Hybrid silicon-epoxy copolymer modified waterborne acrylic resin and preparation method thereof

Abstract

The invention relates to the technical field of acrylic resins, and discloses a hybrid silicon-epoxy copolymer modified water-based acrylic resin and a preparation method thereof. The hybrid silicon-epoxy copolymer of the invention contains epoxy groups, and under the action of a cross-linking agent 4,4-diaminodiphenylmethane or 4,4-diaminodiphenyl sulfone, can undergo a cross-linking reaction with the epoxy groups of a water-based acrylic resin molecular chain. The hybrid silicon-epoxy copolymer contains DOPO, cyanurate and siloxane structures to form a nitrogen-phosphorus-silicon flame retardant system, which promotes the combustion of acrylic resin into carbon. At the same time, the siloxane structure undergoes pyrolysis, and silicon dioxide particles are generated in a carbon layer to form a continuous barrier layer, which inhibits the combustion process, reduces the peak value of the heat release rate and the total heat release, and has excellent flame retardant properties. At the same time, the water resistance and salt spray resistance of the resin are improved.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic resins, in particular to a hybrid silicon-epoxy copolymer modified waterborne acrylic resin and a preparation method thereof. Background Art

[0002] Water-based acrylic resin has the advantages of being green and environmentally friendly, film-forming, and having good gloss and high hardness. It has important applications in furniture, electrical appliances, and automobile manufacturing. Currently, the preparation of water-based acrylic resin mainly includes emulsion polymerization, suspension polymerization, and bulk polymerization. The preparation methods are very diverse. However, water-based acrylic resin has poor water resistance and no flame retardant properties, which hinders the practical application of water-based acrylic resin.

[0003] Silicone polymers are functional materials with excellent waterproof, anti-corrosion, high temperature resistance, flame retardant and other properties, and have broad application prospects in polymer materials such as acrylic resins. Patent CN113372799B discloses that hydroxy acrylic resins, hydroxyl-terminated silicone resins, wear-resistant resins, silicone polymers, etc. are used as excellent materials to prepare water-based two-component anti-slip coatings with good hardness, weather resistance, scratch resistance and other properties; however, the patent does not improve the flame retardant properties of acrylic resins. Summary of the invention

[0004] Technical problems solved: A hybrid silicon-epoxy copolymer modified water-based acrylic resin is provided to solve the problems of poor flame retardancy and poor water resistance of water-based acrylic resin.

[0005] Technical solution:

[0006] The preparation method of hybrid silicon-epoxy copolymer modified waterborne acrylic resin comprises the following steps:

[0007] Step (1), adding xylene, N,N-dimethylformamide, N,N-dimethylacetamide, any one of the reaction solvents, dihydroxypropyl-diepoxypropyl isocyanurate, diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 4,4'-methylenebis(phenyl isocyanate) into a reaction container, and performing a polymerization reaction at a temperature of 75-90° C. in a nitrogen atmosphere for 3-7 hours, adding methanol to the solution for precipitation after cooling, filtering, and washing with ethanol to obtain a hybrid silicon-epoxy copolymer.

[0008] Among them, the structural formula of dihydroxypropyl-diepoxypropyl isocyanurate is:

[0009]

[0010] Step (2), adding water, acrylic acid and its derivatives, and an emulsifier into a reaction container, stirring and heating to 70-80° C., adding an initiator aqueous solution, reacting for 1-2 hours, then adding acrylic acid and its derivatives and an initiator aqueous solution, reacting for 2-3 hours, cooling, adding a neutralizer for neutralization, and then adding a defoamer, a wetting dispersant, a crosslinking agent, and a hybrid silicon-epoxy copolymer, mixing, and obtaining a hybrid silicon-epoxy copolymer modified waterborne acrylic resin.

[0011] Wherein, in step (1), the ratio of the reaction solvent, dihydroxypropyl-diepoxypropyl isocyanurate, diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 4,4'-methylenebis(phenyl isocyanate) is (8-12) mol:(0.25-0.48) mol:(0.12-0.32) mol:(0.2-0.63) mol:(1.05-1.2) mol.

[0012] Wherein, in step (2), the ratio of acrylic acid and its derivatives, crosslinking agent, and hybrid silicon-epoxy copolymer is 100g:(0.4-3)g:(2-20)g.

[0013] Wherein, the cross-linking agent includes 4,4-diaminodiphenylmethane and 4,4-diaminodiphenyl sulfone.

[0014] Wherein, in step (2), acrylic acid and its derivatives include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, glycidyl methacrylate; the initiator includes potassium persulfate and ammonium persulfate; and the emulsifier includes OP-10 and sodium dodecylbenzene sulfonate.

[0015] Among them, the preparation method of dihydroxypropyl-diepoxypropyl isocyanurate includes the following steps: adding 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and epichlorohydrin into a reaction container, adding a catalyst benzyltriethylammonium bromide after mixing, reacting at 80-90°C for 4-6h, then reducing the temperature to 55-60°C, controlling the pressure in the reaction container to 0.06-0.1MPa, adding a sodium hydroxide aqueous solution with a mass fraction of 35-42%, reacting for 30-60min, cooling, concentrating, and recrystallizing the product with ethanol to obtain dihydroxypropyl-diepoxypropyl isocyanurate.

[0016] Among them, the ratio of 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione, epichlorohydrin and benzyltriethylammonium bromide is 1 mol:(12-15) mol:(3.5-6) ​​mmol.

[0017] Technical effect: The present invention uses benzyltriethylammonium bromide as a catalyst to catalyze the reaction of 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and epichlorohydrin to obtain dihydroxypropyl-diepoxypropyl isocyanurate; then it is polymerized with diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 4,4'-methylenebis(phenyl isocyanate) to obtain a hybrid silicon-epoxy copolymer. The copolymer contains epoxy groups, which can undergo cross-linking reaction with epoxy groups of water-based acrylic resin molecular chains under the action of cross-linking agents 4,4-diaminodiphenylmethane or 4,4-diaminodiphenyl sulfone, thereby grafting the hybrid silicon-epoxy copolymer into the acrylic resin matrix, thereby enhancing the interfacial bonding strength between the two. In addition, the hybrid silicon-epoxy copolymer contains DOPO, cyanurate and siloxane structures to form a nitrogen-phosphorus-silicon flame retardant system, which promotes the combustion of acrylic resin into carbon. At the same time, the siloxane structure undergoes pyrolysis to generate silica particles in the carbon layer, forming a continuous barrier layer, inhibiting the combustion process, reducing the peak heat release rate and total heat release, and achieving excellent flame retardant properties.

[0018] The hybrid silicon-epoxy copolymer of the invention and the water-based acrylic resin molecular chain undergo a cross-linking reaction, a chemical bonding reaction is formed between the two, a three-dimensional cross-linking network is formed in the water-based acrylic resin matrix, and the cross-linking degree of the molecular chain of the acrylic resin is improved. The hybrid silicon-epoxy copolymer contains a flexible and water-resistant siloxane segment, which is beneficial to improving the mechanical properties of the resin matrix, such as impact resistance. At the same time, the resin molecular chain matrix with a high cross-linking degree can inhibit corrosive media such as water, acid, alkali, etc. from entering the interior of the resin matrix, thereby improving the water resistance and salt spray resistance of the resin. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The main raw materials of the present invention are:

[0021] Cyanuric acid, CAS No. 108-80-5.

[0022] Benzyltriethylammonium bromide, CAS number 5197-95-5.

[0023] 1,3-Bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, CAS No. 18001-97-3.

[0024] 4,4'-Methylenebis(phenyl isocyanate), CAS No. 101-68-8.

[0025] 4,4-Diaminodiphenylmethane, CAS No. 101-77-9.

[0026] 4,4-Diaminodiphenyl sulfone, CAS No. 80-08-0.

[0027] Defoamer, brand Efka SI 2741.

[0028] Wetting and dispersing agent, brand AFCONA-5207.

[0029] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), CAS No. 35948-25-5.

[0030] Add 10mmol cyanuric acid, 20mL water, and 20mmol sodium hydroxide to the reaction container, stir evenly, then add 10mmol 3-chloro-1,2-propylene glycol, react at 25°C for 12h, add 20% sulfuric acid to adjust the pH to 6, concentrate the solvent, add the product to N,N-dimethylformamide, filter and concentrate the filtrate to obtain 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione. The structural formula is

[0031] Add 20mmol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 20mmol diethanolamine, and 10mL distilled water to the reaction container, add 0.67g paraformaldehyde dropwise at 80°C, react for 1h, cool, concentrate, wash with ethanol, and dry to obtain diethanolamine DOPO. The structural formula is:

[0032]

[0033] Example 1

[0034] Add 4mmol 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and 60mmol epichlorohydrin to the reaction vessel, mix well and add 0.014mmol catalyst benzyltriethylammonium bromide (TEBAB), react at 85℃ for 6h, then reduce the temperature to 60℃, control the pressure in the reaction vessel to 0.1MPa, add 40% sodium hydroxide aqueous solution, react for 60min, cool, concentrate, and recrystallize the product with ethanol to obtain dihydroxypropyl-diepoxypropyl isocyanurate. Reaction route:

[0035]

[0036] 120 mL of N,N-dimethylacetamide reaction solvent, 2.5 mol of dihydroxypropyl-diepoxypropyl isocyanurate, 1.2 mmol of diethanolamine DOPO, 6.3 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 12 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to the reaction container, and the polymerization reaction was carried out at 90° C. in a nitrogen atmosphere for 6 hours. After cooling, methanol was added to the solution for precipitation, and the solution was filtered and washed with ethanol to obtain a hybrid silicon-epoxy copolymer.

[0037] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 80°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 1 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 43.2 g of n-butyl acrylate, 4.4 g of glycidyl methacrylate, 150 mL of water, and add an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 3 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.5 g of a wetting and dispersing agent, 0.4 g of a crosslinking agent 4,4-diaminodiphenyl sulfone, and 2 g of a hybrid silicon-epoxy copolymer, mix well, and obtain a hybrid silicon-epoxy copolymer modified waterborne acrylic resin.

[0038] Example 2

[0039] Add 4mmol 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and 48mmol epichlorohydrin to the reaction container, mix well and add 0.024mmol catalyst benzyltriethylammonium bromide, react at 80°C for 6h, then reduce the temperature to 55°C, control the pressure in the reaction container to 0.08MPa, add a 42% sodium hydroxide aqueous solution by mass fraction, react for 30min, cool, concentrate, and recrystallize the product with ethanol to obtain dihydroxypropyl-diepoxypropyl isocyanurate.

[0040] 120 mL of xylene reaction solvent, 3.5 mol of dihydroxypropyl-diepoxypropyl isocyanurate, 2 mmol of diethanolamine DOPO, 4.5 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 10.5 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to the reaction container, and the polymerization reaction was carried out at 90°C in a nitrogen atmosphere for 3 hours. After cooling, methanol was added to the solution for precipitation, and the solution was filtered and washed with ethanol to obtain a hybrid silicon-epoxy copolymer.

[0041] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 80°C, add an aqueous solution containing 0.3 g of initiator ammonium persulfate, react for 1 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 41.5 g of n-butyl acrylate, 6.1 g of glycidyl methacrylate, 150 mL of water, and add an aqueous solution containing 1.1 g of initiator ammonium persulfate, react for 3 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.5 g of a defoamer, 0.7 g of a wetting and dispersing agent, 1.8 g of a crosslinking agent 4,4-diaminodiphenyl sulfone, and 10 g of a hybrid silicon-epoxy copolymer, mix well, and obtain a hybrid silicon-epoxy copolymer modified waterborne acrylic resin.

[0042] Example 3

[0043] Add 4mmol 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and 52mmol epichlorohydrin to the reaction container, mix well and add 0.014mmol catalyst benzyltriethylammonium bromide, react at 90°C for 4h, then reduce the temperature to 55°C, control the pressure in the reaction container to 0.06MPa, add 35% sodium hydroxide aqueous solution by mass fraction, react for 60min, cool, concentrate, and recrystallize the product with ethanol to obtain dihydroxypropyl-diepoxypropyl isocyanurate.

[0044] 80 mL of N,N-dimethylformamide reaction solvent, 4.8 mol of dihydroxypropyl-diepoxypropyl isocyanurate, 3.2 mmol of diethanolamine DOPO, 2 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 11.2 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to the reaction container, and the polymerization reaction was carried out at 75°C in a nitrogen atmosphere for 7 hours. After cooling, methanol was added to the solution for precipitation, and the solution was filtered and washed with ethanol to obtain a hybrid silicon-epoxy copolymer.

[0045] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 70°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 2 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 39.4 g of n-butyl acrylate, 8.2 g of glycidyl methacrylate, 150 mL of water, and an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 2 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.6 g of a wetting and dispersing agent, 3 g of a crosslinking agent 4,4-diaminodiphenylmethane, and 20 g of a hybrid silicon-epoxy copolymer, mix well, and obtain a hybrid silicon-epoxy copolymer modified waterborne acrylic resin.

[0046] Comparative Example 1

[0047] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 80°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 1 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 43.2 g of n-butyl acrylate, 4.4 g of glycidyl methacrylate, 150 mL of water, and add an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 3 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.5 g of a wetting dispersant, and 0.4 g of a cross-linking agent 4,4-diaminodiphenyl sulfone, mix well, and obtain a water-based acrylic resin.

[0048] Comparative Example 2

[0049] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate to a reaction container, stir and heat to 70°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 2 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 39.4 g of n-butyl acrylate, 8.2 g of glycidyl methacrylate, 150 mL of water, and an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 2 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.6 g of a wetting dispersant, and 20 g of a hybrid silicon-epoxy copolymer, mix well, and obtain a water-based acrylic resin.

[0050] Comparative Example 3

[0051] 120 mL of N,N-dimethylacetamide reaction solvent, 2.5 mol of dihydroxypropyl-diepoxypropyl isocyanurate, 1.2 mmol of diethanolamine DOPO, and 4 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to a reaction container, and a polymerization reaction was carried out at 90° C. in a nitrogen atmosphere for 6 h. After cooling, methanol was added to the solution for precipitation, and the solution was filtered and washed with ethanol to obtain copolymer A.

[0052] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 80°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 1 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 43.2 g of n-butyl acrylate, 4.4 g of glycidyl methacrylate, 150 mL of water, and add an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 3 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.5 g of a wetting and dispersing agent, 0.4 g of a crosslinking agent 4,4-diaminodiphenyl sulfone, and 2 g of a copolymer A, mix well, and obtain a water-based acrylic resin.

[0053] Comparative Example 4

[0054] 120 mL of N,N-dimethylacetamide reaction solvent, 2.5 mol of dihydroxypropyl-diepoxypropyl isocyanurate, 6.3 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 9.6 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to a reaction container, and a polymerization reaction was carried out at 90°C in a nitrogen atmosphere for 6 hours. After cooling, methanol was added to the solution for precipitation, and the mixture was filtered and washed with ethanol to obtain copolymer B.

[0055] 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate were added to the reaction container, stirred and heated to 80°C, an aqueous solution containing 0.3 g of initiator potassium persulfate was added, and the reaction was continued for 1 h, and then 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 43.2 g of n-butyl acrylate, 4.4 g of glycidyl methacrylate, and 150 mL of water were added, and an aqueous solution containing 1.1 g of initiator potassium persulfate was added, and the reaction was continued for 3 h, cooled, and a neutralizer triethanolamine was added for neutralization, and then 0.6 g of a defoamer, 0.5 g of a wetting and dispersing agent, 0.4 g of a crosslinking agent 4,4-diaminodiphenyl sulfone, and 2 g of a copolymer B were added and mixed to obtain a water-based acrylic resin.

[0056] Comparative Example 5

[0057] 120 mL of N,N-dimethylacetamide reaction solvent, 1.2 mmol of diethanolamine DOPO, 6.3 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 8.2 mmol of 4,4'-methylenebis(phenyl isocyanate) were added to the reaction container, and the polymerization reaction was carried out at 90° C. in a nitrogen atmosphere for 6 h. After cooling, methanol was added to the solution for precipitation, and the solution was filtered and washed with ethanol to obtain copolymer C.

[0058] Add 40 mL of water, 0.4 g of methacrylic acid, 7.7 g of methyl methacrylate, 10.8 g of n-butyl acrylate, 1.1 g of glycidyl methacrylate, 1.2 g of emulsifier OP-10, and 2.5 g of emulsifier sodium dodecylbenzene sulfonate into a reaction container, stir and heat to 80°C, add an aqueous solution containing 0.3 g of initiator potassium persulfate, react for 1 h, then add 1.6 g of methacrylic acid, 30.8 g of methyl methacrylate, 43.2 g of n-butyl acrylate, 4.4 g of glycidyl methacrylate, 150 mL of water, and an aqueous solution containing 1.1 g of initiator potassium persulfate, react for 3 h, cool, add a neutralizer triethanolamine for neutralization, then add 0.6 g of a defoamer, 0.5 g of a wetting and dispersing agent, 0.4 g of a crosslinking agent 4,4-diaminodiphenyl sulfone, and 2 g of a copolymer C, mix well, and obtain a water-based acrylic resin.

[0059] The combustion performance of acrylic resin film was tested by microcalorimeter, the sample size was 50mm×50mm×2mm, and the thermal radiation condition was 35kW / m 2 .

[0060] Table 1 Flame retardant properties test of acrylic resin

[0061]

[0062] The water-based acrylic resin was poured into a mold to form a film, dried at 80°C for 4 hours and at 140°C for 6 hours to obtain an acrylic resin film coating. The impact resistance, water resistance and salt spray resistance were tested according to the methods of GB / T 1732-1993, GB / T 1733-1993 and GB / T1771-2007.

[0063] Table 2 Water-based acrylic resin performance test

[0064]

[0065]

[0066] In Examples 1 to 3, dihydroxypropyl-diepoxypropyl isocyanurate, diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 4,4'-methylenebis(phenyl isocyanate) are polymerized to obtain a hybrid silicon-epoxy copolymer. The copolymer contains epoxy groups, which can be cross-linked with the epoxy groups of the water-based acrylic resin molecular chain under the action of the cross-linking agent 4,4-diaminodiphenylmethane or 4,4-diaminodiphenyl sulfone, thereby grafting the hybrid silicon-epoxy copolymer into the acrylic resin matrix, thereby enhancing the interfacial bonding strength between the two. In addition, the hybrid silicon-epoxy copolymer contains DOPO, cyanurate and siloxane structures to form a nitrogen-phosphorus-silicon flame retardant system, which promotes the combustion of acrylic resin into carbon. At the same time, the siloxane structure undergoes pyrolysis, and silicon dioxide particles are generated in the carbon layer to form a continuous barrier layer, which inhibits the combustion process, reduces the peak heat release rate and the total heat release, and has excellent flame retardant properties.

[0067] The hybrid silicon-epoxy copolymer and the water-based acrylic resin molecular chain undergo a cross-linking reaction, forming a chemical bond between the two, forming a three-dimensional cross-linking network in the water-based acrylic resin matrix, and improving the cross-linking degree of the acrylic resin molecular chain. The hybrid silicon-epoxy copolymer contains flexible and water-resistant siloxane segments, which is beneficial to improving the mechanical properties of the resin matrix, such as impact resistance. At the same time, the resin molecular chain matrix with a high degree of cross-linking can inhibit corrosive media such as water, acid, and alkali from entering the interior of the resin matrix, thereby improving the water resistance and salt spray resistance of the resin.

[0068] Comparative Example 1 does not add the hybrid silicon-epoxy copolymer, and the peak heat release rate and total heat release of the waterborne acrylic resin are very high, and the flame retardancy is very poor. In addition, the impact resistance, water resistance and salt spray resistance are not good.

[0069] Although the hybrid silicon-epoxy copolymer was added in Comparative Example 2, the 4,4-diaminodiphenyl sulfone crosslinking agent was not added, and the hybrid silicon-epoxy copolymer could not undergo a crosslinking reaction with the water-based acrylic resin, and the water resistance and salt spray resistance of the resin matrix were poor.

[0070] The copolymer A added in Comparative Example 3 does not contain a siloxane segment, and the resin matrix has poor impact resistance and water resistance, and also does not contain a nitrogen-phosphorus flame retardant system, and the flame retardant performance is lower than that of each example.

[0071] The copolymer A added in Comparative Example 4 does not contain a DOPO structure, and its flame retardancy is lower than that of the examples.

[0072] The copolymer A added in Comparative Example 5 does not contain the epoxy group structure and epoxy group, and cannot undergo a cross-linking reaction with the water-based acrylic resin. The water resistance, salt spray resistance and flame retardancy of the resin matrix are poor.

Claims

1. A method for preparing a hybrid silicon-epoxy copolymer modified waterborne acrylic resin, characterized in that: The preparation method comprises the following steps: Step (1), adding a reaction solvent, dihydroxypropyl-diepoxypropyl isocyanurate, diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 4,4'-methylenebis(phenyl isocyanate) into a reaction container, performing a polymerization reaction in a nitrogen atmosphere, performing precipitation, filtering, and washing to obtain a hybrid silicon-epoxy copolymer; The structural formula of the dihydroxypropyl-diepoxypropyl isocyanurate is: The structural formula of the diethanolamine DOPO is: Step (2), adding water, acrylic acid and its derivatives, and an emulsifier into a reaction container, stirring and heating to 70-80° C., adding an initiator aqueous solution, reacting for 1-2 hours, then adding acrylic acid and its derivatives and an initiator aqueous solution, reacting for 2-3 hours, cooling, adding a neutralizer for neutralization, and then adding a defoamer, a wetting and dispersing agent, a crosslinking agent, and a hybrid silicon-epoxy copolymer, mixing, and obtaining a hybrid silicon-epoxy copolymer modified waterborne acrylic resin; The hybrid silicon-epoxy copolymer contains epoxy groups, which can undergo cross-linking reaction with epoxy groups of the water-based acrylic resin molecular chain under the action of a cross-linking agent, thereby grafting the hybrid silicon-epoxy copolymer into the acrylic resin matrix.

2. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 1, characterized in that: In the step (1), the ratio of the reaction solvent, dihydroxypropyl-diepoxypropyl isocyanurate, diethanolamine DOPO, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 4,4'-methylenebis(phenyl isocyanate) is (8-12) mol: (0.25-0.48) mol: (0.12-0.32) mol: (0.2-0.63) mol: (1.05-1.2) mol.

3. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 2, characterized in that: The reaction solvent includes xylene, N,N-dimethylformamide and N,N-dimethylacetamide.

4. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 1, characterized in that: In the step (1), the polymerization reaction is controlled at a temperature of 75-90° C. and a time of 3-7 hours.

5. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 1, characterized in that: In the step (2), the ratio of acrylic acid and its derivatives, crosslinking agent, and hybrid silicon-epoxy copolymer is 100g:(0.4-3)g:(2-20)g.

6. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 5, characterized in that: The cross-linking agent includes 4,4-diaminodiphenylmethane and 4,4-diaminodiphenyl sulfone.

7. The method for preparing a hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 1, characterized in that: In the step (2), acrylic acid and its derivatives include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, and glycidyl methacrylate; the initiator includes potassium persulfate and ammonium persulfate; and the emulsifier includes OP-10 and sodium dodecylbenzene sulfonate.

8. The method for preparing a hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 1, characterized in that: The preparation method of dihydroxypropyl-diepoxypropyl isocyanurate comprises the following steps: adding 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione and epichlorohydrin into a reaction container, adding a catalyst benzyltriethylammonium bromide after mixing, reacting at 80-90° C. for 4-6 hours, then reducing the temperature to 55-60° C., controlling the pressure in the reaction container to be 0.06-0.1 MPa, dripping a sodium hydroxide aqueous solution, reacting for 30-60 minutes, cooling, concentrating, and recrystallizing to obtain dihydroxypropyl-diepoxypropyl isocyanurate.

9. The method for preparing the hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 8, characterized in that: The ratio of the 1-(2,3-dihydroxypropyl)-S-triazine-2,4,6-trione, epichlorohydrin and benzyltriethylammonium bromide is 1 mol:(12-15) mol:(3.5-6) ​​mmol.

10. The method for preparing a hybrid silicon-epoxy copolymer modified waterborne acrylic resin according to claim 8, characterized in that: The mass fraction of the sodium hydroxide aqueous solution is 35-42%.

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