Common knowledge of coatings: problems in application of additives in powder coatings

Core tip: coating additives are an important part of powder coating How to choose the appropriate additives for powder coating should meet the following requirements 1 Compatibilities of additives and resins for powder coatings This is the first thing we should pay attention to when we choose additives The additives of powder coating must remain in the powder coating for a long time, so as to play its due role Therefore, the commonly used additives should be compatible with epoxy, polyester, acrylic and other resins In general, the compatibility between powder coating additives and resins is compared, and the method used is based on their structure Application scope and advantages of roller ceramic coating Recommended introduction: the surface of ceramic rubber plate used for roller ceramic coating is cast into durable rubber plate by hundreds of independent small ceramic pieces Each ceramic piece has raised characteristics Under general conveyor belt pressure, thousands of unique cast bumps can produce positive traction, prevent slipping and extend the service life of conveyor belt roller At the same time, the bottom layer adopts high-quality rubber, which has strong elasticity and can play a good impact resistance role The scope of application of roller ceramic coating is one three six 83857180 (the same as V) 1 Roller coating in extremely harsh working environment 2 The belt joint is not suitable for fixing with iron buckle; 3 It is suitable for leather Home of coatings: coating additives are an important part of powder coatings How to choose the right additives for powder coatings should meet the following requirements 1 The compatibilities of additives and resins for powder coatings should be paid attention to first The additives of powder coating must remain in the powder coating for a long time, so as to play its due role Therefore, the commonly used additives should be compatible 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 their structural similarity For example, leveling agent is the main additive in the production of powder coating, which can reduce the surface tension of the film, play the role of film homogenization and elimination of shrinkage, and make the cured film obtain a smooth and glossy surface When using, additives with carrier, such as E-12 carrier, can not be used in the formula of pure polyester system In addition, the applicable systems of leveling agents produced by each company are different, which requires powder manufacturers to find suitable resins to match, and the same is true for brighteners As another example, B68 chemical matting agent containing amidine and polybasic acid salt is only suitable for systems with epoxy If it is used in other systems, it will not only lose its due effect, but also bring negative effects on the coating 2 Adaptability of powder coating additives to production process some powder coating additives should be considered in the formulation design, because the production process conditions are relatively harsh, which may be high temperature, low temperature, high-speed shear and so on, resulting in the decomposition, volatilization and failure of powder coating additives, resulting in formula failure For example, some pattern powder coating additives can not be extruded by the extruder together with the base material, but added to the finished powder, only in this way can it show the pattern it should have Because in the process of extrusion and melting, the pattern auxiliaries have completed the pre reaction, resulting in no pattern or different pattern size, different hand feel, different stereo sense and other phenomena In the process of mixing 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 according to different feeding sequence Experienced technical engineers know that the sequence and process conditions are very important when all kinds of powder coating additives are mixed with the base material or added to the finished product process, which directly affects the mixing effect and coating performance 3 The multiplicity of powder coating auxiliaries in powder coating some powder coating auxiliaries not only play the main role, but also have double 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 kind of Party's chemical, which can replace part of titanium dioxide as white pigment At the same time, it has a certain conductivity, which can be used in the occasions requiring antistatic or conductivity; it also has the function of shielding ultraviolet light, especially the UV light in the range of 240-380 / μ m; of course, it also has the function of mildew prevention, sterilization, and improving the coating performance of the resin containing carboxyl group It can be seen that the choice of an effective additive is to fully understand its various functions 4 To make full use of the interaction between additives of powder coating synergism of additives of powder coating refers to the synergism of two or more additives when they are used properly Of course, the opposite of synergy is antagonism For example, the combination of carbon black and thiophenol antioxidant in pure polyester outdoor powder coating has excellent synergistic antioxidant effect, but when it is used together with steric amine or phenolic antioxidant, the original stability effect of the coating will be weakened due to the antagonism 5 As we know, some powder coating additives have to have a bad effect on some properties of powder coating when they play their normal role This is closely related to the amount of additives At present, there is a kind of low-temperature curing agent on the market, which can make the powder coating solidify into film within 120 ℃ / 30min, which is certainly what we need Because such low curing conditions will bring huge economic benefits, but also to some materials can not be baked at high temperature to provide application possibilities, greatly expanding the application of powder coatings However, it is known from our experiments that adding this kind of low temperature curing agent will have a great influence on the adhesion of the film These are all what we should fully understand when we design the formula and select the powder coating additives 6 The application of powder coating additives is often restricted by the final use of powder coating film Different types of powder coating additives have requirements on the color, smell, pollution resistance, durability, electrical, heat and cold resistance of powder coating additives 7 Familiar with the price of powder coating additives, we all know that 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 several different suppliers of the same type of products for comparative test, in the case of the same effect, choose low-cost products The powder coating additives produced by many domestic manufacturers are generally comparable to the similar products produced abroad Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,