The Causes of the Appearance Quality of White Elastic White Printed Paste

The appearance quality of the printed elastic white glue is the external performance of its quality. It includes the appearance, delicateness, and flow properties of the printed elastic white mortar. The quality of the printed elastic white paste should be uniform and white. Viscous semi-paste, delicate balance, good fluidity, shiny surface, but the poor quality of the printing elastic white mortar often appears in the storage layered solidification, poor fluidity, flocculation water, viscosity is too large, into a paste body, Directly affect its quality, color, coverage, water resistance, leveling, coverage, gloss, color yield and other properties.

The appearance quality of the printed elastic white mortar is the external performance of its quality. It includes the appearance, delicateness, and flow properties of the printed elastic white mortar. Good quality and good quality printing white adhesive paste should have a uniform liquid appearance, white and thick semi-paste, fine balance, good fluidity, and shiny surface. The poor quality of the printing elastic white mortar often appears in the storage layered solidification, poor mobility, flocculation water, viscosity is too large, into a paste-like body, directly affect the quality, color, coverage, water resistance, leveling, Coverage, gloss, color yield and other properties.

There are many factors influencing the appearance quality of printed elastic white glues: printing materials such as resin (binder) wetting dispersants, thickeners, fillers and their formulations and production processes will affect it.

The Causes of the Appearance Quality of White Elastic White Printed Paste

1. Grease is the film forming material of printing elastic white glue. In the chemical polymerization reaction of resin, the temperature, time, reaction speed, heat preservation, stirring speed, and the addition of additives may cause incomplete chemical reactions due to various reasons. Too much monomer, resulting in poor chemical stability and physical stability, the resin will also occur coagulation and coalescence, resulting in layered white elastic paste, odor, poor adhesion, blocking mesh and other unstable factors. Therefore, the resin must have good chemical stability, storage stability, good elasticity, strong adhesion, soft and non-stick properties.

2, from the settlement speed (Stokes's law)

The sedimentation speed of the filler and the fineness of the abrasive are multiplied, that is, the greater the fineness of the filler, the faster the sedimentation speed of the filler is. Printing elastic white glue will divide water and layer flocculate in a short time. So the general fineness is within 15-20 inches. However, finer pigment particles merely retard sedimentation and cannot prevent sedimentation. Printable elastic white pastes are viscous liquids with non-Newtonian flowability and must be measured for viscosity using a rotational viscometer.

3, printing elastic white glue additives

The wetting and dispersing agent in the printing elastic white mortar can uniformly disperse all kinds of fillers and introduce a loose network in its composition, so that the filler particles can be suspended without sedimentation, and the viscosity of the slurry can be effectively reduced, so that the printed elastic white glue does not produce flocculation Sedimentation and sedimentation; the addition of leveling reduces the mutual containment of macromolecular chains, reduces the friction of the material and reduces the viscosity. Thickeners are more important for adjusting the appearance quality of printed elastic white glue.

4. Effect of printing elastic white glue production process

If the speed of the stirrer is too fast, the resin will be broken by high shear and the addition of dispersants, flow agents, thickeners, and other additives will lead to demulsification of the elastic white paste and the formation of gel particles. Control the production process time temperature and product fineness.

Method for controlling appearance quality of printed elastic white glue

1, choose the resin suitable for formula design requirements

Resin is the top priority in the formulation of printed elastic white glue. Different resins have different particle size distributions, chemical ion stability and mechanical stability are different, and water-in-oil, oil-in-water, and hydrophilicity are all different and have a great influence on the appearance. Therefore, when selecting the resin, it is necessary to fully consider the characteristics of the resin itself, especially the compatibility of the resin, so that the selection of fillers, auxiliaries, etc. in the process recipe can be integrated.

2, with a good dispersant, leveling agent

Leveling agents and dispersants produced by different manufacturers have different HLB values. The dispersant and leveling agent (water-based) with higher general HLB value will reduce the viscosity of the system; the different types of dispersed leveling agent will reduce the viscosity of the system and affect the resin as its HLB value increases. The bigger it is. Hydrophilic dispersing and leveling agents will improve the storage stability of the printed elastic white paste. The hydrophobic dispersing agent will improve the scrub resistance of the printed elastic white paste after its formation. Therefore, the use of hydrophilic and hydrophobic dispersing and leveling agents can effectively improve the storage properties of printed elastic white glue. If more dispersed leveling agents are added, their hydrophilicity and fluidity will be improved, but their water fastness will be reduced and their water resistance will be poor. If too little dispersed leveling agent is added, it will directly affect the quality of its appearance, so it should generally be controlled between 3% and 5%.

3, the rational choice of thickener, improve the performance of white elastic paste printing

At present, thickening agents commonly used in printing elastic white glues include polyacrylic acids, cellulose ethers, alkali-soluble acrylics and non-ionic associative polyurethanes.

Cellulose thickeners (mainly including hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose) have high thickening efficiency, good stability, but poor leveling, and can easily cause web marks in screen printing. , And have a certain impact on the gloss of the slurry. Polyurethane thickeners have a higher cost and are not used in printing elastic white pastes. Polyacrylic thickeners have good leveling properties, are not prone to web marks, do not affect the gloss of the slurry, have good water resistance and biological stability, and have good intermiscibility, resulting in the formation of molecular links between the particles. The resin-filler-resin forms a network structure to provide a high medium-high shear rate, so that the printed elastic white paste has a good rheology, so that the appearance of milky white fluid semi-paste.

The appearance quality of the printed elastic white glue is the first impression of the product to the customer. Therefore, it is very important to make the appearance quality of the printing paste. To control the appearance quality of the printing elastic white paste, it is necessary to design the resin, additives, fillers and other elements of the formula and use the correct production process.