Ink is light – resistant to discoloration and discoloration

Ink in sunlight, its color and brightness will vary in varying degrees of change, absolute light resistance and do not change the tone of the ink is not, in strong sunlight, all ink color will produce varying degrees of change. There are two types of change.

Fade: under the action of sunlight ultraviolet ray, ink light resistance is poor, lost the original bright color, the color becomes pale gray. Especially light color ink and four-color set printing when yellow and red two colors fade faster, and cyan and ink fade slower.

Discoloration: as opposed to printing ink black discoloration, the color change under the action of sunlight is dark, the color has also changed, people call this change discoloration.

Effect of emulsification

Offsctdruckmasenten printing plate cannot be separated from wetting the blank part of the plate, offsctdruckmasenten is the first water on the ink, water will inevitably appear emulsifying phenomenon. Ink emulsion color will be attenuate, but, after the evaporation of water can restore the original color, so the greater the water, the greater the amount of emulsion, will cause discoloration. In particular, the degree of emulsification of completely different ink tone together, the phenomenon of discoloration is particularly prominent.

Paper properties paper surface smoothness

Paper surface smoothness and imprinting copy has a close relationship, not smooth paper often need greater pressure, in order to make the ink and it has a good contact. Such as printing ink viscosity, liquidity, maintain a certain amount of ink film thickness, increasing pressure often makes molecularly imprinted spreading area, at the same time, the paper dips in place, but still poor contact, such as: coated paper and newsprint in the same plate printed imprinting effects have bigger difference, can obviously contrast different print effect.

Absorbability of paper

Paper, also the size of the absorbent and replication effect has a direct relationship, usually in the printing quality of a material is loose sheets of paper, if ink liquidity, low viscosity, the paper will absorb more ink layer connection, if the wool stoma diameter greater than the diameter of the pigment particles, then, even the pigments are inhaled, the saturation of imprinting decreases. Need to increase ink layer thickness appropriately. However, to increase the thickness of the ink layer, at the moment of embossing will cause “spread”, affect the effect of imprinting copy. Absorbability of small paper, can make most of the ink film appears on the surface of the paper, so that the imprinted ink layer has a good saturation.

Paper permeability paper permeability is large, will make the ink layer thickness thin, paper surface pores are large, but also make part of the pigment particles were infiltrated into the paper at the same time, so there is a sense of color. To this end, the use of a rough surface, loose texture of paper, and ink fluidity and large paper, to pay attention to color.

Pigment is not resistant to heat

Ink in the drying process, light fast – drying rubber printing ink is mainly conjunctiva – oxidation drying. Offset printing ink drying before there is a fixed phase, ink oxidation polymerization is exothermic reaction, drying too fast will give off a lot of heat, if the heat is released slowly, it will not make heat pigment color. For example: gold color ink darkens and loses its original luster.

At the time of printing, the printing sheets piled up into stacks, because stacked too much, the middle part of the printing ink oxidation polymerization exothermic reaction, heat is not easy to send out, too high temperature in the middle part of the more discoloration.

Dry oil has a light effect

Color ink belongs to cool tone, light yellow, emerald green, lake blue and other color ink, do not use red dryness oil, because red dryness oil itself with a deeper purple, will affect the color of light ink.

The white dryness oil appears white, but the conjunctiva is pale brown after oxidation. If the amount of white dryness oil is too much, the print will be yellowish-brown when dry, while the color of the dark ink such as green, black and purple with red dryness oil will not be greatly affected.

Ink is not alkali – resistant

Printing paper PH value =7, neutral paper is the most ideal, the general inorganic pigments produced by the ink acid, alkaline is poor, organic pigments acid, alkaline is better, especially the medium blue, dark blue ink will fade with alkali. Alkali medium yellow in color to red, electrochemical aluminum foil stamping, India will become the ancient yellow gold in alkaline substances, there is no gloss, weak alkaline paper more, often encountered in printing binding post-production contains alkaline adhesives, if packing decoration printing product is alkaline substance such as soap, soap, washing powder and so on, all want to consider the alkali resistance, resistance to saponification of ink performance.

Impact of storage environment

Most printing products for a long time storage, will inevitably show the phenomenon of yellow, the reasons for the following several aspects.

 Paper fiber contains lignin and discoloration. Newspapers printed on newsprint are most likely to turn yellow and brittle.

Offset printing four-color dot overprinter color printing products, most in the sunlight, the weather, the wind and rain, outdoor high temperature erosion, and so on, because the pigment is not light resistant, heat resistant, and color or fade.

The factors of color change in printed matter are varied and there is no product that can do everything. Just like this paper suitcase, its color may change over time. But at least it’s beautiful when we use it.