WO2022137710A1 - ポリエチレン系樹脂多層発泡シート及びその製造方法 - Google Patents
ポリエチレン系樹脂多層発泡シート及びその製造方法 Download PDFInfo
- Publication number
- WO2022137710A1 WO2022137710A1 PCT/JP2021/036370 JP2021036370W WO2022137710A1 WO 2022137710 A1 WO2022137710 A1 WO 2022137710A1 JP 2021036370 W JP2021036370 W JP 2021036370W WO 2022137710 A1 WO2022137710 A1 WO 2022137710A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- polyethylene
- conductive layer
- ethylene
- foamed sheet
- based resin
- Prior art date
Links
- 239000006260 foam Substances 0.000 title claims abstract description 156
- 229920013716 polyethylene resin Polymers 0.000 title claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 title claims description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 102
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 99
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 91
- 239000005977 Ethylene Substances 0.000 claims abstract description 90
- -1 polyethylenes Polymers 0.000 claims abstract description 79
- 239000004698 Polyethylene Substances 0.000 claims abstract description 73
- 229920000573 polyethylene Polymers 0.000 claims abstract description 73
- 238000002844 melting Methods 0.000 claims abstract description 43
- 230000008018 melting Effects 0.000 claims abstract description 43
- 229920005989 resin Polymers 0.000 claims abstract description 38
- 239000011347 resin Substances 0.000 claims abstract description 38
- 239000000178 monomer Substances 0.000 claims abstract description 23
- 229920001684 low density polyethylene Polymers 0.000 claims abstract description 13
- 229920000092 linear low density polyethylene Polymers 0.000 claims abstract description 11
- 229920005678 polyethylene based resin Polymers 0.000 claims description 89
- 229920001577 copolymer Polymers 0.000 claims description 80
- 239000000155 melt Substances 0.000 claims description 57
- 238000002156 mixing Methods 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 26
- 239000004088 foaming agent Substances 0.000 claims description 23
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 claims description 14
- 239000004702 low-density polyethylene Substances 0.000 claims description 12
- 239000004707 linear low-density polyethylene Substances 0.000 claims description 10
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 7
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims description 7
- 238000010521 absorption reaction Methods 0.000 claims description 5
- 238000004898 kneading Methods 0.000 claims description 4
- 238000013329 compounding Methods 0.000 claims description 3
- 229920005680 ethylene-methyl methacrylate copolymer Polymers 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 6
- 229920001038 ethylene copolymer Polymers 0.000 abstract description 3
- 238000001125 extrusion Methods 0.000 description 36
- 230000000052 comparative effect Effects 0.000 description 26
- 239000004014 plasticizer Substances 0.000 description 16
- 239000003795 chemical substances by application Substances 0.000 description 15
- 238000005259 measurement Methods 0.000 description 15
- 239000000203 mixture Substances 0.000 description 14
- 238000005187 foaming Methods 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- 229920000642 polymer Polymers 0.000 description 12
- 239000000654 additive Substances 0.000 description 10
- 239000002585 base Substances 0.000 description 10
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 10
- IJDNQMDRQITEOD-UHFFFAOYSA-N sec-butylidene Natural products CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 9
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 8
- 125000004432 carbon atom Chemical group C* 0.000 description 7
- 238000011109 contamination Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 6
- 230000001771 impaired effect Effects 0.000 description 6
- 239000005022 packaging material Substances 0.000 description 6
- 229920005992 thermoplastic resin Polymers 0.000 description 6
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 5
- 230000000996 additive effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000002708 enhancing effect Effects 0.000 description 5
- 239000001282 iso-butane Substances 0.000 description 5
- 239000001273 butane Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 230000001965 increasing effect Effects 0.000 description 4
- 238000009835 boiling Methods 0.000 description 3
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 3
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229920001903 high density polyethylene Polymers 0.000 description 3
- 239000004700 high-density polyethylene Substances 0.000 description 3
- 238000010030 laminating Methods 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 3
- 239000004711 α-olefin Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-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
- RGSFGYAAUTVSQA-UHFFFAOYSA-N Cyclopentane Chemical compound C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 2
- 229920000181 Ethylene propylene rubber Polymers 0.000 description 2
- 239000004594 Masterbatch (MB) Substances 0.000 description 2
- 239000004793 Polystyrene Substances 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
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 2
- 239000003242 anti bacterial agent Substances 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 2
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000000806 elastomer Substances 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 229920005648 ethylene methacrylic acid copolymer Polymers 0.000 description 2
- 229920006245 ethylene-butyl acrylate Polymers 0.000 description 2
- 229920006244 ethylene-ethyl acrylate Polymers 0.000 description 2
- 229920006225 ethylene-methyl acrylate Polymers 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 239000012760 heat stabilizer Substances 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 2
- 239000003273 ketjen black Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- LVGUZGTVOIAKKC-UHFFFAOYSA-N 1,1,1,2-tetrafluoroethane Chemical compound FCC(F)(F)F LVGUZGTVOIAKKC-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
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 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 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- CSJKPFQJIDMSGF-UHFFFAOYSA-K aluminum;tribenzoate Chemical compound [Al+3].[O-]C(=O)C1=CC=CC=C1.[O-]C(=O)C1=CC=CC=C1.[O-]C(=O)C1=CC=CC=C1 CSJKPFQJIDMSGF-UHFFFAOYSA-K 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- DQXBYHZEEUGOBF-UHFFFAOYSA-N but-3-enoic acid;ethene Chemical compound C=C.OC(=O)CC=C DQXBYHZEEUGOBF-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
- QYMGIIIPAFAFRX-UHFFFAOYSA-N butyl prop-2-enoate;ethene Chemical compound C=C.CCCCOC(=O)C=C QYMGIIIPAFAFRX-UHFFFAOYSA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- HRYZWHHZPQKTII-UHFFFAOYSA-N chloroethane Chemical compound CCCl HRYZWHHZPQKTII-UHFFFAOYSA-N 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000113 differential scanning calorimetry Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 229960003750 ethyl chloride Drugs 0.000 description 1
- 229920006242 ethylene acrylic acid copolymer Polymers 0.000 description 1
- 229920006226 ethylene-acrylic acid Polymers 0.000 description 1
- 239000005042 ethylene-ethyl acrylate Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000006232 furnace black Substances 0.000 description 1
- 238000001864 heat-flux differential scanning calorimetry Methods 0.000 description 1
- DMEGYFMYUHOHGS-UHFFFAOYSA-N heptamethylene Natural products C1CCCCCC1 DMEGYFMYUHOHGS-UHFFFAOYSA-N 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000012968 metallocene catalyst Substances 0.000 description 1
- 229920001526 metallocene linear low density polyethylene Polymers 0.000 description 1
- 229940050176 methyl chloride Drugs 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- WXMKPNITSTVMEF-UHFFFAOYSA-M sodium benzoate Chemical compound [Na+].[O-]C(=O)C1=CC=CC=C1 WXMKPNITSTVMEF-UHFFFAOYSA-M 0.000 description 1
- 239000004299 sodium benzoate Substances 0.000 description 1
- 235000010234 sodium benzoate Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 1
- 229920006132 styrene block copolymer Polymers 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 229920000468 styrene butadiene styrene block copolymer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 239000006234 thermal black Substances 0.000 description 1
- 238000009823 thermal lamination Methods 0.000 description 1
- NFMWFGXCDDYTEG-UHFFFAOYSA-N trimagnesium;diborate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]B([O-])[O-].[O-]B([O-])[O-] NFMWFGXCDDYTEG-UHFFFAOYSA-N 0.000 description 1
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/065—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
- B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
- B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
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- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
- B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
- B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
- B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state
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- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
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- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
- B32B7/025—Electric or magnetic properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
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Definitions
- the present invention relates to a polyethylene-based resin multilayer foamed sheet and a method for producing the same.
- Polyethylene resin foam sheets using polyethylene resin as the base resin are used as cushioning materials and packaging materials because of their high flexibility and excellent shock absorption.
- cushioning materials and packaging materials used for packaging electronic devices and electronic parts may be required to have conductivity in addition to protection against an object to be packaged.
- Patent Document 1 describes a conductive polyethylene-based resin foamed sheet obtained by mixing a masterbatch containing conductive carbon and a polyethylene-based resin and extruding and foaming the masterbatch. Have been described.
- Patent Document 2 describes a foamable multilayer thermoplastic resin sheet composed of at least two layers of a non-conductive polyethylene-based resin containing a pyrolytic foaming agent and a conductive thermoplastic resin layer containing conductive carbon.
- a conductive polyethylene-based resin multilayer foamed sheet obtained by heat-foaming is described.
- the foamed sheet of Patent Document 1 needs to contain a relatively large amount of conductive carbon in the foamed sheet in order to impart conductivity. However, if the amount of the conductive carbon blended in the foamed sheet is large, the foamability is hindered, and the properties such as the cushioning property required for use as a cushioning material or a packaging material may be impaired.
- conductive carbon may fall off from the foamed sheet and contaminate the surroundings of the foamed sheet.
- the conductive carbon is likely to fall off from the foamed sheet, and the periphery of the foamed sheet may be easily contaminated by the conductive carbon.
- the foamed sheet is used as a packaging material, the conductive carbon that has fallen off from the foamed sheet may be transferred to the packaged object, and the packaged object may be contaminated.
- the present invention has been made in view of this background, and an object of the present invention is to provide a polyethylene-based resin multilayer foamed sheet having conductivity and capable of reducing the loss of conductive carbon from the foamed sheet, and a method for producing the same. It is something to do.
- One aspect of the present invention is a polyethylene resin foam layer containing a polyethylene resin (A) as a base resin.
- a conductive layer laminated on at least one side of the polyethylene-based resin foam layer is provided.
- the conductive layer is It comprises one or more polyethylenes (B) selected from the group consisting of low density polyethylene and linear low density polyethylene, and structural units derived from ethylene and structural units derived from monomers having polar groups.
- the difference between the melting point Tm B of the polyethylene (B) contained in the conductive layer and the melting point Tm C of the ethylene-based copolymer (C) Tm B ⁇ Tm C is 30 ° C. or higher and 80 ° C. or lower. Located on a resin multilayer foam sheet.
- a method for producing a polyethylene-based resin multilayer foamed sheet comprising: a polyethylene-based resin foamed layer and the conductive layer laminated on at least one side of the polyethylene-based resin foamed layer.
- the foam layer forming melt is formed by kneading a polyethylene resin (A) as a base resin and a physical foaming agent.
- the melt for forming a conductive layer has one or more types of polyethylene (B) selected from the group consisting of low-density polyethylene and linear low-density polyethylene, and a structural unit and a polar group derived from ethylene.
- a polyethylene-based copolymer (C) having a structural unit derived from a monomer and a conductive carbon are kneaded together.
- the blending amount of the conductive carbon in the melt for forming the conductive layer is 3% by mass or more and 15% by mass or less.
- the polyethylene-based resin multilayer foamed sheet (hereinafter, appropriately referred to as “multilayer foamed sheet”) has a composition of the conductive layer in the specific embodiment, so that even if the amount of the conductive carbon is relatively small, the amount of the conductive carbon is relatively small. Conductivity can be imparted to the multilayer foamed sheet. Further, the conductive layer having the specific composition can suppress the falling off of the conductive carbon.
- a multilayer foamed sheet can be obtained by coextruding the foam layer forming melt and the conductive layer forming melt having the specific composition.
- the composition of the melt for forming the conductive layer to the above-mentioned specific embodiment, it is possible to impart conductivity to the multilayer foamed sheet even if the blending amount of the conductive carbon is relatively small.
- the manufacturing method it is possible to obtain a multilayer foamed sheet capable of reducing the loss of conductive carbon.
- the multilayer foamed sheet has two or more layers including a polyethylene-based resin foamed layer and a conductive layer laminated on at least one side of the polyethylene-based resin foamed layer.
- Each layer contained in the multilayer foam sheet is laminated and adhered to adjacent layers. It is preferable that each layer in the multilayer foamed sheet is laminated and adhered to adjacent layers by coextrusion.
- the multilayer foamed sheet may be composed of two layers, a polyethylene-based resin foamed layer and a conductive layer laminated on one side of the polyethylene-based resin foamed layer.
- the multilayer foamed sheet may be composed of three layers, that is, a polyethylene-based resin foamed layer and a conductive layer laminated on both sides of the polyethylene-based resin foamed layer.
- a layer having a composition different from that of the polyethylene-based resin foam layer and the conductive layer may be provided between the polyethylene-based resin foam layer and the conductive layer in the multilayer foam sheet or on the outermost surface of the multilayer foam sheet. ..
- the conductive layer is laminated on both sides of the polyethylene-based resin foam layer, and the conductive layer is multilayer foamed. It is more preferably located on the surface of the sheet.
- the total thickness of the multilayer foamed sheet is preferably 0.05 mm or more and 3.0 mm or less.
- the total thickness of the multilayer foamed sheet is preferably 0.05 mm or more and 3.0 mm or less.
- the cushioning property of the multilayer foamed sheet can be further enhanced.
- the handleability of the multilayer foamed sheet is further improved. It can be enhanced and the packaged object can be packed more easily.
- the method for measuring the total thickness of the multi-layer foam sheet is as follows. First, the multilayer foam sheet is cut in a plane perpendicular to the extrusion direction. In this cut surface, 10 measurement positions are set so as to divide the length of the cut surface in the width direction (that is, the direction perpendicular to both the extrusion direction and the thickness direction) into 11 equal parts. The thickness of each measurement position is measured by a method such as observing these measurement positions using a microscope. Then, the arithmetic mean value of these thicknesses is taken as the total thickness of the multilayer foamed sheet.
- the apparent density of the multilayer foamed sheet is preferably 30 kg / m 3 or more and 150 kg / m 3 or less.
- the apparent density of the multilayer foam sheet is preferably 30 kg / m 3 or more, more preferably 35 kg / m 3 or more, and further preferably 40 kg / m 3 or more, sufficient strength as a cushioning material or a packaging material can be easily secured. Can be done.
- the apparent density of the multilayer foamed sheet to 150 kg / m 3 or less, more preferably 120 kg / m 3 or less, still more preferably 100 kg / m 3 or less, the lightness and flexibility of the multilayer foamed sheet are sufficiently ensured.
- the cushioning property of the multilayer foam sheet can be further enhanced.
- the method for measuring the apparent density of the multilayer foam sheet is as follows. First, the multilayer foam sheet is cut in the width direction, and a test piece is collected.
- the shape of the test piece can be, for example, a rectangle whose vertical dimension is the same as the total width of the multilayer foam sheet and whose horizontal dimension is 10 cm.
- the basis weight of the multilayer foamed sheet that is, the mass per 1 m 2 of the multilayer foamed sheet (unit: g / m 2 ). Is calculated.
- the apparent density of the multi-layer foam sheet (unit: kg / m 3 ) can be calculated by dividing the basis weight of the multi-layer foam sheet by the total thickness of the multi-layer foam sheet obtained by the above method and then converting the unit. ..
- the surface resistivity of the surface of the multilayer foamed sheet on the side having the conductive layer is preferably 1 ⁇ 10 3 ⁇ or more and 1 ⁇ 10 7 ⁇ or less.
- a multilayer foam sheet having a surface resistivity in such a range is suitable as a cushioning material or a packaging material for electronic parts and devices because static electricity charged on an object to be packaged or the like can be easily eliminated.
- the surface resistivity of the multilayer foamed sheet is more preferably 5 ⁇ 106 ⁇ or less.
- the method for measuring the surface resistivity of the multilayer foam sheet shall be a measurement method based on JIS K6271-1: 2015. Specifically, first, a test piece having a square shape with a side of 100 mm is collected from the multilayer foam sheet. After the electrodes are attached to the surface of the test piece on the side having the conductive layer, a voltage of 1 V is applied between the electrodes in an atmosphere having a temperature of 23 ° C. and a relative humidity of 50%. Then, the surface resistivity (unit: ⁇ ) at the time when 1 minute has passed after the voltage is applied is defined as the surface resistivity of the multilayer foam sheet.
- the polyethylene-based resin foam layer is a foam using the polyethylene-based resin (A) as a base resin.
- the polyethylene-based resin refers to a resin containing 50 mol% or more of structural units derived from ethylene.
- the polyethylene-based resin (A) include polyethylene such as high-density polyethylene (that is, HDPE), low-density polyethylene (that is, LDPE), linear low-density polyethylene (that is, LLDPE), and ethylene-vinyl acetate.
- An ethylene-based copolymer or the like containing 50 mol% or more of a structural unit derived from polyethylene such as a polymer (that is, EVA) can be used.
- the low-density polyethylene exemplified as the polyethylene-based resin (A) refers to a polyethylene having a long-chain branched structure and a density of 910 kg / m 3 or more and less than 930 kg / m 3 , and is referred to as a linear low-density polyethylene.
- polyethylene which is a copolymer of ethylene and ⁇ -olefin having 4 to 8 carbon atoms, has a substantially linear molecular chain, and has a density of 910 kg / m 3 or more and less than 930 kg / m 3 .
- the high-density polyethylene is an ethylene homopolymer or a copolymer of ethylene and ⁇ -olefin having 4 to 8 carbon atoms, and refers to polyethylene having a density of 930 kg / m 3 or more.
- the polyethylene-based resin foam layer may contain one type of polyethylene-based resin (A) selected from the group consisting of an ethylene homopolymer and an ethylene-based copolymer, or two or more types of polyethylene-based resin. (A) may be included.
- the polyethylene-based resin (A) preferably contains 60 mol% or more of structural units derived from ethylene, and more preferably 70 mol% or more.
- the polyethylene-based resin foamed layer contains 50% by mass or more of low-density polyethylene as the polyethylene-based resin (A). It is more preferable that it is contained in an amount of 80% by mass or more, further preferably 90% by mass or more, that is, 100% by mass, that is, the base resin of the polyethylene-based resin foam layer is contained only from low-density polyethylene. Is particularly preferred.
- the melting point Tm A of the polyethylene resin (A) is preferably 100 ° C. or higher and 135 ° C. or lower. By setting the melting point Tm A of the polyethylene resin (A) to the above range, it is possible to stably form a foam layer having excellent extrusion foamability and excellent cushioning property. From this point of view, the melting point TmA of the polyethylene resin ( A ) is preferably 100 ° C. or higher and 130 ° C. or lower, more preferably 105 ° C. or higher and 120 ° C. or lower, and 108 ° C. or higher and 115 ° C. or lower. Is even more preferable.
- the melting point Tm A of the polyethylene resin (A) can be measured by the transition temperature measuring method for plastics specified in JIS K7121: 2012. First, the state of the test piece is adjusted by setting the heating rate and the cooling rate to 10 ° C./min according to "when measuring the melting temperature after performing a certain heat treatment". After that, the heating rate is set to 10 ° C./min, heat flux DSC (that is, differential scanning calorimetry) is performed, and a DSC curve is acquired. The apex temperature of the endothermic peak in the obtained DSC curve is taken as the melting point. When a plurality of endothermic peaks appear on the DSC curve, the peak temperature of the melting peak having the largest area is used as the melting point with reference to the baseline on the high temperature side.
- heat flux DSC that is, differential scanning calorimetry
- melt flow rate (MFR) of the polyethylene resin (A) is excellent in extrusion foamability, it is preferably 0.5 g / 10 minutes or more and 15 g / 10 minutes or less, and 1 g / 10 minutes or more and 8 g / 10 minutes or less. It is more preferably 1.5 g / 10 minutes or more, and further preferably 5 g / 10 minutes or less.
- the MFR of the polyethylene-based resin in the present specification is a value measured under the conditions of a test temperature of 190 ° C. and a load of 2.16 kg based on JIS K7210-1: 2014.
- the polyethylene-based resin foam layer may contain a polymer other than the polyethylene-based resin (A) as the base resin as long as the above-mentioned action and effect are not impaired.
- the polymer other than the polyethylene-based resin (A) include thermoplastic resins such as polystyrene-based resins and elastomers such as ethylene propylene rubber and styrene-butadiene-styrene block copolymers.
- the content of the polymer other than the polyethylene resin (A) in the polyethylene resin foam layer is preferably 20 parts by mass or less with respect to 100 parts by mass of the polyethylene resin (A), and is preferably 10 parts by mass or less.
- the polyethylene-based resin foam layer contains only the polyethylene-based resin (A) as a polymer component constituting the foamed layer. ..
- the polyethylene-based resin foam layer may contain additives such as a bubble regulator, an antioxidant, a heat stabilizer, a weather resistant agent, an ultraviolet absorber, a flame retardant, a filler, and an antibacterial agent.
- the blending amount of the additive in the polyethylene-based resin foam layer is, for example, preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the polyethylene-based resin (A), and 3 It is more preferably less than or equal to parts by mass.
- the conductive layer is laminated on one side or both sides of the polyethylene-based resin foam layer.
- the base resin of the conductive layer is a mixed resin of polyethylene (B) and an ethylene-based copolymer (C).
- the conductive layer is preferably in a non-foamed state from the viewpoint of improving the conductivity, handleability, and appearance of the multilayer foamed sheet. However, a small amount of very small bubbles may be contained in the conductive layer as long as the handleability of the multilayer foamed sheet is not impaired.
- the conductive layer contains one or more polyethylenes (B) selected from the group consisting of low density polyethylene and linear low density polyethylene.
- the low-density polyethylene exemplified as polyethylene (B) means a polyethylene having a long-chain branched structure and a density of 910 kg / m 3 or more and less than 930 kg / m 3
- the linear low-density polyethylene means ethylene and carbon.
- polyethylene (B) is preferably low-density polyethylene.
- the melting point Tm B of polyethylene (B) is preferably 100 ° C. or higher and 120 ° C. or lower, and more preferably 102 ° C. or higher and 115 ° C. or lower.
- the conductive layer can be stably laminated and adhered to the polyethylene-based resin foam layer even when the multilayer foamed sheet is manufactured by coextrusion.
- the method for measuring the melting point Tm B of polyethylene (B) is the same as the method for measuring the melting point Tm A of the polyethylene resin (A) described above.
- the melt flow rate of polyethylene (B) at a temperature of 190 ° C. and a load of 2.16 kg is preferably 5 g / 10 minutes or more and 80 g / 10 minutes or less, and more preferably 10 g / 10 minutes or more and 65 g / 10 minutes or less. , 12 g / 10 minutes or more and 50 g / 10 minutes or less is more preferable.
- the ethylene-based copolymer (C) in the conductive layer has at least a structural unit derived from ethylene and a structural unit derived from a monomer having a polar group.
- the ethylene-based copolymer (C) may be, for example, a copolymer of ethylene and a monomer having a polar group, or a copolymer of ethylene, a monomer having a polar group, and a monomer other than these monomers. It may be a coalescence.
- the amount of the structural unit derived from the other monomer contained in the ethylene-based copolymer (C) is preferably 10% by mass or less, more preferably 5% by mass or less, and 3% by mass or less. It is more preferable that the content is 0% by mass, that is, the ethylene-based copolymer (C) is a copolymer of ethylene and a monomer having a polar group.
- the multilayer foamed sheet has conductivity by using a mixed resin of polyethylene (B) and an ethylene-based copolymer (C) as the base resin of the conductive layer, and the conductive carbon from the multilayer foamed sheet. Dropping can be reduced. The reason is not always clear at this time, but it is thought to be as follows.
- conductive carbon when conductive carbon is dispersed in a thermoplastic resin such as a polyethylene resin, adjacent conductive carbon particles are present in close proximity to each other within a certain distance, so that the conductive network is formed by the conductive carbon particles. Is formed and conductivity is developed.
- a thermoplastic resin such as a polyethylene resin
- the polyethylene (B) and the ethylene-based copolymer (C) are incompatible with each other, a phase mainly composed of polyethylene (B) and a phase mainly composed of polyethylene (B) are mainly contained in the conductive layer.
- a phase composed of the ethylene-based copolymer (C) is formed.
- the conductive carbon is unevenly distributed in one of the phase composed of polyethylene (B) and the phase composed of the ethylene-based copolymer (C). ..
- the conductive carbon is unevenly distributed in any of the phases, it becomes easy to form a conductive network by the conductive carbon particles. As a result, it is considered that conductivity is likely to be exhibited even if the blending amount of the conductive carbon is small.
- the conductive carbon when the conductive carbon is unevenly distributed in either one of the phase made of polyethylene (B) and the phase made of an ethylene-based copolymer (C), the conductive carbon exposed on the surface of the conductive layer The amount can be reduced. This is considered to prevent the conductive carbon from falling off from the multilayer foamed sheet. As a result, the conductive carbon that has fallen off from the multilayer foamed sheet is transferred to the packaged object, and it is possible to prevent the packaged object from being contaminated.
- Examples of the ethylene-based copolymer (C) include an ethylene-vinyl acetate copolymer (that is, EVA), an ethylene-methyl methacrylate copolymer (that is, EMMA), and an ethylene-methyl acrylate copolymer (that is, that is). , EMA), ethylene-methacrylic acid copolymer (ie EMAA), ethylene-acrylic acid copolymer (ie EAA), ethylene-ethyl methacrylate copolymer (ie EEMA), ethylene-ethyl acrylate copolymer Examples include polymers (ie, EEA), ethylene-butyl acrylate copolymers (ie, EBA) and the like.
- the conductive layer is selected from the group consisting of an ethylene-vinyl acetate copolymer and an ethylene-methyl methacrylate copolymer. It is preferable that one or more kinds of ethylene-based copolymers (C) are contained, and more preferably, an ethylene-vinyl acetate copolymer is contained.
- the content of the structural unit derived from the monomer having a polar group in the ethylene-based copolymer (C) is preferably 30% by mass or more and 50% by mass or less.
- the content of the structural unit derived from the monomer having a polar group in the ethylene-based copolymer (C) is more preferably more than 30% by mass, more preferably 35% by mass or more. It is more preferably 40% by mass or more, and most preferably more than 40% by mass.
- the handleability of the multilayer foamed sheet is further improved, and the conductive layer is made of polyethylene. It is possible to further improve the manufacturing stability when laminating on the based resin foam layer.
- the content of the structural unit derived from the monomer having a polar group in the ethylene-based copolymer (C) is more preferably 48% by mass or less, and 45% by mass or less. Is more preferable.
- the melting point Tm C of the ethylene-based copolymer (C) is preferably 30 ° C. or higher and 80 ° C. or lower, more preferably 32 ° C. or higher and 75 ° C. or lower, and further preferably 35 ° C. or higher and 70 ° C. or lower. preferable.
- the method for measuring the melting point Tm C of the ethylene-based copolymer (C) is the same as the method for measuring the melting point Tm A of the polyethylene-based resin (A) described above.
- the difference between the melting point Tm B of polyethylene (B) and the melting point Tm C of the ethylene-based copolymer (C) Tm B ⁇ Tm C is 30 ° C. or higher and 80 ° C. or lower.
- the melting point difference Tm B ⁇ Tm C is less than 30 ° C., sufficient conductivity may not be imparted to the multilayer foamed sheet. Further, when the melting point difference Tm B ⁇ Tm C exceeds 80 ° C., the ethylene-based copolymer (C) easily adheres to the sizing device or the like in the manufacturing process of the multilayer foamed sheet, and a good multilayer foamed sheet is obtained. It may be difficult. Further, in this case, the ethylene-based copolymer (C) may be softened during use, or the multilayer foamed sheets may be fused to each other when stored in a state where the multilayer foamed sheets are stacked. There is a risk that the sex will be impaired.
- the melt flow rate of the ethylene-based copolymer (C) at a temperature of 190 ° C. and a load of 2.16 kg is preferably 10 g / 10 minutes or more and 120 g / 10 minutes or less, and 20 g / 10 minutes or more and 80 g / 10 minutes or less. Is more preferable. In this case, the conductivity of the multilayer foam sheet can be further improved. Further, by setting the melt flow rate of the ethylene-based copolymer (C) to the above-mentioned specific range, the adhesive strength between the conductive layer and the layer adjacent to the conductive layer can be further increased. For example, when the conductive layer and the polyethylene-based resin foam layer are laminated and bonded, the adhesive strength between the two can be further increased.
- the conductive layer contains conductive carbon, that is, a substance mainly composed of carbon atoms and having conductivity.
- conductive carbon black such as furnace black, acetylene black, thermal black, and Ketjen black is preferably exemplified.
- the conductive layer may contain two or more types of conductive carbon. From the viewpoint of further reducing the blending amount of conductive carbon while ensuring the conductivity of the multilayer foam sheet, the conductive layer contains highly conductive carbon black such as Ketjen black as the conductive carbon. Is preferable.
- the amount of dibutyl phthalate (DBP) oil absorbed by the conductive carbon is preferably 150 mL / 100 g or more and 700 mL / 100 g or less.
- the conductivity of the multilayer foam sheet can be further enhanced.
- the DBP oil absorption amount of the conductive carbon is more preferably 200 mL / 100 g or more and 600 mL / 100 g or less, and further preferably 300 mL / 100 g or more and 600 mL / 100 g or less. ..
- the above-mentioned dibutyl phthalate (DBP) oil absorption is a value measured according to ASTM D2414-79.
- the BET specific surface area of the conductive carbon is preferably 600 m 2 / g or more and 2000 m 2 / g or less.
- the conductivity of the multilayer foam sheet can be further enhanced.
- the BET specific surface area of the conductive carbon is more preferably 700 m 2 / g or more and 1600 m 2 / g or less.
- polyethylene is used in the multilayer foamed sheet of the present invention. Highly conductive carbon having a large specific surface area can be blended without inhibiting the foamability of the foamed resin layer.
- the blending amount of the conductive carbon in the conductive layer is 3% by mass or more and 15% by mass or less.
- the blending amount of the conductive carbon in the conductive layer is preferably 4% by mass or more, and more preferably 5% by mass or more. If the blending amount of the conductive carbon in the conductive layer is too small, it becomes difficult to form a conductive network by the conductive carbon particles in the conductive layer, which may lead to a decrease in the conductivity of the multilayer foamed sheet.
- the blending amount of the conductive carbon is substantially equal to the content of the conductive carbon in the conductive layer in the multilayer foamed sheet.
- the blending amount of the conductive carbon is preferably 12% by mass or less, more preferably 10% by mass or less, and 10% by mass. It is more preferably less than. If the amount of the conductive carbon blended in the conductive layer is too large, the conductive carbon tends to fall off from the multilayer foamed sheet, which may cause contamination around the multilayer foamed sheet.
- the conductive layer may contain a polymer other than polyethylene (B) and the ethylene-based copolymer (C) as long as the above-mentioned effects are not impaired.
- the polymer other than polyethylene (B) and the ethylene-based copolymer (C) include thermoplastic resins such as polyethylene-based resins and polystyrene-based resins other than polyethylene (B), ethylene propylene rubber and styrene-butadiene.
- -Examples include elastomers such as styrene block copolymers.
- the conductive layer contains a polymer having a higher melting point than the polyethylene-based resin (A) contained in the polyethylene-based resin foam layer. It is preferable not to.
- the content of the polymer other than polyethylene (B) and the ethylene-based copolymer (C) in the conductive layer is preferably 20% by mass or less, more preferably 10% by mass or less, and 5% by mass. It is more preferably% or less, and particularly preferably 3% by mass or less.
- the conductive layer may contain additives such as antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, fillers and antibacterial agents.
- the blending amount of the additive in the conductive layer is preferably 10 parts by mass or less, preferably 5 parts by mass or less, based on 100 parts by mass of the total of polyethylene (B) and the ethylene-based copolymer (C). More preferably, it is more preferably 3 parts by mass or less.
- the average thickness of the conductive layer is preferably 1 ⁇ m or more and 20 ⁇ m or less.
- the average thickness of the conductive layer is preferably 1 ⁇ m or more, more preferably 3 ⁇ m or more, still more preferably 5 ⁇ m or more.
- the conductivity of the multilayer foamed sheet can be exhibited more stably.
- the average thickness of the conductive layer is set to 20 ⁇ m or less, more preferably 18 ⁇ m or less, further preferably 15 ⁇ m or less, and particularly preferably 10 ⁇ m or less, the detachment of the conductive carbon from the multilayer foamed sheet is more effectively suppressed. be able to.
- the method for measuring the average thickness of the conductive layer is as follows. First, the multilayer foam sheet is cut in a plane perpendicular to the extrusion direction. In this cut surface, 10 measurement positions are set so as to divide the length of the cut surface in the longitudinal direction (that is, the direction perpendicular to both the extrusion direction and the thickness direction) into 11 equal parts. The cross section of the multilayer foam sheet at these measurement positions is observed using a microscope, and the thickness of the conductive layer at each measurement position is measured. The arithmetic mean value of these thicknesses is taken as the average thickness (unit: ⁇ m) of the conductive layer.
- the basis weight of the conductive layer is preferably 1 g / m 2 or more and 20 g / m 2 or less.
- the basis weight of the conductive layer is preferably 1 g / m 2 or more and 20 g / m 2 or less.
- the conductivity of the multilayer foamed sheet can be more stably expressed. ..
- the basis weight of the conductive layer to 20 g / m 2 or less, more preferably 18 g / m 2 or less, further preferably 15 g / m 2 or less, and particularly preferably 10 g / m 2 or less. It is possible to more effectively suppress the dropout of the conductive carbon.
- the basis weight of the conductive layer means the basis weight per one side.
- the method for measuring the basis weight of the conductive layer per one side is as follows. First, the average thickness of the conductive layer is calculated by the method described above. After converting the unit of this average thickness, the basis weight of the conductive layer (unit: g / m 2 ) can be obtained by multiplying by the density of the conductive layer (unit: g / m 3 ).
- the density of the conductive layer is a density including conductive carbon and other additives contained in the conductive layer.
- the discharge amount of the conductive layer per one side is X [g / hour]
- the width of the multilayer foamed sheet is W [m]
- the take-up speed of the multilayer foamed sheet is L [m / hour].
- Basis weight of conductive layer [g / m 2 ] [X / (L ⁇ W)] ... (1)
- a multilayer foam sheet is produced by co-extruding a melt for forming a conductive layer and a melt for forming a foam layer, a conductive layer having a small basis weight and a thin thickness that cannot be formed by thermal lamination or the like. While forming a layer, it is possible to stably develop conductivity.
- the multilayer foamed sheet can be produced, for example, by a coextrusion foaming method. That is, in the method for producing a polyethylene-based resin multilayer foamed sheet, a foam layer-forming melt for forming a polyethylene-based resin foam layer and a conductive layer-forming melt for forming a conductive layer are co-extruded. Thereby, a polyethylene-based resin multilayer foamed sheet having a polyethylene-based resin foamed layer and a conductive layer laminated on at least one side of the polyethylene-based resin foamed layer is produced.
- the foam layer forming melt contains a polyethylene resin (A) and a physical foaming agent.
- the melt for forming a conductive layer contains polyethylene (B), an ethylene-based copolymer (C) having a structural unit derived from ethylene and a structural unit derived from a monomer having a polar group, and conductive carbon. is doing.
- the blending amount of the conductive carbon in the melt for forming the conductive layer is 3% by mass or more and 15% by mass or less.
- the difference Tm B ⁇ Tm C between the melting point Tm B of polyethylene (B) and the melting point Tm C of the ethylene-based copolymer (C) is 30 ° C. or higher and 80 ° C. or lower.
- a known coextrusion device used in the field of extrusion foaming can be used. More specifically, for example, an extruder for forming a foam layer configured to be able to extrude a melt for forming a foam layer, and an extruder for forming a conductive layer configured to be able to extrude a melt for forming a conductive layer.
- the multilayer foam sheet can be manufactured by using a coextrusion device provided with a coextrusion die to which the discharge port of these extruders is connected.
- the foam layer forming melt contains at least a polyethylene-based resin (A) and a physical foaming agent.
- the foam layer forming melt can be produced, for example, by the following method. First, the polyethylene-based resin (A) and an additive added as needed are supplied to the extruder for forming a foam layer, and melt-kneaded. Next, the melt containing the polyethylene-based resin (A) melted in the extruder is supplied with a physical foaming agent while being pressurized and further kneaded to obtain a melt for forming a foam layer.
- an organic physical foaming agent or an inorganic physical foaming agent can be used as the physical foaming agent.
- the organic physical foaming agent include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane and isohexane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and methyl chloride and ethyl chloride. Hydrocarbons such as 1,1,1,2-tetrafluoroethane, fluorinated hydrocarbons such as 1,1-difluoroethane and the like can be mentioned.
- the inorganic physical foaming agent include nitrogen, carbon dioxide, air, and water.
- the melt for forming a foam layer may contain one kind of physical foaming agent, or may contain two or more kinds of physical foaming agents.
- the melt for forming the foam layer contains an organic physical foaming agent as a physical foaming agent, and normal butane, It is more preferable that an organic physical foaming agent containing isobutane or a mixture thereof as a main component is contained.
- the blending amount of the physical foaming agent can be appropriately set according to the type of foaming agent, the desired apparent density, and the like.
- a mixed butane composed of 30% by mass of isobutane and 70% by mass of normal butane is used as a physical foaming agent, 3 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polyethylene resin (A). It is preferable to add 4 parts by mass or more and 20 parts by mass or less, and more preferably 10 parts by mass or more and 20 parts by mass or less of mixed butane.
- a bubble adjusting agent it is preferable to add a bubble adjusting agent to the melt for forming the foam layer.
- an inorganic bubble adjusting agent or an organic bubble adjusting agent can be used.
- the inorganic bubble adjusting agent include boric acid metal salts such as zinc borate, magnesium borate, and borosand, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, and sodium bicarbonate.
- the organic bubble adjusting agent include sodium 2,2-methylenebis (4,6-tert-butylphenyl) phosphate, sodium benzoate, aluminum benzoate, sodium stearate and the like.
- the foam layer forming melt may contain one kind of bubble adjusting agent or two or more kinds of bubble adjusting agents.
- the blending amount of the bubble adjusting agent in the foam layer forming melt may be appropriately set according to the type of the physical foaming agent, the desired apparent density, the bubble diameter and the like.
- the melt for forming the conductive layer contains at least polyethylene (B), an ethylene-based copolymer (C), and conductive carbon.
- the polyethylene (B), the ethylene-based copolymer (C), the conductive carbon and an additive added as necessary are added to the extruder for forming the conductive layer. Supply. Then, by melt-kneading these in an extruder, a melt for forming a conductive layer can be obtained.
- the melt for forming the conductive layer may contain a volatile plasticizer as an additive.
- the volatile plasticizer has an effect of lowering the melt viscosity of the melt for forming the conductive layer, and is configured to volatilize from the conductive layer after coextrusion.
- the volatile plasticizer can bring the extrusion temperature of the melt for forming the conductive layer close to the extrusion temperature of the melt for forming the foam layer during coextrusion. Further, the volatile plasticizer can improve the melt elongation of the conductive layer in the softened state.
- the bubbles of the polyethylene-based resin foam layer are less likely to be destroyed by the heat of the conductive layer during the foaming of the melt for forming the foam layer. Further, the conductive layer tends to expand following the expansion of the foamed polyethylene resin foam layer.
- the volatile plastic agent examples include aliphatic hydrocarbons having 3 to 7 carbon atoms, alicyclic hydrocarbons having 3 to 7 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, and 2 to 8 carbon atoms.
- the following aliphatic ethers and the like can be mentioned.
- the melt for forming the conductive layer may contain one kind of volatile plasticizer, or may contain two or more kinds of volatile plasticizers.
- the boiling point of the volatile plasticizer is preferably 120 ° C. or lower, more preferably 80 ° C. or lower. Volatile plasticizers having a boiling point in such a range spontaneously volatilize from the conductive layer after coextrusion and are removed from the conductive layer.
- the lower limit of the boiling point of the volatile plasticizer is approximately ⁇ 50 ° C.
- the blending amount of the volatile plasticizer can be appropriately set according to the composition of the conductive layer and the polyethylene-based resin foam layer.
- the blending amount of the volatile plasticizer can be 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the total of polyethylene (B) and the ethylene-based copolymer (C).
- the blending amount of the volatile plasticizer is the total of polyethylene (B) and the ethylene-based copolymer (C). It is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and further preferably 10 parts by mass or more with respect to 100 parts by mass.
- the blending amount of the volatile plasticizer should be 50 parts by mass or less with respect to 100 parts by mass in total of the polyethylene (B) and the ethylene-based copolymer (C). Is more preferable, and it is more preferably 45 parts by mass or less, and further preferably 40 parts by mass or less.
- the foam layer forming melt and the conductive layer forming melt formed in each extruder are guided to the co-extrusion die and extruded in a layered manner from the extrusion port of the co-extrusion die.
- the coextrusion die may be, for example, a flat die with a linear extrusion port.
- a laminate of the foam layer forming melt and the conductive layer forming melt is extruded into a sheet shape from the extrusion port of the flat die.
- the foam layer forming melt expands while foaming. Along with this, the melt for forming the conductive layer is stretched.
- the sheet-shaped laminated foam extruded from the extrusion port is cooled while being taken up along the widening device to solidify the foam layer forming melt and the conductive layer forming melt. This fixes the bubble structure formed by foaming and stabilizes the dimensions. From the above, a multilayer foamed sheet can be obtained.
- the co-extrusion die may be, for example, an annular die provided with an annular extrusion port.
- a laminate of the foam layer forming melt and the conductive layer forming melt is extruded into a cylindrical shape from the extrusion port of the annular die.
- the foam layer forming melt expands while foaming.
- the melt for forming the conductive layer is stretched.
- the tubular laminated foam extruded from the extrusion port is widened from the inside with compressed air or the like, and the inside is cooled while being taken along with a widening device such as a mandrel to cool the melt for forming a foam layer.
- a multilayer foam sheet can be obtained by cutting open a tubular laminated foam on the widening device.
- an annular die is used as the coextrusion die, it is easy to manufacture a wide multilayer foam sheet having a width of, for example, 1000 mm or more. Further, it is easy to manufacture a thin foam sheet having an overall thickness of 3 mm or less, for example.
- the foam layer forming melt extruded from the coextrusion die rapidly expands due to foaming, so that the conductive layer forming melt is a foam layer. It is strongly stretched following the expansion of the forming melt. Since the conductive carbon particles in the conductive layer are separated from each other during this stretching, it tends to be difficult to maintain the conductive network if the blending amount of the conductive carbon is insufficient.
- the base resin of the conductive layer is likely to solidify in a state where the conductive carbon particles are separated from each other by stretching.
- the extrusion foaming temperature of the melt for forming the foam layer is set to a relatively low temperature in the range of 100 to 130 ° C., which is near the melting point of the polyethylene resin (A) constituting the polyethylene resin foam layer. Under the extrusion temperature conditions of the melt for forming the conductive layer set to a relatively low temperature corresponding to this, the base resin of the conductive layer is more likely to solidify. For these reasons, it is considered that it was difficult to stably form a conductive network in the conductive layer in the conventional multilayer foamed sheet produced by coextrusion.
- ethylene having the polyethylene (B), a structural unit derived from the ethylene, and a structural unit derived from a monomer having a polar group is provided in the conductive layer. It contains two kinds of resins that are incompatible with each other with the system copolymer (C). Therefore, it is considered that the conductive carbon is unevenly distributed in any phase in the multilayer foamed sheet. As a result, it is considered that the conductive network is easily formed by the conductive carbon particles and the conductive network is easily maintained.
- ethylene-based copolymer (C) a resin having a low melting point such that the melting point difference Tm B ⁇ Tm C from that of polyethylene (B) is within the specific range is used, so that after coextrusion, the resin is used.
- the stretching can be relaxed until the conductive layer solidifies.
- the conductive network is likely to be reconstructed.
- the above-mentioned manufacturing method it is possible to manufacture a multilayer foamed sheet having conductivity by coextrusion even if the blending amount of the conductive carbon is relatively small. Further, according to the above-mentioned manufacturing method, it is possible to easily obtain a multilayer foamed sheet having a thin thickness, excellent cushioning property, and low contamination with an object to be packaged.
- multilayer foam sheet Examples of the multilayer foam sheet and its manufacturing method will be described below.
- the specific embodiment of the multilayer foamed sheet and the method for producing the same according to the present invention is not limited to the embodiments shown below, and the configuration may be appropriately changed as long as the gist of the present invention is not impaired. Can be done.
- the melting point of each resin in Table 1 is a value measured by the above-mentioned method, that is, the transition temperature measuring method of plastic specified in JIS K7121: 2012.
- the melt flow rate measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kg based on the method specified in JIS K7210-1 (2014) is described.
- Table 2 shows the physical characteristics of conductive carbon.
- the porosity is a value obtained by dividing the bulk density of the conductive carbon by the true density of the conductive carbon.
- the primary particle size is a value obtained by observation with a transmission electron microscope.
- the DBP oil absorption amount is a value measured according to ASTM D 2414-79.
- the BET specific surface area is a value obtained in accordance with ASTM D 2414.
- CB1 in Table 2 is specifically "Ketchen Black EC300J" manufactured by Lion Specialty Chemicals Co., Ltd.
- the multilayer foamed sheets of Examples 1 to 8 have a three-layer structure composed of a polyethylene-based resin foamed layer containing the polyethylene-based resin (A) and conductive layers laminated on both sides of the polyethylene-based resin foamed layer. It is a non-crosslinked multilayer foam sheet.
- the conductive layer contains polyethylene (B) of the type and amount shown in Table 3, an ethylene-based copolymer (C), and conductive carbon.
- the method for producing the multilayer foamed sheet of Examples 1 to 8 is as follows. First, a coextrusion device including an extruder for forming a foam layer, an extruder for forming a conductive layer, and a coextrusion die to which the discharge ports of these extruders are connected is prepared.
- the coextrusion die in this example is an annular die having an annular extrusion port.
- the foam layer forming extruder was used in an extruder of 1 part by mass with respect to the polyethylene resin (A) of the type shown in Table 3 and 100 parts by mass of the polyethylene resin (A). And the bubble conditioner was supplied, and these were melt-kneaded in the extruder.
- the bubble adjusting agent a mixture of citric acid and baking soda (“Finecell Master PO217K” manufactured by Dainichiseika Kogyo Co., Ltd.) was used.
- “Fine Cell Master” is a registered trademark of Dainichiseika Kogyo Co., Ltd.
- the physical foaming agent was supplied under pressure to the mixture of the polyethylene resin (A) melted in the extruder and the bubble adjusting agent, and further kneaded in the extruder. From the above, a melt for forming a foam layer having an extrusion temperature shown in Table 3 was obtained.
- the physical foaming agent mixed butane composed of 65% by mass of normal butane and 35% by mass of isobutane was used. The blending amount of the physical foaming agent was 8 parts by mass with respect to 100 parts by mass of the polyethylene resin (A).
- the polyethylene (B), the ethylene-based copolymer (C), and the conductive carbon shown in Table 3 are supplied to the extruder for forming the conductive layer, and the polyethylene is supplied to the extruder.
- 25 parts by mass of the volatile plasticizer was supplied to 100 parts by mass of the total of polyethylene (B) and the ethylene-based copolymer (C). Then, by kneading these in an extruder, a melt for forming a conductive layer having an extrusion temperature shown in Table 3 was obtained.
- the volatile plasticizer mixed butane composed of 65% by mass of normal butane and 35% by mass of isobutane was used.
- the melt thus produced in each extruder is supplied to the co-extrusion die at the same time while maintaining the extrusion temperature shown in Table 3, and conductive layers are formed on both sides of the melt for forming the foam layer in the co-extrusion die.
- the melts were merged so that they could be laminated.
- a tubular laminated foam in which conductive layers are laminated on both sides of the polyethylene-based resin foam layer is formed.
- the discharge amount of the conductive layer shown in Table 3 is the discharge amount per one side.
- a mandrel having a diameter of 360 mm is inserted inside the laminated foam, and the laminated foam is taken up along the mandrel at the take-up speed shown in Table 3, and the laminated foam is cut open to form the multilayer foam of Examples 1 to 8.
- the width, total thickness, basis weight, and apparent density of the multilayer foam sheets of Examples 1 to 8 were the values shown in Table 3.
- the conductive layers of these multilayer foamed sheets were all in a non-foamed state.
- the multilayer foamed sheet of Comparative Example 1 is the same as the multilayer foamed sheet of Example 1 except that the conductive layer does not contain the ethylene-based copolymer (C).
- the method for producing the multilayer foamed sheet of Comparative Example 1 was Example 1 except that the ethylene-based copolymer (C) was not blended in the melt for forming the conductive layer and the production conditions and the like were changed as shown in Table 4. This is the same as the method for producing the multilayer foam sheet of.
- the multilayer foamed sheet of Comparative Example 3 has the same configuration as that of the multilayer foamed sheet of Example 1 except that the conductive layer contains linear polyethylene instead of the ethylene-based copolymer (C). ing.
- the method for producing the multilayer foamed sheet of Comparative Example 3 is the same as the method for producing the multilayer foamed sheet of Example 1 except that the composition and production conditions of the melt for forming the conductive layer are changed as shown in Table 4.
- the multilayer foamed sheet of Comparative Example 5 has the same configuration as that of the multilayer foamed sheet of Comparative Example 1 except that the amount of the conductive carbon in the conductive layer was increased.
- the multilayer foamed sheet of Comparative Example 1 was produced except that the blending amount of the conductive carbon in the melt for forming the conductive layer and the production conditions were changed to the values shown in Table 4. Similar to the method.
- melt viscosity of the conductive layer of the multilayer foamed sheet of Examples and Comparative Examples By the following methods, the melt viscosity of the conductive layer of the multilayer foamed sheet of Examples and Comparative Examples, the total thickness and basis weight of the multilayer foamed sheet, the average thickness and basis weight of the conductive layer of the multilayer foamed sheet, the apparent density, the foaming ratio, Contamination and conductivity were evaluated.
- melt viscosity of conductive layer Using a capillary rheometer (“Leobis 2100” manufactured by Chiast), the melt viscosities of the melts for forming a conductive layer in each of Examples 1 to 8 and Comparative Examples 1 to 5 were measured.
- the orifice diameter of the capillary rheometer was 1 mm, the orifice length was 10 mm, and the measurement was performed under the conditions of a measurement temperature of 190 ° C. and a shear rate of 100 sec -1 .
- the melt viscosities of the melts for forming the conductive layer in Examples and Comparative Examples were as shown in Table 3 or Table 4.
- the multilayer foam sheet was cut in a plane perpendicular to the extrusion direction.
- 10 measurement positions were set so that the intervals in the longitudinal direction of the cut surface (that is, the direction perpendicular to both the extrusion direction and the thickness direction) were equal. These measurement positions were observed using a microscope, and the thickness of each measurement position was measured. The arithmetic mean value of these thicknesses is taken as the total thickness of the multilayer foamed sheet and is shown in Tables 3 and 4.
- Basis weight of multi-layer foam sheet A square test piece having a side of 25 mm was collected from the multilayer foam sheet, and the mass (unit: g) of the test piece was measured. By converting the mass of this test piece into a unit, the basis weight of the multilayer foamed sheet, that is, the mass per 1 m 2 of the multilayer foamed sheet (unit: g / m 2 ) was calculated.
- the basis weight of the multilayer foam sheets of Examples and Comparative Examples was as shown in Table 3 or Table 4.
- the multilayer foam sheet was cut in a plane perpendicular to the extrusion direction. In this cut surface, 10 measurement positions were set so that the intervals in the longitudinal direction of the cut surface (that is, the direction perpendicular to both the extrusion direction and the thickness direction) were equal. The cross section of the multilayer foam sheet at these measurement positions was observed using a microscope, and the thickness of the conductive layer at each measurement position was measured. The arithmetic mean value of these thicknesses was taken as the average thickness (unit: ⁇ m) of the conductive layer. The average thickness of the conductive layer in the multilayer foamed sheets of Examples and Comparative Examples was as shown in Table 3 or Table 4.
- the apparent density of the multi-layer foam sheet (unit: kg / m 3 ) is obtained by dividing the basis weight (unit: g / m 2 ) of the multi-layer foam sheet obtained by the above method by the total thickness of the multi-layer foam sheet and then converting the unit. ) was calculated.
- the multilayer foam sheet was removed from the clean paper 100 seconds after the start of sliding. Then, the color tone of the clean paper was measured using a spectrocolorimeter (“SE-2000” manufactured by Nippon Denshoku Industries Co., Ltd.), and in the CIE 1976 L * a * b * color space of the part sliding with the multilayer foam sheet. The L * value was acquired. Then, the contamination property of the multilayer foamed sheet was evaluated based on the difference between the L * value of the clean paper before sliding with the multilayer foamed sheet and the L * value of the clean paper after sliding, which was measured in advance.
- SE-2000 spectrocolorimeter
- the ⁇ L * value which is the value obtained by subtracting the L * value of the clean paper after sliding from the L * value of the clean paper before sliding, is described.
- the L * value is a value indicating lightness, and the larger the value, the brighter the color tone.
- the surface resistivity of the conductive layer was measured by a measuring method based on JIS K6271-1: 2015. Specifically, a test piece having a square shape with a side of 100 mm was collected from the multilayer foam sheet. After the electrodes were attached to the surface of the conductive layer in this test piece, a voltage of 1 V was applied between the electrodes in an atmosphere having a temperature of 23 ° C. and a relative humidity of 50%. Then, the surface resistivity (unit: ⁇ ) at the time when 1 minute passed after the voltage was applied was defined as the surface resistivity of the multilayer foam sheet. For the measurement of surface resistivity, "High Resta UX MCP-HT800" manufactured by Nittoseiko Analytech Co., Ltd. was used. The surface resistivity in the multilayer foam sheets of Examples and Comparative Examples was as shown in Table 3 or Table 4.
- the conductive layer in the multilayer foamed sheets of Examples 1 to 8 includes polyethylene (B), a structural unit derived from ethylene, and a structural unit derived from a monomer having a polar group. It contains an ethylene-based copolymer (C) and conductive carbon. Further, in the conductive layer of the multilayer foamed sheet of Examples 1 to 8, the blending amount of the conductive carbon and the melting point difference Tm B ⁇ Tm C between the polyethylene (B) and the ethylene-based copolymer (C) are the above-mentioned specific. It is a range. Then, in Examples 1 to 8, the conductive layer having such a structure is laminated and adhered to the polyethylene-based resin foam layer by coextrusion.
- the multilayer foam sheets of Examples 1 to 8 have a surface resistivity of 1 ⁇ 10 7 ⁇ or less, and can reduce the loss of conductive carbon from the multilayer foam sheets.
- the multilayer foamed sheet having the conductive layer having the specific composition is excellent even if the amount of the conductive carbon in the conductive layer is 10% by mass or less, which is a relatively small amount. It can be understood that it shows conductivity. Further, for example, from the comparison between Example 1 and Comparative Example 1 and Example 4 and Comparative Example 4 in which the blending amount of the conductive carbon in the conductive layer is about the same, a multilayer having the conductive layer having the specific composition. It can be understood that the foamed sheet has a small ⁇ L * value and can reduce contamination to the surroundings.
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Abstract
Description
前記ポリエチレン系樹脂発泡層の少なくとも片面側に積層された導電層と、を備え、
前記導電層が、
低密度ポリエチレン及び直鎖状低密度ポリエチレンからなる群より選択される1種または2種以上のポリエチレン(B)と、エチレンに由来する構造単位及び極性基を有するモノマーに由来する構造単位を備えたエチレン系共重合体(C)との混合樹脂と、
前記混合樹脂中に配合された導電性カーボンと、を含み、
前記導電層中における前記導電性カーボンの配合量が3質量%以上15質量%以下であり、
前記導電層に含まれる前記ポリエチレン(B)の融点TmBと、前記エチレン系共重合体(C)の融点TmCとの差TmB-TmCが30℃以上80℃以下である、ポリエチレン系樹脂多層発泡シートにある。
前記発泡層形成用溶融物が基材樹脂としてのポリエチレン系樹脂(A)及び物理発泡剤を混練してなり、
前記導電層形成用溶融物が、低密度ポリエチレン及び直鎖状低密度ポリエチレンからなる群より選択される1種または2種以上のポリエチレン(B)と、エチレンに由来する構造単位及び極性基を有するモノマーに由来する構造単位を備えたエチレン系共重合体(C)と、導電性カーボンと、を混練してなり、
前記導電層形成用溶融物中における前記導電性カーボンの配合量が3質量%以上15質量%以下であり、
前記ポリエチレン(B)の融点TmBと、前記エチレン系共重合体(C)の融点TmCとの差TmB-TmCが30℃以上80℃以下である、ポリエチレン系樹脂多層発泡シートの製造方法にある。
前記多層発泡シートは、ポリエチレン系樹脂発泡層と、ポリエチレン系樹脂発泡層の少なくとも片面側に積層された導電層とを含む2層以上の層を有している。多層発泡シートに含まれる各層は、隣り合う層に積層接着されている。多層発泡シートにおける各層は、隣り合う層と共押出により積層接着されていることが好ましい。
前記多層発泡シートの全体厚みは、0.05mm以上3.0mm以下であることが好ましい。多層発泡シートの全体厚みを0.05mm以上、より好ましくは0.1mm以上、さらに好ましくは0.2mm以上とすることにより、多層発泡シートの緩衝性をより高めることができる。また、多層発泡シートの全体厚みを3.0mm以下、より好ましくは2.0mm以下、さらに好ましくは1.5mm以下、特に好ましくは1.2mm以下とすることにより、多層発泡シートの取り扱い性をより高め、被包装物の梱包をより容易に行うことができる。
前記多層発泡シートの見掛け密度は30kg/m3以上150kg/m3以下であることが好ましい。多層発泡シートの見掛け密度を30kg/m3以上、より好ましくは35kg/m3以上、さらに好ましくは40kg/m3以上とすることにより、緩衝材や包装材として十分な強度を容易に確保することができる。また、多層発泡シートの見掛け密度を150kg/m3以下、より好ましくは120kg/m3以下、さらに好ましくは100kg/m3以下とすることにより、多層発泡シートの軽量性や柔軟性を十分に確保し、多層発泡シートの緩衝性をより高めることができる。
前記多層発泡シートにおける導電層を有する側の表面の表面抵抗率は1×103Ω以上1×107Ω以下であることが好ましい。かかる範囲の表面抵抗率を備えた多層発泡シートは、被包装物等に帯電した静電気を容易に除電できるため、電子部品や電子機器等の緩衝材や包装材として好適である。同様の観点から、前記多層発泡シートの表面抵抗率は5×106Ω以下であることがより好ましい。
ポリエチレン系樹脂発泡層は、ポリエチレン系樹脂(A)を基材樹脂とする発泡体である。
本明細書において、ポリエチレン系樹脂とは、エチレンに由来する構造単位を50モル%以上含む樹脂をいう。ポリエチレン系樹脂(A)としては、例えば、高密度ポリエチレン(つまり、HDPE)や低密度ポリエチレン(つまり、LDPE)、直鎖状低密度ポリエチレン(つまり、LLDPE)等のポリエチレンや、エチレン-酢酸ビニル共重合体(つまり、EVA)等のエチレンに由来する構造単位を50モル%以上含有するエチレン系共重合体等を使用することができる。
ポリエチレン系樹脂発泡層中には、前述した作用効果を損なわない範囲で、基材樹脂であるポリエチレン系樹脂(A)以外の他のポリマーが含まれていてもよい。ポリエチレン系樹脂(A)以外の他のポリマーとしては、例えば、ポリスチレン系樹脂等の熱可塑性樹脂や、エチレンプロピレンゴム、スチレン-ブタジエン-スチレンブロック共重合体等のエラストマー等が挙げられる。ポリエチレン系樹脂発泡層中のポリエチレン系樹脂(A)以外の他のポリマーの含有量は、ポリエチレン系樹脂(A)100質量部に対して20質量部以下であることが好ましく、10質量部以下であることがより好ましく、5質量部以下であることがさらに好ましく、0質量部、つまり、ポリエチレン系樹脂発泡層が発泡層を構成するポリマー成分としてポリエチレン系樹脂(A)のみを含むことが特に好ましい。
ポリエチレン系樹脂発泡層中には、気泡調整剤、酸化防止剤、熱安定剤、耐候剤、紫外線吸収剤、難燃剤、充填材、抗菌剤等の添加剤が含まれていてもよい。ポリエチレン系樹脂発泡層中の添加剤の配合量は、例えば、ポリエチレン系樹脂(A)100質量部に対して10質量部以下であることが好ましく、5質量部以下であることがより好ましく、3質量部以下であることがさらに好ましい。
導電層は、ポリエチレン系樹脂発泡層の片面または両面に積層されている。導電層の基材樹脂は、ポリエチレン(B)とエチレン系共重合体(C)との混合樹脂である。導電層は、多層発泡シートの導電性や取り扱い性、外観を向上させる観点から、非発泡状態であることが好ましい。ただし、多層発泡シートの取り扱い性等を損なわない範囲であれば、導電層中にごく微小な気泡が少量含まれていてもよい。
導電層には、低密度ポリエチレン及び直鎖状低密度ポリエチレンからなる群より選択される1種または2種以上のポリエチレン(B)が含まれている。ポリエチレン(B)として例示した低密度ポリエチレンとは、長鎖分岐構造を有し、密度が910kg/m3以上930kg/m3未満のポリエチレンをいい、直鎖状低密度ポリエチレンとは、エチレンと炭素数4~8のα-オレフィンとの共重合体であって、実質的に分子鎖が線状であり、密度が910kg/m3以上930kg/m3未満のポリエチレンをいう。これらの中でも、ポリエチレン(B)は、低密度ポリエチレンであることが好ましい。ポリエチレン(B)の融点TmBは、100℃以上120℃以下であることが好ましく、102℃以上115℃以下であることがより好ましい。ポリエチレン(B)の融点TmBが前記範囲内であると、多層発泡シートを共押出により製造する場合においても、導電層をポリエチレン系樹脂発泡層に安定して積層接着させることができる。なお、ポリエチレン(B)の融点TmBの測定方法は、前述したポリエチレン系樹脂(A)の融点TmAの測定方法と同様である。
導電層中のエチレン系共重合体(C)は、少なくとも、エチレンに由来する構造単位と、極性基を有するモノマーに由来する構造単位とを有している。エチレン系共重合体(C)は、例えば、エチレンと極性基を有するモノマーとの共重合体であってもよいし、エチレン、極性基を有するモノマー及びこれらのモノマー以外の他のモノマーの共重合体であってもよい。エチレン系共重合体(C)中に含まれる前記他のモノマーに由来する構造単位の量は、10質量%以下であることが好ましく、5質量%以下であることがより好ましく、3質量%以下であることがさらに好ましく、0質量%、すなわちエチレン系共重合体(C)がエチレンと極性基を有するモノマーとの共重合体であることが最も好ましい。
導電層中におけるポリエチレン(B)とエチレン系共重合体(C)との配合比率は、質量比においてポリエチレン(B):エチレン系共重合体(C)=80:20~20:80であることが好ましく、ポリエチレン(B):エチレン系共重合体(C)=50:50~25:75であることがより好ましく、ポリエチレン(B):エチレン系共重合体(C)=45:55~30:70であることがより好ましい。この場合には、多層発泡シートの導電性をより高めることができる。
導電層中には、導電性カーボン、つまり、主に炭素原子からなり、導電性を有する物質が含まれている。導電性カーボンとしては、具体的には、ファーネスブラックやアセチレンブラック、サーマルブラック、ケッチェンブラック等の導電性カーボンブラックが好ましく例示される。導電層中には、2種類以上の導電性カーボンが含まれていてもよい。多層発泡シートの導電性を確保しつつ導電性カーボンの配合量をより低減する観点からは、導電層中には、導電性カーボンとして、ケッチェンブラック等の高導電性カーボンブラックが含まれていることが好ましい。
導電層中には、前述した作用効果を損なわない範囲で、ポリエチレン(B)及びエチレン系共重合体(C)以外の他のポリマーが含まれていてもよい。ポリエチレン(B)及びエチレン系共重合体(C)以外の他のポリマーとしては、例えば、ポリエチレン(B)以外のポリエチレン系樹脂及びポリスチレン系樹脂等の熱可塑性樹脂や、エチレンプロピレンゴム及びスチレン-ブタジエン-スチレンブロック共重合体等のエラストマー等が挙げられる。ポリエチレン系樹脂発泡層に導電層を積層する際の製造安定性の観点からは、導電層中には、ポリエチレン系樹脂発泡層に含まれるポリエチレン系樹脂(A)よりも融点の高いポリマーが含まれていないことが好ましい。導電層中のポリエチレン(B)及びエチレン系共重合体(C)以外の他のポリマーの含有量は、20質量%以下であることが好ましく、10質量%以下であることがより好ましく、5質量%以下であることがさらに好ましく、3質量%以下であることが特に好ましい。
導電層中には、酸化防止剤、熱安定剤、耐候剤、紫外線吸収剤、難燃剤、充填材、抗菌剤等の添加剤が含まれていてもよい。導電層中の添加剤の配合量は、例えば、ポリエチレン(B)及びエチレン系共重合体(C)の合計100質量部に対して10質量部以下であることが好ましく、5質量部以下であることがより好ましく、3質量部以下であることがさらに好ましい。
導電層の平均厚みは、1μm以上20μm以下であることが好ましい。導電層の平均厚みを1μm以上、より好ましくは3μm以上、さらに好ましくは5μm以上とすることにより、多層発泡シートの導電性をより安定して発現させることができる。また、導電層の平均厚みを20μm以下、より好ましくは18μm以下、さらに好ましくは15μm以下、特に好ましくは10μm以下とすることにより、多層発泡シートからの導電性カーボンの脱落をより効果的に抑制することができる。
導電層の坪量は、1g/m2以上20g/m2以下であることが好ましい。導電層の坪量を1g/m2以上、より好ましくは5g/m2以上、さらに好ましくは7g/m2以上とすることにより、多層発泡シートの導電性をより安定して発現させることができる。また、導電層の坪量を20g/m2以下、より好ましくは18g/m2以下、さらに好ましくは15g/m2以下、特に好ましくは10g/m2以下とすることにより、多層発泡シートからの導電性カーボンの脱落をより効果的に抑制することができる。なお、導電層がポリエチレン系樹脂発泡層の両面に積層されている場合には、上記導電層の坪量は、片面当たりの坪量を意味する。
導電層の坪量[g/m2]=〔X/(L×W)〕・・・(1)
前記多層発泡シートは、例えば、共押出発泡法により製造することができる。すなわち、ポリエチレン系樹脂多層発泡シートの製造方法においては、ポリエチレン系樹脂発泡層を形成するための発泡層形成用溶融物と、導電層を形成するための導電層形成用溶融物とを共押出することにより、ポリエチレン系樹脂発泡層と、ポリエチレン系樹脂発泡層の少なくとも片面側に積層された導電層とを備えたポリエチレン系樹脂多層発泡シートを作製する。発泡層形成用溶融物はポリエチレン系樹脂(A)及び物理発泡剤を含有している。導電層形成用溶融物は、ポリエチレン(B)と、エチレンに由来する構造単位及び極性基を有するモノマーに由来する構造単位を備えたエチレン系共重合体(C)と、導電性カーボンとを含有している。導電層形成用溶融物中における導電性カーボンの配合量が3質量%以上15質量%以下である。そして、ポリエチレン(B)の融点TmBと、エチレン系共重合体(C)の融点TmCとの差TmB-TmCが30℃以上80℃以下である。
発泡層形成用溶融物には、少なくともポリエチレン系樹脂(A)及び物理発泡剤が含まれている。発泡層形成用溶融物は、例えば以下の方法により作製することができる。まず、発泡層形成用押出機に前記ポリエチレン系樹脂(A)及び必要に応じて添加される添加剤を供給し、溶融混練する。次いで、押出機内で溶融したポリエチレン系樹脂(A)を含む溶融物に物理発泡剤を加圧しつつ供給してさらに混練することにより、発泡層形成用溶融物を得ることができる。
導電層形成用溶融物には、少なくともポリエチレン(B)、エチレン系共重合体(C)及び導電性カーボンが含まれている。導電層形成用溶融物を作製するに当たっては、例えば、導電層形成用押出機に前記ポリエチレン(B)、エチレン系共重合体(C)、導電性カーボン及び必要に応じて添加される添加剤を供給する。そして、押出機内でこれらを溶融混練することにより、導電層形成用溶融物を得ることができる。
共押出を行うに当たっては、前述したように各押出機内で形成された発泡層形成用溶融物及び導電層形成用溶融物を共押出ダイに導き、共押出ダイの押出口から層状に押し出す。共押出ダイは、例えば、直線状の押出口を備えたフラットダイであってもよい。この場合には、フラットダイの押出口から、発泡層形成用溶融物と導電層形成用溶融物との積層体がシート状に押し出される。押出口から積層体が大気中に押し出されると、発泡層形成用溶融物が発泡しながら膨張する。これに伴い、導電層形成用溶融物が引き伸ばされる。そして、押出口から押し出されたシート状の積層発泡体を拡幅装置に沿わせて引き取りながら冷却することにより、発泡層形成用溶融物及び導電層形成用溶融物を固化させる。これにより、発泡によって形成された気泡構造が固定され、寸法が安定する。以上により、多層発泡シートを得ることができる。
実施例1~実施例8の多層発泡シートは、ポリエチレン系樹脂(A)を含むポリエチレン系樹脂発泡層と、ポリエチレン系樹脂発泡層の両面に積層された導電層と、からなる3層構造を有する無架橋の多層発泡シートである。導電層は、表3に示す種類及び量のポリエチレン(B)と、エチレン系共重合体(C)と、導電性カーボンとを含んでいる。
比較例1の多層発泡シートは、導電層中にエチレン系共重合体(C)が含まれていない以外は実施例1の多層発泡シートと同様である。比較例1の多層発泡シートの作製方法は、導電層形成用溶融物中にエチレン系共重合体(C)を配合せず、製造条件等を表4に示すように変更した以外は実施例1の多層発泡シートの作製方法と同様である。
比較例2及び比較例4の多層発泡シートは、導電層におけるポリエチレン(B)とエチレン系共重合体(C)との融点差TmB-TmCが前記特定の範囲外となっている以外は実施例1の多層発泡シートと同様の構成を有している。比較例2及び比較例4の多層発泡シートの作製方法は、エチレン系共重合体(C)の種類及び製造条件等を表4に示すように変更した以外は実施例1の多層発泡シートの作製方法と同様である。
比較例3の多層発泡シートは、導電層中に、エチレン系共重合体(C)に替えて直鎖状ポリエチレンが含まれている以外は実施例1の多層発泡シートと同様の構成を有している。比較例3の多層発泡シートの作製方法は、導電層形成用溶融物の組成及び製造条件等を表4に示すように変更した以外は実施例1の多層発泡シートの作製方法と同様である。
比較例5の多層発泡シートは、導電層中の導電性カーボンの配合量を多くした以外は比較例1の多層発泡シートと同様の構成を有している。比較例5の多層発泡シートの作製方法は、導電層形成用溶融物中の導電性カーボンの配合量及び製造条件等を表4に示す値に変更した以外は比較例1の多層発泡シートの作製方法と同様である。
以下の方法により、実施例及び比較例の多層発泡シートの導電層の溶融粘度、多層発泡シートの全体厚み及び坪量、多層発泡シートの導電層の平均厚み及び坪量、見掛け密度、発泡倍率、汚染性及び導電性を評価した。
キャピラリーレオメータ(チアスト社製「レオビス2100」)を用い、実施例1~実施例8及び比較例1~比較例5のそれぞれにおける導電層形成用溶融物の溶融粘度を測定した。なお、キャピラリーレオメータのオリフィス径は1mm、オリフィス長は10mmとし、測定温度190℃、せん断速度100sec-1の条件で測定を行った。実施例及び比較例の導電層形成用溶融物の溶融粘度は表3または表4に示す通りであった。
まず、多層発泡シートを押出方向に垂直な面で切断した。この切断面において、切断面の長手方向(つまり、押出方向及び厚み方向の両方に直角な方向)における間隔が等しくなるようにして10か所の測定位置を設定した。顕微鏡を用いてこれらの測定位置を観察し、各測定位置の厚みを測定した。これらの厚みの算術平均値を多層発泡シートの全体厚みとし、表3及び表4に記載した。
多層発泡シートから一辺25mmの正方形状の試験片を採取し、試験片の質量(単位:g)を測定した。この試験片の質量を単位換算することにより、多層発泡シートの坪量、つまり、多層発泡シート1m2当たりの質量(単位:g/m2)を算出した。実施例及び比較例の多層発泡シートの坪量は、表3または表4に示した通りであった。
多層発泡シートを押出方向に垂直な面で切断した。この切断面において、切断面の長手方向(つまり、押出方向及び厚み方向の両方に直角な方向)における間隔が等しくなるようにして10か所の測定位置を設定した。顕微鏡を用いてこれらの測定位置における多層発泡シートの断面を観察し、各測定位置における導電層の厚みを測定した。これらの厚みの算術平均値を、導電層の平均厚み(単位:μm)とした。実施例及び比較例の多層発泡シートにおける導電層の平均厚みは、表3または表4に示した通りであった。
多層発泡シートの共押出時の片面当たりの導電層の吐出量X[g/時]、多層発泡シートの幅W[m]、多層発泡シートの引取速度L[m/時]を用い、下記(1)式に基づいて片面当たりの導電層の坪量を算出した。
導電層の坪量[g/m2]=〔X/(L×W)〕・・・(1)
前述した方法により得られる多層発泡シートの坪量(単位:g/m2)を多層発泡シートの全体厚みで除した後単位換算することにより、多層発泡シートの見掛け密度(単位:kg/m3)を算出した。
実施例及び比較例の多層発泡シートをクリーンペーパーと重ね合わせた後、多層発泡シートを150g/cm2の荷重でクリーンペーパーに押し付けた。この状態で多層発泡シートをクリーンペーパーに対して往復移動させ、多層発泡シートとクリーンペーパーとを摺動させた。なお、往復移動の振幅は5mm、周期は1秒とした。
JIS K6271-1:2015に準拠した測定方法により、導電層の表面抵抗率を測定した。具体的には、多層発泡シートから一辺100mmの正方形状を呈する試験片を採取した。この試験片における導電層の表面に電極を取り付けた後、温度23℃、相対湿度50%の雰囲気中で電極間に1Vの電圧を印加した。そして、電圧を印加してから1分経過した時点での表面抵抗率(単位:Ω)を、多層発泡シートの表面抵抗率とした。なお、表面抵抗率の測定には、日東精工アナリテック株式会社製「ハイレスタUX MCP-HT800」を用いた。実施例及び比較例の多層発泡シートにおける表面抵抗率は、表3または表4に示した通りであった。
Claims (12)
- 基材樹脂としてポリエチレン系樹脂(A)を含むポリエチレン系樹脂発泡層と、
前記ポリエチレン系樹脂発泡層の少なくとも片面側に積層された導電層と、を備え、
前記導電層が、
低密度ポリエチレン及び直鎖状低密度ポリエチレンからなる群より選択される1種または2種以上のポリエチレン(B)と、エチレンに由来する構造単位及び極性基を有するモノマーに由来する構造単位を備えたエチレン系共重合体(C)との混合樹脂と、
前記混合樹脂中に配合された導電性カーボンと、を含み、
前記導電層中における前記導電性カーボンの配合量が3質量%以上15質量%以下であり、
前記導電層に含まれる前記ポリエチレン(B)の融点TmBと、前記エチレン系共重合体(C)の融点TmCとの差TmB-TmCが30℃以上80℃以下である、ポリエチレン系樹脂多層発泡シート。 - 前記導電層中における前記ポリエチレン(B)と前記エチレン系共重合体(C)との配合比率が質量比においてポリエチレン(B):エチレン系共重合体(C)=80:20~20:80である、請求項1に記載のポリエチレン系樹脂多層発泡シート。
- 前記導電層中における前記ポリエチレン(B)と前記エチレン系共重合体(C)との配合比率が質量比においてポリエチレン(B):エチレン系共重合体(C)=50:50~25:75である、請求項1または2に記載のポリエチレン系樹脂多層発泡シート。
- 前記エチレン系共重合体(C)中における極性基を有するモノマーに由来する構造単位の含有量が30質量%以上50質量%以下である、請求項1~3のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記導電層中には、エチレン-酢酸ビニル共重合体及びエチレン-メタクリル酸メチル共重合体からなる群より選択される1種または2種のエチレン系共重合体(C)が含まれている、請求項1~4のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記エチレン系共重合体(C)の温度190℃、荷重2.16kgにおけるメルトフローレイトが20g/10分以上100g/10分以下である、請求項1~5のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記導電層の坪量が1g/m2以上20g/m2以下である、請求項1~6のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記ポリエチレン系樹脂多層発泡シートの見掛け密度が30kg/m3以上150kg/m3以下である、請求項1~7のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記ポリエチレン系樹脂多層発泡シートの全体厚みが0.05mm以上3.0mm以下である、請求項1~8のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記導電性カーボンのジブチルフタレート吸油量が200mL/100g以上600mL/100g以下である、請求項1~9のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- 前記ポリエチレン系樹脂多層発泡シートにおける、前記導電層を有する側の表面の表面抵抗率が1×103Ω以上1×107Ω以下である、請求項1~10のいずれか1項に記載のポリエチレン系樹脂多層発泡シート。
- ポリエチレン系樹脂発泡層を形成するための発泡層形成用溶融物と、導電層を形成するための導電層形成用溶融物とを共押出することにより、前記ポリエチレン系樹脂発泡層と、前記ポリエチレン系樹脂発泡層の少なくとも片面側に積層された前記導電層とを備えたポリエチレン系樹脂多層発泡シートを作製する、ポリエチレン系樹脂多層発泡シートの製造方法であって、
前記発泡層形成用溶融物が基材樹脂としてのポリエチレン系樹脂(A)及び物理発泡剤を混練してなり、
前記導電層形成用溶融物が、低密度ポリエチレン及び直鎖状低密度ポリエチレンからなる群より選択される1種または2種以上のポリエチレン(B)と、エチレンに由来する構造単位及び極性基を有するモノマーに由来する構造単位を備えたエチレン系共重合体(C)と、導電性カーボンと、を混練してなり、
前記導電層形成用溶融物中における前記導電性カーボンの配合量が3質量%以上15質量%以下であり、
前記ポリエチレン(B)の融点TmBと、前記エチレン系共重合体(C)の融点TmCとの差TmB-TmCが30℃以上80℃以下である、ポリエチレン系樹脂多層発泡シートの製造方法。
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- 2021-10-01 EP EP21909868.8A patent/EP4241981A1/en active Pending
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- 2021-10-01 US US18/258,874 patent/US20240042743A1/en active Pending
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JPS54107984A (en) * | 1978-02-14 | 1979-08-24 | Tokyo Printing Ink Mfg Co Ltd | Method of making conductive damper material |
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