Synthetic method of high-molecular-weight polyacrylate, pressure-sensitive adhesive and polaroid

Abstract

The invention discloses a synthetic method of high molecular weight polyacrylate, a pressure-sensitive adhesive and a polaroid, and belongs to the technical field of high molecular materials, the synthetic method of the acrylate comprises the following steps: mixing 55-95 parts by weight of a soft monomer, 5-45 parts by weight of a hard monomer, 0.1-10 parts by weight of a functional monomer and 50-100 parts by weight of a solvent, then putting the mixture into a pretreatment kettle, adding an initiator, deoxidizing, and carrying out heat preservation for 2-3 hours; raising the temperature to 35-65 DEG C and carrying out heat preservation treatment to obtain pretreated kettle liquid; the invention discloses a method for synthesizing polyacrylate, which comprises the following steps of: directly pumping a pretreatment kettle liquid which is 1 / 5-1 / 2 of the total volume into a polymerization kettle, heating to 40-70 DEG C, dropwise adding the residual pretreatment kettle liquid, simultaneously dropwise adding 0.005-1 part by weight of initiator, adjusting the mass concentration of a mixed monomer, carrying out heat preservation reaction for 2-4 hours, and adjusting the solid content. And the polyacrylate is high in molecular weight and narrow in molecular weight distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a synthesis method of high molecular weight polyacrylate, a pressure-sensitive adhesive and a polarizer. Background Art

[0002] Polyacrylate pressure-sensitive adhesives are widely used in pressure-sensitive adhesive tapes, label papers, and the bonding of various optical films due to their excellent pressure-sensitive adhesive properties and good weather resistance. At the same time, with the rapid popularization of displays made of optical films in application scenarios with large changes in the use environment such as automobiles, the requirements for pressure-sensitive adhesives are gradually increasing. For example, in order to ensure that the optical film does not bubble, warp, shrink, bend, or even fall off when used under high temperature and high humidity, and to have anti-light leakage properties at high temperature or high temperature and high humidity, it is necessary to have excellent weather resistance. In addition, under certain special working conditions, such as when the optical film is bonded to the liquid crystal panel, if the bonding position deviates, the optical film needs to be able to be peeled off from the liquid crystal panel, and the bonding surface will not be contaminated during peeling.

[0003] As a pressure-sensitive adhesive for optical films that can simultaneously meet the above performance requirements, it is known to blend high molecular weight polyacrylate polymers with a certain amount of medium and low molecular weight polyacrylate polymers, then add a crosslinking agent for crosslinking, and at the same time, add some other additives such as silane coupling agents. The pressure-sensitive adhesive is mainly obtained by crosslinking high molecular weight polyacrylate polymers to obtain sufficient cohesive force, so that it does not bubble or fall off under high temperature and high humidity. At the same time, the medium and low molecular weight polyacrylate polymers prevent the related components from leaking light.

[0004] The synthesis process of low molecular weight polyacrylate polymers is relatively mature, and there are many domestic market products. However, the products of high molecular weight polyacrylate are mostly concentrated in Japan and South Korea, and there are very few research reports on the synthesis method and equipment of high molecular weight pressure sensitive adhesive for polarizer in China.

[0005] In the traditional synthesis method of polyacrylate optical pressure-sensitive adhesive reported by Japan and South Korea, as described in patent JP5347115B2, toluene, ethyl acetate and mixed solutions thereof in different proportions are mainly used as solvents. For the convenience of temperature control, the temperature during synthesis is mostly above the boiling point of the solvent, and the heat taken away when the solvent boils is used to carry out the reflux reaction. The molecular weight of the polyacrylate synthesized by this method is small, the weather resistance is poor, and the energy consumption is high. Alternatively, as described in patent CN1275984C, critical carbon dioxide is used as a solvent for the synthesis reaction. The molecular weight of the polyacrylate obtained by this method is high and the molecular weight distribution is narrow, but the synthesis conditions of this method are more harsh and dangerous (the pressure of the reaction system needs to be increased to 6-15MPa), and the production cost of the modified method is high.

[0006] The synthesis of domestic polyacrylates is described in patent CN104293249B, and the addition method of the initiator is adjusted, but the molecular weight of the synthesized polyacrylate is not given. In addition, the above synthesis of polyacrylates does not explain the relevant industrial production, but only explores the pure synthesis method. However, for free radical polymerization, especially when polymerizing high molecular weight (Mw>1.5 million) polyacrylates, due to the high viscosity of the reaction system, heat dissipation is more difficult, and the polymerization process is prone to temperature rise, resulting in the synthesized polyacrylate having a small molecular weight, a wide molecular weight distribution, and even undesirable conditions such as implosion and gelation. These undesirable phenomena not only reduce production efficiency, but also greatly increase the risk and cost control difficulty in the production process. Summary of the invention

[0007] In view of the problems that the molecular weight of the polyacrylate synthesized in the prior art is small, or the risk factor and cost of the synthesis process are high, the purpose of the present invention is to provide a method for stably synthesizing high molecular weight polyacrylate. The method has a simple process, is fully feasible for industrial production, and makes the synthesized polyacrylate have a high molecular weight and a narrow molecular weight distribution.

[0008] For this purpose, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for synthesizing a high molecular weight polyacrylate, the method comprising the following steps:

[0010] S1, pretreatment stage: by weight, 55-95 parts of soft monomer, 5-45 parts of hard monomer, 0.1-10 parts of functional monomer, and 50-100 parts of solvent are mixed and placed in a pretreatment kettle, an initiator is added, a protective gas is introduced for deoxygenation, and the temperature is raised to 35-65° C. for heat preservation treatment to obtain a pretreatment kettle liquid;

[0011] S2, reaction stage: directly inject 1 / 5 to 1 / 2 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 40-70°C, add the remaining pretreatment kettle liquid dropwise, and at the same time, add 0.005-1 weight part of initiator or an initiator solution containing 0.005-1 weight part of initiator dropwise. After the remaining pretreatment kettle liquid is added dropwise, continuously add solvent within 2-4 hours to adjust the mass concentration of the mixed monomer to 25%-50%; the mixed monomer is a mixture of soft monomers, hard monomers and functional monomers. After all the additions are completed, keep warm for reaction for 2-4 hours. After the reaction is completed, cool to room temperature, add solvent to adjust the solid content to 16%-25%, and obtain high molecular weight polyacrylate.

[0012] The present invention sets a pretreatment section in the front section of the polymerization reaction, which can effectively remove the polymerization inhibitor in the monomer on the one hand, so that the monomer purity of the polymerization reaction is higher and the molecular weight of the synthesized polyacrylate is higher. On the other hand, the polymerization process is separated from the pretreatment process, and the polymerization process and the pretreatment process can be carried out simultaneously in industry, which can greatly improve production efficiency. The existing polymerization reaction process is all in a polymerization kettle, and the method of slowly dripping initiator is adopted, which can also play the purpose of removing the polymerization inhibitor, but continuous dripping will cause the initiator in the reaction system to aggregate, and at the beginning of the polymerization reaction, the reaction speed will be extremely fast due to the high initiator concentration in the system, and the polymerization reaction will release a large amount of polymerization heat, and the reaction temperature is prone to large fluctuations, thereby causing the polymerization degree of the synthesized polyacrylate to be lower, and if the dripping rate is reduced, it will cause the production efficiency to decrease. Segmented dripping will cause the overall reaction time to be longer and the production efficiency to be lower.

[0013] Furthermore, the protective gas in S1 is one of nitrogen, helium and argon.

[0014] Furthermore, the deoxygenation time in S1 is 1 hour.

[0015] Furthermore, the holding time in S1 is greater than or equal to two half-lives of the initiator.

[0016] Furthermore, the amount of the initiator added in S1 is 0.5 to 2 times the sum of the amounts of the inhibitor substances contained in the soft monomer, the hard monomer and the functional monomer, more preferably 0.7 to 1.5 times, and more preferably 0.9 to 1.1 times.

[0017] Furthermore, the soft monomer contains a polymerization inhibitor, and the hard monomer and the functional monomer contain or do not contain a polymerization inhibitor.

[0018] Furthermore, the content of the polymerization inhibitor is provided by the raw material manufacturer or measured by spectrophotometry.

[0019] Furthermore, the soft monomer is an alkyl acrylate containing an alkyl group of 1 to 14 carbon atoms and / or an alkyl methacrylate containing an alkyl group of 1 to 14 carbon atoms.

[0020] Furthermore, the alkyl acrylate containing an alkyl group having 1 to 14 carbon atoms is at least one of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, pentyl acrylate, isopentyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate and tetradecyl acrylate.

[0021] Furthermore, the methacrylate alkyl ester having an alkyl group of 1 to 14 carbon atoms is at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl propyl acrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, n-octyl methacrylate, (2-ethyl)hexyl methacrylate, decyl methacrylate and dodecyl methacrylate.

[0022] Furthermore, the hard monomer is an acrylate and / or an aromatic vinyl derivative containing a ring structure.

[0023] Further, the hard monomer is at least one of cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, dicyclopentanyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, benzyl acrylate, benzyl methacrylate, 2-phenoxyethyl acrylate, phenyl acrylate, styrene, vinyl toluene, phenoxyethyl acrylate, phenoxyethyl methacrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, hydroxyethylated β-naphthol acrylate, biphenyl (meth)acrylate and α-methylstyrene.

[0024] Furthermore, the functional monomer is an olefin containing a hydroxyl group, a carboxyl group, an ester group, an amide group, an amine group, or a nitrile functional group.

[0025] Further, the functional monomer is at least one of N,N-dimethylaminopropyl acrylamide, N,N'-dimethylacrylamide, N,N'-diethylacrylamide, N,N'-dimethylaminoethylacrylamide, N,N'-diaminopropyl acrylamide, N-isopropylacrylamide, acryloylmorpholine, acrylamide, tert-octyl(methyl)acrylamide, diacetoneacrylamide, acrylonitrile, acrylic acid, itaconic acid, methacrylic acid, hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinylpyridine, N-vinylpyrrolidone, vinylcaprolactam, maleic acid, crotonic acid, trifluoromethylacrylic acid, maleic acid, fumaric acid, citraconic acid, hydroxybutyl acrylate, hydroxyethyl caprolactone acrylate, polypropylene glycol methacrylate, hydroxyacrylic acid, itaconic acid, glycidyl(meth)acrylate and pentaerythritol acrylate.

[0026] Further, the solvent is at least one of benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, aromatic naphtha, n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, white spirit, petroleum naphtha, turpentine, ethyl acetate, n-butyl acetate, n-pentyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, acetone, methyl ethyl ketone, methyl-isobutyl ketone, isophorone cyclohexanone, methylcyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol.

[0027] Furthermore, the one-hour half-life temperature of the initiator in S1 and S2 is 20-80°C.

[0028] Further, the initiator is at least one of diisobutyryl peroxide, isopropylbenzene peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, diisobutyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate and dilauroyl peroxide.

[0029] Furthermore, the remaining pretreatment kettle liquid addition time and the initiator solution addition time in S2 satisfy the following formula: T2-T1≥(1~3)h, T1 is the remaining pretreatment kettle liquid addition time, ranging from 2~4h, T2 is the initiator solution addition time, ranging from 3~5h.

[0030] Furthermore, the mass concentration of the mixed monomers in S2 is 25-45%, more preferably 30-45%.

[0031] In a second aspect, the present invention provides a pressure-sensitive adhesive, which comprises the following raw materials in parts by weight: 100 parts of high molecular weight polyacrylate, 120 parts of ethyl acetate, 0.21 parts of a cross-linking agent, and 0.1 parts of a silane coupling agent.

[0032] The method for preparing the pressure-sensitive adhesive comprises the following steps:

[0033] Weigh the raw materials according to the formula ratio, and stir the high molecular weight polyacrylate, ethyl acetate, crosslinking agent and silane coupling agent evenly at room temperature.

[0034] Furthermore, the cross-linking agent is an isocyanate compound, preferably at least one of toluene diisocyanate (TD I), isophorone diisocyanate (IPD I), diphenylmethane diisocyanate (MD I), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HD I) and lysine diisocyanate (LD I).

[0035] Furthermore, the silane coupling agent is a siloxane containing unsaturated double bonds and / or a siloxane containing epoxy groups and / or a siloxane containing amino groups and / or a siloxane containing halogen atoms.

[0036] Furthermore, the siloxane containing unsaturated double bonds is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-(trimethoxysilyl)propyl 3-oxobutyrate and methacryloxypropyltrimethoxysilane.

[0037] Furthermore, the epoxy-containing siloxane is at least one of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0038] Furthermore, the amino-containing siloxane is at least one of 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0039] Furthermore, the siloxane containing halogen atoms is 3-chloropropyltrimethoxysilane and / or 3-bromopropyltrimethoxysilane.

[0040] In a third aspect, the present invention provides a polarizer comprising the above-mentioned pressure-sensitive adhesive.

[0041] Beneficial effects of the present invention:

[0042] (1) The acrylate preparation process of the present invention adopts low temperature initiation polymerization, thereby reducing the occurrence of chain transfer and side reactions and increasing the degree of polymerization; a two-step treatment process is adopted, the first step is to remove oxygen and inhibitors, and the second step is to initiate polymerization, so that the polymerization reaction is not affected by the inhibitor during synthesis, and polyacrylates with higher molecular weight can be synthesized; low initiator ratio and high monomer concentration increase the molecular weight; to ensure uniformity, solvent is added dropwise during the polymerization process; in addition, the material is slowly added to the polymerization kettle during the polymerization stage, which can make the release of reaction heat slower, thereby improving the stability of the polymerization reaction. A stable reaction system is the key to synthesizing high molecular weight and low molecular weight distribution. The polymerization method of the present invention can obtain polyacrylates with a weight average molecular weight Mw of 1.5 to 2.6 million and a molecular weight distribution Mw / Mn of less than 1.65.

[0043] (2) The present invention accurately controls the dosage range of the initiator in the pretreatment stage, which can effectively remove the inhibitor and ensure the stability of the reaction system. Otherwise, if the amount of initiator added is too little, the inhibitor will remain too much, which is not conducive to the acquisition of high molecular weight polypropionate. If the amount of initiator added is too much, the polymerization reaction will occur prematurely and there is a risk of explosion.

[0044] (3) The present invention strictly controls the amount of initiator used in the reaction stage. If the amount of initiator used in this process is too low, the monomer conversion rate is low, and the pressure-sensitive adhesive prepared from the obtained polyacrylate has poor reworkability. If the amount of initiator used is too high, the molecular weight of the synthesized polyacrylate is low.

[0045] (4) The present invention strictly controls the concentration of the mixed monomers during the reaction stage, because if the concentration is too low, the molecular weight of the synthesized polypropionate is low, and if the concentration is too high, gelation and other phenomena are likely to occur.

[0046] (5) The polyacrylate preparation process provided by the present invention significantly reduces energy consumption because it is carried out in a low temperature environment, avoiding the high energy consumption problem caused by traditional high temperature reactions. This low temperature environment not only helps to save energy, but also reduces the negative impact on the environment, which is in line with the principles of greening and sustainable development.

[0047] (6) The process conditions of the present invention are mild and do not require harsh conditions such as high pressure, which makes the production process safer and more controllable and reduces equipment investment and operating costs. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] A first aspect of an embodiment of the present invention provides a method for synthesizing a high molecular weight polyacrylate, comprising the following steps:

[0050] S1, pretreatment stage: by weight, 55-95 parts of soft monomer, 5-45 parts of hard monomer, 0.1-10 parts of functional monomer, and 50-100 parts of solvent are mixed and placed in a pretreatment kettle, an initiator is added, a protective gas is introduced for deoxygenation, and the temperature is raised to 35-65° C. for heat preservation treatment to obtain a pretreatment kettle liquid;

[0051] S2, reaction stage: directly inject 1 / 5 to 1 / 2 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 40-70°C, add the remaining pretreatment kettle liquid dropwise, and at the same time, add 0.005-1 weight part of initiator or an initiator solution containing 0.005-1 weight part of initiator dropwise. After the remaining pretreatment kettle liquid is added dropwise, continuously add solvent within 2-4 hours to adjust the mass concentration of the mixed monomer to 25-50%; the mixed monomer is a mixture of soft monomers, hard monomers and functional monomers. After all the additions are completed, keep warm for reaction for 2-4 hours. After the reaction is completed, cool to room temperature, add solvent to adjust the solid content to 16-25%, and obtain high molecular weight polyacrylate.

[0052] In some specific embodiments, the protective gas in S1 is one of nitrogen, helium and argon.

[0053] In some specific embodiments, the deoxygenation time in S1 is 1 hour.

[0054] In some specific embodiments, the holding time in S1 is greater than or equal to two half-lives of the initiator.

[0055] In some specific embodiments, the amount of the initiator added in S1 is 0.5 to 2 times the sum of the amounts of the inhibitor substances contained in the soft monomer, the hard monomer and the functional monomer, more preferably 0.7 to 1.5 times, and more preferably 0.9 to 1.1 times.

[0056] In some specific embodiments, the soft monomer contains a polymerization inhibitor, and the hard monomer and the functional monomer contain or do not contain a polymerization inhibitor.

[0057] In some specific embodiments, the content of the polymerization inhibitor is provided by the raw material manufacturer or measured by spectrophotometry.

[0058] In some specific embodiments, the soft monomer is an alkyl acrylate containing an alkyl group of 1 to 14 carbon atoms and / or an alkyl methacrylate containing an alkyl group of 1 to 14 carbon atoms.

[0059] In some specific embodiments, the alkyl acrylate containing an alkyl group of 1 to 14 carbon atoms is at least one of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, isopentyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate and tetradecyl acrylate.

[0060] In some specific embodiments, the methacrylate alkyl ester having an alkyl group of 1 to 14 carbon atoms is at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl propyl acrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, n-octyl methacrylate, (2-ethyl)hexyl methacrylate, decyl methacrylate and dodecyl methacrylate.

[0061] In some specific embodiments, the hard monomer is an acrylate and / or an aromatic vinyl derivative containing a ring structure.

[0062] In some specific embodiments, the acrylate containing a ring structure is at least one of isobornyl acrylate, 2-cyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, benzyl acrylate, benzyl methacrylate, 2-phenoxyethyl acrylate and phenyl acrylate.

[0063] In some specific embodiments, the aromatic vinyl derivative is styrene and / or vinyltoluene.

[0064] In some specific embodiments, the functional monomer is an olefin containing a hydroxyl group, a carboxyl group, an ester group, an amide group, an amine group, or a nitrile functional group.

[0065] In some specific embodiments, the functional monomer is at least one of N,N-dimethylaminopropyl acrylamide, N,N'-dimethylacrylamide, N,N'-diethylacrylamide, N,N'-dimethylaminoethylacrylamide, N,N'-diaminopropyl acrylamide, N-isopropylacrylamide, acryloylmorpholine, acrylamide, tert-octyl(meth)acrylamide, diacetoneacrylamide, acrylonitrile, acrylic acid, itaconic acid, methacrylic acid, hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinylpyridine, N-vinylpyrrolidone, vinyl caprolactam, maleic acid, crotonic acid, trifluoromethylacrylic acid, maleic acid, fumaric acid, citraconic acid, hydroxybutyl acrylate, hydroxyethyl caprolactone acrylate, polypropylene glycol methacrylate, hydroxy acrylic acid, itaconic acid, glycidyl(meth)acrylate and pentaerythritol acrylate.

[0066] In some specific embodiments, the solvent is at least one of benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, aromatic naphtha, n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, white spirit, petroleum naphtha, turpentine, ethyl acetate, n-butyl acetate, n-pentyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, acetone, methyl ethyl ketone, methyl-isobutyl ketone, isophoronecyclohexanone, methylcyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol.

[0067] In some specific embodiments, the one-hour half-life temperature of the initiator in S1 and S2 is 20-80°C.

[0068] In some specific embodiments, the initiator is at least one of diisobutyryl peroxide, isopropylbenzene peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, diisobutyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate and dilauroyl peroxide.

[0069] In some specific embodiments, the remaining pretreatment kettle liquid addition time and the initiator solution addition time in S2 satisfy the following formula: T2-T1≥(1~3)h, T1 is the remaining pretreatment kettle liquid addition time, ranging from 2 to 4h, T2 is the initiator solution addition time, ranging from 3 to 5h.

[0070] In some specific embodiments, the mass concentration of the mixed monomers in S2 is 25-45%, more preferably 30-45%.

[0071] A second aspect of an embodiment of the present invention provides a pressure-sensitive adhesive, which includes the following raw materials in parts by weight: 100 parts of high molecular weight polyacrylate, 120 parts of ethyl acetate, 0.21 parts of a cross-linking agent, and 0.1 parts of a silane coupling agent.

[0072] The method for preparing the pressure-sensitive adhesive comprises the following steps:

[0073] Weigh the raw materials according to the formula ratio, and stir the high molecular weight polyacrylate, ethyl acetate, crosslinking agent and silane coupling agent evenly at room temperature.

[0074] In some specific embodiments, the cross-linking agent is an isocyanate compound, preferably at least one of toluene diisocyanate (TD I), isophorone diisocyanate (IPD I), diphenylmethane diisocyanate (MD I), dicyclohexylmethane diisocyanate (HMD I), hexamethylene diisocyanate (HD I) and lysine diisocyanate (LD I).

[0075] In some specific embodiments, the silane coupling agent is a siloxane containing unsaturated double bonds and / or a siloxane containing epoxy groups and / or a siloxane containing amino groups and / or a siloxane containing halogen atoms.

[0076] In some specific embodiments, the siloxane containing unsaturated double bonds is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-(trimethoxysilyl)propyl 3-oxobutyrate and methacryloxypropyltrimethoxysilane.

[0077] In some specific embodiments, the epoxy-containing siloxane is at least one of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0078] In some specific embodiments, the amino-containing siloxane is at least one of 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0079] In some specific embodiments, the siloxane containing halogen atoms is 3-chloropropyltrimethoxysilane and / or 3-bromopropyltrimethoxysilane.

[0080] A third aspect of the embodiments of the present invention provides a polarizer, comprising the above-mentioned pressure-sensitive adhesive.

[0081] In the present application, the inhibitor contents of butyl acrylate, benzyl methacrylate and hydroxyethyl acrylate are all 60 ppm, and the inhibitor is p-hydroxyanisole, all of which are purchased from Sinopharm Group.

[0082] Example 1

[0083] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0084] S1, pretreatment stage: 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 80 parts of ethyl acetate were mixed by weight, and placed in a pretreatment kettle, and then 0.011 parts of diisobutyl peroxydicarbonate were added, nitrogen was introduced for deoxygenation for 1 hour, and the temperature was raised to 63° C. for insulation treatment for 2 hours to obtain a pretreatment kettle liquid;

[0085] S2, reaction stage: directly inject 1 / 4 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, continuously drop the remaining pretreatment kettle liquid within 3 hours, and at the same time continuously drop 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours. After the remaining pretreatment kettle liquid is added, continuously add 100 parts by weight of ethyl acetate within 3 hours; after all the additions are completed, keep warm and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0086] Example 2

[0087] Compared with Example 1, except that the amount of diisobutyl peroxydicarbonate added in step S2 is adjusted from 0.1 parts by weight to 0.05 parts by weight, the rest is the same as Example 1.

[0088] Example 3

[0089] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0090] S1, pretreatment stage: by weight, 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate and 100 parts of ethyl acetate were mixed and placed in a pretreatment kettle, 0.023 parts of tert-butyl peroxyneodecanoate were added, nitrogen was introduced for deoxygenation for 1 hour, the temperature was raised to 64° C. and heat-insulated for 2 hours to obtain a pretreatment kettle liquid;

[0091] S2, reaction stage: directly inject 1 / 5 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, add the remaining pretreatment kettle liquid dropwise, and at the same time, add 1 weight part of diisobutyl peroxydicarbonate dropwise. The remaining pretreatment kettle liquid is added dropwise for 2 hours, and the initiator solution is added dropwise for 3 hours. After the remaining pretreatment kettle liquid is added dropwise, 200 weight parts of ethyl acetate are continuously added within 2 hours to adjust the mass concentration of the mixed monomer; the mixed monomer is a mixture of soft monomers, hard monomers and functional monomers. After all the additions are completed, keep the temperature for reaction for 4 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 16%, and obtain a high molecular weight polyacrylate.

[0092] Example 4

[0093] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0094] S1, pretreatment stage: by weight, 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate and 50 parts of ethyl acetate were mixed and placed in a pretreatment kettle, 0.006 parts of tert-butyl peroxyneodecanoate were added, nitrogen was introduced for deoxygenation for 1 hour, the temperature was raised to 64°C for insulation treatment for 2 hours, and a pretreatment kettle liquid was obtained;

[0095] S2, reaction stage: directly inject 1 / 2 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, add the remaining pretreatment kettle liquid dropwise, and at the same time add 0.005 weight part of initiator (diisobutyl peroxydicarbonate), the remaining pretreatment kettle liquid dropwise addition time is 4h, the initiator solution dropwise addition time is 5h. After the remaining pretreatment kettle liquid is added dropwise, 50 weight parts of ethyl acetate are continuously added within 4h to adjust the mass concentration of the mixed monomer; the mixed monomer is a mixture of soft monomers, hard monomers and functional monomers. After all the additions are completed, keep the temperature for reaction for 2h. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 25%, and obtain a high molecular weight polyacrylate.

[0096] Comparative Example 1

[0097] Compared with Example 1, in the pretreatment stage, the treatment kettle liquid is put into the reaction kettle at one time, and the rest is consistent with Example 1.

[0098] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0099] S1, pretreatment stage: same as step S1 in Example 1;

[0100] S2, reaction stage: directly inject all the pretreatment kettle liquid into the polymerization kettle, heat to 70°C, continuously add 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours, add ethyl acetate after 3 hours of diisobutyl peroxydicarbonate addition, and continuously add 100 parts by weight of ethyl acetate within 3 hours; after all the additions are completed, keep warm and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0101] Comparative Example 2

[0102] Compared with Example 1, no pretreatment stage is performed, and the rest is the same as Example 1.

[0103] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0104] S1, pretreatment stage: 80 parts by weight of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 80 parts of ethyl acetate are placed in a pretreatment kettle, and stirred for 30 minutes to obtain a pretreatment kettle liquid;

[0105] S2, reaction stage: directly inject 1 / 4 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, continuously drop the remaining pretreatment kettle liquid within 3 hours, and at the same time continuously drop 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours. After the remaining pretreatment kettle liquid is added, continuously add 100 parts by weight of ethyl acetate within 3 hours; after all the additions are completed, keep warm and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0106] Comparative Example 3

[0107] Compared with Example 1, no pretreatment stage is performed, the treated kettle liquid is put into the reactor at one time, and the rest is the same as Example 1.

[0108] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0109] S1, pretreatment stage: 80 parts by weight of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 80 parts of ethyl acetate are placed in a pretreatment kettle, and stirred for 30 minutes to obtain a pretreatment kettle liquid;

[0110] S2, reaction stage: directly inject all the pretreatment kettle liquid into the polymerization kettle, directly inject all the pretreatment kettle liquid into the polymerization kettle, heat to 70°C, continuously add 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours, add ethyl acetate after 3 hours of diisobutyl peroxydicarbonate addition, and continuously add 100 parts by weight of ethyl acetate within 3 hours; after all the additions are completed, keep warm and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0111] Comparative Example 4

[0112] Compared with Example 1, except that the ethyl acetate to be added dropwise in the reaction stage is added all at once before the initiator is added dropwise, the rest is consistent with Example 1.

[0113] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0114] S1, pretreatment stage: same as in Example 1;

[0115] S2, reaction stage: directly inject 1 / 4 of the total volume of pretreatment kettle liquid and 100 parts by weight of ethyl acetate into a polymerization kettle, heat to 70°C, continuously drop the remaining pretreatment kettle liquid within 3 hours, and simultaneously continuously drop 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours. After the remaining pretreatment kettle liquid is added, keep warm and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0116] Comparative Example 5

[0117] Compared with Example 1, except that the ethyl acetate to be added dropwise in the reaction stage is added all at once after the initiator is added dropwise, the rest is the same as Example 1.

[0118] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0119] S1, pretreatment stage: same as in Example 1;

[0120] S2, reaction stage: directly inject 1 / 4 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, and continuously drop the remaining pretreatment kettle liquid within 3 hours. At the same time, continuously drop 0.1 parts by weight of diisobutyl peroxydicarbonate within 4 hours. After the addition of diisobutyl peroxydicarbonate is completed, add 100 parts by weight of ethyl acetate at one time, keep the temperature and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0121] Comparative Example 6

[0122] Compared with Example 1, diisobutyl peroxydicarbonate was replaced with dibenzoyl peroxide, and the temperatures in the pretreatment and reaction stages were both adjusted to 78° C., and the rest were the same as in Example 1.

[0123] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0124] S1, pretreatment stage: 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 80 parts of ethyl acetate were mixed by weight, and placed in a pretreatment kettle, and then 0.011 parts of dibenzoyl peroxide were added, nitrogen was introduced for deoxygenation for 1 hour, and the temperature was raised to 78° C. for insulation treatment for 2 hours to obtain a pretreatment kettle liquid;

[0125] S2, reaction stage: directly inject 1 / 4 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 70°C, continuously drop the remaining pretreatment kettle liquid within 3 hours, and simultaneously continuously drop 1 part by weight of dibenzoyl peroxide ethyl acetate solution within 4 hours, wherein the dibenzoyl peroxide ethyl acetate solution contains 0.1 part by weight of dibenzoyl peroxide. After the remaining pretreatment kettle liquid is added dropwise, continuously add 100 parts by weight of ethyl acetate within 3 hours; after all the additions are completed, heat and react for 3 hours. After the reaction is completed, cool to room temperature, add ethyl acetate to adjust the solid content to 20%, and obtain high molecular weight polyacrylate.

[0126] Comparative Example 7

[0127] Compared with Example 1, except that the amount of diisobutyl peroxydicarbonate added in step S1 is adjusted from 0.011 parts by weight to 0.005 parts by weight, the rest is the same as Example 1.

[0128] Comparative Example 8

[0129] Compared with Example 1, except that the amount of diisobutyl peroxydicarbonate added in step S1 is adjusted from 0.011 parts by weight to 0.025 parts by weight, the rest is the same as Example 1.

[0130] Comparative Example 9

[0131] Compared with Example 1, except that the amount of ethyl acetate added in steps S1 and S2 is reduced, the rest is consistent with Example 1.

[0132] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0133] S1, pretreatment stage: 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 40 parts of ethyl acetate were mixed by mass and placed in a pretreatment kettle, 0.011 parts of diisobutyl peroxydicarbonate were added to the pretreatment kettle, and then nitrogen was introduced for deoxygenation for 1 hour. After the deoxygenation was completed, the temperature was raised to 63°C and kept warm for 2 hours;

[0134] S2, reaction stage: after the pretreatment is completed, 1 / 4 of the pretreatment kettle liquid is directly injected into the polymerization kettle, the kettle temperature is 70°C, the remaining pretreatment kettle liquid is continuously added to the reactor within 3 hours, and 0.1 parts by weight of diisobutyl peroxydicarbonate is continuously added dropwise for 4 hours. After the pretreatment kettle liquid is added dropwise, ethyl acetate is added, and 40 parts by weight of ethyl acetate are continuously added within 3 hours; after the initiator is added dropwise, the reaction is continued for 3 hours, and then an appropriate amount of ethyl acetate is added to adjust the kettle liquid solid content to 20% before discharging.

[0135] Comparative Example 10

[0136] Compared with Example 1, except that the amount of ethyl acetate added in steps S1 and S2 is increased, the rest is consistent with Example 1.

[0137] A method for synthesizing high molecular weight polyacrylate comprises the following steps:

[0138] S1, pretreatment stage: 80 parts of butyl acrylate, 15 parts of benzyl methacrylate, 5 parts of hydroxyethyl acrylate, and 110 parts of ethyl acetate were mixed by mass and placed in a pretreatment kettle, 0.011 parts of diisobutyl peroxydicarbonate were added to the pretreatment kettle, and then nitrogen was introduced for deoxygenation for 1 hour. After the deoxygenation was completed, the temperature was raised to 63°C and kept warm for 2 hours;

[0139] S2, reaction stage: After the pretreatment, 1 / 4 of the pretreatment kettle liquid is directly poured into the preheated reactor, the kettle temperature is 70°C, the remaining pretreatment kettle liquid is continuously added to the reactor within 3 hours, and 0.1 parts by weight of diisobutyl peroxydicarbonate is continuously added dropwise for 4 hours. After the pretreatment kettle liquid is added dropwise, ethyl acetate is added, and 210 parts by weight of ethyl acetate are continuously added within 3 hours; after the initiator is added dropwise, the reaction is continued for 3 hours, and then an appropriate amount of ethyl acetate is added to adjust the kettle liquid solid content to 20% before discharging.

[0140] Comparative Example 11

[0141] Compared with Example 1, except that the amount of diisobutyl peroxydicarbonate added in step S2 is adjusted from 0.1 parts by weight to 0.003 parts by weight, the rest is the same as Example 1.

[0142] Comparative Example 12

[0143] Compared with Example 1, except that the amount of diisobutyl peroxydicarbonate added in step S2 is adjusted from 0.1 parts by weight to 1.2 parts by weight, the rest is the same as Example 1.

[0144] Performance Testing

[0145] The molecular weight and molecular weight distribution tests were performed on the high molecular weight polyacrylates prepared in Examples 1 to 2 and Comparative Examples 1 to 12. The test process is as follows:

[0146] The molecular weight and molecular weight distribution were measured by GPC produced by Waters Company, and the weight average molecular weight was obtained by conversion to standard polystyrene; the sample concentration of GPC test was 2 mg / mL, the sample introduction volume was 5 mL, the temperature was 30°C, and the flow rate was 1 mL / min, and the determination was carried out by dissolving in tetrahydrofuran;

[0147] The high molecular weight polyacrylates prepared in Examples 1 to 4 and Comparative Examples 1 to 12 were prepared into pressure-sensitive adhesives and tested. The preparation process is as follows:

[0148] By weight, 100 parts of the above-mentioned high molecular weight polyacrylate, 120 parts of ethyl acetate, 0.21 parts of toluene diisocyanate, and 0.1 parts of vinyl trimethoxy silane were stirred uniformly at room temperature to obtain a pressure-sensitive adhesive, which was then coated on a PET release film containing a release agent. The adhesive layer had a thickness of 22 um after drying, and was cured at 35° C. and 55% RH for 7 days to obtain a pressure-sensitive adhesive film. The pressure-sensitive adhesive film was attached to a polarizing plate, and then cut to obtain an optical component, which was then tested for durability, reworkability, and light leakage resistance;

[0149] The specific testing process is as follows:

[0150] (1) Durability evaluation method

[0151] The optical components were cut into a specified size of 170*250mm and bonded to one side of an alkali-free glass plate using a laminating machine to make a test plate. After degassing, the plates were placed at a temperature of 60°C and a humidity of 90% RH and at a temperature of 80°C for 500 hours, and evaluated by visually observing for bubbling, peeling, cracking, and edge shrinkage distance of the glue according to the following criteria.

[0152] ○: No appearance defects such as foaming, peeling, and cracking are found, and the shrinkage distance of the glue edge is ≤0.2mm;

[0153] △: A small amount of foaming, peeling, cracking and other poor appearance are found, and the shrinkage distance of the glue edge is ≤0.2mm;

[0154] ×: obvious appearance defects such as foaming, peeling, cracking, etc., or the shrinkage distance of the glue edge is ≥ 0.2mm;

[0155] (2) Reworkability test

[0156] The optical components were cut into a specified size of 170*250mm, bonded to one side of an alkali-free glass plate using a laminating machine to make a test plate. After degassing, the plate was left to stand at 70°C for 6 hours, cooled to 23°C, and then peeled off from the glass plate at 180°, and the surface of the glass plate was observed with the naked eye.

[0157] ○: No contamination or adhesive residue was found on the surface of the glass plate;

[0158] △: A small amount of contamination and adhesive residue were found on the surface of the glass plate;

[0159] ×: Contamination and adhesive residue are obviously found on the surface of the glass plate;

[0160] The test results are shown in Table 1:

[0161] Table 1

[0162]

[0163]

[0164] It can be seen from Table 1 that the synthesis method of the present invention can be used to synthesize polyacrylates with higher molecular weight and narrower molecular weight distribution. At the same time, the weather resistance, rework performance and light leakage prevention performance of Examples 1 and 2 with higher molecular weight are excellent.

[0165] It can be seen from Example 1 and Comparative Example 1 in Table 1 that the step-by-step feeding method is adopted so that the polymerization reaction is not affected by the polymerization inhibitor during synthesis, and polyacrylate with a higher molecular weight can be synthesized.

[0166] It can be concluded from Example 1, Comparative Example 2, Comparative Example 7 and Comparative Example 8 in Table 1 that the monomer needs to be pretreated, and the amount of pretreatment initiator added needs to be within an appropriate range. Too much or too little is not conducive to the synthesis of polyacrylates with higher molecular weight.

[0167] It can be concluded from Example 1 and Comparative Example 6 in Table 1 that the polymerization is initiated at a low temperature, thereby reducing the occurrence of chain transfer and side reactions, which is beneficial to increasing the degree of polymerization;

[0168] It can be concluded from Example 1, Example 2, Comparative Example 9, Comparative Example 10, Comparative Example 11 and Comparative Example 12 in Table 1 that reducing the initiator ratio and increasing the monomer concentration can increase the molecular weight, but the monomer concentration must be within a certain range. Too high a monomer concentration is prone to gelation, and a low monomer concentration will lead to a decrease in the molecular weight of the synthesized polyacrylate.

[0169] It can be concluded from Example 1, Comparative Example 3, Comparative Example 4 and Comparative Example 5 in Table 1 that dropwise addition of monomers and solvents is beneficial to improving the stability of the polymerization reaction and obtaining polyacrylates with higher molecular weight.

[0170] To ensure uniformity, the solvent is added dropwise during the polymerization process. In addition, slowly adding the materials to the polymerization kettle during the polymerization stage can make the release of reaction heat slower, so a stable reaction system is the key to synthesizing high molecular weight and low molecular weight distribution. The polymerization method of the present invention can obtain polyacrylates with a weight average molecular weight Mw of 1.5 to 2.6 million and a molecular weight distribution Mw / Mn of less than 1.65.

[0171] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0172] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing high molecular weight polyacrylate, characterized in that: The following steps are involved: S1. Mix 55-95 parts of soft monomer, 5-45 parts of hard monomer, 0.1-10 parts of functional monomer and 50-100 parts of solvent by weight, place in a pretreatment kettle, add initiator, introduce protective gas for deoxygenation, heat to 35-65° C. for insulation treatment, and obtain pretreatment kettle liquid; S2. Pour 1 / 5 to 1 / 2 of the total volume of the pretreatment kettle liquid into the polymerization kettle, heat it to 40 to 70°C, add the remaining pretreatment kettle liquid dropwise, and at the same time, add 0.005 to 1 part by weight of an initiator or an initiator solution containing 0.005 to 1 part by weight of an initiator. After the remaining pretreatment kettle liquid is added dropwise, continuously add solvent within 2 to 4 hours to adjust the mass concentration of the mixed monomers. After all the additions are completed, keep the temperature for reaction for 2 to 4 hours. After the reaction is completed, cool to room temperature and adjust the solid content to obtain a high molecular weight polyacrylate.

2. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The holding time in S1 is greater than or equal to two half-lives of the initiator.

3. A method for synthesizing a high molecular weight polyacrylate according to claim 1 or 2, characterized in that: The amount of initiator added in S1 is 0.5 to 2 times the sum of the amounts of inhibitor substances contained in the soft monomer, the hard monomer and the functional monomer.

4. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The soft monomer is an alkyl acrylate containing an alkyl group of 1 to 14 carbon atoms and / or an alkyl methacrylate containing an alkyl group of 1 to 14 carbon atoms.

5. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The hard monomer is an acrylate and / or an aromatic vinyl derivative containing a ring structure.

6. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The functional monomer is an olefin containing a hydroxyl group, a carboxyl group, an ester group, an amide group, an amine group or a nitrile functional group.

7. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The one-hour half-life temperature of the initiator in S1 and S2 is 20-80°C.

8. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The initiator is at least one of diisobutyryl peroxide, isopropylbenzene peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, diisobutyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate and dilauroyl peroxide.

9. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The remaining pretreatment kettle liquid addition time and the initiator solution addition time in S2 satisfy the following formula: T2-T1≥(1~3)h, T1 is the remaining pretreatment kettle liquid addition time, ranging from 2 to 4h, T2 is the initiator solution addition time, ranging from 3 to 5h.

10. The method for synthesizing a high molecular weight polyacrylate according to claim 1, characterized in that: The mass concentration of the mixed monomer in S2 is 25-50%, and the mixed monomer is a mixture of soft monomer, hard monomer and functional monomer.

11. A pressure-sensitive adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of high molecular weight polyacrylate prepared by the synthesis method according to any one of claims 1 to 10, 120 parts of ethyl acetate, 0.21 parts of a cross-linking agent, and 0.1 parts of a silane coupling agent.

12. A pressure-sensitive adhesive according to claim 11, characterized in that: The cross-linking agent is an isocyanate compound.

13. A pressure-sensitive adhesive according to claim 12, characterized in that: The silane coupling agent is siloxane containing unsaturated double bonds and / or siloxane containing epoxy groups and / or siloxane containing amino groups and / or siloxane containing halogen atoms.

14. A polarizer, characterized in that: Including the pressure-sensitive adhesive according to any one of claims 11 to 13.

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