JP3565755B2 - Method for producing open cell of polyethylene resin - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、無架橋のポリエチレン系樹脂連続気泡体の製造方法に関するものである。
【０００２】
【従来の技術】
従来、ポリエチレン系連続気泡体の製造方法としては、密閉金型中で発泡性架橋性組成物中の発泡剤と架橋剤を部分的に分解させ、常圧下で残存する発泡剤と架橋剤を分解させて独立気泡体を得、次いで得られた独立気泡体を圧縮して独立気泡を破壊する方法が提案されていた（特公昭５９−２３５４５号及び特開昭５６−１４６７３２ 号公報参照）。しかし、このような方法では、加圧された密閉金型中において、加熱により発泡剤及び架橋剤の分解が行なわれ、架橋反応は生じているが、気泡の形成は行なわれておらず、除圧時に初めて発泡することになる。即ち、まず架橋反応を生ぜしめ、しかる後発泡を行なわせる方法を採用しており、独立気泡体の製造段階において、いわゆる先架橋が行なわれているため、気泡膜が強靭なものとなる。従って、独立気泡の連通化が困難であり、連続気泡率１００％又は１００％に近い気泡体を得ることができなかった。
【０００３】
上記問題点を解消するため、本出願人は、エチレン酢酸ビニル共重合体又は低密度ポリエチレンを基材とする発泡性架橋性組成物を所望の形状に加熱整形した後、常圧下にて加熱して架橋剤及び発泡剤を同時進行的に分解させて気泡体を生成させ、次いで機械的変形を加えて気泡を連通化させる方法（特公昭６２−１９２９４号公報、特公平１−４４４９９ 号公報）、重合触媒としてメタロセン化合物を用いて得られたポリエチレン系樹脂を基材とする発泡性架橋性組成物を所望の形状に加熱整形した後、常圧下にて加熱して架橋剤及び発泡剤を同時進行的に分解させて気泡体を生成させ、次いで機械的変形を加えて気泡を連通化させる方法（特開平１１−３１５１６１）を提案した。しかし、前記本出願人が提案した方法は、連続気泡率が１００％又は１００％に近い連続気泡体を製造することができるが、架橋している為、使用後に回収しても再溶融できず、リサイクルに適さないことが欠点であった。
【０００４】
無架橋ポリエチレン系樹脂連続気泡体の製造方法としては、低密度ポリエチレン及び高密度ポリエチレンのメルトインデックス、混合比率、押出温度を特定し揮発性有機液体を混合して押出す方法（特公昭６０−５５２９０号公報）、オレフィン系樹脂にイオン性共重合体と発泡剤とを混合した樹脂組成物を押出し発泡させる方法（特公平３−８３７９号公報）、ポリオレフィン系樹脂に対し、エチレンーメタクリル酸共重合体（アイオノマー樹脂）及び核形成剤、収縮防止剤等からなる樹脂組成物を加熱して軟化、または溶融させた後、揮発性発泡剤を供給混合して得られる組成物を低圧域に押出す方法（特開平１０−２７９７２４号公報）等が提案されている。このような方法によって製造される連続気泡体は、リサイクル性に優れるが、連続気泡率が低く、生物濾過方式合併処理浄化槽の生物濾過槽に充填する担体、フィルター等の用途に不適当であった。
【０００５】
【発明が解決しようとする課題】
従って、本発明の目的は、前記従来技術の欠点を解消し、リサイクル性に優れ、且つ連続気泡率の高いポリエチレン系樹脂連続気泡体の製造方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明の第一の方法は、重合触媒としてメタロセン化合物を用いて得られたポリエチレン系樹脂に、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を添加した発泡性組成物を整形し、次いで常圧下で加熱発泡して発泡体を成形し、該発泡体に機械的変形を加えて気泡を連通化することを特徴とするものである。第一の方法において、ポリエチレン系樹脂の融点は、１００℃以下であることが好ましい。ポリエチレン系樹脂の融点が１００℃を超えると、破泡性が低下する。理由は、樹脂の剛性によるものと推測される。
【０００７】
本発明の第二の方法は、エチレン酢酸ビニル共重合体に、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を添加した発泡性組成物を整形し、次いで常圧下で加熱発泡して発泡体を成形し、該発泡体に機械的変形を加えて気泡を連通化することを特徴とするものである。第二の方法において、エチレン酢酸ビニル共重合体の酢酸ビニル含有量が、５％以上であることが好ましい。酢酸ビニル含有量が５％未満であると、破泡性が低下する。理由は、樹脂の剛性によるものと推測される。
【０００８】
本発明の第一の方法及び第二の方法の常圧発泡において、三次元方向にフリーに発泡させることが好ましく、金型内で発泡の最終段階で加圧状態になると、発泡に支障をきたし、収縮を生じ易い。
【０００９】
本発明は、発泡剤として４，４’―オキシビス（ベンゼンスルホニルヒドラジド）の分解温度が低く、かつ分解速度が速い為、連続気泡を形成し易いことと、発泡剤の分解残渣の保持力向上効果により、無架橋でも高発泡を形成し易いことに着目した。
メタロセン化合物を重合触媒として得られたポリエチレン系樹脂は、エチレンとＣ３ 〜Ｃ１８のαオレフィンとの共重合体から成り、α−オレフィンとしては、例えば、プロピレン、１−ブテン、１−ペンテン、１−ヘキセン、４−メチル−１−ペンテン、及び１−オクテン等が挙げられる。
【００１０】
一般に、メタロセン触媒とは、遷移金属をπ電子系の不飽和化合物で挟んだ構造の化合物であり、本発明では、チタン、ジルコニウム、ニッケル、パラジウム、ハフニウム、白金等の四価の遷移金属に、１または２以上のシクロペンタジエニル環またはその類縁体がリガンド（配位子）として存在する化合物が挙げられる。
リガンドとしては、シクロペンタジエニル環以外には、例えば、シコロペンタジエニルオリゴマー環、インデニル環、炭化水素基や置換炭化水素基或いは炭化水素―置換メタロイド基により置換されたシクロペンタジエニル環又はインデニル環等が挙げられる。このようなリガンド以外にも、例えば、塩素又は臭素の一価のアニオン又はニ価のアニオンキレート、炭化水素基、アルコキシド、アリールアルコキシド、アリールオキシド、アミド、アリールアミド、ホスフィド、アリールホスフィド等が遷移金属に配位結合されていてもよい。
【００１１】
【発明の実施の形態】
以下、本発明に係る連続気泡体の製造方法についてその好適な態様を具体的に説明する。
まず、重合触媒としてメタロセン化合物を用いて得られたポリエチレン系樹脂又は／及びエチレン酢酸ビニル共重合体１００重量部に、発泡剤として４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を、好ましくは、１〜３０重量部、及び必要に応じて充填剤、顔料等を添加し、これを加熱したミキシングロール、加圧式ニーダー、押出機等によって練和する。
【００１２】
本発明においては、使用する組成物の物性の改良、核形成剤としての作用（気泡の均一化、微細化）、脱泡性の向上、あるいは価格の低下を目的として、発泡剤の分解反応に著しい悪影響を与えず、且つ、樹脂を架橋結合しない添加剤（充填剤）、例えば酸化亜鉛、酸化チタン、酸化カルシウム、酸化マグネシウム、酸化ケイ素等の金属酸化物、炭酸マグネシウム、炭酸カルシウム等の炭酸塩、あるいはパルプ等の繊維物質、または各種染料、顔料並びに蛍光物質、その他常用のゴム配合剤等を必要に応じて添加することができる。
上記のように練和して得られた発泡性組成物を金型に仕込み、プレスにて加圧下で樹脂の融点以上に加熱して整形する。この加熱整形は、所望の形状に整形する工程であり、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）は実質的には、分解しない。この加熱整形工程において、非常に微量の発泡剤が初期分解を生じ、整形品を金型から取り出した場合に２倍程度まで膨張しうるが、これは発泡という概念からは程遠く、本発明にとって何ら差し支えない。
【００１３】
上記のようにして整形された発泡性組成物は、次いで、常圧下にて加熱することによって、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を分解する。常圧下での加熱の方法としては、例えば、熱風恒温槽、金属板外表面にヒーターを密着させて加熱するか、あるいは金属板に熱媒の流路を設け、ジャケット方式で蒸気、加熱オイル等によって加熱する方法、オイルバス、メタルバス、ソルトバス等の熱浴がある。
本発明において、常圧発泡は３次元方向にフリーな発泡が好ましく、また、下面には、タルク等の減摩剤を敷くことが、発泡に際し、抵抗が生じない為、好ましい。常圧発泡時の下面は、鉄板、アルミニウム板等の金属板、金属製の網、繊維網、表面をポリテトラフルオロエテレン加工された各種シートが適用できる。加熱温度は、使用する樹脂の種類に応じて好ましくは１４０〜１８０℃、特に好ましくは１４５〜１７５℃の範囲に設定する。加熱時間は、好ましくは５〜４０分、さらに好ましくは１０〜３５分である。４，４’―オキシビス（ベンゼンスルホニルヒドラジド）の分解残渣は、高温下長時間で黒変する為、この発泡条件の範囲より高温、長時間では、得られる気泡体が黒変してしまう。
このようにして、機械的変形を与えることによって容易に破壊しうる気泡膜を有する気泡体が得られる。
【００１４】
以上のようにして得られた気泡体（いわゆる独立気泡体）は、次いで例えば等速二本ロール等により圧縮変形を加えることによって気泡膜は破壊され、気泡が連通化されて連続気泡体が得られる。等速二本ロールの表面に無数の小さい針を設けるか、又は等速二本ロールの前及び／又は後に無数の小さい針を設けたロールを配置して、該気泡体の表面に無数の小孔を開けることによって、気泡の連通化を促進させることができる。
この方法によって得られる連続気泡体は、ＡＳＴＭ Ｄ ２８５６に準拠した空気比較式比重計１０００型（東京サイエンス（株）製）を用いて測定した結果、１００％又は１００％に近い連続気泡率であった。
【００１５】
【実施例】
以下、実施例を示して本発明を更に具体的に説明するが、本発明は下記実施例により何等限定されるものではない。
実施例１
メタロセン触媒を用いて重合されたポリエチレン系樹脂（商品名：カーネルＫＳ２４０，密度（Ｄ）：０．８８０ｇ／ｃｍ３ 、ＭＦＲ： ２．２ｇ／１０分、融点：６０℃、日本ポリケム株式会社製）１００重量部に４，４’―オキシビス（ベンゼンスルホニルヒドラジド）（商品名：ネオセルボン Ｎ＃５０００、分解温度１６４℃、永和化成工業株式会社製）１０重量部から成る組成物を８５℃のミキシングロールにて練和して得られた組成物を、１１０℃に加熱されたプレス内の金型（５ｘ２００ｘ２００ｍｍ）に充填し、上記温度で２分間密閉して加熱し、発泡性シートを整形した。
次いで、得られた発泡性架橋性シートを、タルク粉末を薄く敷いた金属プレート上に置き、１６０℃の循環式エアーオーブン中で２０分間加熱して発泡体を得た。
得られた発泡体をロール間隔２ｍｍに設定した等速二本ロールの間を２回通過させて気泡膜を破壊させ、気泡の連通化を行なった。得られた連通後の連続気泡体は、サイズ：１１ｘ４７０ｘ４７０ｍｍ、見掛け密度０．０７３ｇ／ｃｍ３ 、連続気泡率１００％であり、均一な気泡を有していた。
【００１６】
実施例２
実施例１において、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を２０重量部に変えた以外は、実施例１と同じ配合及び同じ発泡条件で連続気泡体を得た。
得られた連通後の連続気泡体は、サイズ：１２ｘ５５０ｘ５５０ｍｍ、見掛け密度０．０４９ｇ／ｃｍ３ 、連続気泡率１００％であり、略均一な気泡を有していた。
【００１７】
実施例３
実施例１において、ポリエチレン系樹脂を、メタロセン触媒を用いて重合されたポリエチレン系樹脂（商品名：カーネルＫＳ３４０，密度（Ｄ）：０．８８０ｇ／ｃｍ３ 、ＭＦＲ： ３．５ｇ／１０分、融点：６０℃、日本ポリケム株式会社製）に変えた以外は、実施例１と同じ配合及び同じ発泡条件で連続気泡体を得た。
得られた連通後の連続気泡体は、サイズ：１３ｘ４３０ｘ４３０ｍｍ、見掛け密度０．０７１ｇ／ｃｍ３，連続気泡率１００％であり、均一な気泡を有していた。
【００１８】
実施例４
実施例３において、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を２０重量部に変えた以外は、実施例３と同じ配合及び同じ発泡条件で連続気泡体を得た。
得られた連通後の連続気泡体は、サイズ：１４ｘ５２０ｘ５２０ｍｍ、見掛け密度０．０４６ｇ／ｃｍ３ 、連続気泡率１００％であり、略均一な気泡を有していた。
【００１９】
実施例５
実施例１において、樹脂をエチレン酢酸ビニル共重合体（商品名：ノバテックＬＶ５４０，密度０．９４２ｇ／ｃｍ３，ＭＦＲ ２．５ｇ／１０分、融点：８３℃、酢酸ビニル含有量：２０重量％、日本ポリケム株式会社製）に変え、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を２０重量部に変えた以外は、実施例１と同じ配合及び同じ発泡条件で独立気泡体を製造し、実施例１と同じ間隔の等速ロールの間に該独立気泡体を１０回通して連続気泡体を得た。
得られた連通後の連続気泡体は、サイズ：２１ｘ４６０ｘ４６０ｍｍ、見掛け密度０．０４３ｇ／ｃｍ３ 、連続気泡率９５％であり、略均一な気泡を有していた。
【００２０】
比較例１
実施例１において、樹脂を高圧法低密度ポリエチレン（商品名 ノバテックＹＦ−３０、密度０．９２０ｇ／ｃｍ３，ＭＦＲ１．１ｇ／１０分、融点１０９℃、日本ポリケム株式会社製）に変えた以外は、実施例１と同じ配合及び同じ発泡条件で独立気泡体を成形し、ロール間隔４．０ｍｍの等速二本ロールの間を１０回通過させたが、連続気泡率５％で、連通化できなかった。
【００２１】
比較例２
実施例１において、４，４’―オキシビス（ベンゼンスルホニルヒドラジド）の替わりにアゾジカルボンアミドを３．０重量部配合し、活性亜鉛華２．０重量部、ステアリン酸亜鉛１．０重量部を添加した以外は、実施例１と同じ配合及び同じ発泡条件で成形したが、常圧発泡で収縮し、発泡体を得ることができなかった。
【００２２】
【表１】
【表２】
【発明の効果】
上述の様に、本発明によれば、発泡剤として４，４’―オキシビス（ベンゼンスルホニルヒドラジド）を使用し、基材として、メタロセン触媒によって重合された分子量分布がシャープで均一な物性を有するポリエチレン系樹脂又はエチレン酢酸ビニル共重合体を使用することにより、無架橋で連続気泡率の高い連続気泡体を製造することが出来、リサイクル性に優れ、フィルター、前記浄化槽の担体、エアコン内の結露防止材として好適であり、且つ、使用後溶融し樹脂として再利用でき、省資源の面で有用な発明である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a non-crosslinked polyethylene resin open cell.
[0002]
[Prior art]
Conventionally, as a method for producing a polyethylene-based open cell, a foaming agent and a cross-linking agent in an expandable cross-linkable composition are partially decomposed in a closed mold, and the remaining foaming agent and the cross-linking agent are decomposed under normal pressure. A method of breaking closed cells by compressing the obtained closed cells to obtain closed cells has been proposed (see JP-B-59-23545 and JP-A-56-146732). However, in such a method, the foaming agent and the cross-linking agent are decomposed by heating in the pressurized closed mold, and a cross-linking reaction occurs, but no air bubbles are formed and the foaming agent and the cross-linking agent are removed. It will foam only when pressed. That is, a method in which a cross-linking reaction is caused first, followed by foaming, is employed. In the production stage of the closed cell, so-called pre-crosslinking is performed, so that the cell membrane becomes tough. Therefore, it was difficult to make the closed cells open, and it was not possible to obtain a foam having an open cell ratio of 100% or close to 100%.
[0003]
In order to solve the above problems, the present applicant heat-shapes a foamable crosslinkable composition based on an ethylene-vinyl acetate copolymer or a low-density polyethylene into a desired shape, and then heats it under normal pressure. A cross-linking agent and a foaming agent are simultaneously decomposed to form bubbles, and then mechanically deformed to open the bubbles (Japanese Patent Publication Nos. 62-19294 and 1-44499). After heating and shaping a foamable crosslinkable composition based on a polyethylene resin obtained using a metallocene compound as a polymerization catalyst into a desired shape, the mixture is heated under normal pressure to simultaneously form a crosslinking agent and a foaming agent. A method has been proposed in which bubbles are generated by progressively decomposing them and then mechanically deformed to open the bubbles (Japanese Patent Laid-Open No. 11-315161). However, the method proposed by the present applicant can produce an open cell having an open cell ratio of 100% or close to 100%. However, since it is crosslinked, it cannot be melted again even if collected after use. The disadvantage was that it was not suitable for recycling.
[0004]
As a method for producing a non-crosslinked polyethylene resin open cell, there is a method in which a low-density polyethylene and a high-density polyethylene are specified by a melt index, a mixing ratio and an extrusion temperature, and a volatile organic liquid is mixed and extruded (Japanese Patent Publication No. 60-55290). JP-A-3-8379), a method of extruding and foaming a resin composition in which an ionic copolymer and a foaming agent are mixed with an olefin-based resin (Japanese Patent Publication No. 3-8379), and adding ethylene-methacrylic acid copolymer to a polyolefin-based resin. After heating and softening or melting the resin composition comprising the coalesced (ionomer resin), the nucleating agent, the anti-shrinkage agent and the like, the composition obtained by supplying and mixing the volatile foaming agent is extruded into a low pressure region. A method (JP-A-10-279724) and the like have been proposed. The open-cell foam produced by such a method is excellent in recyclability, but has a low open-cell rate, and is unsuitable for use as a carrier, a filter, and the like for filling a biological filtration tank in a biological filtration system combined treatment / purification tank. .
[0005]
[Problems to be solved by the invention]
Accordingly, it is an object of the present invention to provide a method for producing a polyethylene-based resin open-cell body which is excellent in recyclability and has a high open-cell rate while solving the above-mentioned drawbacks of the prior art.
[0006]
[Means for Solving the Problems]
In the first method of the present invention, a foamable composition obtained by adding 4,4′-oxybis (benzenesulfonyl hydrazide) to a polyethylene resin obtained by using a metallocene compound as a polymerization catalyst is formed, and then under normal pressure. And foaming by heating to form a foam, and applying mechanical deformation to the foam to make the bubbles open. In the first method, the melting point of the polyethylene resin is preferably 100 ° C. or less. When the melting point of the polyethylene-based resin exceeds 100 ° C., the foam breaking property decreases. The reason is assumed to be due to the rigidity of the resin.
[0007]
In the second method of the present invention, a foamable composition obtained by adding 4,4′-oxybis (benzenesulfonylhydrazide) to an ethylene-vinyl acetate copolymer is formed, and then foamed by heating under normal pressure to form a foam. It is characterized in that the foam is formed and mechanical deformation is applied to the foam to open the cells. In the second method, it is preferable that the vinyl acetate content of the ethylene-vinyl acetate copolymer is 5% or more. When the vinyl acetate content is less than 5%, the foam breaking property is reduced. The reason is assumed to be due to the rigidity of the resin.
[0008]
In the normal pressure foaming of the first method and the second method of the present invention, it is preferable to foam freely in a three-dimensional direction, and if a pressure is applied in the final stage of foaming in a mold, foaming is hindered. , Easily contracts.
[0009]
The present invention has a low decomposition temperature of 4,4'-oxybis (benzenesulfonylhydrazide) as a foaming agent and a high decomposition rate, so that it is easy to form open cells and an effect of improving the holding power of the decomposition residue of the foaming agent. Focus on easy foaming even without cross-linking.
The polyethylene-based resin obtained metallocene compound as a polymerization catalyst composed of a copolymer of α-olefins and C 3 -C 18, as α- olefins, for example, propylene, 1-butene, 1-pentene, Examples include 1-hexene, 4-methyl-1-pentene, 1-octene and the like.
[0010]
In general, a metallocene catalyst is a compound having a structure in which a transition metal is sandwiched between π-electron unsaturated compounds.In the present invention, titanium, zirconium, nickel, palladium, hafnium, tetravalent transition metals such as platinum, Examples include compounds in which one or more cyclopentadienyl rings or analogs thereof are present as ligands (ligands).
As the ligand, other than the cyclopentadienyl ring, for example, a cyclopentadienyl oligomer ring, an indenyl ring, a hydrocarbon group or a substituted hydrocarbon group or a cyclopentadienyl ring substituted by a hydrocarbon-substituted metalloid group or And an indenyl ring. In addition to such ligands, for example, monovalent anion or divalent anion chelate of chlorine or bromine, hydrocarbon group, alkoxide, arylalkoxide, aryloxide, amide, arylamide, phosphide, arylphosphide, etc. It may be coordinated to the metal.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the method for producing an open-cell body according to the present invention will be specifically described.
First, 4,4′-oxybis (benzenesulfonyl hydrazide) as a blowing agent, preferably 1: 1 is added to 100 parts by weight of a polyethylene resin or / and an ethylene-vinyl acetate copolymer obtained by using a metallocene compound as a polymerization catalyst. ３０30 parts by weight, and if necessary, a filler, a pigment and the like are added, and the mixture is kneaded with a heated mixing roll, a pressure kneader, an extruder or the like.
[0012]
In the present invention, in order to improve the physical properties of the composition to be used, to act as a nucleating agent (uniform and uniform air bubbles), to improve the defoaming property, or to reduce the price, the decomposition reaction of the foaming agent is performed. Additives (fillers) that do not have a significant adverse effect and do not crosslink the resin, for example, metal oxides such as zinc oxide, titanium oxide, calcium oxide, magnesium oxide, and silicon oxide, and carbonates such as magnesium carbonate and calcium carbonate. Alternatively, fiber materials such as pulp, or various dyes, pigments, fluorescent materials, and other commonly used rubber compounding agents can be added as necessary.
The foamable composition obtained by kneading as described above is charged into a mold, and is heated to a temperature equal to or higher than the melting point of the resin under pressure by a press to be shaped. This heating shaping is a step of shaping into a desired shape, and 4,4′-oxybis (benzenesulfonylhydrazide) does not substantially decompose. In this heating shaping step, a very small amount of the foaming agent undergoes initial decomposition, and when the shaped article is taken out of the mold, it can expand to about twice, but this is far from the concept of foaming, and is not considered for the present invention. No problem.
[0013]
The foamable composition shaped as described above is then heated under normal pressure to decompose 4,4'-oxybis (benzenesulfonylhydrazide). As a method of heating under normal pressure, for example, a hot air thermostat, a heater is closely attached to the outer surface of a metal plate, or heating is performed, or a flow path of a heat medium is provided in a metal plate, and steam, heating oil, or the like is provided by a jacket method. And a heat bath such as an oil bath, a metal bath, and a salt bath.
In the present invention, normal pressure foaming is preferably free foaming in three-dimensional directions, and a lubricating agent such as talc is preferably spread on the lower surface because resistance does not occur during foaming. A metal plate such as an iron plate and an aluminum plate, a metal net, a fiber net, and various sheets whose surfaces are processed with polytetrafluoroethylene can be applied to the lower surface during normal pressure foaming. The heating temperature is preferably set in the range of 140 to 180 ° C, particularly preferably in the range of 145 to 175 ° C, depending on the type of the resin used. The heating time is preferably 5 to 40 minutes, more preferably 10 to 35 minutes. Since the decomposition residue of 4,4'-oxybis (benzenesulfonyl hydrazide) turns black at high temperature for a long time, the foam obtained at a temperature higher than the range of the foaming conditions for a long time turns black.
In this way, a foam having a foam film that can be easily broken by applying mechanical deformation is obtained.
[0014]
The foam obtained as described above (so-called closed cell) is then subjected to compressive deformation with, for example, a constant-speed double roll or the like, so that the foam film is broken, and the bubbles are made open to obtain a continuous foam. Can be Countless small needles are provided on the surface of the constant velocity twin roll, or rolls provided with countless small needles are arranged before and / or after the constant velocity double roll, and countless small needles are provided on the surface of the foam. By forming the holes, communication of bubbles can be promoted.
The open cell obtained by this method has an open cell ratio of 100% or close to 100% as a result of measurement using an air-comparison hydrometer 1000 (manufactured by Tokyo Science Co., Ltd.) based on ASTM D 2856. Was.
[0015]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples.
Example 1
Polyethylene resin polymerized using a metallocene catalyst (trade name: Kernel KS240, density (D): 0.880 g / cm 3 , MFR: 2.2 g / 10 minutes, melting point: 60 ° C., manufactured by Nippon Polychem Co., Ltd.) A composition comprising 10 parts by weight of 4,4'-oxybis (benzenesulfonylhydrazide) (trade name: Neoservon N # 5000, decomposition temperature: 164 ° C., manufactured by Eiwa Chemical Co., Ltd.) in 100 parts by weight was mixed on a 85 ° C. mixing roll. The composition obtained by kneading the mixture was filled in a mold (5 × 200 × 200 mm) in a press heated to 110 ° C., sealed at the above temperature for 2 minutes, and heated to shape a foamable sheet.
Next, the obtained foamable crosslinkable sheet was placed on a metal plate on which talc powder was thinly spread, and heated in a circulating air oven at 160 ° C. for 20 minutes to obtain a foam.
The obtained foam was passed twice between two constant-velocity rolls set at a roll interval of 2 mm to break the cell membrane and to communicate the cells. The obtained open-cell foam after communication had a size of 11 × 470 × 470 mm, an apparent density of 0.073 g / cm 3 and an open-cell ratio of 100%, and had uniform air bubbles.
[0016]
Example 2
An open-cell foam was obtained in the same manner as in Example 1, except that 4,4'-oxybis (benzenesulfonylhydrazide) was changed to 20 parts by weight in Example 1.
The obtained open-cell foam after communication had a size of 12 × 550 × 550 mm, an apparent density of 0.049 g / cm 3 and an open-cell rate of 100%, and had substantially uniform cells.
[0017]
Example 3
In Example 1, a polyethylene-based resin was polymerized using a metallocene catalyst (trade name: Kernel KS340, density (D): 0.880 g / cm 3 , MFR: 3.5 g / 10 min, melting point). : 60 ° C, manufactured by Nippon Polychem Co., Ltd.), and an open-cell foam was obtained under the same composition and under the same foaming conditions as in Example 1.
The obtained open-cell foam after communication had a size of 13 × 430 × 430 mm, an apparent density of 0.071 g / cm 3 , and an open-cell ratio of 100%, and had uniform air bubbles.
[0018]
Example 4
An open-cell foam was obtained in the same manner as in Example 3 except that 4,4′-oxybis (benzenesulfonylhydrazide) was changed to 20 parts by weight in Example 3 and under the same foaming conditions.
The obtained open-cell foam after communication had a size of 14 × 520 × 520 mm, an apparent density of 0.046 g / cm 3 , and an open-cell rate of 100%, and had substantially uniform cells.
[0019]
Example 5
In Example 1, the resin was an ethylene-vinyl acetate copolymer (trade name: Novatec LV540, density 0.942 g / cm 3 , MFR 2.5 g / 10 min, melting point: 83 ° C., vinyl acetate content: 20% by weight, A closed-cell body was produced using the same composition and the same foaming conditions as in Example 1, except that the composition was changed to 20 parts by weight of 4,4'-oxybis (benzenesulfonylhydrazide) instead of Nippon Polychem Co., Ltd. The closed cell was passed 10 times between constant-velocity rolls at the same interval as 1 to obtain a continuous cell.
The obtained open-cell foam after communication had a size of 21 × 460 × 460 mm, an apparent density of 0.043 g / cm 3 , and an open-cell ratio of 95%, and had substantially uniform cells.
[0020]
Comparative Example 1
In Example 1, except that the resin was changed to a high-pressure low-density polyethylene (trade name: Novatec YF-30, density: 0.920 g / cm3, MFR: 1.1 g / 10 min, melting point: 109 ° C., manufactured by Nippon Polychem Co., Ltd.) A closed cell was molded under the same composition and under the same foaming conditions as in Example 1, and was passed ten times between two constant-velocity rolls with a 4.0 mm roll interval. Was.
[0021]
Comparative Example 2
In Example 1, 3.0 parts by weight of azodicarbonamide was blended in place of 4,4'-oxybis (benzenesulfonyl hydrazide), and 2.0 parts by weight of active zinc white and 1.0 part by weight of zinc stearate were added. Except for the above, molding was carried out under the same composition and under the same foaming conditions as in Example 1, but it contracted by normal pressure foaming, and a foam could not be obtained.
[0022]
[Table 1]
[Table 2]
【The invention's effect】
As described above, according to the present invention, 4,4′-oxybis (benzenesulfonylhydrazide) is used as a foaming agent, and a polyethylene having a sharp and uniform physical property in molecular weight distribution polymerized by a metallocene catalyst is used as a base material. By using a system resin or an ethylene vinyl acetate copolymer, it is possible to produce a continuous cell having a high open cell ratio without cross-linking, excellent recyclability, a filter, a carrier of the septic tank, and prevention of dew condensation in an air conditioner. The present invention is suitable as a material, can be melted after use, can be reused as a resin, and is useful in resource saving.
Claims (5)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000038140A JP3565755B2 (en) | 2000-02-10 | 2000-02-10 | Method for producing open cell of polyethylene resin |
| US09/779,862 US6517764B2 (en) | 2000-02-10 | 2001-02-08 | Method of making polyethylene resinous open cell cellular bodies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000038140A JP3565755B2 (en) | 2000-02-10 | 2000-02-10 | Method for producing open cell of polyethylene resin |
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| Publication Number | Publication Date |
|---|---|
| JP2001226511A JP2001226511A (en) | 2001-08-21 |
| JP3565755B2 true JP3565755B2 (en) | 2004-09-15 |
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|---|---|---|---|
| JP2000038140A Expired - Fee Related JP3565755B2 (en) | 2000-02-10 | 2000-02-10 | Method for producing open cell of polyethylene resin |
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| JP (1) | JP3565755B2 (en) |
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| JP2001226511A (en) | 2001-08-21 |
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