In screen printing, printing ink blowing a version by moving in a certain pressure through the screen plate, transfer to the substrates and the formation of a graphic.Therefore, scraping the version of the various indicators affect the printing effect.Due to the is a wide variety of substrates materials, and also not the same condition, can be roughly divided into flat and curved surface (including spherical), so, according to the different substrates and substrates surface shape, should consider the following factors when choosing a scraping version.
(1) scraper hardness ink transfer and graphic reproducibility is good or bad is related to the scraper hardness, generally in hard printed on printing, can use soft scraper, such by scrapping printing pressure can make layout and substrates full contact, in order to improve the printing effect.Instead, when printing soft substrates, with a hard scraper make good contact with the substrates, both in the same way.Because of there printing, printing material are different, the relatively smooth substrates generally choose a hard scraper, on the other hand, use a soft scraper printing effect will be better.Scraping board in India because of its certain pressure, scraper can produce certain bending, therefore, when using scraper, want to consider the bending fatigue and mechanical strength of scraper, scraper with a certain elasticity.Scraping board in India will be caused by friction heat at the same time, make its temperature hardness change, should pay attention to when choosing scraper material selection is not easy to deformation of the heated material usually scraper hardness should choose in the shore hardness of 60 to 90 degrees.
(2) the wearability of scraper Scraper, direct contact with silk screen plate because it is every time scrapping printing have friction (in silkscreen print run long up to tens of thousands of).Therefore require scraper has good abrasion resistance, lubricity and certain mechanical strength, so when scrapping printing can reduce friction, to ensure that the service life of scraper.
(3) the solvent resistance of scraper scraper in use to contact all kinds of printing ink and solvent, such as ethanol, gasoline, etc.In all kinds of rubber material to solvent affinity is not the same, or solvent ink scraper in contact have varying degrees of change, to return to the common is scraper hardness change, contact solvent volume expansion after deformation.If scraper expansion, can reduce the edge of the scraper, precision press will leak ink uneven and affect printing quality.Generally considered high hardness rubber crosslinking density is big, printing ink and solvent molecules are difficult to into rubber molecules, so expansion coefficient is small.Can consider when choose scraper in as far as possible under the premise of meet the requirements of printing, in order to make deformation is reduced to a minimum, can choose high hardness rubber scraper.
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