First, the screen printing process of glass

 

According to the principle of screen printing, the ink is printed on the surface of the glass, and then the curing method of the ink is used, and the printed pattern is firm and durable. The process flow is as follows:

 

Stretching net→sizing→drying→printing→developing→drying

 

↓

 

Flat glass → cutting → edging → cleaning and drying → printing

 

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Sintering

 

    1. Suitable for printing glass

 

According to the user's requirements, the glass can be cut into regular shapes or irregular shapes, then be edged and ground, then cleaned and dried for use. Special care should be taken here that there should be no water marks on the glass surface.

 

    2. Screen selection

 

The screen printing plate for glass printing is the same as the general screen printing plate, and the glass screen printing plate is made of synthetic fiber mesh, stainless steel wire mesh and natural fiber mesh. When printing general color materials, the above-mentioned screens can be used, generally using inexpensive synthetic fiber mesh; when used as gold and silver decoration, stainless steel wire mesh cannot be selected. The specifications of the wire mesh are generally 270 to 300 mesh.

 

3. Frame selection

 

At present, the frame that is relatively regular and has little deformation is an aluminum alloy frame, and its size should be larger than the pattern. The specific size should be that the outer edge of the pattern should be between 70 and 100 mm from the frame. In addition to selecting the frame, its strength is very important, the key is that the rigidity in the horizontal direction is sufficient.

 

4. The netting selects the screen and the net frame to combine the two. This is the stretch net. There are many ways to stretch the net. It can be manually, maneuvered or pneumatic. At present, the more advanced, high-quality screen version is a pneumatic stretcher. The requirement of the stretch net is that the tension is uniform, the web warp and weft are kept vertical, and the adhesive mesh is firm and cannot be slack.

 

5. Select photosensitive adhesive

 

Currently, commercially available photosensitive adhesives are dichromate, diazonium, and iron salts. Silk screen printing requires the photosensitive adhesive: good plate making performance and easy coating. The sensitometric spectrum ranges from 340 to 440 nm, with good developing performance, high resolution, good stability, easy storage, and economical, non-toxic and pollution-free. The requirements for printing on photosensitive materials are: the printing film formed by the photosensitive material is adapted to the performance requirements of different kinds of inks, has a considerable printing durability, can withstand the scraping pressure of the scraping plate a certain number of times; the bonding force with the screen is good, when printing Does not produce a film release failure; easy to peel, which is conducive to the recycling of the screen plate.

 

6. Printing version

 

After selecting the above materials, the photosensitive adhesive is applied in the dark room; the requirements are uniform and then dried, and it is generally required to be applied twice. The printing plate is required to be exposed on a cold light source printing machine, and the exposure time is determined according to the pattern, generally between 12 and 30 minutes. Screen printing screens are produced after exposure and development.

 

7. print

 

There are several types of flat glass printers: manual, semi-automatic and fully automatic. The manual press is suitable for small-volume, small-size flat glass. The semi-automatic and fully automatic printing machine is suitable for printing in large quantities and large specifications, and has the advantages of accuracy and speed. The largest semi-automatic press can print glass of 2000 x 1500 mm size. Fully automatic printing machines are generally used for the printing of automobile windshields, and several companies abroad can provide such equipment.

 

    8. Ink

 

Inorganic glass screen printing uses two kinds of inks, one of which is that the inorganic pigments are ground to a certain degree of fineness. Adding acrylic resin, the screen is printed on the surface of the glass, and it needs to be baked at high temperature for 1-2 minutes. The ink layer and the glass surface are melted together, and the fastness is excellent. The heat resistance temperature of this ink is above 600 °C. However, because this screen printing process is costly and complicated, it is rarely used in the screen printing industry. The other is an inorganic glass ink which uses a polymer compound as a binder. Both the amino type and the epoxy type need to be baked, and the domestic market is extensive. The applied ink is baked at l300 ~ l 400 ° C for 30 min after screen printing, and the heat resistance temperature of this ink is relatively low. However, the baking time is longer, the ink has good fastness and hardness, and the brightness is also very good, and can resist the corrosion of low concentration electrolyte and solvents such as ethanol, acetone, benzene and cyclohexanone.

 

    9. sintering

 

Glass is an amorphous inorganic material that softens as the temperature increases, and when heated to the softening temperature of the glass, the glass deforms. The glass glaze is decorated on the surface of the glass by silk screen printing, and needs to be fixed to the glass surface by high temperature sintering, but the sintering temperature must be lower than the softening temperature of the decorative glass to ensure that the decorative glass is not deformed. Generally, the glass glaze has a sintering temperature of not higher than 520 ° C, and is usually controlled at 480 to 520 ° C. Low-temperature glass glazes are produced by several domestic manufacturers and the prices are relatively low. Several foreign companies can also provide similar products, but the price is one to twenty times different from that of domestic ones. Domestic consumption levels have not yet reached the level of using such glazes, but the glazes provided abroad are indeed much better than the domestic colors and levels.

 

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