JP6306871B2 - Polystyrene resin sheet suitable for microwave heating applications and molded containers thereof - Google Patents
Polystyrene resin sheet suitable for microwave heating applications and molded containers thereof Download PDFInfo
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- JP6306871B2 JP6306871B2 JP2013258644A JP2013258644A JP6306871B2 JP 6306871 B2 JP6306871 B2 JP 6306871B2 JP 2013258644 A JP2013258644 A JP 2013258644A JP 2013258644 A JP2013258644 A JP 2013258644A JP 6306871 B2 JP6306871 B2 JP 6306871B2
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- resin sheet
- polystyrene resin
- oil
- sheet
- polyvinyl alcohol
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- 229920005990 polystyrene resin Polymers 0.000 title claims description 95
- 238000010438 heat treatment Methods 0.000 title description 8
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 46
- 238000000576 coating method Methods 0.000 claims description 46
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 46
- 239000011248 coating agent Substances 0.000 claims description 45
- 229920005989 resin Polymers 0.000 claims description 30
- 239000011347 resin Substances 0.000 claims description 30
- 239000004793 Polystyrene Substances 0.000 claims description 24
- 229920002223 polystyrene Polymers 0.000 claims description 24
- 238000006116 polymerization reaction Methods 0.000 claims description 19
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 16
- 238000007127 saponification reaction Methods 0.000 claims description 14
- 238000000465 moulding Methods 0.000 claims description 12
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 11
- 239000001632 sodium acetate Substances 0.000 claims description 11
- 235000017281 sodium acetate Nutrition 0.000 claims description 11
- 239000007864 aqueous solution Substances 0.000 claims description 7
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims description 5
- 239000003921 oil Substances 0.000 description 76
- 230000000052 comparative effect Effects 0.000 description 19
- 238000000034 method Methods 0.000 description 18
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 15
- 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 13
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 13
- 229920003145 methacrylic acid copolymer Polymers 0.000 description 13
- 229940117841 methacrylic acid copolymer Drugs 0.000 description 13
- 238000011156 evaluation Methods 0.000 description 11
- 235000013305 food Nutrition 0.000 description 11
- 239000000178 monomer Substances 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 235000014113 dietary fatty acids Nutrition 0.000 description 8
- 239000000194 fatty acid Substances 0.000 description 8
- 229930195729 fatty acid Natural products 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- -1 sucrose fatty acid ester Chemical class 0.000 description 8
- 238000004806 packaging method and process Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 125000004432 carbon atom Chemical group C* 0.000 description 6
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000000839 emulsion Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- UKMSUNONTOPOIO-UHFFFAOYSA-N docosanoic acid Chemical compound CCCCCCCCCCCCCCCCCCCCCC(O)=O UKMSUNONTOPOIO-UHFFFAOYSA-N 0.000 description 4
- POULHZVOKOAJMA-UHFFFAOYSA-N dodecanoic acid Chemical compound CCCCCCCCCCCC(O)=O POULHZVOKOAJMA-UHFFFAOYSA-N 0.000 description 4
- ZQPPMHVWECSIRJ-MDZDMXLPSA-N elaidic acid Chemical compound CCCCCCCC\C=C\CCCCCCCC(O)=O ZQPPMHVWECSIRJ-MDZDMXLPSA-N 0.000 description 4
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 description 4
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 4
- UTOPWMOLSKOLTQ-UHFFFAOYSA-N octacosanoic acid Chemical compound CCCCCCCCCCCCCCCCCCCCCCCCCCCC(O)=O UTOPWMOLSKOLTQ-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 239000004094 surface-active agent Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 238000007334 copolymerization reaction Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 150000002148 esters Chemical class 0.000 description 3
- 150000004665 fatty acids Chemical class 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000004667 medium chain fatty acids Chemical class 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 229920002857 polybutadiene Polymers 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 229920003169 water-soluble polymer Polymers 0.000 description 3
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 description 2
- QXJSBBXBKPUZAA-CMDGGOBGSA-N (e)-octadec-10-enoic acid Chemical compound CCCCCCC\C=C\CCCCCCCCC(O)=O QXJSBBXBKPUZAA-CMDGGOBGSA-N 0.000 description 2
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 description 2
- PYSRRFNXTXNWCD-UHFFFAOYSA-N 3-(2-phenylethenyl)furan-2,5-dione Chemical compound O=C1OC(=O)C(C=CC=2C=CC=CC=2)=C1 PYSRRFNXTXNWCD-UHFFFAOYSA-N 0.000 description 2
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 2
- 235000021357 Behenic acid Nutrition 0.000 description 2
- DPUOLQHDNGRHBS-UHFFFAOYSA-N Brassidinsaeure Natural products CCCCCCCCC=CCCCCCCCCCCCC(O)=O DPUOLQHDNGRHBS-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- URXZXNYJPAJJOQ-UHFFFAOYSA-N Erucic acid Natural products CCCCCCC=CCCCCCCCCCCCC(O)=O URXZXNYJPAJJOQ-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000005639 Lauric acid Substances 0.000 description 2
- OYHQOLUKZRVURQ-HZJYTTRNSA-N Linoleic acid Chemical compound CCCCC\C=C/C\C=C/CCCCCCCC(O)=O OYHQOLUKZRVURQ-HZJYTTRNSA-N 0.000 description 2
- 239000005642 Oleic acid Substances 0.000 description 2
- 235000021314 Palmitic acid Nutrition 0.000 description 2
- 239000005062 Polybutadiene Substances 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- 229920001214 Polysorbate 60 Polymers 0.000 description 2
- 235000021355 Stearic acid Nutrition 0.000 description 2
- 229920000147 Styrene maleic anhydride Polymers 0.000 description 2
- 229930006000 Sucrose Natural products 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- DTOSIQBPPRVQHS-PDBXOOCHSA-N alpha-linolenic acid Chemical compound CC\C=C/C\C=C/C\C=C/CCCCCCCC(O)=O DTOSIQBPPRVQHS-PDBXOOCHSA-N 0.000 description 2
- 235000020661 alpha-linolenic acid Nutrition 0.000 description 2
- 229940116226 behenic acid Drugs 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 238000003851 corona treatment Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- GHVNFZFCNZKVNT-UHFFFAOYSA-N decanoic acid Chemical compound CCCCCCCCCC(O)=O GHVNFZFCNZKVNT-UHFFFAOYSA-N 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- DPUOLQHDNGRHBS-KTKRTIGZSA-N erucic acid Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCC(O)=O DPUOLQHDNGRHBS-KTKRTIGZSA-N 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 229940033355 lauric acid Drugs 0.000 description 2
- OYHQOLUKZRVURQ-IXWMQOLASA-N linoleic acid Natural products CCCCC\C=C/C\C=C\CCCCCCCC(O)=O OYHQOLUKZRVURQ-IXWMQOLASA-N 0.000 description 2
- 235000020778 linoleic acid Nutrition 0.000 description 2
- KQQKGWQCNNTQJW-UHFFFAOYSA-N linolenic acid Natural products CC=CCCC=CCC=CCCCCCCCC(O)=O KQQKGWQCNNTQJW-UHFFFAOYSA-N 0.000 description 2
- 229960004488 linolenic acid Drugs 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 description 2
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 2
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 2
- WWZKQHOCKIZLMA-UHFFFAOYSA-N octanoic acid Chemical compound CCCCCCCC(O)=O WWZKQHOCKIZLMA-UHFFFAOYSA-N 0.000 description 2
- 229940098695 palmitic acid Drugs 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 229920001296 polysiloxane Polymers 0.000 description 2
- 230000001846 repelling effect Effects 0.000 description 2
- 239000005060 rubber Substances 0.000 description 2
- 150000004671 saturated fatty acids Chemical class 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000008117 stearic acid Substances 0.000 description 2
- 229960004274 stearic acid Drugs 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- 239000005720 sucrose Substances 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- TUNFSRHWOTWDNC-HKGQFRNVSA-N tetradecanoic acid Chemical compound CCCCCCCCCCCCC[14C](O)=O TUNFSRHWOTWDNC-HKGQFRNVSA-N 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 235000021122 unsaturated fatty acids Nutrition 0.000 description 2
- 150000004670 unsaturated fatty acids Chemical class 0.000 description 2
- BQTPKSBXMONSJI-UHFFFAOYSA-N 1-cyclohexylpyrrole-2,5-dione Chemical compound O=C1C=CC(=O)N1C1CCCCC1 BQTPKSBXMONSJI-UHFFFAOYSA-N 0.000 description 1
- HIDBROSJWZYGSZ-UHFFFAOYSA-N 1-phenylpyrrole-2,5-dione Chemical compound O=C1C=CC(=O)N1C1=CC=CC=C1 HIDBROSJWZYGSZ-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
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-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
- OFNISBHGPNMTMS-UHFFFAOYSA-N 3-methylideneoxolane-2,5-dione Chemical compound C=C1CC(=O)OC1=O OFNISBHGPNMTMS-UHFFFAOYSA-N 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000005632 Capric acid (CAS 334-48-5) Substances 0.000 description 1
- 239000005635 Caprylic acid (CAS 124-07-2) Substances 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 239000005063 High cis polybutadiene Substances 0.000 description 1
- 239000005064 Low cis polybutadiene Substances 0.000 description 1
- PEEHTFAAVSWFBL-UHFFFAOYSA-N Maleimide Chemical compound O=C1NC(=O)C=C1 PEEHTFAAVSWFBL-UHFFFAOYSA-N 0.000 description 1
- GHAZCVNUKKZTLG-UHFFFAOYSA-N N-ethyl-succinimide Natural products CCN1C(=O)CCC1=O GHAZCVNUKKZTLG-UHFFFAOYSA-N 0.000 description 1
- HDFGOPSGAURCEO-UHFFFAOYSA-N N-ethylmaleimide Chemical compound CCN1C(=O)C=CC1=O HDFGOPSGAURCEO-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 229920000800 acrylic rubber Polymers 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 150000001555 benzenes Chemical group 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000012662 bulk polymerization Methods 0.000 description 1
- FACXGONDLDSNOE-UHFFFAOYSA-N buta-1,3-diene;styrene Chemical compound C=CC=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 FACXGONDLDSNOE-UHFFFAOYSA-N 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 239000008157 edible vegetable oil Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- 238000007602 hot air drying Methods 0.000 description 1
- 229920001477 hydrophilic polymer Polymers 0.000 description 1
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 description 1
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 description 1
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 description 1
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 description 1
- 238000007603 infrared drying Methods 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 229910003475 inorganic filler Inorganic materials 0.000 description 1
- 239000004611 light stabiliser Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000006082 mold release agent Substances 0.000 description 1
- SEEYREPSKCQBBF-UHFFFAOYSA-N n-methylmaleimide Chemical compound CN1C(=O)C=CC1=O SEEYREPSKCQBBF-UHFFFAOYSA-N 0.000 description 1
- 229960002446 octanoic acid Drugs 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 230000002335 preservative effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 235000003441 saturated fatty acids Nutrition 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 229920000468 styrene butadiene styrene block copolymer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003856 thermoforming Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 238000005199 ultracentrifugation Methods 0.000 description 1
- 238000007666 vacuum forming Methods 0.000 description 1
- 230000002087 whitening effect Effects 0.000 description 1
Landscapes
- Containers Having Bodies Formed In One Piece (AREA)
- Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
- Laminated Bodies (AREA)
Description
本発明は、電子レンジで使用可能な耐油性ポリスチレン系樹脂シートおよびそれから成形してなる容器に関する。さらに詳しくは、熱板成形、真空成形などの方法での成形に適しており、防曇性に優れ、臭気の問題がなく、耐熱性、耐油性に優れているので、特に電子レンジで加熱する食品の包装容器の用途に好適に用いることができる、耐油性ポリスチレン系樹脂シートおよびそれから成形された容器に関する。 The present invention relates to an oil-resistant polystyrene-based resin sheet that can be used in a microwave oven and a container formed therefrom. More specifically, it is suitable for molding by hot plate molding, vacuum molding, and other methods, has excellent antifogging properties, no odor problems, and excellent heat resistance and oil resistance. The present invention relates to an oil-resistant polystyrene-based resin sheet that can be suitably used for food packaging containers and a container molded therefrom.
ポリスチレンの二軸延伸シートは、透明性、剛性に優れることから、主に軽量容器等の成形品に使用されている。しかしながら、これらの容器は耐熱性に劣ることから、電子レンジで加熱される食品包装容器の用途にはあまり使用されていない。また、電子レンジで加熱される食品は油を含むものが多く、この用途には耐熱性だけでなく耐油性も必要とされるが、ポリスチレンは一般的に油に対する耐性が低い。ポリスチレンの二軸延伸シートは、油と接した状態にあると、白化したり、場合によっては亀裂が生じたりする。高温になるほど油の影響を強く受けるため、特に電子レンジで加熱される食品の用途には、高い耐熱性と耐油性が必要となる。
ポリスチレンの耐熱性を高める方法として、スチレン−メタクリル酸共重合体やスチレン−無水マレイン酸共重合体等の耐熱性スチレン樹脂を使用した耐熱性ポリスチレン系樹脂シートが提案されている（特許文献１〜４）。しかし、特許文献１〜４に記載の延伸シートを熱成形して得た容器は、耐熱性以外の物性に劣る場合があった。例えばシート強度が低く割れやすかったり、十分な耐熱性が得られず加熱した際に容器が変形したりする問題があった。
一方、耐油性を高める方法としては、異素材を併用したり、親水性高分子や熱可塑性エマルジョンの塗膜を形成したりする方法が提案されている（特許文献５〜８）。しかし、特許文献５、６に記載の方法では、透明性が不十分なうえ、異素材が混入しているために原料のリサイクルが困難であるという問題があった。また、特許文献７、８に記載の方法では、塗膜を形成させるためにはポリスチレン系樹脂シートの表面にコロナ処理等の親水化処理を施す必要があった。
Polystyrene biaxially stretched sheets are excellent in transparency and rigidity, and are mainly used for molded articles such as lightweight containers. However, since these containers are inferior in heat resistance, they are not often used for food packaging containers heated in a microwave oven. In addition, many foods heated in a microwave oven contain oil, and this application requires not only heat resistance but also oil resistance. Polystyrene generally has low resistance to oil. When the polystyrene biaxially stretched sheet is in contact with oil, it is whitened or cracked in some cases. The higher the temperature, the stronger the influence of oil, so high heat resistance and oil resistance are required especially for food applications heated in a microwave oven.
As a method for increasing the heat resistance of polystyrene, a heat-resistant polystyrene-based resin sheet using a heat-resistant styrene resin such as a styrene-methacrylic acid copolymer or a styrene-maleic anhydride copolymer has been proposed (Patent Documents 1 to 3). 4). However, containers obtained by thermoforming stretched sheets described in Patent Documents 1 to 4 may be inferior in physical properties other than heat resistance. For example, there is a problem that the sheet strength is low and it is easy to break, or sufficient heat resistance cannot be obtained and the container is deformed when heated.
On the other hand, as a method of improving oil resistance, methods of using different materials together or forming a coating film of a hydrophilic polymer or a thermoplastic emulsion have been proposed (Patent Documents 5 to 8). However, the methods described in Patent Documents 5 and 6 have problems that transparency is insufficient and that it is difficult to recycle raw materials because foreign materials are mixed. In addition, in the methods described in Patent Documents 7 and 8, it is necessary to perform hydrophilic treatment such as corona treatment on the surface of the polystyrene resin sheet in order to form a coating film.
本発明は、ポリスチレン系樹脂シートに成形性やシート強度を損なうことなく耐熱性と耐油性を付与することを目的になされたものである。さらに詳しくは、電子レンジで加熱する食品の包装容器として好適なポリスチレン系樹脂シートならびにそれから形成される包装容器を提供することを目的になされたものである。 The present invention has been made for the purpose of imparting heat resistance and oil resistance to a polystyrene resin sheet without impairing moldability and sheet strength. More specifically, it is an object of the present invention to provide a polystyrene resin sheet suitable as a packaging container for foods heated by a microwave oven and a packaging container formed therefrom.
本発明者は、上記の課題を解決すべく耐熱性と強度が得られるポリスチレン系樹脂の組成ならびに分子量そして加工条件を調査し、さらに得られたポリスチレン系樹脂シートに耐油性を付与するための塗工剤について鋭意検討を重ねた結果、ポリスチレン系樹脂を選定し、シート製膜条件によって延伸倍率や配向緩和応力を調整し、得られたポリスチレン系樹脂シートに重合度とケン化度が適切なポリビニルアルコールを塗工することによって、その目的が達成されることを見出し、本発明に至った。
すなわち本発明は、
（１）ポリスチレン系樹脂シートの片方の面に、重合度１５００以上、ケン化度８５モル％以上のポリビニルアルコールの塗膜を形成させてなることを特徴とする耐油性ポリスチレン系樹脂シートに関する。
（２）ポリスチレン系樹脂がメタクリル酸または無水マレイン酸のいずれか一成分を５〜１５質量％含み、重量平均分子量が１５〜４０万であることを特徴とする上記（１）に記載の耐油性ポリスチレン系樹脂シートに関する。
（３）ポリスチレン系樹脂シートが二軸方向に延伸したシートであって、該シートの延伸倍率が１．５〜５．０倍であり、最大配向緩和応力のピーク温度が１２０〜１５０℃であることを特徴とする上記（１）または（２）に記載の耐油性ポリスチレン系樹脂シートに関する。
（４）ポリスチレン系樹脂シートの最大配向緩和応力が０．２〜１．０ＭＰａであることを特徴とする上記（１）〜（３）のいずれかに記載の耐油性ポリスチレン系樹脂シートに関する。
（５）ポリビニルアルコールの塗工量が３０〜３０００ｍｇ／ｍ２であることを特徴とする上記（１）〜（４）のいずれかに記載の耐油性ポリスチレン系樹脂シートに関する。
（６）ポリビニルアルコールの、２０℃、４．０質量％での水溶液粘度が１０〜２００ｍＰａ・ｓであることを特徴とする上記（１）〜（５）のいずれかに記載の耐油性ポリスチレン系樹脂シートに関する。
（７）ポリビニルアルコールの残存酢酸ナトリウム濃度が１．０質量％以下であることを特徴とする上記（１）〜（６）のいずれかに記載の耐油性ポリスチレン系樹脂シートに関する。
（８）上記（１）〜（７）のいずれかに記載の耐油性ポリスチレン系樹脂シートを成形してなる容器に関する。
（９）成形してなる容器が蓋材であることを特徴とする上記（８）記載の容器に関する。
The present inventor investigated the composition, molecular weight, and processing conditions of a polystyrene resin capable of obtaining heat resistance and strength in order to solve the above problems, and further applied a coating for imparting oil resistance to the obtained polystyrene resin sheet. As a result of intensive studies on the processing agent, a polystyrene resin was selected, the draw ratio and orientation relaxation stress were adjusted according to the sheet forming conditions, and the obtained polystyrene resin sheet had a suitable degree of polymerization and saponification. The inventors have found that the purpose is achieved by applying alcohol, and have reached the present invention.
That is, the present invention
(1) It is related with the oil-resistant polystyrene-type resin sheet formed by forming the coating film of the polyvinyl alcohol of polymerization degree 1500 or more and saponification degree 85 mol% or more on the one side of a polystyrene-type resin sheet.
(2) The oil resistance according to (1) above, wherein the polystyrene-based resin contains 5 to 15% by mass of any one component of methacrylic acid or maleic anhydride and has a weight average molecular weight of 150 to 400,000. The present invention relates to a polystyrene resin sheet.
(3) The polystyrene-based resin sheet is a sheet stretched in the biaxial direction, the stretch ratio of the sheet is 1.5 to 5.0 times, and the peak temperature of the maximum orientation relaxation stress is 120 to 150 ° C. The present invention relates to the oil-resistant polystyrene resin sheet as described in (1) or (2) above.
(4) The maximum orientation relaxation stress of a polystyrene-type resin sheet is 0.2-1.0 MPa, It is related with the oil-resistant polystyrene-type resin sheet in any one of said (1)-(3) characterized by the above-mentioned.
(5) It is related with the oil-resistant polystyrene-type resin sheet in any one of said (1)-(4) characterized by the coating amount of polyvinyl alcohol being 30-3000 mg / m < 2 >.
(6) The oil-resistant polystyrene system according to any one of (1) to (5) above, wherein the viscosity of the aqueous solution of polyvinyl alcohol at 20 ° C. and 4.0% by mass is 10 to 200 mPa · s. It relates to a resin sheet.
(7) The residual sodium acetate concentration of polyvinyl alcohol is 1.0% by mass or less, and the oil-resistant polystyrene resin sheet according to any one of (1) to (6) above.
(8) It is related with the container formed by shape | molding the oil-resistant polystyrene-type resin sheet in any one of said (1)-(7).
(9) The container according to (8) above, wherein the molded container is a lid.
本発明により、耐熱性、剛性に優れる上、耐油性にも優れるポリスチレン系樹脂シートが提供できる。熱板成形や真空成形等の方法で成形された容器により、油を含む食品を電子レンジで加熱する用途にも好適に使用できる食品用容器の蓋材を提供できる。 According to the present invention, it is possible to provide a polystyrene resin sheet that is excellent in heat resistance and rigidity and excellent in oil resistance. By using a container molded by a method such as hot plate molding or vacuum molding, it is possible to provide a lid for a food container that can also be suitably used for heating food containing oil in a microwave oven.
以下に本発明を詳細に説明する。
本発明の耐油性ポリスチレン系樹脂シートを構成するポリスチレン系樹脂は、スチレン系単量体８５〜９５質量％、メタクリル酸、または無水マレイン酸のいずれか一成分５〜１５質量％をラジカル共重合して得られる。ラジカル共重合法としては、一般的なラジカル共重合法が採用でき、具体的には懸濁重合、塊状重合、溶液重合が挙げられる。好ましくは懸濁重合により得られる。スチレン系単量体としては、スチレンあるいはスチレン以外にもα−メチルスチレンまたはベンゼン核の一部がアルキル基で置換されたスチレンを使用できるが、特に好ましくはスチレンである。本発明のポリスチレン系樹脂は、スチレン系単量体が８５質量％未満では成形加工性が劣るものとなり、９５質量％を超えると耐熱性が劣るものとなって好ましくない。より好ましい範囲は、メタクリル酸または無水マレイン酸のいずれか一成分が６〜１４質量％、更に好ましくは７〜１３質量％である。なお、単量体は重合初期に全量存在させて重合しても、重合途中に単量体を添加しながら重合しても差し支えない。また、本発明のポリスチレン系樹脂には、ポリスチレン系樹脂の耐熱性、成形性、剛性を損なわない範囲で、他の共重合性単量体が共重合されていてもよい。他の共重合性単量体とは、スチレン系単量体と共重合可能な単量体であれば特に制限はなく、アクリル酸、マレイン酸、イタコン酸、無水イタコン酸等のラジカル重合性多塩基酸およびその無水物、マレイミド、Ｎ−メチルマレイミド、Ｎ−エチルマレイミド、Ｎ−シクロヘキシルマレイミド、Ｎ−フェニルマレイミド等のマレイミド系単量体、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ブチル、（メタ）アクリル酸ヘキシル等の（メタ）アクリル酸エステル系単量体、あるいは（メタ）アクリルアミド、（メタ）アクリルニトリル等の単量体が例示できる。ポリスチレン系樹脂重合時における、他の共重合性単量体は０〜１０質量％の範囲が好ましい。
The present invention is described in detail below.
The polystyrene resin constituting the oil-resistant polystyrene resin sheet of the present invention is a radical copolymerization of 5 to 15% by mass of any one component of 85 to 95% by mass of styrene monomer, methacrylic acid or maleic anhydride. Obtained. As the radical copolymerization method, a general radical copolymerization method can be employed, and specific examples include suspension polymerization, bulk polymerization, and solution polymerization. Preferably it is obtained by suspension polymerization. As the styrene monomer, in addition to styrene or styrene, α-methylstyrene or styrene in which a part of the benzene nucleus is substituted with an alkyl group can be used, and styrene is particularly preferable. When the styrene monomer is less than 85% by mass, the polystyrene resin of the present invention is inferior in moldability, and when it exceeds 95% by mass, the heat resistance is inferior. A more preferable range is 6 to 14% by mass, and more preferably 7 to 13% by mass of any one component of methacrylic acid or maleic anhydride. The monomer may be polymerized in the total amount in the initial stage of polymerization, or may be polymerized while the monomer is added during the polymerization. The polystyrene resin of the present invention may be copolymerized with other copolymerizable monomers as long as the heat resistance, moldability and rigidity of the polystyrene resin are not impaired. The other copolymerizable monomer is not particularly limited as long as it is a monomer copolymerizable with a styrene-based monomer, and includes radically polymerizable monomers such as acrylic acid, maleic acid, itaconic acid, and itaconic anhydride. Maleic monomers such as basic acid and its anhydride, maleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, methyl (meth) acrylate, ethyl (meth) acrylate, Examples include (meth) acrylic acid ester monomers such as (meth) butyl acrylate and (meth) acrylic acid hexyl, and monomers such as (meth) acrylamide and (meth) acrylonitrile. The other copolymerizable monomer in the polymerization of the polystyrene resin is preferably in the range of 0 to 10% by mass.
本発明のポリスチレン系樹脂の重量平均分子量（Ｍｗ）は１５〜４０万である。Ｍｗは光散乱法、ＧＰＣ法、超遠心法等によって測定することができる。Ｍｗが１５万より小さい場合、分子の絡み合いが不十分となり、延伸配向効果が十分に得られ難くなるため、ポリスチレン系樹脂は脆く、該樹脂から得られるシートやその成形品も脆くなる。また、Ｍｗが４０万より大きい場合、溶融粘度が大きくなり、シートにする際の成膜性やその後の二次加工における成形性に劣る。Ｍｗは１５〜３５万の範囲がより好ましい。 The weight average molecular weight (Mw) of the polystyrene resin of the present invention is from 150 to 400,000. Mw can be measured by a light scattering method, a GPC method, an ultracentrifugation method, or the like. When Mw is smaller than 150,000, the molecular entanglement becomes insufficient, and it becomes difficult to sufficiently obtain the stretch orientation effect. Therefore, the polystyrene resin is brittle, and the sheet obtained from the resin and the molded product thereof are also brittle. On the other hand, when Mw is larger than 400,000, the melt viscosity becomes large, and the film formability when forming into a sheet and the formability in the subsequent secondary processing are inferior. Mw is more preferably in the range of 1 to 350,000.
本発明のポリスチレン系樹脂には、必要に応じて酸化防止剤、滑剤、離型剤、可塑剤、含量、染料、無機フィラー、帯電防止剤、摺動剤等公知の添加剤を含有させることもできる。また、本発明のポリスチレン系樹脂には、ブタジエン系ゴムが含まれていてもよい。ブタジエン系ゴムとしては、ハイシスポリブタジエン、ローシスポリブタジエン、スチレン−ブタジエンゴム、スチレン−ブタジエンブロックゴム、スチレン−ブタジエン−スチレンブロックゴム、部分水添ポリブタジエンゴム等が挙げられる。 The polystyrene resin of the present invention may contain known additives such as an antioxidant, a lubricant, a release agent, a plasticizer, a content, a dye, an inorganic filler, an antistatic agent, and a sliding agent as necessary. it can. The polystyrene resin of the present invention may contain butadiene rubber. Examples of the butadiene rubber include high cis polybutadiene, low cis polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, styrene-butadiene-styrene block rubber, and partially hydrogenated polybutadiene rubber.
本発明の耐油性ポリスチレン系樹脂シートを構成するポリスチレン系樹脂シートは、前掲したポリスチレン系樹脂を二軸延伸することによって得られる。さらに、シートおよび成形品の強度を確保するために、延伸倍率と最大配向緩和応力を適切な範囲に調整することが必要となる。ポリスチレン系樹脂を延伸し分子鎖を配向させると、シートの強度が増す。延伸によって分子鎖を配向させるためには、延伸倍率を高くするだけでなく、適切な温度で延伸することが必要となる。一般的には、樹脂のビカット軟化点＋３０℃程度の温度で延伸することが好ましい。延伸温度が低すぎると配向がかかり過ぎ、硬く脆くなってしまう。また、延伸温度が高すぎると配向がかからず、耐衝撃性に劣る。延伸倍率と温度を合わせることで、シートの最大配向緩和応力を適切な範囲におさめることができ、十分なシート強度が得られるようになる。
本発明のポリスチレン系樹脂シートは、延伸倍率が１．５〜５．０倍である。延伸倍率が１．５倍より小さい場合、十分な延伸配向効果が得られず、シートの強度が不足する。また、５．０倍より大きい場合、延伸時の寸法変化が大きいため、厚みの制御が難しくなる。延伸倍率は１．８〜４．５倍がより好ましい。
The polystyrene resin sheet constituting the oil-resistant polystyrene resin sheet of the present invention is obtained by biaxially stretching the above-described polystyrene resin. Furthermore, in order to ensure the strength of the sheet and the molded product, it is necessary to adjust the draw ratio and the maximum orientation relaxation stress to appropriate ranges. When the polystyrene resin is stretched to align the molecular chain, the strength of the sheet increases. In order to orient molecular chains by stretching, it is necessary not only to increase the stretching ratio but also to stretch at an appropriate temperature. In general, it is preferable to stretch the resin at a temperature about Vicat softening point + 30 ° C. If the stretching temperature is too low, the orientation is too much and it becomes hard and brittle. On the other hand, if the stretching temperature is too high, the orientation is not applied and the impact resistance is poor. By combining the draw ratio and the temperature, the maximum orientation relaxation stress of the sheet can be kept within an appropriate range, and a sufficient sheet strength can be obtained.
The polystyrene resin sheet of the present invention has a draw ratio of 1.5 to 5.0 times. When the draw ratio is less than 1.5 times, a sufficient stretch orientation effect cannot be obtained and the strength of the sheet is insufficient. Moreover, when larger than 5.0 times, since the dimensional change at the time of extending | stretching is large, control of thickness becomes difficult. The draw ratio is more preferably 1.8 to 4.5 times.
本発明のポリスチレン系樹脂シートは、最大配向緩和応力のピーク温度が１２０〜１５０℃である。最大配向緩和応力は、ＡＳＴＭＤ１５０４に準じて測定し、最大配向緩和応力のピーク温度は、シート押出方向（縦方向）とそれに垂直な方向（横方向）での配向緩和応力をそれぞれ測定し、その最大値を示す温度として求めることができる。最大配向緩和応力のピーク温度が１２０℃より小さいと、成形後の容器の耐熱性が不足し、電子レンジで加熱する際、容器が収縮し変形する。また、最大配向緩和応力のピーク温度が１５０℃より大きいと、シートを延伸する際に破断等を生じやすい。最大配向緩和応力のピーク温度は、１２１〜１４５℃がより好ましい。 The polystyrene resin sheet of the present invention has a maximum orientation relaxation stress peak temperature of 120 to 150 ° C. The maximum orientation relaxation stress is measured according to ASTM D1504. The peak temperature of the maximum orientation relaxation stress is measured by measuring the orientation relaxation stress in the sheet extrusion direction (longitudinal direction) and the direction perpendicular to the sheet extrusion direction (lateral direction). It can be determined as a temperature indicating the value. If the peak temperature of maximum orientation relaxation stress is less than 120 ° C., the heat resistance of the molded container is insufficient, and the container shrinks and deforms when heated in a microwave oven. Moreover, when the peak temperature of the maximum orientation relaxation stress is higher than 150 ° C., breakage or the like tends to occur when the sheet is stretched. The peak temperature of the maximum orientation relaxation stress is more preferably 121 to 145 ° C.
本発明のポリスチレン系樹脂シートは、最大配向緩和応力が０．２〜１．０ＭＰａである。最大配向緩和応力は、ＡＳＴＭＤ１５０４に準じて測定することができる。最大配向緩和応力が０．２ＭＰａより小さいと、シートが脆くなり耐衝撃性が不足し、指でシートを曲げても割れてしまう耐折性の低いシートとなる。また、最大配向緩和応力が１．０ＭＰａより大きいと、硬く脆くなる傾向にあり、引き裂き強度が低下し裂けやすいシートとなり、スリット加工時等、ノッチに張力がかかったときに横裂けが生じやすく、実用的でない。最大配向緩和応力は、０．４〜０．９ＭＰａがより好ましい。さらには、縦と横の最大配向緩和応力は同程度であることが強度確保には必要である。縦と横の最大配向緩和応力の差が大きいと、シートの方向性が強く存在し、一方向の裂けに対する強度が弱くなる傾向が見られる。これはクラック発生時に応力が配向の低い方向に集中して割れが成長しやすく、配向の低い方向に沿って破断しやすくなるためと考えられる。 The polystyrene-based resin sheet of the present invention has a maximum orientation relaxation stress of 0.2 to 1.0 MPa. The maximum orientation relaxation stress can be measured according to ASTM D1504. When the maximum orientation relaxation stress is less than 0.2 MPa, the sheet becomes brittle, the impact resistance is insufficient, and a sheet with low folding resistance that breaks even when the sheet is bent with a finger is obtained. Further, when the maximum orientation relaxation stress is larger than 1.0 MPa, the sheet tends to be hard and brittle, the tear strength is reduced and the sheet is easy to tear, and when the notch is tensioned, such as slit processing, a lateral tear is likely to occur. Not practical. The maximum orientation relaxation stress is more preferably 0.4 to 0.9 MPa. Furthermore, it is necessary to ensure the strength that the maximum orientation relaxation stress in the vertical and horizontal directions is approximately the same. When the difference between the maximum orientation relaxation stresses in the vertical and horizontal directions is large, there is a strong directionality of the sheet, and a tendency to weaken the strength against tearing in one direction is seen. This is presumably because when cracks occur, stress concentrates in the direction of low orientation and cracks tend to grow, and breaks easily along the direction of low orientation.
本発明のポリスチレン系樹脂シートは、コロナ処理、火炎処理、オゾン処理等の親水化処理を施すこともできる。親水化処理を施すことで、コーティング液が濡れやすくなり、はじきが起こりにくくなる。 The polystyrene-based resin sheet of the present invention can be subjected to hydrophilic treatment such as corona treatment, flame treatment, and ozone treatment. By applying the hydrophilization treatment, the coating liquid becomes easy to get wet and repelling hardly occurs.
本発明の耐油性ポリスチレン系樹脂シートは、上記のポリスチレン系樹脂シートの片方の面に、ポリビニルアルコールの塗膜が形成されたものである。
本発明の耐油性ポリスチレン系樹脂シートに使用されるポリビニルアルコールは、重合度１５００以上、ケン化度８５モル％以上のものである。ポリビニルアルコールの重合度とケン化度は、ＪＩＳＫ ６７２６：１９９４に準じて求めることができる。重合度が１５００より低いと、形成された塗膜の強度が低くなり、容器成形の際に延伸されると塗膜が追従できず、欠陥を生じることがあるため十分な耐油性が得られなくなる。重合度が高いほど耐油性は向上するが、重合度が高くなるほどポリビニルアルコール水溶液の粘度が高くなり、コーティング液が均一に塗工できず、均一な厚みの塗膜を得ることが難しくなり、外観不良となる可能性がある。
また、ケン化度が８５モル％より小さいと、塗膜中に疎水性の部分が増え、油が疎水性部分を通過してポリスチレン系樹脂シートに達しやすくなるため、十分な耐油性が得られなくなる。
The oil-resistant polystyrene-based resin sheet of the present invention is obtained by forming a polyvinyl alcohol coating film on one surface of the polystyrene-based resin sheet.
The polyvinyl alcohol used in the oil-resistant polystyrene resin sheet of the present invention has a polymerization degree of 1500 or more and a saponification degree of 85 mol% or more. The polymerization degree and saponification degree of polyvinyl alcohol can be determined according to JISK 6726: 1994. If the degree of polymerization is lower than 1500, the strength of the formed coating film will be low, and if it is stretched during container molding, the coating film cannot follow and may cause defects, so that sufficient oil resistance cannot be obtained. . The higher the degree of polymerization, the better the oil resistance, but the higher the degree of polymerization, the higher the viscosity of the aqueous polyvinyl alcohol solution, and the coating solution cannot be applied uniformly, making it difficult to obtain a coating with a uniform thickness. It may become defective.
Also, if the degree of saponification is less than 85 mol%, the hydrophobic portion increases in the coating film, and the oil easily passes through the hydrophobic portion and reaches the polystyrene resin sheet, so that sufficient oil resistance is obtained. Disappear.
本発明の耐油性ポリスチレン系樹脂シートに使用されるポリビニルアルコールは、残存酢酸ナトリウム濃度が１．０質量％以下である。残存酢酸ナトリウム濃度は、ＪＩＳＫ ６７２６：１９９４に準じて求めることができる。残存酢酸ナトリウム濃度が１．０質量％より高いと、ポリビニルアルコールの塗膜が形成されたシートおよびこのシートから成形された容器に酢酸臭が残り、食品包装には向かないものとなる。 The polyvinyl alcohol used in the oil-resistant polystyrene resin sheet of the present invention has a residual sodium acetate concentration of 1.0% by mass or less. The residual sodium acetate concentration can be determined according to JISK 6726: 1994. When the residual sodium acetate concentration is higher than 1.0% by mass, an acetic acid odor remains on a sheet on which a polyvinyl alcohol coating film is formed and a container formed from this sheet, and is not suitable for food packaging.
本発明の耐油性ポリスチレン系樹脂シートは、コーティング液としてポリビニルアルコールの水溶液がポリスチレン系樹脂シート上に塗工された後、乾燥されて、ポリビニルアルコールの塗膜が形成される。塗工方式としては、ダイレクトグラビア方式、リバースグラビア方式、キスリバース方式、オフセットグラビア方式等が挙げられ、コーターとしては、グラビアコーター、リバースグラビアコーター、エアナイフコーター、デイップコーター、バーコーター、コンマコーター、ダイコーター等を用いることができる。乾燥方法としては、熱風乾燥や赤外線乾燥等を用いることができる。 The oil-resistant polystyrene resin sheet of the present invention is coated with an aqueous solution of polyvinyl alcohol as a coating liquid on the polystyrene resin sheet, and then dried to form a polyvinyl alcohol coating film. Examples of coating methods include direct gravure method, reverse gravure method, kiss reverse method, offset gravure method, etc. Gravure coater, reverse gravure coater, air knife coater, dip coater, bar coater, comma coater, and die coater. Can be used. As a drying method, hot air drying, infrared drying, or the like can be used.
本発明の耐油性ポリスチレン系樹脂シートにおいて形成されるポリビニルアルコールの塗膜の量は３０〜３０００ｍｇ／ｍ２であり、好ましくは５０〜１０００ｍｇ／ｍ２、さらに好ましくは１００〜６００ｍｇ／ｍ２である。３０ｍｇ／ｍ２より少ないと、容器成形の際に延伸されて欠陥を生じる可能性があり、十分な耐油性が得られない。３０００ｍｇ／ｍ２より多いと、ブロッキングを生じ、外観不良となる可能性がある。 The amount of the polyvinyl alcohol coating film formed in the oil-resistant polystyrene resin sheet of the present invention is 30 to 3000 mg / m 2 , preferably 50 to 1000 mg / m 2 , more preferably 100 to 600 mg / m 2 . . If it is less than 30 mg / m 2, it may be stretched during the molding of the container to cause defects, and sufficient oil resistance cannot be obtained. If it is more than 3000 mg / m 2 , blocking may occur, resulting in poor appearance.
コーティング液におけるポリビニルアルコールの濃度は、０．５〜１０．０質量％であることが好ましい。０．５質量％より低いと、十分な厚みの塗膜を形成するためには、多量のコーティング液を塗工しなければならず、乾燥効率が悪い。１０．０質量％より高いと、コーティング液の粘度が高くなり均一な厚みの塗膜を得ることが難しくなる。また、本発明に使用されるポリビニルアルコールの、２０℃、４．０質量％の粘度は、１０〜２００ｍＰａ・ｓである。粘度は、ＪＩＳ Ｋ ７１１７−１：１９９９に準じて、Ｂ型粘度計にて求めることができる。なお、粘度計の校正にはＪＩＳ Ｚ ８８０９：２０１１に規定する標準液を使用する。本発明に使用されるポリビニルアルコールの、２０℃、４．０質量％の粘度が１０ｍＰａ・ｓより低いと、コーティング液を塗工する際に液が流れてしまい、はじきが生じやすい。また、２００ｍＰａ・ｓより高いと、コーティング液が均一に塗工できず、均一な厚みの塗膜を得ることが難しくなり、外観不良となる可能性がある。 The concentration of polyvinyl alcohol in the coating liquid is preferably 0.5 to 10.0% by mass. If it is lower than 0.5% by mass, a large amount of coating solution must be applied to form a coating film having a sufficient thickness, resulting in poor drying efficiency. When it is higher than 10.0% by mass, the viscosity of the coating liquid becomes high and it becomes difficult to obtain a coating film having a uniform thickness. Moreover, the viscosity of 20 degreeC and 4.0 mass% of the polyvinyl alcohol used for this invention is 10-200 mPa * s. The viscosity can be determined with a B-type viscometer according to JIS K 7117-1: 1999. For calibration of the viscometer, a standard solution specified in JIS Z 8809: 2011 is used. When the polyvinyl alcohol used in the present invention has a viscosity of 20 ° C. and 4.0 mass% lower than 10 mPa · s, the liquid flows when the coating liquid is applied, and repelling tends to occur. On the other hand, if it is higher than 200 mPa · s, the coating solution cannot be applied uniformly, and it becomes difficult to obtain a coating film having a uniform thickness, which may result in poor appearance.
本発明の耐油性ポリスチレン系樹脂シートは、容器の蓋材に成形され使用されるが、蓋の内側にポリビニルアルコールの塗膜が形成された面が向くように成形される。ポリビニルアルコールは水溶性高分子であるため、食品を入れた容器を電子レンジで加熱する際、水分が蓋内側に付着しても、付着した水滴が濡れ広がるため曇りを生じにくい。 The oil-resistant polystyrene-based resin sheet of the present invention is molded and used as a lid material for containers, and is molded so that the surface on which a polyvinyl alcohol coating film is formed faces the inside of the lid. Since polyvinyl alcohol is a water-soluble polymer, when a container containing food is heated in a microwave oven, even if moisture adheres to the inner side of the lid, the attached water droplets are wet and spread, so that cloudiness is hardly generated.
本発明の耐油性ポリスチレン系樹脂シートは、耐油性に優れるため、ポリスチレン系樹脂に対する侵食力が最も強い中鎖脂肪酸油（ＭＣＴ）をはじめ、様々な食用油に対して優れた耐油性能を示す。 Since the oil-resistant polystyrene resin sheet of the present invention is excellent in oil resistance, it exhibits excellent oil resistance against various edible oils including medium chain fatty acid oil (MCT), which has the strongest erosion power against polystyrene resin.
ポリビニルアルコールからなるコーティング液は、本発明の耐油性ポリスチレン系樹脂の耐油性や透明性等の諸物性を損なわない範囲で、消泡剤、界面活性剤、防腐剤、光安定剤等公知の添加剤を含有させることもできる。この場合、添加剤の含有量は２０．０質量％以下が好ましく、さらには１０．０質量％以下が好ましい。また、ポリビニルアルコールからなるコーティング液は、塗工性や乾燥効率を良くするために、水溶性の有機溶媒を含んでいてもよい。水溶性の有機溶媒としては、アルコール、アセトン等が挙げられる。この場合、水溶性の有機溶媒の含有量は、コーティング液の溶媒において１０．０質量％以下が好ましく、さらには５．０質量％以下が好ましい。 The coating solution made of polyvinyl alcohol is a known additive such as an antifoaming agent, a surfactant, a preservative, and a light stabilizer, as long as various properties such as oil resistance and transparency of the oil-resistant polystyrene resin of the present invention are not impaired. An agent can also be contained. In this case, the content of the additive is preferably 20.0% by mass or less, and more preferably 10.0% by mass or less. Moreover, the coating liquid which consists of polyvinyl alcohol may contain the water-soluble organic solvent in order to improve coating property and drying efficiency. Examples of the water-soluble organic solvent include alcohol and acetone. In this case, the content of the water-soluble organic solvent is preferably 10.0% by mass or less, more preferably 5.0% by mass or less in the solvent of the coating solution.
本発明の耐油性ポリスチレン系樹脂シートは、ポリビニルアルコールの塗膜が形成された面とは反対の面に、離型剤が塗工されていてもよい。離型剤としては、シリコーンエマルジョン、ショ糖脂肪酸エステル、水溶性高分子、界面活性剤からなるコーティング液を使用することができる。この場合、シリコーンエマルジョンとしては、ポリシロキサン骨格で、両端または片端がメチル基、あるいはフェニル基であるシリコーンオイルからなるものが有効である。ショ糖脂肪酸エステルとしては、カプロン酸、カプリン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、ベヘニン酸、モンタン酸等の炭素数６〜３０の飽和脂肪酸のエステルや、リンデン酸、パルミトオレイン酸、オレイン酸、エライジン酸、イソオレイン酸、エルカ酸、リノール酸、リノレン酸等の炭素数１０〜２４の不飽和脂肪酸のエステルが挙げられ、これら脂肪酸エステルは単独でも併用してもよい。その中でも炭素数が１０〜１４の脂肪酸のエステルが有効である。水溶性高分子としては、メチルセルロース、ポリエチレングリコール、ポリエチレングリコールとポリプロピレングリコール共重合体樹脂が好ましい。界面活性剤としては特に制限はないが、シート表面に静電気が帯電しやすいため、帯電防止性を発揮する界面活性剤がよい。その中でポリオキシエチレンソルビタン脂肪酸エステル、アルキル硫酸エステル塩が好ましい。ポリオキシエチレンソルビタン脂肪酸エステルの場合の脂肪酸としては、例えばカプロン酸、カプリル酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、ベヘニン酸、モンタン酸等の炭素数６〜３０の飽和脂肪酸、リンデン酸、パルミトオレイン酸、オレイン酸、エライジン酸、イソオレイン酸、エルカ酸、リノール酸、リノレン酸などの炭素数１０〜２４の不飽和脂肪酸が挙げられる。その中でも炭素数が１０〜１４の脂肪酸が好ましい。 In the oil-resistant polystyrene resin sheet of the present invention, a release agent may be coated on the surface opposite to the surface on which the polyvinyl alcohol coating film is formed. As a mold release agent, a coating liquid comprising a silicone emulsion, a sucrose fatty acid ester, a water-soluble polymer, and a surfactant can be used. In this case, a silicone emulsion having a polysiloxane skeleton and consisting of a silicone oil in which both ends or one end is a methyl group or a phenyl group is effective. Examples of sucrose fatty acid esters include caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid and other esters of saturated fatty acids having 6 to 30 carbon atoms, lindenic acid, palmitoolein Examples thereof include esters of unsaturated fatty acids having 10 to 24 carbon atoms such as acid, oleic acid, elaidic acid, isooleic acid, erucic acid, linoleic acid and linolenic acid, and these fatty acid esters may be used alone or in combination. Of these, esters of fatty acids having 10 to 14 carbon atoms are effective. As the water-soluble polymer, methyl cellulose, polyethylene glycol, polyethylene glycol and polypropylene glycol copolymer resin are preferable. Although there is no restriction | limiting in particular as surfactant, Since the static electricity is easy to be charged to the sheet | seat surface, surfactant which exhibits antistatic property is good. Among them, polyoxyethylene sorbitan fatty acid ester and alkyl sulfate ester salt are preferable. Examples of the fatty acid in the case of polyoxyethylene sorbitan fatty acid ester include caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, etc., saturated fatty acid having 6 to 30 carbon atoms, lindenic acid , Unsaturated fatty acids having 10 to 24 carbon atoms such as palmitooleic acid, oleic acid, elaidic acid, isooleic acid, erucic acid, linoleic acid and linolenic acid. Of these, fatty acids having 10 to 14 carbon atoms are preferred.
本発明の耐油性ポリスチレン系樹脂シートは、公知の手法により食品包装容器とすることができる。例えば、シートを加熱してやわらかくし、型の中の空気を吸引し大気圧で型に押し付けて成形する真空成形や、真空成形で型の中の空気を吸引する時、同時に上から圧縮空気を送ってシートを金型に密着させる圧空成形等の方法が挙げられる。 The oil-resistant polystyrene resin sheet of the present invention can be used as a food packaging container by a known method. For example, when the sheet is heated and softened, the air in the mold is sucked and pressed against the mold at atmospheric pressure to form, or when the air in the mold is sucked by vacuum forming, compressed air is simultaneously applied from above. For example, a method such as pressure forming for feeding and bringing the sheet into close contact with the mold may be used.
［重合度の測定］
ＪＩＳ Ｋ ６７２６：１９９４に準じて、ポリビニルアルコールを水酸化ナトリウムにて完全にケン化した後、粘度計を用いて水との相対粘度を求め、計算によって平均重合度を求めた。
［ケン化度の測定］
ＪＩＳ Ｋ ６７２６：１９９４に準じて、ポリビニルアルコールを溶解後、滴定法により残存酢酸基の定量を行い、計算によってケン化度を求めた。
［粘度の測定］
ＪＩＳ Ｋ ７１１７−１：１９９９に準じて、Ｂ型粘度計にて、２０℃、４．０質量％のポリビニルアルコール水溶液の粘度を測定した。
［残存酢酸ナトリウム濃度の測定］
ＪＩＳ Ｋ ６７２６：１９９４に準じて、ポリビニルアルコールを溶解後、指示薬を添加し、塩酸滴定法により測定した。単位は原試料に対する質量％である。
［重量平均分子量の測定］
テトラヒドロフランを溶媒としてポリスチレン系樹脂を溶解し、２質量％の溶液を作製し測定サンプルとした。カラムとしてＰＬ ｇｅｌ ＭＩＸＥＤ−Ｂ（Ｐｏｌｙｍｅｒ Ｌａｂｏｌａｔｏｒｉｅｓ社製）を３本直列でつなぎ、移動相としてテトラヒドロフランを使用し、ＳＹＳＴＥＭ−２１ Ｓｈｏｄｅｘ（昭和電工社製）を使って、４０℃にて重量平均分子量を測定した。
［シート成膜性の評価］
φ４０ｍｍのシート押出し機（田辺プラスチック機械社製）で樹脂を２４０℃で溶融混練し、Ｔ−ダイより押出し、無延伸シートを得た。得られた無延伸シートを、二軸延伸試験装置（東洋精機社製）にて、ビカット軟化点＋３０℃の温度、３００ｍｍ／ｍｉｎの速度で縦横に延伸してシートを得た。なお、ビカット軟化点は、ＪＩＳ Ｋ ７２０６：１９９９に準じて、昇温速度５０℃／ｈ、荷重５０Ｎの条件で求めることができる。得られたシートの状態を目視にて下記Ａ〜Ｅの５段階で評価した。
Ａ：透明かつ平滑なシートである
Ｂ：平滑だがわずかに不透明なシートである
Ｃ：平滑ではない
Ｄ：延伸および冷却時に割れや破断が生じる
Ｅ：延伸および冷却時に割れや破断が生じシートが得られない
［配向緩和応力の測定］
ＡＳＴＭ Ｄ１５０４に準じて、ポリスチレン系樹脂シートのシート押出方向（縦方向）とそれに垂直な方向（横方向）の配向緩和応力を測定した。
［引裂き強度の評価］
ＪＩＳ Ｋ ７１２８−２：１９９８に準じて、シート押出方向（縦方向）とそれに垂直な方向（横方向）の最大引き裂き荷重を測定した。縦横の平均値を求め、下記Ａ〜Ｃの３段階で評価した。
Ａ：１５００Ｎ／ｃｍ以上
Ｂ：１３００Ｎ／ｃｍ以上、１５００Ｎ／ｃｍ未満
Ｃ：１３００Ｎ／ｃｍ未満
［耐折性の評価］
ＡＳＴＭ Ｄ２１７６に準じて、シート押出方向（縦方向）とそれに垂直な方向（横方向）の耐折曲げ強さを測定した。縦横の平均値を求め、下記Ａ〜Ｃの３段階で評価した。
Ａ：１０回以上
Ｂ：５回以上、１０回未満
Ｃ：５回未満
［塗工外観の評価］
ポリスチレン系樹脂シートにコーティング液を塗工した後、塗工面の外観を、下記Ａ〜Ｃの３段階で評価した。
Ａ：塗工面は平滑で透明である
Ｂ：不透明さがあるが、シートを通して反対側を視認可能である
Ｃ：シートを通して反対側を視認不良である
［防曇性の評価］
（株）脇坂エンジニアリング社製の熱板成形機（ＨＰＴ−４６０Ｓ）を用いて、ポリスチレン系樹脂シートを、弁当蓋の形状の金型（天面２００×１５０ｍｍ、高さ３０ｍｍ）で成形した。
得られた蓋容器に対応する容器本体に、１ｃｍ間隔の格子柄のシート（格子の線の太さは２ｍｍ）を貼付け、水３００ｇを入れた後、得られた蓋容器をかぶせ、出力１５００Ｗの電子レンジで１分間加熱した。加熱後に蓋容器を通した格子柄の見えやすさを、目視にて下記Ａ〜Ｄの４段階で評価した。
Ａ：格子柄がはっきり見える
Ｂ：わずかに格子柄が揺らいで見える
Ｃ：格子柄の揺らぎが多く、ぎらつく
Ｄ：全体的に曇った状態で、格子柄がはっきり見えない
［熱変形率の評価］
防曇性の評価にて成形した弁当蓋の容器の縦、横の寸法を測定し、１１０℃に設定したオーブンに３０分間入れた。オーブン加熱後の容器の縦、横の寸法を測定し、縦、横それぞれについて、加熱前の寸法に対する、加熱前後での寸法差の割合を求め、熱変形率とした。縦、横の熱変形率のうち大きい方の値により、熱変形率を下記Ａ〜Ｃの３段階で評価した。
Ａ：変形率が２％未満
Ｂ：変形率が２％以上〜５％未満
Ｃ：変形率が５％以上
［臭気の評価］
防曇性の評価にて成形した弁当容器を使い、容器本体に水３００ｇを入れ、蓋容器をかぶせて出力１５００Ｗの電子レンジで１分間加熱した後、蓋を開けたときの臭いを官能評価した。
Ａ：まったく酢酸の臭いはしない
Ｂ：わずかに酢酸の臭いを感じる
Ｃ：鼻につくほどの酢酸の臭いを感じる
［電子レンジ使用適性の評価］
防曇性の評価にて成形した弁当容器を使い、蓋の内側中央に２×２ｃｍで中鎖脂肪酸油（花王（株）製 ココナードＭＬ）を付けた。容器本体に水３００ｇを入れ、蓋容器をかぶせて出力１５００Ｗの電子レンジで１分間加熱した後、中鎖脂肪酸油付着部分の様子を目視にて下記Ａ〜Ｃの３段階で評価した。
Ａ：変化なし
Ｂ：白化あり
Ｃ：穴あき
[Measurement of degree of polymerization]
According to JIS K 6726: 1994, after polyvinyl alcohol was completely saponified with sodium hydroxide, the relative viscosity with water was determined using a viscometer, and the average degree of polymerization was determined by calculation.
[Measurement of saponification degree]
In accordance with JIS K 6726: 1994, after dissolving polyvinyl alcohol, the residual acetate groups were quantified by a titration method, and the degree of saponification was determined by calculation.
[Measurement of viscosity]
According to JIS K 7117-1: 1999, the viscosity of the polyvinyl alcohol aqueous solution of 20 degreeC and 4.0 mass% was measured with the B-type viscosity meter.
[Measurement of residual sodium acetate concentration]
According to JIS K 6726: 1994, after dissolving polyvinyl alcohol, an indicator was added, and the measurement was performed by the hydrochloric acid titration method. The unit is mass% with respect to the original sample.
[Measurement of weight average molecular weight]
A polystyrene resin was dissolved in tetrahydrofuran as a solvent to prepare a 2% by mass solution, which was used as a measurement sample. Three columns of PL gel MIXED-B (Polymer Laboratories) were connected in series, tetrahydrofuran was used as the mobile phase, and the weight average molecular weight was measured at 40 ° C. using SYSTEM-21 Shodex (manufactured by Showa Denko). It was measured.
[Evaluation of sheet film formability]
The resin was melt-kneaded at 240 ° C. with a 40 mm sheet extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) and extruded from a T-die to obtain an unstretched sheet. The obtained unstretched sheet was stretched vertically and horizontally at a temperature of Vicat softening point + 30 ° C. and a speed of 300 mm / min with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.) to obtain a sheet. The Vicat softening point can be determined under the conditions of a heating rate of 50 ° C./h and a load of 50 N according to JIS K 7206: 1999. The state of the obtained sheet was visually evaluated in the following five stages A to E.
A: A transparent and smooth sheet B: A smooth but slightly opaque sheet C: Not smooth D: Cracks and breaks during stretching and cooling E: Cracks and breaks during stretching and cooling to obtain a sheet [Measurement of orientational relaxation stress]
According to ASTM D1504, the orientation relaxation stress in the sheet extrusion direction (longitudinal direction) and the direction perpendicular to the polystyrene resin sheet (transverse direction) was measured.
[Evaluation of tear strength]
According to JIS K 7128-2: 1998, the maximum tearing load in the sheet extrusion direction (longitudinal direction) and the direction perpendicular thereto (lateral direction) was measured. The average value of length and breadth was calculated | required and evaluated in three steps of following AC.
A: 1500 N / cm or more B: 1300 N / cm or more, less than 1500 N / cm C: less than 1300 N / cm [Folding resistance evaluation]
In accordance with ASTM D2176, the bending strength in the sheet extrusion direction (longitudinal direction) and the direction perpendicular thereto (lateral direction) was measured. The average value of length and breadth was calculated | required and evaluated in three steps of following AC.
A: 10 times or more B: 5 times or more and less than 10 times C: less than 5 times [Evaluation of coating appearance]
After coating the coating liquid on the polystyrene resin sheet, the appearance of the coated surface was evaluated in the following three stages AC.
A: The coated surface is smooth and transparent. B: Although there is opacity, the opposite side is visible through the sheet. C: The opposite side is not visible through the sheet. [Anti-fogging evaluation]
Using a hot plate molding machine (HPT-460S) manufactured by Wakisaka Engineering Co., Ltd., a polystyrene resin sheet was molded with a mold (top surface 200 × 150 mm, height 30 mm) in the shape of a lunch box lid.
A grid pattern sheet with a 1 cm interval (the thickness of the grid line is 2 mm) is affixed to the container body corresponding to the obtained lid container, and after putting 300 g of water, the obtained lid container is covered, and the output is 1500 W. Heated in microwave for 1 minute. The visibility of the lattice pattern through the lid container after heating was visually evaluated in the following four grades A to D.
A: The lattice pattern is clearly visible B: The lattice pattern is slightly fluctuated C: The lattice pattern is largely fluctuated and glaring D: The lattice pattern is not clearly visible in a cloudy state as a whole ]
The vertical and horizontal dimensions of the container of the lunch box lid molded in the evaluation of antifogging properties were measured, and placed in an oven set at 110 ° C. for 30 minutes. The vertical and horizontal dimensions of the container after oven heating were measured, and for each of the vertical and horizontal dimensions, the ratio of the dimensional difference before and after heating to the dimension before heating was determined to obtain the thermal deformation rate. The thermal deformation rate was evaluated in the following three grades A to C based on the larger value of the vertical and horizontal thermal deformation rates.
A: Deformation rate is less than 2% B: Deformation rate is 2% to less than 5% C: Deformation rate is 5% or more [Odor evaluation]
Using a bento container molded with anti-fogging evaluation, put 300 g of water into the container body, cover the lid container and heat it in a microwave oven with an output of 1500 W, and then sensoryly evaluate the odor when the lid is opened. .
A: Does not smell of acetic acid at all B: Feels a slight smell of acetic acid C: Feels the smell of acetic acid enough to get on the nose [Evaluation of suitability for microwave oven use]
A lunch box container molded in the evaluation of anti-fogging property was used, and a medium chain fatty acid oil (Coconard ML manufactured by Kao Corporation) was attached at 2 × 2 cm in the center of the lid. After putting 300 g of water into the container body, covering the lid container and heating in a microwave oven with an output of 1500 W for 1 minute, the state of the medium chain fatty acid oil adhering portion was visually evaluated in the following three stages AC.
A: No change B: Whitening C: Perforated
［実施例１］
メタクリル酸含有量が１０．０質量％のスチレン−メタクリル酸共重合体（重量平均分子量２０万）をφ４０ｍｍのシート押出し機（田辺プラスチック機械社製）に供給し２８０℃で溶融混練し、Ｔ−ダイより押出し無延伸シートを得た。得られた無延伸シートを、二軸延伸試験装置（東洋精機社製）にて、ビカット軟化点＋３０℃の温度にて、３００ｍｍ／ｍｉｎの速度で縦、横方向にそれぞれ２．５倍延伸した後、厚みが０．３ｍｍのポリスチレン系樹脂シートを得た。得られたシートの最大配向緩和応力は縦横ともに０．６ＭＰａ、最大配向緩和応力のピーク温度は１３１℃であった。
得られたポリスチレン系樹脂シートの片方の面に、ポリビニルアルコール（重合度１７００、ケン化度９８モル％、４．０質量％での粘度２８ｍＰａ・ｓ（２０℃）、酢酸ナトリウム残存率０．５質量％以下）を、１．０質量％の濃度でバーコーターにて塗工し、９０℃で乾燥して、３００ｍｇ／ｍ２の塗膜を形成し、耐油性ポリスチレン系樹脂シートを得た。
得られた耐油性ポリスチレン系樹脂シートについて、成膜性、引裂き強度、耐折性、塗工外観、防曇性、熱変形率、臭気、電子レンジ使用適性を評価した。
ポリスチレン系樹脂の特性値およびシート物性、コーティング液、耐油性ポリスチレン系樹脂シートの性能評価については、表１に記載した。
［実施例２］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が８．０質量％、重量平均分子量が２０万であり、最大配向緩和応力のピーク温度が１２７℃であるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例３］
延伸倍率を変えて、縦方向に１．５倍、横方向に１．５倍とし、最大配向緩和応力が縦０．３ＭＰａ、横０．２ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例２と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例４］
延伸時の温度条件を変えて成膜し、最大配向緩和応力が縦０．８ＭＰａ、横０．９ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例２と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例５］
スチレン−メタクリル酸系共重合体の重量平均分子量が１５万であるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例６］
スチレン−メタクリル酸系共重合体の重量平均分子量が２０万であるポリスチレン系樹脂シートを用いて、重合度が２６００、ケン化度が９９モル％、４．０質量％での粘度（２０℃）が６４ｍＰａ・ｓであるポリビニルアルコールを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例７］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が６．０質量％、重量平均分子量が４０万であり、最大配向緩和応力のピーク温度が１２３℃、最大配向緩和応力が縦横ともに０．７ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例８］
ポリビニルアルコールを、重合度１７００、ケン化度８５モル％、４．０質量％での粘度（２０℃）２３ｍＰａ・ｓ、酢酸ナトリウム残存率０．５質量％以下のものを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例９］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が１３．０質量％、重量平均分子量が２０万であり、最大配向緩和応力のピーク温度が１３７℃、最大配向緩和応力が縦横ともに０．６ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１０］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が１５．０質量％、重量平均分子量が２０万であり、最大配向緩和応力のピーク温度が１４１℃、最大配向緩和応力が縦横ともに０．５ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１１］
無水マレイン酸含有率が１０．０質量％のスチレン−無水マレイン酸系共重合体（重量平均分子量が２５万）であり、最大配向緩和応力のピーク温度が１３３℃、最大配向緩和応力が縦横ともに０．６ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１２］
ポリビニルアルコールの塗膜を１０００ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１３］
ポリビニルアルコールの塗膜を６００ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１４］
ポリビニルアルコールの塗膜を１００ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［実施例１５］
ポリビニルアルコールの塗膜を３０ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１］
ポリスチレン（重量平均分子量３０万）を用いて、最大配向緩和応力のピーク温度が１１２℃、最大配向緩和応力が縦横ともに０．５ＭＰａのポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例２］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が３．０質量％、重量平均分子量が２０万であり、最大配向緩和応力のピーク温度が１１７℃であるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例３］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が１８．０質量％、重量平均分子量が２０万であり、最大配向緩和応力のピーク温度が１４７℃であるポリスチレン系樹脂を用いて、縦方向に２．５倍、横方向に２．５倍延伸し、シートを作製しようと試みたが、シートが脆く割れてしまい、成膜できなかった。
［比較例４］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が１０．０質量％、重量平均分子量が１０万であり、最大配向緩和応力のピーク温度が１３１℃、最大配向緩和応力が縦横ともに０．５ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例５］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が１０．０質量％、重量平均分子量が１３万であり、最大配向緩和応力のピーク温度が１３１℃、最大配向緩和応力が縦横ともに０．６ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例６］
スチレン−メタクリル酸系共重合体のメタクリル酸含有量が６．０質量％、重量平均分子量が４５万であり、最大配向緩和応力のピーク温度が１２３℃であるポリスチレン系樹脂を用いて、縦方向に２．５倍、横方向に２．５倍延伸し、シートを作製したが、シートにゲルやブツが混入しており、透明平滑なシートが得られなかった。
［比較例７］
延伸倍率を変えて、縦方向に１．２倍、横方向に対し垂直な方向に１．２倍とし、シートを作製しようと試みたが、延伸および冷却時に割れが生じやすかった。かろうじて得られたシートの最大配向緩和応力は０．１ＭＰａであった。延伸倍率と最大配向緩和応力以外は実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例８］
延伸倍率を変えて、縦方向に６．０倍、横方向に対し垂直な方向に６．０倍とし、最大配向緩和応力が縦横ともに１．２ＭＰａであるポリスチレン系樹脂シートを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例９］
延伸時の温度条件を変えて成膜し、最大配向緩和応力が縦横とも０．１ＭＰａであるポリスチレン系樹脂シートを作製しようと試みたが、延伸および冷却時に割れが生じやすかった。かろうじて得られたシートについて、最大配向緩和応力以外は実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１０］
重合度が２０００、ケン化度が８０モル％、４．０質量％での粘度（２０℃）が３５ｍＰａ・ｓ、酢酸ナトリウム残存率０．５質量％以下であるポリビニルアルコールを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１１］
重合度が１０００、ケン化度が８６モル％、４．０室量％での粘度（２０℃）が９ｍＰａ・ｓ、酢酸ナトリウム残存率０．５％以下であるポリビニルアルコールを用いた以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１２］
ポリビニルアルコールの塗膜を２０ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１３］
ポリビニルアルコールの塗膜を３２００ｍｇ／ｍ２形成した以外は、実施例１と同様にして耐油性ポリスチレン系樹脂シートを得て、評価した。
［比較例１４］
重合度が２０００、ケン化度が８８モル％、４．０質量％での粘度（２０℃）が３０ｍＰａ・ｓ、残存酢酸ナトリウム濃度が５．０質量％であるポリビニルアルコールを用いた以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
［比較例１５］
ポリビニルアルコールに代わりに、ポリエチレンエマルジョン（中央理化工業（株）製 アクアテックスＥＣ−３５００）を塗工した以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
［比較例１６］
ポリビニルアルコールに代わりに、ポリアクリル酸ナトリウム（東亞合成（株）製 アロンビスＳＸ）の水溶液を塗工した以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
［比較例１７］
ポリビニルアルコールに代わりに、カルボキシメチルセルロース（ダイセル化学工業（株）製 ＣＭＣダイセル１１１０）の水溶液を塗工した以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
［比較例１８］
ポリビニルアルコールに代わりに、ヒドロキシプロピルメチルセルロース（信越化学工業（株）製 ６０ＳＨ−５０）の水溶液を塗工した以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
［比較例１９］
ポリビニルアルコールに代わりに、アクリル酸アルキル共重合体のエマルジョン（東亞合成（株）製 ジュリマーＥＴ−４１０）を塗工した以外は、実施例１と同様にしてポリスチレン系樹脂シートを得て、評価した。
[Example 1]
A styrene-methacrylic acid copolymer (weight average molecular weight 200,000) having a methacrylic acid content of 10.0% by mass is supplied to a sheet extruder having a diameter of 40 mm (manufactured by Tanabe Plastic Machinery Co., Ltd.) and melt-kneaded at 280 ° C. An unstretched extruded sheet was obtained from the die. The obtained unstretched sheet was stretched 2.5 times in the longitudinal and lateral directions at a speed of 300 mm / min at a temperature of Vicat softening point + 30 ° C. using a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.). Thereafter, a polystyrene resin sheet having a thickness of 0.3 mm was obtained. The maximum orientation relaxation stress of the obtained sheet was 0.6 MPa in both length and width, and the peak temperature of the maximum orientation relaxation stress was 131 ° C.
On one side of the obtained polystyrene resin sheet, polyvinyl alcohol (polymerization degree 1700, saponification degree 98 mol%, viscosity 28 mPa · s at 4.0% by mass (20 ° C.), sodium acetate residual ratio 0.5 (Mass% or less) was coated with a bar coater at a concentration of 1.0 mass% and dried at 90 ° C. to form a 300 mg / m 2 coating film to obtain an oil resistant polystyrene resin sheet.
The resulting oil-resistant polystyrene resin sheet was evaluated for film formability, tear strength, folding resistance, coating appearance, antifogging property, thermal deformation rate, odor, and microwave oven suitability.
The characteristic values of the polystyrene resin and the physical properties of the sheet, the coating liquid, and the performance evaluation of the oil resistant polystyrene resin sheet are shown in Table 1.
[Example 2]
A styrene-methacrylic acid copolymer has a methacrylic acid content of 8.0% by mass, a weight average molecular weight of 200,000, and a polystyrene resin sheet having a maximum orientation relaxation stress peak temperature of 127 ° C. In the same manner as in Example 1, an oil resistant polystyrene resin sheet was obtained and evaluated.
[Example 3]
Implemented except changing the draw ratio to 1.5 times in the vertical direction and 1.5 times in the horizontal direction, and using a polystyrene resin sheet having a maximum orientation relaxation stress of 0.3 MPa in length and 0.2 MPa in width In the same manner as in Example 2, an oil-resistant polystyrene resin sheet was obtained and evaluated.
[Example 4]
An oil-resistant polystyrene resin was formed in the same manner as in Example 2 except that a film was formed by changing the temperature conditions during stretching and a polystyrene resin sheet having a maximum orientation relaxation stress of 0.8 MPa in length and 0.9 MPa in width was used. Sheets were obtained and evaluated.
[Example 5]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that a polystyrene resin sheet having a weight average molecular weight of 150,000 was used for the styrene-methacrylic acid copolymer.
[Example 6]
Viscosity at a polymerization degree of 2600, a saponification degree of 99 mol%, and 4.0 mass% (20 ° C.) using a polystyrene resin sheet having a weight-average molecular weight of styrene-methacrylic acid copolymer of 200,000. An oil-resistant polystyrene-based resin sheet was obtained and evaluated in the same manner as in Example 1 except that polyvinyl alcohol having a viscosity of 64 mPa · s was used.
[Example 7]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 6.0 mass%, a weight average molecular weight of 400,000, a maximum orientation relaxation stress peak temperature of 123 ° C., and a maximum orientation relaxation stress of 0.7 MPa in both length and width. An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that the polystyrene resin sheet was used.
[Example 8]
Except for using polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 85 mol%, a viscosity at 4.0% by mass (20 ° C.) of 23 mPa · s, and a residual ratio of sodium acetate of 0.5% by mass or less. In the same manner as in Example 1, an oil resistant polystyrene resin sheet was obtained and evaluated.
[Example 9]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 13.0% by mass, a weight average molecular weight of 200,000, a maximum orientation relaxation stress peak temperature of 137 ° C., and a maximum orientation relaxation stress of 0.6 MPa in both length and width. An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that the polystyrene resin sheet was used.
[Example 10]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 15.0 mass%, a weight average molecular weight of 200,000, a peak temperature of maximum orientation relaxation stress of 141 ° C., and a maximum orientation relaxation stress of 0.5 MPa in both length and width. An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that the polystyrene resin sheet was used.
[Example 11]
It is a styrene-maleic anhydride copolymer having a maleic anhydride content of 10.0% by mass (weight average molecular weight is 250,000), the peak temperature of maximum orientation relaxation stress is 133 ° C., and the maximum orientation relaxation stress is both longitudinal and lateral An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that a polystyrene resin sheet having a pressure of 0.6 MPa was used.
[Example 12]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that a coating film of polyvinyl alcohol was formed at 1000 mg / m 2 .
[Example 13]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that 600 mg / m 2 of the polyvinyl alcohol coating film was formed.
[Example 14]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that 100 mg / m 2 of a polyvinyl alcohol coating film was formed.
[Example 15]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that 30 mg / m 2 of a polyvinyl alcohol coating film was formed.
[Comparative Example 1]
Example 1 was used except that polystyrene (weight average molecular weight 300,000) was used, and a polystyrene resin sheet having a maximum orientation relaxation stress peak temperature of 112 ° C. and a maximum orientation relaxation stress of 0.5 MPa in both vertical and horizontal directions was used. An oil-resistant polystyrene resin sheet was obtained and evaluated.
[Comparative Example 2]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 3.0% by mass, a weight average molecular weight of 200,000, and a polystyrene resin sheet having a maximum orientation relaxation stress peak temperature of 117 ° C. In the same manner as in Example 1, an oil resistant polystyrene resin sheet was obtained and evaluated.
[Comparative Example 3]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 18.0% by mass, a weight average molecular weight of 200,000, and a peak temperature of maximum orientation relaxation stress of 147 ° C. The sheet was stretched 2.5 times in the horizontal direction and 2.5 times in the lateral direction to try to produce a sheet, but the sheet was brittle and cracked, and the film could not be formed.
[Comparative Example 4]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 10.0% by mass, a weight average molecular weight of 100,000, a maximum orientation relaxation stress peak temperature of 131 ° C., and a maximum orientation relaxation stress of 0.5 MPa in both length and width. An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that the polystyrene resin sheet was used.
[Comparative Example 5]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 10.0% by mass, a weight average molecular weight of 130,000, a peak temperature of maximum orientation relaxation stress of 131 ° C., and a maximum orientation relaxation stress of 0.6 MPa in both length and width. An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that the polystyrene resin sheet was used.
[Comparative Example 6]
The styrene-methacrylic acid copolymer has a methacrylic acid content of 6.0% by mass, a weight average molecular weight of 450,000, and a maximum orientation relaxation stress peak temperature of 123 ° C. The sheet was stretched 2.5 times in the horizontal direction and 2.5 times in the lateral direction to produce a sheet, but gel and solids were mixed in the sheet, and a transparent and smooth sheet could not be obtained.
[Comparative Example 7]
An attempt was made to produce a sheet by changing the draw ratio to 1.2 times in the machine direction and 1.2 times in the direction perpendicular to the transverse direction, but cracking was likely to occur during drawing and cooling. The maximum orientation relaxation stress of the barely obtained sheet was 0.1 MPa. An oil-resistant polystyrene-based resin sheet was obtained and evaluated in the same manner as in Example 1 except for the draw ratio and the maximum orientation relaxation stress.
[Comparative Example 8]
Except for changing the draw ratio to 6.0 times in the vertical direction and 6.0 times in the direction perpendicular to the horizontal direction, and using a polystyrene resin sheet having a maximum orientation relaxation stress of 1.2 MPa in both vertical and horizontal directions, In the same manner as in Example 1, an oil-resistant polystyrene resin sheet was obtained and evaluated.
[Comparative Example 9]
An attempt was made to produce a polystyrene-based resin sheet having a maximum orientation relaxation stress of 0.1 MPa in both longitudinal and lateral directions by changing the temperature conditions during stretching, but cracking was likely to occur during stretching and cooling. About the sheet | seat obtained barely, oil resistant polystyrene-type resin sheet was obtained and evaluated like Example 1 except the maximum orientation relaxation stress.
[Comparative Example 10]
Except for using polyvinyl alcohol having a degree of polymerization of 2000, a degree of saponification of 80 mol%, a viscosity at 4.0% by mass (20 ° C.) of 35 mPa · s, and a residual ratio of sodium acetate of 0.5% by mass or less. In the same manner as in Example 1, an oil-resistant polystyrene resin sheet was obtained and evaluated.
[Comparative Example 11]
Except for using polyvinyl alcohol having a degree of polymerization of 1000, a degree of saponification of 86 mol%, a viscosity (20 ° C.) at 4.0% by volume of 9 mPa · s, and a residual ratio of sodium acetate of 0.5% or less. In the same manner as in Example 1, an oil-resistant polystyrene resin sheet was obtained and evaluated.
[Comparative Example 12]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that a polyvinyl alcohol coating film was formed at 20 mg / m 2 .
[Comparative Example 13]
An oil-resistant polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that 3200 mg / m 2 of a polyvinyl alcohol coating film was formed.
[Comparative Example 14]
Except for using polyvinyl alcohol having a polymerization degree of 2000, a saponification degree of 88 mol%, a viscosity at 4.0% by mass (20 ° C.) of 30 mPa · s, and a residual sodium acetate concentration of 5.0% by mass, In the same manner as in Example 1, a polystyrene resin sheet was obtained and evaluated.
[Comparative Example 15]
A polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that a polyethylene emulsion (Aquatex EC-3500 manufactured by Chuo Rika Kogyo Co., Ltd.) was applied instead of polyvinyl alcohol.
[Comparative Example 16]
A polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that an aqueous solution of sodium polyacrylate (Aronbis SX manufactured by Toagosei Co., Ltd.) was applied instead of polyvinyl alcohol.
[Comparative Example 17]
Instead of polyvinyl alcohol, a polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that an aqueous solution of carboxymethyl cellulose (CMC Daicel 1110 manufactured by Daicel Chemical Industries, Ltd.) was applied.
[Comparative Example 18]
A polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that an aqueous solution of hydroxypropylmethylcellulose (60SH-50 manufactured by Shin-Etsu Chemical Co., Ltd.) was applied instead of polyvinyl alcohol.
[Comparative Example 19]
A polystyrene resin sheet was obtained and evaluated in the same manner as in Example 1 except that an emulsion of an alkyl acrylate copolymer (Jurimer ET-410 manufactured by Toagosei Co., Ltd.) was applied instead of polyvinyl alcohol. .
本発明の耐油性ポリスチレン系樹脂シートは、耐油性、耐熱性、剛性に優れ、熱板成形、真空成形などの方法で成形された容器は防曇性に優れ、臭気の問題がなく、耐熱性、耐油性に優れているので、特に電子レンジで加熱する食品の包装容器の用途に好適に用いることができる。
The oil-resistant polystyrene-based resin sheet of the present invention is excellent in oil resistance, heat resistance and rigidity, and the container molded by a method such as hot plate molding and vacuum molding is excellent in anti-fogging property, no odor problem, and heat resistance. Since it is excellent in oil resistance, it can be suitably used particularly for food packaging containers heated in a microwave oven.
Claims (3)
前記耐油性ポリスチレン系樹脂シート中の、ポリスチレン系樹脂がメタクリル酸または無水マレイン酸のいずれか一成分を５〜１５質量％含み、重量平均分子量が１５〜４０万であり、
前記ポリスチレン系樹脂シートが二軸方向に延伸したシートであって、該シートの延伸倍率が１．５〜５．０倍、最大配向緩和応力のピーク温度が１２０〜１５０℃であり、
前記性ポリスチレン系樹脂シートの最大配向緩和応力が０．２〜１．０ＭＰａであり、
前記ポリビニルアルコール塗膜の塗工量が３０〜３０００ｍｇ／ｍ ２ であり、
前記ポリビニルアルコールの、２０℃、４．０質量％での水溶液粘度が１０〜２００ｍＰａ・ｓであり、
前記ポリビニルアルコールの残存酢酸ナトリウム濃度が１．０質量％以下である耐油性ポリスチレン系樹脂シート。 An oil-resistant polystyrene-based resin sheet , wherein a film of polyvinyl alcohol having a polymerization degree of 1500 or more and a saponification degree of 85 mol% or more is formed on one surface of the polystyrene-based resin sheet ,
In the oil-resistant polystyrene resin sheet, the polystyrene resin contains 5 to 15% by mass of any one component of methacrylic acid or maleic anhydride, and the weight average molecular weight is 150 to 400,000.
The polystyrene resin sheet is a sheet stretched in a biaxial direction, the stretching ratio of the sheet is 1.5 to 5.0 times, and the peak temperature of maximum orientation relaxation stress is 120 to 150 ° C.
The maximum orientation relaxation stress of the polystyrene resin sheet is 0.2 to 1.0 MPa,
The coating amount of the polyvinyl alcohol coating film is 30 to 3000 mg / m 2 ,
The polyvinyl alcohol has an aqueous solution viscosity of 10 to 200 mPa · s at 20 ° C. and 4.0% by mass,
An oil-resistant polystyrene-based resin sheet having a residual sodium acetate concentration of the polyvinyl alcohol of 1.0% by mass or less .
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