Papers by Author: Xu Wei Hu

Abstract: This paper provides a novel post treatment method to achieve high conductivity of nano-size silver coatings. Based on the preparation of nano-size conductive ink and conductive circuit, the printed sample and the coated conductive film were treated by series concentrations of silver nitrate solution and hydrazine hydrate solution in this order. The samples were dipped in 1%~20% solutions of silver nitrate and hydrazine hydrate successively, to form the new conductive layer of Ag particles only. It was investigated that the relationship between the thickness of printed and coated layers on photo paper and final conductivity after dipped in two kinds of solutions in turn, which were printed from one to three times and coated by screw (6#). Atomic force microscopy (AFM) was used to characterize the morphologies of as printed and coated samples. The surface sheet resistance of sample was tested by four-probe tester. It was found that when the coated silver conductive ink samples were dipped in 2% silver nitrate solutions and 2% hydrazine hydrate solution at room temperature, the conductivity reaches 0.82Ω/□. The samples with thicker conductive film before dipping need solutions at lower concentration to get high conductivity. The roughness of samples after treatment falls down, as the concentrate of dipping solutions rising. It is therefore considered that the “dip in” method provides an efficient alternative to improve the conductivity of samples.

Abstract: Fluorescent intensity is an important indicator to evaluate the performances of fluorescent inkjet ink. It can be affected by many factors, such as the structure and content of fluorescent material, the polarity of solvent, the type and content of resin, optical properties of different substrates. Formulation of red fluorescent ink-jet ink was designed in the paper and ink samples were prepared to explore the impact of fluorescent material content, solvent polarity, and resin type on fluorescent intensity. Results show that: fluorescent intensity gradually increases as fluorescent material content increases, when the content reaches 1.0%, fluorescent intensity decreases; saturated solubility of fluorescent material at room temperature (25°C) is 1.6%; When propylene glycol monomethyl ether acetate (PMA): ethyl acetate: n-butyl acetate = 0.36:0.42:0.22, resin EP-609 content is 16%, fluorescent intensity reaches to the highest.

Abstract: Environment protection has aroused big concern in industrial development nowadays, and the printing industry has always been known as a big paper consumer and environmental pollution "contributor". In 1980s, Europe and the United States pioneered the concept of environment-friendly printing. China has also issued “Regulations for Environmental Labeling Products—Ink” since the 2008, which contains similar provisions of limited demand with those regulations of USA, EU, Japan, New Zealand and other countries. Environment-friendly ink is the key to achieve environment-friendly printing, and fine chemicals as an indispensable component is the sticking point to control. This paper describes the relevant laws of environment-friendly ink, types of environment-friendly colorant and the actual application, such as in inkjet and flexographic printing field.

Abstract: The performances of three kinds of water-based pigment inks were compared and studied, which include self-made ink, original printing ink and compatible ink. Art paper, matte paper and white card paper were used as the substrates. Testing the contact angle of ink droplets, the spreading, wetting, and drying rate of inks were investigated. The color density and CIE L*a*b* values of the printed samples were measured, to evaluate the hue error and color gamut. The water resistance was studied with corresponding experiments. The result indicates: self-made water-based pigment ink has the smallest contact angle on coated paper, showing a faster drying rate. Its color gamut is similar to the original printing ink on art paper, and the hue error is low. Through the water resistance test, the color density measured on art paper and matte paper had no changes, without color dissolving and color fading, showing good water resistance applicability.

Abstract: The RFID antenna is mainly fabricated by metal coil winding, copper or aluminum etching, plating, printing and so on. In this paper, the comparison of above methods is conducted and the progress of the printing method and water-based conductive ink are emphasized. Water-based conductive inks are environmental-friendly, economic, high applicability, and are widely used in screen printing, gravure, flexible printing, inkjet printing, etc. Although starts late and the technology is not very mature, the RFID antenna prepared by printing method has many advantages, such as low cost, high precision, easy operation, variety of substrates, etc. Thus the printing has great potential applications on the fabrication of RFID antenna. Furthermore, water-based conductive inks used in ink-jet printing RFID antenna will be the first choice of printed RFID antenna.

Abstract: In order to compare different concentration modes' influence on the nano-silver particle size and morphology,we use three methods to refine nano-silver solution prepared in the lab as:1 centrifugal the solution directly,2 deposit the solution with acetone,3 centrifugal the solution with acetone added.Then test the solution processed with particle size distribution,UV-vis and SEM.The result shows that:the particle sizes of the nano-silver solutions enriched with the three methods are 162.5nm,163.5nm,164nm;the peak of the UV-vis absorption curve are 425nm, 426.5nm,427nm,we can see that different methods of enrichment have less influence on the nano-silver particles' size and morphology. Also the same conclusion can be drawn from SEM test.

Abstract: This study aims to analyse how inks of different colorant present unlike printing quality on selected substrates in inkjet printing. Applying Epson piezoelectric inkjet printer, experiments of printing pigment-based ink and dye-based ink on various substrates (coated art paper, porous photo paper, swellable photo paper, PP synthetic paper, xuan paper and PET-based coated film) were carried out respectively. Using digital microscope, the spreading, penetrating and distributing of ink drops were observed. Water fastness and light fastness were evaluated through aging test and water-immersing test, by measuring the decreasing of optical solid density. Taking the formula of inks and the composition of coating layers into consideration, contrast and analysis of print quality with different black inks on substrates of diverse support body were studied. The result demonstrates: Both dye-base and pigment-base inks present ideal optical density in special-purpose photo paper (swellable or porous type), exhibit distinct writing picture edge, and excellent water fastness and light fastness. While, coated art paper, PP synthetic paper, xuan paper and PET-based coated film, which shows relatively rough surface or weak ink absorbancy, are more suitable to use pigment-based ink.

Abstract: In order to study the dispersion and performance of tartrazine aluminum lake, 7 kinds of water-based resins are used to form disperse system. These systems are enviroment friendly (low VOC) and use edible yellow lake as colorant. If proper adjustment is added, these disperse systems can be made into ink and paint. The application field should be printing or coating on all the food or drug packages, toys and decorate materials, which will improve social safe level. Colorant, resin, wetting agent, co-solvent, emulsifier, and deionized water are mixed at certain ratio and pre-dispersed for 15min, then dispersed in GJ-2S high speed sanding mill for 3h. Size distribution, PDI, color characteristics (reflectance spectroscopy and color density), glossiness, abrasion performance, and stability are studied. Results demonstrate particle size of disperse system is 338.1~595.3nm (PDI<0.3) and changed to 428.6~551.2nm after 5 days or so. Reflectance spectroscopy is close to PANTONE standard yellow. Glossiness is referred as Gs(60°)≥32°. Viscosity is 0.2~2Pa·S. Relative stable disperse system is prepared.

Abstract: Water-based polyurethane forms continuous and dense film after fully drying. Ink is lowly absorbed by PU film, affecting drying rate and color reproduction. In order to improve the absorption of ink on PU film, PU/nano alumina compound was prepared by adding nano alumina in PU and stirring at high speed. PU ink absorption coating was got by being coated on the substrate. The influences of different content of nano alumina to transmittance of coating and solid density of color blocks were researched. The influences of soft and hard segment of PU to image resolution and water resistance were also researched. It can be seen that transmittance reduces when content of nano alumina increases. Droplets spread less when using PU of hard segment and image resolution and solid density are also higher. At the same time, water resistance of solid blocks is much better when printed on PU of hard segment.

Abstract: In order to evaluate the practical application effect of the self-made water-based coated paper inkjet ink and to study the influence factors, their printing performance and the influence of the printed material for printing performance is studied. The drying time of coated paper ink and ordinary water-based inkjet ink are measured and compared. Drying process of ink droplet is recorded by video contact angle tester. It is found that the drying rate of the coated paper ink is higher than the ordinary ink and the diffusion of the ordinary ink is severe. The coated paper ink and ordinary ink are printed, and it is found that the former can get better image detail and color reproduction for the picture of human’s face and inanimate object. The coated paper ink can also obtain a better reproduction of tone levels. Coated paper inkjet ink is printed on different coated papers, and the color densities are measured through red, green and blue color filter. The color strength and hue error are obtained to evaluate the color characteristics on different papers. It is concluded that the coated paper inkjet ink can obtain better color on the Henglian gloss coated paper, Sunbrite gloss coated paper and SPCO matt coated paper.