Discussion on the formula technology experiment of

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Discussion on formula technology of inkjet coating continued

2 results and discussion

porous inkjet coating is mainly composed of an insoluble inorganic pigment particle and some adhesives. It may also contain some additives with special system display "C1" to enhance the coating performance. There are more and more reports about the new materials used in porous and high gloss inking coating

three different SiO2 particles, colloidal SiO2, sintered SiO2 and fumed SiO2, and their effects on various coating properties and properties were studied in this paper. The average particle sizes of these three SiO2 particles are 95 nm, 278 nm and 318 nm respectively

2.1 influence on coating formula

the outstanding advantages of this material include excellent mechanical properties, high mobility, outstanding color stability, excellent chemical resistance. The basic formula of the coating is polyvinyl alcohol as adhesive, and the ratio of pigment to adhesive is 80/20. The coating formulation performance is shown in Table 1. Colloidal SiO2 and sintered SiO2 have the potential advantage of obtaining high solid content at low Brookfield viscosity

2.2 effect on coating structure

change the final coating structure by changing the particle size. It is expected that the gloss of the coating is inversely proportional to the particle size, and the gloss of the coating decreases with the increase of the particle size. Calendering can be used to improve gloss and produce high gloss inkjet printing paper

Figure 1 shows the gloss value of each particle before and after calendering in the hot/soft pressing area. It can be seen from Figure 1 that sintered SiO2 has the highest gloss measurement, which can not only protect the value of house structure. Its value is significantly higher than that of fumed SiO2 with the same particle size, and further increases after calendering

the results of scanning electron microscope (SEM) inspection of the coated surface are also expected. The surface image is always consistent with the measurement result of gloss. Tiny cracks appear in the image of colloidal SiO2 based coating

2.3 impact on printing performance

for an inkjet pigment, its performance is good or bad in terms of its printed image. Print the test pattern on coated and calendered paper. Figure 2 shows the ink concentration values of blue, red, yellow and black (cmyb). The properties of all three SiO2 particles were compared. It can be seen from Figure 2 that the concentration of colloidal SiO2 and sintered SiO2 black pigment inks is slightly higher

except for cationic mordants, these pigments showed poor water resistance in the test. The particle structure and pH value have no effect on the water resistance, which is controlled by the surface chemistry of SiO2. Adding cationic polymers such as poly DADMAC can improve the water resistance of these three particles, but colloidal SiO2 and sintered SiO2 will reduce their surface gloss

the study of printing characteristics by image analysis technology further shows that there are differences among these three SiO2 particles. Table 2 shows the diagram of Epson printing machine. What are the extensive uses of electronic universal testing machine, such as the analysis results

it can be seen from table 2 that the area from top to bottom decreases significantly. Smaller area is better, and the printing resolution can be improved without losing ink concentration. The test results of dot roundness value show that the sintered SiO2 coating has a more uniform coating structure. On the contrary, fumed SiO2 has a low dot area due to its high porosity, but irregular fumed particles produce high dot circularity values, resulting in uneven coating

Figure 3 shows the porosity values of three SiO2 particles. The porosity of colloidal SiO2 and sintered SiO2 is lower than that of flue-cured SiO2. This data is consistent with the observed point area results

The porosity of colloidal SiO2 based coating is caused by the interstitial pores produced by spherical particles during the filling process. Sintered SiO2 with intercellular particle porosity is expected to have more porosity, but its porosity is only about 10% higher than that of colloidal SiO2. This may be due to the degradation of some sintered SiO2 into its colloidal raw materials. Fumed SiO2 showed the highest coating porosity. The final image quality requires a balance between coating porosity and coating uniformity. Although the printing quality of colloidal SiO2 and sintered SiO2 coatings is acceptable, their low porosity will restrict their use effect

3 conclusion

colloidal SiO2 and sintered SiO2 particles have more advantages than smoke SiO2 in rheology, solid content percentage, gloss, ink concentration and dot roundness of coating formula. However, the coating shows low porosity. On the contrary, fumed SiO2 with rigid irregular shape can produce more porous layers. However, it can also reduce gloss and solid content of paint formulation. In order to obtain inkjet coatings with low cost and high gloss, all factors must be balanced. (translated by Ma Xin)

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