Double-sided tape and multi-layer structures

Abstract

The present disclosure provides a double-sided adhesive tape, comprising: a first adhesive layer, comprising a first resin and a first thermal crosslinking agent, wherein the first resin comprises a hydroxyl group, the first thermal crosslinking agent comprises a first group that can react with the hydroxyl group of the first resin, and the ratio of the equivalent number of the first group of the first thermal crosslinking agent to the equivalent number of the hydroxyl group of the first resin is represented by r1; and a second adhesive layer, comprising a second resin and a second thermal crosslinking agent, wherein the second resin comprises a hydroxyl (OH) group, the second thermal crosslinking agent comprises a second group that can react with the hydroxyl group of the second resin, and the ratio of the equivalent number of the second group of the second thermal crosslinking agent to the equivalent number of the hydroxyl group of the second resin is represented by r2, wherein r1 <r2≦0.8,r2–r1≧0.025。

Description

Technical field

[0001] The present disclosure relates to a double-sided adhesive tape, and more particularly to a double-sided adhesive tape that can be peeled off by freezing. [Background Technology]

[0002] Existing display technologies use optical adhesives to bond and secure the display's cover and panel, as well as the panel and display module's polarizer. To prevent the two panels from peeling, existing optical adhesives often emphasize their strong adhesion. However, this strong adhesive property also comes with processing difficulties.

[0003] Panel factories use two main processing techniques: one uses low-temperature treatment on the panels before peeling off the two panels bonded together with optical adhesive; the other uses a machine to cut the optical adhesive and then peel off the two panels. However, because both methods adhere part of the optical adhesive to both panels at the same time, both methods require a lot of manpower and use a large amount of solvent to remove the adhesive, which is time-consuming and environmentally unfriendly. In addition, the polarizer is easily damaged during the residual adhesive removal process. [Summary of the invention]

[0004] According to an embodiment of the present disclosure, a double-sided adhesive tape is provided, comprising: a first adhesive layer comprising a first resin and a first thermal crosslinking agent, wherein the first resin comprises a hydroxyl (OH) group, the first thermal crosslinking agent comprises a first group that can react with the hydroxyl group of the first resin, and the ratio of the number of equivalents of the first group of the first thermal crosslinking agent to the number of equivalents of the hydroxyl group of the first resin is represented by r1; and a second adhesive layer comprising a second resin and a second thermal crosslinking agent, wherein the second resin comprises a hydroxyl (OH) group, the second thermal crosslinking agent comprises a second group that can react with the hydroxyl group of the second resin, and the ratio of the number of equivalents of the second group of the second thermal crosslinking agent to the number of equivalents of the hydroxyl group of the second resin is represented by r2, wherein r1 <r2≦0.8,r2–r1≧0.025。

[0005] According to an embodiment of the present disclosure, a multilayer structure is provided, comprising: a first substrate; a second substrate; and the double-sided tape as described above, wherein the first adhesive layer has a first surface, the second adhesive layer has a second surface, the first surface contacts the first substrate, and the second surface contacts the second substrate.

[0006] The present disclosure provides a double-sided adhesive tape with differentiated peel adhesion after low-temperature treatment. The double-sided adhesive tape is used for assembling displays and includes at least a first surface and a second surface, each used to adhere and secure a panel and a polarizer of a display module. After low-temperature treatment, the adhesive strength of the first and second surfaces of the double-sided adhesive tape is significantly reduced, and a difference in adhesive strength is created between the two surfaces. This allows for easy separation of two adhered panels and prevents the adhesive from remaining on both panels, particularly the polarizer.

Brief Description of the Drawings

[0007] Figure 1 It is a schematic cross-sectional view of a multilayer structure according to an embodiment of the present disclosure. [Specific implementation method]

[0008] According to one embodiment of the present disclosure, a double-sided adhesive tape is provided, comprising: a first adhesive layer and a second adhesive layer. The first adhesive layer comprises a first resin and a first thermal crosslinker. The first resin comprises a hydroxyl (OH) group. The first thermal crosslinker comprises a first group that can react with the hydroxyl group of the first resin. The ratio of the equivalent number of the first group of the first thermal crosslinker to the equivalent number of the hydroxyl group of the first resin is represented by r1. The second adhesive layer comprises a second resin and a second thermal crosslinker. The second resin comprises a hydroxyl (OH) group. The second thermal crosslinker comprises a second group that can react with the hydroxyl group of the second resin. The ratio of the equivalent number of the second group of the second thermal crosslinker to the equivalent number of the hydroxyl group of the second resin is represented by r2. It is worth noting that the above r1 and r2 meet the following numerical conditions: r1 <r2≦0.8,r2–r1≧0.025。

[0009] In some embodiments, the monomer composition of the first resin may include a hydroxyl-containing monomer, a hydrophilic monomer without a hydroxyl group, and an alkyl (meth)acrylate monomer. In some embodiments, the carbon number of the alkyl group in the alkyl (meth)acrylate monomer is approximately greater than or equal to 3 and approximately less than or equal to 12. In some embodiments, the first resin comprises approximately 1 to 10 parts by weight of the hydroxyl-containing monomer, approximately 1 to 20 parts by weight of the hydrophilic monomer without a hydroxyl group, and approximately 75 to 95 parts by weight of the alkyl (meth)acrylate monomer, all based on 100 parts by weight of the total weight of the monomers in the first resin.

[0010] In some embodiments, the monomer composition of the second resin may include a hydroxyl-containing monomer, a non-hydroxyl-containing hydrophilic monomer, and an alkyl (meth)acrylate monomer. In some embodiments, the carbon number of the alkyl group in the alkyl (meth)acrylate monomer is approximately greater than or equal to 3 and approximately less than or equal to 12. In some embodiments, the second resin comprises approximately 1 to 10 parts by weight of the hydroxyl-containing monomer, approximately 1 to 20 parts by weight of the non-hydroxyl-containing hydrophilic monomer, and approximately 75 to 95 parts by weight of the alkyl (meth)acrylate monomer, all based on 100 parts by weight of the total weight of the monomers in the second resin.

[0011] In some embodiments, the hydroxyl-containing monomer may include acrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, or hydroxybutyl (meth) acrylate.

[0012] In some embodiments, the hydrophilic monomer without a hydroxyl group may include acrylonitrile, acrylamide, acryloyl morpholine, or N-vinyl-2-pyrrolidone.

[0013] In some embodiments, the first resin and the second resin have the same monomer composition. In some embodiments, the first resin and the second resin have different monomer compositions.

[0014] In some embodiments, the first group and the second group may include an isocyanate group, a carboxyl group, an aziridine group, an anhydride group, or a melamine group.

[0015] See also Figure 1 According to an embodiment of the present disclosure, a multilayer structure 10 is provided. Figure 1 Schematic cross-sectional view of the multilayer structure 10 .

[0016] like Figure 1As shown, the multilayer structure 10 includes a first substrate 12, a second substrate 14, and a double-sided tape 16. The double-sided tape 16 has a first surface 16a and a second surface 16b relative to the first surface 16a. The first surface 16a of the double-sided tape 16 is in contact with the first substrate 12. The second surface 16b of the double-sided tape 16 is in contact with the second substrate 14. The double-sided tape 16 includes a resin and a thermal crosslinking agent. The above-mentioned resin includes a hydroxyl (OH) group. The above-mentioned thermal crosslinking agent includes a group that can react with the above-mentioned hydroxyl group. On the first surface 16a of the double-sided tape 16, the ratio of the equivalent number of the above-mentioned groups of the thermal crosslinking agent to the equivalent number of hydroxyl groups of the above-mentioned resin is represented by r1, and on the second surface 16b of the double-sided tape 16, the ratio of the equivalent number of the above-mentioned groups of the thermal crosslinking agent to the equivalent number of hydroxyl groups of the above-mentioned resin is represented by r2. It is worth noting that the above-mentioned r1 and r2 meet the following numerical conditions: r1 <r2≦0.8,r2–r1≧0.025。

[0017] In some embodiments, the first substrate 12 may include a panel, such as a touch panel, but the present disclosure is not limited thereto. Other suitable components, such as the glass of a solar module or the top glass of a liquid crystal cell, may also serve as the first substrate 12. In some embodiments, the panel may include transparent glass or a transparent substrate, and a transparent conductive electrode may be included on at least one surface of the transparent glass or transparent substrate.

[0018] In some embodiments, the second substrate 14 may include a polarizer, but the present disclosure is not limited thereto. Other suitable components, such as a backplane of a solar module or a bottom glass of a liquid crystal cell, may also serve as the second substrate 14 .

[0019] In some embodiments, the monomer composition of the resin may include a hydroxyl-containing monomer, a non-hydroxyl-containing hydrophilic monomer, and an alkyl (meth)acrylate monomer. In some embodiments, the carbon number of the alkyl group in the alkyl (meth)acrylate monomer is approximately greater than or equal to 3 and approximately less than or equal to 12. In some embodiments, the resin comprises approximately 1 to 10 parts by weight of the hydroxyl-containing monomer, approximately 1 to 20 parts by weight of the non-hydroxyl-containing hydrophilic monomer, and approximately 75 to 95 parts by weight of the alkyl (meth)acrylate monomer, based on 100 parts by weight of the total weight of the monomers in the resin.

[0020] In some embodiments, the hydroxyl-containing monomer may include acrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, or hydroxybutyl (meth) acrylate.

[0021] In some embodiments, the hydrophilic monomer without a hydroxyl group may include acrylonitrile, acrylamide, acryloyl morpholine, or N-vinyl-2-pyrrolidone.

[0022] In some embodiments, the groups may include isocyanate groups, carboxyl groups, aziridine groups, anhydride groups, or melamine groups.

[0023] In some embodiments, after the multilayer structure 10 is subjected to a treatment at a temperature of approximately -20°C to approximately -130°C for approximately 1 minute to approximately 1 hour, the peel adhesion of the first surface 16a and the second surface 16b to the adhesive layer 16 is represented by PA1 and PA2, respectively. It is noteworthy that PA1 and PA2 meet the following numerical condition: PA1>PA2.

[0024] Synthesis example 1

[0025] Synthesis of Resin A

[0026] A four-necked reaction flask was assembled, equipped with a thermometer, condenser, stirring rod, and heater. The condensate temperature of the condenser was maintained at -15°C. 205.31 g of toluene was added to the four-necked reaction flask, which was then filled with nitrogen and stirred at 200 rpm. The solvent temperature was then raised and maintained at 85°C. A clear mixed solution containing 95.35 g of toluene, 11.53 g of acrylic acid, 74.28 g of acrylonitrile, 312.73 g of butyl acrylate, and 1.99 g of azobisisobutyronitrile as an initiator was then added to the four-necked reaction flask for 16 hours to produce a Resin A solution having a solids content of 57.1 wt%.

[0027] Synthesis example 2

[0028] Synthesis of Resin B

[0029] A four-necked reaction flask was assembled, equipped with a thermometer, a condenser, a stirring rod, and a heater. The condensate temperature of the condenser was maintained at -15°C. 253.17 g of toluene was added to the four-necked reaction flask, which was then filled with nitrogen and stirred at 200 rpm. The solvent temperature was then raised and maintained at 85°C. A clear mixed solution containing 117.57 g of toluene, 26.03 g of hydroxypropyl acrylate, 14.22 g of acrylamide, 66.68 g of N-vinyl-2-pyrrolidone, 384.51 g of butyl acrylate, and 2.46 g of azobisisobutyronitrile as an initiator was added to the four-necked reaction flask for reaction for 16 hours to obtain a resin B solution having a solid content of 57.1 wt%.

[0030] Synthesis example 3

[0031] Synthesis of Resin C

[0032] A four-necked reaction flask was assembled, equipped with a thermometer, a condenser, a stirring rod, and a heater. The condensate temperature of the condenser was maintained at -15°C. 255.53 g of toluene was added to the four-necked reaction flask, which was then filled with nitrogen and stirred at 200 rpm. The solvent temperature was then raised and maintained at 85°C. A clarified mixed solution containing 118.67 g of toluene, 11.67 g of hydroxyethyl acrylate, 14.42 g of hydroxybutyl acrylate, 28.43 g of acrylamide, 62.11 g of acryloylmorpholine, 379.38 g of butyl acrylate, and 2.48 g of azobisisobutyronitrile as an initiator was added to the four-necked reaction flask for 16 hours to obtain a resin C solution having a solid content of 57.1 wt%.

[0033] Synthesis example 4

[0034] Synthesis of Resin D

[0035] A four-necked reaction flask was assembled, equipped with a thermometer, a condenser, a stirring rod, and a heater. The condensate temperature of the condenser was maintained at -15°C. 253.35 g of toluene was added to the four-necked reaction flask, which was then filled with nitrogen and stirred at 200 rpm. The solvent temperature was then raised and maintained at 85°C. A clear mixed solution containing 117.66 g of toluene, 26.03 g of hydroxypropyl acrylate, 6.37 g of acrylonitrile, 80.02 g of N-vinyl-2-pyrrolidone, 379.38 g of butyl acrylate, and 4.75 g of azobisisobutyronitrile as an initiator was added to the four-necked reaction flask for reaction for 16 hours to obtain a resin D solution having a solid content of 57.2 wt%.

[0036] Synthesis example 5

[0037] Synthesis of Resin E

[0038] A four-necked reaction flask was assembled, equipped with a thermometer, a condenser, a stirring rod, and a heater. The condensate temperature of the condenser was maintained at -15°C. 260.28 g of toluene was added to the four-necked reaction flask, which was then filled with nitrogen and stirred at 200 rpm. The solvent temperature was then raised and maintained at 85°C. A clear mixed solution containing 120.87 g of toluene, 20.82 g of hydroxypropyl acrylate, 10.61 g of acrylonitrile, 79.06 g of acryloylmorpholine, 394.76 g of butyl acrylate, and 10.96 g of azobisisobutyronitrile as an initiator was added to the four-necked reaction flask for reaction for 16 hours to obtain a resin E solution having a solid content of 57.5 wt%.

[0039] Preparation Example 1

[0040] Preparation of viscose solution a1 (using resin A)

[0041] Mix 0.1g of dibutyltin dilaurate with 10g of toluene to form a 1wt% dibutyltin dilaurate solution. Mix 1g of hexamethylene diisocyanate (HMDI), a thermal crosslinking agent, with 9g of toluene to form a 10wt% HMDI solution. Separately, mix 175.06g of Resin A solution with 103g of toluene and stir thoroughly. Then, add 0.83g of the HMDI solution (so that the NCO to OH equivalent ratio is 0.025) and 0.25g of the dibutyltin dilaurate solution. Stir for another 30 minutes to thoroughly mix until a clear, transparent mixture is obtained. This is viscose solution a1 with a solids content of 35.9wt%.

[0042] Preparation Example 2

[0043] Preparation of viscose solution a2 (using resin A)

[0044] Viscose solution a2 was prepared by the method of preparing viscose solution a1 in Preparation Example 1, wherein 1.66 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.049) to obtain viscose solution a2 with a solid content of 35.8 wt%.

[0045] Preparation Example 3

[0046] Preparation of viscose solution a3 (using resin A)

[0047] Viscose solution a3 was prepared by the method of preparing viscose solution a1 in Preparation Example 1, wherein 2.49 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.074) to obtain viscose solution a3 with a solid content of 35.7 wt%.

[0048] Preparation Example 4

[0049] Preparation of viscose solution b1 (using resin B)

[0050] Mix 0.1 g of dibutyltin dilaurate with 10 g of toluene to form a 1 wt% dibutyltin dilaurate solution. Mix 1 g of hexamethylene diisocyanate (HMDI), a thermal crosslinking agent, with 9 g of toluene to form a 10 wt% HMDI solution. Separately, mix 175.06 g of Resin B solution with 103 g of toluene and stir thoroughly. Then, add 0.83 g of the HMDI solution (so that the NCO to OH equivalent ratio is 0.024) and 0.25 g of the dibutyltin dilaurate solution. Stir for another 30 minutes to thoroughly mix and form a clear, transparent mixture. This is viscose solution b1 with a solids content of 35.9 wt%.

[0051] Preparation Example 5

[0052] Preparation of viscose solution b2 (using resin B)

[0053] Viscose solution b2 was prepared by the method of preparing viscose solution b1 in Preparation Example 4, wherein 1.78 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.052) to obtain viscose solution b2 with a solid content of 35.8 wt%.

[0054] Preparation Example 6

[0055] Preparation of viscose solution b3 (using resin B)

[0056] Viscose solution b3 was prepared by the method of preparing viscose solution b1 in Preparation Example 4, wherein 2.60 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.076) to obtain viscose solution b3 with a solid content of 35.7 wt%.

[0057] Preparation Example 7

[0058] Preparation of viscose solution c1 (using resin C)

[0059] 0.1 g of dibutyltin dilaurate was mixed with 10 g of toluene to form a 1 wt% dibutyltin dilaurate solution. 1 g of hexamethylene diisocyanate (HMDI), a thermal crosslinking agent, was mixed with 9 g of toluene to form a 10 wt% HMDI solution. 175.06 g of Resin C solution was then mixed with 103 g of toluene and thoroughly stirred. Then, 0.88 g of the HMDI solution (to achieve an NCO to OH equivalent ratio of 0.026) and 0.25 g of the dibutyltin dilaurate solution were added. The mixture was stirred for an additional 30 minutes to achieve a clear, transparent mixture. This was viscose solution C1 with a solids content of 35.9 wt%.

[0060] Preparation Example 8

[0061] Preparation of viscose solution c2 (using resin C)

[0062] Viscose solution c2 was prepared by the method of preparing viscose solution c1 in Preparation Example 7, wherein 1.70 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.050) to obtain viscose solution c2 with a solid content of 35.8 wt%.

[0063] Preparation Example 9

[0064] Preparation of viscose solution c3 (using resin C)

[0065] Viscose solution c3 was prepared by the method of preparing viscose solution c1 in Preparation Example 7, wherein 2.55 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.076) to obtain viscose solution c3 with a solid content of 35.7 wt%.

[0066] Preparation Example 10

[0067] Preparation of viscose solution d1 (using resin D)

[0068] Mix 0.1 g of dibutyltin dilaurate with 10 g of toluene to form a 1 wt% dibutyltin dilaurate solution. Mix 1 g of hexamethylene diisocyanate (HMDI), a thermal crosslinking agent, with 9 g of toluene to form a 10 wt% HMDI solution. Separately, mix 174.72 g of Resin D solution with 103 g of toluene and stir thoroughly. Then, add 4.46 g of the HMDI solution (so that the NCO to OH equivalent ratio is 0.132) and 0.25 g of the dibutyltin dilaurate solution. Stir for another 30 minutes to thoroughly mix until a clear, transparent mixture is obtained. This is viscose solution d1 with a solids content of 35.6 wt%.

[0069] Preparation Example 11

[0070] Preparation of viscose solution d2 (using resin D)

[0071] Viscose solution d2 was prepared by the method of preparing viscose solution d1 in Preparation Example 10, wherein 4.98 g of HMDI solution was added so that the equivalent ratio of NCO to OH was 0.147, to obtain viscose solution d2 with a solid content of 35.5 wt%.

[0072] Preparation Example 12

[0073] Preparation of viscose solution d3 (using resin D)

[0074] Viscose solution d3 was prepared by the method of preparing viscose solution d1 in Preparation Example 10, wherein 5.85 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.173) to obtain viscose solution d3 with a solid content of 35.4 wt%.

[0075] Preparation Example 13

[0076] Preparation of viscose solution e1 (using resin E)

[0077] Mix 0.1 g of dibutyltin dilaurate with 10 g of toluene to form a 1 wt% dibutyltin dilaurate solution. Mix 1 g of hexamethylene diisocyanate (HMDI), a thermal crosslinking agent, with 9 g of toluene to form a 10 wt% HMDI solution. Separately, mix 173.84 g of Resin E solution with 103 g of toluene and stir thoroughly. Then, add 8.06 g of the HMDI solution (so that the NCO to OH equivalent ratio is 0.309) and 0.25 g of the dibutyltin dilaurate solution. Stir for another 30 minutes to thoroughly mix until a clear, transparent mixture is obtained. This is viscose solution e1 with a solids content of 35.4 wt%.

[0078] Preparation Example 14

[0079] Preparation of viscose solution e2 (using resin E)

[0080] Viscose solution e2 was prepared by the method of preparing viscose solution e1 in Preparation Example 13, wherein 10.66 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.409) to obtain viscose solution e2 with a solid content of 35.1 wt%.

[0081] Preparation Example 15

[0082] Preparation of viscose solution e3 (using resin E)

[0083] Viscose solution e3 was prepared by the method of preparing viscose solution e1 in Preparation Example 13, wherein 12.94 g of HMDI solution was added (so that the equivalent ratio of NCO to OH was 0.496) to obtain viscose solution e3 with a solid content of 34.9 wt%.

[0084] Adhesive layer preparation, film thickness measurement, glass peeling adhesion, total transmittance, and haze testing

[0085] Test Example 1

[0086] Preparation of adhesive layer A1: Using a scraper with a gap of 560 μm and a width of 150 mm and a translation coater (ZAA2300, ZEHNTNER), the viscose solution a1 (NCO to OH equivalent ratio of 0.025) was coated on a release PET (thickness 30 μm, L130C, Nan Ya. PET: polyethylene terephthalate). The film was then placed horizontally in a 110°C oven to dry for 10 minutes, then removed and placed in a 70°C oven for aging for 18 hours, and then taken out and allowed to cool to room temperature to obtain the adhesive layer A1 containing the release PET substrate.

[0087] Average Thickness of Adhesive Layer A1: The total thickness of the adhesive layer A1 containing the release PET was measured at six points using a micrometer (MITUTOYO IP65). The average of these six points was calculated as the average total thickness. The thickness of the release PET was subtracted from the average total thickness to obtain the average thickness of the adhesive layer A1. The measurement results are shown in Table 1.

[0088] Peel Adhesion of Adhesive Layer A1 to Glass: The adhesive layer A1 containing the release PET was cut into strips 25 mm wide and 100 mm long. The strip (containing the release PET) was then rolled back and forth once with a 2 kg roller. The adhesive layer A1 was then rolled onto a primer-treated PET (25 μm thick, BP21, Nan Ya). The release PET was then removed, and the adhesive layer A1 was transferred to the primer-treated PET. The primer-treated PET was then rolled back and forth once with a 2 kg roller. The adhesive layer A1 was then rolled onto a 1.8 mm thick glass plate to form a primer-treated PET / adhesive layer A1 / glass plate combination test piece. Three sets of test pieces were prepared. These test pieces were allowed to stand at room temperature for 24 hours, and the peel adhesion of the test pieces was then measured. The results are shown in Table 1. The peel adhesion was measured according to ASTM D3330 under the following conditions: a tensile tester (QC-506B1, Guangli Instruments) was used, the angle of the primer PET substrate was pulled up to 180°, and the pulling speed was 300 mm / min.

[0089] Total transmittance and haze of adhesive layer A1: Using the aforementioned adhesive layer A1 with a release PET substrate as a test piece, the test piece was cut into 45 mm wide and 75 mm long. The release PET was rolled back and forth once with a 2 kg roller. The adhesive layer A1 was then rolled onto a 0.7 mm thick optical glass substrate. The release PET was then removed to produce a test piece for adhesive layer A1 / optical glass. Total transmittance and haze were measured according to ASTM D1003 using a haze meter (NDH 2000, Nippon Denshoku). The instrument was first calibrated with the optical glass substrate, and then the total transmittance and haze of the test piece were measured. Three measurements were taken on each test piece, and the average of these three values ​​was calculated as the average measurement for that test piece. The results are shown in Table 1.

[0090] Test Example 2

[0091] Preparation of adhesive layer A2: Adhesive layer A2 was prepared in the same manner as adhesive layer A1, wherein the viscose solution a2 (with an equivalent ratio of NCO to OH of 0.049) was coated on the release PET to obtain an adhesive layer A2 containing the release PET.

[0092] The test results of the average thickness of the adhesive layer A2, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 1.

[0093] Test Example 3

[0094] Preparation of adhesive layer A3: Adhesive layer A3 was prepared in the same manner as adhesive layer A1, wherein the viscose solution a3 (with an equivalent ratio of NCO to OH of 0.074) was coated on the release PET to obtain the release PET-containing adhesive layer A3.

[0095] The test results of the average thickness of the adhesive layer A3, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 1.

[0096] Table 1

[0097] Use Resin A Test Example 1 Test Example 2 Test Example 3 NCO / OH (equivalent ratio) 0.025 0.049 0.074 Average thickness (μm) 100.6 101.3 100.5 Average peel adhesion (gf / 25mm) 2833 2167 2033 Average total penetration (%) 99.9 99.9 99.9 Average haze (%) 0.23 0.25 0.24

[0098] Test Example 4

[0099] Preparation of adhesive layer B1: Adhesive layer B1 was prepared in the same manner as adhesive layer A1, wherein the viscose solution b1 (the equivalent ratio of NCO to OH was 0.024) was coated on the release PET to obtain the release PET-containing adhesive layer B1.

[0100] The test results of the average thickness of the adhesive layer B1, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 2.

[0101] Test Example 5

[0102] Preparation of adhesive layer B2: Adhesive layer B2 was prepared in the same manner as adhesive layer A1, wherein the viscose solution b2 (NCO to OH equivalent ratio of 0.052) was coated on the release PET to obtain a layer of adhesive B2 containing a release PET substrate.

[0103] The test results of the average thickness of the adhesive layer B2, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 2.

[0104] Test Example 6

[0105] Preparation of adhesive layer B3: The adhesive layer B3 was prepared in the same manner as the adhesive layer A1, wherein the adhesive solution b3 (NCO to OH equivalent ratio is 0.076) was coated on the release PET to obtain the adhesive layer B containing the release PET. 3 .

[0106] The test results of the average thickness of the adhesive layer B3, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 2.

[0107] Table 2

[0108] Use resin B Test Example 4 Test Example 5 Test Example 6 NCO / OH (equivalent ratio) 0.024 0.052 0.076 Average thickness (μm) 100.2 100.1 101.3 Average peel adhesion (gf / 25mm) 3100 2300 2100 Average total penetration (%) 99.9 99.9 99.9 Average haze (%) 0.24 0.26 0.26

[0109] Test Example 7

[0110] Preparation of adhesive layer C1: Adhesive layer C1 was prepared in the same manner as adhesive A1, wherein the viscose solution C1 (the equivalent ratio of NCO to OH was 0.026) was coated on the release PET to obtain the release PET-containing adhesive layer C1.

[0111] The test results of the average thickness of the adhesive layer C1, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 3.

[0112] Test Example 8

[0113] Preparation of adhesive layer C2: Adhesive layer C2 was prepared in the same manner as adhesive A1, wherein the viscose solution c2 (with an NCO to OH equivalent ratio of 0.050) was coated on the release PET to obtain an adhesive layer C2 containing the release PET.

[0114] The test results of the average thickness of the adhesive layer C2, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 3.

[0115] Test Example 9

[0116] Preparation of adhesive layer C3: Adhesive layer C3 was prepared in the same manner as adhesive A1, wherein the viscose solution c3 (with an NCO to OH equivalent ratio of 0.076) was coated on the release PET to obtain an adhesive layer C3 containing the release PET.

[0117] The test results of the average thickness of the adhesive layer C3, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 3.

[0118] Table 3

[0119] Use resin C Test Example 7 Test Example 8 Test Example 9 NCO / OH (equivalent ratio) 0.026 0.050 0.076 Average thickness (μm) 101.4 100.3 100.3 Average peel adhesion (gf / 25mm) 3367 2467 2167 Average total penetration (%) 99.9 99.9 99.9 Average haze (%) 0.23 0.25 0.24

[0120] Test Example 10

[0121] Preparation of adhesive layer D1: Adhesive layer D1 was prepared in the same manner as adhesive A1, wherein the viscose solution d1 (NCO to OH equivalent ratio of 0.132) was coated on the release PET to obtain the release PET-containing adhesive layer D1.

[0122] The test results of the average thickness of the adhesive layer D1, peel adhesion to glass, total transmittance, and haze are shown in Table 4.

[0123] Test Example 11

[0124] Preparation of adhesive layer D2: Adhesive layer D2 was prepared in the same manner as adhesive layer A1, wherein the viscose solution d2 (NCO to OH equivalent ratio of 0.147) was coated on the release PET to obtain the release PET-containing adhesive layer D2.

[0125] The test results of the average thickness of the adhesive layer D2, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 4.

[0126] Test Example 12

[0127] Preparation of adhesive layer D3: Adhesive layer D3 was prepared in the same manner as adhesive layer A1, wherein the viscose solution d3 (the equivalent ratio of NCO to OH was 0.173) was coated on the release PET to obtain the release PET-containing adhesive layer D3.

[0128] The test results of the average thickness of the adhesive layer D3, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 4.

[0129] Table 4

[0130] Use resin D Test Example 10 Test Example 11 Test Example 12 NCO / OH (equivalent ratio) 0.132 0.147 0.173 Average thickness (μm) 99.7 100.3 100.3 Average peel adhesion (gf / 25mm) 2100 1750 1550 Average total penetration (%) 99.9 99.9 99.9 Average haze (%) 0.25 0.21 0.28

[0131] Test Example 13

[0132] Preparation of adhesive layer E1: The adhesive layer E1 was prepared in the same manner as the adhesive layer A1, wherein the viscose solution e1 (the equivalent ratio of NCO to OH was 0.309) was coated on the release PET to obtain the release PET-containing adhesive layer E1.

[0133] The test results of the average thickness of the adhesive layer E1, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 5.

[0134] Test Example 14

[0135] Preparation of adhesive layer E2: Adhesive layer E2 was prepared using the same method as in Test Example 1 for preparing adhesive layer A1, wherein the viscose solution e2 (with an NCO to OH equivalent ratio of 0.409) was coated on the release PET to obtain the release PET-containing adhesive E2.

[0136] The test results of the average thickness of the adhesive layer E2, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 5.

[0137] Test Example 15

[0138] Preparation of adhesive layer E3: Adhesive layer E3 was prepared using the same method as in Test Example 1 for preparing adhesive A1, wherein the adhesive solution e3 (with an NCO to OH equivalent ratio of 0.496) was coated on the release PET to obtain the release PET-containing adhesive layer E3.

[0139] The test results of the average thickness of the adhesive layer E3, the peel adhesion to glass, the total transmittance, and the haze are shown in Table 5.

[0140] Table 5

[0141] Use resin E Test Example 13 Test Example 14 Test Example 15 NCO / OH (equivalent ratio) 0.309 0.409 0.496 Average thickness (μm) 100.5 100.1 100.4 Average peel adhesion (gf / 25mm) 1355 924 832 Average total penetration (%) 99.9 99.9 99.9 Average haze (%) 0.29 0.29 0.27

[0142] According to Test Examples 1-15, the peel adhesion of the adhesive layer disclosed herein can be maintained at at least 800 gf / 25 mm at room temperature, the total transmittance is close to complete, and the haze is less than 0.5%, which meets the requirements for assembling displays, for example, meeting the specifications of polarizers used to adhere and fix panels and display modules.

[0143] Example 1

[0144] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin A)

[0145] Using the same method as described above for making adhesive layer A1, resin A was used to prepare a set of adhesives (two adhesives in total) with different r values ​​(NCO / OH equivalent ratios). The r value of adhesive layer 1 was defined as r1 = 0.025, and the r value of adhesive layer 2 was defined as r2 = 0.074. The average thickness of each adhesive layer was measured (using the same method as described above for measuring the average thickness of adhesive layer A1). Each adhesive layer was then used to make test pieces for measuring peel adhesion. Adhesive layer 1 (r1 = 0.025) was used to test the peel adhesion to glass (a composite test piece consisting of primer PET / adhesive layer 1 / glass plate) using the same method as described in Test Example 1. Adhesive layer 2 (r2 = 0.074) was used to test the peel adhesion to polarizer using the following method: First, prepare a polarizer composite structure consisting of a protective film / polarizer / pressure-sensitive adhesive / release film, remove the protective film, and set aside. Adhesive 2 was then cut into strips 25 mm wide and 100 mm long. The strips (containing the release PET) were then rolled back and forth with a 2 kg roller. Adhesive 2 was then applied to a primer-treated PET film (25 μm thick, BP21, Nan Ya). The release PET was then removed, and Adhesive 2 was transferred to the primer-treated PET. The primer-treated PET film was then rolled back and forth with a 2 kg roller once more. Adhesive 2 was then applied to the polarizer film, from which the protective film had been removed. This resulted in three combined test strips: primer-treated PET / adhesive 2 / polarizer / pressure-sensitive adhesive / release film. These test strips were then left at room temperature for 24 hours. The two peel adhesion test strips were then placed in a -50°C freezer for 30 minutes. The peel adhesion of each test strip was then measured using the same method as described for measuring the peel adhesion of Adhesive A1 to glass. The results are shown in Table 6.

[0146] Example 2

[0147] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin A)

[0148] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.030 (Adhesive 3) and r2 = 0.061 (Adhesive 4). The thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 6.

[0149] Example 3

[0150] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin A)

[0151] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.037 (adhesive 5) and r2 = 0.072 (adhesive 6). The average thickness and peel adhesion after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 46.

[0152] Comparative Example 1

[0153] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin A)

[0154] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.046 (adhesive 7) and r2 = 0.046 (adhesive 8). The average thickness and peel adhesion after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 46.

[0155] Table 46 (using resin A)

[0156]

[0157] Example 4

[0158] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin B)

[0159] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.024 (Adhesive 9) and r2 = 0.070 (Adhesive 10). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 7.

[0160] Example 5

[0161] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin B)

[0162] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.033 (Adhesive 11) and r2 = 0.062 (Adhesive 12). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 7.

[0163] Example 6

[0164] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin B)

[0165] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.037 (Adhesive 13) and r2 = 0.072 (Adhesive 14). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 7.

[0166] Comparative Example 2

[0167] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin B)

[0168] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.062 (Adhesive 15) and r2 = 0.072 (Adhesive 16). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 7.

[0169] Table 7 (using resin B)

[0170]

[0171] Example 7

[0172] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin C)

[0173] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.026 (Adhesive 17) and r2 = 0.101 (Adhesive 18). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 8.

[0174] Example 8

[0175] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin C)

[0176] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.039 (Adhesive 19) and r2 = 0.076 (Adhesive 20). The average thickness and peel adhesion after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 8.

[0177] Example 9

[0178] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin C)

[0179] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.045 (Adhesive 21) and r2 = 0.101 (Adhesive 22). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 8.

[0180] Comparative Example 3

[0181] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin C)

[0182] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.026 (Adhesive 23) and r2 = 0.039 (Adhesive 24). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 8.

[0183] Table 8 (using resin C)

[0184]

[0185] Example 10

[0186] Freeze-peel adhesion test of adhesive layers with different r-values ​​to glass and polarizer (using resin D)

[0187] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.132 (Adhesive 25) and r2 = 0.173 (Adhesive 26). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 9.

[0188] Example 11

[0189] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin D)

[0190] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.132 (Adhesive 27) and r2 = 0.165 (Adhesive 28). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 9.

[0191] Example 12

[0192] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin D)

[0193] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.139 (Adhesive 29) and r2 = 0.173 (Adhesive 30). The average thickness and peel adhesion after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 9.

[0194] Comparative Example 4

[0195] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin D)

[0196] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.165 (Adhesive 31) and r2 = 0.173 (Adhesive 32). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 9.

[0197] Table 9 (using resin D)

[0198]

[0199] Example 13

[0200] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin E)

[0201] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.309 (Adhesive 33) and r2 = 0.496 (Adhesive 34). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 10.

[0202] Example 14

[0203] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin E)

[0204] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.309 (Adhesive 35) and r2 = 0.450 (Adhesive 36). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 10.

[0205] Example 15

[0206] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin E)

[0207] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.330 (Adhesive 37) and r2 = 0.496 (Adhesive 38). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 10.

[0208] Comparative Example 5

[0209] Freeze-peel adhesion test of adhesive layers with different r values ​​to glass and polarizer (Using Resin E)

[0210] Using the same method as in Example 1, another set of adhesives was prepared, with r values ​​of r1 = 0.496 (Adhesive 39) and r2 = 0.496 (Adhesive 40). The average thickness and peel strength after treatment at -50°C for 30 minutes were measured. The measurement results are shown in Table 10.

[0211] Table 10 (resin E used)

[0212]

[0213] According to Embodiments 1 to 15, in the present disclosure, adhesives layers with different NCO / OH equivalent ratios (r values) are made from Resins A, B, C, D, and E respectively, and then the adhesive layers are respectively made into peel adhesion measurement test pieces. For example, in each embodiment, one adhesive layer (r = r1) is used to make a peel adhesion measurement test piece for glass, and at the same time, another adhesive layer (r = r2) is used to make a peel adhesion measurement test piece for a polarizer. The r1 value and the r2 value satisfy r1 < r2 ≤ 0.8 and r2 - r1 ≥ 0.025. After the two test pieces are subjected to low-temperature freezing treatment, it can be found that the peel adhesion of the adhesive (r = r1) in the present disclosure to glass can reach more than 210 gf / 25 mm, while the peel adhesion of the adhesive (r = r2) in the present disclosure to the polarizer is at most only 80 gf / 25 mm. That is, after the two-sided adhesives of the present disclosure are subjected to low-temperature freezing treatment, the peel adhesion of the first adhesive (r = r1) to glass and the peel adhesion of the second adhesive (r = r2) to the polarizer are different, and the peel adhesion of the first adhesive (r = r1) to glass is significantly greater than the peel adhesion of the second adhesive (r = r2) to the polarizer, indicating that the two adhesives can be combined to form a freeze-peelable double-sided adhesive. Moreover, when the double-sided adhesive adheres to glass and the polarizer respectively, and then after freezing and peeling the substrate, the double-sided adhesive will only leave residual glue on the glass.

[0214] Embodiment 16

[0215] Processability test of multilayer structure (using resin A)

[0216] Manufacturing a double-sided adhesive: Using Resin A and by the method of Embodiment 1, adhesives with different r values are made. The first adhesive (r1 = 0.025) is made on a heavy-release PET substrate (thickness 50 μm, L150A, Nan Ya), and the second adhesive (r2 = 0.074) is made on a light-release PET substrate (thickness 30 μm, L130C, Nan Ya). Then, a 2-kg heavy rolling roller is used to roll back and forth to laminate the first adhesive and the second adhesive together to form a double-sided adhesive of heavy-release PET / first adhesive / second adhesive / light-release PET. Measure the average thickness of the double-sided adhesive (in the same method as measuring the average thickness of Adhesive A1 mentioned above), and then make test pieces for measuring processability and peel adhesion of a multi-layer structure.

[0217] Preparation of test pieces for measuring processability and freeze-peel adhesion strength (after 30 minutes at -50°C): Prepare a polarizer composite consisting of a protective film / polarizer / pressure-sensitive adhesive / release film. Remove the protective film and set aside. Cut the double-sided tape into strips 45mm wide and 75mm long. Remove the light release PET strip from the strip. Use a 2kg roller to roll the heavy release PET strip back and forth once. Apply the double-sided tape to the polarizer (from which the protective film has been removed). Remove the heavy release PET strip from the double-sided tape. Use a 2kg roller to roll the release film of the polarizer composite back and forth. Apply the double-sided tape to a 1.8mm-thick glass plate to create a multilayer test piece consisting of glass plate / first adhesive (first surface adhesive) / second adhesive (second surface adhesive) / polarizer / pressure-sensitive adhesive / release film. The multilayer structure test piece was placed in a -50°C freezer for 30 minutes. The average peel adhesion was then tested (using the same method as described above for measuring the peel adhesion of adhesive A1 to glass). The double-sided tape residue was also checked. The test results are shown in Table 11.

[0218] Example 17

[0219] Processability test of multilayer structure (using resin A)

[0220] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.030 and r2 = 0.061, respectively. The test results are shown in Table 11.

[0221] Example 18

[0222] Processability test of multilayer structure (using resin A)

[0223] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.037 and r2 = 0.072, respectively. The test results are shown in Table 11.

[0224] Comparative Example 6

[0225] Processability test of multilayer double-sided tape (using resin A)

[0226] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.046 and r2 = 0.046, respectively. The test results are shown in Table 11.

[0227] Table 11

[0228]

[0229] Example 19

[0230] Processability Test of Multilayer Structure (Using Resin B)

[0231] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.024 and r2 = 0.070, respectively. The test results are shown in Table 12.

[0232] Example 20

[0233] Processability Test of Multilayer Structure (Using Resin B)

[0234] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.033 and r2 = 0.062, respectively. The test results are shown in Table 12.

[0235] Example 21

[0236] Processability Test of Multilayer Structure (Using Resin B)

[0237] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.037 and r2 = 0.072, respectively. The test results are shown in Table 12.

[0238] Comparative Example 7

[0239] Processability Test of Multilayer Structure (Using Resin B)

[0240] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.062 and r2 = 0.072, respectively. The test results are shown in Table 12.

[0241] Table 812

[0242]

[0243] Example 22

[0244] Processability Test of Multilayer Structure (Using Resin C)

[0245] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.026 and r2 = 0.101, respectively. The test results are shown in Table 13.

[0246] Example 23

[0247] Processability Test of Multilayer Structure (Using Resin C)

[0248] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.039 and r2 = 0.076, respectively. The test results are shown in Table 13.

[0249] Example 24

[0250] Processability Test of Multilayer Structure (Using Resin C)

[0251] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.045 and r2 = 0.101, respectively. The test results are shown in Table 13.

[0252] Comparative Example 8

[0253] Processability Test of Multilayer Structure (Using Resin C)

[0254] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.026 and r2 = 0.039, respectively. The test results are shown in Table 13.

[0255] Table 13

[0256]

[0257] Example 25

[0258] Processability Test of Multilayer Structure (Using Resin D)

[0259] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.132 and r2 = 0.173, respectively. The test results are shown in Table 14.

[0260] Example 26

[0261] Processability Test of Multilayer Structure (Using Resin D)

[0262] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.132 and r2 = 0.165, respectively. The test results are shown in Table 14.

[0263] Example 27

[0264] Processability Test of Multilayer Structure (Using Resin D)

[0265] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.139 and r2 = 0.173, respectively. The test results are shown in Table 14.

[0266] Comparative Example 9

[0267] Processability Test of Multilayer Structure (Using Resin D)

[0268] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.165 and r2 = 0.173, respectively. The test results are shown in Table 14.

[0269] Table 14

[0270]

[0271] Example 28

[0272] Processability Test of Multilayer Structure (Using Resin E)

[0273] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.309 and r2 = 0.496, respectively. The test results are shown in Table 15.

[0274] Example 29

[0275] Processability Test of Multilayer Structure (Using Resin E)

[0276] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.309 and r2 = 0.450, respectively. The test results are shown in Table 15.

[0277] Example 30

[0278] Processability Test of Multilayer Structure (Using Resin E)

[0279] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.330 and r2 = 0.496, respectively. The test results are shown in Table 15.

[0280] Comparative Example 10

[0281] Processability Test of Multilayer Structure (Using Resin E)

[0282] The preparation and testing methods of double-sided adhesive tape and multilayer structure test pieces were the same as those in Example 16. The r values ​​of the first adhesive sheet and the second adhesive sheet were r1 = 0.496 and r2 = 0.496, respectively. The test results are shown in Table 15.

[0283] Table 15

[0284]

[0285] According to Embodiments 16 to 30, the present disclosure uses Resins A, B, C, D, and E to make double-sided adhesives respectively, and the two adhesive layers on both sides of the double-sided adhesive have different NCO / OH equivalent ratios (r values). For example, in each embodiment, an adhesive with r value = r1 is made, and at the same time, another adhesive with r value = r2 is made. Then, the two adhesives are pasted together to form a double-sided adhesive, such that the r value difference satisfies r1 < r2 ≤ 0.8 and r2 - r1 ≥ 0.025. Then, the double-sided adhesive is used to bond glass and a polarizer, where the adhesive with r value = r1 contacts the glass and the adhesive with r value = r2 contacts the polarizer. After cryogenic freezing treatment and then peeling the glass and the polarizer, it can be found that the double-sided adhesive of the present disclosure only remains on the glass and does not remain on the polarizer. Since the r value differences between the two adhesive layers on both sides of the double-sided adhesives in Comparative Examples 6 to 10 are all less than 0.025, when the glass and the polarizer are peeled, it can be found that the double-sided adhesive remains on both the glass and the polarizer. The above results show that after the double-sided adhesive of the present disclosure bonds the glass and the polarizer, the glass and the polarizer can be easily peeled by freezing treatment, and the double-sided adhesive only leaves residual glue on the glass. Therefore, the double-sided adhesive of the present disclosure is suitable for application in the processing technology of panels, which can simplify the existing processing technology and significantly shorten the processing time.

[0286] Example 31

[0287] Processability testing of multilayer structures (using different resins)

[0288] Select the adhesive containing Resin A with r1 = 0.025 as the first adhesive, with an average thickness of 75.6 μm (its average peel adhesion to glass after being treated at -50°C for 30 minutes is 270 gf / 25 mm, as shown in Table 6, Example 1); select the adhesive containing Resin B with r2 = 0.070 as the second adhesive, with an average thickness of 75.3 μm (its average peel adhesion to the polarizer after being treated at -�0°C for 30 minutes is 60 gf / 25 mm, as shown in Table 7, Example 4). Paste the two adhesives together (using the same method as in Example 16 for making the double-sided adhesive) to form a double-sided adhesive, then measure the average thickness of the double-sided adhesive (using the same method as前述 for measuring the average thickness of Adhesive A1), and then make it into a multi-layer structure to test the processing performance and average peel adhesion of the double-sided adhesive after being treated at -50°C for 30 minutes (the method is the same as in Example 16). The measurement results are shown in Table 16.

[0289] Example 32

[0290] Processability testing of multilayer structures (using different resins) <​Select the adhesive containing Resin A with r1 = 0.030 as the first adhesive. Its average thickness is 75.8 μm (its average peel adhesion to glass after being treated at -50°C for 30 minutes is 263 gf / 25 mm, as shown in Table 6, Example 2); select the adhesive containing Resin B with r2 = 0.062 as the second adhesive. Its average thickness is 74.2 μm (its average peel adhesion to the polarizer after being treated at -50°C for 30 minutes is 80 gf / 25 mm, as shown in Table 7, Example 5). Stick the two adhesives together (using the same method as in Example 16 for making double-sided tape) to make a double-sided tape. Then measure the average thickness of the double-sided tape (using the same method as前述 for measuring the average thickness of Adhesive A12). Then make it into a multi-layer structure as a test piece for the processability and average peel adhesion of the double-sided tape after being treated at -50°C for 30 minutes (the method is the same as in Example 16). The measurement results are shown in Table 16.

[0292] Table 16

[0293]

[0294] According to Examples 31 and 32, in this disclosure, double-sided tapes are made of Resin A and B, and the two adhesive layers on both sides of the double-sided tape have different NCO / OH equivalent ratios (r values). For example, in each example, make an adhesive with r value = r1 and containing Resin A, and at the same time make another adhesive with r value = r2 and containing Resin B. Stick the two adhesives together so that the r value difference meets r1 < r2 ≦ 0.8, r2 – r1 ≧ 0.025. Then use the double-sided tape to adhere the glass and the polarizer. Among them, the adhesive with r value = r1 and containing Resin A contacts the glass, and the adhesive with r value = r2 and containing Resin B contacts the polarizer. After the low-temperature freezing treatment and then peeling off the glass and the polarizer, it can be found that the double-sided tapes containing different resins in this disclosure also only remain on the glass and will not remain on the polarizer. The above results can show that after using the double-sided tapes with different resins to adhere the glass and the polarizer in this disclosure, the glass and the polarizer can be easily peeled off through the freezing treatment, and the double-sided tape will only leave residual glue on the glass. Therefore, the double-sided tapes in this disclosure are suitable for application in the processing technology of the panel, which can simplify the existing processing technology and greatly shorten the processing time.

[0295]

Symbol Explanation

[0296] 10: Multi-layer structure

[0297] 12: First substrate

[0298] 14: Second substrate

[0299] 16: Double-sided tape

[0300] 16a: First surface of the double-sided tape

[0301] 16b: Second surface of the double-sided tape

Claims

1. A double-sided tape comprising: a first adhesive layer comprising a first resin and a first thermal crosslinking agent, wherein the first resin comprises a hydroxyl group (OH), the first thermal crosslinking agent comprises a first group reactive with the hydroxyl group of the first resin, and a ratio of the number of equivalents of the first group of the first thermal crosslinking agent to the number of equivalents of the hydroxyl group of the first resin is represented by r1; and The second adhesive layer includes a second resin and a second thermal crosslinking agent, wherein the second resin includes a hydroxyl group (OH), the second thermal crosslinking agent includes a second group that can react with the hydroxyl group of the second resin, and the ratio of the equivalent number of the second group of the second thermal crosslinking agent to the equivalent number of the hydroxyl group of the second resin is represented by r2. where r1 <r2≦0.8,r2–r1≧0.025, The monomer composition of the first resin and the second resin includes a hydroxyl-containing monomer, a hydrophilic monomer without a hydroxyl group, and an alkyl (meth)acrylate monomer, wherein the carbon number of the alkyl group in the alkyl (meth)acrylate monomer is greater than or equal to 3 and less than or equal to 12, wherein the hydroxyl-containing monomer has 1 to 10 parts by weight, the hydrophilic monomer without a hydroxyl group has 1 to 20 parts by weight, and the alkyl (meth)acrylate monomer has 75 to 95 parts by weight, based on 100 parts by weight of the total weight of the monomers. The first group and the second group include an isocyanate group, a carboxyl group, an aziridine group, an anhydride group, or a melamine group.

2. The double-sided tape according to claim 1, wherein the hydroxyl-containing monomer comprises hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, or hydroxybutyl (meth) acrylate.

3. The double-sided tape according to claim 1, wherein the hydrophilic monomer containing no hydroxyl group comprises acrylonitrile, acrylamide, acryloyl morpholine, or N-vinyl-2-pyrrolidone. The double-sided tape according to claim 1 , wherein the first resin and the second resin have the same monomer composition. The double-sided tape according to claim 1 , wherein the first resin and the second resin have different monomer compositions.

6. A multilayer structure comprising: a first substrate; a second substrate; as well as The double-sided tape as claimed in claim 1, wherein the first adhesive layer has a first surface, the second adhesive layer has a second surface, the first surface contacts the first substrate, and the second surface contacts the second substrate. The multi-layer structure of claim 6 , wherein the first substrate comprises a panel. 8 . The multi-layer structure according to claim 7 , wherein the panel comprises transparent glass or a transparent substrate, and comprises a transparent conductive electrode on at least one surface of the transparent glass or the transparent substrate.

9. The multilayer structure of claim 6, wherein the second substrate comprises a polarizer.

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