Acrylic UV adhesive, preparation method and application thereof, and electronic screen laminating method

Abstract

The invention belongs to the field of adhesives, and relates to an acrylic UV adhesive, a preparation method and application thereof, and an electronic screen laminating method. The acrylic UV adhesive contains epoxy acrylate resin, modified polybutadiene resin, an acrylate diluent and a photoinitiator according to a mass ratio of 100: (20-150): (20-150): (0.2-25): (0-100): (0-100), and optionally selected urethane acrylate resin and an auxiliary agent; the modified polybutadiene resin comprises a polybutadiene main chain and a polyacrylate side chain bonded to the polybutadiene main chain. According to the acrylic UV adhesive provided by the invention, the elongation at break can be improved while the elastic modulus of the acrylic UV adhesive is maintained, and the acrylic UV adhesive has the properties that the elastic modulus is more than 2GPa and the elongation at break is more than 50%, and can meet the requirements of high modulus and high elongation at break.

Description

Technical Field

[0001] The invention belongs to the field of adhesives, and particularly relates to an acrylic UV adhesive, a preparation method and application thereof, and an electronic screen laminating method. Background Art

[0002] As users pursue the ultimate aesthetic for electronic products like mobile phones, demand for larger display screens is increasing. Currently, large screens with narrow bezels have become the mainstream in electronic product development. However, as the screen-to-body ratio of full-screen displays increases, the available bonding area is increasingly squeezed, placing higher demands on adhesive performance. When the black border shrinks from 1mm to 0.4mm, the performance and process of existing adhesives are no longer able to meet this demand.

[0003] Some electronic products utilize the low-pressure injection molding (LIPO) process. LIPO is an advanced manufacturing technology used in iPhone products that helps reduce bezel size, providing a larger display area and a better visual experience. The LIPO process involves heating the molten plastic tank of the injection molding machine at a relatively low temperature. The heated molten plastic then flows under low pressure into the mold cavity. Once the molten plastic solidifies, the product can be demolded.

[0004] By connecting the black edge and the back of the electronic product screen with glue, the bonding area of ​​the screen can be widened from 0.4mm to 3mm. This is equivalent to injecting a glue middle frame on the screen to replace the original plastic, and then bonding it to the metal middle frame with foam tape.

[0005] If the LIPO process is used, each model must correspond to specific equipment and molds, and the investment in equipment and molds is high. In view of this, some electronic products use the lower-cost BNB (Bank Narrow Border) process. The BNB process is a way to expand the bonding area of ​​the screen. The BNB process uses a dam and filling method to replace molds and injection molding. Specifically, first apply two circles of non-flowing glue on the ink area of ​​the screen and the back panel to form a guide groove (moat) similar to the mold, and then fill the guide groove with highly fluid glue. After the glue solidifies, the screen is connected to the back. The BNB process can widen the bondable area of ​​the screen from 0.4mm to 3mm.

[0006] The BNB process requires existing adhesives to have the same properties as plastics, with high elastic modulus and elongation at break. Generally, the elastic modulus needs to be above 2 GPa, and the elongation at break needs to be above 50%. However, existing polyurethane acrylate-based UV adhesives have an elongation at break that meets these requirements, but their elastic modulus is generally below 1.5 GPa, which falls short. Epoxy acrylate-based UV adhesives have an elastic modulus that meets these requirements, but their elongation at break is generally below 20%, which falls short. Therefore, there is an urgent need to develop an adhesive with both high elastic modulus and elongation at break to meet the requirements of the BNB process. Furthermore, the BNB process generally requires the dam adhesive to have high thixotropy and the filler adhesive to have high fluidity. Summary of the Invention

[0007] The first object of the present invention is to provide an acrylic UV adhesive having both high elastic modulus and elongation at break.

[0008] The second object of the present invention is to provide a method for preparing the acrylic UV adhesive.

[0009] The third object of the present invention is to provide application of the above-mentioned acrylic UV adhesive in the field of consumer electronics.

[0010] A fourth object of the present invention is to provide an electronic screen lamination method.

[0011] Specifically, the acrylic UV adhesive provided by the present invention contains an epoxy acrylate resin, a modified polybutadiene resin, an acrylate diluent, a photoinitiator, and optionally a polyurethane acrylate resin and an auxiliary agent in a mass ratio of 100:(20-150):(20-150):(0.2-25):(0-100):(0-100); the modified polybutadiene resin includes a polybutadiene main chain and a polyacrylate side chain bonded to the polybutadiene main chain.

[0012] The preparation method of the acrylic UV adhesive provided by the present invention comprises the steps of uniformly mixing epoxy acrylate resin, modified polybutadiene resin, acrylate diluent, photoinitiator, and optional polyurethane acrylate resin and auxiliary agent to obtain the acrylic UV adhesive.

[0013] The electronic screen laminating method provided by the present invention uses the acrylic UV glue as the adhesive.

[0014] The key to the present invention lies in compounding an epoxy acrylate resin, an acrylate diluent, a photoinitiator, and optionally a polyurethane acrylate resin and additives to form an adhesive. A modified polybutadiene resin comprising a polybutadiene backbone and polyacrylate side chains bonded to the polybutadiene backbone is then added to the adhesive. This allows the adhesive to maintain the elastic modulus of the acrylic UV adhesive while improving its elongation at break, resulting in both an elastic modulus of 2 GPa or greater and an elongation at break of 50% or greater, meeting the requirements for both high modulus and high elongation at break. This is presumably due to the micro-incompatibility of polybutadiene with acrylate, which results in the formation of an island-in-the-sea structure during curing. This structure enhances the system's impact resistance and elongation at break.

[0015] In addition, the viscosity of the dam glue provided by the present invention can reach above 500,000 mPa·s and the thixotropy can reach above 7, the viscosity of the filling glue is below 500 mPa·s and can quickly level within 30 seconds, which can meet the requirements of electronic screen bonding using the BNB process. DETAILED DESCRIPTION

[0016] The acrylic UV adhesive provided by the present invention contains an epoxy acrylate resin, a modified polybutadiene resin, an acrylate diluent, and a photoinitiator. The mass ratio of the epoxy acrylate resin to the modified polybutadiene resin is 100:(20-150), such as 100:20, 100:30, 100:50, 100:80, 100:100, 100:120, 100:150, or any value therebetween. The mass ratio of the epoxy acrylate resin to the acrylate diluent is 100:(20-150), such as 100:20, 100:30, 100:50, 100:80, 100:100, 100:120, 100:150, or any value therebetween. The mass ratio of the epoxy acrylate resin to the photoinitiator is 100:(0.2-25), such as 100:0.2, 100:0.5, 100:1, 100:2, 100:5, 100:8, 100:10, 100:12, 100:15, 100:18, 100:20, 100:22, 100:25, or any value therebetween. Furthermore, the acrylic UV adhesive preferably also contains a polyurethane acrylate resin. In this case, the adhesive has a wide adaptability because the polar groups on the polyurethane acrylate resin molecular chain can form hydrogen bonds or van der Waals forces with the substrate surface, thereby improving the bonding performance. The mass ratio of the polyurethane acrylate resin to the epoxy acrylate resin is (0-100):100, such as 0:100, 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, 55:100, 60:100, 65:100, 70:100, 75:100, 80:100, 85:100, 90:100, 95:100, 100:100 or any value therebetween. In addition, according to actual use requirements, the acrylic UV adhesive may further contain an auxiliary agent. Specific examples of the auxiliary agent include, but are not limited to, at least one of a thixotropic agent, a leveling agent, a coupling agent, a filler, a defoaming agent, a dispersant, a stabilizer, a colorant, and a filler. The mass ratio of the auxiliary agent to the epoxy acrylate resin is (0-100):100, such as 0:100, 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, 55:100, 60:100, 65:100, 70:100, 75:100, 80:100, 85:100, 90:100, 95:100, 100:100 or any value therebetween.

[0017] In the acrylic UV adhesive provided by the present invention, the modified polybutadiene resin comprises a polybutadiene backbone and polyacrylate side chains bonded to the polybutadiene backbone. Based on the total weight of the modified polybutadiene resin, the polybutadiene backbone preferably comprises 25 to 40% by weight, and the polyacrylate side chains preferably comprise 60 to 75% by weight. Furthermore, the number average molecular weight of the modified polybutadiene resin is preferably 1,000 to 10,000, such as 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, or 10,000, or any value therebetween; and the molecular weight distribution is preferably 1 to 2.5, such as 1, 1.2, 1.5, 1.8, 2, 2.2, or 2.5, or any value therebetween.

[0018] In the acrylic UV adhesive provided herein, the modified polybutadiene resin can be commercially available or prepared using various existing methods. In a preferred embodiment, the modified polybutadiene resin is prepared by dropwise adding an acrylate monomer to a mixture containing polybutadiene and a free radical initiator to carry out a free radical polymerization reaction, thereby obtaining the modified polybutadiene resin. The molar ratio of polybutadiene to acrylate monomer is preferably 1:(1.5-3), such as 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, or any value therebetween. In this case, the resulting acrylic UV adhesive exhibits improved elastic modulus and elongation at break. The reason for this is speculated to be that the long linear flexible segments of polybutadiene can increase elongation at break without reducing the modulus of acrylic UV adhesives. However, polybutadiene has low free radical reactivity, making it difficult to cure quickly. Introducing the above-mentioned acrylate side chains into the polybutadiene backbone can enhance free radical curing activity. Controlling the amount of acrylate monomers within the above-mentioned preferred range can ensure that the modified polybutadiene resin has sufficient reactivity and can be well dissolved in the acrylic UV adhesive system, thereby maximizing the advantages of polybutadiene in increasing modulus and elongation at break. The molar ratio of the free radical initiator to polybutadiene is preferably (0.05-0.1:1), such as 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, or any value therebetween. In addition, the acrylic acid ester monomer needs to be added dropwise to the mixed solution containing polybutadiene and the free radical initiator, and the addition time is preferably controlled within 30 to 60 minutes, such as 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes or any value therebetween.

[0019] In the preparation of the modified polybutadiene resin, the number average molecular weight of the polybutadiene is preferably 1,000 to 10,000, such as 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, or any value therebetween; the molecular weight distribution is preferably 1 to 2.5, such as 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, or any value therebetween. The polybutadiene can be prepared by various existing methods or commercially available, for example, at least one of Ricon 142, Ricon 150, Ricon 157, Ricon 130, and Ricon 134 from Crayola, USA.

[0020] In the preparation process of the modified polybutadiene resin, the acrylic acid ester monomers may include at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, polyethylene glycol diacrylate, phenyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dicyclopentadienyl acrylate, alkoxylated nonylphenol acrylate, ethoxylated bisphenol A dimethacrylate, lauryl acrylate, lauryl methacrylate, 2-phenoxyethyl acrylate, isobutyl acrylate, dimethyl acrylamide and acryloylmorpholine.

[0021] In the preparation process of the modified polybutadiene resin, the free radical polymerization reaction conditions preferably include a temperature of 50° C. to 80° C., such as 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., or any value therebetween; and a reaction time of 0.5 h to 5 h, such as 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, or any value therebetween. The free radical initiator may be selected from at least one of an azo initiator, a peroxide initiator, and a redox initiator. Specific examples of the azo initiator include, but are not limited to, at least one of dimethyl azobisisobutyrate, azobisisobutyramidine hydrochloride, azodicarbonamide, azobisisopropylimidazoline hydrochloride, azoisobutylcyanamide, azobiscyclohexylcarbonitrile, azobiscyanovaleric acid, azobisisopropylimidazoline, azobisisobutyronitrile, azobisisovaleronitrile, and azobisisoheptylonitrile. Specific examples of the peroxide initiator include, but are not limited to, at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, benzoyl peroxide, and tert-butyl benzoyl peroxide. Specific examples of the redox initiator include, but are not limited to, at least one of sulfate-sulfite, persulfate-thiourea, persulfate-organic salt, and ammonium persulfate-fatty amine. The sulfate-sulfite may be selected from at least one of sodium sulfate-sodium sulfite, potassium sulfate-potassium sulfite, and ammonium sulfate-ammonium sulfite. The persulfate-thiourea can be selected from at least one of sodium persulfate-thiourea, potassium persulfate-thiourea, and ammonium persulfate-thiourea. The persulfate-organic salt can be selected from at least one of sodium persulfate-potassium acetate, potassium persulfate-potassium acetate, and ammonium persulfate-ammonium acetate. The ammonium persulfate-fatty amine can be ammonium persulfate-N,N-tetramethylethylenediamine and / or ammonium persulfate-diethylamine. The free radical polymerization reaction is typically carried out under the protection of an inert gas. The inert gas can be, for example, at least one of nitrogen, argon, helium, or the like. Furthermore, the free radical polymerization reaction can be solution polymerization, emulsion polymerization, bulk polymerization, or the like, without particular limitation, as long as the acrylic ester monomer can be bonded to the polybutadiene backbone.

[0022] In a preferred embodiment, based on the total weight of the acrylic UV adhesive, the content of the epoxy acrylate resin is 20-50wt%, such as 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt% or any value therebetween; the content of the modified polybutadiene resin is 10-30wt%, such as 10wt%, 15wt%, 20wt%, 25wt%, 30wt% or any value therebetween; the content of the acrylic ester diluent is 10-30wt%, such as 10wt%, 15wt%, 20wt%, 25wt%, 30wt% or any value therebetween. , 30wt% or any value therebetween; the content of the photoinitiator is 0.1-5wt%, such as 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or any value therebetween; the content of the polyurethane acrylate resin is 0-20wt%, such as 0, 2wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt% or any value therebetween; the content of the auxiliary agent is 0-20wt%, such as 0, 2wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt% or any value therebetween.

[0023] In a preferred embodiment, the acrylic UV glue contains a dam glue and a filling glue that are stored independently of each other; the dam glue contains 20-50wt% of epoxy acrylate resin, 10-30wt% of modified polybutadiene resin, 10-30wt% of acrylate diluent, 0.1-5wt% of photoinitiator, 0-20wt% of polyurethane acrylate resin and 5-20wt% of thixotropic agent; the filling glue contains 20-50wt% of epoxy acrylate resin, 10-30wt% of modified polybutadiene resin, 10-30wt% of acrylate diluent, 0.1-5wt% of photoinitiator, 0-20wt% of polyurethane acrylate resin and 0.1-2wt% of leveling agent.

[0024] The present invention does not particularly limit the type of epoxy acrylate resin, and can be any of various existing compounds prepared by ring-opening esterification of epoxy resin and acrylic acid, specifically unmodified epoxy acrylate resin and / or modified epoxy acrylate resin, specific examples of which include but are not limited to at least one of 2-hydroxy-3-phenoxypropyl acrylate, bisphenol A epoxy acrylate, fatty acid epoxy acrylate, novolac epoxy acrylate, epoxy soybean oil acrylate, and epoxy diacrylate. The epoxy acrylate resin can be commercially available, for example, CN104, CN110, CN136 from Sartomer of France, 624-100, 621-100, 6215-100 from Changxing Materials Industry Co., Ltd., 6100D, 6100D-75N from Jiangsu Sanmu Chemical Co., Ltd., etc., or can be prepared according to various existing methods. In addition, the viscosity of the epoxy acrylate resin at 25° C. is preferably 500 to 20,000 mPa.s, such as 500, 800, 1,000, 2,000, 5,000, 8,000, 10,000, 12,000, 15,000, 18,000, 20,000 mPa.s or any value therebetween.

[0025] In the acrylic UV adhesive provided by the present invention, the acrylic ester diluent can be listed as follows: at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, polyethylene glycol diacrylate, phenyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dicyclopentadienyl acrylate, alkoxylated nonylphenol acrylate, ethoxylated bisphenol A dimethacrylate, lauryl acrylate, lauryl methacrylate, 2-phenoxyethyl acrylate, isobutyl acrylate, dimethyl acrylamide and acryloylmorpholine.

[0026] In the acrylic UV adhesive provided by the present invention, the polyurethane acrylic resin can be any of various existing polyurethanes with acrylic groups, which can be purchased commercially or prepared using various existing methods. In a preferred embodiment, the functionality of the polyurethane acrylate resin is not less than 2, such as 2, 3, 4, 5, 6, or any integer greater than 2. The viscosity of the polyurethane acrylate resin at 25°C is preferably 2,000 to 50,000 cps, such as 2,000 cps, 5,000 cps, 8,000 cps, 10,000 cps, 12,000 cps, 15,000 cps, 20,000 cps, 25,000 cps, 30,000 cps, 35,000 cps, 40,000 cps, 45,000 cps, 50,000 cps, or any value therebetween. The polyurethane acrylate resin can be exemplified by at least one of EBECRYL 270, EBECRYL 271, EBECRYL 284, EBECRYL8307, EBECRYL 8254, and EBECRYL 8411 of Allnex Resins (China) Co., Ltd., 7210B, 7220F, 7223F, 7224, 7233F, and 7295 of Guangdong Hengzhiguang Environmental Protection New Materials Co., Ltd., and Trust 7116, Trust 7166, and Trust 7128 of Shenzhen Youyang Technology Co., Ltd.

[0027] In the acrylic UV adhesive provided by the present invention, the photoinitiator may be selected from at least one of benzophenones, alkyl benzophenones, benzil groups, and acylphosphine oxides. The benzophenones may include at least one of benzophenone, 4-methylbenzophenone, 2,4-dihydroxybenzophenone, 2,4,6-trimethylbenzophenone, benzophenone-4-trimethylammonium chloride, Michler's ketone, α,α-diethoxyacetophenone, diphenylacetophenone, and α,α-dimethoxy-α-phenylacetophenone. The alkylphenones include at least one of α-hydroxyalkylphenones (such as 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxy-cyclohexylphenone), α-aminoalkylphenones (such as 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone and 2-phenyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone), and acylphosphine oxides (such as bisbenzoylphenylphosphine oxide). The benzil includes at least one of benzil and α,α-dimethoxy-α-phenylacetophenone. The acylphosphine oxides include at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphine ester, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0028] In the acrylic UV adhesive provided by the present invention, specific examples of the auxiliary agent include, but are not limited to, at least one of a thixotropic agent, a leveling agent, a coupling agent, a filler, a defoaming agent, a dispersant, a stabilizer, a colorant, and a filler, preferably a thixotropic agent and / or a leveling agent. The thixotropic agent is preferably fumed silica, such as Waker's H8, H20, and H30, Cabot's TS-530 and TS720, and Degussa's R972, R974, R976, R202, and R8200. The leveling agent may be at least one of an organosilicon leveling agent (such as polydimethylsiloxane), an acrylate leveling agent, a fluorocarbon leveling agent, and a polyether leveling agent.

[0029] The preparation method of the acrylic UV adhesive provided by the present invention comprises uniformly mixing an epoxy acrylate resin, a modified polybutadiene resin, an acrylate diluent, a photoinitiator, and optionally a polyurethane acrylate resin and an auxiliary agent to obtain the acrylic UV adhesive. The mixing method is not particularly limited; the raw materials can be added and mixed simultaneously or in any order. In a preferred embodiment, the mixing method comprises mixing the acrylate diluent and the photoinitiator until the photoinitiator is completely dissolved, adding the modified polybutadiene resin and mixing uniformly, adding the epoxy acrylate resin and the optional polyurethane acrylate resin and mixing uniformly, then optionally adding the auxiliary agent and mixing uniformly, followed by grinding and degassing in sequence. Mixing in this preferred method does not result in stratification, and the mixing effect is better. This is because first mixing the acrylate diluent and the modified polybutadiene resin with similar polarity, and then adding the epoxy acrylate resin and the polyurethane acrylate resin with increasing polarity, can increase the polarity gradient of the system without large jumps, thereby giving the acrylic UV adhesive a higher elastic modulus and elongation at break.

[0030] The present invention also provides application of the acrylic UV adhesive in the field of consumer electronics.

[0031] In addition, the present invention also provides an electronic screen lamination method, which uses the above-mentioned acrylic UV glue as an adhesive.

[0032] In a preferred embodiment, the electronic screen lamination method is performed using a BNB process; the dam glue used in the BNB process contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin, and 5-20wt% thixotropic agent; the filling glue used in the BNB process contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin, and 0.1-2wt% leveling agent. Both the dam glue and the filling glue have an elastic modulus of 2 GPa or higher and an elongation at break of 50% or higher, meeting the requirements of high modulus and high elongation at break. Furthermore, the dam adhesive has a viscosity exceeding 500,000 mPa·s at 25°C, with a thixotropic index exceeding 7. The filler adhesive has a viscosity below 500 mPa·s at 25°C, enabling rapid leveling in less than 30 seconds. The combination of the dam adhesive and filler adhesive is ideal for laminating electronic screens using the BNB process.

[0033] The present invention will be described in detail below through examples.

[0034] Preparation Example 1 This preparation example is used to illustrate the preparation of the modified polybutadiene resin provided by the present invention.

[0035] 1 mol of polybutadiene resin (Ricon 142 from Cray Valley, USA) and 0.01 mol of benzoyl peroxide were placed in a reactor, heated to 60°C and mixed evenly. Then, 2.2 mol of methyl methacrylate was slowly added dropwise to the resulting mixture. The addition time was controlled within 60 minutes. After the addition was completed, the temperature was maintained at 60°C and stirring was continued for 60 minutes to obtain a modified polybutadiene resin with a number average molecular weight of approximately 4100 and a molecular weight distribution of 1.4.

[0036] Preparation Example 2 This preparation example is used to illustrate the preparation of the modified polybutadiene resin provided by the present invention.

[0037] 1 mol of polybutadiene resin (Ricon 134 from Cray Valley, USA) and 0.01 mol of benzoyl peroxide were placed in a reactor, heated to 80°C and mixed evenly. Then, 1.5 mol of isobornyl acrylate was slowly added dropwise to the resulting mixture. The addition time was controlled within 30 minutes. After the addition was completed, the temperature was maintained at 80°C and stirring was continued for 30 minutes to obtain a modified polybutadiene resin with a number average molecular weight of approximately 8300 and a molecular weight distribution of 1.5.

[0038] Preparation Example 3 This preparation example is used to illustrate the preparation of the modified polybutadiene resin provided by the present invention.

[0039] 1 mol of polybutadiene resin (Ricon 157 from Cray Valley, USA) and 0.01 mol of benzoyl peroxide were placed in a reactor, heated to 50°C and mixed evenly. Then, 3 mol of hydroxyethyl methacrylate was slowly added dropwise to the resulting mixture. The addition time was controlled within 50 minutes. After the addition was completed, the temperature was maintained at 50°C and stirring was continued for 5 hours to obtain a modified polybutadiene resin with a number average molecular weight of approximately 2200 and a molecular weight distribution of 1.2.

[0040] Preparation Example 4

[0041] Modified polybutadiene was prepared according to the method of Example 1, except that the amount of methyl methacrylate was adjusted to 1 mol. The other conditions were the same as those of Preparation Example 1 to obtain a modified polybutadiene resin with a number average molecular weight of about 4000 and a molecular weight distribution of 1.4.

[0042] Comparative Preparation Example 1

[0043] Modified polybutadiene was prepared according to the method of Preparation Example 1, except that methyl methacrylate was replaced by acrylonitrile in the same molar amount. The other conditions were the same as those of Preparation Example to obtain a modified polybutadiene resin with a number average molecular weight of 4000 and a molecular weight distribution of 1.4.

[0044] Example 1-1 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0045] Isobornyl acrylate and a photoinitiator (2,4-dihydroxybenzophenone) were added to a dual-planetary hybrid reactor in sequence and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 1) was then added to the dual-planetary hybrid reactor and stirred and mixed evenly. Epoxy acrylate resin (CN104 from Sartomer, France) and polyurethane acrylate resin (EBECRYL 270 from Allnex Resins (China) Co., Ltd.) were then added to the dual-planetary hybrid reactor in sequence and stirred and mixed evenly. A thixotropic agent (fumed silica, H8 from Waker) was then added to the dual-planetary hybrid reactor and stirred evenly. The mixture was then ground twice using a three-roll mill and returned to the reactor to evacuate and remove bubbles. The dam glue was then discharged and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 1.

[0046] Example 1-2 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0047] Tetrahydrofuran acrylate and photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide) were added to the dual planetary hybrid reactor in sequence and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 2) was then added to the dual planetary hybrid reactor and continued to be stirred and mixed evenly. Epoxy acrylate resin (6100D from Jiangsu Sanmu Chemical Co., Ltd.) and polyurethane acrylate resin (7210B from Guangdong Hengzhiguang Environmental Protection New Materials Co., Ltd.) were then added to the dual planetary hybrid reactor in sequence and continued to be stirred and mixed evenly. A thixotropic agent (fumed silica, Cabot's TS-530) was then added to the dual planetary hybrid reactor and stirred evenly. The mixture was then ground twice using a three-roll mill and returned to the reactor to evacuate and remove bubbles. The dam glue was obtained after discharge and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 1.

[0048] Example 1-3 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0049] Isobornyl acrylate and a photoinitiator (2,4-dihydroxybenzophenone) were sequentially added to a dual-planetary hybrid reactor and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 3) was then added to the dual-planetary hybrid reactor and continued to be stirred and mixed uniformly. Epoxy acrylate resin (624-100 from Changxing Materials Industry Co., Ltd.) and polyurethane acrylate resin (Trust 7116 from Shenzhen Youyang Technology Co., Ltd.) were then added to the dual-planetary hybrid reactor and continued to be stirred and mixed uniformly. A thixotropic agent (fumed silica, R972 from Degussa) was then added to the dual-planetary hybrid reactor and stirred uniformly. The mixture was then ground twice using a three-roll mill and returned to the reactor to evacuate and remove bubbles. The dam glue was discharged and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 1.

[0050] Example 1-4 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0051] A dam glue was prepared according to the method of Example 1-1, except that the modified polybutadiene resin (obtained in Preparation Example 1) was replaced with the same weight portion of the modified polybutadiene resin (obtained in Preparation Example 4). All other conditions were the same as in Example 1-1 to obtain a dam glue. The amounts of the raw materials used are shown in Table 1.

[0052] Examples 1-5 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0053] The dam adhesive was prepared according to the method of Example 1-1, except that the polyurethane acrylate resin was replaced with the same weight portion of epoxy acrylate resin. The remaining conditions were the same as those of Example 1-1 to obtain the dam adhesive. The amounts of the raw materials used are shown in Table 1.

[0054] Example 1-6 This example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0055] The dam glue was prepared according to the method of Example 1-1, except that the polyurethane acrylate resin was added at the same time as the modified polybutadiene. The other conditions were the same as those of Example 1-1 to obtain the dam glue. The amounts of the raw materials used are shown in Table 1.

[0056] Comparative Example 1-1 This comparative example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0057] The dam glue was prepared according to the method of Example 1-1, except that the modified polybutadiene resin was replaced with the same weight portion of epoxy acrylate resin. The remaining conditions were the same as those of Example 1-1 to obtain the dam glue. The amounts of the raw materials used are shown in Table 1.

[0058] Comparative Example 1-2 This comparative example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0059] A dam glue was prepared according to the method of Example 1-1, except that the modified polybutadiene resin was replaced with the reference modified polybutadiene resin obtained in Comparative Preparation Example 1 in equal parts by weight. The remaining conditions were the same as in Example 1-1 to obtain a dam glue. The amounts of the raw materials used are shown in Table 1.

[0060] Comparative Examples 1-3 This comparative example is used to illustrate the preparation of acrylic UV adhesive (dam adhesive)

[0061] A dam glue was prepared according to the method of Example 1-1, except that the modified polybutadiene resin was replaced with an equal weight portion of unmodified polybutadiene (Ricon 142 from Cray Valley, USA). Other conditions were the same as in Example 1-1 to obtain a dam glue. The amounts of the raw materials used are shown in Table 1.

[0062] Example 2-1 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0063] Isobornyl acrylate and a photoinitiator (2,4-dihydroxybenzophenone) were sequentially added to a dual-planetary hybrid reactor and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 1) was then added to the dual-planetary hybrid reactor and stirred and mixed uniformly. An epoxy acrylate resin (CN104 from Sartomer, France) and a polyurethane acrylate resin (EBECRYL 270 from Allnex Resins (China) Co., Ltd.) were then added to the dual-planetary hybrid reactor and stirred and mixed uniformly. A leveling agent (polydimethylsiloxane, purchased from BYK, brand BYK333) was then added to the dual-planetary hybrid reactor and stirred uniformly. The reactor was then vacuumed to remove bubbles. After discharging, the filler was obtained and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 2.

[0064] Example 2-2 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0065] Tetrahydrofuran acrylate and a photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide) were sequentially added to a dual-planetary hybrid reactor and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 2) was then added to the dual-planetary hybrid reactor and stirred and mixed uniformly. An epoxy acrylate resin (6100D from Jiangsu Sanmu Chemical Co., Ltd.) and a polyurethane acrylate resin (7210B from Guangdong Hengzhiguang Environmental Protection New Materials Co., Ltd.) were then added to the dual-planetary hybrid reactor and stirred and mixed uniformly. A leveling agent (a polyether leveling agent purchased from BYK, brand BYK371) was then added to the dual-planetary hybrid reactor and stirred uniformly. The mixture was then vacuumed to remove bubbles. After discharging, the filler was obtained and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 2.

[0066] Example 2-3 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0067] Isobornyl acrylate and a photoinitiator (2,4-dihydroxybenzophenone) were sequentially added to a dual-planetary hybrid reactor and stirred until the photoinitiator was completely dissolved. The modified polybutadiene resin (obtained in Preparation Example 3) was then added to the dual-planetary hybrid reactor and continued to be stirred and mixed uniformly. An epoxy acrylate resin (624-100 from Changxing Materials Industry Co., Ltd.) and a polyurethane acrylate resin (Trust 7116 from Shenzhen Youyang Technology Co., Ltd.) were then added to the dual-planetary hybrid reactor and continued to be stirred and mixed uniformly. A leveling agent (an acrylate leveling agent purchased from BYK, brand BYK358) was then added to the dual-planetary hybrid reactor and stirred uniformly. The mixture was then vacuumed to remove bubbles. After discharging, the filler was obtained and sealed in a light-proof packaging. The amounts of the raw materials used are shown in Table 2.

[0068] Example 2-4 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0069] A filler was prepared according to the method of Example 2-1, except that the modified polybutadiene resin (obtained in Preparation Example 1) was replaced with the same weight portion of the modified polybutadiene resin (obtained in Preparation Example 4). All other conditions were the same as in Example 2-1 to obtain a filler. The amounts of the raw materials used are shown in Table 1.

[0070] Example 2-5 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0071] A filling adhesive was prepared according to the method of Example 2-1, except that the polyurethane acrylate resin was replaced with the same weight portion of epoxy acrylate resin. The remaining conditions were the same as in Example 2-1 to obtain a filling adhesive. The amounts of the raw materials used are shown in Table 2.

[0072] Example 2-6 This example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0073] A filling compound was prepared according to the method of Example 2-1, except that the polyurethane acrylate resin was added earlier to be added simultaneously with the modified polybutadiene. Other conditions were the same as those of Example 2-1 to obtain a filling compound. The amounts of the raw materials used are shown in Table 1.

[0074] Comparative Example 2-1 This comparative example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0075] The filling compound was prepared according to the method of Example 2-1, except that the modified polybutadiene resin was replaced with the same weight portion of epoxy acrylate resin. The remaining conditions were the same as those of Example 2-1 to obtain the filling compound. The amounts of the raw materials used are shown in Table 2.

[0076] Comparative Example 2-2 This comparative example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0077] A filler was prepared according to the method of Example 1-1, except that the modified polybutadiene resin was replaced with the reference modified polybutadiene resin obtained in Comparative Preparation Example 1 in equal parts by weight. All other conditions were the same as in Example 1-1 to obtain a filler. The amounts of the raw materials used are shown in Table 2.

[0078] Comparative Example 2-3 This comparative example is used to illustrate the preparation of acrylic UV glue (filling glue)

[0079] A filling compound was prepared according to the method of Example 1-1, except that the modified polybutadiene resin was replaced with an equal weight portion of unmodified polybutadiene (Ricon 142 from Cray Valley, USA). All other conditions were the same as in Example 1-1 to obtain a filling compound. The amounts of the raw materials used are shown in Table 2.

[0080]

[0081] Test Case

[0082] (1) Viscosity

[0083] The viscosities of the dam and filler compounds obtained in the above examples and comparative examples were measured according to GB / T 2794-2022: the high-viscosity dam and filler compounds were measured at 0.1 rpm using a Brookfield plate viscometer with a 52# rotor at 25°C; the low-viscosity filler compounds were measured at 50 rpm using a Brookfield plate viscometer with a 42# rotor at 25°C. The results are shown in Table 3.

[0084] (2) Elastic modulus

[0085] The elastic modulus of the dam glue and filling glue obtained in the above examples and comparative examples was measured according to ASTM D638, using a type IV dumbbell specimen with a thickness of 0.2 mm and a tensile rate of 100 mm / min. The results are shown in Table 3.

[0086] (3) Elongation at break

[0087] The elongation at break of the dam and filling adhesives obtained in the above examples and comparative examples was measured according to ASTM D638 using a Type IV dumbbell strip with a thickness of 0.2 mm and a tensile rate of 100 mm / min. The results are shown in Table 3.

[0088] (4) Thixotropy

[0089] The thixotropy of the dam adhesives obtained in the above examples and comparative examples was measured according to GB / T 2794-2022. Viscosities at 0.1 and 1 rpm were measured using a Brookfield plate viscometer with a 52# rotor at 25°C. The thixotropy was calculated by dividing the viscosity at 0.1 rpm by the viscosity at 1 rpm. The results are shown in Table 3.

[0090] Table 3

[0091]

[0092]

[0093] The above results demonstrate that the dam glue and filler provided by the present invention meet the requirements for high modulus and high elongation at break. Furthermore, the dam glue provided by the present invention has a viscosity exceeding 500,000 mPa·s and a thixotropic index exceeding 7, while the filler has a viscosity below 500 mPa·s and rapidly leveled within 30 seconds. These characteristics meet the requirements for electronic screen lamination using the BNB process, enabling the creation of a mobile phone midframe integrated with the screen, addressing the issue of large black borders.

[0094] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. An acrylic UV adhesive, characterized in that: The acrylic UV adhesive contains epoxy acrylate resin, modified polybutadiene resin, acrylate diluent, photoinitiator and optional polyurethane acrylate resin and auxiliary agent in a mass ratio of 100:(20-150):(20-150):(0.2-25):(0-100):(0-100); the modified polybutadiene resin includes a polybutadiene main chain and a polyacrylate side chain bonded to the polybutadiene main chain.

2. The acrylic UV adhesive according to claim 1, characterized in that The modified polybutadiene resin is prepared according to the following method: an acrylate monomer is added dropwise to a mixed solution containing polybutadiene and a free radical initiator to carry out a free radical polymerization reaction, thereby obtaining the modified polybutadiene resin.

3. The acrylic UV adhesive according to claim 2, characterized in that: The molar ratio of the polybutadiene to the acrylic ester monomer is 1:(1.5-3); the molar ratio of the free radical initiator to the polybutadiene is (0.05-0.1):1; the number average molecular weight of the polybutadiene is 1,000-10,000, and the molecular weight distribution is 1-2.

5.

4. The acrylic UV adhesive according to claim 2, characterized in that: The conditions of the free radical polymerization reaction include a temperature of 50° C. to 80° C. and a time of 0.5 h to 5 h.

5. The acrylic UV adhesive according to any one of claims 1 to 4, characterized in that: Based on the total weight of the acrylic UV adhesive, the content of the epoxy acrylate resin is 20-50wt%, the content of the modified polybutadiene resin is 10-30wt%, the content of the acrylate diluent is 10-30wt%, the content of the photoinitiator is 0.1-5wt%, the content of the polyurethane acrylate resin is 0-20wt%, and the content of the auxiliary agent is 0-20wt%.

6. The acrylic UV adhesive according to any one of claims 1 to 4, characterized in that: The acrylic UV glue contains dam glue and filling glue that are stored independently of each other; the dam glue contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin and 5-20wt% thixotropic agent; the filling glue contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin and 0.1-2wt% leveling agent.

7. The method for preparing the acrylic UV adhesive according to any one of claims 1 to 6, characterized in that: The method comprises the steps of uniformly mixing epoxy acrylate resin, modified polybutadiene resin, acrylate diluent, photoinitiator, and optional polyurethane acrylate resin and auxiliary agent to obtain the acrylic UV adhesive.

8. The method for preparing acrylic UV adhesive according to claim 7, wherein: The mixing method comprises mixing an acrylate diluent and a photoinitiator until the photoinitiator is completely dissolved, adding a modified polybutadiene resin and mixing evenly, adding an epoxy acrylate resin and an optional polyurethane acrylate resin and mixing evenly, then optionally adding an auxiliary agent and mixing evenly, and then sequentially grinding and degassing.

9. Use of the acrylic UV adhesive according to any one of claims 1 to 6 in the field of consumer electronics.

10. A method for laminating an electronic screen, characterized in that: The method uses the acrylic UV adhesive described in any one of claims 1 to 6 as the adhesive.

11. The electronic screen laminating method according to claim 10, characterized in that: The electronic screen bonding method adopts the BNB process; the dam glue used in the BNB process contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin and 5-20wt% thixotropic agent; the filling glue used in the BNB process contains 20-50wt% epoxy acrylate resin, 10-30wt% modified polybutadiene resin, 10-30wt% acrylate diluent, 0.1-5wt% photoinitiator, 0-20wt% polyurethane acrylate resin and 0.1-2wt% leveling agent.

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