1. The importance of heat resistance stability in plastic coloring. According to the equipment, process conditions and product requirements, the processing temperature of various types of plastic resins varies from 120 ℃ to 350 ℃ / 5min, such as the processing temperature of soft and hard PVC is generally 170-200 ℃, the processing temperature of low-density and high-density polyethylene, polystyrene is 200-280 ℃, while that of polypropylene, polyene amine and ABS, The heat stability of polycarbonate pigment at 250-330 ℃ refers to that the pigment does not have obvious color light, coloring power and function change at a certain processing temperature and a certain time. The change of pigments in plastics by heating has the following elements
(1) Pigments are differentiated by heated structure, for example, azo pigments change color due to cracking of heated azo group
(2) Chemical effects of additives in pigments and plastic resins on each other
(3) Pigment dissolved in resin by heat
(4) The physical properties and particle size of the pigment change after heating. The excellent variety of pigment heat-resistant stability can prevent pigment from color change due to differentiation or crystal change under heating temperature. Heat-resistant stability is an important application function target of pigment in plastic coloring
　　
2 test method for thermal stability of pigments for plastics (din53772): the test method for thermal stability of pigments used in plastics is as follows:
(1) Test equipment: single screw extruder L / D = 24 injection molding machine
(2) Test material: degradation of pigment plastics (HDPE, PP, PS, etc.)
(3) Test concentration: 1% of titanium dioxide
Pigment concentration 0.1%, 0.05%, 0.025% 0.005% respectively
(4) Test: the mixture of quantitative pigment and plastic can be extruded into uniform particles in a single screw extruder according to (3) concentration for many times. In the injection molding machine, at a certain constant time, at a distance of 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃, 300 ℃, gradually make a sample and test
(5) Identification: after the color plate is cooled for 16 hours, test the color plate? E = 3 is the heat stability of the concentration
3. How to correctly use the heat-resistant stability target of pigment in plastic coloring? Because most of the plastic processing processes are thermoforming processes, and the temperature is above 200 ℃, the following points should be paid attention to when using the heat-resistant stability target of pigment in plastic processing:
(1) The target of heat stability of pigments in plastic processing is related to the application concentration of pigments: under different concentrations, the heat stability function of some pigments varies greatly, for example, Pigment Violet 23 is used for HDPE coloring, and the heat stability of Pigment Violet 23 is only 200 ℃ when it is lower than 0.025%, and 260 ℃ when it is greater than 0.1%
(2) The goal of heat resistance of pigment in plastic processing is related to the use of plastic solubilization: the goal of heat stability of pigment under a certain application solubilization and a certain concentration is not the same as that under other solubilization. For example, when the color ability of Pigment Violet 23 in polyester stock solution is 260 ℃ / 4 hours, but the Pigment Violet 23 in polystyrene solubilization is not resistant to 220 ℃
(3) It should be noted that when considering the high temperature resistance of pigments, the heating time should also be considered. For example, when EVA is high foaming, it needs to be resistant to 160 ℃ for 30 minutes. When nylon 6 and polyester are polymerized, the heating time is 260 ℃ for 4 hours. Therefore, the pigment should be selected after the stable experiment under these application conditions
(4) The heat resistance target of pigment in plastic processing is related to the concentration of titanium dioxide
(5) Another need to consider is the thermal stability of the colored resin itself. When the resin is heated, it will change color due to the effect of thermal price reduction, such as yellowing. This will also affect the use of plastic pigments in materials with heat-resistant targets
Shandong Yanling dyestuff Co., Ltd. is a professional manufacturer of dyestuff and organic pigment. The company specializes in the production of "Yanling" brand dyes and "xuanlang" brand organic pigments. The company's sales network is all over the country. The company specializes in production and sales of red, yellow, orange and phthalocyanine. It is widely used in ink, paint, rubber, plastic, printing paste, stationery and other industries. Among them, organic pigments play an important role in the same industry, and they are also well received by our customers! Welcome to inquire. Tel 0534-5083003