JP3692681B2 - Polyolefin resin cross-linked foam - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、成型寸法安定性に優れ、かつ車輌用内装材に用いたとき生ずるブリードアウトによる汚れ発生の少ないポリオレフィン系樹脂架橋発泡体に関する。
【０００２】
【従来の技術】
従来、ダッシュボード等の車輌用内装成型品には、発泡剤にアゾジカルボンアミドを用いたポリオレフィン系樹脂発泡体が広く使用されている。成型時の寸法安定性については特公平６ー７８４４９号公報が知られていたが、寸法安定性と発泡剤の分解物等に起因するブリードアウト汚れを同時に解決する手段は存在しなかった。
【０００３】
【発明が解決しようとする課題】
前記の発泡剤にアゾジヂカルボンアミドを用いるポリオレフィン系樹脂発泡体からなるパッド材を備えた車輌内装材の成型方法としては、たとえば、一体成型法、真空圧縮法などの周知の方法が用いられている。また、最近では、省エネルギー、省人、接着剤レス等の低コスト化が計られるようになってきており、また、品質の安定性が良好な成型方法として、ホットスタンピングモールド法が採用されはじめている。しかし、車輌用内装材は、前記したような成型方法により高圧で成型加工されると厚みが減少する、いわゆる許容範囲を越えた寸法減少をおこすことがある。
【０００４】
また、一体成型法やホットスタンピングモールド法の場合には、高温に接するため発泡体の気泡が破壊される。その結果、凹凸等の表面荒れが車輌用内装材の表面にも現れると言う問題が生じる。また、ポリオレフィン系樹脂発泡体を車輌用内装材として使用した場合、発泡剤の分解物等に起因したブリードアウト汚れで外観を悪化させるという問題が生じる。
【０００５】
従って、本発明の目的は成型時の寸法安定性およびブリードアウト汚れを同時に解決することにある。
【０００６】
【課題を解決するための手段】
前記課題を達成するため本発明のポリオレフィン系樹脂架橋発泡体は下記の構成からなる。
【０００７】
すなわち、ポリプロピレン系樹脂１００〜３０重量％とポリエチレン系樹脂０〜７０％とからなる混和物１００重量部に対し、０．０２〜２０．０μｍの平均粒子径を有する、アルミニウムを構成成分とする複合酸化物粒子および／または酸化アルミニウム粒子を０．１〜２０重量部を含有する見掛け密度０．２００〜０．０２５ｇ／ｃｍ3 のポリオレフィン系樹脂架橋発泡体である。
【０００８】
【発明の実施の形態】
本発明に用いられるポリオレフィン系樹脂は、ポリプロピレン系樹脂単独またはポリプロピレン系樹脂とポリエチレン系樹脂との混合樹脂からなる。ポリプロピレン系樹脂としては、プロピレンの単独重合体、エチレンやブテン等のαオレフィンとのブロック共重合体、ランダム共重合体、ランダムーブロック共重合体等を例示することができる。これらのポリプロピレン系樹脂は、それぞれ単独で用いても、２種以上混合してもよい。ポリエチレン系樹脂としては、低圧法、中圧法、高圧法により製造された密度０．９００〜０．９６５ｇ／ｃｃのポリエチレン樹脂、エチレンー酢酸ビニル共重合体、エチレンーアクリル酸エステル共重合体等を例示することができる。これらのポリエチレン系樹脂は、それぞれ単独で用いてもよいし、２種以上混合して用いてもよい。
【０００９】
本発明に用いられるポリオレフィン系樹脂は、前記ポリプロピレン系樹脂１００〜３０重量％、好ましくは９０〜５０重量％に対して、前記ポリエチレン系樹脂を０〜７０重量％、好ましくは１０〜５０重量％混合した樹脂からなる。ポリエチレン系樹脂が７０重量％より多く含まれる場合には、発泡体の耐熱性が低下し、車輌用内装材に用いるのが困難となる。
【００１０】
本発明で使用される発泡剤としては、アゾジカルボンアミドが使用されその添加量は、所望の発泡倍率により適宜調整されるが、一般的には樹脂１００重量部に対し２〜２５重量部である。
【００１１】
本発明に使用されるアルミニウムを構成成分とする複合酸化物粒子および／または酸化アルミニウム粒子は、例えば複合酸化物粒子としては、カオリン、ゼオライト、ジークライト、非晶質シリカーアルミナ粒子、アルミノケイ酸塩粒子等が挙げられる。中でもカオリンは優れた寸法安定性とブリードアウト汚れ防止効果効果を有しているので好ましく用いられる。特に、アルミニウムを構成成分とする複合酸化物粒子中の珪素、アルミニウム及びアルカリ金属の含有量が、式（１）〜（３）を満たすことにより、より優れた寸法安定性とブリードアウト汚れ防止効果効果を有するポリオレフィン系樹脂架橋発泡体が得られる。
【００１２】
１０重量％ ≦ Ｓｉ ≦ ４５重量％ …（１）
３重量％ ≦ Ａｌ ≦ ３０重量％ …（２）
０重量％ ≦ Ｍ ≦ ２０重量％ …（３）
（式中Ｓｉは珪素原子含有量を，Ａｌはアルミニウム原子含有量を、Ｍはアルカリ原子含有量を表す。）
【００１３】
また、酸化アルミニウム粒子としては、δ、γ、θ、α型酸化アルミニウム粒子等が挙げられる。
【００１４】
本発明における無機粒子の一次粒子径は、０．０２〜２０．０μｍとする必要がある。好ましくは、０．０５〜２０．０μｍであり、さらに好ましくは、０．１〜１５．０μｍである。粒子径が２０．０μｍを越えると、発泡シートの表面平坦性が損なわれ、外観が悪化する原因となり好ましくない。逆に、０．０２μｍより小さい場合も、粒子の一部が二次凝集を起こすためか、発泡シートの表面平坦性が損なわれ、外観が悪化し好ましくない。
【００１５】
本発明における粒子径とは、全粒子の５０重量％の点における粒子の等価球形直径を意味する。ここでいう等価球形直径とは、対象粒子と同じ体積を有する仮想球の直径を意味し、通常の沈降法や電子顕微鏡による直接観察など公知の方法で測定することができる。
【００１６】
アルカリ金属原子の定量は、原子吸光法で測定し、ケイ素原子、アルミニウム原子の定量は蛍光Ｘ線分析法で測定した。
【００１７】
本発明に用いられる無機粒子含有ポリオレフィン系樹脂組成物は、前記ポリオレフィン系樹脂１００重量部に対し前記無機粒子を０．１〜２０重量部、好ましくは０．１〜１０重量部混合したものである。無機粒子が０．１重量部未満の場合は、本発明の効果が得られなくなる。無機粒子量が２０重量部を越えた場合は、ポリオレフィン系樹脂の発泡性が低下し、発泡体の緩衝性や柔軟性が低下する。
【００１８】
本発明で使用される無機粒子の添加方法としては特に限定されないが、無機粒子を含有したペレットで添加する方法が好ましい。
【００１９】
なお、本発明に用いられる組成物には第３成分として、ポリオレフィン系樹脂以外の樹脂、たとえば石油樹脂、ポリスチレン樹脂等が混合されていてもよい。また、発泡性樹脂組成物には、難燃剤、着色剤、抗酸化剤、充填剤、発泡助剤、滑剤、架橋助剤等を必要により適宜添加することができる。本発明のポリオレフィン系樹脂架橋発泡体は、架橋構造を有することが必須であるが、かかる架橋発泡体とする場合は、一般的には電子線による方法や、ジクミルパーオキサイド等の有機過酸化物を用いた化学架橋による方法や架橋反応性ビニルメトキシシラン等を樹脂にグラフトまたは共重合した樹脂を用いて電子線照射法や化学架橋方法等も適用できる。また、各種の架橋方法を併用してもよい。
【００２０】
このようにして得られた発泡体の架橋度は、好ましくは１０〜７５％、さらに好ましくは４０〜６５％の範囲にあるのがよい。架橋度が低い場合は発泡体の耐熱性が低く、成型時に表面荒れが生じやすい。一方、架橋度が高い場合は発泡体の伸度が低下して成型性が悪化する。なお、架橋度は発泡体試料０．１ｇを１３０℃のテトラリンに３時間溶解した後に残った不溶分の重量％で示される値である。また本発明の発泡体の見掛け密度は、０．２００〜０．０２５ｇ／ｃｍ3 、さらに、０．１００〜０．０４０ｇ／ｃｍ3 が望ましい。見掛け密度が小さい場合には、発泡体の応力が小さくなり、発泡体が成型時破壊しやすくなる。見掛け密度が大きい場合には、発泡体の緩衝性が小さくなる。なお、発泡体の見掛け密度は、下記の式によって求めることができる。
【００２１】
【数１】
また、ブリードアウトによる汚れ発生状況は、次の様に求めた。得られた発泡体シートの片面に接着剤を介して厚さ０．６μｍの軟質ポリ塩化ビニルシートを張り合わせ、軟質ポリ塩化ビニルシート面を上にして、ＨＡＡＫＥのフォギング装置を用いて、１００℃、３時間加熱後、常温で１時間冷却した。ブリードアウトによる汚れ発生は５０倍の顕微鏡を用いて結晶の有無で判定した。
【００２３】
また、成型時の寸法安定性は次の様に求めることができる。得られた発泡体シートの片面に接着剤を介して厚さ０．６μｍの軟質ポリ塩化ビニルシートを張り合わせ、これを２５０ｍｍ角に切断し、２００℃の溶融状態のポリプロピレン樹脂３０ｇを圧縮成型機を用いてホットスタンピングモールド法により温度６０℃、圧力５８ｋｇ／ｃｍ2 で成型加工した。得られた車輌用内装材について、気泡破壊状態、表皮面の凹凸状態を目視で、および発泡層の寸法安定性を次式により求めた。
【００２４】
【数２】
このようにして得られた車輌用内装材は、例えばダッシュボード、ドアトリム、シートバックトリム、成型天井、リアクオータトリム、センターピラーパッド等に好適に用いられる。
【００２６】
【発明の効果】
本発明により、成型寸法安定性に優れ、かつ車輌用内装材に用いたとき生ずるブリードアウトによる汚れ発生の少ない車輌用内装材として好適なポリオレフィン系樹脂架橋発泡体が得られる。
【００２７】
【実施例】
［実施例１、２、３、４、５］
プロピレンにエチレンを５重量％ランダム共重合したポリプロピレン系樹脂（メルトインデクッス２．０）８０重量部、直鎖状低密度ポリエチレン（密度０．９３、メルトインデクッス８．０）２０重量部に発泡剤としてアゾジカルボンアミド１０重量部、架橋助剤としてジビニルベンゼン４重量部、熱安定剤としてＩｒｇａｎｏｘ１０１０を０．２重量部加え、カオリン（平均粒子径１．１μｍ、アルミウム含有量１９．３％、Ｓｉ含有量２２．２％、Ｎａ含有量０．１５％）をそれぞれ０．１（実施例１）、０．５（実施例２）、１．０（実施例３）、３．０（実施例４）、５．０（実施例５）重量部に調整し、ヘンシェルミキサーで予備混合し、その混合物を９０ｍｍφ一軸押出機（Ｌ／Ｄ＝２５）に投入し、発泡剤が分解しないよう平均樹脂温度を１８０℃以下に調整して混練し、Ｔダイより押出して、それぞれ、厚み１．７５ｍｍ、幅４１０ｍｍの発泡性樹脂組成物シートを５種類作成した。次に、それぞれの発泡性樹脂組成物シートに電子線照射機（８００ｋｖ）を用いて５Ｍｒａｄの電子線量を照射して架橋させ、発泡性樹脂組成物架橋シートとした。得られたシートを発泡装置内で発泡剤の分解温度以上の約２３０〜２４０℃に加熱し、架橋度５２％見掛け密度０．０５８ｇ／ｃｍ3 の架橋発砲体を製造した。結果を表１に示す。
【００２８】
カオリンを添加した実施例１、２、３、４、５は、ブリードアウトによる汚れ発生原因となる結晶の生成は認められず、成型時の寸法安定性も、目視による発泡体シートの表面平坦性も良好であった。
【００２９】
［比較例１］
カオリンを含有しない以外は実施例１〜５と同様に発泡体を製造した。結果を表１に示す。カオリンを含有しない場合は、目視による発泡体シートの表面平坦性は良好であったが、汚れ発生原因となる結晶が生成し、成型時の寸法安定性も劣っていた。
【００３０】
【表１】
［実施例６、７、比較例２、３、４］
プロピレンにエチレンを５重量％ランダム共重合したポリプロピレン系樹脂（メルトインデクッス２．０）８０重量部、直鎖状低密度ポリエチレン（密度０．９３、メルトインデクッス８．０）２０重量部に発泡剤としてアゾジカルボンアミド１０重量部、架橋助剤としてジビニルベンゼン４重量部、熱安定剤としてＩｒｇａｎｏｘ１０１０を０．２重量部加え、カオリン（アルミウム含有量１９．３％、Ｓｉ含有量２２．２％、Ｎａ含有量０．１５％）、添加量、平均粒子径、をそれぞれ変更し、ヘンシェルミキサーで予備混合し、その混合物を９０ｍｍφ一軸押出機（Ｌ／Ｄ＝２５）に投入し、発泡剤が分解しないよう平均樹脂温度を１８０℃以下に調整して混練し、Ｔダイより押出して、それぞれ、厚み１．７５ｍｍ、幅４１０ｍｍの発泡性樹脂組成物シートを５種類作成した。次に、それぞれの発泡性樹脂組成物シートに電子線照射機（８００ｋｖ）を用いて５Ｍｒａｄの電子線量を照射して架橋させ、発泡性樹脂組成物架橋シートとした。得られたシートを発泡装置内で発泡剤の分解温度以上の約２３０〜２４０℃に加熱し、架橋度５２％、見掛け密度０．０５８ｇ／ｃｍ3 の架橋発砲体を製造した。結果を表２に示す。
【００３２】
カオリンの粒子径が本願範囲より大きい場合（比較例２）は、発泡シート表面に凹凸が現れ外観に劣り、カオリン添加量が多い場合（比較例３）は、シート発泡性に劣り、カオリン添加量が少ない場合（比較例４）は、汚れ発生原因となる結晶が生成し、成型時の寸法安定性も劣っていた。
【００３３】
【表２】
［実施例８］
プロピレンにエチレンを５重量％ランダム共重合したポリプロピレン系樹脂（メルトインデクッス２．０）８０重量部、直鎖状低密度ポリエチレン（密度０．９３、メルトインデクッス８．０）２０重量部に発泡剤としてアゾジカルボンアミド１０重量部、架橋助剤としてジビニルベンゼン４重量部、熱安定剤としてＩｒｇａｎｏｘ１０１０を０．２重量部加え、δ型酸化アルミニウム粒子（平均粒子径０．１μｍ）を５．０重量部に調整し、ヘンシェルミキサーで予備混合し、その混合物を９０ｍｍφ一軸押出機（Ｌ／Ｄ＝２５）に投入し、発泡剤が分解しないよう平均樹脂温度を１８０℃以下に調整して混練し、Ｔダイより押出して、それぞれ、厚み１．７５ｍｍ、幅４１０ｍｍの発泡性樹脂組成物シートを５種類作成した。次に、それぞれの発泡性樹脂組成物シートに電子線照射機（８００ｋｖ）を用いて５Ｍｒａｄの電子線量を照射して架橋させ、発泡性樹脂組成物架橋シートとした。得られたシートを発泡装置内で発泡剤の分解温度以上の約２３０〜２４０℃に加熱し、架橋発砲体を製造した。得られた発泡体シートの見掛け密度は０．０４９ｇ／ｃｍ3 を有し、寸法安定性は２４％で、結晶発生は全く認められずシート表面状態も極めて良好であった。
【００３５】
［実施例９、１０、１１、１２］
プロピレンにエチレンを５重量％ランダム共重合したポリプロピレン系樹脂（メルトインデクッス２．０）８０重量部、直鎖状低密度ポリエチレン（密度０．９３、メルトインデクッス８．０）２０重量部に発泡剤としてアゾジカルボンアミド１０重量部、架橋助剤としてジビニルベンゼン４重量部、熱安定剤としてＩｒｇａｎｏｘ１０１０を０．２重量部加え、平均粒径２．０μｍを有する各種ケイ酸アルミウム粒子３．０重量部を調整し、ヘンシェルミキサーで予備混合し、その混合物を９０ｍｍφ一軸押出機（Ｌ／Ｄ＝２５）に投入し、発泡剤が分解しないよう平均樹脂温度を１８０℃以下に調整して混練し、Ｔダイより押出して、それぞれ、厚み１．７５ｍｍ、幅４１０ｍｍの発泡性樹脂組成物シートを４種類作成した。次に、それぞれの発泡性樹脂組成物シートに電子線照射機（８００ｋｖ）を用いて５Ｍｒａｄの電子線量を照射して架橋させ、発泡性樹脂組成物架橋シートとした。得られたシートを発泡装置内で発泡剤の分解温度以上の約２３０〜２４０℃に加熱し、架橋発砲体を製造した。結果を表３に示す。
【００３６】
Ｓｉ、Ａｌ、Ｎａ含有量が本発明範囲内（実施例９、１０）の組成を有する粒子を含有した発泡シートは、汚れの発生原因となる結晶の生成は認められなかった。Ｓｉ量が多め（実施例１１）やＡｌ量が多め（実施例１２）の発泡シートは、結晶の生成が僅かに認められた。
【００３７】
【表３】
BACKGROUND OF THE INVENTION
The present invention relates to a polyolefin resin cross-linked foam which is excellent in molding dimensional stability and is less likely to generate dirt due to bleed-out that occurs when used as an interior material for vehicles.
[0002]
[Prior art]
Conventionally, polyolefin resin foams using azodicarbonamide as a foaming agent have been widely used for interior molded articles for vehicles such as dashboards. Japanese Patent Publication No. 6-78449 has been known for dimensional stability at the time of molding, but there has been no means for simultaneously solving dimensional stability and bleed-out contamination caused by a decomposed product of a foaming agent.
[0003]
[Problems to be solved by the invention]
As a method for molding a vehicle interior material provided with a pad material made of a polyolefin resin foam using azodidicarbonamide as the foaming agent, for example, a well-known method such as an integral molding method or a vacuum compression method is used. ing. In recent years, energy saving, labor saving, adhesiveless, etc. have been made cost-effective, and the hot stamping mold method has begun to be adopted as a molding method with good quality stability. . However, the interior material for a vehicle may cause a reduction in dimension exceeding a so-called allowable range in which the thickness decreases when it is molded at a high pressure by the molding method as described above.
[0004]
In the case of the integral molding method or the hot stamping mold method, the foam bubbles are destroyed due to contact with the high temperature. As a result, there arises a problem that surface roughness such as irregularities also appears on the surface of the vehicle interior material. Further, when a polyolefin resin foam is used as an interior material for a vehicle, there arises a problem that the appearance is deteriorated due to bleed-out dirt caused by a decomposition product of the foaming agent.
[0005]
Accordingly, an object of the present invention is to simultaneously solve the dimensional stability and bleed-out contamination during molding.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the polyolefin resin cross-linked foam of the present invention has the following constitution.
[0007]
That is, a composite having aluminum as a constituent component having an average particle diameter of 0.02 to 20.0 μm with respect to 100 parts by weight of a mixture composed of 100 to 30% by weight of polypropylene resin and 0 to 70% of polyethylene resin. It is a polyolefin resin cross-linked foam having an apparent density of 0.200 to 0.025 g / cm 3 containing 0.1 to 20 parts by weight of oxide particles and / or aluminum oxide particles.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The polyolefin resin used in the present invention comprises a polypropylene resin alone or a mixed resin of a polypropylene resin and a polyethylene resin. Examples of the polypropylene resin include propylene homopolymers, block copolymers with α-olefins such as ethylene and butene, random copolymers, random block copolymers, and the like. These polypropylene resins may be used alone or in combination of two or more. Examples of polyethylene resins include polyethylene resins having a density of 0.900 to 0.965 g / cc, ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, etc. produced by the low pressure method, medium pressure method, and high pressure method. can do. These polyethylene resins may be used alone or in combination of two or more.
[0009]
The polyolefin resin used in the present invention is a mixture of 100 to 30 wt%, preferably 90 to 50 wt% of the polypropylene resin, and 0 to 70 wt%, preferably 10 to 50 wt% of the polyethylene resin. Made of resin. When the polyethylene resin is contained in an amount of more than 70% by weight, the heat resistance of the foam is lowered, and it becomes difficult to use it for the vehicle interior material.
[0010]
As the foaming agent used in the present invention, azodicarbonamide is used, and the amount added is appropriately adjusted according to the desired foaming ratio, but is generally 2 to 25 parts by weight with respect to 100 parts by weight of the resin. .
[0011]
The composite oxide particles and / or aluminum oxide particles containing aluminum as a constituent component used in the present invention include, for example, kaolin, zeolite, dikelite, amorphous silica-alumina particles, aluminosilicate as composite oxide particles. Particles and the like. Of these, kaolin is preferably used because it has excellent dimensional stability and an effect of preventing bleeding out stains. In particular, when the content of silicon, aluminum, and alkali metal in the composite oxide particles containing aluminum as a constituent satisfies the formulas (1) to (3), more excellent dimensional stability and bleed-out contamination prevention effect A polyolefin resin cross-linked foam having an effect is obtained.
[0012]
10 wt% ≤ Si ≤ 45 wt% (1)
3% by weight ≦ Al ≦ 30% by weight (2)
0% by weight ≤ M ≤ 20% by weight (3)
(In the formula, Si represents the silicon atom content, Al represents the aluminum atom content, and M represents the alkali atom content.)
[0013]
Examples of the aluminum oxide particles include δ, γ, θ, α-type aluminum oxide particles and the like.
[0014]
The primary particle diameter of the inorganic particles in the present invention needs to be 0.02 to 20.0 μm. Preferably, it is 0.05-20.0 micrometers, More preferably, it is 0.1-15.0 micrometers. When the particle diameter exceeds 20.0 μm, the surface flatness of the foamed sheet is impaired, and the appearance is deteriorated. On the other hand, when the particle size is smaller than 0.02 μm, it is not preferable because some of the particles cause secondary aggregation, or the surface flatness of the foamed sheet is impaired and the appearance deteriorates.
[0015]
The particle diameter in the present invention means an equivalent spherical diameter of particles at a point of 50% by weight of all particles. The equivalent spherical diameter here means the diameter of a virtual sphere having the same volume as the target particle, and can be measured by a known method such as a normal sedimentation method or direct observation with an electron microscope.
[0016]
Alkali metal atoms were quantified by atomic absorption, and silicon atoms and aluminum atoms were quantified by fluorescent X-ray analysis.
[0017]
The inorganic particle-containing polyolefin resin composition used in the present invention is obtained by mixing 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight of the inorganic particles with respect to 100 parts by weight of the polyolefin resin. . When the inorganic particles are less than 0.1 parts by weight, the effect of the present invention cannot be obtained. When the amount of inorganic particles exceeds 20 parts by weight, the foaming property of the polyolefin resin is lowered, and the buffering property and flexibility of the foam are lowered.
[0018]
The addition method of the inorganic particles used in the present invention is not particularly limited, but a method of adding the pellets containing inorganic particles is preferable.
[0019]
In addition, in the composition used for this invention, resin other than polyolefin resin, for example, petroleum resin, polystyrene resin, etc. may be mixed as a 3rd component. Moreover, a flame retardant, a coloring agent, an antioxidant, a filler, a foaming aid, a lubricant, a crosslinking aid and the like can be appropriately added to the foamable resin composition as necessary. The polyolefin resin cross-linked foam of the present invention must have a cross-linked structure. When such a cross-linked foam is used, generally, a method using an electron beam or an organic peroxide such as dicumyl peroxide is used. applicable electron beam irradiation method or a chemical crosslinking method and the like using a method and a crosslinking reactive vinyl methoxy silane was grafted or copolymerized in tree butter resins by chemical crosslinking with things. Various crosslinking methods may be used in combination.
[0020]
The degree of crosslinking of the foam thus obtained is preferably in the range of 10 to 75% , more preferably 40 to 65%. When the degree of crosslinking is low, the heat resistance of the foam is low, and surface roughening is likely to occur during molding. On the other hand, when the degree of crosslinking is high, the elongation of the foam is lowered and the moldability is deteriorated. The degree of cross-linking is a value represented by weight% of insoluble matter remaining after 0.1 g of the foam sample was dissolved in tetralin at 130 ° C. for 3 hours. The apparent density of the foam of the present invention is preferably 0.200 to 0.025 g / cm 3 , more preferably 0.100 to 0.040 g / cm 3 . When the apparent density is small, the stress of the foam is small, and the foam is easily broken at the time of molding. When the apparent density is large, the cushioning property of the foam becomes small. The apparent density of the foam can be obtained by the following formula.
[0021]
[Expression 1]
In addition, the occurrence of contamination due to bleed out was determined as follows. A soft polyvinyl chloride sheet having a thickness of 0.6 μm is bonded to one side of the obtained foam sheet via an adhesive, the surface of the soft polyvinyl chloride sheet is turned up, and a HAAKE fogging apparatus is used. After heating for 3 hours, it was cooled at room temperature for 1 hour. The occurrence of contamination due to bleed-out was determined by the presence or absence of crystals using a 50 × microscope.
[0023]
Moreover, the dimensional stability at the time of shaping | molding can be calculated | required as follows. A soft polyvinyl chloride sheet having a thickness of 0.6 μm is laminated on one side of the obtained foam sheet with an adhesive, cut into a 250 mm square, and 30 g of a molten polypropylene resin at 200 ° C. is compressed with a compression molding machine. It was molded by a hot stamping mold method at a temperature of 60 ° C. and a pressure of 58 kg / cm 2 . About the obtained vehicle interior material, the bubble destruction state and the unevenness | corrugation state of the skin surface were observed visually, and the dimensional stability of the foam layer was calculated | required by following Formula.
[0024]
[Expression 2]
The vehicle interior material thus obtained is suitably used for, for example, a dashboard, a door trim, a seat back trim, a molded ceiling, a rear quarter trim, a center pillar pad, and the like.
[0026]
【The invention's effect】
According to the present invention, it is possible to obtain a polyolefin-based resin cross-linked foam which is excellent as molding dimensional stability and which is suitable as a vehicle interior material that is less likely to generate dirt due to bleed-out that occurs when used in a vehicle interior material.
[0027]
【Example】
[Examples 1, 2, 3, 4, 5]
As a foaming agent, 80 parts by weight of a polypropylene resin (melt index 2.0) obtained by random copolymerization of 5% by weight of ethylene with propylene and 20 parts by weight of a linear low density polyethylene (density 0.93, melt index 8.0) 10 parts by weight of azodicarbonamide, 4 parts by weight of divinylbenzene as a crosslinking aid, 0.2 part by weight of Irganox 1010 as a thermal stabilizer, kaolin (average particle size 1.1 μm, aluminum content 19.3%, Si content 22.2%, Na content 0.15%) 0.1 (Example 1), 0.5 (Example 2), 1.0 (Example 3), 3.0 (Example 4), respectively. , 5.0 (Example 5), adjusted to parts by weight, premixed with a Henschel mixer, and the mixture was put into a 90 mmφ single screw extruder (L / D = 25) to prevent the blowing agent from being decomposed. The average resin temperature was adjusted to 180 ° C. or lower, kneaded, and extruded from a T-die to prepare five types of foamable resin composition sheets having a thickness of 1.75 mm and a width of 410 mm, respectively. Next, each foamable resin composition sheet was crosslinked by irradiating with an electron dose of 5 Mrad using an electron beam irradiator (800 kv) to obtain a foamable resin composition crosslinked sheet. The obtained sheet was heated to about 230 to 240 ° C. above the decomposition temperature of the foaming agent in a foaming apparatus to produce a crosslinked foamed body having a degree of crosslinking of 52% and an apparent density of 0.058 g / cm 3 . The results are shown in Table 1.
[0028]
In Examples 1, 2, 3, 4, and 5 to which kaolin was added, no generation of crystals that caused stains due to bleed-out was observed, and the dimensional stability during molding was also visually flat on the surface of the foam sheet. Was also good.
[0029]
[Comparative Example 1]
A foam was produced in the same manner as in Examples 1 to 5 except that no kaolin was contained. The results are shown in Table 1. When kaolin was not contained, the surface flatness of the foam sheet was visually good, but crystals causing the occurrence of contamination were generated, and the dimensional stability during molding was also poor.
[0030]
[Table 1]
[Examples 6 and 7, Comparative Examples 2, 3, and 4]
As a foaming agent, 80 parts by weight of a polypropylene resin (melt index 2.0) obtained by random copolymerization of 5% by weight of ethylene with propylene and 20 parts by weight of a linear low density polyethylene (density 0.93, melt index 8.0) 10 parts by weight of azodicarbonamide, 4 parts by weight of divinylbenzene as a crosslinking aid, 0.2 part by weight of Irganox 1010 as a heat stabilizer, kaolin (aluminum content 19.3%, Si content 22.2%, Na content) 0.15%), addition amount, and average particle diameter are changed, premixed with a Henschel mixer, and the mixture is put into a 90 mmφ single screw extruder (L / D = 25) so that the blowing agent does not decompose. The average resin temperature is adjusted to 180 ° C. or lower, kneaded, and extruded from a T-die, each having a thickness of 1.75 mm and a width of 410 mm. The foaming resin composition sheet was five created. Next, each foamable resin composition sheet was crosslinked by irradiating with an electron dose of 5 Mrad using an electron beam irradiator (800 kv) to obtain a foamable resin composition crosslinked sheet. The obtained sheet was heated in a foaming apparatus to about 230 to 240 ° C., which is higher than the decomposition temperature of the foaming agent, to produce a crosslinked foamed body having a crosslinking degree of 52% and an apparent density of 0.058 g / cm 3 . The results are shown in Table 2.
[0032]
When the particle size of kaolin is larger than the range of the present application (Comparative Example 2), irregularities appear on the surface of the foamed sheet and the appearance is poor, and when the amount of kaolin added is large (Comparative Example 3), the sheet foaming property is poor and the amount of kaolin added When there is little (comparative example 4), the crystal | crystallization which becomes a stain | pollution | contamination generation | occurrence | production produced | generated and the dimensional stability at the time of shaping | molding was also inferior.
[0033]
[Table 2]
[Example 8]
As a foaming agent, 80 parts by weight of a polypropylene resin (melt index 2.0) obtained by random copolymerization of 5% by weight of ethylene with propylene and 20 parts by weight of a linear low density polyethylene (density 0.93, melt index 8.0) Add 10 parts by weight of azodicarbonamide, 4 parts by weight of divinylbenzene as a crosslinking aid, 0.2 parts by weight of Irganox 1010 as a heat stabilizer, and add 5.0 parts by weight of δ-type aluminum oxide particles (average particle size 0.1 μm). Adjusted, premixed with a Henschel mixer, put the mixture into a 90 mmφ single screw extruder (L / D = 25), kneaded by adjusting the average resin temperature to 180 ° C. or less so as not to decompose the foaming agent, Further, five types of foamable resin composition sheets each having a thickness of 1.75 mm and a width of 410 mm were produced by extrusion. Next, each foamable resin composition sheet was crosslinked by irradiating with an electron dose of 5 Mrad using an electron beam irradiator (800 kv) to obtain a foamable resin composition crosslinked sheet. The obtained sheet was heated to about 230 to 240 ° C. above the decomposition temperature of the foaming agent in the foaming apparatus to produce a crosslinked foamed body. The apparent density of the obtained foam sheet was 0.049 g / cm 3 , the dimensional stability was 24%, no crystal generation was observed, and the sheet surface state was very good.
[0035]
[Examples 9, 10, 11, 12]
As a foaming agent, 80 parts by weight of a polypropylene resin (melt index 2.0) obtained by random copolymerization of 5% by weight of ethylene with propylene and 20 parts by weight of a linear low density polyethylene (density 0.93, melt index 8.0) Add 10 parts by weight of azodicarbonamide, 4 parts by weight of divinylbenzene as a crosslinking aid, 0.2 part by weight of Irganox 1010 as a heat stabilizer, and adjust 3.0 parts by weight of various aluminum silicate particles having an average particle size of 2.0 μm. Then, the mixture is premixed with a Henschel mixer, the mixture is put into a 90 mmφ single screw extruder (L / D = 25), the average resin temperature is adjusted to 180 ° C. or lower so as not to decompose the foaming agent, and kneaded. Four types of foamable resin composition sheets each having a thickness of 1.75 mm and a width of 410 mm were prepared by extrusion. Next, each foamable resin composition sheet was crosslinked by irradiating with an electron dose of 5 Mrad using an electron beam irradiator (800 kv) to obtain a foamable resin composition crosslinked sheet. The obtained sheet was heated to about 230 to 240 ° C. above the decomposition temperature of the foaming agent in the foaming apparatus to produce a crosslinked foamed body. The results are shown in Table 3.
[0036]
In the foamed sheet containing particles having compositions having Si, Al, and Na contents within the range of the present invention (Examples 9 and 10), generation of crystals that cause generation of dirt was not recognized. In the foam sheet with a large amount of Si (Example 11) and a large amount of Al (Example 12), the generation of crystals was slightly observed.
[0037]
[Table 3]
Claims (5)
１０重量％ ≦ Ｓｉ ≦ ４５重量％ …（１）
３重量％ ≦ Ａｌ ≦ ３０重量％ …（２）
０重量％ ≦ Ｍ ≦ ２０重量％ …（３）
（式中Ｓｉは珪素原子含有量を，Ａｌはアルミニウム原子含有量を、Ｍはアルカリ原子含有量を表す。）3. The polyolefin-based resin-crosslinked foam according to claim 1, wherein the content of silicon, aluminum, and alkali metal in the composite oxide particles containing aluminum satisfies the formulas (1) to (3). .
10 wt% ≤ Si ≤ 45 wt% (1)
3% by weight ≦ Al ≦ 30% by weight (2)
0% by weight ≤ M ≤ 20% by weight (3)
(In the formula, Si represents the silicon atom content, Al represents the aluminum atom content, and M represents the alkali atom content.)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02248797A JP3692681B2 (en) | 1997-02-05 | 1997-02-05 | Polyolefin resin cross-linked foam |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02248797A JP3692681B2 (en) | 1997-02-05 | 1997-02-05 | Polyolefin resin cross-linked foam |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10219016A JPH10219016A (en) | 1998-08-18 |
| JP3692681B2 true JP3692681B2 (en) | 2005-09-07 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP02248797A Expired - Lifetime JP3692681B2 (en) | 1997-02-05 | 1997-02-05 | Polyolefin resin cross-linked foam |
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| JP (1) | JP3692681B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102004004237C5 (en) * | 2004-01-27 | 2009-11-12 | Woco Industrietechnik Gmbh | Process for the production of microporous plastic products and the moldings, profiles and granules obtainable by this process |
| JP6696902B2 (en) * | 2015-03-31 | 2020-05-20 | 積水化学工業株式会社 | Crosslinked polyolefin resin foam |
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- 1997-02-05 JP JP02248797A patent/JP3692681B2/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| JPH10219016A (en) | 1998-08-18 |
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