UV light-cured adhesive, preparation method thereof and application of UV light-cured adhesive in electronic field

Abstract

The invention discloses a UV photocuring adhesive, a preparation method thereof and an application of the UV photocuring adhesive in the electronic field, and relates to the field of adhesives. The preparation method comprises the following steps: when the UV photocuring adhesive is prepared, carrying out a reaction on dihydroxyl modified 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, p-phenylene diisocyanate, polyethylene glycol and 2-ethyl-4-methylimidazole, so as to obtain imidazole-terminated isocyanate, and carrying out a reaction on the imidazole-terminated isocyanate and the 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, so as to obtain the UV photocuring adhesive. The modified lignin, butanediamine and N, N '-methylene bisacrylamide are subjected to a reaction, and a double-bond reactant is prepared; the preparation method comprises the following steps: reacting epoxy-terminated siloxane with octamethylcyclotetrasiloxane, tetramethyltetravinyl cyclotetrasiloxane and tetramethylammonium hydroxide to obtain modified siloxane, and finally, uniformly mixing imidazole-terminated isocyanate, a double-bond reactant, modified polysiloxane and benzoin butyl ether to obtain the polyurethane adhesive. The UV light-cured adhesive prepared by the invention has good adhesive property, anti-aging property and flame retardant property.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, in particular to a UV light-curing adhesive and a preparation method thereof and application in the field of electronics. Background Art

[0002] UV curing and electron beam curing are collectively referred to as radiation curing. UV-curable materials are a general term for UV-curable coatings, inks, adhesives, and other materials. Under UV radiation, the photoinitiator in the liquid UV material is excited and converted into free radicals or cations, triggering chemical reactions between substances containing unsaturated double bonds in the material, forming a cured structure. The research and development of UV-curable materials not only enriches related disciplines such as radiation chemistry, organic chemistry, polymer chemistry, and physics, but also expands the range of products necessary for production and daily life. It also meets the specialized requirements of high-tech fields, particularly microelectronics material processing, and promotes the advancement of high-tech technologies.

[0003] Ultraviolet light-curing adhesive has the advantages of fast curing rate, low cost, less pollution, low cost and simple operation. However, single light-curing adhesive is difficult to use in colored systems and opaque materials, and the bonding effect is also poor in curing objects with complex shapes. The UV light-curing adhesive prepared by the present invention has a dual curing system, which can be cured by UV light and at high temperature. It has good anti-aging and flame retardant properties and has broad market prospects. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing UV light-curing adhesive to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A UV light-curing adhesive, wherein the UV light-curing adhesive is prepared by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and then reacting the dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with p-phenylene diisocyanate, polyethylene glycol, and 2-ethyl-4-methylimidazole to obtain imidazole-terminated isocyanate; enzymatically hydrolyzed lignin, 3-(2-aminoethyl)phenol, formaldehyde, and a concentration of 1,000 NM are reacted to obtain a UV light-curing adhesive. The invention relates to a novel polysiloxane comprising a first step of reacting 30% sodium hydroxide solution with urea to prepare modified lignin; reacting the modified lignin, diaminobutane and N,N'-methylenebisacrylamide to prepare a double bond reactant; reacting allyl glycidyl ether, an isopropanol solution of 0.2 wt% chloroplatinic acid and 1,1,3,3-tetramethyldisiloxane to prepare an epoxy-terminated siloxane; reacting the epoxy-terminated siloxane, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide to prepare a modified polysiloxane; and uniformly mixing imidazole-terminated isocyanate, a double bond reactant, the modified polysiloxane and benzoin butyl ether to prepare the polysiloxane.

[0006] A method for preparing UV light-curing adhesive comprises the following steps: (1) P-phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate were mixed and stirred at room temperature for 2.5 to 3.5 hours. A 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole with a mass concentration of 4 to 6 times that of p-phenylene diisocyanate was added dropwise. The mixture was stirred for 1.5 to 2.5 hours. The solvent was removed by rotary evaporation and dried to obtain imidazole-terminated isocyanate. (2) Mix diaminobutane, modified lignin, and N,N'-methylenebisacrylamide in a molar ratio of 1:2:5, add dimethyl sulfoxide (40-60 times the mass of diaminobutane), react at 55-65°C in the dark for 3-5 hours, cool to room temperature, pour in methyl tert-butyl ether (5-15 times the mass of dimethyl sulfoxide), and repeat 3 times. Remove the solvent by rotary evaporation to obtain a double bond reactant. (3) Octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide were mixed in a mass ratio of 1:(0.03~0.05):(0.0006~0.0008), stirred at 75~85℃ for 55~65min, added with 0.004~0.006 times the mass of octamethylcyclotetrasiloxane end-epoxy siloxane, heated to 90~110℃ and continued to stir for 2~4h, distilled under reduced pressure, heated to 135~145℃ and allowed to stand for 1~2h to obtain modified polysiloxane; (4) The imidazole-terminated isocyanate, double bond reactant, modified polysiloxane, and benzoin butyl ether are mixed in a mass ratio of 1: (1.8~2.2): (1.1~1.3): (0.002~0.004) to obtain a benzoin-containing compound.

[0007] As an optimization, the preparation method of the dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in step (1) is as follows: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone are mixed in a molar ratio of 2:1, heated and stirred at 185-195°C for 2-4 hours, cooled to 100°C, added with toluene in an amount of 4-6 times the mass of 4,4'-dihydroxybenzophenone, filtered, washed the solid with toluene 3-5 times, dissolved and recrystallized, and dried to obtain the product.

[0008] As an optimization, the mass ratio of p-phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate in step (1) is 1:(0.4~0.6):(0.5~0.7):(0.0004~0.0006).

[0009] As an optimization, the polyethylene glycol in step (1) is polyethylene glycol with a molecular weight of 400.

[0010] As an optimization, the preparation method of the modified lignin in step (2) is as follows: 9 parts by mass of enzymatically hydrolyzed lignin and 10 parts by mass of a 30% sodium hydroxide solution are mixed, ultrasonicated for 5 minutes, 9 parts by mass of 3-(2-aminoethyl)phenol and 9 parts by mass of formaldehyde are added, stirred at 80-90°C for 25-35 minutes, then 5-6 parts by mass of enzymatically hydrolyzed lignin, 4-5 parts by mass of a 30% sodium hydroxide solution, and 4-5 parts by mass of formaldehyde are added, stirring is continued for 20-30 minutes, and finally 5-6 parts by mass of enzymatically hydrolyzed lignin, 4-5 parts by mass of a 30% sodium hydroxide solution, 4-5 parts by mass of formaldehyde and 1.5-2.5 parts by mass of urea are added, stirring is continued for 10-20 minutes, and cooling is performed to room temperature to obtain the product.

[0011] As an optimization, the preparation method of the enzymatic lignin is as follows: dissolving lignin in tris (hydroxymethyl)aminomethane-hydrochloric acid buffer with a pH of 6.0, adding enzyme solution, stirring at 40-50° C. for 1-2 hours, cooling to room temperature, centrifuging and separating the precipitate, washing the precipitate with deionized water for 3-5 times, and drying to obtain the product.

[0012] As an optimization, the preparation method of the epoxy-terminated siloxane in step (3) is as follows: allyl glycidyl ether, 0.2 wt% chloroplatinic acid in isopropanol solution, and 1,1,3,3-tetramethyldisiloxane are mixed in a mass ratio of 1:(2-4):(1-1.4), reacted at 65-75°C for 1-2 hours, and the solvent was removed by rotary evaporation to obtain the obtained product.

[0013] Compared with the prior art, the present invention has the following beneficial effects: In the preparation of UV light-curing adhesive, the present invention comprises the following steps: reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with 4,4'-dihydroxybenzophenone to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; then reacting the dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with p-phenylene diisocyanate, polyethylene glycol, and 2-ethyl-4-methylimidazole to obtain imidazole-terminated isocyanate; and enzymatically degraded lignin, 3-(2-aminoethyl)phenol, formaldehyde, and 30% by mass of phenol are reacted to obtain a phenol-terminated isocyanate. Modified lignin is prepared by reacting sodium hydroxide solution and urea; modified lignin, diaminobutane and N,N'-methylenebisacrylamide are reacted to prepare a double bond reactant; allyl glycidyl ether, 0.2 wt% chloroplatinic acid isopropanol solution and 1,1,3,3-tetramethyldisiloxane are reacted to prepare epoxy-terminated siloxane; epoxy-terminated siloxane, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide are reacted to prepare modified polysiloxane; imidazole-terminated isocyanate, double bond reactant, modified polysiloxane and benzoin butyl ether are mixed to prepare a UV light-curing adhesive.

[0014] First, enzymatic lignin, 3-(2-aminoethyl)phenol, formaldehyde, 30% mass concentration sodium hydroxide solution, and urea were reacted to prepare modified lignin; the modified lignin, diaminobutane, and N,N'-methylenebisacrylamide were reacted to prepare double bond reactants, which introduced rich lignin structures into the UV curing adhesive system. The phenolic hydroxyl structures on the lignin can chemically react with the active groups on the surface of the adhered material to form chemical bonds, thereby enhancing the adhesion between the adhesive and the adhered material, thereby improving the bonding performance of the UV light curing adhesive; and the lignin introduced a large amount of polyphenol structures into the UV curing agent. The polyphenol structures have good anti-aging properties, thereby effectively improving the anti-aging properties of the UV curing adhesive.

[0015] Secondly, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone are reacted to prepare dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which is then reacted with p-phenylene diisocyanate, polyethylene glycol, and 2-ethyl-4-methylimidazole to prepare imidazole-terminated isocyanate. DOPO, a phosphorus-containing flame retardant compound with excellent flame retardant properties, is introduced into the UV-curing adhesive. DOPO can promote carbonization when the UV-curing adhesive burns, forming a dense carbon layer on the surface, preventing the escape of combustible gases and isolating oxygen, thereby effectively improving the flame retardant properties of the UV-curing adhesive.

[0016] Finally, modified polysiloxane was prepared by reacting terminal epoxy siloxane, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide. A rich double bond structure was introduced into the modified polysiloxane, which underwent chemical cross-linking with the rich double bond structure on the double bond reactant under the irradiation of initiator and ultraviolet light to form a complex cross-linking network, effectively improving the bonding performance of UV-curing adhesive. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0018] A method for preparing UV light-curing adhesive comprises the following steps: (1) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone were mixed in a molar ratio of 2:1, heated and stirred at 185°C for 2 h, cooled to 100°C, added with toluene 4 times the mass of 4,4'-dihydroxybenzophenone, filtered, washed with toluene 3 times, dissolved and recrystallized, and dried to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; Phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate were mixed in a mass ratio of 1:0.4:0.5:0.0004, stirred at room temperature for 2.5 hours, and a 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole (4 times the mass of phenylene diisocyanate) was added dropwise. The mixture was stirred for 1.5 hours, and the solvent was removed by rotary evaporation. The mixture was dried to obtain imidazole-terminated isocyanate. (2) 9 parts by mass of enzymatically hydrolyzed lignin and 10 parts by mass of 30% sodium hydroxide solution were mixed, ultrasonicated for 5 minutes, 9 parts by mass of 3-(2-aminoethyl)phenol and 9 parts by mass of formaldehyde were added, stirred at 80°C for 25 minutes, and then 5 parts by mass of enzymatically hydrolyzed lignin, 4 parts by mass of 30% sodium hydroxide solution, and 4 parts by mass of formaldehyde were added, and stirring was continued for 20 minutes. Finally, 5 parts by mass of enzymatically hydrolyzed lignin, 4 parts by mass of 30% sodium hydroxide solution, 4 parts by mass of formaldehyde and 1.5 parts by mass of urea were added, and stirring was continued for 10 minutes. The mixture was cooled to room temperature to obtain modified lignin. (3) Mix diaminobutane, modified lignin, and N,N'-methylenebisacrylamide in a molar ratio of 1:2:5, add dimethyl sulfoxide (40 times the mass of diaminobutane), react at 55°C in the dark for 3 h, cool to room temperature, pour in methyl tert-butyl ether (5 times the mass of dimethyl sulfoxide), and repeat 3 times. Remove the solvent by rotary evaporation to obtain a double bond reactant. (4) Allyl glycidyl ether, 0.2 wt% chloroplatinic acid in isopropanol solution, and 1,1,3,3-tetramethyldisiloxane were mixed in a mass ratio of 1:2:1, reacted at 65 ° C for 1 hour, and the solvent was removed by rotary evaporation to obtain terminal epoxy siloxane; octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and tetramethylammonium hydroxide were mixed in a mass ratio of 1:0.03:0.0006, stirred at 75 ° C for 55 minutes, and terminal epoxy siloxane (0.004 times the mass of octamethylcyclotetrasiloxane) was added, the temperature was raised to 90 ° C and the stirring was continued for 2 hours, and the mixture was distilled under reduced pressure, and the temperature was raised to 135 ° C and allowed to stand for 1 hour to obtain modified polysiloxane; (5) The imidazole-terminated isocyanate, double bond reactant, modified polysiloxane, and benzoin butyl ether were mixed in a mass ratio of 1:1.8:1.1:0.002 to obtain a product. Example

[0019] A method for preparing UV light-curing adhesive comprises the following steps: (1) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone were mixed in a molar ratio of 2:1, heated and stirred at 190°C for 3 h, cooled to 100°C, added with toluene 5 times the mass of 4,4'-dihydroxybenzophenone, filtered, and the solid was washed with toluene 4 times, dissolved and recrystallized, and dried to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; P-phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate were mixed in a mass ratio of 1:0.5:0.6:0.0005, stirred at room temperature for 3 hours, and a 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole (5 times the mass of p-phenylene diisocyanate) was added dropwise. The mixture was stirred for 2 hours, and the solvent was removed by rotary evaporation. The mixture was dried to obtain imidazole-terminated isocyanate. (2) 9 parts by mass of enzymatically hydrolyzed lignin and 10 parts by mass of 30% sodium hydroxide solution were mixed, ultrasonicated for 5 minutes, 9 parts by mass of 3-(2-aminoethyl)phenol and 9 parts by mass of formaldehyde were added, stirred at 85°C for 30 minutes, and then 5.5 parts by mass of enzymatically hydrolyzed lignin, 4.5 parts by mass of 30% sodium hydroxide solution and 4.5 parts by mass of formaldehyde were added, and stirring was continued for 25 minutes. Finally, 5.5 parts by mass of enzymatically hydrolyzed lignin, 45 parts by mass of 30% sodium hydroxide solution, 4.5 parts by mass of formaldehyde and 2 parts by mass of urea were added, and stirring was continued for 15 minutes. The mixture was cooled to room temperature to obtain modified lignin. (3) Mix diaminobutane, modified lignin, and N,N'-methylenebisacrylamide in a molar ratio of 1:2:5, add dimethyl sulfoxide (50 times the mass of diaminobutane), react at 60°C in the dark for 4 hours, cool to room temperature, pour in methyl tert-butyl ether (10 times the mass of dimethyl sulfoxide), and repeat 3 times. Remove the solvent by rotary evaporation to obtain a double bond reactant. (4) Allyl glycidyl ether, 0.2 wt% isopropanol solution of chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane were mixed in a mass ratio of 1:3:1.2, reacted at 70 ° C for 1.5 hours, and the solvent was removed by rotary evaporation to obtain terminal epoxy siloxane; octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and tetramethylammonium hydroxide were mixed in a mass ratio of 1:0.04:0.0007, stirred at 80 ° C for 60 minutes, and 0.005 times the mass of octamethylcyclotetrasiloxane terminal epoxy siloxane was added, the temperature was raised to 100 ° C and the stirring was continued for 3 hours, and the mixture was distilled under reduced pressure, and the temperature was raised to 140 ° C and allowed to stand for 1.5 hours to obtain modified polysiloxane; (5) The imidazole-terminated isocyanate, double bond reactant, modified polysiloxane, and benzoin butyl ether were mixed in a mass ratio of 1:2:1.2:0.003 to obtain a product. Example

[0020] A method for preparing UV light-curing adhesive comprises the following steps: (1) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone were mixed in a molar ratio of 2:1, heated and stirred at 195 °C for 4 h, cooled to 100 °C, added with toluene 6 times the mass of 4,4'-dihydroxybenzophenone, filtered, washed with toluene 5 times, dissolved and recrystallized, and dried to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; Phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate were mixed in a mass ratio of 1:0.6:0.7:0.0006, stirred at room temperature for 3.5 hours, and a 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole (6 times the mass of phenylene diisocyanate) was added dropwise. The mixture was stirred for 2.5 hours, and the solvent was removed by rotary evaporation. The mixture was dried to obtain imidazole-terminated isocyanate. (2) 9 parts by mass of enzymatically hydrolyzed lignin and 10 parts by mass of 30% sodium hydroxide solution were mixed, ultrasonicated for 5 minutes, 9 parts by mass of 3-(2-aminoethyl)phenol and 9 parts by mass of formaldehyde were added, stirred at 90°C for 35 minutes, and then 6 parts by mass of enzymatically hydrolyzed lignin, 5 parts by mass of 30% sodium hydroxide solution, and 5 parts by mass of formaldehyde were added, and stirring was continued for 30 minutes. Finally, 6 parts by mass of enzymatically hydrolyzed lignin, 5 parts by mass of 30% sodium hydroxide solution, 5 parts by mass of formaldehyde and 2.5 parts by mass of urea were added, and stirring was continued for 20 minutes. The mixture was cooled to room temperature to obtain modified lignin; (3) Mix dimethylbenzene, modified lignin, and N,N'-methylenebisacrylamide in a molar ratio of 1:2:5, add dimethyl sulfoxide (60 times the mass of dimethylbenzene), react at 65°C in the dark for 5 hours, cool to room temperature, pour in methyl tert-butyl ether (15 times the mass of dimethyl sulfoxide), and repeat 3 times. Remove the solvent by rotary evaporation to obtain a double bond reactant. (4) Allyl glycidyl ether, 0.2 wt% isopropanol solution of chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane were mixed in a mass ratio of 1:4:1.4, reacted at 75 ° C for 2 h, and the solvent was removed by rotary evaporation to obtain terminal epoxy siloxane; octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and tetramethylammonium hydroxide were mixed in a mass ratio of 1:0.05:0.0008, stirred at 85 ° C for 65 min, and terminal epoxy siloxane (0.006 times the mass of octamethylcyclotetrasiloxane) was added, the temperature was raised to 110 ° C and the stirring was continued for 4 h, and the mixture was distilled under reduced pressure, and the temperature was raised to 145 ° C and allowed to stand for 2 h to obtain modified polysiloxane; (5) The imidazole-terminated isocyanate, double bond reactant, modified polysiloxane, and benzoin butyl ether were mixed in a mass ratio of 1:2.2:1.3:0.004 to obtain a product.

[0021] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that step (2) is omitted, and step (3) is modified as follows: dimethyl sulfoxide (DMSO) in a molar ratio of 1:2:5 is added to dimethyl sulfoxide (DMSO) at a mass of 50 times that of dimethyl sulfoxide, and the mixture is stirred at 60°C in the dark for 4 h. The mixture is cooled to room temperature, and methyl tert-butyl ether (DMSO) in a mass of 10 times that of dimethyl sulfoxide is added to the mixture to allow the mixture to settle. The reaction is repeated three times, and the solvent is removed by rotary evaporation to obtain a double bond reactant. The remaining steps are the same as those in Example 2.

[0022] Comparative Example 2: The difference between Comparative Example 2 and Example 2 lies in step (1). Step (1) is modified as follows: p-phenylene diisocyanate, polyethylene glycol, and dibutyltin dilaurate are mixed in a mass ratio of 1:1:0.6:0.0005, stirred at room temperature for 3 h, and a 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole (5 times the mass of p-phenylene diisocyanate) is added dropwise. Stirring is continued for 2 h, the solvent is removed by rotary evaporation, and the mixture is dried to obtain imidazole-terminated isocyanate. The remaining steps are the same as those in Example 2.

[0023] Comparative Example 3: The difference between Comparative Example 3 and Example 2 lies in the difference in step (4). Step (4) is modified as follows: allyl glycidyl ether, 0.2wt% isopropanol solution of chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane are mixed in a mass ratio of 1:3:1.2, reacted at 70°C for 1.5h, and the solvent is removed by rotary evaporation to obtain terminal epoxy siloxane; octamethylcyclotetrasiloxane and tetramethylammonium hydroxide are mixed in a mass ratio of 1:0.0007, stirred at 80°C for 60min, and terminal epoxy siloxane with a mass of 0.005 times that of octamethylcyclotetrasiloxane is added, the temperature is raised to 100°C and the stirring is continued for 3h, the mixture is distilled under reduced pressure, the temperature is raised to 140°C and the mixture is allowed to stand for 1.5h to obtain modified polysiloxane; Test Example 1: Curing method: The UV light curing adhesive obtained in each embodiment and comparative example was poured into a mold, irradiated with ultraviolet light of a wavelength of 405 nm for 5 minutes and heated at 110° C. for curing.

[0024] Adhesion Performance Testing: A German Zwick-Roell universal testing machine (model Z010) was used to test the bond strength of UV-curing adhesive to metal. The metal sheet was surface treated according to GB / T 21526-2008, and the testing process was conducted according to GB / T 7124-2008. The metal sheet used for testing measured 100 × 25 × 2 mm, with a bonding surface length of 12.5 ± 2.5 mm. The bond strength was measured at a tensile rate of 5 mm / min. The results are shown in Table 1.

[0025] Aging resistance test: Metal sheets were bonded using the same method as in the bonding test. The bonded metal sheets were placed in a simulated aging test chamber at 80°C and 75% humidity. After two days, the bond strength was measured and the bond strength retention rate was calculated. The results are shown in Table 1.

[0026] Flame retardant performance test: Samples of the UV curable adhesives obtained in the embodiments and test examples were prepared according to GB / T2406 and tested for limiting oxygen index. The results are shown in Table 1.

[0027] Table 1 From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the UV light-curing adhesive prepared by the present invention has good bonding performance, anti-aging performance and flame retardant performance.

[0028] The difference between Comparative Example 1 and Example 2 is that no lignin is added. By comparison, the bonding strength of Examples 1 to 3 is greater than that of Comparative Example 1, indicating that the modified lignin prepared by reacting enzymatic lignin, 3-(2-aminoethyl)phenol, formaldehyde, 30% sodium hydroxide solution, and urea; and the double bond reactant prepared by reacting the modified lignin, diamine, and N,N'-methylenebisacrylamide introduces a rich lignin structure into the UV curing adhesive system. The phenolic hydroxyl structure on the lignin can chemically react with the active groups on the surface of the adhered material to form a chemical bond, thereby enhancing the adhesion between the adhesive and the adhered material, thereby improving the bonding performance of the UV light curing adhesive; by comparison, the bonding strength retention rate of Examples 1 to 3 is greater than that of Comparative Example 1, indicating that the lignin introduces a large amount of polyphenol structure into the UV curing agent, and the polyphenol structure has good anti-aging properties, thereby effectively improving the anti-aging properties of the UV curing adhesive.

[0029] The difference between Comparative Example 2 and Example 2 is that no dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added. By comparison, the limiting oxygen index of Examples 1 to 3 is greater than the limiting oxygen index of Comparative Example 2, indicating that dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is prepared by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone, and then dihydroxy-modified 9,1 Imidazole-terminated isocyanate is prepared by reacting 0-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with p-phenylene diisocyanate, polyethylene glycol, and 2-ethyl-4-methylimidazole. DOPO, a phosphorus-containing flame retardant compound with excellent flame retardancy, is introduced into the UV-curing adhesive. DOPO promotes charring during combustion of the UV-curing adhesive, forming a dense carbon layer on the surface that prevents the escape of combustible gases and isolates oxygen, effectively improving the flame retardancy of the UV-curing adhesive.

[0030] The difference between Comparative Example 3 and Example 2 is that tetramethyltetravinylcyclotetrasiloxane is not added. By comparison, the bonding strength of Examples 1 to 3 is greater than the bonding strength of Comparative Example 3, indicating that the modified polysiloxane is prepared by reacting terminal epoxy siloxane, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide, and a rich double bond structure is introduced into the modified polysiloxane. The rich double bond structure on the double bond reactant undergoes chemical crosslinking under the initiator and ultraviolet light irradiation to form a complex crosslinking network, which effectively improves the bonding performance of the UV curing adhesive.

[0031] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A UV light curing adhesive, characterized in that: The UV light curing adhesive is prepared by mixing imidazole-terminated isocyanate, double bond reactant, modified polysiloxane and benzoin butyl ether; The imidazole-terminated isocyanate is prepared by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone to obtain dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and then reacting the dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with p-phenylene diisocyanate, polyethylene glycol, and 2-ethyl-4-methylimidazole. The double bond reactant is prepared by reacting enzymatic lignin, 3-(2-aminoethyl)phenol, formaldehyde, 30% sodium hydroxide solution, and urea to obtain modified lignin; and reacting the modified lignin, diaminobutane, and N,N'-methylenebisacrylamide to obtain the double bond reactant. The modified polysiloxane is prepared by reacting allyl glycidyl ether, an isopropanol solution of 0.2 wt% chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane to obtain an epoxy-terminated siloxane; and reacting the epoxy-terminated siloxane, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and tetramethylammonium hydroxide to obtain the modified polysiloxane.

2. A method for preparing UV light-curing adhesive, characterized in that: The method comprises the following preparation steps: (1) P-phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate were mixed and stirred at room temperature for 2.5 to 3.5 hours. A 5% tetrahydrofuran solution of 2-ethyl-4-methylimidazole with a mass concentration of 4 to 6 times that of p-phenylene diisocyanate was added dropwise. The mixture was stirred for 1.5 to 2.5 hours. The solvent was removed by rotary evaporation and dried to obtain imidazole-terminated isocyanate. (2) Mix diaminobutane, modified lignin, and N,N'-methylenebisacrylamide in a molar ratio of 1:2:5, add dimethyl sulfoxide (40-60 times the mass of diaminobutane), react at 55-65°C in the dark for 3-5 hours, cool to room temperature, pour in methyl tert-butyl ether (5-15 times the mass of dimethyl sulfoxide), and repeat 3 times. Remove the solvent by rotary evaporation to obtain a double bond reactant. (3) Octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide were mixed in a mass ratio of 1:(0.03~0.05):(0.0006~0.0008), stirred at 75~85℃ for 55~65min, added with 0.004~0.006 times the mass of octamethylcyclotetrasiloxane end-epoxy siloxane, heated to 90~110℃ and continued to stir for 2~4h, distilled under reduced pressure, heated to 135~145℃ and allowed to stand for 1~2h to obtain modified polysiloxane; (4) The imidazole-terminated isocyanate, double bond reactant, modified polysiloxane, and benzoin butyl ether are mixed in a mass ratio of 1: (1.8~2.2): (1.1~1.3): (0.002~0.004) to obtain a benzoin-containing compound.

3. The method for preparing a UV light-curing adhesive according to claim 2, characterized in that: The preparation method of the dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in step (1) is as follows: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 4,4'-dihydroxybenzophenone are mixed in a molar ratio of 2:1, heated and stirred at 185-195°C for 2-4 hours, cooled to 100°C, added with toluene in an amount of 4-6 times the mass of 4,4'-dihydroxybenzophenone, filtered, washed the solid with toluene 3-5 times, dissolved and recrystallized, and dried to obtain the product.

4. The method for preparing a UV light-curing adhesive according to claim 2, wherein: The mass ratio of p-phenylene diisocyanate, polyethylene glycol, dihydroxy-modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dibutyltin dilaurate in step (1) is 1:(0.4-0.6):(0.5-0.7):(0.0004-0.0006).

5. The method for preparing a UV light-curing adhesive according to claim 2, characterized in that: The polyethylene glycol in step (1) is polyethylene glycol with a molecular weight of 400.

6. The method for preparing a UV light-curing adhesive according to claim 2, characterized in that: The preparation method of the modified lignin in step (2) is as follows: 9 parts by mass of enzymatically hydrolyzed lignin and 10 parts by mass of a 30% sodium hydroxide solution are mixed, ultrasonicated for 5 minutes, 9 parts by mass of 3-(2-aminoethyl)phenol and 9 parts by mass of formaldehyde are added, stirred at 80-90°C for 25-35 minutes, then 5-6 parts by mass of enzymatically hydrolyzed lignin, 4-5 parts by mass of a 30% sodium hydroxide solution, and 4-5 parts by mass of formaldehyde are added, stirring is continued for 20-30 minutes, and finally 5-6 parts by mass of enzymatically hydrolyzed lignin, 4-5 parts by mass of a 30% sodium hydroxide solution, 4-5 parts by mass of formaldehyde and 1.5-2.5 parts by mass of urea are added, stirring is continued for 10-20 minutes, and cooling to room temperature is obtained.

7. The method for preparing a UV light-curing adhesive according to claim 6, characterized in that: The preparation method of the enzymatically hydrolyzed lignin comprises the following steps: dissolving lignin in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 6.0, adding an enzyme solution, stirring at 40-50° C. for 1-2 hours, cooling to room temperature, centrifuging and separating the precipitate, washing the precipitate with deionized water for 3-5 times, and drying to obtain the product.

8. The method for preparing a UV light-curing adhesive according to claim 2, characterized in that: The preparation method of the epoxy-terminated siloxane in step (3) is as follows: allyl glycidyl ether, 0.2 wt% chloroplatinic acid in isopropanol solution, and 1,1,3,3-tetramethyldisiloxane are mixed in a mass ratio of 1:(2-4):(1-1.4), reacted at 65-75° C. for 1-2 h, and the solvent is removed by rotary evaporation to obtain the obtained product.

9. Use of the UV light-curing adhesive prepared by the method for preparing a UV light-curing adhesive according to any one of claims 2 to 8 in the field of electronics.