JP7492315B2 - Resin foam sheet - Google Patents
Resin foam sheet Download PDFInfo
- Publication number
- JP7492315B2 JP7492315B2 JP2019065383A JP2019065383A JP7492315B2 JP 7492315 B2 JP7492315 B2 JP 7492315B2 JP 2019065383 A JP2019065383 A JP 2019065383A JP 2019065383 A JP2019065383 A JP 2019065383A JP 7492315 B2 JP7492315 B2 JP 7492315B2
- Authority
- JP
- Japan
- Prior art keywords
- foam sheet
- resin foam
- less
- resin
- sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000006260 foam Substances 0.000 title claims description 142
- 229920005989 resin Polymers 0.000 title claims description 136
- 239000011347 resin Substances 0.000 title claims description 136
- 230000006835 compression Effects 0.000 claims description 27
- 238000007906 compression Methods 0.000 claims description 27
- 239000000853 adhesive Substances 0.000 claims description 17
- 230000001070 adhesive effect Effects 0.000 claims description 17
- 229920005672 polyolefin resin Polymers 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 12
- 239000002390 adhesive tape Substances 0.000 claims description 8
- 239000011358 absorbing material Substances 0.000 claims description 4
- 238000011176 pooling Methods 0.000 description 27
- 150000001875 compounds Chemical class 0.000 description 20
- 239000004088 foaming agent Substances 0.000 description 16
- 238000010521 absorption reaction Methods 0.000 description 15
- 238000004132 cross linking Methods 0.000 description 15
- 238000000034 method Methods 0.000 description 15
- 229920013716 polyethylene resin Polymers 0.000 description 15
- 239000011342 resin composition Substances 0.000 description 15
- 238000012360 testing method Methods 0.000 description 14
- 238000005187 foaming Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 8
- 239000012790 adhesive layer Substances 0.000 description 7
- 230000005865 ionizing radiation Effects 0.000 description 7
- 239000004711 α-olefin Substances 0.000 description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 239000003446 ligand Substances 0.000 description 6
- 229920000092 linear low density polyethylene Polymers 0.000 description 6
- 239000004707 linear low-density polyethylene Substances 0.000 description 6
- -1 polypropylene Polymers 0.000 description 6
- 230000035939 shock Effects 0.000 description 6
- 238000005979 thermal decomposition reaction Methods 0.000 description 6
- 239000004973 liquid crystal related substance Substances 0.000 description 5
- 230000006911 nucleation Effects 0.000 description 5
- 238000010899 nucleation Methods 0.000 description 5
- 239000002685 polymerization catalyst Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 4
- ZGEGCLOFRBLKSE-UHFFFAOYSA-N 1-Heptene Chemical compound CCCCCC=C ZGEGCLOFRBLKSE-UHFFFAOYSA-N 0.000 description 4
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 4
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 4
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 4
- 239000004604 Blowing Agent Substances 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000005038 ethylene vinyl acetate Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 150000002430 hydrocarbons Chemical group 0.000 description 4
- 230000001678 irradiating effect Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 4
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 4
- 239000011359 shock absorbing material Substances 0.000 description 4
- 239000004156 Azodicarbonamide Substances 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 239000003963 antioxidant agent Substances 0.000 description 3
- 230000003078 antioxidant effect Effects 0.000 description 3
- XOZUGNYVDXMRKW-AATRIKPKSA-N azodicarbonamide Chemical compound NC(=O)\N=N\C(N)=O XOZUGNYVDXMRKW-AATRIKPKSA-N 0.000 description 3
- 235000019399 azodicarbonamide Nutrition 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 125000000058 cyclopentadienyl group Chemical group C1(=CC=CC1)* 0.000 description 3
- 230000008034 disappearance Effects 0.000 description 3
- 229920001971 elastomer Polymers 0.000 description 3
- 238000010894 electron beam technology Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 2
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 2
- 229920000089 Cyclic olefin copolymer Polymers 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 239000001099 ammonium carbonate Substances 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 150000001923 cyclic compounds Chemical group 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- CPOFMOWDMVWCLF-UHFFFAOYSA-N methyl(oxo)alumane Chemical compound C[Al]=O CPOFMOWDMVWCLF-UHFFFAOYSA-N 0.000 description 2
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 2
- 150000001451 organic peroxides Chemical class 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920005678 polyethylene based resin Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 2
- ULUZGMIUTMRARO-UHFFFAOYSA-N (carbamoylamino)urea Chemical compound NC(=O)NNC(N)=O ULUZGMIUTMRARO-UHFFFAOYSA-N 0.000 description 1
- YBYIRNPNPLQARY-UHFFFAOYSA-N 1H-indene Chemical group C1=CC=C2CC=CC2=C1 YBYIRNPNPLQARY-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
- NBOCQTNZUPTTEI-UHFFFAOYSA-N 4-[4-(hydrazinesulfonyl)phenoxy]benzenesulfonohydrazide Chemical compound C1=CC(S(=O)(=O)NN)=CC=C1OC1=CC=C(S(=O)(=O)NN)C=C1 NBOCQTNZUPTTEI-UHFFFAOYSA-N 0.000 description 1
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- TXPAAJFKASNIGR-UHFFFAOYSA-N CN(C)[Ti](C1C=CC=C1)(N(C)C)N(C)C Chemical compound CN(C)[Ti](C1C=CC=C1)(N(C)C)N(C)C TXPAAJFKASNIGR-UHFFFAOYSA-N 0.000 description 1
- XZGCGBCJTNRXPB-UHFFFAOYSA-N C[Ti](N(C)C)(N(C)C)(N(C)C)C1C=CC=C1 Chemical compound C[Ti](N(C)C)(N(C)C)(N(C)C)C1C=CC=C1 XZGCGBCJTNRXPB-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- MWRWFPQBGSZWNV-UHFFFAOYSA-N Dinitrosopentamethylenetetramine Chemical compound C1N2CN(N=O)CN1CN(N=O)C2 MWRWFPQBGSZWNV-UHFFFAOYSA-N 0.000 description 1
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229920003351 Ultrathene® Polymers 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- ZZBBIOXLMBBGJM-UHFFFAOYSA-L [Cl-].[Cl-].[Zr+3].C[SiH](C)C(C(C(C)(C)C)(C)[N-]C1C=CC=C1)C Chemical compound [Cl-].[Cl-].[Zr+3].C[SiH](C)C(C(C(C)(C)C)(C)[N-]C1C=CC=C1)C ZZBBIOXLMBBGJM-UHFFFAOYSA-L 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000003522 acrylic cement Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- CAMXVZOXBADHNJ-UHFFFAOYSA-N ammonium nitrite Chemical compound [NH4+].[O-]N=O CAMXVZOXBADHNJ-UHFFFAOYSA-N 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 125000005604 azodicarboxylate group Chemical group 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- JAGHDVYKBYUAFD-UHFFFAOYSA-L cyclopenta-1,3-diene;titanium(4+);dichloride Chemical compound [Cl-].[Cl-].[Ti+4].C1C=CC=[C-]1.C1C=CC=[C-]1 JAGHDVYKBYUAFD-UHFFFAOYSA-L 0.000 description 1
- 125000002704 decyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- BXKDSDJJOVIHMX-UHFFFAOYSA-N edrophonium chloride Chemical compound [Cl-].CC[N+](C)(C)C1=CC=CC(O)=C1 BXKDSDJJOVIHMX-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- ZSWFCLXCOIISFI-UHFFFAOYSA-N endo-cyclopentadiene Natural products C1C=CC=C1 ZSWFCLXCOIISFI-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 125000003187 heptyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000004051 hexyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 150000002429 hydrazines Chemical class 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 125000003454 indenyl group Chemical group C1(C=CC2=CC=CC=C12)* 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 150000002738 metalloids Chemical class 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- HWPKGOGLCKPRLZ-UHFFFAOYSA-M monosodium citrate Chemical compound [Na+].OC(=O)CC(O)(C([O-])=O)CC(O)=O HWPKGOGLCKPRLZ-UHFFFAOYSA-M 0.000 description 1
- 235000018342 monosodium citrate Nutrition 0.000 description 1
- 239000002524 monosodium citrate Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 125000000740 n-pentyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002832 nitroso derivatives Chemical class 0.000 description 1
- 125000001400 nonyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000002347 octyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 125000000913 palmityl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920005673 polypropylene based resin Polymers 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 229920001384 propylene homopolymer Polymers 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 150000003349 semicarbazides Chemical class 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 150000003752 zinc compounds Chemical class 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0014—Use of organic additives
- C08J9/0023—Use of organic additives containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0066—Use of inorganic compounding ingredients
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
- C08J9/10—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing nitrogen, the blowing agent being a compound containing a nitrogen-to-nitrogen bond
- C08J9/102—Azo-compounds
- C08J9/103—Azodicarbonamide
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
- C08J2201/026—Crosslinking before of after foaming
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/04—N2 releasing, ex azodicarbonamide or nitroso compound
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2207/00—Foams characterised by their intended use
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/04—Homopolymers or copolymers of ethene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2423/04—Homopolymers or copolymers of ethene
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Description
本発明は、例えば、タッチパネル等の表示装置の衝撃吸収材として使用される樹脂発泡シートに関する。 The present invention relates to a resin foam sheet that is used, for example, as a shock absorbing material for display devices such as touch panels.
ノート型パーソナルコンピューター、携帯電話、スマートフォン、タブレット等の携帯機器において、表示装置は、破損や故障の防止のために、背面側に衝撃吸収材が配置されることがある。衝撃吸収材は、高い柔軟性が求められており、従来、発泡シートが広く使用されている。 In portable devices such as notebook personal computers, mobile phones, smartphones, and tablets, shock absorbing materials are often placed on the back side of the display device to prevent damage or malfunction. Shock absorbing materials are required to be highly flexible, and foam sheets have traditionally been widely used.
携帯機器、特にスマートフォンの表示装置では、タッチパネル式のものが多く採用されている。タッチパネル式の液晶パネルは、パネル操作時の押圧が強くなると、プーリングと呼ばれる液晶の滲みが発生することがある。そのため、表示装置に衝撃吸収材として使用される発泡シートは、高い衝撃吸収性のみならず、耐プーリング特性も求められるようになってきている。 Many mobile devices, especially smartphones, use touch panels for their display devices. Touch panel liquid crystal panels can suffer from a phenomenon known as pooling, where liquid crystal bleeds when the panel is operated with too much pressure. For this reason, foam sheets used as shock absorbing materials in display devices are now required to have not only high shock absorption properties, but also resistance to pooling.
例えば、特許文献１には、厚さが０．０５～０．３５ｍｍである独立気泡発泡シートにおいて、２５％圧縮応力、及びＭＤ、ＴＤにおける引張強さを一定の範囲としつつ、５Ｎで５秒間押圧した後解放したときの回復時間を０．１秒以下にすることが開示される。特許文献１において、発泡シートは、衝撃吸収性が良好で、かつ発生したプーリングを早期に消失できる耐プーリング特性を有することが示される。 For example, Patent Document 1 discloses that in a closed-cell foam sheet having a thickness of 0.05 to 0.35 mm, the 25% compressive stress and the tensile strength in MD and TD are within a certain range, and the recovery time when pressed with 5 N for 5 seconds and then released is 0.1 seconds or less. Patent Document 1 shows that the foam sheet has good shock absorption properties and anti-pooling properties that can quickly eliminate any pooling that occurs.
しかし、特許文献１の発泡シートは、表示装置において発生するプーリングを早期に消失できるものの、表示パネルを押圧すると一定量のプーリングが発生する。近年、プーリングに対する要求は、年々厳しくなっており、プーリングをできる限り発生しないようにすることが望まれている。
そこで、本発明は、衝撃吸収性を良好にしつつ、プーリングの発生を十分に抑制できる樹脂発泡シートを提供することを課題とする。
However, although the foam sheet of Patent Document 1 can quickly eliminate pooling that occurs in a display device, a certain amount of pooling occurs when the display panel is pressed. In recent years, requirements for pooling have become stricter year by year, and it is desired to prevent pooling as much as possible.
Therefore, an object of the present invention is to provide a resin foam sheet that can sufficiently suppress the occurrence of pooling while improving impact absorption properties.
本発明者らは、鋭意検討の結果、所定量圧縮変形したときの樹脂発泡シートの応力緩和特性を高くすることで、上記課題を解決できることを見出し、以下の本発明を完成させた。本発明は、以下の［１］～［１３］を提供する。
［１］樹脂発泡シートであって、前記樹脂発泡シートを初期厚みに対して７５％の厚みとなるように圧縮して６時間後の圧縮応力が４００Ｐａ以下、かつ、１２時間後の圧縮応力が３００Ｐａ以下である、樹脂発泡シート。
［２］独立気泡率が７０％以上である、上記［１］に記載の樹脂発泡シート。
［３］発泡倍率が８ｃｍ3／ｇ以上１４ｃｍ3／ｇ以下である、上記［１］又は［２］に記載の樹脂発泡シート。
［４］厚みが０．１ｍｍ以上０．５ｍｍ以下である、上記［１］～［３］のいずれか１項に記載の樹脂発泡シート。
［５］２５％圧縮強度が５ｋＰａ以上４５ｋＰａ以下、かつ、５０％圧縮強度が１５ｋＰａ以上１００ｋＰａ以下である、上記［１］～［４］のいずれか１項に記載の樹脂発泡シート。
［６］ＭＤの平均気泡径が６０μｍ以上３５０μｍ以下、ＴＤの平均気泡径が５０μｍ以上３５０μｍ以下、ＺＤの平均気泡径が１０μｍ以上７０μｍ以下である、上記［１］～［５］のいずれか１項に記載の樹脂発泡シート。
［７］平均気泡径が下記式（１）及び（２）を満たす、上記［１］～［６］のいずれか１項に記載の樹脂発泡シート。
２≦ＭＤの平均気泡径／ＺＤの平均気泡径≦８ （１）
２≦ＴＤの平均気泡径／ＺＤの平均気泡径≦８ （２）
［８］表面のアスカーＣ硬度が１５以下である、上記［１］～［７］のいずれか１項に記載の樹脂発泡シート。
［９］前記樹脂発泡シートが、ポリオレフィン系樹脂発泡シートである上記［１］～［８］のいずれか１項に記載の樹脂発泡シート。
［１０］表示パネルの衝撃吸収材である上記［１］～［９］のいずれか１項に記載の樹脂発泡シート。
［１１］前記表示パネルがタッチパネルである上記［１０］に記載の樹脂発泡シート。
［１２］上記［１］～［１１］のいずれか１項に記載の樹脂発泡シートと、前記樹脂発泡シートの少なくとも一方の面に設けた粘着材とを備える粘着テープ。
［１３］上記［１］～［１１］のいずれか１項に記載の樹脂発泡シートと、その樹脂発泡シートの上に配置された表示パネルとを備える表示装置。
As a result of intensive research, the present inventors have found that the above-mentioned problems can be solved by increasing the stress relaxation property of a resin foam sheet when it is compressed and deformed by a predetermined amount, and have completed the present invention as described below. The present invention provides the following [1] to [13].
[1] A resin foam sheet, the resin foam sheet being compressed to a thickness of 75% of its initial thickness, and having a compressive stress of 400 Pa or less 6 hours later and a compressive stress of 300 Pa or less 12 hours later.
[2] The resin foam sheet according to the above [1], having a closed cell rate of 70% or more.
[3] The resin foam sheet according to the above [1] or [2], which has an expansion ratio of 8 cm 3 /g or more and 14 cm 3 /g or less.
[4] The resin foam sheet according to any one of the above [1] to [3], having a thickness of 0.1 mm or more and 0.5 mm or less.
[5] The resin foam sheet according to any one of the above [1] to [4], having a 25% compressive strength of 5 kPa or more and 45 kPa or less and a 50% compressive strength of 15 kPa or more and 100 kPa or less.
[6] The resin foam sheet according to any one of the above [1] to [5], wherein the MD average cell diameter is 60 μm or more and 350 μm or less, the TD average cell diameter is 50 μm or more and 350 μm or less, and the ZD average cell diameter is 10 μm or more and 70 μm or less.
[7] The resin foam sheet according to any one of the above [1] to [6], wherein an average cell diameter satisfies the following formulas (1) and (2):
2≦Average cell diameter in MD/Average cell diameter in ZD≦8 (1)
2≦Average bubble diameter of TD/Average bubble diameter of ZD≦8 (2)
[8] The resin foam sheet according to any one of the above [1] to [7], wherein the Asker C hardness of the surface is 15 or less.
[9] The resin foam sheet according to any one of the above [1] to [8], wherein the resin foam sheet is a polyolefin-based resin foam sheet.
[10] The resin foam sheet according to any one of the above [1] to [9], which is an impact absorbing material for a display panel.
[11] The resin foam sheet according to the above [10], wherein the display panel is a touch panel.
[12] An adhesive tape comprising the resin foam sheet according to any one of [1] to [11] above, and an adhesive material provided on at least one surface of the resin foam sheet.
[13] A display device comprising the resin foam sheet according to any one of [1] to [11] above, and a display panel disposed on the resin foam sheet.
本発明の樹脂発泡シートは、衝撃吸収性を良好にしつつ、プーリングの発生を抑制することができる。 The resin foam sheet of the present invention can suppress the occurrence of pooling while providing good shock absorption.
［樹脂発泡シート］
本発明の樹脂発泡シートは、初期厚みに対して７５％の厚みとなるように圧縮して（すなわち、２５％圧縮して）６時間後の圧縮応力が４００Ｐａ以下、かつ、１２時間後の圧縮応力が３００Ｐａ以下となるものである。
本発明の樹脂発泡シートは、圧縮６時間後及び１２時間後の圧縮応力が上記のように低くなることで、圧縮に対する応力緩和特性が優れる。そのため、通常の使用状態では、樹脂発泡シートによって表示装置の画面などに反発力が作用されにくくなると考えられ、それにより表示装置にプーリングが発生しにくくなる。また、大きな衝撃が作用されたときには、樹脂発泡シートの優れた圧縮特性により、衝撃を吸収することができる。
[Resin foam sheet]
The resin foam sheet of the present invention, when compressed to 75% of its initial thickness (i.e., compressed by 25%), has a compressive stress of 400 Pa or less after 6 hours and a compressive stress of 300 Pa or less after 12 hours.
The resin foam sheet of the present invention has excellent stress relaxation properties against compression because the compressive stress after 6 hours and 12 hours of compression is low as described above. Therefore, it is considered that the resin foam sheet makes it difficult for a repulsive force to act on the screen of a display device under normal use conditions, and therefore, pooling is unlikely to occur in the display device. In addition, when a large impact is applied, the excellent compression properties of the resin foam sheet can absorb the impact.
一方で、圧縮６時間後の圧縮応力が４００Ｐａより大きくなったり、１２時間後の圧縮応力が３００Ｐａ以下より大きくなったりすると、樹脂発泡シートは、通常の使用状態で反発力が大きくなり、プーリングが発生しやすくなる。衝撃吸収性を良好にしつつ、プーリングを抑制する観点から、上記圧縮６時間後の圧縮応力は、３８０Ｐａ以下であることが好ましく、また、１５０Ｐａ以上が好ましく、２５０Ｐａ以上がより好ましい。
圧縮１２時間後の圧縮応力は、２９０Ｐａ以下であることが好ましく、また、１００Ｐａ以上が好ましく、２００Ｐａ以上がより好ましい。
On the other hand, if the compressive stress after 6 hours of compression is greater than 400 Pa, or the compressive stress after 12 hours is greater than 300 Pa or less, the resin foam sheet will have a large repulsive force under normal use conditions, and pooling will be more likely to occur. From the viewpoint of suppressing pooling while improving the impact absorption, the compressive stress after 6 hours of compression is preferably 380 Pa or less, more preferably 150 Pa or more, and more preferably 250 Pa or more.
The compressive stress after 12 hours of compression is preferably 290 Pa or less, and is preferably 100 Pa or more, and more preferably 200 Pa or more.
本発明の樹脂発泡シートは、表面を比較的柔らかくすることで、上記した圧縮６時間、及び１２時間後の圧縮応力を低くすることができる。そのような観点から、アスカーＣ硬度は、１５以下であることが好ましく、１３以下がより好ましい。また、アスカーＣ硬度は、樹脂発泡シートに適度な機械強度を付与する観点から、１以上が好ましく、５以上がより好ましい。 The resin foam sheet of the present invention can reduce the compressive stress after 6 hours and 12 hours of compression by making the surface relatively soft. From this viewpoint, the Asker C hardness is preferably 15 or less, and more preferably 13 or less. Furthermore, from the viewpoint of imparting appropriate mechanical strength to the resin foam sheet, the Asker C hardness is preferably 1 or more, and more preferably 5 or more.
本発明の樹脂発泡シートは、発泡倍率が８ｃｍ3／ｇ以上１４ｃｍ3／ｇ以下であることが好ましい。発泡倍率が８ｃｍ3／ｇ以上となると、樹脂発泡シートの柔軟性が確保され、上記したアスカーＣ硬度を低くしやすくなり、それにより、圧縮６時間後、及び１２時間後の圧縮応力を低くしやすくなる。また、後述する２５％、５０％圧縮強度も低くしやすくなる。発泡倍率は、これら観点から８．５ｃｍ3／ｇ以上がより好ましい。
また、発泡倍率が１４ｃｍ3／ｇ以下であると、樹脂発泡シートは、適度な機械強度を有し、良好な衝撃吸収性及び耐久性を確保しやすくなる。このような観点から発泡倍率は、１２ｃｍ3／ｇ以下がより好ましく、１１ｃｍ3／ｇ以下が更に好ましい。
The resin foam sheet of the present invention preferably has an expansion ratio of 8 cm 3 /g or more and 14 cm 3 /g or less. When the expansion ratio is 8 cm 3 /g or more, the flexibility of the resin foam sheet is ensured, and the above-mentioned Asker C hardness is easily reduced, which makes it easier to reduce the compressive stress after 6 hours and 12 hours of compression. In addition, the 25% and 50% compression strengths described below are also easily reduced. From these viewpoints, the expansion ratio is more preferably 8.5 cm 3 /g or more.
In addition, when the expansion ratio is 14 cm3 /g or less, the resin foam sheet has appropriate mechanical strength and is likely to ensure good impact absorption and durability. From such a viewpoint, the expansion ratio is more preferably 12 cm3/g or less, and even more preferably 11 cm3 /g or less.
本発明の樹脂発泡シートは、２５％圧縮強度が５ｋＰａ以上４５ｋＰａ以下であり、かつ５０％圧縮強度が１５ｋＰａ以上１００ｋＰａ以下であることが好ましい。２５％及び５０％圧縮強度が上記範囲内であると、衝撃吸収性が優れたものとなり、かつプーリングの発生も抑えやすくなる。また、これら下限値以上とすることで、プーリングが発生してもプーリングを素早く消失させ、耐プーリング性が向上する。
これら観点から、２５％圧縮強度は、１５ｋＰａ以上がより好ましく、２５ｋＰａ以上がさらに好ましく、また、４０Ｐａ以下がより好ましく、３７ｋＰａ以下がさらに好ましい。同様の観点から、５０％圧縮強度は、２５ｋＰａ以上がより好ましく、３５ｋＰａ以上がさらに好ましく、また、９５ｋＰａ以下がより好ましく、８５ｋＰａ以下がさらに好ましい。
The resin foam sheet of the present invention preferably has a 25% compression strength of 5 kPa to 45 kPa and a 50% compression strength of 15 kPa to 100 kPa. When the 25% and 50% compression strengths are within the above ranges, the impact absorption is excellent and the occurrence of pooling is easily suppressed. Furthermore, by making the strengths equal to or greater than these lower limits, even if pooling occurs, it quickly disappears and the pooling resistance is improved.
From these viewpoints, the 25% compressive strength is more preferably 15 kPa or more, even more preferably 25 kPa or more, and more preferably 40 kPa or less, and even more preferably 37 kPa or less. From the same viewpoints, the 50% compressive strength is more preferably 25 kPa or more, even more preferably 35 kPa or more, and more preferably 95 kPa or less, and even more preferably 85 kPa or less.
本発明の樹脂発泡シートの厚みは、０．１ｍｍ以上０．５ｍｍ以下が好ましい。樹脂発泡シートの厚みが０．５ｍｍ以下となると、厚みが必要以上に大きくならないので、発泡シートが適用される表示装置の小型化及び薄型化を達成しやすくなる。また、０．１ｍｍ以上とすることで、樹脂発泡シートの衝撃吸収性を良好としやすくなる。
樹脂発泡シートの厚みは、表示装置の小型化及び薄型化、衝撃吸収性の向上の観点から、０．１２ｍｍ以上がより好ましく、０．１４ｍｍ以上がさらに好ましく、また、０．３５ｍｍ以下がより好ましく、０．２５ｍｍ以下がさらに好ましい。
The thickness of the resin foam sheet of the present invention is preferably 0.1 mm or more and 0.5 mm or less. When the thickness of the resin foam sheet is 0.5 mm or less, the thickness is not greater than necessary, so that it is easy to achieve a small and thin display device to which the foam sheet is applied. In addition, when the thickness is 0.1 mm or more, it is easy to improve the impact absorption of the resin foam sheet.
From the viewpoint of making the display device smaller and thinner and improving the impact absorption, the thickness of the resin foam sheet is preferably 0.12 mm or more, and more preferably 0.14 mm or more, and more preferably 0.35 mm or less, and even more preferably 0.25 mm or less.
また、樹脂発泡シートは、独立気泡発泡体であることが好ましい。なお、独立気泡発泡体であるとは、樹脂発泡シートの独立気泡率が７０％以上であることを意味する。すなわち、樹脂発泡シートの内部に包含された気泡は概ね独立気泡となり、押圧に対する反発力が大きくなりやすいため、プーリングが発生しても素早く消失させことが可能であり、耐プーリング性が向上する。また、独立気泡発泡体であることで、衝撃吸収性も良好となりやすい。これら観点から、発泡シートの独立気泡率は、より好ましくは８０％以上、さらに好ましくは９０％以上１００％以下である。 The resin foam sheet is preferably a closed-cell foam. A closed-cell foam means that the closed-cell ratio of the resin foam sheet is 70% or more. In other words, the bubbles contained inside the resin foam sheet are mostly closed cells, and the repulsive force against pressure is likely to be large, so that even if pooling occurs, it can be quickly eliminated, and pooling resistance is improved. In addition, being a closed-cell foam tends to provide good shock absorption. From these perspectives, the closed-cell ratio of the foam sheet is more preferably 80% or more, and even more preferably 90% or more and 100% or less.
なお、独立気泡率は、下記の要領で測定できる。
まず、樹脂発泡シートから一辺が５ｃｍの平面正方形状の試験片を切り出す。そして、試験片の厚さを測定して試験片の見掛け体積Ｖ1を算出すると共に、試験片の重量Ｗ1を測定する。
次に、気泡の占める体積Ｖ2を下記式に基づいて算出する。なお、試験片を構成している材料の密度はρ（ｇ／ｃｍ3）とする。
気泡の占める体積Ｖ2＝Ｖ1－Ｗ1／ρ
続いて、試験片を２３℃の蒸留水中に水面から１００ｍｍの深さに沈めて、試験片に１５ｋＰａの圧力を３分間に亘って加える。その後、水中で加圧から解放し、１分間静置した後、試験片を水中から取り出して試験片の表面に付着した水分を除去して試験片の重量Ｗ2を測定し、下記式に基づいて連続気泡率Ｆ1及び独立気泡率Ｆ2を算出する。
連続気泡率Ｆ1（％）＝１００×（Ｗ2－Ｗ1）／Ｖ2
独立気泡率Ｆ2（％）＝１００－Ｆ1
The closed cell ratio can be measured as follows.
First, a square test piece having a side length of 5 cm is cut out from a resin foam sheet. The thickness of the test piece is then measured to calculate the apparent volume V1 of the test piece, and the weight W1 of the test piece is also measured.
Next, the volume V2 occupied by the air bubbles is calculated based on the following formula: The density of the material constituting the test piece is ρ (g/cm 3 ).
Volume occupied by air bubbles V 2 = V 1 - W 1 /ρ
Next, the test piece is submerged in distilled water at 23° C. to a depth of 100 mm from the water surface, and a pressure of 15 kPa is applied to the test piece for 3 minutes. After that, the pressure is released in the water and the test piece is left to stand for 1 minute, and then the test piece is taken out of the water and the water adhering to the surface of the test piece is removed, and the weight W2 of the test piece is measured, and the open cell ratio F1 and closed cell ratio F2 are calculated based on the following formula.
Open cell ratio F 1 (%) = 100 × (W 2 - W 1 )/V 2
Closed cell ratio F 2 (%) = 100 - F 1
本発明の樹脂発泡シートは、ＭＤにおける引張強度が２５００ｋＰａ以上、かつＴＤにおける引張強度が１８００ｋＰａ以上であることが好ましい。引張強度がこれら下限値以上となると、樹脂発泡シートの機械強度が良好となり耐久性が高められる。
また、ＭＤにおける引張強度が９５００ｋＰａ以下、かつＴＤにおける引張強度が８０００ｋＰａ以下であることが好ましい。引張強度がこれら上限値以下となると、機械強度が適切な大きさとなり、アスカーＣ硬度を上記上限値以下にしやすくなる。
本発明では、ＭＤにおける引張強度が３０００ｋＰａ以上，かつＴＤにおける引張強度が２０００ｋＰａ以上であることがより好ましく、また、ＭＤにおける引張強度が７０００ｋＰａ以下，かつＴＤにおける引張強度が５５００ｋＰａ以下であることがより好ましい。
なお、ＭＤは、Machine directionを意味し、押出方向等と一致する方向である。ＴＤは、Transverse directionを意味し、ＭＤに直交しかつ発泡シートに平行な方向である。また、後述するＺＤは、発泡シートの厚さ方向であり、ＭＤ及びＴＤのいずれにも垂直な方向である。
The resin foam sheet of the present invention preferably has a tensile strength in MD of 2500 kPa or more and a tensile strength in TD of 1800 kPa or more. When the tensile strength is equal to or more than these lower limits, the mechanical strength of the resin foam sheet is good and durability is improved.
It is also preferable that the tensile strength in MD is 9500 kPa or less and the tensile strength in TD is 8000 kPa or less. When the tensile strength is below these upper limits, the mechanical strength becomes appropriate, and it becomes easier to make the Asker C hardness below the upper limits.
In the present invention, it is more preferable that the tensile strength in MD is 3000 kPa or more and the tensile strength in TD is 2000 kPa or more, and it is more preferable that the tensile strength in MD is 7000 kPa or less and the tensile strength in TD is 5500 kPa or less.
In addition, MD means machine direction and is a direction that coincides with the extrusion direction, etc., TD means transverse direction and is a direction perpendicular to MD and parallel to the foamed sheet, and ZD, which will be described later, is a thickness direction of the foamed sheet and is a direction perpendicular to both MD and TD.
本発明では、上記した圧縮６時間後及び１２時間後の圧縮応力を低くするためには、気泡の形状は、扁平であることが好ましい。具体的には、樹脂発泡シートの気泡の平均気泡径は、ＭＤの平均気泡径／ＺＤの平均気泡径を「ＭＤ／ＺＤ」、ＴＤの平均気泡径／ＺＤの平均気泡径を「ＴＤ／ＺＤ」とすると、下記の式（１）及び（２）を満たすことが好ましい。
２≦ＭＤ／ＺＤ≦８ ・・・（１）
２≦ＴＤ／ＺＤ≦８ ・・・（２）
また、上記観点から、ＭＤ／ＺＤが３以上７以下で、かつＴＤ／ＺＤが３以上７以下であることがより好ましく、ＭＤ／ＺＤが４．８以上７以下で、ＴＤ／ＺＤが５．５以上７以下であることがさらに好ましい。
In the present invention, in order to reduce the compressive stress after 6 hours and 12 hours of compression, the shape of the bubbles is preferably flat. Specifically, the average bubble diameter of the bubbles in the resin foam sheet preferably satisfies the following formulas (1) and (2), where the average bubble diameter in MD/ZD is "MD/ZD" and the average bubble diameter in TD/ZD is "TD/ZD".
2≦MD/ZD≦8 ... (1)
2≦TD/ZD≦8 ... (2)
From the above viewpoints, it is more preferable that MD/ZD is 3 or more and 7 or less, and TD/ZD is 3 or more and 7 or less, and it is even more preferable that MD/ZD is 4.8 or more and 7 or less, and TD/ZD is 5.5 or more and 7 or less.
樹脂発泡シートにおける気泡の平均気泡径は、例えば、ＭＤにおいて６０μｍ以上３５０μｍ以下、ＴＤにおいて５０μｍ以上３５０μｍ以下、ＺＤにおいて１０μｍ以上７０μｍ以下となるものである。樹脂発泡シートにおける気泡の平均気泡径は、好ましくは、ＭＤにおいて１００μｍ以上３２０μｍ以下、ＴＤにおいて１００μｍ以上３２０μｍ以下、ＺＤにおいて２０μｍ以上５５μｍ以下である。より好ましくは、ＭＤにおいて２０μｍ以上３００μｍ以下、ＴＤにおいて２１０μｍ以上３１０μｍ以下、ＺＤにおいて２０μｍ以上５５μｍ以下である。平均気泡径を一定の範囲内とすることで、上記した圧縮６時間後及び１２時間後の圧縮応力を所望の範囲内に調整しやすくなる。 The average bubble diameter of the bubbles in the resin foam sheet is, for example, 60 μm to 350 μm in MD, 50 μm to 350 μm in TD, and 10 μm to 70 μm in ZD. The average bubble diameter of the bubbles in the resin foam sheet is preferably 100 μm to 320 μm in MD, 100 μm to 320 μm in TD, and 20 μm to 55 μm in ZD. More preferably, it is 20 μm to 300 μm in MD, 210 μm to 310 μm in TD, and 20 μm to 55 μm in ZD. By setting the average bubble diameter within a certain range, it becomes easier to adjust the compression stress after 6 hours and 12 hours of compression to within the desired range.
樹脂発泡シートは、樹脂を含む発泡性樹脂組成物を発泡してなるものであるが、発泡性樹脂組成物を架橋及び発泡してなることが好ましい。すなわち、樹脂発泡シートは、架橋体であることが好ましい。樹脂発泡シートは、架橋体であることで、圧縮強度及び引張強度などを優れたものとしつつ、圧縮６時間後及び１２時間後の圧縮応力を所望の範囲内に調整しやすくなる。樹脂発泡シートの架橋は、後述する電離性放射線の照射により行うことが好ましいが、その他の方法で行ってもよい。 The resin foam sheet is formed by foaming a foamable resin composition containing a resin, and is preferably formed by crosslinking and foaming the foamable resin composition. That is, the resin foam sheet is preferably a crosslinked body. By being a crosslinked body, the resin foam sheet has excellent compressive strength and tensile strength, and the compressive stress after 6 hours and 12 hours of compression can be easily adjusted to within a desired range. The resin foam sheet is preferably crosslinked by irradiation with ionizing radiation, which will be described later, but may be crosslinked by other methods.
樹脂発泡シートの架橋度は、通常、５～６０質量％程度であるが、好ましくは１０～５０質量％、より好ましくは２０～３５質量％である。架橋度は、後述する電離性放射線の照射量などにより調整可能である。
なお、架橋度は、以下の測定方法で測定する。樹脂発泡シートから約１００ｍｇの試験片を採取し、試験片の重量Ａ（ｍｇ）を精秤する。次に、この試験片を１２０℃のキシレン３０ｃｍ3中に浸漬して２４時間放置した後、２００メッシュの金網で濾過して金網上の不溶解分を採取、真空乾燥し、不溶解分の重量Ｂ（ｍｇ）を精秤する。得られた値から、下記式により架橋度（質量％）を算出する。
架橋度（質量％）＝１００×（Ｂ／Ａ）
The degree of crosslinking of the resin foam sheet is usually about 5 to 60% by mass, preferably 10 to 50% by mass, and more preferably 20 to 35% by mass. The degree of crosslinking can be adjusted by the amount of ionizing radiation to be described later.
The degree of crosslinking is measured by the following method. A test piece of about 100 mg is taken from the resin foam sheet, and the weight A (mg) of the test piece is precisely weighed. Next, the test piece is immersed in 30 cm3 of xylene at 120°C and left for 24 hours, and then filtered through a 200-mesh wire net to collect the insoluble matter on the wire net, vacuum-dried, and the weight B (mg) of the insoluble matter is precisely weighed. From the obtained value, the degree of crosslinking (mass%) is calculated by the following formula.
Degree of crosslinking (mass%)=100×(B/A)
（ポリオレフィン系樹脂）
本発明の樹脂発泡シートは、樹脂成分として、ポリオレフィン系樹脂を使用したポリオレフィン系樹脂発泡シートであることが好ましい。ポリオレフィン系樹脂を使用することで、アスカーＣ硬度を低くして、圧縮６時間後及び１２時間後の圧縮応力を所定値以下に調整しやすくなる。また、圧縮強度及び引張強度なども所望の範囲内に調整しやすくなる。
ポリオレフィン系樹脂発泡シートにおいて、ポリオレフィン系樹脂は、主成分となるものであり、通常、樹脂発泡シート全量基準で、５０質量％以上含有され、好ましくは７０質量％以上、より好ましくは８０～１００質量％含有される。
(Polyolefin resin)
The resin foam sheet of the present invention is preferably a polyolefin resin foam sheet using a polyolefin resin as a resin component. By using a polyolefin resin, the Asker C hardness can be lowered, and the compressive stress after 6 hours and 12 hours of compression can be easily adjusted to a predetermined value or less. In addition, the compressive strength and tensile strength can be easily adjusted to within a desired range.
In the polyolefin-based resin foam sheet, the polyolefin-based resin is a main component, and is usually contained in an amount of 50 mass % or more, preferably 70 mass % or more, and more preferably 80 to 100 mass %, based on the total amount of the resin foam sheet.
樹脂発泡シートに使用されるポリオレフィン系樹脂としては、ポリエチレン系樹脂、ポリプロピレン系樹脂、またはこれらの混合物が挙げられ、これらの中ではポリエチレン系樹脂が好ましい。より具体的には、チーグラー・ナッタ化合物、メタロセン化合物、酸化クロム化合物等の重合触媒で重合されたポリエチレン系樹脂、ポリプロピレン系樹脂、又はこれらの混合物が挙げられ、これらの中では、メタロセン化合物の重合触媒で重合されたポリエチレン系樹脂が好ましい。
ポリエチレン系樹脂は、エチレン単独重合体でもよいが、エチレンと必要に応じて少量（例えば、全モノマーの３０質量％以下、好ましくは１～１０質量％）のα－オレフィンとを共重合することにより得られるポリエチレン系樹脂が好ましく、その中でも、直鎖状低密度ポリエチレンが好ましい。
メタロセン化合物の重合触媒により得られた、ポリエチレン系樹脂、特に直鎖状低密度ポリエチレンを用いることにより、アスカーＣ硬度を低くして、圧縮６時間後、及び１２時間後の圧縮応力を所定の範囲内に調整しやすくなる。さらには、圧縮強度及び引張強度なども所望の範囲内に調整しやすくなる。また、樹脂発泡シートを薄くても高い性能を維持しやすくなる。
ポリエチレン系樹脂を構成するα－オレフィンとして、具体的には、プロピレン、１－ブテン、１－ペンテン、４－メチル－１－ペンテン、１－ヘキセン、１－ヘプテン、及び１－オクテン等が挙げられる。なかでも、炭素数４～１０のα－オレフィンが好ましい。
また、ポリエチレン系樹脂としては、エチレン－酢酸ビニル共重合体も好ましく用いられる。エチレン－酢酸ビニル共重合体は、通常、エチレン単位を５０質量％以上含有する共重合体である。エチレン－酢酸ビニル共重合体を用いる場合、直鎖状低密度ポリエチレン、特にメタロセン化合物の重合触媒により得られた直鎖状低密度ポリエチレンと併用することが好ましい。
メタロセン化合物の重合触媒により得られたポリエチレン系樹脂は、樹脂発泡シートにおいて樹脂全量に対して好ましくは５０質量％以上含有され、さらに好ましくは７０質量％以上、最も好ましくは１００質量％含有される。
Examples of polyolefin resins used in the resin foam sheet include polyethylene resins, polypropylene resins, and mixtures thereof, among which polyethylene resins are preferred. More specifically, examples include polyethylene resins, polypropylene resins, and mixtures thereof polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound, or a chromium oxide compound, among which polyethylene resins polymerized with a polymerization catalyst such as a metallocene compound are preferred.
The polyethylene-based resin may be an ethylene homopolymer, but is preferably a polyethylene-based resin obtained by copolymerizing ethylene with a small amount of an α-olefin (for example, 30% by mass or less of the total monomers, preferably 1 to 10% by mass) as necessary, and among these, linear low-density polyethylene is preferred.
By using a polyethylene resin, particularly a linear low-density polyethylene, obtained by using a polymerization catalyst of a metallocene compound, it is possible to reduce the Asker C hardness and easily adjust the compressive stress after 6 hours and 12 hours of compression within a predetermined range. Furthermore, it is also possible to easily adjust the compressive strength and tensile strength within a desired range. In addition, it is also possible to easily maintain high performance even when the resin foam sheet is thin.
Specific examples of the α-olefin constituting the polyethylene resin include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene, etc. Among these, α-olefins having 4 to 10 carbon atoms are preferred.
As the polyethylene resin, an ethylene-vinyl acetate copolymer is also preferably used. The ethylene-vinyl acetate copolymer is usually a copolymer containing 50% by mass or more of ethylene units. When an ethylene-vinyl acetate copolymer is used, it is preferable to use it in combination with a linear low-density polyethylene, in particular a linear low-density polyethylene obtained by using a polymerization catalyst of a metallocene compound.
The polyethylene resin obtained using a metallocene compound as a polymerization catalyst is contained in the resin foam sheet in an amount of preferably 50% by mass or more, more preferably 70% by mass or more, and most preferably 100% by mass, based on the total amount of resin.
また、ポリプロピレン系樹脂としては、例えば、プロピレン単独重合体、プロピレン単位を５０質量％以上含有するプロピレン－α－オレフィン共重合体等が挙げられる。これらは１種を単独で用いてもよく、２種以上を併用してもよい。
プロピレン－α－オレフィン共重合体を構成するα－オレフィンとしては、具体的には、エチレン、１－ブテン、１－ペンテン、４－メチル－１－ペンテン、１－ヘキセン、１－ヘプテン、１－オクテン等が挙げられ、これらの中では、炭素数６～１２のα－オレフィンが好ましい。
Examples of polypropylene-based resins include propylene homopolymers, propylene-α-olefin copolymers containing 50% by mass or more of propylene units, etc. These may be used alone or in combination of two or more.
Specific examples of the α-olefin constituting the propylene-α-olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. Among these, α-olefins having 6 to 12 carbon atoms are preferred.
＜メタロセン化合物＞
好適なメタロセン化合物としては、遷移金属をπ電子系の不飽和化合物で挟んだ構造を有するビス（シクロペンタジエニル）金属錯体等の化合物が挙げられる。より具体的には、チタン、ジルコニウム、ニッケル、パラジウム、ハフニウム、及び白金等の四価の遷移金属に、１又は２以上のシクロペンタジエニル環又はその類縁体がリガンド（配位子）として存在する化合物が挙げられる。
このようなメタロセン化合物は、活性点の性質が均一であり各活性点が同じ活性度を備えている。メタロセン化合物を用いて合成した重合体は、分子量、分子量分布、組成、組成分布等の均一性が高くなるため、メタロセン化合物を用いて合成した重合体を含むシートを架橋した場合には、架橋が均一に進行する。均一に架橋されたシートは、均一に延伸しやすくなるため、架橋ポリオレフィン樹脂発泡シートの厚さを均一にしやすくなり、厚さが薄くても高い性能を維持しやすくなる。
<Metallocene Compound>
Suitable metallocene compounds include compounds such as bis(cyclopentadienyl) metal complexes having a structure in which a transition metal is sandwiched between π-electron unsaturated compounds, more specifically compounds in which one or more cyclopentadienyl rings or analogs thereof exist as ligands on a tetravalent transition metal such as titanium, zirconium, nickel, palladium, hafnium, or platinum.
Such metallocene compounds have uniform properties of active sites, and each active site has the same activity. A polymer synthesized using a metallocene compound has high uniformity in molecular weight, molecular weight distribution, composition, composition distribution, etc., so that when a sheet containing a polymer synthesized using a metallocene compound is crosslinked, crosslinking proceeds uniformly. A uniformly crosslinked sheet is easily stretched uniformly, so that the thickness of the crosslinked polyolefin resin foam sheet can be easily made uniform, and high performance can be easily maintained even if the thickness is thin.
リガンドとしては、例えば、シクロペンタジエニル環、インデニル環等が挙げられる。これらの環式化合物は、炭化水素基、置換炭化水素基又は炭化水素－置換メタロイド基により置換されていてもよい。炭化水素基としては、例えば、メチル基、エチル基、各種プロピル基、各種ブチル基、各種アミル基、各種ヘキシル基、２－エチルヘキシル基、各種ヘプチル基、各種オクチル基、各種ノニル基、各種デシル基、各種セチル基、フェニル基等が挙げられる。なお、「各種」とは、ｎ－、ｓｅｃ－、ｔｅｒｔ－、ｉｓｏ－を含む各種異性体を意味する。
また、環式化合物をオリゴマーとして重合したものをリガンドとして用いてもよい。
更に、π電子系の不飽和化合物以外にも、塩素や臭素等の一価のアニオンリガンド又は二価のアニオンキレートリガンド、炭化水素、アルコキシド、アリールアミド、アリールオキシド、アミド、アリールアミド、ホスフィド、アリールホスフィド等を用いてもよい。
Examples of the ligand include a cyclopentadienyl ring and an indenyl ring. These cyclic compounds may be substituted with a hydrocarbon group, a substituted hydrocarbon group, or a hydrocarbon-substituted metalloid group. Examples of the hydrocarbon group include a methyl group, an ethyl group, various propyl groups, various butyl groups, various amyl groups, various hexyl groups, 2-ethylhexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various cetyl groups, and a phenyl group. Here, "various" refers to various isomers including n-, sec-, tert-, and iso-.
Furthermore, a cyclic compound may be polymerized as an oligomer and used as the ligand.
Furthermore, in addition to the π-electron unsaturated compounds, monovalent anion ligands such as chlorine and bromine or divalent anion chelate ligands, hydrocarbons, alkoxides, arylamides, aryloxides, amides, arylamides, phosphides, arylphosphides, and the like may also be used.
四価の遷移金属やリガンドを含むメタロセン化合物としては、例えば、シクロペンタジエニルチタニウムトリス（ジメチルアミド）、メチルシクロペンタジエニルチタニウムトリス（ジメチルアミド）、ビス（シクロペンタジエニル）チタニウムジクロリド、ジメチルシリルテトラメチルシクロペンタジエニル－ｔ－ブチルアミドジルコニウムジクロリド等が挙げられる。
メタロセン化合物は、特定の共触媒（助触媒）と組み合わせることにより、各種オレフィンの重合の際に触媒としての作用を発揮する。具体的な共触媒としては、メチルアルミノキサン（ＭＡＯ）、ホウ素系化合物等が挙げられる。なお、メタロセン化合物に対する共触媒の使用割合は、１０～１００万モル倍が好ましく、５０～５，０００モル倍がより好ましい。
Examples of metallocene compounds containing a tetravalent transition metal or a ligand include cyclopentadienyltitanium tris(dimethylamide), methylcyclopentadienyltitanium tris(dimethylamide), bis(cyclopentadienyl)titanium dichloride, and dimethylsilyltetramethylcyclopentadienyl-t-butylamide zirconium dichloride.
Metallocene compounds, when combined with a specific cocatalyst (promoter), act as a catalyst during the polymerization of various olefins. Specific examples of the cocatalyst include methylaluminoxane (MAO) and boron-based compounds. The ratio of the cocatalyst to the metallocene compound is preferably 100,000 to 1,000,000 times by mole, and more preferably 50 to 5,000 times by mole.
上記ポリエチレン系樹脂は、樹脂発泡シートの圧縮６時間後及び１２時間後の圧縮応力、圧縮強度、並びに引張強度を所望の範囲に調整しやすくするために、低密度であることが好ましい。上記ポリエチレン系樹脂の密度は、具体的には、０．９２０ｇ／ｃｍ3以下が好ましく、より好ましくは０．８８０～０．９１５ｇ／ｃｍ3、特に好ましくは０．８８５～０．９１０ｇ／ｃｍ3である。なお、密度はＡＳＴＭ Ｄ１５０５に準拠して測定したものである。 The polyethylene resin preferably has a low density so that the compressive stress, compressive strength, and tensile strength of the resin foam sheet after 6 hours and 12 hours of compression can be easily adjusted to the desired range. Specifically, the density of the polyethylene resin is preferably 0.920 g/cm 3 or less, more preferably 0.880 to 0.915 g/cm 3 , and particularly preferably 0.885 to 0.910 g/cm 3. The density is measured in accordance with ASTM D1505.
また、樹脂発泡シートに使用される樹脂として、ポリオレフィン系樹脂を使用する場合、ポリオレフィン系樹脂は、ポリオレフィン系樹脂以外の樹脂と併用してもよい。そのような樹脂成分は、ゴム、エラストマー成分などであってもよい。ポリオレフィン系樹脂以外の樹脂成分の含有量は、ポリオレフィン系樹脂よりも含有量が少なく、ポリオレフィン系樹脂１００質量部に対して、通常５０質量部以下、好ましくは３０質量部以下程度である。 When a polyolefin resin is used as the resin for the resin foam sheet, the polyolefin resin may be used in combination with a resin other than the polyolefin resin. Such a resin component may be a rubber or elastomer component. The content of the resin component other than the polyolefin resin is less than that of the polyolefin resin, and is usually 50 parts by mass or less, preferably 30 parts by mass or less, per 100 parts by mass of the polyolefin resin.
（熱分解型発泡剤）
本発明の樹脂発泡シートは、上記樹脂成分に加えて、熱分解型発泡剤を含む発泡性樹脂組成物を発泡してなることが好ましい。
熱分解型発泡剤としては、有機発泡剤、無機発泡剤が使用可能である。有機系発泡剤としては、アゾジカルボンアミド、アゾジカルボン酸金属塩（アゾジカルボン酸バリウム等）、アゾビスイソブチロニトリル等のアゾ化合物、Ｎ，Ｎ’－ジニトロソペンタメチレンテトラミン等のニトロソ化合物、ヒドラゾジカルボンアミド、４，４’－オキシビス（ベンゼンスルホニルヒドラジド）、トルエンスルホニルヒドラジド等のヒドラジン誘導体、トルエンスルホニルセミカルバジド等のセミカルバジド化合物等が挙げられる。
無機系発泡剤としては、炭酸アンモニウム、炭酸ナトリウム、炭酸水素アンモニウム、炭酸水素ナトリウム、亜硝酸アンモニウム、水素化ホウ素ナトリウム、無水クエン酸モノソーダ等が挙げられる。
これらの中では、微細な気泡を得る観点、及び経済性、安全面の観点から、アゾ化合物が好ましく、アゾジカルボンアミドが特に好ましい。これらの熱分解型発泡剤は、単独で又は２以上を組み合わせて使用することができる。
発泡性組成物における熱分解型発泡剤の配合量は、樹脂１００質量部に対して、好ましくは１～１５質量部、より好ましくは１～１２質量部、さらに好ましくは１．５～５質量部である。
(Thermal decomposition type foaming agent)
The resin foam sheet of the present invention is preferably obtained by foaming a foamable resin composition containing a thermally decomposable foaming agent in addition to the above-mentioned resin components.
As the thermal decomposition type blowing agent, organic blowing agents and inorganic blowing agents can be used. Examples of the organic blowing agent include azo compounds such as azodicarbonamide, azodicarboxylate metal salts (e.g., barium azodicarboxylate), azobisisobutyronitrile, etc., nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, etc., hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), toluenesulfonylhydrazide, etc., and semicarbazide compounds such as toluenesulfonylsemicarbazide, etc.
Examples of inorganic foaming agents include ammonium carbonate, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and anhydrous monosodium citrate.
Among these, from the viewpoint of obtaining fine bubbles, and from the viewpoints of economy and safety, azo compounds are preferred, and azodicarbonamide is particularly preferred. These thermal decomposition type foaming agents can be used alone or in combination of two or more.
The amount of the thermally decomposable foaming agent in the foamable composition is preferably 1 to 15 parts by mass, more preferably 1 to 12 parts by mass, and further preferably 1.5 to 5 parts by mass, based on 100 parts by mass of the resin.
また、発泡性樹脂組成物は、上記樹脂成分と熱分解型発泡剤に加えて、気泡核調整剤を含有してもよい。気泡核調整剤としては、酸化亜鉛、ステアリン酸亜鉛等の亜鉛化合物、クエン酸、尿素の有機化合物等が挙げられるが、これらの中では、酸化亜鉛がより好ましい。気泡核調整剤の配合量は、樹脂１００質量部に対して、好ましくは０．４～８質量部、より好ましくは０．５～５質量部、さらに好ましくは０．８～２．５質量部である。気泡核調整剤を配合することで、微細気泡の気泡径のばらつきを抑えることが可能になる。
発泡性樹脂組成物は、必要に応じて、上記以外にも、酸化防止剤、架橋助剤、熱安定剤、着色剤、難燃剤、帯電防止剤、充填材等の発泡体に一般的に使用する添加剤を含有していてもよい。
The foamable resin composition may contain a bubble nucleation regulator in addition to the resin components and the thermal decomposition type foaming agent. Examples of the bubble nucleation regulator include zinc compounds such as zinc oxide and zinc stearate, and organic compounds such as citric acid and urea. Of these, zinc oxide is more preferable. The amount of the bubble nucleation regulator is preferably 0.4 to 8 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.8 to 2.5 parts by mass, based on 100 parts by mass of the resin. By adding the bubble nucleation regulator, it becomes possible to suppress the variation in the bubble diameter of the fine bubbles.
The foamable resin composition may contain, if necessary, additives generally used in foams, such as an antioxidant, a crosslinking aid, a heat stabilizer, a colorant, a flame retardant, an antistatic agent, and a filler, in addition to the above.
［樹脂発泡シートの製造方法］
本発明の樹脂発泡シートは、例えば、樹脂及び熱分解型発泡剤を含む発泡性樹脂組成物を架橋し、加熱して熱分解型発泡剤を発泡させ、かつＴＤ及びＭＤの両方に延伸することで製造することができる。
その製造方法は、より具体的には、以下の工程（１）～（４）を含む。
工程（１）：樹脂、熱分解型発泡剤、及び必要に応じて配合されるその他の添加剤を混合して、シート状の発泡性樹脂組成物（樹脂シート）に成形する工程
工程（２）：シート状の発泡性樹脂組成物に電離性放射線を照射して発泡性樹脂組成物を架橋させる工程
工程（３）：架橋させた発泡性樹脂組成物を加熱し、熱分解型発泡剤を発泡させて、発泡シートを得る工程
工程（４）：ＭＤ及びＴＤの両方に延伸させて発泡シートを延伸する工程
[Method of manufacturing resin foam sheet]
The resin foam sheet of the present invention can be produced, for example, by crosslinking a foamable resin composition containing a resin and a thermally decomposable foaming agent, heating the composition to foam the thermally decomposable foaming agent, and stretching the composition in both TD and MD.
More specifically, the production method includes the following steps (1) to (4).
Step (1): A step of mixing a resin, a thermally decomposable foaming agent, and other additives blended as necessary, and forming the mixture into a sheet-shaped foamable resin composition (resin sheet). Step (2): A step of irradiating the sheet-shaped foamable resin composition with ionizing radiation to crosslink the foamable resin composition. Step (3): A step of heating the crosslinked foamable resin composition to foam the thermally decomposable foaming agent and obtain a foamed sheet. Step (4): A step of stretching the foamed sheet in both MD and TD.
工程（１）において、樹脂シートを成形する方法は、特に限定されないが、例えば、樹脂、熱分解型発泡剤、及びその他必要に応じて配合される添加剤を押出機に供給して溶融混練し、押出機から発泡性樹脂組成物をシート状に押出すことによって樹脂シートを成形すればよい。
工程（２）において発泡性樹脂組成物を架橋する方法としては、樹脂シートに電子線、α線、β線、γ線等の電離性放射線を照射する方法を用いる。上記電離性放射線の照射量は、得られる発泡シートの架橋度が上記した所望の範囲となるように調整すればよいが、３．５～１３Ｍｒａｄであることが好ましく、４～８Ｍｒａｄであることがより好ましい。また、これら電離性放射線の加速電圧は、特に限定されないが、例えば、４００～８００ｋＶであることが好ましい。
工程（３）において、発泡性樹脂組成物を加熱し熱分解型発泡剤を発泡させるときの加熱温度は、熱分解型発泡剤の発泡温度以上であればよいが、好ましくは２００～３００℃、より好ましくは２２０～２８０℃である。
In step (1), the method for molding the resin sheet is not particularly limited. For example, the resin, the thermally decomposable foaming agent, and other additives that are blended as necessary are supplied to an extruder, melt-kneaded, and the foamable resin composition is extruded from the extruder into a sheet shape to mold the resin sheet.
In the step (2), the foamable resin composition is crosslinked by irradiating the resin sheet with ionizing radiation such as electron beams, α-rays, β-rays, or γ-rays. The dose of the ionizing radiation may be adjusted so that the crosslinking degree of the resulting foamed sheet falls within the desired range described above, and is preferably 3.5 to 13 Mrad, and more preferably 4 to 8 Mrad. The accelerating voltage of the ionizing radiation is not particularly limited, but is preferably, for example, 400 to 800 kV.
In the step (3), the heating temperature when the foamable resin composition is heated to foam the thermally decomposable foaming agent may be equal to or higher than the foaming temperature of the thermally decomposable foaming agent, and is preferably 200 to 300°C, more preferably 220 to 280°C.
工程（４）における発泡シートの延伸は、ＭＤ及びＴＤの両方に行う。発泡シートの延伸は、樹脂シートを発泡させて発泡シートを得た後に行ってもよいし、樹脂シートを発泡させつつ行ってもよい。なお、樹脂シートを発泡させて発泡シートを得た後、発泡シートを延伸する場合には、発泡シートを冷却することなく発泡時の溶融状態を維持したまま続けて発泡シートを延伸してもよく、発泡シートを冷却した後、再度、発泡シートを加熱して溶融又は軟化状態とした上で発泡シートを延伸してもよい。発泡シートは延伸することで薄厚にしやすくなる。 In step (4), the foam sheet is stretched in both MD and TD. The foam sheet may be stretched after the resin sheet is foamed to obtain a foam sheet, or may be stretched while the resin sheet is foamed. When the foam sheet is stretched after the resin sheet is foamed to obtain a foam sheet, the foam sheet may be stretched without cooling the foam sheet while maintaining the molten state at the time of foaming, or the foam sheet may be stretched after cooling by heating the foam sheet again to a molten or softened state. Stretching the foam sheet makes it easier to make it thinner.
工程（４）において、発泡シートのＭＤ及びＴＤへの延伸倍率は、いずれも１８０％以上が好ましく、２００％以上がより好ましく、２２０％以上がさらに好ましい。本製造方法では、ＭＤ及びＴＤ両方の延伸倍率を高くすることで、樹脂発泡シートの表面が柔軟となる。そのため、上記下限値以上とすると、アスカーＣ硬度が低くなり、圧縮６時間後及び１２時間後の圧縮応力を低くしやすくなる。ＭＤ及びＴＤへの延伸倍率は、いずれも４００％以下が好ましく、３５０％以下がより好ましく、３００％以下がさらに好ましい。延伸倍率は、これら上限値以下とすると、発泡シートが延伸中に破断したり、発泡中の発泡シートから発泡ガスが抜けて発泡倍率が著しく低下したりすることが防止される。また、延伸時に発泡シートは、例えば１００～２８０℃、好ましくは１５０～２６０℃に加熱すればよい。なお、延伸倍率は、元の長さを１００％として、延伸後の発泡シートの長さを％で示す。 In step (4), the stretch ratios of the foam sheet in both MD and TD are preferably 180% or more, more preferably 200% or more, and even more preferably 220% or more. In this manufacturing method, the surface of the resin foam sheet becomes flexible by increasing the stretch ratios in both MD and TD. Therefore, when the stretch ratios are set to the above lower limit or more, the Asker C hardness decreases, and it becomes easier to reduce the compressive stress after 6 hours and 12 hours of compression. The stretch ratios of both MD and TD are preferably 400% or less, more preferably 350% or less, and even more preferably 300% or less. When the stretch ratios are set to the upper limit or less, the foam sheet is prevented from breaking during stretching, and the foaming gas is prevented from escaping from the foam sheet during foaming, which causes a significant decrease in the foaming ratio. In addition, the foam sheet may be heated to, for example, 100 to 280°C, preferably 150 to 260°C, during stretching. The stretch ratio is expressed in % as the length of the foam sheet after stretching, with the original length being 100%.
ただし、樹脂発泡シートの製造方法は、上記に限定されずに、上記以外の方法により、樹脂発泡シートを得てもよい。例えば、電離性放射線を照射する代わりに、発泡性樹脂組成物に予め有機過酸化物を配合しておき、発泡性樹脂組成物を加熱して有機過酸化物を分解させる方法等により架橋を行ってもよい。 However, the method for producing the resin foam sheet is not limited to the above, and the resin foam sheet may be obtained by a method other than the above. For example, instead of irradiating with ionizing radiation, crosslinking may be performed by a method in which an organic peroxide is mixed in advance with the foamable resin composition, and the foamable resin composition is heated to decompose the organic peroxide.
［粘着テープ］
本発明の樹脂発泡シートは、樹脂発泡シートを基材とする粘着テープに使用してもよい。粘着テープは、例えば、樹脂発泡シートと、樹脂発泡シートの少なくともいずれか一方の面に設けた粘着材とを備えるものである。粘着テープは、粘着材を介して他の部材に接着することが可能になる。粘着テープは、樹脂発泡シートの両面に粘着材を設けたものでもよいし、片面に粘着材を設けたものでもよい。
また、粘着材は、少なくとも粘着剤層を備えるものであればよく、樹脂発泡シートの表面に積層された粘着剤層単体であってもよいし、樹脂発泡シートの表面に貼付された両面粘着シートであってもよいが、粘着剤層単体であることが好ましい。なお、両面粘着シートは、基材と、基材の両面に設けられた粘着剤層とを備えるものである。両面粘着シートは、一方の粘着剤層を樹脂発泡シートに接着させるとともに、他方の粘着剤層を他の部材に接着させるために使用する。
粘着剤層を構成する粘着剤としては、特に制限はなく、例えば、アクリル系粘着剤、ウレタン系粘着剤、ゴム系粘着剤等を用いることができる。また、粘着材の上には、さらに離型紙等の剥離シートが貼り合わされてもよい。
粘着材の厚さは、５～２００μｍであることが好ましく、より好ましくは７～１５０μｍであり、更に好ましくは１０～１００μｍである。
[Adhesive tape]
The resin foam sheet of the present invention may be used for an adhesive tape using the resin foam sheet as a substrate. The adhesive tape includes, for example, a resin foam sheet and an adhesive material provided on at least one surface of the resin foam sheet. The adhesive tape can be adhered to other members via the adhesive material. The adhesive tape may include an adhesive material provided on both surfaces of the resin foam sheet, or an adhesive material provided on one surface.
The adhesive material may be one that includes at least an adhesive layer, and may be a single adhesive layer laminated on the surface of the resin foam sheet, or a double-sided adhesive sheet attached to the surface of the resin foam sheet, but is preferably a single adhesive layer. The double-sided adhesive sheet includes a substrate and adhesive layers provided on both sides of the substrate. The double-sided adhesive sheet is used to adhere one adhesive layer to the resin foam sheet and adhere the other adhesive layer to another member.
The adhesive constituting the adhesive layer is not particularly limited, and for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, etc. may be used. In addition, a release sheet such as release paper may be further attached onto the adhesive material.
The thickness of the adhesive material is preferably 5 to 200 μm, more preferably 7 to 150 μm, and further preferably 10 to 100 μm.
［樹脂発泡シートの使用方法］
本発明の樹脂発泡シートは、具体的には、液晶パネル等の表示パネルの衝撃吸収材として使用される。表示パネルの衝撃吸収材は、表示パネルの背面側に配置され、表示パネルに作用される衝撃を吸収して、表示パネルの破損、故障を防止する。また、本発明の樹脂発泡シートは、表示パネルの背面側に配置されることで、表示パネルにおけるプーリングの発生を防止する。
[How to use resin foam sheet]
Specifically, the resin foam sheet of the present invention is used as an impact absorbing material for a display panel such as a liquid crystal panel. The impact absorbing material for the display panel is disposed on the rear side of the display panel and absorbs impacts acting on the display panel to prevent damage and breakdown of the display panel. In addition, the resin foam sheet of the present invention, disposed on the rear side of the display panel, prevents pooling from occurring in the display panel.
樹脂発泡シートは、例えば、表示装置に組み込まれて使用される。したがって、表示装置は、例えば、支持部材の上に配置された本発明の樹脂発泡シートと、その樹脂発泡シートの上に配置された表示パネルとを備える。なお、支持部材は、例えば、各種携帯装置の筺体等の一部を構成するものである。また、支持部材と樹脂発泡シートの間や、樹脂発泡シートと表示パネルの間には、樹脂フィルム等の他のシート部材が配置されていてもよい。
表示装置に使用される樹脂発泡シートは、上記したように粘着材が設けられた粘着テープとされてもよく、粘着材によって表示パネル、支持部材、又は他の樹脂フィルムに貼り合わせられてもよい。
本発明において、発泡シートが使用される表示パネルは、タッチパネルであることが好ましい。タッチパネルの表面は、高速で繰り返し押圧されるが、樹脂発泡シートがプーリングの発生を抑制するので、表示装置の表示性能が改善される。
The resin foam sheet is incorporated into, for example, a display device. Thus, the display device includes, for example, the resin foam sheet of the present invention arranged on a support member, and a display panel arranged on the resin foam sheet. The support member, for example, constitutes a part of the housing of various portable devices. In addition, other sheet members such as resin films may be arranged between the support member and the resin foam sheet, or between the resin foam sheet and the display panel.
The resin foam sheet used in the display device may be in the form of an adhesive tape provided with an adhesive material as described above, and may be attached to a display panel, a support member, or another resin film by the adhesive material.
In the present invention, the display panel in which the foamed sheet is used is preferably a touch panel. The surface of the touch panel is repeatedly pressed at high speed, but the resin foamed sheet suppresses the occurrence of pooling, improving the display performance of the display device.
以下、本発明を実施例により更に詳細に説明するが、本発明はこれらの例によってなんら限定されるものではない。 The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
なお、本明細書における各種物性、評価方法は、以下のとおりである。
＜厚み＞
ＪＩＳ Ｋ６７６７の方法に従って測定した。
＜見掛け密度＞
ＪＩＳ Ｋ６７６７の方法に従って測定した。
＜発泡倍率＞
見掛け密度の逆数を発泡倍率とした。
＜アスカーＣ硬度＞
ＪＩＳ K ７３１２の方法に従って測定した。なお、アスカーＣ硬度が樹脂発泡シートの両面で異なる場合、平均値を樹脂発泡シートの表面のアスカー硬度とする。
＜独立気泡率＞
独立気泡率は、明細書記載の方法で測定した。
＜架橋度＞
架橋度は、明細書記載の方法で測定したものである。
＜２５％、５０％圧縮強度＞
ＪＩＳ Ｋ６７６７の方法に従って測定した。
＜引張強度＞
ＪＩＳ Ｋ６７６７の方法に従って測定した。
In the present specification, various physical properties and evaluation methods are as follows.
<Thickness>
Measurement was performed according to the method of JIS K6767.
<Apparent density>
Measurement was performed according to the method of JIS K6767.
<Expansion ratio>
The reciprocal of the apparent density was taken as the expansion ratio.
<Asker C hardness>
It was measured according to the method of JIS K 7312. When the Asker C hardness differs between the two surfaces of the resin foam sheet, the average value is regarded as the Asker hardness of the surface of the resin foam sheet.
<Closed bubble ratio>
The closed cell ratio was measured by the method described in the specification.
<Degree of crosslinking>
The degree of crosslinking was measured by the method described in the specification.
<25% and 50% compression strength>
Measurement was performed according to the method of JIS K6767.
<Tensile strength>
Measurement was performed according to the method of JIS K6767.
＜圧縮６時間後及び１２時間後の圧縮応力＞
樹脂発泡シートを５０ｍｍ四方にカットし、１０枚重ねて、初期厚みに対して７５％の厚みとなるように２５％圧縮した状態にして、６時間後、１２時間後の応力を測定した。応力測定は、引張・圧縮試験機（株式会社エー・アンド・デイ製、製品名「TENSILON」、モデル「RTG-1250」）により、５０００Ｎのロードセルを用い、初期加重１０Ｎの設定で行った。
<Compressive stress after 6 hours and 12 hours of compression>
The resin foam sheet was cut into 50 mm squares, 10 sheets were stacked, and the sheet was compressed by 25% to a thickness of 75% of the initial thickness, and the stress was measured after 6 hours and 12 hours. The stress was measured using a tensile/compression tester (manufactured by A&D Co., Ltd., product name "TENSILON", model "RTG-1250") with a 5000 N load cell and an initial load of 10 N.
＜平均気泡径＞
樹脂発泡シートをＭＤ及びＴＤそれぞれに沿って厚さ方向に切断して、デジタルマイクロスコープ（株式会社キーエンス製、製品名「ＶＨＸ－９００」）を用いて２００倍の拡大写真を撮影した。撮影した拡大写真において、ＭＤ、ＴＤそれぞれにおける長さ２ｍｍ分の切断面に存在する全ての気泡についてＭＤ，ＺＤの気泡径、及びＴＤ，ＺＤの気泡径を測定し、その操作を５回繰り返した。そして、全ての気泡のＭＤ、ＴＤそれぞれの気泡径の平均値をＭＤ、ＴＤの平均気泡径とするとともに、以上の操作によって測定された全てのＺＤの気泡径の平均値をＺＤの平均気泡径とした。
<Average bubble diameter>
The resin foam sheet was cut in the thickness direction along each of the MD and TD, and a 200x magnified photograph was taken using a digital microscope (manufactured by Keyence Corporation, product name "VHX-900"). In the magnified photograph, the MD and ZD bubble diameters and the TD and ZD bubble diameters were measured for all bubbles present on the cut surface of 2 mm length in each of the MD and TD, and this operation was repeated five times. The average value of the bubble diameters of all bubbles in the MD and TD was taken as the average bubble diameter of MD and TD, and the average value of the bubble diameters of all ZDs measured by the above operation was taken as the average bubble diameter of ZD.
＜衝撃吸収率＞
樹脂発泡シートを５０ｍｍ四方にカットし、アクリル板の上に置いたうえで、４．３ｇの鉄球を３０ｃｍの高さから落とし、アクリル板に作用される衝撃を測定した。その後、樹脂発泡シートを除き、同様に鉄球を落とし、アクリル板に作用される衝撃をブランクとして測定し、以下の式により、樹脂発泡シートの衝撃吸収率を算出した。
衝撃吸収率（％）＝（ブランクの衝撃－樹脂発泡シートを置いたときの衝撃）÷ブランクの衝撃×１００
<Impact absorption rate>
The resin foam sheet was cut into 50 mm squares and placed on an acrylic plate, and a 4.3 g iron ball was dropped from a height of 30 cm to measure the impact on the acrylic plate. Thereafter, the resin foam sheet was removed, and the iron ball was dropped in the same manner to measure the impact on the acrylic plate as a blank, and the impact absorption rate of the resin foam sheet was calculated by the following formula.
Impact absorption rate (%) = (Impact of blank - Impact when resin foam sheet is placed) ÷ Impact of blank × 100
＜耐プーリング性＞
５０ｍｍ×７０ｍｍにカットした樹脂発泡シートの上に、４．７インチの液晶パネルを配置させ、液晶パネルの表面を押し棒で１０Ｎの力で押した。プーリングが抑えられ、かつプーリングの消失速度の速いもの“Ａ”とし、プーリングが抑えられないが消失速度が速いものを“Ｂ”とし、プーリングが抑えられず、消失速度も遅いものを“Ｃ”とした。
<Pooling resistance>
A 4.7-inch liquid crystal panel was placed on a resin foam sheet cut to 50 mm x 70 mm, and the surface of the liquid crystal panel was pressed with a push rod with a force of 10 N. The sample in which pooling was suppressed and the pooling disappearance rate was fast was designated "A," the sample in which pooling was not suppressed but the disappearance rate was fast was designated "B," and the sample in which pooling was not suppressed and the disappearance rate was slow was designated "C."
実施例、及び比較例では、以下の成分を使用した。
ポリエチレン系樹脂（１）：メタロセン化合物を用いて得られた直鎖状低密度ポリエチレン［エクソン・ケミカル社製、商品名．ＥＸＡＣＴ３０２７、密度０．９００ｇ／ｃｍ3］
ポリエチレン系樹脂（２）：日本ポリエチレン株式会社製、商品名．カーネルＫＦ３７０
熱分解型発泡剤：アゾジカルボンアミド
酸化防止剤：２，６－ジ－ｔ－ブチル－ｐ－クレゾール
気泡核調整剤：酸化亜鉛
In the examples and comparative examples, the following components were used.
Polyethylene resin (1): Linear low-density polyethylene obtained using a metallocene compound [manufactured by Exxon Chemical Company, trade name EXACT3027, density 0.900 g/cm 3 ]
Polyethylene resin (2): Trade name: Kernel KF370, manufactured by Japan Polyethylene Corporation
Thermal decomposition type foaming agent: azodicarbonamide Antioxidant: 2,6-di-t-butyl-p-cresol Bubble nucleus regulator: zinc oxide
[実施例１]
ポリエチレン系樹脂（１）１００質量部と、熱分解型発泡剤４質量部と、酸化防止剤０．３質量部と、気泡核調整剤１質量部とを押出機に供給して１３０℃で溶融混練し、厚み約０．２ｍｍの樹脂シートとして押出した。次に、樹脂シートを、その両面に加速電圧５００ｋＶの電子線を５Ｍｒａｄ照射して架橋した後、熱風及び赤外線ヒーターにより２５０℃に保持された発泡炉内に連続的に送り込んで加熱させて発泡させた。発泡シートは、発泡させながらＭＤの延伸倍率２３０％、ＴＤの延伸倍率２３０％で延伸させ、厚み０．１５ｍｍで架橋度２５％の樹脂発泡シートを得た。得られた発泡シートの評価結果を表１に示す。
[Example 1]
100 parts by mass of polyethylene resin (1), 4 parts by mass of a thermal decomposition type foaming agent, 0.3 parts by mass of an antioxidant, and 1 part by mass of a bubble nucleation regulator were fed to an extruder, melt-kneaded at 130 ° C., and extruded as a resin sheet with a thickness of about 0.2 mm. Next, the resin sheet was crosslinked by irradiating both sides with an electron beam of 500 kV at an acceleration voltage of 5 Mrad, and then continuously sent into a foaming furnace maintained at 250 ° C. by hot air and an infrared heater, and heated to foam. The foamed sheet was stretched at a stretch ratio of 230% in MD and 230% in TD while foaming, to obtain a resin foamed sheet with a thickness of 0.15 mm and a crosslinking degree of 25%. The evaluation results of the obtained foamed sheet are shown in Table 1.
[実施例２]
表１に示す気泡径となるように延伸倍率を調整した点以外は、実施例１と同様に実施した。
[実施例３]
直鎖状低密度ポリエチレン（ポリエチレン系樹脂（１））を、ポリエチレン系樹脂（２）（「カーネルＦＫ３７０」）として配合量を３０質量部に変更するとともに、ポリオレフィン系樹脂としてエチレン－酢酸ビニル共重合体（東ソー株式会社製「ウルトラセン６３６」、酢酸ビニル含有率１９質量％)を７０質量部さらに配合した。また、表１に示す気泡径となるように延伸倍率を調整した点以外は、実施例１と同様に実施した。
［比較例１，２］
表１に示すとおりに、熱分解型発泡剤の質量部を調整し、かつ表２に記載の架橋度となるように電子線の照射量を調整した。また、表１に記載される気泡径となるように、ＭＤ及びＴＤの延伸倍率がいずれも１８０％未満となるようにした点以外は、実施例１と同様に実施した。
[Example 2]
The same procedure as in Example 1 was carried out, except that the stretch ratio was adjusted so as to obtain the air bubble diameter shown in Table 1.
[Example 3]
The amount of linear low-density polyethylene (polyethylene resin (1)) mixed as polyethylene resin (2) ("Kernel FK370") was changed to 30 parts by mass, and 70 parts by mass of an ethylene-vinyl acetate copolymer ("Ultrathene 636" manufactured by Tosoh Corporation, vinyl acetate content 19% by mass) was further mixed as a polyolefin resin. The same procedure as in Example 1 was repeated, except that the stretch ratio was adjusted to obtain the cell diameter shown in Table 1.
[Comparative Examples 1 and 2]
The parts by mass of the thermally decomposable foaming agent were adjusted as shown in Table 1, and the amount of electron beam irradiation was adjusted so as to obtain the degree of crosslinking shown in Table 2. The same procedure as in Example 1 was repeated, except that the stretch ratios in both MD and TD were less than 180% so as to obtain the cell diameters shown in Table 1.
表１に示すように、実施例１、２、３では、圧縮６時間後、及び１２時間後の圧縮応力を規定値以下とすることで、衝撃吸収性を良好にしつつ、耐プーリング特性を優れたものにすることができた。それに対して、比較例１、２では、圧縮６時間後又は１２時間後の圧縮応力が規定値を越えたため、衝撃吸収性を良好にしつつ、耐プーリング特性を優れたものにすることができなかった。 As shown in Table 1, in Examples 1, 2, and 3, the compressive stress after 6 and 12 hours of compression was set to a value below the specified value, which enabled the shock absorption to be good while the anti-pooling properties to be excellent. In contrast, in Comparative Examples 1 and 2, the compressive stress after 6 or 12 hours of compression exceeded the specified value, so the shock absorption to be good while the anti-pooling properties could not be excellent.
Claims (8)
３．６≦ＭＤの平均気泡径／ＺＤの平均気泡径≦８ （１）
４．８≦ＴＤの平均気泡径／ＺＤの平均気泡径≦８ （２） A resin foam sheet, wherein, when the resin foam sheet is compressed to a thickness of 75% of its initial thickness, the compressive stress after 6 hours is 400 Pa or less and the compressive stress after 12 hours is 300 Pa or less, the average cell diameter satisfies the following formulas (1) and (2), the resin foam sheet has an Asker C hardness of 1 or more and 15 or less, the volume ratio to the weight of the resin foam sheet is 8 cm3 /g or more and 14 cm3 /g or less, the resin foam sheet has an MD average cell diameter of 60 μm or more and 350 μm or less, a TD average cell diameter of 50 μm or more and 350 μm or less, and a ZD average cell diameter of 10 μm or more and 70 μm or less , and a closed cell ratio of 70% or more .
3.6≦Average cell diameter in MD/Average cell diameter in ZD≦8 (1)
4.8≦average bubble diameter of TD/average bubble diameter of ZD≦8 (2)
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| US10174178B2 (en) * | 2014-09-30 | 2019-01-08 | Sekisui Chemical Co., Ltd. | Polyolefin resin foam sheet and adhesive tape |
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| JPWO2017170786A1 (en) * | 2016-03-30 | 2019-02-14 | 積水化学工業株式会社 | Foamable resin sheet and heat conductive foam sheet for electronic equipment |
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| JP2015091920A (en) | 2013-09-30 | 2015-05-14 | 積水化学工業株式会社 | Porous sheet and manufacturing method therefor |
| JP2015153977A (en) | 2014-02-18 | 2015-08-24 | 積水化学工業株式会社 | Seal material for solar cell and laminated seal material for solar cell |
| JP2016088977A (en) | 2014-10-31 | 2016-05-23 | 日東電工株式会社 | Resin foam and foam member |
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