An OCA optical thin film and its preparation method

Abstract

The present invention relates to the technical field of optical films, and particularly relates to an OCA optical thin film and a preparation method thereof, which comprises a five-layer structure, namely a fluorine-containing shaped film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer and a fluorine-containing shaped film layer in sequence. The raw material for preparing the silicon-containing adhesive layer is a silicon-containing adhesive. The OCA optical thin film of the present invention has excellent anti-aging yellowing performance, high temperature resistance performance and flexibility, and in addition, has better light transmittance, transmittance, flame retardant performance and low refractive index.

Description

Technical Field

[0001] The present invention relates to the technical field of optical films, and particularly relates to an OCA optical thin film and a preparation method thereof. Background Art

[0002] With the continuous development of technology, there are more and more large electronic devices such as smart phones, tablet computers, and smart TVs. The screen is one of the most important components in such electronic products. The vast majority of screens are made of multiple layer structures such as display components, touch films, polarizers, cover plates, etc. These components need to be bonded together, so some adhesives are required. Among them, OCA glue is one of the more common adhesives used in the flexible screen field, and it also has a very broad application prospect in the fields of aerospace, transportation, etc.

[0003] Traditional OCA mainly includes acrylic systems and polyurethane systems. In particular, acrylic and urea systems are widely used because of their good transparency, easy design, low price, etc. However, traditional OCA glue has poor adhesion, so it needs to be improved.

[0004] For example, CN116200140A discloses "an OCA glue, an OCA layer, an OCA film and applications", which is prepared by using acrylate monomer A, acrylate monomer B, hydrophilic acrylate monomer, curing agent, tackifier, elastic resin, organic solvent, etc. as main raw materials. This OCA layer has good adhesion and creep recovery performance, and is not easy to appear cracks, deformation and other phenomena.

[0005] Another example is that CN107353854B discloses "an OCA optical glue and an OCA optical glue film", which is prepared by using saturated polyacrylate containing crosslinkable groups, oligomer containing unsaturated bonds, diluent, photoinitiator, crosslinking agent. This optical film has high viscosity and good peelability.

[0006] However, in addition to the above problems of traditional OCA, such adhesives also have poor heat resistance, and the poor heat resistance will further cause the problem of yellowing of the film material, which limits the application of OCA. And the above-mentioned disclosed patents also do not mention and solve this problem.

[0007] Therefore, it is urgent to develop an OCA optical thin film with excellent anti-aging yellowing performance, high temperature resistance, flexibility, and in addition, having better light transmittance, transmittance, flame retardant performance and low refractive index. Summary of the Invention

[0008] The main purpose of the present invention is to provide an OCA optical thin film and a preparation method thereof. This OCA optical thin film has excellent anti-aging yellowing performance, high temperature resistance, flexibility, and in addition, has better light transmittance, transmittance, flame retardant performance and low refractive index.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] On the one hand, the present invention provides an OCA optical film, which includes a five-layer structure, namely a fluorine-containing special-shaped film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer, and a fluorine-containing special-shaped film layer in sequence; the raw material for preparing the silicon-containing adhesive layer is a silicon-containing adhesive.

[0011] Traditional OCA adhesives are mainly acrylic systems and polyurethane systems, but the adhesives in this system have poor heat resistance and will further cause the problem of yellowing of the film material, which limits the application of OCA.

[0012] The OCA optical film of the present application uses a modified silicon-containing adhesive layer to bond each layer, and at the same time uses a modified PET matrix in combination, which can further improve the light transmittance of the OCA adhesive. The reason may be that the silicon-containing adhesive layer of the present invention has a higher light transmittance. When traditional PET is used, its light transmittance will be low due to the low light transmittance of PET, resulting in a decrease in the overall light transmittance of the OCA film. The modified PET matrix of the present application has a higher light transmittance, and after being used in combination, it can maintain excellent light transmittance of the OCA film. In addition, the OCA film of the present application has excellent anti-aging yellowing performance, high temperature resistance, and flexibility.

[0013] In some embodiments, the thickness of the silicon-containing adhesive layer is 100 - 3000 μm; the thickness of the fluorine-containing special-shaped film layer is 1000 - 3000 μm.

[0014] In some embodiments, the thickness ratio of the silicon-containing adhesive layer to the modified PET matrix is 1:(0.1 - 10).

[0015] By regulating the thickness ratio of the silicon-containing adhesive layer to the modified PET matrix, on the one hand, it can prevent the bonding force from being too low and resulting in a poor bonding effect, and on the other hand, it can prevent more reflection and scattering of light when passing through the OCA film, resulting in a decrease in the light transmittance of the OCA film.

[0016] In some embodiments, the silicon-containing adhesive includes a modified inorganic silicon adhesive and an organosilicon adhesive with a mass ratio of 1:(0.8 - 1.5); the modified inorganic silicon adhesive is composed of a hollow core layer and a shell layer; the outer layer of the shell layer is grafted with the structure shown in Formula I:

[0017]

[0018] Among them, each R1 is independently hydrogen, methyl, halogen, amino group, epoxy group, cyclohexene oxide, methacryl group, propenyl group, hydroxyl group, siloxy group, isocyanate group, nitrile group, nitro group, phenyl group, an alkyl group with 1 to 40 carbon atoms, a vinyl group with 2 to 40 carbon atoms, an alkoxy group with 1 to 40 carbon atoms, a cycloalkyl group with 3 to 40 carbon atoms, a heterocycloalkyl group with 3 to 40 carbon atoms, an aryl group with 6 to 40 carbon atoms or a heteroaryl group with 3 to 40 carbon atoms;

[0019] Each R2 is independently hydrogen, methyl, halogen, amino group, epoxy group, cyclohexene oxide, methacryl group, propenyl group, hydroxyl group, siloxy group, isocyanate group, nitrile group, nitro group, phenyl group, an alkyl group with 1 to 40 carbon atoms, a vinyl group with 2 to 40 carbon atoms, an alkoxy group with 1 to 40 carbon atoms, a cycloalkyl group with 3 to 40 carbon atoms, a heterocycloalkyl group with 3 to 40 carbon atoms, an aryl group with 6 to 40 carbon atoms or a heteroaryl group with 3 to 40 carbon atoms, and it must contain any one of methyl, vinylmethyl, styrene or perfluorovinylmethyl;

[0020] Each R3 is independently hydrogen, methyl, halogen, amino group, epoxy group, cyclohexene oxide, methacryl group, propenyl group, hydroxyl group, siloxy group, isocyanate group, nitrile group, nitro group, phenyl group, an alkyl group with 1 to 40 carbon atoms, a vinyl group with 2 to 40 carbon atoms, an alkoxy group with 1 to 40 carbon atoms, a cycloalkyl group with 3 to 40 carbon atoms, a heterocycloalkyl group with 3 to 40 carbon atoms, an aryl group with 6 to 40 carbon atoms or a heteroaryl group with 3 to 40 carbon atoms, and it must contain an allyl group or a methacryl group;

[0021] x, y, and z are each independently an integer from 1 to 100; p is an integer from 1 to 200; is the grafting site with the shell;

[0022] The structure of structural unit A is as follows

[0023] Among them is the chemical bond connection site; structural unit B is the crosslinking agent residue.

[0024] In some embodiments, the preparation method of the silicon-containing adhesive includes the following steps by weight parts:

[0025] S1. Prepare a suspension by mixing the products A and B obtained by hydrolysis and polycondensation of any two of tin tetrachloride, zirconium tetrachloride, tetraethyl orthosilicate and tetrabutyl titanate with water, heat it to the reflux state, continue stirring for 2 to 3 h, after the reaction is completed, centrifuge, wash with ethanol and then dry, and calcine at 500 to 600 °C to obtain an inorganic silicon adhesive;

[0026] S2. Mix 80 - 90 parts of organosiloxane containing R1 group, 80 - 90 parts of organosiloxane containing R2 group, and 80 - 90 parts of organosiloxane containing R3 group, add 170 - 180 parts of toluene, 45 - 50 parts of deionized water, and 2 - 4 parts of concentrated sulfuric acid. Heat up to 70 - 80 °C and stir at a constant temperature for 1 - 2 h. After the reaction is completed, filter, concentrate under reduced pressure, dry, and then add 35 - 45 parts of the compound containing structural unit A and 160 - 180 parts of heptane. Heat up to 40 - 50 °C and continue to react for 12 - 14 h. After the reaction is completed, cool to room temperature to obtain a polysiloxane copolymer precursor;

[0027] S3. Under an inert protective gas atmosphere, mix 60 - 70 parts of tetraethyl orthosilicate, 180 - 220 parts of the inorganic silicon binder in step S1, 80 - 90 parts of the polysiloxane copolymer precursor in step S2, and a crosslinking agent, add triethylamine, heat up to 70 - 80 °C, and stir at a constant temperature for 1 - 3 h. After the reaction is completed, obtain a modified inorganic silicon binder;

[0028] S4. Mix and stir the organosilicon binder and the inorganic silicon binder in step S3 evenly to obtain a silicon-containing binder.

[0029] The structure of the organosilicon binder is shown in formula I:

[0030]

[0031] In some embodiments, in step S3, the crosslinking agent has any one of the following structures:

[0032] (1)

[0033] (2) where n is an integer from 0 to 8, and R4 is any one of -COOH, -OH, -SH, or -NCO.

[0034] In some embodiments, the preparation method of the compound containing structural unit A includes the following steps: Mix 3 - amino - 1 - propanol and 2,6 - di - tert - butyl - 4 - chlorophenol, add them to N,N - dimethylformamide, add an acid - binding agent, heat up to 35 - 45 °C, and stir at a constant temperature for 12 - 14 h. After the reaction is completed, filter to obtain the compound containing structural unit A.

[0035] In some embodiments, the preparation method of the modified PET matrix, by mass parts, includes the following steps: Melt - blend 1 - 3 parts of ionomer, 70 - 74 parts of PET, and 1 - 2 parts of chain extender, extrude through a twin - screw extruder, and cool and cut into shape.

[0036] The OCA film of the present application is prepared by compounding a fluorine-shaped film layer, a silicon-containing adhesive layer, and a modified PET matrix. The fluorine-shaped film layer and the silicon-containing adhesive layer have high light transmittance. Although traditional PET has a certain light transmittance, there is still room for improvement.

[0037] The modified PET matrix of the present application can obtain a modified PET matrix with low transparency and refractive index by melt blending an ionomer, PET, and a chain extender and extrusion molding, which can improve the light transmittance of the OCA film and reduce the refractive index. At the same time, it can also enhance the flame retardant performance of the OCA film. The reason may be that the PET molecular chain structure is regular and has strong crystallization performance. However, due to the rigidity of its molecular chain, the movement ability of the molecular chain is hindered. The self-made ionomer structure in the present application contains a small amount of ionizable groups, which can form physical crosslinks with the PET matrix through hydrogen bond interaction, improving the light transmittance of PET. At the same time, it can also interact with the silicon-containing adhesive layer, increasing the adhesion between the modified PET matrix and the silicon-containing adhesive layer. In addition, the ionomer structure also contains a certain amount of N element, which improves the flame retardant performance of the OCA film.

[0038] In some embodiments, the preparation method of the ionomer includes the following steps:

[0039] A1. Mix N-methylallylamine, diethanolamine, and cyanuric chloride, add N,N-dimethylformamide, then add an acid-binding agent, heat to 40-45 °C and stir at a constant temperature for 14-16 h. After the reaction is completed, concentrate under reduced pressure and dry to obtain compound A;

[0040] A2. Mix compound A, 3-methyl-1-butene, and toluene, add a catalyst, heat to 80-90 °C and stir at a constant temperature for 2-3 h. After the reaction is completed, obtain the ionomer.

[0041] In some embodiments, in step A1, the molar ratio of N-methylallylamine, diethanolamine, and cyanuric chloride is (0.9-1.1):(2-2.2):1.

[0042] In some embodiments, in step A2, the molar ratio of compound A and 3-methyl-1-butene is 1:(2-2.4).

[0043] In some embodiments, in step A2, the catalyst is benzoyl peroxide and / or ammonium persulfate.

[0044] On the other hand, the present invention provides a preparation method of an OCA optical film, including the following steps: apply a layer of silicon-containing adhesive on the upper and lower surfaces of the modified PET matrix to obtain a silicon-containing adhesive layer. After scraping flat, attach the fluorine-shaped film layer to the silicon-containing adhesive layer, and cure at 200-300 °C for 1-2 h to obtain the OCA optical film.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) The OCA optical film of the present invention is composed of a fluorine-containing special-shaped film layer, a silicon-containing adhesive layer and a modified PET matrix through bonding and compounding. The OCA optical film has excellent anti-aging yellowing performance, high-temperature resistance performance and flexibility. In addition, it has better light transmittance, transmittance, flame retardant performance and low refractive index.

[0047] (2) By regulating the thickness ratio of the silicon-containing adhesive layer to the modified PET matrix, the present invention can, on the one hand, prevent the bonding effect from deteriorating due to low bonding force, and on the other hand, prevent more reflection and scattering from occurring when light passes through the OCA film, resulting in a decrease in the light transmittance of the OCA film.

[0048] (3) The self-made ionomer structure in the present invention contains a small amount of ionizable groups, which can form physical cross-links with the PET matrix through hydrogen bond action, improving the light transmittance of PET. At the same time, it can also act with the silicon-containing adhesive layer to increase the bonding force between the modified PET matrix and the silicon-containing adhesive layer. In addition, the ionomer structure also contains a certain amount of N element, improving the flame retardant performance of the OCA film.

[0049] (4) On the one hand, the silicon-containing adhesive of the present invention has a core-shell structure, and can improve the reflectivity of the binder and reduce the refraction efficiency through the complementarity and synergy of various different elements; on the other hand, the outermost layer of the silicon-containing adhesive has a modified POSS structure, and the double bond therein can improve the bonding ability of the adhesive. The structure also has a hindered phenol group, improving the anti-aging yellowing performance of the adhesive. At the same time, the chemical structure of the POSS group endows the adhesive with a certain toughness; on the other hand, the cross-linking agent cross-links the silicon-containing adhesive, increasing its molecular weight and viscosity while the phenyl group therein can form π-π stacking, improving the temperature resistance performance of the adhesive. Detailed implementation manners

[0050] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0051] In the following preparation examples, examples and comparative examples, PET was purchased from Ningbo Jianxing Plastic Co., Ltd.; CESA-extend chain extender was purchased from Shenzhen Huixin Plastic Chemical Co., Ltd.; acrylic adhesive was purchased from Juli (Dongguan) New Material Technology Co., Ltd.

[0052] Preparation Example 1

[0053] The preparation method of the compound containing structural unit A comprises the following steps: Mix 0.3 mol of 3-amino-1-propanol and 0.36 mol of 2,6-di-tert-butyl-4-chlorophenol and add them to 300 mL of N,N-dimethylformamide. Add 0.42 mol of sodium bicarbonate, heat up to 40 °C and stir at a constant temperature for 13 h. After the reaction is completed, filter to obtain the compound containing structural unit A.

[0054] Preparation Example 2

[0055] The silicone-containing binder comprises a modified inorganic silicone binder and an organosilicone binder with a mass ratio of 1:1.3; the modified inorganic silicone binder consists of a hollow core layer and a shell layer; the outer layer of the shell layer is grafted with the structure shown in Formula I:

[0056] Wherein, R1 is methyl, R2 is methyl and hydrogen, R3 is propenyl and hydroxyl; x is 40, y is 40, z is 40; p is 30; is the grafting site of the shell layer; the structure of structural unit A is as follows

[0057] Wherein is the chemical bond connection site; structural unit B is the crosslinking agent residue.

[0058] The preparation method of the silicone-containing binder comprises the following steps according to weight parts:

[0059] S1. Mix 100 parts of tetraethyl orthosilicate, 2 L of deionized water and 70 mL of 2 mol / L sodium hydroxide solution, and carry out hydrolysis and polycondensation at room temperature for 3 h. After centrifugation, obtain product A. Prepare material A by mixing 300 parts of tetrabutyl titanate and 900 parts of ethanol. Prepare material B by mixing 900 parts of ethanol, 90 parts of deionized water and 72 parts of glacial acetic acid. Add material B to material A and stir at room temperature for 2 h. After centrifugation, obtain product B. Mix product A and product B with 2.5 L of deionized water to form a suspension, heat up to the reflux state, continue to stir for 2.5 h. After the reaction is completed, centrifuge, wash with ethanol and dry, and calcine at 550 °C to obtain the inorganic silicone binder;

[0060] S2. Mix 85 parts of dimethyldimethoxysilane, 85 parts of methyldiethoxysilane and 85 parts of allyltriethoxysilane, add 175 parts of toluene, 47 parts of deionized water and 3 parts of 98 wt% concentrated sulfuric acid, heat up to 75 °C and stir at a constant temperature for 1.5 h. After the reaction is completed, filter, concentrate under reduced pressure and dry, then add 40 parts of the compound containing structural unit A and 170 parts of heptane, heat up to 45 °C and continue to react for 13 h. After the reaction is completed, cool to room temperature to obtain the polysiloxane copolymer precursor;

[0061] S3. Under an N2 gas atmosphere, mix 7 parts of tetraethyl orthosilicate, 200 parts of the inorganic silicon binder in step S1, 85 parts of the polysiloxane copolymer precursor in step S2, and 0.2 part of p-xylene glycol, add 20 parts of triethylamine, heat up to 75 °C, and stir at a constant temperature for 2 h. After the reaction ends, a modified inorganic silicon binder is obtained.

[0062] S4. Mix and stir the organosilicon binder and the inorganic silicon binder in step S3 evenly to obtain a silicon-containing binder.

[0063] Among them, the compound containing structural unit A is prepared from Preparation Example 1; the structure of the organosilicon binder is shown in Formula II:

[0064]

[0065] Preparation Example 3

[0066] A method for preparing an ionomer, comprising the following steps:

[0067] A1. Mix 0.5 mol of N-methylallylamine, 1.05 mol of diethanolamine, and 0.5 mol of cyanuric chloride, add 1 L of N,N-dimethylformamide, then add 0.7 mol of sodium carbonate, heat up to 42 °C and stir at a constant temperature for 15 h. After the reaction ends, concentrate under reduced pressure and dry to obtain compound A.

[0068] A2. Mix 0.5 mol of compound A, 1.1 mol of 3-methyl-1-butene, and 1.8 L of toluene, add 0.5 g of benzoyl peroxide, heat up to 85 °C and stir at a constant temperature for 2.5 h. After the reaction ends, an ionomer is obtained.

[0069] Preparation Example 4

[0070] A method for preparing an ionomer, the specific implementation method is the same as that of Preparation Example 3, except that (3-aminocyclobutane-1,1-diyl)dimethanol in equimolar amount is used instead of 3-methyl-1-butene.

[0071] Preparation Example 5

[0072] A method for preparing an ionomer, the specific implementation method is the same as that of Preparation Example 3, except that the amount of 3-methyl-1-butene is 0.5 mol.

[0073] Preparation Example 6

[0074] A method for preparing an ionomer, the specific implementation method is the same as that of Preparation Example 3, except that 1,3-dichloro-2-(chloromethyl)propane is used instead of cyanuric chloride.

[0075] Preparation Example 7

[0076] The preparation method of the ionomer is the same as that of Preparation Example 3, except that the diethanolamine is 0.5 mol.

[0077] Preparation Example 8

[0078] The preparation method of the modified PET matrix includes the following steps by mass parts: melting and blending 2 parts of the ionomer, 72 parts of PET and 1.5 parts of CESA-extend chain extender, extruding through a twin-screw extruder, and cooling and cutting into shape.

[0079] Among them, the ionomer is prepared from Preparation Example 3.

[0080] Preparation Example 9

[0081] The preparation method of the modified PET matrix is the same as that of Preparation Example 8, except that the ionomer is prepared from Preparation Example 4.

[0082] Preparation Example 10

[0083] The preparation method of the modified PET matrix is the same as that of Preparation Example 8, except that the ionomer is prepared from Preparation Example 5.

[0084] Preparation Example 11

[0085] The preparation method of the modified PET matrix is the same as that of Preparation Example 8, except that the ionomer is prepared from Preparation Example 6.

[0086] Preparation Example 12

[0087] The preparation method of the modified PET matrix is the same as that of Preparation Example 8, except that the ionomer is prepared from Preparation Example 7.

[0088] Example 1

[0089] An OCA optical film includes a five-layer structure, which are an FEP film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer and an FEP film layer from top to bottom in sequence; the raw material for preparing the silicon-containing adhesive layer is a silicon-containing adhesive.

[0090] The preparation method of the OCA optical film includes the following steps: applying a layer of silicon-containing adhesive with a thickness of 1500 μm on each of the upper and lower surfaces of the modified PET matrix with a thickness of 7500 μm to obtain a silicon-containing adhesive layer, scraping it flat, and then attaching a 2000 μm FEP film layer to the silicon-containing adhesive layer, and curing it at 250 °C for 1.5 h to obtain the OCA optical film.

[0091] Among them, the modified PET matrix is prepared according to Preparation Example 8, and the silicon-containing adhesive is prepared according to Preparation Example 2.

[0092] Example 2

[0093] An OCA optical film includes a five-layer structure, which are, from top to bottom, an FEP film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer, and an FEP film layer; the raw material for preparing the silicon-containing adhesive layer is the silicon-containing adhesive.

[0094] The preparation method of the OCA optical film includes the following steps: apply a layer of silicon-containing adhesive with a thickness of 100 μm on each of the upper and lower surfaces of the modified PET matrix with a thickness of 1000 μm to obtain the silicon-containing adhesive layer. After scraping flat, attach a 1000-μm FEP film layer to the silicon-containing adhesive layer, and cure it at 200 °C for 2 h to obtain the OCA optical film.

[0095] Among them, the modified PET matrix is prepared according to Preparation Example 8, and the silicon-containing adhesive is prepared according to Preparation Example 2.

[0096] Example 3

[0097] An OCA optical film includes a five-layer structure, which are, from top to bottom, an FEP film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer, and an FEP film layer; the raw material for preparing the silicon-containing adhesive layer is the silicon-containing adhesive.

[0098] The preparation method of the OCA optical film includes the following steps: apply a layer of silicon-containing adhesive with a thickness of 3000 μm on each of the upper and lower surfaces of the modified PET matrix with a thickness of 300 μm to obtain the silicon-containing adhesive layer. After scraping flat, attach a 3000-μm FEP film layer to the silicon-containing adhesive layer, and cure it at 300 °C for 1 h to obtain the OCA optical film.

[0099] Among them, the modified PET matrix is prepared according to Preparation Example 8, and the silicon-containing adhesive is prepared according to Preparation Example 2.

[0100] Example 4

[0101] An OCA optical film and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the modified PET matrix is prepared according to Preparation Example 9.

[0102] Example 5

[0103] An OCA optical film and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the modified PET matrix is prepared according to Preparation Example 10.

[0104] Example 6

[0105] An OCA optical film and its preparation method. The specific implementation manner is the same as that of Example 1, except that the modified PET substrate is prepared from Preparation Example 11.

[0106] Example 7

[0107] An OCA optical film and its preparation method. The specific implementation manner is the same as that of Example 1, except that the modified PET substrate is prepared from Preparation Example 12.

[0108] Comparative Example 1

[0109] An OCA optical film and its preparation method. The specific implementation manner is the same as that of Example 1, except that a PET substrate is used instead of the modified PET substrate.

[0110] The preparation method of the PET substrate includes the following steps by mass parts: melting and blending 72 parts of PET and 1.5 parts of dicyandiamide through a twin-screw extruder, extruding, cooling and cutting into shape.

[0111] Comparative Example 2

[0112] An OCA optical film and its preparation method. The specific implementation manner is the same as that of Example 1, except that an acrylic adhesive is used instead of the silicone-containing adhesive.

[0113] Performance test:

[0114] (1) UV resistance: Place the OCA optical film in an ultraviolet aging chamber, use a 1kW lamp tube, at a distance of 50 cm, continuously irradiate and age for 100 h, and measure the yellowing index of the adhesive layer according to the standard of GB / T7975-2005;

[0115] (2) Peel strength test: Test the peel strength of the silicone-containing adhesive layer in the optical film according to GB / T7122-1996 "Determination of peel strength of high-strength adhesives - Floating roller method";

[0116] (3) Elongation test: Cut the OCA optical film into dumbbell shape, and test it at a rate of 50 mm / min using a tensile testing machine. The greater the elongation, the better the toughness;

[0117] (4) Heat resistance: Place the OCA optical film in method (3) in an environment of 300 °C for 3 days, and test the elongation again;

[0118] (5) Transparency test: Measure using a photoelectric haze meter of model NDH2000;

[0119] (6) Transmittance test: Measure using a spectrophotometer UV3100, wavelength range 400 - 700 nm;

[0120] (7) Flame retardancy test: According to UL-94 test.

[0121] The binders of each example and comparative example were tested according to the above test method, and the results are shown in Table 1.

[0122] Table 1

[0123]

[0124]

[0125] According to the above results, it was found that the OCA optical films of Examples 1 to 3 had good anti-aging yellowing performance, flexibility, high temperature resistance, good light transmittance, high bonding strength between layers, and good flame retardancy; in Example 4, due to the use of equimolar (3-aminocyclobutane-1,1-diyl) dimethanol instead of 3-methyl-1-butene, the flexibility of the OCA optical film decreased, but due to the increase in ionic bonds therein, the peel strength and light transmittance of the OCA optical film increased; in Example 5, due to the change in the molar ratio of Compound A and 3-methyl-1-butene, the light transmittance and transmittance of the OCA optical film decreased slightly; in Example 6, due to the use of 1,3-dichloro-2-(chloromethyl) propane instead of cyanuric chloride, the flame retardancy of the OCA optical film decreased; in Example 7, due to the change in the molar ratio of N-methylallylamine, diethanolamine and cyanuric chloride, the light transmittance, transmittance and peel force of the OCA optical film decreased; in Comparative Example 1, due to the use of a PET layer instead of a modified PET matrix, the peel force between the base layers of the OCA optical film decreased, and at the same time its light transmittance, transmittance and flame retardancy decreased; in Comparative Example 2, due to the use of an acrylic binder layer instead of a silicone-containing binder layer, the light transmittance, transmittance, anti-aging yellowing performance, high temperature resistance and flexibility of the OCA optical film all decreased.

[0126] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An OCA optical film, characterized in that: The invention comprises a five-layer structure, which is a fluorine-containing special-shaped film layer, a silicon-containing adhesive layer, a modified PET matrix, a silicon-containing adhesive layer and a fluorine-containing special-shaped film layer in sequence; the raw material for preparing the silicon-containing adhesive layer is a silicon-containing adhesive; The preparation method of the modified PET matrix comprises the following steps, calculated by weight: melt-blending 1-3 parts of ionomer, 70-74 parts of PET and 1-2 parts of chain extender, extruding through a twin-screw extruder, cooling and cutting to form; The preparation method of the ionomer comprises the following steps: A1, N-methylallylamine, diglycolamine and cyanuric chloride were mixed, N,N-dimethylformamide was added, and then an acid binding agent was added, the temperature was raised to 40-45°C and stirred at a constant temperature for 14-16 hours, and after the reaction was completed, the mixture was concentrated and dried under reduced pressure to obtain compound A; A2. Compound A, 3-methyl-1-butene and toluene are mixed, and then a catalyst is added. The mixture is heated to 80-90°C and stirred at a constant temperature for 2-3 hours. After the reaction is completed, an ionomer is obtained.

2. The OCA optical film according to claim 1, characterized in that: The thickness of the silicon-containing adhesive layer is 100-3000 μm; the thickness of the fluorine-containing special-shaped film layer is 1000-3000 μm.

3. The OCA optical film according to claim 1, characterized in that: The ratio of the thickness of the silicon-containing adhesive layer to the thickness of the modified PET substrate is 1:(0.1-10).

4. The OCA optical film according to claim 1, characterized in that: The silicon-containing adhesive comprises a modified inorganic silicon adhesive and an organic silicon adhesive in a mass ratio of 1:(0.8-1.5); the modified inorganic silicon adhesive consists of a hollow core layer and a shell layer; the outer layer of the shell layer is grafted with a structure shown in Formula I: （Ⅰ）； Wherein, R1 is independently hydrogen, methyl, halogen, amine, epoxy, cyclohexene oxide, methacryl, acryl, hydroxyl, siloxy, isocyanate, nitrile, nitro, phenyl, C1-C40 alkyl, C2-C40 vinyl, C1-C40 alkoxy, C3-C40 cycloalkyl, C3-C40 heterocycloalkyl, C6-C40 aryl or C3-C40 heteroaryl; R2 is independently hydrogen, methyl, halogen, amine, epoxy, cyclohexene oxide, methacryl, acryl, hydroxyl, siloxy, isocyanate, nitrile, nitro, phenyl, C1-C40 alkyl, C2-C40 vinyl, C1-C40 alkoxy, C3-C40 cycloalkyl, C3-C40 heterocycloalkyl, C6-C40 aryl or C3-C40 heteroaryl, and must contain any one of methyl, vinylmethyl, styrene or perfluorovinylmethyl; R3 is independently hydrogen, methyl, halogen, amine, epoxy, cyclohexene oxide, methacryl, propenyl, hydroxyl, siloxy, isocyanate, nitrile, nitro, phenyl, C1-C40 alkyl, C2-C40 vinyl, C1-C40 alkoxy, C3-C40 cycloalkyl, C3-C40 heterocycloalkyl, C6-C40 aryl or C3-C40 heteroaryl, including one propenyl or methacryl; x, y, z are each independently an integer between 1 and 100; p is an integer between 1 and 200; is the grafting site with the shell; The structure of structural unit A is as follows ,in A is a chemical bond connection site; structural unit B is a cross-linker residue.

5. The OCA optical film according to claim 1, characterized in that: In step A1, the molar ratio of N-methylallylamine, diglycolamine and cyanuric chloride is (0.9-1.1):(2-2.2):

1.

6. The OCA optical film according to claim 1, characterized in that: In step A2, the molar ratio of compound A to 3-methyl-1-butene is 1:(2-2.4).

7. The OCA optical film according to claim 1, characterized in that: In step A2, the catalyst is benzoyl peroxide and / or ammonium persulfate.

8. A method for preparing an OCA optical film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: applying a layer of silicon-containing adhesive on the upper and lower surfaces of a modified PET substrate to obtain a silicon-containing adhesive layer, flattening the layer and attaching a fluorine-containing special-shaped film layer to the silicon-containing adhesive layer, curing the film at 200-300°C for 1-2 hours, and obtaining an OCA optical film.

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