Environment-friendly high methyl etherified resin adhesive and preparation method thereof

Abstract

This invention relates to the field of adhesive technology, specifically disclosing an environmentally friendly high-methyl etherified resin adhesive and its preparation method. The environmentally friendly high-methyl etherified resin adhesive comprises raw materials: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. The adhesive of this invention uses highly methyl etherified, low-free-formaldehyde melamine resin as the main matrix, and is compounded with bio-based polyol, achieving green environmental protection from the source. Furthermore, multi-functionalized nano-silica is introduced to form a chemically bonded reinforcing network with the resin matrix. Simultaneously, the flexible segments of the bio-based polyol act as internal toughening agents, enabling the adhesive to achieve high hardness, high wear resistance, and excellent adhesion while also possessing good toughness.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to an environmentally friendly highly methylated resin adhesive and its preparation method. Background Technology

[0002] Amino resins, especially melamine-formaldehyde resins, are widely used in the adhesives industry due to their excellent hardness, abrasion resistance, heat resistance, and chemical resistance. However, traditional melamine resins release large amounts of free formaldehyde during synthesis and curing, posing serious harm to human health and the environment, and failing to meet increasingly stringent environmental regulations.

[0003] To reduce formaldehyde release, melamine-formaldehyde resins are typically modified industrially through etherification. High-methyl-etherified melamine-formaldehyde resin (HMMM), by converting most of the hydroxymethyl groups (-CH2OH) to methoxy groups (-OCH3), significantly reduces free formaldehyde content, making it an ideal matrix resin for preparing environmentally friendly adhesives. However, current high-methyl-etherified resin adhesives still face the following technical bottlenecks: First, single high-methyl etherified resins have the disadvantages of being brittle and having insufficient adhesion to certain polar substrates. Although the mechanical properties can be improved by adding inorganic nanofillers (such as nano silica), unmodified nanoparticles are very easy to agglomerate in the resin matrix, which leads to stress concentration, performance degradation, and even accelerated aging.

[0004] Secondly, to promote the curing of highly methylated resins, existing technologies often employ strong acid catalysts (such as p-toluenesulfonic acid). While these catalysts can effectively lower the curing temperature, they are highly corrosive and have a pungent odor, posing safety and health risks during production and application. Furthermore, residual acidic substances may affect the long-term weather resistance of the cured product. In addition, these catalysts exhibit some activity at room temperature, significantly shortening the shelf life of single-component adhesives.

[0005] Furthermore, existing formulations heavily utilize petroleum-based raw materials (such as petrochemical polyols), which inherently raise concerns about the non-renewable nature of resources and their "non-green" nature. Although some studies have attempted to introduce bio-based raw materials, this often comes at the cost of sacrificing the performance of the final product, making it difficult to replace traditional products in high-end applications.

[0006] In summary, existing technologies struggle to simultaneously achieve low formaldehyde release, excellent overall performance, and good storage stability in a single system. Based on the above, this invention proposes an environmentally friendly highly methylated resin adhesive and its preparation method. Summary of the Invention

[0007] To address the challenges of achieving low formaldehyde release, excellent overall performance, and good storage stability simultaneously in a single system, this invention proposes an environmentally friendly highly methylated resin adhesive and its preparation method.

[0008] In a first aspect, the present invention provides an environmentally friendly highly methylated resin adhesive, which adopts the following technical solution: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60-80 parts of melamine-formaldehyde resin, 5-15 parts of modified nano-silica, 10-25 parts of bio-based polyol, 15-30 parts of co-solvent, 5-10 parts of curing agent, 1-3 parts of catalyst, and 1-2 parts of leveling agent.

[0009] Preferably, the melamine-formaldehyde resin has a solids content of ≥98% and a free formaldehyde content of ≤0.2%.

[0010] Preferably, the modified nano-silica is nano-silica that has been surface-modified with an organic modifier, and its particle size is 10-50 nm.

[0011] Furthermore, the modified nano-silica is nano-silica that has been surface-modified with an organic modifier, and its particle size is 20-30 nm.

[0012] Preferably, the modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether and sonicate to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether to obtain a phenylphosphonic acid mixed solution; S2. Under nitrogen protection, the phenylphosphonic acid mixed solution is added dropwise to the nano silica suspension while stirring, and the addition is completed within 30 minutes. The system is heated to 75-85℃ and refluxed for 8-10 hours to obtain the intermediate reaction solution. S3. Add 1,2-epoxy-9-decene and aluminum acetylacetonate to the intermediate reaction solution, heat the system to 90-95℃, stir the reaction for 4-5 hours, then raise the system temperature to 100-110℃, add hydroxyethyl methacrylate phosphate, and continue stirring the reaction for 4-5 hours to obtain the modified reaction solution. S4. Cool the modified reaction solution, centrifuge, and wash with propylene glycol methyl ether 3-5 times to obtain modified nano-silica.

[0013] Preferably, the mass ratio of nano-silica to phenylphosphonic acid in step S1 is 1:0.1-0.3.

[0014] Preferably, the ultrasonic processing in step S1 specifically involves controlling the ultrasonic power to be 300-500W, the ultrasonic frequency to be 25-35kHz, using pulse mode, working for 2-3 seconds, stopping for 1-2 seconds, and the total processing time being 1-2 hours.

[0015] Preferably, the amount of propylene glycol methyl ether used in the nano-silica suspension in step S1 is 10-20 times the mass of the nano-silica.

[0016] Preferably, the amount of propylene glycol methyl ether in the phenylphosphonic acid mixed solution in step S1 is 5-10 times the mass of phenylphosphonic acid.

[0017] Preferably, the stirring rate in step S2 is 200-400 rpm.

[0018] Preferably, in step S3, the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, hydroxyethyl methacrylate phosphate, and nano-silica is 15-25:0.5-1.5:5-10:100.

[0019] Preferably, the bio-based polyol is one or more of castor oil-based polyol, cashew phenol-based polyol, and soybean oil-based polyol.

[0020] Preferably, the bio-based polyol is a castor oil-based polyol with a hydroxyl value of 160-190 mgKOH / g and a functionality of 1.6-2.5.

[0021] Preferably, the co-solvent is an alcohol ether solvent.

[0022] Preferably, the co-solvent is propylene glycol methyl ether.

[0023] Preferably, the curing agent is one of methylhexahydrophthalic anhydride, nadic anhydride, or dicyandiamide.

[0024] Preferably, the curing agent is methylhexahydrophthalic anhydride.

[0025] Preferably, the catalyst is a mixture of L-lysine methyl ester hydrochloride and zinc acetylacetone.

[0026] Preferably, the catalyst is L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2-4:1.

[0027] Preferably, the leveling agent is BYK-306.

[0028] Secondly, the present invention provides a method for preparing an environmentally friendly highly methylated resin adhesive, employing the following technical solution: A method for preparing an environmentally friendly highly methylated resin adhesive includes the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Under stirring conditions, add the bio-based polyol to the co-solvent and dissolve it at 40-60℃ for 10-20 minutes to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50-60℃, disperse for 30-60 min, and obtain the modified slurry; Step 4: Cool the modified slurry system to 30-40℃, add melamine-formaldehyde resin and catalyst while stirring, and mix for 20-40 minutes to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix for 10-20 minutes, then add the curing agent and continue stirring until uniform to obtain an environmentally friendly high-methyl etherified resin adhesive.

[0029] Preferably, the stirring rate in step 2 is 200-300 rpm.

[0030] Preferably, the dispersion in step 3 specifically involves shear dispersion at a rate of 2000-3000 r / min.

[0031] Preferably, the stirring rate in step 4 is 400-600 rpm.

[0032] Preferably, the stirring rate in step 5 is 150-250 rpm.

[0033] In summary, the present invention has the following beneficial effects: 1. This invention uses highly methylated melamine-formaldehyde resin with a solid content ≥98% and a free formaldehyde content ≤0.2% as the main resin, thereby reducing the content of harmful substances in the adhesive from the source and reducing the emission of volatile organic compounds (VOCs), making the product safer and more environmentally friendly. Simultaneously, the formula incorporates castor oil-based polyols, which are derived from renewable resources, replacing some petroleum-based raw materials, reducing the product's carbon footprint, and meeting the requirements of green chemistry and sustainable development.

[0034] 2. This invention combines modified nano-silica with bio-based polyols. On one hand, the nano-silica, modified with multiple functional groups such as phenylphosphonic acid, epoxy decene, and hydroxyethyl methacrylate phosphate, possesses not only resin-loving groups on its surface but also reactive groups. This allows the nano-silica to firmly bond with the resin matrix via chemical bonds (covalent bonds), forming a nano-reinforcing network at the molecular level, thereby significantly improving the adhesive's hardness, wear resistance, and adhesion. On the other hand, the flexible long-chain structure of the bio-based polyol is introduced into the rigid melamine resin crosslinking network, acting as an "internal toughening" agent, effectively improving the brittle texture and poor impact resistance of traditional melamine resins after curing. The synergistic effect of these two components gives the adhesive both high hardness and high toughness, achieving a perfect balance of rigidity and toughness.

[0035] 3. This invention employs a catalyst system composed of L-lysine methyl ester hydrochloride and zinc acetylacetonate. This system possesses potential catalytic properties, exhibiting low activity at room temperature, ensuring a long shelf life and application period for the adhesive, facilitating operation. Under heat curing conditions, it can effectively catalyze the crosslinking reaction of the resin, ensuring rapid and complete curing of the adhesive. Furthermore, compared to traditional strong acid catalysts, this catalytic system is milder, avoiding problems such as short application period due to excessively rapid catalysis or corrosion of substrates and equipment due to excessive acidity, thus improving the process stability and application reliability of the product. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the embodiments.

[0037] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0038] The key raw materials used in this invention are sourced from the following sources: Melamine-formaldehyde resin: Model CYMEL 303LF, purchased from Foshan Weng Kai'er Trading Co., Ltd.; Nano silica: CAS No. 60676-86-0, particle size 20nm, purchased from Shanghai Xiaohuang Nanotechnology Co., Ltd.; Propylene glycol methyl ether: CAS No. 107-98-2, purchased from Jinan Chengyijia Chemical Technology Co., Ltd.; Phenylophosphonic acid: CAS No. 1571-33-1, purchased from Hubei Xinghengye Technology Co., Ltd.; 1,2-Epoxy-9-decene: Product No. E918212, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Aluminum acetylacetone: CAS No. 13963-57-0, purchased from Jinan Zhiheng Zhiyuan Chemical Technology Co., Ltd.; Hydroxyethyl methacrylate phosphate: CAS No. 52628-03-2, purchased from Zhongshan Dixing Chemical Co., Ltd.; Castor oil-based polyol: model AC006, hydroxyl value 178, functionality 2, purchased from Shandong Jiaying Chemical Technology Co., Ltd. Methylhexahydrophthalic anhydride: CAS No. 25550-51-0, purchased from Jinan Yuyi Chemical Co., Ltd.; L-Lysine methyl ester hydrochloride: CAS No. 26348-70-9, purchased from Hubei Watson Chemical Technology Co., Ltd.; Zinc acetylacetone: CAS No. 14024-63-6, purchased from Shandong Qiangsen Chemical Co., Ltd.; Leveling agent: Model BYK-306, purchased from Guangzhou Huiwangcheng Chemical Co., Ltd.

[0039] Preparation Examples 1-3 and Comparative Preparation Examples 1-3 provide a method for preparing modified nano-silica.

[0040] Preparation Example 1 Modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether at 10 times its own weight, control the ultrasonic power at 300W, the ultrasonic frequency at 25kHz, use pulse mode, work for 2s, stop for 1s, and the total processing time is 1h to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether at 5 times its own weight to obtain a phenylphosphonic acid mixed solution. S2. Under nitrogen protection, the phenylphosphonic acid mixed solution was added dropwise to the nano silica suspension at a rate of 200 rpm while stirring, and the addition was completed within 30 min. The system was then heated to 75 °C and refluxed for 8 h to obtain the intermediate reaction solution. S3. Controlling the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, hydroxyethyl methacrylate phosphate, and nano silica to 15:0.5:5:100, 1,2-epoxy-9-decene and aluminum acetylacetonate were added to the intermediate reaction solution. The system was heated to 90°C and stirred for 4 hours. Then, the system temperature was increased to 100°C, hydroxyethyl methacrylate phosphate was added, and the reaction was continued for 4 hours to obtain the modified reaction solution. S4. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it three times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 20 nm.

[0041] Preparation Example 2 Modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether at 15 times its own weight, control the ultrasonic power at 400W, the ultrasonic frequency at 30kHz, use pulse mode, work for 2s, stop for 1s, and the total processing time is 1.5h to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether at 7 times its own weight to obtain a phenylphosphonic acid mixed solution. S2. Under nitrogen protection, the phenylphosphonic acid mixed solution was added dropwise to the nano silica suspension at a rate of 300 rpm while stirring, and the addition was completed within 30 min. The system was then heated to 80 °C and refluxed for 9 h to obtain the intermediate reaction solution. S3. Controlling the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, hydroxyethyl methacrylate phosphate, and nano silica to 20:0.9:7:100, 1,2-epoxy-9-decene and aluminum acetylacetonate were added to the intermediate reaction solution. The system was heated to 93°C and stirred for 4.5 h. Then, the system temperature was increased to 105°C, hydroxyethyl methacrylate phosphate was added, and the reaction was continued for 4.6 h to obtain the modified reaction solution. S4. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it 4 times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 25 nm.

[0042] Preparation Example 3 Modified nano-silica was prepared by the following method: S1. Disperse nano-silica in propylene glycol methyl ether at 20 times its own weight, control the ultrasonic power at 500W, the ultrasonic frequency at 35kHz, use pulse mode, work for 3s, stop for 2s, and the total processing time is 2h to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether at 10 times its own weight to obtain a phenylphosphonic acid mixed solution. S2. Under nitrogen protection, the phenylphosphonic acid mixed solution was added dropwise to the nano silica suspension at a rate of 400 rpm while stirring, and the addition was completed within 30 min. The system was then heated to 85 °C and refluxed for 10 h to obtain the intermediate reaction solution. S3. Controlling the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, hydroxyethyl methacrylate phosphate, and nano silica to 25:1.5:10:100, 1,2-epoxy-9-decene and aluminum acetylacetonate were added to the intermediate reaction solution. The system was heated to 95°C and stirred for 5 hours. Then, the system temperature was increased to 110°C, hydroxyethyl methacrylate phosphate was added, and the reaction was continued for 5 hours to obtain the modified reaction solution. S4. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it 5 times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 30 nm.

[0043] Comparative Preparation Example 1 Modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether at 10 times its own weight, control the ultrasonic power at 300W, the ultrasonic frequency at 25kHz, use pulse mode, work for 2s, stop for 1s, and the total processing time is 1h to obtain a uniform nano-silica suspension. S2. Controlling the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, hydroxyethyl methacrylate phosphate, and nano silica to 15:0.5:5:100, 1,2-epoxy-9-decene and aluminum acetylacetonate were added to the nano silica suspension. The system was heated to 90°C and stirred for 4 hours. Then, the system temperature was increased to 100°C, hydroxyethyl methacrylate phosphate was added, and the reaction was continued for 4 hours to obtain the modified reaction solution. S3. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it three times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 20 nm.

[0044] Comparative Preparation Example 2 Modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether at 10 times its own weight, control the ultrasonic power at 300W, the ultrasonic frequency at 25kHz, use pulse mode, work for 2s, stop for 1s, and the total processing time is 1h to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether at 5 times its own weight to obtain a phenylphosphonic acid mixed solution. S2. Under nitrogen protection, the phenylphosphonic acid mixed solution was added dropwise to the nano silica suspension at a rate of 200 rpm while stirring, and the addition was completed within 30 min. The system was then heated to 75 °C and refluxed for 8 h to obtain the intermediate reaction solution. S3. Controlling the mass ratio of 1,2-epoxy-9-decene, aluminum acetylacetonate, and nano silica to 15:0.5:100, 1,2-epoxy-9-decene and aluminum acetylacetonate were added to the intermediate reaction solution, the system was heated to 90℃, and the reaction was stirred for 4 hours to obtain the modified reaction solution. S4. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it three times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 20 nm.

[0045] Comparative preparation example 3 Modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether at 10 times its own weight, control the ultrasonic power at 300W, the ultrasonic frequency at 25kHz, use pulse mode, work for 2s, stop for 1s, and the total processing time is 1h to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether at 5 times its own weight to obtain a phenylphosphonic acid mixed solution. S2. Under nitrogen protection, the phenylphosphonic acid mixed solution was added dropwise to the nano silica suspension at a rate of 200 rpm while stirring, and the addition was completed within 30 min. The system was then heated to 75 °C and refluxed for 8 h to obtain the intermediate reaction solution. S3. Control the mass ratio of aluminum acetylacetonate, hydroxyethyl methacrylate phosphate and nano silica to 0.5:5:100, add aluminum acetylacetonate to the intermediate reaction solution, heat the system to 90℃, stir and react for 4h, then raise the system temperature to 100℃, add hydroxyethyl methacrylate phosphate, and continue stirring and reacting for 4h to obtain the modified reaction solution. S4. Cool the modified reaction solution to room temperature, centrifuge at 10,000 rpm for 5 min to separate the solid product, and wash it three times with propylene glycol methyl ether to obtain modified nano silica with a particle size of 20 nm.

[0046] Examples 1-3 provide an environmentally friendly highly methylated resin adhesive and its preparation method.

[0047] Example 1 An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0048] In this process, the modified nano-silica was prepared by Preparation Example 1; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2:1; and the leveling agent was BYK-306.

[0049] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0050] Example 2 An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 70 parts melamine-formaldehyde resin, 10 parts modified nano silica, 18 parts bio-based polyol, 20 parts co-solvent, 7 parts curing agent, 2 parts catalyst, and 1.5 parts leveling agent.

[0051] In this preparation, the modified nano-silica was prepared by Example 2; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 3:1; and the leveling agent was BYK-306.

[0052] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 260 rpm and dissolve at 50°C for 14 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 55℃, and shear and disperse at a rate of 2500 r / min for 45 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 35°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 500 rpm, and mix for 30 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 200 rpm for 15 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0053] Example 3 An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 80 parts melamine-formaldehyde resin, 15 parts modified nano silica, 25 parts bio-based polyol, 30 parts co-solvent, 10 parts curing agent, 3 parts catalyst, and 2 parts leveling agent.

[0054] In this study, the modified nano-silica was prepared by Preparation Example 3; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 4:1; and the leveling agent was BYK-306.

[0055] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 300 rpm and dissolve at 60°C for 10 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 60℃, and shear and disperse at a rate of 3000 r / min for 30 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 40°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 600 rpm, and mix for 20 minutes to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 250 rpm for 10 minutes, then add the curing agent and continue stirring until uniform to obtain an environmentally friendly high methyl etherified resin adhesive.

[0056] To verify the comprehensive performance of the environmentally friendly high-methyl etherified resin adhesive provided by the present invention, comparative examples 1-5 were set up, wherein: Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the modified nano-silica obtained in Preparation Example 1 is replaced with the modified nano-silica obtained in Comparative Preparation Example 1. Specifically: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0057] The modified nano-silica was prepared by Comparative Preparation Example 1; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2:1; and the leveling agent was BYK-306.

[0058] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0059] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the modified nano-silica obtained in Preparation Example 1 is replaced with the modified nano-silica obtained in Comparative Preparation Example 2. Specifically: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0060] The modified nano-silica was prepared by Comparative Preparation Example 2; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2:1; and the leveling agent was BYK-306.

[0061] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0062] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that the modified nano-silica obtained in Preparation Example 1 is replaced with the modified nano-silica obtained in Comparative Preparation Example 3. Specifically: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0063] The modified nano-silica was prepared by Comparative Preparation Example 3; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2:1; and the leveling agent was BYK-306.

[0064] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0065] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that the catalyst is only L-lysine methyl ester hydrochloride. Details are as follows: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0066] In this process, the modified nano-silica was prepared by Preparation Example 1; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was L-lysine methyl ester hydrochloride; and the leveling agent was BYK-306.

[0067] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0068] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that the catalyst used is only zinc acetylacetonate. Details are as follows: An environmentally friendly high-methyl etherified resin adhesive comprises the following raw materials in parts by weight: 60 parts melamine-formaldehyde resin, 5 parts modified nano silica, 10 parts bio-based polyol, 15 parts co-solvent, 5 parts curing agent, 1 part catalyst, and 1 part leveling agent.

[0069] In this process, the modified nano-silica was prepared by Preparation Example 1; the bio-based polyol was castor oil-based polyol; the co-solvent was propylene glycol methyl ether; the curing agent was methyl hexahydrophthalic anhydride; the catalyst was zinc acetylacetone; and the leveling agent was BYK-306.

[0070] An environmentally friendly, highly methylated resin adhesive is prepared by the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Add the bio-based polyol to the co-solvent at a stirring rate of 200 rpm and dissolve at 40°C for 20 min to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50℃, and shear and disperse at a rate of 2000 r / min for 60 min to obtain the modified slurry; Step 4: Cool the modified slurry system to 30°C, add melamine-formaldehyde resin and catalyst at a stirring speed of 400 rpm, and mix for 40 min to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix at a speed of 150 rpm for 20 minutes, then add the curing agent and continue to stir evenly to obtain an environmentally friendly high methyl etherified resin adhesive.

[0071] The comprehensive performance of the environmentally friendly highly methylated resin adhesives prepared in Examples 1-3 and Comparative Examples 1-5 of this invention was tested respectively.

[0072] 1. Free formaldehyde content test Weigh 5.0 g of sample into a 500 mL distillation flask, add 20 mL of ethyl acetate (analytical grade) to dissolve, then add 250 mL of H2O, heat and distill to collect 200 mL of distillate, and dilute to 250 mL. Take 10 mL of distillate into a 25 mL colorimetric tube, add 5 mL of 0.25% acetylacetone solution, dilute to volume with water, shake well, heat in a 100℃ water bath for 3 min, and then cool. Use a spectrophotometer to measure the absorbance at 415 nm wavelength with a 1 cm cuvette. Calculate the free formaldehyde content using the formula X = [(A-A0)×V×f] / (m×1000) (X: free formaldehyde content (g / kg), A: absorbance of the sample solution, A0: absorbance of the blank solution, V: distillate volume, f: dilution factor (1 in this step), m: sample mass).

[0073] 2. Hardness performance test Referring to GB / T 6739-2022 standard, the cured adhesive film was applied to clean glass and conditioned for 16 hours under standard environmental conditions (25℃, 55% relative humidity). During testing, a set of test pencils with known hardness grades (from 6B to 9H), sharpened to straight edges using a standard pencil sharpener, were selected and mounted on a pencil hardness tester with the pencil tip at a 45° angle to the coating surface, and a load of 7.6N was applied. Testing began with a medium-hardness pencil (e.g., 2H), pushing the hardness tester across the coating surface at a uniform speed for approximately 7mm, creating at least three parallel lines with each pencil. The scratches were observed through a magnifying glass. If the coating was not scratched, the test was repeated with a harder pencil of the next grade; if scratched, a softer pencil of the next grade was used. Finally, the highest pencil hardness grade that did not scratch the coating was taken as the surface hardness value of the sample.

[0074] 3. Wear resistance test Referring to GB / T 1768-2006 standard, the cured adhesive sample was fixed on the worktable of the abrasion tester. A CS-10 type grinding wheel was selected, and a load of 500g was applied. The instrument was started, and the friction wheel reciprocated against the sample surface at a fixed speed and stroke. The total number of cycles was set to 500. After the test, the sample was removed, and the mass of the sample before and after friction was accurately weighed using an analytical balance. The mass loss (unit: mg) was calculated. The smaller the mass loss, the better the abrasion resistance of the sample. Three parallel tests were conducted, and the average value was taken as the final result.

[0075] 4. Adhesion performance test Referring to GB / T 9286-2021 standard, use a single-blade scribing tool to cut six parallel cuts with a spacing of 2mm on the coating surface, and then make six more perpendicular cuts to form 25 squares with an area of ​​4mm². Use a soft brush to gently brush along the diagonal of the grid five times to remove debris. Apply pressure-sensitive adhesive tape (3M 610) with an adhesion strength ≥3.5N / cm tightly to the grid, ensuring no air bubbles. After standing for 90 seconds, peel off the tape quickly and smoothly at a 180° angle to the coating surface. Immediately inspect the coating peeling in the square areas under sufficient light using a magnifying glass, and judge according to the standard grading chart (0-5 levels), where level 0 is no peeling and level 5 is severe peeling.

[0076] 5. Impact resistance test Referring to GB / T 1732-2020 standard, the cured adhesive sample with the paint film facing upwards was placed horizontally on the anvil of the impactor. By adjusting the height of the hammer, the hammer (mass 1kg, punch diameter 20mm) was dropped freely from a height of 50cm, applying an impact energy of 5J to the sample. Immediately after the impact, the sample was removed and the paint film surface was observed under sufficient light using a 4x magnifying glass. The results were recorded to check whether cracking or peeling occurred in the impact deformation area.

[0077] 6. Storage Stability Refer to the GB / T 14074-2017 standard. Seal the prepared adhesive in a clean polyethylene plastic bottle and place it in a constant temperature oven at 50 °C for accelerated aging. Take it out after 0 day, 7 days, 14 days, and 30 days respectively, and let it cool naturally to 25 °C. Observe whether there is stratification, skin formation, and color change in its appearance, and use a rotational viscometer to measure the viscosity change, and record the change rate of viscosity. If after 30 days of accelerated aging, the sample appearance is uniform, without gel, and the viscosity change rate ≤ 20%, it is determined that its storage stability is qualified.

[0078] The test results are shown in Table 1-2.

[0079] Table 1: Test data of free formaldehyde content, hardness performance, abrasion resistance performance, adhesion performance, and impact resistance performance of environmentally friendly highly methylated resin adhesive Table 2: Test data of storage stability performance of environmentally friendly highly methylated resin adhesive It can be seen from the results shown in Table 1 and Table 2 that: the environmentally friendly highly methylated resin adhesives prepared in Examples 1-3 of the present invention all show low free formaldehyde content, excellent hardness (≥ 5H), excellent abrasion resistance (mass loss ≤ 30 mg), excellent adhesion (grade 0), and good impact resistance. At the same time, after 30 days of accelerated aging at 50 °C, the sample appearance is stable and the viscosity change rate is extremely small, demonstrating excellent storage stability.

[0080] It can be seen from the comparison between Example 1 and Comparative Examples 1, 2, and 3 that: in Comparative Example 1, phenylphosphonic acid was not used, resulting in serious agglomeration of nanoparticles and the worst performance in all aspects; in Comparative Example 2, hydroxyethyl methacrylate phosphate was missing, making it impossible for nanoparticles to form effective chemical bonding with the resin, and the enhancement effect was greatly weakened; in Comparative Example 3, 1,2-epoxy-9-decene was missing, resulting in insufficient toughness of the system and significantly poor impact resistance.

[0081] It can be seen from the comparison between Example 1 and Comparative Examples 4 and 5 that: the compound catalyst of L-lysine methyl ester hydrochloride and zinc acetylacetonate is the key to achieving high performance and high stability of the product. In Comparative Example 4, only L-lysine methyl ester hydrochloride was used, although it could also catalyze, but the storage stability was extremely poor and it would gel quickly; in Comparative Example 5, only zinc acetylacetonate was used, and the curing was incomplete, resulting in poor performance such as hardness and abrasion resistance.

[0082] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. An environmentally friendly, highly methylated resin adhesive, characterized in that, The raw materials include the following parts by weight: 60-80 parts of melamine-formaldehyde resin, 5-15 parts of modified nano-silica, 10-25 parts of bio-based polyol, 15-30 parts of co-solvent, 5-10 parts of curing agent, 1-3 parts of catalyst, and 1-2 parts of leveling agent.

2. The environmentally friendly high-methyl etherified resin adhesive according to claim 1, characterized in that, The melamine-formaldehyde resin has a solids content of ≥98% and a free formaldehyde content of ≤0.2%.

3. The environmentally friendly highly methylated resin adhesive according to claim 1, characterized in that, The modified nano-silica is nano-silica with a particle size of 10-50 nm, which has been surface-modified by an organic modifier.

4. The environmentally friendly highly methylated resin adhesive according to claim 3, characterized in that, The modified nano-silica is prepared by the following steps: S1. Disperse nano-silica in propylene glycol methyl ether and sonicate to obtain a uniform nano-silica suspension; dissolve phenylphosphonic acid in propylene glycol methyl ether to obtain a phenylphosphonic acid mixed solution; S2. Under nitrogen protection, the phenylphosphonic acid mixed solution is added dropwise to the nano silica suspension while stirring, and the addition is completed within 30 minutes. The system is heated to 75-85℃ and refluxed for 8-10 hours to obtain the intermediate reaction solution. S3. Add 1,2-epoxy-9-decene and aluminum acetylacetonate to the intermediate reaction solution, heat the system to 90-95℃, stir the reaction for 4-5 hours, then raise the system temperature to 100-110℃, add hydroxyethyl methacrylate phosphate, and continue stirring the reaction for 4-5 hours to obtain the modified reaction solution. S4. Cool the modified reaction solution, centrifuge, and wash with propylene glycol methyl ether 3-5 times to obtain modified nano-silica.

5. The environmentally friendly highly methylated resin adhesive according to claim 4, characterized in that, The ultrasonic processing in step S1 specifically involves controlling the ultrasonic power to be 300-500W, the ultrasonic frequency to be 25-35kHz, using pulse mode, working for 2-3 seconds, stopping for 1-2 seconds, and the total processing time to be 1-2 hours.

6. The environmentally friendly highly methylated resin adhesive according to claim 1, characterized in that, The bio-based polyol is one or more of castor oil-based polyol, cashew phenol-based polyol, and soybean oil-based polyol.

7. The environmentally friendly highly methylated resin adhesive according to claim 1, characterized in that, The co-solvent is an alcohol ether solvent.

8. The environmentally friendly high-methyl etherified resin adhesive according to claim 1, characterized in that, The catalyst is a mixture of L-lysine methyl ester hydrochloride and zinc acetylacetone.

9. The environmentally friendly highly methylated resin adhesive according to claim 8, characterized in that, The catalyst is L-lysine methyl ester hydrochloride and zinc acetylacetone in a mass ratio of 2-4:

1.

10. A method for preparing an environmentally friendly highly methylated resin adhesive according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Weigh out the following ingredients by weight: melamine-formaldehyde resin, modified nano-silica, bio-based polyol, co-solvent, curing agent, catalyst, and leveling agent. Step 2: Under stirring conditions, add the bio-based polyol to the co-solvent and dissolve it at 40-60℃ for 10-20 minutes to obtain a polyol premix. Step 3: Add the modified nano-silica to the polyol premix, raise the system temperature to 50-60℃, disperse for 30-60 min, and obtain the modified slurry; Step 4: Cool the modified slurry system to 30-40℃, add melamine-formaldehyde resin and catalyst while stirring, and mix for 20-40 minutes to obtain a mixed resin solution. Step 5: Add the leveling agent to the mixed resin liquid, stir and mix for 10-20 minutes, then add the curing agent and continue stirring until uniform to obtain an environmentally friendly high-methyl etherified resin adhesive.

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