JP5553983B2 - Styrene-modified polyethylene resin particles and pre-expanded particles obtained from the resin particles - Google Patents
Styrene-modified polyethylene resin particles and pre-expanded particles obtained from the resin particles Download PDFInfo
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- JP5553983B2 JP5553983B2 JP2008262364A JP2008262364A JP5553983B2 JP 5553983 B2 JP5553983 B2 JP 5553983B2 JP 2008262364 A JP2008262364 A JP 2008262364A JP 2008262364 A JP2008262364 A JP 2008262364A JP 5553983 B2 JP5553983 B2 JP 5553983B2
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- Prior art keywords
- styrene
- modified polyethylene
- polyethylene resin
- weight
- particles
- Prior art date
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- 239000002245 particle Substances 0.000 title claims description 217
- 229920013716 polyethylene resin Polymers 0.000 title claims description 201
- 229920005989 resin Polymers 0.000 title claims description 43
- 239000011347 resin Substances 0.000 title claims description 43
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical group C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 74
- 238000006116 polymerization reaction Methods 0.000 claims description 37
- 239000010410 layer Substances 0.000 claims description 25
- 229920005990 polystyrene resin Polymers 0.000 claims description 25
- 239000003431 cross linking reagent Substances 0.000 claims description 21
- 238000000465 moulding Methods 0.000 claims description 20
- 239000002344 surface layer Substances 0.000 claims description 18
- 229920005678 polyethylene based resin Polymers 0.000 claims description 16
- -1 polyethylene Polymers 0.000 claims description 13
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 10
- 239000004698 Polyethylene Substances 0.000 claims description 10
- 229920000573 polyethylene Polymers 0.000 claims description 10
- 239000008096 xylene Substances 0.000 claims description 10
- 239000004793 Polystyrene Substances 0.000 claims description 5
- 229920002223 polystyrene Polymers 0.000 claims description 5
- 239000004088 foaming agent Substances 0.000 description 63
- 238000006243 chemical reaction Methods 0.000 description 26
- 238000004132 cross linking Methods 0.000 description 23
- 238000005187 foaming Methods 0.000 description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 238000000034 method Methods 0.000 description 18
- 229910001868 water Inorganic materials 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 15
- 239000000178 monomer Substances 0.000 description 13
- 238000001816 cooling Methods 0.000 description 11
- 239000002270 dispersing agent Substances 0.000 description 11
- 239000006260 foam Substances 0.000 description 11
- 238000001035 drying Methods 0.000 description 10
- 230000006837 decompression Effects 0.000 description 8
- 239000003505 polymerization initiator Substances 0.000 description 8
- 150000003254 radicals Chemical class 0.000 description 8
- IJDNQMDRQITEOD-UHFFFAOYSA-N sec-butylidene Natural products CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 8
- 239000007900 aqueous suspension Substances 0.000 description 7
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 6
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 6
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910052708 sodium Inorganic materials 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 6
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- 239000004342 Benzoyl peroxide Substances 0.000 description 5
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 5
- 235000019400 benzoyl peroxide Nutrition 0.000 description 5
- 239000001273 butane Substances 0.000 description 5
- 239000001506 calcium phosphate Substances 0.000 description 5
- 239000002612 dispersion medium Substances 0.000 description 5
- 235000019731 tricalcium phosphate Nutrition 0.000 description 5
- 239000004711 α-olefin Substances 0.000 description 5
- 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 4
- 239000005977 Ethylene Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- 239000004014 plasticizer Substances 0.000 description 4
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 4
- 229940078499 tricalcium phosphate Drugs 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- QEQBMZQFDDDTPN-UHFFFAOYSA-N (2-methylpropan-2-yl)oxy benzenecarboperoxoate Chemical compound CC(C)(C)OOOC(=O)C1=CC=CC=C1 QEQBMZQFDDDTPN-UHFFFAOYSA-N 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 239000004604 Blowing Agent Substances 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 239000001282 iso-butane Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 3
- 230000000007 visual effect Effects 0.000 description 3
- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-Divinylbenzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 description 2
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-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
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 2
- 235000019482 Palm oil Nutrition 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000003570 air Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 229920001903 high density polyethylene Polymers 0.000 description 2
- 239000004700 high-density polyethylene Substances 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- CRSOQBOWXPBRES-UHFFFAOYSA-N neopentane Chemical compound CC(C)(C)C CRSOQBOWXPBRES-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- LYRFLYHAGKPMFH-UHFFFAOYSA-N octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(N)=O LYRFLYHAGKPMFH-UHFFFAOYSA-N 0.000 description 2
- 239000002540 palm oil Substances 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 239000000454 talc Substances 0.000 description 2
- 229910052623 talc Inorganic materials 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- VMPHSYLJUKZBJJ-UHFFFAOYSA-N trilaurin Chemical compound CCCCCCCCCCCC(=O)OCC(OC(=O)CCCCCCCCCCC)COC(=O)CCCCCCCCCCC VMPHSYLJUKZBJJ-UHFFFAOYSA-N 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- KDGNCLDCOVTOCS-UHFFFAOYSA-N (2-methylpropan-2-yl)oxy propan-2-yl carbonate Chemical compound CC(C)OC(=O)OOC(C)(C)C KDGNCLDCOVTOCS-UHFFFAOYSA-N 0.000 description 1
- XLYMOEINVGRTEX-ONEGZZNKSA-N (e)-4-ethoxy-4-oxobut-2-enoic acid Chemical compound CCOC(=O)\C=C\C(O)=O XLYMOEINVGRTEX-ONEGZZNKSA-N 0.000 description 1
- LVGUZGTVOIAKKC-UHFFFAOYSA-N 1,1,1,2-tetrafluoroethane Chemical compound FCC(F)(F)F LVGUZGTVOIAKKC-UHFFFAOYSA-N 0.000 description 1
- PYOLJOJPIPCRDP-UHFFFAOYSA-N 1,1,3-trimethylcyclohexane Chemical compound CC1CCCC(C)(C)C1 PYOLJOJPIPCRDP-UHFFFAOYSA-N 0.000 description 1
- HSLFISVKRDQEBY-UHFFFAOYSA-N 1,1-bis(tert-butylperoxy)cyclohexane Chemical compound CC(C)(C)OOC1(OOC(C)(C)C)CCCCC1 HSLFISVKRDQEBY-UHFFFAOYSA-N 0.000 description 1
- NPNPZTNLOVBDOC-UHFFFAOYSA-N 1,1-difluoroethane Chemical compound CC(F)F NPNPZTNLOVBDOC-UHFFFAOYSA-N 0.000 description 1
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- YAJYJWXEWKRTPO-UHFFFAOYSA-N 2,3,3,4,4,5-hexamethylhexane-2-thiol Chemical compound CC(C)C(C)(C)C(C)(C)C(C)(C)S YAJYJWXEWKRTPO-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
- SBYMUDUGTIKLCR-UHFFFAOYSA-N 2-chloroethenylbenzene Chemical compound ClC=CC1=CC=CC=C1 SBYMUDUGTIKLCR-UHFFFAOYSA-N 0.000 description 1
- DXIJHCSGLOHNES-UHFFFAOYSA-N 3,3-dimethylbut-1-enylbenzene Chemical compound CC(C)(C)C=CC1=CC=CC=C1 DXIJHCSGLOHNES-UHFFFAOYSA-N 0.000 description 1
- JLBJTVDPSNHSKJ-UHFFFAOYSA-N 4-Methylstyrene Chemical compound CC1=CC=C(C=C)C=C1 JLBJTVDPSNHSKJ-UHFFFAOYSA-N 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- PYGXAGIECVVIOZ-UHFFFAOYSA-N Dibutyl decanedioate Chemical compound CCCCOC(=O)CCCCCCCCC(=O)OCCCC PYGXAGIECVVIOZ-UHFFFAOYSA-N 0.000 description 1
- YIVJZNGAASQVEM-UHFFFAOYSA-N Lauroyl peroxide Chemical compound CCCCCCCCCCCC(=O)OOC(=O)CCCCCCCCCCC YIVJZNGAASQVEM-UHFFFAOYSA-N 0.000 description 1
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- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
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- 229910000831 Steel Inorganic materials 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 125000005396 acrylic acid ester group Chemical group 0.000 description 1
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- 238000004378 air conditioning Methods 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
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- 239000003945 anionic surfactant Substances 0.000 description 1
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- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- VBICKXHEKHSIBG-UHFFFAOYSA-N beta-monoglyceryl stearate Natural products CCCCCCCCCCCCCCCCCC(=O)OCC(O)CO VBICKXHEKHSIBG-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- ZFMQKOWCDKKBIF-UHFFFAOYSA-N bis(3,5-difluorophenyl)phosphane Chemical compound FC1=CC(F)=CC(PC=2C=C(F)C=C(F)C=2)=C1 ZFMQKOWCDKKBIF-UHFFFAOYSA-N 0.000 description 1
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- 235000011010 calcium phosphates Nutrition 0.000 description 1
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- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
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- XYJRXVWERLGGKC-UHFFFAOYSA-D pentacalcium;hydroxide;triphosphate Chemical compound [OH-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O XYJRXVWERLGGKC-UHFFFAOYSA-D 0.000 description 1
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- FZYCEURIEDTWNS-UHFFFAOYSA-N prop-1-en-2-ylbenzene Chemical compound CC(=C)C1=CC=CC=C1.CC(=C)C1=CC=CC=C1 FZYCEURIEDTWNS-UHFFFAOYSA-N 0.000 description 1
- SCUZVMOVTVSBLE-UHFFFAOYSA-N prop-2-enenitrile;styrene Chemical compound C=CC#N.C=CC1=CC=CC=C1 SCUZVMOVTVSBLE-UHFFFAOYSA-N 0.000 description 1
- 239000001294 propane Substances 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
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
- 229940037312 stearamide Drugs 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 150000003440 styrenes Chemical class 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- OPQYOFWUFGEMRZ-UHFFFAOYSA-N tert-butyl 2,2-dimethylpropaneperoxoate Chemical compound CC(C)(C)OOC(=O)C(C)(C)C OPQYOFWUFGEMRZ-UHFFFAOYSA-N 0.000 description 1
- SWAXTRYEYUTSAP-UHFFFAOYSA-N tert-butyl ethaneperoxoate Chemical compound CC(=O)OOC(C)(C)C SWAXTRYEYUTSAP-UHFFFAOYSA-N 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- PVNIQBQSYATKKL-UHFFFAOYSA-N tripalmitin Chemical compound CCCCCCCCCCCCCCCC(=O)OCC(OC(=O)CCCCCCCCCCCCCCC)COC(=O)CCCCCCCCCCCCCCC PVNIQBQSYATKKL-UHFFFAOYSA-N 0.000 description 1
- DCXXMTOCNZCJGO-UHFFFAOYSA-N tristearoylglycerol Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCC(OC(=O)CCCCCCCCCCCCCCCCC)COC(=O)CCCCCCCCCCCCCCCCC DCXXMTOCNZCJGO-UHFFFAOYSA-N 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Landscapes
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Polymerisation Methods In General (AREA)
- Graft Or Block Polymers (AREA)
Description
本発明は、耐割れ性、成形加工性の優れたスチレン改質ポリエチレン系樹脂粒子および該樹脂粒子より得られる予備発泡粒子および発泡成形体に関する。 The present invention relates to a styrene-modified polyethylene resin particle having excellent crack resistance and molding processability, pre-foamed particles obtained from the resin particles, and a foam-molded article.
ポリオレフィン系樹脂の発泡体は一般に弾性が高く、繰り返しの応力に対しても歪の回復力が大きいという特徴の他に、耐油性、耐割れ性に優れることから、包装資材として広く利用されている。しかし、剛性が低く、型内成形後の発泡成形体の収縮がおこりやすく、圧縮強度が低いという短所を有している。 Polyolefin resin foams are generally widely used as packaging materials because of their high elasticity and excellent strain resistance against repeated stresses, as well as excellent oil resistance and crack resistance. . However, it has disadvantages of low rigidity, easy shrinkage of the foamed molded product after in-mold molding, and low compressive strength.
このような欠点を改良する方法として、ポリエチレン系樹脂にスチレン系単量体を含浸させて重合を行った、スチレン改質ポリエチレン樹脂が知られている。 As a method for improving such a defect, a styrene-modified polyethylene resin is known in which a polyethylene resin is impregnated with a styrene monomer and polymerized.
例えば、特許文献１では、繰り返し圧縮に耐え、衝撃によっても破壊しない耐衝撃強度特性を維持し、しかも剛性を改良した耐熱性に優れた発泡成形体を提供することを目的として、特定のゲル分率を有する架橋化高密度ポリエチレン系樹脂粒子を用いて得られる改質ポリエチレン系樹脂粒子が開示されている。 For example, in Patent Document 1, for the purpose of providing a foamed molded article excellent in heat resistance that can withstand repeated compression and maintains impact resistance strength that does not break even by impact, and has improved rigidity, a specific gel component is provided. Modified polyethylene-based resin particles obtained by using crosslinked high-density polyethylene-based resin particles having a rate are disclosed.
また、特許文献２では、重合時のモノマーの追加方法、攪拌所要動力を制御することによって樹脂表面をオレフィンリッチにし、スチレン改質ポリエチレン系樹脂の耐衝撃性や耐薬品性を高める方法が記載されている。 Patent Document 2 describes a method for adding a monomer during polymerization and a method for increasing the impact resistance and chemical resistance of a styrene-modified polyethylene resin by controlling the power required for stirring to make the resin surface rich in olefin. ing.
特許文献３では、樹脂表面から少なくとも５μｍで０．８μｍ以下のスチレン系樹脂粒子が分散された状態とすることで、耐薬品性に優れたスチレン改質ポリエチレン系樹脂を得られることが示されている。 Patent Document 3 shows that a styrene-modified polyethylene resin having excellent chemical resistance can be obtained by dispersing styrene-based resin particles of at least 5 μm and 0.8 μm or less from the resin surface. Yes.
以上のように、スチレン改質ポリエチレン発泡体において、耐割れ性、耐薬品性を向上させる報告は多くなされており、樹脂粒子表層部の形態の重要性についても報告されている。また、特許文献４には、耐割れ性、成形加工性を両立するためのゲル量、分子量範囲に関する記載があり、優れた成形加工性を有する予備発泡粒子が得られている。 As described above, in the styrene-modified polyethylene foam, many reports on improving crack resistance and chemical resistance have been made, and the importance of the form of the resin particle surface layer has been reported. Further, Patent Document 4 describes a gel amount and a molecular weight range for achieving both crack resistance and molding processability, and pre-expanded particles having excellent molding processability are obtained.
一方、スチレン改質ポリエチレン発泡成形体の原料は、予備発泡粒子の形態でモルダーまで運ばれ、成形に供されるが、通常、日を経る毎に予備発泡粒子中の発泡剤は逸散していく。それゆえ、予備発泡粒子中の発泡剤の逸散が少ない予備発泡粒子、或いは、予備発泡粒子の発泡剤がある程度逸散しても優れた成形加工性を有するスチレン改質ポリエチレン系樹脂予備発泡粒子が望まれていた。
以上のような状況に鑑み、本発明は、予備発泡粒子の発泡剤逸散後においても成形加工時の表面伸びに優れ、得られた発泡成形体が高い耐割れ性を有する、スチレン改質ポリエチレン系樹脂粒子を提供することにある。 In view of the above situation, the present invention is a styrene-modified polyethylene having excellent surface elongation at the time of molding processing even after the foaming agent escapes from the pre-foamed particles, and the obtained foamed molded article has high crack resistance. It is to provide a resin particle.
ポリエチレン系樹脂１００重量部に対してスチレン系単量体を１５０重量部以上３００重量部以下含浸させる際、ポリエチレン系樹脂粒子１００重量部に対し、スチレン系単量体２５重量部以上１００重量部以下を本質的に重合が進まない温度下で添加して含浸させ、残りのスチレン系単量体を加熱下で添加し、重合を行い、かつ、重合中、或いは、重合後に、１０時間半減期温度が１００℃以上１２５℃以下である架橋剤を添加し、１３０℃以上１５０℃以下で５０％以上の架橋剤が分解されることによって得られる改質ポリエチレン系樹脂において、スチレン改質ポリエチレン系樹脂粒子中央部が層の平均厚みが０．３μｍ以上１．０μｍ以下であるポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成し、かつ、その共連続構造のポリエチレン系樹脂の比率が３０％以上であり、さらに、該スチレン改質ポリエチレン系樹脂粒子から得られるスチレン改質ポリエチレン系樹脂予備発泡粒子のキシレン不溶のゲル成分が１０重量％以上３５重量％以下であるスチレン改質ポリエチレン系樹脂粒子を用いることで、予備発泡した後、経日でスチレン改質ポリエチレン系樹脂予備発泡粒子内の発泡剤が逸散した後も成形加工性に優れ、かつ耐割れ性が優れた発泡体を得ることができるスチレン改質ポリエチレン系樹脂予備発泡粒子が得られることを見出し本発明の完成に至った。
Styrene when the monomer Ru impregnated 300 parts hereinafter more than 150 parts by weight, per 100 parts by weight of polyethylene-based resin particles, styrene monomer 25 parts by weight or more to 100 weight per 100 parts by weight of polyethylene resin The amount below 10 parts is added and impregnated at a temperature at which the polymerization does not proceed substantially, and the remaining styrenic monomer is added under heating to conduct the polymerization, and during the polymerization, or after the polymerization, halved for 10 hours A modified polyethylene resin obtained by adding a crosslinking agent having an initial temperature of 100 ° C. or more and 125 ° C. or less and decomposing 50% or more of the crosslinking agent at 130 ° C. or more and 150 ° C. or less. The central part of the resin particle forms a co-continuous structure of polyethylene resin and polystyrene resin having an average layer thickness of 0.3 μm or more and 1.0 μm or less, and the co-continuous structure The ratio of the polyethylene resin is 30% or more, and the xylene-insoluble gel component of the styrene-modified polyethylene resin pre-expanded particles obtained from the styrene-modified polyethylene resin particles is 10% by weight to 35% by weight. By using styrene-modified polyethylene resin particles that are pre-foamed, after the foaming agent in the styrene-modified polyethylene resin pre-foamed particles dissipates over time, it has excellent moldability and is resistant to cracking. As a result, it was found that styrene-modified polyethylene resin pre-expanded particles capable of obtaining a foam having excellent properties were obtained, and the present invention was completed.
すなわち、本発明の第１は、
ポリエチレン系樹脂１００重量部に対してスチレン系単量体が１５０重量部以上３００重量部以下を含浸させる際、
ポリエチレン系樹脂粒子１００重量部に対し、スチレン系単量体２５重量部以上１００重量部以下を本質的に重合が進まない温度下で添加して含浸させ、残りのスチレン系単量体を加熱下で添加し、重合を行い、かつ、
重合中、或いは、重合後に、１０時間半減期温度が１００℃以上１２５℃以下である架橋剤を添加し、１３０℃以上１５０℃以下で５０％以上の架橋剤が分解されることによって得られるスチレン改質ポリエチレン系樹脂粒子において、
該スチレン改質ポリエチレン系樹脂粒子中央部が、層の平均厚みが０．３μｍ以上１．０μｍ以下であるポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成し、かつ、該中央部共連続構造のポリエチレン系樹脂の比率が３０％以上であり、
さらに、該スチレン改質ポリエチレン系樹脂粒子から得られるスチレン改質ポリエチレン系樹脂予備発泡粒子のキシレン不溶のゲル成分が１０重量％以上３５重量％以下である、スチレン改質ポリエチレン系樹脂粒子に関する。
That is, the first of the present invention is
When the styrene monomer is Ru impregnated with 300 parts by weight to 150 parts by weight per 100 parts by weight of polyethylene resin,
To 100 parts by weight of polyethylene resin particles, 25 parts by weight or more and 100 parts by weight or less of styrene monomer are added and impregnated at a temperature at which polymerization does not proceed substantially, and the remaining styrene monomer is heated. Added to perform polymerization, and
Styrene obtained by adding a crosslinking agent having a 10-hour half-life temperature of 100 ° C. or more and 125 ° C. or less during or after polymerization, and decomposing 50% or more of the crosslinking agent at 130 ° C. or more and 150 ° C. or less. In the modified polyethylene resin particles,
The central part of the styrene-modified polyethylene resin particles forms a co-continuous structure of a polyethylene resin and a polystyrene resin having an average layer thickness of 0.3 μm or more and 1.0 μm or less, and the central part co-continuous structure The ratio of polyethylene resin is 30% or more,
Furthermore, the gel component of the xylene insoluble styrene-modified polyethylene-based resin pre-expanded particles obtained from the styrene-modified polyethylene-based resin particles is 35 wt% or less 10 wt% or more, about styrene-modified polyethylene-based resin particles.
好ましい態様としては、
（１）スチレン改質ポリエチレン系樹脂粒子の表面から深さ５μｍ以内の表層部において、直径１．０μｍ以下の球状のポリスチレン系樹脂がポリエチレン系樹脂に分散している、
前記記載のスチレン改質ポリエチレン系樹脂粒子に関する。
As a preferred embodiment,
(1) In the surface layer portion having a depth of 5 μm or less from the surface of the styrene-modified polyethylene resin particles, a spherical polystyrene resin having a diameter of 1.0 μm or less is dispersed in the polyethylene resin .
The present invention relates to the styrene-modified polyethylene resin particles described above.
本発明の第２は、前記記載のスチレン改質ポリエチレン系樹脂粒子を予備発泡してなるスチレン改質ポリエチレン系樹脂予備発泡粒子に関し、本発明の第３は、前記記載のスチレン改質ポリエチレン系樹脂予備発泡粒子を成形してなる発泡成形体に関する。 The second aspect of the present invention relates to styrene-modified polyethylene resin pre-foamed particles obtained by pre-foaming the styrene-modified polyethylene resin particles described above, and the third aspect of the present invention is the styrene-modified polyethylene resin described above. The present invention relates to a foamed molded article obtained by molding pre-expanded particles.
本発明のスチレン改質ポリエチレン系樹脂粒子は、予備発泡してスチレン改質ポリエチレン系樹脂予備発泡粒子とした際、スチレン改質ポリエチレン系樹脂予備発泡粒子の発泡剤逸散後であっても成形加工性に優れている。その為、ビーズライフが延長され、工業的に有利である。 When the styrene-modified polyethylene resin particles of the present invention are pre-foamed into styrene-modified polyethylene resin pre-foamed particles, the molding process is performed even after the blowing agent escapes from the styrene-modified polyethylene resin pre-foamed particles. Excellent in properties. Therefore, the bead life is extended, which is industrially advantageous.
また、本発明のスチレン改質ポリエチレン系樹脂予備発泡粒子から得られた発泡成形体は高い耐割れ性を示す。 Moreover, the foaming molding obtained from the styrene modified polyethylene resin pre-expanded particles of the present invention exhibits high crack resistance.
本発明の、スチレン改質ポリエチレン系樹脂粒子は、ポリエチレン系樹脂１００重量部に対してスチレン系単量体が１５０重量部以上３００重量部以下使用されるスチレン改質ポリエチレン系樹脂粒子であり、スチレン改質ポリエチレン系樹脂粒子中央部が層の平均厚みが０．３μｍ以上１．０μｍ以下であるポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成し、かつ、該中央部共連続構造のポリエチレン系樹脂の比率が３０％以上であり、さらに、該スチレン改質ポリエチレン系樹脂粒子から得られるスチレン改質ポリエチレン系樹脂予備発泡粒子のキシレン不溶のゲル成分が１０重量％以上３５重量％以下である。 The styrene-modified polyethylene resin particles of the present invention are styrene-modified polyethylene resin particles in which a styrene monomer is used in an amount of 150 to 300 parts by weight based on 100 parts by weight of a polyethylene resin. The central part of the modified polyethylene resin particles forms a co-continuous structure of a polyethylene resin and a polystyrene resin having an average layer thickness of 0.3 μm or more and 1.0 μm or less, and the polyethylene part of the center part co-continuous structure The resin ratio is 30% or more, and the xylene-insoluble gel component of the styrene-modified polyethylene resin pre-expanded particles obtained from the styrene-modified polyethylene resin particles is 10% by weight or more and 35% by weight or less.
本発明においては、ポリエチレン系樹脂１００重量部に対して、スチレン系単量体を１５０重量部以上３００重量部以下、好ましくは１８０重量部以上２５０重量部以下重合させる。当該範囲内であればスチレン改質ポリエチレン系予備発泡粒子としたときに成形加工性と得られる発泡成形体の耐割れ性良好なスチレン改質ポリエチレン系樹脂粒子が得られる。 In the present invention, 150 parts by weight or more and 300 parts by weight or less, preferably 180 parts by weight or more and 250 parts by weight or less of the styrene monomer is polymerized with respect to 100 parts by weight of the polyethylene resin. Within this range, styrene-modified polyethylene resin particles having good moldability and good crack resistance of the resulting foamed molded article when obtained as styrene-modified polyethylene pre-expanded particles can be obtained.
本発明において、ポリエチレン系樹脂にスチレン系単量体を含浸させ重合させる方法としては、攪拌機を具備した容器内に、粒子形状に加工されたポリエチレン系樹脂粒子を含む水性懸濁液を仕込み、スチレン系単量体を連続的にまたは断続的に添加することにより、ポリエチレン系樹脂粒子にスチレン系単量体を含浸させ、重合させる。重合において、添加するスチレン系単量体の添加速度を任意に選択することで、スチレン改質ポリエチレン系樹脂粒子の重量平均分子量に調整することが可能である。 In the present invention, as a method of polymerizing a polyethylene resin by impregnating a styrene monomer, an aqueous suspension containing polyethylene resin particles processed into a particle shape is charged into a container equipped with a stirrer, and styrene is used. By continuously or intermittently adding the system monomer, the polyethylene resin particles are impregnated with the styrene monomer and polymerized. In the polymerization, it is possible to adjust the weight average molecular weight of the styrene-modified polyethylene resin particles by arbitrarily selecting the addition rate of the styrene monomer to be added.
本発明において重合に際し、好ましい態様としては、ポリエチレン系樹脂粒子１００重量部に対し、スチレン系単量体２５重量部以上１００重量部以下を本質的に重合が進まない温度下で添加して含浸させ、残りのスチレン系単量体を加熱下で添加することである。「本質的に重合が進まない温度下」とは、使用する重合開始剤の１０時間半減期温度以下の温度であることを言う。重合に際し、添加するスチレン系単量体の一部を本質的に重合が進まない温度下で添加、含浸させることにより、重合場であるポリエチレン系樹脂粒子の粘度を変化させることができるため、スチレン改質ポリエチレン系樹脂予備発泡粒子のゲル成分量及び重量平均分子量を調整し易い。 In the polymerization in the present invention, as a preferred embodiment, 25 parts by weight or more and 100 parts by weight or less of a styrene monomer are added and impregnated with 100 parts by weight of polyethylene resin particles at a temperature at which the polymerization does not proceed substantially. The remaining styrenic monomer is added under heating. “Under the temperature at which the polymerization does not proceed essentially” means a temperature not higher than the 10-hour half-life temperature of the polymerization initiator used. In the polymerization, by adding and impregnating a part of the styrene monomer to be added at a temperature at which the polymerization does not proceed essentially, the viscosity of the polyethylene resin particles as the polymerization site can be changed. It is easy to adjust the gel component amount and the weight average molecular weight of the modified polyethylene resin pre-expanded particles.
本発明で使用するポリエチレン系樹脂は、高密度ポリエチレン、低密度ポリエチレン等のエチレンの単独重合体、エチレンと、例えば、プロピレン、１−ブテン、１−ペンテン、１−ヘキセン等のα−オレフィンや酢酸ビニル、アクリル酸エステル、塩化ビニル等との共重合体があげられる。これらの中でもエチレンと酢酸ビニルの共重合体が好ましい。更に好ましくは、メルトフローレート（以下、ＭＦＲと表記する場合がある）が１．５ｇ／１０分以下で酢酸ビニル含有量が１０重量％以下であるエチレン・酢酸ビニル共重合体である。ＭＦＲが１．５ｇ／１０分を超えては耐割れ性の発現が難しくなる傾向がある。酢酸ビニル含有量が１０重量％を超えては融点が低いため、重合時に樹脂変形を起こしやすい傾向がある。なお、メルトフローレートはＪＩＳ Ｋ ６９２４に準拠して測定した値である。 The polyethylene resin used in the present invention is a homopolymer of ethylene such as high density polyethylene and low density polyethylene, ethylene, and α-olefin such as propylene, 1-butene, 1-pentene, 1-hexene, and acetic acid. Examples thereof include copolymers with vinyl, acrylic acid ester, vinyl chloride and the like. Among these, a copolymer of ethylene and vinyl acetate is preferable. More preferred is an ethylene / vinyl acetate copolymer having a melt flow rate (hereinafter sometimes referred to as MFR) of 1.5 g / 10 min or less and a vinyl acetate content of 10 wt% or less. If the MFR exceeds 1.5 g / 10 min, the development of crack resistance tends to be difficult. If the vinyl acetate content exceeds 10% by weight, the melting point is low, so that the resin tends to be deformed during polymerization. The melt flow rate is a value measured according to JIS K 6924.
前記ポリエチレン系樹脂は、あらかじめ、例えば押出し機、ニーダー、バンバリーミキサー、ロール等を用いて溶融することによりポリエチレン系樹脂粒子となす。形状はパウダー、ペレット状等の粒子形状であることが好ましい。これらポリエチレン系樹脂粒子の平均粒重量は０．１ｍｇ／粒以上３ｍｇ／粒以下が好適な範囲である。０．１ｍｇ／粒より小さい場合は発泡剤の逸散が激しく高倍率化させにくくなる場合があり、３ｍｇ／粒より大きい場合は成形時の充填性が悪くなる恐れがある。 The polyethylene resin is made into polyethylene resin particles by melting in advance using, for example, an extruder, a kneader, a Banbury mixer, a roll or the like. The shape is preferably a particle shape such as powder or pellet. The average particle weight of these polyethylene resin particles is preferably in the range of 0.1 mg / particle to 3 mg / particle. If it is less than 0.1 mg / grain, the foaming agent may dissipate rapidly, making it difficult to increase the magnification. If it is greater than 3 mg / grain, the filling property during molding may be deteriorated.
本発明のスチレン改質ポリエチレン系樹脂粒子には、必要に応じて各種添加剤を使用することができる。各種添加剤としては、目的に応じて可塑剤、気泡調整剤等が挙げられる。可塑剤としては、例えば、ステアリン酸トリグリセライド、パルミチン酸トリグリセライド、ラウリン酸トリグリセライド、ステアリン酸ジグリセライド、ステアリン酸モノグリセライド等の脂肪酸グリセライド、ヤシ油、パーム油、パーム核油等の植物油、ジオクチルアジペート、ジブチルセバケート等の脂肪族エステル、流動パラフィン、シクロヘキサン等の有機炭化水素、トルエン、エチルベンゼン等の有機芳香族炭化水素等があげられ、これらは併用しても何ら差し支えない。 Various additives can be used in the styrene-modified polyethylene resin particles of the present invention as needed. Examples of the various additives include a plasticizer and a bubble regulator according to the purpose. Examples of the plasticizer include stearic acid triglyceride, palmitic acid triglyceride, lauric acid triglyceride, stearic acid diglyceride, stearic acid monoglyceride and other fatty acid glycerides, palm oil, palm oil, palm kernel oil and other vegetable oils, dioctyl adipate, dibutyl sebacate And the like, organic hydrocarbons such as liquid paraffin and cyclohexane, and organic aromatic hydrocarbons such as toluene and ethylbenzene. These may be used in combination.
気泡調整剤としては、例えば、メチレンビスステアリン酸アマイド、エチレンビスステアリン酸アマイド等の脂肪族ビスアマイドやステアリン酸アミド等の有機系気泡調整剤、タルク、シリカ、珪酸カルシウム、炭酸カルシウム等の無機系気泡調整剤等があげられる。また、これらの各種添加剤は重合時、発泡剤含浸時のみならず、あらかじめ前記ポリエチレン系樹脂粒子に混ぜ込むことで使用することもできる。 Examples of the foam regulator include organic foam regulators such as aliphatic bisamides and stearamide such as methylene bis stearic acid amide and ethylene bis stearic acid amide, inorganic foams such as talc, silica, calcium silicate, and calcium carbonate. Examples thereof include regulators. These various additives can be used not only at the time of polymerization and at the time of impregnation with a foaming agent, but also by previously mixing with the polyethylene resin particles.
特に、後に示す除圧発泡を行う場合、無機系気泡調整剤を使用することが好ましく、好ましい使用量としてはポリエチレン系樹脂１００重量部に対し、０．０１重量部以上０．５重量部以下である。無機系気泡調整剤が０．０１重量部より少ないと安定的に気泡を生成することが困難となり、０．５重量部より多く使用した場合は成形時の融着が悪化する傾向がある。 In particular, in the case of performing the decompression foaming described later, it is preferable to use an inorganic cell regulator, and the preferable usage amount is 0.01 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the polyethylene resin. is there. When the amount of the inorganic air-conditioning agent is less than 0.01 parts by weight, it is difficult to stably generate bubbles, and when the amount is more than 0.5 parts by weight, the fusion during molding tends to deteriorate.
本発明に使用するスチレン系単量体としては、スチレン、およびα−メチルスチレン、パラメチルスチレン、ｔ−ブチルスチレン、クロルスチレン等のスチレン系誘導体を主成分として使用することができる。また、スチレン系単量体と共重合が可能な成分、例えば、メチルアクリレート、ブチルアクリレート、メチルメタクリレート、エチルメタクリレート等のアクリル酸およびメタクリル酸のエステル、あるいはアクリロニトリル、ジメチルフマレート、エチルフマレート等が挙げられ、これら各種単量体を１種または２種以上併用してもよい。更に、ジビニルベンゼン、アルキレングリコールジメタクリレート等の多官能性単量体を使用することもできる。 As the styrene monomer used in the present invention, styrene and styrene derivatives such as α-methyl styrene, paramethyl styrene, t-butyl styrene and chlorostyrene can be used as main components. In addition, components capable of copolymerization with styrene monomers, for example, acrylic acid and methacrylic acid esters such as methyl acrylate, butyl acrylate, methyl methacrylate, and ethyl methacrylate, or acrylonitrile, dimethyl fumarate, ethyl fumarate, etc. These various monomers may be used alone or in combination of two or more. Furthermore, polyfunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate can also be used.
本発明において使用する重合開始剤としては、一般に熱可塑性重合体の製造に用いられるラジカル発生型重合開始剤を用いることができ、代表的なものとしては、例えば、過酸化ベンゾイル、ｔ−ブチルパーオキシ−２−エチルヘキサノエート、ラウロイルパーオキサイド、ｔ−ブチルパーピバレート、ｔ−ブチルパーオキシイソプロピルカーボネート、ジ−ｔ−ブチルパーオキシヘキサハイドロテレフタレート、１，１−ジ（ｔ−ブチルパーオキシ）３，３，５−トリメチルシクロヘキサン、１，１−ジ（ｔ−ブチルパーオキシ）シクロヘキサンなどの有機過酸化物や、アゾビスイソブチロニトリル、アゾビスジメチルバレロニトリルなどのアゾ化合物が挙げられる。これらの重合開始剤は単独もしくは２種以上を混合して用いることができる。重量平均分子量は重合開始剤の量と反応温度により調整できる。 As the polymerization initiator used in the present invention, radical generating polymerization initiators generally used for the production of thermoplastic polymers can be used. Typical examples thereof include benzoyl peroxide and t-butyl peroxide. Oxy-2-ethylhexanoate, lauroyl peroxide, t-butyl perpivalate, t-butyl peroxyisopropyl carbonate, di-t-butyl peroxyhexahydroterephthalate, 1,1-di (t-butylperoxy ) Organic peroxides such as 3,3,5-trimethylcyclohexane and 1,1-di (t-butylperoxy) cyclohexane, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. . These polymerization initiators can be used alone or in admixture of two or more. The weight average molecular weight can be adjusted by the amount of the polymerization initiator and the reaction temperature.
これら重合開始剤の使用量は、スチレン系単量体１００重量部に対して０．０５重量部以上１．０重量部以下であることが好ましく、さらには０．１重量部以上０．５重量部以下であることが好ましい。 The amount of the polymerization initiator used is preferably 0.05 parts by weight or more and 1.0 parts by weight or less, more preferably 0.1 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the styrene monomer. Part or less.
重合温度は７０℃以上９０℃以下であると所望の重量平均分子量であるスチレン改質ポリエチレン系樹脂予備発泡粒子が得られるため、好ましい。 A polymerization temperature of 70 ° C. or higher and 90 ° C. or lower is preferable because styrene-modified polyethylene resin pre-expanded particles having a desired weight average molecular weight can be obtained.
本発明における前記重合においては、更に、ｎ−オクチルメルカプタン、ｎ−ドデシルメルカプタン、ｔ−ドデシルメルカプタン等メルカプタン系の連鎖移動剤やアクリロニトリル−スチレン系樹脂の重合に一般的に用いられるα−メチルスチレンダイマー等を併用しても良い。 In the polymerization according to the present invention, α-methylstyrene dimer generally used for polymerization of mercaptan chain transfer agents such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan and acrylonitrile-styrene resin. Etc. may be used in combination.
本発明においては、ポリエチレン系樹脂粒子を含む水性懸濁液中にて重合を行うが、その際樹脂粒子同士の融着を防止するために分散剤を使用することが好ましい。使用できる分散剤としては、一般的に懸濁重合に用いられる分散剤、例えば、ポリビニルアルコール、ポリビニルピロリドン、ポリアクリルアミド等の高分子分散剤、例えば、リン酸カルシウム、ハイドロキシアパタイト、ピロリン酸マグネシウム、カオリン等の難水溶性無機塩があげられる。 In the present invention, the polymerization is carried out in an aqueous suspension containing polyethylene resin particles. In this case, it is preferable to use a dispersant in order to prevent fusion between the resin particles. Examples of the dispersant that can be used include dispersants generally used for suspension polymerization, for example, polymer dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylamide, such as calcium phosphate, hydroxyapatite, magnesium pyrophosphate, and kaolin. Examples include poorly water-soluble inorganic salts.
また、難水溶性無機塩を用いる場合には、α−オレフィンスルフォン酸ソーダ、ドデシルベンゼンスルフォン酸ソーダ等のアニオン性界面活性剤を併用すると分散安定性が増すので効果的であるため好ましい。また、これらの分散剤は重合中に追加しても良い。分散剤の使用量は種類によるが基本的に水１００重量部に対して０．２重量部以上１０重量部以下が好ましい。 In addition, when a poorly water-soluble inorganic salt is used, it is preferable to use an anionic surfactant such as α-olefin sodium sulfonate or sodium dodecylbenzene sulfonate because the dispersion stability is increased, which is effective. These dispersants may be added during the polymerization. The amount of the dispersant used is preferably 0.2 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of water although it depends on the type.
本発明の「水性懸濁液」とは樹脂と単量体液滴を攪拌等により水または水溶液に分散させた状態を指し、水中には水溶性の界面活性剤や単量体が溶解していても良く、また水に不溶の分散剤、開始剤、架橋剤、気泡調整剤、難燃剤、可塑剤等がともに分散していても良い。得られるスチレン改質ポリエチレン系樹脂と水の重量比は、樹脂／水で１．０／０．６から１．０／４．０が好ましい。 The “aqueous suspension” of the present invention refers to a state in which resin and monomer droplets are dispersed in water or an aqueous solution by stirring or the like, and a water-soluble surfactant or monomer is dissolved in water. In addition, a water-insoluble dispersant, an initiator, a crosslinking agent, a bubble regulator, a flame retardant, a plasticizer, and the like may be dispersed together. The weight ratio of the obtained styrene-modified polyethylene resin and water is preferably 1.0 / 0.6 to 1.0 / 4.0 in terms of resin / water.
本発明においては、スチレン改質ポリエチレン系樹脂予備発泡粒子中のゲル成分を有していることが必要であり、そのためラジカル種発生型架橋剤を使用することが好ましい。架橋反応は１０時間半減期温度が１００℃以上１２５℃以下の架橋剤を使用するのが好ましい。１０時間半減期温度が１００℃より低いラジカル種発生型架橋剤を使用すると重合時に架橋反応が進行しすぎてしまい、１３０℃以上で架橋反応する時間が短くなる傾向がある。１０時間半減期温度が１２５℃を超えると、１３０℃以上１５０℃以下の温度で架橋反応を進行させるのに時間がかかり過ぎる場合がある。１０時間半減期温度が１００℃以上１２５℃以下であるラジカル種発生型架橋剤としては、ジ−ｔ−ブチルパーオキサイド（１０時間半減期温度：１２３℃）、ジクミルパーオキサイド（１０時間半減期温度：１１６℃）、ｔ−ブチルパーオキシベンゾエ−ト（１０時間半減期温度：１０４℃）、ｔ−ブチルパーオキシアセテート（１０時間半減期温度：１０２℃）、２，２−ビス−ｔ−ブチルパーオキシブタン（１０時間半減期温度：１０３℃）等が挙げられる。これらは、スチレン系単量体の添加前あるいはスチレン系単量体と共に重合系に添加してもよいし、除圧発泡の仕込み時に追加しても良い。 In the present invention, it is necessary to have a gel component in the styrene-modified polyethylene resin pre-expanded particles, and therefore it is preferable to use a radical species-generating crosslinking agent. In the crosslinking reaction, it is preferable to use a crosslinking agent having a 10-hour half-life temperature of 100 ° C. or more and 125 ° C. or less. When a radical species-generating crosslinking agent having a 10-hour half-life temperature lower than 100 ° C. is used, the crosslinking reaction proceeds excessively during polymerization, and the crosslinking reaction time tends to be shortened at 130 ° C. or higher. If the 10-hour half-life temperature exceeds 125 ° C, it may take too much time for the crosslinking reaction to proceed at a temperature of 130 ° C or higher and 150 ° C or lower. Examples of the radical species-generating crosslinking agent having a 10-hour half-life temperature of 100 ° C. or more and 125 ° C. or less include di-t-butyl peroxide (10-hour half-life temperature: 123 ° C.), dicumyl peroxide (10-hour half-life). Temperature: 116 ° C.), t-butyl peroxybenzoate (10-hour half-life temperature: 104 ° C.), t-butyl peroxyacetate (10-hour half-life temperature: 102 ° C.), 2,2-bis-t -Butyl peroxybutane (10-hour half-life temperature: 103 degreeC) etc. are mentioned. These may be added to the polymerization system before the addition of the styrenic monomer or together with the styrenic monomer, or may be added at the time of preparation for decompression foaming.
１０時間半減期温度が１００℃以上１２５℃以下の架橋剤を用いた架橋反応としては１３０℃以上１５０℃以下で５０％以上の架橋剤が分解されることが好ましい。架橋剤が分解される主たる要因は、架橋反応が進行することによるものであることから、５０％以上の架橋剤が分解されるということは、架橋反応の５０％以上が進行していると概ね同義である。架橋反応が１３０℃未満であるとスチレン改質ポリエチレン系樹脂粒子中央部の、層の平均厚みが０．３μｍ以上１．０μｍ以下である共連続構造を得ることが難しく、成形加工性が悪化する傾向がある。架橋反応が１５０℃を超えると樹脂が軟化しすぎ、スチレン改質ポリエチレン系樹脂粒子が凝集しやすくなる傾向にある。 As a crosslinking reaction using a crosslinking agent having a 10-hour half-life temperature of 100 ° C. or more and 125 ° C. or less, 50% or more of the crosslinking agent is preferably decomposed at 130 ° C. or more and 150 ° C. or less. Since the main factor for the decomposition of the crosslinking agent is due to the progress of the crosslinking reaction, the decomposition of 50% or more of the crosslinking agent generally means that 50% or more of the crosslinking reaction has progressed. It is synonymous. When the cross-linking reaction is less than 130 ° C., it is difficult to obtain a co-continuous structure having an average layer thickness of 0.3 μm or more and 1.0 μm or less at the center of the styrene-modified polyethylene resin particles, and the moldability deteriorates. Tend. When the crosslinking reaction exceeds 150 ° C., the resin is too soft and the styrene-modified polyethylene resin particles tend to aggregate.
架橋反応は、重合中、或いは、重合終了後、水性懸濁液の温度を架橋反応温度まで上昇させて行っても良いし、後述する予備発泡時に架橋反応を行っても良い。 The cross-linking reaction may be performed during the polymerization or after completion of the polymerization by raising the temperature of the aqueous suspension to the cross-linking reaction temperature, or may be performed at the time of preliminary foaming described later.
本発明におけるスチレン改質ポリエチレン系樹脂粒子中央部の構造は、層の平均厚みが０．３μｍ以上１．０μｍ以下であるポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成している。好ましくは層の平均厚みが０．３５μｍ以上０．９μｍ以下である。層の平均厚みが０．３μｍ未満であると成形時の樹脂の伸びが悪化し、成形加工性に劣る。層の平均厚みが１．０μｍを超えると耐割れ性を得ることが困難となる。 The structure of the central part of the styrene-modified polyethylene resin particles in the present invention forms a co-continuous structure of a polyethylene resin and a polystyrene resin having an average layer thickness of 0.3 μm or more and 1.0 μm or less. The average thickness of the layer is preferably 0.35 μm or more and 0.9 μm or less. If the average thickness of the layer is less than 0.3 μm, the elongation of the resin at the time of molding deteriorates and the moldability is inferior. When the average thickness of the layer exceeds 1.0 μm, it becomes difficult to obtain crack resistance.
また本発明のスチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率は３０％以上であり、好ましくは４０％以上である。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率が３０％を下回ると耐割れ性が悪化する。 The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles of the present invention is 30% or more, and preferably 40% or more. If the ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles is less than 30%, the crack resistance deteriorates.
なおここでいうスチレン改質ポリエチレン系樹脂粒子中央部とは、スチレン改質ポリエチレン系樹脂粒子の中心から、スチレン改質ポリエチレン系樹脂粒子の半径の１／３の領域をいう。 The central portion of the styrene-modified polyethylene resin particles referred to here is a region that is 1/3 of the radius of the styrene-modified polyethylene resin particles from the center of the styrene-modified polyethylene resin particles.
スチレン改質ポリエチレン系樹脂粒子中央部の構造は、具体的には、スチレン改質ポリエチレン系樹脂粒子の最大径付近を薄膜状にスライスし透過型電子顕微鏡（ＴＥＭ）用いて観察することで評価する。共連続構造を構成する層の平均厚みはスチレン改質ポリエチレン系樹脂粒子中央部の任意の箇所を透過型電子顕微鏡で撮影した写真（以下、ＴＥＭ写真と称す場合がある）において、当該写真に１μｍ間隔で長さ５μｍの直線を５本引き、各５μｍ直線上に存在する、ポリスチレン系樹脂層、ポリエチレン系樹脂層それぞれについて層の厚さを読み取り、５本の平均値として算出した。得られたポリスチレン系樹脂層の厚みとポリエチレン系樹脂層の厚みの平均を層の平均厚みとした。 Specifically, the structure of the central part of the styrene-modified polyethylene resin particles is evaluated by slicing the vicinity of the maximum diameter of the styrene-modified polyethylene resin particles into a thin film and using a transmission electron microscope (TEM). . The average thickness of the layers constituting the co-continuous structure is 1 μm in a photograph (hereinafter sometimes referred to as a TEM photograph) taken with a transmission electron microscope of an arbitrary portion of the central part of the styrene-modified polyethylene resin particles. Five straight lines having a length of 5 μm were drawn at intervals, and the thickness of each of the polystyrene-based resin layer and the polyethylene-based resin layer existing on each 5 μm straight line was read and calculated as an average value of the five lines. The average of the thickness of the obtained polystyrene-type resin layer and the thickness of a polyethylene-type resin layer was made into the average thickness of a layer.
また、スチレン改質ポリエチレン系樹脂粒子の中央部のポリエチレン系樹脂の比率は、上記写真において、直線の長さ（５μｍ×５）に対する、直線上に占めるポリエチレン系樹脂の長さをポリエチレン系樹脂の比率とした。 The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles is the length of the polyethylene resin on the straight line with respect to the length of the straight line (5 μm × 5) in the above photograph. It was a ratio.
また本発明において、スチレン改質ポリエチレン系樹脂粒子は、スチレン改質ポリエチレン系樹脂粒子の表面から深さ５μｍ以内の表層部において直径１．０μｍ以下の球状のポリスチレン系樹脂がポリエチレン系樹脂に分散していることが好ましい。ポリスチレン系樹脂の直径が１．０μｍを超えると耐割れ性が悪化する傾向がある。なお、表層部のポリスチレン樹脂粒子の直径は透過型電子顕微鏡の写真を観察することで判別することが出来る。 In the present invention, the styrene-modified polyethylene resin particles have a spherical polystyrene resin having a diameter of 1.0 μm or less dispersed in the polyethylene resin in the surface layer within a depth of 5 μm from the surface of the styrene-modified polyethylene resin particles. It is preferable. When the diameter of the polystyrene resin exceeds 1.0 μm, the crack resistance tends to deteriorate. In addition, the diameter of the polystyrene resin particles in the surface layer can be determined by observing a photograph of a transmission electron microscope.
また、予備発泡の発泡剤含浸時に架橋反応を行っているスチレン改質ポリエチレン系樹脂粒子については、予備発泡直前の時点で、耐圧容器を冷却、常圧に戻し、発泡させずに樹脂を取り出したものについて測定を行う。なお、予備発泡の態様については後述する。 For styrene-modified polyethylene resin particles that undergo a crosslinking reaction when impregnated with a prefoaming foaming agent, the pressure-resistant container was cooled to normal pressure immediately before the prefoaming, and the resin was taken out without foaming. Measure things. The pre-foaming mode will be described later.
本発明において使用することが出来る発泡剤としては、公知のものが挙げられ、例えば、プロパン、イソブタン、ノルマルブタン、イソペンタン、ノルマルペンタン、ネオペンタン等の脂肪族炭化水素類、ジフルオロエタン、テトラフルオロエタン等のオゾン破壊係数がゼロであるハイドロフルオロカーボン類等の揮発性発泡剤、空気、窒素、二酸化炭素等の無機ガス、水等があげられる。これらの発泡剤は併用しても何ら差し支えない。 Examples of the blowing agent that can be used in the present invention include known ones such as aliphatic hydrocarbons such as propane, isobutane, normal butane, isopentane, normal pentane, and neopentane, difluoroethane, tetrafluoroethane, and the like. Examples thereof include volatile foaming agents such as hydrofluorocarbons having an ozone depletion coefficient of zero, inorganic gases such as air, nitrogen and carbon dioxide, and water. These foaming agents can be used in combination.
発泡剤は一般的には前記ラジカル種発生型架橋剤による架橋反応の後に追加されるが、架橋反応が完了する前に追加しても良い。 The foaming agent is generally added after the crosslinking reaction with the radical species generating crosslinking agent, but may be added before the crosslinking reaction is completed.
また、発泡剤量としてはスチレン改質ポリエチレン系樹脂粒子１００重量部に対して１０重量部以上３０重量部以下であることが好ましく、より好ましくは１５重量部以上２５重量部以下である。１０重量部未満では十分な発泡倍率を得ることができない場合がある上に、成形加工性の良好な予備発泡粒子を得ることが難しい場合がある。３０重量部を超えると発泡剤含浸時の樹脂の分散状態が不安定となり、樹脂同士が凝集を起こしやすくなる傾向がある。 The amount of the foaming agent is preferably 10 parts by weight or more and 30 parts by weight or less, and more preferably 15 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the styrene-modified polyethylene resin particles. If it is less than 10 parts by weight, a sufficient expansion ratio may not be obtained, and it may be difficult to obtain pre-expanded particles having good moldability. If it exceeds 30 parts by weight, the dispersion state of the resin when impregnated with the foaming agent becomes unstable and the resins tend to aggregate.
ポリエチレン系樹脂粒子にスチレン系単量体を含浸、重合させたスチレン改質ポリエチレン系樹脂粒子に、発泡剤を含浸、予備発泡する方法としては、（１）耐圧容器中でスチレン改質ポリエチレン系樹脂粒子を水性分散媒に分散させ、耐圧容器内に発泡剤を入れてスチレン改質ポリエチレン系樹脂粒子の軟化点以上の温度に加熱し、発泡剤の蒸気圧以上の加圧下でスチレン改質ポリエチレン系樹脂粒子に発泡剤を含浸させた後、耐圧容器内の温度および圧力を一定に保ちながらスチレン改質ポリエチレン系樹脂粒子と水性分散媒との混合物を耐圧容器内よりも低圧域に放出するいわゆる「除圧発泡」と呼ばれる方法、（２）ポリエチレン系樹脂粒子にスチレン系単量体を含浸、重合させた後、発泡剤を含浸させ発泡性スチレン改質ポリエチレン系樹脂粒子と成し、攪拌機を具備した容器内に発泡性スチレン改質ポリエチレン系樹脂粒子を入れ水蒸気等の熱源により加熱する方法、（３）ポリエチレン系樹脂粒子にスチレン系単量体を含浸、重合させてスチレン改質ポリエチレン系樹脂粒子と成し、攪拌機を具備した容器内にて発泡剤を含浸させ、水蒸気等の熱源により加熱する方法、等があげられるが、特に（１）の方法を選択することが、発泡剤の含浸と予備発泡を一連の操作で行うために過剰量の発泡剤を必要とせず、好ましい。 As a method of impregnating and pre-foaming styrene-modified polyethylene resin particles impregnated and polymerized with polyethylene-based resin particles with a foaming agent, (1) styrene-modified polyethylene resin in a pressure-resistant container Disperse the particles in an aqueous dispersion medium, place the foaming agent in a pressure-resistant container, heat it to a temperature above the softening point of the styrene-modified polyethylene resin particles, and pressurize it above the vapor pressure of the foaming agent. After impregnating the resin particles with a foaming agent, the so-called "" releases a mixture of styrene-modified polyethylene resin particles and an aqueous dispersion medium to a lower pressure region than in the pressure vessel while keeping the temperature and pressure in the pressure vessel constant. A method called “depressurization foaming”, (2) a polyethylene-based resin particle impregnated with a styrene monomer and polymerized, and then impregnated with a foaming agent to produce a foamable styrene-modified polyethylene. A method in which foamable styrene-modified polyethylene resin particles are placed in a container equipped with a stirrer and heated with a heat source such as water vapor. (3) Polyethylene resin particles are impregnated with styrene monomers. A method of polymerizing into styrene-modified polyethylene resin particles, impregnating a foaming agent in a container equipped with a stirrer, and heating with a heat source such as water vapor. It is preferable that an excessive amount of foaming agent is not required to perform impregnation of the foaming agent and prefoaming in a series of operations.
（１）の方法において、具体的には、重合反応によって得られたスチレン改質ポリエチレン系樹脂粒子を、一度重合を行った容器より取り出して洗浄・乾燥を行った後に、除圧発泡用の耐圧容器に仕込み、発泡剤を追加した後に加熱昇温し、前記耐圧容器内の温度および圧力を一定に保ちながら容器の一端を開放し、例えば開孔径が１ｍｍから１０ｍｍのオリフィス等を通して該耐圧容器内よりも低圧の雰囲気中、例えば大気中等の雰囲気中に内容物を放出し発泡させることにより、均一微細な気泡構造を有するスチレン改質ポリエチレン系樹脂予備発泡粒子を製造することができる。 In the method of (1), specifically, the styrene-modified polyethylene resin particles obtained by the polymerization reaction are taken out from the container once polymerized, washed and dried, and then pressure-resistant for decompression foaming. After charging the container and adding a foaming agent, the temperature is raised by heating, and one end of the container is opened while keeping the temperature and pressure in the pressure container constant, for example, through an orifice having a hole diameter of 1 mm to 10 mm. The styrene-modified polyethylene resin pre-expanded particles having a uniform and fine cell structure can be produced by releasing and foaming the contents in a lower pressure atmosphere, for example, in an atmosphere such as the air.
この除圧発泡でいう水性分散媒は、水に分散剤が溶解または分散したものを示し、分散剤は重合時と同様の種類の分散剤を使用することができる。この際、スチレン改質ポリエチレン系樹脂と水の重量比は樹脂／水で１．０／０．６から１．０／４．０であることが好ましい。この除圧発泡時点で可塑剤、気泡調整剤等の各種添加剤を含浸させても良い。この方法では発泡剤の含浸と予備発泡を同時に行うことができ、また発泡剤は吸引設備により回収することができるため、効率的である。 The aqueous dispersion medium referred to as decompression foaming indicates a solution in which a dispersant is dissolved or dispersed in water, and the same type of dispersant as in the polymerization can be used as the dispersant. At this time, the weight ratio of styrene-modified polyethylene resin to water is preferably 1.0 / 0.6 to 1.0 / 4.0 in terms of resin / water. You may impregnate various additives, such as a plasticizer and a bubble regulator, at the time of this decompression foaming. This method is efficient because the foaming agent can be impregnated and pre-foamed at the same time, and the foaming agent can be recovered by a suction facility.
（２）の方法においては、具体的には、前述の方法で重合反応に続いて発泡剤の追加、含浸を行う。発泡剤は架橋反応の前後どのタイミングで追加してもかまわない。この際、発泡剤導入による缶内圧力の急激な上昇を防ぐため、必要に応じて発泡剤を追加しやすい温度まで冷却を行ってから発泡剤を追加し、その後に温度を上昇させて発泡剤含浸や架橋反応を行うこともできる。その後、発泡剤を含浸させたスチレン改質ポリエチレン系樹脂粒子を耐圧容器より払い出し、洗浄・乾燥を行った後に水蒸気等によって加熱し、スチレン改質ポリエチレン系樹脂予備発泡粒子とすることができる。 In the method (2), specifically, the foaming agent is added and impregnated following the polymerization reaction by the above-described method. The blowing agent may be added at any timing before and after the crosslinking reaction. At this time, in order to prevent a sudden rise in the internal pressure due to the introduction of the foaming agent, the foaming agent is added after cooling to a temperature at which it is easy to add the foaming agent, if necessary, and then the temperature is raised to increase the foaming agent. Impregnation and crosslinking reaction can also be performed. Thereafter, the styrene-modified polyethylene resin particles impregnated with the foaming agent are discharged from the pressure vessel, washed and dried, and then heated with steam or the like to obtain styrene-modified polyethylene resin pre-expanded particles.
（３）においては、具体的には、重合反応を行うことによって得られたスチレン改質ポリエチレン系樹脂粒子を、一度、耐圧容器より取り出して洗浄・乾燥を行う。更に発泡剤含浸用の攪拌期を具備した耐圧容器に移し、少量の水、分散剤と発泡剤を追加して発泡剤含浸を行った後に払い出し、水蒸気等によって加熱し、スチレン改質ポリエチレン系樹脂予備発泡粒子とすることができる。この方法では発泡剤含浸時に仕込む水の量を少なくすることで発泡剤含浸後の乾燥工程を省くことができるため、予備発泡までの発泡剤の逸散を抑えることができる。 In (3), specifically, the styrene-modified polyethylene resin particles obtained by carrying out the polymerization reaction are once taken out from the pressure vessel and washed and dried. Transfer to a pressure-resistant vessel equipped with a stirring period for impregnating foaming agent, add a small amount of water, a dispersant and a foaming agent, impregnate the foaming agent, and then discharge and heat with steam, etc. It can be a pre-expanded particle. In this method, since the drying step after impregnating the foaming agent can be omitted by reducing the amount of water charged at the time of impregnation with the foaming agent, the dissipation of the foaming agent until the preliminary foaming can be suppressed.
以上のようにして得られた、スチレン改質ポリエチレン系樹脂予備発泡粒子は、キシレンに不溶なゲル成分量が１０重量％以上３５重量％以下であり、好ましくは１５重量％以上３０重量％以下である。当該範囲内であると、型内成形を行う場合、高圧あるいは長時間の蒸気加熱を必要とせず、高倍率化しやすく、耐割れ性が良好な発泡成形体が得られる。 The styrene-modified polyethylene resin pre-expanded particles obtained as described above have an amount of gel component insoluble in xylene of 10% by weight to 35% by weight, preferably 15% by weight to 30% by weight. is there. Within the range, when performing in-mold molding, high pressure or long-time steam heating is not required, and a foamed molded article that is easy to increase in magnification and has good crack resistance can be obtained.
本発明におけるキシレンに不溶なゲル成分量は以下のようにして測定する。２００メッシュの金網袋中に０．４ｇのスチレン改質ポリエチレン系樹脂予備発泡樹脂粒子を入れ、大気圧下で沸騰させたキシレン４５０ｍｌ中に２時間浸漬して冷却後に一旦、取り出し、更に新たな沸騰させたキシレン中に樹脂を１時間浸漬して冷却後にキシレンから取り出す。その後、同様に２時間、１時間の浸漬、溶出を繰り返し、その後、常温下で１晩液切りした後に１５０℃のオーブン中で１時間乾燥させ、常温まで自然冷却させ、冷却後の残留分をゲル成分とし、初期のスチレン改質ポリエチレン系樹脂予備発泡粒子量に対するゲル成分の量の重量比率をゲル成分量としている。 The amount of gel component insoluble in xylene in the present invention is measured as follows. Put 0.4g of styrene-modified polyethylene resin pre-expanded resin particles in a 200 mesh wire mesh bag, immerse in 450ml of xylene boiled under atmospheric pressure for 2 hours, take out once after cooling, and then boil again The resin is soaked in xylene for 1 hour, cooled, and taken out from xylene. Thereafter, the immersion and elution were repeated for 2 hours and 1 hour in the same manner. After that, the liquid was drained overnight at room temperature, dried in an oven at 150 ° C. for 1 hour, allowed to cool naturally to room temperature, and the residue after cooling was removed. As the gel component, the weight ratio of the amount of the gel component to the amount of the pre-expanded styrene-modified polyethylene resin pre-expanded particles is used as the gel component amount.
また、本発明のスチレン改質ポリエチレン系樹脂予備発泡粒子は、テトラヒドロフランに可溶な成分の重量平均分子量が１５万以上４０万以下である。当該範囲内であると、型内成形を行う場合、高圧あるいは長時間の蒸気加熱を必要とせず、高倍率化しやすく、耐割れ性が良好な発泡成形体が得られる。 In the styrene-modified polyethylene resin pre-expanded particles of the present invention, a component soluble in tetrahydrofuran has a weight average molecular weight of 150,000 to 400,000. Within the range, when performing in-mold molding, high pressure or long-time steam heating is not required, and a foamed molded article that is easy to increase in magnification and has good crack resistance can be obtained.
本発明におけるテトラヒドロフランに可溶分の重量平均分子量とは、スチレン改質ポリエチレン系樹脂予備発泡粒子０．０２ｇを常温のテトラヒドロフラン２０ｍｌに２４時間浸漬させることで抽出される成分を０．２μｍのフィルターでろ過したもの、ゲル・パーミエーション・クロマトグラフィーにより標準ポリスチレン試料を基準に求められた値である。 In the present invention, the weight-average molecular weight soluble in tetrahydrofuran is determined by immersing 0.02 g of styrene-modified polyethylene resin pre-foamed particles in 20 ml of normal temperature tetrahydrofuran for 24 hours using a 0.2 μm filter. It is a value obtained on the basis of a standard polystyrene sample by filtration or gel permeation chromatography.
以上のようにして得られた本発明のスチレン改質ポリエチレン系樹脂予備発泡粒子は、発泡剤逸散時においても成形性が良好である。なお本発明にいう発泡剤逸散時とは、スチレン改質ポリエチレン系樹脂予備発泡粒子中の発泡剤量が０．９重量％以下になった状態を言う。具体的に、発泡剤逸散時の成形性が良好であるとは、スチレン改質ポリエチレン系樹脂予備発泡粒子中の発泡剤量が０．９重量％となったときに成形性が良好であることをいう。これよりも発泡剤量が少ない状態で成形性が良好であることがより好ましい。 The styrene-modified polyethylene resin pre-expanded particles of the present invention obtained as described above have good moldability even when the foaming agent escapes. The term “when the foaming agent escapes” as used in the present invention refers to a state in which the amount of the foaming agent in the styrene-modified polyethylene resin pre-expanded particles is 0.9% by weight or less. Specifically, good moldability when the foaming agent escapes means that the moldability is good when the amount of the foaming agent in the styrene-modified polyethylene resin pre-expanded particles becomes 0.9% by weight. That means. It is more preferable that the moldability is good with a smaller amount of foaming agent.
なお、スチレン改質ポリエチレン系樹脂予備発泡粒子中の発泡剤量は、約２ｇのスチレン改質ポリエチレン系樹脂予備発泡粒子を計量し、１５０℃のオーブンで３０分乾燥を行った後に室温まで冷却してから再度計量を行い、乾燥後のスチレン改質ポリエチレン系樹脂予備発泡粒子の重量に対する、重量減少分の重量％を求めることにより測定した。 The amount of foaming agent in the styrene-modified polyethylene resin pre-expanded particles was measured by weighing about 2 g of styrene-modified polyethylene resin pre-expanded particles, drying in an oven at 150 ° C. for 30 minutes, and then cooling to room temperature. Then, the measurement was performed again, and the measurement was performed by determining the weight percent of the weight reduction with respect to the weight of the styrene-modified polyethylene resin pre-expanded particles after drying.
このようにして得られたスチレン改質ポリエチレン系樹脂予備発泡粒子は、一般的な型内成形方法によって成形される。具体的には、閉鎖し得るが密閉しえない金型内に充填し、加熱融着せしめて発泡成形体とされる。得られた発泡成形体は、剛性が高く、優れた耐割れ性を示す。そのため、自動車部材、緩衝材等に好適に使用することが出来る。 The styrene-modified polyethylene resin pre-expanded particles thus obtained are molded by a general in-mold molding method. Specifically, it is filled in a mold that can be closed but cannot be sealed, and is heat-sealed to obtain a foam molded article. The obtained foamed molded article has high rigidity and excellent crack resistance. Therefore, it can be suitably used for automobile members, cushioning materials and the like.
以下に実施例及び比較例をあげるが、これによって本発明は制限されるものではない。尚、測定評価については以下の通り実施した。 Examples and Comparative Examples are given below, but the present invention is not limited thereby. In addition, about measurement evaluation, it implemented as follows.
＜発泡成形体の表面状態＞
発泡成形体の表面状態は、目視観察にて評価した。数値が大きいほうが粒子同士の隙間が少ない表面状態であり、５点満点で表現した３以上を合格とした。
５：隙間がみあたらない
４：部分的に隙間があるがほとんどわからない
３：所々隙間があるが、全体としては許容レベル
２：隙間が目立つ
１：隙間が多い
<Surface condition of foam molded article>
The surface state of the foamed molded product was evaluated by visual observation. The larger the numerical value, the smaller the surface state between the particles, and a score of 3 or more expressed as a perfect score of 5 was accepted.
5: The gap does not meet 4: There is a gap partially, but it is almost unknown 3: There are gaps in some places, but as a whole, the tolerance level 2: The gap is conspicuous 1: There are many gaps
＜耐割れ性（半数破壊高さの測定）＞
発泡成形体を２００×２０×２０（ｔ）ｍｍに切り出したサンプル片にてＪＩＳ Ｋ ７２１１に準拠して３２１ｇの鋼球を落下させ半数破壊高さを測定した。
<Crack resistance (measurement of half fracture height)>
Based on JIS K 7211, a 321 g steel ball was dropped with a sample piece obtained by cutting the foam molded body into 200 × 20 × 20 (t) mm, and the half fracture height was measured.
＜発泡剤逸散時に成形を行った発泡成形体の表面状態＞
発泡成形体の表面状態は、成形後に約３５℃の乾燥室で１日保管したものを目視観察にて評価した。数値が大きいほうが粒子同士の隙間が少ない表面状態であり、３以上を合格とした。
<Surface condition of the foamed molded product when the foaming agent escapes>
The surface state of the foamed molded product was evaluated by visual observation after storage for 1 day in a drying room at about 35 ° C. The higher the numerical value, the smaller the surface state between the particles, and 3 or more were acceptable.
＜ゲル成分量の測定＞
２００メッシュの金網袋中に０．４ｇの予備発泡樹脂粒子を入れ、大気圧下で沸騰させたキシレン４５０ｍｌ中に２時間浸漬して冷却後に一旦、取り出し、更に新たな沸騰させたキシレン中に樹脂を１時間浸漬して冷却後にキシレンから取り出す。その後、同様に２時間、１時間の浸漬、溶出を繰り返し、その後、常温下で１晩液切りした後に１５０℃のオーブン中で１時間乾燥させ、常温まで自然冷却させ、冷却後の残留分をゲル成分とし、初期の予備発泡粒子量に対するゲル成分の量の重量比率をゲル成分量とした。
<Measurement of gel component amount>
Place 0.4 g of pre-expanded resin particles in a 200-mesh wire mesh bag, immerse in 450 ml of xylene boiled under atmospheric pressure for 2 hours, take it out after cooling, and then remove the resin in new boiled xylene. For 1 hour and after cooling, it is taken out from xylene. Thereafter, the immersion and elution were repeated for 2 hours and 1 hour in the same manner. After that, the liquid was drained overnight at room temperature, dried in an oven at 150 ° C. for 1 hour, allowed to cool naturally to room temperature, and the residue after cooling was removed. The gel component was used, and the weight ratio of the amount of the gel component to the initial amount of pre-expanded particles was used as the gel component amount.
＜スチレン改質ポリエチレン系樹脂粒子中央部の層の平均厚み＞
樹脂粒子中央部の平均厚みはＲｕＯ4染色した樹脂を常温超薄切片法により薄膜化し、樹脂中心部のＴＥＭ写真を撮影した。さらにＴＥＭ写真に１μｍ間隔で長さ５μｍの直線を５本引き、各５μｍ直線上に存在する各層の厚さの平均値を読み取り、さらに５本の平均値として算出した。この際、厳密にはポリエチレン系樹脂、ポリスチレン樹脂の各層には純粋なポリエチレン系樹脂、ポリスチレン樹脂以外にも各成分が反応したグラフトポリマーを含むが、本測定では考慮に入れず非染色部をポリエチレン系樹脂、染色部分をポリスチレンと判断した。また、ポリエチレン系樹脂成分中には連続層を形成していない粒子状の微細ポリスチレン粒子を含むが、これもポリエチレン層の一部とみなすこととした。
<Average thickness of the central layer of styrene-modified polyethylene resin particles>
The average thickness at the center of the resin particles was obtained by thinning a RuO 4 dyed resin by a room temperature ultrathin section method and taking a TEM photograph of the center of the resin. Further, five straight lines having a length of 5 μm were drawn on the TEM photograph at intervals of 1 μm, the average value of the thickness of each layer existing on each 5 μm straight line was read, and the average value of five lines was calculated. In this case, strictly speaking, each layer of polyethylene resin and polystyrene resin includes a graft polymer in which each component reacts in addition to pure polyethylene resin and polystyrene resin, but this measurement does not take into account the non-stained portion of polyethylene resin. The system resin and the dyed part were judged as polystyrene. Moreover, although the polyethylene-type resin component contains the particulate fine polystyrene particle which does not form the continuous layer, we decided to consider this also as a part of polyethylene layer.
＜スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂比率＞
樹脂粒子中央部の平均厚みはＲｕＯ4染色した樹脂を常温超薄切片法により薄膜化し、樹脂中心部のＴＥＭ写真を撮影した。さらにＴＥＭ写真に１μｍ間隔で長さ５μｍの直線を５本引き、各５μｍ直線中のポリエチレン成分の長さを比率として求め、５本の平均として算出した。
<Polyethylene resin ratio at the center of styrene-modified polyethylene resin particles>
The average thickness at the center of the resin particles was obtained by thinning a RuO 4 dyed resin by a room temperature ultrathin section method and taking a TEM photograph of the center of the resin. Further, five straight lines having a length of 5 μm were drawn on the TEM photograph at intervals of 1 μm, and the length of the polyethylene component in each 5 μm straight line was obtained as a ratio and calculated as an average of the five lines.
＜スチレン改質ポリエチレン系樹脂粒子の表層部のポリスチレン樹脂の直径＞
ＲｕＯ4染色した樹脂を常温超薄切片法により薄膜化し、樹脂表面のＴＥＭ写真から、表面から深さ５μｍ以内の視野中のポリスチレン樹脂の直径を観察した。
<The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles>
The resin stained with RuO 4 was thinned by an ultra-thin section method, and the diameter of the polystyrene resin in the visual field within 5 μm depth from the surface was observed from a TEM photograph of the resin surface.
（実施例１）
ポリエチレン系樹脂として住友化学株式会社製「エバテートＦ１１０３−１」を使用し、ポリエチレン系樹脂１００重量部に対してタルク０．２重量部を混合し押出機内で溶融混合して造粒し水中に押出した直後にカッティングすることで粒重量約１ｍｇ／粒の球状としたポリエチレン系樹脂粒子を作製した。
Example 1
“Evaate F1103-1” manufactured by Sumitomo Chemical Co., Ltd. is used as the polyethylene resin, 0.2 parts by weight of talc is mixed with 100 parts by weight of the polyethylene resin, melt-mixed in the extruder, granulated, and extruded into water. By cutting immediately after the formation, spherical polyethylene resin particles having a particle weight of about 1 mg / particle were produced.
続いて６Ｌオートクレーブに水１５０重量部に、第３リン酸カルシウム１重量部、α−オレフィンスルフォン酸ソーダ０．０２４重量部、ポリエチレン系樹脂粒子３０重量部を懸濁させ、スチレン１５重量部に、重合開始剤として過酸化ベンゾイル０．１８重量部（１０時間半減期温度：７４℃）、ラジカル種発生型架橋剤としてジクミルパーオキサイド（１０時間半減期温度：１１６℃）０．２９重量部を溶解させた溶液を添加した。その後、この水性懸濁液を７０℃まで昇温し、３０分間維持することでポリエチレン系樹脂粒子にスチレン単量体溶液を含浸させた。更に８５℃まで昇温し、スチレン単量体５５重量部を３時間４０分かけて反応系中に滴下し、滴下終了後８５℃で１時間保持した。その後、１４０℃昇温して３時間保持して架橋反応を行い、冷却後、洗浄・脱水・乾燥することによりスチレン改質ポリエチレン系樹脂粒子を得た。 Subsequently, 150 parts by weight of water, 1 part by weight of tribasic calcium phosphate, 0.024 parts by weight of sodium α-olefin sulfonate, and 30 parts by weight of polyethylene resin particles are suspended in a 6 L autoclave, and polymerization is started on 15 parts by weight of styrene. 0.18 parts by weight of benzoyl peroxide (10-hour half-life temperature: 74 ° C.) as an agent and 0.29 parts by weight of dicumyl peroxide (10-hour half-life temperature: 116 ° C.) as a radical species-generating crosslinking agent Solution was added. Thereafter, this aqueous suspension was heated to 70 ° C. and maintained for 30 minutes to impregnate the polyethylene resin particles with the styrene monomer solution. The temperature was further raised to 85 ° C., 55 parts by weight of a styrene monomer was dropped into the reaction system over 3 hours and 40 minutes, and the mixture was held at 85 ° C. for 1 hour after the completion of dropping. Thereafter, the temperature was raised to 140 ° C. and held for 3 hours to carry out a crosslinking reaction, and after cooling, washing, dehydration and drying were performed to obtain styrene-modified polyethylene resin particles.
得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成しており、層の平均厚みは０．４６μｍであった。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率は４９％であった。スチレン改質ポリエチレン系樹脂粒子表層部のポリスチレン樹脂の直径１μｍ以下であった。 When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles formed a co-continuous structure of polyethylene resin and polystyrene resin, and the average thickness of the layer was It was 0.46 μm. The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles was 49%. The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles was 1 μm or less.
４．５Ｌオートクレーブに水３３０重量部、第３リン酸カルシウム２重量部、ｎ−パラフィンスルホン酸ソーダ０．０１重量部、スチレン改質ポリエチレン系樹脂粒子１００重量部を仕込んだ。発泡剤としてノルマルリッチブタン（ノルマルブタン／イソブタン＝７５／２５）２２重量部をオートクレーブに添加した後、１４０℃に昇温し３０分保持することで発泡剤を含浸させた。その後、オートクレーブより開口径４ｍｍのオリフィスを通して水性分散媒と共にスチレン改質ポリエチレン系樹脂粒子を大気圧下に放出し、発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。大気圧下に放出している間、高圧窒素を導入することでオートクレーブ内の圧力が一定に保持されるように調整した。 A 4.5 L autoclave was charged with 330 parts by weight of water, 2 parts by weight of tricalcium phosphate, 0.01 parts by weight of sodium n-paraffin sulfonate, and 100 parts by weight of styrene-modified polyethylene resin particles. After adding 22 parts by weight of normal rich butane (normal butane / isobutane = 75/25) as a foaming agent, the temperature was raised to 140 ° C. and held for 30 minutes to impregnate the foaming agent. Thereafter, the styrene-modified polyethylene resin particles together with the aqueous dispersion medium were discharged under atmospheric pressure through an orifice having an opening diameter of 4 mm from the autoclave to obtain styrene-modified polyethylene resin pre-expanded particles having an expansion bulk ratio of 30 times. During the discharge under atmospheric pressure, the pressure in the autoclave was adjusted to be kept constant by introducing high-pressure nitrogen.
得られたスチレン改質ポリエチレン系樹脂予備発泡粒子を洗浄・脱水・乾燥した後に、室温で２日間養生させた予備発泡粒子（以下、「発泡直後の予備発泡粒子」と称す場合がある）、および約３５℃の乾燥室で残存発泡剤量が発泡粒子に対して０．９％となるまで乾燥した予備発泡粒子（以下、「発泡剤逸散時の予備発泡粒子」と称す場合がある）、の２種類を作製し、それぞれダイセンＫＲ−５７成形機を用いて３００×４５０×２５（ｔ）ｍｍサイズの金型にて成形を行い、発泡成形体を得た。発泡成形体の耐割れ性を評価したところ３４ｃｍであった。なお、予備発泡粒子中の発泡剤量は、約２ｇの予備発泡粒子を計量し、１５０℃のオーブンで３０分乾燥を行った後に室温まで冷却してから再度計量を行い、逸散分の重量％を求めることにより測定した。発泡剤逸散時の予備発泡粒子を用いて成形を行った発泡成形体の表面状態は３であった。 Pre-expanded particles obtained by washing, dehydrating and drying the obtained styrene-modified polyethylene resin pre-expanded particles, and then curing at room temperature for 2 days (hereinafter, referred to as “pre-expanded particles immediately after expansion”), and Pre-foamed particles dried in a drying chamber at about 35 ° C. until the residual foaming agent amount is 0.9% of the foamed particles (hereinafter, sometimes referred to as “pre-foamed particles when the foaming agent escapes”), These were produced using a Daisen KR-57 molding machine and molded with a 300 × 450 × 25 (t) mm size mold to obtain a foamed molded product. The crack resistance of the foamed molded product was evaluated and found to be 34 cm. The amount of the foaming agent in the pre-expanded particles is determined by weighing about 2 g of pre-expanded particles, drying in an oven at 150 ° C. for 30 minutes, cooling to room temperature, measuring again, %. The surface state of the foamed molded article formed by using the pre-expanded particles when the foaming agent escaped was 3.
(実施例２)
実施例１と同様にポリエチレン系樹脂粒子を作製した。
(Example 2)
Polyethylene resin particles were prepared in the same manner as in Example 1.
続いて６Ｌオートクレーブに水１５０重量部に、第３リン酸カルシウム１重量部、α−オレフィンスルフォン酸ソーダ０．０２４重量部、ポリエチレン系樹脂粒子３５重量部を懸濁させ、スチレン１７．５重量部に、重合開始剤として過酸化ベンゾイル０．２４重量部（１０時間半減期温度：７４℃）、ラジカル種発生型架橋剤としてｔ−ブチルパーオキシベンゾエート（１０時間半減期温度：１０４℃）０．５６重量部を溶解させた溶液を添加した。その後、この水性懸濁液を７０℃まで昇温し、３０分間維持することでポリエチレン系樹脂粒子にスチレン単量体溶液を含浸させた。更に８５℃まで昇温し、スチレン単量体４７．５重量部を２時間４０分かけて反応系中に滴下し、滴下終了後更８５℃で１時間保持した。その後、１２０℃昇温して１時間保持し、スチレン単量体の重合を完結させた。この際、架橋剤の分解量は１０時間半減期温度から計算して４割程度であり、架橋反応は完結していない。冷却後、洗浄・脱水・乾燥することによりスチレン改質ポリエチレン系樹脂粒子を得た。 Subsequently, 150 parts by weight of water, 1 part by weight of tricalcium phosphate, 0.024 part by weight of sodium α-olefin sulfonate, and 35 parts by weight of polyethylene resin particles were suspended in a 6 L autoclave, and 17.5 parts by weight of styrene was suspended. 0.24 parts by weight of benzoyl peroxide (10-hour half-life temperature: 74 ° C.) as a polymerization initiator and 0.56 weight of t-butyl peroxybenzoate (10-hour half-life temperature: 104 ° C.) as a radical species-generating crosslinking agent The solution in which the part was dissolved was added. Thereafter, this aqueous suspension was heated to 70 ° C. and maintained for 30 minutes to impregnate the polyethylene resin particles with the styrene monomer solution. The temperature was further raised to 85 ° C., and 47.5 parts by weight of styrene monomer was dropped into the reaction system over 2 hours and 40 minutes. After completion of the dropping, the mixture was further maintained at 85 ° C. for 1 hour. Thereafter, the temperature was raised to 120 ° C. and held for 1 hour to complete the polymerization of the styrene monomer. At this time, the amount of decomposition of the crosslinking agent is about 40% calculated from the 10-hour half-life temperature, and the crosslinking reaction is not completed. After cooling, styrene-modified polyethylene resin particles were obtained by washing, dehydration and drying.
４．５Ｌオートクレーブに水３３０重量部、第３リン酸カルシウム２重量部、ｎ−パラフィンスルホン酸ソーダ０．０１重量部、スチレン改質ポリエチレン系樹脂粒子１００重量部を仕込んだ。発泡剤としてノルマルリッチブタン（ノルマルブタン／イソブタン＝７５／２５）２２．５重量部をオートクレーブに添加した後、１４０℃に昇温し５０分保持することで発泡剤の含浸を行うとともに残り約６割の架橋反応を進行させた。その後、オートクレーブより開口径４ｍｍのオリフィスを通して水性分散媒と共にスチレン改質ポリエチレン系樹脂粒子を大気圧下に放出し、発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。大気圧下に放出している間、高圧窒素を導入することでオートクレーブ内の圧力が一定に保持されるように調整した。 A 4.5 L autoclave was charged with 330 parts by weight of water, 2 parts by weight of tricalcium phosphate, 0.01 parts by weight of sodium n-paraffin sulfonate, and 100 parts by weight of styrene-modified polyethylene resin particles. After adding 22.5 parts by weight of normal rich butane (normal butane / isobutane = 75/25) as a foaming agent to the autoclave, the temperature was raised to 140 ° C. and held for 50 minutes to impregnate the foaming agent and the remaining about 6 The cross-linking reaction was allowed to proceed. Thereafter, the styrene-modified polyethylene resin particles together with the aqueous dispersion medium were discharged under atmospheric pressure through an orifice having an opening diameter of 4 mm from the autoclave to obtain styrene-modified polyethylene resin pre-expanded particles having an expansion bulk ratio of 30 times. During the discharge under atmospheric pressure, the pressure in the autoclave was adjusted to be kept constant by introducing high-pressure nitrogen.
得られたスチレン改質ポリエチレン系樹脂予備発泡粒子は実施例１と同様に成形して評価した。耐割れ性は４２ｃｍであった。スチレン改質ポリエチレン系樹脂予備発泡粒子の残存発泡剤が０．９％の時点で成形を行った発泡成形体の表面状態は３であった。 The obtained styrene-modified polyethylene resin pre-expanded particles were molded and evaluated in the same manner as in Example 1. The crack resistance was 42 cm. The surface state of the foamed molded article that was molded when the residual foaming agent of the styrene-modified polyethylene resin pre-expanded particles was 0.9% was 3.
除圧発泡による予備発泡時に架橋反応を行ったため、ＴＥＭ写真については、除圧発泡の直前まで同様の操作を行い、除圧発泡直前の時点で、耐圧容器を冷却、常圧に戻し、発泡させずに樹脂粒子を取り出し、測定を行った。得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成しており、層の平均厚みは０．４０μｍであった。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂成分の比率は４４％であった。スチレン改質ポリエチレン系樹脂粒子表層部のポリスチレン樹脂の直径は１μｍ以下であった。 Since the cross-linking reaction was performed during pre-foaming by decompression foaming, the same operation was performed for TEM photographs until just before decompression foaming, and the pressure-resistant container was cooled to normal pressure and foamed immediately before decompression foaming. The resin particles were taken out and measured. When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles formed a co-continuous structure of polyethylene resin and polystyrene resin, and the average thickness of the layer was It was 0.40 μm. The ratio of the polyethylene resin component at the center of the styrene-modified polyethylene resin particles was 44%. The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles was 1 μm or less.
(比較例１)
６Ｌオートクレーブでの重合において、架橋剤をｔ−ブチルパーオキシベンゾエート（１０時間半減期温度：１０４℃）０．４５部とし、架橋反応時の１４０℃の昇温を１２５℃とした以外は実施例１と同様にし、スチレン改質ポリエチレン系樹脂粒子を得た。
(Comparative Example 1)
In the polymerization in a 6 L autoclave, the example is except that the cross-linking agent is t-butyl peroxybenzoate (10 hour half-life temperature: 104 ° C.) 0.45 part, and the temperature rise at 140 ° C. during the cross-linking reaction is 125 ° C. In the same manner as in Example 1, styrene-modified polyethylene resin particles were obtained.
得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成しており、層の平均厚みは０．２９μｍであった。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率は４７％であった。スチレン改質ポリエチレン系樹脂粒子表層部のポリスチレン樹脂の直径は１μｍ以下であった。 When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles formed a co-continuous structure of polyethylene resin and polystyrene resin, and the average thickness of the layer was It was 0.29 μm. The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles was 47%. The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles was 1 μm or less.
更に発泡剤としてノルマルリッチブタン２４部を使用した以外は実施例１と同様に予備発泡を行い、発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。得られたスチレン改質ポリエチレン系予備発泡粒子は実施例１と同様に成形して評価した。耐割れ性は３７ｃｍであった。スチレン改質ポリエチレン系樹脂予備発泡粒子の残存発泡剤量が０．９重量％の時点で成形を行った発泡成形体の表面状態は２であった。 Further, pre-expansion was carried out in the same manner as in Example 1 except that 24 parts of normal rich butane was used as a foaming agent to obtain styrene-modified polyethylene resin pre-expanded particles having an expansion bulk ratio of 30 times. The obtained styrene-modified polyethylene pre-expanded particles were molded and evaluated in the same manner as in Example 1. The crack resistance was 37 cm. The surface state of the foamed molded article that was molded when the residual foaming agent amount of the styrene-modified polyethylene resin pre-expanded particles was 0.9% by weight was 2.
(比較例２)
６Ｌオートクレーブでの重合で１２５℃に昇温し、１２５℃での保持時間を３時間として架橋反応を完結させた以外は実施例２と同様にし、スチレン改質ポリエチレン系樹脂粒子を得た。
(Comparative Example 2)
Styrene-modified polyethylene resin particles were obtained in the same manner as in Example 2 except that the temperature was raised to 125 ° C. by polymerization in a 6 L autoclave and the crosslinking reaction was completed by setting the holding time at 125 ° C. to 3 hours.
得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成しており、層の平均厚みは０．２５μｍであった。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率は４６％であった。スチレン改質ポリエチレン系樹脂粒子表層部のポリスチレン樹脂の直径は１μｍ以下であった。 When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles formed a co-continuous structure of polyethylene resin and polystyrene resin, and the average thickness of the layer was It was 0.25 μm. The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles was 46%. The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles was 1 μm or less.
更に実施例２と同様の操作で発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。 Furthermore, by the same operation as in Example 2, styrene-modified polyethylene resin pre-expanded particles having an expansion bulk ratio of 30 times were obtained.
得られたスチレン改質ポリエチレン系樹脂予備発泡粒子は実施例１と同様に成形して評価した。耐割れ性は４３ｃｍであった。スチレン改質ポリエチレン系樹脂予備発泡粒子の残存発泡剤量が０．９重量％の時点で成形を行った発泡成形体の表面状態は１であった。 The obtained styrene-modified polyethylene resin pre-expanded particles were molded and evaluated in the same manner as in Example 1. The crack resistance was 43 cm. The surface state of the foamed molded article that was molded when the residual foaming agent amount of the styrene-modified polyethylene resin pre-expanded particles was 0.9% by weight was 1.
（比較例３）
実施例１と同様にポリエチレン系樹脂粒子を作製した。
(Comparative Example 3)
Polyethylene resin particles were prepared in the same manner as in Example 1.
続いて６Ｌオートクレーブに水１５０重量部に、第３リン酸カルシウム１重量部、α−オレフィンスルフォン酸ソーダ０．０２４重量部、ポリエチレン系樹脂粒子３０重量部を懸濁させた。その後、この水性懸濁液を８５℃まで昇温し、スチレン１５重量部に、重合開始剤として過酸化ベンゾイル０．１８重量部（１０時間半減期温度：７４℃）、ラジカル種発生型架橋剤としてジクミルパーオキサイド（１０時間半減期温度：１１６℃）０．２９重量部を溶解させた溶液を１時間かけて連続的に添加した。更に、スチレン単量体５５重量部を３時間４０分かけて反応系中に滴下し、滴下終了後８５℃で１時間保持した。その後、１４０℃昇温して３時間保持して架橋反応を行い、冷却後、洗浄・脱水・乾燥することによりスチレン改質ポリエチレン系樹脂粒子を得た。 Subsequently, 1 part by weight of tricalcium phosphate, 0.024 part by weight of sodium α-olefin sulfonate, and 30 parts by weight of polyethylene resin particles were suspended in 150 parts by weight of water in a 6 L autoclave. Thereafter, the aqueous suspension was heated to 85 ° C., 15 parts by weight of styrene, 0.18 parts by weight of benzoyl peroxide (10 hour half-life temperature: 74 ° C.) as a polymerization initiator, and a radical species generating type crosslinking agent. As a solution, 0.29 parts by weight of dicumyl peroxide (10-hour half-life temperature: 116 ° C.) was continuously added over 1 hour. Further, 55 parts by weight of a styrene monomer was dropped into the reaction system over 3 hours and 40 minutes, and maintained at 85 ° C. for 1 hour after the completion of the dropping. Thereafter, the temperature was raised to 140 ° C. and held for 3 hours to carry out a crosslinking reaction, and after cooling, washing, dehydration and drying were performed to obtain styrene-modified polyethylene resin particles.
得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成しており、層の平均厚みは０．７１μｍであった。スチレン改質ポリエチレン系樹脂粒子中央部のポリエチレン系樹脂の比率は２３％であった。スチレン改質ポリエチレン系樹脂粒子表層のポリスチレン樹脂の直径は１μｍ以下であった。 When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles formed a co-continuous structure of polyethylene resin and polystyrene resin, and the average thickness of the layer was It was 0.71 μm. The ratio of the polyethylene resin at the center of the styrene-modified polyethylene resin particles was 23%. The diameter of the polystyrene resin on the surface layer of the styrene-modified polyethylene resin particles was 1 μm or less.
更に発泡剤としてノルマルリッチブタン２０．５部を使用した以外は実施例１と同様に予備発泡を行い、発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。 Further, pre-expansion was carried out in the same manner as in Example 1 except that 20.5 parts of normal rich butane was used as a foaming agent to obtain styrene-modified polyethylene resin pre-expanded particles having an expansion bulk ratio of 30 times.
得られたスチレン改質ポリエチレン系予備発泡粒子は実施例１と同様に成形して評価した。耐割れ性は２９ｃｍであった。スチレン改質ポリエチレン系樹脂予備発泡粒子の残存発泡剤量が０．９重量％の時点で成形を行った発泡成形体の表面状態は２であった。 The obtained styrene-modified polyethylene pre-expanded particles were molded and evaluated in the same manner as in Example 1. The crack resistance was 29 cm. The surface state of the foamed molded article that was molded when the residual foaming agent amount of the styrene-modified polyethylene resin pre-expanded particles was 0.9% by weight was 2.
（比較例４）
過酸化ベンゾイルを０．１１重量部、ジクミルパーオキサイドを０．１８重量部とした以外は比較例３と同様にスチレン改質ポリエチレン系樹脂粒子を得た。
(Comparative Example 4)
Styrene-modified polyethylene resin particles were obtained in the same manner as in Comparative Example 3, except that 0.11 part by weight of benzoyl peroxide and 0.18 part by weight of dicumyl peroxide were used.
得られたスチレン改質ポリエチレン系樹脂粒子のＴＥＭ観察をおこなったところ、スチレン改質ポリエチレン系樹脂粒子中央部はポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成していなかった。スチレン改質ポリエチレン系樹脂粒子表層部のポリスチレン樹脂の直径は１μｍ以下であった。 When TEM observation of the obtained styrene modified polyethylene resin particles was performed, the central part of the styrene modified polyethylene resin particles did not form a co-continuous structure of the polyethylene resin and the polystyrene resin. The diameter of the polystyrene resin in the surface layer portion of the styrene-modified polyethylene resin particles was 1 μm or less.
更に発泡剤としてノルマルリッチブタン１９．５部を使用した以外は実施例１と同様に予備発泡を行い、発泡嵩倍率３０倍のスチレン改質ポリエチレン系樹脂予備発泡粒子を得た。 Further, pre-foaming was performed in the same manner as in Example 1 except that 19.5 parts of normal rich butane was used as a foaming agent to obtain styrene-modified polyethylene resin pre-foamed particles having a foam volume ratio of 30 times.
得られたスチレン改質ポリエチレン系樹脂予備発泡粒子は実施例１と同様に成形して評価した。耐割れ性は１５ｃｍであった。スチレン改質ポリエチレン系樹脂予備発泡粒子の残存発泡剤量が０．９％の時点で成形を行った発泡成形体の表面状態は４であった。 The obtained styrene-modified polyethylene resin pre-expanded particles were molded and evaluated in the same manner as in Example 1. The crack resistance was 15 cm. The surface state of the foamed molded product that was molded when the amount of the remaining foaming agent of the styrene-modified polyethylene resin pre-expanded particles was 0.9% was 4.
実施例１、２では残存発泡剤が０．９重量％以下での成形において、得られた発泡成形体の表面状態において３以上の評価が得られており、発泡剤逸散時の予備発泡粒子の成形加工性が優れていることがわかる。一方、比較例１から４では耐割れ性、発泡剤逸散時の成形のおける表面状態のいずれかに劣るものであった。 In Examples 1 and 2, in the molding with a residual foaming agent of 0.9% by weight or less, an evaluation of 3 or more was obtained in the surface state of the obtained foamed molded product, and the pre-expanded particles when the foaming agent escaped It can be seen that the moldability is excellent. On the other hand, Comparative Examples 1 to 4 were inferior to either the crack resistance or the surface condition in the molding when the foaming agent escaped.
本発明の製造方法によって得られたスチレン改質ポリエチレン系樹脂予備発泡粒子は、予備発泡直後でなくとも成形加工性に優れ、また、得られた発泡成形体は、耐割れ性に優れているため、とりわけ自動車部材、緩衝材に好適に使用できる。 The styrene-modified polyethylene resin pre-expanded particles obtained by the production method of the present invention are excellent in molding processability even if not immediately after the pre-expansion, and the obtained expanded molded article is excellent in crack resistance. In particular, it can be suitably used for automobile members and cushioning materials.
Claims (4)
ポリエチレン系樹脂粒子１００重量部に対し、スチレン系単量体２５重量部以上１００重量部以下を本質的に重合が進まない温度下で添加して含浸させ、残りのスチレン系単量体を加熱下で添加し、重合を行い、かつ、
重合中、或いは、重合後に、１０時間半減期温度が１００℃以上１２５℃以下である架橋剤を添加し、１３０℃以上１５０℃以下で５０％以上の架橋剤が分解されることによって得られるスチレン改質ポリエチレン系樹脂粒子において、
該スチレン改質ポリエチレン系樹脂粒子中央部が、層の平均厚みが０．３μｍ以上１．０μｍ以下であるポリエチレン系樹脂とポリスチレン系樹脂の共連続構造を形成し、かつ、該中央部共連続構造のポリエチレン系樹脂の比率が３０％以上であり、
さらに、該スチレン改質ポリエチレン系樹脂粒子から得られるスチレン改質ポリエチレン系樹脂予備発泡粒子のキシレン不溶のゲル成分が１０重量％以上３５重量％以下である、スチレン改質ポリエチレン系樹脂粒子。 When the styrene monomer Ru impregnated 300 parts hereinafter more than 150 parts by weight per 100 parts by weight of polyethylene resin,
To 100 parts by weight of polyethylene resin particles, 25 parts by weight or more and 100 parts by weight or less of styrene monomer are added and impregnated at a temperature at which polymerization does not proceed substantially, and the remaining styrene monomer is heated. Added to perform polymerization, and
Styrene obtained by adding a crosslinking agent having a 10-hour half-life temperature of 100 ° C. or more and 125 ° C. or less during or after polymerization, and decomposing 50% or more of the crosslinking agent at 130 ° C. or more and 150 ° C. or less. In the modified polyethylene resin particles,
The central part of the styrene-modified polyethylene resin particles forms a co-continuous structure of a polyethylene resin and a polystyrene resin having an average layer thickness of 0.3 μm or more and 1.0 μm or less, and the central part co-continuous structure The ratio of polyethylene resin is 30% or more,
Furthermore, the styrene gel component of xylene insoluble modified polyethylene-based derived from the resin particles modified polyethylene-based resin pre-expanded particles is 35 wt% or less 10% by weight or more, styrene-modified polyethylene-based resin particles.
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