Screen printing process of the hottest glass

Glass wire printing process flow

glass wire printing refers to the wire printing method with glass plates or glass containers as the main products. The use of glass has a long history in China. Even in modern times, glass still plays an important role in our life. At present, the financial crisis that originated on Wall Street in the United States has hit the nerves of the world like a "tsunami", and has had a certain impact on the economies of all countries in the world

since 2008, the soaring international oil price, the appreciation of the RMB and the reduction of export tax rebates have had a negative impact on the export-oriented enterprises of China's printing industry. The outbreak of the global financial crisis has made it worse for the printing enterprises that originally had low profits and difficult operations, especially the small and medium-sized packaging and printing enterprises. In addition, after the implementation of the new labor law, the increase of labor costs has increased the operating costs of Indian enterprises. In addition, the serious deposits of its downstream customers have led to the tension or even fracture of the capital chain, which has increased the operating difficulties of Indian enterprises. Therefore, Indian enterprises should rationally combine the actual situation of enterprises and product characteristics, and serve customers with the lowest production cost and the highest production efficiency. Under the conditions of both opportunities and challenges, the application of silk printing to glass products is undoubtedly a very effective response, which can increase market development and open up a variety of marketing channels

as a building decoration material, glass has the advantages of flat and transparent, can block wind and rain, and is easy to scrub. The printed glass is more popular for indoor and outdoor decoration, which greatly meets people's life and aesthetic needs. All kinds of beautiful patterns compete with each other, making the best of the best and surpassing nature. Now glass containers have begun to develop into medical supplies and industrial supplies. The high quality and quantification of glass products decorated with silk printing technology will become a new growth point of glass printing

I. silk printing process of glass

according to the principle of silk printing, ink is printed on the surface of glass, and then ink curing measures are adopted. The printed patterns are firm and durable. The process flow is as follows:

stretching → sizing → drying → plate printing → developing → drying

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

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sintering

1. Glass suitable for printing

cut the glass according to the user's requirements, which can be in regular shape or irregular shape, then reverse the edge, grind, clean, dry and wait for use. Special attention should be paid here that there should be no water stains on the glass surface

2。 Selection of silk

the screen printing plate for glass printing is the same as the general screen printing plate. The glass screen printing plate adopts synthetic fiber, stainless steel wire and natural fiber. When printing general pigments, the above silk can be used, and generally cheap synthetic fiber silk is selected; When it is used as gold and silver decoration, stainless steel wire cannot be selected. The specification of silk is generally 270 ~ 300 mesh

3。 Selection of frame

at present, the relatively regular frame with little deformation is 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 ~ 100mm from the frame. In addition, the strength of the selection box is very important, and the key is the sufficient rigidity in the horizontal direction

4。 Tau selects silk and frame, and combines the two, which is tau. There are many ways to stretch, including manual, motorized and pneumatic methods. At present, the more advanced one that can stretch the high-quality version is the pneumatic stretching machine. The tension is required to be uniform, the warp and weft lines should be vertical, and the glue should be firm without relaxation

5。 Choose photosensitive adhesive

at present, the commercially available photosensitive adhesives include dichromate system, diazonium salt system and iron salt system. The requirements for photosensitive glue in screen printing plate making are: good plate making performance and easy coating. The photosensitive spectrum range is 340 ~ 440nm, with good development performance, high resolution, good stability, easy storage, economy, sanitation, non-toxic and pollution-free. The requirements of printing on photosensitive materials are: the plate film formed by photosensitive materials meets the performance requirements of different types of inks, has considerable printing resistance, and can withstand the scraping pressure of the doctor blade for a considerable number of times; It has good adhesion with silk, and there is no film failure during printing; It is easy to peel, which is conducive to the recycling of silk plates

6。 Print

after selecting the above material, apply photosensitive glue in the darkroom; It is required to be uniform, and then dry. Generally, it is required to apply twice. Printing requires exposure on a cold light source printing machine. The exposure time should be determined according to the pattern, generally between 12 and 30 minutes. After exposure and development, a silk screen version is made

7。 There are manual, semi-automatic and full-automatic printing machines for printing

flat glass. The manual printing machine is suitable for small batch and small specification flat glass. The semi-automatic and full-automatic printing machine is suitable for large batch, large-scale multi chromatic printing, with the advantages of accuracy and speed. The largest semi-automatic printing machine can print 2000 × 1500mm size glass. Automatic printing machines are generally used for the printing of automobile windscreens, and several foreign companies can provide such equipment

8。 Ink

inorganic glass printing uses two kinds of inks. One is that the inorganic pigment reaches a certain fineness after grinding. Add acrylic resin and print it on the glass surface. It needs to be roasted at high temperature (above 600 ℃) for 1 ~ 2min. The ink layer and the glass surface melt together, and the fastness is excellent. The heat-resistant temperature of this ink is above 600 ℃. However, because this printing process is expensive and complex, it is rarely used in the printing industry. The other is inorganic glass ink with polymer as binder. Amino type and epoxy type need to be baked, and the domestic market is wide. The applied ink is baked at 1300 ~ 400 ℃ for 30min after printing, and the heat-resistant temperature of this ink is relatively low. However, the baking time is long, the ink has good fastness and hardness, and the brightness is also very good. It can resist the corrosion of low concentration electrolytes and solvents such as ethanol, acetone, benzene, cyclohexanone, etc

9。 Sintered

glass is an amorphous inorganic material, which softens with the increase of temperature. When heated to the softening temperature of glass, the glass will deform. The colored glaze of glass is decorated on the surface of glass through silk screen printing and needs to be consolidated on the surface of glass through high-temperature sintering, but the sintering temperature must be lower than the softening temperature of the decorated glass to ensure that the decorative glass does not deform. Generally, the sintering temperature of glass glaze is not higher than 520 ℃, which is usually controlled at 480 ~ 520 ℃. Low temperature glass glaze is produced by several domestic manufacturers, and the price is relatively low. Several foreign companies can also provide similar products, but the price is ten or twenty times higher than that of domestic ones. The domestic consumption level has not reached the level of using this kind of glaze, but the glaze provided by foreign countries is indeed much better than the domestic color and level

it is inevitable to improve the quality of decorative glass and the grade of glaze. Sintering equipment includes flame furnace and resistance furnace. Resistance furnace is divided into vertical hanging type and horizontal roller table type according to the hanging mode of glass. Vertical hanging sintering furnace has the advantages of small sintering deformation and yield of more than 95%, but the equipment is complex. If the horizontal roller table is not adjusted well, it is prone to large deformation and low yield. In addition, it is also feasible to use horizontal tempering furnace to produce decorative glass. The grade of the product is improved and the safety is guaranteed. It is an ideal sintering method

second, the silk screen printing process of glass is prone to faults

some of the silk screen printing faults are caused by a single reason, but more are the result of the cross influence of various reasons. This is what the operator should pay special attention to when judging the failure cause of glass fiber printing and taking corresponding countermeasures:

1. Paste plate

paste plate, also known as blocking plate, refers to the phenomenon that the ink cannot be transferred to the substrate during the printing of the through-hole part of the silk plate. The appearance of this phenomenon will affect the printing quality, and even fail to print normally in serious cases

① reasons for glass: the glass surface is not cleaned, and there are still dirt such as watermark, paper print, mimeograph, handprint, dust particles, etc. Thus causing paste

② reasons for workshop temperature, humidity and ink properties. The silk printing workshop requires to maintain a certain temperature of about 20 ℃ and relative humidity of about 50%. If the temperature is high and the relative humidity is low, the volatile solvent in the ink will evaporate quickly, and the viscosity of the ink on the silk will become high, thus blocking the hole. Industrial ash concrete hollow partition board jg3063 ⑴ 999 another point that should be noted is that if the shutdown time is too long, there will also be paste phenomenon, and the longer the time, the more serious the paste. Secondly, if the ambient temperature is low, the ink fluidity is poor, and it is easy to produce paste

③ reasons for silk screen printing. The prepared screen printing plate can be used only after it is washed with water and dried before use. If the plate is not printed in time after being placed for too long. In the process of preservation, dust will adhere to it more or less. If it is not cleaned during printing, it will cause paste

④ causes of printing pressure. During the printing process, too much embossing force will bend the scraper. The scraper is not in line contact with the screen printing plate and glass, but in face contact. In this way, each scraping can scrape the ink clean, leaving residual ink, which will cause a paste after a certain period of time

⑤ reasons for improper gap between screen printing plate and glass. The gap between the screen printing plate and the glass should not be too small. If the gap is too small, the screen printing plate cannot be separated from the glass in time after scraping. When the screen printing plate is lifted, a certain amount of ink is stuck on the bottom of the printing plate, which is also easy to cause board pasting

⑥ the reason of ink is that when the pigment and other solid particles in silk printing ink are large, it is easy to block the hole

in addition, the selected wire mesh and through-hole area are smaller than the particle size of the ink, which makes it difficult for the ink with coarser particles to pass through the hole and seal. The paste caused by the larger particles of ink can be solved from the time of manufacturing ink. The main method is to strictly control the fineness of ink

in the printing process, the increase of ink viscosity causes plate pasting. The main reason is that the ink solvent on the screen printing plate evaporates, resulting in the increase of ink viscosity and sealing. If the printing area is relatively large, the ink consumption on the screen printing plate is more, and the paste phenomenon is less. If the image and text area is small and the ink consumption on the screen printing plate is small, it is easy to cause paste. The countermeasure is to adopt the principle of adding ink a few times. The poor fluidity of the ink will cause the ink to paste when it does not pass through the silk. This situation can be solved by reducing the viscosity of the ink and improving the fluidity of the ink without affecting the printing quality. In case of a paste failure, appropriate solvent can be used for scrubbing according to the nature of the ink on the plate. The key of scrubbing is to start from the printing surface and wipe gently from the middle to the periphery. Check the printing plate after wiping. If there is any defect, it should be repaired in time. After repairing, the printing can be restarted. It should be noted that the plate film becomes thinner every time it is wiped. If there is a major defect in the plate film during wiping, it has to be printed with a new version

2。 Ink is not firmly fixed on glass

① when printing glass, it is very important to strictly degrease and pre-treatment the glass before printing. When grease, binder, dust and other substances are attached to the surface of the glass,