CN118006261B - Acrylic pressure-sensitive adhesive for foldable display screen and adhesive sheet thereof - Google Patents
Acrylic pressure-sensitive adhesive for foldable display screen and adhesive sheet thereof Download PDFInfo
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- CN118006261B CN118006261B CN202410421285.XA CN202410421285A CN118006261B CN 118006261 B CN118006261 B CN 118006261B CN 202410421285 A CN202410421285 A CN 202410421285A CN 118006261 B CN118006261 B CN 118006261B
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- 239000000853 adhesive Substances 0.000 title claims abstract description 66
- 230000001070 adhesive effect Effects 0.000 title claims abstract description 66
- 239000004820 Pressure-sensitive adhesive Substances 0.000 title claims abstract description 28
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 title claims abstract description 21
- 229920006243 acrylic copolymer Polymers 0.000 claims abstract description 18
- 239000000178 monomer Substances 0.000 claims description 166
- 229920001577 copolymer Polymers 0.000 claims description 98
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 21
- 239000003999 initiator Substances 0.000 claims description 21
- 239000012986 chain transfer agent Substances 0.000 claims description 20
- 238000004132 cross linking Methods 0.000 claims description 19
- 125000004122 cyclic group Chemical group 0.000 claims description 15
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 15
- 239000012790 adhesive layer Substances 0.000 claims description 11
- 239000003431 cross linking reagent Substances 0.000 claims description 9
- GOXQRTZXKQZDDN-UHFFFAOYSA-N 2-Ethylhexyl acrylate Chemical compound CCCCC(CC)COC(=O)C=C GOXQRTZXKQZDDN-UHFFFAOYSA-N 0.000 claims description 6
- FIHBHSQYSYVZQE-UHFFFAOYSA-N 6-prop-2-enoyloxyhexyl prop-2-enoate Chemical compound C=CC(=O)OCCCCCCOC(=O)C=C FIHBHSQYSYVZQE-UHFFFAOYSA-N 0.000 claims description 5
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 5
- 230000009477 glass transition Effects 0.000 claims description 5
- JWYVGKFDLWWQJX-UHFFFAOYSA-N 1-ethenylazepan-2-one Chemical compound C=CN1CCCCCC1=O JWYVGKFDLWWQJX-UHFFFAOYSA-N 0.000 claims description 4
- QZPSOSOOLFHYRR-UHFFFAOYSA-N 3-hydroxypropyl prop-2-enoate Chemical compound OCCCOC(=O)C=C QZPSOSOOLFHYRR-UHFFFAOYSA-N 0.000 claims description 4
- NDWUBGAGUCISDV-UHFFFAOYSA-N 4-hydroxybutyl prop-2-enoate Chemical compound OCCCCOC(=O)C=C NDWUBGAGUCISDV-UHFFFAOYSA-N 0.000 claims description 4
- LVGFPWDANALGOY-UHFFFAOYSA-N 8-methylnonyl prop-2-enoate Chemical compound CC(C)CCCCCCCOC(=O)C=C LVGFPWDANALGOY-UHFFFAOYSA-N 0.000 claims description 4
- DAKWPKUUDNSNPN-UHFFFAOYSA-N Trimethylolpropane triacrylate Chemical compound C=CC(=O)OCC(CC)(COC(=O)C=C)COC(=O)C=C DAKWPKUUDNSNPN-UHFFFAOYSA-N 0.000 claims description 4
- GMSCBRSQMRDRCD-UHFFFAOYSA-N dodecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCOC(=O)C(C)=C GMSCBRSQMRDRCD-UHFFFAOYSA-N 0.000 claims description 4
- RBQRWNWVPQDTJJ-UHFFFAOYSA-N methacryloyloxyethyl isocyanate Chemical compound CC(=C)C(=O)OCCN=C=O RBQRWNWVPQDTJJ-UHFFFAOYSA-N 0.000 claims description 4
- FSAJWMJJORKPKS-UHFFFAOYSA-N octadecyl prop-2-enoate Chemical compound CCCCCCCCCCCCCCCCCCOC(=O)C=C FSAJWMJJORKPKS-UHFFFAOYSA-N 0.000 claims description 4
- LJWQJECMFUGUDV-UHFFFAOYSA-N (4-benzoyl-3-hydroxyphenyl) prop-2-enoate Chemical compound OC1=CC(OC(=O)C=C)=CC=C1C(=O)C1=CC=CC=C1 LJWQJECMFUGUDV-UHFFFAOYSA-N 0.000 claims description 3
- OMIGHNLMNHATMP-UHFFFAOYSA-N 2-hydroxyethyl prop-2-enoate Chemical compound OCCOC(=O)C=C OMIGHNLMNHATMP-UHFFFAOYSA-N 0.000 claims description 3
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 claims description 3
- VPASWAQPISSKJP-UHFFFAOYSA-N ethyl prop-2-enoate;isocyanic acid Chemical compound N=C=O.CCOC(=O)C=C VPASWAQPISSKJP-UHFFFAOYSA-N 0.000 claims description 3
- DTGKSKDOIYIVQL-WEDXCCLWSA-N (+)-borneol Chemical group C1C[C@@]2(C)[C@@H](O)C[C@@H]1C2(C)C DTGKSKDOIYIVQL-WEDXCCLWSA-N 0.000 claims description 2
- ZOKCNEIWFQCSCM-UHFFFAOYSA-N (2-methyl-4-phenylpent-4-en-2-yl)benzene Chemical compound C=1C=CC=CC=1C(C)(C)CC(=C)C1=CC=CC=C1 ZOKCNEIWFQCSCM-UHFFFAOYSA-N 0.000 claims description 2
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 claims description 2
- VTLHIRNKQSFSJS-UHFFFAOYSA-N [3-(3-sulfanylbutanoyloxy)-2,2-bis(3-sulfanylbutanoyloxymethyl)propyl] 3-sulfanylbutanoate Chemical compound CC(S)CC(=O)OCC(COC(=O)CC(C)S)(COC(=O)CC(C)S)COC(=O)CC(C)S VTLHIRNKQSFSJS-UHFFFAOYSA-N 0.000 claims description 2
- LTYBJDPMCPTGEE-UHFFFAOYSA-N (4-benzoylphenyl) prop-2-enoate Chemical compound C1=CC(OC(=O)C=C)=CC=C1C(=O)C1=CC=CC=C1 LTYBJDPMCPTGEE-UHFFFAOYSA-N 0.000 claims 1
- XQACRXVFENATBU-UHFFFAOYSA-N dodecan-2-yl prop-2-enoate Chemical compound CCCCCCCCCCC(C)OC(=O)C=C XQACRXVFENATBU-UHFFFAOYSA-N 0.000 claims 1
- 238000002360 preparation method Methods 0.000 description 24
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 19
- 239000002904 solvent Substances 0.000 description 16
- 238000012360 testing method Methods 0.000 description 13
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- 239000010410 layer Substances 0.000 description 10
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- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 229910052757 nitrogen Inorganic materials 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
- 239000003054 catalyst Substances 0.000 description 8
- 239000002313 adhesive film Substances 0.000 description 7
- 238000002156 mixing Methods 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- FJKROLUGYXJWQN-UHFFFAOYSA-N 4-hydroxybenzoic acid Chemical compound OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 5
- 239000004642 Polyimide Substances 0.000 description 5
- 238000004821 distillation Methods 0.000 description 5
- 229920001721 polyimide Polymers 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000010992 reflux Methods 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 4
- 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 description 4
- 230000007423 decrease Effects 0.000 description 4
- 229940119545 isobornyl methacrylate Drugs 0.000 description 4
- 239000000126 substance Substances 0.000 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 description 3
- AZUYLZMQTIKGSC-UHFFFAOYSA-N 1-[6-[4-(5-chloro-6-methyl-1H-indazol-4-yl)-5-methyl-3-(1-methylindazol-5-yl)pyrazol-1-yl]-2-azaspiro[3.3]heptan-2-yl]prop-2-en-1-one Chemical compound ClC=1C(=C2C=NNC2=CC=1C)C=1C(=NN(C=1C)C1CC2(CN(C2)C(C=C)=O)C1)C=1C=C2C=NN(C2=CC=1)C AZUYLZMQTIKGSC-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 235000019400 benzoyl peroxide Nutrition 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011229 interlayer Substances 0.000 description 3
- ZDHCZVWCTKTBRY-UHFFFAOYSA-N omega-Hydroxydodecanoic acid Natural products OCCCCCCCCCCCC(O)=O ZDHCZVWCTKTBRY-UHFFFAOYSA-N 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- ABNRTWIZOVJPNY-UHFFFAOYSA-N 1-(4-benzoyl-3-hydroxyphenyl)prop-2-en-1-one Chemical compound OC1=CC(C(=O)C=C)=CC=C1C(=O)C1=CC=CC=C1 ABNRTWIZOVJPNY-UHFFFAOYSA-N 0.000 description 2
- -1 acrylic ester Chemical class 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
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- 150000002978 peroxides Chemical class 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- AVTLBBWTUPQRAY-UHFFFAOYSA-N 2-(2-cyanobutan-2-yldiazenyl)-2-methylbutanenitrile Chemical compound CCC(C)(C#N)N=NC(C)(CC)C#N AVTLBBWTUPQRAY-UHFFFAOYSA-N 0.000 description 1
- MTLWTRLYHAQCAM-UHFFFAOYSA-N 2-[(1-cyano-2-methylpropyl)diazenyl]-3-methylbutanenitrile Chemical compound CC(C)C(C#N)N=NC(C#N)C(C)C MTLWTRLYHAQCAM-UHFFFAOYSA-N 0.000 description 1
- FRIBMENBGGCKPD-UHFFFAOYSA-N 3-(2,3-dimethoxyphenyl)prop-2-enal Chemical compound COC1=CC=CC(C=CC=O)=C1OC FRIBMENBGGCKPD-UHFFFAOYSA-N 0.000 description 1
- CWPKTBMRVATCBL-UHFFFAOYSA-N 3-[1-[1-[(2-methylphenyl)methyl]piperidin-4-yl]piperidin-4-yl]-1h-benzimidazol-2-one Chemical compound CC1=CC=CC=C1CN1CCC(N2CCC(CC2)N2C(NC3=CC=CC=C32)=O)CC1 CWPKTBMRVATCBL-UHFFFAOYSA-N 0.000 description 1
- 102100040409 Ameloblastin Human genes 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 1
- 101000891247 Homo sapiens Ameloblastin Proteins 0.000 description 1
- YIVJZNGAASQVEM-UHFFFAOYSA-N Lauroyl peroxide Chemical compound CCCCCCCCCCCC(=O)OOC(=O)CCCCCCCCCCC YIVJZNGAASQVEM-UHFFFAOYSA-N 0.000 description 1
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 125000005250 alkyl acrylate group Chemical group 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000012975 dibutyltin dilaurate Substances 0.000 description 1
- 125000003438 dodecyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- ZQMHJBXHRFJKOT-UHFFFAOYSA-N methyl 2-[(1-methoxy-2-methyl-1-oxopropan-2-yl)diazenyl]-2-methylpropanoate Chemical compound COC(=O)C(C)(C)N=NC(C)(C)C(=O)OC ZQMHJBXHRFJKOT-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007719 peel strength test Methods 0.000 description 1
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- GJBRNHKUVLOCEB-UHFFFAOYSA-N tert-butyl benzenecarboperoxoate Chemical compound CC(C)(C)OOC(=O)C1=CC=CC=C1 GJBRNHKUVLOCEB-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to the technical field of adhesives, and provides an acrylic pressure-sensitive adhesive for a foldable display screen and an adhesive sheet thereof. The acrylic pressure-sensitive adhesive comprises an acrylic copolymer A and an acrylic copolymer B having a weight average molecular weight of 20,000-35,000, wherein the content of the acrylic copolymer B is 5-10 parts by mass relative to 100 parts by mass of the acrylic copolymer A. According to the invention, a certain amount of oligomer components with defined molecular weight are added into the adhesive, so that the adhesive has good peeling strength and low high-low temperature modulus, and the folding life of the foldable display screen can be effectively ensured.
Description
Technical Field
The invention relates to the technical field of adhesives, in particular to an acrylic pressure-sensitive adhesive for a foldable display screen and an adhesive sheet thereof.
Background
OCA optical adhesive (Optically CLEAR ADHESIVE) is a special adhesive for cementing transparent optical elements, belongs to pressure-sensitive adhesives, is widely used for bonding between touch screen components, and has the characteristics of high light transmittance, high cohesiveness, aging resistance, high bonding yield and the like. Along with the rapid development of the folding mobile phone market, the folding mobile phone tends to be light and thin, and the OCA optical adhesive is used as an important adhesive material of a display screen of the folding mobile phone, so that the performance upgrading of the OCA optical adhesive is also urgently required. Because of the requirements of light weight, thinness and foldability of the folding mobile phone display screen, the adhesive layer has high viscosity while reducing the thickness, so that the display screen can be ensured not to have the defects of warping, stripping and the like in the folding process. Meanwhile, the folding performance requires that the modulus of the adhesive film is lower than that of the common OCA optical adhesive, especially the modulus at low temperature, so that larger deformation can be obtained to buffer interlayer displacement, and the problem of warping caused by stress concentration is prevented. Based on the above requirements, the adhesive film layer cannot be peeled off in the folding process of the display screen, the adhesive film layer has higher adhesive force, and in order to buffer the stress caused by interlayer displacement, the modulus of the adhesive film layer is as low as possible, but in general, the decrease of the modulus can cause the decrease of the adhesive force.
The following schemes are generally adopted to solve the problems at present:
(1) The use of monomers with a lower glass transition temperature (glass transition temperature, abbreviated as Tg) as much as possible, and the Tg of the crosslinking monomer is also low enough, while increasing the peel strength by increasing the amount of polar monomer; (2) The low Tg monomer is used as far as possible, the adding amount of the crosslinking monomer is controlled in a certain range, and the peeling strength is improved and the high temperature modulus is increased by adding the high Tg monomer containing nitrogen; (3) The low Tg monomer and crosslinking monomer are used as much as possible, the polar monomer is reduced, and the peel strength is improved by adding the oligomer to act as a tackifying resin.
However, the above solutions have some problems that are difficult to solve:
If the polar monomer is increased too much, the gel problem occurs, because the molecular weight of the flexible OCA optical adhesive is generally larger, so as to ensure that the modulus difference at high and low temperatures is small; adding Tg monomers with high nitrogen content can significantly increase the low temperature modulus, which is detrimental to low temperature folding properties; the increase in oligomers causes compatibility problems and the modulus decreases faster at high temperatures, resulting in poor high temperature performance.
Disclosure of Invention
In view of the above, the present invention provides an acrylic pressure-sensitive adhesive for a foldable display screen and an adhesive sheet thereof, which can reduce modulus loss at high temperature by introducing a high Tg oligomer to increase peeling force and simultaneously crosslinking the oligomer with a main adhesive, so as to solve the problem of balance between high and low temperature modulus and peeling force in the prior art.
According to a first aspect of the present invention, there is provided an acrylic pressure-sensitive adhesive for a foldable display screen, the acrylic pressure-sensitive adhesive comprising an acrylic copolymer a and an acrylic copolymer B having a weight average molecular weight of 20,000 to 35,000, the content of the acrylic copolymer B being 5 to 10 parts by mass with respect to 100 parts by mass of the acrylic copolymer a.
The weight average molecular weight of the acrylate copolymer B in the present invention is 20,000 to 35,000, and in some embodiments, the weight average molecular weight may be 20,000, 25,000, 30,000, 35,000, or any number between the two ends. Controlling the molecular weight of the acrylate copolymer B in this range in the present invention can improve the release force of the pressure-sensitive adhesive.
In the present invention, the content of the acrylate copolymer B is 5 to 10 parts by mass with respect to 100 parts by mass of the acrylate copolymer a, and in some embodiments, the content of the acrylate copolymer B may be 5 parts by mass, 6 parts by mass, 7 parts by mass, 7.5 parts by mass, 9 parts by mass, 10 parts by mass, or any value between the two ends. The content of the acrylate copolymer B in the present invention is limited within this range, and the peeling force and flexibility of the pressure-sensitive adhesive can be ensured.
The acrylic pressure sensitive adhesive provided by the invention can increase the stripping force by introducing a certain amount of oligomer with molecular weight in a specific range to act as tackifying resin, and the network crosslinking formed between the oligomer and the main adhesive can reduce the modulus loss of the adhesive at high temperature, so that the balance between high and low temperature modulus and the stripping force is realized.
In the present invention, the glass transition temperature (Tg) of the acrylate copolymer B is preferably 100 to 150 ℃, and in some embodiments, the Tg of the acrylate copolymer B may be specifically 100 ℃, 110 ℃, 120 ℃, 130 ℃, 132 ℃, 135 ℃, 137 ℃, 150 ℃, or any value between two end values. The higher Tg of the acrylate copolymer B in the invention can increase the stripping force of the adhesive.
The Tg of the acrylate copolymer a is < -40 ℃, in some embodiments, the Tg of the acrylate copolymer a can be any number below-45 ℃, -50 ℃, -52 ℃, -55 ℃, -60 ℃, or-40 ℃. The acrylate copolymer A used as the main adhesive has lower Tg and can lead the low-temperature modulus of the adhesive to be smaller.
In the invention, the total acrylate copolymer B monomer is 100 wt percent, and the acrylate copolymer B monomer comprises the following monomer components: 40-59 wt% of cyclic acrylate monomer, 30-40 wt% of nitrogen-containing monomer, 10-15 wt% of polar monomer and 1-5 wt% of functional monomer.
In the present invention, the content of the cyclic acrylate monomer is 40 to 59 wt% based on 100 wt% of the total amount of the acrylate copolymer B monomer, and in some embodiments, the content of the cyclic acrylate monomer may be specifically 40 wt%, 45 wt%, 50 wt%, 55 wt%, 59 wt%, or any value between the two end values. In addition, the cyclic acrylate monomer comprises isobornyl (meth) acrylate, and specifically can be isobornyl acrylate (IBOA) or isobornyl methacrylate (IBOMA). Because the volume of the acrylic ester monomer with a cyclic structure is larger, and particularly the isobornyl (methyl) acrylate contains double rings, the monomer has higher Tg, and the stripping force of the adhesive can be effectively enhanced.
In the present invention, the content of the nitrogen-containing monomer is 30 to 40 wt% based on 100 wt% of the total amount of the acrylate copolymer B monomer, and in some embodiments, the content of the nitrogen-containing monomer may be 30 wt%, 31 wt%, 35 wt%, 37 wt%, 40 wt%, or any value between the two end values. The nitrogen-containing monomer can be selected from one or two of N-vinyl-2-pyrrolidone (NVP) and N-vinyl caprolactam (NVC). The nitrogen-containing monomer has higher polarity and higher Tg, so that the stripping force of the adhesive can be effectively enhanced.
In the present invention, the content of the polar monomer is 10 to 15 wt% based on 100 wt% of the total amount of the acrylate copolymer B monomer, and in some embodiments, the content of the polar monomer may be 10 wt%, 11 wt%, 12.5 wt%, 13 wt%, 15 wt%, or any value between the two end values. The polar monomer comprises any one or a combination of a plurality of 2-hydroxyethyl acrylate (HEA for short), hydroxypropyl acrylate (HPA for short) and hydroxybutyl acrylate (4-HBA for short). The polar monomer is selected from acrylate monomers containing hydroxyl, is favorable for the compatibility between the oligomer and the main adhesive, and can obtain higher stripping force.
In the present invention, the content of the functional monomer is 1 to 5 wt% based on 100 wt% of the total amount of the acrylate copolymer B monomer, and in some embodiments, the content of the functional monomer may be specifically 1 wt%, 2 wt%, 2.5 wt%, 4 wt%, 5 wt%, or any value between the two end values. The functional monomer comprises any one or a combination of a plurality of 4-acryloylhydroxybenzophenone (ABP for short), 2-hydroxy-4-acryloyloxy benzophenone (AEBP for short), isocyanate ethyl acrylate (AOI-VM for short) and isocyano ethyl methacrylate (MOI for short). The functional monomer provides photopolymerization crosslinking effect, and under UV light irradiation, 4-acryloylhydroxybenzophenone and 2-hydroxy-4-acryloyloxy benzophenone can abstract H on polymer chains, so that free radicals are generated, and the free radicals of different polymer chains are combined to realize crosslinking. On the other hand, the unreacted double bonds contained in the two monomers of isocyanate ethyl acrylate (AOI-VM) and isocyanatoethyl Methacrylate (MOI) can also react and crosslink under the action of UV irradiation and a photoinitiator.
The acrylate copolymer B further comprises an initiator, wherein the content of the initiator is 0.01-1.5 parts by mass relative to 100 parts by mass of the total amount of the acrylate copolymer B monomers. The initiator comprises azo initiator or peroxide initiator, wherein the initiator only plays a role in initiating polymerization, and is not particularly limited, and the azo initiator can adopt any one or a combination of more of Azobisisobutyronitrile (AIBN), azobisisoheptonitrile (ABVN), azobisisovaleronitrile (AMBN) and dimethyl Azobisisobutyrate (AIBME); the peroxide initiator can be any one or a combination of a plurality of dibenzoyl peroxide (BPO for short), lauroyl peroxide (LPO for short), benzoyl tert-butyl peroxide (TBPB for short) and cumene hydroperoxide (CHP for short).
The acrylate copolymer B may further comprise a chain transfer agent, wherein the content of the chain transfer agent is 1-3 parts by mass relative to 100 parts by mass of the total amount of the acrylate copolymer B monomers. The chain transfer agent can promote the molecular weight of the acrylic ester copolymer B to be kept in a certain range, and the chain transfer agent can be one or a combination of two selected from 2, 4-diphenyl-4-methyl-1-pentene (TPMS for short) and pentaerythritol tetra (3-mercaptobutyrate) (PE 1 for short).
The acrylate copolymer B may further include a catalyst in an amount of not more than 0.6 parts by mass, preferably not less than 0.4 parts by mass, relative to 100 parts by mass of the total acrylate copolymer B monomer. In the invention, the catalyst comprises dibutyl tin dilaurate (DY-12 for short). The catalyst is not an essential component, and when the reactivity of certain functional monomers is low, such as AOI-VM and MOI, a certain amount of catalyst is added at the moment to help the normal reaction.
The acrylate copolymer B may further include a solvent, and the solvent content is 50 to 300 parts by mass with respect to 100 parts by mass of the total amount of the acrylate copolymer B monomers. In the invention, the solvent comprises one or a combination of more of Ethyl Acetate (EA), toluene (Tol) and butanone (MEK).
The invention also provides a method for preparing the acrylic ester copolymer B, which comprises the following steps: mixing and adding the cyclic acrylate monomer, the nitrogen-containing monomer, the polar monomer, the functional monomer, the chain transfer agent and the solvent in a mass ratio into a reaction device, introducing nitrogen for 0.5-2 hours, heating to 65-80 ℃, then adding the initiator, reacting for 2-3.5 hours, then heating to a reflux temperature of 75-85 ℃, and preserving heat for 3.5-4.5 hours to prepare an acrylate copolymer B solution; subsequently, the solvent, unreacted monomer, chain transfer agent, etc. are removed by distillation under reduced pressure to obtain the acrylate copolymer B in a solid state.
When the acrylic ester copolymer B contains a low-activity functional monomer, the preparation steps are as follows: mixing and adding the cyclic acrylate monomer, the nitrogen-containing monomer, the polar monomer, the chain transfer agent and the solvent in a mass ratio into a reaction device, introducing nitrogen for 0.5-2 hours, heating to 65-80 ℃, adding the initiator, reacting for 2-3.5 hours, heating to a reflux temperature of 75-85 ℃, and preserving heat for 3.5-4.5 hours; adding functional monomers and catalysts in a proportion when the temperature is reduced to 40-50 ℃, and continuously reacting for 4-6 hours to prepare the acrylic ester copolymer B solution; subsequently, the solvent, unreacted monomer, chain transfer agent, etc. are removed by distillation under reduced pressure to obtain the acrylate copolymer B in a solid state.
In the invention, the acrylate copolymer A comprises the following monomer components in percentage by weight based on 100 wt% of the total amount of the monomers: 45-75 wt% of a first monomer, 20-45 wt% of a second monomer and 5-10 wt% of a crosslinking monomer.
In the present invention, the first monomer content accounts for 45-75wt% based on 100 wt% of the total acrylate copolymer a monomer, and in some embodiments, the first monomer content may be 45-wt%, 50 wt%, 55-wt%, 60-wt%, 65-wt%, 70-wt%, 75-wt%, or any value between the two end values. In the present invention, the first monomer includes any one or a combination of a plurality of 2-ethylhexyl acrylate (2-EHA), n-Butyl Acrylate (BA), dodecyl methacrylate (LMA), isodecyl acrylate (IDA). The first monomer is a monomer with a lower Tg value, so that the adhesive performance of the adhesive can be ensured.
In the present invention, the second monomer content accounts for 20 to 45 wt% based on 100 wt% of the total acrylate copolymer a monomer, and in some embodiments, the second monomer content may be specifically 20 to wt%, 25 to wt%, 30 to wt%, 32.5 to wt%, 40 to wt%, 45 to wt%, or any value between the two end values. In the invention, the second monomer is one or the combination of two of dodecyl 2-acrylate (LA) and octadecyl acrylate (SA). According to the invention, the second monomer is alkyl acrylate with a longer alkyl chain segment, and the modulus and Tg of the polymer are greatly reduced through copolymerization of a large amount of first monomers and the second monomers, so that adverse effects caused by high Tg oligomer components are counteracted, and the low-temperature modulus of the adhesive is maintained at a lower level.
In the present invention, the content of the crosslinking monomer is 5 to 10 wt% based on 100 wt% of the total acrylate copolymer a monomer, and in some embodiments, may be specifically 5wt%, 6 wt%, 7.5 wt%, 8 wt%, 9 wt%, 10 wt%, or any value between the two end values. In the invention, the crosslinking monomer comprises any one or a combination of a plurality of hydroxybutyl acrylate (abbreviated as 4-HBA), 2-hydroxyethyl acrylate (abbreviated as HEA), 2-hydroxyethyl methacrylate (abbreviated as 2-HEMA) and hydroxypropyl acrylate (abbreviated as HPA).
In the present invention, the acrylate copolymer a further includes a photoinitiator, and the content of the photoinitiator is 0.05 to 0.5 parts by mass, and in some embodiments, may be specifically 0.05 parts by mass, 0.1 parts by mass, 0.2 parts by mass, 0.3 parts by mass, 0.4 parts by mass, 0.5 parts by mass, or any value between the two ends, with respect to 100 parts by mass of the total amount of the acrylate copolymer a monomer components. The photoinitiator may be selected from any one or a combination of more of the photoinitiators 184, 651, TPO.
The invention also provides a method for preparing the acrylic ester copolymer A, which comprises the following steps: mixing the first monomer, the second monomer, the crosslinking monomer and the photoinitiator according to the mass ratio, adding the mixture into a reaction device, introducing nitrogen for 0.5-2 hours, then turning on a UV lamp for irradiation until the viscosity of the mixture reaches about 3,000 cps, turning off the UV lamp, and stopping the reaction to obtain the acrylic ester copolymer A.
The acrylic pressure-sensitive adhesive of the present invention further comprises a crosslinking agent in an amount of 0.1 to 1 part by mass with respect to 100 parts by mass of the acrylic copolymer a, and in some embodiments, the crosslinking agent may be in an amount of 0.1 part by mass, 0.2 part by mass, 0.3 part by mass, 0.4 part by mass, 0.5 part by mass, 0.6 part by mass, 0.7 part by mass, 1 part by mass, or any value between both ends. In the present invention, the crosslinking agent may be selected from a polyfunctional acrylate monomer, and the polyfunctional acrylate monomer may be selected from one or a combination of two of 1, 6-hexanediol diacrylate (abbreviated as HDDA) and trimethylolpropane triacrylate (abbreviated as TMPTA).
The preparation method of the pressure-sensitive adhesive can be prepared according to the following steps: and mixing the acrylic ester copolymer A, the acrylic ester copolymer B and the crosslinking agent, fully stirring, standing and defoaming to obtain the pressure-sensitive adhesive to be coated.
The second aspect of the present invention provides an adhesive sheet comprising an adhesive layer comprising the cured product of the acrylic pressure-sensitive adhesive for a foldable display screen according to the first aspect of the present invention.
The cured product of the acrylic pressure-sensitive adhesive for a foldable display screen in the present invention refers to a film formed after the adhesive is cured by coating. The adhesive sheet of the invention can contain other adhesive layers or substrate layers besides the adhesive layer, or can contain other combinations of the adhesive layers and the substrate layers, and different structures can be designed according to actual requirements. In the present invention, the specific structure of the adhesive sheet is not limited, and the thickness of the adhesive layer is not particularly limited, and the thickness of the adhesive layer may be 25 to 150 μm.
The adhesive sheet provided by the invention is used for bonding structural components of a foldable display screen, the adhesive layer keeps good adhesive force under the condition of keeping a thinner thickness, and meanwhile, the shear modulus of the adhesive sheet at a low temperature is lower, so that larger deformation is obtained to buffer interlayer displacement, and therefore, the display screen is ensured not to warp after being folded for many times.
Compared with the prior art, the invention has the following beneficial effects:
(1) The acrylic pressure sensitive adhesive for the foldable display screen provided by the invention has the advantages that the high Tg oligomer is introduced to serve as tackifying resin to increase the peeling force, and meanwhile, the modulus and Tg increase caused by the high Tg oligomer are counteracted by the internal plasticization of the second monomer, so that the modulus and Tg of the whole system are kept at lower level; in addition, the oligomer and the main adhesive are crosslinked to prevent the problems of phase separation, sudden modulus drop and the like of the adhesive film in a high-temperature or temperature and humidity environment due to the migration of a low-molecular part.
(2) The adhesive sheet provided by the invention has good adhesive force and low shear modulus, and is suitable for bonding of foldable display screens.
Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention relates.
The technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified. The invention is described in detail below in connection with specific embodiments, which are intended to be illustrative rather than limiting. The parts in the following examples are parts by mass, 1 part representing 1g.
Example 1
1. Preparation of acrylate copolymer A
(1) Composition of raw materials
A first monomer: 60 parts of 2-EHA;
and a second monomer: LA,32.5 parts;
crosslinking monomer: HEA,7.5 parts;
and (3) a photoinitiator: 184,0.25 parts of photoinitiator;
(2) Preparation method
In a reaction kettle, adding the raw material components in the proportion, introducing nitrogen for one hour, then turning on a UV lamp for irradiation until the viscosity reaches about 3000 cps, turning off the UV lamp, and stopping the reaction to obtain an acrylic ester copolymer A, wherein the Tg of the acrylic ester copolymer A is-55 ℃.
2. Preparation of acrylate copolymer B
(1) Composition of raw materials
Cyclic acrylate monomers: IBOMA,50 parts;
Nitrogen-containing monomers: NVP,35 parts;
polar monomer: 12.5 parts of 4-HBA;
functional monomer: 2.5 parts of AOI-VM;
And (3) an initiator: AIBN,1 part;
Chain transfer agent: PE1,2 parts;
Catalyst: DY-12,0.5 parts;
solvent: MEK,100 parts;
(2) Preparation method
In a reaction kettle, adding the cyclic acrylate monomer, the nitrogen-containing monomer, the polar monomer, the chain transfer agent and the solvent according to the mass ratio, introducing nitrogen for 1 hour, and heating to 70 ℃. After initiator is added, the reaction is carried out for 3 hours, then the temperature is raised to 80 ℃ of reflux temperature, and the temperature is kept for 4 hours; cooling to 45 ℃, adding functional monomers and catalysts in parts by mass, and continuing to react for 5 hours to obtain an acrylic ester copolymer B solution; subsequently, the solvent, unreacted monomer, chain transfer agent, and the like were removed by distillation under reduced pressure to obtain an acrylate copolymer B solid having a weight average molecular weight of 30,000 and a Tg of 137 ℃.
3. Preparation of the adhesive
100 Parts of the acrylic copolymer A, 7.5 parts of the acrylic copolymer B and 0.5 part of the crosslinking agent HDDA prepared in the above way are mixed, and the mixture is fully stirred and then is left to stand for defoaming, so that the adhesive to be coated can be obtained.
Example 2
This example was conducted with reference to example 1, and the preparation methods of the acrylate copolymer a and the adhesive were the same as in example 1, and the preparation method of the acrylate copolymer B was different from example 1, and the specific differences were as follows:
1. preparation of acrylate copolymer A
(1) Composition of raw materials
A first monomer: 45 parts of 2-EHA;
and a second monomer: LA,45 parts;
crosslinking monomer: 10 parts of 4-HBA;
And (3) a photoinitiator: 184,0.05 parts of photoinitiator;
the Tg of the acrylate copolymer A prepared was-60 ℃.
2. Preparation of acrylate copolymer B
(1) Composition of raw materials
Cyclic acrylate monomers: IBOA,59 parts;
nitrogen-containing monomers: NVC,30 parts;
Polar monomer: HPA,10 parts;
functional monomer: AEBP,1 part;
And (3) an initiator: BPO,1 part;
chain transfer agent: TPMS,2 parts;
Solvent: tol,100 parts;
mixing and adding the cyclic acrylate monomer, the nitrogen-containing monomer, the polar monomer, the functional monomer, the chain transfer agent and the solvent in mass ratio into a reaction device, introducing nitrogen for 1 hour, heating to 70 ℃, adding the initiator, reacting for 3 hours, heating to a reflux temperature of 80 ℃, and preserving heat for 4 hours to prepare the acrylate copolymer B solution; subsequently, the solvent, unreacted monomer, chain transfer agent, etc. are removed by distillation under reduced pressure to obtain the acrylate copolymer B in a solid state. The weight average molecular weight of the prepared acrylate copolymer B was 35,000 and Tg was 135 ℃.
3. Preparation of the adhesive
The adhesive contains 100 parts of the acrylate copolymer A, 10 parts of the acrylate copolymer B and 0.1 part of the crosslinking agent TMPTA.
Example 3
This example was conducted with reference to example 1, and the preparation methods of the acrylate copolymer a and the adhesive were the same as in example 1, and the preparation method of the acrylate copolymer B was different from example 1, and the specific differences were as follows:
1. preparation of acrylate copolymer A
(1) Composition of raw materials
A first monomer: 75 parts of 2-EHA;
and a second monomer: LA,20 parts;
Crosslinking monomer: HEA,5 parts;
And (3) a photoinitiator: 184,0.5 parts of photoinitiator;
The Tg of the acrylate copolymer A prepared was-50 ℃.
2. Preparation of acrylate copolymer B
(1) Composition of raw materials
Cyclic acrylate monomers: IBOMA,40 parts;
Nitrogen-containing monomers: NVP,40 parts;
polar monomer: HEA,15 parts;
functional monomer: ABP,5 parts;
And (3) an initiator: AIBN,1 part;
Chain transfer agent: PE1,2 parts;
solvent: EA,100 parts;
mixing and adding the cyclic acrylate monomer, the nitrogen-containing monomer, the polar monomer, the functional monomer, the chain transfer agent and the solvent in mass ratio into a reaction device, introducing nitrogen for 1 hour, heating to 70 ℃, adding the initiator, reacting for 3 hours, heating to a reflux temperature of 80 ℃, and preserving heat for 4 hours to prepare the acrylate copolymer B solution; subsequently, the solvent, unreacted monomer, chain transfer agent, etc. are removed by distillation under reduced pressure to obtain the acrylate copolymer B in a solid state. The weight average molecular weight of the prepared acrylate copolymer B was 20,000 and Tg was 130 ℃.
3. Preparation of the adhesive
The adhesive contains 100 parts of the acrylate copolymer A, 5 parts of the acrylate copolymer B and 1 part of the crosslinking agent HDDA, which are prepared in the above way.
Example 4
This example was carried out with reference to example 1, and the preparation method is the same as in example 1, except that the components are not changed, and the substances and contents which are not listed are as follows:
1. preparation of acrylate copolymer A
(1) Composition of raw materials
A first monomer: IDA,60 parts;
And a second monomer: SA,32.5 parts;
Crosslinking monomer: 7.5 parts of 4-HBA;
And (3) a photoinitiator: 651,0.25 parts of photoinitiator;
the Tg of the acrylate copolymer A prepared was-55 ℃.
2. Preparation of acrylate copolymer B
(2) Composition of raw materials
Polar monomer: HEA,12.5 parts;
functional monomer: MOI,2.5 parts;
the weight average molecular weight of the prepared acrylate copolymer B was 30,000 and Tg was 132 ℃.
3. Preparation of the adhesive
The adhesive contains 10 parts of acrylate copolymer B.
Example 5
This example was carried out with reference to example 1, and the preparation method is the same as in example 1, except that the components are not changed, and the substances and contents which are not listed are as follows:
1. preparation of acrylate copolymer A
(1) Composition of raw materials
Crosslinking monomer: HPA,7.5 parts;
and (3) a photoinitiator: TPO,0.25 part;
the Tg of the acrylate copolymer A prepared was-52 ℃.
2. Preparation of the adhesive
The adhesive contains 5 parts of acrylate copolymer B.
Comparative example 1 group
The comparative examples were carried out in the same manner as in example 1, except that the amount of the acrylic acid ester copolymer B and the content of the polar monomer in the acrylic acid ester copolymer B were adjusted as in example 1, and the amounts of the substances and the contents not shown were not changed, as follows:
Comparative example 1a: the adhesive does not contain the acrylic copolymer B;
comparative example 1b: the dosage of the acrylic ester copolymer B is 15 parts;
Comparative example 1c: the polar monomer in the acrylic ester copolymer B is HEA, the dosage of the polar monomer is 15 parts, and the polar monomer does not contain functional monomers and catalysts; the weight average molecular weight of the prepared acrylate copolymer B was 30,000 and Tg was 135 ℃.
Comparative example 2 group
This comparative example was carried out with reference to example 1, and was prepared in the same manner as in example 1, with the contents of the first monomer and the second monomer in the acrylate copolymer a being adjusted, and the substances and contents not listed were not changed, specifically differing as follows:
Comparative example 2a: 92.5 parts of a first monomer in the acrylate copolymer A, and no second monomer; the Tg of the acrylate copolymer A is-50 ℃;
Comparative example 2b: 42.5 parts of a first monomer and 50 parts of a second monomer in the acrylate copolymer A; the Tg of the acrylate copolymer A is-54 ℃;
Comparative example 2c: 77.5 parts of a first monomer and 15 parts of a second monomer in the acrylate copolymer A; the Tg of the acrylate copolymer A was-48 ℃.
Test case
The adhesive prepared in each example and comparative example is coated on the surface of a 50um PET release film by a slit coating process, a UV lamp is turned on to irradiate for 6min at illuminance of 5mW/cm 2, then the adhesive is baked for 5min in a baking oven at 100 ℃, and then the 50um PET release film is compounded, so that a film test sample with the adhesive layer thickness of 50um can be obtained.
Test item
The pressure-sensitive adhesive sheet of the present invention was mainly tested for 180 ° peel force at ordinary temperature, shear modulus at different temperatures, and folding properties at different temperatures.
1. 180 ° Peel force test: the test specimens were cut into 2.5cm wide strips, and the test method was performed according to international standard astm d3330 "pressure-sensitive adhesive tape peel strength test standard", the test panels being glass plates and Polyimide (PI) plates. The testing method comprises the following steps: the test specimen was allowed to stand at room temperature for 20 minutes and then tested, and the average adhesion force required to tear the spline off the test panel was recorded as gf/25 mm.
2. Shear modulus test: the PET release films on both sides of the test sample prepared above were removed, and a sample having a thickness of about 1mm was obtained by overlapping a plurality of film layers, and cut into a disk shape having a diameter of 8mm, and shear moduli at different temperatures were measured using a rheometer (TA company, model: HR 10), the frequency was measured at 1Hz, and the measured shear modulus values were recorded as kPa.
(3) Folding performance test: tearing off PET release films on two sides of the prepared test sample, sequentially and alternately attaching the adhesive film layers and 50 mu m PI layers to prepare a composite structure with 2 adhesive film layers and 3 PI layers sequentially designed at intervals, and standing for 30min at the temperature of 50 ℃ under the pressure of 0.5MPa for defoaming. Then, folding performance at different temperatures was tested by a folding apparatus (Beijing Wo Huahui, equipment model: WH-1711-2W), the folding radius of curvature of which was R=1 mm. And recording the folding times completed when the appearance of the composite structure is abnormal, wherein the appearance abnormality comprises defects such as bubbles, layering, serious folds and the like.
The 180℃peel force, shear modulus and folding properties at low temperature (-20 ℃), normal temperature (25 ℃) and high temperature (65 ℃) are shown in Table 1.
TABLE 1
As shown in the test results of Table 1, the adhesive sheet prepared by the scheme of the invention has excellent peel strength to the glass plate and the PI plate, has good folding performance at high and low temperatures, and has the folding times of more than 20 ten thousand times, thereby meeting the use requirements; the difference in shear modulus at high and low temperatures is small.
As can be seen from the combination of example 1 and comparative example 1a, the acrylate copolymer B of comparative example 1a, to which no oligomer is added, although its low temperature modulus can be effectively reduced, is advantageous for low temperature properties, but the peel force is too low and the high temperature shear modulus is too low, resulting in poor folding properties. The present invention has been made to solve the above problems, and an object of the present invention is to provide an adhesive sheet which can maintain a shear modulus at a high temperature, and which can provide a strong peel force and a good folding property, even though a certain amount of an oligomer component is added to the adhesive. As can be seen from comparative example 1b, when the amount of the oligomer added is too large, the low-temperature modulus tends to be high, and the overall folding property tends to be poor.
It can be seen from a combination of example 1 and comparative example 1c that the low molecular weight fraction migration is severe at high temperature when the functional monomer is not contained in the acrylate copolymer B of the oligomer, resulting in a rapid decrease in modulus and poor performance at high Wen Shedie, thus indicating that the present invention employs a crosslinkable oligomer component in the adhesive system, so that the adhesive sheet can be folded at high temperature many times without deformation.
It can be seen from a combination of example 1 and comparative example 2 that the absence of the second monomer in comparative example 2a, the lack of internal plasticization of the long chain branches, results in an adhesive sheet with a higher low temperature modulus and poor low temperature folding properties, thus indicating that the present invention employs the use of dodecyl methacrylate and/or octadecyl acrylate in acrylate polymers for crosslinking, ensuring that the adhesive system has a low Tg and a lower low temperature shear modulus. In comparative example 2b, the amount of the second monomer added was too much to be used, and in comparative example 2c, the amount of the second monomer added was too low, which also resulted in a high low temperature modulus and poor low temperature folding properties, thus indicating that the use of dodecyl methacrylate and/or octadecyl acrylate as the second monomer within the scope defined by the present invention not only ensured the normal morphology of the adhesive, but also achieved the purpose of providing the adhesive sheet with a low tg and a low temperature shear modulus.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing the functions in the order shown or discussed, but may also include performing the functions in a substantially simultaneous manner or in an opposite order depending on the functions involved, e.g., the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is to be construed as including any modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. The acrylic pressure-sensitive adhesive for the foldable display screen is characterized by comprising an acrylic copolymer A and an acrylic copolymer B with a weight average molecular weight of 20,000-35,000, wherein the content of the acrylic copolymer B is 5-10 parts by mass relative to 100 parts by mass of the acrylic copolymer A;
the acrylate copolymer A comprises the following monomer components in percentage by mass based on 100 wt% of the total monomer component of the acrylate copolymer A: 45-75 wt% of a first monomer, 20-45 wt% of a second monomer and 5-10 wt% of a crosslinking monomer; the second monomer is one or the combination of two of 2-dodecyl acrylate and octadecyl acrylate, and the first monomer comprises one or the combination of more of 2-ethylhexyl acrylate, n-butyl acrylate, dodecyl methacrylate and isodecyl acrylate; the crosslinking monomer comprises any one or a combination of a plurality of hydroxybutyl acrylate, 2-hydroxyethyl methacrylate and hydroxypropyl acrylate;
The glass transition temperature of the acrylic ester copolymer B is 100-150 ℃, and the glass transition temperature of the acrylic ester copolymer A is < -40 ℃;
The acrylate copolymer B comprises the following monomer components in percentage by mass based on 100 wt% of the total monomer component of the acrylate copolymer B: 40-59 wt% of cyclic acrylate monomer, 30-40 wt% of nitrogen-containing monomer, 10-15 wt% of polar monomer and 1-5 wt% of functional monomer; wherein the cyclic acrylate monomer comprises isobornyl (meth) acrylate, the functional monomer comprises any one or more of 4-acryloyloxybenzophenone, 2-hydroxy-4-acryloyloxy benzophenone, isocyanate ethyl acrylate and isocyanatoethyl methacrylate, and the nitrogen-containing monomer comprises one or two of N-vinyl-2-pyrrolidone and N-vinyl caprolactam; the polar monomer comprises any one or a combination of a plurality of 2-hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate.
2. The acrylic pressure-sensitive adhesive for a foldable display screen according to claim 1, wherein the acrylic copolymer B further comprises an initiator and a chain transfer agent; the content of the initiator is 0.01-1.5 parts by mass and the content of the chain transfer agent is 1-3 parts by mass relative to 100 parts by mass of the total amount of the acrylate copolymer B monomers.
3. The acrylic pressure-sensitive adhesive for a foldable display screen according to claim 2, wherein the initiator comprises an azo-type initiator or a peroxide-type initiator.
4. The acrylic pressure sensitive adhesive for a foldable display screen according to claim 2, wherein the chain transfer agent comprises one or a combination of two of 2, 4-diphenyl-4-methyl-1-pentene and pentaerythritol tetrakis (3-mercaptobutyrate).
5. The acrylic pressure-sensitive adhesive for a foldable display screen according to any one of claims 1 to 4, further comprising a crosslinking agent in an amount of 0.1 to 1 part by mass relative to 100 parts by mass of the acrylic copolymer a.
6. The acrylic pressure sensitive adhesive for a foldable display screen of claim 5, wherein the cross-linking agent is selected from the group consisting of polyfunctional acrylate monomers.
7. The acrylic pressure sensitive adhesive for a foldable display screen according to claim 6, wherein the polyfunctional acrylate monomer is selected from one or a combination of two of 1, 6-hexanediol diacrylate and trimethylolpropane triacrylate.
8. An adhesive sheet comprising an adhesive layer, wherein the adhesive layer comprises the cured product of the acrylic pressure-sensitive adhesive for a foldable display screen according to any one of claims 1 to 7.
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| CN202410421285.XA CN118006261B (en) | 2024-04-09 | Acrylic pressure-sensitive adhesive for foldable display screen and adhesive sheet thereof |
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|---|---|---|---|---|
| JP2022132137A (en) * | 2021-02-26 | 2022-09-07 | 大塚化学株式会社 | Adhesive composition for flexible display, adhesive material, and adhesive sheet |
| CN115141554A (en) * | 2021-03-31 | 2022-10-04 | 琳得科株式会社 | Adhesive sheet, repeatedly bending laminated member, and repeatedly bending device |
| CN116023864A (en) * | 2022-10-11 | 2023-04-28 | 新纶电子材料(常州)有限公司 | Optical adhesive, adhesive sheet and preparation method thereof |
| CN116656262A (en) * | 2023-05-26 | 2023-08-29 | 浙江东柔新材料有限公司 | Adhesive for flexible display, adhesive sheet, laminate, and display |
| CN117089014A (en) * | 2023-10-18 | 2023-11-21 | 江苏皇冠新材料科技有限公司 | Acrylate copolymer, adhesive and protective film |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2022132137A (en) * | 2021-02-26 | 2022-09-07 | 大塚化学株式会社 | Adhesive composition for flexible display, adhesive material, and adhesive sheet |
| CN115141554A (en) * | 2021-03-31 | 2022-10-04 | 琳得科株式会社 | Adhesive sheet, repeatedly bending laminated member, and repeatedly bending device |
| CN116023864A (en) * | 2022-10-11 | 2023-04-28 | 新纶电子材料(常州)有限公司 | Optical adhesive, adhesive sheet and preparation method thereof |
| CN116656262A (en) * | 2023-05-26 | 2023-08-29 | 浙江东柔新材料有限公司 | Adhesive for flexible display, adhesive sheet, laminate, and display |
| CN117089014A (en) * | 2023-10-18 | 2023-11-21 | 江苏皇冠新材料科技有限公司 | Acrylate copolymer, adhesive and protective film |
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