LCD ink composition characteristics and its market analysis (1)

In the field of inks, the temperature change materials for liquid crystals are currently of greatest interest to people. It mainly causes changes in optical properties through changes in the crystal lattice.

Composition and characteristics of liquid crystal
Generally, heating a solid substance to a melting point will turn it into a liquid. However, some substances with a special molecular structure do not change from a solid to a liquid, but first pass through an intermediate state. This kind of intermediate state, which is not an ordinary solid, a liquid, or a gas, is called the fourth state of the substance. Its appearance is a fluid turbid liquid with the fluidity and surface tension of the liquid, and is also unique to crystals. Optically anisotropic birefringence. This substance that can both characterize liquids and crystals within a certain temperature range is called liquid crystal and is generally classified into nematic, smectic, cholesteric, and heteromorphic types.

Nematic: When viewed with a polarizing microscope, many filament-like optical patterns can be seen. This liquid crystal still shows positive refraction, its viscosity is small, and it is rich in fluidity.

Smectic: The rod-like molecules form a layered structure, and the molecules are arranged parallel to each other. The molecular forces between the arranged molecular layers are relatively weak and easily slide between each other. Therefore, the smectic liquid crystal exhibits two-dimensional fluid properties and has high viscosity characteristics.

Cholesterol type: Most of them are compounds derived from cholesteryl alcohol. The liquid crystal forms a spiral structure as a whole and has birefringence properties. It is the main type of liquid crystal ink.

Shaped liquid crystal: It is divided into reentry liquid crystal and disc type liquid crystal. Reentry liquid crystals are liquid crystals that again exhibit the same phase during the phase transition. The discotic liquid crystal is a liquid crystal having a discotic molecular structure.

Liquid crystal is an intermediate state that certain organic substances are present in a certain temperature range. In this state, due to the special orientation of molecular alignment, there are also specific laws of molecular motion. If the humidity is higher than the upper limit of the temperature of the liquid crystal phase, the liquid crystal becomes an ordinary transparent liquid, losing optical properties such as the temperature lower than the lower limit of the liquid crystal phase temperature It will become ordinary crystals and lose fluidity.

Composition and process of liquid crystal ink

LCD inks originated in the United States in the 1970s. Later, as its technology matured and the printing market continued to expand, liquid crystal ink printing was rapidly developed in the United States, Japan, and other countries, and its application range was also expanding. The liquid crystal ink is a microcapsule structure ink type in terms of production methods. From the application point of view, it belongs to the category of temperature-sensitive thermochromic inks for anti-counterfeit printing inks, but in terms of the characteristics of liquid crystal inks, it mainly uses the characteristics of temperature-sensitive discoloration of liquid crystals. .

The liquid crystal ink is mainly composed of a water-soluble resin, a liquid crystal capsule, an auxiliary agent, a binder, and a defoamer. The liquid crystal ink is prepared by dispersing liquid crystals, additives and the like enclosed in the microcapsules in a binder. It changes the orientation of the aligned molecules by the temperature of the liquid crystal in the ink layer, thereby selectively reflecting the visible light of a specific wavelength, absorbing the optical characteristics of other wavelengths and showing a color change, instead of forming a color with the ink layer pigment. Graphically. When the liquid crystal is irradiated with natural light, artificial white light, and color light of a certain wavelength, reflection is strengthened due to the refraction phenomenon, and as the temperature rises, the color changes from a long wavelength to a short wavelength (i.e., changes in red-green-cyan), The color forming mechanism of the liquid crystal is due to the liquid crystal selectively reflecting light of a specific wavelength. The LCD must be printed on a black or dark background, and the LCD can now reflect -100 to +700 degrees Celsius. The accuracy is 0.50 degrees Celsius. Since the alignment of the liquid crystal molecules is not as strong as the crystal structure, it is easily affected by external stimuli such as electric fields, magnetic fields, temperature, stress, and adsorption impurities, causing various optical properties to change. Liquid crystal inks use this characteristic of liquid crystals.

Since the liquid crystal is an organic compound between the liquid and the crystal, it cannot be directly added to the binder like ordinary ink. In order to prevent the liquid crystal from being contaminated by its chemical substances, in order to ensure the color rendering effect, it is necessary to enclose the liquid crystal in microsphere capsules and then mix with the connecting material to make a so-called `microcapsule` type ink. The microcapsules in the liquid crystal ink are different from the microcapsules in the foaming and aroma inks. The microcapsules of the foaming ink are foaming agents (or low-boiling liquefied gases). Upon heating, the foaming agent in the microcapsules emits a large amount of gas (or a low-boiling liquefied gas expander) to increase the volume of the microcapsules to foaming. effect. In addition, pigments are added to the foaming ink, printed into various colored foaming graphics, and have dual functions of foaming coloration. The characteristics of microcapsules in scented inks are that they are not crushed and damaged during printing, but they are required to be easily broken by pressing and tearing with nails, pencils, etc. after printing into products, thereby achieving the purpose of emitting fragrance. The microcapsules in the liquid crystal ink are used to fix the liquid crystal in the capsule in the ink layer through the connecting material.