Ultraviolet curing adhesive for temporary protection of screw hole of metal shell of notebook computer

Abstract

Belonging to the technical field of adhesives, the invention relates to an ultraviolet curing adhesive for temporary protection of laptop metal shell screw holes, which comprises, by weight, 20-40 parts of a crosslinking prepolymer, 20-40 parts of an alkenylation prepolymer, 30-35 parts of a reactive diluent, 1-1.5 parts of a silane coupling agent, 4-5 parts of a photoinitiator, 4-5 parts of fumed silica, the preparation method comprises the following steps: reacting oxalyl chloride with excessive 1-thioglycerol to form a hydroxyl-terminated low-molecular-weight ester, namely a modifier, pre-polymerizing the modifier with HMDI (hexamethylenediphenyl diisocyanate), and terminating with hydroxyethyl acrylate to form a prepolymer with active sulfydryl on a side chain; the alkenyl prepolymer is pre-polymerized by hydroxyl-terminated polybutadiene and HMDI (hexamethylenediphenyl diisocyanate), and is terminated by hydroxyethyl acrylate to form a prepolymer with unsaturated double bonds on a side chain; the prepared ultraviolet curing adhesive is shorter in veneer working time, higher in yield and suitable for high-efficiency assembly line work.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to an ultraviolet curing adhesive for temporarily protecting screw holes of a metal shell of a notebook. Background Art

[0002] With the development of science and technology, laptops are accompanying us in our daily life. Among them, the shell used to build the laptop keyboard is mostly made of aluminum alloy, which is made of aluminum alloy sheet through CNC finishing. Since there are impurities and burrs on the surface of the finished product after CNC processing, sandblasting, grinding, pickling, anodizing and other operations are required. Such a production process will cause the planned screw holes on the frame to wear or become larger as a whole, which will affect the later assembly and cannot be fixed intact. Therefore, it is necessary to fill the screw holes to facilitate pickling and other process operations to protect the screw holes from wear and other chemicals during the operation. After the operation is completed, the filler in the screw hole is removed. The traditional process is to use silicone plugs to plug the screw holes, but because the use of rubber plugs must be manually operated individually, there are more than 20-100 large and small holes on a notebook shell. The operation takes too long and cannot form a streamlined operation. In addition, the rubber plug is easy to fall off during the sandblasting process, resulting in the inability to protect the screw holes and produce defective products. The development of new UV curing adhesives that can meet simple and fast operation has become an urgent need in the market. Summary of the invention

[0003] In order to solve the technical problem mentioned in the background technology, the purpose of the present invention is to provide a UV curing adhesive for temporary protection of screw holes of a notebook metal shell.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A UV curing adhesive for temporary protection of screw holes of a notebook metal shell comprises, by weight, 20-40 parts of a cross-linked prepolymer, 20-40 parts of an olefinic prepolymer, 30-35 parts of an active diluent, 1-1.5 parts of a silane coupling agent, 4-5 parts of a photoinitiator and 4-5 parts of fumed silica.

[0005] The cross-linked prepolymer is prepared by the following method: Step A1: 1-thioglycerol, triethylamine and acetone are mixed, and dry nitrogen is introduced for protection. The temperature is controlled at 5-15° C. in an ice-water bath, and stirring is applied at 120-180 rpm. Oxalyl chloride is slowly added to react for 1-1.5 hours. After the reaction is completed, acetone is removed by vacuum drying. The liquid is washed with water, the aqueous phase is removed, and the water is removed by vacuum drying to obtain a modified monomer; Furthermore, the dosage ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1 mol: 0.12-0.14 mol: 4-6 mL: 25-35 mL, triethylamine is an acid binding agent, and under low temperature environment, oxalyl chloride reacts with excess 1-thioglycerol to form a hydroxyl-terminated low molecular weight ester.

[0006] Step A2: HMDI and modified monomer are mixed and preheated to 45-55°C, 10 ppm of catalyst is added, the mixture is heated to 75-80°C and reacted for 2-3 hours, hydroxyethyl acrylate is added and 10 ppm of catalyst is added, the temperature is controlled to 70-75°C and reacted for 2-3 hours, 50 ppm of polymerization inhibitor is added and the reaction is continued for 1-2 hours, and the reaction is completed and the temperature is lowered to 50°C and discharged to obtain a cross-linked prepolymer; Furthermore, the molar ratio of the hydroxyl content of the modified monomer, hydroxyethyl acrylate and HMDI is 2:2:2.2-2.3.

[0007] The preparation method of the olefination prepolymer is as follows: HMDI and terminal hydroxyl polybutadiene are mixed and preheated to 45-55° C., 10 ppm of catalyst is added and mixed, the temperature is raised to 75-80° C. for reaction for 2-3 hours, hydroxyethyl acrylate is added and 10 ppm of catalyst is added, the temperature is controlled to 70-75° C. for reaction for 2-3 hours, 50 ppm of polymerization inhibitor is added and the reaction is continued for 1-2 hours, and the temperature is lowered to 50° C. for discharge after the reaction is completed to obtain the olefination prepolymer; Furthermore, the molar ratio of the hydroxyl content of the hydroxyl-terminated polybutadiene, hydroxyethyl acrylate and HMDI is 2:2:2.1-2.25, and the number average molecular weight of the hydroxyl-terminated polybutadiene is 1000-3000.

[0008] Preferably, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol.

[0009] Further, the active diluent is one or more of ethoxyethoxyethyl acrylate, tetrahydrofuran acrylate, 2-phenoxyethyl acrylate, lauric acid acrylate, lauryl methacrylate and isodecyl acrylate.

[0010] Furthermore, the silane coupling agent is one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

[0011] Furthermore, the photoinitiator is one or more of photoinitiator 184 , photoinitiator MBF, photoinitiator 1173 , photoinitiator TPO and photoinitiator 819 .

[0012] Beneficial effects of the present invention: The invention is based on the traditional acrylate modified polyurethane prepolymer technology, and independently develops a cross-linked prepolymer and an olefinic prepolymer as the matrix of the ultraviolet curing adhesive, wherein the cross-linked prepolymer is formed by the reaction of oxalyl chloride and excess 1-thioglycerol to form a hydroxyl-terminated low molecular weight ester, i.e., a modifier, and then prepolymerized with HMDI, and then terminated by hydroxyethyl acrylate to form a prepolymer with an active thiol group on the side chain; the olefinic prepolymer is prepolymerized by terminal hydroxyl polybutadiene and HMDI, and then terminated by hydroxyethyl acrylate to form a prepolymer with an unsaturated double bond on the side chain; the ultraviolet curing adhesive is prepared by using the two as the matrix, and in the curing process, the terminal acrylate structure triggers cross-linking to form a long chain, and the thiol group of the side chain clicks and adds with the double bond to form micro cross-linking between chains, thereby improving the curing efficiency of the adhesive liquid, and having lower single board working hours when applied in the assembly line operation, and at the same time, the cured adhesive block has moderate toughness, and plays a good protective role on the screw holes. DETAILED DESCRIPTION

[0013] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0014] Example 1: This embodiment prepares UV curing adhesive, and the specific implementation process is as follows: (1) Preparation of cross-linked prepolymer Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 15°C in an ice-water bath, stirring is applied at 180rpm, oxalyl chloride is slowly added, and the addition time is controlled to be 30min. After complete addition, constant temperature stirring is continued for reaction, and the total reaction time of oxalyl chloride is controlled to be 1h, wherein the amount ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1mol:0.14mol:6mL:35mL. After the reaction is completed, acetone is removed by vacuum drying, the liquid is washed with water, the aqueous phase is removed, and water is removed by vacuum drying to obtain a modified monomer.

[0015] Step A2: Take HMDI and the modified monomer, mix them and pre-heat them to 55°C, add 10 ppm of catalyst and mix, heat them to 80°C and react for 2 hours, then add hydroxyethyl acrylate and add 10 ppm of catalyst, control the temperature to 75°C and react for 2 hours, then add 50 ppm of inhibitor and continue to react for 1 hour, wherein HMDI is 4,4-diisocyanate dicyclohexylmethane, the hydroxyl content of the modified monomer, the molar ratio of hydroxyethyl acrylate and HMDI is 2:2:2.3, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain a cross-linked prepolymer.

[0016] (2) Preparation of olefin prepolymer Take HMDI and terminal hydroxyl polybutadiene (number average molecular weight of 3000), mix and preheat to 55°C, add 10ppm catalyst and mix, heat to 80°C and react for 2h, then add hydroxyethyl acrylate and 10ppm catalyst, control the temperature to 75°C and react for 2h, then add 50ppm inhibitor and continue to react for 1h, wherein the hydroxyl content of terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI have a molar ratio of 2:2:2.25, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C to obtain an olefin prepolymer.

[0017] (3) Preparation of UV curing adhesive Ingredients: The raw materials are measured by weight: 40 parts of cross-linked prepolymer, which is homemade in this embodiment; 20 parts of olefinated prepolymer, which is homemade in this embodiment; 30 parts of reactive diluent, which is a mixture of 15 parts of isodecyl acrylate and 15 parts of tetrahydrofuran acrylate; 1 part of silane coupling agent, which is selected from vinyltrimethoxysilane; 4 parts of photoinitiator, which is a mixture of 2.5 parts of photoinitiator 184 and 1.5 parts of photoinitiator 819; 4 parts of fumed silica, which is selected from AEROSIL 380 type raw material.

[0018] Glue preparation: Mix the cross-linked prepolymer, olefinic prepolymer, active diluent and silane coupling agent, stir at 800 rpm for 1 hour, then add the photoinitiator in a light-proof environment, stir at a vacuum degree of -0.08 MPa and 1200 rpm for 1 hour, then add fumed silica and continue stirring for 1 hour to obtain a UV-curing adhesive.

[0019] Example 2: This embodiment prepares UV curing adhesive, and the specific implementation process is as follows: (1) Preparation of cross-linked prepolymer Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 5°C in an ice-water bath, stirring is applied at 120rpm, oxalyl chloride is slowly added, and the addition time is controlled to be 50min. After complete addition, constant temperature stirring is continued for reaction, and the total reaction time of oxalyl chloride is controlled to be 1.5h, wherein the amount ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1mol:0.12mol:4mL:25mL. After the reaction is completed, acetone is removed by vacuum drying, the liquid is washed with water, the aqueous phase is removed, and water is removed by vacuum drying to obtain a modified monomer.

[0020] Step A2: Take HMDI and the modified monomer, mix them and pre-heat them to 45°C, add 10 ppm of catalyst and mix them, heat them to 75°C and react for 3 hours, then add hydroxyethyl acrylate and add 10 ppm of catalyst, control the temperature to 70°C and react for 3 hours, then add 50 ppm of inhibitor and continue to react for 2 hours, wherein HMDI is 4,4-diisocyanate dicyclohexylmethane, the hydroxyl content of the modified monomer, the molar ratio of hydroxyethyl acrylate and HMDI is 2:2:2.2, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain a cross-linked prepolymer.

[0021] (2) Preparation of olefin prepolymer Take HMDI and terminal hydroxyl polybutadiene (number average molecular weight of 1000), mix and preheat to 45°C, add 10ppm catalyst and mix, heat to 75°C and react for 3h, then add hydroxyethyl acrylate and 10ppm catalyst, control the temperature to 70°C and react for 3h, then add 50ppm inhibitor and continue to react for 2h, wherein the hydroxyl content of terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI have a molar ratio of 2:2:2.1, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C to obtain an olefin prepolymer.

[0022] (3) Preparation of UV curing adhesive Ingredients: raw materials are taken according to weight parts, 40 parts of cross-linked prepolymer, which is homemade in this embodiment; 20 parts of olefination prepolymer, which is homemade in this embodiment; 30 parts of active diluent, which is a mixture of 15 parts of 2-phenoxyethyl acrylate and 15 parts of lauric acid acrylate; 1 part of silane coupling agent, which is selected from γ-(2,3-epoxypropoxy)propyltrimethoxysilane; 4 parts of photoinitiator, which is a mixture of 2.5 parts of photoinitiator 1173 and 1.5 parts of photoinitiator TPO; 4 parts of fumed silica, which is selected from AEROSIL 380 type raw material.

[0023] Glue preparation: Mix the cross-linked prepolymer, olefinic prepolymer, active diluent and silane coupling agent, stir at 800 rpm for 1 hour, then add the photoinitiator in a light-proof environment, stir at a vacuum degree of -0.08 MPa and 1200 rpm for 1 hour, then add fumed silica and continue stirring for 1 hour to obtain a UV-curing adhesive.

[0024] Example 3: This embodiment prepares UV curing adhesive, and the specific implementation process is as follows: (1) Preparation of cross-linked prepolymer Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 10°C in an ice-water bath, stirring is applied at 120rpm, oxalyl chloride is slowly added, and the addition time is controlled to be 40min. After complete addition, constant temperature stirring is continued for reaction, and the total reaction time of oxalyl chloride is controlled to be 1.2h, wherein the amount ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1mol:0.13mol:5mL:30mL. After the reaction is completed, acetone is removed by vacuum drying, the liquid is washed with water, the aqueous phase is removed, and water is removed by vacuum drying to obtain a modified monomer.

[0025] Step A2: Take HMDI and the modified monomer, mix them and pre-heat them to 50°C, add 10 ppm of catalyst and mix them, heat them to 78°C and react for 2.5 hours, then add hydroxyethyl acrylate and add 10 ppm of catalyst, control the temperature to 70°C and react for 2.2 hours, then add 50 ppm of inhibitor and continue to react for 1.5 hours, wherein HMDI is 4,4-diisocyanate dicyclohexylmethane, the hydroxyl content of the modified monomer, the molar ratio of hydroxyethyl acrylate and HMDI is 2:2:2.25, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain a cross-linked prepolymer.

[0026] (2) Preparation of olefin prepolymer Take HMDI and terminal hydroxyl polybutadiene (number average molecular weight is 2000), mix and preheat to 50°C, add 10ppm catalyst and mix, heat to 80°C and react for 2.2h, then add hydroxyethyl acrylate and 10ppm catalyst, control the temperature to 70°C and react for 2.5h, then add 50ppm inhibitor and continue to react for 1.8h, wherein the hydroxyl content of terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI have a molar ratio of 2:2:2.15, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain an olefin prepolymer.

[0027] (3) Preparation of UV curing adhesive Ingredients: raw materials are taken according to weight parts, 40 parts of cross-linked prepolymer, which is homemade in this embodiment; 20 parts of olefinated prepolymer, which is homemade in this embodiment; 30 parts of active diluent, which is a mixture of 15 parts of 2-phenoxyethyl acrylate and 15 parts of tetrahydrofuran acrylate; 1 part of silane coupling agent, which is selected from vinyl triethoxysilane; 4 parts of photoinitiator, which is a mixture of 2.5 parts of photoinitiator MBF and 1.5 parts of photoinitiator TPO; 4 parts of fumed silica, which is selected from AEROSIL 380 type raw material.

[0028] Glue preparation: Mix the cross-linked prepolymer, olefinic prepolymer, active diluent and silane coupling agent, stir at 800 rpm for 1 hour, then add the photoinitiator in a light-proof environment, stir at a vacuum degree of -0.08 MPa and 1200 rpm for 1 hour, then add fumed silica and continue stirring for 1 hour to obtain a UV-curing adhesive.

[0029] Example 4: This embodiment prepares UV curing adhesive, and the specific implementation process is as follows: (1) Preparation of cross-linked prepolymer Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 10°C in an ice-water bath, stirring is applied at 180rpm, oxalyl chloride is slowly added, and the addition time is controlled to be 45min. After complete addition, constant temperature stirring is continued for reaction, and the total reaction time of oxalyl chloride is controlled to be 1.2h, wherein the amount ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1mol:0.12mol:6mL:30mL. After the reaction is completed, acetone is removed by vacuum drying, the liquid is washed with water, the aqueous phase is removed, and water is removed by vacuum drying to obtain a modified monomer.

[0030] Step A2: Take HMDI and the modified monomer, mix them and pre-heat them to 55°C, add 10 ppm of catalyst and mix them, heat them to 75°C and react for 2.5 hours, then add hydroxyethyl acrylate and add 10 ppm of catalyst, control the temperature to 70°C and react for 2.5 hours, then add 50 ppm of inhibitor and continue to react for 2 hours, wherein HMDI is 4,4-diisocyanate dicyclohexylmethane, the hydroxyl content of the modified monomer, the molar ratio of hydroxyethyl acrylate and HMDI is 2:2:2.27, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain a cross-linked prepolymer.

[0031] (2) Preparation of olefin prepolymer Take HMDI and terminal hydroxyl polybutadiene (number average molecular weight is 2000), mix and preheat to 50°C, add 10ppm catalyst and mix, heat to 80°C and react for 2.6h, then add hydroxyethyl acrylate and 10ppm catalyst, control the temperature to 75°C and react for 2.5h, then add 50ppm inhibitor and continue to react for 1.2h, wherein the hydroxyl content of terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI have a molar ratio of 2:2:2.18, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain an olefin prepolymer.

[0032] (3) Preparation of UV curing adhesive Ingredients: The raw materials are measured by weight: 40 parts of cross-linked prepolymer, which is homemade in this embodiment; 20 parts of olefinated prepolymer, which is homemade in this embodiment; 30 parts of reactive diluent, which is a mixture of 15 parts of 2-phenoxyethyl acrylate and 15 parts of lauryl methacrylate; 1 part of silane coupling agent, which is selected from vinyl triethoxysilane; 4 parts of photoinitiator, which is a mixture of 2.5 parts of photoinitiator MBF and 1.5 parts of photoinitiator TPO; 4 parts of fumed silica, which is selected from AEROSIL 380 type raw material.

[0033] Glue preparation: Mix the cross-linked prepolymer, olefinic prepolymer, active diluent and silane coupling agent, stir at 800 rpm for 1 hour, then add the photoinitiator in a light-proof environment, stir at a vacuum degree of -0.08 MPa and 1200 rpm for 1 hour, then add fumed silica and continue stirring for 1 hour to obtain a UV-curing adhesive.

[0034] Example 5: This embodiment prepares UV curing adhesive, and the specific implementation process is as follows: (1) Preparation of cross-linked prepolymer Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 5°C in an ice-water bath, stirring is applied at 180rpm, oxalyl chloride is slowly added, and the addition time is controlled to be 45min. After complete addition, constant temperature stirring is continued for reaction, and the total reaction time of oxalyl chloride is controlled to be 1.3h, wherein the amount ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1mol:0.14mol:5mL:35mL. After the reaction is completed, acetone is removed by vacuum drying, the liquid is washed with water, the aqueous phase is removed, and water is removed by vacuum drying to obtain a modified monomer.

[0035] Step A2: Take HMDI and the modified monomer, mix them and pre-heat them to 50°C, add 10 ppm of catalyst and mix them, heat them to 75°C and react for 2.8 hours, then add hydroxyethyl acrylate and add 10 ppm of catalyst, control the temperature to 75°C and react for 2.5 hours, then add 50 ppm of inhibitor and continue to react for 1.6 hours, wherein HMDI is 4,4-diisocyanate dicyclohexylmethane, the hydroxyl content of the modified monomer, the molar ratio of hydroxyethyl acrylate and HMDI is 2:2:2.25, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C and the material is discharged to obtain a cross-linked prepolymer.

[0036] (2) Preparation of olefin prepolymer Take HMDI and terminal hydroxyl polybutadiene (number average molecular weight is 2000), mix and preheat to 50°C, add 10ppm catalyst and mix, heat to 80°C and react for 2.5h, then add hydroxyethyl acrylate and 10ppm catalyst, control the temperature to 70°C and react for 2h, then add 50ppm inhibitor and continue to react for 1.5h, wherein the hydroxyl content of terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI have a molar ratio of 2:2:2.2, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C to obtain an olefin prepolymer.

[0037] (3) Preparation of UV curing adhesive Ingredients: The raw materials are measured by weight: 40 parts of cross-linked prepolymer, which is homemade in this embodiment; 20 parts of olefinated prepolymer, which is homemade in this embodiment; 30 parts of reactive diluent, which is a mixture of 15 parts of ethoxyethoxyethyl acrylate and 15 parts of lauryl methacrylate; 1 part of silane coupling agent, which is selected from vinyl triethoxysilane; 4 parts of photoinitiator, which is a mixture of 2.5 parts of photoinitiator MBF and 1.5 parts of photoinitiator TPO; 4 parts of fumed silica, which is selected from AEROSIL 380 type raw material.

[0038] Glue preparation: Mix the cross-linked prepolymer, olefinic prepolymer, active diluent and silane coupling agent, stir at 800 rpm for 1 hour, then add the photoinitiator in a light-proof environment, stir at a vacuum degree of -0.08 MPa and 1200 rpm for 1 hour, then add fumed silica and continue stirring for 1 hour to obtain a UV-curing adhesive.

[0039] Comparative Example In this comparative example, a bifunctional polyurethane acrylate prepolymer is prepared as a matrix of a UV-curable adhesive with reference to the prior art. The specific preparation method is as follows: HMDI and polyester diol (model HJ-2005) are mixed and preheated to 50°C, 10 ppm of catalyst is added and mixed, the temperature is raised to 80°C for reaction for 2.5 hours, hydroxyethyl acrylate is added and 10 ppm of catalyst is added, the temperature is controlled to 75°C for reaction for 2.2 hours, and 50 ppm of inhibitor is added to continue the reaction for 1.5 hours, wherein the hydroxyl content of the polyester diol, the amount of hydroxyethyl acrylate and HMDI are in a molar ratio of 2:2:2.3, the catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol. After the reaction is completed, the temperature is lowered to 50°C for discharge to obtain a bifunctional polyurethane acrylate prepolymer; Referring to Example 5, the cross-linked prepolymer and the olefinic prepolymer were replaced with 60 parts of difunctional polyurethane acrylate prepolymer, and the rest of the implementation process was exactly the same.

[0040] Take the UV curing glue prepared above, inject it into the screw hole processed by CNC using a dispensing machine, place it in a UV curing machine, and control the UV radiation intensity to 100mW / cm 2 The curing was carried out and the parameters of the cured product were tested. At the same time, it was compared with the current silicone plug process. The specific test data are shown in Table 1: Table 1

[0041] It can be seen from the test data in Table 1 that the UV-curing adhesive prepared in the embodiment can provide good protection for the threaded holes, and its curing depth reaches more than 7 mm, which fully meets the screw hole depth requirement of CNC-processed metal housings. The comprehensive mechanical properties after curing are good, and it can completely replace the traditional silicone plug from the perspective of protective performance. The mechanical properties of the existing polyurethane acrylate-based UV-curing adhesive are insufficient.

[0042] The above UV curing adhesive is used in the temporary protection production of screw holes of the notebook metal shell. The specific production data is shown in Table 2: Table 2

[0043] It can be seen from the test data in Table 2 that both the embodiment and the comparative example are suitable for assembly line operations, and the working hours are shorter than those of traditional silicone plugs. However, compared with the comparative example, the embodiment has a shorter working time for a single board and a higher yield rate, and is suitable for high-efficiency assembly line operations.

[0044] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A UV curing adhesive for temporary protection of screw holes in a notebook metal shell, characterized in that: The composition comprises, by weight: 20-40 parts of cross-linked prepolymer, 20-40 parts of olefinic prepolymer, 30-35 parts of reactive diluent, 1-1.5 parts of silane coupling agent, 4-5 parts of photoinitiator and 4-5 parts of fumed silica; The cross-linked prepolymer is prepared by the following method: Step A1: 1-thioglycerol, triethylamine and acetone are mixed, dry nitrogen is introduced for protection, the temperature is controlled at 5-15° C. in an ice-water bath, oxalyl chloride is slowly added with stirring for 1-1.5 hours, and acetone is removed by vacuum drying after the reaction is completed. The liquid is washed with water, the aqueous phase is removed, and the water is removed by vacuum drying to obtain a modified monomer; Step A2: HMDI and modified monomer are mixed and preheated to 45-55°C, 10 ppm of catalyst is added, the mixture is heated to 75-80°C and reacted for 2-3 hours, hydroxyethyl acrylate is added and 10 ppm of catalyst is added, the temperature is controlled to 70-75°C and reacted for 2-3 hours, 50 ppm of polymerization inhibitor is added and the reaction is continued for 1-2 hours, and the reaction is completed and the temperature is lowered to 50°C and discharged to obtain a cross-linked prepolymer; The preparation method of the olefination prepolymer is as follows: HMDI and terminal hydroxyl polybutadiene are mixed and preheated to 45-55° C., 10 ppm of a catalyst is added and mixed, the temperature is raised to 75-80° C. for reaction for 2-3 hours, hydroxyethyl acrylate is added and 10 ppm of a catalyst is added, the temperature is controlled to 70-75° C. for reaction for 2-3 hours, 50 ppm of a polymerization inhibitor is added, the reaction is continued for 1-2 hours, and the temperature is lowered to 50° C. for discharge after the reaction is completed to obtain the olefination prepolymer.

2. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: The usage ratio of oxalyl chloride, 1-thioglycerol, triethylamine and acetone is 0.1 mol: 0.12-0.14 mol: 4-6 mL: 25-35 mL.

3. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 2, characterized in that: In step A2, the molar ratio of the hydroxyl content of the modified monomer, hydroxyethyl acrylate and HMDI is 2:2:2.2-2.

3.

4. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: In the process of preparing the olefination prepolymer, the molar ratio of the hydroxyl content of the terminal hydroxyl polybutadiene, hydroxyethyl acrylate and HMDI is 2:2:2.1-2.25, and the number average molecular weight of the terminal hydroxyl polybutadiene is 1000-3000.

5. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate, and the inhibitor is 4-methoxyphenol.

6. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: The active diluent is one or more of ethoxyethoxyethyl acrylate, tetrahydrofuran acrylate, 2-phenoxyethyl acrylate, lauric acid acrylate, lauryl methacrylate and isodecyl acrylate.

7. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: The silane coupling agent is one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

8. The UV curing adhesive for temporary protection of screw holes of a notebook metal shell according to claim 1, characterized in that: The photoinitiator is one or more of photoinitiator 184 , photoinitiator MBF, photoinitiator 1173 , photoinitiator TPO and photoinitiator 819 .

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