The types of plastic colorants are divided into four types according to their physical forms: powdery colorants - toners; solid colorants - masterbatch; pasty colorants - color pastes; liquid colorants - colored oils; In the coloring of the plastics industry, the application of toner and masterbatch is relatively extensive.
Toner coloring
Direct use of toner (pigment or dye) to add appropriate amount of powder additives to color plastic particles, also known as dry coloring.
advantage:
1, good dispersion;
2, suitable for small batch plastic processing;
3, The cost is low, which saves manpower and material resources in the process of color masterbatch and color paste.
Disadvantages:
1, fly dust pollution, pigments in the transport, storage, weighing, mixing process will fly, resulting in pollution, seriously affecting the working environment.
2. The hopper of the extruder is not easy to clean. The pigmented toner adheres to the inner wall (or even the screw) of the feeding cylinder under the action of the white oil and other wetting agents. When the reloading is required, the cleaning cartridge becomes On-site operator's puzzle.
3, blown film, spinning products are not practical, use the coloring of the toner, because the pigment powder is evenly distributed in the resin to be colored, so its dispersion is better, this conclusion can only be targeted for injection products, especially thick-walled products In fact, for blown film, spinning products are another matter. Because toners are not pretreated in general, when they are mixed with resin, they are only fed from the feed port of the extruder, the screw, to the discharge port. For a certain distance and such a short mixing time, it is absolutely impossible to ensure that the molecules of the pigment powder and the pigment molecules to be dyed are well-connected. This phenomenon of 'cracking' will be obscured in thick-walled products and will be evident in blown film and spinning products. Therefore, the coloring method of the latter is still dominated by masterbatch.
Color Mastering
Using a certain process and corresponding equipment, under the action of additives, the pigment (or dye) is mixed into the carrier, and the molecules of the pigment powder are fully combined with the molecules of the carrier resin by heating, plasticizing, stirring, and shearing. It is then made into particles of similar size to the resin particles.
advantage:
1, Improved environmental pollution caused by flying toner
2. It is easy to change the color during use. It is not necessary to perform special cleaning on the extruder hopper.
3, Strongly targeted, simple color matching, easy to quantify.
4, compared with the batch of resin dry dyeing granulation and then to plastic parts, the use of masterbatch can reduce the plastic products caused by secondary processing after the performance of the resin aging, is conducive to the improvement of the life of plastic products.
5. In the process of processing, the pigments are fully combined with the carrier resin after fully mixing with the carrier resin under the action of the additives. When used, the resin to be processed is placed in a certain proportion, the compatibility is obviously better than Toner coloring.
Disadvantages:
1, poor dispersion, due to the small amount of added plastic products, processing time is short, by the extruder screw length-diameter ratio, the masterbatch dispersion is often not as good as toner.
2, the cost is high, more than one manufacturing process, dyeing costs higher than toner coloring.
3, The performance requirements for masterbatch are too high. When the carrier in the masterbatch is different from the performance of the resin to be colored, the surface of the plastic product often has undistributed spots, stains, and patterns. Therefore, the use of the masterbatch is due to its phase. Capability and dispersiveness are limited.
Paste coloring
Color paste is a semi-manufactured product in which pigments and fillers are dispersed in the paint. According to the purpose of use, it can be divided into paint paste, tape paste, paper paste, textile paste, mechanical paste, toy paste , Latex products such as color paste.
advantage:
1, easy to use, can be directly put into the processing technology for forming and sheet coloring;
2, In general, good high temperature resistance, convenient storage, no precipitation;
3, can reduce the problem of dust pollution in the use of toner, but also can solve the lack of compatibility and dispersion of masterbatch;
4, The color paste is easy to control the use of input in use, reduce chromatic aberration, improve coloring power and color brightness
5, Environmental protection conforms to EU REACH and other regulatory requirements.
Disadvantages:
1. At present, the biggest constraint in the development of color paste is the production process of domestic color paste. High-quality color paste requires high quality of the process and raw materials, and its cost will be higher than that of color masterbatch and toner.
2, When the amount of addition is large, the screw may slip.
3, When storage time is long, sedimentation will occur. It is better to stir before use.
Oil coloring
Color oil is a liquid pigment concentrate without resin carrier. At present, color oil is mainly used in the preform in our country.
advantage:
1. Low addition ratio, usually 0.1~0.5% for transparent series, 0.3~3.0% for pearlescent/solid color series.
2, excellent dispersion, more uniform color, brighter colors, products with a higher gloss; color stability, reduce coloring defects.
3, The material is only subjected to a high temperature process, and the physical properties of the raw material resin are not affected.
4, The best inventory management, only requires a small space to complete the color oil storage. Compared with color masterbatch to save three quarters of the storage space. Reduce overall inventory and working capital pressure.
5, The color oil adding equipment is simple, the cost is low, the color changing process is simple and fast, the freedom of production scheduling is improved, the staff and the energy consumption are saved when saving the staff;
6, applies to all polyolefins (such as PP / PE), polystyrene resin (PS), PET resin and other engineering resins.
Disadvantages:
1, can not add anti-static agent in the color oil, resulting in the product can not be dust-proof in the shelf or storage;
2. The shelf life of colored oil products is shorter than that of masterbatch products;
3, color oil needs special color oil adding equipment, that is, colored oil metering pump can supply colored oil to the injection molding machine to produce the desired color products.