JP2004067181A - Food container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a food container capable of preventing a content from oozing out. <P>SOLUTION: The food container is constituted of a foam-molded food container obtained of a foamable thermoplastic resin particle and a coating film containing 0.005-50 wt.% fluorine-containing vinyl polymer formed on at least its outside peripheral wall part. <P>COPYRIGHT: (C)2004,JPO

Description

【００１８】
（上記式中、Ｒｆは炭素数３〜２１のポリフルオロアルキル又はポリフルオロアルケニル基、Ｒ_１は水素原子又は炭素数１〜１０のアルキル基、Ｒ_２は炭素数１〜１０のアルキレン基、Ｒ_３は水素原子又はメチル基、Ａｒは置換基を有してもよいアリーレン基である）
や一般式（Ｈ）（Ｃ_ｍＦ_２ｍ＋１・Ｃ_ｎＨ_２ｎＯ）_ＹＰＯ（ＯＮＨ_４）_３−Ｙ
（上記式中、ｍは１〜１０の整数、ｎは１〜１１の整数であって、ｍ＋ｎは８以上であり、Ｙは１又は２である）
が挙げられる。
【００１９】
なお、上記含フッ素型ビニル単量体以外の単量体として、国際特許公開番号ＷＯ９８／３１７３３号公報に記載の単量体を使用することができる。
上記含フッ素型ビニル単量体の内、一般式（Ａ）に含まれる単量体が好ましく、特にＦ（ＣＦ_２）_８（ＣＨ_２）_２ＯＣＯＣＨ＝ＣＨ_２、Ｆ（ＣＦ_２）_８（ＣＨ_２）_２ＯＣＯＣ（ＣＨ_３）＝ＣＨ_２、（ＣＦ_３）_２ＣＦ（ＣＦ_２）_６（ＣＨ_２）_２ＯＣＯＣ（ＣＨ_３）＝ＣＨ_２、（ＣＦ_３）_２ＣＦ（ＣＦ_２）_８（ＣＨ_２）_２ＯＣＯＣ（ＣＨ_３）＝ＣＨ_２が好ましい。
非フッ素ビニル型単量体としては、上記含フッ素型ビニル単量体と共重合可能でありさえすれば特に限定されず、親水性又は親油性の単量体を使用することができる。親水性の単量体としては、下記の一般式（Ｉ）〜（Ｎ）
【００２０】
【化２】

【００２１】
（式中、Ｒ_４は水素原子又はメチル基、ｒは１〜４の整数、ｐは１〜２０の整数である）
【００２２】
【化３】

【００２３】
（式中、Ｒ_４は上記と同じ。Ｒ_５は水素原子、Ｃ_ｒＨ_２ｒ＋１（ｒは上記と同じ）、ＣＨ_２ＯＣＨ_３、Ｃ（ＣＨ_３）_２ＣＨ_２ＣＯＣＨ_３、
【００２４】
【化４】

【００２５】
（ｓは１〜１０の整数）、Ｃ_ｒＨ_２ｒＣＯＮＨ_２（ｒは上記と同じ）、Ｃ_２Ｈ_４ＣＯＮＨ_３、Ｃ_２Ｈ_４Ｎ（ＣＨ_３）_２、（ＣＨ_２）_３Ｎ（ＣＨ_３）_２、ＣＯＯＣ_ｒＨ_２ｒ＋１（ｒは上記と同じ）、Ｃ_ｔＨ_２ｔＳＯ_３Ｈ（ｔは２〜４の整数）である）
【００２６】
【化５】

【００２７】
（式中、Ｒ_４は上記と同じ。ｕは２又は３、Ｒ_５はＣ_ｗＨ_２ｗ＋１（ｗは１〜８の整数）である）
【００２８】
【化６】

【００２９】
（式中、Ｒ_４は上記と同じ。Ｒ_７は水素原子又は水酸基、ｘは０又は１、Ｘは塩素原子、臭素原子、ヨウ素原子又はＣＯＯである）
【００３０】
【化７】

【００３１】
（式中、Ｒ_４は上記と同じ。Ｒ_８はＣ_ｕＨ_２ｕ（ｕは上記と同じ）又はＣＨ_２−ＣＨ（ＣＨ_２Ｃｌ）である）
【００３２】
【化８】

【００３３】
（式中、Ｒ_９は水素原子、メチル基又はカルボキシル基、Ｒ_１０は水素原子、メチル基又はＣＨ_２ＣＯＯＨである）
が挙げられる。
親油性の単量体としては、（メタ）アクリル酸−２−エチルヘキシル、（メタ）アクリル酸オクチル、（メタ）アクリル酸イソオクチル、（メタ）アクリル酸デシル、（メタ）アクリル酸イソデシル、（メタ）アクリル酸ウンデシル、（メタ）アクリル酸ラウリル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸トリデシル、（メタ）アクリル酸テトラデシル、（メタ）アクリル酸ペンタデシル、（メタ）アクリル酸ヘキサデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸ベンジル等が挙げられる。
【００３４】
上記非フッ素ビニル型単量体の内、塗布膜との親和性の良好な親油性の単量体を使用することが好ましい。
上記単量体は組み合わせて使用することが可能である。また、共重合体の場合、重合形式は、ランダム、ブロック、グラフト等のいずれの形式でもよい。なお、含フッ素ビニル型単量体と非フッ素ビニル型単量体の共重合体を使用する場合、含フッ素ビニル型単量体：非フッ素ビニル型単量体＝１：０．２５〜４（重量比）の割合の共重合体を使用することが好ましい。
【００３５】
含フッ素ビニル型重合体は、それを構成する単量体の種類によっても異なるが、３０００〜３０００００の重量平均分子量の重合体を使用することが好ましい。
含フッ素ビニル型重合体は、塗布膜中０．００５〜５０重量％の割合で含まれる。０．００５重量％より少ない場合、内容物の滲み出し防止効果が劣り、５０重量％を越えると塗布膜を形成することが困難となり好ましくない。塗布膜には、含フッ素ビニル型重合体以外に、前記重合体を外側周壁部に固定するためのバインダーが含まれている。より好ましい含フッ素ビニル型重合体の含有割合は、０．１〜３０重量％であり、更に好ましい含有割合は、０．５〜１０重量％である。
【００３６】
バインダーとしては、含フッ素ビニル型重合体を外側周壁部に固定することができさえすれば特に限定されない。但し、以下で説明する塗布法により塗布の容易なバインダーを使用することが好ましい。そのようなバインダーとしては、ポリエステル、アルキッド樹脂、ポリ酢酸ビニル、エポキシ樹脂、ポリアミド樹脂、メラミン樹脂、尿素樹脂、アクリル樹脂、フェノール樹脂、ポリオレフィン、ポリビニルアルコール等の樹脂や、紫外線の照射によりバインダー前駆体を硬化して得られた樹脂等が挙げられる。後者の前駆体としては、東洋インキ製造社製ＦＬＡＳＨ　ＤＲＹ　ＦＤＣメジウム６口、ＦＬＡＳＨ　ＤＲＹ　ＦＯＣ　コンク赤６口等が挙げられる。特に、エポキシ樹脂、ポリアミド樹脂、アクリル樹脂、ポリオレフィン、紫外線の照射によりバインダー前駆体を硬化して得られた樹脂が好ましい。
【００３７】
塗布膜の厚さは、樹脂粒子同士の間隙を十分埋めることで、内容物の滲み出しを防ぐことができさえすれば特に限定されないが、通常０．１〜３０μｍであり、より好ましくは１〜２０μｍである。０．１μｍより薄い場合、樹脂粒子同士の間隙を十分埋めることができないので好ましくなく、３０μｍより厚い場合、塗布膜が剥がれやすくなるので好ましくない。塗布膜の厚さは、塗布膜を形成した食品容器を切り取り、日本電子社製の走査電子顕微鏡ＪＳＭ−８２０で撮影した断面の写真から求めた。
塗布膜の形成方法は、特に限定されず、公知の方法をいずれも使用することができる。例えば、インクジェット塗布法、スプレー、刷毛やローラ等を用いた塗布法、塗布膜を構成する成分を含む溶液中に発泡成形容器を浸ける方法等が挙げられる。
【００３８】
塗布膜を形成するための塗布液は、上記含フッ素ビニル型重合体とバインダー（又はバインダー前駆体）とを少なくとも含む。塗布液は、発泡成形容器を構成する樹脂粒子同士の間隙を十分埋めることが可能な粘度をもつことが好ましい。そのような粘度は、２５℃の場合、１〜５００万ＣＳｔである（ＪＩＳ　Ｚ８８０３に準拠して測定した値を意味する）。なお、例えばアルコール、パラフィン等の溶媒を塗布液に含ませてもよい。所定の粘度に調整するために、溶媒以外の他の成分として、光重合開始剤、重合禁止剤、顔料（例えば、酸化チタン、カーボンブラック等）、顔料分散剤等が挙げられる。
なお、塗布液がバインダー前駆体を含む場合、塗布後に塗布膜が紫外線照射処理に付される。また、溶媒を含む場合、塗布後に溶媒を除去するために塗布膜を熱処理に付してもよい。
【００３９】
本発明の食品容器は、これに牛脂、大豆油、菜種油等の植物油類、ラード、即席麺類、シチュー、マヨネーズ、ドレッシングソース、カレールー、バター、マーガリン、ホワイトソース、ヨーグルト類、アイスクリーム、ドーナツ、ハンバーガー、フライドチキン等の油性食品や脂肪食品を直接入れても、あるいは界面活性剤水溶液を直接入れても、食品容器を構成する各発泡粒子間より外部への油脂、水溶液又は色素等の浸透を長時間にわたり抑制することができる。
【００４０】
【実施例】
以下、実施例により本発明を更に詳細に説明するが、本発明はこれによって制限されるものではない。
実施例１
［含フッ素ビニル型重合体（ブロック共重合体）の合成例］
温度計、滴下フロート、窒素ガス導入管及び撹拌装置を取り付けた５００ｍｌの四つ口フラスコに窒素ガスを導入した後、イソパラフィン（日本油脂社製ＮＡＳ−３）を１７５ｇ入れ、７０℃に昇温した。その後、メタクリル酸ステアリル３９ｇ、下記一般式（１）で表されるポリメリックペルオキシド（ｎは２〜２０の整数）５ｇ及びイソパラフィン５０ｇの混合物を２時間で滴下した。その後７０℃で４時間反応を続けた。
次いで、Ｆ（ＣＦ_２）_３（ＣＨ_２）_２ＯＣＯＣＨ＝ＣＨ_２の含フッ素ビニル型単量体５８．５ｇを１時間かけて滴下した。その後７０℃で５時間反応を行った。イソパラフィン溶液の３０重量％が含フッ素ビニル型重合体（ブロック共重合体）であった。
【００４１】
【化９】

【００４２】
［食品容器の製造方法］
発泡剤として５．５重量％のｎ−ペンタンを含有する直径０．３〜０．６ｍｍの発泡性ポリスチレン樹脂粒子１０００ｇにステアリン酸亜鉛２．５ｇを表面被覆した。バッチ型予備発泡機で水蒸気による均一加熱をすることで、かさ密度０．１ｇ／ｍｌになるように発泡させ、予備発泡粒子を得た。この予備発泡粒子を大気中で６時間熟成乾燥した後、内容量４５０ｃｃ、肉厚２ｍｍのカップ型金型に充填し、０．２ＭＰａ（ゲージ圧）の水蒸気で６秒間加熱、水冷後、カップ状の発泡成形食品容器を得た。次に、得られた発泡成形食品容器を湖北精工社製ＣＵＰ　ＰＲＩＮＴＥＲ　ＫＨ−６１００にて、上記含フッ素ビニル型重合体のイソパラフィン溶液を東洋インキ製造社製のインキであるＦＬＡＳＨ　ＤＲＹ　ＦＤＣ　メジウム　６口に対して５ｗｔ％含有させたインキを成形品表面に被覆印刷し、アイグラフィックス社製のアイ紫外硬化用電源装置にて紫外線乾燥により厚さ４μｍの塗布膜を形成することで、図２に示すカップ状の食品容器を得た。図２中、７は発泡成形食品容器、８は塗布膜を意味する。図２では、食品容器の外側周壁部の上端及び下端に塗布膜を形成していない。
【００４３】
得られた食品容器にカレー粉を８分目まで入れ、ラッピングした後、６０℃オーブンの中に入れ、食品容器の外側周壁部へのカレー粉の黄色色素の滲み出し始め時間を評価した。また、得られた食品容器に界面活性剤水溶液を８分目まで入れ、食品容器の外側周壁部への界面活性剤水溶液の滲み出し始め時間評価した。更に、印刷性を目視で評価した。結果を表１に示す。
【００４４】
実施例２と３、比較例１と２
インキに含有させる含フッ素ビニル型重合体を表に示す量に変更すること以外は実施例１と同様に行った。それらの滲み出し始め時間及び印刷性の結果を表１に示す。なお、実施例２と３、比較例１と２の塗布膜の厚さは、４μｍであった。
【００４５】
比較例３
含フッ素ビニル型重合体を使用しないこと以外は実施例１と同様に行った。滲み出し始め時間及び印刷性の結果を表１に示す。なお、比較例３の塗布膜の厚さは、４μｍであった。
【００４６】
実施例４
［含フッ素ビニル型重合体（ランダム共重合体）の合成例］
実施例１と同じ四つ口フラスコに窒素ガスを導入した後、イソパラフィン（日本油脂社製ＮＡＳ−３）を１７５ｇ入れ、６０℃に昇温した。その後、メタクリル酸ステアリル３９ｇ、Ｆ（ＣＦ_２）_８（ＣＨ_２）_２ＯＣＯＣＨ＝ＣＨ_２の構造式をもつ含フッ素ビニル型単量体５８．５ｇ、ｔ−ブチルパーオキシピバレート１ｇ及び、イソパラフィン５０ｇの混合物を２時間で滴下した。その後６０℃で７時間反応を続けた。イソパラフィン溶液の３０重量％が含フッ素ランダム共重合体であった。
【００４７】
［食品容器の製造方法］
含フッ素ビニル型重合体を、上記ランダム共重合体に変更すること以外は実施例１と同様に行った。但し、塗布膜を図３に示すように食品容器外側周壁部全面に形成した。滲み出し始め時間及び印刷性の結果を表１に示す。
【００４８】
【表１】

【００４９】
表１中、＊１〜＊３は以下の事項を意味する。
＊１　食品容器にカレー粉を８分目まで入れ、カップ成形品をラッピングした後、６０℃オーブンの中に入れ、食品容器の外側周壁部へのカレー粉の滲み出し始め時間を評価。
＊２　食品容器に界面活性剤水溶液（エマルゲン８１０（花王社製）を０．１ｗｔ％、エリオクロムブラックＴ（同仁化学工業研究所社製）を０．００５％溶解させた水溶液）を８分目まで入れ、食品容器の外側周壁部への界面活性剤水溶液の滲み出し始め時間を評価。
＊３　塗布膜を有する食品容器の印刷面を目視で評価した。
表１から実施例１〜４の食品容器は、内容物の滲み出し防止及び印刷性を両立できることがわかる。
【００５０】
【発明の効果】
以上のように、本発明の食品容器は、内容物の外側周壁部からの滲み出しを防止し、生産上においても、成形不良問題、発泡粒子輸送問題、異物混入問題を起こすこと無く安定して効率よく生産することができ、内容物の風味を損なうこともない。
【図面の簡単な説明】
【図１】食品容器の外側周壁部の要部断面図である。
【図２】実施例の食品容器の概略斜視図である。
【図３】実施例の食品容器の概略斜視図である。
【符号の説明】
１　発泡粒子
２　毛細管
３　滲み出した内容物
４　含フッ素共重合体を含むシート
５　凹部
６、８　塗布膜
７　発泡成形食品容器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a food container. More specifically, the present invention relates to a container obtained by foam molding, wherein instant noodles contained in the container, oily foods such as fried chicken, fats and oils such as fat-containing foods or coffee, and ice water in an ice box The present invention relates to a food container capable of preventing the like from oozing out through the fused surface of the foamed particles of the vessel wall.
[0002]
[Prior art]
BACKGROUND ART A container made of a foam is known as a container for storing foods such as instant noodles, oily foods such as fried chicken, fats and oils such as fat-containing foods, coffee, and ice water in an ice box. A container made of a foam is usually formed from expandable thermoplastic resin particles.
The expandable thermoplastic resin particles contain a small amount of a solvent such as toluene, cyclohexane or the like, which is a method of impregnating an aqueous suspension with a readily volatile aliphatic hydrocarbon as a blowing agent, or having a solubility in the resin particles. It is produced by a method of impregnating resin particles with a foaming agent in an aqueous suspension.
[0003]
The foamable thermoplastic resin particles thus obtained are preliminarily foamed, and then the prefoamed particles are charged into a mold of a molding machine having small holes, and heated to a softening point or higher with pressurized steam to form a container. Can be obtained.
When the container thus obtained is broken, the fusion state of each particle is good, that is, even if 100% fusion is achieved without any surface of each particle appearing on the fractured surface, the adhesion of each particle is maintained. Instead of surface bonding, the container has fine capillaries that open from inside to outside. For example, it has been confirmed that when a dye aqueous solution containing a surfactant is put into a container, the aqueous solution leaks out through the particle fusion surface.
[0004]
In particular, the content is oily foods, for example, donut, hamburger, fried chicken, margarine and other salad oils, food containing tallow, etc. for a long time, the oil and fat gradually seeps out of the container wall, the above container Were unsuitable as containers for these foods. In addition, if instant noodles mixed with curry powder are stored and stored inside, the yellow pigment of curry powder oozes out to the outer peripheral wall of the container, contaminating the container, and the product as instant noodle with container Significantly reduce value. Further, in a container such as a simple ice box, the ice water in the ice box oozes out of the container after a long time elapses, lowering the commercial value.
[0005]
In order to prevent oozing of oils and fats in a container formed using the general foamable thermoplastic resin particles, a method of increasing the heating conditions during molding or extending the heating time may be considered. According to these methods, the ability to prevent oozing of oils and fats can be improved. However, since the heat resistance of the container is low, there is a problem that the container melts and shrinks when heated, and it is difficult to obtain a container having a beautiful appearance that can be commercialized. Furthermore, since a heat treatment is required, there is a problem that a molding cycle is lengthened and productivity is deteriorated.
[0006]
As a method of preventing oozing of the contents to the outer peripheral wall portion of the container, there has been proposed a method of coating an additive for preventing oozing on the surface of expandable styrene resin particles and forming a container using the same. I have. For example, JP-A-5-140364 and JP-A-10-298339 disclose a method of coating the surface of resin particles with a fluorine-containing vinyl polymer, and JP-B-56-34172 discloses a method of coating resin particles with sucrose ester. There has been proposed a method of coating the surface of the above.
[0007]
[Problems to be solved by the invention]
The above proposal is an effective means in preventing the bleeding phenomenon.However, since the surface of the expandable styrene-based resin particles is coated with a fluorine-based resin, the fluorine-based resin is not required to prevent bleeding even on the inner surface of the container. It is desired that the inner surface is not coated because it may be coated and the flavor of the contents may be impaired. Furthermore, in the method of coating the foamable thermoplastic resin particles with the fluorine-containing vinyl polymer on the surface, the foamed particles are apt to be charged with static electricity, and therefore, there is a problem of poor molding such that poor filling or mold release during molding tends to occur. . In addition, in the case of surface coating with sucrose ester, since the foamed particles are sticky, the flowability of the foamed particles during the production of the container is poor, and it takes time to feed the foamed particles. There is a possibility of foreign matter being mixed in such a manner that it adheres to the inside and becomes a dirty foamed particle later to be mixed into the molded product.
[0008]
[Means for Solving the Problems]
The inventor of the present invention, in a food container molded with expandable thermoplastic resin particles, prevents the contents in the container from seeping out to the outer peripheral wall portion, and furthermore, causes the above-described problems such as productivity. As a result of studying a container having a configuration that is not allowed to occur, the present invention was reached.
Thus, according to the present invention, an expanded molded food container obtained from expandable thermoplastic resin particles, and a coating film containing at least 0.005 to 50% by weight of a fluorine-containing vinyl polymer formed on at least the outer peripheral wall portion thereof A food container characterized by comprising:
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the history of inventing the present invention will be described.
As described above, since the bonding of the foamed particles is not surface bonding, a fine capillary tube is opened from the inside to the outside on the particle fusion surface of the container. Therefore, as shown in FIG. 1A, the contents pass through the capillaries and seep out to the outside. In FIG. 1 (a), 1 indicates expanded particles, 2 indicates a capillary, and 3 indicates exuded contents.
As a method of preventing the contents from seeping out, a method of laminating a sheet containing a fluorocopolymer on the outer peripheral wall portion of the foamed food container as shown in FIG. However, even with this method, the concave portions existing between the particles constituting the outer peripheral wall portion of the container cannot be filled, so that the contents ooze into the concave portions. In FIG. 1B, reference numeral 4 denotes a sheet containing a fluorinated copolymer, and reference numeral 5 denotes a concave portion. Further, in this method, it is necessary to increase the number of sheet laminating steps, and as a result, productivity is deteriorated.
Therefore, the inventor of the present invention can fill the concave portion by forming a coating film containing a fluorine-containing vinyl polymer on the outer peripheral wall portion of the food container as shown in FIG. 1 (c). The present inventors have found that the bleeding of the contents to the outside can be prevented in the portion in which the concave portion is filled, and have reached the present invention.
[0010]
That is, in the present invention, since bleeding can be prevented by forming a coating film, the fluorine-containing vinyl polymer is present only in the particle gap of the resin particles constituting the food container without lowering the productivity. Becomes possible. In addition, since the coating film can be formed only on necessary portions, the amount of the fluorine-containing vinyl polymer used can be reduced. Further, as described above, when coating the fluorinated vinyl polymer with the expandable thermoplastic resin particles, there is a problem of poor molding such as poor filling or mold release during molding due to static electricity of the expanded particles, and expanded particles. The problem of foam particle transport is that the fluidity of the foam is poor and it takes a long time to feed the foam particles, and foreign matter such as adhering to the inside of the foam particle feed pipe and then becoming contaminated foam particles and entering the molded product is mixed. There are problems, but we can solve them all. In FIG. 1C, reference numeral 6 denotes a coating film.
Hereinafter, the food container of the present invention will be described.
[0011]
First, the foam-formed food container constituting the food container of the present invention is obtained by foam-forming foamable thermoplastic resin particles (hereinafter, simply referred to as resin particles). The thermoplastic resin constituting the resin particles is not particularly limited as long as the resin can be foamed with an inorganic or organic foaming agent. For example, aromatic vinyl resins such as polystyrene, impact-resistant polystyrene, styrene- (meth) acrylic acid copolymer, styrene-methyl (meth) acrylate copolymer, styrene-maleic anhydride copolymer, and AS resin Methacrylic acid ester resins, vinylidene chloride resins, olefin homopolymers and copolymers such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers; polyphenylene ether, mixed resins of polyphenylene ether and polystyrene; some polyolefins And a composite resin in which a vinyl monomer is graft-copolymerized. Of these, aromatic vinyl resins, polyolefin homopolymers and copolymers are preferred, and polystyrene resins are particularly preferred.
[0012]
Resin particles are formed by adding a blowing agent, for example, an aliphatic hydrocarbon such as propane, n-butane, isobutane, n-pentane, isopentane, or cyclopentane; One or two or more foaming agents that are liquid or gas at room temperature, such as freon compounds, inorganic compounds such as carbon dioxide and nitrogen, are impregnated with 2 to 10 parts by weight per 100 parts by weight of resin particles. Known methods can be used for impregnation of the foaming agent. For example, a method of impregnating the thermoplastic resin particles in an autoclave as an aqueous suspension of the foaming agent can be mentioned.
[0013]
The size of the resin particles is not particularly limited, but preferably has an average diameter of usually 0.2 to 1.0 mm. Further, the resin particles may be subjected to a preliminary foaming treatment before foam molding.
The resin particles exhibit an effect of preventing agglomeration during prefoaming, an effect of releasing from a molding die, an effect of preventing permeation such as improvement in slipperiness of a molded body, and an effect of promoting fusion of resin particles during molding. Can be used as a coating.
[0014]
For example, a metal salt of a higher fatty acid may be used as a coating agent having an effect of preventing agglomeration and / or preventing penetration. Fatty acid amides such as lauric amide, oleic acid amide, and the like, which are amidated natural fatty acids such as amide of rice sugar oil and hydrogenated tallow oil amide, as coating agents exhibiting a fusion promoting effect, triglyceride stearate, triglyceride palmitate, etc. Examples include triglycerides of fatty acids, natural triglycerides such as soybean hardened oil and hardened castor oil.
As a method of treating the surface of the resin particles with the coating agent, a conventionally known method can be used. For example, the treatment can be performed by mixing the resin particles and the coating agent using a mixer such as a super mixer, a Henschel mixer, a Loedige mixer, or the like.
[0015]
The foam molded food container is obtained by foaming and molding the above-described resin particles by a known method. The shape of the foam molded food container is not particularly limited, and includes various shapes used as food containers such as a cup, a dish, a bowl, and a box.
The thickness of the foam molded food container varies depending on the contents, but is usually in the range of 1 to 30 mm.
The foamed molded food container becomes the food container of the present invention by forming a coating film containing 0.005 to 50% by weight of the fluorine-containing vinyl polymer on the outer peripheral wall.
[0016]
In the present invention, the coating film is formed on at least the outer peripheral wall. Forming the above-mentioned coating film on the outer peripheral wall portion corresponding to the height of the content contained in the foam-molded food container, that is, the portion where the bleeding of the content may occur is one of more preferable embodiments. . In addition, a coating film may be formed on other portions, for example, on the outer bottom portion of the container, the outer peripheral wall portion corresponding to the height of the contents or more, as necessary. However, it is preferable not to provide a coating film on the upper part of the outer peripheral wall where a person may attach a mouth to the container.
The fluorinated vinyl polymer includes a homopolymer or copolymer of a fluorinated vinyl monomer, or a copolymer of a homopolymer of a fluorinated vinyl monomer and a non-fluorinated vinyl monomer. Is included.
As the fluorine-containing vinyl monomer, the following general formulas (A) to (G)
[0017]
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[0018]
(In the above formula, Rf is a polyfluoroalkyl or polyfluoroalkenyl group having 3 to 21 carbon atoms, R ₁ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ₂ is an alkylene group having 1 to 10 carbon atoms, R ₃ is a hydrogen atom or a methyl group, and Ar is an arylene group which may have a substituent.)
And general formula _{(H) (C m F 2m} + 1 · C n H 2n O) Y PO (ONH 4) 3-Y
(In the above formula, m is an integer of 1 to 10, n is an integer of 1 to 11, m + n is 8 or more, and Y is 1 or 2.)
Is mentioned.
[0019]
In addition, as a monomer other than the fluorine-containing vinyl monomer, a monomer described in International Patent Publication No. WO 98/31733 can be used.
Among the above-mentioned fluorinated vinyl monomers, those contained in the general formula (A) are preferable, and in particular, F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH ＝ CH ₂ , F (CF ₂ ) ₈ (CH _{2) 2 OCOC (CH 3)} = CH 2, (CF 3) 2 CF (CF 2) 6 (CH 2) 2 OCOC (CH 3) = CH 2, (CF 3) 2 CF (CF 2) 8 (CH _{2) 2 OCOC (CH 3)} = CH 2 are preferred.
The non-fluorinated vinyl type monomer is not particularly limited as long as it can be copolymerized with the above-mentioned fluorinated vinyl monomer, and a hydrophilic or lipophilic monomer can be used. As the hydrophilic monomer, the following general formulas (I) to (N)
[0020]
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[0021]
(In the formula, R ₄ is a hydrogen atom or a methyl group, r is an integer of 1 to 4, and p is an integer of 1 to 20.)
[0022]
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[0023]
(Wherein R ₄ is the same as above; R ₅ is a hydrogen atom, C _r H _{2r + 1} (r is the same as above), CH ₂ OCH ₃ , C (CH ₃ ) ₂ CH ₂ COCH ₃ ,
[0024]
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[0025]
(S is an integer of from 1 to _{10), C r H 2r CONH 2} (r is as defined _{above), C 2 H 4 CONH 3} , C 2 H 4 N (CH 3) 2, (CH 2) 3 N (CH _{3) 2, COOC r H 2r} + 1 (r is as defined _above), a _{C t H 2t SO 3 H (} t is an integer of 2 to 4))
[0026]
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[0027]
(In the formula, R ₄ is the same as above. U is 2 or 3, and R ₅ is C _w H _{2w + 1} (w is an integer of 1 to 8).)
[0028]
Embedded image

[0029]
(In the formula, R ₄ is the same as above. R ₇ is a hydrogen atom or a hydroxyl group, x is 0 or 1, X is a chlorine atom, a bromine atom, an iodine atom, or COO.)
[0030]
Embedded image

[0031]
(Wherein, _{R 4} is the same .R ₈ as above is _C u _{H 2u} (u is the same as above) or _{CH 2 -CH (CH 2 Cl)} )
[0032]
Embedded image

[0033]
(Wherein R ₉ is a hydrogen atom, a methyl group or a carboxyl group, and R ₁₀ is a hydrogen atom, a methyl group or CH ₂ COOH)
Is mentioned.
As the lipophilic monomer, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) Undecyl acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meth) acryl Examples thereof include stearyl acid, behenyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate.
[0034]
It is preferable to use a lipophilic monomer having good affinity with the coating film among the above non-fluorinated vinyl monomers.
The above monomers can be used in combination. In the case of a copolymer, the polymerization mode may be any of random, block, graft and the like. When a copolymer of a fluorinated vinyl monomer and a non-fluorinated vinyl monomer is used, the fluorinated vinyl monomer: non-fluorinated vinyl monomer = 1: 0.25 to 4 ( (Weight ratio) is preferably used.
[0035]
The fluorine-containing vinyl polymer varies depending on the type of the monomer constituting the polymer, but it is preferable to use a polymer having a weight average molecular weight of 3,000 to 300,000.
The fluorine-containing vinyl polymer is contained in the coating film at a ratio of 0.005 to 50% by weight. If the amount is less than 0.005% by weight, the effect of preventing oozing of the contents is poor, and if it exceeds 50% by weight, it becomes difficult to form a coating film, which is not preferable. The coating film contains, in addition to the fluorovinyl polymer, a binder for fixing the polymer to the outer peripheral wall. A more preferred content of the fluorine-containing vinyl polymer is 0.1 to 30% by weight, and a still more preferred content is 0.5 to 10% by weight.
[0036]
The binder is not particularly limited as long as the fluorovinyl polymer can be fixed to the outer peripheral wall. However, it is preferable to use a binder that can be easily applied by the application method described below. Examples of such a binder include resins such as polyester, alkyd resin, polyvinyl acetate, epoxy resin, polyamide resin, melamine resin, urea resin, acrylic resin, phenol resin, polyolefin, and polyvinyl alcohol, and binder precursors by irradiation of ultraviolet rays. And the like. Examples of the latter precursor include 6 FLASH DRY FDC media manufactured by Toyo Ink Mfg. Co., Ltd. and 6 FLASH DRY FOC Conc Red. In particular, an epoxy resin, a polyamide resin, an acrylic resin, a polyolefin, and a resin obtained by curing a binder precursor by irradiation with ultraviolet rays are preferable.
[0037]
The thickness of the coating film is not particularly limited as long as the bleeding of the contents can be prevented by sufficiently filling the gap between the resin particles, but is usually 0.1 to 30 μm, and more preferably 1 to 30 μm. 20 μm. When the thickness is less than 0.1 μm, it is not preferable because the gap between the resin particles cannot be sufficiently filled, and when the thickness is more than 30 μm, the coating film is easily peeled off, which is not preferred. The thickness of the coating film was determined from a photograph of a cross-section taken with a scanning electron microscope JSM-820 manufactured by JEOL Ltd. by cutting out the food container on which the coating film was formed.
The method for forming the coating film is not particularly limited, and any known method can be used. Examples of the method include an inkjet coating method, a spray method, a coating method using a brush or a roller, and a method of dipping a foam molding container in a solution containing components constituting a coating film.
[0038]
A coating liquid for forming a coating film contains at least the above-mentioned fluorine-containing vinyl polymer and a binder (or a binder precursor). The coating liquid preferably has a viscosity that can sufficiently fill the gap between the resin particles constituting the foam molding container. Such a viscosity at 25 ° C. is from 1 to 5,000,000 CSt (meaning a value measured according to JIS Z8803). Note that a solvent such as alcohol or paraffin may be included in the coating solution. In order to adjust the viscosity to a predetermined value, other components other than the solvent include a photopolymerization initiator, a polymerization inhibitor, a pigment (for example, titanium oxide, carbon black, etc.), a pigment dispersant, and the like.
When the coating liquid contains a binder precursor, the coating film is subjected to an ultraviolet irradiation treatment after the coating. When a solvent is contained, the applied film may be subjected to a heat treatment after the application to remove the solvent.
[0039]
The food container of the present invention comprises vegetable oils such as beef tallow, soybean oil, rapeseed oil, lard, instant noodles, stew, mayonnaise, dressing sauce, curry roux, butter, margarine, white sauce, yogurt, ice cream, donut, hamburger. Even if an oil-based food or fatty food such as fried chicken is directly added, or a surfactant aqueous solution is directly added, the penetration of oils, fats, aqueous solutions or dyes from the foamed particles constituting the food container to the outside is prolonged. Can be suppressed over time.
[0040]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
Example 1
[Synthesis example of fluorinated vinyl polymer (block copolymer)]
After introducing nitrogen gas into a 500 ml four-necked flask equipped with a thermometer, a drop float, a nitrogen gas inlet tube and a stirrer, 175 g of isoparaffin (NAS-3, manufactured by NOF Corporation) was added, and the temperature was raised to 70 ° C. . Thereafter, a mixture of 39 g of stearyl methacrylate, 5 g of a polymeric peroxide represented by the following general formula (1) (n is an integer of 2 to 20) and 50 g of isoparaffin was added dropwise over 2 hours. Thereafter, the reaction was continued at 70 ° C. for 4 hours.
Next, 58.5 g of a fluorinated vinyl monomer of F (CF ₂ ) ₃ (CH ₂ ) ₂ OCOCH ＝ CH ₂ was added dropwise over 1 hour. Thereafter, the reaction was performed at 70 ° C. for 5 hours. 30% by weight of the isoparaffin solution was a fluorine-containing vinyl polymer (block copolymer).
[0041]
Embedded image

[0042]
[Production method of food container]
2.5 g of zinc stearate was surface-coated on 1000 g of expandable polystyrene resin particles having a diameter of 0.3 to 0.6 mm and containing 5.5% by weight of n-pentane as a blowing agent. By performing uniform heating with steam using a batch-type prefoaming machine, foaming was performed to a bulk density of 0.1 g / ml, thereby obtaining prefoamed particles. After aging and drying the pre-expanded particles in the atmosphere for 6 hours, they are filled into a cup mold having an inner volume of 450 cc and a thickness of 2 mm, heated with steam of 0.2 MPa (gauge pressure) for 6 seconds, water-cooled, and shaped like a cup. Was obtained. Next, the obtained foam-molded food container was placed in 6 cups of FLASH DRY FDC medium, which is an ink manufactured by Toyo Ink Mfg. Co., Ltd., with an isoparaffin solution of the above-mentioned fluorine-containing vinyl polymer in CUP PRINTER KH-6100 manufactured by Hubei Seiko Co., Ltd. On the other hand, an ink containing 5 wt% was coated on the surface of the molded article and printed, and a coating film having a thickness of 4 μm was formed by drying with an ultraviolet ray using a power supply device for eye ultraviolet curing manufactured by Eye Graphics Co., Ltd., as shown in FIG. A cup-shaped food container was obtained. In FIG. 2, 7 indicates a foam-formed food container, and 8 indicates a coating film. In FIG. 2, no coating film is formed on the upper and lower ends of the outer peripheral wall of the food container.
[0043]
The curry powder was put into the obtained food container for up to 8 minutes, wrapped, and then placed in a 60 ° C. oven, and the time at which the yellow pigment of the curry powder began to seep into the outer peripheral wall of the food container was evaluated. In addition, the surfactant aqueous solution was put into the obtained food container for up to 8 minutes, and the time at which the surfactant aqueous solution started to seep into the outer peripheral wall of the food container was evaluated. Further, printability was visually evaluated. Table 1 shows the results.
[0044]
Examples 2 and 3, Comparative Examples 1 and 2
The procedure was performed in the same manner as in Example 1 except that the amount of the fluorinated vinyl polymer contained in the ink was changed to the amount shown in the table. Table 1 shows the bleeding start time and printability results. The thickness of the coating films of Examples 2 and 3 and Comparative Examples 1 and 2 was 4 μm.
[0045]
Comparative Example 3
Except not using a fluorine-containing vinyl polymer, it carried out similarly to Example 1. Table 1 shows the bleeding start time and printability results. In addition, the thickness of the coating film of Comparative Example 3 was 4 μm.
[0046]
Example 4
[Synthesis example of fluorinated vinyl polymer (random copolymer)]
After nitrogen gas was introduced into the same four-necked flask as in Example 1, 175 g of isoparaffin (NAS-3, manufactured by NOF Corporation) was added, and the temperature was raised to 60 ° C. Thereafter, stearyl methacrylate _{39g, F (CF 2) 8} (CH 2) 2 OCOCH = fluorovinyl having the structural formula of CH ₂ type monomer 58.5 g, t-butyl peroxypivalate 1g and isoparaffin 50g Was added dropwise over 2 hours. Thereafter, the reaction was continued at 60 ° C. for 7 hours. 30% by weight of the isoparaffin solution was a fluorine-containing random copolymer.
[0047]
[Production method of food container]
The procedure was carried out in the same manner as in Example 1 except that the fluorine-containing vinyl polymer was changed to the above random copolymer. However, the coating film was formed on the entire outer peripheral wall portion of the food container as shown in FIG. Table 1 shows the bleeding start time and printability results.
[0048]
[Table 1]

[0049]
In Table 1, * 1 to * 3 mean the following items.
* 1 Put curry powder into a food container for up to 8 minutes, wrap the cup molded product, place it in a 60 ° C oven, and evaluate the time to start oozing of the curry powder into the outer peripheral wall of the food container.
* 2 A surfactant solution (aqueous solution in which 0.1% by weight of Emulgen 810 (manufactured by Kao Corporation) and 0.005% of Eriochrome Black T (manufactured by Dojindo Laboratories) are dissolved) in a food container for 8 minutes And evaluated the time when the aqueous solution of the surfactant started to seep into the outer peripheral wall of the food container.
* 3 The printed surface of a food container having a coating film was visually evaluated.
From Table 1, it can be seen that the food containers of Examples 1 to 4 can achieve both prevention of oozing of the contents and printability.
[0050]
【The invention's effect】
As described above, the food container of the present invention prevents oozing of the contents from the outer peripheral wall portion, and stably without producing a molding defect problem, a foaming particle transport problem, or a foreign matter mixing problem even in production. It can be produced efficiently and does not impair the flavor of the contents.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of an outer peripheral wall portion of a food container.
FIG. 2 is a schematic perspective view of the food container of the embodiment.
FIG. 3 is a schematic perspective view of the food container of the embodiment.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 foam particles 2 capillaries 3 exuded contents 4 sheet containing fluorocopolymer 5 recesses 6 and 8 coating film 7 foamed food container

Claims (4)

It comprises a foamed food container obtained from expandable thermoplastic resin particles, and a coating film containing 0.005 to 50% by weight of a fluorine-containing vinyl polymer formed on at least the outer peripheral wall thereof. Food containers. The food container according to claim 1, wherein the coating film is formed on a part of the outer peripheral wall portion. 3. The food container according to claim 1, wherein the fluorine-containing vinyl polymer is a copolymer of fluorine-containing vinyl monomers, or a copolymer of a fluorine-containing vinyl monomer and a non-fluorovinyl monomer. . The fluorinated vinyl monomer is F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH = CH ₂ , F (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ , (CF ₃ ) ₂ The method is selected from CF (CF ₂ ) ₆ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ and (CF ₃ ) ₂ CF (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH _2. 4. The food container according to 3.

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