The application of gas phase alumina in powder coatings.

Wen/Li Political Law, Qiu Qinbing, Liu Li, Yang Xiaochun, Zhang Wei
Guangzhou Jibisheng Technology Industry Co., Ltd.
Abstract: Introduces the main characteristics of powder coatings and their classification, and briefly describes the main technical indicators affecting powder coating processes. The characteristics and technical indicators of alumina by gas phase method are also introduced, in view of the practical application of powder coatings, the application performance research of gas phase alumina in improving the corrosion resistance, powder rate, fluidity and wear resistance of powder coatings is described, and the guiding suggestions for the use of gas phase alumina in the powder coating industry are briefly described.introduction to
1 Powder Coatings
Powder coatings since the 1950s, is a solid content of 100%, and no organic volatiles (VOC) produced by environmentally friendly coatings, with energy saving, pollution reduction, simple process, easy to achieve industrial automation, excellent coating performance and so onPowder coatings are powder coatings made up of polymers, pigments and additives. Powder coatings are 100% solid powder coatings that can be fully automatically sprayed. Powder coating can form a thick coating at once, excessive powder coating in the process of spraying, can be recycled through the recycling system device, so powder coating can be almost 100 percent utilization rate, so that the coating industry reduces the treatment of waste, while reducing the degree of environmental pollution to a minimum. Liquid coatings contain organic solvents, easy to cause solvents to evaporate into the atmosphere to pollute the environment, while powder coatings are non-toxic, solvent-free and non-volatile toxic substances, with energy-saving, environmentally friendly advantages.
powder coatings can be divided into thermostered powder coatings and thermoplastic powder coatings due to the process of curing into film. Thermoplastic powder coating contains a large molecular weight and non-polar group thermoplastic resin as the main component, the need for a higher temperature to fully melt, level. At present, the market commonly used thermoplastic powder coatings have more special properties, such as polyolefin powder coatings with strong solvent resistance, polyfluoroethylene with excellent weather resistance. The thermostatic coating uses a small molecular quality thermosolytic resin, at a certain temperature, cross-linking with the curing agent to form a mesh structure of the large molecular coating. Compared with thermoplastic coatings, because the thermosystic coatings are resins with small molecular weight, the leveling of the coating is better, with strong corrosion resistance and mechanical properties. At present, powder coating has the main disadvantages of low powder rate, poor mobility, high curing requirements and defects in cured coating film.
powder coating in the process of electrostectrectrectrectrective spraying, because the powder is through the use of air thrust and other external forces evenly dispersed spray to the surface of the work piece, so the powder coating is required to maintain good mobility, while the product in the storage process to prevent the phenomenon of lumps. At the same time, due to the presence of Faraday cage effect, powder coating often appears in the process of spraying can not be effectively sprayed to the surface of the work piece, affecting the powder coating powder rate. Fluidity and powder rate is an important technical index of powder coating construction, gas phase alumina has the characteristics of fine particles, good dispersion and surface positive electricity, can be used as an effective filler of powder coating, added to help improve the fluidity of powder coating, powder rate, corrosion resistance and other aspects of performance.
2 Gas Phase Alumina Introduction
Gas Phase Alumina is a nanoscale fluffy powder produced by high temperature combustion hydrolysis of aluminum tyclone, oxygen and hydrogen, with a primary particle size between 7 and 40 nm. Alumina gas phase alumina has the characteristics of fine particles, high purity, good optical performance, good dispersion and surface positive electricity, and is widely used in coatings, inks, high-gloss photo paper, photoelectrelectrical ceramics, lighting products and other fields, is an important inorganic nano-new material.
3 Gas phase alumina in powder coating application performance research
3.1 to enhance the corrosion resistance of powder coating
With the rapid development of China's industry, pipeline in chemical products delivery, urban water supply, sewage treatment and other fields have been widely used. At present, the pipeline carrying oil and gas is mainly installed in complex soil environment, and most of the medium transported is corrosive, so the inside and outside walls of the pipeline may be corroded. If the pipeline does not do a good job of protection from corrosion perforation, easy to cause gas, oil leakage, not only interrupt its transportation process, but also serious pollution of the environment, serious times may even cause fire, causing harm, so in the design of the pipeline need to consider the installation of the environment on the pipe wear, corrosion effects. These devices require coating to protect against corrosion resistance in applications in these areas by coating on their surfaces to enhance their service life and safety.
add gas phase alumina to the powder coating as a hardener to improve the hardness of the coating. Alumina has a large surface area and high surf activity, good affinity with the substation and strong chemical stability. In ordinary anti-corrosion coating fillers and resins are easily penetrated by corrosive media, corrosion phenomenon. After adding gas phase method into alumina, the coating surface will form a tight, uniform oxide film protection structure, shielding the corrosion medium, to achieve the protection of the coating surface, play a role in corrosion resistance. At the same time, the addition of gas phase alumina in powder coatings will not affect the transparency and compatibleness of the coating, can ensure better decorative effect, but also achieve coating protection. The results show that under the test conditions, the corrosion resistance of alumina-enhanced inorganic zinc silicate coating is increased by 6 times, the sliding friction coefficient of the coating is about 0.2, and the wear resistance is improved by 3 times.
3.2 To improve the powder rate of powder coatings
in the production and application of powder coatings, powder coatings powder rate has been a major problem for manufacturers and customers. If the powder rate on the powder is low, a large number of powders will fall back during the construction process, the utilization rate of the powder will be reduced, and the spraying speed will be reduced, which will directly affect the continuity of the process and greatly reduce its economic benefits.
In the process of spraying, the particle size control of the powder used in the friction gun is strictly controlled, because the powder particles must have a certain speed and the inner wall of the gun tube in order to carry a sufficient positive charge, to achieve powder adsorption on the work piece, if the powder belt power is too small, low electrostation gravity, the powder rate will be reduced. Therefore, from the spraying machine, it can be known that the main adsorption force of electrostectrulation spray is static electricity, the powder rate on the powder, mainly depends on how much powder particles are charged.
many industries today add gas-phase alumina to powder coatings to achieve increased powder rates on coatings. Alumina itself is a large positive charge, can effectively improve the frictional charge of the powder, and effectively overcome the Faraday cage effect in the spray process, suitable for electrostitive spraying process. In the spraying process, alumina particles will be evenly distributed on the substitut surface, effectively enhance the frictional charge of the powder coating, enhance electrostitive gravity, powder can be better adsorbed on the work piece, improve powder rate, reduce powder recovery rate, improve the utilization rate of powder.
3.3 Increase the fluidity of powder coatings
when the fluidity of powder coatings is low, the phenomenon of irregular powder shape, powder particle adhesion, large particles, poor looseness. In the process of spraying the use of low-flowing powder coating, the construction process will appear high recovery powder quantity, reduced utilization rate, slow spraying speed and other issues, directly affect the continuity of the process and greatly reduce its economic benefits. Therefore, it is necessary to improve the flow of powder coatings to improve efficiency, while ensuring the quality and stability of powder coatings.
study found that by adding alumina nanomaterials by gas phase method, the adhesion between powders is effectively reduced, and the effect of increasing mobility is played. By adding a certain amount of gas phase alumina and stirring it thoroughly during the powder coating chip crushing phase, Because the gas phase alumina has a unique nanostructure and surface positive electricity, so that it is orderly combined on the surface of the substation particles, forming an orderly outer coating, and the overall structure of the substation particles for orderly movement, effectively reduce the static gravity between particles and particles, while avoiding the powder due to Van der Wah force, moisture absorption, particle friction and other phenomena between the bonding, effectively enhance the flow of powder, powder looseness is also significantly increased, the powder is also significantly increased.
3.4 Improve the wear resistance of powder coatings
With the development of science and technology, machinery in the modern industry more and more important role, but mechanical parts wear failure is also a loss for enterprises, Mechanical part wear mainly occurs on the surface of material contact, the most cutting-edge technology to improve the service life of mechanical parts is to apply a ceramic film on the surface of the metal material to reduce wear, in the preparation of metal-based ceramic coating needs to add gas phase nano-alumina to improve its performance, due to the high dispersion of nano-alumina, its particle size distribution is very uniform, and has a high ratio surface area, hardness and purity, so gas-phase nano-alumina in the coating of the coating is very uniform. When the nano-alumina addition amount reaches 2%, the coating surface appearance is relatively smooth and flat, and the coating and substation binding very closely, the internal structure of the coating is also very dense and uniform, can greatly improve the wear resistance and strength of the coating, improve the service life of metal parts.
4 Conclusion
alumina, as an inorganic nanomaterial with superior performance, plays a key role in improving the performance of powder coatings. At present, Guangzhou Jibisheng has mastered the core production technology of gas phase alumina, and has the independent intellectual property rights of this production technology, production capacity has reached 300 tons / year, the future will also carry out technical transformation to achieve higher output value, higher quality gas phase alumina production line. At present, the gas phase alumina has been pushed to the domestic market, improve the domestic gas phase alumina in the domestic market share, thereby reducing the cost of such products, is conducive to promoting the domestic powder coating industry to a more environmentally friendly, higher-end direction of high-speed development. In the future, we will continue to carry out the application of gas phase alumina in other fields, open up the international market, so that domestic gas phase alumina products to the international, gas phase alumina has a good development prospects.
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