Coating formulation: formulation design of powder coating

Core tip: the application of powder coating is very popular, and it is gradually replacing the traditional coating such as solvent coating in many fields With the development of several decades, the technology of powder coating has been very mature This paper briefly introduces the basic formula (general type) design and formula design (practical type) and test process in some key markets 1、 Key points of basic formula design of powder coating 1 Epoxy powder coating Epoxy powder is one of the earliest thermosetting powder developed and formed in the market It is generally based on bisphenol-A epoxy resin, according to the common view ring Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings: the application of powder coating is very popular, and it is gradually replacing the traditional coating such as solvent coating in many fields With the development of several decades, the technology of powder coating has been very mature This paper briefly introduces the design of basic formula (general type), formula design (practical type) and test process in some key markets 1、 The main points of the basic formula design of powder coating 1 Epoxy powder is the earliest powder type developed and formed market for thermosetting powder, generally based on bisphenol A epoxy resin, according to the common view Epoxy powder can be divided into functional type and decorative type In recent years, functional epoxy powder has developed rapidly and is mainly used in anti-corrosion (oil and gas transportation, pipe fittings and valves, steel bars, etc.), electronic (components, etc.) and electrical fields (bus bars and buses, etc.) In addition to bisphenol-A epoxy resin, the basic resin of functional epoxy powder often uses modified epoxy resin, such as phenolic epoxy resin, rubber elastomer epoxy resin, etc Decorative epoxy powder is not popular at present, and it is generally used for special effects such as water grain (continuous paint) and crack powder, bathroom handle cover smooth transparent powder and cast iron surface pattern (such as wrinkles for sewing machine head), etc Any compound that can react with epoxy group at a certain temperature (110-200 ℃) can be used as curing agent of epoxy powder In fact, the main curing agents suitable for epoxy powder are amines (dicyandiamide, modified or accelerated dicyandiamide), anhydrides (aromatic anhydrides, alicyclic anhydrides, etc.), hydrazides (dihydrazides, adipates, etc.), imidazoles (to As accelerant) and organic phenol curing agent, the corresponding curing agent shall be selected according to different technical requirements At the same time, the appropriate curing accelerant coordination shall be selected to meet various practical needs and curing conditions There are also many kinds of accelerants, such as acetylacetone metal salt [M (AA) n], triphenylphosphine (TPP), phosphonium salt and addition of arylisocyanate (substituted urea) , 2-phenylimidazoline, dimethylimidazole, etc 2 At present, epoxy / polyester (mixed type) powder is still the product with the largest production capacity and the widest application range in China The formulation design mainly starts from the performance requirements and selling price cost of the coating Relevant technologies and formulas are specified in relevant chapters before and after 2、 The common formulas are mainly weather resistant powder, white household appliance powder (take microwave oven as an example), basic art powder and household powder As the basic content of internal and external high transparent powder, this paper focuses on the introduction of functional powder This is because the practical application field and market of functional powder (mainly epoxy powder) have been expanding rapidly recently, and its application and performance have been continuously improved It is one of the important research and development directions at present, and it is also an important way to obtain better economic benefits （1） Weather resistant powder (taking building aluminum profile as an example) building profile is widely used in all aspects of buildings due to its excellent durability, decoration and processing formability The aluminum alloy profile has the advantages of good processing performance, light weight and so on The amount of aluminum alloy profile accounts for more than 80% of the metal profile The application of powder coating in aluminum profile has been growing rapidly At present, the surface treatment of aluminum profile is anodizing, electrophoretic coating and powder spraying, each of which has its own advantages In terms of environmental protection, powder coating has more advantages At the same time, powder coating has good selectivity in color, pattern, gloss and other aspects, and is loved by all walks of life The representative powder coatings are epoxy type, polyester type, acrylic type and silicone resin type As a practical application, such as aluminum frame, doors and windows, balcony, corridor, partition board and other high corrosion-resistant aluminum profiles, most of them use polyester and acrylic powder coating; in addition, because of the excellent adhesion and corrosion resistance of epoxy resin powder coating, but the weather resistance is poor, it is used indoors or as primer The polyester resin selected for powder coating of building profile is saturated type, which can be divided into two types according to its end group, i.e COOH type and oh type For polyester with low acid value (20-45mgkoh / g), TGIC and hydroxylamide are used as curing agents (Primid or HAA) For polyester with hydroxyl terminated (- OH), IPDI polyol prepolymer sealed by caprolactam is used as curing agent to prepare pure polyester powder coating with excellent weather resistance According to the weathering requirements of powder coatings, foreign countries usually divide into three levels according to Florida natural exposure test results: 1 Standard weathering powder coatings (can pass Florida exposure test standard 1-2a) 2 Improved weathering powder coatings (can pass Florida exposure test standard 2-3a) 3 Super weather resistant powder coating (which can pass the Florida exposure test standard for more than 5 years) in China, we generally evaluate the weather resistance of the corresponding powder coating according to GB / T 1865-1997 "artificial climate aging and artificial radiation exposure of paints and varnishes" (filtered xenon arc radiation) The first step to design the powder coating of profile with good weather resistance is the selection of raw and auxiliary materials Without reliable materials, the basic quality of powder cannot be guaranteed According to the climatic conditions in various parts of China, we provide more suitable raw materials here, as shown in table 11-5 See table 11-6 for typical white and gray reference formulas Table 11-5 aluminum profile powder raw material selection coating house is specialized in coating, diatom mud, paint coating, coating process, news information and coating of fireproof coating, diatom mud, paint coating, coating process, decoration knowledge and decoration effect map of fireproof coating,