Types of plastic colorants and their advantages and disadvantages

[China Packaging Reuters type of plastic colorants, four, divided according to their physical form: powder colorant - toner; colorant solid form - masterbatch; colorant paste - paste; liquid colorant - colorless oil; colored plastics industry, the toner and relatively extensive application masterbatch.

Toner coloring

The method of coloring plastic particles directly with toner ( pigment or dye ) and adding an appropriate amount of powdery additives is also called dry coloring.

advantage:

1. Good dispersion;

2. Suitable for plastic processing in small batches;

3. The cost is low, which saves the consumption of manpower and material resources in the processing of color masterbatch and color paste.

Disadvantages:

1. Fly dust pollution, pigment will fly in the process of transportation, storage, weighing, mixing, resulting in pollution, which seriously affects the working environment.

2, the extruder hopper difficult to clean toner for coloring white oil under the effect of a humectant, buildup on the inner wall of the cartridge (or even a screw). When the material needs to be changed, cleaning the barrel becomes a problem for the field operator.

3. Film blowing and spinning products are not practical. Toner coloring is used. Since the pigment powder is evenly distributed in the resin to be colored, its dispersibility is good. This conclusion can only be used for injection products, especially thick-walled products. In other words, the blown film and spinning products are different. Because the toner is generally not pretreated, when it is mixed with the resin, the pigment powder is only required for such a distance from the inlet of the extruder, the screw, and the outlet and such a short plasticizing mixing time Of the molecules and the pigment molecules of the pigment are well held together - fully combined, it is completely impossible to guarantee, there will be " pinching " phenomenon. But this kind of " pinching " phenomenon will be covered up in thick-walled products, which is obvious in blown film and spinning products. Therefore, the latter coloring method is still dominated by masterbatch.

Coloring

Using a certain process and corresponding equipment, the pigment ( or dye ) is mixed into the carrier under the action of the auxiliary agent , and finally the molecules of the pigment powder and the carrier resin are fully combined by heating, plasticizing, stirring, and shearing It is then made into particles of similar size to the resin particles.

advantage:

1. The problem of environmental pollution caused by flying toner is improved.

2. It is easy to change the color during use, no special cleaning is needed for the hopper of the extruder.

3. Strong pertinence, simple color matching and easy quantification.

4, with the resin batch dry granulation after staining compared to plastic parts manufactured using resin masterbatch can reduce the performance of secondary processing plastic articles caused by aging, help to improve the life of the plastic article.

5. In the process of processing, the pigment masterbatch is fully mixed with the carrier resin after being fully kneaded under the action of additives . When used, it is placed in the resin to be processed in a certain proportion, and the compatibility is significantly better than the coloring of the toner.

Disadvantages:

1. Poor dispersibility, due to the small amount of addition, the processing time of plastic products is short, limited by the length-diameter ratio of the screw of the extruder, the dispersion of the masterbatch is often not as good as the toner.

2. The cost is relatively high, and the manufacturing process is more than once, the dyeing cost is higher than the toner coloring.

3. The performance requirements of the color masterbatch are on the high side. When the performance of the carrier in the color masterbatch differs from the resin to be colored, undispersed spots, stains, and patterns often appear on the surface of the plastic product. Therefore, the use of the color masterbatch depends on its phase. Capacitive and decentralized.

Coloring

Color paste is a semi-product made of pigment and filler dispersed in paint. According to the purpose of classification, it can be divided into paint color paste, tape color paste, papermaking color paste, textile color paste, mechanical color paste, toy color paste, latex product color paste, etc.

advantage:

1. Easy to use, can be directly put into the processing technology for molding and coloring of the board;

2. Usually, it has good high temperature resistance, convenient storage, and no precipitation;

3. Can reduce the problem of dust pollution in the use of toner, and can also solve the lack of compatibility and dispersion of the masterbatch;

4. The color paste is easy to control the input amount in use, reduce the color difference, improve the coloring power and the luster of color;

5. Environmental protection conforms to EU REACH and other regulations.

Disadvantages:

1. At present, the biggest restriction on the development of color pastes is the production process of domestic color pastes. High-quality color pastes have higher requirements on process and raw material quality, and their cost will be higher than that of color masterbatch and color powder;

2. When the added amount is large, the screw may slip.

3. When stored for a long time, precipitation will occur, it is better to stir before use.

Color oil coloring

Color oil is a liquid pigment concentrate without resin carrier. At present, color oil is mainly used on preforms in China.

advantage:

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

2. Excellent dispersibility, the color is more uniform, the color is more gorgeous, the product has a higher gloss ; the color is stable, and the coloring defects are reduced.

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

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

5. The equipment for adding color oil is simple, the cost is low, the color changing process is simple and fast, the freedom of production scheduling is improved, and the time, machinery and energy consumption of people and employees are saved.

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

Disadvantages:

1. Anti-static agent cannot be added to the color oil, so that the product cannot be dust-proof in the shelf or storage;

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

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