JP2004067955A - Anticlouding styrene type transparent resin sheet and its formed product - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、防曇効果、シート外観、シートの高温多湿時の保管性に優れた防曇性スチレン系透明樹脂シート及びその成形品に関する。更に詳しくは包装材分野等に広く用いられているスチレン系透明樹脂シートに対し、防曇効果、シート外観、夏期の倉庫保管を考慮したシートの高温多湿時の保管性に優れた特性を付与したスチレン系透明樹脂シート及びその成形品に関するものである。
【０００２】
【従来の技術】
スチレン系透明樹脂シートやその成形品は包装、被覆材として広く使用されているが、その表面が疎水性の為に気温や湿度の変化により凝集した水分が微小水滴となり表面に付着する、いわゆる曇りが発生することがある。その曇りにより収納物の見分けが困難となり、商品価値を低下させる原因となる場合が多かった。
【０００３】
この問題を解決しようと、特開平１０−３０９７８５号公報ではショ糖脂肪酸エステルとメチルセルロースの混合物を用いることが記載されているが防曇効果、シート外観、夏期の倉庫保管を考慮したシートの高温多湿時の保管性のバランスに優れたとは言えなかった。
【０００４】
【発明が解決しようとする課題】
本発明は、上記のような技術状況の基で、防曇効果、シート外観、夏期の倉庫保管を考慮したシートの高温多湿時の保管性に優れたスチレン系透明樹脂シート及びその成形品を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明者らは、上記の課題を解決すべく鋭意検討を重ねた結果、特定の構成からなる防曇剤を使用することによって本発明に達したものである。すなわち、本発明は、スチレン系透明樹脂シートをショ糖ラウリン酸エステル７０〜９９質量％とＨＬＢが１２以上のショ糖ステアリン酸エステル３０〜１質量％を含有してなる防曇剤で表面処理して得た防曇性スチレン系透明樹脂シート及びそのシートを用いて得た成形品とすることによって課題を解決したものである。
【０００６】
以下に本発明を詳しく説明する。
本発明の防曇剤はショ糖ラウリン酸エステルとＨＬＢ（Ｈｙｄｒｏｐｈｉｌｅ−Ｌｉｐｏｐｈｉｌｅ Ｂａｌａｎｃｅ）が１２以上のショ糖ステアリン酸エステルを必須とする。本発明のショ糖ラウリン酸エステルはラウリン酸成分の割合は、５０質量％以上であるが、好ましくは５５質量％以上、更に好ましくは６５質量％以上であるものが好ましい。ラウリン酸としての割合が５０質量％以上のショ糖ラウリン酸エステルを使用した場合、表面処理性に優れ、更に防曇効果にも優れる。ラウリン酸以外の成分として例えば、カプロン酸、カプリル酸、ラウリン酸、ミスチリン酸、パルミチン酸、ステアリン酸、ベヘニン酸、モンタン酸などの炭素数６〜３０程度の飽和脂肪酸、リンデン酸、パルミトオレイン酸、オレイン酸、エライジン酸、イソオレイン酸、エルカ酸、リノール酸、リノレン酸などの炭素数１０〜２４程度の不飽和脂肪酸が挙げられ、これら脂肪酸は単独でも併用してもよい。
【０００７】
本発明のＨＬＢが１２以上のショ糖ステアリン酸エステルはステアリン酸成分の割合が５０質量％以上であるが、好ましくは５５質量％以上、更に好ましくは６５質量％以上であるものが好ましい。ステアリン酸成分としての割合が５０質量％以上のショ糖ステアリン酸エステルを使用した場合、高温多湿時の保管性に優れる傾向が見られる。その他の成分としてはパルミチン酸、ミスチリン酸等の単独でも併用でも構わない。
【０００８】
本発明は、ＨＬＢが１２以上のショ糖ステアリン酸エステルを使用することが必須であり、好ましくはＨＬＢが１３以上、特に好ましくはＨＬＢが１４以上である。ＨＬＢが１２より小さいと水への溶解性に劣る。その為、水溶液でシートに塗布する場合シート表面への均一な表面処理が難しく、塗布ムラが発生し易くなる。なお、ＨＬＢが１２未満のショ糖ステアリン酸エステルを含有することもできるが、その場合用いる全ショ糖ステアリン酸エステル中において、ＨＬＢが１２以上の割合が７０質量％以上であることが好ましい。
【０００９】
本発明の防曇剤中のショ糖ラウリン酸エステルとＨＬＢが１２以上のショ糖ステアリン酸エステルの割合は、ショ糖ラウリン酸エステルが７０〜９９質量％、ショ糖ステアリン酸エステル３０〜１質量％である。好ましくはショ糖ラウリン酸エステルが７５〜９７質量％、ショ糖ステアリン酸エステル２５〜３質量％、更に好ましくはショ糖ラウリン酸エステルが８０〜９４質量％、ショ糖ステアリン酸エステル２０〜６質量％である。ショ糖ラウリン酸エステルが７０質量％より小さいと防曇効果に劣る。また、ショ糖ステアリン酸エステルが１質量％より小さいと高温多湿時の保管性に劣り、３０質量％より大きいと防曇効果に劣る。
【００１０】
スチレン系透明樹脂シートの表面を防曇剤で処理する際には、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルを溶媒に溶解した溶液として用いる。溶媒としては水、アルコール等が用いられるが特にこれらに限定されるものではない。取扱い上は水が好ましい。その場合、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルの溶液濃度は特に限定されることはないが０．０１〜１０質量％が好ましい。
【００１１】
本発明の防曇性スチレン系透明樹脂シートに用いるスチレン系透明樹脂シートとは、スチレン系透明樹脂を成形加工して得た防曇剤で処理する前のシートである。スチレン系透明樹脂には、スチレン系単量体の単独重合体、スチレン系単量体の共重合体、スチレン系単量体に共重合可能な単量体を共重合して得た共重合体及びそれらの混合物が挙げられる。
【００１２】
上記の（共）重合体に用いられるスチレン系単量体にはスチレン、α−メチルスチレン、ｐ−メチルスチレン、ビニルトルエン、ｔ−ブチルスチレン等が挙げられ、また、スチレン系単量体と共重合可能な単量体としてはアクリル酸、アクリル酸エチル、アクリル酸メチル、アクリル酸ブチル、アクリル酸２−エチルヘキシル、アクリロニトリル、メタクリル酸、メタクリル酸エチル、メタクリル酸メチル、メタクリル酸ブチル、メタクリル酸２−エチルヘキシル、１，３−ブタジエン、２−メチル−１，３−ブタジエン（イソプレン）等が挙げられる。
【００１３】
これらスチレン系単量体の単独重合体又は、スチレン系単量体の共重合体としてはスチレンを重合して得られるＧＰ（一般用）ポリスチレンが好ましい。また、スチレン系単量体に共重合可能な単量体を共重合して得た共重合体としては、メタクリル酸−スチレン共重合体、、メタクリル酸メチル−スチレン共重合体、メタクリル酸メチル−メタクリル酸−スチレン共重合体、アクリロニトリル−スチレン共重合体、スチレン−ブタジエンブロック共重合体が好ましい。
【００１４】
また、ブタジエン系ゴム存在下でスチレン系単量体及び／又はスチレン系単量体と共重合可能な単量体を重合して得た重合体を透明性を損なわない範囲で上記のスチレン系単量体を必須とする（共）重合体に混合して用いることもできる。ブタジエン系ゴムにはハイシスポリブタジエン、ローシスポリブタジエン、スチレン−ブタジエンゴム、スチレン−ブタジエンブロックゴム、スチレン−ブタジエン−スチレンブロックゴム、部分水添ポリブタジエンゴム等が挙げられる。更に、スチレン系単量体及びスチレン系単量体と共重合可能な単量体としては、前記で挙げた単量体を用いることが出来る。
なお、重合に用いる単量体やブタジエン系ゴムは少なくとも１種類以上を用いることができる。これらの透明性を損なわない範囲で混合できる重合体としてはゴム変性耐衝撃性ポリスチレン（ＨＩＰＳ）が好ましい。
【００１５】
スチレン系透明樹脂をシートに加工する方法は特に限定されることはなく、１軸延伸法、２軸延伸法、多軸延伸法、共押出法、積層法等の常法が挙げられる。また、シートを防曇処理するにはシートの表面をコロナ放電処理法、オゾン処理法、プラズマ処理法等で改質したものが好ましい。
【００１６】
防曇剤処理液をスチレン系透明樹脂シートに処理する方法は特に限定されることはなく、簡便にはロールコーター、ナイフコーター、グラビアロールコーター等を用い塗布する方法が挙げられる。また、噴霧、浸漬等を採用することも出来る。
【００１７】
防曇剤処理した本発明のスチレン系透明樹脂シート表面の防曇剤の固形分は好ましくは０．００５〜０．５ｇ／ｍ２ 、更に好ましくは０．０１〜０．４５ｇ／ｍ２、特に好ましくは０．０１〜０．４ｇ／ｍ２ である。チレン系透明樹脂シートの防曇剤の固形分が０．００５ｇ／ｍ２ より少ないと防曇効果に劣る傾向が見られ、また、０．５ｇ／ｍ２ より多いとシート表面の塗工ムラが目立ち易く、そのシートを成形した成形品の透明性が低下し易い。
【００１８】
本発明の防曇性スチレン系透明樹脂シートとは食料品の包装材或いは被覆材として使用されるので、この防曇性スチレン系透明樹脂シートを通して収納物が確認出来る透明性が必要である。また、この防曇性スチレン系透明樹脂シートの厚みは特に限定されることはなく、一般に１００μｍ〜１０ｍｍである。このシートは成形して容器にも用いられる。また、該防曇性スチレン系透明樹脂シートの透明性として好ましくはＨａｚｅ（ヘーズ）が１０以下であり、更に好ましくはＨａｚｅが５以下である。
【００１９】
本発明の成形品とは防曇性スチレン系透明樹脂シートを圧空成形、真空成形、真空圧空成形等を用いて成形された食料品を包装する蓋容器やフードパックである。
【００２０】
【実施例】
以下に実施例により本発明を説明するが、本発明はこれら実施例によって制限されるものではない。
【００２１】
実施例１
スチレン系透明樹脂シートは、縦方向に２．５倍、横方向に２．５倍延伸した厚み０．３ｍｍの２軸延伸ＧＰポリスチレンシートを用いた。なお、２軸延伸ＧＰポリスチレンシートのＨａｚｅは日本電色工業社製測定機ＮＤＨ−１００１ＤＰにて測定したが、２．０％未満であった。
また、防曇剤としてはラウリン酸が７０質量％であるショ糖ラウリン酸エステルで、かつそのショ糖ラウリン酸エステルの４０質量％水溶液を用い、ＨＬＢが１５でステアリン酸が７０質量％であるショ糖ステアリン酸エステルを用いて、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルを固形分割合で９５質量％と５質量％になるように調整して得た。更にこの防曇剤を１．５質量％水溶液に希釈して、シート表面の防曇剤の固形分が０．１ｇ／ｍ２ に塗布したシートを得た。また、そのシートを用い、蓋容器（２００ｍｍ長×１２０ｍｍ幅×５０ｍｍ高さ）を成形した。なお、ショ糖ラウリン酸エステルの４０質量％水溶液に三菱化学フーズ社製リョートーシュガーエステルＬＷＡ−１５７０を、ショ糖ステアリン酸エステルにＨＬＢが１５の三菱化学フーズ社製リョートーシュガーエステルＳ−１５７０を用いた。表１に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。
【００２２】
実施例２
防曇剤としては実施例１で用いたショ糖ラウリン酸エステル、ショ糖ステアリン酸エステルを用い、固形分割合をそれぞれ９０質量％と１０質量％になるように調整して得た。この防曇剤を用いた以外は実施例１と同様に行った。表１に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。
【００２３】
実施例３
防曇剤としては実施例１で用いたショ糖ラウリン酸エステル、ショ糖ステアリン酸エステルと、他にパルミチン酸が８０質量％であるショ糖パルミチン酸エステルを用い、固形分割合をそれぞれ８５質量％と１２質量％と３質量％になるように調整して得た。この防曇剤を用いた以外は実施例１と同様に行った。なお、ショ糖パルミチン酸エステルに三菱化学フーズ社製リョートーシュガーエステルＰ−１５７０を用いた。表１に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。
【００２４】
実施例４
防曇剤としては実施例１で用いたショ糖ラウリン酸エステル、ショ糖ステアリン酸エステルと、他にＨＬＢが９でステアリン酸が７０質量％であるショ糖ステアリン酸エステルを用い、固形分割合をそれぞれ７５質量％と１５質量％と１０質量％になるように調整して得た。この防曇剤を用いた以外は実施例１と同様に行った。なお、ＨＬＢが９のショ糖ステアリン酸エステルに三菱化学フーズ社製リョートーシュガーエステルＳ−９７０を用いた。表１に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。
【００２５】
実施例５
スチレン系透明樹脂シートに縦方向に２．５倍、横方向に２．５倍延伸した厚み０．３ｍｍの２軸延伸メタクリル酸−スチレン共重合体シート（スチレン系透明樹脂はスチレン９７質量％とメタクリル酸３質量％）を用いた以外は実施例２と同様に行った。表１に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。なお、２軸延伸シートのＨａｚｅは日本電色工業社製測定機ＮＤＨ−１００１ＤＰにて測定したが、２．０％未満であった。
【００２６】
比較例１
防曇剤としては実施例１で用いたショ糖ラウリン酸エステルの４０質量％水溶液を用い、ショ糖ステアリン酸エステルに実施例１で用いたＨＬＢが１５のショ糖ステアリン酸エステルを用い、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルの固形分割合をそれぞれ５質量％と９５質量％となるように調整して得た。この防曇剤を用いた以外は実施例１と同様行った。表２に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。防曇効果に劣ることが分かる。
【００２７】
比較例２
防曇剤としては実施例１で用いたショ糖ラウリン酸エステルの４０質量％水溶液を用い、ショ糖ステアリン酸エステルに実施例１で用いたＨＬＢが１５のショ糖ステアリン酸エステルを用い、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルの固形分割合をそれぞれ９９．５質量％と０．５質量％となるように調整して得た。この防曇剤を用いた以外は実施例１と同様行った。表２に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。高温多湿時の保管性に劣ることが分かる。
【００２８】
比較例３
防曇剤としては実施例１で用いたショ糖ラウリン酸エステルの４０質量％水溶液と、実施例４で用いたＨＬＢが９のショ糖ステアリン酸エステルを用い、ショ糖ラウリン酸エステルとショ糖ステアリン酸エステルの固形分割合をそれぞれ９０質量％と１０質量％となるように調整して得た。この防曇剤を用いた以外は実施例１と同様行った。表２に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。シート外観に劣ることが分かる。
【００２９】
比較例４
防曇剤としては実施例１で用いたショ糖ラウリン酸エステルの４０質量％水溶液と、他にメチルセルロースを用い、固形分割合でそれぞれ８５質量％と１５質量％となるように調整して得た。更にこの防曇剤を０．５質量％水溶液に希釈してシート表面の防曇剤の固形分が０．０３ｇ／ｍ２ に塗布したシートを得た。このシートを用いた以外は実施例１と同様行った。表２に防曇剤の固形分の配合割合を質量％で示し、得られた物性も示した。高温多湿時の保管性に劣ることが分かる。
【００３０】
なお、実施例における物性測定は以下の通り実施した。
（１）シート外観：各実施例で得られた防曇性スチレン系透明樹脂シート１０枚（各一枚が縦４００ｍｍ×横４００ｍｍ）を用い、目視で１０枚の防曇性スチレン系透明樹脂シートの塗り斑点の個数をカウントし、１枚当たりの平均塗り斑点の個数で評価した。
◎：塗り斑点が０から５個あった。
○：塗り斑点が６から２０個あった。
△：塗り斑点が２１から５０個あった。
×：塗り斑点が５１個以上あった。
【００３１】
（２）高温多湿時の保管性：各実施例で得られた防曇性スチレン系透明樹脂シート３０枚（各一枚が縦４００ｍｍ×横４００ｍｍ）を重ね、質量５ｋｇの荷重をかけた。この質量５ｋｇの荷重をかけた３０枚の防曇性スチレン系透明樹脂シートを温度５０℃、湿度７０％に調整したナガノ科学機械製作所製の恒温恒湿槽（ＬＨ−３１−１５）に１週間放置した。１週間後、取り出し、３０枚重ねの防曇性スチレン系透明樹脂シートの６枚目から１５枚目の１０枚を取り出し、それぞれのシートの中央部分のＨａｚｅを日本電色工業社製測定機ＮＤＨ−１００１ＤＰにて測定した。その平均のＨａｚｅで評価した。
◎：Ｈａｚｅが２．０％未満
○：Ｈａｚｅが２．０から３．５％
△：Ｈａｚｅが３．５より大きく５．０％以下
×：Ｈａｚｅが５．０％より大きい
【００３２】
（３）防曇効果▲１▼：各実施例で得た防曇性スチレン系透明樹脂シートを関西自動成型機（株）製の真空圧空成形機ＰＫ４００を用い、成型温度１２５℃で天面が平らな蓋容器（２００ｍｍ長×１２０ｍｍ幅×５０ｍｍ高）を１０個成型した。その蓋を温度４０℃のお湯を張ったＰＳＰ（ポリスチレンペーパー）容器の上にそれぞれ張り付けた後、温度５℃の冷蔵庫に３０分放置した。その後ＰＳＰ容器から蓋容器を取り外し、縦３００ｍｍ、横３００ｍｍの範囲に１０ｍｍおきに黒字で太さ１ｍｍの格子状の線を引いた白色用紙の上に置き、蓋容器を通して背後の格子の黒線の見え具合を評価した。尚、評価は各サンプル１０個づつ評価し、その中で一番格子がぼやけて見えたものを評価した。
◎：黒色の格子が確認出来る。
○：黒色の格子が一部ぼやけた。
△：黒色の格子が半分程度ぼやけた。
×：黒色の格子が全体ぼやけた。
【００３３】
（４）防曇効果▲２▼：（２）の高温多湿時の保管性を評価した防曇性スチレン系透明樹脂シートの１６枚目から２５枚目の１０枚を用い蓋容器を１０個成形した。評価方法は（３）と同じ方法で行った。
【００３４】
【表１】
【表２】
【発明の効果】
本発明の防曇性スチレン系透明樹脂シート及びその成形品は防曇効果、シート外観及び夏期の倉庫保管を考慮したシートの高温多湿時の保管性に優れているので食料品の包装等に広く使用でき、非常に有用である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antifogging styrene-based transparent resin sheet excellent in antifogging effect, sheet appearance, and storage stability of the sheet at high temperature and high humidity, and a molded product thereof. More specifically, a styrene-based transparent resin sheet widely used in the field of packaging materials and the like is provided with excellent antifogging effect, excellent sheet appearance, and excellent storage properties at high temperature and high humidity in consideration of storage in a warehouse in summer. The present invention relates to a styrene-based transparent resin sheet and a molded product thereof.
[0002]
[Prior art]
Styrene-based transparent resin sheets and their molded products are widely used as packaging and coating materials, but due to the hydrophobic nature of the surface, water that aggregates due to changes in temperature and humidity becomes minute water droplets and adheres to the surface. May occur. The fogging makes it difficult to identify stored items, which often causes a reduction in commercial value.
[0003]
To solve this problem, Japanese Patent Application Laid-Open No. Hei 10-309785 describes that a mixture of sucrose fatty acid ester and methyl cellulose is used. It could not be said that the storage stability at the time was excellent.
[0004]
[Problems to be solved by the invention]
The present invention provides a styrene-based transparent resin sheet having excellent antifogging effect, sheet appearance, and excellent storage stability at high temperature and high humidity in consideration of warehouse storage in summer, and a molded article thereof, based on the above technical situation. The purpose is to do.
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention by using an antifogging agent having a specific configuration. That is, in the present invention, a styrene-based transparent resin sheet is surface-treated with an anti-fogging agent containing 70 to 99% by mass of sucrose laurate and 30 to 1% by mass of sucrose stearate having an HLB of 12 or more. The object has been solved by providing a styrene-based transparent resin sheet obtained by the above method and a molded article obtained by using the sheet.
[0006]
Hereinafter, the present invention will be described in detail.
The antifogging agent of the present invention essentially comprises sucrose laurate and sucrose stearate having an HLB (Hydrophile-Lipophile Balance) of 12 or more. In the sucrose laurate ester of the present invention, the ratio of the lauric acid component is 50% by mass or more, preferably 55% by mass or more, and more preferably 65% by mass or more. When sucrose laurate having a ratio as lauric acid of 50% by mass or more is used, the surface treatment properties are excellent and the antifogging effect is also excellent. Components other than lauric acid include, for example, saturated fatty acids having about 6 to 30 carbon atoms such as caproic acid, caprylic acid, lauric acid, mystic acid, palmitic acid, stearic acid, behenic acid, and montanic acid, lindenic acid, palmito oleic acid And unsaturated fatty acids having about 10 to 24 carbon atoms such as oleic acid, elaidic acid, isooleic acid, erucic acid, linoleic acid and linolenic acid. These fatty acids may be used alone or in combination.
[0007]
The sucrose stearic acid ester having an HLB of 12 or more according to the present invention has a stearic acid component ratio of 50% by mass or more, preferably 55% by mass or more, and more preferably 65% by mass or more. When sucrose stearic acid ester having a ratio of 50% by mass or more as a stearic acid component is used, the storage stability at high temperature and high humidity tends to be excellent. Other components such as palmitic acid and mystyric acid may be used alone or in combination.
[0008]
In the present invention, it is essential to use a sucrose stearic acid ester having an HLB of 12 or more, preferably an HLB of 13 or more, particularly preferably an HLB of 14 or more. If the HLB is less than 12, the solubility in water is poor. Therefore, when applying to a sheet with an aqueous solution, uniform surface treatment on the sheet surface is difficult, and coating unevenness is likely to occur. The sucrose stearic acid ester having an HLB of less than 12 can be contained, but the ratio of the HLB of 12 or more to all sucrose stearic acid esters used in this case is preferably 70% by mass or more.
[0009]
The ratio of the sucrose laurate to the sucrose stearate having an HLB of 12 or more in the antifogging agent of the present invention is as follows: sucrose laurate is 70 to 99% by mass, and sucrose stearate is 30 to 1% by mass. It is. Preferably, sucrose laurate is 75 to 97% by mass, sucrose stearate is 25 to 3% by mass, more preferably, sucrose laurate is 80 to 94% by mass, and sucrose stearate is 20 to 6% by mass. It is. If sucrose laurate is less than 70% by mass, the antifogging effect is poor. On the other hand, if the sucrose stearic acid ester is less than 1% by mass, the storage stability at high temperature and high humidity is inferior.
[0010]
When the surface of the styrene-based transparent resin sheet is treated with an antifogging agent, a solution in which sucrose laurate and sucrose stearate are dissolved in a solvent is used. As the solvent, water, alcohol, and the like are used, but the solvent is not particularly limited thereto. Water is preferred for handling. In this case, the solution concentration of sucrose laurate and sucrose stearate is not particularly limited, but is preferably 0.01 to 10% by mass.
[0011]
The styrene-based transparent resin sheet used for the anti-fogging styrene-based transparent resin sheet of the present invention is a sheet before being treated with an anti-fogging agent obtained by molding and processing a styrene-based transparent resin. Styrene-based transparent resins include homopolymers of styrene-based monomers, copolymers of styrene-based monomers, and copolymers obtained by copolymerizing monomers copolymerizable with styrene-based monomers. And mixtures thereof.
[0012]
The styrene-based monomer used in the (co) polymer includes styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, t-butylstyrene, and the like. Polymerizable monomers include acrylic acid, ethyl acrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylonitrile, methacrylic acid, ethyl methacrylate, methyl methacrylate, butyl methacrylate, and 2-methacrylic acid. Examples include ethylhexyl, 1,3-butadiene, and 2-methyl-1,3-butadiene (isoprene).
[0013]
As the homopolymer of these styrene monomers or the copolymer of styrene monomers, GP (general use) polystyrene obtained by polymerizing styrene is preferable. Examples of the copolymer obtained by copolymerizing a monomer copolymerizable with a styrene monomer include methacrylic acid-styrene copolymer, methyl methacrylate-styrene copolymer, and methyl methacrylate- Methacrylic acid-styrene copolymer, acrylonitrile-styrene copolymer, and styrene-butadiene block copolymer are preferred.
[0014]
Further, a polymer obtained by polymerizing a styrene monomer and / or a monomer copolymerizable with a styrene monomer in the presence of a butadiene rubber may be used as a styrene monomer as long as the transparency is not impaired. It is also possible to use a mixture with a (co) polymer in which a monomer is essential. Butadiene rubbers include high cis polybutadiene, low cis polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, styrene-butadiene-styrene block rubber, partially hydrogenated polybutadiene rubber, and the like. Further, as the styrene monomer and the monomer copolymerizable with the styrene monomer, the above-mentioned monomers can be used.
In addition, at least one kind of monomer or butadiene rubber used for polymerization can be used. As a polymer that can be mixed within a range that does not impair the transparency, rubber-modified impact-resistant polystyrene (HIPS) is preferable.
[0015]
The method for processing the styrene-based transparent resin into a sheet is not particularly limited, and examples thereof include ordinary methods such as a uniaxial stretching method, a biaxial stretching method, a multiaxial stretching method, a coextrusion method, and a lamination method. Further, in order to perform the antifogging treatment on the sheet, it is preferable that the surface of the sheet is modified by a corona discharge treatment method, an ozone treatment method, a plasma treatment method or the like.
[0016]
The method of treating the antifoggant treatment liquid into a styrene-based transparent resin sheet is not particularly limited, and a simple method of applying using a roll coater, a knife coater, a gravure roll coater, or the like is exemplified. Further, spraying, immersion and the like can also be adopted.
[0017]
Styrene solids content of antifogging agents of the transparent resin sheet surface of the present invention treated anti-fogging agent is preferably 0.005 to 0.5 / m 2, more preferably 0.01~0.45g / m 2, in particular preferably from 0.01~0.4g / m 2. Styrene-based solid transparent resin sheet antifogging agents tended to be inferior in low antifogging effect than 0.005 g / m 2, also is uneven coating of more sheet surface than 0.5 g / m 2 It is conspicuous, and the transparency of the molded article formed from the sheet is apt to decrease.
[0018]
Since the antifogging styrene-based transparent resin sheet of the present invention is used as a packaging material or a covering material for foodstuffs, it is necessary to have transparency so that stored items can be confirmed through the antifogging styrene-based transparent resin sheet. The thickness of the antifogging styrene-based transparent resin sheet is not particularly limited, and is generally 100 μm to 10 mm. This sheet is molded and used for a container. Further, as the transparency of the antifogging styrene-based transparent resin sheet, Haze (haze) is preferably 10 or less, and more preferably Haze is 5 or less.
[0019]
The molded product of the present invention is a lid container or a food pack for packaging a food product formed by pressure-forming, vacuum forming, vacuum-pressure forming or the like of an antifogging styrene-based transparent resin sheet.
[0020]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
[0021]
Example 1
As the styrene-based transparent resin sheet, a biaxially stretched GP polystyrene sheet having a thickness of 0.3 mm stretched 2.5 times in the longitudinal direction and 2.5 times in the transverse direction was used. In addition, the haze of the biaxially stretched GP polystyrene sheet was measured with a measuring device NDH-1001DP manufactured by Nippon Denshoku Industries Co., Ltd., and was less than 2.0%.
As the anti-fog agent, a sucrose laurate ester containing 70% by mass of lauric acid and a 40% by mass aqueous solution of the sucrose laurate ester are used. The sucrose having an HLB of 15 and 70% by mass of stearic acid is used. Using sucrose stearate, sucrose laurate and sucrose stearate were adjusted to a solid content of 95% by mass and 5% by mass, respectively. Further, this antifogging agent was diluted with a 1.5% by mass aqueous solution to obtain a sheet coated with the antifogging agent having a solid content of 0.1 g / m 2 on the sheet surface. Using the sheet, a lid container (200 mm length × 120 mm width × 50 mm height) was formed. In addition, Ryoto Sugar Ester LWA-1570 manufactured by Mitsubishi Chemical Foods Co., Ltd. was added to a 40% by mass aqueous solution of sucrose laurate ester, and Ryoto Sugar Ester S-1570 manufactured by Mitsubishi Chemical Foods Co., Ltd. having an HLB of 15 was used as sucrose stearate. Using. Table 1 shows the blending ratio of the solid content of the anti-fogging agent in mass%, and also shows the obtained physical properties.
[0022]
Example 2
Sucrose laurate and sucrose stearate used in Example 1 were used as anti-fogging agents, and the solid content was adjusted to 90% by mass and 10% by mass, respectively. The procedure was performed in the same manner as in Example 1 except that this antifogging agent was used. Table 1 shows the blending ratio of the solid content of the anti-fogging agent in mass%, and also shows the obtained physical properties.
[0023]
Example 3
Sucrose laurate and sucrose stearate used in Example 1 and sucrose palmitate containing 80% by weight of palmitic acid were used as anti-fogging agents. The solid content was 85% by weight. And 12% by mass and 3% by mass. The procedure was performed in the same manner as in Example 1 except that this antifogging agent was used. Note that Ryoto Sugar Ester P-1570 manufactured by Mitsubishi Chemical Foods, Inc. was used as sucrose palmitate. Table 1 shows the blending ratio of the solid content of the anti-fogging agent in mass%, and also shows the obtained physical properties.
[0024]
Example 4
The sucrose laurate and sucrose stearate used in Example 1 and the sucrose stearate having an HLB of 9 and stearic acid of 70% by mass were used as the antifogging agent. They were obtained by adjusting to 75% by mass, 15% by mass and 10% by mass, respectively. The procedure was performed in the same manner as in Example 1 except that this antifogging agent was used. Note that Ryoto Sugar Ester S-970 manufactured by Mitsubishi Chemical Foods, Inc. was used as the sucrose stearate having an HLB of 9. In Table 1, the mixing ratio of the solid content of the anti-fogging agent is shown by mass%, and the obtained physical properties are also shown.
[0025]
Example 5
A biaxially stretched methacrylic acid-styrene copolymer sheet having a thickness of 0.3 mm stretched 2.5 times in the longitudinal direction and 2.5 times in the transverse direction on a styrene-based transparent resin sheet (styrene-based transparent resin is 97% by mass of styrene. (Methacrylic acid 3% by mass) was used in the same manner as in Example 2. Table 1 shows the blending ratio of the solid content of the anti-fogging agent in mass%, and also shows the obtained physical properties. The haze of the biaxially stretched sheet was measured with a measuring device NDH-1001DP manufactured by Nippon Denshoku Industries Co., Ltd., and was less than 2.0%.
[0026]
Comparative Example 1
A 40% by mass aqueous solution of sucrose laurate used in Example 1 was used as an anti-fogging agent, and sucrose stearate having an HLB of 15 used in Example 1 was used as sucrose stearate. The lauric ester and the sucrose stearic ester were obtained by adjusting the solid content ratio to be 5% by mass and 95% by mass, respectively. Except that this antifogging agent was used, the procedure was the same as in Example 1. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It can be seen that the anti-fog effect is inferior.
[0027]
Comparative Example 2
A 40% by mass aqueous solution of sucrose laurate used in Example 1 was used as an anti-fogging agent, and sucrose stearate having an HLB of 15 used in Example 1 was used as sucrose stearate. The solid content ratio of lauric ester and sucrose stearic ester was adjusted to 99.5% by mass and 0.5% by mass, respectively. Except that this antifogging agent was used, the procedure was the same as in Example 1. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It can be seen that the storage property under high temperature and high humidity is poor.
[0028]
Comparative Example 3
As the anti-fog agent, a 40% by mass aqueous solution of sucrose laurate used in Example 1 and the sucrose stearate having an HLB of 9 used in Example 4 were used. It was obtained by adjusting the solid content ratio of the acid ester to 90% by mass and 10% by mass, respectively. Except that this antifogging agent was used, the procedure was the same as in Example 1. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It can be seen that the sheet appearance is inferior.
[0029]
Comparative Example 4
The antifogging agent was obtained by using a 40% by mass aqueous solution of sucrose laurate ester used in Example 1 and methylcellulose, and adjusting the solid content to 85% by mass and 15% by mass, respectively. . Further, this antifogging agent was diluted with a 0.5% by mass aqueous solution to obtain a sheet in which the solid content of the antifogging agent on the sheet surface was applied to 0.03 g / m 2 . The same operation as in Example 1 was performed except that this sheet was used. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It can be seen that the storage property under high temperature and high humidity is poor.
[0030]
In addition, the physical property measurement in an Example was implemented as follows.
(1) Sheet appearance: 10 antifogging styrene-based transparent resin sheets were visually observed using 10 antifogging styrene-based transparent resin sheets obtained in each example (each sheet is 400 mm long × 400 mm wide). And the number of spots was counted, and evaluated by the average number of spots per sheet.
A: 0 to 5 spots were observed.
：: 6 to 20 spots were observed.
Δ: 21 to 50 spots were observed.
X: 51 or more spots were observed.
[0031]
(2) Storage property at high temperature and high humidity: 30 sheets of antifogging styrene-based transparent resin sheets obtained in each example (each sheet was 400 mm long × 400 mm wide) were stacked and a load of 5 kg was applied. 30 weeks of this antifogging styrene-based transparent resin sheet with a weight of 5 kg applied to Nagano Kagaku Kikai Seisakusho (LH-31-15) adjusted to a temperature of 50 ° C. and a humidity of 70% for one week. I left it. One week later, the sheet was taken out, and ten sheets of the sixth to fifteenth sheets of the thirty sheets of the antifogging styrene-based transparent resin sheet were taken out, and the Haze at the center of each sheet was measured with a measuring machine NDH manufactured by Nippon Denshoku Industries Co., Ltd. It was measured at -1001DP. Evaluation was made based on the average Haze.
◎: Haze is less than 2.0% ：: Haze is 2.0 to 3.5%
Δ: Haze is more than 3.5 and 5.0% or less. X: Haze is more than 5.0%.
(3) Antifogging effect {circle around (1)}: The antifogging styrene-based transparent resin sheet obtained in each of the examples was applied to a top surface at a molding temperature of 125 ° C. using a vacuum pressure air molding machine PK400 manufactured by Kansai Automatic Molding Machine Co., Ltd. Ten flat lid containers (200 mm length × 120 mm width × 50 mm height) were molded. The lids were respectively stuck on PSP (polystyrene paper) containers filled with hot water at a temperature of 40 ° C., and then left in a refrigerator at a temperature of 5 ° C. for 30 minutes. Thereafter, the lid container was removed from the PSP container, and placed on a white sheet of black with a grid line of 1 mm thick in black every 10 mm in a range of 300 mm in length and 300 mm in width, and the black line of the grid behind it was passed through the lid container. The appearance was evaluated. In addition, the evaluation was performed for each sample of 10 samples, and the sample in which the lattice was most blurred was evaluated.
：: Black lattice can be confirmed.
：: Black lattice was partially blurred.
Δ: Black lattice was blurred by about half.
×: The entire black lattice was blurred.
[0033]
(4) Antifogging effect (2): Ten lid containers were formed using tenth to twenty-fifth sheets of the antifogging styrene-based transparent resin sheet evaluated for the storage stability at high temperature and high humidity of (2). did. The evaluation method was the same as (3).
[0034]
[Table 1]
[Table 2]
【The invention's effect】
The antifogging styrene-based transparent resin sheet and the molded article of the present invention are excellent in antifogging effect, sheet appearance and storage stability at high temperature and high humidity in consideration of warehouse storage in summer, so that they are widely used for food packaging. Can be used and very useful.
Claims (6)
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| JP2002232337A JP3721349B2 (en) | 2002-08-09 | 2002-08-09 | Antifogging styrene-based transparent resin sheet and molded product thereof |
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| JP2002232337A JP3721349B2 (en) | 2002-08-09 | 2002-08-09 | Antifogging styrene-based transparent resin sheet and molded product thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016039341A1 (en) * | 2014-09-08 | 2016-03-17 | 電気化学工業株式会社 | Biaxially stretched sheet and container for packaging |
| JP2016175393A (en) * | 2015-04-14 | 2016-10-06 | デンカ株式会社 | Biaxially stretched sheet and molded article |
| JP2019107897A (en) * | 2019-02-18 | 2019-07-04 | デンカ株式会社 | Biaxially stretched sheet and molded article |
-
2002
- 2002-08-09 JP JP2002232337A patent/JP3721349B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016039341A1 (en) * | 2014-09-08 | 2016-03-17 | 電気化学工業株式会社 | Biaxially stretched sheet and container for packaging |
| WO2016039340A1 (en) * | 2014-09-08 | 2016-03-17 | 電気化学工業株式会社 | Biaxially stretched sheet and container for packaging |
| CN106573410A (en) * | 2014-09-08 | 2017-04-19 | 电化株式会社 | Biaxially stretched sheet and container for packaging |
| CN106573411A (en) * | 2014-09-08 | 2017-04-19 | 电化株式会社 | Biaxially stretched sheet and container for packaging |
| JPWO2016039340A1 (en) * | 2014-09-08 | 2017-04-27 | デンカ株式会社 | Biaxially stretched sheet and packaging container |
| JPWO2016039341A1 (en) * | 2014-09-08 | 2017-04-27 | デンカ株式会社 | Biaxially stretched sheet and packaging container |
| JP2016175393A (en) * | 2015-04-14 | 2016-10-06 | デンカ株式会社 | Biaxially stretched sheet and molded article |
| JP2019107897A (en) * | 2019-02-18 | 2019-07-04 | デンカ株式会社 | Biaxially stretched sheet and molded article |
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| JP3721349B2 (en) | 2005-11-30 |
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