What kind of wax powder is best to add to the screen printing ink? In the process of printing, there will be many problems, such as viscosity, fluidity, thixotropy, plasticity, fineness, dryness, etc., need additives to improve and optimize product performance, so what kind of wax powder is the best suitable?
1. Viscosity. Viscosity is the resistance to fluid flow, also known as the coefficient of internal friction or viscosity. If the viscosity of the ink is too high, it will not be easily transferred to the substrate through the silk screen, causing printing difficulties and incomplete imprints; if the viscosity is too low, the imprint will expand, affecting the printing quality, and even causing waste.
2. Mobility. Mobility is a measure of the flow properties of a fluid. The fluidity of ink can be regarded as the degree to which a certain amount of ink flows naturally on a flat surface within a certain period of time without external force. The fluidity of the ink is generally controlled at 30-50mm. The fluidity of the ink is large, the imprint is easy to expand, and the thin lines with small gaps are easy to merge; the fluidity is small, the imprinted lines are easy to break, the ink is short, and the printing is also difficult.
3. Thixotropy. Thixotropy refers to the property of fluid that causes changes in flow properties under the action of external forces. For example, in the process of screen printing, the ink thickens after a certain period of time, and the reversible phenomenon of thinning after stirring can be explained by the concept of thixotropy. Because the shape of the pigment particles in the ink is irregular, although a layer of binder is adsorbed, it is also an irregular particle. After a certain period of time, the pigment particles will contact or be very close to each other, and the attraction will be enhanced. The ink thickens and becomes sticky. This temporarily stable structure is quickly destroyed by external agitation, the attraction between particles is weakened, the fluidity is improved, the ink becomes thinner, and the viscosity decreases.
4. Plasticity. Plasticity refers to the property of fully or partially retaining its deformation after being deformed by external forces. Screen printing ink is a thick suspension colloid between fluid and semi-solid, so it has both fluidity and plasticity. Low levels of pigments and other solid materials result in thinner inks and less plasticity.
5. Drawability. Due to the large molecular weight and strong viscosity of the binder in the ink, when the printing plate is lifted, many ink filaments appear on the back of the screen, which is called drawing. This is a taboo phenomenon in silk screen printing. It is not only easy to stain the printed matter and screen, but also makes silk screen printing impossible. Therefore, the screen printing ink is required to have the basic performance of no wire drawing during the printing process.
6. Dryness. The requirements for drying performance of silk screen printing are: the ink can not dry the conjunctiva for a long time on the silk screen, and after printing, it is required to be as dry as possible on the substrate. When multi-color continuous overprinting, the drying performance of the screen printing ink is more demanding.
Founded in 2002, Nanjing Tianshi has always focused on the development and application of wax additives, creating a whole industrial chain from the refining, oxidation, grafting, esterification and saponification of upstream raw waxes to the emulsification and micronization of downstream polymer waxes. .
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