Introduction to basic knowledge of color masterbatch (color species)

Time：2021-05-13 14:46:16 / Popularity： / Source：

1. What is color masterbatch?

Color masterbatch is also known as color type. Color masterbatch is a new type of special colorant for polymer materials, also known as pigment preparation.
It is composed of three basic elements: pigments or dyes, carriers, and additives. It is an aggregate obtained by uniformly loading an ultra-constant amount of pigment or dye in resin, which can be called a pigment concentration, so its coloring power is higher than pigment itself.
To put it simply, color masterbatch is an aggregate made by uniformly loading an ultra-constant amount of pigments or dyes in resin.

2. What are basic ingredients of color masterbatch?

Basic components of color masterbatch are:

1. Pigments or dyes

Pigments are divided into organic pigments and inorganic pigments
Commonly used organic pigments are: phthalocyanine red, phthalocyanine blue, phthalocyanine green, light fast red, macromolecular red, macromolecular yellow, permanent yellow, permanent violet, azo red, etc.
Commonly used inorganic pigments are: cadmium red, cadmium yellow, titanium dioxide, carbon black, iron oxide red, iron oxide yellow, etc.

2. Carrier

Carrier is matrix of masterbatch. Special color masterbatches generally choose same resin as product resin as carrier, compatibility of the two is the best, but at the same time, fluidity of carrier should also be considered.

3. Dispersant

Promote uniform dispersion of pigment and no longer agglomerate, melting point of dispersant should be lower than that of resin, have good compatibility with resin, have a good affinity with pigment. The most commonly used dispersants are: polyethylene low-molecular wax and stearate.

4. Additives

Such as flame-retardant, brightening, anti-bacterial, anti-static, anti-oxidation and other varieties, generally do not contain above additives in color masterbatch unless customer requests it.

3. What kinds and grades of color masterbatches?

Classification methods of color masterbatches are commonly used as follows:
Classified by carrier: such as PE masterbatch, PP masterbatch, ABS masterbatch, PVC masterbatch, EVA masterbatch, etc.
Classified by purpose: such as injection masterbatch, blow molding masterbatch, spinning masterbatch, etc.
Each species can be divided into different grades, such as:

1. Advanced injection color masterbatch:

Used in cosmetic packaging boxes, toys, electrical appliances shells and other advanced products.

2. Ordinary injection color masterbatch:

Used for general daily-use plastic products, industrial containers, etc.

3. Advanced blown film masterbatch:

Used for blow molding coloring of ultra-thin products.

4. Ordinary blown film masterbatch:

Used for blow molding and coloring of general packaging bags and woven bags.

5. Spinning masterbatch:

It is used for spinning and coloring of textile fibers. Masterbatch has fine particles, high concentration, strong coloring power, good heat resistance and light resistance.

6. Low-grade color masterbatch:

Used to manufacture low-grade products that do not require high color quality, such as trash cans, low-grade containers, etc.

7. Special masterbatch:

It is a color masterbatch made by selecting same plastic as carrier according to plastic species designated by user for product. For example, PP masterbatch and ABS masterbatch use PP and ABS as carrier respectively.
Universal color masterbatch: also use a certain resin (usually low melting point PE) as a carrier, but it can be applied to coloring other resins besides its carrier resin.

8. Universal color masterbatch:

General-purpose color masterbatch is relatively simple and convenient, but there are many disadvantages. It is recommended that users choose special color masterbatch.
Heat-resistant grade of special color masterbatch is generally compatible with plastic used for product, and it can be used with confidence under normal temperature. Only under following conditions will cause different degrees of discoloration, one is that temperature exceeds normal range, and the other is that downtime is too long.

9. Compared with granulation coloring, masterbatch coloring has following advantages:

9.1. Coloring and product processing are completed at one time, avoiding heating process of pelletizing and coloring on plastics, which is good for protecting quality of plastic products.
9.2. Minimize production process of plastic products.
9.3. It can save a lot of power.

4. Why use color masterbatch?

Use of color masterbatch has following advantages:

1. Make pigment have better dispersibility in product:

Color masterbatch is an aggregate made by uniformly loading an ultra-constant amount of pigment in resin.
In production process of color masterbatch, pigment must be refined to improve dispersibility and tinting strength of pigment. Carrier of special color masterbatch is same as plastic of product, and it has good matching. After heating and melting, pigment particles can be well dispersed in product plastic.

2. Conducive to maintaining chemical stability of pigment:

If pigment is used directly, pigment will absorb water and oxidize due to direct contact with air during storage and use. After color masterbatch is made, resin carrier separates pigment from air and moisture, which can make quality of pigment long-term change.

3. Ensure stability of product color:

Masterbatch particles are similar to resin particles, which are more convenient and accurate in metering. They will not stick to container during mixing, mixing with resin is more uniform. Therefore, stability of addition amount can be ensured to ensure stability of product color.

4. Protect health of operators:

Pigment is generally in powder form, which is easy to fly when added and mixed, it will affect health of operator after being inhaled by human body.

5. Keep environment clean and not stain utensils:

6. Process is simple, color is easy to change, it saves time and raw materials:

Because pigment is in direct contact with air during storage and use, phenomena such as moisture absorption, oxidation, and agglomeration will occur. Direct use will cause color spots on the surface of plastic product, hue will be dark, color will fade easily, dust will fly during mixing, which will affect health of operator. Color masterbatch undergoes mechanical processing during production process to refine pigments. Pigments are fully mixed with resin carriers and dispersants to isolate pigments from air and moisture, thereby enhancing weather resistance of pigments, improving dispersibility and coloring power of pigment, and hue is bright.
Since color masterbatch is similar to resin particle shape, it is more convenient and accurate in metering, will not stick to container during mixing, thus saving time of cleaning container, machine and raw materials used for cleaning machine.

5. Precautions for using color masterbatch:

1. How to use color masterbatch?

Use of color masterbatch is very simple. It only needs to be mixed with resin particles according to specified ratio and mixed by hand.
Pay attention to following issues in operation of equipment:
1.1. Mixing cavity of an injection molding machine or extruder generally has multiple temperature zones. Temperature of section near blanking port should be slightly higher. This is to make color masterbatch melt quickly after entering mixing chamber and mix with plastic resin as quickly as possible. This will help color masterbatch pigment to be in a good dispersion state in product.
1.2. Appropriate back pressure is applied to injection molding machine, which can improve mixing effect of screw and facilitate dispersion of pigments. Side effect of applying back pressure is to slow down injection speed.
1.3. Properly increase temperature of die head of extruder to increase brightness of product.

2. How to determine use ratio of color masterbatch?

Basis for determining proportion of color masterbatch is to obtain a satisfactory coloring effect. As long as surface tone of product is uniform, there are no streaks and spots, it can be approved. Use ratio of color masterbatch can be selected as follows:
1:100 Unless mixing performance of equipment is very good, uneven pigment dispersion is likely to occur. Generally, customers are not recommended to use this ratio.
However, due to price pressure, some customers particularly want to use this ratio of color masterbatches. For sake of customers, they also produce more concentrated color masterbatches with such a low ratio, dispersibility of pigments can generally meet requirements.
1:50 is used for plastic products with general coloring requirements. PE and PP color masterbatches are more used in this ratio
1:33--1:25 is used for PO products with high coloring requirements, and ABS products with low coloring requirements or general.
1:20 is used for advanced plastic products, including PO, ABS, can be widely used in injection molding, blow molding, spinning and other processes.
1:20 and above are generally used for coloring of high-grade cosmetics containers, and mostly used for small injection molding machines.

3. How to calculate cost of using color masterbatch?

Weight of color masterbatch itself should be deducted when calculating coloring cost of masterbatch.

4. Will using color masterbatch increase product cost?

This is case in most cases. However, in some cases, coloring with masterbatch is more economical than coloring with toner. Reason is that colorists can use a combination of several lower-priced pigments to achieve coloring effect of higher-priced pigments.
Also consider following two phenomena:
(1) In many cases, pigments selected by plastic manufacturers when matching colors with toners are not the most economical, because they are not familiar with pigments, it is very common to waste manpower and materials due to repeated trials when matching colors. Use of color masterbatch does not have this problem.
(2) Grades of products colored with color masterbatches and products colored with toner are completely different, their prices are also higher. Higher prices are often higher than increased costs of using color masterbatches, so color masterbatch can create "profit" instead. From this point of view, in some cases, it is more "economical" to use masterbatch coloring than toner coloring.

5. Do color masterbatches need to be dried before use?

Color masterbatches generally do not need to be dried and can be used directly. However, except for ABS and NY masterbatches, they should be dried according to conventional processes.
How long is shelf life of color masterbatch?
Masterbatch can be stored for a long time.
Pigment in color masterbatch is dispersed and fixed in carrier resin, is in a closed state, so its quality will not change even if it is stored for a long time. But it should be stored in a dry and cool environment.

6. Is it possible to use several different color masterbatches to formulate colors?

Several color masterbatches can be used to formulate specific colors for small-dosage customers. However, without guidance of company’s technical staff, customer can not claim to use several color masterbatches together, let alone mix color masterbatches produced by different companies, so as to avoid incompatibility and cause losses.
Will use of color masterbatch affect other properties of product?
Some pigments have an impact on flame retardant effect of product. When used in flame-retardant products, it should be pointed out to masterbatch manufacturer.
Does mold affect use of color masterbatch?
In order to fully display coloring effect of masterbatch, mold must have corresponding quality, especially surface must be very smooth.

6. Common defects of color masterbatch

1. Under sunlight, there are striped pigment bands in product

This problem needs to be considered from two aspects: physical and mechanical properties of plastic, plastic molding process:
1.1 Temperature of injection molding equipment is not well controlled, color masterbatch cannot be fully mixed with resin after entering mixing chamber.
1.2 Injection molding machine does not add a certain amount of back pressure, mixing effect of screw is not good.
1.3 Dispersion of color masterbatch is not good or resin plasticization is not good.
Process can be debugged as follows: 1. Increase temperature of part of mixing cavity by blanking port slightly 2. Apply a certain back pressure to injection molding machine.
If it is still not good after above debugging, it may be a problem of dispersion or matching of color masterbatch and resin, masterbatch manufacturer should be contacted to solve it.

2. After using a certain color masterbatch, product appears to be easier to break

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

3. Color is too dark (too light) after using according to ratio on masterbatch instruction

Although this problem is simple, there are many possibilities.
Specifically:
3.1. Color masterbatch has not been tested carefully, and pigment is too little or too much.
3.2. Measurement is inaccurate when in use, there are a lot of random measurement by domestic enterprises, especially small and medium-sized enterprises.
3.3. There is a problem with matching of color masterbatch and resin. This may be caused by improper selection of carrier of color masterbatch, or manufacturer may change resin variety at will.
3.4. Temperature of machine is improper, color masterbatch stays in machine for too long.
Processing procedure: Firstly, check whether resin type matches color masterbatch and whether measurement is accurate. Secondly, adjust temperature or speed of machine. If there are still problems, contact masterbatch manufacturer.

4. With same color masterbatch, resin and formula, why are colors of products injected by different injection molding machines in different shades?

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

5. After changing to another brand of resin, color of same masterbatch and formula has changed. Why?

Density and melt index of different grades of resin will be different, so performance of resin will be different, compatibility with color masterbatch will also be different, resulting in a color change. Generally speaking, as long as density and melt index are not much different, difference in color will not be too large, color can be corrected by adjusting amount of color masterbatch.

6. Will migration of pigments during storage of color masterbatch affect quality of product?

Some color masterbatches have high pigment content (or dyes). In this case, migration is normal. Especially color masterbatches added with dyes will cause serious migration. But this does not affect quality of product, because after color masterbatch is injected into product, pigment is in normal color concentration in product.

7. Why do some injection products have poor gloss?

There are many possibilities:
Nozzle temperature of injection molding machine is too low;
Mold finish of injection molding machine is not good;
Product molding cycle is too long;
Too much titanium dioxide in color masterbatch;
Dispersion of color masterbatch is not good.

8. After a period of time, some plastic products will fade.

Basic pigments used by manufacturer are of poor quality and drifting occurs.

9. Why is ABS color masterbatch particularly prone to color differences?

Different brands of ABS produced in various countries have a large color difference. Even same brand of ABS, each batch may have color difference, and of course there will be color difference after coloring with masterbatch. This is caused by characteristics of ABS, and there is no complete solution in the world. However, this chromatic aberration is generally not serious. When using ABS color masterbatch, users must pay attention to this characteristic of ABS.