Types, advantages and disadvantages of plastic colorants

First, toner coloring

A method of coloring plastic particles by directly adding an appropriate amount of a powdery auxiliary agent to a toner (pigment or dye), which is also called dry coloring.

advantage:

1. Good dispersion;

2, suitable for small batches of plastic processing;

3, low cost, eliminating the consumption of human and material resources in the processing of color masterbatch, color paste and so on.

Disadvantages:

1. Fly dust pollution, pigments will fly during transportation, storage, weighing and mixing, causing pollution and seriously affecting the working environment.

2. The hopper of the extruder is not easy to clean, and the coloring powder is adhered to the inner wall of the barrel (or even the screw) under the action of a humectant such as white oil. When refueling is required, cleaning the cartridge becomes a problem for the field operator.

3, blown film, spinning products are not practical, using toner coloring, because the pigment powder is evenly distributed in the resin to be colored, so its dispersion is good, this conclusion can only be for injection products, especially thick-walled products. In other words, for blown film and spinning products, it is another matter. Because the toner is generally not pretreated, when it is mixed with the resin, the pigment powder should be made only from the inlet of the extruder, the screw, the discharge port, and the short plasticization mixing time. The molecules and the pigmented molecules are well-joined – full combination is completely unguaranteed and there is a “sandwich” phenomenon. However, this "sandwich" phenomenon will be masked in thick-walled products, which is obvious in blown film and spinning products. Therefore, the latter method of coloring is still dominated by color masterbatch.

Second, the color mastering

Using a certain process and corresponding equipment, the pigment (or dye) is mixed into the carrier under the action of the auxiliary agent, 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 toner flying

2. It is easy to change color during use, and it is not necessary to carry out special cleaning on the extruder hopper.

3, strong targeting, simple color matching, easy to quantify.

4. Compared with the batch of resin dry dyeing granulation and then to the plastic parts, the use of color masterbatch can reduce the aging of the resin caused by the secondary processing of the plastic products, which is beneficial to the improvement of the service life of the plastic products.

5. During the processing, the pigment masterbatch is fully combined with the carrier resin after being fully mixed by the auxiliary agent. When used, it is placed in a certain proportion of the resin to be processed, and the compatibility is obviously superior to the coloring of the toner.

Disadvantages:

1. Dispersibility is poor. Due to the small amount of addition, the processing time of plastic products is short. Due to the limitation of the length-to-diameter ratio of the screw of the extruder, the dispersibility of the color masterbatch is often inferior to that of the toner.

2, the cost is too high, an additional manufacturing process, the cost of dyeing is higher than the coloring of toner.

3. The performance requirements of the color masterbatch are relatively high. When the properties of the carrier in the color masterbatch are different from those of the resin to be colored, the surface of the plastic product often has undispersed spots, stains, and patterns. Therefore, the use of the masterbatch is due to its phase. Capacity and dispersion are limited.

Third, color paste coloring

A color paste is a semi-finished product in which a pigment and a filler are dispersed in a paint. According to the use of classification, can be divided into paint color paste, tape color paste, paper color paste, textile color paste, mechanical color paste, toy color paste, latex color paste.

advantage:

1, easy to use, can be directly put into the processing technology for molding and sheet coloring;

2, usually, high temperature resistance, storage, no precipitation;

3, can reduce the problem of dust pollution in the use of toner, can also 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 tinting strength and color brightness

5. The environmental protection type meets the requirements of EU REACH and other regulations.

Disadvantages:

1. At present, the biggest constraint on the development of color paste is the production process of domestic color paste. High-quality color paste has higher requirements on process and raw material quality, 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 the storage time is long, precipitation will occur, and it is better to stir before use.

Fourth, color oil coloring

The color oil is a liquid pigment concentrate without a resin carrier. At present, color oil is mainly used in bottle embryos in China.

advantage:

1. Low addition ratio, usually 0.1-0.5% for transparent series and 0.3-3.0% for pearl/solid color series.

2, excellent dispersion, more uniform color, more colorful, the product has a higher gloss; color stability, reduce coloring flaws.

3. The material only undergoes a high temperature process to keep the physical properties of the raw material resin unaffected.

4, the best inventory management, only need a small space to complete the storage of color oil. The relative color master saves three-quarters of the storage space. Reduce the pressure on overall inventory and working capital.

5. The color oil adding equipment is simple, the cost is low, the color changing process is simple and fast, the degree of freedom of production scheduling is improved, and the staff, the machine and the energy loss are saved;

6. Suitable for all polyolefins (such as PP / PE), polystyrene resin (PS), PET resin and other engineering resins.

Disadvantages:

1. Antistatic agents cannot be added to the color oil, resulting in the product not being dust-proof during storage or storage;

2. The shelf life of color oil products is shorter than that of color master products;

3. The color oil needs special color oil adding equipment, that is, the color oil metering pump can supply the color oil to the injection molding machine to produce the product of the desired color.