A polyurethane acrylate, high-temperature-resistant weld adhesive and a preparation method thereof

Abstract

This invention relates to a polyurethane acrylate, a high-temperature resistant weld adhesive, and a method for preparing the same. The polyurethane acrylate has a structure derived from (a) a polyurethane acrylate prepolymer, a structure derived from (b) a capping agent, and a structure derived from (c) a blocking agent; the polyurethane acrylate does not contain NCO groups; the molar ratio of the structure derived from (b) the capping agent to the structure derived from (c) the blocking agent is 1.5 to 3:1; the capping agent is an acrylate monomer containing a group reactive with an NCO group; the structure of (a) the polyurethane acrylate prepolymer includes repeating units derived from the following components: a first component is an aliphatic diisocyanate; a second component is a saturated diol; and a third component is a saturated triol. When this polyurethane acrylate is applied to a weld adhesive, it can provide excellent adhesion, high-temperature resistance, and anti-yellowing properties without the presence of PVC resin, while also exhibiting good compatibility with powder coatings.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a polyurethane acrylate, a high-temperature resistant weld adhesive, and a method for preparing the same. Background Technology

[0002] In the manufacturing process of metal components (such as automobile bodies, construction machinery, and household appliances), metal plates are typically joined by welding, resulting in weld seams. To achieve waterproofing, rust prevention, and improve structural safety and aesthetics, these weld seams must be sealed with weld sealant before painting.

[0003] In traditional processes, PVC-based weld sealant is typically used in conjunction with oil-based coatings. However, with increasingly stringent environmental regulations and advancements in coating technology, powder coatings, due to their solvent-free nature, high utilization rate, and superior coating performance, have gradually replaced traditional oil-based coatings. However, the curing temperature of powder coatings is typically 180-220℃. At this temperature, PVC-based weld sealant will exhibit problems such as yellowing, blistering, cracking, and decreased adhesion due to the oxidative decomposition of PVC. This can lead to powder coating sagging, color variations, and the release of HCl, which can corrode the substrate and reduce the lifespan of the components.

[0004] Currently, while high-temperature resistant weld sealants are available on the market, their high-temperature resistance is limited because they still contain PVC resin, failing to fundamentally solve the problems caused by the oxidative decomposition of PVC. For example, CN115785857A introduces liquid rubber to reduce the proportion of plasticizer and PVC resin, and uses tin maleate stabilizer as a heat stabilizer to prepare a high-temperature curing PVC weld sealant. However, this weld sealant still uses PVC resin, and cannot completely avoid its decomposition under high-temperature conditions. Similarly, CN117777184A prepares an epoxy-organic silicone cyclic compound and applies it to weld sealants to improve their heat resistance, flexibility, and adhesion, but this weld sealant still contains PVC resin.

[0005] Therefore, there is an urgent need to develop a weld adhesive product that is free of PVC resin, has excellent adhesion, high temperature resistance and anti-yellowing properties, and is compatible with powder coatings. Summary of the Invention

[0006] The primary objective of this invention is to overcome the defects or shortcomings of existing weld adhesives and to provide a polyurethane acrylate.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned polyurethane acrylate.

[0008] Another object of the present invention is to provide the application of the above-mentioned polyurethane acrylate in the preparation of weld adhesive.

[0009] Another object of the present invention is to provide a weld adhesive.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned weld adhesive.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solution: A polyurethane acrylate having a structure derived from (a) a polyurethane acrylate prepolymer, a structure derived from (b) a capping agent, and a structure derived from (c) a blocking agent; the polyurethane acrylate is free of NCO groups; the molar ratio of the structure derived from (b) the capping agent to the structure derived from (c) the blocking agent is 1.5 to 3:1; the capping agent is an acrylate monomer containing an active group that reacts with an NCO group; the structure of (a) the polyurethane acrylate prepolymer comprises repeating units derived from the following components: The first component is an aliphatic diisocyanate; the second component is a saturated diol, including hydrogenated bisphenol A and polyether diol; the third component is a saturated triol; the molar ratio between the aliphatic diisocyanate, hydrogenated bisphenol A, polyether diol and saturated triol is 6~8:1~1.5:1~1.5:1.

[0012] This invention uses saturated triols as the core raw material, combined with hydrogenated bisphenol A, polyether diols, aliphatic diisocyanates, end-capping agents, and blocking agents, to successfully prepare polyurethane acrylates with a "star-shaped" structure. The "star-shaped" structure endows the polyurethane acrylates with highly branched characteristics, which not only improves the crosslinking efficiency during thermosetting but also significantly enhances the material's cohesiveness, thereby effectively increasing the crosslinking density and heat resistance of the cured product. Specifically, the fully saturated hydrogenated bisphenol A and aliphatic diisocyanate act as a rigid skeleton, giving the polyurethane acrylates excellent resistance to yellowing and heat resistance. Simultaneously, the introduction of polyether segments improves the flexibility of the polyurethane acrylates, making them less prone to cracking and brittleness after high-temperature curing. More importantly, by controlling the molar ratio of end-capping agents to blocking agents, this invention ensures that the prepared polyurethane acrylates have sufficient carbon-carbon double bond groups for thermocrosslinking and curing, thus giving the material excellent adhesive properties. At the same time, it retains sufficient heat-unblocking groups, which unblock and release active NCO groups during heating, thereby significantly enhancing the interfacial bonding performance with powder coatings.

[0013] Preferably, the molar ratio of the end-capping agent to the blocking agent is 2~2.5:1.

[0014] Preferably, the aliphatic diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, or 1,5-pentanediisocyanate.

[0015] More preferably, the aliphatic diisocyanate is isophorone diisocyanate.

[0016] Preferably, the saturated triol is one or both of trimethylolpropane or ethoxylated trimethylolpropane.

[0017] More preferably, the saturated triol is ethoxylated trimethylolpropane.

[0018] Preferably, the number-average molecular weight of the ethoxylated trimethylolpropane is 500-1500.

[0019] More preferably, the number-average molecular weight of the ethoxylated trimethylolpropane is 500-1000.

[0020] Most preferably, the number-average molecular weight of the ethoxylated trimethylolpropane is 500.

[0021] Preferably, the polyether diol is one or both of polytetrahydrofuran ether diol or polyoxypropylene ether diol.

[0022] Preferably, the number average molecular weight of the polyether diol is 500 to 2000.

[0023] More preferably, the number-average molecular weight of the polyether diol is 800-1500.

[0024] Most preferably, the number-average molecular weight of the polyether diol is 1000.

[0025] Preferably, the sealing agent described in this invention can be a commonly used sealing agent in the art, such as one or more of methyl ethyl oxime, caprolactam, or 3,5-dimethylpyrazole.

[0026] More preferably, the blocking agent is butanone oxime.

[0027] Preferably, the capping agent is an acrylate monomer containing one hydroxyl group. In this invention, commonly used acrylate monomers containing one hydroxyl group in the art can be selected, such as one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, or hydroxypropyl methacrylate.

[0028] The above-mentioned method for preparing polyurethane acrylate is also within the scope of protection of this invention, and includes the following steps: after stirring saturated triol, hydrogenated bisphenol A, polyether diol and catalyst evenly, add them dropwise to aliphatic diisocyanate, stir and react, and after the reaction is complete, add end-capping agent and blocking agent, and react until the infrared peak of NCO group disappears, thereby obtaining the polyurethane acrylate.

[0029] Those skilled in the art will know that a catalyst can be added to increase the reaction rate during the preparation of polyurethane acrylates. The catalyst can be one or more commonly used catalysts in the art, such as, but not limited to, dibutyltin dilaurate, stannous octoate, tetramethylbutanediamine, or triethylenediamine. Preferably, the catalyst is dibutyltin dilaurate.

[0030] As is known to those skilled in the art, in the preparation of polyurethane acrylates, the amount of catalyst added is generally 0.2 to 1% of the total mass of the reaction system.

[0031] As is known to those skilled in the art, in the preparation of polyurethane acrylates, the main reactants must undergo strict dehydration treatment to avoid side reactions between water and isocyanate groups, which could lead to uncontrolled crosslinking and gelation of the reaction system. The dehydration treatment can be performed by stirring the reactants at 90-110°C under vacuum. Dehydration is considered complete when the water content in the system is ≤300 ppm.

[0032] The method for testing moisture content is as follows: using the Karl Fischer method, an appropriate amount of dehydrated raw material is accurately weighed into the titration cup of the moisture analyzer using a sampler, and the moisture content is automatically measured and calculated by the instrument.

[0033] Those skilled in the art will know that the content of NCO groups in the reaction system can be determined by titration to judge the degree of reaction. Preferably, the condition for judging the completeness of the reaction is that the reaction solution is titrated with -NCO value, and the deviation of the titration result from the theoretical value is ≤5%, then the reaction is judged to be complete.

[0034] Preferably, the reaction temperature is 50~80℃.

[0035] Preferably, the dripping time is 1 to 2 hours.

[0036] The application of the aforementioned polyurethane acrylate in the preparation of weld adhesives is also within the scope of protection of this invention.

[0037] The present invention also provides a weld adhesive, comprising the following components in parts by weight: 30-80 parts of the above-mentioned polyurethane acrylate; 5-15 parts of polyester plasticizer; 5-10 parts of fumed silica; 20-50 parts of filler; 5-10 parts of dehydrating agent; Colorant 1-5 parts; 2-8 parts of crosslinking agent; 1-5 parts of thermal initiator.

[0038] In this invention, the polyester plasticizer can be a commonly used polyester plasticizer in the art, such as one or two of polyadipate ester plasticizers and sebacic acid plasticizers.

[0039] Specifically, the adipic acid plasticizer is one or more of polypropylene adipate, polybutylene adipate, or polyethylene adipate.

[0040] Specifically, the sebacic acid plasticizer is one or more of polypropylene sebacic acid, polybutylene sebacic acid, or polyethylene sebacic acid.

[0041] Preferably, the polyester plasticizer is an adipic acid-based plasticizer.

[0042] More preferably, the polyester plasticizer is polypropylene adipate.

[0043] As is known to those skilled in the art, the plasticizing effect of polyester plasticizers is mainly affected by their number-average molecular weight. Generally, the number-average molecular weight of polyester plasticizers is 1500-8000. Preferably, the number-average molecular weight of the polyester plasticizer is 2000-6000.

[0044] In this invention, the filler can be one or more commonly used fillers in the art, such as calcium carbonate, kaolin, talc, or silica powder. Preferably, the filler is silica powder.

[0045] Preferably, the crosslinking agent is one or more of trimethylolpropane trimethacrylate, pentaerythritol triacrylate, or triallyl isocyanurate.

[0046] In this invention, the thermal initiator can be one or more commonly used thermal initiators in the art, such as dicumyl peroxide, bis-tert-butyldicumyl peroxide, benzoyl peroxide, or cumyl hydroperoxide. Preferably, the thermal initiator is dicumyl peroxide.

[0047] In this invention, the dehydrating agent can be one or more commonly used dehydrating agents in the art, such as calcium oxide, 4A molecular sieve, or barium oxide. Preferably, the dehydrating agent is calcium oxide.

[0048] In this invention, the colorant can be one or more commonly used colorants in the art, such as titanium dioxide, lithopone, or zinc oxide. Preferably, the colorant is titanium dioxide.

[0049] The above-mentioned method for preparing weld adhesive is also within the scope of protection of this invention, including the following steps: stirring and mixing the above-mentioned polyurethane acrylate, polyester plasticizer, fumed silica, filler, dehydrating agent and colorant evenly, then adding crosslinking agent and thermal initiator and stirring and mixing evenly, and removing air bubbles under vacuum to obtain the weld adhesive.

[0050] Compared with the prior art, the beneficial effects of the present invention include: This invention uses saturated triols as the core raw material, hydrogenated bisphenol A and aliphatic diisocyanate as rigid frameworks, and polyether diols as flexible segments, combined with end-capping agents and blocking agents, to prepare a "star-shaped" polyurethane acrylate. The polyurethane acrylate molecule contains a saturated rigid framework and is free of yellowing-prone groups, thus endowing the polymer with excellent anti-yellowing properties, heat resistance, and mechanical properties. The polyether segments provide good flexibility, making it less prone to cracking and brittleness after high-temperature curing. More importantly, by controlling the molar ratio of end-capping agents to blocking agents, this invention allows the polyurethane acrylate to retain sufficient carbon-carbon double bond groups and thermally descalable NCO groups. The carbon-carbon double bond groups enable thermal cross-linking and curing, providing excellent adhesion properties, while the thermally descalable NCO groups significantly enhance the interfacial bonding ability between the polyurethane acrylate and powder coatings, thereby improving the compatibility between weld adhesives and powder coatings. When this polyurethane acrylate is applied to weld adhesive, its unique structure and molecular properties significantly improve the thermosetting crosslinking efficiency of the weld adhesive, enhance the crosslinking density and cohesive force of the cured product, and further give the weld adhesive excellent adhesion, heat resistance, and anti-yellowing properties. Therefore, the weld adhesive provided by this invention can maintain good shear strength after baking at 220°C without PVC resin, and the adhesive does not exhibit yellowing, cracking, or delamination. It also has good compatibility with powder coatings, and the cured coating does not have defects such as discoloration, blistering, or sagging. Detailed Implementation

[0051] The present invention will be further described below with reference to embodiments and comparative examples. These embodiments are merely typical descriptions of the present invention, but the present invention is not limited thereto. Unless otherwise specified, the test methods used in the following embodiments and comparative examples are conventional methods, and the raw materials and reagents used are commercially available from conventional commercial sources.

[0052] Information on the raw materials used in each embodiment and comparative example is shown in Table 1.

[0053] Table 1. Raw material information for each embodiment and comparative example.

[0054] The same reagents were used in parallel experiments of all embodiments and comparative examples of this invention.

[0055] Examples 1-8 and Comparative Examples 1-7 provide different polyurethane acrylates, which are prepared by the following steps: S1. According to the formula, weigh out saturated triol, hydrogenated bisphenol A, polyether diol and catalyst, stir and mix evenly to obtain a polyol mixture; S2. According to the formula, add aliphatic diisocyanate to a dry four-necked flask, heat to 80°C under nitrogen protection, and add the polyol mixture obtained in step S1 dropwise to the reaction system through a constant pressure dropping funnel. The dropping time is 2 hours. After the dropping is completed, keep the temperature and stir the reaction until the reaction is complete. S3. After the system cools down to 60°C, according to the formula, the end-capping agent and blocking agent are added dropwise to the reaction system through a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, the system is kept warm and stirred until the infrared peak of the NCO group disappears, and the polyurethane acrylate is obtained.

[0056] The preparation formulations of polyurethane acrylates in each embodiment and comparative example are shown in Table 2 and Table 3.

[0057] Table 2. Preparation formulations of polyurethane acrylates in each example.

[0058] Table 3. Preparation formulations of polyurethane acrylates in each comparative example.

[0059] Application testing (1) Preparation of weld adhesive The polyurethane acrylates prepared in each embodiment and comparative example were formulated into weld adhesives, and the preparation method of the weld adhesives included the following steps: Weigh 60g of polyurethane acrylate, 10g of polyester plasticizer, 5g of fumed silica, 40g of filler, 5g of dehydrating agent, and 3g of titanium dioxide and add them to a planetary mixer. Mix them evenly at 600 rpm. Then add 2g of crosslinking agent and 2g of thermal initiator and mix them evenly at 300 rpm. Remove air bubbles under vacuum to obtain the weld adhesive.

[0060] The raw material information for the weld adhesive is as follows: Polyester plasticizer: PPA-2500, purchased from Wuhan Shuer Biotechnology; Fumed silica: Aerosil 200, purchased from Evonik Degussa; Filler: Silica powder, purchased from Jiangsu Shengtian New Materials Co., Ltd.; Dehydrating agent: calcium oxide, purchased from Hunan Xiangyi Calcium Industry Co., Ltd.; Titanium dioxide: Titanium dioxide was purchased from Guangxi Jinmao Titanium Industry Co., Ltd. Crosslinking agent: Trimethylolpropane trimethacrylate (TMPTMA), purchased from Guangdong Yingtai New Materials Co., Ltd. Thermal initiator: dicumyl peroxide, DCP, purchased from Arkema.

[0061] (2) Weld adhesive performance test The weld adhesive prepared above was subjected to performance testing, and the test results are shown in Table 4. The specific test methods and conditions are as follows: 1. Shear strength: According to GB / T 7124 standard, the lap joint specimens were prepared and baked at 220℃ for 30 minutes. After cooling to room temperature, they were subjected to tensile shear test at a specified tensile speed on a universal testing machine, and their shear strength was recorded.

[0062] 2. Yellowing test: Referring to the GB / T 39294-2020 standard, the weld adhesive was applied to the cold-rolled plate in the form of a 100mm*50mm*2mm adhesive layer, and baked at 220℃ for 30 minutes. After cooling to room temperature, the color difference value ΔE before and after curing was observed. The larger the ΔE value, the more severe the yellowing.

[0063] 3. Appearance and adhesion of cured weld adhesive: 3.1 Appearance of cured weld adhesive Apply the weld adhesive to the cold-rolled sheet in a 100mm*50mm*2mm layer and bake it at 220℃ for 30 minutes. After cooling to room temperature, observe the cracking and bubbling conditions. If cracking or bubbling occurs, it is considered unqualified.

[0064] 3.2 Adhesive properties of weld seams Apply weld adhesive to a 100mm*50mm*2mm layer on a cold-rolled sheet and bake at 220℃ for 30 minutes. After cooling to room temperature, cut a small opening at one end of the adhesive layer to create a starting end that is easy to hold. Hold this starting end and peel the adhesive strip off the substrate at an angle of approximately 130° to 160°. Observe the failure mode of the weld adhesive: if the failure occurs inside the weld adhesive layer, it is cohesive failure, denoted as CF, and record the area percentage of cohesive failure; if the failure occurs at the interface between the weld adhesive and the substrate, it is adhesive interface failure, denoted as AF.

[0065] 4. Hardness test: Referring to GB / T 531.1 standard, the weld adhesive was applied to the release paper in the form of a 50mm*50mm*6mm adhesive layer, baked at 220℃ for 30 minutes, cooled to room temperature, and then the hardness was tested under standard conditions.

[0066] 5. Elongation test: Referring to GB / T 528-2020 standard, the weld adhesive was applied to the release paper in the form of a 100mm*50mm*2mm adhesive layer, and baked at 220℃ for 30 minutes. After cooling to room temperature, the elongation was tested under standard conditions.

[0067] 6. Compatibility test with powder coatings: 6.1 Appearance of Powder Coating Apply the weld adhesive to the cold-rolled sheet in a 100*50mm*2mm layer, spray on powder coating, place vertically in an oven, and bake at 220℃ for 30 minutes. After cooling to room temperature, observe the flatness of the adhesive and the coating on the sheet. If there is sagging or unevenness, it is considered unqualified.

[0068] 6.2 Adhesion Test The adhesion performance of the weld adhesive was tested using the cross-cut test, where grade 0 was no peeling (best adhesion) and grade 5 was complete peeling (worst adhesion).

[0069] Table 4 Performance test results of weld adhesive

[0070] As shown in Table 4, this invention prepares a star-shaped polyurethane acrylate using saturated triol, hydrogenated bisphenol A, polyether diol, aliphatic diisocyanate, end-capping agent, and sealing agent as raw materials. When this polyurethane acrylate is applied to weld adhesive, the resulting weld adhesive exhibits excellent mechanical and adhesive properties after high-temperature baking at 220℃, with a shear strength exceeding 4.2 MPa. Furthermore, it exhibits a complete cohesive failure mode (100% cohesive failure area), indicating a strong bond between the adhesive layer and the substrate. Simultaneously, the adhesive demonstrates excellent thermal stability and flexibility, showing no yellowing, cracking, or delamination after curing. In addition, this weld adhesive has good compatibility with powder coatings, and the cured coating exhibits good adhesion with no surface defects such as discoloration, blistering, or sagging. Therefore, the weld adhesive provided by this invention does not require the addition of PVC resin, thus avoiding the risk of steel plate corrosion caused by the high-temperature decomposition of PVC and the generation of HCl.

[0071] Comparing Example 1 with Comparative Examples 1 and 5, it can be seen that by introducing hydrogenated bisphenol A, the present invention imparts a rigid structure to polyurethane acrylate while avoiding the introduction of easily yellowing groups, thereby giving the weld adhesive excellent thermal stability and good compatibility with powder coatings. After curing, it will not affect the color and leveling of the powder coating.

[0072] Comparing Example 1 and Comparative Example 2, it can be seen that by introducing saturated triols, the polyurethane acrylate prepared by this invention exhibits a "star-shaped" structure, which effectively increases the crosslinking density after curing, thereby endowing the polyurethane acrylate with good heat resistance and shear strength, and no bubbling phenomenon after high-temperature baking.

[0073] Comparing Example 1 and Comparative Example 3, it can be seen that when the molar ratio of the structure from the (b) end-capping agent in the polyurethane acrylate is too high, although the polyurethane acrylate contains a sufficient amount of carbon-carbon double bond groups and has excellent adhesive properties, due to the lack of thermally decapping groups, the number of NCO groups released at high temperature is limited, making it difficult to effectively participate in the curing reaction of the powder coating, resulting in a significant decrease in the adhesion performance of the cured coating.

[0074] Comparing Example 1 and Comparative Example 4, it can be seen that when the molar ratio of the structure from (c) the sealant in the polyurethane acrylate is too high, although the polyurethane acrylate contains a sufficient amount of heat-deblocking groups, it can release a sufficient amount of NCO groups after heat deblocking, thereby improving the compatibility and adhesion performance with powder coatings. However, due to the low content of carbon-carbon double bond groups, its adhesive performance will be significantly reduced.

[0075] Comparing Example 1 and Comparative Example 6, it can be seen that when the polyurethane acrylate structure lacks polyether segments, the colloid will become too hard and crack.

[0076] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A polyurethane acrylate, characterized in that, The polyurethane acrylate has a structure derived from (a) a polyurethane acrylate prepolymer, a structure derived from (b) a capping agent, and a structure derived from (c) a blocking agent; the polyurethane acrylate does not contain NCO groups; the molar ratio of the structure derived from (b) the capping agent to the structure derived from (c) the blocking agent is 1.5 to 3:1; the capping agent is an acrylate monomer containing an active group that reacts with an NCO group; The structure of (a) the polyurethane acrylate prepolymer comprises repeating units derived from the following components: The first component is an aliphatic diisocyanate; the second component is a saturated diol, including hydrogenated bisphenol A and polyether diol; the third component is a saturated triol; the molar ratio between the aliphatic diisocyanate, hydrogenated bisphenol A, polyether diol and saturated triol is 6~8:1~1.5:1~1.5:

1.

2. The polyurethane acrylate according to claim 1, characterized in that, The saturated triol is one or both of trimethylolpropane or ethoxylated trimethylolpropane.

3. The polyurethane acrylate according to claim 2, characterized in that, The number-average molecular weight of the ethoxylated trimethylolpropane is 500-1500.

4. The polyurethane acrylate according to claim 1, characterized in that, The polyether diol is one or both of polytetrahydrofuran ether diol or polyoxypropylene ether diol.

5. The polyurethane acrylate according to claim 1, characterized in that, The number-average molecular weight of the polyether diol is 500-2000.

6. The polyurethane acrylate according to claim 1, characterized in that, The blocking agent is one or more of butanone oxime, caprolactam, or 3,5-dimethylpyrazole.

7. The method for preparing the polyurethane acrylate according to any one of claims 1 to 6, characterized in that, The process includes the following steps: saturated triol, hydrogenated bisphenol A, polyether diol and catalyst are stirred evenly and then added dropwise to aliphatic diisocyanate. The mixture is stirred and reacted. After the reaction is complete, end-capping agent and blocking agent are added. The reaction continues until the infrared peak of the NCO group disappears, thus obtaining the polyurethane acrylate.

8. The use of the polyurethane acrylate according to any one of claims 1 to 6 in the preparation of weld adhesive.

9. A weld adhesive, characterized in that, Includes the following components by weight: 30-80 parts of the polyurethane acrylate according to any one of claims 1-6; 5-15 parts of polyester plasticizer; 5-10 parts of fumed silica; 20-50 parts of filler; 5-10 parts of dehydrating agent; Colorant 1-5 parts; 2-8 parts of crosslinking agent; 1-5 parts of thermal initiator.

10. The method for preparing the weld adhesive according to claim 9, characterized in that, The process includes the following steps: mixing the polyurethane acrylate, polyester plasticizer, fumed silica, filler, dehydrating agent and colorant as described in any one of claims 1 to 6 until homogeneous; then adding the crosslinking agent and thermal initiator and mixing until homogeneous; and finally removing air bubbles under vacuum to obtain the weld adhesive.

Images