company news about Terminology for cathodic electrophoretic coating

CED technology: cathodic electrophoretic coating technology. 1, solid (NV) : that is, the concentration, indicating the weight ratio (%) of the resin and pigment in the paint. Is the proportion of components that form the film. When NV is too high, the problems are: secondary flow marks, film thickness increases, and paint recovery decreases. When the NV is too low, the problems are: the film thickness is reduced, the orange peel, and the swimming permeability is decreased. 2, PH: is the concentration index of hydrogen ions, the smaller the value, the stronger the acidity. PH range: 0-14, PH=7 is neutral, and CED is usually between 6.0 and 6.7, which is a weakly acidic solution. The problems caused by too high PH value are: the stability of the tank liquid is reduced → coating precipitation, condensation → blocking filtration, producing particles. Problems with too low PH value include: corrosion of equipment such as paint circulation pipes, reduced coulomb efficiency, reduced damage voltage, and redissolution with U/F washing. 3, conductivity (COD) : represents the electrode distance of 1cm (area of 1cm2 cathode-anode) conductivity (μs/cm), the greater the value, the stronger the conductivity. Generally MEQ value, NV, bath temperature high conductivity is large, PH high conductivity is low. If MEQ and NV are normal and the conductivity is high, it may be that a large number of impurity ions such as Na, Fe and PO4 brought into the tank by pre-treatment will accumulate in the tank, which will lead to reduced stability of the tank and easy to produce abnormal coating phenomena such as orange peel, pinholes and processing marks. The problems of high conductivity include: coulomb efficiency decrease, pinhole on galvanized sheet, damage voltage decrease, and orange peel. The problems of too low conductivity are: the stability of the tank decreases and the film thickness distribution is not uniform. 4, MEQ value: indicates the milligram equivalent of the neutralizer consumed by 100g of solids in the paint, the unit is mmol/100g, the conventional range is 0.19-0.29, which is an important parameter of the tank. General MEQ value ↑, conductivity ↑, PH↓. If ASH↑, MEQ↓. High MEQ problems include: coulomb efficiency, film thickness, permeability, damage voltage drop, galvanized plate prone to pinholes, corrosion of paint circulation pipes and other equipment, with U/F water redissolution. The problems of too low MEQ are: the stability of the tank decreases and the transmittance of U/F decreases. 5, ASH (ASH) : indicates the weight ratio (%) of the pigment in the solid composition. When ASH drops due to pigment precipitation in the tank, the coating film is easy to produce particles, and the filtration is easy to block. The problems of high ASH are: the film thickness decreases, the coating level loses light, and the orange peel is easy to produce. ASH is too low, the problems are: shrinkage hole resistance decreased, decreased permeability. 6, solvent content: indicates the total weight of organic solvents in the tank (%). The problems of excessive solvent content include: permeability, failure voltage drop, film thickness increase and uneven distribution. The problems that the solvent content is too low are: the film thickness is reduced, the coating film produces orange peel, pinholes, dry spots and other ills. 7, voltage - film thickness: under normal tank temperature, with the specified voltage, the specified time measured film thickness. The factors that affect the film thickness are: positive factors: solvent content, NV, tank temperature, construction voltage, energizing time Negative factors: MEQ, ASH 8, Coulomb efficiency: usually used to measure the film coating ability of electrophoretic coatings. Represents the weight of the film (mg/c) precipitated with 1 coulomb of electricity. Factors affecting coulomb efficiency include solvent content, NV, MEQ, ASH, tank temperature, construction voltage, etc. Problems caused by high coulomb efficiency: poor tank stability. Problems caused by too low coulomb efficiency: the permeability decreases and the electricity consumption increases. The coulomb efficiency tends to decrease after the tank aging. 9, swimming penetration: also known as dispersion ability, is a method to determine the uniform distribution of electrophoretic coating film thickness. In electrophoretic painting, the coating ability of the paint to the inner surface, cavity and back of the coated object. It is generally expressed by the height of electrophoretic paint on the test strip (cm). It is also the ability to make all surfaces of the complex coating coated with uniform paint film. The smaller the resistance value of the paint, the larger the resistance of the deposited paint film, the better the permeability. The electrophoretic paint with good permeability can ensure that the welding joints, deep holes and inner surface of the coated material are evenly painted, so that the anticorrosion ability of the paint film is enhanced. It is proportional to electrophoretic voltage, time and paint solid content. It is inversely proportional to the pH value, temperature and polar distance of the coating. There are glass tube method and steel tube method for the determination of swimming permeability. When measuring, insert a test strip into the glass tube (or stainless steel tube) of the tester, after electrophoretic painting, remove the test strip, after drying, measure the height of the electrophoretic paint on the test strip (measured in centimeters), the higher the height of the electrophoretic paint on the test strip, the greater the permeability. The steel tube method is suitable for the determination of electrophoretic paint with high permeability. 10. Impurity ion concentration: mainly refers to Na, Fe, Zn and other impurity ions brought into the main tank by the coating or hanging device in the previous treatment project. Fe ions are also brought into the main tank due to corrosion and other reasons of the coating circulation pipeline. To remove Na and k plasma, U/F filtrate can be discarded. The same method cannot be used to remove Fe ions, and can only be solved by replacing part of the tank. It is also important to strengthen the management of pure water. 11. L Effect: Electrophoretic test plate bent into L font is used to evaluate the coating state of the horizontal surface. → 12, polarity: the resistance value of the wet film per unit area precipitated by electrophoresis (kΩ· cm2). The problem caused by excessive extreme value: the film thickness is reduced, the coating film appears shrivelled, and the orange peel is easy to produce. The problems caused by too small extremum: the permeability is reduced, the film thickness is thicker, the film is rough, and the film thickness is uneven. 13. Renewal cycle T.O. or T/O: The cumulative solid fraction of the supplementary paint is equal to the solid fraction of the tank liquid, which is called a T/O.