Princip elektroforézy
Electrophoresis is basically the same as traditional light and transparent electrophoresis. Anodic electrophoresis is performed under the action of direct current. Under the action of the electric field, the coated particles with charge move to the coated workpiece, so that the electrophoretic coating deposited on the surface of the aluminum profile precipitates, forming a film. The difference is in the type of coating and slightly different equipment.
Electrophoretic coatings include acrylic resins, melamine resins, pigments, solvents, neutralizers, additives and other ingredients. By thermal fixation in the viaduct layer of particles, the shape of the concave coating is essentially unchanged during baking and the appearance of the film is uniformly formed. Dimming can be adjusted by the ratio of high gloss paint to low gloss paint.
Elektroforetické potahování má ve srovnání s jinými metodami potahování následující vlastnosti:
(1) použití vodou-rozpustného nátěru, vody jako média roztoku, šetří spoustu organických rozpouštědel, výrazně snižuje znečištění ovzduší a rizika pro životní prostředí, bezpečnost a zdraví a zabraňuje skrytému nebezpečí požáru;
(2) vysoká účinnost povlaku, ztráta povlaku je malá, míra využití povlaku může dosáhnout 90 procent 95 procent;
(3) Jednotná tloušťka filmu, silná přilnavost, dobrá kvalita povlaku, všechny části obrobku, jako je vnitřní vrstva, průhyb, svar a další místa, mohou být rovnoměrné, hladký film, vyřešit problém povlakování jiných metod povlakování pro obrobek složitého tvaru ;
(4) Vysoká efektivita výroby, konstrukce může realizovat automatickou nepřetržitou výrobu, výrazně zlepšit efektivitu práce;
(5) zařízení je složité, investiční náklady jsou vysoké, spotřeba energie je velká, teplota sušení a vytvrzování je vysoká, řízení nátěrů a nátěrů je složité, stavební podmínky jsou přísné a je zapotřebí čištění odpadních vod;
(6) Lze použít pouze vodou-ředitelnou barvu a barvu nelze v procesu natírání změnit. Stabilita barvy se při dlouhodobém skladování špatně kontroluje.
Za prvé, elektroforézní potahovací zařízení
Zařízení pro elektroforetické nanášení se skládá z elektroforetické nádrže, směšovacího zařízení, zařízení pro filtraci povlaku, zařízení pro regulaci teploty, zařízení pro řízení povlaku, zařízení pro napájení stejnosměrným proudem, mycího zařízení po elektroforetickém povlaku, ultrafiltračního zařízení, pečícího zařízení, náhradní nádrže a tak dále.
The size and shape of the electrophoresis tank should be determined according to the size, shape and construction process of the workpiece. Under the condition of ensuring a certain distance between poles, it should be designed as small as possible. The tank is equipped with a filter device and a temperature regulating device to ensure a certain temperature of the paint and remove impurities and bubbles in the circulating paint. The stirring device can make the working paint keep uniform and consistent, and the circulating pump is mostly used. The circulation of paint is generally 4-6 times per hour. When the circulating pump starts, the surface of the paint in the tank should be turned evenly. The function of the coating management device is to supplement and adjust the coating composition, control the PH value of the tank liquid, remove the neutralizer with diaphragm electrode and eliminate the low molecular weight components with ultrafiltration device. Dc power supply is generally used for selection of electrophoresis power supply. Rectifier equipment can be silicon rectifier or silicon controlled.
Za druhé, hlavní parametry procesu ovlivňující elektroforetické nanášení
1, napětí
Electrophoretic coating is a constant voltage method, the equipment is relatively simple, easy to control. Voltage has great influence on paint film; The higher the voltage is, the thicker the electrophoretic paint film is, and the coating ability can be improved accordingly for the parts that are difficult to be coated and the construction time can be shortened. But voltage is too high, can cause paint film surface coarse, easy generation after drying "orange peel" phenomenon. Low voltage, slow electrolytic reaction, thin and uniform paint film, poor penetration force. The choice of voltage is determined by coating type and construction requirement. Under normal circumstances, voltage and coating solid cent and paint temperature into inverse ratio, proportional to the distance between the two poles. Steel surface is 40 70V, aluminum and aluminum alloy surface can use 60 100V, galvanized parts use 70 85V.
2. Doba elektroforézy
The film thickness increases with the extension of electrophoresis time, but when the film reaches a certain thickness, it can not increase the thickness, but will aggravate the side reaction. On the contrary, the electrophoresis time is too short, the coating is too thin. The electrophoresis time should be as short as possible according to the voltage used to ensure the quality of the coating. General workpiece electrophoresis time is 1 to 3 minutes, large workpiece 3 to 4 minutes. If the surface geometry of the coated object is complex, the voltage can be appropriately increased and the time can be prolonged.
3, teplota povlaku
Coating temperature is high, film forming rate is fast, but the paint film appearance is rough, will also cause coating deterioration; Low temperature, less electrodeposition, slow film formation, thin and dense film. In the process of construction, due to electrical deposition part of the electrical energy into heat energy, mechanical friction in the circulation system to generate heat, will lead to coating temperature rise. General paint temperature control in some aspects 15 30 degree .
4, barva pevných bodů a poměr základny yan
The solid cent of the electrophoretic coating that sells on the market is generally about 50 percent , when construction, need to use distilled water to control the coating solid cent in 10 percent 15 percent . The solid content is too low, the covering power of the paint film is not good, the pigment is easy to precipitate, and the stability of the paint is poor. Solid points too high, viscosity, will cause the paint film rough loose, poor adhesion. The face base ratio of high gloss electrophoretic coating can be controlled at 1 to 4. As a result of actual operation in, the pigment quantity of coating can drop gradually, must add pigment to cent tall coating to adjust at any time.
5, hodnota PH povlaku
The PH value of electrophoretic coating directly affects the stability of bath. If PH value is too high, the newly deposited film will dissolve again, the film will become thin, and the film will be removed after washing after electrophoresis. PH value is too low, the workpiece surface gloss is inconsistent, the stability of the paint is not good, the dissolved resin will be precipitated, the paint film surface is rough, adhesion is reduced. Generally, the PH value should be between 7.5 and 8.5 during construction. During construction, cationic ammonium compounds accumulated in the paint due to continuous electrophoresis, resulting in an increase in PH value. The solution with low PH value can be added, the distilled water of the cathode cover can be replaced, ammonium ion can be removed by ion exchange resin, and the PH value can be reduced by anodic cover. If the PH value is too low, can be added to adjust the ammonium ethanol.
6. Odolnost povlaku
The impurities ions brought into the electrophoretic tank by the previous process of the coated objects cause the decrease of resistance value of the paint, resulting in uneven roughness and pinholes and other defects of the paint film. In painting construction, the coating should be purified. In order to obtain high quality coating, cathode cover equipment can be used to remove positive ions such as ammonium and calcium and magnesium impurities.
7. Vzdálenost mezi obrobkem a katodou
Short distance, high deposition efficiency. But the distance is too close, can make paint film is too thick and generation flow hangs, orange skin to wait for malady. Generally, the distance is not less than 20cm. For large and complex shape of the workpiece, when the external has been deposited very thick film, and the internal film is still thin, should be far from the cathode part, increase the auxiliary cathode.
Metody a dovednosti elektroforetického lakování
(1) Elektroforetické lakování kovového povrchu, jeho technologický postup je následující:
Pre-cleaning → on-line → degreasing → washing → rust removal → washing → neutralization → washing → phosphating → washing → passivation → electrophoretic painting → in-tank cleaning → ultrafiltration washing → drying → offline.
(2) The substrate and pretreatment of the coating have a great influence on the electrophoretic coating film. Castings generally use sandblasting or shot blasting for rust removal, with cotton yarn to remove floating dust on the surface of the workpiece, with 80 120 sand paper to remove residual steel shot and other sundries on the surface. The surface of steel is treated with oil removal and rust removal. When the surface requirements are too high, phosphating and passivation surface treatment can be carried out. Ferrous metal workpiece must be phosphating before anodic electrophoresis, otherwise the corrosion resistance of the paint film is poor. Phosphating treatment, generally choose zinc salt phosphating film, thickness of about 1 2μm, requires fine and uniform crystallization of phosphating film.
(3) The circulation quantity of electrophoretic coating system directly affects the stability of bath liquid and the quality of paint film. With the increase of circulation, the precipitation and bubble in the tank decrease. However, the aging of the tank is accelerated, the energy consumption increases, and the stability of the tank becomes worse. It is ideal to control the circulation number of tank liquid 6 8 times /h, not only to ensure the quality of paint film, but also to ensure the stable operation of tank liquid.
(4) Ultrafiltration system controls the concentration of impurity ions brought into the workpiece to ensure the coating quality. In the operation of this system, attention should be paid to the continuous operation of the system after operation, discontinuous operation is strictly prohibited to prevent the drying of the ultrafiltration membrane. The dried resin and pigment adhere to the ultrafiltration membrane and cannot be thoroughly cleaned, which will seriously affect the permeability and service life of the ultrafiltration membrane. The effluent rate of ultrafiltration membrane decreases with the running time, and it should be cleaned once for 30 to 40 days in order to ensure the ultrafiltration water required for leaching and washing.
4. Vynikající výkon produktu
(1) Vysoká průhlednost a plná velikost, se speciálním leskem a průhledností, povlak má vysoký trojrozměrný efekt a barva substrátu je zřejmá.
(2) vysoká tvrdost, při pečení při 180 stupních po dobu 30 minut může tvrdost dosáhnout 4 až 5 hodin.
(3) Dobrá tekutost, pevný film a hladký film.
(4) Silná vazebná síla a propustnost, povlak je všude, mokrý film a suchý film mají silnou vazebnou sílu.
(5) dobrý výkon, obrobek nemění barvu při teplotě pečení 180 stupňů 200 stupňů, odolává změně barvy a korozi, barva a lesk produktu jsou jasné a trvalé, účinek koroze je ideální.
(6) Průměrný elektroforetický efekt je dobrý, nátěrový film je rovnoměrný a hladký, při 90-200V může dosáhnout 10-16um, vysoká účinnost, nízká spotřeba energie.
(7) Dobrá odolnost proti nárazu a odolnost proti umělému potu.
(8) Lze jej použít pro hliník, pokovování, doplňky z drahých kovů, lampy a špičkovou-ochranu povrchu nábytku.
(9) It can be electrophoretic into a variety of color paste: titanium, ordinary gray, pure black and other colors. Because of the high screening rate of matte electrophoretic coating film, the extrusion die pattern on the surface of aluminum has a certain hiding effect, and also has a certain compensation effect on the color difference of dyeing process.
Pět hlavních charakteristik vysoce-kvalitního elektroforetického hliníku:
1, se silnou tvrdostí filmu, silnou odolností proti nárazu.
2, s vysokou přilnavostí filmu, není snadné spadnout stárnutí.
3. Má lepší odolnost proti opotřebení, odolnost proti povětrnostním vlivům a odolnost proti alkáliím než oxid hlinitý.
4, barva povrchu je bohatá, krásná, se zrcadlovým-efektem lesku.
Šestá, princip a aplikace zhášecího nátěru
With the development of electrophoretic coating technology, in China's coating industry, it has become the world's top coating manufacturers, formed relevant industrial groups, and actively promote the technological revolution and development of traditional coating field. During this period, bright and bright paint with its bright colors and bright colors and welcomed by consumers, and in a long period of time by the paint market. However, with the improvement of people's living standard, on the one hand, consumers feel that high gloss coating is more serious than reflective coating, which is harmful to people's eyes. On the other hand, consumers have an increasingly casual, fashionable and personalized aesthetic concept. Coupled with the booming demand of China's electronics and electrical industry. These factors have led to a sharp increase in the demand for low-gloss coatings with a soft appearance. At the same time, how to produce matte coatings must be considered.
Sedm faktorů lesku
Light projected onto the surface of the object will reflect light, and the surface of the object will reflect in light. Different surfaces have different glossiness. Measuring the surface size of light reflected by light is called glossiness. Glossiness is expressed as a percentage. The higher the glossiness of a surface, the greater its ability to reflect light and its brightness. Glossiness is measured by a photoelectric gloss meter. According to the size of gloss, coatings can be divided into light, matte and weak light. Coating gloss classification (60 reflections) :
(1) Nízké světlo: lesk méně než 10 procent;
(2) mat: lesk 10 60 procent;
(3) light: gloss GT; 60 percent .
Za osmé, vliv faktorů lesku
Surface gloss of an object is closely related to surface roughness. When light is on the surface of an object, some of it is absorbed by the object, some is reflected and scattered, and some is refracted. The smaller the surface roughness, the more light reflected and the higher the gloss. Conversely, if the surface of the object is not flat, the scattered light increases, causing the luster to decrease. The surface roughness (H) of the polished object can be perceived by human vision, and the theoretical knowledge of the microscopic surface can be calculated according to the following formula: H = λ/ cos a, where λ is the wavelength of incident light; One is the incident Angle. If the incident Angle is 60 degree , h =1.1μm is calculated. When the surface roughness is greater than 1.1μm, it will show uneven and glossiness decreases.
