Hole printing, relief printing, gravure printing and lithography are called the four major printing techniques. Screen printing is one of the main printing methods in hole printing.Ink Comparison For Screen Printing

       As well as screen printing, the printing methods of hole printing include transcription printing, typing wax printing, hollow printing and spray printing. Ink Comparison For Screen Printing

       Screen printing is an ancient printing method, also known as silk paint printing, silk leakage printing and yarn sticking printing. Flat, convex and concave printing methods transfer the ink to the surface of the substrate to realize the reproduction of graphics and text; Ink Comparison For Screen Printing

     Screen printing is a printing method in which the ink passes through the mesh of the printing plate and makes the ink Miss printing on the surface of the substrate. Ink Comparison For Screen Printing

       Therefore, there are more and more kinds of inks available for screen printing, and the substrate is not limited to paper. Screen printing can be carried out for metal, plastic, wood, etc.Ink Comparison For Screen Printing

      With the continuous expansion of screen printing ink and its application range, it is very important to study the performance of screen printing ink. Ink Comparison For Screen Printing

       This paper analyzes the characteristics of screen printing ink by using screen printing ink and other inks to carry out printing experiments and compare the performance of ink.Ink Comparison For Screen Printing

theoretical analysis

According to Newton’s law of viscosity, equation ① can be known

τ=η D ①

Of which:

τ—— The shear stress applied to the ink;Ink Comparison For Screen Printing

η—— The constant independent of shear velocity is called viscosity coefficient;Ink Comparison For Screen Printing

D — rheological rate gradient, d = DV / Dr.

When the fluid is subjected to external force, it does not start flowing immediately. It must not start flowing until the applied external force reaches a certain degree. Such a fluid is defined as a plastic fluid, and its mathematical expression is formula ②:Ink Comparison For Screen Printing

τ=τ 0+ η D ②

τ 0 is the minimum shear stress required by the external force to overcome the internal molecular structure of the fluid and make the fluid flow.Ink Comparison For Screen Printing

The transfer process of screen printing ink is to reach the substrate surface through the mesh under the action of external force, and the ink (fluid) needs to meet formula ③ through the mesh.Ink Comparison For Screen Printing

Q=πr4 Δ p/8 η l ③

Of which:

Q – ink transfer amount;Ink Comparison For Screen Printing

Δ P — the pressure difference between the two sides of the screen, which is actually the scraping pressure;Ink Comparison For Screen Printing

R — mesh aperture;

L – screen thickness;

η—— Screen ink viscosity.

     It can be seen from equation ③ that the amount of ink transferred (missed) from the screen is inversely proportional to the viscosity of the ink and inversely proportional to the thickness of the screen. Ink Comparison For Screen Printing

      The thickness of the screen generally does not change greatly after plate making, which is taken as a constant value in this paper. Therefore, the key factor affecting the amount of ink transfer is the viscosity of ink.Ink Comparison For Screen Printing