nonwoven fabric has a relatively high birefringence in the core and the sheath, and has a relatively low elongation at break (MD + CD) in a heated atmosphere. Slightly inferiorThere was a trend.
[0072]
(Comparative Example 2)
The single-hole discharge rate during spinning was 1.60 g / min, and the spinning speed was 4000 m / min. And other than that, it is the same prescription as Example 1, and a basis weight is about 100 g / m.2The long fiber nonwoven fabric was manufactured and the characteristic was measured. Moreover, the nonwoven fabric was used as a base fabric for molding, and the molding was performed to evaluate the moldability. The results are shown in Table 1.
[0073]
As is apparent from Table 1, the obtained long fiber nonwoven fabric has biodegradability and is excellent in normal mechanical properties, but the birefringence is too high, so that the tensile elongation in a heated atmosphere ( MD + CD) was low, unsuitable as a non-woven fabric for molding, and the moldability was poor.
[0074]
(Comparative Example 3)
Applying a normal uniaxial melt extruder, polyethylene terephthalate having a melting point of 256 ° C. and an intrinsic viscosity of 0.70 (measured in a mixed solvent of phenol: tetrachloroethane = 1: 1 at 20 ° C.) at 290 ° C. The melt was weighed and spun at a single hole discharge rate of 1.67 g / min using a single-type spinning die having a round hole (temperature: 290 ° C.). After that, it was pulled at 5000 m / min by air soccer through a cooling device, opened, and deposited on a moving conveyor net to obtain a fiber web having a fineness of 3 denier. This fiber web has a crimping area ratio of 15% and a crimping part density of 22 pieces / cm.2, Crimp area is 0.7mm2This is a hot embossing machine consisting of a sculpture roll and a flat roll, and is point-bonded under conditions where the processing temperature is 230 ° C. and the linear pressure is 40 kg / cm, and the basis weight is about 100 g / m2A long fiber nonwoven fabric was produced. Moreover, the characteristic of the nonwoven fabric was measured. Further, the non-woven fabric was used as a base fabric for molding, and molding was performed to evaluate moldability. The results are shown in Table 1.
[0075]
As is clear from Table 1, the obtained long-fiber nonwoven fabric has excellent mechanical properties, but its constituent fibers are thermoplastic such as polylactic acid and / or polylactic acid as in the present invention. Not using two-component core-sheath type composite continuous fiber made of polymer, and the pulling speed was too high, so it not only has no biodegradability but also has a low tensile elongation (MD + CD) in a heated atmosphere. It was unsuitable as a non-woven fabric for molding, and the moldability was extremely inferior.
[0076]
(Comparative Example 4)
The single-hole discharge rate during spinning was 0.83 g / min, the spinning speed was 2500 m / min, and the hot embossing temperature was 150 ° C. And other than thatComparative Example 3The basis weight is about 100 g / m.2The long fiber nonwoven fabric was manufactured and the characteristic was measured. Moreover, the nonwoven fabric was used as a base fabric for molding, and the molding was performed to evaluate the moldability. The results are shown in Table 1.
[0077]
As is clear from Table 1, the obtained long fiber nonwoven fabric has a high tensile elongation (MD + CD) in a heated atmosphere, but its constituent fibers are mainly composed of polylactic acid and / or polylactic acid as in the present invention. It is not a two-component core-sheath type composite long fiber made of thermoplastic polymer, and has a high area shrinkage rate, so it is not only biodegradable but also has poor wear resistance and is not suitable as a nonwoven fabric for molding. Yes, the moldability was remarkably inferior.
[0078]
【The invention's effect】
According to the present invention, it is composed of two-component core-sheath-type composite continuous fibers having a melting point of 100 ° C. or higher and comprising polylactic acid and / or a thermoplastic polymer mainly composed of polylactic acid, and birefringence of the constituent fibers. Since a specific long-fiber nonwoven fabric configured so that the rate, that is, the degree of orientation, is controlled and the sum of the elongation at break in the machine direction and the transverse direction at a high temperature is 160% or more is used as a molding base fabric, Good deep drawability at low temperatures and no thermal degradation. This non-woven fabric for molding has a wide range of temperature conditions associated with the molding process, the quality of the molded product is extremely stable, there is no problem in operation in the molding process, and it is biodegradable when discarded after use. Because it is not a problem. In particular, as a polymer having biodegradability, polylactic acid and / or a thermoplastic polymer mainly composed of polylactic acid is used, so that the crystallization is faster and spinnability is better than other biodegradable resins. There is also an advantage that thermal stability is excellent. In addition, as the sheath component of the core-sheath type composite fiber, a polymer having a melting point lower than that of the core component is provided. Therefore, the heat sealability is good even after molding. It can be used for general purposes such as liquid molding containers, various molding materials for automobile interiors, molding containers for raising seedlings, interior bedding materials, and filters.
Claims (10)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30465298A JP4390302B2 (en) | 1998-10-27 | 1998-10-27 | Non-woven fabric for molding having biodegradability, method for producing the same, and container-shaped product using the nonwoven fabric |
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| Application Number | Priority Date | Filing Date | Title |
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| JP30465298A JP4390302B2 (en) | 1998-10-27 | 1998-10-27 | Non-woven fabric for molding having biodegradability, method for producing the same, and container-shaped product using the nonwoven fabric |
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| JP2000136478A JP2000136478A (en) | 2000-05-16 |
| JP4390302B2 true JP4390302B2 (en) | 2009-12-24 |
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| JP30465298A Expired - Fee Related JP4390302B2 (en) | 1998-10-27 | 1998-10-27 | Non-woven fabric for molding having biodegradability, method for producing the same, and container-shaped product using the nonwoven fabric |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103422252A (en) * | 2013-07-29 | 2013-12-04 | 博爱（中国）膨化芯材有限公司 | Dry paper capable of being degraded completely and preparing technology and application thereof |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100623837B1 (en) * | 2000-05-25 | 2006-09-12 | 에스케이케미칼주식회사 | Method and apparatus for producing thermal-bonded fiber board with high density |
| GB0016116D0 (en) * | 2000-06-30 | 2000-08-23 | Crompton J R Plc | Beverage infusion packages and materials therefor |
| JP2005176616A (en) * | 2003-12-16 | 2005-07-07 | Unitika Ltd | Binding tape |
| JP2011162925A (en) * | 2010-02-15 | 2011-08-25 | Unitika Ltd | Polylactic acid-based filament nonwoven fabric |
| JP6053289B2 (en) * | 2012-01-26 | 2016-12-27 | ユニチカ株式会社 | Polylactic acid long fiber nonwoven fabric |
| FI127679B (en) | 2015-01-29 | 2018-11-30 | Teknologian Tutkimuskeskus Vtt Oy | Thermoplastic fibrous materials and a method of producing the same |
| JP6649016B2 (en) * | 2015-09-11 | 2020-02-19 | 三菱ケミカル株式会社 | Thermoformed article manufacturing method and thermoforming material |
| CA3038791C (en) | 2016-10-14 | 2021-04-06 | Asahi Kasei Kabushiki Kaisha | Biodegradable nonwoven fabric |
| CA3204737A1 (en) | 2021-02-17 | 2022-08-25 | Yuya FUJIMOTO | Biodegradable non-woven fabric and method for producing molded body |
| JP7373005B2 (en) | 2022-03-24 | 2023-11-01 | 東洋紡Ｓｔｃ株式会社 | biodegradable textile products |
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1998
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103422252A (en) * | 2013-07-29 | 2013-12-04 | 博爱（中国）膨化芯材有限公司 | Dry paper capable of being degraded completely and preparing technology and application thereof |
| CN103422252B (en) * | 2013-07-29 | 2016-02-17 | 博爱（中国）膨化芯材有限公司 | One can degradable dry-papermaking and preparation technology thereof and application |
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| JP2000136478A (en) | 2000-05-16 |
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