(meth) acrylate polymers having siloxy groups

Abstract

A (meth) acrylate polymer having a siloxy group has a weight-average molecular weight of 5500 to 78500, and is formed by a polymerization reaction of a reaction composition. The reaction composition comprises acrylic ester as shown in a formula (I) and a silane compound as shown in a formula (II). When the (methyl) acrylate polymer with the siloxy group is applied to the pressure-sensitive adhesive, an adhesive body formed by the pressure-sensitive adhesive has the advantages of reworking property and no bubbles, and also has the characteristic of no stripping and bubbling after thermal cycling. # imgabs0 # in formula (I), X1 represents hydrogen or a methyl group and X2 represents an alkyl group of C1 to C10, (X3) nSi (X4) 4-n formula (II) in formula (II), X3 represents an alkoxy group of C1 to C3, X4 represents an epoxy group, an acryloyloxy group, a thiol group or an amino group, and n represents 1 to 3.

Description

Technical Field

[0001] The present invention relates to a (meth)acrylate polymer in a pressure-sensitive adhesive, and particularly to a (meth)acrylate polymer having a siloxy group. Background Art

[0002] In recent years, compared with glass materials, plastic materials such as polymethyl methacrylate or polycarbonate have been widely used in optical laminates such as display panels due to their characteristics such as light weight, low cost, and safety.

[0003] Generally, the optical laminate includes a plurality of optical members (such as a polarizing plate, a light guide plate, or a touch substrate in a touch panel) made of the above-mentioned plastic materials, and an adhesive layer that bonds the optical members together and is formed of an optically transparent adhesive (such as a pressure-sensitive adhesive). Compared with glass materials, the water content of plastic materials is often relatively high, so that the optical members of the optical laminate are likely to release moisture under high-temperature use environments or high-temperature process conditions, resulting in bubbles at the bonding interface between the adhesive layer and the optical members, thereby causing the adhesive layer to peel off from the optical members. Or, due to the large difference in the thermal expansion coefficients between the adhesive layer and the optical members, the adhesive layer peels off from the optical members and other problems occur in the optical laminate under alternating hot and cold use environments or process conditions.

[0004] To solve the above problems, Taiwan Patent Publication No. 509046 discloses a pressure-sensitive adhesive composition containing 100 parts by weight of an acrylic polymer (A), 1 to 50 parts by weight of an acrylic polymer (B), an initiator (C), a crosslinking agent (D), and a chain transfer agent (E).

[0005] The acrylic polymer (A) is formed by a polymerization reaction of a first reaction composition, and the first reaction composition includes 30 wt% to 80 wt% of an alkyl (meth)acrylate having an alkyl group, 15 wt% to 35 wt% of a monomer having a hydroxyl group, and 3 wt% to 25 wt% of a monomer having a nitrogen. The weight-average molecular weight of the acrylic polymer (A) is 100,000 to 3,000,000. The acrylic polymer (B) is formed by a polymerization reaction of a second reaction composition, and the second reaction composition includes 20 wt% to 80 wt% of an alkyl (meth)acrylate having an alkyl group and 20 wt% to 80 wt% of a (meth)acrylate having a crosslinked hydrocarbon ring structure with three or more rings in the molecule. The weight-average molecular weight of the acrylic polymer (B) is 1,000 to 30,000.

[0006] Although, through the design of the acrylic polymer (B), the adhesive layer formed from the pressure-sensitive adhesive composition containing the acrylic polymer (B) has the advantages of resisting blistering and peeling at high temperatures and resisting cloudiness at high temperatures and high humidity, the initial adhesion of the adhesive layer is high and it does not have reworkability, and after undergoing thermal cycling, the adhesive layer is prone to peeling and there are bubbles. Summary of the Invention

[0007] An object of the present invention is to provide a (meth)acrylate polymer having a siloxy group.

[0008] The (meth)acrylate polymer having a siloxy group of the present invention has a weight-average molecular weight of 5,500 to 78,500 and is formed by a polymerization reaction of a reaction composition, and the reaction composition includes an acrylate represented by formula (I) and a silane compound represented by formula (II).

[0009]

[0010] In formula (I), X 1 represents hydrogen or methyl and X 2 represents an alkyl group having 1 to 10 carbon atoms,

[0011] (X 3 ) n Si(X 4 ) 4-n Formula (II)

[0012] In formula (II), X 3 represents an alkoxy group having 1 to 3 carbon atoms, X 4 represents an epoxy group, an acryloyloxy group, a thiol group or an amino group, and n represents 1 to 3.

[0013] For the (meth)acrylate polymer having a siloxy group of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by formula (II) is 1 wt% to 10 wt%.

[0014] For the (meth)acrylate polymer having a siloxy group of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by formula (II) is 1 wt% to 5 wt%.

[0015] For the (meth)acrylate polymer having a siloxy group of the present invention, the acryloyloxy group is Y 1 represents an alkylene group having 1 to 4 carbon atoms, and Y 2 represents hydrogen or methyl.

[0016] The (meth)acrylate polymer having a siloxy group of the present invention, the silane compound represented by the formula (II) is selected from (3-glycidyloxypropyl)methyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, (N-(2-aminoethyl)-3-amino)propyltrimethoxysilane, or any combination thereof.

[0017] The (meth)acrylate polymer having a siloxy group of the present invention, the reaction composition further includes an acrylamide compound represented by the formula (III),

[0018]

[0019] In the formula (III), X 5 and X 6 independently represent hydrogen or methyl.

[0020] The (meth)acrylate polymer having a siloxy group of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by the formula (III) is greater than 0 wt% and 20 wt% or less.

[0021] The (meth)acrylate polymer having a siloxy group of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by the formula (III) is 10 wt% to 20 wt%.

[0022] The (meth)acrylate polymer having a siloxy group of the present invention, the (meth)acrylate polymer having a siloxy group has a glass transition temperature of greater than 70 °C.

[0023] The (meth)acrylate polymer having a siloxy group of the present invention, the acrylate represented by the formula (I) is selected from methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, or any combination thereof.

[0024] The beneficial effects of the present invention are as follows: By introducing the silane compound represented by the formula (II) into the (meth)acrylate polymer having a siloxy group, when the (meth)acrylate polymer having a siloxy group is applied to a pressure-sensitive adhesive, it can endow the adhesive body formed by the pressure-sensitive adhesive with a low initial adhesion and the ability to be peeled off, thereby endowing the adhesive body with reworkability, and the adhesive body has an excellent water vapor penetration rate, which can reduce the generation of bubbles due to water vapor accumulation and the occurrence of white fog phenomenon in the adhesive body. At the same time, during the process of the adhesive body experiencing thermal cycling, the adhesive body can release the stress generated by the alternating heat and cold, so that the adhesive body is still firmly set and will not peel off, and the adhesive body can still release water vapor without bubbles. Detailed Description

[0025] The present invention will be described in detail below.

[0026] The present invention provides a (meth)acrylate polymer having a siloxy group, with a weight-average molecular weight of 5,500 to 78,500, and is formed by polymerization of a reaction composition, and the reaction composition includes an acrylate represented by formula (I) and a silane compound represented by formula (II).

[0027]

[0028] In formula (I), X 1 represents hydrogen or methyl and X 2 represents an alkyl group having 1 to 10 carbon atoms.

[0029] (X 3 ) n Si(X 4 ) 4-n Formula (II)

[0030] In formula (II), X 3 represents an alkoxy group having 1 to 3 carbon atoms, X 4 represents an epoxy group, an acryloyloxy group, a thiol group or an amino group, and n represents 1 to 3.

[0031] In some embodiments of the present invention, the (meth)acrylate polymer having a siloxy group has a weight-average molecular weight of 8,000 to 51,000. In some embodiments of the present invention, the (meth)acrylate polymer having a siloxy group has a glass transition temperature of 70 °C or higher. In some embodiments of the present invention, the (meth)acrylate polymer having a siloxy group has a glass transition temperature of 70 °C to 120 °C. In some embodiments of the present invention, the (meth)acrylate polymer having a siloxy group has a glass transition temperature of 90 °C to 120 °C.

[0032] [The acrylate represented by formula (I)]

[0033] In formula (I), the alkyl group having 1 to 10 carbon atoms is, for example, a straight-chain alkyl group having 1 to 10 carbon atoms, a branched-chain alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 1 to 10 carbon atoms. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the acrylate represented by formula (I) is the balance to adjust the total amount of the reaction composition to 100 wt%.

[0034] The acrylate represented by the formula (I) can be used alone or in combination of multiple types. In some embodiments of the present invention, the acrylate represented by the formula (I) is, for example but not limited to, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, or isobornyl methacrylate, etc.

[0035] [Silane compound represented by formula (II)]

[0036] The silane compound represented by the formula (II) reacts with the acrylate represented by the formula (I) through the epoxy group of the epoxy group, the acryloyloxy group of the acryloyloxy group, the thiol group of the thiol group, or the amino group of the amino group.

[0037] In formula (II), the epoxy group is, for example, (glycidoxy)alkylene.

[0038] In formula (II), the acryloyloxy group is, for example Y 1 represents C1-C4 alkylene, and Y 2 represents hydrogen or methyl. In Y of formula (II) 1 , the C1-C4 alkylene is, for example, a C1-C4 straight-chain alkylene or a C1-C4 branched-chain alkylene, etc.

[0039] In formula (II), the thiol group is, for example, -Y 3 -SH, and Y 3 represents C1-C4 alkylene. In Y of formula (II) 3 , the C1-C4 alkylene is, for example, a C1-C4 straight-chain alkylene or a C1-C4 branched-chain alkylene, etc.

[0040] In formula (II), the amino group is, for example, (N-(aminoalkylene)-amino)alkylene.

[0041] In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by the formula (II) is 1 wt% to 10 wt%. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by the formula (II) is 1 wt% to 5 wt%. The silane compound represented by the formula (II) can be used alone or in combination of multiple types. In some embodiments of the present invention, the silane compound represented by the formula (II) is, for example but not limited to, (3-glycidoxypropyl)methyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, or (N-(2-aminoethyl)-3-amino)propyltrimethoxysilane, etc.

[0042] [Acrylamide compound represented by formula (III)]

[0043] In some embodiments of the present invention, the reaction composition further comprises an acrylamide compound represented by formula (III),

[0044]

[0045] In formula (III), X 5 and X 6 each independently represents hydrogen or methyl.

[0046] In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by formula (III) is greater than 0 wt% and 20 wt% or less. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by formula (III) is 10 wt% to 20 wt%. The acrylamide compound represented by formula (III) can be used alone or in combination of multiple kinds. In some embodiments of the present invention, the acrylamide compound represented by formula (III) is, for example but not limited to, N,N-dimethylacrylamide.

[0047] [Thermal initiator]

[0048] In some embodiments of the present invention, the reaction composition further comprises a thermal initiator. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the thermal initiator is 0.1 wt% to 2 wt%. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the thermal initiator is 0.1 wt% to 1 wt%. In some embodiments of the present invention, the thermal initiator is, for example but not limited to, a thermal initiator for free radical polymerization. The thermal initiator for free radical polymerization is, for example but not limited to, a peroxide or an azo compound, etc. The peroxide is, for example but not limited to, benzoyl peroxide, tert-butyl peroxide, tert-amyl peroxybenzoate, 2,2-bis(tert-butylperoxy)butane or 2,4-pentanedione peroxide. The azo compound is, for example but not limited to, azobisisobutyronitrile or azobisisoheptonitrile, etc.

[0049] [Chain transfer agent]

[0050] In some embodiments of the present invention, the reaction composition further includes a chain transfer agent. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the chain transfer agent is 1 wt% to 5 wt%. In some embodiments of the present invention, based on the total amount of the reaction composition being 100 wt%, the content of the chain transfer agent is 2 wt% to 3 wt%. In some embodiments of the present invention, the chain transfer agent is, for example but not limited to, 2-mercaptoethanol or (3-mercaptopropyl)triethoxysilane, etc.

[0051] The present invention will be further described with reference to the following examples. However, it should be understood that the examples are for illustrative purposes only and should not be construed as limitations on the implementation of the present invention.

[0052] Preparation Example 1 (Meth)acrylate Polymer

[0053] 50 parts by weight of butyl acrylate, 10 parts by weight of tert-butyl acrylate, 25 parts by weight of (4-hydroxy)butyl acrylate, 5 parts by weight of tetrahydrofurfuryl acrylate, 10 parts by weight of N-vinylpyrrolidone, and 0.01 part by weight of 1-hydroxycyclohexyl phenyl ketone (model: Irgacure 184) were mixed for 30 minutes under a nitrogen atmosphere and at a temperature of 27.5 ± 7.5 °C to form a mixture. Then, the mixture was irradiated with ultraviolet light having a wavelength of 365 nm for 5 minutes to obtain a (meth)acrylate polymer with a viscosity of 2000 cp.

[0054] Preparation Examples 2 to 4

[0055] The preparation methods of Preparation Examples 2 to 4 are generally similar to that of Preparation Example 1, except that the types and amounts of the components are changed as shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] Example 1

[0060] Mix 30 parts by weight of methyl methacrylate, 55 parts by weight of isobornyl methacrylate, 4 parts by weight of 3-acryloxypropyltrimethoxysilane (model: KBM503), and 11 parts by weight of N,N-dimethylacrylamide. Then, add ethyl acetate (as a solvent) to form a first component with a solid content of 50 wt%. Next, mix the first component in a nitrogen environment at 65 °C for 30 minutes to form a second component. Then, add 2 parts by weight of 2-mercaptoethanol and 0.6 parts by weight of azobisisobutyronitrile. Next, react under nitrogen environment at 65 °C for 3 hours to form a third component. Then, adjust the temperature to 75 °C and react the third component at 75 °C for 12 hours to obtain a solution containing a (meth)acrylate polymer having a siloxy group. Then, perform a drying treatment to obtain the (meth)acrylate polymer having a siloxy group.

[0061] Examples 2 to 3 and Comparative Examples 1 to 5

[0062] The preparation methods of Examples 2 to 3 and Comparative Examples 1 to 5 are generally similar to those of Example 1, except that the types and amounts of the components are changed, as shown in Table 2.

[0063] Table 2

[0064]

[0065]

[0066]

[0067] Application Example 1 Pressure-sensitive Adhesive

[0068] Mix 95 parts by weight of the (meth)acrylate polymer of Preparation Example 1 with 5 parts by weight of the (meth)acrylate polymer having a siloxy group of Example 3. Then, add 0.12 parts by weight of 1,6-hexanediol diacrylate and 0.14 parts by weight of dimethylbenzyl benzoin ether (model: Irgacure 651) to obtain a transparent and clear pressure-sensitive adhesive.

[0069] Application Examples 2 to 4 and Comparative Application Examples 1 to 7

[0070] The preparation methods of Application Examples 2 to 4 and Comparative Application Examples 1 to 7 are generally similar to those of Application Example 1, except that the types and amounts of the components are changed, as shown in Tables 3 and 4.

[0071] Evaluation Items

[0072] Perform the following tests on the pressure-sensitive adhesives of Application Examples 1 to 4 and Comparative Application Examples 1 to 7. For the sake of clarity, the test procedures for the following test items are described taking the pressure-sensitive adhesive of Application Example 1 as a representative.

[0073] Peeling resistance measurement: The pressure-sensitive adhesive of Application Example 1 was subjected to the following measurement process. Using a doctor blade, the pressure-sensitive adhesive of Application Example 1 was coated on the surfaces of two release films, then they were laminated together, and then irradiated with ultraviolet light having a wavelength of 365 nm until the cumulative irradiation energy reached 2500 ± 500 mJ / cm 2 At this time, the irradiation was stopped to obtain an adhesive layer with a film thickness of 250 μm and a size of 20 cm × 30 cm located between the release films, and then the adhesive layer was peeled off from the release films and obtained. Then, using a rubber roller, the adhesive layer was pasted between a transparent polycarbonate plate and a glass plate to form a transparent laminate. Among them, the thickness of the polycarbonate plate was 375 μm and the size was 8 cm × 8 cm, and the thickness of the glass plate was 1.1 mm and the size was 8 cm × 8 cm. Then, the three transparent laminates were placed in a pressure and degassing machine and subjected to a pressure and degassing treatment at 50 °C and a load of 5 kg for 20 minutes, and then placed in a thermal shock tester for thermal cycling tests. In this thermal cycling test, the temperature was raised from 25 °C to 80 °C, and then the temperature was lowered from 80 °C to 25 °C, and this was repeated three times. Then, the transparent laminates were taken out from the thermal shock tester, and the number of bubbles in the transparent laminates was counted visually and averaged, and the peeling area was calculated based on the bubble size in the transparent laminates and averaged.

[0074] Redoability measurement: Using a doctor blade, the pressure-sensitive adhesive of Application Example 1 was coated on the surfaces of two release films, then they were laminated together, and then irradiated with ultraviolet light having a wavelength of 365 nm until the cumulative irradiation energy reached 2500 ± 500 mJ / cm 2 At this time, the irradiation was stopped to obtain an adhesive layer with a film thickness of 250 μm and a size of 20 cm × 30 cm located between the release films, and then the adhesive layer was peeled off from the release films and obtained. The adhesive layer was cut into test pieces with a size of 50 mm × 2.5 mm, and using a rubber roller, the test pieces were pasted on the surface of a horizontally placed and position-fixed polyethylene terephthalate film. After 5 minutes, the test pieces were slowly peeled off from the surface of the polyethylene terephthalate film along the 90-degree direction of the surface of the polyethylene terephthalate film, and visually observed whether there was residual adhesive on the surface of the polyethylene terephthalate film, and the area of the residual adhesive on the surface of the polyethylene terephthalate film was recorded.

[0075] Initial tack (unit: gf / cm 2Measurement: Refer to the standard test method for pressure-sensitive tack of adhesives using an inverted probe machine in ASTM D2979 (2009 edition). Using a scraper, apply the pressure-sensitive adhesive of Application Example 1 on the surfaces of two release films, then laminate them together. Next, irradiate with ultraviolet light with a wavelength of 365 nm until the cumulative irradiation energy reaches 2500 ± 500 mJ / cm 2 At this time, stop irradiation to obtain an adhesive layer with a film thickness of 250 μm and a size of 20 cm × 30 cm between the release films, and then peel and obtain this adhesive layer from the release films. Cut this adhesive layer into test pieces with a size of 25 mm × 25 mm. Measure this test piece using a probe-type initial tack tester (manufacturer: Yixin Instrument Co., Ltd.; model: YST36C). Paste this test piece on the aluminum alloy test piece holder of the probe-type initial tack tester, and make the probe (with a diameter of 5 mm) of the probe-type initial tack tester contact the adhesive layer of the test piece to be tested for 3 seconds. Then, pull the aluminum alloy test piece holder upward at a speed of 5 mm / s to separate the probe from the adhesive layer, and record the value measured when the probe separates from the adhesive layer, and this value is the initial tack force.

[0076] Measurement of foam resistance: Perform the following measurement process on three pressure-sensitive adhesives of Application Example 1. Using a scraper, apply the pressure-sensitive adhesive of Example 1 on the surfaces of two release films, then laminate them together. Next, irradiate with ultraviolet light with a wavelength of 365 nm until the cumulative irradiation energy reaches 2500 ± 500 mJ / cm 2 At this time, stop irradiation to obtain an adhesive layer with a film thickness of 250 μm between the release films, and then peel and obtain this adhesive layer from the release films. Next, use a rubber roller to paste this adhesive layer between two transparent polycarbonate plates to form a transparent laminate, where the thickness of the transparent polycarbonate plate is 375 μm and the size is 8 cm × 8 cm. Then, place these three transparent laminates into a pressure and defoaming machine and perform a pressure and defoaming treatment for 20 minutes under the conditions of 50 °C and a load of 5 kg. Next, place them in an oven with a temperature set at 80 °C for a drying treatment for 2 hours. Then, take out the transparent laminate from the oven and visually observe and count the number of bubbles in the transparent laminate and take the average value.

[0077] Water vapor transmission rate (unit: g / m 2· Measurement of water vapor transmission rate (WVTR) (g / m²·24h): Conducted in accordance with the test method for measuring the water vapor transmission rate of moisture-proof packaging materials specified in JIS Z 0208 (1976 edition). Using a spatula, apply the pressure-sensitive adhesive of Application Example 1 to the surfaces of two release films, then laminate them together. Subsequently, irradiate with ultraviolet light having a wavelength of 365 nm until the cumulative irradiation energy reaches 2500 ± 500 mJ / cm² 2 at which point, stop the irradiation to obtain an adhesive layer with a film thickness of 250 μm located between the release films. Then, peel and obtain this adhesive layer from the release films. Next, attach this adhesive layer to a gauze to obtain a test piece. Then, tightly cover the mouth (opening area A is 0.0029 m²) of a moisture-permeable cup containing calcium chloride with the adhesive layer of this test piece to obtain a test sample. Place this test sample in a thermo-hygrostat aging tester and leave it to stand for 1 hour in an environment with a temperature of 40 °C and a relative humidity of 90%. After the water vapor reaches equilibrium, take out this test sample and weigh it to obtain a weight value of W0. Then, put this test sample back into the thermo-hygrostat aging tester and leave it to stand for 24 hours in an environment with a temperature of 40 °C and a relative humidity of 90%. Then, take out this test sample and weigh it to obtain a weight value of W1. Next, substitute the weight values into the following formula to calculate the water vapor transmission rate. 2 ) to obtain a test sample. Place this test sample in a thermo-hygrostat aging tester and leave it to stand for 1 hour in an environment with a temperature of 40 °C and a relative humidity of 90%. After the water vapor reaches equilibrium, take out this test sample and weigh it to obtain a weight value of W0. Then, put this test sample back into the thermo-hygrostat aging tester and leave it to stand for 24 hours in an environment with a temperature of 40 °C and a relative humidity of 90%. Then, take out this test sample and weigh it to obtain a weight value of W1. Next, substitute the weight values into the following formula to calculate the water vapor transmission rate.

[0078] Water vapor transmission rate (g / m²·24h) = (W1 - W0) / A 2 ·24h) = (W1 - W0) / A

[0079] Measurement of storage modulus (G’, unit: Pa): Using a spatula, apply the pressure-sensitive adhesive of Application Example 1 to the surfaces of two release films, then laminate them together. Subsequently, irradiate with ultraviolet light having a wavelength of 365 nm until the cumulative irradiation energy reaches 2500 ± 500 mJ / cm² 2 at which point, stop the irradiation to obtain an adhesive layer with a film thickness of 250 μm located between the release films. Then, peel and obtain this adhesive layer from the release films. Laminate this adhesive layer 4 times to form an adhesive sheet with a thickness of 1000 μm. Next, use a die cutter to punch this adhesive sheet into a circular sample with a diameter of 25 mm. Then, tear off the release films to obtain a circular adhesive sheet. Then, place it in a rheometer (TA Rheometer HR20) and, under the conditions of an axial force of 1.56 N and a discrete sweep frequency of 1 Hz, increase the temperature to 120 °C at a heating rate of 5 °C / min and record the storage modulus at 120 °C.

[0080] Table 3

[0081]

[0082]

[0083] Table 4

[0084]

[0085]

[0086] Referring to Table 3 and Table 4, in Application Examples 1 to 4, a (meth)acrylate polymer having a siloxy group was used, and the tack of the adhesive layer was 53 gf / cm 2 to 80 gf / cm 2 , the residual glue area was 0 cm 2 , and the average number of bubbles after undergoing thermal cycling was 0 and the average peel area was 0 cm 2 , while in Comparative Application Examples 1 to 4, a (meth)acrylate polymer was used, and the tack of the adhesive layer was 230 gf / cm 2 to 467 gf / cm 2 , the residual glue area was 42 cm 2 or more, and the average number of bubbles after undergoing thermal cycling was 5 or more and the average peel area was 4 cm 2 or more. As can be seen from the above, the adhesive body formed from the pressure-sensitive adhesive containing a (meth)acrylate polymer having a siloxy group has low tack and reworkability, and after undergoing thermal cycling, the adhesive body is still firmly set without peeling, and the adhesive body can still release water vapor without bubbles.

[0087] In summary, in the present invention, by introducing the silane compound represented by formula (II) into the (meth)acrylate polymer having a siloxy group, and applying the (meth)acrylate polymer having a siloxy group to the pressure-sensitive adhesive, the adhesive body formed from the pressure-sensitive adhesive can be given low tack and the ability to be peeled, resulting in the adhesive body having reworkability, and the adhesive body has excellent water vapor permeability, so that the generation of bubbles due to water vapor accumulation and the generation of white fog on the adhesive body can be reduced. At the same time, during the process of the adhesive body undergoing thermal cycling, the adhesive body can release the stress generated by the thermal cycle, so that the adhesive body is still firmly set without peeling, and the adhesive body can still release water vapor without bubbles, so the object of the present invention can be truly achieved.

Claims

1. A (meth)acrylate polymer having a siloxy group, characterized in that: The (meth)acrylate polymer having a siloxy group has a weight-average molecular weight of 5,500 to 78,500 and is formed by a polymerization reaction of a reaction composition, and the reaction composition includes an acrylate represented by formula (I) and a silane compound represented by formula (II). In formula (I), X 1 represents hydrogen or methyl and X 2 represents an alkyl group having 1 to 10 carbon atoms, (X 3 ) n Si(X 4 ) 4-n Formula (II) In formula (II), X 3 represents an alkoxy group having 1 to 3 carbon atoms, X 4 represents an epoxy group, an acryloyloxy group, a thiol group or an amino group, and n represents 1 to 3.

2. The (meth)acrylate polymer having a siloxy group according to claim 1, characterized in that: Based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by formula (II) is 1 wt% to 10 wt%.

3. The (meth)acrylate polymer having a siloxy group according to claim 2, wherein: Based on the total amount of the reaction composition being 100 wt%, the content of the silane compound represented by formula (II) is 1 wt% to 5 wt%.

4. The (meth)acrylate polymer having a siloxy group according to claim 1, characterized in that: The acryloyloxy group is Y 1 represents an alkylene group having 1 to 4 carbon atoms, and Y 2 represents hydrogen or methyl.

5. The (meth)acrylate polymer having a siloxy group according to claim 1, characterized in that: The silane compound represented by formula (II) is selected from (3-glycidoxypropyl)methyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, (N-(2-aminoethyl)-3-amino)propyltrimethoxysilane, or any combination thereof.

6. The (meth)acrylate polymer having a siloxy group according to claim 1, wherein: The reaction composition further includes an acrylamide compound represented by formula (III). In formula (III), X 5 and X 6 each independently represents hydrogen or methyl.

7. The (meth)acrylate polymer having a siloxy group according to claim 6, characterized in that: Based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by formula (III) is greater than 0 wt% and 20 wt% or less.

8. The (meth)acrylate polymer having a siloxy group according to claim 7, characterized in that: Based on the total amount of the reaction composition being 100 wt%, the content of the acrylamide compound represented by formula (III) is 10 wt% to 20 wt%.

9. The (meth)acrylate polymer having a siloxy group according to claim 1, wherein: The (meth)acrylate polymer having a siloxy group has a glass transition temperature higher than 70 °C.

10. The (meth)acrylate polymer having a siloxy group according to claim 1, characterized in that: The acrylate represented by formula (I) is selected from methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, or any combination thereof.

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