A self-crosslinking waterborne cardanol-based resin and a preparation method thereof

Abstract

The present application relates to a kind of self-crosslinking water-based cardanol-based resin and its preparation method. Specifically, a kind of self-crosslinking water-based cardanol-based resin is disclosed, including the following components: cardanol-based monomer, styrene, acrylate monomer, first self-crosslinking monomer, methyl methacrylate monomer, second self-crosslinking monomer, first solvent, neutralizing agent, initiator, curing agent and water. The film obtained by baking the resin has excellent hardness, adhesion and chemical resistance, etc. The present application also discloses the preparation method and application of the resin.

Description

Technical Field

[0001] This invention relates to the field of waterborne cashew phenolic resin technology, and more specifically to a self-crosslinking waterborne cashew phenolic resin and its preparation method. Background Technology

[0002] With increasingly stringent environmental regulations, waterborne resins have been widely used as alternatives to solvent-based resins. However, traditional waterborne resins (such as pure acrylic and styrene-acrylic emulsions) often fall short of solvent-based resins in terms of hardness, water resistance, chemical resistance, and drying speed. To improve performance, crosslinking technology is often introduced, but most of these require the addition of external crosslinking agents, resulting in problems such as short pot life and inconvenient application.

[0003] Cashew nut shell phenol (CNP), a widely available and inexpensive renewable bio-based raw material, possesses a benzene ring structure that imparts good hardness, hydrophobicity, and heat resistance to resins. Introducing CNP into waterborne resin systems is an effective way to improve performance and achieve environmental friendliness. However, CNP has low reactivity, making direct copolymerization difficult, and its long-chain alkanes may negatively impact the drying speed and hardness of the resin.

[0004] Therefore, developing a waterborne resin that can effectively introduce cashew phenols, has high self-crosslinking ability, fast drying speed and adjustable performance has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a self-crosslinking waterborne cashew phenolic resin and its preparation method.

[0006] In a first aspect, the present invention provides a self-crosslinking aqueous cashew nut resin, said resin being formed by reacting the following components: The remainder is water.

[0007] In another preferred embodiment, the structural formula of the cashew phenol monomer is as follows: Where n is selected from the following group: 0, 1, 2, 3.

[0008] In another preferred embodiment, the cashew phenol monomer is prepared as follows: a1) Cashew nut phenol and ethyl acrylate isocyanate are reacted to obtain the cashew nut phenol monomer.

[0009] In another preferred embodiment, n in the cashew phenol is selected from the group consisting of 0, 1, 2, and 3.

[0010] In another preferred embodiment, in step a1), the reaction is carried out in a dry reaction vessel.

[0011] In another preferred embodiment, in step a1), the reaction is carried out at 50-85°C, preferably 60-80°C.

[0012] In another preferred embodiment, in step a1), the reaction is carried out under nitrogen protection.

[0013] In another preferred embodiment, in step a1), the molar ratio of cashew nut shell powder to ethyl acrylate isocyanate is 1:0.8-1.2, more preferably 1:0.9-1.1.

[0014] In another preferred embodiment, in step a1), the reaction time is 1-10 hours, more preferably 2-6 hours, and even more preferably 2-4 hours.

[0015] In another preferred embodiment, the acrylate monomer is selected from the group consisting of acrylic acid, butyl acrylate, isobornyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, or combinations thereof.

[0016] In another preferred embodiment, the first self-crosslinking monomer is selected from the group consisting of diacetone acrylamide, ethyl acetoacetate, ethyl acetoacetate methacrylate, ethylene glycol acetoacetate methacrylate, or combinations thereof.

[0017] In another preferred embodiment, the methacrylate monomer is selected from the group consisting of methyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, isobutyl methacrylate, methacrylic acid, butyl methacrylate, or combinations thereof.

[0018] In another preferred embodiment, the second self-crosslinking monomer is selected from the group consisting of: , , , .

[0019] In another preferred embodiment, the second self-crosslinking monomer is prepared as follows: b1) The ethyl acrylate isocyanate and the blocking agent are reacted to obtain the second self-crosslinking monomer.

[0020] In another preferred embodiment, in step b1), the reaction is carried out in a dry reaction vessel.

[0021] In another preferred embodiment, in step b1), the reaction is carried out at 50-85°C, preferably 60-80°C.

[0022] In another preferred embodiment, in step b1), the reaction is carried out under nitrogen protection.

[0023] In another preferred embodiment, in step b1), the molar ratio of ethyl acrylate isocyanate to the blocking agent is 1:1-1.1.

[0024] In another preferred embodiment, in step b1), the reaction time is 2-8 hours, more preferably 4-7 hours, and even more preferably 5-6 hours.

[0025] In another preferred embodiment, the blocking agent is selected from the group consisting of methyl ethyl ketone oxime (MEKO), n-butanol, ethylene glycol butyl ether, 3,5-dimethylpyrazole (DMP), or combinations thereof.

[0026] In another preferred embodiment, the first solvent is selected from the group consisting of propylene glycol methyl ether, acetone, butanone, methyl pentyl ketone, isobutanol, or combinations thereof.

[0027] In another preferred embodiment, the neutralizing agent is selected from the group consisting of dimethylethanolamine, 1-dimethylamino-2-propanol, triethylamine, ammonia, or combinations thereof.

[0028] In another preferred embodiment, the initiator is selected from the group consisting of azobisisobutyronitrile, benzoyl peroxide, tert-butyl peracetate, t-butyl peroxide-2-ethylhexanoate, azobisisoheptanenitrile, or combinations thereof.

[0029] In another preferred embodiment, the curing agent is ADH.

[0030] In another preferred embodiment, the resin has one or more characteristics selected from the group consisting of: 1) The resin is a milky white aqueous dispersion; 2) The particle size of the resin is 80-350nm, preferably 90-300nm, and more preferably 100-280nm; 3) The resin has a solid content of 25-60 wt%, preferably 30-50 wt%, and more preferably 35-45 wt%.

[0031] A second aspect of the present invention provides a method for preparing the self-crosslinking aqueous cashew phenolic resin described in the first aspect of the present invention, comprising the following steps: 1) Provide a first mixture, a second mixture, a first solvent, a neutralizing agent, a curing agent, and water; The first mixture comprises the following components: cashew nut phenol monomer, styrene, acrylate monomer, first self-crosslinking monomer, methacrylate monomer, second self-crosslinking monomer and first solvent; The second mixture comprises the following components: an initiator and a first solvent; 2) In a reaction vessel, add the first solvent, 5-20 wt% (preferably 6-15 wt%, more preferably 8-12 wt%) of the first mixture and 2-10 wt% (preferably 4-8 wt%, more preferably 5-7 wt%) of the second mixture to obtain mixture A; 3) Heat the mixture A to a first temperature, and continue to add the remaining 80-95 wt% of the first mixture and 90-98 wt% of the second mixture, and keep the temperature for a first time to obtain mixture B; 4) Cool the mixture B to a second temperature, add the neutralizing agent, and stir to obtain mixture C; 5) Add water to the mixture C to obtain mixture D, and stir at a third temperature for a second time to obtain mixture E; 6) Heat the mixture E to a fourth temperature, vacuum treat for a third time, cool to a fifth temperature, add a curing agent, adjust the solid content with the neutralizing agent and water, stir evenly, and obtain the self-crosslinking waterborne cashew phenolic resin.

[0032] In another preferred embodiment, the first temperature is 60-100°C, more preferably 70-90°C, and even more preferably 75-85°C.

[0033] In another preferred embodiment, the first time is 0.5-5h, more preferably 0.8-3h, and even more preferably 1-2h.

[0034] In another preferred embodiment, the second temperature is 40-80°C, more preferably 50-70°C, and even more preferably 55-65°C.

[0035] In another preferred embodiment, in step 4), the stirring time is 5-60 min, more preferably 10-30 min, and even more preferably 10-20 min.

[0036] In another preferred embodiment, the third temperature is 20-60°C, more preferably 30-50°C, and even more preferably 35-45°C.

[0037] In another preferred embodiment, the second time is 0.5-5h, more preferably 0.8-3h, and even more preferably 0.8-1.5h.

[0038] In another preferred embodiment, the fourth temperature is 80-120°C, more preferably 90-110°C, and even more preferably 92-100°C.

[0039] In another preferred embodiment, the third time is 4-12 hours, more preferably 6-10 hours, and even more preferably 8-9 hours.

[0040] In another preferred embodiment, the fifth temperature is 20-60°C, more preferably 30-50°C, and even more preferably 35-45°C.

[0041] In a third aspect, the present invention provides a membrane prepared using the self-crosslinking aqueous cashew phenolic resin described in the first aspect of the present invention.

[0042] In another preferred embodiment, the membrane is prepared as follows: 1) After the resin is evenly coated onto the tinplate, it is baked in an oven to allow the solvent to evaporate and the coating to cure into a film.

[0043] In another preferred embodiment, the baking temperature is 120-160°C, more preferably 130-150°C.

[0044] In another preferred embodiment, the baking time is 10-60 minutes, more preferably 15-30 minutes.

[0045] In another preferred embodiment, the membrane has one or more features selected from the group consisting of: 1) The thickness of the membrane is 10-30 micrometers; 2) The pencil hardness of the membrane is B-2H, preferably HB-H; 3) The adhesion of the membrane is grade 0-1; 4) The membrane is resistant to ethanol wiping cycles of 800-2000 times, preferably 1000-1500 times; 5) The membrane has a resistance to salt water (3%) immersion without change for 200-500 hours, preferably 230-400 hours.

[0046] In a fourth aspect, the present invention provides a product comprising or made from the self-crosslinking aqueous cashew phenolic resin described in the first aspect of the present invention.

[0047] In another preferred embodiment, the product is selected from the group consisting of: coatings and inks.

[0048] The beneficial effects of this invention are as follows: By introducing cashew nut shell groups through chemical bonding, this invention not only reduces reliance on petroleum-based raw materials, meeting green and environmental protection requirements, but also, through the synergistic effect of the rigid benzene ring structure and flexible alkyl long chains of the cashew nut shell groups, endows the resin with high hardness, excellent toughness, high adhesion, and hydrophobicity. Furthermore, this invention designs a dual self-crosslinking mechanism. The first self-crosslinking monomer can slowly crosslink at room temperature, rapidly improving the initial surface drying and mechanical properties of the resin. The second self-crosslinking monomer can unblock and release NCO during heating and baking. The released NCO groups can react with hydroxyl and amino groups on the polymer chain to achieve self-crosslinking, forming a dense network structure, further improving resin performance and solving the technical problem that waterborne resins are inferior to solvent-based resins in terms of hardness, water resistance, chemical resistance, and drying speed.

[0049] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Detailed Implementation

[0050] Through long-term and in-depth research, the inventors unexpectedly prepared a self-crosslinking waterborne cashew nut resin with excellent hardness, adhesion, and chemical resistance. Based on this, the inventors completed this invention.

[0051] The meanings of the English abbreviations used in this invention are as follows: DAAM: Diacetone Acrylamide, structural formula is .

[0052] AAEM: Ethyl acetoacetate methacrylate, structural formula is .

[0053] ADH: Adipate dihydrazide, structural formula is... .

[0054] MEKO: Methyl ethyl ketone oxime, structural formula is... .

[0055] DMP: 3,5-dimethylpyrazole, structural formula is... .

[0056] Compared with the prior art, the present invention has the following main advantages: (1) High bio-based content: 2-25 wt% cashew phenol is introduced through chemical bonding, which reduces the dependence on petroleum-based raw materials and is green and environmentally friendly.

[0057] (2) Dual self-crosslinking mechanism: • Room temperature crosslinking: The first self-crosslinking monomer (such as DAAM) can undergo slow room temperature crosslinking with the added ADH during the film formation process, improving the initial performance.

[0058] • High-temperature crosslinking: The second self-crosslinking monomer is desealed during baking (e.g., >130°C), generating a rapid NCO crosslinking reaction, which greatly improves the final properties of the coating (hardness, chemical resistance).

[0059] • Adjustable crosslinking: By adjusting the types and ratios of the two self-crosslinking monomers, the drying curve and final properties of the resin can be flexibly designed to adapt to different application scenarios.

[0060] (3) Excellent performance: The rigid benzene ring and long flexible alkyl chain of cashew phenol work together to give the resin high hardness, high adhesion, excellent toughness and hydrophobicity.

[0061] (4) Stable process: The method of solution polymerization followed by phase inversion is adopted, and the resulting dispersion has a uniform particle size (80-350nm) and good storage stability.

[0062] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are by weight.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0064] General testing methods Particle size Using a laser particle size analyzer (Zetasizer Nano ZS model) from Malvern Instruments AG, a drop of sample was placed in the sample cell, diluted with deionized water to the graduation mark, and the particle size was measured at 25°C.

[0065] Solid content ISO 3251 (1) Set the oven temperature (110℃). (2) Zero the balance, weigh the first weighing box, and record the corresponding data m0. After zeroing, add approximately 1g of sample, and use a paperclip to spread the sample thoroughly into a thin layer in the aluminum foil dish. Record the actual weight m1 in the aluminum foil dish. (3) Repeat step 3 to weigh the second and third weighing boxes and make three parallel samples; (4) Place the sample in an oven that has been heated to the test temperature and dry for 1 hour; (5) After the drying time is over, remove the weighing box and cool it to room temperature in the desiccator; (6) Zero the balance, weigh each weighing box in turn and record the data m2.

[0066] Calculation and Result Representation NV=(m2-m0) / (m1-m0)% In the formula: NV --- Solid content, % m2 --- Weight of the weighing box after drying + sample, in grams m1 --- Sample weight, g m0 --- Weight of the weighing box, in grams Pencil hardness The pencil hardness tester is manufactured according to the manual operation method in Clause 2.3 of the national standard GB 6739-86 "Coating Hardness - Pencil Hardness Method". It belongs to the category of scratch hardness testing instruments and is a simple and quick method for testing the hardness of coatings. The hardness of pencil lead is divided into 13 levels. From the hardest 6H, the levels decrease progressively: 5H, 4H, 3H, 2H, H, then the moderately hard HB, and finally B, 2B, and the softest 6B. Here, H represents hardness, and B represents blackness. From 6H to 6B, the hardness decreases, and the pencil color becomes progressively darker.

[0067] Adhesion The cross-cut test is a simple and easy method for evaluating the adhesion of single or multiple coatings.

[0068] Operating steps: - Use a BYK-Gardner cross-cut tester to cut a cross pattern on the coating, with the cut extending to the substrate. - Brush five times along each diagonal direction with a brush, then apply tape to the cut and pull it off. The cut edges are completely smooth, and there is no peeling at the edges of the grid, which is grade 0.

[0069] There are small pieces peeling off at the intersection of the cuts, and the actual damage within the gridded area does not exceed 5%, which is classified as Level 1.

[0070] The edges and / or intersections of the incision are peeled off, with an area greater than 5% but less than 15%, which is classified as Grade 2.

[0071] The cut edge has partial or large-scale peeling, and / or some grids are peeled off in whole pieces, with the peeled area exceeding 15% but less than 35%, which is classified as Level 3.

[0072] Large areas of the cut edge are peeled off and / or some squares are partially or completely peeled off, with the area being greater than 35% but not exceeding 65% of the grid area, which is classified as Level 4.

[0073] Any degree of peeling that cannot be measured by even a Level 4 standard is classified as Level 5.

[0074] Ethanol-resistant wipe GB / T 1768-2006: A rotary abrasion tester is used to rub the coating surface with an alcohol-soaked grinding head. The standard speed is 60 rpm and the load is 500 g.

[0075] Salt water (3%) immersion resistant Salt water resistance refers to a material's ability to resist salt water corrosion. This property is usually determined according to GB / T 10834-2008 "Determination of Salt Water Resistance of Marine Paints - Salt Water and Hot Salt Water Immersion Method". The coated test panel is immersed in salt water at a specified temperature, and after a specified time, the paint film is checked for phenomena such as loss of gloss, discoloration, rusting, blistering, peeling, or cracking.

[0076] Monomer pre-synthesis: a. Synthesis of cashew nut phenol monomer: Cashew nut phenol was added to a dry reaction vessel and heated to 60-85°C. Under nitrogen protection, a measured amount of ethyl acrylate isocyanate was slowly added dropwise (the molar ratio of cashew nut phenol to ethyl acrylate isocyanate was 1:0.95-1.05). After the addition was complete, the reaction was maintained at this temperature for 2-4 hours. The disappearance of the NCO peak was monitored by FT-IR to obtain the cashew nut phenol monomer. Cashew phenol ethyl acrylate isocyanate cashew phenol monomer Where n is 0-3.

[0077] b. Synthesis of the second self-crosslinking monomer: Ethyl acrylate isocyanate was added to a dry reaction vessel, and the temperature was raised to 60-80°C. Under nitrogen protection, a measured amount of blocking agent (the molar ratio of ethyl acrylate isocyanate to blocking agent was 1:1) was slowly added dropwise. After the addition was complete, the reaction was maintained at this temperature until the FT-IR spectrum reached 2270 cm⁻¹. -1 The NCO characteristic peak at the point completely disappeared, yielding the second self-crosslinking monomer.

[0078] General methods for resin film formation After the resin is evenly coated onto the tinplate, it is baked in an oven to allow the solvent to evaporate and the coating to cure into a film. Refer to the example for specific baking temperature and time.

[0079] After film formation, the first self-crosslinking monomer and the curing agent undergo a crosslinking reaction: Ketohydrazine crosslinking reaction The second self-crosslinking monomer is desealed when heated (e.g., >130°C), and the released NCO groups can react with hydroxyl, amino, and other groups on the polymer chain to achieve self-crosslinking.

[0080] Preparation example: Preparation of cashew phenol monomer: Weigh 304 g of cashew phenol (n=0) and add it to a dry four-necked flask. Heat the flask to 70°C and add 141 g of ethyl acrylate isocyanate dropwise to the reaction vessel. Stir and keep warm for 1 hour, taking samples every hour and testing the infrared spectrum until the characteristic peak of NCO disappears. Stop the heating to obtain the cashew phenol monomer.

[0081] Preparation of the second self-crosslinking monomer: Weigh 87 g of methyl ethyl ketone oxime and add it to a dry four-necked flask. Heat the flask to 80°C and add 141 g of ethyl acrylate isocyanate dropwise to the reaction vessel. Stir and keep warm for 1 hour, taking samples every hour and testing the infrared spectrum until the characteristic peak of NCO disappears. Stop the heating to obtain MEKO-blocked ethyl acrylate isocyanate of the second self-crosslinking monomer.

[0082] The preparation of the corresponding second self-crosslinking monomer was carried out by replacing methyl ethyl ketone oxime with equimolar amounts of n-butanol, ethylene glycol butyl ether, 3,5-dimethylpyrazole, etc.

[0083] The structures of the second self-crosslinking monomers prepared by each blocking agent are as follows: It should be understood that the cashew phenol monomer and the second self-crosslinking monomer used in the following embodiments and comparative examples of the present invention are the products obtained in the preparation examples above.

[0084] Example 1 Resin 1 (fast-drying waterborne self-crosslinking cashew phenolic resin) Add 40g of methyl amyl ketone, 20g of cashew nut shell monomer, 95g of styrene, 50g of methyl methacrylate, 50g of hydroxyethyl acrylate, 30g of acrylic acid, 30g of diacetone acrylamide, and 50g of MEKO-blocked ethyl acrylate isocyanate sequentially to a dropping vessel and stir until homogeneous. Add 25g of t-butylperoxide-2-ethylhexanoate and 50g of methyl amyl ketone to an initiator bottle and stir until homogeneous. Add 150g of methylpentyl ketone to a four-necked flask, then add 9% of the monomer mixture and 5g of the initiator solution. Heat to 80°C, and simultaneously add the monomer and initiator dropwise. The monomer takes 120 minutes, and the initiator takes 130 minutes. After the addition is complete, continue to heat for 1 hour, then cool to 60°C. Add 16g of dimethylethanolamine and continue stirring for 15 minutes. Add 300g of deionized water, maintain the temperature at 40°C, and stir for 1 hour. Then raise the temperature to 94°C and evaporate the methylpentyl ketone under vacuum. Cool to 40°C, add 25g of ADH, and stir until homogeneous. Adjust the solid content to 35% using dimethylethanolamine and deionized water.

[0085] The resulting resin has a particle size of approximately 100 nm and a solid content of 35 wt%. After baking at 140°C for 20 min to form a film (film thickness of 18 micrometers), it has a pencil hardness of H, an adhesion grade of 0, and can withstand ethanol wiping for >1000 times. It also shows no change after soaking in 3% salt water for 240 h.

[0086] Example 2 Resin 2 (Waterborne self-crosslinking cashew nut resin with hardness focus) Add 40g of methyl pentyl ketone, 70g of cashew nut shell monomer, 45g of styrene, 50g of isobornyl methacrylate, 50g of hydroxyethyl acrylate, 45g of acrylic acid, 30g of ethylene glycol acetoacetate methacrylate, and 50g of DMP-blocked ethyl acrylate isocyanate sequentially to a dropping vessel and stir until homogeneous. Add 25g of t-butylperoxide-2-ethylhexanoate and 50g of methyl pentyl ketone to an initiator bottle and stir until homogeneous. Add 150g of methylpentyl ketone to a four-necked flask, then add 9% of the monomer mixture and 5g of the initiator solution. Heat to 80°C, and simultaneously add the monomer and initiator dropwise. The monomer takes 120 minutes, and the initiator takes 130 minutes. After the addition is complete, continue to heat for 1 hour, then cool to 60°C. Add 18g of dimethylethanolamine and continue stirring for 15 minutes. Add 300g of deionized water, maintain the temperature at 40°C, and stir for 1 hour. Then raise the temperature to 94°C and evaporate the methylpentyl ketone under vacuum. Cool to 40°C, add 25g of ADH, and stir until homogeneous. Adjust the solid content to 35% using dimethylethanolamine and deionized water.

[0087] The resulting resin 2 has a particle size of approximately 280 nm and a solid content of 35 wt%. After baking at 140°C for 20 min to form a film (film thickness of 17 micrometers), the following properties were observed: pencil hardness of HB, adhesion grade 0, and no change after immersion in 3% salt water for 240 h.

[0088] Comparative Example 1 Resin C1 Add 40g of methyl amyl ketone, 115g of styrene, 50g of methyl methacrylate, 50g of hydroxyethyl acrylate, 45g of acrylic acid, 30g of ethylene glycol acetoacetate methacrylate, and 50g of butyl acrylate sequentially to a dropping vessel and stir until homogeneous. Add 25g of t-butylperoxide-2-ethylhexanoate and 50g of methyl amyl ketone to an initiator bottle and stir until homogeneous. Add 150g of methylpentyl ketone to a four-necked flask, then add 9% of the monomer mixture and 5g of the initiator solution. Heat to 80°C, and simultaneously add the monomer and initiator dropwise. The monomer takes 120 minutes, and the initiator takes 130 minutes. After the addition is complete, continue to heat for 1 hour, then cool to 60°C. Add 18g of dimethylethanolamine and continue stirring for 15 minutes. Add 300g of deionized water, maintain the temperature at 40°C, and stir for 1 hour. Then raise the temperature to 94°C and evaporate the methylpentyl ketone under vacuum. Cool to 40°C, add 25g of ADH, and stir until homogeneous. Adjust the solid content to 35% using dimethylethanolamine and deionized water.

[0089] The resulting resin C1 has a particle size of approximately 290 nm and a solid content of 35 wt%. After drying at 140°C for 1 hour to form a film (film thickness of 20 micrometers), the following properties are observed: pencil hardness 2B, adhesion grade 2, and resistance to bubbling after soaking in 3% salt water for 240 hours.

[0090] Performance comparison: After the comparative resin film was formed, its hardness, adhesion and salt water immersion resistance were significantly lower than those of Examples 1 and 2, proving that the introduction of cashew phenol monomer and double self-crosslinking structure is crucial to the performance improvement.

[0091] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A self-crosslinking waterborne cashew phenolic resin, characterized in that, The resin is formed by reacting the following components: The remainder is water.

2. The resin as described in claim 1, characterized in that, The structural formula of the cashew phenol monomer is as follows: Where n is selected from the following group: 0, 1, 2, 3.

3. The resin as described in claim 1, characterized in that, The acrylate monomers are selected from the group consisting of: acrylic acid, butyl acrylate, isobornyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, or combinations thereof.

4. The resin as described in claim 1, characterized in that, The first self-crosslinking monomer is selected from the group consisting of: diacetone acrylamide, ethyl acetoacetate, ethyl acetoacetate methacrylate, ethylene glycol acetoacetate methacrylate, or combinations thereof.

5. The resin as described in claim 1, characterized in that, The methacrylate monomers are selected from the group consisting of: methyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, isobutyl methacrylate, methacrylic acid, butyl methacrylate, or combinations thereof.

6. The resin as described in claim 1, characterized in that, The second self-crosslinking monomer is selected from the group consisting of: , , , .

7. The resin according to claim 1, characterized in that, The neutralizing agent is selected from the group consisting of: dimethylethanolamine, 1-dimethylamino-2-propanol, triethylamine, ammonia, or combinations thereof.

8. A method for preparing the self-crosslinking aqueous cashew phenolic resin according to claim 1, characterized in that, Includes the following steps: 1) Provide a first mixture, a second mixture, a first solvent, a neutralizing agent, a curing agent, and water; The first mixture comprises the following components: cashew nut phenol monomer, styrene, acrylate monomer, first self-crosslinking monomer, methacrylate monomer, second self-crosslinking monomer and first solvent; The second mixture comprises the following components: an initiator and a first solvent; 2) In a reaction vessel, add the first solvent, 5-20 wt% of the first mixture and 2-10 wt% of the second mixture to obtain mixture A; 3) Heat the mixture A to a first temperature, and continue to add the remaining 80-95 wt% of the first mixture and 90-98 wt% of the second mixture, and keep the temperature for a first time to obtain mixture B; 4) Cool the mixture B to a second temperature, add the neutralizing agent, and stir to obtain mixture C; 5) Add water to the mixture C to obtain mixture D, and stir at a third temperature for a second time to obtain mixture E; 6) Heat the mixture E to a fourth temperature, vacuum treat for a third time, cool to a fifth temperature, add a curing agent, adjust the solid content with the neutralizing agent and water, stir evenly, and obtain the self-crosslinking waterborne cashew phenolic resin.

9. A membrane, characterized in that, The membrane is prepared using the self-crosslinking aqueous cashew phenolic resin described in claim 1.

10. A product characterized in that, The product comprises the self-crosslinking waterborne cashew phenolic resin of claim 1 or is made from the self-crosslinking waterborne cashew phenolic resin of claim 1.

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