JP4313889B2 - Biaxially stretched styrene resin sheet - Google Patents
Biaxially stretched styrene resin sheet Download PDFInfo
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- JP4313889B2 JP4313889B2 JP11790499A JP11790499A JP4313889B2 JP 4313889 B2 JP4313889 B2 JP 4313889B2 JP 11790499 A JP11790499 A JP 11790499A JP 11790499 A JP11790499 A JP 11790499A JP 4313889 B2 JP4313889 B2 JP 4313889B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、二軸延伸スチレン系樹脂シートに関し、さらに詳しくは、該シートの巻き取り時の耐ブロッキンブ性が良好で、前記シートの巻き取りロール輸送時の擦り傷の発生を抑制し、且つ、該シートの二次成形品を積み重ねた際の剥離性を向上させた二軸延伸スチレン系樹脂シートに関する。
【０００２】
【従来の技術】
二軸延伸スチレン系樹脂シートは、環境衛生、腰の強さ、透明性、成形性、回収性に優れている等の理由で軽量食品包装容器やその他の物品の包装に多く用いられている。しかし、この二軸延伸シートは、シート巻き取り時のブロッキング性が強く、また該シートの二次成形品は、積み重ねた状態で保存すると使用時に個々を剥離し難いという欠点がある。さらに、前記シートを熱板圧空成形する際に、加熱板及び金型に該シートに塗布した防曇剤やシリコーンオイルが付着しやすく、二次成形品の外観を損ねることがある。
【０００３】
この様なシート巻き取り時のブロッキング性、シートの二次成形品の剥離性を改善するために、従来より種々の検討がなされており、例えばスチレン系樹脂に不定形の酸化珪素微粉末を添加してシートを二軸延伸し、シート表面に前記微粉末を突出させる方法が知られている。
【０００４】
【発明が解決しようとする課題】
しかし、この様な不定形の酸化珪素微粉末をスチレン系樹脂に配合して得られる樹脂成分から二軸延伸により得られるシートを製造した場合には、前記のシリコーンオイルの金型等への付着を多少防止できるもその効果は十分でなく、また、酸化珪素微粉末同士が凝集しやすいため、均一に樹脂中に分散させることが難しく、シート中にフィッシュ・アイと呼ばれる凝集物の突起による外観不良が発生しやすい他、前記シートをロール状に巻き取った状態で輸送する際に、シート同士の擦れ合いによって微細な傷が発生しやすいものであった。
【０００５】
本発明が解決しようとする課題は、シートのブロッキング性や二次成形品の剥離性を改善すると共に、凝集物の突起、シリコーンオイルの塗布性に起因する外観不良を改善し、かつ、シート同士の擦れ合いによって生ずる微細な傷の防止、即ち耐スクラッチ性を改善することにある。
【０００６】
【課題を解決するための手段】
本発明等は、上記課題を解決すべく鋭意検討した結果、二軸延伸スチレン系樹脂シートに特定粒子径の球状無機系粒状体が配合させることにより、シリコーンオイルの塗布性が向上され、二軸延伸シート同士のブロッキング性を弱められ、また該シートの巻き取りロールの輸送時の擦り傷の発生を抑制し、該シートの二次成形品の積み重ね時の剥離性を向上させ、さらには熱板圧空成形機の加熱板及び金型への塗布剤の転写による汚れの発生が少なくなることを見出し、本発明を完成するに至った。
【０００７】
本発明で用いるスチレン系樹脂（Ａ）は、芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との二元共重合体である。前記芳香族ビニル系単量体としては、例えば、スチレン、α−メチルスチレン等が挙げられる。前記酸基含有ビニル系単量体としては、例えば、（メタ）アクリル酸等が挙げられる。前記酸無水物基含有ビニル系単量体としては、例えば、無水マレイン酸、無水イタコン酸等が挙げられる。
【０００８】
スチレン系樹脂（Ａ）として、芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との二元共重合体を用いた場合、二軸延伸シート及びその成形品の耐熱性及び耐油性が良好となる他、本発明の効果も極めて顕著なものとなる。即ち、この様な芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との二元共重合体は、二軸延伸シート及びその成形品の耐熱性及び耐油性に優れるものの、無機系粒状体の添加なしに使用した場合、該シート同士のブロッキングや二次成形品の剥離性が極度に低くなるという欠点を有していたが、本発明においては、この様な本来的にシートのブロッキングや二次成形品の剥離性に劣る当該二元共重合体を用いた場合において、優れた改善効果を発現するのであり、よって、当該二元共重合体を用いた場合には、二軸延伸シート及びその成形品の耐熱性及び耐油性と共に、シートのブロッキング性や二次成形品の剥離性、外観不良の改善、耐スクラッチ性等の諸性能を兼備させることができる。
【０００９】
この芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との二元共重合体の中でも特に前記二元共重合体における改善効果がより顕著なものとなり、また耐熱性、耐油性も極めて良好である点からスチレン−メタクリル酸共重合体であることが好ましい。
【００１０】
また、芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との二元共重合体における、芳香族ビニル系単量体と、酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体との存在比率は特に制限されるものではなく、原料単量体の量比として、両者の合計重量に対する酸基含有ビニル系単量体又は酸無水物基含有ビニル系単量体重量が５０重量％以下となる割合であればよいが、押出加工性及び回収性の観点から、なかでも１〜２０重量％の範囲がより好ましい。
【００１１】
また、上記スチレン系樹脂（Ａ）の重量平均分子量は、特に限定されるものではないが、押出加工性の観点から２０〜４５万が好ましい。前記スチレン系樹脂の製造方法は、特に限定されるものではなく、通常の重合方法を採用することができる。
【００１２】
次に、本発明で用いる球状無機系粒状体（Ｂ）としては、平均粒子径１〜２０μｍのものである。即ち、１μｍ未満の場合は、シート表面に適当な突起を形成することができずに、本発明の効果が発現されなくなり、その一方、２０μｍを越える場合には透明性の低下を招き外観不良を起こしやすくなる。これらの性能バランスに優れ、更に二次成形品の高い透明性も良好となる点から、２〜１０μｍの範囲がより好ましい。ここで、平均粒子径は、レーザー回折法により測定した５０％体積平均粒子径である。
【００１３】
次に球状無機系粒状体（Ｂ）の粒度分布として粒度分布幅が２．５以下であることが、シート表面の突起の均一性が良好となる点から好ましい。ここで、粒度分布とは、前記レーザー回折法により測定される９０％体積平均粒子径と１０％体積平均粒子径との比率、即ち、（９０％体積平均粒子径）／（１０％体積平均粒子径）で示される値である。
【００１４】
また、球状無機系粒状体（Ｂ）は前記の通り球状粒状体である。即ち、無機系粒状体の形状が不定形の場合は、シート表面に十分な粗度を与えるためには、無機系粒状体の添加量を多くする必要があり、シートの透明性を損なうとともに、シートの耐スクラッチ性が低下して該シートの巻き取りロール輸送時の擦り傷が発生しやすくなる。この様な球状粒状体は、具体的には長径と短径の比から算出されるアスペクト比が１〜１．５であることが好ましい。
【００１５】
また、シート表面に均一な突起を生じさせ、外観を一層向上させるにはより真球に近いものが好ましく、具体的には、アスペクト比が１〜１．２であることがより好ましい。
【００１６】
また、球状無機系粒状体（Ｂ）は、比表面積４００ｍ２／ｇ以上の多孔性粒子であることが、スチレン系樹脂（Ａ）との親和性が良好で、シート表面に均一な突起を生じさせることができ、且つ深絞り成形時に成形品角部に白化が生じ難くなる点から好ましい。
【００１７】
また、球状無機系粒状体（Ｂ）は、既述の通り無機系粒状体である。即ち、粒状体が有機物である場合、二軸延伸時、及び二次成形時に該粒状体が変形、埋没しやすくなり、本発明の効果が発現されなくなる。ここで、無機系粒状体としては、特に限定されるものではないが、球状シリカ、ガラスビーズ等、及びそれらの表面に化学的処理を施したもの等が挙げられるが、化学的に安定であり、触媒作用によって樹脂を変性させないこと、及び該シートへのシリコーンオイルの塗布性が良好であることから、酸化珪素を主体成分とする球状シリカが好ましい。
【００１８】
以上詳述したスチレン系樹脂（Ａ）及び球状無機系粒状体（Ｂ）を必須の構成成分とする本発明の二軸延伸スチレン系シートは、スチレン系樹脂（Ａ）中に球状無機系粒状体（Ｂ）を５０〜１０００ｐｐｍなる割合で添加することが好ましい。即ち、球状無機系粒状体（Ｂ）の添加量が５０ｐｐｍ以上において、二軸延伸シート表面の突起数が十分な水準となり、二次成形品の剥離性が一層良好なものとなる。１０００ｐｐｍ以下においては、該シート及びその二次成形品の透明性が良好なものとなる。これらの性能バランスに優れる点から５０〜５００ｐｐｍがより好ましく、更に好ましくは５０〜３００ｐｐｍなる範囲である。
【００１９】
本発明の二軸延スチレン系樹脂シートは、上記の通りスチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）を必須成分とする樹脂成分から構成されるものであり、具体的には、当該樹脂成分から得られる単層のものであってもよいが、当該樹脂成分から構成される樹脂層（以下、これを「Ｓ層」と略記する。）を両表層に有し、当該Ｓ層で挟まれる中心層（以下、これを「Ｃ層」と略記する。）を有する３層又は５層の多層シートであってもよい。即ち、Ｓ層を表層に配し二軸延伸シートの両表面に露出させることにより、本願発明の効果を発現することが可能となる。
【００２０】
この際、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）を必須成分とする樹脂層（Ｓ層）で挟まれる中心層（Ｃ層）としては、特に限定されるものではないが、表層樹脂との親和性が良好であることから、スチレン系樹脂（Ｃ）で構成されていることが好ましいが、Ｓ層とＣ層とが同一樹脂である必要はない。中心層（Ｃ層）に用いるスチレン系樹脂（Ｃ）としては、例えば、スチレン、α−メチルスチレン等の芳香族ビニル系単量体の単独重合物、又は、これらと共重合可能な他の重合性単量体との二元系以上の共重合体が挙げられる。尚、ここで、スチレン系樹脂（Ｃ）として、芳香族ビニル系単量体と他の重合性単量体との二元系以上の共重合体を用いる場合には、両者の単量体の合計重量に対して芳香族ビニル系単量体と共重合可能な他の重合性単量体を５０重量％以下なる範囲で用いて共重合させたものである。ここで、共重合可能な他の重合性単量体としては、（メタ）アクリル酸に代表される酸基含有ビニル系単量体、（メタ）アクリル酸アルキルエステルに代表されるエステル基含有ビニル系単量体、無水マレイン酸、無水イタコン酸に代表される酸無水物基含有ビニル系単量体等が挙げられる。また、５層のシートとしては、Ｓ層／Ｃ層／Ｓ層／Ｃ層／Ｓ層の層構成の構造のものが挙げられる。
【００２１】
前記３層又は５層の多層シートにおいては、従来の不定形微粒子を用いた多層シートでは二軸延伸する際に、表層樹脂中に分散している微粒子は、内層に埋没しやすく、単層シートと比較して、シート表面に突起を生じさせることが難しいため、該微粒子の含有量を増やす必要があったが、本発明においてはこの様な問題を招くことなく、良好な剥離性及び耐スクラッチ性を発現させることができる。
【００２２】
また、前記多層シートの製造方法は特に制限されるものでなく、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを必須成分とする組成物を、熱溶融押出後、二軸延伸する方法、或いは、該組成物およびその他の樹脂成分を熱溶融共押出、二軸延伸する方法が挙げられる。
【００２３】
ここで、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを必須成分とする組成物の調製方法は、特に限定されるものではないが、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを、ヘンシェルミキサー、タンブラーなどの撹拌装置を用いて混合する方法、及び前記混合物を押出機、ニーダー等で溶融混練する方法等が挙げられる。
【００２４】
スチレン系樹脂（Ａ）には、必要に応じて内部潤滑剤として添加する鉱油、スリップ剤、帯電防止剤、酸化防止剤、抗菌剤、紫外線吸収剤等を添加することができる。さらに、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを必須成分とする組成物には、耐衝撃ポリスチレン（ＨＩＰＳ）、スチレン−ブタジエン−スチレンブロック共重合体（ＳＢＳ）、スチレン−ブタジエン−（メタ）アクリル酸エステル共重合体（ＭＢＳ）等のスチレン変性ゴム類をシートの透明性を損なわない範囲内で混合することができる。上記スチレン変性ゴム類をスチレン系樹脂（Ａ）に添加することによって、該シートの深絞り成形時に成形品角部が白化しやすくなることから、その添加量は５％以下であることが好ましい。
【００２５】
また、中心層（Ｃ層）を形成する樹脂成分としても、前記スチレン系樹脂（Ｃ）を主成分とする場合には、前記各種添加剤及びスチレン変性ゴム類を併用することができる。
【００２６】
以上の様にして調製された樹脂成分から本発明の二軸延伸スチレン系樹脂シートを製造するには、上記スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを必須成分とする組成物を溶融混練後ダイスより押し出し、延伸処理して目的とする二軸延伸スチレン系樹脂シートとするか、或いは、スチレン系樹脂（Ａ）と球状無機系粒状体（Ｂ）とを必須成分とする組成物と、中心層（Ｃ層）とを形成する樹脂成分とを押出機内で２００〜３００℃なる条件下で溶融混練し、ダイスより押し出し、延伸処理して目的とする二軸延伸スチレン系樹脂シートとする。また、多層シートにする場合は、前記の通り、共押出後に延伸処理に供される。
【００２７】
延伸処理方法としては、特に制限されるものではないが、ダイスより押出された未延伸シートを、ロール間速度差及びテンターを利用した、同時二軸延伸又は逐次二軸延伸で行う方法が好ましい。延伸倍率は目的に応じ異なるが、通常面倍率で３〜１５倍、より好ましくは４〜１０倍である。また、逐次延伸の場合の流れ方向の延伸倍率は、１．２〜５倍、なかでも１．５〜４倍が好ましく、クロス方向の延伸倍率は１．２〜５倍、なかでも１．５〜３倍が好ましい。同時二軸延伸の各方向の延伸倍率は、１．５〜５倍、好ましくは２〜４倍である。
【００２８】
また、同時二軸延伸又は逐次二軸延伸における、温度条件は、特に制限されるものではないが、ＡＳＴＭ Ｄ−１５０４に準拠し測定される配向緩和応力が０．１５〜１．３ＭＰａとなる様に行うのが、延伸切れを防止でき、また、二次成形性が良好となる点から好ましい。
【００２９】
なお、該二軸延伸シートの表面には、防曇剤、帯電防止剤、シリコーンオイルを適宜塗布することができるが、本発明においては、特に本発明の効果が顕著なものとなること、即ち、シートのブロッキング性や二次成形品の剥離性の改善、耐スクラッチ性の改善効果等の諸効果が顕著なものとなる点からシリコーンオイルを塗布することが好ましい。特に本発明においては、シリコーンオイルをシート表面に塗布しても、加熱板及び金型へのシリコーンオイルの付着を防止でき、二次成形品の外観に優れたものとなる。
【００３０】
シリコーンオイルの塗布量は、特に制限されるものではないが、上記のシート性能を発揮させるためには、少なくとも片面に５〜５０ｍｇ／ｍ２の範囲で塗布することが好ましい。また、シリコーンオイルとしては、高温成形時に該シート表面を侵しにくいことから、ポリジメチルシロキサンが好ましい。
【００３１】
【実施例】
本発明の実施例及び比較例により詳細に説明するが、本発明の内容はこれらの実施例に限定されるものではない。なお、各評価項目は以下の要領により実施したものである。
【００３２】
［シートの透明性］
ＪＩＳ Ｋ７１０５でシートのヘイズ値を測定。
【００３３】
判定基準
◎；１％未満、○；１〜２％未満、△；２〜３％未満、×；３％以上
【００３４】
［シートの表面状態（表面粗度及び突起均一性）］
落写型偏光顕微鏡（１００倍）を用いてシート表面を観察し、表面粗度については、０．０１ｍｍ四方中にある平均突起数で評価した。
判定基準
○；２０個以上、△；１０〜２０個未満、×；１０個未満
また、突起均一性については、落写型偏光顕微鏡を用いてシート表面を観察した。比較例１、比較例２及び比較例５における顕微鏡写真を図１〜図３に示した。
【００３５】
［シリコーンオイルの塗布性］
２５℃のシリコーンエマルジョン液（１％シリコーンオイル、及び非イオン系界面活性剤を含む）に上記のサンプルを浸し、速度５ｍ／ｍｉｎ、圧力０．４ＭＰａのゴム製ニップロールで絞った後、ドライヤーで乾燥させた。それらのサンプルを蛍光Ｘ線分析計によってサンプル片面の平均シリコン塗布量を測定した。
【００３６】
判定基準
○；１５ｍｇ／ｍ２以上、△；１０〜１５ｍｇ／ｍ２未満、×；１０ｍｇ／ｍ２未満
【００３７】
［シートの耐スクラッチ性］
シリコーンオイルを１０〜２０ｍｇ／ｍ２塗布したサンプルの塗布面同士を重ね合わせて、３８９Ｐａの圧力になるようにシートに荷重をかけた状態で２０回擦り合わせて、ＪＩＳＫ７１０５でシートのヘイズ値を測定した。
判定基準
◎；４％未満、○；４〜８％未満、△；８〜１２％未満、×；１２％以上
【００３８】
［二次成形品の剥離性］
菓子用仕切トレーの成形品を２０枚重ねて、上から３．５ｋｇｆの荷重を一分間かけた時の高さをＴ１、次に荷重を取り除いて一分後の高さをＴ２として、式１に示される成形品高さの回復率（％）を指標として、二次成形品の剥離性評価を行った。
【００３９】
式１ 回復率（％）＝（Ｔ２−Ｔ１）／Ｔ１
判定基準
◎；１２０％以上、○；８０〜１２０％未満、△；４０〜８０％未満、×；４０％未満
【００４０】
比較例１
透明ポリスチレン（ＧＰＰＳ）（大日本インキ化学工業株式会社製造、商品名ディックスチレンＣＲ５６００）に、平均粒子径４．５μｍ、粒度分布幅１．９、比表面積５２０ｍ２／ｇ、アスペクト比１〜１．１の球状シリカ（富士シリシア化学株式会社製造、商品名サイロスフェアＣ−１５０４）を２００ｐｐｍなる割合で溶融混合した樹脂組成物をＴダイから押し出し、厚み１．０ｍｍのシートを作製した。次に、二軸延伸装置を用いて、該シートを１２０℃雰囲気中で、縦方向、横方向共に２．２倍延伸を行い、厚み０．２１ｍｍの二軸延伸スチレン系樹脂シートを得た。次いで、該シートの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。このシリコーンオイルを塗布した二軸延伸スチレン系樹脂シートについて、シートの透明性、シートの表面粗度、シートのシリコン塗布性、シートの耐スクラッチ性、二次成形品の剥離性及びシートの耐油性について評価した結果を表２に示す。シートの耐油性以外の各評価試験において優れた結果が得られたが、シートの耐油性が不十分であった。
【００４１】
実施例１
スチレン単量体に対してメタクリル酸を３重量％なる割合で共重合した樹脂（３％ＳＭＡＡ）（Ｍｗ＝２６万、Ｍｗ／Ｍｎ＝２．５）に、平均粒子径４．５μｍの球状シリカ（富士シリシア化学株式会社製造、商品名サイロスフェアＣ−１５０４）を２００ｐｐｍなる割合で溶融混合した樹脂組成物からなる厚み１．０ｍｍのシートを作製した。次に、二軸延伸装置を用いて、該シートを１２５℃雰囲気中で、縦方向、横方向共に２．２倍延伸を行い、厚み０．２１ｍｍの二軸延伸スチレン系樹脂シートを得た。次いで、該シートの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。
【００４２】
実施例２
スチレン単量体に対してメタクリル酸を１０重量％なる割合で共重合した樹脂（１０％ＳＭＡＡ）（Ｍｗ＝３０万、Ｍｗ／Ｍｎ＝２．５）に、平均粒子径４．５μｍの球状シリカ（富士シリシア化学株式会社製造、商品名サイロスフェアＣ−１５０４）を２００ｐｐｍなる割合で溶融混合した樹脂組成物からなる厚み１．０ｍｍのシートを作製した。次に、二軸延伸装置を用いて、該シートを１４０℃雰囲気中で、縦方向、横方向共に２．２倍延伸を行い、厚み０．２１ｍｍの二軸延伸スチレン系樹脂シートを得た。次いで、該シートの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。
【００４３】
実施例３
実施例２と同様の製法により、平均粒子径１０．０μｍ、粒度分布幅２．３、比表面積５２０ｍ２／ｇ、アスペクト比１〜１．１の球状シリカ（富士シリシア化学株式会社製造、商品名サイロスフェアＣ−１５１０）を１００ｐｐｍなる割合で分散させ、厚み０．２１ｍｍの二軸延伸スチレン系樹脂シートを得た。次いで、該シートの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。
【００４４】
実施例４
スチレン単量体に対してメタクリル酸を３重量％なる割合で共重合した樹脂（３％ＳＭＡＡ）（Ｍｗ＝２６万、Ｍｗ／Ｍｎ＝２．５）に、平均粒子径４．５μｍの球状シリカ（富士シリシア化学株式会社製造、商品名サイロスフェアＣ−１５０４）を２００ｐｐｍなる割合で溶融混合した樹脂組成物を両表層とし、透明ポリスチレン樹脂（大日本インキ化学工業株式会社、ディックスチレンＣＲ５６００）を該表層に挟まれた内層として共押出し、２種３層の分配機を通した後Ｔダイから押し出して、層構成比が２／９６／２なる割合の厚さ１．０ｍｍの多層シートを制作した。次に、二軸延伸装置を用いて、該シートを１２０℃雰囲気中で、縦方向、横方向共に２．２倍延伸して厚さ０．２１ｍｍの二軸延伸スチレン系樹脂積層シートを得た。次いで、該シートの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。
【００４５】
実施例１〜４のシリコーンオイルを塗布した二軸延伸スチレン系シートについて、シートの透明性、シートの表面粗度、シートのシリコン塗布性、シートの耐スクラッチ性及び二次成形品の剥離性について評価した結果を表１に示す。何れの実施例についても、各評価試験において優れた結果が得られた。
【００４６】
比較例２
比較例１と同様の製法により、平均粒子径６．８μｍの不定形シリカ（シオノギ製薬株式会社製造、商品名カープレックス＃８０）を分散させ、シリコーンオイルを塗布した厚さ０．２１ｍｍのＧＰＰＳ二軸延伸シートを得た。次いで、実施例１〜４と同様に各種試験を行った。結果を表２に示す。尚、シート表面を顕微鏡で観察した結果を図２に示す。シート表面に突起は存在するものの、大きさが不均一であることが解る。二次成形品の剥離性等は問題が無かったが、シートの耐スクラッチ性が著しく劣っていた。
【００４７】
比較例３
実施例１と同様の製法により、平均粒子径１．８μｍであって、表面に疎水化処理を施された不定形シリカ（富士シリシア化学株式会社製造、商品名サイロホービック２００）を分散させ、シリコーンオイルを塗布した厚さ０．２１ｍｍ、３％ＳＭＡＡ二軸延伸シートを得た。次いで、実施例１〜４と同様に各種試験を行った。結果を表２に示す。結果を表２に示す。シートの表面粗度が十分ではなく、二次成形品の剥離性が著しく劣っていた。
【００４８】
比較例４
実施例２と同様の製法により、粒状体が無添加の１０％ＳＭＡＡ樹脂を用いて（粒状体（Ｂ）は不使用）、シリコーンオイルを塗布した二軸延伸シートを得た。次いで、実施例１〜４と同様に各種試験を行った。結果を表２に示す。粒状体を添加していなため、シート表面に突起が存在せず、二次成形品の剥離性が著しく劣っていた。
【００４９】
比較例５
実施例２と同様の製法により、平均粒子径２．０μmの不定形シリカ（シオノギ製薬株式会社製造、商品名カープレックスＣＳ−７）を分散させ、シリコーンオイルを塗布した１０％ＳＭＡＡ二軸延伸シートを得た。次いで、実施例１〜４と同様に各種試験を行った。結果を表２に示す。また、得られたシートの顕微鏡写真を図３に示した。粒状体を添加したにもかかわらず、顕微鏡観察ではシート表面に突起がほとんど存在せず、二次成形品の剥離性が劣っているばかりか、シートの耐スクラッチ性も著しく劣っていた。
【００５０】
比較例６
透明ポリスチレン樹脂（ＧＰＰＳ）（大日本インキ化学工業株式会社製造、商品名ディックスチレンＣＲ５６００）に、平均粒子径２．０μｍの不定形シリカ（シオノギ製薬株式会社製造、商品名サイロスフェアＣ−１５０４）を２００ｐｐｍなる割合で溶融混合した樹脂組成物を両表層とし、微粒子非含有の前記ポリスチレン樹脂（ＣＲ５６００）を該表層に挟まれた内層として共押出し、２種３層の分配機を通した後Ｔダイから押し出して、層構成比が６／８８／６なる割合の厚さ１．０ｍｍの多層シートを制作した。次に、該シートを１２０℃雰囲気中で、縦方向、横方向共に２．２倍延伸して厚さ０．２１ｍｍの二軸延伸スチレン系樹脂積層シートを得た。さらに、該サンプルの両面にそれぞれ１０〜２０ｍｇ／ｍ２のシリコーンオイルを塗布した。次いで、実施例１〜４と同様に各種試験を行った。結果を表２に示す。シートの透明性は良好なものの、二次成形品の剥離性等の性能は不十分であった。
【００５１】
【表１】
【表２】
【本発明の効果】
本発明によれば、シートのブロッキング性や二次成形品の剥離性を改善すると共に、凝集物の突起凝、シリコーンオイルの塗布性に起因するによる外観不良を改善し、かつ、シート同士の擦れ合いによって生ずる微細な傷の防止、即ち耐スクラッチ性を改善することができる。
よって、該シートの二次成形加工時の作業性の向上が可能であるとともに、該シートの巻き取りロールの輸送時の擦り傷の発生を抑制できることから、二次成形品の不良率の減少も期待できる。
【図面の簡単な説明】
【図１】図１は、実施例１で得られたシートを落写型偏光顕微鏡で撮影した写真である。
【図２】図２は、比較例１で得られたシートを落写型偏光顕微鏡で撮影した写真である。
【図３】図３は、比較例４で得られたシートを落写型偏光顕微鏡で撮影した写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biaxially stretched styrene-based resin sheet, and more specifically, has good blocking resistance during winding of the sheet, suppresses the occurrence of scratches during transport of the winding roll of the sheet, and The present invention relates to a biaxially stretched styrene-based resin sheet that has improved peelability when stacked secondary sheet products.
[0002]
[Prior art]
Biaxially stretched styrene-based resin sheets are often used for packaging lightweight food packaging containers and other articles for reasons such as environmental hygiene, waist strength, transparency, moldability, and recoverability. However, this biaxially stretched sheet has a strong blocking property at the time of winding the sheet, and the secondary molded product of the sheet has a drawback that it is difficult to separate each other when used when stored in a stacked state. Further, when hot-pressing the sheet, the antifogging agent or silicone oil applied to the sheet is likely to adhere to the heating plate and the mold, which may impair the appearance of the secondary molded product.
[0003]
In order to improve the blocking property at the time of winding the sheet and the releasability of the secondary molded product of the sheet, various studies have been made conventionally. For example, an amorphous silicon oxide fine powder is added to a styrene resin. Then, a method is known in which the sheet is biaxially stretched and the fine powder protrudes from the sheet surface.
[0004]
[Problems to be solved by the invention]
However, when a sheet obtained by biaxial stretching is produced from a resin component obtained by blending such an irregularly shaped silicon oxide fine powder with a styrene resin, the silicone oil adheres to a mold or the like. However, the effect is not sufficient, and it is difficult to disperse uniformly in the resin because the silicon oxide fine powders tend to aggregate together, and the appearance due to the projections of aggregates called fish eyes in the sheet In addition to being prone to defects, when the sheet was transported in a roll shape, fine scratches were likely to occur due to friction between the sheets.
[0005]
The problem to be solved by the present invention is to improve the blocking property of the sheet and the peelability of the secondary molded product, improve the appearance defect due to the protrusion of the aggregate and the coating property of the silicone oil, and the sheets to each other It is to prevent fine scratches caused by rubbing, that is, to improve scratch resistance.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present invention and the like has improved the coating property of silicone oil by adding spherical inorganic particles having a specific particle diameter to the biaxially stretched styrene-based resin sheet, thereby improving the biaxial property. The blocking property between the stretched sheets is weakened, the occurrence of scratches during the transport of the take-up roll of the sheet is suppressed, the peelability at the time of stacking the secondary molded product of the sheet is improved, and the hot plate pressure It has been found that the occurrence of contamination due to transfer of the coating agent to the heating plate and mold of the molding machine is reduced, and the present invention has been completed.
[0007]
Styrenic resin (A),It is a binary copolymer of an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer. As the aromatic vinyl monomer,For example, styrene, α-methylstyrene, etc.Is mentioned. As the acid group-containing vinyl monomer, for example,(Meth) acrylic acidEtc. As the acid anhydride group-containing vinyl monomer, for example,Maleic anhydride, itaconic anhydrideetcIs mentioned.
[0008]
When a binary copolymer of an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer is used as the styrene resin (A), biaxial In addition to the heat resistance and oil resistance of the stretched sheet and the molded product thereof being good, the effects of the present invention are also extremely remarkable. That is, a binary copolymer of such an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer is a biaxially stretched sheet and a molded product thereof. Although it has excellent heat resistance and oil resistance, when used without the addition of inorganic particles, it has the disadvantage that the blocking between the sheets and the peelability of the secondary molded product become extremely low. In the invention, in the case of using such a binary copolymer that is inherently inferior in sheet blocking and releasability of the secondary molded product, an excellent improvement effect is expressed. When a copolymer is used, various properties such as sheet blocking properties, peelability of secondary molded products, improvement in appearance defects, scratch resistance, as well as heat resistance and oil resistance of biaxially stretched sheets and molded products thereof are used. Performance can be combined.
[0009]
Among the binary copolymers of this aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer, the improvement effect in the binary copolymer is more significant. A styrene-methacrylic acid copolymer is preferred from the standpoint that it becomes prominent and has extremely good heat resistance and oil resistance.
[0010]
Further, in the binary copolymer of an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer, the aromatic vinyl monomer and the acid group The abundance ratio with the vinyl-containing monomer or acid anhydride group-containing vinyl monomer is not particularly limited, and the amount ratio of the raw material monomers is the acid group-containing vinyl monomer with respect to the total weight of both. It is sufficient that the weight of the monomer or acid anhydride group-containing vinyl monomer is 50% by weight or less, but from the viewpoint of extrusion processability and recoverability, the range of 1 to 20% by weight is more preferable. .
[0011]
Moreover, the weight average molecular weight of the styrene resin (A) is not particularly limited, but is preferably 200 to 450,000 from the viewpoint of extrusion processability. The method for producing the styrene resin is not particularly limited, and a normal polymerization method can be employed.
[0012]
Next, the spherical inorganic particles (B) used in the present invention have an average particle diameter of 1 to 20 μm. That is, when the thickness is less than 1 μm, appropriate projections cannot be formed on the sheet surface and the effect of the present invention is not expressed. On the other hand, when the thickness exceeds 20 μm, the transparency is deteriorated and the appearance is deteriorated. It is easy to wake up. The range of 2-10 micrometers is more preferable from the point which is excellent in these performance balances, and also the high transparency of a secondary molded article becomes favorable. Here, the average particle diameter is a 50% volume average particle diameter measured by a laser diffraction method.
[0013]
Next, the particle size distribution width of the spherical inorganic particles (B) is preferably 2.5 or less from the viewpoint of good uniformity of protrusions on the sheet surface. Here, the particle size distribution is the ratio of the 90% volume average particle diameter and the 10% volume average particle diameter measured by the laser diffraction method, that is, (90% volume average particle diameter) / (10% volume average particle). (Diameter).
[0014]
The spherical inorganic particles (B) are spherical particles as described above. That is, when the shape of the inorganic particles is indefinite, it is necessary to increase the amount of the inorganic particles to give sufficient roughness to the sheet surface, which impairs the transparency of the sheet, The scratch resistance of the sheet is lowered and scratches are easily generated when the take-up roll of the sheet is transported. Specifically, such a spherical granular material preferably has an aspect ratio of 1 to 1.5 calculated from the ratio of the major axis to the minor axis.
[0015]
Moreover, in order to produce a uniform protrusion on the sheet surface and further improve the appearance, a material closer to a true sphere is preferable, and specifically, an aspect ratio of 1 to 1.2 is more preferable.
[0016]
The spherical inorganic particles (B) have a specific surface area of 400 m.2/ G or more porous particles have good affinity with the styrene resin (A), can produce uniform protrusions on the sheet surface, and whiten the corners of the molded product during deep drawing It is preferable from the point that it becomes difficult to occur.
[0017]
The spherical inorganic particles (B) are inorganic particles as described above. That is, when the granular material is an organic material, the granular material is easily deformed and embedded during biaxial stretching and secondary molding, and the effects of the present invention are not exhibited. Here, the inorganic particles are not particularly limited, and examples thereof include spherical silica, glass beads and the like, and those obtained by chemically treating the surface thereof, but are chemically stable. Spherical silica containing silicon oxide as a main component is preferable because the resin is not denatured by catalytic action and the coating property of silicone oil to the sheet is good.
[0018]
The biaxially stretched styrene-based sheet of the present invention comprising the styrene-based resin (A) and the spherical inorganic-based granular material (B) described above in detail as essential constituents is a spherical inorganic-based granular material in the styrene-based resin (A). It is preferable to add (B) at a ratio of 50 to 1000 ppm. That is, when the addition amount of the spherical inorganic particles (B) is 50 ppm or more, the number of protrusions on the surface of the biaxially stretched sheet becomes a sufficient level, and the peelability of the secondary molded product becomes even better. In 1000 ppm or less, transparency of this sheet | seat and its secondary molded product will become favorable. From the point which is excellent in these performance balance, 50-500 ppm is more preferable, More preferably, it is the range which is 50-300 ppm.
[0019]
The biaxially stretched styrene resin sheet of the present invention is composed of a resin component having the styrene resin (A) and the spherical inorganic particles (B) as essential components as described above. Specifically, Although it may be a single layer obtained from the resin component, it has a resin layer composed of the resin component (hereinafter, abbreviated as “S layer”) on both surface layers, and the S layer. It may be a three-layer or five-layer multilayer sheet having a central layer sandwiched between (hereinafter, abbreviated as “C layer”). That is, the effect of the present invention can be exhibited by arranging the S layer on the surface layer and exposing it on both surfaces of the biaxially stretched sheet.
[0020]
At this time, the center layer (C layer) sandwiched between the resin layers (S layer) having the styrene resin (A) and the spherical inorganic particles (B) as essential components is not particularly limited. Because of good affinity with surface resin, SuTyrene treeWith fat (C)Although it is preferable to be configured, the S layer and the C layer need not be the same resin.Examples of the styrene resin (C) used for the central layer (C layer) include homopolymers of aromatic vinyl monomers such as styrene and α-methylstyrene, or other polymerizations copolymerizable therewith. And a binary or higher copolymer with a functional monomer. Here, as the styrene resin (C), when using a binary or higher copolymer of an aromatic vinyl monomer and another polymerizable monomer, both monomers This is a copolymer obtained by using another polymerizable monomer copolymerizable with an aromatic vinyl monomer in an amount of 50% by weight or less based on the total weight. Here, other polymerizable monomers that can be copolymerized include acid group-containing vinyl monomers typified by (meth) acrylic acid and ester group-containing vinyl typified by (meth) acrylic acid alkyl ester. And acid anhydride group-containing vinyl monomers such as maleic anhydride, maleic anhydride, and itaconic anhydride.Examples of the five-layer sheet include those having a layer structure of S layer / C layer / S layer / C layer / S layer.
[0021]
In the three-layer or five-layer multilayer sheet, when the conventional multilayer sheet using irregular fine particles is biaxially stretched, the fine particles dispersed in the surface layer resin are easily embedded in the inner layer, and the single layer sheet. Compared to the above, it is difficult to generate protrusions on the surface of the sheet, so it was necessary to increase the content of the fine particles. However, in the present invention, good releasability and scratch resistance were obtained without causing such problems. Sex can be expressed.
[0022]
The method for producing the multilayer sheet is not particularly limited, and a composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components is subjected to biaxial stretching after hot melt extrusion. Or a method of hot-melt coextrusion and biaxial stretching of the composition and other resin components.
[0023]
Here, the preparation of the composition comprising styrene resin (A) and spherical inorganic particles (B) as essential components.MadeThe method is not particularly limited, and the styrene resin (A) and the spherical inorganic particles (B) are mixed using a stirring device such as a Henschel mixer or a tumbler, and the mixture is extruded. Examples thereof include a melt kneading method using a machine or a kneader.
[0024]
Mineral oil, a slip agent, an antistatic agent, an antioxidant, an antibacterial agent, an ultraviolet absorber and the like added as an internal lubricant can be added to the styrene resin (A) as necessary. Further, the composition comprising the styrene resin (A) and the spherical inorganic particles (B) as essential components includes impact-resistant polystyrene (HIPS), styrene-butadiene-styrene block copolymer (SBS), styrene- Styrene-modified rubbers such as butadiene- (meth) acrylic acid ester copolymer (MBS) can be mixed within a range that does not impair the transparency of the sheet. By adding the styrene-modified rubbers to the styrene-based resin (A), the corner of the molded product is likely to be whitened during the deep drawing of the sheet. Therefore, the addition amount is preferably 5% or less.
[0025]
Moreover, as a resin component which forms a center layer (C layer),AboveStyrenic resin (C) As a main component, the various additives and styrene-modified rubbers can be used in combination.
[0026]
As aboveMadeBiaxial stretching of the present invention from the obtained resin componentStyrenic resinIn order to produce a sheet, a composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components is extruded from a die after melt-kneading, and then stretched.do itThe target biaxially stretched styrene resin sheet is formed, or a composition containing a styrene resin (A) and spherical inorganic particles (B) as essential components and a central layer (C layer) are formed. Under the condition of 200 to 300 ° C. in the extrudersoMelt-kneading, extruding from a die, stretching processdo itTarget biaxially oriented styrene resin sheetTossThe Moreover, when making it a multilayer sheet, as above-mentioned, it uses for an extending | stretching process after co-extrusion.
[0027]
Although it does not restrict | limit especially as a extending | stretching processing method, The method of performing the unstretched sheet extruded from the die | dye by simultaneous biaxial stretching or sequential biaxial stretching using a roll speed difference and a tenter is preferable. The draw ratio varies depending on the purpose, but is usually 3 to 15 times, more preferably 4 to 10 times in terms of surface magnification. Further, the draw ratio in the flow direction in the case of sequential drawing is preferably 1.2 to 5 times, particularly 1.5 to 4 times, and the draw ratio in the cross direction is 1.2 to 5 times, particularly 1.5. ~ 3 times is preferable. The draw ratio in each direction of simultaneous biaxial stretching is 1.5 to 5 times, preferably 2 to 4 times.
[0028]
Further, the temperature condition in simultaneous biaxial stretching or sequential biaxial stretching is not particularly limited, but the orientation relaxation stress measured in accordance with ASTM D-1504 is 0.15 to 1.3 MPa. It is preferable to carry out the step because it is possible to prevent breakage of stretch and to improve the secondary formability.
[0029]
An antifogging agent, an antistatic agent, and silicone oil can be appropriately applied to the surface of the biaxially stretched sheet. In the present invention, the effects of the present invention are particularly remarkable. It is preferable to apply silicone oil from the standpoint that various effects such as the sheet blocking property, the releasability of the secondary molded product, and the scratch resistance improving effect become remarkable. In particular, in the present invention, even if silicone oil is applied to the sheet surface, adhesion of the silicone oil to the heating plate and the mold can be prevented, and the appearance of the secondary molded product is excellent.
[0030]
The application amount of the silicone oil is not particularly limited, but in order to exhibit the above sheet performance, it is 5 to 50 mg / m at least on one side.2It is preferable to apply in the range. Further, as the silicone oil, polydimethylsiloxane is preferable because it does not easily attack the surface of the sheet during high temperature molding.
[0031]
【Example】
Examples and comparative examples of the present invention will be described in detail, but the contents of the present invention are not limited to these examples. Each evaluation item was carried out according to the following procedure.
[0032]
[Transparency of sheet]
The haze value of the sheet is measured according to JIS K7105.
[0033]
Judgment criteria
◎: Less than 1%, ○: Less than 1-2%, △: Less than 2-3%, x: 3% or more
[0034]
[Surface condition (surface roughness and protrusion uniformity)]
The surface of the sheet was observed using a reflection-type polarizing microscope (100 times), and the surface roughness was evaluated by the average number of protrusions in a 0.01 mm square.
Judgment criteria
○: 20 or more, Δ: less than 10-20, x: less than 10
Further, regarding the projection uniformity, the surface of the sheet was observed using a episcopic polarizing microscope.Comparative Example 1Comparative example2And comparative examples5The photomicrographs at are shown in FIGS.
[0035]
[Applicability of silicone oil]
Immerse the above sample in a silicone emulsion at 25 ° C (including 1% silicone oil and nonionic surfactant), squeeze it with a rubber nip roll at a speed of 5 m / min and a pressure of 0.4 MPa, and then dry it with a dryer. I let you. The average silicon coating amount on one side of each sample was measured with a fluorescent X-ray analyzer.
[0036]
Judgment criteria
○: 15 mg / m2Or more; Δ: 10 to 15 mg / m2Less than, x; 10 mg / m2Less than
[0037]
[Scratch resistance of sheet]
10-20 mg / m of silicone oil2The coated surfaces of the coated samples were overlapped and rubbed 20 times with a load applied to the sheet so that the pressure was 389 Pa, and the haze value of the sheet was measured with JISK7105.
Judgment criteria
◎: Less than 4%, ○: Less than 4-8%, Δ: Less than 8-12%, X: 12% or more
[0038]
[Peelability of secondary molded product]
20 pieces of confectionery partition trays are stacked, and the height when a load of 3.5 kgf is applied from the top for 1 minute is T1, and then the load is removed and the height after 1 minute is T2. The peelability of the secondary molded product was evaluated using the recovery rate (%) of the molded product height shown in FIG.
[0039]
Formula 1 Recovery rate (%) = (T2-T1) / T1
Judgment criteria
◎; 120% or more, ○; 80 to less than 120%, Δ; 40 to less than 80%, ×; less than 40%
[0040]
ComparisonExample 1
Transparent polystyrene (GPPS) (manufactured by Dainippon Ink Chemical Co., Ltd., trade name: Dick Styrene CR5600) has an average particle size of 4.5 μm, a particle size distribution width of 1.9, and a specific surface area of 520 m.2/ G, a resin composition in which spherical silica (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Cyrossphere C-1504) having an aspect ratio of 1 to 1.1 is melt-mixed at a ratio of 200 ppm is extruded from a T die and has a thickness of 1.0 mm. A sheet of was prepared. Next, using a biaxial stretching apparatus, the sheet was stretched 2.2 times in the longitudinal direction and the lateral direction in a 120 ° C. atmosphere to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Then, 10-20 mg / m on each side of the sheet2The silicone oil was applied.About biaxially stretched styrene resin sheet coated with this silicone oil, sheet transparency, sheet surface roughness, sheet silicone coating property, sheet scratch resistance, secondary molded product peelability and sheet oil resistance Table 2 shows the results of the evaluation. Although excellent results were obtained in each evaluation test other than the oil resistance of the sheet, the oil resistance of the sheet was insufficient.
[0041]
Example1
Spherical silica with an average particle diameter of 4.5 μm is added to a resin (3% SMAA) (Mw = 260,000, Mw / Mn = 2.5) copolymerized with 3% by weight of methacrylic acid with respect to the styrene monomer. A sheet having a thickness of 1.0 mm made of a resin composition obtained by melt-mixing (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Cyrossphere C-1504) at a ratio of 200 ppm was prepared. Next, using a biaxial stretching apparatus, the sheet was stretched 2.2 times in the longitudinal direction and the lateral direction in an atmosphere of 125 ° C. to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Then, 10-20 mg / m on each side of the sheet2The silicone oil was applied.
[0042]
Example2
Resin (10% SMAA) (Mw = 300,000, Mw / Mn = 2.5) copolymerized with 10% by weight of methacrylic acid with respect to styrene monomer, and spherical silica with an average particle size of 4.5 μm A sheet having a thickness of 1.0 mm made of a resin composition obtained by melt-mixing (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Cyrossphere C-1504) at a ratio of 200 ppm was prepared. Next, using a biaxial stretching apparatus, the sheet was stretched 2.2 times in the longitudinal direction and the lateral direction in an atmosphere of 140 ° C. to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Then, 10-20 mg / m on each side of the sheet2The silicone oil was applied.
[0043]
Example3
Example2By the same production method, the average particle size 10.0 μm, the particle size distribution width 2.3, the specific surface area 520 m2/ G, spherical silica having an aspect ratio of 1 to 1.1 (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Cyrossphere C-1510) is dispersed at a rate of 100 ppm, and a biaxially stretched styrene resin sheet having a thickness of 0.21 mm is obtained. Obtained. Then, 10-20 mg / m on each side of the sheet2The silicone oil was applied.
[0044]
Example4
Spherical silica with an average particle diameter of 4.5 μm is added to a resin (3% SMAA) (Mw = 260,000, Mw / Mn = 2.5) copolymerized with 3% by weight of methacrylic acid with respect to the styrene monomer. A resin composition obtained by melting and mixing (Fuji Silysia Chemical Co., Ltd., trade name Cyrossphere C-1504) at a ratio of 200 ppm is used as both surface layers, and transparent polystyrene resin (Dainippon Ink Chemical Co., Ltd., Dick Styrene CR5600) Co-extruded as an inner layer sandwiched between surface layers, passed through a distributor of two types and three layers, and then extruded from a T die to produce a multilayer sheet having a thickness of 1.0 mm with a layer composition ratio of 2/96/2 . Next, using a biaxial stretching apparatus, the sheet was stretched 2.2 times in the longitudinal and lateral directions in an atmosphere of 120 ° C. to obtain a biaxially stretched styrene-based resin laminated sheet having a thickness of 0.21 mm. . Then, 10-20 mg / m on each side of the sheet2The silicone oil was applied.
[0045]
Example 14Of the biaxially stretched styrene-based sheet coated with the above silicone oil, the results of evaluating the transparency of the sheet, the surface roughness of the sheet, the silicone coating property of the sheet, the scratch resistance of the sheet and the peelability of the secondary molded product are shown. It is shown in 1. For any of the examples, excellent results were obtained in each evaluation test.
[0046]
Comparative example2
ComparisonIn the same manner as in Example 1, an amorphous silica (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name Carplex # 80) having an average particle size of 6.8 μm was dispersed, and a 0.21 mm thick GPPS biaxial coated with silicone oil A stretched sheet was obtained. Then Examples 1 to4Various tests were conducted in the same manner as above. The results are shown in Table 2. In addition, the result of having observed the sheet | seat surface with the microscope is shown in FIG. It can be seen that although the protrusions are present on the sheet surface, the sizes are not uniform. There was no problem with the peelability of the secondary molded product, but the scratch resistance of the sheet was remarkably inferior.The.
[0047]
Comparative example3
Example1In the same way as above, an amorphous silica (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Silo Hovic 200) having an average particle size of 1.8 μm and a surface subjected to hydrophobic treatment is dispersed, The applied thickness was 0.21 mm, and a 3% SMAA biaxially stretched sheet was obtained. Then Examples 1 to4Various tests were conducted in the same manner as above. The results are shown in Table 2. The results are shown in Table 2. The surface roughness of the sheet is not sufficient, and the peelability of the secondary molded product is extremely poor.The.
[0048]
Comparative example4
Example2By the same manufacturing method, the biaxially stretched sheet which apply | coated the silicone oil was obtained using the 10% SMAA resin to which a granular material is not added (granular body (B) is not used). Then Examples 1 to4Various tests were conducted in the same manner as above. The results are shown in Table 2. Since no granular material is added, there are no protrusions on the sheet surface, and the peelability of the secondary molded product is remarkably inferior.The.
[0049]
Comparative example5
Example210% SMAA biaxially stretched sheet coated with silicone oil was obtained by dispersing amorphous silica having an average particle size of 2.0 μm (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name Carplex CS-7) by the same production method as above. . Then Examples 1 to4Various tests were conducted in the same manner as above. The results are shown in Table 2. Moreover, the microscope picture of the obtained sheet | seat was shown in FIG. Despite the addition of granules, the microscopic observation shows almost no protrusions on the sheet surface, not only the peelability of the secondary molded product is poor, but also the scratch resistance of the sheet is extremely poor.The.
[0050]
Comparative example6
Transparent polystyrene resin (GPPS) (manufactured by Dainippon Ink & Chemicals, Inc., trade name: Dick Styrene CR5600) and amorphous silica having an average particle diameter of 2.0 μm (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name: Cyrossphere C-1504) The resin composition melt-mixed at a ratio of 200 ppm is used as both surface layers, and the polystyrene resin (CR5600) containing no fine particles is coextruded as an inner layer sandwiched between the surface layers, and after passing through a two-type / three-layer distributor, a T-die And a multilayer sheet having a thickness of 1.0 mm with a layer composition ratio of 6/88/6 was produced. Next, the sheet was stretched 2.2 times in the longitudinal direction and the lateral direction in a 120 ° C. atmosphere to obtain a biaxially stretched styrene resin laminated sheet having a thickness of 0.21 mm. Furthermore, 10-20 mg / m on each side of the sample2The silicone oil was applied. Then Examples 1 to4Various tests were conducted in the same manner as above. The results are shown in Table 2. Although the transparency of the sheet is good, the performance such as peelability of the secondary molded product is insufficient.Was.
[0051]
[Table 1]
[Table 2]
[Effect of the present invention]
According to the present invention, the blocking property of the sheet and the releasability of the secondary molded product are improved, the appearance defect due to the protrusion of the aggregate and the coating property of the silicone oil is improved, and the sheets are rubbed together. It is possible to prevent fine scratches caused by mating, that is, improve scratch resistance.
Therefore, it is possible to improve the workability at the time of secondary forming of the sheet and to suppress the generation of scratches during transportation of the take-up roll of the sheet. it can.
[Brief description of the drawings]
FIG. 1 is a photograph of the sheet obtained in Example 1 taken with a episcopic polarization microscope.
FIG. 2 is a photograph of the sheet obtained in Comparative Example 1 taken with a episcopic polarization microscope.
FIG. 3 is a photograph of the sheet obtained in Comparative Example 4 taken with a episcopic polarization microscope.
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11790499A JP4313889B2 (en) | 1999-04-26 | 1999-04-26 | Biaxially stretched styrene resin sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11790499A JP4313889B2 (en) | 1999-04-26 | 1999-04-26 | Biaxially stretched styrene resin sheet |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2000309645A JP2000309645A (en) | 2000-11-07 |
| JP2000309645A5 JP2000309645A5 (en) | 2006-06-08 |
| JP4313889B2 true JP4313889B2 (en) | 2009-08-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP11790499A Expired - Lifetime JP4313889B2 (en) | 1999-04-26 | 1999-04-26 | Biaxially stretched styrene resin sheet |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5020124B2 (en) * | 2008-03-07 | 2012-09-05 | 旭化成ケミカルズ株式会社 | Styrenic resin film |
| JP6085533B2 (en) * | 2013-07-19 | 2017-02-22 | サンディック株式会社 | Biaxially stretched styrene resin sheet and molded product thereof |
| JP6481848B2 (en) * | 2014-07-30 | 2019-03-13 | Dic株式会社 | Styrene resin composition, biaxially stretched styrene resin sheet and molded article |
| JP6481847B2 (en) * | 2014-07-30 | 2019-03-13 | Dic株式会社 | Styrene resin sheet and molded body using the same |
| JP6536873B2 (en) * | 2014-11-18 | 2019-07-03 | Dic株式会社 | LAMINATE AND MOLDED BODY USING THE SAME |
| WO2017029936A1 (en) * | 2015-08-17 | 2017-02-23 | Dic株式会社 | Styrene resin composition, biaxially stretched styrene resin sheet and molded body |
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1999
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