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    Home > Coatings News > Paints and Coatings Market > Formulas for powder coatings

    Formulas for powder coatings

    • Last Update: 2020-02-18
    • Source: Internet
    • Author: User
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    The sample recipe mixes the raw materials given below in order and extrudes them Epoxy resin: 80.0% amine curing agent: 6.0% iron oxide red: 11.6% leveling agent: 1.6% defoamer: 0.8% after extrusion, the extrudate is cooled, rolled and then broken Key problem 2: the characteristics of powder coating are different from that of traditional liquid coating in the following aspects: 1 Ecological characteristics (see 10) 1 Economic and technological characteristics A high coating efficiency (the powder can be recycled); B Although the coating is thick, the raw material cost per unit area is low; C special spraying equipment; d Color change is troublesome and expensive; e coating with large amount of coating work and less color change is suitable for powder coating; F excellent mechanical properties; g excellent scratch resistance, impact resistance and chemical resistance; l toxicity A no heavy metal; B no physiological impact on human; C very small powder particles may enter human lungs; d Improper operation may cause dust explosion (oxygen content, fire source) 3 epoxy resin Epoxy resin (bisphenol A with molecular weight of 1000-4000) powder coating is widely used, which has good adhesion, storage stability, binding effect and corrosion resistance However, this powder coating has poor weather resistance and is mainly used as the primer for metal furniture, household goods, shelves, hardware tools, lamps, electric heaters, toys, etc The following are the curing agents used for this type of powder coating a Baking conditions of dicyandiamide substitutes (possibly containing accelerators): 15 min at 160 ℃, or 15 min at 200 ℃ Performance: good mechanical properties and chemical resistance [upload = GIF] / powder / UploadFile / 20045281792616965 GIF [/ upload] 4 pigment selection in order to avoid pigment damage in the extrusion process and ensure no discoloration, the pigment must have the following characteristics: l thermal stability l good mechanical properties l pigment must have good chemical resistance The raw materials used as fillers should be spherical, because the flake and whisker particles will form structural viscosity and cause leveling problems in the process of coating film formation In the process of powder coating production, the air can be coated in the powder material, resulting in surface defects In order to avoid this situation, a certain amount of defoamer, such as benzoin, can be added to the powder coating Other additives include leveling agent (such as acrylate or silicone oil), lubricating oil, accelerator, etc Wax can improve the pulverization and leveling of raw materials, avoid powder agglomeration, and improve the leveling, leveling and scratch resistance of the coating 6 Masterbatch additive masterbatch additive is a mixture of raw materials, which can improve the processability of raw materials Usually, its dosage is very small, but it also causes some problems due to its physical characteristics The used masterbatch additives should have the following characteristics: 1 The masterbatch additives with different particle sizes, 1 The amount of use is small (0.01% ~ 0.1%), and the typical masterbatch additives with different aggregation states (such as liquid additives) are: 1 The leveling agent with the base material as the carrier, 1 The catalyst with the base material as the carrier, 1 The advantages of using masterbatch additives with the filler as the carrier for valuable organic pigments are: 1 Improve the uniformity of the system, improve the accuracy of measurement, promote the mixing of raw materials, 7 The production of powder coating is quite different from that of liquid coating The processing steps are: 1 Premixing raw materials in a special equipment; 2 Homogenizing and dispersing raw materials with extruder (extrusion processing) In extrusion, raw materials are mixed or dispersed by one or more screws With the rotation of the screw, the raw materials are extruded and expanded regularly between the screw and the extruder wall Under the action of this shear force, good homogenization effect of raw materials is obtained In the whole extrusion process, the raw materials are heated to about 80 ~ 120 ℃ By using the vacuum extruder, it can prevent the raw materials from being covered by air; 3) cool the extrusion materials and roll them; 4) crush the rolled products into pieces; 5) grind and crush the fragments; 6) grade the powder particles according to different particle sizes, and the equipment used can be air particle size classifier, screen or cyclone separator 7) Product packaging 8 powder coating construction a fluidized bed coating In the process of fluidized bed coating, the powder coating is placed in a container with a hole at the bottom, the powder is uniformly fluidized in the container by blowing air, the workpiece heated to a certain temperature is immersed in the container, the powder particles adhere to the surface of the coated object, and the powder particles sublimate and melt on the coated object to form a continuous film by using the heat brought by the coated object The deposition time of the powder is determined according to the shape of the coating, the heat capacity of the workpiece and the required film thickness B electrostatic coating l corona spraying method in electrostatic coating, by using a high voltage spray device to powder particles charged, and then the vast majority of negatively charged powder particles move to the ground coating, thus discharge on the coating, deposition to form the coating Different from corona coating, the powder particles are charged not by high pressure, but by friction produced by high-speed movement of powder materials in plastic pipes Because the friction electric spraying method reduces the Faraday electrostatic shielding effect, it can effectively spray the corner and gap parts of the workpiece 9 powder slurry is a kind of product which disperses and stabilizes the powder coating in water The use method of powder slurry is the same as that of traditional liquid coating, and it can also reflect the advantages of powder coating Compared with traditional coating materials, powder coating has the following ecological advantages: 1 No solvent release, 1 No spray (recyclable), 1 No danger, energy saving, 1 No "three wastes" problem, 1 No heavy metals
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