Abstract: [Objective] Combing with papermaking and coating finishing process of decorative paper, the influence of coating on the printability of decorative base paper and its act mechanism were investigated, which provide the reference basis for the improvement of performance of decorative base paper and its use in the field of wood panel decoration.[Method] Decorative base paper was made through dynamic sheet former, using mixed pulp of fine hardwood and softwood, TiO₂, polyacrylamide (PAM), polyamide epichlorohydrin (PAE), aluminum sulfate and other filler additives as raw material. Surface coating was prepared with PVA, cationic starch as the adhesive, then distilled water, pigments, dispersants and other additives were added in a high-speed mixer stirring for 40-60 min. The particle size and thixotropy of the coating were analyzed by laser particle size analyzer and cone-plate viscometer. The decorative base paper was coated and calendered by using a coater and a calendar, respectively.The morphology of the coated decorative base paper was characterized by SEM, AFM, dynamic osmometry and dynamic contact angle analyzer. The printability tester was used for the intaglio printing proofing of coating decorative base paper, measuring the color characteristics of proofs by color density meter, and analyzing the printing performance of coating decorative base paper.[Result] Based on particle size and thixotropy analysis of pigments, it was found that TiO₂ (201) and SiO₂ pigments had small particle size and narrow distribution, but TiO₂ (902) and Clay pigments had large particle size and wide distribution, while Al₂O₃ pigment had small particle size and wide distribution. When the pigments were prepared into coatings, the particle size distribution range of pigment coating became larger, in which the Clay coating had the largest particle size distribution, and the SiO₂ coating had the smallest particle size range. However, the thixotropy of Clay coating and Al₂O₃ coating was the biggest, and the thixotropy of TiO₂ (902) coating and SiO₂ coating was the smallest. The coating structure, surface morphology and the printing performance were characterized through using of SEM, AFM, dynamic permeation analyzers and dynamic contact angle measurement. The result showed that the surface of the base paper could be covered more effectively with the SiO₂ coating, and the pore of coating layer was uniform. Dynamic contact angle of SiO₂ coating layer has declined by 58.17% within 1.3 s, and the C_i and C_t value was 17.6 and 2.8, respectively. It showed that the surface of base paper coated by SiO₂ coating had the optimal coating structure. Physical properties of coated decorative base papers were improved significantly, in which the tightness, water absorption height, smoothness, dry tensile strength and wet tensile strength was increased by 25%-61%, 33%-118%, 150%-290%, 171%-194%, and 220%-290% respectively. The physical properties of SiO₂ coated base paper were the best, with tightness increasing by 25%, water absorption height increasing by 108%, smoothness increasing by 290%, dry tensile strength increasing by 171% and wet tensile strength increasing by 290%. For the printability of the decorative base paper coated with SiO₂ coating, the color density was increased by 16.5% to 40%, comparing the decorative base paper, and the value of CMY of gravure printing color was 1.31, 1.3, 1.28 for the net hole depth of 33 μm respectively which were beneficial to improve the overall reproduction range of color and the effect of printing decoration.[Conclusion] The pores of surface structure of decorative base paper could be filled by the SiO₂ coating effectively, forming an excellent coating structure, which contributed the good ink receptivity, ink absorption and ink fixing properties, thereby inhibiting dot enlargement and further improving the printability of base paper.

Key words: wood-based panels, decorative paper, wood surfaces decorative, surface coating structure, printability