| For the past 50 years,waterborne acrylic coatings have been increasingly used in various industrial and civilian applications,including wood paints,floor paints,building interior or exterior latex paints,automotive and appliance finishes,etc.Yet,due to their intrinsically high flammability,waterborne acrylic coatings are easy to burn and emit smoke when combustion occurs,which makes it difficult to control fire and evacuate a crowd.As a result,there are some fire safety issues.Regarding the modification of waterborne acrylic coatings for flame retardancy,the method of physically blending flame retardants into the polymer matrix is typically used,but it has the drawback of low flame-retardant efficiency.Consequently,high loading is required for decent flame retardancy,which leads to the deterioration of the mechanical properties of the final coating products.Hence,it is of great significance to make an effort to explore a novel flame-retardant method for waterborne acrylic coatings.In this paper,waterborne acrylic resin dispersion modified with vinyl chloride-co-isobutyl vinyl ether（VC-IBVE）was designed and synthesized successfully by solution polymerization.The preparation process and formula were optimized using an orthogonal experiment to obtain the best preparation strategy.Additionally,the properties of waterborne VC-IBVE-modified acrylic resin dispersion and the two-component coatings were investigated.On the basis of this,we fabricated a phosphorus-containing waterborne VC-IBVE-modified acrylic resin by introducing a vinyl phosphate monomer（PM-2）and evaluated its flame retardancy and thermal stability.Moreover,in order to further improve the coatings’flame resistance,waterborne acrylic composite coating with a P/Si synergistic effect was created by blending modified nano-Si O2 into the polymer matrix.The effects of nano-Si O2 on flame retardance,thermal stability,anticorrosion,and mechanical properties of composite coatings were also studied.The following are the primary research contents covered in this paper:（1）Waterborne acrylic resin dispersion modified with vinyl chloride-co-isobutyl vinyl ether（VC-IBVE）was designed and synthesized successfully by solution polymerization.The effects of the ratio of soft and hard monomers,the amount of hydrophilic monomer,the amount of initiator,the amount of VC-IBVE,the reaction temperature,the type and amount of neutralizer as well as the use of HPA and IBOMA on the dispersion were investigated.Using the waterborne acrylic resin created in this article with Bayhydur 2655 curing agent and amino resin,respectively,two types of two-component waterborne acrylic coatings were created.According to the results of coating performance tests,two-component waterborne coatings made from waterborne VC-IBVE-modified acrylic resin have better chemical resistance and adhesion than two-component waterborne coatings made from commercially available hydroxyl acrylic resin aqueous dispersion.The above results show that the introduction of VC-IBVE can significantly improve the adhesion,flexibility,and corrosion resistance of waterborne acrylic coatings,and VC-IBVE also contains flame retardant components that can be utilized as the basic resin for flame retardant coatings.（2）We fabricated a phosphorus-containing waterborne VC-IBVE-modified acrylic resin by introducing a vinyl phosphate monomer（PM-2）.Moreover,a flame-resistant coating was prepared by mixing this resin with a curing agent and other additives.The effect of PM-2 on the flame retardance of the coating was studied via thermogravimetric analysis（TGA）,limiting oxygen index（LOI）,and flammability test.The results of TGA show that the flame-retardant coating has a higher thermal decomposition temperature,and the residual rate is 12.8%at 600℃,which is about 3%higher than that before modification.The results of the flammability test show that the introduction of PM-2greatly increased the flame retardance of acrylic resin,and the LOI value of the flame-retardant coating（22.6%）is higher than the ones of the pure acrylic coating（only17.8%）.At the same time,the results of coating performance tests show that the flame resistance coating still maintains the excellent performance of the waterborne acrylic coating.（3）Using KH-550 surface-modified nano-Si O2 as an inorganic filler dispersed in phosphorus-containing waterborne VC-IBVE/acrylic dispersion,we successfully prepared a type of P-Si/VC-IBVE modified acrylic composite coating.The flame retardance and mechanism of the composite coating were investigated by TGA,LOI,horizontal combustion test,scanning electron microscope（SEM）,and energy dispersive spectroscopy（EDS）.The corrosion resistance of the composite coating was studied by potentiodynamic polarization test（PDP）,water contact angle test（WCA）,and coatings performance tests.The results show that the addition of Si O2 can significantly enhance the corrosion resistance and water resistance of the composite coating.Additionally,the results of coating performance tests and electrochemical testing demonstrate that the composite coating has strong corrosion resistance and can effectively protect metal substrates.The results of the TGA and horizontal combustion test show that the composite coating has excellent flame retardance and thermal stability,and the residual rate of composite coating is as high as 25.78%at 600℃.Furthermore,the composite coating shows a limited oxygen index（LOI）value of 25.3%and reaches an HB rating in the horizontal combustion test.Waterborne acrylic composite coating with phosphorus/silicon synergistic effect prepared in this paper maintains the excellent overall performance of waterborne acrylic coatings,and it has the advantages of a simple preparation process and lower VOCs emissions,which lays a foundation for its application in the field of flame resistance protection. |
PDF Full Text Request