JP3909881B2 - Styrene resin laminated biaxially oriented sheet - Google Patents
Styrene resin laminated biaxially oriented sheet Download PDFInfo
- Publication number
- JP3909881B2 JP3909881B2 JP31542095A JP31542095A JP3909881B2 JP 3909881 B2 JP3909881 B2 JP 3909881B2 JP 31542095 A JP31542095 A JP 31542095A JP 31542095 A JP31542095 A JP 31542095A JP 3909881 B2 JP3909881 B2 JP 3909881B2
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- JP
- Japan
- Prior art keywords
- resin
- styrene
- oil
- sheet
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920005989 resin Polymers 0.000 title claims description 169
- 239000011347 resin Substances 0.000 title claims description 168
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 title claims description 145
- 239000011342 resin composition Substances 0.000 claims description 49
- 229920001955 polyphenylene ether Polymers 0.000 claims description 33
- 238000011156 evaluation Methods 0.000 claims description 32
- 239000000463 material Substances 0.000 claims description 28
- -1 polypropylene Polymers 0.000 claims description 22
- 239000000178 monomer Substances 0.000 claims description 18
- 238000000465 moulding Methods 0.000 claims description 12
- 241000209094 Oryza Species 0.000 claims description 9
- 235000007164 Oryza sativa Nutrition 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 9
- 235000009566 rice Nutrition 0.000 claims description 9
- 150000001993 dienes Chemical class 0.000 claims description 7
- 239000004743 Polypropylene Substances 0.000 claims description 5
- 229920001400 block copolymer Polymers 0.000 claims description 5
- 229920001155 polypropylene Polymers 0.000 claims description 5
- 229920001971 elastomer Polymers 0.000 claims description 4
- 239000005060 rubber Substances 0.000 claims description 4
- 229920001519 homopolymer Polymers 0.000 claims description 3
- 150000004667 medium chain fatty acids Chemical class 0.000 claims description 2
- 239000011550 stock solution Substances 0.000 claims description 2
- UFTFJSFQGQCHQW-UHFFFAOYSA-N triformin Chemical compound O=COCC(OC=O)COC=O UFTFJSFQGQCHQW-UHFFFAOYSA-N 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 139
- 239000003921 oil Substances 0.000 description 100
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 20
- 235000013305 food Nutrition 0.000 description 20
- 238000000034 method Methods 0.000 description 20
- 229920001890 Novodur Polymers 0.000 description 15
- 238000002156 mixing Methods 0.000 description 15
- 239000004014 plasticizer Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 238000001125 extrusion Methods 0.000 description 11
- 229920001577 copolymer Polymers 0.000 description 10
- 229920000642 polymer Polymers 0.000 description 10
- 239000008188 pellet Substances 0.000 description 7
- 229920013636 polyphenyl ether polymer Polymers 0.000 description 7
- 239000004793 Polystyrene Substances 0.000 description 5
- 238000004806 packaging method and process Methods 0.000 description 5
- 229920002223 polystyrene Polymers 0.000 description 5
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 229920006302 stretch film Polymers 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 3
- 238000004898 kneading Methods 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 150000003440 styrenes Chemical class 0.000 description 3
- KTZVZZJJVJQZHV-UHFFFAOYSA-N 1-chloro-4-ethenylbenzene Chemical compound ClC1=CC=C(C=C)C=C1 KTZVZZJJVJQZHV-UHFFFAOYSA-N 0.000 description 2
- NVZWEEGUWXZOKI-UHFFFAOYSA-N 1-ethenyl-2-methylbenzene Chemical compound CC1=CC=CC=C1C=C NVZWEEGUWXZOKI-UHFFFAOYSA-N 0.000 description 2
- JZHGRUMIRATHIU-UHFFFAOYSA-N 1-ethenyl-3-methylbenzene Chemical compound CC1=CC=CC(C=C)=C1 JZHGRUMIRATHIU-UHFFFAOYSA-N 0.000 description 2
- SDJHPPZKZZWAKF-UHFFFAOYSA-N 2,3-dimethylbuta-1,3-diene Chemical compound CC(=C)C(C)=C SDJHPPZKZZWAKF-UHFFFAOYSA-N 0.000 description 2
- OMNYXCUDBQKCMU-UHFFFAOYSA-N 2,4-dichloro-1-ethenylbenzene Chemical compound ClC1=CC=C(C=C)C(Cl)=C1 OMNYXCUDBQKCMU-UHFFFAOYSA-N 0.000 description 2
- NXXYKOUNUYWIHA-UHFFFAOYSA-N 2,6-Dimethylphenol Chemical compound CC1=CC=CC(C)=C1O NXXYKOUNUYWIHA-UHFFFAOYSA-N 0.000 description 2
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 2
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 2
- BTOVVHWKPVSLBI-UHFFFAOYSA-N 2-methylprop-1-enylbenzene Chemical compound CC(C)=CC1=CC=CC=C1 BTOVVHWKPVSLBI-UHFFFAOYSA-N 0.000 description 2
- JLBJTVDPSNHSKJ-UHFFFAOYSA-N 4-Methylstyrene Chemical compound CC1=CC=C(C=C)C=C1 JLBJTVDPSNHSKJ-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- SOGAXMICEFXMKE-UHFFFAOYSA-N Butylmethacrylate Chemical compound CCCCOC(=O)C(C)=C SOGAXMICEFXMKE-UHFFFAOYSA-N 0.000 description 2
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 2
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 2
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 2
- 210000000988 bone and bone Anatomy 0.000 description 2
- 238000007334 copolymerization reaction Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000003925 fat Substances 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- AHAREKHAZNPPMI-AATRIKPKSA-N (3e)-hexa-1,3-diene Chemical compound CC\C=C\C=C AHAREKHAZNPPMI-AATRIKPKSA-N 0.000 description 1
- 125000001140 1,4-phenylene group Chemical group [H]C1=C([H])C([*:2])=C([H])C([H])=C1[*:1] 0.000 description 1
- QKNQPCLQRXMWJO-UHFFFAOYSA-N 1-(tert-butyldiazenyl)cyclohexane-1-carbonitrile Chemical compound CC(C)(C)N=NC1(C#N)CCCCC1 QKNQPCLQRXMWJO-UHFFFAOYSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- JQXYBDVZAUEPDL-UHFFFAOYSA-N 2-methylidene-5-phenylpent-4-enoic acid Chemical compound OC(=O)C(=C)CC=CC1=CC=CC=C1 JQXYBDVZAUEPDL-UHFFFAOYSA-N 0.000 description 1
- FRIBMENBGGCKPD-UHFFFAOYSA-N 3-(2,3-dimethoxyphenyl)prop-2-enal Chemical compound COC1=CC=CC(C=CC=O)=C1OC FRIBMENBGGCKPD-UHFFFAOYSA-N 0.000 description 1
- OFNISBHGPNMTMS-UHFFFAOYSA-N 3-methylideneoxolane-2,5-dione Chemical compound C=C1CC(=O)OC1=O OFNISBHGPNMTMS-UHFFFAOYSA-N 0.000 description 1
- OXGOEZHUKDEEKS-UHFFFAOYSA-N 3-tert-butylperoxy-1,1,5-trimethylcyclohexane Chemical compound CC1CC(OOC(C)(C)C)CC(C)(C)C1 OXGOEZHUKDEEKS-UHFFFAOYSA-N 0.000 description 1
- OMIHGPLIXGGMJB-UHFFFAOYSA-N 7-oxabicyclo[4.1.0]hepta-1,3,5-triene Chemical compound C1=CC=C2OC2=C1 OMIHGPLIXGGMJB-UHFFFAOYSA-N 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000004342 Benzoyl peroxide Substances 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- JIGUQPWFLRLWPJ-UHFFFAOYSA-N Ethyl acrylate Chemical compound CCOC(=O)C=C JIGUQPWFLRLWPJ-UHFFFAOYSA-N 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- GYCMBHHDWRMZGG-UHFFFAOYSA-N Methylacrylonitrile Chemical compound CC(=C)C#N GYCMBHHDWRMZGG-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- KYIKRXIYLAGAKQ-UHFFFAOYSA-N abcn Chemical compound C1CCCCC1(C#N)N=NC1(C#N)CCCCC1 KYIKRXIYLAGAKQ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 125000005396 acrylic acid ester group Chemical group 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000012662 bulk polymerization Methods 0.000 description 1
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 description 1
- 150000001244 carboxylic acid anhydrides Chemical class 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
- 239000008157 edible vegetable oil Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- SUPCQIBBMFXVTL-UHFFFAOYSA-N ethyl 2-methylprop-2-enoate Chemical compound CCOC(=O)C(C)=C SUPCQIBBMFXVTL-UHFFFAOYSA-N 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 229920005669 high impact polystyrene Polymers 0.000 description 1
- 239000004797 high-impact polystyrene Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 229940057917 medium chain triglycerides Drugs 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 125000005397 methacrylic acid ester group Chemical group 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000012778 molding material Substances 0.000 description 1
- 235000014593 oils and fats Nutrition 0.000 description 1
- 150000001451 organic peroxides Chemical class 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 125000000843 phenylene group Chemical group C1(=C(C=CC=C1)*)* 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 239000003505 polymerization initiator Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- NHARPDSAXCBDDR-UHFFFAOYSA-N propyl 2-methylprop-2-enoate Chemical compound CCCOC(=O)C(C)=C NHARPDSAXCBDDR-UHFFFAOYSA-N 0.000 description 1
- PNXMTCDJUBJHQJ-UHFFFAOYSA-N propyl prop-2-enoate Chemical compound CCCOC(=O)C=C PNXMTCDJUBJHQJ-UHFFFAOYSA-N 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 101150002764 purA gene Proteins 0.000 description 1
- 239000007870 radical polymerization initiator Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 125000000547 substituted alkyl group Chemical group 0.000 description 1
- 125000003107 substituted aryl group Chemical group 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- 238000012719 thermal polymerization Methods 0.000 description 1
- 238000003856 thermoforming Methods 0.000 description 1
- 238000007666 vacuum forming Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 230000002087 whitening effect Effects 0.000 description 1
Landscapes
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Laminated Bodies (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、スチレン系樹脂積層二軸延伸シートに関する。さらに詳しくは、透明性、剛性、成形性などのスチレン系樹脂延伸シートの本来有する諸特性を保ち、且つ、耐油性、耐可塑剤性、リサイクル性、耐折性に優れ、油分を含有する食品を収納してラップ包装に供される容器の成形材料として安価で、好適なスチレン系樹脂積層二軸延伸シートに関する。
【０００２】
【従来の技術】
スチレン系樹脂延伸シート、特に一般用ポリスチレンを主成分とするスチレン系樹脂よりなる二軸延伸シートは、良好な透明性を示し、腰が強く、また成形性にも優れ、真空成形法や圧空成形法等の熱成形法により容易に容器等が成形できるため、主として食品包装用の軽量容器の製造に大量に使用されている。
【０００３】
またこれまで、電子レンジでの加熱調理用途や直接沸騰水に接する用途等に応じるため、耐熱性等の改良が行われてきた。
しかしながら現在、多種多様な食品を包装するため、未だ改良すべき課題が残されている。
その１つには、耐油性による問題がある。包装される多くの食品は艶を出すため等の理由で合成食品用油脂、例えばＭＣＴ（中鎖脂肪酸トリグリセリド）を含有している。通常のスチレン系樹脂延伸シートであると、このような合成食品油脂により短時間の内に侵され、容器が白化したり、容器にクラックが発生して割れるという欠点があった。
【０００４】
また、食品を収納した容器全体をストレッチフィルムでオーバーラップする場合、ストレッチフィルムとして軟質ポリ塩化ビニルフィルムを用いると、フィルム中に含まれる可塑剤やその他の添加剤により、特に容器のフランジ部が侵されて劣化し、非常に割れ易くなるという欠点があった。
スチレン系樹脂延伸シートに耐油性を付与させる方法として、例えば特開昭５４―２９３８１号公報、特定のグラフト型ハイインパクトポリスチレンを用いる方法や、例えば特開平５―３１８５８０号公報、スチレン―メタクリル酸二元共重合体を用いる方法等が提案されているが、いずれも合成食用油脂に対しては侵され易く、とても十分な耐油性を発揮するとは言えない。また、耐油性の良好な樹脂を用いる方法として、例えば特開平４―１４５１５５号公報、実質的に非晶質な特定のポリエステル系重合体と、スチレン系誘導体等よりなる特定の共重合体等を特定割合で配合してなる樹脂組成物を利用する方法や、例えば特開平６―８７１９１号公報、スチレン系樹脂層にプロピレン系樹脂層を積層する方法等が提案されている。
【０００５】
これらの方法では耐油性や耐可塑剤性は改良されても、積層シート製造時に出るトリム、スクラップ、或いは積層シートから成形品を打ち抜いた際に生じるスケルトン（骨）等を再利用することができない。なぜなら上記ポリエステル類、ポリプロピレン類等は、スチレン系樹脂との相溶性が極めて悪く、物性低下が著しい。かりに相溶化剤等の利用により再利用を試みても、コストがかかる上、シートが不透明になってしまい、食品容器用としての価値を失ってしまう。
【０００６】
【発明が解決しようとする課題】
本発明は、上記従来からの課題を解決しようとするものであり、透明性、剛性、成形性などのスチレン系樹脂延伸シートの本来有する諸特性を保ち、且つ食品中の油分やストレッチフィルム中の可塑剤成分によって侵されず、さらに、積層シート製造時に出るトリム、スクラップ、或いは積層シートから成形品を打ち抜いた際に生じるスケルトン（骨）等を再利用することができ、また充分な強度を備えたフードパック等の成形品を得ることができる、安価なスチレン系樹脂積層二軸延伸シートを提供することを目的とするものである。
【０００７】
【課題を解決するための手段】
しかして、本発明においては、上記課題を解決するため次のような手段を講じている。 すなわち本発明は、スチレン系樹脂（ａ）を基材層（Ａ）とし、この基材層（Ａ）の少なくとも一方の面に耐油性樹脂層（Ｂ）が形成されてなるスチレン系樹脂積層二軸延伸シートにおいて、基材層（Ａ）はその厚みが８０〜５００μｍであり、耐油性樹脂層（Ｂ）は、ポリフェニレンエーテル系樹脂（ｂ１）１０〜４０重量％及びスチレン系樹脂（ｂ２）９０〜６０重量％からなる樹脂組成物１００重量部に対して、スチレン系単量体と共役ジエン単量体からなり、共役ジエン単量体に由来する部分が５〜４０重量％であるブロック共重合体からなる透明な耐衝撃性スチレン系樹脂（ｂ３）が５〜４０重量部配合された樹脂組成物から構成され、その厚みが１０〜１００μｍであり、積層シートの配向緩和応力が、流れ方向及びこれと直角方向ともに３〜８ｋｇ／ｃｍ2 となるように二軸延伸されており、耐折強度が２００回以上であり、かつ下記評価方法による耐油性評価においてクレイズやクラックの発生時間が２４時間を越える耐油性を有することを特徴とする耐油性スチレン系樹脂積層二軸延伸シートに存する。
耐油性評価方法：二軸延伸シートより、圧空成形（関西自動成形機ＰＫ−４５０型）により、耐油性樹脂層（Ｂ）が容器の内側となるようにして蓋状成形品（長さ２２６ｍｍ、幅１４７ｍｍ、高さ１２ｍｍ）を成形する。一方、市販のおにぎり型に油分（花王（株）製、商品名ココナードＭＴ、主成分：中鎖脂肪酸トリグリセリド、の原液）を一様に塗布し、炊きたてのご飯を詰めておにぎりを作成した後、これをポリプロピレンより成形した容器（長さ２２３ｍｍ、幅１４４ｍｍ、深さ３０ｍｍ）に詰め、上記成形蓋を乗せて輪ゴムで止める（総重量３６０ｇ）。これを複数個作り、３段に積み重ね、最上段には重量のみ合わせたダミーを乗せ、２３℃の室内に放置し、所定時間ごとに各段の成形蓋についてクレイズやクラックの発生の有無をチェックする。
【０００８】
以下、本発明を詳細に説明する。
本発明のスチレン系樹脂二軸延伸積層シートは、スチレン系樹脂（ａ）よりなる基材層（Ａ）を有する。スチレン系樹脂（ａ）は、特に限定されるものではなく、従来公知の各種のスチレン系樹脂を適宜選択して使用することができる。代表例としては、スチレン、ｏーメチルスチレン、ｍーメチルスチレン、ｐーメチルスチレン、ジメチルスチレン、αーメチルスチレン、ｐークロロスチレン、２，４ージクロロスチレン等のスチレン及びその誘導体よりなる単独重合体、又は共重合体、スチレンもしくは上記スチレン誘導体のうち少なくとも１種とこれら重合体と共重合可能な他の単量体との２元系、３元系もしくは４元系以上の共重合体が挙げられる。また、これら重合体を２種以上混合した混合組成物が挙げられる。
【０００９】
上記共重合可能な他の単量体としては、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ブチル等のメタクリル酸エステル類；アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ブチル等のアクリル酸エステル類；アクリロニトリル、メタクリロニトリル等の不飽和ニトリル化合物；無水マレイン酸、無水イタコン酸等の不飽和カルボン酸無水物；アクリル酸、メタクリル酸等の不飽和カルボン酸等が挙げられる。
【００１０】
これらのスチレン系樹脂（ａ）の中でも、特に、一般用ポリスチレン（スチレンの単独重合体）が透明性に優れ、且つ入手が容易で安価なことから最も好ましい。
この基材層（Ａ）には、シート成形時に発生する耳トリム、シート屑、或いはシートから成形品を打ち抜いた後に発生するスケルトン等のいわゆるリサイクル材を含んでも良く、その量は１０〜５０重量％が好ましい。この時、基材層（Ａ）中のポリフェニレンエーテル系樹脂（ｂ１）の濃度が５％より大きいと、積層シート全体の強度が低下するので好ましくない。
【００１１】
尚、通常リサイクル材は粉砕して小片状にした後、バージン原料とブレンドされ、シート化に供される。
基材層（Ａ）の厚みは８０〜５００μｍであり、好ましくは１００〜３００μｍである。８０μｍ未満であると成形した際の積層シート全体の剛性が低下し、その結果、耐油性樹脂層（Ｂ）への負荷が大きくなり、望ましい耐油性及び耐可塑剤性が得られない。
【００１２】
本発明のスチレン系樹脂二軸延伸積層シートは、基材層（Ａ）の少なくとも一方の面に耐油性樹脂層（Ｂ）が形成されてなり、耐油性樹脂層（Ｂ）は、スチレン系樹脂積層二軸延伸シートに耐油性、耐可塑剤性、耐折性を付与する。
この耐油性樹脂層（Ｂ）は、ポリフェニレンエーテル系樹脂（ｂ１）及びスチレン系樹脂（ｂ２）、さらに透明な耐衝撃性スチレン系樹脂（ｂ３）が特定の割合で混合されてなる樹脂より構成されている。
【００１３】
ポリフェニレンエーテル系樹脂（ｂ１）としては、下記一般式（Ｉ）で表されるものが挙げられる。
【００１４】
【化１】
【００１５】
上記一般式（〓）で表されるポリフェニレンエーテル系樹脂の具体例としては、ポリ（２，６−ジメチル−１，４−フェニレン）エーテル、ポリ（２，６−ジエチル−１，４−フェニレン）エーテル、ポリ（２，６−ジプロピル−１，４−フェニレン）エーテル、ポリ（２−メチル−６−エチル−１，４−フェニレン）エーテル、ポリ（２−メチル−６−プロピル−１，４−フェニレン）エーテル、ポリ（２−エチル−６−プロピル−１，４−フェニレン）エーテル、ポリ（２−メチル−６−ブロム−１，４−フェニレン）エーテル、ポリ（２−メチル−６−クロル−１，４−フェニレン）エーテル、等が挙げられる。
【００１６】
本発明では、ポリフェニレンエーテル系樹脂（ｂ１）として、前記一般式（〓）で表される化学構造を主体とするものであれば共重合可能な他の単量体も使用可能である。このような共重合体の具体例としては、２，６−ジ置換フェノ−ルと２，４−ジ置換フェノ−ルとの共重合体、２，６−ジ置換フェノ−ルと２，３、６−トリ置換フェノ−ルとの共重合体、２，６−ジメチルフェノ−ルと２−置換フェノ−ル、３−置換フェノ−ルまたは４−置換フェノ−ルとの共重合体等が挙げられる。
【００１７】
これらの中では、ポリ（２，６−ジメチル−１，４−フェニレン）エーテルが特に好ましい。また、その重合体の固有粘度（クロロホルム、２５℃測定）は０.２〜１ｄｌ／ｇの範囲が好ましく、０.３〜０.７ｄｌ／ｇの範囲のものを使用したときには、機械的強度及び成形性の優れたスチレン系樹脂積層二軸延伸シートが得られ、更に好ましい。
【００１８】
スチレン系樹脂（ｂ２）は、スチレン、ｏーメチルスチレン、ｍーメチルスチレン、ｐーメチルスチレン、ジメチルスチレン、αーメチルスチレン、ｐークロロスチレン、２，４ージクロロスチレン等のスチレン及びその誘導体よりなる単量体、又は共重合体、スチレンもしくは上記スチレン誘導体のうち少なくとも１種とこれら重合体と共重合可能な他の単量体との２元系、３元系もしくは４元系以上の共重合体が挙げられる。また、これら重合体を２種以上混合した混合組成物が挙げられる。
【００１９】
透明性、分散性の点から、またシート上への未溶融物等の発生を極力抑えるためにもスチレン系樹脂（ａ）と同じ組成のものを用いるのが好ましく、一般用ポリスチレン（スチレンの単独重合体）が透明性に優れ、且つ入手が容易で安価なことから最も好ましい。
耐油性樹脂層（Ｂ）に用いる透明な耐衝撃性スチレン系樹脂（ｂ３）は、透明であれば特に限定されるものではないが、スチレン系単量体と共役ジエン単量体からなるブロック共重合体が好ましい。スチレン系単量体としては、前記スチレン系樹脂（ｂ２）と同じ組成のものが好ましく、特にスチレンが好ましい。共役ジエン単量体としては１，３―ブタジエン、イソプレン、２，３―ジメチル―１，３ブタジエン、１，３―ヘキサジエンなどが挙げられるが、１，３―ブタジエンが好ましい。これらブロック共重合体の構造はＡ−Ｂ、Ａ−Ｂ−Ａ等いかなる構造でもかまわない。この時、共役ジエン単量体に由来する部分が５〜４０重量％であるのが好ましく、１０〜３０重量％が更に好ましい。４０重量％よりも多いと、シートの透明性が低下したり、コストも高くなるので好ましくない。また、スチレンージエンブロック共重合体が水添されているとシートの透明性が失われて好ましくない。
【００２０】
本発明シートの耐油性樹脂層（Ｂ）を形成する前記ポリフェニレンエーテル系樹脂（ｂ１）、スチレン系樹脂（ｂ２）及び透明な耐衝撃性スチレン系樹脂（ｂ３）の混合割合は、ポリフェニレンエーテル系樹脂（ｂ１）１０〜４０重量％、スチレン系樹脂（ｂ２）９０〜６０重量％、及びこれら混合樹脂１００重量部に対して透明な耐衝撃性スチレン系樹脂（ｂ３）が３〜４０重量部である。
【００２１】
ポリフェニレンエーテル系樹脂（ｂ１）が１０重量％未満で、スチレン系樹脂（ｂ２）が９０重量％より多いと、得られるスチレン系樹脂二軸延伸積層シートの耐油性、耐可塑剤性を十分に発揮させることができない。他方、ポリフェニレンエーテル系樹脂が４０重量％より多く、スチレン系樹脂（ｂ２）が６０重量％未満であると、シートの透明性が低下し、コストが高くなり、また、耐油性樹脂層（Ｂ）と基材層（Ａ）の溶融粘度差が大きくなるため、共押出時のシート成形性及び二次加工時の成形性が難しくなり、生産性が悪くなってしまう。更に好ましくは（ｂ１）の割合が１５〜２５重量％、且つ（ｂ２）のそれが８５〜７５重量％である。これらは、製品の耐油性、耐可塑剤性、低コスト等の目的に合わせて合理的に決められる。
【００２２】
また、透明な耐衝撃性スチレン系樹脂（ｂ３）の混合割合は、上記（ｂ１）と（ｂ２）の混合樹脂１００重量部に対して５〜４０重量部、特に５〜２０重量部が好ましい。（ｂ３）をこの範囲内で混合することによって、ポリフェニレンエーテル系樹脂（ｂ１）とスチレン系樹脂（ｂ２）との相溶性を向上することができ、その結果、シートの表面にゲル化したポリフェニレンエーテル系樹脂に由来するブツなどが現れることなく、外観に優れたシートを得られる。また、本発明に係るシートの要件である十分な耐折強度が得られる。更に透明な耐衝撃性スチレン系樹脂とポリフェニレンエーテル系樹脂を併用することにより、耐油性をより向上させる。
【００２３】
（ｂ３）の混合割合が５重量部未満であると、ポリフェニレンエーテル系樹脂（ｂ１）とスチレン系樹脂（ｂ２）との相溶性の向上、並びに十分な耐折強度が期待できない。従って蓋、容器等の成形品にした場合に、耐油性樹脂層（Ｂ）に掛かる応力ひずみが大きくなり、機械的強度不足による割れや、合成食用油脂等によるクラックや白化が生じてしまう。一方、４０重量部より多いと透明性を著しく低下させる上、かなりのコスト高になってしまう。
【００２４】
（ｂ１）、（ｂ２）、（ｂ３）の混合方法は特に制限はなく、一般の溶融混練による混合でも良いし、共重合による混合でも良い。溶融混練の場合にはポリフェニレンエーテル系樹脂（ｂ１）とスチレン系樹脂（ｂ２）をあらかじめ溶融混練してペレット化し、シート成形時に透明な耐衝撃性スチレン系樹脂（ｂ３）ペレットとドライブレンドするか、３者を同時に溶融混練してペレット化する方法が好ましい。共重合の場合は、ポリフェニレンエーテル系樹脂（ｂ１）をスチレン系樹脂（ｂ２）の量に相当する量の単量体に溶解させ、重合した後にペレット化し、シート成形時に透明な耐衝撃性スチレン系樹脂（ｂ３）ペレットとドライブレンドするか、ポリフェニレンエーテル系樹脂（ｂ１）と透明なスチレン―ブタジエンブロック共重合体をスチレン系樹脂（ｂ２）に相当する単量体に溶解させ、３者を同時に共重合した後ペレット化する方法が好ましい。
【００２５】
ポリフェニレンエーテル系樹脂のスチレン系単量体への溶解は、適宜の溶解槽を利用し、６０〜１００℃、好ましくは７０〜９０℃の温度で１〜２時間攪拌を続けることにより行われる。溶解温度が６０℃未満の場合は、ポリフェニレンエーテル系樹脂が十分に溶解せずにスラリー状となり、また１００℃を越える場合はスチレンの熱重合が促進されてしまう。
【００２６】
また、重合の形式は、懸濁重合、溶液重合、塊状重合のいずれによっても良い。ラジカル重合開始剤としては、例えば、ｔ-ブチルペルオキシド、ジ-ｔ-ブチルペルオキシド、クメンヒドロペルオキシド、ジクミルペルオキシド、ベンゾイルペルオキシド、１,１-ビス（ｔ-ブチルペルオキシド）シクロヘキサン、１,１-ビス（ｔ-ブチルペルオキシ）-３,３,５-トリメチルシクロヘキサン、２,２-ビス（４,４-ジ-ｔ-ブチルペルオキシシクロヘキシル）プロパノンなどの有機過酸化物、アゾビスイソブチロニトリル、アゾビス-２,４-ジメチルバレロニトリル、アゾビスシクロヘキサンカルボニトリル、アゾビスイソ酪酸メチル、アゾビスシアノ吉草酸、１-ｔ-ブチルアゾ-１-シアノシクロヘキサン、１,１'-アゾビス-１-カルボニトリルなどのアゾ化合物が挙げられる。重合開始剤は、スチレン系単量体を重合させるために適当な量で使用することができるが、スチレン系単量体１００重量部に対し０.１〜１０重量％が好ましい。
【００２７】
耐油性樹脂層（Ｂ）の厚みは１０〜１００μｍのものであるのが好ましい。耐油性樹脂層（Ｂ）の厚みが１０μｍ未満であると、耐油性樹脂層（Ｂ）中のポリフェニレンエーテル系樹脂（ｂ１）の割合を高めても、成形品表面に付着したＭＣＴ等の油分が基材層（Ａ）まで浸透してしまい、成形品にクレイズやクラックが生じてしまう。万一、成形品にキズ等が入った場合は特に顕著である。一方、１００μｍを超えるとシートの二次加工性が悪くなり、透明性も劣るため食品容器としての使用に適さなくなる。
【００２８】
実際の耐油性樹脂層（Ｂ）の厚みは、層厚みとの関係で、成形する容器の用途、要求される耐油性、耐可塑剤性、コストに応じて適宜選択されるが、例えば層厚みが２００〜３００μｍであるときには、耐油性樹脂層（Ｂ）は通常１５〜９０μｍ、特に好ましくは２０〜６０μｍであるのが良い。
本発明の積層シートは、ＡＳＴＭ Ｄ−１５０４に準拠して測定した配向緩和応力が、シートの流れ方向及びこれと直角方向ともに３〜８ｋｇ／ｃｍ2となるように延伸されてなり、強度と成形性とを兼ね備えている。配向緩和応力が３ｋｇ／ｃｍ2未満であると実用強度を有する成形品が得られず、また８ｋｇ／ｃｍ2を超えると型決まりの悪い成形品しか得られない。
【００２９】
本発明の積層シートは、折り曲げ角度を左右に９０°とするように変更した他はＡＳＴＭ Ｄ−２１７６に準拠して測定した耐折強度（縦横の平均値）が、２００回以上であることが必要である。耐折強度が２００回より少ないと、食品容器としての使用に適さない。
本発明の積層シートは、２４時間を超える耐油性を有することが必要である。２４時間を超える耐油性を有するとは、後記する耐油性評価方法において、２４時間以内にシート表面にクレイズやクラックが発生しないことを意味する。耐油性が２４時間以内であると、本発明のシートの用途の１つである食品用容器として好ましくない。
【００３０】
本発明の積層シートにおいて、基材層（Ａ）に用いるスチレン系樹脂（ａ）及び耐油性樹脂層（Ｂ）を構成するスチレン系樹脂（ｂ２）は、好ましくは一般用ポリスチレンとし、ＡＳＴＭ Ｄ−１００３に準拠して測定した積層シートの透明度は好ましくは７０％以上である。更に好ましくは、透明度が８０％以上である。透明度が７０％未満であると、食品用容器として使用する際、見栄えが悪くなる。
【００３１】
本発明のスチレン系樹脂二軸延伸積層シートの層構成としては、容器成形に供する際に容器の食品収納側が耐油性樹脂層（Ｂ）となるようにすれば制限はないが、シートの製造、成形性とのバランス等を考えると特に２層構造、３層構造のものが好ましい。具体的には、耐油性樹脂層（Ｂ）／基材層（Ａ）の２層構造、または耐油性樹脂層（Ｂ）／基材層（Ａ）／耐油性樹脂層（Ｂ）の３層構造が挙げられる。このように使用することにより、２層構造のものは容器の内面とフランジ部とで耐油性、耐可塑剤性を発揮し、また３層構造のものは容器の内面とフランジ部での耐油性、耐可塑剤性に加え、容器の外壁部や底部でも同様に良好な耐油性、耐可塑剤性を発揮する。
【００３２】
また、必要によっては、本発明の特性が損なわれない範囲内で、接着剤層、１００％または自由な混合比率での回収樹脂層、その他の樹脂よりなる付加層を加えても良い。
本発明のスチレン系樹脂二軸延伸積層シートは、基材層（Ａ）用のスチレン系樹脂（ａ）、及び耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）をそれぞれ準備し、従来より知られている積層二軸延伸シートの製造方法に従って容易に製造することができる。
【００３３】
具体的には、（イ）２台の押出機を用い、それぞれよりスチレン系樹脂（ａ）及び樹脂組成物（ｂ）を溶融押出しし、２層または３層構成の多層Ｔダイにより前記２層構造または３層構造の未延伸積層シートを得、次いで従来より公知の方法で二軸方向に延伸する方法、
（ロ）２台の押出機を用い、それぞれよりスチレン系樹脂（ａ）及び樹脂組成物（ｂ）を溶融押出しし、２個または３個の単層Ｔダイにより基材層（Ａ）用の溶融状シート１枚と耐油性樹脂層（Ｂ）用の溶融状シート１枚または２枚とを別々に得、これらが未だ溶融状態にあるうちに圧着積層して前記２層構造または３層構造の未延伸積層シートを得、次いで従来より公知の方法により二軸方向に延伸する方法、
（ハ）基材層（Ａ）用のスチレン系樹脂（ａ）よりなる二軸延伸シート、及び耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）よりなる二軸延伸シートの２種の二軸延伸シートを別々に製造し、これらの二軸延伸シートを接着剤を用いて接着する方法、等が挙げられる。
【００３４】
【実施例】
次に、本発明を実施例及び比較例により具体的に説明するが、本発明は、その要旨を超えない限りこれらの実施例の記載に限定されるものではない。なお、以下の記載において、特に記載のない限り「部」は重量基準を意味する。
各実施例、比較例により得られた二軸延伸シートについて、下記の方法で評価した。
（１）配向緩和応力
得られた二軸延伸シートの配向緩和応力をＡＳＴＭ Ｄ−１５０４準拠して、シートの流れ方向及びこれと直角方向に測定した。
（２）耐折強度
得られた二軸延伸シートの耐折強度を、折り曲げ角度を左右９０°に変更した他はＡＳＴＭ Ｄ−２１７６に準拠してシートの流れ方向及びこれと直角方向に測定し、平均値を求めた。
（３）耐油性
得られた二軸延伸シートより、圧空成形（関西自動成形機ＰＫ―４５０型）により蓋状成形品（長さ２２６ｍｍ、幅１４７ｍｍ、高さ１２ｍｍ）を得た。この時、２種２層シートの場合には耐油性樹脂層（Ｂ）が容器の内側となるようにした。一方、市販のおにぎり型に油分（花王（株）製、商品名ココナードＭＴ、主成分：中鎖脂肪酸トリグリセリド、の原液）を一様に塗布し、炊きたてのご飯を詰めておにぎりを作成した後、これを汎用のポリプロピレンより成形した容器（長さ２２３ｍｍ、幅１４４ｍｍ、深さ３０ｍｍ）に詰め、上記成形蓋を乗せて輪ゴムで止めた（総重量３６０ｇ）。これを複数個作り、３段に積み重ね（最下段から１段目、２段目、３段目とする）、最上段には重量のみ合わせたダミーを乗せ、２３℃の室内に放置し、所定時間ごとに各段の成形蓋についてクレイズやクラックの発生の有無をチェックした。評価の基準は次の通りとした。
【００３５】
××：
２時間以内にクレイズやクラック発生
× ：６時間以内にクレイズやクラック発生
△ ：２４時間以内にクレイズやクラック発生
○ ：２４時間以内にはクレイズやクラックは発生しなかったが、
４８時間以内に発生
◎ ：４８時間経過後もクレイズやクラック発生せず
（４）耐可塑剤性
上記、（３）耐油性の評価に供したのと同様の成形蓋を成形した。但し、２種２層シートの場合には耐油性樹脂層（Ｂ）が容器の外側となるようにした。次に、（３）耐油性の評価に使用したのと同じ汎用ポリプロピレン製の容器に炊き立てのご飯を詰め、成形蓋を乗せた（総重量３６０ｇ）。次にこれをストレッチ自動包装機（フジパックシステム（株）製、Ａ−１２型）に掛け、市販のポリ塩化ビニル製ストレッチフィルム（三菱樹脂（株）製、商品名ダイヤラップ）を使用してラップ包装した。これを複数個作り、３段に積み重ね（最下段から１段目、２段目、３段目とする）、最上段には重量のみ合わせたダミーを乗せ、２３℃の室内に放置し、所定時間ごとに各段の成形蓋のフランジ部や角部についてクレイズやクラックの発生の有無をチェックした。評価の基準は次の通りとした。
【００３６】
× ：６時間以内にクレイズやクラック発生
△ ：２４時間以内にクレイズやクラック発生
○ ：４８時間以内にクレイズやクラック発生
◎ ：４８時間経過後もクレイズやクラック発生せず
（５）透明度
得られた二軸延伸シートの透明度（％）をＡＳＴＭ Ｄ−１００３に準拠して測定し、次の評価基準で表した。
【００３７】
× ：７０％未満
△ ：７０％以上、８０％未満
○ ：８０％以上、９０％未満
◎ ：９０％以上
使用した樹脂及び単量体は、以下の通りである。
・スチレン系樹脂（ａ）（ｂ１）：三菱化学（株）製、商品名「ダイヤレックスＨＨ−１０２」（以下、ＧＰＰＳという）
・ポリフェニレンエーテル系樹脂（ｂ２）：三菱ガス化学（株）製、商品名「ＹＰＸ−１００Ｌ」、主成分；ポリ（２，６ージメチルー１，４ーフェニレン）エーテル（以下、ＰＰＥという）
・透明な耐衝撃性スチレン系樹脂（ｂ３）：旭化成（株）製、商品名「アサフレックス８１５」（ゴム成分含有率約２５％）（以下、ＳＢＢＣという）
・スチレン単量体（以下、ＳＭという）
尚、以下の実施例及び比較例中、シートの層構成比率の調節・変更、或いはシート全体厚みの調節・変更は各押出機の押出量とラインの速度をコントロールすることによって行なった。
実施例１
基材層（Ａ）用のスチレン系樹脂（ａ）としてＧＰＰＳを使用した。一方、ＰＰＥ２０部に対し、ＧＰＰＳ８０部を加え、同方向回転二軸押出機（東芝機械(株)製）を用いて３１０℃の条件で溶融混合することにより、２成分からなる中間樹脂組成物をペレット化して調整した。この中間樹脂組成物１００部に対してＳＢＢＣのペレット５部をドライブレンドしたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として使用した。
【００３８】
次に、２台のベント式押出機（プラ技研（株）製と池貝鉄工（株）製）を用い、これに２種２層用フィードブロック及びコートハンガータイプのＴ―ダイ（いずれもプラ技研（株）製）を取り付け、一方の押出機に前記スチレン系樹脂（ａ）を、他方の押出機に前記樹脂組成物（ｂ）を供給し、共押出しして厚み約１.４ｍｍの未延伸２層シートを得た。引き続き未延伸２層シートをロール方式縦延伸機、次いでテンター横延伸機にて、縦方向に約２.６倍、横方向に約２.５倍それぞれ延伸することにより、基材層（Ａ）の厚みが１９２μｍ、耐油性樹脂層（Ｂ）の厚みが１８μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００３９】
得られたシートの評価結果を表１に示す。
実施例２
実施例１と同じのスチレン系樹脂（ａ）の７０部に、実施例１で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）は実施例１と全く同じにして、実施例１と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７２μｍ、耐油性樹脂層（Ｂ）の厚みが４０μｍで、全厚み２１２μｍの二軸延伸シートを得た。
【００４０】
得られたシートの評価結果を表１に示す。
実施例３
基材層（Ａ）用のスチレン系樹脂（ａ）としてＧＰＰＳを使用した。一方、ＰＰＥ１０部に対し、ＧＰＰＳ９０部を加え、同方向回転二軸押出機（東芝機械(株)製）を用いて３１０℃の条件で溶融混合することにより、２成分からなる中間樹脂組成物をペレット化して調整した。この中間樹脂組成物１００部に対してＳＢＢＣのペレット１０部をドライブレンドしたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として使用した。以後は実施例１と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７２μｍ、耐油性樹脂層（Ｂ）の厚みが３９μｍで、全厚み２１１μｍの二軸延伸シートを得た。
【００４１】
得られたシートの評価結果を表１に示す。
実施例４
実施例１と同じＧＰＰＳ７０部に、実施例３で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例３と同じ中間樹脂組成物１００部に対してＳＢＢＣ３０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として、実施例１と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７１μｍ、耐油性樹脂層（Ｂ）の厚みが４０μｍで、全厚み２１１μｍの二軸延伸シートを得た。
【００４２】
得られたシートの評価結果を表１に示す。
実施例５
フィードブロックを２種２層から２種３層に変えた以外は実施例１と全く同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１６９μｍ、両側の耐油性樹脂層（Ｂ）の厚みが２０μｍで、全厚み２０９μｍの二軸延伸シートを得た。
【００４３】
得られたシートの評価結果を表１に示す。
実施例６
実施例１と同じＧＰＰＳ７０部に、実施例５で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）は実施例５と全く同じにして、実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１２０μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１８μｍで、全厚み１５６μｍの二軸延伸シートを得た。
【００４４】
得られた二軸延伸シートの評価結果を表１に示す。
実施例７
実施例１と同じＧＰＰＳ７０部に、実施例５で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例１と同じ中間樹脂組成物１００部に対してＳＢＢＣを２０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として、実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７０μｍ、両側の耐油性樹脂層（Ｂ）の厚みが２０μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００４５】
得られたシートの評価結果を表１に示す。
実施例８
実施例１と同じＧＰＰＳの７０部に、実施例５で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例１と同じ中間樹脂組成物（ｂ’）１００部に対してＳＢＢＣを４０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として、実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７６μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１６μｍで、全厚み２０８μｍの二軸延伸シートを得た。
【００４６】
得られたシートの評価結果を表１に示す。
実施例９
実施例１と同じＧＰＰＳ７０部に、実施例６で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例３と同じ中間樹脂組成物１００部に対してＳＢＢＣを２０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として、実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが３６９μｍ、両側の耐油性樹脂層（Ｂ）の厚みが３９μｍで、全厚み４４７μｍの二軸延伸シートを得た。
【００４７】
得られたシートの評価結果を表１に示す。
実施例１０
基材層（Ａ）用のスチレン系樹脂（ａ）としてＧＰＰＳを使用した。ＰＰＥ４０重量部に対してＧＰＰＳ６０部を加え、同方向回転二軸押出機（東芝機械(株)製）を用いて３２０℃の条件で溶融混合することにより、２成分からなる中間樹脂組成物をペレット化して調整した。この中間樹脂組成物１００部に対してＳＢＢＣを１０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例５と同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１８０μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１５μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００４８】
得られたシートの評価結果を表１に示す。
実施例１１
実施例１と同じＧＰＰＳ７０部に、実施例６で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、耐油性樹脂層（Ｂ）用の中間樹脂組成物に下記の重合品を用いた。
【００４９】
即ち、いかり型の攪拌翼を備えた５０Ｌの溶解層にＰＰＥ５.０kg、ＳＭ１５.０kgを入れ８０℃に昇温し、ＰＰＥをＳＭに十分溶解させるため６０分間攪拌を続けた。その後、熱脱イオン水２０kg、ドデシルベンゼンスルホン酸ナトリウム１.０kg、ポリアクリレート系懸濁剤の２％水溶液４５０g、硫酸ナトリウム１００gを加えて１２０℃に昇温した。１２０℃に達した後、ジクミルパーオキサイド３０gを加え５時間かけて１５０℃に昇温し、更に、１時間保ち反応を終了した。得られたビードを乾燥した後、単軸押出機（プラ技研(株)製）により２６０℃設定で１パス溶融混錬させてペレットを得た。
【００５０】
この中間樹脂組成物１００部に対してＳＢＢＣのペレット５部をドライブレンドしたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として使用した。実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７５μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１８μｍで、全厚み２１１μｍの二軸延伸シートを得た。
【００５１】
得られたシートの評価結果を表１に示す。
比較例１
１台のベント式押出機（池貝鉄工（株）製）を用い、これに単層用フィードブロック及びコートハンガータイプのＴ―ダイ（いずれもプラ技研（株）製）を取り付け、スチレン系樹脂（ａ）としてＧＰＰＳを使用した。以後は実施例１と同じ方法で延伸することにより、全厚み２１０μｍの単層二軸延伸シートを得た。
【００５２】
得られたシートの評価結果を表２に示す。
比較例２
実施例３と同じ中間樹脂組成物をそのまま耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例１と同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１９２μｍ、耐油性樹脂層（Ｂ）の厚みが１８μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００５３】
得られたシートの評価結果を表２に示す。
比較例３
実施例３と同じ中間樹脂組成物１００部に対してＳＢＢＣを２０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例１と全く同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが２０５μｍ、耐油性樹脂層（Ｂ）の厚みが５μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００５４】
得られたシートの評価結果を表２に示す。
比較例４
基材層（Ａ）用のスチレン系樹脂（ａ）としてＧＰＰＳを使用した。一方、ＰＰＥ５０部に対し、ＧＰＰＳ５０部を加え、同方向回転二軸押出機（東芝機械(株)製）を用いて３２０℃の条件で溶融混合することにより、２成分からなる中間樹脂組成物をペレット化して調整した。この中間樹脂組成物をそのまま耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として使用した。以後は実施例１と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１９３μｍ、耐油性樹脂層（Ｂ）の厚みが１６μｍで、全厚み２０９μｍの二軸延伸シートを得た。
【００５５】
得られたシートの評価結果を表２に示す。
比較例５
基材層（Ａ）用の樹脂組成物として、ＧＰＰＳを使用した。耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）としてＧＰＰＳ１００部にＳＢＢＣのペレット２０部をドライブレンドしたものを使用した。以後は実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１６９μｍ、両側の耐油性樹脂層（Ｂ）の厚みが２０μｍで、全厚み２０９μｍの二軸延伸シートを得た。
【００５６】
得られたシートの評価結果を表２に示す。
比較例６
実施例１と同じ中間樹脂組成物をそのまま耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例５と同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１８０μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１６μｍで、全厚み２１２μｍの二軸延伸シートを得た。
【００５７】
得られたシートの評価結果を表２に示す。
比較例７
実施例１と同じＧＰＰＳ７０部に、実施例５で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例１と同じ中間樹脂組成物１００部に対してＳＢＢＣを３０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）として、実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが２００μｍ、両側の耐油性樹脂層（Ｂ）の厚みが５μｍで、全厚み２１０μｍの二軸延伸シートを得た。
【００５８】
得られたシートの評価結果を表２に示す。
比較例８
実施例１と同じ中間樹脂組成物１００部に対してＳＢＢＣを５０部加えたものを耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例５と同じ樹脂、同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１１９μｍ、両側の耐油性樹脂層（Ｂ）の厚みが１８μｍで、全厚み１５５μｍの二軸延伸シートを得た。
【００５９】
得られたシートの評価結果を表２に示す。
比較例９
実施例１と同じＧＰＰＳ７０部に、比較例６で得た二軸延伸シートの粉砕品３０部を加えたものを基材層（Ａ）に用い、実施例１１と同じ中間樹脂組成物をそのまま耐油性樹脂層（Ｂ）用の樹脂組成物（ｂ）とした以外は実施例５と同じ方法で共押出し、共延伸することにより、基材層（Ａ）の厚みが１７１μｍ、両側の耐油性樹脂層（Ｂ）の厚みが２０μｍで、全厚み２１１μｍの二軸延伸シートを得た。
【００６０】
得られたシートの評価結果を表２に示す。
一方、耐衝撃性ポリスチレンの替わりに汎用ポリスチレンを用いてもポリフェニレンエーテル系樹脂と任意の組成で混ざり合って完全相溶系を形成することが知られているが、実際にはポリフェニレンエーテル系樹脂の高い軟化点と低い流動性のため、特別な場合を除き、完全溶解させることは困難である。混練、押出条件によっては混合樹脂組成物中に未溶融のポリフェニレンエーテル系樹脂、或いはゲル化したポリフェニレンエーテル系樹脂に由来する”ブツ”や”焼けポリ”が見受けられることがある。これらの異物は、例えば着色した射出成形品の場合には、中に潜り込んで目立たなくなるだろうが、食品容器成形用の二軸延伸シートの場合には、該シートが透明性故に目立ち易く、また食品容器用という観点からも極力排除しなければならない。
【００６１】
【表１】
【表２】
【発明の効果】
本発明のスチレン系樹脂積層二軸延伸シートは、耐油性樹脂層を特定の配合割合で混合したポリフェニレンエーテル系樹脂、スチレン系樹脂及び透明な耐衝撃性スチレン系樹脂の組成物で構成し、積層シートが特定の物性値を兼ね備えることにより、耐油性、耐可塑剤性、耐折性に優れ、且つ透明性、剛性、成形性を併せ持つ上、シート自身のリサイクルが可能で、成形品においても充分な強度がある。そのため、安価にして性質の優れた食品包装用シートに広く用いることができる。特に食品油が使用される食品の包装に最適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a styrene resin laminated biaxially stretched sheet. More specifically, foods that retain the inherent properties of a stretched styrene resin sheet such as transparency, rigidity, and moldability, and that are excellent in oil resistance, plasticizer resistance, recyclability, folding resistance, and contain oil. The present invention relates to a styrene-based resin laminated biaxially stretched sheet that is inexpensive and suitable as a molding material for containers that are used for wrap packaging.
[0002]
[Prior art]
Styrenic resin stretched sheets, especially biaxially stretched sheets made of styrene resin mainly composed of general-purpose polystyrene, show good transparency, strong stiffness, and excellent moldability, vacuum forming method and pressure forming Since containers and the like can be easily formed by a thermoforming method such as the method, they are mainly used in the manufacture of lightweight containers for food packaging.
[0003]
In addition, heat resistance and the like have been improved so far in order to respond to uses such as cooking in a microwave oven and direct contact with boiling water.
However, at present, there are still problems to be improved in order to package a wide variety of foods.
One of them is a problem due to oil resistance. Many foods to be packaged contain synthetic food fats and oils such as MCT (medium chain fatty acid triglycerides) for reasons such as gloss. In the case of a normal styrene resin stretched sheet, such synthetic food oils and fats are eroded within a short time, and the container is whitened or cracked by cracking the container.
[0004]
In addition, when the entire container containing food is overlapped with a stretch film, if a soft polyvinyl chloride film is used as the stretch film, the flange portion of the container is particularly affected by the plasticizer and other additives contained in the film. As a result, it has deteriorated and has a drawback of becoming very easy to break.
As a method for imparting oil resistance to a stretched styrenic resin sheet, for example, Japanese Patent Application Laid-Open No. 54-29381, a method using specific graft type high impact polystyrene, for example, Japanese Patent Application Laid-Open No. 5-318580, styrene-methacrylic acid Although a method using an original copolymer has been proposed, all of them are easily eroded by synthetic edible fats and oils and cannot be said to exhibit very sufficient oil resistance. Further, as a method using a resin having good oil resistance, for example, JP-A-4-145155, a specific polyester polymer substantially amorphous and a specific copolymer composed of a styrene derivative or the like For example, Japanese Patent Application Laid-Open No. 6-87191, a method of laminating a propylene resin layer on a styrene resin layer, and the like have been proposed.
[0005]
Even if oil resistance and plasticizer resistance are improved by these methods, trim, scrap, or skeleton (bone) generated when a molded product is punched from the laminated sheet cannot be reused. . This is because the polyesters, polypropylenes and the like have extremely poor compatibility with the styrene resin, and the physical properties are remarkably lowered. Even if reuse is attempted by using a compatibilizing agent or the like, the cost is increased and the sheet becomes opaque and loses its value as a food container.
[0006]
[Problems to be solved by the invention]
The present invention is intended to solve the above-mentioned conventional problems, maintains various properties inherent to the stretched styrenic resin sheet such as transparency, rigidity, moldability, etc., and also contains oils in foods and stretch films. It is not affected by the plasticizer component, and it can be reused for trim, scrap, or skeleton (bone) generated when a molded product is punched from the laminated sheet. Another object of the present invention is to provide an inexpensive styrene-based resin laminated biaxially stretched sheet from which a molded product such as a food pack can be obtained.
[0007]
[Means for Solving the Problems]
Therefore, in the present invention, the following means are taken in order to solve the above problems. That is, according to the present invention, a styrene-based resin laminate (A) having a styrene-based resin (a) as a base layer (A) and an oil-resistant resin layer (B) formed on at least one surface of the base layer (A). In the axially stretched sheet, the base material layer (A) has a thickness of 80 to 500 μm, and the oil-resistant resin layer (B) is composed of 10 to 40% by weight of a polyphenylene ether resin (b1) and a styrene resin (b2) 90. A block copolymer consisting of a styrene monomer and a conjugated diene monomer, and a portion derived from the conjugated diene monomer is 5 to 40% by weight with respect to 100 parts by weight of the resin composition comprising ˜60% by weight. It is composed of a resin composition containing 5 to 40 parts by weight of a transparent impact-resistant styrenic resin (b3) made of a coalescence, its thickness is 10 to 100 μm, and the orientation relaxation stress of the laminated sheet is the flow direction and Perpendicular to this 3-8kg / cm for both directions 2 It is biaxially stretched so that the folding resistance is 200 times or more, and the oil resistance evaluation by the following evaluation method has oil resistance that exceeds 24 hours in the occurrence of crazes and cracks. It exists in the oil-resistant styrene resin laminated biaxially stretched sheet.
Oil resistance evaluation method: compressed air molding from biaxially stretched sheet (Kansai automatic molding machine PK-450 type) To make the oil-resistant resin layer (B) inside the container (Length 226mm, width 147mm, height 12mm) Is molded. On the other hand, oil ( Product name, Coconard MT, manufactured by Kao Corporation. Medium chain triglycerides , A uniform solution), and then cooked rice and stuffed with rice to make rice balls, and then molded this from polypropylene (Length 223mm, width 144mm, depth 30mm) And put on the molding lid and fasten with rubber bands (total weight 360 g). Make a number of them, stack them in three stages, put a dummy with only the weight on the top stage, leave it in a room at 23 ° C, and check for the occurrence of crazes and cracks in the molding lid at each stage every predetermined time To do.
[0008]
Hereinafter, the present invention will be described in detail.
The styrene resin biaxially stretched laminated sheet of the present invention has a base material layer (A) made of a styrene resin (a). The styrene resin (a) is not particularly limited, and various conventionally known styrene resins can be appropriately selected and used. Typical examples include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, dimethyl styrene, α-methyl styrene, p-chloro styrene, 2,4-dichloro styrene and the like homopolymers or copolymers, styrene or A binary, ternary, or quaternary or higher copolymer of at least one of the styrene derivatives and another monomer copolymerizable with these polymers may be used. Moreover, the mixed composition which mixed 2 or more types of these polymers is mentioned.
[0009]
Examples of the other copolymerizable monomers include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Acrylic acid esters such as; unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; unsaturated carboxylic acids such as acrylic acid and methacrylic acid, etc. .
[0010]
Among these styrenic resins (a), in particular, general-purpose polystyrene (styrene homopolymer) is most preferable because it is excellent in transparency, easily available, and inexpensive.
This base material layer (A) may contain so-called recycled materials such as ear trims, sheet waste, or skeleton generated after punching a molded product from the sheet, and the amount thereof is 10 to 50 weights. % Is preferred. At this time, if the concentration of the polyphenylene ether-based resin (b1) in the base material layer (A) is greater than 5%, the strength of the entire laminated sheet is not preferable.
[0011]
Normally, the recycled material is pulverized into small pieces, then blended with the virgin raw material and used for forming a sheet.
The thickness of the base material layer (A) is 80 to 500 μm, preferably 100 to 300 μm. When the thickness is less than 80 μm, the rigidity of the entire laminated sheet is reduced when it is molded. As a result, the load on the oil-resistant resin layer (B) increases, and desired oil resistance and plasticizer resistance cannot be obtained.
[0012]
The styrenic resin biaxially stretched laminated sheet of the present invention has an oil-resistant resin layer (B) formed on at least one surface of the base material layer (A), and the oil-resistant resin layer (B) is a styrene resin. Add oil resistance, plasticizer resistance, and folding resistance to the laminated biaxially oriented sheet.
The oil-resistant resin layer (B) is composed of a resin obtained by mixing a polyphenylene ether-based resin (b1) and a styrene-based resin (b2) and a transparent impact-resistant styrene-based resin (b3) at a specific ratio. ing.
[0013]
Examples of the polyphenylene ether resin (b1) include those represented by the following general formula (I).
[0014]
[Chemical 1]
[0015]
Specific examples of the polyphenylene ether resin represented by the general formula (式) include poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,6-diethyl-1,4-phenylene). Ether, poly (2,6-dipropyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ether, poly (2-methyl-6-propyl-1,4-phenylene) Phenylene) ether, poly (2-ethyl-6-propyl-1,4-phenylene) ether, poly (2-methyl-6-bromo-1,4-phenylene) ether, poly (2-methyl-6-chloro-) 1,4-phenylene) ether and the like.
[0016]
In the present invention, other copolymerizable monomers can be used as the polyphenylene ether-based resin (b1) as long as it mainly has the chemical structure represented by the general formula (〓). Specific examples of such copolymers include copolymers of 2,6-disubstituted phenol and 2,4-disubstituted phenol, 2,6-disubstituted phenol and 2,3. A copolymer of 6-trisubstituted phenol, a copolymer of 2,6-dimethylphenol and 2-substituted phenol, 3-substituted phenol or 4-substituted phenol, etc. Can be mentioned.
[0017]
Of these, poly (2,6-dimethyl-1,4-phenylene) ether is particularly preferred. Further, the intrinsic viscosity of the polymer (chloroform, measured at 25 ° C.) is preferably in the range of 0.2 to 1 dl / g, and when a polymer having a range of 0.3 to 0.7 dl / g is used, the mechanical strength and A styrenic resin laminated biaxially stretched sheet having excellent moldability is obtained, and is more preferable.
[0018]
Styrene resin (b2) is a monomer or copolymer comprising styrene such as styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, dimethyl styrene, α-methyl styrene, p-chloro styrene, 2,4-dichloro styrene, and derivatives thereof. Binary or ternary or quaternary or higher copolymers of styrene or at least one of the above styrene derivatives and other monomers copolymerizable with these polymers. Moreover, the mixed composition which mixed 2 or more types of these polymers is mentioned.
[0019]
From the viewpoint of transparency and dispersibility, and in order to suppress the occurrence of unmelted material on the sheet as much as possible, it is preferable to use a resin having the same composition as the styrene resin (a). (Polymer) is most preferable because it is excellent in transparency, easily available, and inexpensive.
The transparent impact-resistant styrenic resin (b3) used for the oil-resistant resin layer (B) is not particularly limited as long as it is transparent, but a block copolymer comprising a styrenic monomer and a conjugated diene monomer. Polymers are preferred. As the styrene monomer, one having the same composition as the styrene resin (b2) is preferable, and styrene is particularly preferable. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-hexadiene, and 1,3-butadiene is preferred. The structure of these block copolymers may be any structure such as AB or ABA. At this time, the portion derived from the conjugated diene monomer is preferably 5 to 40% by weight, and more preferably 10 to 30% by weight. If it is more than 40% by weight, the transparency of the sheet is lowered and the cost is increased, which is not preferable. Further, when the styrene-diene block copolymer is hydrogenated, the transparency of the sheet is lost, which is not preferable.
[0020]
The mixing ratio of the polyphenylene ether resin (b1), the styrene resin (b2), and the transparent impact resistant styrene resin (b3) that forms the oil resistant resin layer (B) of the sheet of the present invention is a polyphenylene ether resin. (B1) 10 to 40% by weight, styrene resin (b2) 90 to 60% by weight, and 3 to 40 parts by weight of the impact-resistant styrene resin (b3) transparent to 100 parts by weight of these mixed resins .
[0021]
When the polyphenylene ether resin (b1) is less than 10% by weight and the styrene resin (b2) is more than 90% by weight, the resulting styrene resin biaxially stretched laminated sheet exhibits sufficient oil resistance and plasticizer resistance. I can't let you. On the other hand, when the polyphenylene ether resin is more than 40% by weight and the styrene resin (b2) is less than 60% by weight, the transparency of the sheet is lowered, the cost is increased, and the oil-resistant resin layer (B). And the melt viscosity difference between the base material layer (A) becomes large, the sheet formability during coextrusion and the moldability during secondary processing become difficult, and the productivity becomes poor. More preferably, the proportion of (b1) is 15 to 25% by weight and that of (b2) is 85 to 75% by weight. These are reasonably determined according to the purpose of the oil resistance, plasticizer resistance, low cost, etc. of the product.
[0022]
The mixing ratio of the transparent impact-resistant styrenic resin (b3) is preferably 5 to 40 parts by weight, particularly 5 to 20 parts by weight with respect to 100 parts by weight of the mixed resin (b1) and (b2). By mixing (b3) within this range, the compatibility between the polyphenylene ether resin (b1) and the styrene resin (b2) can be improved. As a result, the polyphenylene ether gelled on the surface of the sheet A sheet having an excellent appearance can be obtained without the appearance of defects derived from the resin. Moreover, sufficient folding strength which is a requirement for the sheet according to the present invention is obtained. Furthermore, oil resistance is further improved by using a transparent impact-resistant styrene resin and polyphenylene ether resin in combination.
[0023]
When the mixing ratio of (b3) is less than 5 parts by weight, the compatibility between the polyphenylene ether resin (b1) and the styrene resin (b2) cannot be improved, and sufficient bending strength cannot be expected. Accordingly, when a molded product such as a lid or a container is formed, the stress strain applied to the oil-resistant resin layer (B) increases, and cracks due to insufficient mechanical strength, cracks due to synthetic edible oils, and whitening occur. On the other hand, when the amount is more than 40 parts by weight, the transparency is remarkably lowered and the cost is considerably increased.
[0024]
The mixing method of (b1), (b2), and (b3) is not particularly limited, and may be mixing by general melt kneading or mixing by copolymerization. In the case of melt-kneading, the polyphenylene ether resin (b1) and the styrene resin (b2) are previously melt-kneaded and pelletized, and dry blended with the transparent impact-resistant styrene resin (b3) pellets during sheet molding, A method in which the three are simultaneously melt-kneaded and pelletized is preferred. In the case of copolymerization, the polyphenylene ether-based resin (b1) is dissolved in an amount of monomer corresponding to the amount of the styrene-based resin (b2), polymerized, pelletized, and transparent impact-resistant styrene-based during sheet molding Dry blend with the resin (b3) pellets, or dissolve the polyphenylene ether resin (b1) and the transparent styrene-butadiene block copolymer in the monomer corresponding to the styrene resin (b2). A method of pelletizing after polymerization is preferred.
[0025]
The polyphenylene ether-based resin is dissolved in the styrene-based monomer by using an appropriate dissolution tank and continuing stirring at a temperature of 60 to 100 ° C., preferably 70 to 90 ° C. for 1 to 2 hours. When the melting temperature is less than 60 ° C., the polyphenylene ether-based resin is not sufficiently dissolved and becomes a slurry, and when it exceeds 100 ° C., thermal polymerization of styrene is promoted.
[0026]
The polymerization may be carried out by any of suspension polymerization, solution polymerization, and bulk polymerization. Examples of the radical polymerization initiator include t-butyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, 1,1-bis (t-butyl peroxide) cyclohexane, 1,1-bis. Organic peroxides such as (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propanone, azobisisobutyronitrile, azobis Azo compounds such as -2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobiscyanovaleric acid, 1-t-butylazo-1-cyanocyclohexane, 1,1'-azobis-1-carbonitrile Can be mentioned. The polymerization initiator can be used in an appropriate amount to polymerize the styrene monomer, but is preferably 0.1 to 10% by weight with respect to 100 parts by weight of the styrene monomer.
[0027]
The thickness of the oil resistant resin layer (B) is preferably 10 to 100 μm. When the thickness of the oil-resistant resin layer (B) is less than 10 μm, even if the ratio of the polyphenylene ether-based resin (b1) in the oil-resistant resin layer (B) is increased, oil such as MCT attached to the surface of the molded product It penetrates to the base material layer (A), and crazes and cracks occur in the molded product. This is particularly noticeable if the molded product is scratched. On the other hand, when it exceeds 100 μm, the secondary processability of the sheet is deteriorated and the transparency is also inferior, so that it is not suitable for use as a food container.
[0028]
The actual thickness of the oil-resistant resin layer (B) is appropriately selected according to the use of the container to be molded, required oil resistance, plasticizer resistance, and cost in relation to the layer thickness. Is 200 to 300 μm, the oil-resistant resin layer (B) is usually 15 to 90 μm, particularly preferably 20 to 60 μm.
The laminated sheet of the present invention has an orientation relaxation stress measured in accordance with ASTM D-1504 of 3 to 8 kg / cm in both the sheet flow direction and the direction perpendicular thereto. 2 The film is stretched so as to have both strength and formability. Orientation relaxation stress is 3kg / cm 2 If it is less than the range, a molded product having practical strength cannot be obtained, and 8 kg / cm. 2 Beyond, only molded products with poor mold determination can be obtained.
[0029]
The laminated sheet of the present invention has a folding strength (average length and width average value) of 200 times or more measured according to ASTM D-2176, except that the bending angle is changed to 90 ° to the left and right. is necessary. If the folding strength is less than 200 times, it is not suitable for use as a food container.
The laminated sheet of the present invention needs to have oil resistance exceeding 24 hours. Having oil resistance exceeding 24 hours means that no craze or crack is generated on the sheet surface within 24 hours in the oil resistance evaluation method described later. When the oil resistance is within 24 hours, it is not preferable as a food container which is one of the uses of the sheet of the present invention.
[0030]
In the laminated sheet of the present invention, the styrene resin (b2) constituting the styrene resin (a) and the oil resistant resin layer (B) used for the base material layer (A) is preferably general-purpose polystyrene, and ASTM D- The transparency of the laminated sheet measured according to 1003 is preferably 70% or more. More preferably, the transparency is 80% or more. When the transparency is less than 70%, it looks bad when used as a food container.
[0031]
The layer structure of the styrene resin biaxially stretched laminated sheet of the present invention is not limited as long as the food storage side of the container is an oil-resistant resin layer (B) when subjected to container molding, In view of the balance with moldability, the two-layer structure and the three-layer structure are particularly preferable. Specifically, a two-layer structure of oil-resistant resin layer (B) / base material layer (A) or three layers of oil-resistant resin layer (B) / base material layer (A) / oil-resistant resin layer (B) Structure is mentioned. By using in this way, the two-layer structure exhibits oil resistance and plasticizer resistance on the inner surface and flange portion of the container, and the three-layer structure exhibits oil resistance on the inner surface and flange portion of the container. In addition to the plasticizer resistance, the outer wall and bottom of the container also exhibit good oil resistance and plasticizer resistance.
[0032]
In addition, if necessary, an additional layer made of an adhesive layer, a recovered resin layer at 100% or a free mixing ratio, and other resins may be added as long as the characteristics of the present invention are not impaired.
The styrene resin biaxially stretched laminated sheet of the present invention is prepared by preparing a styrene resin (a) for the base material layer (A) and a resin composition (b) for the oil resistant resin layer (B), respectively. It can be easily produced according to a more known method for producing a laminated biaxially stretched sheet.
[0033]
Specifically, (a) using two extruders, the styrene-based resin (a) and the resin composition (b) are melt-extruded from each of the two extruders, and the two layers are formed by a multilayer T die having a two-layer or three-layer structure. A method of obtaining an unstretched laminated sheet having a structure or a three-layer structure and then stretching in a biaxial direction by a conventionally known method,
(B) Using two extruders, the styrene-based resin (a) and the resin composition (b) are melt-extruded from each, and the base layer (A) is used with two or three single-layer T dies. The two-layer structure or the three-layer structure is obtained by separately obtaining one molten sheet and one or two molten sheets for the oil-resistant resin layer (B), and pressing and laminating them while they are still in a molten state. A non-stretched laminated sheet, and then stretched biaxially by a conventionally known method,
(C) Two types of biaxially stretched sheets composed of a styrene resin (a) for the base layer (A) and a biaxially stretched sheet composed of the resin composition (b) for the oil resistant resin layer (B). Examples thereof include a method of separately producing biaxially stretched sheets and bonding these biaxially stretched sheets using an adhesive.
[0034]
【Example】
EXAMPLES Next, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to description of these Examples, unless the summary is exceeded. In the following description, “parts” means weight basis unless otherwise specified.
About the biaxially stretched sheet obtained by each Example and the comparative example, it evaluated by the following method.
(1) Orientation relaxation stress
The orientation relaxation stress of the obtained biaxially stretched sheet was measured in the flow direction of the sheet and in a direction perpendicular thereto according to ASTM D-1504.
(2) Folding strength
The folding strength of the obtained biaxially stretched sheet was measured in the sheet flow direction and in a direction perpendicular to this according to ASTM D-2176, except that the bending angle was changed to 90 ° on the left and right, and the average value was obtained. .
(3) Oil resistance
From the obtained biaxially stretched sheet, a lid-shaped molded product (length 226 mm, width 147 mm, height 12 mm) was obtained by pressure forming (Kansai automatic molding machine PK-450 type). At this time, in the case of a two-type two-layer sheet, the oil-resistant resin layer (B) was set to the inside of the container. On the other hand, after uniformly applying oil (Kao Co., Ltd., trade name: Coconard MT, main component: medium chain fatty acid triglyceride stock solution) to a commercially available rice ball type, stuffed with freshly cooked rice, This was packed in a container (length: 223 mm, width: 144 mm, depth: 30 mm) molded from general-purpose polypropylene, and the molded lid was put on and fastened with a rubber band (total weight 360 g). Make a plurality of these and stack them in 3 stages (from the bottom to the 1st, 2nd, and 3rd), and put the dummy with only the weight on the top, and let it stand in a room at 23 ° C. Whether or not crazing or cracking occurred was checked for each stage of the molded lid. The evaluation criteria were as follows.
[0035]
××:
Crazes and cracks occur within 2 hours
×: Craze or crack occurred within 6 hours
Δ: Craze or crack occurred within 24 hours
○: Although no crazes or cracks occurred within 24 hours,
Occurs within 48 hours
◎: No crazing or cracking occurred after 48 hours
(4) Plasticizer resistance
The same molding lid as that described above for (3) oil resistance evaluation was molded. However, in the case of a two-type two-layer sheet, the oil-resistant resin layer (B) was arranged outside the container. Next, (3) freshly cooked rice was packed in the same general-purpose polypropylene container used for the oil resistance evaluation, and a molding lid was placed (total weight 360 g). Next, this is applied to a stretch automatic packaging machine (Fujipack System Co., Ltd., A-12 type), and a commercially available polyvinyl chloride stretch film (Mitsubishi Resin Co., Ltd., trade name: Diawrap) is used. Wrapped. Make a plurality of these and stack them in 3 stages (from the bottom to the 1st, 2nd, and 3rd), and put the dummy with only the weight on the top, and let it stand in a room at 23 ° C. Every time, the presence or absence of crazes and cracks was checked on the flanges and corners of the molded lid at each stage. The evaluation criteria were as follows.
[0036]
×: Craze or crack occurred within 6 hours
Δ: Craze or crack occurred within 24 hours
○: Craze or crack occurred within 48 hours
◎: No crazing or cracking occurred after 48 hours
(5) Transparency
Transparency (%) of the obtained biaxially stretched sheet was measured according to ASTM D-1003 and represented by the following evaluation criteria.
[0037]
X: Less than 70%
Δ: 70% or more and less than 80%
○: 80% or more and less than 90%
◎: 90% or more
The resins and monomers used are as follows.
Styrenic resin (a) (b1): manufactured by Mitsubishi Chemical Corporation, trade name “Dialex HH-102” (hereinafter referred to as GPPS)
Polyphenylene ether resin (b2): Mitsubishi Gas Chemical Co., Ltd., trade name “YPX-100L”, main component: poly (2,6-dimethyl-1,4-phenylene) ether (hereinafter referred to as PPE)
Transparent impact-resistant styrene resin (b3): manufactured by Asahi Kasei Co., Ltd., trade name “Asaflex 815” (rubber component content about 25%) (hereinafter referred to as SBBC)
・ Styrene monomer (hereinafter referred to as SM)
In the following Examples and Comparative Examples, adjustment / change of the sheet layer composition ratio or adjustment / change of the entire sheet thickness was performed by controlling the extrusion amount of each extruder and the line speed.
Example 1
GPPS was used as the styrenic resin (a) for the base layer (A). On the other hand, by adding 80 parts of GPPS to 20 parts of PPE and melt-mixing at 310 ° C. using a co-rotating twin screw extruder (manufactured by Toshiba Machine Co., Ltd.), an intermediate resin composition comprising two components is obtained. It was pelletized and adjusted. What dry-blended 5 parts of SBBC pellets with respect to 100 parts of this intermediate resin composition was used as the resin composition (b) for the oil-resistant resin layer (B).
[0038]
Next, two vent type extruders (Pura Giken Co., Ltd. and Ikekai Tekko Co., Ltd.) were used. The styrene resin (a) is supplied to one extruder, the resin composition (b) is supplied to the other extruder, and co-extruded to give an unstretched thickness of about 1.4 mm. A two-layer sheet was obtained. Subsequently, the unstretched two-layer sheet is stretched about 2.6 times in the longitudinal direction and about 2.5 times in the transverse direction by a roll type longitudinal stretching machine and then a tenter transverse stretching machine, whereby the base layer (A) A biaxially stretched sheet having a thickness of 192 μm, an oil-resistant resin layer (B) of 18 μm, and a total thickness of 210 μm was obtained.
[0039]
The evaluation results of the obtained sheet are shown in Table 1.
Example 2
An oil-resistant resin layer comprising 70 parts of the same styrenic resin (a) as in Example 1 plus 30 parts of a pulverized biaxially stretched sheet obtained in Example 1 is used as the base material layer (A). The resin composition (B) for (B) is exactly the same as in Example 1, and is co-extruded and co-stretched in the same manner as in Example 1, whereby the base layer (A) has a thickness of 172 μm and oil resistance. A biaxially stretched sheet having a resin layer (B) thickness of 40 μm and a total thickness of 212 μm was obtained.
[0040]
The evaluation results of the obtained sheet are shown in Table 1.
Example 3
GPPS was used as the styrenic resin (a) for the base layer (A). On the other hand, by adding 90 parts of GPPS to 10 parts of PPE and melt-mixing at 310 ° C. using a co-rotating twin screw extruder (manufactured by Toshiba Machine Co., Ltd.), an intermediate resin composition comprising two components is obtained. It was pelletized and adjusted. What dry-blended 10 parts of SBBC pellets with respect to 100 parts of this intermediate resin composition was used as the resin composition (b) for the oil-resistant resin layer (B). Thereafter, by co-extrusion and co-stretching in the same manner as in Example 1, the base layer (A) has a thickness of 172 μm, the oil-resistant resin layer (B) has a thickness of 39 μm, and a total thickness of 211 μm. Got.
[0041]
The evaluation results of the obtained sheet are shown in Table 1.
Example 4
70 parts of the same GPPS as in Example 1 and 30 parts of a pulverized biaxially stretched sheet obtained in Example 3 were used for the base material layer (A), and 100 parts of the same intermediate resin composition as in Example 3 was used. On the other hand, by adding 30 parts of SBBC as a resin composition (b) for the oil-resistant resin layer (B), coextruding and co-stretching in the same manner as in Example 1, the thickness of the base material layer (A) is reduced. A biaxially stretched sheet having a thickness of 171 μm, an oil-resistant resin layer (B) of 40 μm, and a total thickness of 211 μm was obtained.
[0042]
The evaluation results of the obtained sheet are shown in Table 1.
Example 5
Except for changing the feed block from 2 types 2 layers to 2 types 3 layers, the same resin as in Example 1 was coextruded and co-extruded in the same manner, so that the thickness of the base layer (A) was 169 μm, A biaxially stretched sheet having an oil-resistant resin layer (B) thickness of 20 μm and a total thickness of 209 μm was obtained.
[0043]
The evaluation results of the obtained sheet are shown in Table 1.
Example 6
Resin composition for oil-resistant resin layer (B) using 70 parts of GPPS same as Example 1 plus 30 parts of pulverized biaxially stretched sheet obtained in Example 5 as the base layer (A) (B) is exactly the same as in Example 5, and is co-extruded and co-stretched in the same manner as in Example 5, so that the thickness of the base material layer (A) is 120 μm and the oil-resistant resin layers (B) on both sides are A biaxially stretched sheet having a thickness of 18 μm and a total thickness of 156 μm was obtained.
[0044]
The evaluation results of the obtained biaxially stretched sheet are shown in Table 1.
Example 7
70 parts of the same GPPS as in Example 1 and 30 parts of the pulverized biaxially stretched sheet obtained in Example 5 were used for the base material layer (A), and 100 parts of the same intermediate resin composition as in Example 1 was used. On the other hand, by adding 20 parts of SBBC as a resin composition (b) for the oil-resistant resin layer (B), co-extrusion in the same manner as in Example 5 and co-stretching, the base layer (A) A biaxially stretched sheet having a thickness of 170 μm, the oil-resistant resin layers (B) on both sides of 20 μm, and a total thickness of 210 μm was obtained.
[0045]
The evaluation results of the obtained sheet are shown in Table 1.
Example 8
The same intermediate resin composition as in Example 1 (70) of the same GPPS as in Example 1 plus 30 parts of the pulverized biaxially stretched sheet obtained in Example 5 was used as the base material layer (A). b ′) By adding 40 parts of SBBC to 100 parts as a resin composition (b) for the oil-resistant resin layer (B), coextruding and coextending in the same manner as in Example 5, A biaxially stretched sheet having a material layer (A) thickness of 176 μm, oil-resistant resin layers (B) on both sides of 16 μm and a total thickness of 208 μm was obtained.
[0046]
The evaluation results of the obtained sheet are shown in Table 1.
Example 9
70 parts of the same GPPS as in Example 1 and 30 parts of the pulverized biaxially stretched sheet obtained in Example 6 were used for the base material layer (A), and 100 parts of the same intermediate resin composition as in Example 3 was used. On the other hand, by adding 20 parts of SBBC as a resin composition (b) for the oil-resistant resin layer (B), co-extrusion in the same manner as in Example 5 and co-stretching, the base layer (A) A biaxially stretched sheet having a thickness of 369 μm, a thickness of the oil-resistant resin layers (B) on both sides of 39 μm, and a total thickness of 447 μm was obtained.
[0047]
The evaluation results of the obtained sheet are shown in Table 1.
Example 10
GPPS was used as the styrenic resin (a) for the base layer (A). By adding 60 parts of GPPS to 40 parts by weight of PPE and melt-mixing at 320 ° C. using a co-rotating twin screw extruder (manufactured by Toshiba Machine Co., Ltd.), the intermediate resin composition composed of two components is pelleted. Adjusted. Except for adding 100 parts of SBBC to 100 parts of this intermediate resin composition and making it a resin composition (b) for the oil-resistant resin layer (B), the same resin as in Example 5 was coextruded in the same manner, By co-stretching, a biaxially stretched sheet having a base layer (A) thickness of 180 μm, oil-resistant resin layers (B) on both sides of 15 μm and a total thickness of 210 μm was obtained.
[0048]
The evaluation results of the obtained sheet are shown in Table 1.
Example 11
Intermediate resin composition for oil-resistant resin layer (B) using 70 parts of GPPS as in Example 1 plus 30 parts of pulverized biaxially stretched sheet obtained in Example 6 as the base layer (A) The following polymerized product was used as the product.
[0049]
That is, 5.0 kg of PPE and 15.0 kg of SM were placed in a 50 L dissolving layer equipped with an agitator type stirring blade, and the temperature was raised to 80 ° C., and stirring was continued for 60 minutes to sufficiently dissolve PPE in SM. Thereafter, 20 kg of hot deionized water, 1.0 kg of sodium dodecylbenzenesulfonate, 450 g of a 2% aqueous solution of a polyacrylate suspension and 100 g of sodium sulfate were added, and the temperature was raised to 120 ° C. After reaching 120 ° C., 30 g of dicumyl peroxide was added, the temperature was raised to 150 ° C. over 5 hours, and the reaction was further continued for 1 hour. The obtained beads were dried and then melted and kneaded in one pass at a setting of 260 ° C. using a single screw extruder (manufactured by Plastic Giken Co., Ltd.) to obtain pellets.
[0050]
What dry-blended 5 parts of SBBC pellets with respect to 100 parts of this intermediate resin composition was used as the resin composition (b) for the oil-resistant resin layer (B). By co-extrusion and co-stretching in the same manner as in Example 5, the thickness of the base layer (A) is 175 μm, the thickness of the oil-resistant resin layers (B) on both sides is 18 μm, and the total thickness is 211 μm. Got.
[0051]
The evaluation results of the obtained sheet are shown in Table 1.
Comparative Example 1
Using a single vent-type extruder (Ikegai Iron Works Co., Ltd.), a single layer feed block and a coat hanger type T-die (both made by Pla Giken Co., Ltd.) were attached, and styrene resin ( GPPS was used as a). Thereafter, a single-layer biaxially stretched sheet having a total thickness of 210 μm was obtained by stretching in the same manner as in Example 1.
[0052]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 2
The same resin as in Example 1, except that the same intermediate resin composition as in Example 3 was used as the resin composition (b) for the oil-resistant resin layer (B), was coextruded by the same method and co-extended, A biaxially stretched sheet having a thickness of 192 μm, a thickness of the oil-resistant resin layer (B) of 18 μm, and a total thickness of 210 μm was obtained.
[0053]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 3
Exactly the same resin as in Example 1, except that 20 parts of SBBC was added to 100 parts of the same intermediate resin composition as in Example 3 to obtain a resin composition (b) for the oil-resistant resin layer (B). By co-extrusion and co-stretching by the method, a biaxially stretched sheet having a base layer (A) thickness of 205 μm, an oil-resistant resin layer (B) thickness of 5 μm and a total thickness of 210 μm was obtained.
[0054]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 4
GPPS was used as the styrenic resin (a) for the base layer (A). On the other hand, by adding 50 parts of GPPS to 50 parts of PPE and melt-mixing at 320 ° C. using a co-rotating twin screw extruder (manufactured by Toshiba Machine Co., Ltd.), an intermediate resin composition comprising two components is obtained. It was pelletized and adjusted. This intermediate resin composition was used as it is as the resin composition (b) for the oil-resistant resin layer (B). Thereafter, by co-extrusion and co-stretching in the same manner as in Example 1, the base layer (A) has a thickness of 193 μm, the oil-resistant resin layer (B) has a thickness of 16 μm, and a total thickness of 209 μm. Got.
[0055]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 5
GPPS was used as the resin composition for the base material layer (A). As the resin composition (b) for the oil-resistant resin layer (B), one obtained by dry blending 20 parts of SBBC pellets with 100 parts of GPPS was used. Thereafter, by co-extrusion and co-stretching in the same manner as in Example 5, the base layer (A) has a thickness of 169 μm, the oil-resistant resin layers (B) on both sides have a thickness of 20 μm, and the total thickness is 209 μm. A stretched sheet was obtained.
[0056]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 6
The same resin as in Example 5 except that the same intermediate resin composition as in Example 1 was used as the resin composition (b) for the oil-resistant resin layer (B). A biaxially stretched sheet having a thickness of the material layer (A) of 180 μm, a thickness of the oil-resistant resin layers (B) on both sides of 16 μm, and a total thickness of 212 μm was obtained.
[0057]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 7
70 parts of the same GPPS as in Example 1 and 30 parts of the pulverized biaxially stretched sheet obtained in Example 5 were used for the base material layer (A), and 100 parts of the same intermediate resin composition as in Example 1 was used. On the other hand, by adding 30 parts of SBBC as a resin composition (b) for the oil-resistant resin layer (B), co-extrusion and co-stretching in the same manner as in Example 5, the base layer (A) A biaxially stretched sheet having a thickness of 200 μm, an oil-resistant resin layer (B) on both sides of 5 μm, and a total thickness of 210 μm was obtained.
[0058]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 8
The same resin and the same method as in Example 5 except that 50 parts of SBBC was added to 100 parts of the same intermediate resin composition as in Example 1 to obtain a resin composition (b) for the oil-resistant resin layer (B). Was coextruded and co-stretched to obtain a biaxially stretched sheet having a base layer (A) thickness of 119 μm, oil-resistant resin layers (B) on both sides of 18 μm in thickness, and a total thickness of 155 μm.
[0059]
Table 2 shows the evaluation results of the obtained sheet.
Comparative Example 9
70 parts of the same GPPS as in Example 1 and 30 parts of the pulverized biaxially stretched sheet obtained in Comparative Example 6 were used for the base material layer (A), and the same intermediate resin composition as in Example 11 was used as it was for oil resistance. The base layer (A) has a thickness of 171 μm and oil-resistant resins on both sides by co-extrusion and co-stretching in the same manner as in Example 5 except that the resin composition (b) for the conductive resin layer (B) is used. A biaxially stretched sheet having a layer (B) thickness of 20 μm and a total thickness of 211 μm was obtained.
[0060]
Table 2 shows the evaluation results of the obtained sheet.
On the other hand, it is known that even if general-purpose polystyrene is used instead of impact-resistant polystyrene, it is mixed with polyphenylene ether resin with an arbitrary composition to form a completely compatible system. Due to the softening point and low fluidity, complete dissolution is difficult except in special cases. Depending on the kneading and extrusion conditions, unfused polyphenylene ether resins or gelled polyphenylene ether resins may be found in the mixed resin composition. For example, in the case of a colored injection-molded product, these foreign substances will sneak inside and become inconspicuous, but in the case of a biaxially stretched sheet for forming a food container, the sheet is easily noticeable due to its transparency. It must be excluded as much as possible from the viewpoint of food containers.
[0061]
[Table 1]
[Table 2]
【The invention's effect】
The styrene resin laminated biaxially stretched sheet of the present invention comprises a composition of a polyphenylene ether resin, a styrene resin and a transparent impact resistant styrene resin mixed with a specific blending ratio of an oil resistant resin layer. Since the sheet has specific physical property values, it has excellent oil resistance, plasticizer resistance, folding resistance, transparency, rigidity, and moldability, and the sheet itself can be recycled. There is a strong strength. Therefore, it can be widely used for a food packaging sheet that is inexpensive and excellent in properties. It is particularly suitable for food packaging in which food oil is used.
Claims (2)
耐油性評価方法：二軸延伸シートより、圧空成形（関西自動成形機ＰＫ−４５０型）により、耐油性樹脂層（Ｂ）が容器の内側となるようにして蓋状成形品（長さ２２６ｍｍ、幅１４７ｍｍ、高さ１２ｍｍ）を成形する。一方、市販のおにぎり型に油分（花王（株）製、商品名ココナードＭＴ、主成分：中鎖脂肪酸トリグリセリド、の原液）を一様に塗布し、炊きたてのご飯を詰めておにぎりを作成した後、これをポリプロピレンより成形した容器（長さ２２３ｍｍ、幅１４４ｍｍ、深さ３０ｍｍ）に詰め、上記成形蓋を乗せて輪ゴムで止める（総重量３６０ｇ）。これを複数個作り、３段に積み重ね、最上段には重量のみ合わせたダミーを乗せ、２３℃の室内に放置し、所定時間ごとに各段の成形蓋についてクレイズやクラックの発生の有無をチェックする。In the styrene-based resin laminated biaxially stretched sheet in which the styrene-based resin (a) is a base layer (A) and the oil-resistant resin layer (B) is formed on at least one surface of the base layer (A), The base material layer (A) has a thickness of 80 to 500 μm, and the oil-resistant resin layer (B) is composed of 10 to 40% by weight of the polyphenylene ether resin (b1) and 90 to 60% by weight of the styrene resin (b2). A transparent composition comprising a block copolymer having a styrene-based monomer and a conjugated diene monomer, and a portion derived from the conjugated diene monomer being 5 to 40% by weight with respect to 100 parts by weight of the resulting resin composition. It is composed of a resin composition in which 5 to 40 parts by weight of impact-resistant styrene resin (b3) is blended, its thickness is 10 to 100 μm, and the orientation relaxation stress of the laminated sheet is both in the flow direction and in the direction perpendicular thereto. 3-8kg Biaxially stretched so as to be / cm 2 , the folding strength is 200 times or more, and the oil resistance evaluation by the following evaluation method has oil resistance exceeding 24 hours in the occurrence of crazes and cracks. An oil-resistant styrene-based resin laminated biaxially stretched sheet.
Oil resistance evaluation method: From a biaxially stretched sheet, a lid-shaped molded product (length: 226 mm, length 226 mm, by pressure forming (Kansai automatic molding machine PK-450 type) so that the oil-resistant resin layer (B) is inside the container . 147 mm in width and 12 mm in height) . On the other hand, commercially available rice ball type in oil (commercially available from Kao Corporation under the trade name Coconad MT, the main component: medium-chain fatty acid triglyceride, of stock solution) is uniformly coated with, after you create a rice balls stuffed with rice freshly cooked, This is packed in a container (length: 223 mm, width: 144 mm, depth: 30 mm) molded from polypropylene, and the molded lid is put on and fastened with a rubber band (total weight 360 g). Make a number of them, stack them in three stages, put a dummy with only the weight on the top stage, leave it in a room at 23 ° C, and check for the occurrence of crazes and cracks in the molding lid at each stage every predetermined time To do.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31542095A JP3909881B2 (en) | 1995-12-04 | 1995-12-04 | Styrene resin laminated biaxially oriented sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31542095A JP3909881B2 (en) | 1995-12-04 | 1995-12-04 | Styrene resin laminated biaxially oriented sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09156048A JPH09156048A (en) | 1997-06-17 |
| JP3909881B2 true JP3909881B2 (en) | 2007-04-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP31542095A Expired - Lifetime JP3909881B2 (en) | 1995-12-04 | 1995-12-04 | Styrene resin laminated biaxially oriented sheet |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6436529B1 (en) * | 1997-01-21 | 2002-08-20 | 3M Innovative Properties Company | Elatomeric laminates and composites |
| AU8399798A (en) * | 1997-07-23 | 1999-02-16 | Nyman Mfg. Co. | Multilayer, microwaveable container |
| JP5619392B2 (en) * | 2009-08-20 | 2014-11-05 | 株式会社日本触媒 | Front plate for image display device and manufacturing method thereof |
| JP5942081B2 (en) * | 2011-06-07 | 2016-06-29 | 旭化成株式会社 | Formed body by vacuum forming or blow molding |
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1995
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