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Three issues that need to be considered for ABS coloring---Shenzhen pc lens price

by:Eugenia     2022-01-11
ABS resin has both the impact resistance of styrene resin and the oil resistance of AS resin. Since ABS is copolymerized by three monomers, it can exhibit the synergistic effect of the three components. Although there are many types of ABS resin, the colorants used are basically the same. The colorant used in ABS requires good heat resistance and weather resistance, and strong hiding power. Commonly used colorants include inorganic pigments such as titanium dioxide, cadmium pigments, iron red, ultramarine blue, and carbon black, as well as phthalocyanine pigments and quinacridone organic pigments. Since ABS contains rubber components, uneven coloring will appear when it is colored. The coloring is different, the reflection is different, and the color and light seen are also different. If the color is thicker, this shortcoming can be remedied. Therefore, the amount of colorant is relatively large, generally about 2%; the amount of titanium dioxide added is as high as 10%. The amount of colorant is large, so the dispersion problem of colorant must be considered. In addition, ABS resin is easy to change color when exposed to heat and ultraviolet rays, so it is necessary to choose pigments with relatively small variability. 1. The effect of pigments on the UV aging of ABS resin is the same as that of polystyrene and other plastics. ABS will promote aging when exposed to UV rays, especially its dimerized rubber components are more susceptible to UV rays. Therefore, if the product is exposed outdoors for a long time, it will change color and reduce the impact resistance. However, if the ABS material is mixed with inorganic or organic pigments to make a product, its strength will hardly change even if it is exposed for a long time outdoors. In addition, the changes in Rockwell hardness and tensile strength are also minimal. The above situation shows that the influence of ultraviolet rays only remains on the surface of the colored object, and the surface of the colored object reflects or absorbs ultraviolet rays, thereby forming a surface layer to protect the interior. The inside of the molded article is hardly affected by ultraviolet rays, so the physical properties change little. In contrast, the aging degree of natural resin is more obvious. Generally, the greater the UV absorption capacity of the pigment, the greater the effect of inhibiting aging. Therefore, when choosing pigments for ABS resin, we must fully consider the impact on the resin. For example, ABS resin products used outdoors, use suitable pigments with high concentration and strong hiding power as much as possible to improve the light resistance of the polymer itself. 2. The effect of pigments on the thermal aging of ABS resin. Due to the cross-linking of rubber components, ABS resin will change color with thermal aging. At the same time, the tensile strength and yield value will increase, while the impact value and elongation will decrease significantly. In addition, the color of the colored product itself will have considerable changes due to the same rubber composition and processing conditions. It is self-evident that the different content of the pigment causes some differences in the color tone. Judging from the discoloration of the ABS resin itself and the limitation of the discoloration and concealing ability of the pigment, the processing range is limited to 230~250℃. Of course, the higher the temperature, the more obvious the thermal change of the ABS resin. However, while considering the stability of the polymer itself, attempts are often made to conceal its discoloration by selecting appropriate pigments. Due to the different cross-linking and processing conditions of the rubber components in ABS, different pigments, and different pigment content, the color of the product changes considerably during the heat aging process. 3. ABS resin coloring processing problems. In plastic coloring, it is necessary to understand the role of the molding process on the coloring effect. Correctly mastering the molding process is an important means to ensure the coloring effect. ①Dry ABS resin is a water-absorbing resin, and the moisture absorption rate in the warehouse is usually 0.3%~0.4%. Therefore, ABS resin must be fully dried before use. If the pre-drying is not sufficient, the extruded product will have bubbles, causing surface scars, surface roughness, bubbles, etc. ②The coloring concentration of blended ABS resin is generally 1%~3%. There is enough mixing time for ABS resin and colorant to make them evenly mixed. Depending on the mixing equipment, the time should be controlled within 3~10min. The coloring agent is best to use color masterbatch, and the dilution ratio is 5%. If powder coloring agent is used, it is best to filter the coloring agent with a 250-mesh screen, otherwise color spots will appear, and the dilution ratio is about 2%. ③Coloring process ABS resin coloring can generally use an extruder, and the power of the extruder is preferably 1.5 times that of polystyrene and polyethylene. The screw can be of the Durmeg u200bu200btype, and the compression ratio of the screw is usually (3:1) ~ (4:1). The aspect ratio is about 18-22. The molding temperature of ABS colored resin is generally controlled at 180~230℃. Back pressure is very important for the melt mixing of colored resins. Proper back pressure can increase the surface gloss of the product, reduce or eliminate color spots, and make the dispersion of the colorant reach the best state. Shenzhen pc lens price
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