Preparation Of Crosslinked Acrylate Latex With Reactive Emulsifiers And Application On Impregnated Resins Paper

In recent years,the formaldehyde-free decorative materials for wooden had gradually become the research hotspot.But the formaldehyde-type adhesives has been widely used in the impregnated film paper for the surface decoration materials of wood-based panels.Formaldehyde-type adhesives can release a large amount of free formaldehyde that was not only the primary cause of indoor pollution but also caused serious physical harm to workers and consumers during the production and application process.Polyacrylate emulsion adhesive as zero formaldehyde emission that has been small molecule,low viscosity,good stability,and easy penetration into the paper layer especially and gradually become a good substitute for formaldehyde-type impregnated adhesive.In this paper,the feasibility of replacing traditional small molecular emulsifiers with reactive emulsifiers was firstly explored.The research indicates that substrate and surface adhesive of impregnated paper were successfully synthesized with acetoacetoxyethyl methacrylate(AAEM)or hydroxybutyl acrylate(4HBA)as the postcrosslinking monomers respectively and 1,3-butanediol dimethacrylate(1,3-BDDMA)as the internal crosslinking monomer.And the effect of three functional crosslinking monomers on the polymerization of acrylic was investigated.Finally,the impregnation process and hot pressing process of acrylic emulsion adhesive on impregnated film paper was optimized,and the application effect of acrylic latex on impregnated film paper and veneer wood-based panels was investigated.(1)The two reactive emulsifiers SR-10 and JS-20 had successfully participated in the emulsion copolymerization.The good stability emulsions that the monomer conversion rate of more than 97 %,latex particle size less than 100 nm and PDI less than 0.5 were obtained under the condition that the reactive emulsifiers dosage exceeded 3% of the monomer.Because of lacking of migration and aggregation of the emulsifiers,the acrylate latex film synthesized by reactive emulsifiers system had the excellent surface properties and good stability of 1% calcium ion resistance.Among them,the water absorption rate of the latex film that prepared by the system with 3% JS-20 reduced about 7.89% after soaking for 24 h at room temperature,and the heat-resistant stability of the latex film that prepared by the system with 3% SR-10 increased about 9.1 ℃.(2)The acrylate polymers were modified by two post-crosslinking monomers and an internal crosslinking monomer in order to improve the water resistance and abrasion resistance of polymer and its application performance on impregnated film paper.All three crosslinking monomers successfully participated in the copolymerization of acrylate emulsion,and the good stability emulsions with the monomer conversion rate of more than 98 %,latex particle size less than 98 nm and PDI less than 0.5 were obtained under the condition of 3% the crosslinking monomers dosage of the total monomer.The crosslinking degree of the latex films at room temperature reached 12.8% and 53.9% respectively with 3% AAEM and 4HBA,and the crosslinking degree further reached 82.7% and 81.6% respectively after the high temperature treatment.The polyacrylate latex film modified by 3% the internal crosslinking monomer 1,3-BDDMA had the best water resistance as cross-linking degree reached 93.75% and the water absorption rate of latex film at room temperature for 24,48 and 72 h was 1.69%,2.37% and 3.25%respectively.The thermal stability and mechanical properties of the polymers that modified by three crosslinking monomers were improved greatly.Among them,the maximum tensile strength and elongation at break of the acrylic latex film modified by 1,3-BDDMA reached 21.16 MPa and 166% respectively.The tensile strength of the latex film modified by the two postcrosslinking monomers could be further enhanced after secondary curing and crosslinking.(3)Finally,the process parameters of the acrylic adhesive on the impregnated film paper were optimized.The research indicates impregnated amount of the impregnated film paper reached 140%,the volatile content and pre-curing degree were basically maintained between8%～12% and 60%～65%.Under the process of hot pressing pressure 1.0 Mpa for 60 s at 160 ℃,the surface bonding strength of the veneer wood-based panel was 0.826 MPa,the surface abrasion resistance value was up to 30 mg/100 r and the surface resistances of acid and alkali,water vapor,heat coffee and acetone reached the level 5,3,5,and 4.