1. Compatibility of powder coating additives and resin
This is the first issue that should be paid attention to when choosing additives. Powder coating additives must remain stable in the powder coating for a long period of time in order to exert their due effectiveness. Therefore, the commonly used additives should have compatibility with epoxy, polyester, acrylic and other resins. Generally, the compatibility of powder coating additives and resins is compared, and the method used is based on the similarity of their structures. For example, the leveling agent is the main auxiliary agent in the production of powder coatings, which can reduce the difference in surface tension of the coating film, play a role in homogenizing the coating film and eliminating shrinkage holes, so that the cured coating film can obtain a smooth and glossy surface. When used, the carrier-supported additives such as E-12 carrier can not be used in the formulation of pure polyester systems. Also, the applicable leveling system produced by each company is different, which requires powder production. Manufacturers are looking for suitable resins to match, and so are brighteners. Another example is the commonly used B68 type chemical matting agent containing cycloamidine and polyacid salt, which is only suitable for systems with epoxy. If it is used in other systems, it will not only lose the expected effect, but also bring a negative impact on the coating film. .
2. Adaptability of powder coating additives to production process
When formulating some powder coating additives, it should be considered that due to the harsh production process conditions, it may be high temperature, low temperature, high-speed shearing, etc., which will cause the decomposition and volatilization of the powder coating additives and fail, resulting in formula failure. For example, some pattern powder coating additives can not be extruded together with the base material by the extruder, but added to the finished powder later. Only in this way can it show its proper pattern. Because during the extrusion and melting process, the pattern aid has been reacted in advance, resulting in no patterns or different patterns generated during the film formation, different hand feelings, different three-dimensional feelings and other phenomena.
In the process of compounding two or more additives with the base material, in order to give full play to the effectiveness of the additives, they must be fully dispersed in the powder coating base material, and can be combined with the base material in different addition orders.
Experienced technical engineers know that the various powder coating additives are mixed with the base material or added to the finished product process, the order and each step of the process conditions are very important, it directly affects the mixing effect and the performance of the coating film.
3. The multiplicity of powder coating additives in powder coatings
In addition to the main role, some powder coating additives also have dual or multiple roles. Therefore, we must consider comprehensively when designing the formula, such as adjusting the dosage in the formula or simplifying the formula. For example, zinc oxide is a common chemical that can replace a part of titanium dioxide as a white pigment; at the same time, it has a certain conductivity for applications requiring antistatic or conductivity; it also has the function of shielding ultraviolet rays, especially It has good protection for UV light in the range of 240-380/μm; of course, it also has anti-mold and sterilization effects, and improves the performance of coatings containing carboxyl group resins. It can be seen that the choice of an effective additive is to fully understand its various functions.
4. Make full use of the mutual effects between powder coating additives
The synergistic effect of powder coating additives refers to the synergistic effect of two or more additives when properly used together. Of course, the opposite of synergy is confrontation. For example, carbon black combined with thiophenolic antioxidants in pure polyester outdoor powder coatings has excellent synergistic antioxidant effects, but when used with sterically hindered amine or phenolic antioxidants, A confrontation occurs to weaken the original stabilizing effect of the coating film.
5. The influence of powder coating additives on the performance of powder coatings
We know that while some powder coating additives play their normal role, they sometimes have to adversely affect certain properties of powder coatings. This is closely related to the amount of additives. At present, there is a low-temperature curing agent on the market, which can make the powder coating solidify into a film within 120℃/30min, which is of course what we need. Because such low curing conditions will bring huge economic benefits, it also provides some applications for materials that cannot be baked at high temperatures, which greatly expands the application field of powder coatings. However, as we know from experiments, adding such a low-temperature curing agent will have a greater influence on the adhesion of the coating film. These are all we should fully understand when choosing powder coating additives when designing formulas.
6. The use of powder coatings restricts the additives of powder coatings
The application of powder coating additives is often restricted by the end use of the powder coating film. Different types of powder coatings have different effects on the color, smell, pollution resistance, durability, electrical properties, heat resistance, cold resistance, etc. of the powder coating additives Claim.
7. The price of powder coating additives
Those who are familiar with powder coatings know that the general powder coating additives account for a small proportion in the powder coating formulation system, but the price is very expensive, so sometimes the price is also an important factor to measure its use. Usually, we can choose the same type of products from several different suppliers as a comparative test. If the effect is the same, choose the cheaper product. The powder coating additives produced by many domestic manufacturers are generally comparable to similar products produced abroad.