The application of water-based heavy anti-corrosion coatings in port machinery products

1, Introduction
In recent years, with the acceleration of China's industrialization, the environmental pressure has been not to be ignored. From the research field of anti-corrosion coatings, due to solvent-based, a large number of organic compounds are evaporated into the atmosphere, affecting the air, water environment and so on. At the same time, threatening human health, and low-carbon economic development needs, with the State Council issued on September 10, 2013 "air pollution prevention and control action plan" notice issued, the Shanghai Municipal Government immediately followed by October 18, the same year issued the "Shanghai Clean Air Action Plan", in both action plans clearly require industrial enterprises must reduce VOC emissions, reduce air pollution.
machine products are mainly used along rivers, rivers and oceans, most of them in high humidity, high salt spray corrosion environment, according to ISO12944-2 standards, belong to C4, C5-I or C5-M severe corrosion environment. But the port machine is also a large steel structure products, once the completion of coating delivery, it is difficult to do regular coating repair and maintenance. Therefore, the heavy anti-corrosion coatings used in Hong Kong machinery products, generally designed to ensure that more than ten years or even more than 20a corrosion environment test, according to ISO12944-1 standards, to achieve H-grade durability. China has a part of the field such as steel structure, petrochemical and vehicles and other fields have successfully applied water-based metal corrosion-resistant coatings, environmental protection coatings have become inevitable. The selection of coatings with both heavy anti-corrosion performance and green environmental protection performance is the focus of the reform of the port machinery anti-corrosion system, the use of comprehensive port machinery equipment environment is harsh, maintenance difficulties, high protection requirements, taking into account the water-based coatings in the field of heavy anti-corrosion has no examples to learn from the situation, efforts to carry out the port machine heavy anti-corrosion field water-based anti-corrosion coating research and application.2, water-based paint selection and testing standards
2.1 water-based paint technology selection
port machine products are near-water operations, once the pollution will directly affect the national economy and people's livelihood, so the control standard for paint VOC is the lower the better, the research target is VOC content <100g/L.
can be diluted with water during construction, and is close to the construction performance of conventional solvent-based coatings. Solvent-free coating VOC emissions are also relatively low, but this type of coating often requires expensive special two-part spraying equipment construction, and mixed after the use of a very short time, film thickness, high cost, long curing time, and this kind of coating viscosity is large, for the membrane thickness requirements are not high projects, often need to add a large number of thin materials to reduce viscosity, so that VOC emissions go up again. Therefore, water-based heavy anti-corrosion coatings are the best choice for Hong Kong machine products.
considering the industry situation of water-based coatings, combined with the characteristics of Hong Kong machinery products, it is determined to carry out the research and application of water-based heavy anti-corrosion coatings on the inner surface of the box beam structure.
2.2 Water-based coating testing method
According to iso12944-2 standard classification of corrosive environment, the coating should meet the C5-M high salinity coastal environment H (high) durability requirements. According to ISO12944-6 laboratory test requirements in this environment, the salt-resistant fog 1440h test is carried out, which requires that the rust spread at one-side scratches after the test is not more than 1mm, no foaming, rust, cracking and peeling, while the adhesion of the coating should be ≥5MPa.
2.3 Salt-resistant spray test results of water-based coatings
after coating plate, maintenance and 1440h salt mist test and adhesion test and construction performance comprehensive assessment, the United States Tenmec Company's Series27WB water-based heavy anti-corrosion coating passed all indicators, and salt spray resistance performance is better than traditional solvent-based matching coatings (epoxy-rich primer and epoxy mid-grade paint), the test performance is compared to table 1.
Table 1 Heavy anti-corrosion coating performance test results
experimental conclusions:
(1) physical performance test,
water-based coatings and solvent-based coatings are in line with the requirements, water-based coatings slightly superior;
1.4 water-based coating application performance analysis
water-based paint salt spray detection shows that series 27WB construction and corrosion protection performance is outstanding. The product is a patented product of Tnemec Corporation of the United States, which translates as "inorgic hybridized water-based epoxy coating". Its solids are divided into 100%, the use of water needs to be added 15% to 20% to dilute, and a part of the water involved in the curing reaction, so the construction loss rate will be lower. The environmental performance and construction efficiency test data of the coating are in Table 2.
2 heavy anti-corrosion coating application
results show that series27WB water-based coatings have the following advantages.
1, a construction of 150 m anti-corrosion performance is better than the traditional two-way construction of 215 m;
2, VOC emissions are low, emission reduction of more than 99%;
3, high construction efficiency, after spraying construction 2h can be handled, and the traditional solvent-based coatings need 22h;
4, is a low surface treatment coating, pre-treatment up to St2 level can be constructed;
5, a single film thickness of up to 150 to 300 m;
6, water-based paint construction is not flammable and explosive risk.3, the application of water-based heavy anti-corrosion coatings in Hong Kong machinery products
although the anti-corrosion properties of water-based coatings in the laboratory has been demonstrated, but to get the recognition of the field of heavy anti-corrosion of hong Kong machinery, and to promote the application, we must promote from the following aspects.
3.1 user's approval
(1) from the technical aspects to dispel the user's concerns, finishing the water-based paint test data, especially with the conventional paint matching comparative data, from the anti-corrosion performance to obtain the user's trust in the water-based paint corrosion resistance;
(2) from environmental protection, safety awareness guidance, with the national quality, health and safety of the environment concept continues to improve, many users of green manufacturing, green environmental protection, Series 27WB has been certified green products in the United States, in line with the user's psychology;
(3) To strengthen user confidence with similar application success stories, select some similar successful application cases to increase the persuasiveness of implementation, Series 27WB's first application project——— CNOOC Huizhou refining base, after the cooling tower construction application 3a is still intact.
(4) to select the right project to implement, and soon officially confirmed the application of the Ningbo Port Project (2 shore bridges).
3.2 Change the construction habits of construction personnel
Construction personnel are used to solvent-based coating construction mode, so before the formal application must be changed through training to meet the skills requirements of water-based coating construction.
3.3 construction equipment requirements
Series27WB does not have special requirements for spraying equipment and can be sprayed with conventional spray equipment, but it is important to note that
(1) conventional coatings use solvents as a medium and cleaning solution, and Series27W, like other water-based coating properties, cannot contain solvents in the equipment. Before spraying, be sure to clean the solvents in the equipment lines,
(2) because the solid content of Series27WB coating is relatively high, belongs to the low viscosity high solid content of the coating, relative to the spray pressure is relatively high, generally choose 65:1 and above spray equipment.
3.4 Construction Process Control
There will be many differences between the construction of water-based coatings and solvent-based coatings, which require comprehensive improvement and improvement of the characteristics of water-based coatings from the construction methods in order to maximize the advantages of water-based coatings.
3.4.1 Race viscosity adjustment
Traditional solvent-based coatings can be adjusted at any time by adding thinners if they feel viscous during construction, as long as they do not exceed the active period (Potelife). Series27WB water-based coatings need to be mixed from the base material, curing agent mixing start to add the appropriate amount of water, the viscosity adjusted to the required state, in the subsequent use of the process, generally do not allow the addition of water dilution.
3.4.2 Weld repair and pre-coated
water-based coatings have poor immersion performance on substrate surfaces compared to traditional solvent-based coatings, which are characteristic of water-based coatings. Therefore, when coating the weld area or the area that needs to be pre-coated, to ensure sufficient film thickness, if the thickness is not enough, it is not possible to ensure that the steel substrate crest is covered by paint, will cause spot rust. At the same time, in order to achieve better coating effect, the special use of a pre-coated spray gun, the spray gun can greatly improve the film thickness and speed of pre-painting, directly improve the construction efficiency of water-based coatings.
3.4.3 Cleaning of construction equipment
The construction mode of water-based coatings is consistent with solvent-based, but because it uses water as an adjustment of viscosity, curing, so once the tool there is solvent, easy to cause paint film shrink holes and other ills.
3.4.4 Safety and Curing Ventilation
Water-based coatings are free of solvent volatilization during construction, and paint mist from spray construction is significantly reduced. But construction workers also need to do a good job of personal safety protection to prevent water-based paint mist into the body or into the eyes. Forced ventilation is also required during the curing of water-based coatings. Water-based coatings are volatile with moisture, which slows down curing if ventilation is poor.
3.4.5 to enhance the pre-painting work
Another characteristic of Series27WB water-based coating is to change the anti-corrosion mode of the previous two coatings, to a single-track construction, a single-track film anti-corrosion, will pay more attention to corners, side silk, weld pre-coated construction, emphasizing a construction to meet the required film thickness requirements. 4, conclusion
According to the characteristics of water-based coatings and the characteristics of port equipment, water-based coatings in the field of port machinery (in the steel structure box beam) to try to apply, this is the water-based coatings in the field of heavy anti-corrosion application of "zero" breakthrough, for the future water-based heavy anti-corrosion coatings in the port equipment promotion and application is of great significance.
(1) ensures safe production in a limited
Series27WB voC emissions as low as 6.6g/L completely eliminate the limited space of coating construction safety hazards.
(2) the first port machine coating green creation
water-based coating application will make the heavy pollution of the port machine coating industry to the green port machine corrosion protection transformation.
(3) highlighted the social responsibility of enterprises
the promotion and application of water-based coatings in Hong Kong is the implementation of "energy conservation and emission reduction" specific actions, fully reflects the sense of social responsibility.
(4) saved the social non-renewable resources
oil resources are limited and non-renewable, the use of water solvents is petroleum products, alternative solvents, but also a good measure to protect the earth's resources.
(5) reduces the comprehensive cost of coating construction
with the continuous introduction of national and local government environmental protection policies, environmental input (controlling the disorderly emissions of VOC) will become an important input to the cost of coating construction, and the use of water-based coatings will not exist VOC emission input.
Series27WB water-based coatings can not only achieve the thickness and corrosion-proof effect of traditional solvent-based coatings, but also at 24 degrees C at room temperature as long as 2h can be cured, to achieve a transportable state, curing 24h can be long-term immersion in water. Traditional solvent-based coatings, not counting the second road construction time, only the curing time of the second road needs at least 22h before curing can be handled. The production cycle of coating can be greatly shortened, reducing production costs.