The biggest difficulty in using masterbatches is how do I properly add it to the material?
The two main factors are the carrier resin used to produce the masterbatch and its molecular weight, and they are often not determined by the company that buys the masterbatch. In addition to some specially requested colors, those that are not normally used are not used. Raw materials that are potentially destructive to polymer properties, particulate color concentrates typically contain 30% to 50% of a colorant, and the rest of the polymer system, such as a carrier resin, is essentially an adherent that acts as a colorant.
The amount of color masterbatch in the final resin is generally 2%-5%
If the color masterbatch is properly mixed, the content of the carrier resin in the final mixture is 1% to 3% or more.
As a result, it has become the largest additive in the additive series. Therefore, attention should be paid to the details when selecting the carrier resin.
Specifically, the carrier resin and the matrix resin should be chemically compatible.
The best way is to choose the same type of polymer as the matrix resin being filled.
There is a certain scope of application in these rules.
For example, nylon 6 can be used as a carrier resin in the coloration of nylon 66 or nylon 46. These nylons are compatible, and the melting point of nylon 6 is low, which promotes good mixing.
Similarly, polyoxymethylene copolymers can be used as carrier resins on polyoxymethylene homopolymers and SAN can also be used as a compatible carrier for ABS (but polystyrene is not acceptable). In addition, for certain plastic alloys, alloys can be used. One of the two polymers is used as a carrier resin for color masterbatches.
If incompatible resins are used as carriers in the production process, contamination is intentionally introduced. In order to avoid contamination, it is generally recommended that masterbatch processing plants use carriers that are compatible with the final resin product. However, most manufacturers care about It is how to meet the customer's desired color at the lowest cost.
One of them, It is the use of inexpensive polymers such as ethylene or ethylene copolymers such as EVA.
This decision may be due to the fact that the masterbatch makers do not have an in-depth understanding of the customer's or product shaper's experience with the product. Some masterbatch suppliers used to use a compatible carrier when formulating the masterbatch. Differentiate themselves from these competitors. But more suppliers are committed to price warfare, providing low-cost solutions based on the so-called 'universal carrier'.
Manufacturers who produce plastic barrels by injection molding find polyethylene particles in the barrels of ABS or PC. They are likely to discard them or pick out unqualified materials. However, downstream processing companies are contaminated by matrix resins due to the addition of color concentrates. , This contamination will still have an impact on the final product performance.
Suppliers that provide so-called 'salt and pepper' blends also add incompatible materials to their own products.
A major supplier of nylon 66 compounds, it will use nylon 6 as a carrier in some mixtures, but in most cases it will use EVA. Under the normal processing temperature of nylon 66, the ethylene acetate vinegar in EVA begins to undergo thermal degradation. , The by-products produced will cause the screw to wear and cause the product appearance problems, especially in places close to the pouring date and the weld line.
Some materials, such as polypropylene, can be adversely affected by the use of incompatible carrier resin colorants. One example shows the use of multiple living hinges to attach the lid to the spice container. There are some colors, and the part runs without any problems. The appearance of the hinge is also normal. In addition, other colors of the hinge, the appearance of the color slowly released from the product out of the trend, and after a few bending will occur after the destructive fracture. This difference in performance is not Because the colorant is due to the incompatibility of the carrier resin in the color masterbatch with the base resin, this process and phenomenon will disappear after correction of the color masterbatch carrier resin.
Assuming that the carrier resin and the matrix resin are compatible, then the second important attribute is the molecular weight of the carrier, which is usually expressed in terms of melt flow rate (MFR). In general, the masterbatch formulation is designed to promote better The mixture is generally selected as a carrier with a higher melt flow rate than the matrix resin to be colored. For example, a polycarbonate with an MFR of 10 g/10 min can be used with an MFR of 20-30 g/lOmin. The masterbatch. The high-melt masterbatch's masterbatch makes it easier to flow in the screw, and it is easier to disperse in a large number of primary color materials.
However, this method often has drawbacks.
Sometimes the relationship between MFR and molecular weight is neglected, and the molecular weight will directly affect the subsequent performance. On the other hand, for high MFR carrier resins, the possibility of a decrease in product performance in the final molded part will greatly increase.
In the use of color masterbatches in polyolefin products, high melt index LLDPE resin is widely used as a carrier resin. According to different product requirements, LLDPE grades with different melt index are selected as the carrier resin. Masterbatches manufacturers can process according to products. The process involves injection moulding or extrusion, the flow of the base resin, and the final use of the mechanical conditions of the product to design different masterbatch formulations.