Know the LCD ink

The liquid crystal ink in the 1970s originated in the United States, then developed rapidly in the United States and other countries won, to expand its scope of application won benefits. In recent years, China is also gradually open the LCD ink applications.

With the diversification of specialty printing and printing processes progress of science and technology demonstrated strong vitality and broad prospects for development. In the field of specialty printing supplies liquid ink has been used to on product packaging and printing products, liquid crystal ink for its unique way of coloring, printing and special effects become a wonderful work in specialty printing, it has aroused concern.

Understanding and additives liquid crystal of the liquid crystal ink ink <br> <br> belongs sensitive ink, the water-soluble resin as a main component, the liquid crystal capsules, binder aids, defoamers, is enclosed in microcapsules and the like dispersed in connection compound of preparation. The liquid crystal ink does not constitute a color image by a pigment, and it is a kind of liquid crystal which causes changes in the alignment molecule direction caused by the liquid crystal temperature in the ink layer, thereby selectively reflecting visible light of a specific wavelength and absorbing optical properties of other wavelengths of light. A special ink that exhibits color changes. When the liquid crystal is irradiated with natural light, artificial white light, and color light of a certain wavelength, the reflection increases with temperature, and changes from a long-wavelength color to a short-wavelength color (i.e., changes in red, green, and cyan) due to the refraction phenomenon. The color rendering principle of the liquid crystal is due to the selective reflection of the liquid crystal to light of a specific wavelength.

Usually liquid crystal can reflect a 100 ~ 700 °C, the accuracy is 0 50 °C. Since the molecular arrangement of the liquid crystal is not as strong as the crystal structure, it is easily influenced by external stimuli such as electric field magnetic field, temperature, stress, and adsorption impurities to change various optical properties. The liquid crystal ink is applied to the liquid crystal. This feature.

Since the liquid crystal is an organic compound between the liquid and the crystal, it cannot be directly added to the binder like a normal ink. Instead, the liquid crystal is wrapped in microcapsules and then mixed with the binder to make a microcapsule ink to prevent contamination by other substances and to ensure the color rendering effect. However, the microcapsules in the liquid crystal ink are different from the microcapsules in the foam ink fragrance ink. The microcapsules in foamed inks and fragrance inks require no breakage at the time of application, but under certain conditions after printing, the heartwood in the microcapsules is broken up and released.

However, the microcapsules in the liquid crystal ink are used to fix the liquid crystals in the capsules in the ink layer through the connecting material, and the microcapsules are required to not only pass through the printing plate smoothly, but also must have permanent sturdiness. In addition, LCD ink does not need to process any material. It is a kind of transparent "clean ink. Liquid crystal microencapsulation has the advantages of preventing the contamination of the liquid crystal itself, prolonging the service life, facilitating long-term preservation, improving the adaptability of EPN, etc. The amount of liquid crystal added in the ink is 40% of the total amount of ink, and the microcapsules Diameter between 10-30um.

Technical requirements for liquid crystal ink printing Liquid crystal ink printing refers to printing with inks doped with liquid crystals, so that the printed products have a reversible reaction or an irreversible reaction. The key to liquid crystal printing technology is the ability to display brightly colored liquid crystals at different temperatures. And in the color gamut to make a series of liquid crystal microcapsules is also a key requirement for microcapsules to do small and uniform. Wall is transparent and thin. Incorporation of ink requires stable, reliable solvent resistance and long life: during the printing process, the liquid crystal microcapsules are not to be crushed; the surface is covered with a protective film.

From the printing point of view, liquid crystal ink can be screen or gravure printing. To reduce the damage to the capsule during the printing process, screen printing is often used. For the selection of the screen, a nylon mesh or a polyester mesh may generally be used. If necessary, stainless steel mesh plate can be used. The diameter of the microcapsules is generally between 10 and 30 μm, so the choice of mesh size should be based on the diameter of the ink microcapsules and the thickness of the ink layer. Usually the mesh size is 100 to 1,75 mesh. The printing material for printing is preferably a paper that absorbs water, and synthetic paper is also suitable. Since the screen liquid crystal microcapsule ink is water-soluble, the photosensitive resist which has strong water resistance should be used when making the plate.

After printing and printing, it should be noted that in order to improve the liquid crystal color optical effect, it should be printed on a substrate with a black or dark tone background color. It is best not to fill the ink halfway, and there is not enough ink on the printing substrate. Will affect the color effect; due to the micro-capsule ink is easy to block version, found in the printing blocking the net, blistering. To immediately stop the exclusion, wash thoroughly with alcohol; printing pressure can not be too large. In case of liquid crystal capsule rupture, reduce the color effect; printing methods available screen printing, offset printing, gravure: when using organic solvent ink. Must be fully dried after printing. Ink film should not remain organic solvents. Otherwise it reacts with the liquid crystal, affecting the color effect: the printing ink layer should be smooth and smooth, the thickness of the ink layer should be controlled to 20 ~ 30pm, the ink layer is not even or too thin will reduce the color effect; the printing sequence can be black (or dark color) Ink printing background color, then use liquid crystal ink to print the desired pattern. You can also use liquid crystal ink to print the thin substrate first, and then use the black (or dark color) ink to print the desired negative pattern. Can improve the color effect: the printed surface is best coated varnish or paste protective film to protect the ink layer gloss and improve wear resistance and temperature resistance; postpress drying is best for natural drying. Or about 40 °C warm air drying, can not be heated rapidly high temperature. Also, do not pressurize the printed matter when it is stacked, and do not apply pressure when breaking it.

LCD ink application market

Liquid crystal ink capsules can play a protective role, to avoid the liquid crystal contamination by the outside, improve the printability, prolong life, easy to long-term preservation. The unique function of LCD ink makes it have its own unique positioning in the printing market and has high added value.

Detection function. Mainly used in thermometers, thermometers, automatic temperature recorders, testing machinery and testing equipment and other temperature display requirements on the substrate. A few days ago, in the United States, hospital-use liquid-crystal printing paper was used as a one-time body temperature test agent. It can also be used as a relaxation card for testing the looseness of the human body and non-destructive inspection of materials.

Entertainment features. Mainly used for advertising, trademark labels, arts and crafts, medals, jewelry and other decorative items and security printing products. If used to print calendar pictures, the pictures will show different effects with the changes in the temperature of the four seasons. If printed into a children's album, they can change colors with children's pointing and touch, and improve children's reading interest.

Prompt function. Mainly used for trademarks, wrapping paper, etc. Posted on some similar to frozen foods and other heat-prone products. According to the changes in the color of the packaging pattern. Can understand the quality of the contents of the contents, such as candy on the bright paper screen becomes gray, you should eat candy as soon as possible. Otherwise it will melt. A liquid crystal pattern is printed on the container to show the temperature of the contents in the container. In expensive, afraid of heat, cold large items. LCD ink printing. Can be used as a reminder card to keep the temperature.

Temperature identification. Can be used for cold, warm appliances, indoor temperature signs. The temperature range is accurately predicted by the color change of the liquid crystal print. This technology can be used to control the temperature of greenhouse vegetable cultivation. Farmers can correctly adjust the temperature in vegetable greenhouses through the color change of LCD prints. This technology also has certain guiding significance for the control of the temperature of the printing shop and printing warehouse.
Anti-counterfeiting features. The use of the liquid crystal thermochromic characteristics, so that liquid crystal prints with anti-counterfeiting features, and now in the field of anti-counterfeiting packaging and decorating has played a great role.

LCD ink originated in the United States in the 1970s, and then developed rapidly in the United States, Japan and other countries. Its application is expanding. In recent years, China is gradually opening up the application market for liquid crystal inks, researching and overcoming technological bottlenecks such as liquid crystal display and liquid crystal microcapsule production. It is believed that the market for liquid crystal inks will be even broader in the near future.

Reprinted from: Printed in China