LCD printing (liquidcrystalprinting) is mixed with liquid crystal ink, so that the printed products are reversible or irreversible reaction printing mode.

A, crystal printing principle

The LCD is some organic matter in a certain temperature range, an intermediate state of. In this state, because the molecular arrangement with special orientation, molecular motion also have specific rules, so that the liquid has not only the fluidity of liquid and the surface tension, and some of the optical properties of crystals, such as the temperature is higher than the liquid crystal phase temperature limit, LCD will become common transparent liquid, loss of optical properties, such as low temperature below the liquid crystal phase temperature, liquid crystal becomes common crystal, loss of mobility. Liquid crystal in nematic liquid crystal, inElectronicsIndustry as a display material, cholesteric liquid crystals can be used for temperature indicator.

Liquid crystal by natural light and artificial light, and a wavelength color because of the refraction phenomenon strengthened reflex, as temperatures rise, the long wavelength colors into short wavelength colors (red, green, blue change from the colouring mechanism), the liquid crystal is formed as a result of reflective liquid crystal on a specific wavelength of light selective. Liquid crystal must be printed in black or dark background, the LCD can reaction between -10 ℃ ~ +70 ℃, +/-0.5 ℃ accuracy.

In printing, the liquid crystal filled microcapsules, adding ink printing, can prevent the liquid crystal's pollution, can play a role in protection, protection of life extension, for long term preservation, can improve the printability. Ink adding liquid crystal amount for the total ink amount 40%, do the capsule diameter in 10 ~ 30 microns.

Two, liquid crystal ink

Liquid crystal ink to join with crystallizability. Effect of liquid crystal in weak current and temperature, due to the lattice changes and shows the shading pattern and color. With this kind of ink.PackingDecoration can be produced with the temperature changes, if used for printed calendar, will with the seasons and different color temperature change.

Liquid crystal ink is mainly composed of a water-soluble resin, liquid crystal capsule, additives, binders, defoaming agent.

Three, crystal printing process

By screen printing or gravure printing can be used in liquid crystal ink, should according to use to determine the color temperature range and use of liquid crystal durability under consideration.

Key LCD printing technology is: can display liquid crystal color in different temperature, but also to a series of the color gamut value; liquid crystal microcapsules production technology is the key. Microcapsules to do small and uniformly, coat of transparent and thin, adding ink requirements of solvent, stable and reliable, long life; the printing process, to ensure that the liquid crystal microcapsules was not crushed; surface protection film. Liquid crystal ink printing most of the use of screen printing, screen printing process is as follows:

The 1 screen printing plate

General screen available nylon silk or polyester mesh. If a printing plate on the need to load a large quantity of ink, can be made of stainless steel mesh plate. Screen mesh size is generally 100-175. The diameter of the microcapsules in general between 10-30 μ M. Seihan by strong water resistance of the emulsion.

The 2 screen printing liquid crystal ink requirements

In terms of its function, LCD printing is mainly used for temperature and humidity, two aspects of color change.

The plate to be one with sufficient amount of ink, the best way not to fill the ink, to prevent foaming.

Because of the microcapsule ink easy edition plug, printing found clogging, foaming, should immediately stop exclusion, water thoroughly washed with alcohol.

The printing ink evenly, adequate attention should be paid to the substrate, printing ink is insufficient, will affect the effect of color.

The printing pressure can not be too large, to prevent the crushed LCD capsule, will also reduce the effect of color.

The printing color to choose black or dark tone. The colour of the available water soluble ink, can also be used organic solvent ink. After printing ink film must be fully dry, no organic solvent residue.

The printing ink layer should be smooth, ink layer thickness should be controlled at 15-35 μ m, ink layer is uneven or too thin will reduce the color effect.

The printing sequence can be used to black (or dark color) printing ink color, then the liquid crystal ink printing the desired pattern; also be the first to use liquid crystal ink printing thin foundation, and aqueous ink (or dark color) printing ink required negative patterns are covered, can improve the color effect.

The best printing surface coating varnish or adhesive protective film temperature tolerance in order to protect the ink layer and improve the wear resistance, gloss.

3 after drying

The best way to dry naturally dry, also can use 40 ℃ warm air drying, must not be high temperature rapid heating.

③ print dumps do not stress, cutting is not pressure.

Main uses and characteristics of four, LCD printing

Liquid crystal ink does not use pigment, with small thixotropic characteristics, good leveling etc.. Mainly used in thermometers, automatic temperature recorder, detector temperature display substrate for printing. Are you thereAdvertisement,TrademarkLabel, substrate applications such as arts and Crafts Ornament color change is very extensive, printed calendar picture, the picture will bring out different colors in the four seasons different temperatures; on some heat on the product, according to the pattern of change color, quality change of loading goods out, such as the candy wrappers on the bright picture become dark, it should be candy eaten as soon as possible; LCD printing can also be used as storage temperature cue card. Foreign LCD printing tape as a disposable temperature tester. With the development of society, the liquid crystalPrintingThere will be more wide application fields.