In the era of environmental protection storm, the development of environmentally friendly coatings is the inevitable choice of enterprises, but environmentally friendly coatings are not only water-based coatings, if enterprises flock to the development of water-based coatings, it is inevitable that there will be product homogenization. In addition to water-based coatings, high solid sub-coatings, solvent-free coatings, powder coatings are also environmentally friendly coatings, should become the focus of the paint industry development direction. Research reports say the Asia-Pacific region expects the value and volume of the powder coatings market to grow at its highest rate between 2017 and 2022
. Powder coating technology is evolving rapidly to meet demand-driven markets. Market-driven research on the application of different powder materials in powder coatings is particularly important.
1, Powder Coatings Overview
1, Powder Coatings Introduction
Powder coatings began in the 1950s, is a solid content of 100%, and no organic volatiles (VOCs) produced by environmentally friendly coatings, with energy saving, reduce pollution, simple process, easy to achieve industrial automation, excellent coating performance and so on.
powder coating is a powder coating consisting of polymers, pigments and additives. Because there is no volatile liquid medium, with good ecological environmental protection, powder coating can form a thick coating at one time, with very high production efficiency, powder coatings with excellent technical properties and chemical corrosion resistance, with excellent coating properties, powder coatings can save energy, save resources, utilization rate of up to 99%, safe to use, with outstanding economy;
2, Powder Coatings Market Profile
As demand for electrical appliances and light vehicles continues to grow, the demand for powder coatings increases. Growing demand for end-use industries in developed and emerging countries has also led to growth in the powder coatings market. The global powder coatings market is expected to reach $134.9 billion by 2022, with a compound annual growth rate of 6.75 percent from 2017 to 2022, according to a report by Markets and Markets, a market research firm.
Thanks to a combination of factors, particularly the rapid development of urbanization and the combined growth of housing, construction and automotive, China's powder coatings market demand is growing at the fastest rate in the world, with China's powder coatings industry producing 2.07 million tons in 2016.
Chart 1: Changes in China's Powder Coatings Industry Production 2009-2016 (units: tons)
From the point of view of production, powder coatings currently account for about 11% of China's total coating production, according to the "13th Five-Year Plan" to 20 The total output of the coating industry is expected to grow to about 22 million tons in 20 years, of which the cost-effective and environmentally friendly coating varieties account for 57% of the total coating production," and the proportion of powder coatings will rise to about 18% in 2020, with a production of 4 million tons. The rapid development of powder coatings will inevitably lead to the growth of powder filler demand.
, the application of different powder materials in powder coatings analysis
coating fillers can not only reduce their costs, but also improve the performance of coating products also play a great role. Such as improving the wear resistance and scratching properties of the coating film, reducing the normal flow of paint melt flow, improve corrosion resistance, improve moisture resistance and so on.
powder coatings need to take into account factors such as density, dispersion performance, particle size distribution, and purity when selecting fillers. In general, the greater the density, the lower the coverage of the powder coating, the greater the dispersion of large particles than the dispersion of small particles, the chemical inertness of fillers to avoid reactions with certain components of the powder formulation, such as pigments, the color of the fillers should be as white as possible. Powder coatings are commonly used in powder materials such as calcium carbonate, vanadium sulfate, talcum powder, mica powder, kaolin, silicon dioxide, silica ash and so on.
1, calcium carbonate in powder coating applications
calcium carbonate is divided into light calcium carbonate (precipitation calcium carbonate) and heavy calcium carbonate. Regardless of the type of calcium carbonate and the method used to produce it, different particle sizes strongly affect the gloss of the coating. Calcium carbonate is generally not recommended for outdoor use.
addition to incremental use, heavy calcium is mainly used to partially replace titanium dioxide and color pigments, replace light calcium and precipitation of radon sulfate, anti-corrosion and partial replacement of rust-proof pigments.
calcium can be used alone or in the same time as talcum powder when used in indoor building paint. Compared with talcum powder, calcium carbonate can reduce the powder rate and improve the color preservation and anti-mold resistance of light paint. However, poor acid resistance hinders its application in external coatings.
compared with heavy calcium, light calcium has a small particle size and narrow particle size distribution range, high oil absorption and brightness, light calcium can be used in the place where the greatest demand for light dissipation effect.
2, the application of sulphate in powder coatings
as a coating body pigment of nihric sulfate has natural and synthetic two kinds, natural products weighing crystalline powder, synthetic products called precipitation sulphate.
in powder coatings, precipitation of nicosate can enhance the fluidity and photoresistability of powder coatings, and has better compatibility with all colors. The powder coating can achieve the ideal coating thickness in the spraying process, and the powder rate is high.
heavy crystal powder fillers are mainly used in industrial primers and automotive intermediate coatings that require high film strength, high filling force and high chemical inertness, as well as in finishes that require a high gloss. In latex paint, due to the high refractive index of heavy crystal (1.637), fine heavy crystal powder can have the function of translucent white pigment, can replace some titanium white powder in the coating.
3, mica powder in the application of powder coatings
mica powder for complex silicate composition, particles are scaly, heat-resistant, acid-resistant and alkaline excellent, the melting fluidity of powder coatings has an impact, generally used in temperature-resistant and insulated powder coatings, can be used as a texture powder filler.
many mica-like species, the chemical structure of mica is similar to that of kaolin, and it has many characteristics of mica-like minerals and clay-like minerals. It can be applied to the coating, can greatly improve the weather resistance of the coating film, water permeability, enhance the adhesion and strength of the coating film, improve the surface of the coating film. At the same time, dye particles easily enter the lattice layer of mica powder, thus keeping the color from fading for a long time. In addition, mica powder also has anti-algae mold function. Therefore, mica powder is a multi-functional filler with superior price performance for coatings.
4, talcum powder in powder coating applications
talcum powder is also known as water-containing magnesium silicate, by talc ore directly crushed. Particles are needle-like crystallization, have a slippery feel, soft texture and low abrasiveness, have good suspension and dispersion and a certain denaturation, the melting fluidity of powder coating has a greater impact, often used in texture powder. At present, a variety of primers, intermediate coatings, road signs paint, industrial coatings and internal and external architectural coatings used in the application.
talcum powder is cheap, but it has drawbacks and is therefore used in limited quantities. First of all, the amount of oil absorption is large. When low oil absorption is required, it must be combined with low oil-absorbing fillers and heavy crystal powders; Talcum powder, because impurity minerals easily react with acid (such as acid rain), it is not suitable for external coatings that require high weather resistance;
5, the application of silicon dioxide in powder coatings
porous powder quartz belongs to a silicon dioxide system, the safety of use is recognized, has been widely used in powder coatings, fire protection coatings, waterproof coatings, anti-corrosion coatings. Cheap porous powder quartz reduces the cost of powder coatings while replacing vanadium sulfate to reduce the soluble radon content of the product and meet environmental requirements.
addition, powder coatings often use gas phase white carbon black as a powder coating loose and anti-block additives. Gas-phase silica is a multi-functional body pigment and a coating fluid control agent with excellent performance. In liquid coatings, its fluid control functions include: thickening, tentacles, anti-flow hanging, covering edges, and in solid powder coating systems, the free flow of powder is enhanced to prevent lumps and fluidization.
6, kaolin in powder coatings
kaolin can improve tentacles and precipitation resistance. Calcined clay has no effect on fluidity, but can have a de-lighting effect, increased cover and increased whiteness, like unprocessed clay, which is similar to talcum powder.
, kaolin is generally water-absorbing, not suitable to improve the tenacity of the coating, not suitable for the preparation of water-repugnance coating. The particle size of kaolin products is between 0.2 and 1 m. The tall sorg soil with large particle size absorbs water, the light-absorbing effect is good, and the small-grained kaolin soil (less than 1 m) can be used for semi-optical coatings and internal coatings.
kaolin can be divided into calcined kaolin and washed kaolin. Generally speaking, the oil absorption, opacity, porosity, hardness and Baidu are higher than washing kaolin.
7, the application of hollow glass microbeads in powder coatings
Hollow glass microbeads are a small, hollow ball-shaped powder with light weight, large volume, low thermal conductivity, high pressure strength, insulation, corrosion resistance, non-toxicity and dispersion, mobility, good stability and other advantages.
in powder coatings, hollow glass microbeads can play the following roles:
(1) insulation, insulation, low water absorption. The interior of the hollow glass microbeads is a vacuum or thin gas, with epoxy resin has a difference in density and thermal conductivity, so it has insulation properties, is an excellent filler for high temperature powder coatings.
(2) improves the physical and mechanical properties of powder coatings. Hollow glass microbead fillers increase the hardness and stiffness of powder coatings. However, the impact resistance performance decreased, the decline is related to the surface treatment of hollow glass microbeads. If the correct coupled agent is selected for pre-treatment, the impact on the material's impact resistance can be reduced.
(3) has a low suction rate. Different models of hollow glass microbeads per 100g of oil absorption rate between 7mg to 50mg, this low oil absorption of filling materials in the production process disguised to increase the amount of filling to reduce the overall cost.
8, the application of silica ash in powder coating
the main component of silica ash is calcium silicate, density of 2.9g/cm3, refractive index of 1.63, oil absorption of 30 to 50%, with a needle-like structure, and good brightness.
powder coatings are generally made from natural silica ash powder, which is processed from natural silica ash. Silica ash in the coating can be used as a physical pigment and replace part of the white pigment, covering, incremental action, reduce the cost of paint. Because of its good conductivity, it is often used in epoxy insulated powder coatings. Silica ash is a white needle-like structure that improves the bending and stretching performance of powder coatings.
3. The development trend of powder fillers for powder coatings
1, powder filler surface treatment
powder fillers are polar, and powder coating resin polarity is very small, will cause the compatibility between the two is not good, powder coating processing and coating performance has a negative impact. Therefore, it is usually necessary to physically (table bread cladding and surface adsorption) or chemical methods (surface replacement, hydrolyzing, polymerization and joint techniques, etc.) to treat the powder fillers, so that the particle diameter of the aggregate body is significantly reduced or the mobility of the system can be improved, improving the processing performance of the coating, apparent quality (e.g. gloss, brightness of color, etc.) and mechanical strength.
2, powder filler micro-refinement
powder coating resin and filler ratio a certain time, theoretical filler particle size is smaller, coating surface performance, mechanical performance is better. If the particle size of the filler is reduced to a level similar to the diameter of the titanium dioxide particle (0.2 to 0.5 m), it can isolate the polymethic titanium produced in the formula, forming more effective dispersion center, and improve the covering force of titanium dioxide, which is the principle of spatial space separation of the micro-refined filler. Similarly, fine-grained fillers can reduce the amount of pigment used.
3, powder filler nanotechnology
the most commonly used nanomaterials are nano-silicon dioxide, nano-titanium dioxide and nano-calcium carbonate. It is reported that nano-titanium dioxide is transparent, can improve the mechanical properties of the coating and ultraviolet absorption, applied to the car cover varnish, can make the powder coating weather resistance has been significantly improved. Because nanomaterials are very small particles, surface activity is quite high, it is easy to reunite, flocculation, so nanofill surface treatment, addition methods and dispersion equipment selection, nanomaterials in the powder coating addition and how to disperse into the base resin, nanomaterials in powder coating application is the key. When designing powder coatings, different fillers can be selected according to product performance requirements for optimum results.
4, powder coating filler functionalization
functional powder coating development direction is to improve the physical, chemical, technical properties of certain aspects of powder coatings, or to give powder coatings new functions. For example, kaolin and silica ash powder are used in the production of electrically insulated powder coatings, which can reduce the cost of powder coatings and improve electrical insulation. Aluminum hydroxide and magnesium hydroxide have flame retardant properties and can be made into flame retardant powder coatings, as well as controlling fluidity, improving adhesion, controlling gloss, and improving cover. Therefore, powder coating fillers should be from simple cost reduction to other functional research, to develop more excellent performance, low-cost new fillers to meet the needs of the continuous development of powder coatings.
powder coating is a kind of energy-saving, resource-saving, low-polluting environmental protection paint. As the world's demand for energy is increasing, reducing energy consumption and protecting the environment have become the main direction of development. Therefore, the development of low temperature curing, high weather resistance, decorative and thin coating powder coating will be the main direction of development in the future. Driven by the demand for powder coatings, the demand for powder fillers such as calcium carbonate, quartz, mica powder, talc and kaolin is bound to increase. And the requirements for the micro-refinement, functionalization and surface modified treatment of powder fillers are getting higher and higher.