Several New Thermal Paper Introduction

1. Two-color thermal paper

The so-called two-color thermal paper refers to paper that can produce two different colors after thermal development. It consists of two heat-sensitive layers. The upper layer is a low-melting-point heat sensitive layer, and the bottom layer is a high-melting-point heat sensitive layer. When heated, the upper layer develops first to produce a color. When the temperature rises, the high melting point heat sensitive layer melts to produce a second color. This color is a mixture of the color that appears after the development of the high melting point heat sensitive layer and the color that appears after the development of the low melting point heat sensitive layer. For example, the upper layer develops red and the lower layer develops green alone, then the second color is black. As described above, although two colors can be produced, vivid colors cannot be produced. To this end, but also developed a clear layer of two-color thermal paper thermal layer. the bottom layer is a high melting point heat sensitive layer, sandwiched between the two with a layer of removal layer, the melting point of the material contained in the removal layer is close to the melting point of the underlying material, and when this material is melted and mixed with the upper layer, it can weaken the color of the upper developed image and even make it colorless, making the color of the underlying developed more vivid. This results in a clear color difference between the two-color images.

2. PTM Paper

thermal recording system has many advantages, such as: small size, low price, less supporting equipment, etc., but ordinary thermal paper also has many shortcomings, such as the surface is easy to scratch, the image is easy to be blurred by oil, detergent, etc. High surface gloss brings difficulties to the interpretation of recorded images. To overcome these shortcomings, people developedPTM paper (Plain Thermax), this thermal paper has the characteristics of ordinary paper. PTM paper consists of three layers: heat sensitive layer, bottom layer and paper base. The heat-sensitive layer is the surface layer: it has the ability to resist abrasion and pollution. A large number of organic dyes are added to this layer to reduce the appearance of scratches to the lowest point. In addition, some chemical substances conducive to ink solidification also reduce the probability of hot head scratches. The adhesive with special properties used on the surface improves the waterproof performance and has no adhesive feeling when touched by wet hands. In order to make images and characters easy to identify and interpret, the surface is matte. Underlayer: It has an effect on the optical density and resolution of the paper. In order to obtain higher heat sensitivity and good resolution power, an oily dye absorbent is added to the bottom layer to form a porous space with heat insulation effect, thereby preventing the energy loss of the thermal head. Paper base: In order to obtain the characteristics of ordinary paper, hard paper base must be used, and the thickness of paper base is about 70-90μm. The thermal performance and image stability of PTM paper are also greatly improved compared with ordinary thermal paper. For thermal paper, the dye particle size in the thermal layer has a great influence on the thermal performance. The smaller the particle size of the dye, the better the thermal performance. If the average particle diameter is reduced from 1.5 μm to 0.8 μm, 30% of the thermal head energy can be saved. PTM paper uses this technology, so it can get good images on low power fax machines.

The development of ordinary thermal paper is achieved by heating the reaction of leuco dyes with phenol compounds to generate color dyes. However, since this reaction is reversible, the image is often degraded when affected by plasticizers and oils. To this end,PTM paper adds compounds with epoxy functional groups to improve image stability.

in this system, the leuco dye of the heat sensitive layer cannot directly react with the epoxy compound, but can only react with the chromogenic dye, the product generated by the reaction of the leuco dye and the developer, and this reaction is irreversible. Therefore, the image attenuation is suppressed, and the stability of the image is enhanced.

3. Color thermal paper

color thermal paper, that is, printing paper that produces all colors by the action of heat. They enclose the chromogenic agent in microcapsules and then coat it on the surface of the paper to make colored thermal paper. Once the thermal effect is used for color thermal

the surface of the paper, the capsule then burst, according to the different heat and produce yellow, purple, dark red three colors.

4. transfer thermal paper

transfer thermal paper is a set of paper overlap, in the base paper(such as capacitor paper or polyester film with a thickness of about 6-10μm), and then pad a piece of white paper (the surface should be extremely smooth and high adsorption). When the thermal head contacts the paper surface, the ink is melted and transferred to the white paper. This heat-sensitive recording method can facilitate the direct use of plain paper on the facsimile machine without the use of heat-sensitive paper.