Optical adhesive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of optical cement, in particular to optical cement as well as a preparation method and application thereof. The optical cement comprises acrylic resin and a cross-linking agent, the use amount of the cross-linking agent is 0.1 wt%-0.5 wt% of the acrylic resin; the acrylic resin is mainly prepared by copolymerizing acrylate monomers; the acrylate monomer comprises 5 wt%-10 wt% of an acrylate compound as shown in a formula I which is described in the specification; in the formula, R1 is selected from alkylene groups with the carbon number being 1-3, and R2 is selected from alkyl groups with the carbon number being 1-3. According to the optical adhesive disclosed by the invention, a certain amount of monomers simultaneously containing F atoms and boric acid groups are introduced into the acrylic resin, so that the high temperature resistance and weather resistance of the optical adhesive are improved, and the stripping force, initial adhesion and cohesion of the optical adhesive are balanced, so that the requirements of the optical adhesive for vehicle-mounted display are met.

Description

Technical Field

[0001] The present invention relates to the technical field of optical adhesives, and in particular to an optical adhesive and a preparation method and application thereof. Background Art

[0002] Optical Clear Adhesive (OCA) for automotive displays is a key material for automotive displays (such as central control screens, instrument panels, HUDs, etc.), which directly affects display effects, touch sensitivity, durability and safety. After the temperature resistance (95℃×1000h) and weather resistance (85℃ / 85%×1000h) tests, the optical adhesive for automotive displays is required to be free of defects such as yellowing, bubbling, and warping.

[0003] At present, solvent-based acrylic resin and UV-curable acrylic resin are mostly used to prepare optical adhesives for vehicle displays. However, optical adhesives made from acrylic resins have poor weather resistance and temperature resistance, and are prone to yellowing, bubbling and other defects.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide an optical adhesive and a preparation method and application thereof. The optical adhesive of the present invention not only has good temperature resistance and weather resistance, but also has balanced three forces (peeling force, initial adhesion and cohesive force).

[0006] In order to achieve the above-mentioned object of the present invention, the first aspect of the present invention provides an optical adhesive, comprising an acrylic resin and a cross-linking agent; the amount of the cross-linking agent is 0.1wt% to 0.5wt% of the acrylic resin;

[0007] The acrylic resin is mainly prepared by copolymerization of acrylic ester monomers; the acrylic ester monomers include 5wt% to 10wt% of an acrylic ester compound as shown in Formula I;

[0008]

[0009] Among them, R 1 It is selected from an alkylene group having 1 to 3 carbon atoms.

[0010] In a specific embodiment of the present invention, the acrylic acid ester monomer includes the following components by mass percentage: 10% to 20% of hard monomer, 70% to 80% of soft monomer, 3% to 5% of functional monomer, 1% to 2% of polar monomer and 5% to 10% of acrylic acid ester compound as shown in formula I.

[0011] In a specific embodiment of the present invention, the hard monomer includes methyl acrylate and / or methyl methacrylate.

[0012] In a specific embodiment of the present invention, the soft monomer includes butyl acrylate and / or isooctyl acrylate.

[0013] In a specific embodiment of the present invention, the functional monomer is a hydroxyl-containing acrylic ester monomer. Further, the functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

[0014] In a specific embodiment of the present invention, the polar monomer includes acrylamide.

[0015] In a specific embodiment of the present invention, the acrylic resin further comprises an initiator and an organic solvent. Further, the amount of the initiator is 0.1wt% to 0.3wt% of the total amount of the acrylic ester monomers; the amount of the organic solvent is 80wt% to 120wt% of the total amount of the acrylic ester monomers.

[0016] In a specific embodiment of the present invention, the cross-linking agent is an isocyanate cross-linking agent.

[0017] The second aspect of the present invention provides a method for preparing the optical adhesive described in the first aspect of the present invention, comprising the following steps: (a) mixing the components in proportion to obtain a mixture; (b) applying the mixture on the surface of a release film, drying it, and then covering it with a release film to obtain the optical adhesive.

[0018] The third aspect of the present invention provides application of the optical adhesive described in the first aspect of the present invention in a vehicle-mounted display device.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) In the optical adhesive of the present invention, a certain amount of monomers having both F atoms and boronic acid groups are introduced into the acrylic resin. The boronic acid groups undergo self-dehydration condensation under high temperature conditions, which can not only form a cross-linking network but also generate new cross-linking points, thereby helping to improve the high temperature resistance of the optical adhesive. At the same time, the introduction of F atoms makes the acrylic resin have low surface energy, giving the acrylic resin excellent water resistance, and making the optical adhesive have excellent weather resistance.

[0021] (2) After the temperature resistance test of 95°C × 1000h and the weather resistance test of double 85°C × 1000h, the optical adhesive of the present invention has no defects such as yellowing, bubbling, and warping, and meets the use requirements of vehicle-mounted display equipment. DETAILED DESCRIPTION

[0022] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0023] Acrylic resin is one of the main resin matrices for preparing optical adhesives for vehicle-mounted displays. However, acrylic resin contains a large number of ester groups, carbonyl groups, hydroxyl groups and other groups, which are easy to form hydrogen bonds with water molecules; and ester groups are prone to hydrolysis in a hot and humid environment. The long-term exposure of the vehicle environment to high temperature and high humidity accelerates the penetration of water molecules, resulting in yellowing, bubbling, warping and other problems in the optical adhesive for vehicle-mounted displays. Based on this, the development of an optical adhesive with good weather resistance is of great significance to the development of vehicle-mounted displays.

[0024] The first aspect of the present invention provides an optical adhesive, comprising an acrylic resin and a crosslinking agent; the amount of the crosslinking agent is 0.1wt% to 0.5wt% of the acrylic resin; the acrylic resin is mainly prepared by copolymerization of acrylic ester monomers; the acrylic ester monomers include 5wt% to 10wt% of an acrylic ester compound as shown in Formula I;

[0025]

[0026] Among them, R 1 It is selected from an alkylene group having 1 to 3 carbon atoms.

[0027] In the optical adhesive of the present invention, a certain amount of monomers having both F atoms and boric acid groups are introduced into the acrylic resin. The boric acid groups undergo self-dehydration condensation under high temperature conditions, which can not only form a cross-linked network but also generate new cross-linking points, thereby helping to improve the high temperature resistance of the optical adhesive. At the same time, the introduction of F atoms enables the acrylic resin to have low surface energy, and imparts excellent water resistance to the acrylic resin. After the cross-linking reaction with the cross-linking agent, the optical adhesive has excellent high temperature resistance and weather resistance, and can ensure the balance of peeling force, initial adhesion and cohesion.

[0028] In the acrylate compound shown in Formula I, R 1It can be at least one of methylene, ethylene or propylene. For example, in different embodiments, in the acrylate monomer, the acrylate compound as shown in Formula I can account for 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or a range consisting of any two of them, such as 6wt% to 8wt%, etc. Studies have found that when the proportion of the acrylate compound as shown in Formula I in the acrylate monomer is too low, the improvement of the weather resistance of the optical adhesive is not obvious; when the proportion of the acrylate compound as shown in Formula I in the acrylate monomer is too high, the three forces of the optical adhesive cannot be taken into account.

[0029] For example, in different embodiments, the amount of the cross-linking agent may be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% of the acrylic resin, or a range consisting of any two thereof.

[0030] In a specific embodiment of the present invention, the acrylate monomers include the following components by mass percentage: 10% to 20% of hard monomers, 70% to 80% of soft monomers, 3% to 5% of functional monomers, 1% to 2% of polar monomers, and 5% to 10% of acrylate compounds as shown in Formula I. A certain amount of acrylate compounds as shown in Formula I is introduced into the acrylic resin of the present invention to improve the high temperature resistance and weather resistance of the optical adhesive, and at the same time, the amounts of hard monomers, soft monomers, functional monomers and polar monomers are regulated to meet the above conditions to further balance the three forces of the optical adhesive.

[0031] For example, in different embodiments, in terms of mass percentage, the usage of each type of monomer in the acrylic ester monomer may be as follows:

[0032] The amount of the hard monomer can be 10%, 12%, 15%, 18%, 20% or a range consisting of any two thereof;

[0033] The amount of the soft monomer can be 70%, 72%, 75%, 78%, 80% or a range consisting of any two thereof;

[0034] The amount of the functional monomer can be 3%, 3.5%, 4%, 4.5%, 5% or a range consisting of any two thereof;

[0035] The amount of polar monomer can be 1%, 1.2%, 1.5%, 1.8%, 2% or a range consisting of any two thereof;

[0036] The usage of the acrylic acid ester compound as shown in Formula I can be 5%, 6%, 7%, 8%, 9%, 10% or the range of any two thereof.

[0037] The acrylic acid ester compound of the present invention as shown in Formula I can be prepared according to the following route:

[0038]

[0039] Specifically, compound A and compound B are subjected to an esterification reaction under the action of a condensing agent (such as DCC and DMAP) to obtain an acrylic acid ester compound as shown in Formula I. In the esterification reaction, boric acid has low reactivity and does not affect the esterification reaction process of forming the compound as shown in Formula I.

[0040] In actual operation, the esterification reaction includes: mixing compound A, compound B and DMAP, adding DCC, and then reacting at 10-30°C for 6-10 hours to obtain an acrylate compound as shown in Formula I. The molar ratio of compound A to compound B can be 1:1, the molar ratio of DMAP to compound A is 0.1:1, and the molar ratio of DCC to compound A is 1.1:1. The specific reaction temperature and reaction time can be conventionally adjusted according to the progress of the reaction.

[0041] In a specific embodiment of the present invention, the acrylate compound as shown in Formula I has the following structural formula:

[0042]

[0043] When the structure of the acrylic acid ester compound represented by formula I is as shown above, the corresponding structure of compound B is as follows:

[0044]

[0045] In a particular embodiment of the present invention, the hard monomer comprises methyl acrylate and / or methyl methacrylate.

[0046] In a specific embodiment of the present invention, the soft monomer includes butyl acrylate and / or isooctyl acrylate.

[0047] In a specific embodiment of the present invention, the functional monomer is a hydroxyl-containing acrylic ester monomer. Further, the functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

[0048] In a specific embodiment of the present invention, the polar monomer includes acrylamide. Introducing a proper amount of acrylamide into the acrylic resin of the present invention is more helpful to improve the initial adhesion of the optical adhesive.

[0049] In a specific embodiment of the present invention, the acrylic resin further comprises an initiator and an organic solvent. Further, the amount of the initiator is 0.1wt% to 0.3wt% of the total amount of the acrylic ester monomers, for example, it can be 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt% or a range consisting of any two thereof; the amount of the organic solvent can be 80wt% to 120wt% of the total amount of the acrylic ester monomers, for example, it can be 80wt%, 90wt%, 100wt%, 110wt%, 120wt% or a range consisting of any two thereof.

[0050] In a specific embodiment of the present invention, the initiator is at least one of a peroxide initiator and an azo initiator, and the specific type is not limited, as long as it can initiate the polymerization reaction of the acrylate monomer, for example, it can be dibenzoyl peroxide, azobisisobutyronitrile, etc.; the organic solvent includes but is not limited to at least one of ethyl acetate, toluene, xylene, and butyl acetate.

[0051] In a specific embodiment of the present invention, the preparation of acrylic resin includes: weighing raw materials (acrylate monomer, initiator and solvent) in proportion, reacting at 85-95°C for 6-12h under a protective atmosphere. In the preparation of acrylic resin, the protective atmosphere can be nitrogen, but is not limited thereto; the reaction temperature can be 85°C, 88°C, 90°C, 92°C, 95°C or any value between any two end values ​​thereof, and the reaction time can be 6h, 8h, 10h, 12h, etc.

[0052] In a specific embodiment of the present invention, the weight average molecular weight of the acrylic resin may be exemplified as 900,000 to 1.5 million, but is not limited thereto; the molecular weight distribution width of the acrylic resin may be exemplified as 3.5 to 4.5, but is not limited thereto.

[0053] In a specific embodiment of the present invention, the crosslinking agent is an isocyanate crosslinking agent. The isocyanate crosslinking agent can react with hydroxyl groups in the acrylic resin to achieve crosslinking. For example, in different embodiments, the isocyanate crosslinking agent is a multifunctional isocyanate crosslinking agent, including but not limited to any one or more of HDI trimer, TDI trimer, and IPDI trimer.

[0054] In a specific embodiment of the present invention, the optical adhesive further comprises a solvent. Further, the solvent comprises at least one of ethyl acetate, toluene, xylene and butyl acetate.

[0055] The amount of solvent in the optical adhesive can be adjusted according to actual needs to ensure the coating requirements of the optical adhesive and the drying time requirements after coating. For example, the amount of solvent can be 5wt% to 40wt% of the acrylic resin, such as 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, etc., but not limited thereto.

[0056] The second aspect of the present invention provides a method for preparing the optical adhesive of the first aspect of the present invention, comprising the following steps: (a) mixing the components in proportion to obtain a mixture; (b) applying the mixture to the surface of a release film, drying it, and then covering it with the release film to obtain the optical adhesive.

[0057] Among them, the coating thickness of the mixture can be adjusted according to the actual thickness requirement of the optical adhesive, such as the thickness of the optical adhesive layer formed after the mixture is coated and dried can be controlled to be 50 to 300 μm, but it is not limited to this. The release film may include materials such as polyethylene terephthalate (PET) film, polyimide (PI) film, polyethylene (PE) film, oriented stretch polypropylene (OPP) film, composite release film, etc. Since the release film will be peeled off during actual use, the thickness of the release film has little effect on the actual use of the product. The thickness of the release film can be freely selected according to actual needs without special limitation, for example, it can be 25 to 100 μm, specifically 25 μm, 40 μm, 60 μm, 80 μm, 100 μm or any value between any two end values.

[0058] In actual operation, during the drying process, the drying temperature may be 110 to 130° C., and the drying time may be 5 to 20 minutes.

[0059] The third aspect of the present invention provides application of the optical adhesive of the first aspect of the present invention in a vehicle-mounted display device.

[0060] Example 1

[0061] This embodiment provides a method for preparing an optical adhesive, comprising the following steps:

[0062] (1) Preparation of acrylic acid ester compounds as shown in formula I:

[0063] Into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser, and a dropping funnel, 1 mol of 2-hydroxyethyl acrylate, 1 mol of 3-fluoro-4-carboxyphenylboric acid, and 0.1 mol of DMAP were added, and after stirring evenly, 1.1 mol of DCC was added, and then reacted at 25°C for 8 hours to obtain an acrylic acid ester compound as shown in Formula I.

[0064]

[0065] (2) Preparation of acrylic resin:

[0066] In a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser, and a dropping funnel, 13 g of methyl acrylate, 74 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 2 g of acrylamide, 7 g of the compound shown in formula I, 0.2 g of dibenzoyl peroxide, and 100 g of toluene were added, and the mixture was reacted at 90°C for 8 h, and then the temperature was lowered to 40°C to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 115×10 4 , the Mw / Mn molecular weight distribution width is 4.

[0067] (3) Preparation of optical adhesive:

[0068] Weigh 100 g of the acrylic resin obtained in step (2), 0.3 g of an isocyanate crosslinking agent (Desmodur N3390), and 20 g of ethyl acetate in proportion, and mix them evenly to obtain a mixture; apply the mixture on the surface of a 75 μm thick release film substrate (such as PET), and dry it at 120° C. for 10 min to obtain a 250 μm thick adhesive layer; and cover the other side of the adhesive layer with a 50 μm thick PET release film to obtain an optical adhesive.

[0069] Example 2

[0070] This embodiment refers to the method for preparing the optical adhesive of Embodiment 1, with the only difference being that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0071] Step (2) of this embodiment includes: adding 13 g of methyl acrylate, 71 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 2 g of acrylamide, 10 g of the compound shown in formula I, 0.2 g of dibenzoyl peroxide and 100 g of toluene to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 105×10 4 , the Mw / Mn molecular weight distribution width is 3.6.

[0072] Example 3

[0073] This embodiment refers to the method for preparing the optical adhesive of Embodiment 1, with the only difference being that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0074] Step (2) of this embodiment includes: adding 13 g of methyl acrylate, 76 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 2 g of acrylamide, 5 g of the compound shown in formula I, 0.2 g of dibenzoyl peroxide and 100 g of toluene to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 99×10 4 , the Mw / Mn molecular weight distribution width is 3.7.

[0075] Example 4

[0076] This embodiment refers to the method for preparing the optical adhesive of Embodiment 1, with the only difference being that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0077] Step (2) of this embodiment includes: adding 15 g of methyl acrylate, 74 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 7 g of the compound shown in formula I, 0.2 g of dibenzoyl peroxide and 100 g of toluene to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 120×10 4 , the Mw / Mn molecular weight distribution width is 3.9.

[0078] Example 5

[0079] This embodiment refers to the method for preparing the optical adhesive of Embodiment 1, with the only difference being that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0080] Step (2) of this embodiment comprises: adding 11 g of methyl acrylate, 74 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 4 g of acrylamide, 7 g of the compound shown in formula I, 0.2 g of dibenzoyl peroxide and 100 g of toluene to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 125×10 4 , the Mw / Mn molecular weight distribution width is 3.6.

[0081] Comparative Example 1

[0082] Comparative Example 1 refers to the method for preparing the optical adhesive of Example 1, except that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0083] Step (2) of Comparative Example 1 comprises: adding 14 g of methyl acrylate, 80 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 2 g of acrylamide, 0.2 g of dibenzoyl peroxide and 100 g of toluene into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 120×10 4 , the Mw / Mn molecular weight distribution width is 3.5.

[0084] Comparative Example 2

[0085] Comparative Example 2 refers to the method for preparing the optical adhesive of Example 1, except that in step (2) of preparing the acrylic resin, the amounts of the monomers used are different.

[0086] Step (2) of Comparative Example 2 comprises: adding 13 g of methyl acrylate, 70 g of butyl acrylate, 4 g of 2-hydroxyethyl acrylate, 2 g of acrylamide, 11 g of the compound represented by Formula I, 0.2 g of dibenzoyl peroxide and 100 g of toluene to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser and a dropping funnel, reacting at 90° C. for 8 h, then cooling to 40° C. to obtain an acrylic resin. The weight average molecular weight Mw of the acrylic resin is 95×10 4 , the Mw / Mn molecular weight distribution width is 4.6.

[0087] Comparative Example 3

[0088] Comparative Example 3 refers to the method for preparing the optical adhesive of Example 1, except that in the step (2) of preparing the acrylic resin, an equal mass of the compound represented by Formula II is used to replace the compound represented by Formula I.

[0089] The preparation of the compound represented by formula II includes: adding 1 mol of 2-hydroxyethyl acrylate, 1 mol of 4-carboxyphenylboric acid, and 0.1 mol of DMAP to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a reflux condenser, and a dropping funnel, adding 1.1 mol of DCC after stirring evenly, and then reacting at 25° C. for 8 hours to obtain an acrylic ester compound represented by formula II.

[0090]

[0091] Experimental example

[0092] In order to compare and illustrate the performance of the optical adhesives prepared in different embodiments and comparative examples, the optical adhesives prepared in the embodiments and comparative examples were subjected to the following tests. The test results are shown in Table 1.

[0093] 25℃ peel strength: tested in accordance with GB / T 2792-2014; the test substrate is 304 mirror stainless steel plate;

[0094] Rolling ball initial adhesion: tested according to GB / T 4852-2002;

[0095] Adhesion retention at 80℃: tested in accordance with GB / T 4851-2014; the test substrate is 304 mirror stainless steel plate;

[0096] Temperature resistance test: peel off the release film on one side of the optical adhesive to be tested, use a pressure roller to stick the side of the optical adhesive to be tested with the release film peeled off to the surface of the polarizer, then peel off the release film on the other side, and use a pressure roller to stick the side of the optical adhesive to the glass cover; then place the component in a high-pressure degassing machine for 50 minutes, and then place it at 95℃ for 1000 hours, and visually inspect the appearance to see if there are any bubbling or warping defects. If not, it passes;

[0097] Weather resistance test: peel off the release film on one side of the optical adhesive to be tested, use a pressure roller to stick the side of the release film of the optical adhesive to be tested to the surface of the polarizer, then peel off the release film on the other side, and use a pressure roller to stick the side of the optical adhesive to the glass cover; then place the assembly in a high-pressure degassing machine for 50 minutes, and then place it under constant temperature and humidity conditions of 85°C and 85% relative humidity for 1000 hours, visually inspect the appearance to see if there are bubbling or warping defects, if not, it passes.

[0098] Table 1 Performance test results of different optical adhesives

[0099]

[0100] From the above test results, it can be seen that the optical adhesive of the present invention not only has good temperature resistance and weather resistance, but also has good peeling force, initial adhesion and cohesive force, and can meet the requirements of optical adhesive for vehicle-mounted display.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Optical adhesive, characterized in that: It comprises an acrylic resin and a cross-linking agent; the amount of the cross-linking agent is 0.1wt% to 0.5wt% of the acrylic resin; The acrylic resin is mainly prepared by copolymerization of acrylic ester monomers; the acrylic ester monomers include 5wt% to 10wt% of an acrylic ester compound as shown in Formula I; Here, R1 is selected from an alkylene group having 1 to 3 carbon atoms.

2. The optical adhesive according to claim 1, characterized in that: The acrylic ester monomers include the following components by mass percentage: 10% to 20% of hard monomers, 70% to 80% of soft monomers, 3% to 5% of functional monomers, 1% to 2% of polar monomers and 5% to 10% of acrylic ester compounds as shown in formula I.

3. The optical adhesive according to claim 2, characterized in that: The hard monomer includes methyl acrylate and / or methyl methacrylate.

4. The optical adhesive according to claim 2, characterized in that: The soft monomer includes butyl acrylate and / or isooctyl acrylate.

5. The optical adhesive according to claim 2, characterized in that: The functional monomer is a hydroxyl-containing acrylic ester monomer; Preferably, the functional monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

6. The optical adhesive according to claim 2, characterized in that: The polar monomer includes acrylamide.

7. The optical adhesive according to claim 1, characterized in that: The acrylic resin also includes an initiator and an organic solvent; Preferably, the amount of the initiator is 0.1 wt% to 0.3 wt% of the total amount of the acrylic ester monomer; Preferably, the amount of the organic solvent used is 80 wt % to 120 wt % of the total amount of the acrylic ester monomers.

8. The optical adhesive according to claim 1, characterized in that: The cross-linking agent is an isocyanate cross-linking agent.

9. The method for preparing the optical adhesive according to any one of claims 1 to 8, characterized in that: The steps include: (a) mixing the components in proportion to obtain a mixture; (b) coating the mixture on the surface of a release film, drying it, and then covering it with a release film to obtain the optical adhesive.

10. Use of the optical adhesive according to any one of claims 1 to 8 or the optical adhesive prepared by the preparation method according to claim 9 in vehicle-mounted display equipment.

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