Application standards and schemes for water-based industrial coatings.

Abstract: This paper introduces the development of water-based industrial coatings, summarizes the relevant national policies and regulations, elaborates the national and industry standards referenced in the application process of water-based industrial coatings, cites coating design schemes in different fields, analyzes the existing problems at this stage and the future development direction.
0 foreword
With the strengthening of national efforts to prevent and control air pollution, various places have also introduced VOC control measures, and formulated local policies and regulations. The enhancement of people's environmental awareness, as well as the improvement of national education level, the personnel engaged in coating operations have also had a scientific understanding of the harm of solvents, so the application of water-based coatings, high solid sub-coats, powder coatings and other environmentally friendly products is an inevitable trend in the field of coating developmentEspecially with solvent-based coating process, equipment similar to water-based coatings, in recent years in the field of industrial coating rapid development, and gradually in the construction machinery, special vehicles, bicycle tricyriers, commercial vehicles, equipment facilities, steel structure and other fields to achieve successful applications, at the same time, water-based coatings related to the national and industry standards have been introduced, which also provides a standard and basis for the water-based coating industry. In recent years, the domestic increase in the research and development and production of water-based resins for coatings, water-based aliclicic acid resins, water-based acrylic resins, water-based epoxy resins, water-based polyurethane resins, etc. have significantly improved performance, while foreign water-based resin brands in the domestic factory production and sales, to solve the supply and price of the dual problems, these have provided adequate conditions for the development of water-based coatings.
1 Water-based industrial coatings
advantages and disadvantages of water-based industrial coatings
the biggest characteristics of water-based coatings are safe and environmentally friendly. Because it does not belong to the flammable, explosive, toxic, corrosion-prone category of dangerous chemicals, in transport, storage, construction and other links are safe and convenient, while the construction of low odor, and low-to-medium solid solvent-based coatings, can greatly reduce VOC emissions, by many government environmental protection departments, coating enterprises, coating personnel, consumers of all ages. However, due to the existence of moisture, water-based coatings with slow volatilization rate, large surface tensor and other objective problems, compared with solvent-based coatings, in gloss, plumpness, rust inhibition, construction tolerance, rapid film-forming process, early drying after the physical and chemical properties, there are still some gaps, which affect the application of water-based coatings in some specific areas, therefore, hydration coating also needs to be in-depth research in resin and coating research and development innovation, coating process and equipment improvement.
market potential of industrial coatings
according to the field of paint use, divided into architectural coatings, industrial coatings, which is divided according to the category. The industrial sector is more subdivided, according to the current application of the industrial field, some experts pointed out that cars, coils, powders, furniture statistics, other industrial protection into one category. According to this method, the yield of the main varieties of coatings in the last 3 years is shown in Table 1. As shown in Table 1, the output of construction coatings in 2017 was 745 t, accounting for 36.59% of the total output, the output of industrial protective coatings was 5.77 million t, accounting for 28.34% of the total output, while the annual growth rate of nearly 10%, the growth rate of vehicle coatings, coil coatings was slower, the output of powder coatings reached the highest value of 175 t, the growth rate was 12.9%, with the increase of national environmental protection efforts, the increase of non-organic solvents. There are no separate statistics on the production of water-based coatings, and the market situation of industrial coatings is described below.
water-based applications in key industries
seeding applications
are currently less used in the marine field, some enterprises in the water-based inorganic zinc silicate workshop primer promotion and application work, but the proportion of applications is still not high; The product system involved has water-based epoxy, melphate thick slurry, acrylic, polyurethane, etc., are in the trial phase, mainly used in the construction area, cabin area, cabin area, etc. do not require long-term immersion media and do not need heavy anti-corrosion protection of the site. The standard of water-based coatings for ships has not yet been issued, and can only be used for coating design and acceptance by reference to solvent-based standards. The design of the heavy anti-corrosion coating can be tried in the specific parts of the upper building system and indoor compartment, mainly by reference to HG/T 5176-2017 "steel structure water-based anti-corrosion coating" standard, but other parts still can not meet the performance requirements. Because the water-based heavy anti-corrosion coating technology is not mature, C4 environment has applications, but less applications in ships, primers, intermediate paints, a construction film thick without solvent-based high, C5 environment and immersed in soil, water, oil and other liquids, no water-based solutions; The application of environmentally friendly coatings such as high solids and solvent-free coatings in this field is also an important means to reduce VOC emissions.
applications in the field
Since April 1, 2017, the national standard dry container manufacturers coating production lines, all to promote the use of water-based coatings product system. Up to now, the new production standard dry cargo box, in addition to the workshop sanding after the first epoxy zinc-rich primer, all water-based; The product system involved is, applied to the standard dry cargo tank water-based epoxy zinc-rich, water-based epoxy thick slurry, water-based acrylic paint, water-based aleate anti-rust coatings, water-based acrylic protective coatings, water-based epoxy primers, water-based polyurethane paint, etc., see Table 7. Water-based container coating applications are more, although at the beginning of the application of flash rust, coating efficiency reduction, single-box cost increases and other issues, but also appeared coating shedding, but the current water-based coating technology, under the premise of strict control of construction, is able to meet the performance requirements of the container market. Container water-based coating standards are more perfect, the standards are also set relatively early.
3.3 Bridge applications
water-related support systems have been used on concrete bridges, and steel-framed bridges are also experimenting with water-like bottom, middle and surface coatings, but at present water-escaturalization is slow. The water-based coating product systems involved are: acrylic, epoxy, fluorocarbon resin products applied to concrete bridges, inorganic zinc-rich, epoxy-rich zinc, epoxy cloud iron, polyurethane, fluorocarbon paint, etc. applied to steel structure bridges, see Table 8. Concrete bridge structure already has water-based paint standards, steel structure bridges currently have no clear standards to follow.
3.4 Applications in the field of steel structure
As of early 2018, Beijing, Tianjin, Yangtze River Delta and Pearl River Delta have all had strict restrictions on the construction of solvent-based coatings. For coating enterprises, production line modifications are required, VOC reprocessing units are added, and production is discontinued in foggy weather. In particular, steel structure products large volume, wide industry distribution, the average size of enterprises is small, paint spraying is often carried out in open places, the realization of VOC organized emissions is more difficult, resulting in air pollution, and the application of water-based coatings can greatly reduce VOC emissions, there is a lot of market space. In 2016, the steel structure coatings market was about 480,000 t, water-based coatings sales were 15,000 t, water-based ratio of 3%;
The main research and development and application difficulties are: water-based coating design system, approved by the design institute needs a long process; steel structure water-based paint application time is short, the current heavy anti-corrosion support does not have a long time of practical application cases; The specific matching of the steel structure system is shown in Table 10. The standard of water-based coatings in steel structures is relatively perfect, and is also one of the first areas to be promoted by the industry, but in areas with high anti-corrosion requirements, such as corrosion environments above C5, it is necessary to reduce emissions with the help of high-solid content products
3.5 applications in the field of construction machinery and special vehicle
s Engineering machinery, agricultural machinery, special vehicles belong to the industrial sub-sector, is expected to use more than 200,000 t of paint per year, all product systems for epoxy primers and polyurethane paint matching, different parts of the coating performance requirements are different, the current water-based coatings have been able to meet customer requirements. However, there are still some projects that need to be improved in the application process: exploring the wet and wet process, the process matching is slightly worse, polyurethane paint more than 80 sm, easy to start tweezers, water-based paint construction viscosity is large, equipment requirements are high, water-based products construction window narrow, affected by temperature, humidity, water-based repair coating interface problems. It is understood that Revo Heavy Industry, Hongchang Heavy Industry, Dongfeng modified vehicles, Dadi and other manufacturers use water-based paint system in bulk, Sany Heavy Industry Beijing, Kunshan, Shanghai several production lines are all water-based, Xugong, Lingong, Longgong and other enterprises are also trying to use water-based systems, the current overall degree of water-based less than 5%. With the strict control of environmental protection emission requirements, the hydration of special vehicle coating field shows a rapid upward trend. Construction machinery and special vehicles water-based coatings currently have no standards to rely on, can only refer to solvent-based coating standards and customer basic requirements, the urgent need for the introduction of relevant standards. By table 12 can be known, the general weighting, boom and other parts of the requirements are not high epoxy primer and polyurethane paint coating, coating film thickness of 80 to 120 m; Special vehicle coating line is relatively simple, the enterprise is not the same, the current more or similar "wet touch wet" process, primer spraying after 40 degrees C to maintain 10 to 15 min, and then spray paint, the last 80 degrees C baking 40 to 50 min. In the field of construction machinery large-scale coating has tried high solid content and solvent-free products, but there is no large-volume application, sheet coating
3.6 bicycle and tricyclosan applications
Research and development and application need to solve the difficulties: water-based bicycle composite coating film adhesion problem, bicycle paint color complex, water-oil system cover varnish plumpness gap, tricyrier products electrophoresis primer brand more, opposite paint adhesion adaptability requirements, the use of water-based dispersion to reduce VOC. At present, bicycle water-based paint standards have been developed, three-wheeler-related standards have not yet been issued. Higher requirements of bicycle coating, drawing on the technical requirements of automotive paint, the last varnish requires high plumpness, generally using high solid content varnish coating. Figure 1, Figure 2 is a bicycle and tricyil two typical coating schemes.
3.7 Petrochemical, power applications
petroleum and petrochemical field, in addition to inorganic zinc-rich, repair program to try water-based systems, other most of the use of solvent-based coatings, the entire supporting system water-based products are not up to performance requirements. The power industry involves anti-corrosion coating of steel structures (thermal power plant housing steel structure, various types of brackets, wind power towers, etc.), transformer industry, there are already water-based solutions to try, especially in the original infrastructure construction repair coating, low VOC water-based industrial coatings have environmental advantages. The application of water-based industrial systems for wind power towers can be found in Table 15. The difficulties in research and development and application are: the product line is complex, the current water-based coating does not have a complete program, long-term immersion in soil, water, oil and other liquid applications without corrosion protection program. Wind power tower water-based coatings are improving the relevant standards, Guo electricity group, Jinfeng Technology and other companies have also issued water-based coating technical specifications, other power and petrochemical areas of water-free standards can be followed.
4 Conclusion
(1) Water-based industrial coatings are one of the environmentally friendly coatings and play an important role in reducing VOC emissions.
(2) water-based industrial coatings in the field of heavy anti-corrosion and special needs is not much or similar to the "wet touch wet" process, the primer sprayed after 40 degrees C to maintain 10 to 15 min, and then spray paint, the last 80 degrees C baking 40 to 50 min. In the field of construction machinery large-scale coating has tried too high solid content and solvent-free products, but there is currently no large-volume application, thin plate coating also has the use of powder coating cases, such as Furen Technology, in the field of special vehicles are also trying powder coating applications, such as in the horse shop set Huajun powder coating automatic spray line. The specific package is shown in Table 13. To meet the coating requirements, upstream and downstream enterprises need to continue to overcome existing technical bottlenecks, or with other types of environmentally friendly coatings to use together.
(3) water-based industrial coatings brand is uneven, need to continue to develop relevant industry standards, standardized application. (4) There are many policies to encourage water-based industrial coatings, but when landing resistance is greater, it is necessary to continue to refine measures on the existing policy system, such as simplifying the EIA procedures for water-based coatings, and water-based coatings manufacturers do not have to enter chemical parks.
(5) Water-based paint raw materials, finished products, packaging, construction waste, etc. can be transported in accordance with the general goods and general waste emissions, at the same time, it is urgent to solve the identification process cumbersome, high cost problems.
(6) water-based industrial coating application cases are still few, and some areas of the test cycle is longer, with the rapid development of recent years, the replication of application experience, will usher in explosive growth.
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