A uv debonding adhesive and its use

Abstract

This invention provides a UV-resistant adhesive and its application. The UV-resistant adhesive comprises an acrylate polymer, which is obtained by polymerizing at least a soft monomer, a hard monomer, a functional monomer, and a graft monomer. The soft monomer includes at least one of isooctyl acrylate, n-butyl acrylate, isononyl acrylate, and ethyl acrylate. The hard monomer includes at least one of methyl methacrylate, isobornyl methacrylate, methyl acrylate, and vinyl acetate. The functional monomer includes carboxyl-containing acrylate monomers and hydroxyl-containing acrylate monomers. The graft monomer includes at least one of isocyanoethyl methacrylate and isocyanoethyl acrylate.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, and particularly relates to a UV-resistant adhesive and its application. Background Technology

[0002] In the manufacturing processes of display panels, optical devices, and precision electronic components, temporary fixation and non-destructive separation are common process requirements. For example, the assembly and disassembly of mobile phone or watch displays and cover glass, the temporary bonding of substrates to carriers, and the positioning and fixation of PCBs or FPCs during drilling or punching processes all require a solution that provides sufficient adhesion while allowing for easy peeling without damaging the device after the operation. UV-reducing adhesive tape has gained industry attention due to its unique properties. It maintains good adhesion when not exposed to ultraviolet light, facilitating temporary positioning or assembly. After completing specific process requirements, simply irradiating the tape with a specific wavelength of ultraviolet light reduces its adhesion, thus enabling peeling.

[0003] However, applying UV anti-adhesion tapes to these precision applications still faces numerous practical challenges. In display module or circuit board manufacturing, the bonding area is often very small, and the surfaces to be bonded may contain various materials such as glass, metal, and resin. On the one hand, it is difficult for the UV light source to precisely and evenly irradiate the tape's location, easily creating blind spots or resulting in incomplete local anti-adhesion. If residual adhesive remains upon peeling, it may pull on surrounding precision circuitry or contaminate surrounding optical coatings; while excessive irradiation may cause aging of the tape substrate or the formation of exudates, affecting product cleanliness or yield. On the other hand, due to the significant differences in surface energy of the bonded materials, the initial adhesion of the tape may exhibit inconsistent bonding effects, thus affecting positioning accuracy or the stability of temporary fixation. Summary of the Invention

[0004] In order to reduce the ultraviolet light irradiation energy threshold of UV-resistant adhesives and broaden their light response window, this invention provides a UV-resistant adhesive and its application.

[0005] According to one aspect of the present invention, a UV-resistant adhesive is provided, comprising an acrylate polymer, wherein the acrylate polymer is obtained by polymerization of at least a soft monomer, a hard monomer, a functional monomer, and a graft monomer; wherein the soft monomer comprises at least one selected from isooctyl acrylate, n-butyl acrylate, isononyl acrylate, and ethyl acrylate; the hard monomer comprises at least one selected from methyl methacrylate, isobornyl methacrylate, methyl acrylate, and vinyl acetate; the functional monomer comprises a carboxyl-containing acrylate monomer and a hydroxyl-containing acrylate monomer; and the graft monomer comprises at least one selected from isocyanoethyl methacrylate and isocyanoethyl acrylate.

[0006] In this invention, the isocyanate groups in the grafted monomer can react with the hydroxyl groups in the functional monomer to form a urethane structure, which helps to increase the molecular chain size and improve the photoresponse rate. Simultaneously, it allows the adhesive layer to maintain high sensitivity to ultraviolet light in the wavelength range of 250 nm to 400 nm, achieving effective anti-tack even under low light intensity. Furthermore, a small amount of residual active groups after the reaction can participate in secondary cross-linking, which is beneficial for improving the adhesion stability of the adhesive layer on different dial coatings (including specially treated surfaces). Based on the above design, this invention further reduces the ultraviolet light irradiation energy threshold of the UV anti-tack adhesive and broadens its photoresponse window through the synergistic effect of soft monomers, hard monomers, functional monomers, and grafted monomers. Specifically, the soft monomer imparts suitable flexibility and wettability to the adhesive, ensuring good adhesion to the bonded surface when not exposed to light; the hard monomer provides the necessary cohesive strength and dimensional stability, allowing the adhesive layer to maintain structural integrity during processing and storage. The hydroxyl groups in the functional monomer react with the isocyanate groups of the grafted monomer, grafting polymerizable olefinic unsaturated double bonds onto the acrylate backbone. Meanwhile, intermolecular hydrogen bonds formed between the carboxyl and hydroxyl groups in the functional monomer construct a physically cross-linked secondary network structure. Thus, the residual double bonds in the backbone, the olefinic unsaturated double bonds introduced by the grafted side chains, and the hydrogen bond network work together to more efficiently initiate cross-linking reactions under UV irradiation, thereby reducing the minimum required irradiation energy. Simultaneously, the olefinic double bonds in the grafted side chains, the residual double bonds in the backbone, and the reactive groups provided by the functional monomers with hydrogen bond assistance constitute various types of photoreactive sites. These sites with different structures have complementary response characteristics to different wavelengths of UV light, thus contributing to broadening the photoresponse window of the tape. This allows the UV-resistant adhesive provided by this invention to achieve a relatively uniform and thorough anti-tack effect even in the confined and complex internal environment of precision components, despite limitations in the irradiation angle or uneven intensity.

[0007] Preferably, the carboxyl-containing acrylate monomer includes at least one of acrylic acid and methacrylic acid, and / or the hydroxyl-containing acrylate monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0008] Preferably, the mass ratio of carboxyl-containing acrylate monomers to hydroxyl-containing acrylate monomers is 1:2~4. This invention, by optimizing the mass ratio of carboxyl-containing acrylate monomers to hydroxyl-containing acrylate monomers in the functional monomers, not only forms a more balanced intermolecular hydrogen bond network but also provides an appropriate amount of active hydroxyl groups for the grafting reaction. This ratio helps to provide relatively sufficient hydrogen bond crosslinking points, thereby enhancing the cohesive strength of the adhesive layer and reducing the possibility of excessive carboxyl groups leading to high acidity or insufficient hydroxyl groups affecting grafting efficiency. Therefore, the UV anti-tack adhesive exhibits relatively stable adhesion properties before curing, and after curing, the moderately dense crosslinking structure helps to achieve a faster anti-tack effect, while also ensuring long-term storage stability and weather resistance.

[0009] Preferably, the number-average molecular weight of the acrylate polymer is 400,000 to 700,000, and the weight-average molecular weight is 700,000 to 1,200,000.

[0010] Preferably, the preparation of the acrylate polymer includes the following steps: Step 1: The soft monomer, hard monomer, and functional monomer are each divided into two parts, and the initiator is divided into three parts; the soft monomer, hard monomer, functional monomer, initiator, and solvent of the first part are mixed and heated to 75℃~80℃ under a protective gas atmosphere for 20~40 minutes; then the soft monomer, hard monomer, functional monomer, and initiator of the second part are added dropwise to the reaction system for 2 hours to 2.5 hours, and the reaction is maintained at the temperature for 3 hours to 4 hours after the addition is completed; then the initiator of the third part is added to the reaction system, and the reaction is maintained at the temperature for 1.5 hours to 2 hours to obtain the acrylate precursor; Step 2: The acrylate precursor is cooled to 40℃~50℃, an inhibitor is added and a protective gas is introduced for 20 minutes to 30 minutes, then a mixture of grafted monomer and catalyst A is added dropwise, and the reaction is maintained at the temperature for 4 hours to 5 hours to obtain the acrylate polymer.

[0011] Preferably, after adding the polymerization inhibitor and purging the protective gas in step two for 20 to 30 minutes, the photoinitiator is added and reacted for 1 to 2 hours. Then, a mixture of grafted monomer and catalyst A is added dropwise and the reaction is maintained at a certain temperature for 4 to 5 hours to obtain the acrylate polymer.

[0012] Preferably, the amount of soft monomer in the first part accounts for 10% to 20% of the total mass of soft monomer.

[0013] Preferably, the amount of hard monomer in the first part accounts for 10% to 20% of the total mass of hard monomer.

[0014] Preferably, the amount of the functional monomer in the first part accounts for 10% to 20% of the total mass of the functional monomer.

[0015] Preferably, the amount of the initiator in the first part accounts for 20% to 25% of the total mass of the initiator.

[0016] Preferably, the amount of initiator in the second part accounts for 50% to 60% of the total mass of the initiator.

[0017] Preferably, the initiator in the third part is dissolved in a small amount of solvent before being added to the reaction system.

[0018] Preferably, in step two, the NCO content is determined by di-n-butylamine back titration. When the mass fraction of NCO is less than 0.3%, it is considered the reaction endpoint, and the acrylate polymer is obtained.

[0019] Preferably, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, tert-butyl hydroperoxide, and dicumyl peroxide.

[0020] Preferably, the polymerization inhibitor includes at least one of polymerization inhibitor 701, polymerization inhibitor 702, polymerization inhibitor 705, polymerization inhibitor 706, methylhydroquinone, and p-benzoquinone.

[0021] Preferably, catalyst A comprises an organotin catalyst or an organobismuth catalyst.

[0022] Preferably, the acrylate polymer is prepared by weight parts comprising 75 to 80 parts of soft monomer, 5 to 15 parts of hard monomer, 4 to 15 parts of functional monomer, and 2 to 6 parts of graft monomer.

[0023] Preferably, the preparation of the acrylate polymer further includes 0.1 to 2 parts by mass of initiator.

[0024] Preferably, the preparation of the acrylate polymer further includes 0.01 to 0.5 parts of catalyst, calculated by mass parts.

[0025] Preferably, the UV-cured adhesive further includes a crosslinking agent, which comprises a high-functionality resin with a functionality of 3-10. By employing a high-functionality resin with a functionality of 3-10, this invention further optimizes the adhesiveness of the colloid before UV irradiation, thereby further improving the adhesion between the colloid and the bonded surface. Furthermore, after UV curing, the high-functionality resin and the acrylate polymer together form a dense three-dimensional crosslinked network, effectively restricting the movement of molecular chain segments, thus significantly reducing interfacial adhesion and achieving a rapid and thorough anti-tack effect.

[0026] Preferably, the high-functionality resin includes trifunctional resin and hexafunctional resin, and the ratio of trifunctional resin to hexafunctional resin is 1:2~4 by mass.

[0027] Preferably, the trifunctional resin includes at least one of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and tri(2-hydroxyethyl)isocyanurate triacrylate; the hexafunctional resin includes at least one of dipentaerythritol hexaacrylate and hexafunctional polyurethane acrylate. High-functionality resins with a functionality greater than 6 are generally polyurethane acrylate polymers, typically hexafunctional, octahedral, quintahedral, or decafunctional, such as the ETERCURE series from Changxing Chemical, the Sartomer CN series, the EBECREL series from Zhanxin Chemical, and the Wannate series from Wanhua Chemical.

[0028] Preferably, the UV anti-tack adhesive includes a photoinitiator, which includes at least one of carbon-carbon double bonds and isocyanate groups. In tiny areas such as precision components, small-molecule photoinitiators in the adhesive layer are prone to precipitation or migration, resulting in residues and contamination of surrounding precision parts when the adhesive layer is peeled off. Furthermore, photoinitiators migrating to the surface and their decomposition products may cause yellowing of the adhesive layer, potentially affecting the dial's appearance. This invention employs photoinitiators containing carbon-carbon double bonds or isocyanate groups, grafting the photoinitiator into the cross-linked structure of the acrylate polymer in the form of chemical bonds. While retaining the photoinitiating groups, this not only reduces the potential precipitation or migration of small-molecule photoinitiators but also improves the compatibility of the system and reduces phase separation in the colloid. Specifically, the isocyanate groups can react with the hydroxyl groups in the functional monomers, while the carbon-carbon double bonds can be incorporated into the acrylate segments via thermally initiated polymerization.

[0029] Preferably, the preparation method of the photoinitiator includes the following steps: Step S1, mixing the hydroxyl-containing photoinitiator, solvent B and catalyst B, and then slowly adding it dropwise to solvent B containing diisocyanate, and reacting at 55℃~65℃ for 6 hours~8 hours under a protective gas atmosphere to obtain the photoinitiator containing NCO groups.

[0030] Preferably, the preparation method of the photoinitiator further includes step S2, slowly adding a solution B containing hydroxy acrylate to the reaction system of the photoinitiator containing NCO groups, continuing to stir the reaction for 5 to 8 hours, and then performing vacuum distillation to obtain a photoinitiator containing carbon-carbon double bonds.

[0031] Preferably, in step S2 of the photoinitiator preparation, the -NCO value is monitored by di-n-butylamine back titration or FTIR to reach the NCO content. When the mass fraction of NCO is less than 0.3%, it is considered the reaction endpoint. Subsequently, the photoinitiator is obtained by vacuum distillation.

[0032] Preferably, in step S2, the solvent B containing hydroxy acrylate is added dropwise over 1 to 2 hours.

[0033] Preferably, the hydroxyl-containing photoinitiator is an α-hydroxy ketone initiator and / or a hydroxythioxanthone, wherein the α-hydroxy ketone initiator includes at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, and 2-hydroxy-1-(4-(2-hydroxy-2-methylpropanoyl)phenyl)-2-methylpropanone; and the hydroxythioxanthone includes 2-(2-hydroxyethoxy)thioxanthone or 2-(2,3-dihydroxy)propoxythioxanthone. It should be noted that when a hydroxythioxanthone is used as the hydroxyl-containing photoinitiator, a small amount of tertiary amine accelerator needs to be introduced during the stage of adding the crosslinking agent and / or curing agent to the UV adhesive.

[0034] Preferably, the molar ratio of the hydroxyl-containing photoinitiator to the diisocyanate is 1:1.01~1.2.

[0035] Preferably, the hydroxyl-containing acrylate includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate.

[0036] Preferably, the amount of hydroxy acrylate added in step S2 is calculated according to a molar ratio of 1 to 1.1:1 with the residual NCO groups in the system in step S1.

[0037] Preferably, the diisocyanate includes at least one of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), hydrogenated diphenylmethane diisocyanate (H12MDI), and toluene diisocyanate (TDI).

[0038] Preferably, catalyst B comprises an organotin catalyst or an organobismuth catalyst.

[0039] Preferably, solvent B is at least one of toluene, ethyl acetate, and acetone.

[0040] Preferably, the method for preparing UV-resistant adhesive includes the following steps: mixing an acrylate polymer with a crosslinking agent, a curing agent, and a solvent to obtain a UV-resistant adhesive material.

[0041] Preferably, the raw materials for preparing the UV-resistant adhesive, calculated by mass parts, include 70 to 80 parts of acrylate polymer, 0.1 to 3 parts of photoinitiator, and 0.1 to 5 parts of crosslinking agent.

[0042] Preferably, the UV-resistant adhesive further includes 0.01 to 3 parts of curing agent by weight.

[0043] Preferably, the curing agent includes at least one of an NCO-containing curing agent and an epoxy-containing curing agent. The NCO-containing curing agent is selected from any one of diisocyanate, isocyanate trimer, or polyisocyanate prepolymer; the epoxy-containing curing agent is selected from bisphenol A or bisphenol F type low molecular weight epoxy curing agents, such as Huntsman G240, Dow DER331, and Nanya NPEL-128. To improve curing efficiency, tertiary amine, polyamide, or aliphatic amine accelerators are generally required. The NCO-containing curing agent can crosslink with the hydroxyl groups in the raw material, while the epoxy-containing curing agent can crosslink with the carboxyl groups in the raw material.

[0044] In a second aspect, the present invention provides a UV anti-adhesion tape comprising an anti-adhesion layer and a release film, wherein the anti-adhesion layer comprises the UV anti-adhesion as described above.

[0045] Preferably, the UV anti-adhesion tape further includes a substrate layer having a first surface and a second surface opposite to each other, and the anti-adhesion layer includes a first anti-adhesion layer and a second anti-adhesion layer; the first anti-adhesion layer is disposed on the first surface, and the second anti-adhesion layer is disposed on the second surface; the transmittance of the substrate layer is higher than 70%.

[0046] Preferably, the thicknesses of the first anti-adhesive layer and the second anti-adhesive layer are 25μm to 35μm, respectively.

[0047] Preferably, the substrate layer includes at least one of polyolefin (PO), ethylene-vinyl acetate copolymer (EVA), polyethylene terephthalate (PET), thermoplastic polyurethane elastomer (TPU), and transparent acrylic foam, and the thickness of the substrate layer is 100μm~150μm.

[0048] Preferably, the release film includes at least one of silicone release film, fluorinated release film, and non-silicone release film. The peel strength of the release film is preferably 5 N / 25 mm to 15 N / 25 mm, and the thickness of the release film is 30 μm to 50 μm.

[0049] More preferably, the release film is a black light-blocking release film with a thickness of 50 μm.

[0050] A third aspect of the invention provides the application of the UV anti-adhesive adhesive or the UV anti-adhesive tape described above in electronic components or electronic assemblies.

[0051] Preferably, the electronic component includes at least one of a display panel, a cover glass, a flexible circuit board, a semiconductor substrate, or a ceramic substrate.

[0052] Preferably, the electronic component includes at least one of a display module, a touch module, a camera module, a sensor module, or a packaging module. Detailed Implementation

[0053] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0054] Regarding the settings of the embodiment: Example 1 1. Preparation of UV-resistant adhesives In this embodiment, the raw materials for preparing the UV-resistant adhesive were weighed according to the formula shown in Table 1. Subsequently, the UV-resistant adhesive material was prepared according to the following steps: Step 1: Add 20% of the formulated amount of soft monomer, 20% of the formulated amount of hard monomer, 20% of the formulated amount of functional monomer, 25% of the formulated amount of initiator, and 40 parts of ethyl acetate to a reaction vessel. Heat to 75°C under a protective gas atmosphere and react for 30 minutes. Then, add the remaining soft monomer, hard monomer, and functional monomer, as well as 50% of the formulated amount of initiator and 200 parts of ethyl acetate dropwise to the vessel over a period of 2 hours. After the addition is complete, maintain the temperature for 4 hours. Immediately afterwards, dissolve the remaining initiator in 10 parts of ethyl acetate and add it dropwise to the reaction system. Continue to maintain the temperature for 1.5 to 2 hours to obtain the acrylate precursor. Step 2: Cool the acrylate precursor reaction system from Step 1 to 45°C, add a polymerization inhibitor, purge with nitrogen for 30 minutes, then add 2.5 parts of a photoinitiator containing NCO groups and react for 1.5 hours. When the NCO content in the system is below 0.3% as monitored by FTIR, add a mixture of grafted monomer and catalyst A dropwise, keep the reaction at the temperature for 4.5 hours, and stop the reaction when the NCO content in the system is below 0.3% as monitored by FTIR, to obtain the acrylate polymer. Step 3: Cool the acrylate polymer reaction system from Step 2 to below 30°C, add the crosslinking agent and curing agent and mix evenly. Adjust the solid content of the adhesive to 30% using a solvent. Filter the mixture through a 200-400 mesh stainless steel filter and degas it under vacuum (-0.08 MPa, 20 min) to obtain the UV-resistant adhesive.

[0055] The preparation of the NCO-containing photoinitiator used in step 2 is as follows: 10 parts of hydroxyl-containing photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), 20 parts of ethyl acetate and 0.005 parts of catalyst B (dibutyltin dilaurate) are mixed and then slowly added dropwise to solvent B (11 parts IPDI + 20 parts ethyl acetate) containing diisocyanate. The mixture is reacted at 55°C for 8 hours under a protective gas atmosphere to obtain the NCO-containing photoinitiator. Excess solvent and residual monomers are removed before use.

[0056] Table 1. Raw materials used in the preparation of UV-resistant adhesives in this embodiment.

[0057] 2. Preparation of UV-resistant adhesive tape This embodiment prepares UV anti-adhesion tape according to the following method, including the following steps: prepare a 50μm first silicone release film and a 50μm second silicone release film; apply UV anti-adhesion adhesive to one surface of the first silicone release film and the second silicone release film respectively; dry at 110°C to form a first anti-adhesion layer with a thickness of 30μm and a second anti-adhesion layer with a thickness of 30μm respectively; then laminate the first silicone release film with the first anti-adhesion layer to one side of the substrate; then laminate the second silicone release film with the second anti-adhesion layer to the other side of the substrate to obtain the UV anti-adhesion tape.

[0058] Example 2 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that, in preparing the acrylate polymer, the mass ratio of carboxyl-containing acrylate monomer (3 parts acrylic acid) to hydroxyl-containing acrylate monomer (12 parts hydroxyethyl acrylate) is 1:4. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0059] Example 3 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that, in preparing the acrylate polymer, the mass ratio of carboxyl-containing acrylate monomer (3 parts acrylic acid) to hydroxyl-containing acrylate monomer (6 parts hydroxyethyl acrylate) is 1:2. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0060] Example 4 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that, in preparing the acrylate polymer, the mass ratio of carboxyl acrylate monomer (2.5 parts acrylic acid) to hydroxyl acrylate monomer (8 parts hydroxyethyl acrylate) is 1:3.2. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0061] Example 5 This embodiment refers to the formulation and method provided in Example 1 to prepare UV anti-adhesive adhesive and UV anti-adhesive tape using the same formulation. The difference from Example 1 is that in this embodiment, an equal mass fraction of dipentaerythritol hexaacrylate is used instead of trimethylolpropane triacrylate during the preparation of the UV anti-adhesive adhesive. Apart from the above differences, the operational steps for preparing the UV anti-adhesive adhesive and UV anti-adhesive tape using the same formulation are strictly consistent with those in Example 1.

[0062] Example 6 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that in this embodiment, trimethylolpropane triacrylate is used instead of dipentaerythritol hexaacrylate in equal parts by mass during the preparation of the UV-resistant adhesive. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0063] Example 7 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that, in preparing the UV-resistant adhesive in this embodiment, the mass ratio of trifunctional resin (trimethylolpropane triacrylate): hexafunctional resin (dipentaerythritol hexaacrylate): decafunctional resin (Sartomer CN9026) is 1:3:0.5 (the total mass fraction of the crosslinking agent remains unchanged). Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation in this embodiment are strictly consistent with those in Example 1.

[0064] Example 8 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that in this embodiment, the total mass fraction of the crosslinking agent used in preparing the UV-resistant adhesive is 2 parts. Furthermore, the specific materials of the crosslinking agent used in this embodiment are a hexafunctional resin (dipentaerythritol hexaacrylate) and a decafunctional resin (Sartomer CN9026), with a hexafunctional resin:decafunctional resin ratio of 7:1. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation in this embodiment are strictly consistent with those in Example 1.

[0065] Example 9 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that the photoinitiator used in this embodiment contains carbon-carbon double bonds when preparing the UV-resistant adhesive; and in step 2, the amount of grafted monomer is adjusted to 7.35 parts. Apart from the above differences, the operating steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation in this embodiment are strictly consistent with those in Example 1. Specifically, in this embodiment, the photoinitiator is prepared as follows: 10 parts of a hydroxyl-containing photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), 20 parts of ethyl acetate, and 0.005 parts of catalyst B (dibutyltin dilaurate) are mixed and then slowly added dropwise to solvent B (11 parts IPDI + 20 parts ethyl acetate) containing diisocyanate. The mixture is reacted at 60°C for 7 hours under a protective gas atmosphere. Then, a mixture of 6 parts hydroxyethyl methacrylate and 10 parts ethyl acetate is slowly added dropwise to the system, and the reaction is continued with stirring for 6 hours. The reaction endpoint is considered when the -NCO value reaches less than 0.3% by FTIR monitoring. The photoinitiator is then obtained by vacuum distillation.

[0066] Example 10 This embodiment refers to the formulation and method provided in Example 9 to prepare UV-resistant adhesive and UV-resistant tape using it. The difference from Example 9 is that in this embodiment, the photoinitiator used in the preparation of the UV-resistant adhesive contains carbon-carbon double bonds, and in this embodiment, the photoinitiator is introduced after the acrylate polymer is prepared. Apart from the above differences, the operation steps for preparing the UV-resistant adhesive and UV-resistant tape using it in this embodiment are strictly consistent with those in Example 1. Specifically, the steps for preparing the acrylate polymer and the UV-resistant adhesive material in this embodiment are as follows: Step 1: Add 20% of the formulated amount of soft monomer, 20% of the formulated amount of hard monomer, 20% of the formulated amount of functional monomer, 25% of the formulated amount of initiator, and 40 parts of ethyl acetate to a reaction vessel. Heat to 75°C under a protective gas atmosphere and react for 30 minutes. Then, add the remaining soft monomer, hard monomer, and functional monomer, as well as 50% of the formulated amount of initiator and 200 parts of ethyl acetate dropwise to the vessel over a period of 2 hours. After the addition is complete, maintain the temperature for 4 hours. Immediately afterwards, dissolve the remaining initiator in 10 parts of ethyl acetate and add it dropwise to the reaction system. Continue to maintain the temperature for 1.5 to 2 hours to obtain the acrylate precursor. Step 2: Cool the acrylate precursor reaction system from Step 1 to 45°C, add a polymerization inhibitor, and purge with nitrogen for 30 minutes. If the NCO content in the system is below 0.3% as monitored by FTIR, add a mixture of grafted monomer and catalyst A dropwise, keep the reaction at the temperature for 4.5 hours, and stop the reaction if the NCO content in the system is below 0.3% as monitored by FTIR to obtain the acrylate polymer. Step 3: Cool the acrylate polymer reaction system from Step 2 to below 30°C, add 2.5 parts of a photoinitiator containing carbon-carbon double bonds, react for 1.5 hours, then add a crosslinking agent and a curing agent and mix evenly. Adjust the solid content of the adhesive to 30% using a solvent, filter through a 200-400 mesh stainless steel filter and vacuum degas (-0.08 MPa, 20 min) to obtain the UV-resistant adhesive.

[0067] Example 11 This embodiment refers to the formulation and method provided in Example 1 to prepare a UV-resistant adhesive and a UV-resistant tape using the same formulation. The difference from Example 1 is that, in preparing the UV-resistant adhesive, an equal mass fraction of 2-hydroxy-2-methyl-1-phenyl-1-propanone is used instead of the hydroxyl-containing photoinitiator in Example 1. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and the UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0068] Example 12 This embodiment refers to the formulation and method provided in Example 1 to prepare UV-resistant adhesive and UV-resistant tape using the same formulation. The difference from Example 1 is that in this embodiment, ethyl isocyanate acrylate (grafted monomer) in equal molar amounts of NCO is used instead of ethyl isocyanate methacrylate in Example 1 during the preparation of the UV-resistant adhesive. Apart from the above differences, the operation steps for preparing the UV-resistant adhesive and UV-resistant tape using the same formulation are strictly consistent with those in Example 1.

[0069] Comparative Example 1 This comparative example prepares a UV-resistant adhesive and a UV-resistant tape using the formulation and method provided in Example 1. The difference from Example 1 is that, in preparing the acrylate polymer, an equal mass fraction of carboxyl-containing acrylate monomers is used instead of hydroxyl-containing acrylate monomers. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and the UV-resistant tape using the same method in this comparative example are strictly consistent with those in Example 1.

[0070] Comparative Example 2 This comparative example prepares a UV-resistant adhesive and a UV-resistant tape using the formulation and method provided in Example 1. The difference from Example 1 is that, in preparing the acrylate polymer, an equal mass fraction of hydroxyl-containing acrylate monomers is used instead of carboxyl-containing acrylate monomers. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and the UV-resistant tape using the same method in this comparative example are strictly consistent with those in Example 1.

[0071] Comparative Example 3 This comparative example prepares a UV-resistant adhesive and a UV-resistant tape using the formulation and method provided in Example 1. The difference from Example 1 is that, in preparing the acrylate polymer, an equal mass fraction of glycidyl methacrylate is used instead of the grafted monomer. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and the UV-resistant tape using the same method in this comparative example are strictly consistent with those in Example 1.

[0072] Comparative Example 4 This comparative example prepares a UV-resistant adhesive and a UV-resistant tape using the formulation and method provided in Example 1. The difference from Example 1 is that, in preparing the acrylate polymer, the grafted monomers used in Example 1 are not added, and the remaining components are adjusted in equal proportions. Apart from the above differences, the operational steps for preparing the UV-resistant adhesive and the UV-resistant tape using the same formulation and method in this comparative example are strictly consistent with those in Example 1.

[0073] Test case 1. Test Object The UV anti-tack adhesives and UV anti-tack tapes prepared in Examples 1 to 12 and Comparative Examples 1 to 4.

[0074] 2. Testing Methods Peel strength before UV testing: According to the standard GB / T 2792-1998 "Test Method for 180° Peel Strength of Pressure-Sensitive Adhesive Tape", the laboratory environment requirements are as follows: A 170mm × 25mm tape is adhered to a steel plate, and a 2kg pressure roller is used to roll it back and forth three times. After standing for 20 minutes, the 180° peel force is measured using a tensile testing machine at a test speed of 300mm / min.

[0075] Peel strength after UV treatment: According to the standard GB / T 2792-1998 "Test Method for 180° Peel Strength of Pressure-Sensitive Adhesive Tape", the laboratory environment requirements are as follows: A 170mm × 25mm tape is adhered to a steel plate, and a 2kg pressure roller is used to roll it back and forth 3 times. After standing for 20 minutes, a UV light machine (LED surface light source, 365nm) is used at 500mJ / cm². 2 After being treated with ultraviolet light, the peel force at 180° was finally measured using a tensile testing machine at a test speed of 300 mm / min.

[0076] The tensile strength test method is as follows: Under a test environment of 23℃±1℃ and 50%±5% relative humidity, the tape is cut into 125mm×250mm specimens. The specimens are vertically clamped between a glass substrate and an aluminum alloy substrate (i.e., the two sides of the specimens are respectively attached to the surfaces of the glass substrate and the 3003 aluminum alloy substrate). Then, the assembled specimens are placed on a tensile testing machine and stretched vertically at a test speed of 100mm / min until the specimens break.

[0077] The test method for residual adhesive peeling is as follows: A 170mm × 25mm tape is adhered to a steel plate, and a 2kg pressure roller is used to roll it back and forth three times. After standing for 20 minutes, the tape is peeled off at a tensile testing machine at a test speed of 300mm / min at 180°. The amount of adhesive residue on the steel plate is observed and classified according to the degree of residue as no residue, slight residue, moderate residue, and severe residue.

[0078] 3. Test Results and Analysis The test results for this test example are shown in Table 1. The UV-resistant adhesive tape provided by this invention was tested and found to be suitable for UV light irradiation with wavelengths from 250nm to 400nm (preferably 365nm), and a UV light intensity of 100 mW / cm². 2 ~150 mW / cm 2 The exposure was 500 mj / cm. 2 ~1000 mJ / cm 2 This achieves reduced adhesion. Test results show that the residual adhesive residue of UV-reducing tape after UV irradiation depends not only on the cross-linked network structure of the adhesive layer but also on the interfacial adhesion between the substrate and the adhesive layer. Furthermore, since pull-out strength can reflect the adhesive ability of UV-reducing tape at different interfaces, it helps characterize the bonding and fixing effect of UV-reducing tape on the bonded components before UV irradiation.

[0079] Specifically, based on the data from Examples 1 to 4 and Comparative Examples 1 to 2, when the mass ratio of carboxyl-containing acrylate monomers to hydroxyl-containing acrylate monomers was within the preferred range, the tapes exhibited low peel strength and pull-out strength after UV irradiation, while no significant residue was observed. When the ratio was adjusted to the upper limit (Example 2) or the lower limit (Example 3), although the peel strength and residue after UV irradiation were still acceptable, slight residue appeared, indicating that both high and low relative contents of the single functional monomer could affect the cleanliness of the adhesive layer at the peel interface. In the schemes using only carboxyl-containing acrylate monomers (Comparative Example 1) or only hydroxyl-containing acrylate monomers (Comparative Example 2), the peel strength before UV irradiation decreased significantly, and residue was further aggravated. This reflects that the two functional monomers need to be properly combined to achieve the ideal temporary fixation effect.

[0080] Furthermore, based on the data from Examples 1 and 12, as well as Comparative Examples 3 and 4, it was found that the introduction of graft monomers has a significant impact on the anti-tack effect after UV treatment. When glycidyl methacrylate (in which case epoxy groups are introduced during grafting) is used instead of the graft monomer (Comparative Example 3) or no graft monomer is added (Comparative Example 4), the peel strength after UV treatment increases to 1.432 N / inch and 7.832 N / inch, respectively, while the pull-out strength is also at a low level, and relatively heavy and severe adhesive residues appear, respectively. In contrast, in Example 1, using isocyanate methacrylate as the graft monomer, the peel strength after UV treatment decreases to 0.274 N / inch, and there is no adhesive residue. In Example 12, using isocyanate acrylate instead of isocyanate methacrylate, the same adhesive residue-free effect is achieved, indicating that different types of isocyanate-based graft monomers can introduce photoreactive groups into the acrylate backbone through chemical bonding, which helps to reduce the peel strength after UV treatment and improve the adhesive residue situation.

[0081] Regarding the selection of high-functionality resins, in Example 5, using only a hexafunctional resin helped to construct a relatively dense crosslinked network. The rapid increase in modulus led to a significant UV-induced tack reduction effect, resulting in a decrease in peel strength after UV treatment. In Example 6, using only a trifunctional resin resulted in a relatively limited crosslinking density, leading to higher peel strength and slight residue. Notably, in Example 7, the introduction of a decafunctional resin resulted in an excessively fast crosslinking rate and a sharp increase in modulus, leading to a harder adhesive layer and a decrease in adhesion force (the bonding between the adhesive layer and the substrate). Even with lower peel strength, slight residue still occurred. In Example 8, due to the high average functionality of the crosslinking agent, the excessive cohesive force caused by moderately reducing the amount of crosslinking agent altered the adhesion failure mode and reduced the risk of gelation. The peel strength after UV treatment increased, but a certain degree of residue remained. This demonstrates that the balance between the cohesive strength of the adhesive layer and the interfacial adhesion also affects residue control.

[0082] Regarding photoinitiators, polymerizable photoinitiators containing isocyanate groups (Example 1) or carbon-carbon double bonds (Example 9) achieved a residue-free effect. However, when using small-molecule photoinitiators (Example 11), although the peel strength was not high, significant residue was observed. This is related to the fact that the photoinitiator could not anchor itself in the adhesive layer after curing, leading to interfacial migration. Furthermore, based on the data from Examples 9 and 10, it is evident that introducing a photoinitiator during the preparation of the acrylate copolymer allows the photoinitiator to be chemically bonded to the crosslinked network structure of the acrylate polymer, avoiding the problem of free residue of small-molecule initiators.

[0083] By comparing and analyzing the test results of various embodiments and comparative examples, it can be found that the residue phenomenon is mainly affected by three factors: first, the adhesion force of the adhesive layer to the substrate; second, the cohesive strength of the adhesive layer; and third, the interfacial adhesion between the adhesive layer and the object being adhered to. When the adhesive layer has good adhesion force to the substrate, and the cohesive strength of the adhesive layer is greater than the interfacial adhesion force between the adhesive layer and the object being adhered to, the tape will not leave residue. Adhesive force is sufficient to support overall peeling, which is a prerequisite for achieving clean separation; after the adhesive force meets the requirements, ensuring that the cohesive strength of the adhesive layer after UV irradiation is greater than the interfacial adhesion force becomes the key to determining whether residue exists. From the test data, all embodiments can provide high adhesive strength and pull-out strength before UV irradiation to ensure fixation, while the peel strength decreases significantly after irradiation. Multiple schemes achieved no or slight residue under different combinations of variables, while some comparative examples, either due to insufficient reduction in peel strength or insufficient cohesive strength of the adhesive layer, exhibited more serious residue problems. This indicates that by synergistically adjusting the components and maintaining a balance between adhesive strength, cohesive strength, and interfacial bonding forces, an ideal debonding effect for UV-resistant tapes can be achieved.

[0084] Table 2. Test Results

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A UV-resistant adhesive, characterized in that: The UV-resistant adhesive includes an acrylate polymer, which is obtained by polymerizing at least soft monomers, hard monomers, functional monomers, and graft monomers. The soft monomer includes at least one of isooctyl acrylate, n-butyl acrylate, isononyl acrylate, and ethyl acrylate. The hard monomer includes at least one of methyl methacrylate, isobornyl methacrylate, methyl acrylate, and vinyl acetate; The functional monomers include carboxyl-containing acrylate monomers and hydroxyl-containing acrylate monomers; The grafting monomer includes at least one of isocyanate methacrylate and isocyanate acrylate.

2. The UV-debindering adhesive according to claim 1, characterized in that The carboxyl-containing acrylate monomer includes at least one of acrylic acid and methacrylic acid, and / or the hydroxyl-containing acrylate monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

3. The UV-resistant adhesive as described in claim 1, characterized in that: The UV-resistant adhesive further includes a crosslinking agent, which comprises a high-functionality resin with a functionality of 3 to 10.

4. The UV-debindering adhesive according to claim 3, wherein The high-functionality resin includes trifunctional resin and hexafunctional resin, and the ratio of trifunctional resin to hexafunctional resin by mass is 1:2~4.

5. The UV-debindering adhesive according to claim 1, wherein The UV-resistant adhesive includes a photoinitiator, which includes at least one of carbon-carbon double bonds and isocyanate groups.

6. The UV-debindering adhesive according to claim 1, wherein The preparation of acrylate polymers includes the following steps: Step 1: The soft monomer, hard monomer, and functional monomer are each divided into two parts, and the initiator is divided into three parts. The soft monomer, hard monomer, functional monomer, initiator, and solvent of the first part are mixed and heated to 75°C~80°C under a protective gas atmosphere for 20~40 minutes. Then, the soft monomer, hard monomer, functional monomer, and initiator of the second part are added dropwise to the reaction system over a period of 2~2.5 hours. After the addition is complete, the reaction is maintained at this temperature for 3~4 hours. Then, the initiator of the third part is added to the reaction system, and the reaction is maintained at this temperature for another 1.5~2 hours to obtain the acrylate precursor. Step 2: Cool the acrylate precursor to 40℃~50℃, add a polymerization inhibitor and pass a protective gas through it to react for 20 minutes~30 minutes, then add the mixture of the grafted monomer and catalyst A dropwise, and keep it at the temperature for 4 hours~5 hours to obtain the acrylate polymer.

7. The UV-resistant adhesive as described in claim 6, characterized in that, In step two, after adding the polymerization inhibitor and passing a protective gas for 20 to 30 minutes, the photoinitiator is added and reacted for 1 to 2 hours. Then, the mixture of the grafted monomer and catalyst A is added dropwise and the reaction is maintained at a certain temperature for 4 to 5 hours to obtain the acrylate polymer.

8. A UV anti-adhesive tape, characterized in that, The UV anti-adhesion tape includes an anti-adhesion layer and a release film, wherein the anti-adhesion layer includes the UV anti-adhesion as described in any one of claims 1 to 7.

9. The UV anti-adhesion tape as described in claim 8, characterized in that, The UV anti-adhesion tape further includes a substrate layer having a first surface and a second surface opposite to each other. The anti-adhesion layer includes a first anti-adhesion layer and a second anti-adhesion layer. The first anti-adhesion layer is disposed on the first surface, and the second anti-adhesion layer is disposed on the second surface. The transmittance of the substrate layer is higher than 70%.

10. The UV anti-tack adhesive as described in any one of claims 1 to 7, or the application of the UV anti-tack tape as described in claim 8 or 9 in electronic components or electronic assemblies.

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