Примена органских пигмената у индустрији премаза
The proportion of organic pigments used in the coatings industry is rising. At present, about 26% of coating pigments are used. In recent years, with the rapid development of China's coating industry, new coatings have been continuously developed, and the proportion of high-grade coatings has increased. The demand for pigments is growing rapidly. Its variety and performance put forward more and higher requirements, which provides a good opportunity for the development of organic pigment industry.
Effect of organic pigments on coating properties
1. The size of organic pigment particles has a great influence on the color performance of the coating. On the one hand, it will affect the hiding power and tinting strength of the coating. In the range of pigment, the particle size will increase, and the hiding power of the coating will increase. When the pigment particles become smaller, the coating will increase in specific surface area. The tinting strength is increased and the pigment particle size also has an effect on the color shade of the coating. Generally, the particle size distribution is larger, the color is darker, and the color is brighter. The other is that the strength of the pigment also affects the UV resistance of the coating. When the particle becomes smaller, the specific surface area increases, the absorbed light energy increases, and is damaged. The degree is also increased, so the paint fades faster. The small amount of pigment is less gravity, and the coating is not easy to be layered and precipitated. However, the large specific surface area of the pigment with small particle size increases the chance of flocculation of the coating, which is not conducive to grinding and dispersion.
Organic pigments should have excellent weather resistance, solvent resistance, stain resistance, scratch resistance, and excellent water resistance, acid resistance, alkali resistance, etc., if they are baking coatings, they must have excellent properties. Heat resistance. In particular, in addition to the above properties, automotive paints must have high color, high vividness, good texture and fullness. Generally, inorganic pigments have good durability and hiding power, but their color is not as bright as organic pigments, and their texture is not as good as that of organic pigments. Many organic pigments with excellent properties have been used more and more in high performance coatings industry. However, due to the different film-forming materials used in different coating systems, the corresponding organic pigments should be selected according to the resin properties, additives and solvent systems. The following is an introduction to the use of organic pigments in architectural, automotive and coil coatings.
2.1 Application of organic pigments in architectural coatings
Because the latex paint is rich in color, it can be selected at will, the decorative effect is good, the use period is long, and the architectural paint with acrylic emulsion as the film-forming material plays an increasingly important role in urban dressing. As an important constituent material in latex paints, the selection and use of organic materials directly affects the color retention of latex paints. Facing the understanding of pigment properties and applications, it can guide the production of high quality latex paints. Organic pigments are not affected by physical and chemical factors during use. They are generally insoluble in the medium used, and always exist in the original crystal state. The coloring of organic pigments is achieved by selective absorption and scattering of light.
2.2 Application of organic pigments in automotive coatings
Automotive coatings are mainly divided into three parts: primer, intermediate coating and topcoat. The topcoat using pigment accounts for about 1/3 of the amount of paint used. The amount of organic material used in topcoat is 2%-4%, according to 2006. 300,000 tons of automotive coatings calculated in 2006, the use of organic pigments in automotive coatings is 2000-4000T. In the coating industry, the high technical content of automotive coatings is difficult to construct. It can be said that the level of automotive coatings in a country basically represents the overall level of the national coatings industry, which puts high demands on the resins and pigments used in the distribution of automotive coatings. Quality requirements. Automotive coatings should meet the weather resistance, heat resistance, acid rain resistance, UV radiation resistance and hazard resistance of metal surface coatings. The pigment for automotive coatings is a high-quality coloring agent. The change of color of automobile is to adjust the organic pigment in the coating. Therefore, the application of organic pigment in automotive coating must have stability, chemical resistance and anti-seepage. Thermal stability. For automotive topcoats, such as metallic glitter paints, organic pigments are required to have high transparency and complement the hiding power of inorganic pigments.
2.3 Application of organic pigments in coil coatings
The coil coating is divided into functional topcoats, primers and backcoats. The main types of primers are epoxy, polyester and polyurethane: while the topcoats and back-painted varieties mainly include PVC plastic melt, polyester, polyurethane, acrylic, fluorocarbon and silicon. Polyester and so on. Generally, coil coatings require high temperature resistance and weather resistance of pigments. Therefore, when selecting organic pigments, it should be considered to select a heterocyclic pigment with a symmetrical structure to meet the requirements similar to automotive coatings, such as quinacridone. For the class, titanium bismuth, DPP pigments, coil coatings, the requirements for pigments are as follows:
1 heat resistance, required to withstand the high temperature of 250 ° C above the baking, no change in color:
2 weather resistance, especially pay attention to the weathering resistance of the color:
3 flocculation resistance generally requires color difference △ E ≤ 0.5:
4 solvent resistance For coil coatings, strong polar solvents such as ethylene glycol butyl ether and methyl ethyl ketone are used:
5 migration resistance pigments show partial solubility in solvents with high solubility due to the use of different pigments in the coating system, especially Different solubility properties of organic pigments and inorganic pigments lead to bleed and floating. Polyester and polyurethane coatings contain aromatic solvents. Some organic pigments will crystallize in aromatic solvents, causing crystal transformation and color change. The tinting strength is reduced.
3. Requirements for the development of high performance coatings for organic pigments
Organic pigments have been developed with the advancement of organic dye technology, and have formed a special performance, relatively independent organic color system, widely used in inks, coatings and plastics. In recent years, the world's organic pigment industry has not produced Too much growth, but the production, variety and specifications of high-performance organic pigments have increased significantly. Although the ratio of high-performance organic pigment production to total production is not very large, the high-performance organic materials produced by high-performance organic materials bring high performance and high added value, so its output value exceeds the mid-range organic pigment, accounting for half of the total output. The output of low-grade organic pigments is equivalent.
Increasing the variety of high-performance organic pigments to meet the high performance requirements of the application field will be the future development trend of organic pigments. With the advancement of technology, the demand for high-performance organic pigments and organic pigments with special functions will continue to increase: at the same time, the environment The concept of protection will be fully integrated into every link of organic pigment production, trade and consumption. The innovation of organic pigment technology should be market-oriented, accelerate the construction of technological innovation system, attach great importance to original innovation, and rely on independent innovation to enhance the core competitiveness of the industry. The research and development of organic pigments in China in the future should be carried out around new products such as coatings and inks, improve the performance of old products, research and develop new varieties of organic pigments, and meet the requirements of environmental protection regulations for continuous production. It can be summarized as: high-grade products, that is, the durability, weather resistance, heat resistance, time solvent and migration resistance of the coating to meet the requirements of the metal watch: development of special functional organic pigments with high purity and specific crystal form Wait.
