A UV adhesive, a UV adhesive film and its preparation method

Abstract

This invention relates to the field of polymer optical adhesives, specifically disclosing a UV adhesive, a UV adhesive film, and a method for preparing the same. The UV adhesive provided by this invention comprises 43-47 parts isooctyl acrylate, 10-13 parts butyl acrylate, 2-3 parts hydroxyethyl acrylate, 4-5 parts methyl methacrylate, 1-2 parts acrylic acid, 2-4 parts benzophenone monomers, and 1-7 parts tris(trimethylsiloxy)silyl monomers. The UV adhesive provided by this invention has a simple composition; simply controlling the UV irradiation dose is sufficient to achieve both thickening and thinning of the adhesive. No additional thermosetting agents or photopolymerizing components are required, solving the problem of poor compatibility in existing UV adhesive systems. This not only facilitates uniform coating but also fundamentally solves the problem of adhesive residue.

Description

Technical Field

[0001] This invention relates to the field of polymer optical adhesive technology, and in particular to a UV adhesive, a UV adhesive film, and a method for preparing the same. Background Technology

[0002] With the rapid development and rise of the semiconductor industry, the demand for adhesives in the semiconductor wafer field has also grown rapidly. UV-resistant adhesive films are needed to fix and protect wafers during wafer dicing and grinding processes. The UV-resistant adhesive used for wafer dicing is an adhesive that provides high adhesion under normal conditions, but its adhesion decreases dramatically after UV irradiation. Before UV irradiation, the adhesive film fixes the wafer with high adhesion, preventing silicon wafer breakage during dicing. After dicing, the adhesive loses its tackiness after UV irradiation, making wafer pickup easier. In recent years, with the development of the electronics and information industry, semiconductor electronic devices have become increasingly thinner, making wafers more susceptible to damage during processing. Therefore, UV-resistant adhesives are required to maintain high adhesion under normal conditions while also meeting higher requirements for residual adhesive and tack reduction after curing.

[0003] Currently, researchers have attempted to reduce adhesive residue by modifying existing anti-tack adhesive systems. Their designed UV anti-tack adhesive systems include acrylate copolymer-based adhesives, bifunctional polyurethane prepolymers, crosslinking agents, photoinitiators, and dispersants. The polyurethane prepolymer with isocyanate end groups can crosslink with acrylate copolymer-based adhesives containing hydroxyl and carboxyl groups to form a network structure. This network then forms an interpenetrating network structure with the polymer network generated after UV irradiation. Compared to a semi-interpenetrating network structure, this network is denser and has better peel performance. However, experiments have shown that the peel strength of the anti-tack adhesive remains high after UV irradiation, and the residue of the pyrolytic small-molecule photoinitiator easily migrates to the wafer surface, also easily forming adhesive residue. Other researchers have designed hydroxyl-terminated fumaric acid chloride-pentanediol copolyesters, isophorone diisocyanate, chain extenders, and free radical small-molecule photoinitiators as... The existing UV-resistant adhesive system exhibits a 180° peel strength of 19 N / 25 mm before UV curing and 0.4 N / 25 mm after UV curing. However, due to its multi-component formulation, compatibility issues arise, leading to significant fluctuations in peel strength before UV irradiation. Furthermore, small-molecule photoinitiators remain free within the system, easily migrating to the adhesive surface and causing residue. Additionally, the significantly increased cohesive strength of the adhesive layer after curing results in a high maximum peel strength during the peeling process, potentially causing wafer breakage and reducing yield. Existing UV-resistant adhesives also include systems composed of acrylate copolymer base adhesives, multifunctional polyurethane prepolymers, photoinitiators, functional diluents, and other additives. While these compositions exhibit low adhesion and peel strength after UV irradiation, their complex composition and poor component compatibility lead to component precipitation, resulting in short shelf life. Therefore, there is an urgent need to research a new UV adhesive to address the inability of existing UV adhesives to simultaneously achieve low UV adhesion, high UV adhesion reduction, and low residue. Summary of the Invention

[0004] To address the above problems, the present invention provides a UV adhesive, a UV adhesive film, and a method for preparing the same.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] The first aspect of the present invention provides a UV adhesive comprising the following raw material components in parts by weight: 43-47 parts of isooctyl acrylate, 10-13 parts of butyl acrylate, 2-3 parts of hydroxyethyl acrylate, 4-5 parts of methyl methacrylate, 1-2 parts of acrylic acid, 2-4 parts of benzophenone monomers and 1-7 parts of tris(trimethylsiloxy)silyl monomers.

[0007] The molecular weight of the benzophenone monomer is 200-300.

[0008] The molecular weight of the tri(trimethylsiloxy)silyl monomer is 370-470.

[0009] Currently, traditional UV adhesives for reducing tack primarily achieve tack enhancement and reduction through the thermosetting reaction of active groups (such as isocyanate groups and epoxy groups) in the thermosetting agent with functional groups (such as hydroxyl and carboxyl groups) in the acrylate copolymer base. This process is complex, involves high curing temperatures, and consumes a lot of energy. Furthermore, the small molecules in the thermosetting agents used are difficult to react completely, and residues easily migrate to the wafer surface, forming adhesive residue. Therefore, to address the problems of complex composition, poor compatibility of components, and large amounts of adhesive residue in existing UV adhesive systems, there is an urgent need for a new type of UV adhesive.

[0010] While UV-resistant adhesives bonded only to benzophenone monomers exhibit self-adjusting and tack-reducing effects after UV irradiation, their insufficient internal polymerization strength leads to low initial peel strength, insignificant UV-adjusting and tack-reducing effects, and a tendency to leave residue. Through extensive experimentation, the inventors accidentally discovered that by simultaneously adding benzophenone monomers of specific molecular weights and tris(trimethylsiloxy)silyl monomers to the UV adhesive, the tris(trimethylsiloxy)silyl monomers effectively compensate for the low cohesive strength of benzophenone monomers, improving the cohesive strength of the UV adhesive to a certain extent. Furthermore, the Si-O-Si bonds in the tris(trimethylsiloxy)silyl monomers give the UV adhesive higher dynamic flexibility, reducing intermolecular forces in the system. Through synergistic action with benzophenone monomers, the surface tension and surface energy of the prepared UV adhesive are reduced during peeling, effectively lowering the peeling force and significantly reducing residue. The UV adhesive provided by this invention has a simple composition. It is easy to increase or decrease the viscosity of the UV adhesive by simply controlling the UV irradiation dose. There is no need to add additional thermosetting agents, photopolymerizing components, etc. This solves the problem of poor compatibility of existing UV adhesive systems. It not only facilitates uniform coating, but also fundamentally solves the problem of adhesive residue.

[0011] The inventors have demonstrated through extensive experiments that when the amount of benzophenone monomers is too high, the molecular weight of the UV adhesive is too large, resulting in a high degree of rigidity in the molecular chain and thus a low peel strength before UV irradiation. Conversely, when the amount of benzophenone monomers is too low, the crosslinking sites of the UV adhesive copolymer are too few, leading to poor tack reduction after UV irradiation. When the amount of tris(trimethylsiloxy)silyl monomers is too low, the cohesive strength of the copolymer is significantly low, resulting in a low peel strength of the UV adhesive before UV irradiation. Conversely, when the amount of tris(trimethylsiloxy)silyl monomers is too high, the molecular weight of the UV adhesive copolymer is too large, resulting in high rigidity, poor surface wetting ability, and difficulty in coating.

[0012] This invention further controls the addition of benzophenone monomers and tris(trimethylsiloxy)silyl monomers to give the UV adhesive suitable molecular weight, flexibility, and intermolecular forces. This facilitates the synergistic effect of benzophenone monomers and tris(trimethylsiloxy)silyl monomers, resulting in excellent tack-reducing and tack-reducing effects with minimal residue. This achieves a balance between low UV tack-reducing, high UV tack-reducing, and low residue. Before UV irradiation, the UV adhesive provided by this invention exhibits a 180° peel strength of 20N / 25mm-40N / 25mm. After low UV dose (5mJ / cm²), the peel strength further increases. 2 -30mJ / cm 2 After irradiation, UV adhesives can achieve a thickening effect, and the 180° peel strength can increase to 26N / 25mm-43N / 25mm; after high UV dose (30000mJ / cm²), the adhesive can achieve a thickening effect. 2 -40000mJ / cm 2 After irradiation, the crosslinking degree of the UV adhesive polymer increases significantly, achieving a reduced viscosity effect. The 180° peel strength can be reduced to 0.12N / 25mm-0.35N / 25mm, and the water contact angle of the substrate after peeling off the UV adhesive can be as low as 74.71°, close to the water contact angle of the blank substrate (72.68°). The UV adhesive provided by this invention also has extremely low residual amount.

[0013] Preferably, the benzophenone monomer is 4-acryloyloxybenzophenone.

[0014] Preferably, the tri(trimethylsiloxy)silane monomer is 3-methacryloyloxypropyltri(trimethylsiloxy)silane.

[0015] The structural formula of the UV adhesive provided by this invention is as follows:

[0016]

[0017] The present invention further specifies the specific substances of benzophenone monomers and tris(trimethylsiloxy)silyl monomers, which enables the UV adhesive to form a specific structure, giving the UV adhesive the advantages of both excellent tack-enhancing and tack-reducing effects and very little residual adhesive.

[0018] A second aspect of this invention provides a method for preparing a UV adhesive, comprising the following steps:

[0019] S1. Mix isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, benzophenone monomers and tris(trimethylsiloxy)silyl monomers evenly to obtain a polymer mixed solution;

[0020] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution;

[0021] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution;

[0022] S4. At 73℃-76℃, a 33wt%-50wt% mixture of the total volume of the mixture is reacted to obtain the first reactant;

[0023] S5. Add the remaining mixed solution to the first reactant, and then react at 73℃-76℃ to obtain UV adhesive.

[0024] Compared with existing technologies, the preparation method provided by this invention only requires the addition of an initiator to polymerize the UV adhesive raw material components, without the need for complex synthesis steps and operating equipment. The preparation process is green and environmentally friendly, and can be easily industrialized, thus reducing production costs to a certain extent. Furthermore, the preparation method provided by this invention only requires strict control of the monomer mass ratio, the selection of the initiator, and the reaction conditions to stably prepare consistent UV adhesive products, thereby ensuring the stability and reliability of product quality and facilitating large-scale production and quality control.

[0025] Preferably, in S2, the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is (1-2):(13-15):(13-15).

[0026] Preferably, in S3, the mass ratio of the polymer mixed solution to the initiator solution is (70-73):(27-32).

[0027] Preferably, by limiting the specific ratio of the initiator and the mixture of the initiator solution and the polymer solution, the present invention is beneficial to further improve the tack-adjusting effect of the UV adhesive and reduce the amount of residual adhesive during peeling.

[0028] Preferably, in step S4, the reaction time is 0.5h-1h.

[0029] Preferably, in step S5, the remaining mixed solution is added by uniform dripping for a period of 0.5-1 hour.

[0030] By controlling the time it takes for the uniform droplet to complete, it is beneficial to control the reaction rate and the molecular weight and distribution of the product, thereby further improving the performance of the UV adhesive.

[0031] Preferably, in S5, the condition for the reaction to end is that the viscosity of the reactants is 50000 mPa·s-200000 mPa·s.

[0032] Preferably, in step S5, after the reaction is complete, excess solvent needs to be evaporated.

[0033] A third aspect of the present invention provides a UV adhesive film, comprising a base film layer, a UV adhesive layer and a release film layer stacked sequentially;

[0034] The UV adhesive layer is prepared from the UV adhesive.

[0035] Preferably, the base film layer is composed of polyolefin or polyester.

[0036] Preferably, the thickness of the base film layer is 80μm-120μm.

[0037] Preferably, the thickness of the UV adhesive layer is 28μm-32μm.

[0038] Preferably, the release film layer is composed of polyester or polyolefin.

[0039] Preferably, the thickness of the release film layer is 20μm-50μm.

[0040] A fourth aspect of the present invention provides a method for preparing a UV adhesive film, comprising the following steps:

[0041] Step 1: Mix the UV adhesive and ethyl acetate evenly to obtain a UV adhesive solution with a solid content of 45%-55%;

[0042] Step 2: Apply the UV adhesive solution onto the base film layer and dry it to obtain the composite layer;

[0043] Step 3: Expose the composite layer to UV light, then attach a release film layer, and age it to obtain a UV adhesive film.

[0044] Preferably, in step 2, the base film layer also requires corona treatment.

[0045] Preferably, in step 2, the drying conditions are: temperature of 78℃-80℃ and time of 2.5min-3min.

[0046] Preferably, in step 3, the wavelength of the UV light used for irradiation is 365 nm, and the UV dose is 5 mJ / cm². 2 -30mJ / cm 2 .

[0047] Preferably, in step 3, the aging conditions are: temperature 34℃-36℃, humidity 59%-61%, and time 23h-25h. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] To better illustrate the present invention, further examples are provided below.

[0050] Example 1

[0051] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 45 parts isooctyl acrylate, 11 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 2 parts 4-acryloyloxybenzophenone, and 2 parts 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0052] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0053] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0054] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 1:14:14.

[0055] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 70:29;

[0056] S4. At 75°C, add 50wt% mixed solution to the reactor and react for 0.5h to obtain the first reactant;

[0057] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, and control the time for the uniform dropwise addition to be completed to 1 hour. Then react at 75°C until the viscosity of the reactant is 50000 mPa·s, stop the reaction, evaporate the solvent, and obtain the UV adhesive.

[0058] Example 2

[0059] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 45 parts isooctyl acrylate, 11 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 3 parts 4-acryloyloxybenzophenone, and 2 parts 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0060] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0061] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0062] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 2:15:15.

[0063] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 71:32;

[0064] S4. At 73°C, a 33wt% mixed solution was added to the reactor and reacted for 1 hour to obtain the first reactant.

[0065] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, controlling the time for the uniform dropwise addition to be completed to 0.5 h. Then react at 76 °C until the viscosity of the reactant reaches 80000 mPa·s, stop the reaction, evaporate the solvent, and obtain the UV adhesive.

[0066] Example 3

[0067] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 45 parts isooctyl acrylate, 11 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 4 parts 4-acryloyloxybenzophenone, and 2 parts 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0068] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0069] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0070] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 1:14:15.

[0071] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 72:30;

[0072] S4. At 76°C, a 40wt% mixed solution was added to the reactor and reacted for 0.7h to obtain the first reactant.

[0073] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, controlling the time for the uniform dropwise addition to be completed to 0.6 h. Then react at 73 °C until the viscosity of the reactant reaches 120000 mPa·s, then stop the reaction, evaporate the solvent, and obtain the UV adhesive.

[0074] Example 4

[0075] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 46 parts isooctyl acrylate, 12 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 2 parts 4-acryloyloxybenzophenone, and 1 part 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0076] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0077] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0078] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 1:14:14.

[0079] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 71:29;

[0080] S4. At 75°C, add 50wt% mixed solution to the reactor and react for 0.5h to obtain the first reactant;

[0081] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, and control the time for the uniform dropwise addition to be completed to 1 hour. Then react at 75°C until the viscosity of the reactant is 50000 mPa·s, stop the reaction, evaporate the solvent, and obtain the UV adhesive.

[0082] Example 5

[0083] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 44 parts isooctyl acrylate, 11 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 2 parts 4-acryloyloxybenzophenone, and 4 parts 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0084] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0085] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0086] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 1:14:14.

[0087] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 71:29;

[0088] S4. At 75°C, add 50wt% mixed solution to the reactor and react for 0.5h to obtain the first reactant;

[0089] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, controlling the time for the uniform dropwise addition to be completed to 1 hour. Then react at 75°C until the viscosity of the reactant reaches 120000 mPa·s, then stop the reaction and evaporate the solvent to obtain the UV adhesive.

[0090] Example 6

[0091] This embodiment provides a UV adhesive comprising the following raw material components in parts by weight: 43 parts isooctyl acrylate, 11 parts butyl acrylate, 3 parts hydroxyethyl acrylate, 5 parts methyl methacrylate, 2 parts acrylic acid, 2 parts 4-acryloyloxybenzophenone, and 7 parts 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0092] This embodiment also provides a method for preparing the above-mentioned UV adhesive, including the following steps:

[0093] S1. Weigh out isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, 4-acryloyloxybenzophenone and 3-methacryloyloxypropyltris(trimethylsiloxy)silane and mix them evenly to obtain a polymer mixed solution.

[0094] S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 2:15:15.

[0095] S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixed solution and the initiator solution is 73:32;

[0096] S4. At 75°C, add 50wt% mixed solution to the reactor and react for 0.5h to obtain the first reactant;

[0097] S5. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, and control the time for the uniform dropwise addition to be completed to 1 hour. Then react at 75°C until the viscosity of the reactant reaches 200,000 mPa·s. Stop the reaction, evaporate the solvent, and obtain the UV adhesive.

[0098] Comparative Example 1

[0099] This comparative example provides a UV adhesive that differs from Example 1 in that the amount of 4-acryloyloxybenzophenone is increased. Specifically, it includes the following raw material components in parts by weight: 45 parts of isooctyl acrylate, 11 parts of butyl acrylate, 3 parts of hydroxyethyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid, 6 parts of 4-acryloyloxybenzophenone, and 2 parts of 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0100] Other operations are the same as in Example 1.

[0101] Comparative Example 2

[0102] This comparative example provides a UV adhesive that differs from Example 1 in that the amount of 4-acryloyloxybenzophenone is reduced. Specifically, it includes the following raw material components in parts by weight: 45 parts of isooctyl acrylate, 11 parts of butyl acrylate, 3 parts of hydroxyethyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid, 1.5 parts of 4-acryloyloxybenzophenone, and 2 parts of 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0103] Other operations are the same as in Example 1.

[0104] Comparative Example 3

[0105] This comparative example provides a UV adhesive that differs from Example 1 in that the amount of 3-methacryloyloxypropyltris(trimethylsiloxy)silane is reduced. Specifically, it includes the following raw material components in parts by weight: 45 parts of isooctyl acrylate, 11 parts of butyl acrylate, 3 parts of hydroxyethyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid, 2 parts of 4-acryloyloxybenzophenone, and 0.5 parts of 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0106] Other operations are the same as in Example 1.

[0107] Comparative Example 4

[0108] This comparative example provides a UV adhesive that differs from Example 1 in that the amount of 3-methacryloyloxypropyltris(trimethylsiloxy)silane is increased. Specifically, it includes the following raw material components in parts by weight: 45 parts of isooctyl acrylate, 11 parts of butyl acrylate, 3 parts of hydroxyethyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid, 2 parts of 4-acryloyloxybenzophenone, and 8 parts of 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0109] Other operations are the same as in Example 1.

[0110] Result: The colloid was too hard to be removed.

[0111] Comparative Example 5

[0112] This comparative example differs from Example 1 in that 3-methacryloyloxypropyltris(trimethylsiloxy)silane is replaced with an equal amount of 3-methacryloyloxypropylmethyldimethoxysilane.

[0113] Other operations are the same as in Example 1.

[0114] Result: After the remaining mixed solution was added to S5, it polymerized explosively and could not react normally.

[0115] Comparative Example 6

[0116] This comparative example differs from Example 1 in that 3-methacryloyloxypropyltris(trimethylsiloxy)silane is replaced with an equal amount of methacryloyloxypropylmethyldiethoxysilane.

[0117] Other operations are the same as in Example 1.

[0118] Result: After the remaining mixed solution was added to S5, it polymerized explosively and could not react normally.

[0119] Comparative Example 7

[0120] This comparative example provides a UV adhesive that differs from Example 1 in that 4-acryloyloxybenzophenone is replaced with an equal amount of benzophenone.

[0121] Other operations are the same as in Example 1.

[0122] Comparative Example 8

[0123] This comparative example provides a UV adhesive, including the following preparation method:

[0124] 1. Under a nitrogen atmosphere, 32 parts of castor oil, 21 parts of isophorone diisocyanate, 1 part of dibutyltin dilaurate and 25 parts of ethyl acetate were placed in a four-necked flask and stirred at 60°C for 6 hours. Then, 20 parts of pentaerythritol triacrylate and 1 part of p-tert-butylcatechol were added. The NCO content of the reactants was measured every 0.5 hours. When the designed value was reached, the reaction was stopped to obtain castor oil-based polyurethane prepolymer.

[0125] 2. Mix 45 parts of isooctyl acrylate, 11 parts of butyl acrylate, 3 parts of hydroxyethyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid and 2 parts of 4-acryloyloxybenzophenone evenly to obtain a polymer mixed solution.

[0126] 3. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution, wherein the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is 1:14:14.

[0127] 4. Mix the polymer mixture solution and the initiator solution evenly to obtain a mixed solution, wherein the mass ratio of the polymer mixture solution to the initiator solution is 70:29;

[0128] 5. At 75°C, add 50 wt% mixed solution to the reactor and react for 0.5 h to obtain the first reactant;

[0129] 6. Add the remaining mixed solution dropwise to the first reactant at a uniform rate, controlling the time for the uniform dropwise addition to be completed to 1 hour. Then react at 75℃ until the viscosity of the reactant is 50000 mPa·s, stop the reaction, evaporate the solvent, and obtain the main adhesive.

[0130] 7. Mix castor oil-based polyurethane prepolymer, main adhesive, pentaerythritol triacrylate and ethyl acetate in a mass ratio of 100:100:20:80 to obtain UV adhesive.

[0131] Other operations are the same as in Example 1.

[0132] The UV adhesives prepared in Examples 1-6 and Comparative Examples 1-3 and 7 were used to prepare UV adhesive films, including the following steps:

[0133] Step 1: Mix the above UV adhesive and ethyl acetate evenly to obtain a UV adhesive solution with a solid content of 45%-55%.

[0134] Step 2: Coat the UV adhesive solution onto a 100μm thick polyolefin-based film layer and dry it to obtain a composite layer, wherein the thickness of the UV adhesive layer is 30μm.

[0135] Step 3: Expose the composite layer to low UV irradiation, then attach a polyester release film layer with a thickness of 20μm, and age it to obtain a UV adhesive film.

[0136] The UV adhesive prepared in Comparative Example 8 was used to make a UV adhesive film, including the following steps:

[0137] Step 1: Mix the above UV adhesive and ethyl acetate evenly to obtain a UV adhesive solution with a solid content of 45%-55%;

[0138] Step 2: Coat the UV adhesive solution onto a 100μm thick polyolefin-based film layer and dry it to obtain a composite layer, wherein the thickness of the UV adhesive layer is 30μm.

[0139] Step 3: Expose the composite layer to low UV irradiation, then attach a polyester release film layer with a thickness of 20μm, and age it to obtain a UV adhesive film.

[0140] The UV adhesives prepared in Examples 1-6 and Comparative Examples 1-3 and 7-8 were tested for their 180° peel strength before UV irradiation. The UV adhesives of Examples 1-6 and Comparative Examples 1-3 and 7-8 were irradiated with UV light at a wavelength of 365 nm. In Examples 1-4 and Comparative Examples 1-3 and 7-8, the controlled dose was 25 mJ / cm². 2 Example 5: The controlled dose was 10 mJ / cm². 2 Example 6: The controlled dose was 5 mJ / cm². 2 The peel strength after 180° exposure to low UV doses was tested. UV adhesives from Examples 1-6 and Comparative Examples 1-3 and 7-8 were irradiated with UV light at a wavelength of 365 nm. The controlled dose for Examples 1-6 and Comparative Examples 1-3 and 7 was 40000 mJ / cm². 2 Comparative Example 8: Controlled dose of 8000 mJ / cm 2 The peel strength after 180° exposure to high UV dose UV irradiation was tested; the number-average molecular weight of the UV adhesive was calculated and the water contact angle was statistically analyzed.

[0141] The 180° peel strength was tested according to the method of GB / T2792-2014.

[0142] The method for determining the number-average molecular weight includes the following: using tetrahydrofuran as the eluent, the molecular weight of the UV gel is tested using a gel permeation chromatography instrument (Waters 1515) (test temperature is 25℃, flow rate is 1mL / min), and a standard curve is prepared using polystyrene standard to determine the number-average molecular weight of the sample.

[0143] The method for testing the water contact angle includes the following: a UV adhesive film is adhered to the wafer surface, and after UV curing, the adhesive film is peeled off. The water contact angle of the wafer surface is then tested using a Theta Flex contact angle meter.

[0144] The specific test results are shown in Table 1:

[0145] Table 1

[0146]

[0147]

[0148]

[0149] The UV adhesive provided in this embodiment of the invention has a 180° peel strength of 20N / 25mm-40N / 25mm before UV irradiation, and after low UV dose (5mJ / cm²), the peel strength can reach 20N / 25mm-40N / 25mm. 2 -30mJ / cm 2 After irradiation, UV adhesives can achieve a thickening effect, and the 180° peel strength can increase to 26N / 25mm-43N / 25mm; after high UV dose (30000mJ / cm²), the adhesive can achieve a thickening effect. 2 -40000mJ / cm 2 After irradiation, the crosslinking degree of the UV adhesive polymer increases significantly, achieving a reduced viscosity effect. The 180° peel strength can be reduced to 0.12N / 25mm-0.35N / 25mm, and the water contact angle of the substrate after peeling off the UV adhesive can be as low as 74.71°, close to the water contact angle of the blank substrate (72.68°). The UV adhesive provided by this invention also has extremely low residual amount.

[0150] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A UV adhesive, characterized in that, The raw material components include the following parts by weight: 43-47 parts of isooctyl acrylate, 10-13 parts of butyl acrylate, 2-3 parts of hydroxyethyl acrylate, 4-5 parts of methyl methacrylate, 1-2 parts of acrylic acid, 2-4 parts of benzophenone monomers and 1-7 parts of tris(trimethylsiloxy)silyl monomers. The molecular weight of the benzophenone monomer is 200-300. The molecular weight of the tris(trimethylsiloxy)silyl monomer is 370-470; The benzophenone monomer is 4-acryloyloxybenzophenone; The tri(trimethylsiloxy)silyl monomer is 3-methacryloyloxypropyltri(trimethylsiloxy)silane; The preparation method of the UV adhesive includes the following steps: S1. Mix isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, benzophenone monomers and tris(trimethylsiloxy)silyl monomers evenly to obtain a polymer mixed solution; S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution; S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution; S4. React a 33wt%-50wt% mixture of the total volume of the mixture at 73℃-76℃ to obtain the first reactant; S5. Add the remaining mixed solution to the first reactant, and then react at 73℃-76℃ to obtain UV adhesive; In S2, the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is (1-2):(13-15):(13-15); in S3, the mass ratio of the polymer mixed solution and the initiator solution is (70-73):(27-32).

2. A method for preparing the UV adhesive according to claim 1, characterized in that, Includes the following steps: S1. Mix isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, acrylic acid, benzophenone monomers and tris(trimethylsiloxy)silyl monomers evenly to obtain a polymer mixed solution; S2. Mix benzoyl peroxide, anhydrous ethanol and ethyl acetate evenly to obtain an initiator solution; S3. Mix the polymer mixed solution and the initiator solution evenly to obtain a mixed solution; S4. React a 33wt%-50wt% mixture of the total volume of the mixture at 73℃-76℃ to obtain the first reactant; S5. Add the remaining mixed solution to the first reactant, and then react at 73℃-76℃ to obtain UV adhesive.

3. The method for preparing the UV adhesive as described in claim 2, characterized in that, In S2, the mass ratio of benzoyl peroxide, anhydrous ethanol and ethyl acetate is (1-2):(13-15):(13-15).

4. The method for preparing the UV adhesive as described in claim 2, characterized in that, In S3, the mass ratio of the polymer mixed solution to the initiator solution is (70-73):(27-32).

5. The method for preparing the UV adhesive as described in claim 2, characterized in that, In S4, the reaction time is 0.5h-1h.

6. The method for preparing the UV adhesive as described in claim 2, characterized in that, In step S5, the remaining mixed solution is added dropwise at a constant rate over a period of 0.5-1 hour.

7. The method for preparing the UV adhesive as described in claim 2, characterized in that, In S5, the reaction ends when the viscosity of the reactant is 50,000 mPa·s - 200,000 mPa·s.

8. A UV adhesive film, characterized in that, It includes a base film layer, a UV adhesive layer, and a release film layer stacked sequentially; The UV adhesive layer is prepared from the UV adhesive described in claim 1.

9. A method for preparing the UV adhesive film according to claim 8, characterized in that, Includes the following steps: Step 1: Mix the UV adhesive and ethyl acetate evenly to obtain a UV adhesive solution with a solid content of 45%-55%; Step 2: Apply the UV adhesive solution onto the base film layer and dry it to obtain the composite layer; Step 3: Expose the composite layer to UV light, then attach a release film layer, and age it to obtain a UV adhesive film.

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