CN117946606A - Adhesive composition for foldable display and adhesive sheet - Google Patents
Adhesive composition for foldable display and adhesive sheet Download PDFInfo
- Publication number
- CN117946606A CN117946606A CN202311311870.6A CN202311311870A CN117946606A CN 117946606 A CN117946606 A CN 117946606A CN 202311311870 A CN202311311870 A CN 202311311870A CN 117946606 A CN117946606 A CN 117946606A
- Authority
- CN
- China
- Prior art keywords
- meth
- acrylate
- monomer
- acrylic
- adhesive
- 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.)
- Granted
Links
- 239000000853 adhesive Substances 0.000 title claims abstract description 187
- 230000001070 adhesive effect Effects 0.000 title claims abstract description 187
- 239000000203 mixture Substances 0.000 title claims abstract description 61
- 239000000178 monomer Substances 0.000 claims abstract description 161
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 128
- 229920006243 acrylic copolymer Polymers 0.000 claims abstract description 74
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims abstract description 69
- 230000009477 glass transition Effects 0.000 claims abstract description 61
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 56
- 125000000524 functional group Chemical group 0.000 claims abstract description 45
- 230000008859 change Effects 0.000 claims abstract description 38
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 28
- 229920001519 homopolymer Polymers 0.000 claims abstract description 20
- 125000005907 alkyl ester group Chemical group 0.000 claims abstract description 7
- 239000012790 adhesive layer Substances 0.000 claims description 61
- 238000004519 manufacturing process Methods 0.000 claims description 32
- -1 beta-carboxyethyl Chemical group 0.000 claims description 20
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 12
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 claims description 12
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 12
- GOXQRTZXKQZDDN-UHFFFAOYSA-N 2-Ethylhexyl acrylate Chemical compound CCCCC(CC)COC(=O)C=C GOXQRTZXKQZDDN-UHFFFAOYSA-N 0.000 claims description 9
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 9
- SXIFAEWFOJETOA-UHFFFAOYSA-N 4-hydroxy-butyl Chemical group [CH2]CCCO SXIFAEWFOJETOA-UHFFFAOYSA-N 0.000 claims description 8
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 8
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 8
- 239000004593 Epoxy Substances 0.000 claims description 7
- DXPPIEDUBFUSEZ-UHFFFAOYSA-N 6-methylheptyl prop-2-enoate Chemical compound CC(C)CCCCCOC(=O)C=C DXPPIEDUBFUSEZ-UHFFFAOYSA-N 0.000 claims description 6
- CUXGDKOCSSIRKK-UHFFFAOYSA-N 7-methyloctyl prop-2-enoate Chemical compound CC(C)CCCCCCOC(=O)C=C CUXGDKOCSSIRKK-UHFFFAOYSA-N 0.000 claims description 6
- GMSCBRSQMRDRCD-UHFFFAOYSA-N dodecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCOC(=O)C(C)=C GMSCBRSQMRDRCD-UHFFFAOYSA-N 0.000 claims description 6
- LNMQRPPRQDGUDR-UHFFFAOYSA-N hexyl prop-2-enoate Chemical compound CCCCCCOC(=O)C=C LNMQRPPRQDGUDR-UHFFFAOYSA-N 0.000 claims description 6
- MDYPDLBFDATSCF-UHFFFAOYSA-N nonyl prop-2-enoate Chemical compound CCCCCCCCCOC(=O)C=C MDYPDLBFDATSCF-UHFFFAOYSA-N 0.000 claims description 6
- ANISOHQJBAQUQP-UHFFFAOYSA-N octyl prop-2-enoate Chemical compound CCCCCCCCOC(=O)C=C ANISOHQJBAQUQP-UHFFFAOYSA-N 0.000 claims description 6
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 claims description 5
- SJMYWORNLPSJQO-UHFFFAOYSA-N tert-butyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC(C)(C)C SJMYWORNLPSJQO-UHFFFAOYSA-N 0.000 claims description 5
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 claims description 4
- OIWOHHBRDFKZNC-UHFFFAOYSA-N cyclohexyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC1CCCCC1 OIWOHHBRDFKZNC-UHFFFAOYSA-N 0.000 claims description 4
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical compound C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 claims description 4
- 125000003700 epoxy group Chemical group 0.000 claims description 4
- 125000003055 glycidyl group Chemical group C(C1CO1)* 0.000 claims description 4
- PSGCQDPCAWOCSH-UHFFFAOYSA-N (4,7,7-trimethyl-3-bicyclo[2.2.1]heptanyl) prop-2-enoate Chemical compound C1CC2(C)C(OC(=O)C=C)CC1C2(C)C PSGCQDPCAWOCSH-UHFFFAOYSA-N 0.000 claims description 3
- RUMACXVDVNRZJZ-UHFFFAOYSA-N 2-methylpropyl 2-methylprop-2-enoate Chemical compound CC(C)COC(=O)C(C)=C RUMACXVDVNRZJZ-UHFFFAOYSA-N 0.000 claims description 3
- IAXXETNIOYFMLW-COPLHBTASA-N [(1s,3s,4s)-4,7,7-trimethyl-3-bicyclo[2.2.1]heptanyl] 2-methylprop-2-enoate Chemical compound C1C[C@]2(C)[C@@H](OC(=O)C(=C)C)C[C@H]1C2(C)C IAXXETNIOYFMLW-COPLHBTASA-N 0.000 claims description 3
- SUPCQIBBMFXVTL-UHFFFAOYSA-N ethyl 2-methylprop-2-enoate Chemical compound CCOC(=O)C(C)=C SUPCQIBBMFXVTL-UHFFFAOYSA-N 0.000 claims description 3
- 229940119545 isobornyl methacrylate Drugs 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 238000005452 bending Methods 0.000 abstract description 51
- 230000000052 comparative effect Effects 0.000 description 59
- 239000011521 glass Substances 0.000 description 29
- 238000012360 testing method Methods 0.000 description 24
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 21
- 238000011156 evaluation Methods 0.000 description 19
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 17
- 230000003287 optical effect Effects 0.000 description 14
- 239000000243 solution Substances 0.000 description 14
- 230000007423 decrease Effects 0.000 description 12
- 239000003505 polymerization initiator Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- 238000004132 cross linking Methods 0.000 description 11
- 238000000034 method Methods 0.000 description 10
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 9
- 150000001875 compounds Chemical class 0.000 description 9
- 238000009472 formulation Methods 0.000 description 9
- 239000010410 layer Substances 0.000 description 9
- 239000002994 raw material Substances 0.000 description 9
- 229920005989 resin Polymers 0.000 description 9
- 239000011347 resin Substances 0.000 description 9
- 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 8
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000012986 chain transfer agent Substances 0.000 description 7
- 239000012948 isocyanate Substances 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 239000000654 additive Substances 0.000 description 6
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 6
- 150000002513 isocyanates Chemical class 0.000 description 6
- 239000013522 chelant Substances 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 4
- NDWUBGAGUCISDV-UHFFFAOYSA-N 4-hydroxybutyl prop-2-enoate Chemical compound OCCCCOC(=O)C=C NDWUBGAGUCISDV-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 238000012512 characterization method Methods 0.000 description 4
- 239000007810 chemical reaction solvent Substances 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- 229920001721 polyimide Polymers 0.000 description 4
- 238000010992 reflux Methods 0.000 description 4
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 3
- 229920002799 BoPET Polymers 0.000 description 3
- 239000004642 Polyimide Substances 0.000 description 3
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 3
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 3
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 3
- 238000013329 compounding Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000005056 polyisocyanate Substances 0.000 description 3
- 229920001228 polyisocyanate Polymers 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 description 3
- WRXCBRHBHGNNQA-UHFFFAOYSA-N (2,4-dichlorobenzoyl) 2,4-dichlorobenzenecarboperoxoate Chemical compound ClC1=CC(Cl)=CC=C1C(=O)OOC(=O)C1=CC=C(Cl)C=C1Cl WRXCBRHBHGNNQA-UHFFFAOYSA-N 0.000 description 2
- ZICNIEOYWVIEQJ-UHFFFAOYSA-N (2-methylbenzoyl) 2-methylbenzenecarboperoxoate Chemical compound CC1=CC=CC=C1C(=O)OOC(=O)C1=CC=CC=C1C ZICNIEOYWVIEQJ-UHFFFAOYSA-N 0.000 description 2
- FVQMJJQUGGVLEP-UHFFFAOYSA-N (2-methylpropan-2-yl)oxy 2-ethylhexaneperoxoate Chemical compound CCCCC(CC)C(=O)OOOC(C)(C)C FVQMJJQUGGVLEP-UHFFFAOYSA-N 0.000 description 2
- FKTHNVSLHLHISI-UHFFFAOYSA-N 1,2-bis(isocyanatomethyl)benzene Chemical compound O=C=NCC1=CC=CC=C1CN=C=O FKTHNVSLHLHISI-UHFFFAOYSA-N 0.000 description 2
- UICXTANXZJJIBC-UHFFFAOYSA-N 1-(1-hydroperoxycyclohexyl)peroxycyclohexan-1-ol Chemical compound C1CCCCC1(O)OOC1(OO)CCCCC1 UICXTANXZJJIBC-UHFFFAOYSA-N 0.000 description 2
- WFUGQJXVXHBTEM-UHFFFAOYSA-N 2-hydroperoxy-2-(2-hydroperoxybutan-2-ylperoxy)butane Chemical compound CCC(C)(OO)OOC(C)(CC)OO WFUGQJXVXHBTEM-UHFFFAOYSA-N 0.000 description 2
- OMIGHNLMNHATMP-UHFFFAOYSA-N 2-hydroxyethyl prop-2-enoate Chemical compound OCCOC(=O)C=C OMIGHNLMNHATMP-UHFFFAOYSA-N 0.000 description 2
- RTANHMOFHGSZQO-UHFFFAOYSA-N 4-methoxy-2,4-dimethylpentanenitrile Chemical compound COC(C)(C)CC(C)C#N RTANHMOFHGSZQO-UHFFFAOYSA-N 0.000 description 2
- RRBONVXWAGQXDJ-UHFFFAOYSA-N 4-methoxybutyl 2-sulfanylacetate Chemical compound COCCCCOC(=O)CS RRBONVXWAGQXDJ-UHFFFAOYSA-N 0.000 description 2
- VIQGKXOVPDLASV-UHFFFAOYSA-N 4-methoxybutyl 2-sulfanylpropanoate Chemical compound COCCCCOC(=O)C(C)S VIQGKXOVPDLASV-UHFFFAOYSA-N 0.000 description 2
- 239000004342 Benzoyl peroxide Substances 0.000 description 2
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- YIVJZNGAASQVEM-UHFFFAOYSA-N Lauroyl peroxide Chemical compound CCCCCCCCCCCC(=O)OOC(=O)CCCCCCCCCCC YIVJZNGAASQVEM-UHFFFAOYSA-N 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- 239000004480 active ingredient Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000002318 adhesion promoter Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 2
- 239000002216 antistatic agent Substances 0.000 description 2
- 229920005601 base polymer Polymers 0.000 description 2
- 235000019400 benzoyl peroxide Nutrition 0.000 description 2
- 238000012662 bulk polymerization Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 2
- WNAHIZMDSQCWRP-UHFFFAOYSA-N dodecane-1-thiol Chemical compound CCCCCCCCCCCCS WNAHIZMDSQCWRP-UHFFFAOYSA-N 0.000 description 2
- 238000007720 emulsion polymerization reaction Methods 0.000 description 2
- 238000005227 gel permeation chromatography Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- QJAOYSPHSNGHNC-UHFFFAOYSA-N octadecane-1-thiol Chemical compound CCCCCCCCCCCCCCCCCCS QJAOYSPHSNGHNC-UHFFFAOYSA-N 0.000 description 2
- SRSFOMHQIATOFV-UHFFFAOYSA-N octanoyl octaneperoxoate Chemical compound CCCCCCCC(=O)OOC(=O)CCCCCCC SRSFOMHQIATOFV-UHFFFAOYSA-N 0.000 description 2
- MADOXCFISYCULS-UHFFFAOYSA-N octyl 2-sulfanylacetate Chemical compound CCCCCCCCOC(=O)CS MADOXCFISYCULS-UHFFFAOYSA-N 0.000 description 2
- SFHANYOFMGEJCT-UHFFFAOYSA-N octyl 2-sulfanylpropanoate Chemical compound CCCCCCCCOC(=O)C(C)S SFHANYOFMGEJCT-UHFFFAOYSA-N 0.000 description 2
- 150000001451 organic peroxides Chemical class 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 150000002978 peroxides Chemical class 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- FZYCEURIEDTWNS-UHFFFAOYSA-N prop-1-en-2-ylbenzene Chemical compound CC(=C)C1=CC=CC=C1.CC(=C)C1=CC=CC=C1 FZYCEURIEDTWNS-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- OPQYOFWUFGEMRZ-UHFFFAOYSA-N tert-butyl 2,2-dimethylpropaneperoxoate Chemical compound CC(C)(C)OOC(=O)C(C)(C)C OPQYOFWUFGEMRZ-UHFFFAOYSA-N 0.000 description 2
- CIHOLLKRGTVIJN-UHFFFAOYSA-N tert‐butyl hydroperoxide Chemical compound CC(C)(C)OO CIHOLLKRGTVIJN-UHFFFAOYSA-N 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 150000003573 thiols Chemical class 0.000 description 2
- RTTZISZSHSCFRH-UHFFFAOYSA-N 1,3-bis(isocyanatomethyl)benzene Chemical compound O=C=NCC1=CC=CC(CN=C=O)=C1 RTTZISZSHSCFRH-UHFFFAOYSA-N 0.000 description 1
- DFPJRUKWEPYFJT-UHFFFAOYSA-N 1,5-diisocyanatopentane Chemical compound O=C=NCCCCCN=C=O DFPJRUKWEPYFJT-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- NOWKCMXCCJGMRR-UHFFFAOYSA-N Aziridine Chemical compound C1CN1 NOWKCMXCCJGMRR-UHFFFAOYSA-N 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 1
- 239000005058 Isophorone diisocyanate Substances 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 239000004695 Polyether sulfone Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 125000005396 acrylic acid ester group Chemical group 0.000 description 1
- 125000005250 alkyl acrylate group Chemical group 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- OHJMTUPIZMNBFR-UHFFFAOYSA-N biuret Chemical class NC(=O)NC(N)=O OHJMTUPIZMNBFR-UHFFFAOYSA-N 0.000 description 1
- QHIWVLPBUQWDMQ-UHFFFAOYSA-N butyl prop-2-enoate;methyl 2-methylprop-2-enoate;prop-2-enoic acid Chemical compound OC(=O)C=C.COC(=O)C(C)=C.CCCCOC(=O)C=C QHIWVLPBUQWDMQ-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 125000000753 cycloalkyl group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000000113 differential scanning calorimetry Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000003480 eluent Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 1
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical class OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 description 1
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 125000005397 methacrylic acid ester group Chemical group 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920003223 poly(pyromellitimide-1,4-diphenyl ether) Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 229930195734 saturated hydrocarbon Natural products 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/062—Copolymers with monomers not covered by C09J133/06
- C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
- C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
- C08F220/1804—C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
- C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
- C08F220/1806—C6-(meth)acrylate, e.g. (cyclo)hexyl (meth)acrylate or phenyl (meth)acrylate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
- C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
- C08F220/1808—C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/08—Macromolecular additives
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
- C09J2301/12—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers
- C09J2301/122—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers the adhesive layer being present only on one side of the carrier, e.g. single-sided adhesive tape
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J2467/00—Presence of polyester
- C09J2467/006—Presence of polyester in the substrate
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- Adhesive Tapes (AREA)
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Abstract
The present invention relates to an adhesive composition for a foldable display and an adhesive sheet. An adhesive composition for foldable displays, which has both bending resistance and high adhesive strength and suppresses the change of adhesive strength with time to a release film. The adhesive composition for a foldable display comprises: (meth) acrylic copolymer (A), (meth) acrylic tackifier (B) and crosslinking agent (C); wherein the (meth) acrylic copolymer (a) contains a monomer (A1) having a functional group and an alkyl (meth) acrylate monomer (A2) as structural units; the (meth) acrylic tackifier (B) comprises a monomer (B1) having a functional group, a (meth) acrylic alkyl ester monomer (B2) having a homopolymer glass transition temperature (Tg) of-50 ℃ or lower, and a (meth) acrylic (cyclo) alkyl ester monomer (B3) having a homopolymer glass transition temperature of 40 ℃ or higher as structural units.
Description
Technical Field
The present invention relates to an adhesive composition for a foldable display and an adhesive sheet.
Background
In recent years, portable electronic devices having a bendable display (so-called foldable display) have been increasingly popular. Since the foldable display is repeatedly bent at the same position, the adhesive sheet may be peeled off from the adherend at the bent portion. Accordingly, an adhesive composition for foldable display applications is required to be capable of forming an adhesive layer excellent in bending resistance. It is generally known that the higher the stress relaxation property of the adhesive layer is, the better the bending resistance is. As an example of a design in which the adhesive layer becomes soft, the lower the glass transition temperature (Tg) of the (meth) acrylic copolymer in the adhesive composition is, the more an adhesive layer excellent in bending resistance can be formed. However, when the pressure-sensitive adhesive layer is designed to be soft, the pressure-sensitive adhesive layer tends to have a problem of a decrease in cohesive force and a significant decrease in adhesive force, although the bending resistance is improved. As a result, the bending resistance and the adhesive force are in a trade-off relationship, and thus, it is difficult to achieve both performance improvements.
Accordingly, patent document 1 proposes, as a method for improving bending resistance without reducing adhesive force, an adhesive sheet comprising an acrylic base polymer having a crosslinked structure and an acrylic oligomer having a glass transition temperature (Tg) of 60 ℃ or higher.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2020-122140
Disclosure of Invention
Problems to be solved by the invention
However, since the (meth) acrylic oligomer used in the adhesive composition of patent document 1 has a glass transition temperature (Tg) of 60 ℃ or higher (i.e., a high Tg), the (meth) acrylic oligomer has poor stress relaxation properties, and when stress is accumulated due to long-term repeated bending operation, appearance defects such as lifting and peeling tend to occur easily. Therefore, the technique of patent document 1 cannot meet high requirements regarding bending resistance. Further, an adhesive sheet made of an adhesive layer containing a (meth) acrylic oligomer having a high Tg tends to have an adhesive force to a release film that increases with time. This is thought to be because the (meth) acrylic oligomer has a very low molecular weight compared to the (meth) acrylic base polymer, and therefore tends to move to the surface of the adhesive layer with time, and further because the (meth) acrylic oligomer component moving to the surface of the adhesive layer has a high Tg, the cohesive force at the interface between the release film and the adhesive layer is excessively increased. That is, when a long time passes after the pressure-sensitive adhesive sheet is processed, for example, by transportation, a large force is required to peel the pressure-sensitive adhesive sheet from the release film, and thus there is a possibility that the work is hindered. Thus, the technique of patent document 1 has the following problems: the properties of bending resistance and high adhesion cannot be sufficiently combined, and the adhesion to a release film increases with time.
Accordingly, an object of the present invention is to provide an adhesive composition for a foldable display, which suppresses the change with time of the adhesive force to a release film while satisfying both the 2 properties of bending resistance and high adhesive force.
Solution for solving the problem
In order to achieve the object of the present invention, an adhesive composition for a foldable display of the present invention comprises: a (meth) acrylic copolymer (a) containing a monomer (A1) having a functional group and an alkyl (meth) acrylate monomer (A2) as structural units; a (meth) acrylic tackifier (B) comprising, as structural units, a monomer (B1) having a functional group, an alkyl (meth) acrylate monomer (B2) having a homopolymer glass transition temperature (Tg) of-50 ℃ or lower, and a (cyclo) alkyl (meth) acrylate monomer (B3) having a homopolymer glass transition temperature of 40 ℃ or higher; and a crosslinking agent (C), wherein the glass transition temperature (Tg) of the (meth) acrylic copolymer (A) is-50 ℃ or lower, the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) is-10 ℃ or higher and 40 ℃ or lower, the glass transition temperature (Tg) of the (meth) acrylic copolymer (A) and the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) are determined based on the FOX formula, and the adhesive force of an adhesive layer formed from the adhesive composition for a foldable display is 6.0N/25mm or higher, wherein the adhesive force is according to JIS Z0237:2009, a measured value is specified.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide an adhesive composition for a foldable display, which can suppress the change with time of the adhesive force to a release film while satisfying both the 2 properties of bending resistance and high adhesive force.
Detailed Description
Hereinafter, embodiments will be described in detail. The following embodiments do not limit the scope of the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily.
< Adhesive composition for foldable display >
The adhesive composition for a foldable display of the present invention comprises: a (meth) acrylic copolymer (a) containing a monomer (A1) having a functional group and an alkyl (meth) acrylate monomer (A2) as structural units; a (meth) acrylic tackifier (B) comprising, as structural units, a monomer (B1) having a functional group, an alkyl (meth) acrylate monomer (B2) having a homopolymer glass transition temperature (Tg) of-50 ℃ or lower, and a (cyclo) alkyl (meth) acrylate monomer (B3) having a homopolymer glass transition temperature of 40 ℃ or higher; a crosslinking agent (C). The adhesive composition for a foldable display of the present invention may further comprise a crosslinking reaction accelerator in addition to the above-mentioned components (a) to (C).
The adhesive composition for foldable displays contains 0.5 to 20 parts by mass, preferably 0.5 to 14 parts by mass of the (meth) acrylic tackifier (B) per 100 parts by mass of the (meth) acrylic copolymer (a). Here, when the adhesive composition for a foldable display contains more than 20 parts by mass of the (meth) acrylic tackifier (B) per 100 parts by mass of the (meth) acrylic copolymer (a), the cohesive force of the adhesive layer excessively increases, and the stress relaxation property decreases, so that the bending resistance decreases. On the other hand, when the adhesive composition for a foldable display contains less than 0.5 parts by mass of the (meth) acrylic tackifier (B) per 100 parts by mass of the (meth) acrylic copolymer (a), the cohesive force of the adhesive layer is lowered and the adhesive force is lowered.
((Meth) acrylic copolymer (A))
The (meth) acrylic copolymer (a) contains a monomer (A1) having a functional group and an alkyl (meth) acrylate monomer (A2) as structural units. Here, in the case where the (meth) acrylic copolymer (a) does not contain the monomer (A1) having a functional group as a structural unit and contains only the alkyl (meth) acrylate monomer (A2) as a structural unit, the (meth) acrylic copolymer (a) does not have a component that reacts with the crosslinking agent (C), and thus cannot form a crosslinked structure. Therefore, proper cohesive force cannot be exerted, and a residual adhesive phenomenon due to cohesive failure occurs at the time of peeling. Further, since the crosslinked structure with the (meth) acrylic tackifier (B) via the crosslinking agent (C) cannot be formed, the (meth) acrylic tackifier (B) tends to move to the surface of the adhesive layer (film surface), and there is a problem that the adhesive force to the release film increases with time. In the present specification, "component (A1)" means a monomer (A1) having a functional group, and "component (A2)" means an alkyl (meth) acrylate monomer (A2).
The (meth) acrylic copolymer (a) contains 0.1 to 8.0 parts by mass, preferably 0.2 to 5.0 parts by mass of the monomer (A1) having a functional group in 100 parts by mass of the (meth) acrylic copolymer (a). Here, when the (meth) acrylic copolymer (a) contains more than 8.0 parts by mass of the monomer (A1) having a functional group in 100 parts by mass of the (meth) acrylic copolymer (a), the crosslinking density of the adhesive layer excessively increases, and thus the adhesive force and the bending resistance of the adhesive layer are lowered. On the other hand, when the (meth) acrylic copolymer (a) contains less than 0.1 part by mass of the functional group-containing monomer (A1) per 100 parts by mass of the (meth) acrylic copolymer (a), the crosslinking density of the adhesive layer becomes extremely low, and thus the adhesive layer cannot exhibit an adequate cohesive force, and a residual adhesive phenomenon due to cohesive failure occurs at the time of peeling. Further, since the crosslinked structure with the (meth) acrylic tackifier (B) via the crosslinking agent (C) cannot be sufficiently formed, the (meth) acrylic tackifier (B) tends to move to the surface of the adhesive layer (film surface), and there is a problem that the adhesive force to the release film increases with time. Thus, a large force is required to peel the pressure-sensitive adhesive sheet from the release film, and thus there is a possibility that the work will be hindered.
The (meth) acrylic copolymer (a) contains 50 to 99.9 parts by mass, preferably 70 to 99.0 parts by mass of the alkyl (meth) acrylate monomer (A2) in 100 parts by mass of the (meth) acrylic copolymer (a).
The (meth) acrylic copolymer (a) contains an alkyl (meth) acrylate monomer (A2) as a main monomer component. In the present specification, "(meth) acrylic acid" means "acrylic acid" and "methacrylic acid", and "(meth) acrylic acid ester" means "acrylic acid ester" and "methacrylic acid ester".
(Monomer (A1) having functional group)
The monomer (A1) having a functional group is not limited to a specific kind of monomer having a functional group as long as it is a monomer having a functional group. The monomer (A1) having a functional group is a polar monomer such as a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, or an epoxy group-containing monomer.
The monomer (A1) having a functional group includes: hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, carboxyl-containing monomers such as (meth) acrylic acid and beta-carboxyethyl (meth) acrylate, nitrogen-containing monomers such as (meth) acrylamide and dimethylaminopropyl (meth) acrylamide, and epoxy-containing monomers such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether. The monomer (A1) having a functional group is preferably 4-hydroxybutyl acrylate (Tg: -32 ℃ C.), 2-hydroxyethyl acrylate (Tg: -15 ℃ C.) and acrylic acid (Tg: 106 ℃ C.). The monomer (A1) having a functional group may contain only 1 or 2 or more of the above.
The monomer (A1) having a functional group is preferably a hydroxyl group-containing monomer from the viewpoint of improving the adhesive force and bending resistance and achieving the suppression of the rate of change of the adhesive force to the release film. The functional group-containing monomer described above can be reacted with an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or the like, and thus a crosslinked structure can be introduced into the acrylic copolymer (a). This is considered to be related to the improvement of the cohesive force and the adhesiveness of the adhesive layer.
((Meth) acrylic acid alkyl ester monomer (A2))
The kind of the alkyl (meth) acrylate monomer (A2) is not particularly limited. The alkyl group of the alkyl (meth) acrylate monomer (A2) may be either a straight chain or a branched chain. The carbon number of the alkyl group is preferably 1 to 18. In order to lower the glass transition temperature (Tg) of the (meth) acrylic copolymer (A), the glass transition temperature (Tg) of the homopolymer of the alkyl (meth) acrylate monomer (A2) is preferably-50℃or lower.
The alkyl (meth) acrylate monomer (A2) includes: 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃), and the like. The alkyl (meth) acrylate monomers (A2) are preferably butyl acrylate and 2-ethylhexyl acrylate. The alkyl (meth) acrylate monomer (A2) may contain only 1 of the above, or may contain 2 or more.
(Physical Properties)
The glass transition temperature (Tg) of the (meth) acrylic copolymer (A) is-50 ℃ or lower. The method for calculating the glass transition temperature (Tg) of the (meth) acrylic copolymer (a) will be described later. Here, when the glass transition temperature (Tg) of the (meth) acrylic copolymer (a) exceeds-50 ℃, the stress relaxation property of the adhesive layer decreases, and therefore the bending resistance decreases.
The weight average molecular weight of the (meth) acrylic copolymer (a) is 50 to 250 ten thousand, preferably 70 to 200 ten thousand, more preferably 80 to 180 ten thousand.
(Polymerization method, etc.)
The (meth) acrylic copolymer (a) can be produced by usual solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, and the like. The (meth) acrylic copolymer (a) is particularly preferably produced by solution polymerization using a (meth) acrylic copolymer (a) which can be obtained in the form of a solution. Thus, the (meth) acrylic copolymer (a) in a solution state can be directly used for the production of the adhesive composition for a foldable display of the present invention. The solvent used in the solution polymerization includes, for example, an organic solvent such as ethyl acetate, toluene, n-hexane, acetone, methyl ethyl ketone, and the like.
(Polymerization initiator)
The polymerization initiator used in polymerizing the above-mentioned component (A1) and component (A2) includes: for example, oil-soluble organic peroxides such as 2, 4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, benzoyl peroxide, o-methylbenzoyl peroxide, bis-3, 5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, dicumyl peroxide, t-butylhydroperoxide, and t-butylperoxide, and oil-soluble azo compounds such as 2,2' -azobisisobutyronitrile, 2' -azobis (2, 4-dimethylvaleronitrile), 2' - (2, 4-dimethyl-4-methoxypentanenitrile, and the like. The oil-soluble polymerization initiator is preferably an oil-soluble azo compound. The oil-soluble polymerization initiator may contain only 1 kind of the above-mentioned materials, or may contain 2 or more kinds.
(Chain transfer agent)
In order to adjust the molecular weight of the (meth) acrylic copolymer (a), a chain transfer agent may be suitably used. Chain transfer agents include, for example: the above-mentioned materials may be used singly or in combination of 1 or 2 or more of octyl mercaptoacetate, methoxybutyl mercaptoacetate, octyl mercaptopropionate, methoxybutyl mercaptopropionate, stearyl mercaptan, thiols such as lauryl mercaptan, and α -methylstyrene dimer.
(Other additives)
The (meth) acrylic copolymer (a) may contain additives for the purpose of adjusting the adhesion and other properties, in addition to the above-mentioned component (A1) and component (A2). The additive specifically comprises: adhesion promoters, plasticizers, silane coupling agents, antioxidants, antistatic agents, and the like.
((Meth) acrylic tackifier (B))
The (meth) acrylic tackifier (B) comprises, as structural units, a monomer (B1) having a functional group, an alkyl (meth) acrylate monomer (B2) having a homopolymer glass transition temperature (Tg) of-50 ℃ or lower, and a (cyclo) alkyl (meth) acrylate monomer (B3) having a homopolymer glass transition temperature of 40 ℃ or higher.
Here, when the (meth) acrylic tackifier (B) does not contain the (B1) component as a structural unit and contains the (B2) component and the (B3) component as a structural unit, the (B2) component cannot form a crosslinked structure, and further cannot form a crosslinked structure with the (meth) acrylic copolymer (a) via the crosslinking agent (C), and therefore the (meth) acrylic tackifier (B) tends to move to the surface of the adhesive layer (film surface), and there is a problem that the adhesive force to the release film increases with time.
In addition, when the (meth) acrylic tackifier (B) does not contain the component (B2) as a structural unit or is small in content, the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) exceeds 40 ℃, the stress relaxation property of the (meth) acrylic tackifier (B) is insufficient, and therefore the bending resistance tends to be lowered. On the other hand, when the (meth) acrylic tackifier (B) does not contain the component (B3) as a structural unit or contains a small amount of the component (B3), the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) is lower than-10 ℃, the cohesive force of the (meth) acrylic tackifier (B) is insufficient, and thus the adhesive force tends to be lowered.
In the present specification, "component (B1)" means a monomer (B1) having a functional group, "component (B2)" means an alkyl (meth) acrylate monomer (B2) having a glass transition temperature (Tg) of-50 ℃ or lower, and "component (B3)" means a (cyclo) alkyl (meth) acrylate monomer (B3) having a glass transition temperature of 40 ℃ or higher.
The (meth) acrylic tackifier (B) contains 0.1 to 20 parts by mass, preferably 1 to 17 parts by mass of a monomer (B1) having a functional group in 100 parts by mass of the (meth) acrylic tackifier (B). Here, when the (meth) acrylic tackifier (B) contains more than 20 parts by mass of the component (B1) in 100 parts by mass of the (meth) acrylic tackifier (B), the crosslinking density increases, and the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer is greatly reduced. This results in insufficient effects of improving the cohesive force at the interface between the adhesive layer and the adherend, and reduced adhesive force, which reduces the practical applicability as an adhesive for foldable displays. On the other hand, when the (meth) acrylic tackifier (B) contains less than 0.1 part by mass of the component (B1) per 100 parts by mass of the (meth) acrylic tackifier (B), a crosslinked structure with the (meth) acrylic copolymer (a) via the crosslinking agent (C) cannot be formed, and therefore the (meth) acrylic tackifier (B) tends to excessively migrate to the surface of the pressure-sensitive adhesive layer (film surface), and the problem of an increase in the adhesive force to the release film with time arises.
The (meth) acrylic tackifier (B) contains 10 to 60 parts by mass, preferably 10 to 55 parts by mass, more preferably 10 to 45 parts by mass of an alkyl (meth) acrylate monomer (B2) having a homopolymer glass transition temperature (Tg) of-50 ℃ or lower in 100 parts by mass of the (meth) acrylic tackifier (B). Here, when the (meth) acrylic tackifier (B) contains more than 60 parts by mass of the above (B2) component in 100 parts by mass of the (meth) acrylic tackifier (B), the cohesive force of the (meth) acrylic tackifier (B) is insufficient, and thus the adhesive force tends to be lowered. On the other hand, when the (meth) acrylic tackifier (B) contains less than 10 parts by mass of the component (B2) per 100 parts by mass of the (meth) acrylic tackifier (B), the stress relaxation property of the acrylic tackifier (B) is insufficient, and thus the bending resistance tends to be lowered.
The (meth) acrylic tackifier (B) contains 35 to 85 parts by mass, preferably 40 to 85 parts by mass, more preferably 50 to 85 parts by mass of an alkyl (meth) acrylate monomer (B3) having a glass transition temperature of 40 ℃ or higher when the homopolymer is contained in 100 parts by mass of the (meth) acrylic tackifier (B). Here, when the (meth) acrylic tackifier (B) contains more than 85 parts by mass of the component (B3) in 100 parts by mass of the (meth) acrylic tackifier (B), the stress relaxation property of the acrylic tackifier (B) is insufficient, and thus the bending resistance tends to be lowered. On the other hand, when the (meth) acrylic tackifier (B) contains less than 35 parts by mass of the component (B3) in 100 parts by mass of the (meth) acrylic tackifier (B), the cohesive force of the (meth) acrylic tackifier (B) is insufficient, and thus the adhesive force tends to be lowered.
In the present specification, "(cyclo) alkyl" means "alkyl" and "cycloalkyl", and "(meth) acrylic acid (cyclo) alkyl ester monomer" means "alkyl acrylate monomer", "alkyl methacrylate monomer", "cycloalkyl acrylate monomer", and "cycloalkyl methacrylate monomer".
(Monomer (B1) having functional group)
The monomer (B1) having a functional group is not limited to a specific kind of monomer having a functional group as long as it is a monomer having a functional group. The monomer (B1) having a functional group is a polar monomer such as a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer, or an epoxy group-containing monomer.
The monomer (B1) having a functional group includes: hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, carboxyl-containing monomers such as (meth) acrylic acid and beta-carboxyethyl (meth) acrylate, nitrogen-containing monomers such as (meth) acrylamide and dimethylaminopropyl (meth) acrylamide, and epoxy-containing monomers such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether. The monomers (B1) having functional groups are preferably 4-hydroxybutyl acrylate (Tg: -32 ℃), 2-hydroxyethyl acrylate (Tg: -15 ℃) and acrylic acid (Tg: 106 ℃). The monomer (B1) having a functional group may contain only 1 or 2 or more of the above. In addition, from the viewpoint of compatibility with the (meth) acrylic copolymer (a), the monomer (B1) having a functional group is preferably a monomer having the same functional group as the monomer (A1) having a functional group.
The functional group-containing monomer described above can be reacted with an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or the like, and thus a crosslinked structure can be introduced into the (meth) acrylic tackifier (B). The (meth) acrylic tackifier (B) may form a crosslinked structure with the (meth) acrylic copolymer (a) via an isocyanate crosslinking agent or the like. This suppresses the movement of the (meth) acrylic tackifier (B) to the surface of the pressure-sensitive adhesive layer (film surface), and thus can solve the problem of the increase in the adhesive force to the release film with time.
((Meth) acrylic acid alkyl ester monomer (B2))
The type of the alkyl (meth) acrylate monomer (B2) is not particularly limited as long as the homopolymer has a glass transition temperature (Tg) of-50℃or lower. The alkyl group of the alkyl (meth) acrylate monomer (B2) may be either a straight chain or a branched chain. The carbon number of the alkyl group is preferably 1 to 18. The difference in glass transition temperature (Tg) between the component (B2) and the component (B3) as a structural unit of the (meth) acrylic tackifier (B) is preferably large. Further, from the viewpoint of compatibility with the (meth) acrylic copolymer (a), the alkyl (meth) acrylate monomer (B2) is more preferably the same monomer as the alkyl (meth) acrylate monomer (A2).
The alkyl (meth) acrylate monomer (B2) includes: 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃), and the like. The alkyl (meth) acrylate monomer (B2) is preferably butyl acrylate or 2-ethylhexyl acrylate. The alkyl (meth) acrylate monomer (B2) may contain only 1 of the above, or may contain 2 or more. Further, from the viewpoint of compatibility with the (meth) acrylic copolymer (a), the alkyl (meth) acrylate monomer (B2) more preferably contains 1 or more monomer similar to the alkyl (meth) acrylate monomer (A2).
((Meth) acrylic acid (cyclo) alkyl ester monomer (B3))
The type of the (cyclo) alkyl (meth) acrylate monomer (B3) is not particularly limited as long as the (cyclo) alkyl (meth) acrylate monomer has a glass transition temperature of 40 ℃ or higher. The alkyl group of the (cyclo) alkyl (meth) acrylate monomer (B3) may be any of linear, branched and cyclic. The (cyclo) alkyl (meth) acrylate monomer (B3) contains: monomers having saturated hydrocarbon groups containing cyclic structures. The difference in glass transition temperature (Tg) between the component (B2) and the component (B3) as a structural unit of the (meth) acrylic tackifier (B) is preferably large. Therefore, the glass transition temperature (Tg) of the homopolymer of the (meth) acrylic acid (cyclo) alkyl ester monomer (B3) is preferably a high temperature, preferably 40℃or higher, more preferably 80℃or higher.
The (cyclo) alkyl (meth) acrylate monomer (B3) includes: methyl methacrylate (Tg: 105 ℃ C.), isobutyl methacrylate (Tg: 48 ℃ C.), tert-butyl methacrylate (Tg: 107 ℃ C.), cyclohexyl methacrylate (Tg: 100 ℃ C.), isobornyl methacrylate (Tg: 155 ℃ C.), isobornyl acrylate (Tg: 96 ℃ C.), ethyl methacrylate (Tg: 65 ℃ C.), and the like. The (cyclo) alkyl (meth) acrylate monomer (B3) is preferably methyl methacrylate, t-butyl methacrylate and cyclohexyl methacrylate from the viewpoint of high glass transition temperature (Tg) and excellent compatibility. The (cyclo) alkyl (meth) acrylate monomer (B3) may contain only 1 or 2 or more of the above.
(Physical Properties)
The glass transition temperature (Tg) of the (meth) acrylic tackifier (B) is from-10 ℃ to 40 ℃. The method for calculating the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) will be described later. Here, when the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) exceeds 40 ℃, the stress relaxation property of the adhesive layer decreases, and therefore the bending resistance of the adhesive layer decreases. On the other hand, in the case where the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) is lower than-10 ℃, the cohesive force of the adhesive layer is lowered, and therefore the adhesive force of the adhesive layer is lowered.
The weight average molecular weight of the (meth) acrylic tackifier (B) is 5,000 or more and 15 ten thousand or less. Here, when the weight average molecular weight of the (meth) acrylic tackifier (B) exceeds 15 ten thousand, the mobility of the (meth) acrylic tackifier (B) to the surface of the pressure-sensitive adhesive layer is significantly reduced, and thus the cohesive force improving effect at the interface between the pressure-sensitive adhesive layer and the adherend is not sufficiently exhibited, and the adhesive force is reduced. On the other hand, when the weight average molecular weight of the (meth) acrylic tackifier (B) is less than 5,000, the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer excessively increases, and thus there is a problem that the adhesive force to the release film increases with time.
(Polymerization method, etc.)
The (meth) acrylic tackifier (B) can be produced by usual solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, and the like. It is particularly preferable to produce the (meth) acrylic tackifier (B) by solution polymerization using a (meth) acrylic tackifier (B) obtainable in the form of a solution. Thus, the (meth) acrylic tackifier (B) in a solution state can be directly used for the production of the adhesive composition for a foldable display of the present invention. The solvent used in the solution polymerization includes, for example, an organic solvent such as ethyl acetate, toluene, n-hexane, acetone, methyl ethyl ketone, and the like.
(Polymerization initiator)
The polymerization initiator used in polymerizing the above-mentioned (B1) to (B3) components includes: for example, oil-soluble organic peroxides such as 2, 4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, benzoyl peroxide, o-methylbenzoyl peroxide, bis-3, 5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, dicumyl peroxide, t-butylhydroperoxide, and t-butylperoxide, and oil-soluble azo compounds such as 2,2' -azobisisobutyronitrile, 2' -azobis (2, 4-dimethylvaleronitrile), 2' - (2, 4-dimethyl-4-methoxypentanenitrile, and the like. The oil-soluble polymerization initiator is preferably an oil-soluble azo compound. The oil-soluble polymerization initiator may contain only 1 kind of the above-mentioned materials, or may contain 2 or more kinds.
(Chain transfer agent)
In order to adjust the molecular weight of the (meth) acrylic tackifier (B), a chain transfer agent may be suitably used. The chain transfer agent includes, for example, thiols such as octyl mercaptoacetate, methoxybutyl mercaptoacetate, octyl mercaptopropionate, methoxybutyl mercaptopropionate, stearyl mercaptan, lauryl mercaptan, and the like, α -methylstyrene dimer, and the like, and 1 or 2 or more of them are used singly.
(Other additives)
The (meth) acrylic tackifier (B) may contain additives for the purpose of adjusting the adhesive force and other properties, in addition to the above-mentioned components (B1) to (B3). The additive specifically comprises: adhesion promoters, plasticizers, silane coupling agents, antioxidants, antistatic agents, and the like.
(Crosslinking agent (C))
The adhesive composition for a foldable display contains 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass of a crosslinking agent (C) per 100 parts by mass of the (meth) acrylic copolymer (A). The type of the crosslinking agent (C) is not particularly limited, and includes isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, polyfunctional metal chelates, and the like. The crosslinking agent (C) may contain only 1 of the above, or may contain 2 or more. In addition, an isocyanate-based crosslinking agent is preferable from the viewpoint of improving the adhesive force and the bending resistance of the adhesive composition for a foldable display in a well-balanced manner.
The isocyanate-based crosslinking agent is a polyisocyanate compound having 2 or more isocyanate groups in 1 molecule. The polyisocyanate compounds include, for example: and adducts of pentamethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, toluene diisocyanate, isophorone diisocyanate and the like with trimethylolpropane and the like, isocyanurate compounds, biuret compounds and the like. The polyisocyanate compound is preferably a compound of toluene diisocyanate and xylylene diisocyanate.
(Crosslinking reaction promoter)
In order to shorten the crosslinking reaction time, the adhesive composition for a foldable display may contain 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass of a crosslinking reaction accelerator per 100 parts by mass of the (meth) acrylic copolymer (a) in addition to the crosslinking agent (C). The type of the crosslinking reaction accelerator is not particularly limited, and is, for example, a metal chelate compound such as an aluminum chelate compound, a zirconium chelate compound, or a titanium chelate compound.
< Use >
The adhesive composition for a foldable display of the present invention is used as an adhesive for a foldable display by, for example, curing to form an adhesive layer. "foldable display" refers to a flexible display having an arbitrary radius of curvature designed to be repeatedly folded or unfolded like paper. Foldable displays are used, for example, to fold smart phones and foldable phones. The adhesive layer is included in a foldable display, for example, formed on a substrate film (also referred to as an optical member). Further, as an example of the optical member, an adhesive layer may be present on one or both sides of a polarizing plate, for example. As described above, the adhesive composition for a foldable display of the present invention can form an adhesive layer that improves bending resistance and adhesive force and suppresses the rate of change of adhesive force to a release film, and thus can be suitably used for bonding applications of optical members constituting a foldable display, for example, but is not limited thereto. For example, the adhesive layer of the present invention can be applied to bonding applications of optical members constituting a display that is simply curved without folding the display or a display having a complicated shape.
The thickness of the adhesive layer in the optical member of the present invention is not particularly limited, and is appropriately set, for example, according to the kinds of the optical member and the foldable display, the materials of the optical member and the foldable display, and the like. The thickness of the pressure-sensitive adhesive layer in one embodiment is in the range of 1 μm to 100 μm, preferably in the range of 5 μm to 50 μm.
The optical member includes, for example: members constituting devices such as image display devices and input devices (so-called optical devices), or members used in these devices. The optical member includes: polarizing plates, AG (Anti-Glare) polarizing plates, wavelength plates, retardation plates including 1/2, 1/4, etc., viewing angle compensation films, optical compensation films, brightness enhancement films, light guide plates, reflection films, transparent conductive films such as antireflection films, ITO (Indium-Tin Oxide) films, prism sheets, lens sheets, diffusion plates, etc.
The optical member comprises the following materials: polyester-based resins, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, acrylic-based resins, vinyl chloride-based resins, ABS (Acrylonitrile Butadiene Styrene, acrylonitrile-butadiene-styrene) resins, fluorine-based resins, and the like.
< Production of adhesive composition for foldable display and the like >
Table 1 shows an explanation of abbreviations for the monomers of tables 2 to 3. Table 2 shows the raw material formulation and physical properties of the (meth) acrylic copolymer (a). Table 3 shows the raw material formulation and physical properties of the (meth) acrylic tackifier (B). Table 4 shows the raw material formulations of the adhesive compositions for foldable displays of examples 1 to 19. Table 5 shows the raw material formulations of the adhesive compositions for foldable displays of comparative examples 1 to 13. Table 6 shows the results of performance evaluation for the 2 kinds of adhesive sheets of examples 1 to 19. Table 7 shows the results of performance evaluation for the 2 kinds of adhesive sheets of comparative examples 1 to 13.
TABLE 1
TABLE 2
The numerical values of the component A1 and the component A2 in the respective columns represent parts by mass.
TABLE 3
TABLE 4
The respective parts by weight of the respective components in the table represent parts by weight of the active ingredient.
TABLE 5
The respective parts by weight of the respective components in the table represent parts by weight of the active ingredient.
TABLE 6
TABLE 7
CF (Cohesive failure/cohesive failure)
Production example A-1 production of (meth) acrylic copolymer (A) solution
Based on the raw material formulation of a-1 in table 2, after filling nitrogen gas into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas introduction tube, 2 parts by mass of 4-hydroxybutyl acrylate (4 HBA) as component (A1), 49 parts by mass of Butyl Acrylate (BA) and 49 parts by mass of 2-ethylhexyl acrylate (2 EHA) as component (A2) were added, and 0.05 part by mass of a polymerization initiator (azobisisobutyronitrile), 50 parts by mass of ethyl acetate as a reaction solvent, and 30 parts by mass of acetone were further added. They were stirred and reacted at reflux temperature of ethyl acetate for 5 hours. After the completion of the reaction, the mixture was diluted with ethyl acetate and cooled to room temperature, whereby a (meth) acrylic copolymer (a) solution was obtained.
Production examples A-2 to A-7 production of (meth) acrylic copolymer (A) solution
Based on the raw material formulations of production examples A-2 to A-7 in Table 2, the (meth) acrylic copolymer (A) solutions of production examples A-2 to A-7 were produced in the same manner as production example A-1. The types and amounts of the reaction solvent, the polymerization initiator, and the chain transfer agent were adjusted to prepare the weight average molecular weight (Mw) of the (meth) acrylic copolymer (A) targeted in each of production examples A-2 to A-7.
Production example B-1 production of (meth) acrylic tackifier (B) solution
Based on the raw material formulation of B-1 in Table 3, after filling nitrogen gas into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction pipe and a dropping apparatus, 50 parts by mass of methyl ethyl ketone and 10 parts by mass of ethyl acetate as reaction solvents were first added, and heated and refluxed at a temperature of about 90℃for 10 minutes. Then, 1.0 part by mass of a polymerization initiator (azobisisobutyronitrile) was added, and a solution obtained by mixing 5.0 parts by mass of 4-hydroxybutyl acrylate (4 HBA) as component (B1), 30 parts by mass of Butyl Acrylate (BA) as component (B2), and 65 parts by mass of Methyl Methacrylate (MMA) as component (B3) was further added from a dropping apparatus over 90 minutes. After the completion of the addition, the mixture was further kept in a heated reflux state for 5 hours, to complete the polymerization reaction. After the completion of the reaction, the mixture was diluted with ethyl acetate and cooled to room temperature, whereby a (meth) acrylic tackifier (B-1) solution was obtained.
Production examples B-2 to B-21 production of (meth) acrylic tackifier (B) solution
Based on the raw material formulations of production examples B-2 to B-21 in Table 3 and the same production steps as in production example B-1, the (meth) acrylic tackifier (B) solutions of production examples B-2 to B-21 were produced, respectively. The types and amounts of the reaction solvent, the polymerization initiator, and the chain transfer agent were adjusted in order to prepare the weight average molecular weight (Mw) of the (meth) acrylic tackifier (B) targeted in each of production examples B-2 to B-21.
(Method for measuring weight average molecular weight (Mw))
The weight average molecular weight (Mw) shown in tables 2 to 3 is a molecular weight in terms of polystyrene as measured by GPC (Gel Permeation Chromat ography ). Specifically, the (meth) acrylic copolymer (A) of production examples A-1 to A-7 and the (meth) acrylic thickener (B) of production examples B-1 to B-21 were dissolved in tetrahydrofuran, and the films obtained by drying at room temperature were measured by a high performance liquid chromatograph (Tosoh Co., ltd.: HLC-8320GPC, column: KF-G+KF-806X 2, detector: differential Refractometer (RI), measurement temperature: 40 ℃, eluent: tetrahydrofuran, flow rate: 1mL/min, injection amount: 100. Mu.L), and the weight average molecular weight (Mw) was obtained by conversion of polystyrene.
(Method for measuring glass transition temperature (Tg))
The method for measuring the glass transition temperature (Tg) of the (meth) acrylic copolymer (A) and the (meth) acrylic tackifier (B) will be described. The glass transition temperature (Tg) of the present invention is a theoretical value obtained from the glass transition temperature (Tg) of a homopolymer of each of the monomer components of the (meth) acrylic copolymer (a) and the (meth) acrylic tackifier (B) and the FOX formula (see formula 1 below).
1/Tg=W1/Tg1+W2/Tg2+ … Wn/Tgn (formula 1)
The glass transition temperature (Tg) herein means the glass transition temperature (unit: K) of a copolymer obtained by copolymerizing n monomer components (monomers 1 to n). W1, W2, … Wn represent mass fractions of the respective monomers (1, 2, … n) relative to the total amount of the n monomer components. Tg1, tg2, … Tgn represent the glass transition temperatures (units: K) of homopolymers of the respective monomers (1, 2, … n).
For example, the glass transition temperatures (Tg) of homopolymers of the monomer components of the (meth) acrylic copolymer (a) and the (meth) acrylic tackifier (B) shown in tables 2 to 3 are shown in table 1. The glass transition temperatures (Tg) of the (meth) acrylic copolymers (A) of production examples A-1 to A-7 and the (meth) acrylic tackifiers (B) of production examples B-1 to B-21 were calculated using the values of the glass transition temperatures (Tg) of the homopolymers of the respective monomers shown in Table 1.
The glass transition temperature (Tg) of the homopolymer of each monomer component is a value measured by DSC measurement (DIFFERENTIAL SCANNING Calorimetry ).
Example 1 production of adhesive composition for foldable display
Based on the raw material formulation of example 1 of table 4, 10 parts by mass (solid content conversion value) of the (meth) acrylic tackifier (B) of production example B-1, 0.3 part by mass of the adduct type toluene diisocyanate which is an isocyanate compound as the crosslinking agent (C) (trade name; TAKENATE D E (45 EA)) and 0.2 part by mass of the aluminum triacetylacetone (KAWAKEN FINE CHEMICALS co., ltd. Which is a metal chelate compound as the crosslinking accelerator (aluminum chelate complex a)) were added to 100 parts by mass (solid content conversion value) of the (meth) acrylic copolymer (a) of production example a-1, and the mixture was thoroughly mixed to obtain the adhesive composition for a foldable display of example 1.
(Production of adhesive sheet for evaluation of adhesive force)
The adhesive composition for a foldable display of example 1 was applied to a 38 μm thick polyethylene terephthalate (PET) film (corresponding to the base material of the adhesive sheet) whose surface was treated with silicone so that the thickness of the adhesive layer after drying the adhesive composition for a foldable display with a dryer at 120 ℃ for 120 seconds was 10 μm (dry). After drying (after curing of the adhesive composition for foldable display), a 50 μm thick PET film was bonded to the coated surface of the 38 μm thick PET film, and cured for 4 days in an atmosphere at 60 ℃.
(Production of adhesive sheet for bending test)
Further, a pressure-sensitive adhesive sheet for bending test having a thickness of 50 μm was prepared separately from the pressure-sensitive adhesive layer after drying (after curing the pressure-sensitive adhesive composition for foldable display). The steps other than the step of adjusting the thickness of the dried pressure-sensitive adhesive layer to 50 μm are the same as those in the case of producing the pressure-sensitive adhesive sheet for evaluating the pressure-sensitive adhesive force, and therefore, detailed description thereof is omitted.
The method for producing the adhesive sheet for evaluating adhesive force and the adhesive sheet for testing bending property using the adhesive compositions for foldable displays of examples 2 to 19 and comparative examples 1 to 13 are the same as the method for producing the adhesive sheet of example 1, and therefore, detailed description thereof is omitted.
< Test method >
Performance evaluation was performed by performing the following test examples 1 to 3 using the adhesive sheets for adhesive force evaluation and the adhesive sheets for bending property test of examples 1 to 19 and comparative examples 1 to 13.
Test example 1 measurement of adhesion to glass
For the adhesive sheet for adhesive force evaluation, according to JIS Z0237:2009, 180 ° peel adhesion to glass plates was measured at 23 ℃ under 50% rh. The glass plate is an example of an adherend for evaluating the performance of the adhesive force, and the adherend is not limited to this, and may be a member made of a material different from glass. Specifically, the adhesive sheet for evaluating adhesive force was cut to a width of 25mm, and after peeling off the release film, the sheet was adhered to a glass plate, and the pressure-bonding roller was reciprocated 1 time with a load of 2kg to perform pressure-bonding, thereby producing a test piece. The test piece after being left at 23℃for 24 hours after the press-bonding was peeled off from the glass plate at a peeling speed of 300 mm/min, whereby the adhesion to the glass plate was measured. The adhesive force of the adhesive sheet for adhesive force evaluation to glass was evaluated based on the following evaluation criteria. For example, when the measured adhesive force is 6.0N/25mm or more, it is shown that no practical problem occurs in the adhesion of the foldable display to the optical member. On the other hand, in the case where the measured adhesive force is less than 6.0N/25mm, it means that a practical problem occurs in the adhesion of the foldable display to the optical member.
(Evaluation criteria)
O: the adhesive force was measured to be 6.0N/25mm or more. In this case, practical problems do not occur.
Delta: the adhesive force was found to be 6.0N/25mm or more, but the cohesive failure was confirmed at the time of peeling. In this case, practical problems occur.
X: the adhesion force measured was less than 6.0N/25mm. In this case, practical problems occur.
Test example 2 measurement of the change Rate of adhesive force to Release film
For the adhesive sheet for adhesive force evaluation, according to JIS Z0237:2009, 180 ° peel adhesion to release film was measured at 23 ℃ under 50% rh. Specifically, the adhesive sheet for evaluating adhesive force was cut to a width of 25mm, and the cut sheet was adhered to a glass plate having the back surface of a release film as a support, to prepare a test piece. Then, the adhesive sheet for evaluating adhesive force was peeled off at a peeling speed of 300 mm/min, and the adhesive force to the release film was measured. Further, in order to confirm the change with time of the adhesive force to the release film, the adhesive sheet for adhesive force evaluation cut into a width of 25mm was left at 50℃for 14 days as a promotion condition, and the measurement was also carried out in the same manner. The adhesive force of the adhesive sheet for evaluating adhesive force to a release film before being left at 50℃for 14 days was defined as "initial" adhesive force (initial (gf/25 mm) in tables 6 and 7). The adhesive force of the adhesive sheet for evaluation of adhesive force after standing at 50℃for 14 days to a release film was defined as "adhesive force after time change" (shown as time-dependent (gf/25 mm) in tables 6 and 7). The change rate of the adhesive force was determined by the following equation 2.
Rate of change in adhesion (%) = adhesion after time change (gf/25 mm)/initial adhesion (gf/25 mm) ×100 (formula 2)
The rate of change of the adhesive force of the adhesive sheet for adhesive force evaluation to the release film was evaluated based on the following evaluation criteria. For example, when the change rate is 150% or less, the change rate is small, and the increase in the adhesive strength to the release film is suppressed, so that there is no fear of deterioration in workability. On the other hand, if the rate of change is more than 150%, the adhesion to the release film increases with time, and therefore a large force is required to peel the adhesive sheet from the release film, and there is a concern that the workability may be deteriorated.
(Evaluation criterion)
O: the change rate is 150% or less. In this case, there is no possibility that workability is deteriorated.
X: the change rate is more than 150%. In this case, the workability may be deteriorated.
Test example 3 bending test
After the release film was peeled off from the pressure-sensitive adhesive sheet for bending test, the film was bonded to a Polyimide (PI) film (DU PONT-TORAY co., ltd., trade name; kapton 200H) having a thickness of 50 μm, and pressure-bonded by a hand press roll. The sample was cut into dimensions of 25mm×100mm to obtain test pieces. The test piece was mounted on a Folding tester (YUAS ASYSTEM co., ltd., trade name; project-Free (registered trademark) Folding CLAMSH ELL-type) with the polyimide film on the inside and the PET film on the outside, and a Folding test was performed under the following conditions.
(Test conditions)
Measuring temperature: 23 ℃, 50% RH
Radius of curvature: 2mm of
Bending angle: 180 degree
Bending speed: 2 seconds/time
Number of bending: 30 ten thousand times
After the test, the bending portion of the test piece was observed to evaluate the bending resistance visually.
(Evaluation criterion)
And (3) the following materials: no floating and peeling were observed in the test piece. In this case, there is no problem in practical use, and therefore, the adhesive sheet can be suitably used as a foldable adhesive sheet.
O: peeling was confirmed in a very small portion of the test piece. In this case, there is no problem in practical use, and therefore, the adhesive sheet can be suitably used as a foldable adhesive sheet.
X: the test piece was clearly observed to be lifted and peeled off. In this case, the adhesive sheet is not suitable as a foldable adhesive sheet, and therefore cannot be used.
< Test results >
The test results of examples 1 to 19 and comparative examples 1 to 13 will be described with reference to tables 6 and 7. First, examples 1 to 19 were excellent in all evaluation items of the adhesive force (to glass), the change rate inhibition of the adhesive force (to release film), and the bending resistance. In contrast, comparative examples 1 to 13 satisfied only the performance for some of the entire evaluation items. Hereinafter, the comparison of example 1 with comparative examples 1 to 13 and the characteristics of examples 1 to 19 will be described.
(Comparison of example 1 with comparative example 1)
The adhesive force (to glass) of example 1 was improved as compared with comparative example 1 (case of not containing (meth) acrylic tackifier (B)). On the other hand, the adhesive layer of comparative example 1 was insufficient in cohesive force, and thus the adhesive force (to glass) of comparative example 1 was lowered.
(Comparison of example 1 with comparative example 2)
The bending resistance of example 1 was improved as compared with comparative example 2 (when the blending amount of the (meth) acrylic tackifier (B) exceeded the predetermined amount of the present invention). On the other hand, the cohesive force of the adhesive layer of comparative example 2 excessively increases, and the stress relaxation property decreases, so that the bending resistance of comparative example 2 decreases.
(Comparison of example 1 with comparative example 3)
The adhesive force (to glass) of example 1 was improved as compared with that of comparative example 3 (case where the weight average molecular weight (Mw) of the (meth) acrylic tackifier (B) was larger than the weight average molecular weight (Mw) defined in the present invention). On the other hand, the (meth) acrylic tackifier (B) of the adhesive layer of comparative example 3 significantly reduced the mobility to the surface of the adhesive layer, and thus the adhesive force (to glass) of comparative example 3 was reduced.
(Comparison of example 1 with comparative example 4)
The rate of change of the adhesive force (to a release film) in example 1 was smaller than that in comparative example 4 ((case where the weight average molecular weight (Mw) of the acrylic tackifier (B) was smaller than the weight average molecular weight (Mw) specified in the present invention), and the change of the adhesive force (to a release film) with time was suppressed. On the other hand, the (meth) acrylic tackifier (B) of the adhesive layer of comparative example 4 excessively increases in mobility to the surface of the adhesive layer, and therefore the change rate of the adhesive force (to a release film) of comparative example 4 is larger than the change rate specified in the present invention.
(Comparison of example 1 with comparative example 5)
The bending resistance of example 1 was improved as compared with that of comparative example 5 (in the case where the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) was higher than the glass transition temperature (Tg) defined in the present invention). On the other hand, the stress relaxation property of the adhesive layer of comparative example 5 was lowered, and thus the bending resistance of comparative example 5 was lowered.
(Comparison of example 1 with comparative example 6)
The adhesive force (to glass) of example 1 was improved as compared with comparative example 6 (case where the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) was lower than the glass transition temperature (Tg) defined in the present invention). On the other hand, the cohesive force of the adhesive layer of comparative example 6 was lowered, and thus the adhesive force (to glass) of comparative example 6 was lowered.
(Comparison of example 1 with comparative example 7)
The adhesive force (to glass) and bending resistance of example 1 were improved as compared with comparative example 7 (case where (B2) and (B3) components were not contained in the (meth) acrylic tackifier (B)). On the other hand, the adhesive layer of comparative example 7 had reduced stress relaxation and cohesion, and thus the adhesive force (to glass) and bending resistance of comparative example 7 were reduced.
(Comparison of example 1 with comparative example 8)
The rate of change of the adhesive force (to the release film) in example 1 was smaller than that in comparative example 8 ((meth) acrylic tackifier (B) contains no (B1) component), and the change of the adhesive force (to the release film) with time was suppressed. On the other hand, the (meth) acrylic tackifier (B) of the adhesive layer of comparative example 8 excessively increases in mobility to the surface of the adhesive layer, and therefore the change rate of the adhesive force (to a release film) of comparative example 8 is larger than the change rate specified in the present invention.
(Comparison of example 1 with comparative example 9)
The adhesive force (to glass) of example 1 was improved as compared with comparative example 9 (in the case where (B1) component exceeding the upper limit value defined in the present invention was contained in the (meth) acrylic tackifier (B)). On the other hand, the (meth) acrylic tackifier (B) of the adhesive layer of comparative example 9 significantly reduced the mobility to the surface of the adhesive layer, and thus the adhesive force (to glass) of comparative example 9 was reduced.
(Comparison of example 1 with comparative example 10)
The bending resistance of example 1 was improved as compared with comparative example 10 (in the case where the glass transition temperature (Tg) of the (meth) acrylic copolymer (a) exceeded the glass transition temperature (Tg) specified in the present invention). On the other hand, the stress relaxation property of the adhesive layer of comparative example 10 was lowered, and thus the bending resistance of comparative example 10 was lowered.
(Comparison of example 1 with comparative example 11)
The rate of change of the adhesive force (to the release film) in example 1 was smaller than that in comparative example 11 ((meth) acrylic copolymer (a) containing no component (A1)), and the change of the adhesive force (to the release film) with time was suppressed. On the other hand, the (meth) acrylic copolymer (a) of the adhesive layer of comparative example 11 failed to form a crosslinked structure with the (meth) acrylic tackifier (B) via the crosslinking agent (C), and therefore the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer (film surface) excessively increased, and the rate of change of the adhesive force (to the release film) of comparative example 11 was greater than the rate of change specified in the present invention. Further, since the cohesive force was lowered, the cohesive failure was confirmed at the time of peeling.
(Comparison of example 1 with comparative example 12)
The adhesive force (to glass) and bending resistance of example 1 were improved as compared with comparative example 12 (in the case where (A1) component was contained in an amount more than the prescribed amount of the present invention). On the other hand, the adhesive layer of comparative example 12 had an excessively increased crosslinking density, and thus the adhesive force (to glass) and bending resistance of comparative example 12 were reduced.
(Comparison of example 1 with comparative example 13)
The bending resistance of example 1 was improved as compared with comparative example 13 ((case where the (meth) acrylic copolymer (a) contained a carboxyl group-containing monomer as the (A1) component, and the (meth) acrylic tackifier (B) contained no (B2) component, and TBMA was contained as the (B3) component). On the other hand, the stress relaxation property of the adhesive layer of comparative example 13 was lowered, and thus the bending resistance of comparative example 13 was lowered.
(Characteristics of examples 1 to 5 and 12)
Examples 1 to 5 and 12 were excellent in balance among all evaluation items of the adhesive force (to glass), the rate of change of the adhesive force (to release film), and the bending resistance.
(Characteristics of examples 6 and 7)
The (meth) acrylic tackifier (B) contains the component (B3) at the upper limit of the compounding amount specified in the present invention, and thus the stress relaxation property is reduced. Therefore, the bending resistance is slightly lowered.
(Characteristics of example 8)
Since the (meth) acrylic tackifier (B) contains the component (B1) at the lower limit value of the compounding amount specified in the present invention, the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer increases, and the rate of change of the adhesive force (to the release film) slightly increases.
(Characteristics of example 9)
Since the (meth) acrylic tackifier (B) contains the component (B1) at the upper limit value of the compounding amount specified in the present invention, the crosslinking density of the (meth) acrylic tackifier (B) increases and the mobility to the surface of the adhesive layer decreases. Thus, the adhesion (to glass) of example 9 was lower than that of example 1.
(Characteristics of example 10)
Since the weight average molecular weight (Mw) of the (meth) acrylic tackifier (B) is a lower limit value defined in the present invention, the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer increases, and the rate of change of the adhesive force (to the release film) slightly increases.
(Characteristics of example 11)
Since the weight average molecular weight (Mw) of the (meth) acrylic tackifier (B) is the upper limit value defined in the present invention, the mobility of the (meth) acrylic tackifier (B) to the surface of the adhesive layer is reduced, and the adhesive force (to glass) is lower than in example 1.
(Characteristics of example 13)
Since the glass transition temperature (Tg) of the (meth) acrylic tackifier (B) is a lower limit value defined in the present invention, the cohesive force of the adhesive layer is reduced. Thus, the adhesion (to glass) of example 13 was lower than that of example 1.
(Characteristics of example 14)
Since the blending amount of the (meth) acrylic tackifier (B) with respect to the (meth) acrylic copolymer (a) is a lower limit value defined in the present invention, the adhesive force (to glass) of example 14 is lower than that of example 1.
(Characteristics of example 15)
Since the blending amount of the (meth) acrylic tackifier (B) with respect to the (meth) acrylic copolymer (a) is the upper limit value defined in the present invention, the adhesive force (to glass) of example 15 is improved. On the other hand, the cohesive force of the adhesive layer increases, and thus the bending resistance slightly decreases.
(Characterization of example 16)
Since the glass transition temperature (Tg) of the (meth) acrylic copolymer (a) is the upper limit value defined in the present invention, the adhesive force (to glass) is improved and the bending resistance is slightly lowered.
(Characterization of example 17)
Even in the case where the weight average molecular weight (Mw) of the (meth) acrylic copolymer (a) is smaller than that of the (meth) acrylic copolymers (a) of examples 1 to 5, there is no performance difference between examples 17 and examples 1 to 5.
(Characterization of example 18)
Even in the case where the (meth) acrylic copolymer (a) contains the carboxyl group-containing monomer (AAC) as the (A1) component, there is no performance difference between examples 18 and examples 1 to 5.
(Characterization of example 19)
Even in the case where the (meth) acrylic copolymer (a) contains the carboxyl group-containing monomer (AAC) as the (A1) component and the (meth) acrylic tackifier (B) further contains the carboxyl group-containing monomer (AAC) as the (B1) component, there is no performance difference between examples 19 and examples 1 to 5.
As described above, the adhesive layer formed from the adhesive composition for a foldable display of the present invention has a remarkable effect of suppressing the change with time of the adhesive force to the release film while satisfying both the properties of bending resistance and high adhesive force.
The present invention is not limited to the above embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.
Claims (10)
1. An adhesive composition for a foldable display, comprising:
a (meth) acrylic copolymer (a) containing a monomer (A1) having a functional group and an alkyl (meth) acrylate monomer (A2) as structural units;
A (meth) acrylic tackifier (B) comprising, as structural units, a monomer (B1) having a functional group, an alkyl (meth) acrylate monomer (B2) having a homopolymer glass transition temperature Tg of-50 ℃ or lower, and a (cyclo) alkyl (meth) acrylate monomer (B3) having a homopolymer glass transition temperature Tg of 40 ℃ or higher; and
A crosslinking agent (C),
The glass transition temperature Tg of the (meth) acrylic copolymer (A) is-50 ℃ or lower,
The glass transition temperature Tg of the (meth) acrylic tackifier (B) is from-10 ℃ to 40 ℃,
Here, the glass transition temperature Tg of the (meth) acrylic copolymer (A) and the glass transition temperature Tg of the (meth) acrylic tackifier (B) are determined based on the FOX formula,
The adhesive force of the adhesive layer formed by the adhesive composition for the foldable display is more than 6.0N/25mm,
Here, the adhesive force is according to JIS Z0237:2009, a measured value is specified.
2. The adhesive composition for a foldable display according to claim 1,
The (meth) acrylic tackifier (B) is contained in an amount of 0.5 to 20 parts by mass per 100 parts by mass of the (meth) acrylic copolymer (A).
3. The adhesive composition for a foldable display according to claim 1, wherein,
The weight average molecular weight of the (meth) acrylic copolymer (A) is 50 to 250 ten thousand,
The weight average molecular weight of the (meth) acrylic tackifier (B) is 5,000 or more and 15 ten thousand or less.
4. The adhesive composition for a foldable display according to claim 1, wherein,
The (meth) acrylic tackifier (B) comprises, in 100 parts by mass of the (meth) acrylic tackifier (B), 0.1 to 20 parts by mass of the monomer (B1) having a functional group, 10 to 60 parts by mass of the alkyl (meth) acrylate monomer (B2), and 35 to 85 parts by mass of the (meth) acrylic (cyclo) alkyl ester monomer (B3),
The monomer (B1) having a functional group contains at least any one of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer and an epoxy group-containing monomer,
The alkyl (meth) acrylate monomer (B2) contains at least any one of 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃),
The (meth) acrylic acid (cyclo) alkyl ester monomer (B3) contains at least one of methyl methacrylate (Tg: 105 ℃ C.), isobutyl methacrylate (Tg: 48 ℃ C.), tert-butyl methacrylate (Tg: 107 ℃ C.), cyclohexyl methacrylate (Tg: 100 ℃ C.), isobornyl methacrylate (Tg: 155 ℃ C.), isobornyl acrylate (Tg: 96 ℃ C.), and ethyl methacrylate (Tg: 65 ℃ C.).
5. The adhesive composition for a foldable display according to claim 1, wherein,
The monomer (B1) having a functional group contains at least one of hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, carboxyl-containing monomers such as (meth) acrylic acid, beta-carboxyethyl (meth) acrylate, nitrogen-containing monomers such as (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, epoxy-containing monomers such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether,
The alkyl (meth) acrylate monomer (B2) contains at least any one of 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃),
The (meth) acrylic acid (cyclo) alkyl ester monomer (B3) contains at least one of methyl methacrylate (Tg: 105 ℃ C.), isobutyl methacrylate (Tg: 48 ℃ C.), tert-butyl methacrylate (Tg: 107 ℃ C.), cyclohexyl methacrylate (Tg: 100 ℃ C.), isobornyl methacrylate (Tg: 155 ℃ C.), isobornyl acrylate (Tg: 96 ℃ C.), and ethyl methacrylate (Tg: 65 ℃ C.).
6. The adhesive composition for a foldable display according to claim 1, wherein,
The (meth) acrylic copolymer (A) contains 0.1 to 8.0 parts by mass of the monomer (A1) having a functional group and 50 to 99.9 parts by mass of the alkyl (meth) acrylate monomer (A2) in 100 parts by mass of the (meth) acrylic copolymer (A),
The monomer (A1) having a functional group contains at least any one of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a nitrogen-containing monomer and an epoxy group-containing monomer,
The alkyl (meth) acrylate monomer (A2) contains at least any one of 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃).
7. The adhesive composition for a foldable display according to claim 1, wherein,
The monomer (A1) having a functional group contains at least one of hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, carboxyl-containing monomers such as (meth) acrylic acid, beta-carboxyethyl (meth) acrylate, nitrogen-containing monomers such as (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, glycidyl (meth) acrylate, and epoxy-containing monomers such as 4-hydroxybutyl (meth) acrylate glycidyl ether,
The alkyl (meth) acrylate monomer (A2) contains at least any one of 2-ethylhexyl acrylate (Tg: -70 ℃), n-hexyl acrylate (Tg: -65 ℃), n-octyl acrylate (Tg: -65 ℃), isononyl acrylate (Tg: -60 ℃), n-nonyl acrylate (Tg: -58 ℃), isooctyl acrylate (Tg: -58 ℃), butyl acrylate (Tg: -52 ℃), n-dodecyl methacrylate (Tg: -65 ℃).
8. The adhesive composition for a foldable display according to claim 1,
The adhesive composition for foldable displays contains 0.01 to 10 parts by mass of a crosslinking agent (C) per 100 parts by mass of the (meth) acrylic copolymer (A).
9. An adhesive sheet comprising:
Substrate and method for producing the same
An adhesive layer formed of the adhesive composition for a foldable display according to any one of claims 1 to 8 on the substrate.
10. The adhesive sheet according to claim 9, wherein,
When the adherend is a release film, the adhesive force of the adhesive sheet to the release film has a change rate of 150% or less,
Here, the rate of change of the adhesive force of the adhesive sheet to the release film is a value obtained by the following formula:
The change rate of adhesion (%) = adhesion after time change (gf/25 mm)/initial adhesion (gf/25 mm) ×100.
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| JP2022-173614 | 2022-10-28 | ||
| JP2022173614 | 2022-10-28 | ||
| JP2023038938A JP7329210B1 (en) | 2022-10-28 | 2023-03-13 | Adhesive composition and adhesive sheet for foldable display |
| JP2023-038938 | 2023-03-13 |
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| TWI696673B (en) * | 2017-12-11 | 2020-06-21 | 南韓商Ｌｇ化學股份有限公司 | Adhesive composition for foldable display and adhesive layer and foldable display comprising the same |
| JP6757479B2 (en) | 2019-01-30 | 2020-09-16 | 日東電工株式会社 | Adhesive sheets, optical films with adhesive layers, laminates, and image displays |
| JP7338829B2 (en) * | 2019-12-09 | 2023-09-05 | 日本カーバイド工業株式会社 | PSA COMPOSITION FOR FOLDABLE DISPLAY AND OPTICAL MEMBER FOR FOLDABLE DISPLAY |
| JP7434696B2 (en) * | 2019-12-09 | 2024-02-21 | 日本カーバイド工業株式会社 | Adhesive composition for foldable displays and optical members for foldable displays |
| JP7369073B2 (en) | 2020-03-23 | 2023-10-25 | 日本カーバイド工業株式会社 | Adhesive composition for optical member protective film and optical member protective film |
| JP2022124274A (en) * | 2021-02-15 | 2022-08-25 | 日本カーバイド工業株式会社 | Adhesive composition, adhesive sheet, and optical member |
| JP7108165B1 (en) | 2021-05-27 | 2022-07-28 | 東洋インキＳｃホールディングス株式会社 | Adhesives, Adhesive Sheets, Laminates, and Flexible Displays |
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