What are the common problems in glass screen printing?

1.Paste

Paste plate,also known as blockage,refers to the phenomenon that the through-hole portion of the screen printing plate cannot transfer ink to the substrate during printing.The appearance of this phenomenon will affect the printing quality.In the printing process,the viscosity of the ink is increased to cause the paste.The main reason is that the ink solvent on the screen printing plate evaporates,resulting in an increase in the viscosity of the ink and a phenomenon of sealing.If the printed graphic area is relatively large,the ink on the screen printing plate consumes a lot,and the paste phenomenon is less.If the image area is small and the ink consumption on the screen printing plate is small,it is easy to cause a paste.

2.The ink is not fixed firmly on the glass

When printing on glass,it is very important to perform strict degreasing and pre-treatment inspection of the glass before printing. When the surface of the glass is attached with grease,adhesive, dust, etc., it cause the poor performance of ink bonded to the glass. 

3.Inaccurate ink

The thickness of the ink film is not uniform.In terms of ink,the ink is poorly formulated, or the ink that is normally blended is mixed with the ink.When printing,the ink expands and softens due to the action of the solvent,and the mesh that should be permeable to the ink is blocked.The action of the membrane prevents the ink from passing.If the tip of the front end of the ink return plate is damaged,a trace will appear along the moving direction of the squeegee.Furthermore,the unevenness of the printing table also affects the uniformity of the ink.The ink layer of the convex portion is thin,and the ink layer of the concave portion is thick.This phenomenon is also called unevenness of ink.In addition,if the back of the substrate or the printing table is dusty,the above failure may occur.

4.Pinhole phenomenon

Pinhole phenomenon is the biggest headache for workers engaged in glass screen printing.There are many reasons for pinholes to occur, many of which are currently unexplained,and some are quality management issues.Before the official printing,the screen should be carefully checked to eliminate the dirt on the plate.The glass plate should be pre-treated before printing to make the surface clean and print immediately.If the glass is processed,it will not be printed immediately,and it will be contaminated again.Pay special attention to the fact that when the glass is moved by hand,the fingerprint of the hand will also adhere to the printing surface, and pinholes will be formed during printing.

5.Bubbles appear

The glass sometimes has bubbles on the ink after printing. The main reasons for the bubble are as follows: 1. The substrate is poorly printed before printing. The surface of the substrate is attached with dust and oil stains; 2 bubbles in the ink. In order to adjust the ink, when adding solvent and additives for stirring, some bubbles will be mixed in the ink. If left unattended, the ink with low viscosity will naturally defoam, and some inks with high viscosity will not be naturally defoamed. Some of these bubbles are naturally removed during printing due to the transfer of ink, and some are becoming larger and larger. 3 The printing speed is too fast or the printing speed is uneven, and bubbles are also generated. The printing speed should be appropriately reduced to maintain the uniformity of the printing speed.

6.Electrostatic failure

The electrostatic current is generally small,but the potential difference is very large,and the phenomenon of attraction,repulsion, conduction, discharge, etc. can be adversely affected by screen printing.The screen at the time of printing heats the rubber portion and the screen due to the pressure scraping of the blade rubber.If the screen itself is charged,it will affect the normal inking and cause blockage failure; it will be sucked by the screen at the moment of the output of the substrate.

7.Print size expansion

The main reason for the increase in printing size is that the viscosity of the ink is relatively low and the fluidity is too large;the size of the screen printing plate is enlarged during the production,which is also the cause of the enlargement of the printing size.

8.The printing plate leaks ink

Part of the film leaks ink, which is called ink leakage failure.The reason is: a part of the scraper is injured;the pressure of the ink is large;the gap between the plate and the glass is too large;the frame is deformed greatly, and the partial printing pressure is not enough:The ink is not uniform;the screen is too fine;the printing speed is too fast.If dust is mixed on the glass and in the ink,and printing is performed without treatment,the film may be damaged by the pressure of the squeegee;the pinhole may be caused by insufficient exposure during plate making, and the film may be leaky.

9.The image part and the dark part are spotted

The ink is a speckle-like imprint of the graphic part and the dark part of the glass surface,which impairs the printing effect.Glass screen printing is easy and produces this phenomenon.The reasons are as follows:the printing speed and the drying of the ink are too slow;the ink layer is too thin; the ink thixotropy is large; the influence of static electricity; the pigment dispersion in the ink is poor, and the particles agglomerate and appear color due to the polarity action of the pigment particles. Dot blot.

10.Image distortion

The printing press applied to the printing plate by the squeegee can make the line contact between the printing plate and the printed matter,and it should not be exceeded.If the printing pressure is too large,the printing plate will contact the inside of the substrate,which will cause the screen to expand and contract,causing the printed image to be deformed.Screen printing is one of the smallest printing methods in various printing methods.If we forget this,we can't print good prints.If the pressure cannot be printed without increasing the pressure,the gap between the layout and the glass surface should be reduced,so that the pressure of the squeegee can be reduced.

At present,glass screen printing technology is transforming into a high-tech,high-tech value-added processing field.Products including touch screens,liquid crystal substrates,and solar photovoltaic substrates mentioned above have gradually become an integral part of the current electronic information products field.It is believed that over time, glass screen printing technology will provide more support for the glass industry and even electronics,construction, energy and other fields.