Optical adhesive tape with optical radiation resistance and high creep restorability and preparation method thereof

Abstract

The invention relates to the technical field of adhesive tape production, in particular to an optical adhesive tape with optical radiation resistance and high creep restorability and a preparation method of the optical adhesive tape. The pressure-sensitive adhesive layer is prepared by adopting the acrylate pressure-sensitive adhesive with light radiation resistance, yellowing resistance, high creep restorability, high adhesive property and low adhesive overflow and the tackifying resin and selecting polyisocyanate, an epoxy curing agent or a metal salt curing agent as a curing agent; therefore, the pressure-sensitive adhesive layer has excellent optical properties, high creep restorability and strong bonding properties under high temperature, high humidity and intense radiation. The optical adhesive tape prepared by the preparation method disclosed by the invention is continuously irradiated for 1000h under three harsh conditions of irradiance 2.4 W / m < 2 > / nm (at the wavelength of 420nm), high radiation at a high temperature of 60 DEG C, 90% RH and high humidity, still keeps good optical properties such as yellowness, transmissivity and haze, has high adhesive property, and does not generate adhesive overflow; and when the strain of 400% at 65 DEG C is kept for 60 min, and the product is naturally cooled to the room temperature of 25 DEG C after the stress is removed, the creep recovery rate can reach 65% or above, so that the excellent impact resistance of the product is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive tape production, in particular to an optical adhesive tape resistant to light radiation and having high creep recovery and a preparation method thereof. Background Art

[0002] LCD is the most mature, most supported and most widely used product type in the field of new flat panel display devices. However, the LCD panel itself does not have the characteristic of emitting light, so a light source must be added to the LCD panel to achieve the display effect. The backlight unit (BLU) is a key component that provides light source to the back of the LCD display, and its light effect directly affects the visual effect of the liquid crystal display module.

[0003] The LCD backlight module is mainly composed of a backlight source, a lamp tube, a bottom cover, a reflective film, a light guide plate, a diffusion film, and a brightness enhancement film, etc. The bottom cover and one end of the light guide plate need to be fixed together using an optical tape.

[0004] For example, Chinese patent publication number CN100410781C discloses an adhesive tape, (a) which combines light reflective and light shielding properties and is used for bonding between an LCD panel and a backlight housing of an LCD assembly, (b) and includes a liner formed by laminating a light reflective layer and a light shielding layer, and an adhesive layer provided on at least one surface of the liner, (c) wherein the light reflective layer is formed of a white resin film having a thickness of 10-30 μm and a tensile strength of at least 10.0 N / 10 mm.

[0005] The reflective layer and adhesive layer of the adhesive tape prepared by this patent are mainly used for bonding LCD backlight modules. However, light will continuously shine on the tape during the use of the equipment. Due to long-term exposure to light, the optical properties of traditional optical tapes such as yellowness, haze, transmittance, and viscosity will change, thereby affecting the brightness and brilliance of the entire display module.

[0006] In addition, electronic devices may fall and be hit during use, causing the light guide plate and the bottom cover to be misaligned, which requires the tape that fixes the module to have good creep recovery and impact resistance. At the same time, the environment in which display devices are used varies. When used for a long time, the device will also generate a lot of heat. The temperature of the entire module is very high. In addition, under the influence of the temperature and humidity in the environment, the tape will overflow under the influence of the triple factors of light, heat and humidity. In severe cases, it will overflow onto the reflective film and be reflected on the screen, thus affecting the consumer's experience.

[0007] Therefore, providing a tape product with a wide range of applications, resistance to light radiation, resistance to yellowing, high creep recovery, high bonding performance, low glue overflow, and the ability to be widely used in the field of LCD display screens has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0008] The object of the present invention is to provide an optical adhesive tape with high light radiation resistance and creep recovery and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] An optical tape resistant to light radiation and having high creep recovery comprises a substrate, wherein the substrate is an optical grade polyester film PET substrate with a thickness of 6 to 20 μm, an acrylic pressure-sensitive adhesive layer with a thickness of 14 to 60 μm is adhered to one side or both sides of the substrate, and a release film is adhered to the outer side of the pressure-sensitive adhesive layer.

[0011] More optimally, the acrylic pressure-sensitive adhesive layer comprises the following components by weight:

[0012] 100 parts of acrylic acid ester polymer;

[0013] 5-20 parts of tackifying resin;

[0014] Curing agent 0.1-5 parts;

[0015] 160-300 parts of solvent.

[0016] More optimally, the glass transition temperature of the acrylic pressure-sensitive adhesive layer is between -40 and -10°C; the weight average molecular weight M of the acrylic pressure-sensitive adhesive layer is W The molecular weight of the acrylic pressure-sensitive adhesive is 300,000 to 500,000, and the molecular weight distribution is 4.5 to 7.5; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 100 to 160 KPa, and the loss factor tanδ is 0.45 to 0.60; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 42 to 60 KPa, and the loss factor tanδ is 0.3 to 0.40; the creep recovery rate of the acrylic pressure-sensitive adhesive is greater than 65% after the temperature drops from 65°C to 25°C under a high creep state of 400%.

[0017] More preferably, the acrylic ester polymer comprises the following components by weight:

[0018] 65-100 parts of high creep recovery optical acrylate monomer;

[0019] 5-35 parts of acrylate hard segment monomer;

[0020] 0.5-10 parts of functional monomer;

[0021] Initiator 0.1-0.5 parts;

[0022] 80 to 150 parts of solvent.

[0023] More optimally, the high creep recovery optical acrylate monomer is at least one of dicyclopentenyl ethoxylated acrylate, ethoxyethoxy acrylate, stearic acid methacrylate, 2-[[butylamino)carbonyl]oxy]ethyl acrylate, eicosyl acrylate, and docosyl acrylate.

[0024] More optimally, the acrylate hard segment monomer is at least one of isobutyl acrylate, tetrahydrofurfuryl methacrylate, tert-butyl acrylate, isobornyl acrylate, propoxylated nonylphenol acrylate, tetrahydrofurfuryl acrylate, and cyclohexyl methacrylate.

[0025] More preferably, the functional monomer is ethoxylated tetrahydrofuran acrylate, glycidyl methacrylate, 2-hydroxypropyl methacrylate, acrylic acid, 2-hydroxyethyl methacrylate, acetoacetoxyethyl methacrylate. 、 At least one of acrylamide; the initiator is at least one of azobisisobutyronitrile, dodecyl peroxide, tert-butyl perbenzoate, azobisisoheptylnitrile, benzoyl peroxide, and lauroyl peroxide.

[0026] More optimally, the tackifying resin is any one or more of rosin resin, modified rosin resin, terpene resin, modified terpene resin, petroleum resin, hydrogenated petroleum resin and styrene resin; the curing agent is at least one of polyisocyanate, epoxy curing agent and metal salt curing agent.

[0027] More optimally, the optical grade polyester film PET substrate has a transmittance of >90%, a haze of <2%, a color difference △E≤1, a surface gloss of >180%, and a low heat shrinkage of ≤0.3% under the condition of 150°C / 30min.

[0028] The present invention also provides a method for preparing an optical tape resistant to light radiation and having high creep recovery, which is used for any of the above optical tapes resistant to light radiation and having high creep recovery, and comprises the following steps:

[0029] Step 1: Take high creep recovery optical acrylate monomer, acrylate hard segment monomer, initiator, and solvent, mix them evenly, and react at 65-95° C. for 6-12 hours to obtain an acrylate polymer with light radiation resistance and high creep recovery;

[0030] Step 2: Take an acrylate polymer having high creep recovery and light radiation resistance, a curing agent, and a solvent, mix them evenly, and mechanically stir them to obtain a pressure-sensitive adhesive;

[0031] Step three: coating a pressure-sensitive adhesive on the release surface of the release film, drying, and obtaining a pressure-sensitive adhesive layer; laminating the pressure-sensitive adhesive layer on an optical-grade polyester film PET substrate to obtain an optical tape that is resistant to light radiation and has high creep recovery.

[0032] Preferably, the coating method is any one of slit extrusion coating and comma blade coating.

[0033] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0034] (1) In the present invention, a light radiation resistant and high creep recovery acrylate polymer is prepared by free radical polymerization of a high creep recovery optical acrylate monomer and an acrylate hard monomer in a specific weight ratio, and the acrylate polymer and a tackifying resin are reasonably combined to prepare an acrylate pressure-sensitive adhesive layer that is light radiation resistant and has high creep recovery. The optical tape is prepared by combining it with an optical grade polyester film substrate, and can be continuously irradiated for 1000 hours under three harsh conditions: an irradiance of 2.4 W / m2 / nm (at a wavelength of 420 nm), a high temperature of 60°C, and a high humidity of 90% RH, while still maintaining good optical properties such as yellowness, transmittance, and haze.

[0035] (2) In the present invention, the prepared light radiation resistant and high creep recovery acrylic pressure-sensitive adhesive layer has high flexibility and high creep recovery, low adhesive overflow, high adhesion performance, and excellent impact resistance under high temperature, high humidity, and high radiation conditions.

[0036] (3) The optical adhesive tape provided in the present invention can be widely used in the field of LCD display screens because of its wide range of applications, resistance to light radiation, resistance to yellowing, high creep recovery, high bonding performance, and low glue overflow. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0038] The present invention verifies the effects of the present invention through several embodiments and comparative examples and experiments. The purchase channels of the chemical reagents used in the present invention are shown in Table 1.

[0039] Table 1 Purchase channels of chemical reagents used in the examples and comparative examples

[0040] Reagent name Purity Grade Manufacturer Dicyclopentenyl ethoxylated acrylate Industrial Grade Changxing Chemical Eicosyl acrylate Industrial Grade Changxing Chemical Isobutyl acrylate Analytical grade Changxing Chemical Ethoxylated tetrahydrofuran acrylate Chemically pure Aladdin Chemistry Ethoxyethoxy acrylate Analytical grade Aladdin Chemistry Tert-Butyl Acrylate Analytical grade Aladdin Chemistry Isobornyl acrylate Chemically pure Changxing Chemical Glycidyl Methacrylate Analytical grade Aladdin Chemistry Stearic acid methacrylate Analytical grade Aladdin Chemistry Tetrahydrofurfuryl methacrylate Analytical grade Aladdin Chemistry 2-Hydroxypropyl Methacrylate Analytical grade Aladdin Chemistry acrylic acid Analytical grade Aladdin Chemistry Lauroyl Peroxide Analytical grade Aladdin Chemistry Benzoyl peroxide Analytical grade Aladdin Chemistry Azobisisobutyronitrile Analytical grade Aladdin Chemistry Butyl acetate Industrial Grade Suzhou Chengxiang Chemical Ethyl acetate Industrial Grade Suzhou Chengxiang Chemical Polyisocyanate Analytical grade Anzo Chemical Y-105 Epoxy Curing Agent Analytical grade Anzuo Chemical Y-202

[0041] Example 1

[0042] S1. Preparation of acrylic polymers with high creep recovery and resistance to light radiation;

[0043] (1) 30 g of dicyclopentenyl ethoxylated acrylate, 10 g of eicosyl acrylate, 15 g of isobutyl acrylate, 4 g of ethoxylated tetrahydrofuran acrylate, 0.1 g of azobisisobutyronitrile and 60 g of ethyl acetate were uniformly mixed to obtain a mixed solution. The mixed solution was added to a reactor and placed in a constant temperature oil bath at 85°C. After free radical polymerization for 2 hours, a reaction solution A1 was obtained. (2) The reaction conditions were maintained, 30 g of dicyclopentenyl ethoxylated acrylate, 5 g of eicosyl acrylate, 15 g of isobutyl acrylate, 4 g of ethoxylated tetrahydrofuran acrylate, 0.1 g of benzoyl peroxide and 20 g of ethyl acetate were uniformly mixed and added dropwise to the above reaction solution for 2 to 3 hours. After the addition was completed, the reaction was continued for 1.5 hours to obtain a reactant A2. (3) The reaction conditions were maintained, 0.2 g of azobisisobutyronitrile and 40 g of ethyl acetate were added to the reactant A2, the reaction was continued for 3 hours, the mixture was uniformly stirred, and the mixture was cooled to room temperature to obtain an acrylate polymer A that was resistant to light radiation and had high creep recovery properties.

[0044] S2. Preparation of an optical tape with high creep recovery and light radiation resistance

[0045] a. Mix 100 parts of a light radiation resistant, high creep recovery acrylate polymer A, 8 parts of a tackifying resin, 0.5 parts of a curing agent, and 200 parts of a solvent, and perform ultrasonic dispersion to obtain an acrylate pressure-sensitive solution;

[0046] The tackifying resin is a petroleum resin with a softening point of 95°C, specifically FTR-6100 from Mitsui Chemicals; the curing agent is an epoxy curing agent, specifically Y-202 from Anzu Chemicals; and the solvent is butyl acetate;

[0047] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -15°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M W The molecular weight distribution is 5.4; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 130KPa, and the loss factor tanδ is 0.52; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 58KPa, and the loss factor tanδ is 0.36; the creep recovery rate of the acrylic pressure-sensitive adhesive is 68.1% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0048] b. Coating a 49 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer A; laminating the pressure-sensitive adhesive layer A on a PET substrate to obtain a semi-finished optical tape having light radiation resistance and high creep recovery;

[0049] c. Coating a 49 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer A; laminating the pressure-sensitive adhesive layer A on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0050] The PET substrate (SKC, Korea) is a polyester film with a thickness of 12 μm. The PET substrate has a transmittance of 91%, a haze of 1.5%, a color difference △E of 0.5, a surface gloss of 185%, and a heat shrinkage of 0.25% under the condition of 150°C / 30min.

[0051] Example 2

[0052] S1. Preparation of acrylic polymers with high creep recovery and resistance to light radiation;

[0053] (1) 35 g of ethoxyethoxy acrylate, 10 g of tert-butyl acrylate, 5 g of isobornyl acrylate, 3 g of glycidyl methacrylate, 0.15 g of lauroyl peroxide and 50 g of ethyl acetate were uniformly mixed to obtain a mixed solution. The mixed solution was added into a reactor and placed in a constant temperature oil bath at 85°C. After free radical polymerization for 2.5 hours, a reaction solution B1 was obtained. (2) The reaction conditions were maintained, 35 g of ethoxyethoxy acrylate, 10 g of tert-butyl acrylate, 5 g of isobornyl acrylate, 3 g of glycidyl methacrylate, 0.05 g of lauroyl peroxide and 25 g of ethyl acetate were uniformly mixed, and the mixture was dropwise added into the above reaction solution. The dropwise addition time was 2 to 3 hours. After the dropwise addition was completed, the reaction was continued for 2 hours to obtain a reactant B2. (3) The reaction conditions were maintained, 0.1 g of lauroyl peroxide and 25 g of ethyl acetate were added into the reactant A2. The mixture was reacted for 2 hours. After stirring, the mixture was cooled to room temperature to obtain an acrylate polymer B having high creep recovery and light radiation resistance.

[0054] S2. Preparation of an optical tape with high creep recovery and light radiation resistance

[0055] a. Mix 100 parts of light radiation resistant, high creep recovery acrylate polymer B, 6 parts of tackifying resin, 0.8 parts of curing agent, and 220 parts of solvent by weight, stir, and ultrasonically disperse to obtain an acrylate pressure-sensitive solution;

[0056] The tackifying resin is a petroleum resin with a softening point of 100°C, specifically FTR-8100 from Mitsui Chemicals; the curing agent is an epoxy curing agent, specifically Y-202 from Anzu Chemicals; and the solvent is butyl acetate;

[0057] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -12°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M WThe molecular weight distribution is 450000 and 4.8; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 138KPa, and the loss factor tanδ is 0.55; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 55KPa, and the loss factor tanδ is 0.34; the creep recovery rate of the acrylic pressure-sensitive adhesive is 67.6% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0058] b. Coating a 56.5 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer B; laminating the pressure-sensitive adhesive layer B on a PET substrate to obtain a semi-finished optical tape having light radiation resistance and high creep recovery;

[0059] c. Coating a 56.5 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer B; laminating the pressure-sensitive adhesive layer B on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0060] The PET substrate (SKC, South Korea) is a polyester film with a thickness of 12 μm. The transmittance of the PET substrate is 91%, the haze is 1.5%, the color difference △E is 0.5, the surface gloss is 185%, and the heat shrinkage is 0.25% under the condition of 150℃ / 30min;

[0061] Example 3

[0062] S1. Preparation of acrylic polymers with high creep recovery and resistance to light radiation;

[0063] (1) 40 g of stearic acid methacrylate, 15 g of tetrahydrofurfuryl methacrylate, 3 g of 2-hydroxypropyl methacrylate, 1 g of acrylic acid, 0.1 g of azobisisoheptanenitrile and 60 g of butyl acetate were uniformly mixed to obtain a mixed solution. The mixed solution was added to a reactor and placed in a constant temperature oil bath at 80°C. After free radical polymerization for 1.5 hours, a reaction solution C1 was obtained. (2) The reaction conditions were maintained, 40 g of stearic acid methyl acrylate, 10 g of tetrahydrofurfuryl methacrylate, 3 g of 2-hydroxypropyl methacrylate, 1 g of acrylic acid, 0.1 g of azobisisoheptanenitrile and 40 g of butyl acetate were uniformly mixed and added dropwise to the above reaction solution. The addition time was 2.5 to 3.5 hours. After the addition was completed, the reaction was continued for 2 hours to obtain a reactant C2. (3) The reaction conditions were maintained, 0.1 g of azobisisoheptanenitrile and 30 g of butyl acetate were added to the reactant C2. The reaction was continued for 3.5 hours. After stirring, the mixture was cooled to room temperature to obtain an acrylic polymer C that was resistant to light radiation and had high creep recovery properties.

[0064] S2. Preparation of an optical tape with high creep recovery and light radiation resistance

[0065] a. Mix 100 parts of light radiation resistant, high creep recovery acrylate polymer C, 10 parts of tackifying resin, 1 part of curing agent, and 200 parts of solvent by weight, and disperse them by ultrasonic to obtain an acrylate pressure-sensitive solution;

[0066] The tackifying resin is a petroleum resin with a softening point of 95°C, specifically FTR-6100 from Mitsui Chemicals; the curing agent is a polyisocyanate and a metal salt curing agent, with a mass ratio of 6:4, specifically Anzo Chemical Y-105 and Y-202 respectively; the solvent is ethyl acetate;

[0067] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -12°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M W The molecular weight distribution is 460000 and 4.8; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 150KPa, and the loss factor tanδ is 0.49; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 55KPa, and the loss factor tanδ is 0.35; the creep recovery rate of the acrylic pressure-sensitive adhesive is 69.2% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0068] b. Coating a 34 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer C; laminating the pressure-sensitive adhesive layer C on a PET substrate to obtain a semi-finished optical tape having light radiation resistance and high creep recovery;

[0069] c. Coating a 34 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer C; laminating the pressure-sensitive adhesive layer C on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0070] The PET substrate (SKC, South Korea) is a polyester film with a thickness of 12 μm. The transmittance of the PET substrate is 91%, the haze is 1.5%, the color difference △E is 0.5, the surface gloss is 185%, and the heat shrinkage is 0.25% under the condition of 150℃ / 30min;

[0071] Comparative Example 1

[0072] Example 1 is used as a control group, but an acrylate polymer having light radiation resistance and high creep recovery, specifically Y-1421 of Anzu Chemical, is recorded as acrylate polymer D;

[0073] a. Mix 100 parts of acrylate polymer D, 8 parts of tackifying resin, 0.5 parts of curing agent and 200 parts of solvent by weight, stir and disperse by ultrasonic to obtain an acrylate pressure-sensitive solution;

[0074] The tackifying resin is a petroleum resin with a softening point of 95°C, specifically FTR-6100 from Mitsui Chemicals; the curing agent is an epoxy curing agent, specifically Y-202 from Anzu Chemicals; and the solvent is butyl acetate;

[0075] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -4°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M W The molecular weight distribution is 3.8; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 220KPa, and the loss factor tanδ is 0.62; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 72KPa, and the loss factor tanδ is 0.42; the creep recovery rate of the acrylic pressure-sensitive adhesive is 25.3% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0076] b. Coating a 49 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer D; and laminating the pressure-sensitive adhesive layer D on a PET substrate to obtain a semi-finished optical tape having light radiation resistance and high creep recovery;

[0077] c. Coating a 49 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer D; laminating the pressure-sensitive adhesive layer D on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0078] The PET substrate (SKC, South Korea) is a polyester film with a thickness of 12 μm. The transmittance of the PET substrate is 91%, the haze is 1.5%, the color difference △E is 0.5, the surface gloss is 185%, and the heat shrinkage is 0.25% under the condition of 150℃ / 30min;

[0079] Comparative Example 2

[0080] Using Example 2 as a control group, the ratio of the optical acrylate monomer with high creep recovery and the acrylate hard segment monomer was changed during the preparation of the acrylate polymer with high creep recovery and light radiation resistance;

[0081] S1. Preparation of acrylic polymers with high creep recovery and resistance to light radiation;

[0082] (1) 25 g of ethoxyethoxy acrylate, 15 g of tert-butyl acrylate, 10 g of isobornyl acrylate, 3 g of glycidyl methacrylate, 0.15 g of lauroyl peroxide, and 50 g of ethyl acetate were uniformly mixed to obtain a mixed solution. The mixed solution was added into a reactor and placed in a constant temperature oil bath at 85°C. After free radical polymerization for 2.5 hours, a reaction solution E1 was obtained. (2) The reaction conditions were maintained, 25 g of ethoxyethoxy acrylate, 15 g of tert-butyl acrylate, 5 g of isobornyl acrylate, 3 g of glycidyl methacrylate, 0.05 g of lauroyl peroxide and 25 g of ethyl acetate were uniformly mixed, and the mixture was dropwise added into the above reaction solution. The dropwise addition time was 2 to 3 hours. After the dropwise addition was completed, the reaction was continued for 2 hours to obtain a reactant E2. (3) The reaction conditions were maintained, 0.1 g of lauroyl peroxide and 25 g of ethyl acetate were added into the reactant A2. The mixture was reacted for 2 hours. After stirring, the mixture was cooled to room temperature to obtain an acrylate polymer E which was resistant to light radiation and had high creep recovery properties.

[0083] S2. Preparation of an optical tape with high creep recovery and light radiation resistance

[0084] a. Mix 100 parts of light radiation resistant, high creep recovery acrylate polymer E, 6 parts of tackifying resin, 0.8 parts of curing agent, and 220 parts of solvent by weight, and perform ultrasonic dispersion to obtain an acrylate pressure-sensitive solution;

[0085] The tackifying resin is a petroleum resin with a softening point of 100°C, specifically FTR-8100 from Mitsui Chemicals; the curing agent is an epoxy curing agent, specifically Y-202 from Anzu Chemicals; and the solvent is butyl acetate;

[0086] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -6°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M W The molecular weight distribution is 4.2; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 175KPa, and the loss factor tanδ is 0.62; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 62KPa, and the loss factor tanδ is 0.42; the creep recovery rate of the acrylic pressure-sensitive adhesive is 45.3% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0087] b. Coating a 56.5 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer E; and laminating the pressure-sensitive adhesive layer E on a PET substrate to obtain a semi-finished optical adhesive tape having light radiation resistance and high creep recovery;

[0088] c. Coating a 56.5 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer E; laminating the pressure-sensitive adhesive layer E on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0089] The PET substrate (SKC, South Korea) is a polyester film with a thickness of 12 μm. The transmittance of the PET substrate is 91%, the haze is 1.5%, the color difference △E is 0.5, the surface gloss is 185%, and the heat shrinkage is 0.25% under the condition of 150℃ / 30min;

[0090] Comparative Example 3

[0091] Using Example 3 as a control group, the ratio of the light radiation resistant, high creep recovery acrylate polymer and the tackifying resin in the acrylate pressure-sensitive adhesive layer was changed.

[0092] S1. Preparation of acrylic polymers with high creep recovery and resistance to light radiation;

[0093] (1) 40 g of stearic acid methacrylate, 15 g of tetrahydrofurfuryl methacrylate, 3 g of 2-hydroxypropyl methacrylate, 1 g of acrylic acid, 0.1 g of azobisisoheptanenitrile and 60 g of butyl acetate were uniformly mixed to obtain a mixed solution. The mixed solution was added to a reactor and placed in a constant temperature oil bath at 80°C. After free radical polymerization for 1.5 hours, a reaction solution C1 was obtained. (2) The reaction conditions were maintained, 40 g of stearic acid methyl acrylate, 10 g of tetrahydrofurfuryl methacrylate, 3 g of 2-hydroxypropyl methacrylate, 1 g of acrylic acid, 0.1 g of azobisisoheptanenitrile and 40 g of butyl acetate were uniformly mixed and added dropwise to the above reaction solution. The addition time was 2.5 to 3.5 hours. After the addition was completed, the reaction was continued for 2 hours to obtain a reactant C2. (3) The reaction conditions were maintained, 0.1 g of azobisisoheptanenitrile and 30 g of butyl acetate were added to the reactant C2. The reaction was continued for 3.5 hours. After stirring, the mixture was cooled to room temperature to obtain an acrylic polymer C that was resistant to light radiation and had high creep recovery properties.

[0094] S2. Preparation of an optical tape with high creep recovery and light radiation resistance

[0095] a. Mix 100 parts of acrylate polymer C with high creep recovery and light radiation resistance, 30 parts of tackifying resin, 1 part of curing agent and 200 parts of solvent by weight, and disperse them by ultrasonic to obtain an acrylate pressure-sensitive solution;

[0096] The tackifying resin is a petroleum resin with a softening point of 95°C, specifically FTR-6100 from Mitsui Chemicals; the curing agent is a polyisocyanate and a metal salt curing agent, with a mass ratio of 6:4, specifically Anzo Chemical Y-105 and Y-202 respectively; the solvent is ethyl acetate;

[0097] The glass transition temperature of the acrylic pressure-sensitive adhesive layer is -5°C; the weight average molecular weight of the acrylic pressure-sensitive adhesive layer is M W The molecular weight distribution is 460000 and 4.8; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 155KPa, and the loss factor tanδ is 0.44; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 40KPa, and the loss factor tanδ is 0.42; the creep recovery rate of the acrylic pressure-sensitive adhesive is 32.2% after the temperature drops from 65°C to 25°C under a high creep state of 400%;

[0098] b. Coating a 34 μm thick pressure-sensitive adhesive on the release surface of a 70 μm thick release film having an aged release force of 15 gf / in and a residual rate of 87%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer C; laminating the pressure-sensitive adhesive layer C on a PET substrate to obtain a semi-finished optical tape having light radiation resistance and high creep recovery;

[0099] c. Coating a 34 μm thick pressure-sensitive adhesive on the release surface of a 45 μm thick release film with an aged release force of 6 gf / in and a residual rate of 88%, and drying at 110° C. for 3 min to obtain a pressure-sensitive adhesive layer C; laminating the pressure-sensitive adhesive layer C on the PET substrate surface of a semi-finished adhesive tape to obtain an optical adhesive tape with light radiation resistance and high creep recovery;

[0100] The PET substrate (SKC, Korea) is a polyester film with a thickness of 12 μm. The PET substrate has a transmittance of 91%, a haze of 1.5%, a color difference △E of 0.5, a surface gloss of 185%, and a heat shrinkage of 0.25% under the condition of 150°C / 30min.

[0101] After the examples and comparative examples were prepared, their peel strength and optical properties were tested experimentally.

[0102] experiment

[0103] The adhesive tapes prepared in Examples 1-3 and Comparative Examples 1-3 were tested for peel strength, optical properties (transmittance, haze, yellowness), creep recovery and adhesive overflow performance at room temperature and after Q-SUN aging. The test results are shown in the following table;

[0104] Q-SUN aging conditions: irradiance 2.4W / m2 / nm (at 420nm wavelength), blackboard temperature 60℃, chamber humidity 90%RH, continuous irradiation 1000h;

[0105] The peel strength of the prepared tape was measured with reference to the method of GB / T2792-2014: the adhered object was a steel plate SUS with a bright surface and a roughness of 50nm (GB / T2523-2008). The tape was cut into a size of 25mm×300mm, and pressed back and forth 3 times with a 2kg roller, and left for 20min. The test environment was at room temperature 23℃ / 50%RH, and a 180° peeling test was performed at a speed of 300mm / min;

[0106] Optical properties: 1. Transmittance, using UV spectrophotometer, wavelength range 380nm ~ 700nm; 2. Haze, haze meter, wavelength range 380nm ~ 700nm; 3. Yellowness, colorimeter, 360nm ~ 740nm

[0107] Creep recovery: TADHR-10 rheometer, temperature 65°C, constant time 10s, strain 400%, duration 60min, then natural cooling, constant time 0s, stress 0 Pa, creep time 0s, duration 60min

[0108] Glue overflow characteristics: Use a Keyence microscope to observe whether the distance between the tape and the reflective film in the backlight module changes

[0109] Impact resistance: Drop hammer impact tester, height 51mm, weight 7kg

[0110] The performance comparison of the adhesive tapes prepared in Examples 1-3 and Comparative Examples 1-3 is shown in Table 2:

[0111] Table 2 Performance of the adhesive tapes obtained in the embodiments and comparative examples

[0112]

[0113] Conclusion: By comparing the embodiments with the comparative examples, it can be seen that the optical tape prepared by the method provided by the present invention is continuously irradiated for 1000 hours under three harsh conditions of irradiance of 2.4W / m2 / nm (at 420nm wavelength), high radiation of 60°C, and high humidity of 90% RH, and still maintains good optical properties such as yellowness, transmittance and haze, and has high bonding performance, and no overflow of glue occurs; when the strain is 400% at 65°C for 60 minutes and the stress is removed and naturally cooled to room temperature 25°C, the creep recovery rate can reach more than 65%, thereby ensuring that the material has good impact resistance.

[0114] 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.

[0115] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical tape with light radiation resistance and high creep recovery, characterized in that: The invention comprises a substrate, wherein the substrate is an optical-grade polyester film PET substrate with a thickness of 6 to 20 μm, an acrylic pressure-sensitive adhesive layer with a thickness of 14 to 60 μm is pasted on one side or both sides of the substrate, and a release film is pasted on the outer side of the pressure-sensitive adhesive layer.

2. The optical tape with high creep recovery and light radiation resistance according to claim 1, characterized in that: The acrylic pressure-sensitive adhesive layer comprises the following components by weight: 100 parts of acrylic acid ester polymer; 5-20 parts of tackifying resin; Curing agent 0.1-5 parts; 160-300 parts of solvent.

3. The optical tape with high creep recovery and light radiation resistance according to claim 2, characterized in that: The glass transition temperature of the acrylic pressure-sensitive adhesive layer is between -40 and -10°C; Weight average molecular weight of acrylic pressure-sensitive adhesive layer M W The molecular weight of the acrylic pressure-sensitive adhesive is 300,000 to 500,000, and the molecular weight distribution is 4.5 to 7.5; the storage modulus G' of the acrylic pressure-sensitive adhesive at 23°C is 100 to 160 KPa, and the loss factor tanδ is 0.45 to 0.60; the storage modulus G' of the acrylic pressure-sensitive adhesive at 65°C is 42 to 60 KPa, and the loss factor tanδ is 0.3 to 0.40; the creep recovery rate of the acrylic pressure-sensitive adhesive is greater than 65% after the temperature drops from 65°C to 25°C under a high creep state of 400%.

4. The optical tape with high creep recovery and light radiation resistance according to claim 2, characterized in that: The acrylic acid ester polymer comprises the following components by weight: 65-100 parts of high creep recovery optical acrylate monomer; 5 to 35 parts of acrylate hard segment monomer; 0.5-10 parts of functional monomer; Initiator 0.1-0.5 parts; 80 to 150 parts of solvent.

5. The optical tape with high creep recovery and light radiation resistance according to claim 4, characterized in that: The high creep recovery optical acrylate monomer is at least one of dicyclopentenyl ethoxylated acrylate, ethoxyethoxy acrylate, stearic acid methacrylate, 2-[[butylamino)carbonyl]oxy]ethyl acrylate, eicosyl acrylate, and docosyl acrylate.

6. The optical tape with high creep recovery and light radiation resistance according to claim 4, characterized in that: The acrylic acid ester hard segment monomer is at least one of isobutyl acrylate, tetrahydrofurfuryl methacrylate, tert-butyl acrylate, isobornyl acrylate, propoxylated nonylphenol acrylate, tetrahydrofurfuryl acrylate, and cyclohexyl methacrylate.

7. The optical tape with high creep recovery and light radiation resistance according to claim 4, characterized in that: The functional monomers are ethoxylated tetrahydrofuran acrylate, glycidyl methacrylate, 2-hydroxypropyl methacrylate, acrylic acid, 2-hydroxyethyl methacrylate, acetoacetoxyethyl methacrylate, 、 At least one of acrylamide; the initiator is at least one of azobisisobutyronitrile, dodecyl peroxide, tert-butyl perbenzoate, azobisisoheptylnitrile, benzoyl peroxide, and lauroyl peroxide.

8. The optical tape with high creep recovery and light radiation resistance according to claim 2, characterized in that: The tackifying resin is any one or more of rosin resin, modified rosin resin, terpene resin, modified terpene resin, petroleum resin, hydrogenated petroleum resin and styrene resin; the curing agent is at least one of polyisocyanate, epoxy curing agent and metal salt curing agent.

9. The optical tape with high creep recovery and light radiation resistance according to claim 1, characterized in that: The optical grade polyester film PET substrate has a transmittance greater than 90%, a haze less than 2%, a color difference ΔE≤1, a surface gloss greater than 180%, and a low heat shrinkage of ≤0.3% under the condition of 150°C / 30min.

10. A method for preparing an optical tape resistant to light radiation and having high creep recovery, for preparing any one of the optical tapes resistant to light radiation and having high creep recovery as claimed in claims 1 to 9, characterized in that: The following steps are involved: Step 1: Take high creep recovery optical acrylate monomer, acrylate hard segment monomer, initiator, and solvent, mix them evenly, and react at 65-95° C. for 6-12 hours to obtain an acrylate polymer with light radiation resistance and high creep recovery; Step 2: Take an acrylate polymer having high creep recovery and light radiation resistance, a curing agent, and a solvent, mix them evenly, and stir them mechanically to obtain a pressure-sensitive adhesive; Step three: coating a pressure-sensitive adhesive on the release surface of the release film, drying, and obtaining a pressure-sensitive adhesive layer; laminating the pressure-sensitive adhesive layer on an optical-grade polyester film PET substrate to obtain an optical tape that is resistant to light radiation and has high creep recovery.

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