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Nano-silica from rice husk (nano-RHS) was synthesized and used in a coating agent to enhance the flexographic print quality of bleached kraft liner. The rice husk was refluxed with a 2 M HCl solution and calcined in a muffle furnace at 650 °C for 4 h. The particle size of the resultant rice husk ash was reduced to a very fine nano-RHS by hexadecyl trimethyl ammonium bromide. The synthesized nano-RHS in different proportions – 1%, 2%, 3%, 4% and 5% (w/w resin ) – was added to a water-based coating agent consisting of acrylic resin. The coating agent with nano-RHS additive was applied by gravure rolling onto the surface of a 170 g/m 2 bleached kraft liner 3–4 μm in thickness. The flexographic print quality was determined with printing details of 31.5 lpc using water-based process colors. The results indicated that the coating agent with 1% nano-RHS was the most promising for improving the flexographic print quality on the bleached kraft liner. At this fraction, the best print quality in terms of high sharpness of fonts and texts, line art, realistic image, and TVI curve (under the requirements of ISO 12647-6) were achieved. In addition, low tone-value and Δ E * ab with a large, three-dimensional color profile and the widest color gamut were obtained.

To enhance printing qualities, this study used refluxed silica (SiO2) from rice husk by hydrochloric acid (HCl) at different molarities and reaction times as coating agent for printed paper. Characterization of the refluxed silica from 2M HCl 120 min elucidated the purity of 98.7% and amorphous structure. Particle size of the silica exhibited uniform size of 3 μm and the color measurement (CIE L*a*b*) indicated 94.79+0.48+1.24, whiteness and color difference (E) were 84.85, 3.28, respectively. The coating agent was prepared by water-based varnish of acrylic resin mixed with the synthesized silica at different proportions: 0.0, 0.5, 1.0, and 1.5 (%wt), and later was applied on 170 g/m2-white kraft papers. The results showed that the water-based coating varnish with silica exhibited an increase of viscosity as increasing the amount of the silica. Printing qualities indicated that the vanished printed paper with 1.0% silica elucidated the highest details in shadow tone and text (font) sharpness. The color gamut yielded a wider scope than the printed papers which were varnished with the silica at 0.0%, 0.5% and 1.5%. Nonetheless, the color density showed insignificant difference to 1.5% silica varnished paper.

Alkyd resins were cheap and can perform good properties depend on the modification. In this study, commercial alkyd resins were blended with various proportions of phthalic anhydride and oil on solid. The solvent system showed a clear single phase solution and a clear coat of binder. All the blends were applied on duplex paperboards. The evaluation of coat ability in terms of drying time, adhesion, glossiness, rub resistance, and physical appearance were investigated.

Oil palm frond pulp (OPF) was blended with activated carbon for the purpose of active packaging in this preliminary study. It was aimed to investigate the effect of in-situ activated carbon on physical and mechanical properties of the pulp handsheets made from OPF. Testing of property performances of the resulted handsheets included density, moisture content, thickness swelling, folding, tensile strength, %elongation, stiffness, and modulus of rupture. Ultimately, the intention is to use for prospected active packaging for fresh produce. OPF pulp was prepared by the kraft process. The pulp stock was mixed with different proportions of activated carbon (0, 10, 20, and 30% w/w). The results showed that an increased proportion of activated carbon decreased density and thickness selling, but had no effect on moisture content.

The surface of low density polyethylene (LDPE) film was modified by coating with titanium dioxide (TiO2) nano-particles in epoxy resin in order to increase the surface energy. Epoxy/TiO2 yielded a bridging effect between TiO2 particles and polymer matrix, while epoxide group played a role as dispersant. The surface energy of coated film and uncoated film were compared. The modification of LDPE surface used different two TiO2 nano-particles in size (100 and 150 nm) and weight loadings (0.5, 1.0, 2.0 and 4.0 %wt/wt). The results showed that the surface energy of LDPE films were raised up after the coating but it was still lower than the commercial film. Changes in colors and the agglomeration of TiO2 particles caused by non-homogeneity to the epoxy resin were detected on the film surface. To this end, it can be concluded that the TiO2 coating improves the printability on LDPE film.