OCA optical adhesive and method for producing the same.

Abstract

The present invention discloses an OCA optical adhesive and a method for manufacturing the same. The optical adhesive is composed of one or more block copolymers. The method uses reversible addition-fragmentation chain transfer emulsion polymerization, and controls the types and supply order of monomers to prepare a block copolymer with controllable design. Then, one or more types of prepared block copolymers are mixed and a solution is formed into a film to obtain an OCA optical adhesive. The OCA optical adhesive manufactured by the present invention has the advantages of high elongation, high transparency, and low haze, and can effectively reduce the modulus and improve the peel strength on the premise of not affecting the resilience. Therefore, it has extremely great application potential in fields such as electronic display devices, wearable electronic devices, resistive touch panels, and smart optical devices.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, and particularly to an OCA optical adhesive and a method for manufacturing the same.

Background Art

[0002] In the modern information electronics industry, displays provide users with a gateway to device operation, enabling feedback and responses to the device, and are a crucial component of the Human-Computer Interaction (HCI) interface in modern electronic devices. The development of display technology and related materials is a critical condition for the advancement of advanced electronic devices. Optically clear pressure-sensitive adhesive (OCA) is an important functional material widely used in display devices, and is used for bonding transparent optical elements. Optical adhesives are colorless and transparent, have a light transmittance of over 90%, excellent adhesive strength, can be cured at room temperature, and exhibit low curing shrinkage. Furthermore, optical adhesives are flexible, highly viscoelastic, and have the ability to reduce refractive index differences by filling voids, thus contributing to improved image clarity. To reduce the mechanical feel of electronic displays and improve the intimacy between the user and the device, displays have evolved from conventional flat-type displays to flexible arc-shaped displays, curved displays, and even foldable and rollable displays. Furthermore, the growing demand for wearable and flexible electronic devices has led to increasing public interest in flexible displays. The emergence of these new device forms presents new challenges to the performance of OCA optical adhesives. Conventional OCA has characteristics such as high modulus and strong adhesive performance, but the stress on the tensile stress layer of the panel increases during the folding process, causing serious material fatigue. As a result, the adhesive function is lost when the device is actually used, leading to visual discomfort during use and significantly reducing the user experience and lifespan of the foldable smartphone. Currently, OCA optical adhesives used in foldable smartphones need to possess three properties: (1) high flexibility that can generate high shear strain and only small stress when greatly deformed, (2) high elasticity that can quickly restore even when statically folded for a long time, and (3) high interfacial adhesion that prevents delamination and peeling of the adhesive when subjected to pressure.

[0003] Currently, most OCA optical adhesives are manufactured by photoinitiated polymerization. Firstly, the elasticity of OCA optical adhesives can be improved by increasing the initiator concentration and thus the crosslinking density. Secondly, the elasticity of OCA optical adhesives can also be improved by adding functional monomers such as acrylic acid to the system to improve the cohesive force of the material. However, the main difficulty lies in the inability to achieve a balance between fluidity and elasticity. In this case, the modulus of the OCA optical adhesive is significantly improved, but the extensibility decreases, making it difficult to apply to foldable smartphones.

[0004] In addition, OCA optical adhesives with alternating high and low crosslinking degrees are manufactured using the UV molding method. In this case, it is possible to reduce the modulus of the OCA optical adhesive to some extent and improve the peel strength of the material, but at the same time, the resilience of the material is reduced.

[0005] Currently, one way to balance elasticity and flexibility is to add 10 mol% acrylic acid to the adhesive prepolymer. This improves the peel strength of a 100 μm thick OCA optical adhesive to approximately 14 N / 25 mm while maintaining a vitrification temperature of -54.3°C and a modulus of 27 kPa. However, since fracture occurs when the elongation exceeds 300%, this method cannot support the long-term use of the optical adhesive.

[0006] Therefore, it is an urgent issue to research and develop a technology that improves the peel strength of the OCA optical adhesive and lowers the modulus of the material, thereby giving the OCA optical adhesive a good balance of flexibility, modulus, and interfacial adhesion, while improving the elongation of the OCA optical adhesive without affecting its resilience. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In response to the shortcomings of the prior art, the present invention provides a method for producing an OCA optical adhesive with controllable structure. This method involves preparing block copolymers with controllable design by reversible addition-cleavage chain transfer emulsion polymerization, and forming one or more types of block copolymer solutions to produce a highly elongated, highly transparent, and low-haze OCA optical adhesive that effectively reduces modulus and improves peel strength without affecting resilience. [Means for solving the problem]

[0008] This invention is realized by the following technical means. The OCA optical adhesive is composed of a main substrate with a mass content of 20-100% and a reinforcing substrate with a mass content of 0-80%.

[0009] The structural formula of the aforementioned main substrate is M1-b-M2-b-M3···-bM j The range of j is 3 to 11. Also, M1, M2, M3...M j M1, M2, M3···M are comonomers of block copolymers, and the number-average molecular weight of the block copolymers of the main substrates is 8 to 800,000 g / mol. j Each of these is selected from soft monomers, hard monomers, or functional monomers. Furthermore, the mass content of soft monomers, hard monomers, and functional monomers in the block copolymer is 70-98%, 2-30%, and 0-5%, respectively.

[0010] The structural formula of the reinforcing substrate is N1 or N1-b-N2, and the number-average molecular weight of the block copolymer of the reinforcing substrate is 10 to 400,000 g / mol. N1 is a soft monomer, and N2 is a hard monomer or a functional monomer. Furthermore, the mass content of the soft monomer, hard monomer, and functional monomer in the block copolymer is 75 to 100%, 0 to 25%, and 0 to 5%, respectively.

[0011] Specifically, the hard monomers include styrene, methyl acrylate, methyl methacrylate, acrylamide, acrylonitrile, and vinyl acetate, with a vitrification temperature range of 60 to 150°C. The soft monomers include ethyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, butadiene, isoprene, ethylene-butene, and methacrylic acid, with a vitrification temperature range of -90 to -30°C. The functional monomers include methacrylic acid, acrylic acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxy-1-methylethyl acrylat, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-(dimethylamino)ethyl methacrylate, methacrylamide, N-(hydroxymethyl)acrylamide, glycidyl methacrylate, and maleic anhydride.

[0012] Specifically, the steps are as follows:

[0013] (1) Dissolve the amphiphilic polymer reversible addition-cleavage chain transfer reagent in water, then add styrene, or styrene and methacrylic acid, and stir until homogeneous. Then, add the first initiator at 70-90°C and react for 1-3 hours to obtain a homopolymer. The homopolymer is stably dispersed in water in particulate form to form a latex.

[0014] (2) Add a 10 wt% aqueous sodium hydroxide solution, then add isooctyl acrylate, or isooctyl acrylate and methacrylic acid, followed by water. Then, add the second initiator at 40-60°C and allow the reaction time to be 4-10 hours in an oxygen-free environment. After that, add the hard monomer and allow the reaction to proceed for 5-10 hours in an oxygen-free environment to obtain the polymer latex of the main substrate.

[0015] (3) After the reaction is complete, polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid are placed in a beaker in a volume ratio of 2:1:2, stirred for 15 minutes until homogeneous, then heated to 50°C and reacted for 1.5 to 3 hours. Next, the precipitate product is washed with distilled water until neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 5 to 20 hours to finally obtain the main substrate.

[0016] (4) The amphiphilic polymer reversible addition-cleavage chain transfer reagent is stirred and dissolved in water, then styrene, or styrene and methacrylic acid is added and stirred until completely dissolved. Then, the water bath is heated to 70-90°C, the first initiator is added, and the reaction is carried out for 1-3 hours to obtain a homopolymer. The homopolymer is stably dispersed in water in particulate form to form a latex.

[0017] (5) After adding a 10 wt% aqueous sodium hydroxide solution, isooctyl acrylate and water are added, followed by the second initiator. The water bath temperature is set to 40-60°C, and the reaction time is 4-10 hours under vacuum conditions to obtain the polymer latex reinforcing substrate.

[0018] (6) After the reaction is complete, polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid are placed in a beaker in a volume ratio of 2:1:2, stirred for 15 minutes until homogeneous, then heated to 40-60°C and reacted for 1.5-3 hours. Next, the precipitate product is washed several times with distilled water until neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 5-20 hours to finally obtain the reinforcing substrate.

[0019] (7) The main substrate and reinforcing substrate are dissolved in a dispersion medium, and the OCA optical adhesive is finally obtained by coating, forming a film, and drying in an argon gas environment.

[0020] Specifically, the structural formula of the amphiphilic polymer reversible addition-cleavage chain transfer reagent is R-(M n1 -bN n2 )-X.

[0021] R is an isopropionic acid group, an acetic acid group, a 2-cyanoacetic acid group or a 2-aminoacetic acid group. M n1 Among them, M is a methacrylic acid monomer or an acrylic acid monomer unit, and n1 is the average degree of polymerization of M. Also, the range of n1 is 10 to 30. N n2 Among them, N is a styrene monomer, a butyl acrylate monomer, methyl acrylate, isooctyl acrylate or a methyl methacrylate monomer unit, and n2 is the average degree of polymerization of N. Also, the range of n2 is 1 to 8. The X group is an alkyldithioester group or an alkyltrithioester group.

[0022] Furthermore, the dispersion medium is any one of ethyl ether, methyl tert-butyl ether, tetrahydrofuran, methyl ethyl ketone, ethyl acetate and methyl propionate.

[0023] Specifically, the first initiator in steps (1) and (4) is any one of ammonium persulfate, potassium persulfate, hydrogen peroxide and hydrogen peroxide derivatives. The second initiator in steps (2) and (5) is any one of 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane]2 hydrochloride, 2,2'-azobis(propane-2-carboxamidine) dihydrochloride, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, sodium bisulfate / potassium persulfate redox initiator and sodium persulfate / ammonium persulfate redox initiator. Furthermore, the Methacrylic acid can be replaced by any of other functional monomers.

Advantages of the Invention

[0024] The beneficial effects of the present invention are as follows.

[0025] (1) By reversible addition-fragmentation chain transfer emulsion polymerization, a block copolymer can be prepared as an OCA optical adhesive with controllable design. The soft segment of the block copolymer is formed by the polymerization of a soft monomer or a soft monomer and a functional monomer. The hard segment of the block copolymer is formed by the polymerization of a hard monomer or a hard monomer and a functional monomer. Also, compared with a homopolymer, the glass transition temperature of the block copolymer does not change significantly.

[0026] (2) By adding two blocks or a homopolymer, the modulus of the OCA optical adhesive can be significantly reduced. Also, by introducing a functional monomer, the glass transition temperature, cohesive force and peel strength of the OCA optical adhesive can be adjusted.

[0027] (3) By using a controllable living polymerization method that can be industrialized at low cost, the synthesized block copolymers can be compounded and produced continuously and on a large scale. The process is simpler and is advantageous for the customized production of OCA optical adhesives.

[0028] (4) The OCA optical adhesive produced by this method has the characteristics of flexibility, high transparency, high elongation, and high peel strength. Also, high resilience can be achieved, and the degree of resilience exceeds 95%.

Brief Description of the Drawings

[0029] [Figure 1] Figure 1 is the GPC curve of the block copolymer obtained in the present invention. [Figure 2] Figure 2 is the mechanical elongation curve of the block copolymer obtained in the present invention. [Figure 3] Figure 3 is the stress relaxation recovery curve of the block copolymer obtained in the present invention. [Figure 4] Figure 4 is a diagram of the results of the shear dynamic mechanical properties obtained in the present invention. [Figure 5] Figure 5 is a diagram of the results of the shear dynamic mechanical properties obtained in the present invention. [Figure 6] Figure 6 shows the results of the peel strength obtained in the present invention. [Figure 7] Figure 7 shows the stress relaxation recovery curve of the block copolymer obtained in the present invention. [Modes for carrying out the invention]

[0030] The following are specific embodiments of the present invention and further describe the technical means of the present invention, but the present invention is not limited to these embodiments. [Examples]

[0031] Preparation and performance of poly(styrene-β-isooctyl β-styrene) block copolymer In this example, the material was prepared using the RAFT reversible addition-fraction chain transfer emulsion polymerization method. The specific steps were as follows:

[0032] Step 1: Stirring 1 part by mass of amphiphilic polymer RAFT reagent (amphiphilic polymer reversible addition-cleavage chain transfer reagent) with 13 parts by mass of water until completely dissolved, then add 6 parts by mass of styrene, or add 6 parts by mass of styrene and 1 part by mass of methacrylic acid. The addition of methacrylic acid was to improve the adhesion between monomers. After that, stirring and mixing were performed. The structural formula of the amphiphilic polymer RAFT reagent was as follows.

[0033] [ka]

[0034] Step 2: The above raw materials were added to a four-necked flask, and nitrogen was introduced and oxygen removed at room temperature for 0.5 hours. Then, the water bath was heated to 70°C, and an aqueous potassium persulfate solution (0.02 parts by mass of potassium persulfate dissolved in 12 parts by mass of water) was added as an initiator and reacted for 1 hour. After that, an aqueous sodium hydroxide solution (1 part by mass of sodium hydroxide dissolved in 10 parts by mass of water) was slowly added, followed by the addition of 90 parts by mass of isooctyl acrylate and 50 parts by mass of water, and then 0.02 parts by mass of 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane]2-hydrochloride and reacted for 2 hours. Finally, 7 parts by mass of styrene was added and reacted for 1.5 hours to obtain polymer latex.

[0035] Step 3: Polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid were placed in a beaker in a volume ratio of 2:1:2, stirred for 15 minutes until homogeneous, then heated to 50°C and reacted in an air environment for 1.5 hours.

[0036] Step 4: After the reaction was complete, the precipitated product was washed multiple times with distilled water until it was neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 12 hours to finally obtain white polymer particles.

[0037] Step 5: The polymer was dissolved in butanone and then deposited into a 12 cm diameter polytetrafluoroethylene watch glass to form a film. After allowing most of the solvent to evaporate at room temperature, the film was dried and annealed in a 130°C vacuum oven to produce a polymer film with a thickness of approximately 0.8 to 1 mm.

[0038] Step 6: The polymer was dissolved in butanone, and an OCA optical adhesive film with a thickness of approximately 25 μm for peel strength testing was prepared using a bar coater.

[0039] The molecular weight of the polymers was characterized using a Waters 1525-2414-717 GPC gel permeation chromatography system. The eluate was tetrahydrofuran, and the system was calibrated with a narrow-distribution polystyrene standard.

[0040] The mechanical properties of the polymer were tested using a universal tester (Zwick / Roll Z020). The above steps were performed using standard cut samples. 5 The polymer film was cut into dumbbell-shaped test pieces. The GB16421-1996 test method was used, with a tensile speed of 30 mm / min. Each sample was tested at least three times.

[0041] The stress relaxation recovery properties of the polymer were tested using DMA (TAQ800). (See above steps) 6 The OCA optical adhesive film was cut into test pieces measuring 5 mm in width and 25 mm in length. The OCA optical adhesive was then stretched for 1 hour at strains of 100%, 200%, 300%, 400%, and 500%, and then maintained at a stress of 0 MPa for 1 hour, and the recovery curve was recorded.

[0042] The dynamic mechanical properties of the polymer were evaluated using a rotary rheometer (HAAKE MARS 60). The polymer film was cut into circular test pieces with a diameter of 2 cm, and the test frequency was set to 0.01 to 1 Hz and the test temperature to 25°C. The material loss coefficient tanδ was recorded during the test process.

[0043] The peel strength of the polymer was tested using an adhesive shear strength tester (KJ-1066A). (See above steps) 6 The OCA optical adhesive film was cut into test pieces measuring 25 mm in width and approximately 300 mm in length. The GB / T2792-2014 test method was used. Each sample was tested at least three times.

[0044] Figure 1 shows the GPC curves of the block copolymers obtained after the reaction of each block. Curve 1 in the figure is polystyrene (PSt), curve 2 is poly(styrene-β-isooctyl acrylate) (PSt-EHA), and curve 3 is poly(styrene-β-isooctyl acrylate-β-styrene) (PSt-EHA-PSt). As is clear from the figure, the molecular weight of the polymer generally increased as the number of blocks increased. This means that the product was a block copolymer. The molecular weights of each block were 1.5W, 22.5W, and 1.5W, respectively. Figure 2 shows the mechanical property curves of the block copolymers. As is clear from the figure, the polymers had a low modulus of 162.7 kPa, a low stress of 0.515 MPa, and a high elongation at break of nearly 1200%. Figure 3 shows the stress relaxation recovery curve of the OCA optical adhesive. As is clear from the drawing, the final deformation rate was only 4.55% at 100% tensile strain. At 200% tensile strain, the final deformation rate was 5.07%, at 300% tensile strain, it was 8.93%, at 400% tensile strain, it was 11.58%, and at 500% tensile strain, it was 17.05%. Figure 4 shows the shear dynamic mechanical properties of the OCA optical adhesive, with a shear modulus of only 26 kPa and a tanδ of only 0.2021.

[0045] When the film thickness was 25 μm, the peel strength of the OCA optical adhesive film was 6.40 N / 25 mm. [Examples]

[0046] Preparation and performance of poly(styrene-β-isooctyl β-styrene) block copolymer This example is basically the same as the steps in Example 1, but differs in that the parts by mass of styrene is 1 and the parts by mass of isooctyl acrylate is 18.

[0047] The characterization of the polymer's molecular weight and the testing of its mechanical properties in this example were similar to those in Example 1.

[0048] Figure 5 shows the shear dynamic mechanical properties in this embodiment, with a storage modulus of 45 kPa. Under a tensile strain of 300%, the sample fractured after being maintained for 47 minutes. When the film thickness was 25 μm, the peel strength of the OCA optical adhesive film was 10.01 N / 25 mm. [Examples]

[0049] A mixture of a 3-block copolymer and a poly(styrene-β-isooctyl acrylate) copolymer. The preparation of the three-block copolymer in this example was the same as in Example 1. Furthermore, the poly(styrene-β-isooctyl acrylate) copolymer was prepared using the RAFT reversible addition-fraction chain transfer emulsion polymerization method. The specific steps were as follows:

[0050] Step 1: After stirring until 1 part by mass of amphiphilic polymer RAFT reagent and 13 parts by mass of water were completely dissolved, 6 parts by mass of styrene were added and stirred and mixed. The structural formula of the amphiphilic polymer RAFT reagent was as follows.

[0051] [ka]

[0052] Step 2: The above raw materials were added to a four-necked flask, and nitrogen was introduced and oxygen removed at room temperature for 0.5 hours. Then, the water bath was heated to 70°C, and an aqueous potassium persulfate solution (0.02 parts by mass of potassium persulfate dissolved in 12 parts by mass of water) was added as an initiator and reacted for 1 hour. After that, an aqueous sodium hydroxide solution (1 part by mass of sodium hydroxide dissolved in 10 parts by mass of water) was slowly added, followed by the addition of 24 parts by mass of isooctyl acrylate and 50 parts by mass of water, and then 0.02 parts by mass of 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane]2-hydrochloride was added and reacted for 2 hours to obtain polymer latex.

[0053] Step 3: Polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid were placed in a beaker in a volume ratio of 2:1:2, stirred for 15 minutes until homogeneous, then heated to 50°C and reacted in an air environment for 1.5 hours.

[0054] Step 4: After the reaction was complete, the precipitated product was washed multiple times with distilled water until it was neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 12 hours to finally obtain white polymer particles.

[0055] Step 5: The particles of the 3-block copolymer from Example 1 and the 2-block copolymer from this example were dissolved in butanone in ratios of 75 / 25, 50 / 50, and 25 / 75, and then placed in a 12 cm diameter polytetrafluoroethylene watch glass to form a film. After most of the solvent was evaporated at room temperature, the film was dried and annealed in a vacuum oven at 130°C to produce a polymer film with a thickness of approximately 0.8 to 1 mm.

[0056] Step 6 The particles of the 3-block copolymer from Example 1 and the 2-block copolymer from this example were dissolved in butanone in ratios of 75 / 25, 50 / 50, and 25 / 75, and then an OCA optical adhesive film with a thickness of approximately 25 μm for peel strength testing was prepared using a bar coater.

[0057] The characterization of the polymer molecular weight and the performance testing of the polymer in this embodiment were similar to those in Example 1. The molecular weights of each block were 1W-4W, respectively.

[0058] As is clear from the comparison of peel strength performance with different ratios of two-block copolymers in Figure 6, when the addition ratio of two blocks was halved compared to the pure three-block copolymer, the peel strength improved from 6.40 N / 25 mm to 9.40 N / 25 mm. Figure 7 shows the stress relaxation recovery. As is clear from the figure, the recovery did not change with increasing addition ratio of two-block copolymer, and the final deformation rate was maintained at approximately 11% in all cases. [Examples]

[0059] Mixture of 3-block copolymer and poly(styrene-b-(isooctyl acrylate-r-acrylic acid)) copolymer The preparation of the three-block copolymer in this example was the same as in Example 1. Furthermore, the (styrene-β-isooctyl acrylate) copolymer was prepared using the RAFT reversible addition-fraction chain transfer emulsion polymerization method. The specific steps were as follows:

[0060] Step 1: After stirring until 1 part by mass of amphiphilic polymer RAFT reagent and 13 parts by mass of water were completely dissolved, 6 parts by mass of styrene were added and stirred and mixed. The structural formula of the amphiphilic polymer RAFT reagent was as follows.

[0061] [ka]

[0062] Step 2: The above raw materials were added to a four-necked flask, and nitrogen was introduced and oxygen removed at room temperature for 0.5 hours. Then, the water bath was heated to 70°C, and an aqueous solution of potassium persulfate (0.02 parts by mass of potassium persulfate dissolved in 12 parts by mass of water) was added as an initiator and the reaction was carried out for 1 hour. After that, an aqueous solution of sodium hydroxide (1 part by mass of sodium hydroxide dissolved in 10 parts by mass of water) was slowly added, followed by the addition of 48 parts by mass of isooctyl acrylate, 1 part by mass of acrylic acid, and 50 parts by mass of water. Finally, 0.02 parts by mass of 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane]2-hydrochloride was added and the reaction was carried out for 2 hours to obtain polymer latex.

[0063] Step 3: Polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid were placed in a beaker in a volume ratio of 2:1:2, stirred for 15 minutes until homogeneous, then heated to 50°C and reacted in an air environment for 1.5 hours.

[0064] Step 4: After the reaction was complete, the precipitated product was washed multiple times with distilled water until it was neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 12 hours to finally obtain white polymer particles.

[0065] Step 5: The particles of the 3-block copolymer from Example 1 and the 2-block copolymer from this example were dissolved in butanone in a 50 / 50 ratio, and then an OCA optical adhesive film with a thickness of approximately 25 μm for peel strength testing was prepared using a bar coater.

[0066] The characterization of the polymer's molecular weight and the testing of its mechanical properties in this example were similar to those in Example 1.

[0067] Compared to Example 1, the peel strength of the block copolymer improved to 12.21 N / 25 mm. In other words, the introduction of functional monomers further improved the functionality of the OCA optical adhesive.

[0068] The above embodiments are not intended to limit the present invention, but rather to illustrate it. Any modifications and changes made to the present invention within the spirit and scope of the claims are all within the scope of the protection of the present invention.

Claims

1. It is composed of a main substrate with a mass content of 20-100% and a reinforcing substrate with a mass content of 0-80%. The structural formula of the main matrix is M １ -b-M ２ -b-M ３ ...-b-M ｊ where the value range of j is 3 to 11, and M １ , M ２ , M ３ ...M ｊ are comonomers of the block copolymer. The number average molecular weight of the block copolymer of the main matrix is 80,000 to 800,000 g / mol. M １ , M ２ , M ３ ...M ｊ are respectively selected from soft monomers, hard monomers or functional monomers, and the mass content ratios of the soft monomer, hard monomer and functional monomer in the block copolymer are 70 to 98%, 2 to 30% and 0 to 5% respectively. The structural formula of the reinforcing substrate is N １ or N １ -b-N ２ The number-average molecular weight of the reinforcing substrate block copolymer is 100,000 to 400,000 g / mol, and N １ It is a soft monomer, N ２ The monomers are hard monomers or functional monomers, and the mass content of the soft monomers, hard monomers, and functional monomers in the block copolymer is 75-99.9%, 0.1-25%, and 0-5%, respectively. The main substrate and reinforcing substrate have terminal structures derived from an amphiphilic polymer reversible addition-cleavage chain transfer reagent represented by the structural formula: R-(M n1-b-N n2)-X. An OCA optical adhesive characterized in that R is an isopropionic acid group, an acetate group, a 2-cyanoacetic acid group, or a 2-aminoacetic acid group; in M ​​n1, M is a methacrylic acid monomer or an acrylic acid monomer unit, n1 is the average degree of polymerization of M, and the range of n1 is 10 to 30; in N n2, N is a styrene monomer, a butyl acrylate monomer, a methyl acrylate, an isooctyl acrylate, or a methyl methacrylate monomer unit, n2 is the average degree of polymerization of N, and the range of n2 is 1 to 8; and the X group is an alkyl dithioester group or an alkyl trithioester group.

2. The hard monomer comprises at least one selected from styrene, methyl acrylate, methyl methacrylate, acrylamide, acrylonitrile, and vinyl acetate, and the vitrification temperature range is 60 to 150°C. The soft monomer comprises at least one selected from ethyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, butadiene, isoprene, and ethylene-butene, and the vitrification temperature range is -90 to -30°C. The OCA optical adhesive according to claim 1, characterized in that the functional monomer comprises at least one selected from methacrylic acid, acrylic acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxy-1-methylethyl acrylat, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-(dimethylamino)ethyl methacrylate, methacrylamide, N-(hydroxymethyl)acrylamide, glycidyl methacrylate, and maleic anhydride.

3. A method for producing an OCA optical adhesive according to claim 1 or 2, (1) The amphiphilic polymer reversible addition-cleavage chain transfer reagent is dissolved in water, then styrene, or styrene and methacrylic acid is added and stirred until uniformly mixed, and the first initiator is added and the reaction is carried out at 70-90°C for 1-3 hours to obtain a homopolymer, the homopolymer which is stably dispersed in water in particulate form to form a latex (1) (2) Adding a 10 wt% aqueous sodium hydroxide solution, then adding isooctyl acrylate, or isooctyl acrylate and methacrylic acid, then adding water, adding a second initiator at 40-60°C, reacting for 4-10 hours in an oxygen-free environment, then adding a hard monomer and reacting for 5-10 hours in an oxygen-free environment to obtain the polymer latex of the main substrate (2), (3) After the reaction is complete, polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid are placed in a beaker in a volume ratio of 2:1:2, stirred for 15 min until homogeneous, then heated to 50°C and reacted for 1.5 to 3 hours, washed the precipitate product with distilled water until neutral, dried it, and then vacuum-dried in a vacuum oven at 120°C for 5 to 20 hours to finally obtain the main substrate. (4) The amphiphilic polymer reversible addition-cleavage chain transfer reagent is stirred and dissolved in water, then styrene, or styrene and methacrylic acid is added and stirred until completely dissolved, the water bath is set to 70-90°C, and then the first initiator is added and the reaction is carried out for 1-3 hours to obtain a homopolymer, the homopolymer which is stably dispersed in water in particulate form to form a latex (step (4) (5) Add a 10 wt% aqueous sodium hydroxide solution, then add isooctyl acrylate and water, then add the second initiator, set the water bath temperature to 40-60°C, and react for 4-10 hours under vacuum conditions to obtain the polymer latex of the reinforcing substrate (5), (6) After the reaction is complete, polymer latex, 30 wt% hydrogen peroxide solution, and 7.5 wt% hydrochloric acid are placed in a beaker in a volume ratio of 2:1:2, stirred for 15 min until homogeneous, then the temperature is raised to 40-60°C and the reaction is carried out for 1.5-3 hours, the precipitate product is washed several times with distilled water until neutral, dried, and then vacuum-dried in a vacuum oven at 120°C for 5-20 hours to finally obtain the reinforcing substrate. (7) A manufacturing method characterized by comprising the step (7) of dissolving the main substrate and the reinforcing substrate in a dispersion medium, and then coating, forming a film and drying in an argon gas environment to finally obtain an OCA optical adhesive.

4. The method for producing an OCA optical adhesive according to claim 3, characterized in that the dispersion medium in step (7) is one of ethyl ether, methyl tert-butyl ether, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, and methyl propionate.

5. The method for producing an OCA optical adhesive according to claim 3, characterized in that the first initiator in steps (1) and (4) is any of ammonium persulfate, potassium persulfate, hydrogen peroxide, and a hydrogen peroxide derivative, and the second initiator in steps (2) and (5) is any of 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] dihydrochloride, 2,2'-azobis(propane-2-carbamidine) dihydrochloride, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, sodium persulfate / potassium persulfate redox initiator, and sodium persulfate / ammonium persulfate redox initiator.

6. The method for producing an OCA optical adhesive according to claim 3, characterized in that the methacrylic acid in steps (1) and (2) can be replaced with any of the other functional monomers.

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