Epoxy solvent-free coating tank anti-corrosion coating application

1
, product composition the use of low-viscosity epoxy resin, pigments, additives and other high-speed dispersion and grinding to make paint materials, with low-viscosity modified amine
as a curing agent composed of two-component reaction curing antiseptic coating.
2
, product characteristics The biggest difference between solvent-free epoxy coatings and solvent-based epoxy coating products is that the coating is not used in the process of coating manufacturing and construction applications

3
, product use
at present, China's petrochemical industry development is at a peak
China'
. From crude oil transportation, storage transit, pipeline transportation, refining production
to the storage of refined oil products, all need to build a large number of tanks, laying a large number of pipelines, such as the use of solvent-free epoxy coatings, and traditional solvent-based anti-corrosion coatings, with good thick coating, good corrosion resistance, construction safety and other advantages, in line with the "efficient, economic, environmental protection, safety, energy-saving" principle, with a very broad application prospects.
3.
1
Construction safety and environmental protection and energy saving
because ordinary solvent-based epoxy paint contains more than 30% of volatile organic solvents, even high solid epoxy paint, volatile organic matter content (VOC) is more than 10%. These organic solvents evaporate during coating and drying and are mixed with air to form an explosive mixture of gases. Some closed places (e.g. tank inner wall, etc.) for coating construction work, must be forced to carry out a large number of ventilation, safety management departments need to regularly measure the construction process of the tank wall oxygen content and flammable gas concentration, oxygen content of more than 18%, flammable gas concentration is lower than the lower limit of the explosion 10% before coating operations, so as to avoid the explosion of the single mountain tank similar events. The use of solvent-free epoxy paint due to the volatility of solvents is very few, the requirements for ventilation is greatly reduced.
, organic solvents are mostly toxic and harmful substances, have different toxic effects on the human body, in order to ensure the health of construction workers, it is necessary to limit their content in the air. The higher the organic solvent content in the coating, the more fresh air needs to be replenished, i.e. the greater the amount of ventilation required, the use of solvent-free epoxy paint means that this part of the ventilation can be reduced.
must emphasize the most prominent advantages of using solvent-free epoxy coatings to reduce the air pollution caused by the volatile organic solvents. At present, the world's environmental requirements are getting higher and higher, especially in some developed countries, the content of volatile organic compounds (VOCs) in coatings has been limited, the emission of volatile organic compounds has also been restricted. As a developing country, china, in order to catch up with the advanced level of the world, take the road of sustainable development, avoid taking the detour of pollution first and then treatment, and pay more and more attention to environmental protection. Therefore, strict restrictions on VOCs in coatings, so as to minimize environmental damage, to achieve zero emissions will be the future direction. In heavy anti-corrosion coatings, the solvent-free and hydration of coatings will be the future direction of development, while solvent-free epoxy coatings are more practical under the current conditions.
4.1
Excellent physical and mechanical properties
due to the large number of polar groups such as hydroxyl and ether in the molecular structure of epoxy resins, coupled with the active epoxy-based energy reacts with interface metal atoms during curing. The formation of extremely strong chemical bonds ensures excellent adhesion between the coating and substrate, especially the solvent-free epoxy corrosion-proof coating with excellent wet adhesion, which ensures excellent durability of the coating in the context of liquid media corrosion.
Solvent-free epoxy coating can form a enamel-like finish coating after cross-link curing, due to the high cross-link density and the benzene ring structure in the molecular chain, so that the coating is hard and flexible, good wear resistance, good scratch resistance, good impact resistance. Solvent-free epoxy coating in the process of reaction curing shrinkage is very low, with a single film thick, good edge coverage, less internal stress, not easy to produce cracks and so on.
4.2
Excellent chemical resistance
highly cross-linked solvent-free epoxy anti-corrosion coating with excellent chemical resistance, resistance to seawater, moderate acids, alkalis, salts, various oils, fatty hydrocarbons and other chemicals long-term immersion.
4.3
Excellent corrosion resistance
solvent-free epoxy coating because it does not contain volatile organic solvents, in the drying process will not form a pore left by solvent volatilization, and film thickness, coating tightness is excellent, can effectively resist water, oxygen and other corrosive media through the coating and corrosion of steel.
4.4
Economy
Although the unit price of solvent-free epoxy coatings is slightly higher than solvent-based epoxy coatings, but the economics of anti-corrosion coatings can not be measured only by unit price, solvent-free epoxy coating solids Nearly 100%, in the case of reaching the same coating thickness, the amount of paint required is less than the use of solvent-based epoxy coating, in addition, because solvent-free epoxy coating can be up to high film thickness, can reduce the number of construction channels, thereby reducing the cost of coating construction.
5
Solvent-free epoxy coating construction
Because the use of solvent-free coating is a solvent-free epoxy coating, paint solid content of more than 98%, compared with solvent-based epoxy coating, there are some differences in construction performance, the biggest difference is the increase in viscosity and the shortening of the operating period. Solvent-free epoxy coatings have a high viscosity, which increases the requirements for spraying equipment. In the past, the traditional products have air spraying process and the old airless paint pump, simply can not spray this paint out normally, so the need to add pressure than higher new airless paint pump. However, in the construction process, because it does not contain solvents, its drying, curing process is not dependent on the volatile solvent, but completely dependent on its own curing reaction, its reaction process is faster, and affected by the temperature, therefore, the two-part mix has a shorter use period. Although the use period of the coating can be adjusted by the selection of curing agents in the formulation, but relative to the operation period of 2-8 hours of solvent-based epoxy paint, is still greatly shortened, and the longer the operating period of the coating, the longer the drying time required, which increases the difficulty of construction. In order to solve this difficult problem, attention should be paid to the following measures:
(1) solvent-free epoxy coating purchase should pay attention to the construction conditions, construction conditions include the site feasible construction methods (double feed thermal spray, single feed airless spray, roller brush, etc.) and construction environment temperature, according to the construction conditions to choose the appropriate solvent-free epoxy coating varieties or require paint manufacturers to adjust their construction performance to meet the construction conditions on site requirements. It is usually not suitable to choose solvent-free epoxy coating when it is less than 10 degrees C, it is recommended to use winter-type solvent-free epoxy coating when it is less than 10 degrees C, and summer-type solvent-free epoxy coating is used when it is above 20 degrees C, which is conducive to obtaining the appropriate operating period and coating drying time.
(2) Coating preparation must take into account the construction capacity during the life of the period, during which time can be used up how much on how much to match, so as not to too much ingredients too late to use resulting in gel waste.
(3) If the use of single-tube feed high-pressure airless spray method construction, it is advisable to choose a pressure ratio of large airless spray pump, appropriate nozzle pipe length, improve the total output fluid pressure to ensure smooth feed and atomization is good, select the appropriate caliber and flow nozzle to ensure that the mixed paint can be used during the operating period. In addition, winter construction due to the lower temperature, paint viscosity greatly increased, according to past experience is to increase the thinner method to reduce viscosity, but in the use of solvent-free epoxy, if only rely on this method will lose the use of solvent-free epoxy significance. Therefore, in the course of use as far as possible to store the paint indoors or properly preheat, so that the temperature of the coating itself is not less than 15 degrees C, in order to improve the temperature of the coating to reduce viscosity, to meet the requirements of spraying, and appropriately increase the pressure of the paint pump, as far as possible to shorten the length of the paint tube, so that the coating can be normal spraying.
(4). Construction with a two-tube feed high-pressure airless spraying device with a heating device is the best way, such as GRACO's Xtreme Mix and XTR products and Chongqing Changjiang Coating Machinery Factory SZD2 electronic ratio two-component sprayer, This device is characterized by: a, for high viscosity solvent-free epoxy coatings can be preheated in advance of the methyl B parts, and then viscous solvent-free epoxy coatings such as preheated to 40-70 degrees C can obtain a lower viscosity to fit feed and atomize. b, due to the paint meth and B parts of the feed, proportionally mixed in the mixing cavity quickly sprayed out, which solves the problem caused by the solvent-free epoxy paint pre-mixed operating life (Pot Life) is too short, and can be constructed fast-drying solvent-free epoxy coating, up to 2 hours of drying, 12 hours of complete curing, a single film thickness can even reach 2500 m.
Again, the improvement of solvent-free epoxy coating viscosity for roller brush construction, paint workers may feel more labor-thy-effort, may reduce efficiency, at low temperature because the viscosity is too high or even unable to carry out roller brush, and for the plane easy to exceed the design thickness, for the facade to prevent the phenomenon of hanging, it is appropriate to use a hard brush or short-hair roller force, Try not to apply too thick, a single coating film can usually be controlled in the range of 150-300 microns to prevent the phenomenon of hanging.
some particularly viscous solvent-free epoxy paint, which can be scraped when repairing construction in a small area.
Solvent-free epoxy anti-corrosion coating in the manufacturing and construction application process does not need to use volatile organic solvent as a dispersion medium, with safety, environmental protection, high efficiency, economy, energy saving and other advantages, if you understand its construction performance, equipped with the corresponding construction conditions, to solve some difficult problems in the construction process, can play a great role in storage tanks and pipeline anti-corrosion coating.