New product of steel drum epoxy coating - X-622 steel barrel interior coating
Shanghai Xugong Coating Technology Co., Ltd. Xu Guoxing
First, epoxy resin introduction
Epoxy coatings are one of the best coatings for metals and the earliest and most common internal coatings used in the domestic steel drum industry. One of the main film-forming materials for epoxy coatings is epoxy resin.
Epoxy resin is a polymer prepolymer which contains two or more epoxy groups and is aliphatic, alicyclic or aromatic. Due to the different raw materials and synthetic processes, the properties and molecular weight of the epoxy resin are different, and there are several forms of liquid, viscous and solid forms. In general, it can be basically classified into a glycidyl ether type resin, a glycidyl ester type resin, a glycidylamine type resin, an alicyclic epoxy compound, a linear alicyclic epoxy compound, a modified epoxy resin. (such as elemental silicone, phosphorus epoxy resin and urethane epoxy resin) and bisphenol A type resin.
Second, X-622 steel barrel inside paint introduction
The epoxy resin used in the X-622 steel drum is a bisphenol A diglycidyl ether (DGEBPA) type resin which is obtained by polymerizing epichlorohydrin and bisphenol A in the presence of sodium hydroxide.
Since both epichlorohydrin and bisphenol A are difunctional compounds, epoxy resins of this type are linear structures. This epoxy resin contains a hydroxyl group, an ether group and a very reactive epoxy group. Among them, the hydroxyl group and the ether group have a strong polarity, so that the epoxy resin generates a strong force with the adjacent interface. Therefore, the paint used in the X-622 steel drum has a strong adhesion to the surface of the steel drum, while the active epoxy group gives the coating and the steel drum surface a high strength bonding force.
The molecular chain of the bisphenol A diglycidyl ether (DGEBPA) type epoxy resin used in the X-622 steel drum internal coating is carbon-carbon bond and ether bond structure, and the chemical property is very stable. Therefore, its chemical resistance and acid and alkali resistance are very good. In addition, since the epoxy group of the epoxy resin is at both ends of the molecule, the internal rotation resistance of the molecular chain is small, and the epoxy resin used in the coating for the X-622 steel drum is softened by low viscosity. Therefore, its flexibility is better. This is very suitable for the inner coating process of the steel drum industry (coating of the barrel and the bottom of the bucket, top coating, baking and curing, and then re-winding).
The X-622 steel drum inner coating utilizes the reactive epoxy group in the epoxy resin structure to crosslink and solidify with various organic compounds to form a strong three-dimensional network structure film, and the butanol etherified phenolic resin. Crosslinking at high temperatures further enhances the mechanical and chemical resistance of the coatings used in X-622 steel drums. The cross-linking curing reaction at this high temperature only releases three parts of water, no other by-products are released during the process, and the shrinkage is small, and the cross-linking curing has a very strong and dense network structure film, thereby further enhancing Adhesion, mechanical properties, corrosion resistance and chemical resistance of the coating.
Third, the characteristics of X-622 steel barrel internal coating
l, bisphenol A glycidyl ether (DGEBPA) type epoxy resin used in X-622 steel drum internal coating is treated with "X-6 technology" low viscosity softening, so under the same resin content, its Under the condition of low viscosity and resin content, its viscosity is low, which makes it easy to form a thick coating film at one time, which is beneficial to the coating process of steel drums.
2. No softener is added to the paint used in X-622 steel drum. Softeners are softened by increasing the molecular gap of the epoxy resin, but while achieving softness, the anticorrosive properties of the coating are affected by the increase in the molecular gap of the epoxy resin. The epoxy resin used in the X-622 steel drum is softened by low viscosity, so even if no softener is added, it can be curled freely after being applied to the steel drum.
3. No additives such as tackifiers, leveling agents and defoamers are added to the coatings used in X-622 steel drums. Because these additives improve the coating performance of epoxy coatings, they have a certain influence on the crosslinking of epoxy resin and butanol etherified phenolic resin, which easily causes defects of three-dimensional network structure film, so ultimately The corrosion resistance of the coating is affected.
4. X-622 steel drum inner coating completely adopts imported rutile titanium dioxide powder treated by particle surface treatment as pigment and filler, and eliminates the use of cheap pigments and fillers such as talc powder, calcium carbonate, barium sulfate, zinc barium white. Therefore, the surface of the coating film is bright and smooth, and the coating film has excellent corrosion resistance.
5. Because the bisphenol A diglycidyl ether (DGEBPA) type epoxy resin used in the coating of X-622 copper barrel contains hydroxyl and ether bonds, it can form a chemical bond with the free bond on the metal surface, so Steel drums are the best adhesion coating.
6. After the cross-linking and solidification of the coating in the X-622 steel drum, the structural stability of the carbon-carbon and ether bonds in the molecular chain is greatly enhanced, and the coating film structure is more dense, so the chemical resistance of the coating film is enhanced. The properties (especially alkali resistance) make the coating further enhanced resistance to composite media corrosion.
7. After the X-622 steel drum is cured with a coating film, the coating film forms a three-dimensional three-dimensional structure, so the coating film has high mechanical strength, stability and insulation properties.
8. After the film is cured in the X-622 steel drum, the adhesion between the film and the other resin film is not very good due to the compactness and stability of the film itself. Therefore, it is not suitable to apply other coatings on the film. If the steel drum is coated with two layers, the first coating should be baked at a lower temperature for a shorter period of time.
9. The common problem of bisphenol A glycidyl ether epoxy resin is poor weather resistance, easy to be pulverized by ultraviolet light irradiation, so the paint used in X-622 steel drum can not be used as steel drum outer coating.
10. According to China GB4805-1994 "Sanitary Standard for Epoxy Phenolic Paint on Canned Inner Wall of Food", the content of free phenol and free formaldehyde in the coating after baking epoxy phenolic paint should be less than 0.1 mg per gram, but X-622 paint The Shanghai Institute of Preventive Medicine has not detected the test. The safety and health indicators of other indicators such as evaporation residue and potassium permanganate consumption are also more than three times higher than the above national standards. Therefore, X-622 coating can pass SGS international certification and meet the US FDA standards for food and drug coatings.
In fact, the epoxy resin of the butanol etherified phenolic resin is completely non-toxic, and the fully cross-linked cured coating film is subjected to an oral test LD50 of 15000 mg / kg or more in rats, and is negative by Ames test, which proves that there is no It is surprising, cell-mutated, and carcinogenic, so it can be used for the inner wall coating of food steel drums. But here is the complete cure, if not fully cured, then of course it is toxic, and all the properties of the coating are not reflected. Conversely, if the curing temperature is too high, the original properties are destroyed in addition to the coking of the coating. Other toxic gases such as propylene and methyl chloride are also produced. Therefore, it is preferable that such a coating is preferably baked at a temperature of 182 ° C for 45 minutes. For a tunnel that cannot form a 40 minute period, it can also be cured under conditions of about 225 ° C for about 10 minutes.
4. Physicochemical properties of X-622 steel drums for internal coatings
1, the main physical properties:
2. Main chemical properties:
Plastic Shampoo Bottle,Big Volume Plastic Bottle,Lotion Bottle with Lids,PET Bottle 200ml
Shijiazhuang HuangJia Trading Co., Ltd , http://www.hj-cosmetic.com