Presswork the reason that printing ink colour changes and influencing factor
From;    Author:Stand originally
In the process that presswork is pressworking and deposits, regular meeting of its hue, lightness, degree of saturation produces change, no matter be monochromatic Chinese ink, still be the printing ink of color of two kinds of above, falling with explicit action inside, colour may become deep already, become possibly weak again. The presswork of high grade quantity measures a standard to be: The Chinese ink lubricious around of a batch of products is deep weak should agree, colourful, of the Chinese ink lubricious hue that should accord with prospectus at the same time and Chinese ink color deep weak. The factor that affects presswork color change has a lot of, have the following sides roughly. Printing ink is not able to bear or endure smooth become angry and fade reason printing ink is below solar illuminate, its colour and shining can different level produce change, be able to bear or endure absolutely smooth and changing tonal printing ink is done not have, below strong solar action, the color of all printing ink will produce the change of different level. This kind of change can be divided for two sort model. 1. Fade: Below the action of sun's rays ultraviolet ray, printing ink light resistance is poor, lost original and bright-coloured colour and lustre, color becomes shallow to become hoar. When the printing ink of light color and 4 kinds of registering imprint, fizzle out especially and red two kinds of color fade faster, and cyan and Chinese ink color fade a few slower. 2. Become angry: Turn over with hue of fade of black of presswork printing ink, below solar action color changes greatly dark, colour also was changed, people is what this kind of change says become angry. Emulsification pressworks to offset print of print colorific influence forme cannot leave to use part of blank of wet forme of fountain solution embellish, offset print is Chinese ink goes up after sailing upstream first, appear with respect to hard to avoid with water show emulsion. The colour and lustre after printing ink emulsification can be decreased weak, but, can restore original colour and lustre however after moisture evaporates, reason moisture is bigger, emulsification amount is larger, can cause become angry. Especially the lubricious Chinese ink that emulsification degree differs completely is moved together, the phenomenon that become angry is highlighted particularly. The relation with the property of paper and duplicate print 1. The exterior smoothness of paper. Paper surface smoothness and print are duplicate have affinity, not flowing paper face often needs greater pressure, ability makes printing ink and it has good osculatory case. Hold certain amount like ply of layer of printing ink viscosity, fluidity, Chinese ink, increase pressure to often make area of print spread out increases, in the meantime, the small sunken position of paper, still contact however undesirable, for example: Art paper and newspaper imprint in same forme place the print effect that come out has bigger difference, contrast of OK and apparent ground gives distinct duplicate effect. 2. The absorbency of paper. The absorbefacient size of paper, also have immediate concern with duplicate effect, pressworking normally when the paper with loose quality of a material, if printing ink fluidity is great, viscosity is small, paper can draw material of more join of printing ink layer, if the smuggling of wool stoma is more than the diameter of painty grain, so, also meet even dye by inspiratory, this makes the degree of saturation of print decreases. Need raises ply of Chinese ink layer appropriately. But, increase ply of Chinese ink layer, can cause again however in the instant of embossing " spread out " , influence print is duplicate the effect. The paper with small absorbency, can make the much of Chinese ink film appears in paper surface, make layer of print Chinese ink has better degree of saturation. Of paper osmotic osmotic to colorific influence paper big, can make ply of Chinese ink layer is decreased thin, paper surface pore is big, still can make a part painty grain at the same time by infiltration paper inside, consequently colour and lustre has decrease weak feeling. For this, use surface is rough, the paper with loose quality of a material, and printing ink fluidity big paper, want to notice to become angry. Painty not the influence printing ink of heat-resisting is in dry process, light is wash-and-wear model offset print brushs printing ink is in order to oxidize conjunctiva dry give priority to. There is a solid to wear before offset print printing ink is dry level, the oxidation polymerization of printing ink is exothermic reaction, dry too fast when can emit a lot of quantity of heat, if quantity of heat sends out slow, can make not the dye of heat-resisting becomes angry. For example: Printing ink of golden light color pales, lose original luster. Pile up in what the printed sheet on paper stage closes to become a battlements when pressworking, because pile up too much, the exothermic reaction of polymerization of oxidation of printed sheet printing ink of intermediate place, quantity of heat sends out not easily, the place that temperature crosses to put an inter high becomes angry more. The affects light light color printing ink that dry oil becomes angry to print belongs to cool color to move, weak yellow, emerald green, lake is blue wait for a lubricious Chinese ink, do not use red dry oil, because of red dry oil its itself contains deeper amaranth, meeting influence moves the color of light Chinese ink. White dry oil looks show white, but show after oxidation conjunctiva fallow, if white dry is oily dosage is more word, print dries up can meet have slant Huang Zong's lubricious likelihood, and saturate printing ink uses red dry oily color to won't get like green, black, purple bigger impact. Printing ink not alkali resistance affects black-and-white paper PH=7 to print colorific, submitting neuter paper is optimal, general inorganic pigment produces the printing ink that come out acid-proof, alkalescent poorer, organic pigment is acid-proof, alkalescent better, especially in blue, deep La Mo is encountered alkaline can fade. Huang Yu alkaline color turns into in slant red, iron imprinted report to change aluminum foil, imprint gold encounters basic material to be able to turn Gu Huang into color, without glossiness, often paper slants alkalescent more, pressworking later period is bound make encounter contain alkalescent adhesive, if pack decorate to presswork,the product is to pack basic material to wait for material like soap, toilet soap, washing powder, the alkali resistance that should consider printing ink, be able to bear or endure the function of saponification, sex of alkali resistance of peacock blue printing ink is better. Of presswork deposit reach use process to become angry mediumly element great majority pressworks the product is deposited for a long time, can present the appearance of extensive yellow, the reason has the following sides. 1. The fiber in paper contains lignin much and become angry. Be like: Newspaper black-and-white press runs the most easily yellow, and hair is fragile. 2. Offset print the color of overprint of 4 kinds of sites pressworks product, great majority falls in the illuminate of sun's rays, after a considerable period of time, wind blows drench, the high temperature outdoor is eroded etc, because dye is not able to bear or endure smooth, not heat-resisting, and become angry or fade.

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