What are the disadvantages of electrophoresis

The characteristics of anodic electrophoresis are: the raw material is cheap (generally 50% cheaper than cathode electrophoresis); The equipment is simpler and the investment is less (generally 30% cheaper than cathode electrophoresis); Low technical requirements; The corrosion resistance of the coating is worse than that of cathode electrophoresis (about a quarter of the life of cathode electrophoresis). The reasons for the high corrosion resistance of cathode electrophoretic coatings are:

The workpiece is a cathode, no anodic dissolution, and the surface of the workpiece and the phosphate film are not damaged; Electrophoretic coatings (generally nitrogenous resins) have a protective effect on metals, and the paint used is of high price and high quality. If you want to know more about it, you can consult Jinan CIFI Chemical****, thank you!

High-quality cathodic electrophoretic coatings.

Coated under the best swimming coating conditions, the appearance of the resulting electrophoretic coating is smooth, flat and plump, and there should be no particles, shrinkage holes, pinholes, stains and pig skin.

and other defects. The cathode electrophoresis primer coating can be applied almost without sanding, and can be applied directly to the middle coat or top coat for a high-grade decorative coating.

The appearance of the electrophoretic coating film is poor, in addition to the above-mentioned various paint film defects, there are also yin and yang surfaces, uneven gloss, smoothness, loss of light, the appearance is not plump, pigskin-like, rough paint surface, bad hand feel (not smooth when touched by hand, there is a rough feeling) and so on. The poor appearance of the electrophoretic coating film is generally caused by redissolution, poor L-effect and thermal flattening of the electrophoretic coating, too high pigment content of the tank solution, too low solvent content, too low flow rate of the tank liquid around the coated object, and small tank liquid.

Due to the redissolution of the coating film, the paint film becomes thinner, loses its gloss, and exposes the bottom.

The L-effect of electrophoretic coating is not good, resulting in different gloss and roughness of horizontal and vertical surfaces.

The pigment content of the bath is too high.

The organic solvent content of the bath is too low.

The flow rate of the bath around the coated object is too low or non-flowing.

Surface roughness of the substrate and phosphate film to be coated.

unevenness, affecting the appearance of the coating film.

The solid content of the bath liquid is too low.

The bath temperature is low.

Poor bath filtration.

The impurity ion content in the bath is high and the conductivity is high.

Too high prevention and control methods.

Eliminate the conditions for redissolving the film and strictly control the pH value and organic solvent content of the bath and cleaning solution.

The L-effect of the electrophoretic coating used was improved to control the coating below 15 m.

Add resin solution and adjust the pigment-to-base ratio of the bath solution.

Add the appropriate amount of organic solvent.

Strengthen the stirring of the bath liquid, and check the nozzle status or flow direction.

To improve the roughness and uniformity of the surface of the substrate, a dense film type phosphate film is selected to strengthen the cleaning after phosphating.

Increase the solid content of the bath.

Strictly control the temperature of the bath according to the process requirements.

Strengthen the filtration of the bath, and the filtration accuracy should not be higher than 25 m

Drain the UF solution and add deionized water.

The factors that affect electrophoresis are as follows:

1. Electric field strengthThe electric field strength is also known as the potential gradient, which refers to the potential drop per unit length. The electric field strength plays an important role in electrophoresis. The greater the strength of the electric field, the faster the movement of the charged particles.

According to the intensity of the electric field, electrophoresis can be divided into atmospheric electrophoresis (100 500V) and high-voltage electrophoresis (500 10000V).

The separation time of atmospheric pressure electrophoresis is long, and it is mostly used to separate macromolecular substances such as proteins; The separation time of high-pressure electrophoresis is short, and it is mostly used to separate small molecule substances such as amino acids, peptides, and nucleic acids.

2. The pH value of the solution determines the degree of dissociation of the substance, and also determines the net charge of the charged particles. The farther the pH of the solution is from the isoelectric point, the more charge the particles carry and the faster the electrophoresis speed. When separating a protein mixture, the appropriate pH value should be selected to facilitate the separation of each protein component.

In order to keep the pH of the solution constant during electrophoresis, a buffer solution must be used.

3. The ionic strength of the solution The ionic strength affects the electromotive potential (potential) of the particles, which should not be too high or too low, and the most suitable ionic strength is generally in.

4. Electroosmosis: The relative movement of liquid to solid support under the action of electric field is called electroosmosis. Since electroosmosis often coexists with electrophoresis, the movement of charged particles is also affected by electroosmosis. If the direction of electrophoresis is opposite to electroosmosis, the distance of the actual electrophoresis is equal to the distance of electrophoresis minus the distance of electroosmosis.

When selecting supports, care should be taken to avoid the selection of substances with high electroosmosis as much as possible.

5. Other influencing factors, such as the viscosity of the buffer, the interaction between the buffer and the dotted particles, and the temperature change during electrophoresis, also affect the speed of electrophoresis.