The research progress and performance of water-based polyurethane chemical modified (including epoxy, acrylic, silicone and composite modified) has been improved

Abstract: The research progress of several water-based polyurethane chemical changes, including binary copolytic changes such as epoxy resins, acrylic resins, silicone oxane, and the three-way copolytic correction of two or more resins, is introduced. The development trend of chemical change of water-based polyurethane is forecasted.polyurethane, short for polyurethane, is a polymeric compound containing a significant amount of urethane bonds. Water-based polyurethane (WPU) is a binary gel system that replaces organic solvents with water as a dispersion medium, which contains or contains a small amount of organic solvents, has the advantages of non-combustible, non-toxic and non-polluting, energy saving, easy operation and processing, and retains some excellent properties of traditional solvent-based polyurethanes, such as good wear resistance, flexibility, low temperature resistance and fatigue resistance. A single polyurethane emulsion still has the disadvantages of poor self-thickening, low solid content, poor water resistance of latex film, low gloss and poor comprehensive performance of coating film. However, pu pre-polymer - NCO group has a strong activity, can react with hydroxyl, amino, vinyl and other groups, which provides the possibility for researchers to improve the comprehensive performance of WPU coatings through change, prompting the majority of researchers to carry out various modified research on water-based polyurethane coatings to expand their application range. The method of water-based polyurethane change has two forms of physical mixing and chemical co-fusion: co-mixing is mixing two or more resins with complementary characteristics, and the biggest problem is the stability difference of mixing. Co-fusion is the synthesis of a compound emulsion with special properties by introducing various functional components into the system, which is practical because of the good stability of the emulsion. At present, PU and methyl cellulose, polyethylene alcohol, ethylene acetate, butyl rubber, epoxy resin, polysilica and acrylic composite emulsions have been studied, of which the 3th type of composite emulsions are complementary in function and water-based polyurethane, especially on the water resistance and hardness, strength and other mechanical properties of polyurethane coating is more significant, therefore, the most active research.1 epoxy modified water-based polyurethaneepoxy resin has many excellent performance, such as high mechanical strength, strong adhesion, low forming shrinkage, good chemical stability, good electrical insulation, good thermal stability, etc., widely used in the coatings industry. Because the hydroxyl and polyurethane reaction of epoxy resin can introduce the branching point into the main chain of polyurethane, so that it partially forms a mesh structure, so the epoxy modified polyurethane (EPU) emulsion in improving the adhesion of the coating film, anti-sheet strength, water resistance and solvent resistance and other aspects of the role is obvious. Wang Hua equal people with epoxy resin modified water-based polyurethane, the results show that: modified water-based polyurethane mechanical performance is good, high bonding strength, water and solvent resistance performance is excellent, but when the epoxy resin dosing is too high, the stability is poor. Wen Xiufang et al. discussed the effects of R-value (NCO/OH), 1,4-butyl glycol, dihydroxymethyl acid, epoxy resin, neutrality, etc. on dispersion and coating properties in epoxy resin synthesis, and the addition of epoxy resin significantly improved the water resistance, chemical resistance, hardness and stretch strength of the coating film, and its suitable dosing was 8% to 9%. Jiang Shouxia and others studied the effect of epoxy resin in water-based polyurethane emulsion on its performance, and found that: after adding epoxy resin, the water resistance of the product has been significantly improved, with the increase of epoxy resin content, hardness increased, viscosity is on the rise. Y.C.CHERN et al. compared the structures of two methic acid-modified polyurethanes and analyzed the polyols of different relative molecular mass. M.Alagar et al. carried out DSC analysis and SEM testing on the epoxy modified water-modified polyurethane produced, and found that after the modified, the coating performance was optimized. Luo Jianguang and others compared the effect of EP's addition on coating performance, and the results showed that the comprehensive coating performance of copolymer legal system was better than that of confming, and the analysis of infrared spectroscopy and DSC showed that the epoxy group had an interlinking reaction during the coggestion, forming a local IPN structure with PU.。 It is more appropriate for the EP to be added less than 7%. Wu Xiaoqing et al. modified water-based polyurethane with epoxy E-44, and found that when the content of hydroxymethyl propylene acid was 5% to 7%, the added amount of epoxy resin was 5% to 8%, the reverse transfer dispersion method was used, a more stable epoxy-modified water-based polyurethane emulsion could be obtained, and the overall performance of emulsion was better. The coating film prepared with epoxy modified water-based polyurethane has the characteristics of high hardness, water resistance and solvent resistance. Hu Jianqing et al. introduced epoxy resin in the synthesis process of self-emulsified water-based polyurethane, obtained water-based polyurethane epoxy resin emulsion, the emulsion organic volatile content is low, not only has the high adhesion, high strength, chemical resistance and corrosion resistance of epoxy resin, but also has the excellent flexibility of polyurethane, wear resistance, abundance, aging resistance and film-forming properties. With this emulsion as the base material, through the formulation design, prepared a high-performance water-based rust-proof coating.2 Acrylic modified water-based polyurethanepolyacrylate (PA) emulsion has better water resistance, physical mechanical properties and weather resistance, so PU and PA are complementary in performance. The co-polymerization of acrylic compounds to water-based polyurethanes is the addition of PA to pu emulsions and the production of compound emulsions (PUAs) by free-based polymerization of the trigger. The preparation method mainly has the following: (1) PU emulsion and PA emulsion mixed, plus crosslinker for copolymer formation PUA composite emulsion; The two emulsions penetrate each other with molecular line degree, and then react to form a PUA composite emulsion with high molecular interoperability network; (4) synthesize the unsaturated aminomate monomer with C-C double bond, and then co-polymerize the large monomer and other acrylic monomers to obtain pua co-polylactic emulsion. ChoiHS et al. used hydrogen oxide as a trigger to prepare acrylic polyurethane latte co-polymers, and discussed the reaction temperature, reaction time, monomer concentration on the reaction effect. Xu Kewen et al. used acrylic hydroxyethyl ethyl esters as an end agent, potassium persulphate as a trigger, and legally synthesized a well-stable, high comprehensive performance acrylic copolytic water-modified polyurethane emulsion. By comparing the infrared spectra of PU and PUA, the excellent performance of PUA is explained from the structure. Ma Chao et al. synthesized a water-based polyurethane/acrylic composite emulsion (PUA) with a nuclear shell structure by polymerization of free-form emulsions. The results show that the smaller the nuclear shell ratio, the more normal the structure of the nuclear shell, the more uniform the distribution of particle size, the more stable the emulsion; The larger the nuclear shell ratio, the better the water resistance of the film. WilliamsN et al. prepared hydrophobic polyurethane pre-polymers, then added acrylic monomers and chain expanders, catalysts before free-based polymerization reaction, to obtain the nuclear shell non-cross-linked acrylic-polyurethane emulsion, after dry coating film wear resistance, water resistance and anti-fouling resistance have been improved. Kim K et al. studied the linear interoperability network structure (LIPN) acrylic polyurethane emulsion of light-triggered polymerization, which is similar to the non-crosslinking polymerization process, including the process of swelling monomer, causing polymerization, latex particle growth, etc. Jiang Dawei et al. used the method of dripping acrylic monomers into water-based polyurethane emulsions to carry out composite emulsion polymerization or interoperability network (IPN) polymerization to prepare PU/PA composite emulsions. The results show that the materials polymerized by IPN have excellent properties in elastic mods, stretch strength and so on, and the content of NCO end-base will affect the compatibleness of these two materials in the process of emulsion preparation. Ren Xiangzhong et al. introduced double bonds in water-based polyurethanes with shunbutene dionium, and joined with methyl acrylates (MMA) in the non-trigger system of Cu2 plus, and the results showed that the hydromassivity of binary alcohol had an effect on the particle size of the glue beam. With the increase of polypropylene glycol content, the thing co-clustering reaction is easier to carry out, and the particle size of the gel beam increases after gliding. However, with the continued increase of propylene glycol content, the thing co-fusion reaction is difficult to carry out, the adhesive beam particle size before and after the branching changes little, and there is a tendency to decrease; With the increase of the softness of the polyurethane molecular side chain, the rigidity of the main chain is enhanced, and the beam particles are prone to microphase separation, forming a shell core structure.3 Silicone modified water-based polyurethanesilicone molecules contain both organic groups and inorganic silicon atoms with low surface energy, often used as an organic medium and inorganic media coupled agent.It is rich in surface in the coating film, giving the coating film excellent water resistance, weather resistance, acid and alkalinity resistance, high and low temperature resistance and good mechanical properties, so it has been widely studied and applied. However, in order to realize the copolymeration of silicone and polyurethane, the silicone molecular chain must contain active groups such as hydroxyl, amino, vinyl, epoxy and so on, which can react with NCO-based reactions in isocyanate. Hydroxylsilane is often used as a hydroxy component to partially or completely replace polyglycol to participate in the synthesis of polyurethane pre-polymers, the introduction of Si-O bonds on the molecular chain of pre-polymers; Aminosilane is used mostly in bi-aminosilane and is introduced into polyurethane emulsions through a chain expansion reaction with pre-polymers; Ethylene silane is used as a diplomatic co-agent to achieve the purpose of change by reacting with water-based polyurethane-chained niobium-based or niobium-based ammonium salts.。 MequanintK et al. used sioxane to transform water-based polyurethanes. The results show that sioxane is mainly concentrated on the surface of the membrane, which provides water repulsive properties for the coating film. With this property, water-resistant coating films can be prepared with hydro-hydro-water-based PU polymers. ZhuXL et al. used the method of hydroxyalkyl sealing to synthesize and study silica with polyhydroxygen groups to obtain Si-C-O structures that can be stable in water, and segment copolymers with controlled relative molecular mass. Through infrared, nuclear magnetic and other analytical means to prove that hydroxyane sealing end of silane as a chaining agent for the preparation of water-based polyurethane has a significant effect. Liu Hongzhi et al. will add a mixture of TDI, polyether binary alcohol and end hydroxysilicon monomer to react, generating a polyurethane pre-polymer with an end-based NCO, which is emulsified by expanding the chain, neutralizing, and watering, and synthesizing the silicone modified polyurethane emulsion. The water resistance, heat resistance, low temperature resistance and aesthetic properties of the resulting materials have been improved. Bao Liang et al. synthesized polyurethane prepolymers with TDI, polyether glycol, dihydroxymethylate, etc. as raw materials, and prepared cross-linked water-based polyurethane through 3-amino propylene triethyloxylsilane (KH550) sealing and emulsification. The results show that KH550 can significantly improve the water resistance and hardness of water-based polyurethane. When the KH550 mass score was 7.5%, the comprehensive performance of water-based polyurethane was better and the hardness reached 2H. ChuangFS et al. used hydroxysiloxane and aminosiloxane amplification chain agent and end-NCO prepolymer reaction, resulting in sioxane modified polyurethane, thermal analysis results show that: thermal stability and degradation rate and polyurethane chain in the type of soft and hard segments, hydroxysiloxane modified hydrothermal polyurethane thermal stability is better than urethane conversion polyurethane. Wang Hao et al. synthesized a series of endoamide-based anionic water-based polyurethanes and analyzed their structure with GPC, IR, H-NMR, through their association with the silane compound agent Y-(2,3-epoxy propylene oxygen) The room temperature curing reaction of propylene-trimoxysilane (KH560) resulted in an excellent performance polyurethane coating, which has good regeneration and water resistance.4 Composite modified water-based polyurethaneuses only one substance to modifie water-based polyurethane, its performance can not meet a variety of needs. Because epoxy resin has the advantages of high mod, high strength and good chemical resistance. Acrylic has good water resistance, weather resistance; Silicone has better breathability, water resistance, low temperature resistance is particularly good. Therefore, in the experiment how to combine these advantages organically, make up for each other to improve the comprehensive performance of water-based polyurethane, which put forward higher requirements for WPU modified research. On the basis of binary copolytic change, many researchers have carried out fruitful research on binary copolytic change, especially with epoxy resin, acrylates, silicone three kinds of modified materials, the two cross-combination of water-based polyurethane modified research has become a recent research focus. A group of researchers from South China University of Technology conducted a deeper study on the synthesis of epoxy-acrylic-polyurethane hybrid emulsion. Such as Huang Hong et al. with epoxy resin E-44 and methyl acrylates (MMA) composite modified water-modified polyurethane (WPU), acrylic hydroxyethylate (HEA) and MMA copolymer reaction, the production of acrylates for the core, polyurethane for the shell, HEA for the nuclear shell bridge between the nucleus cross-linked PUA composite emulsion. This composite emulsion concentrates the advantages of low temperature resistance, good softness, strong adhesion, good water and weather resistance of acrylic, high modulation, high strength and good chemical resistance of epoxy resin. Fu and Qing et al. used trihydroxymethyl propane (TMP) as crosslinker, first with epoxy resin modified polyurethane (PU), get epoxy resin modified water-based polyurethane (WPUE) dispersion, and then add methamphetamine (MMA) and trigger acetone isobutylene (AIBN), through free radical emulsion polymerization to obtain polyurethane-epoxy-propylene resin (WPUEA) dispersion.results show that E20 epoxy resin is selected, when the total molar ratio of NCO/OH is 1.2 to 1.5, the addition of TMP is 4% to 8%, the addition of E20 is 4% to 6%, and the addition of MMA is 10% to 30%, the resulting WPUEA hybrid dispersion performance is better, coating hardness of 0.73, gloss reached 85, table drying time of 30min, freeze-thaw cycle greater than 5 times, while water resistance and solvent resistance are improved.In the epoxy-silicon modified water-based polyurethane, Guangzhou Pearl River Chemical Corporation to E-20 epoxy resin and γ-ammonia propylene triethyl silane (A1100) as modified materials, the production of polyether binary alcohol, toluene isocyanate, dihydroxymethylate as the base material of the water-based polyurethane adhesive. In addition to the advantages of non-toxic, non-flammable, environment-friendly and low cost, the adhesive has excellent comprehensive performance. Its appearance is translucent (milk white) liquid, viscosity value of 31 to 35mPa.s, strong resistance to boiling (90 oC), peeling strength 1.35 to 3.05MPa, stretch shear strength 1.85 to 4.81MPa. Zhang Xiaoxuan et al. modified water-based polyurethanes with acrylic resin (PA or PAr) and silicone to synthesize a silicone acrylic polyurethane polymer. Various synthesis conditions, such as reaction temperature, NCO/OH value, trigger concentration, COOH dosage, silicone dosage, etc., are discussed