Comparison of screen printing inks

推薦連結:洗衣機不能脫水怎麼辦

In this paper, the performance of screen printing ink and other printing ink was tested. The results show that: compared with other printing inks, screen printing ink has higher viscosity, ink layer thickness and ink transfer rate. Today, the editor of China paper network takes you to start with screen printing and introduce the related contents in detail.

Key words: screen printing ink / ink performance / ink layer thickness

Screen printing is one of the main printing methods in the process of hole printing. As well as screen printing, there are other printing methods which belong to hole printing, such as transcribing printing, typewriting stencil printing, hollow out printing and spray printing. Screen printing is an old printing method, also known as silk paint printing, silk leakage printing, paste yarn printing. Flat, convex and concave printing methods all transfer the ink to the surface of the substrate to realize the copy of the text; Screen printing is a printing method that the ink passes through the screen holes of the printing plate to make the ink Miss printing on the surface of the substrate. Therefore, screen printing ink types available more and more, substrate is not limited to paper, metal, plastic, wood can be screen printing. With the continuous expansion of screen printing ink and its application, it is very important to study the performance of screen printing ink. This paper analyzes the characteristics of screen printing ink by comparing screen printing ink with other inks.

theoretical analysis

According to Newton's law of viscosity, we can know formula (1)

τ=η D ①

Among them:

τ—— Applied to the ink shear stress;

η—— A constant independent of shear velocity is called viscosity coefficient;

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

When the fluid is under the action of external force, it does not start to flow immediately. It must start to flow after the applied external force reaches a certain degree. Such a fluid is defined as a plastic fluid, and its mathematical expression is formula (2)

τ=τ 0+ η D ②

τ 0 is the minimum shear stress value that the external force must overcome the internal molecular structure of the fluid to make the fluid flow.

Screen printing ink transfer process is under the action of external force through the mesh to the substrate surface, ink (fluid) through the mesh to meet the formula 3.

Q= π r4 Δ p/8 η l ③

Among them:

Q -- ink transfer amount;

Δ P -- the pressure difference between the two sides of the screen, which is actually the scraping pressure;

R -- mesh aperture;

L -- screen thickness;

η—— Screen ink viscosity.

As can be seen from Formula 3, the amount of screen transfer ink is inversely proportional to the viscosity of the ink, and inversely proportional to the thickness of the screen. The thickness of the screen in the plate after the general no big change, this paper takes it as a constant. So the key factor affecting the amount of ink transfer is the viscosity of the ink.