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Causes and solutions of nine common problems in Color Masterbatch

Causes and solutions of nine common problems in Color Masterbatch

2022-04-02

Color masterbatch is a plastic colorant made of high proportion of pigments or additives and thermoplastic resin. The selected resin has good wetting and dispersion effect on the colorant and good compatibility with the colored material. Today, Sainuo will take you to know the causes and solutions of the nine problems of color masterbatch. 

1. After using a certain color masterbatch, the product appears to be easy to crack

This may be due to the poor diffusion and mutual solubility caused by the poor quality of dispersant or additives selected by the manufacturer, which affects the physical and mechanical properties of the products.

Sainuo polyethylene wax for color masterbatch has high molecular weight, high viscosity, Both lubrication and dispersion; the dispersibility of this pe wax is equivalent to BASF A wax and Honeywell AC6A.

2. Under the sunlight, there are striped pigment strips in the product

Considering from two aspects of plastic physical and mechanical properties and plastic molding process:

(1) The temperature of the injection molding equipment is not well controlled, and the color masterbatch cannot be fully mixed with the resin after entering the mixing chamber.

(2) The injection molding machine does not add a certain back pressure, and the mixing effect of the screw is not good.

The process can be debugged as follows:

(1) Slightly increase the temperature of the mixing chamber near the blanking port;

(2) The injection molding machine does not add a certain back pressure, and the mixing effect of the screw is not good.

3. With the same color masterbatch, resin and formula, the color of products injected by different injection molding machines is different.

This is often caused by the injection molding machine. Different injection molding machines have different mechanical states due to different manufacturing, use time or maintenance conditions, especially the difference in the adhesion between the heating element and the barrel, so that the dispersion state of the color masterbatch in the barrel is also different, and the above phenomenon will appear.

4. After changing another brand of resin, the color of the same color masterbatch and formula has changed

The density and melt index of different brands of resins will be different, so the performance of the resin will be different and the compatibility with the color masterbatch will be different, resulting in color changes. Generally speaking, as long as the density and melt index are not different, the color difference will not be too large. The color can be corrected by adjusting the amount of color masterbatch.

5. Does the pigment migration of Color Masterbatch during storage affect the quality of products?

The pigment content (or dye) of some color masterbatch is very high. In this case, migration is normal. In particular, the color masterbatch added with dyes will have serious migration. However, this does not affect the quality of the product, because after the color masterbatch is injected into the product, the pigment is in the normal color concentration in the product.

6. Some injection products have poor gloss

There are several possibilities:

(1) The nozzle temperature of the injection molding machine is too low

(2) The mold finish of the injection molding machine is not good

(3) Product forming cycle is too long

(4) There is too much titanium dioxide in the color masterbatch

(5) The dispersion of color masterbatch is not good

7. ABS color masterbatch is particularly prone to color difference

The color difference of different brands of ABS produced by various countries is large. Even for the same brand of ABS, there may be color difference in each batch number. Of course, there will be color difference after coloring with color masterbatch. This is caused by the characteristics of ABS, and there is no complete solution in the world. However, this color difference is generally not serious. Users must pay attention to the characteristic of ABS when using ABS color masterbatch.

8. The color is too dark (too light) after being used according to the proportion in the color masterbatch manual

Although this problem is simple, there are many possibilities, specifically:

(1) The color masterbatch has not been carefully tested, and there are too few or too many pigments

(2) Inaccurate measurement in use, and a large number of domestic enterprises, especially small and medium-sized enterprises, measure at will

(3) There is a problem in the matching between color masterbatch and resin, which may be due to the improper selection of Color Masterbatch carrier, or the manufacturer may change the resin variety at will

(4) The temperature of the machine is improper, and the color masterbatch stays in the machine for too long.

Treatment procedure: firstly, check whether the resin variety matches the color masterbatch and whether the measurement is accurate. Secondly, adjust the machine temperature or speed. If there are still problems, contact the color masterbatch manufacturer.

9. Discoloration of plastic color matching products

Plastic colored products will fade under the influence of many factors. The fading of plastic colored products is related to the light resistance, oxygen resistance, heat resistance, acid and alkali resistance of toner and the characteristics of resin used. The following is a detailed analysis of the fading factors of plastic coloring:

(1) The light fastness of colorant the light fastness of colorant directly affects the fading of products. For outdoor products exposed to strong light, the light fastness (light fastness) grade of colorant used is an important index. Due to the poor light fastness grade, the products will fade quickly in use. The light resistance grade of weather resistant products shall not be lower than grade 6, preferably grade 7 and grade 8, and grade 4 and grade 5 can be selected for indoor products. The light resistance of the carrier resin also has a great influence on the color change. The molecular structure of the resin caused by ultraviolet radiation changes and fades. Adding UV absorber and other light stabilizers into masterbatch can improve the light resistance of colorants and colored plastic products. The light resistance grade of weather resistant products shall not be lower than grade 6, preferably grade 7 and grade 8, and grade 4 and grade 5 can be selected for indoor products. The light resistance of the carrier resin also has a great influence on the color change. The molecular structure of the resin caused by ultraviolet radiation changes and fades. Adding UV absorber and other light stabilizers into masterbatch can improve the light resistance of colorants and colored plastic products. 

(2) The thermal stability of heat-resistant pigment refers to the degree of thermal weight loss, discoloration and fading of pigment at processing temperature. Inorganic pigments are composed of metal oxides and salts, with good thermal stability and high heat resistance. The pigments of organic compounds will change their molecular structure and decompose a small amount at a certain temperature. Especially for PP, PA and pet products, the processing temperature needs to be above 280 ℃. When selecting colorants, on the one hand, we should pay attention to the heat resistance of pigments, on the other hand, we should consider the heat resistance time of pigments. Generally, the heat resistance time is required to be 4-10min.

(3) Oxidation resistance after oxidation, some organic pigments gradually fade due to macromolecular degradation or other changes. One is high-temperature oxidation in processing, and the other is oxidation with strong oxidants (such as chromate in chrome yellow). When lakes, azo pigments and chrome yellow are mixed, the red color will gradually fade.

(4) The fading of acid and alkali resistant colored plastic products is related to the chemical resistance of Colorants (acid and alkali resistance, redox resistance). For example, molybdenum chrome red is resistant to dilute acid, but sensitive to alkali, and cadmium yellow is not resistant to acid. These two pigments and phenolic resin have a strong reducing effect on some colorants, seriously affecting the heat resistance, weather resistance and fading of colorants. For the fading of plastic colored products, the above properties of required pigments, dyes, surfactants, dispersants, carrier resins and anti-aging additives shall be comprehensively evaluated according to the processing conditions and application requirements of plastic products. 

Qingdao Sainuo Chemical Co., Ltd. We are a manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing. Sainuo rest assured wax, welcome your inquiry!

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