Laboratory efficient coating machineThe common coating defects during operation mainly include wrinkles, uneven color, rough surface, bubbles, flower spots, liquid droplets or oily appearance on the surface of the coating film, sticking, marking bridging, peeling, cracking, exposed edges and rough surface, color difference, pinholes and bubbles. The following is a detailed analysis of these defects:

wrinkled skin

Reason: Excessive amount of coating solution, improper drying, uneven coating film that has already dried, or film-forming agent with a significant tendency to shrink.

Solution: Choose appropriate drying conditions, control the amount of coating solution, master the solvent evaporation rate, or select suitable film-forming materials.

Uneven color

Cause: The spray equipment is not well adjusted, the spray is uneven, and the pigment distribution in the coating paste is uneven.

Solution: Mix the film material into a dilute solution and spray multiple times, or grind the pigment and coating material evenly in a ball mill before spraying.

One sidedly rough

Reason: High drying temperature, fast solvent evaporation, or impurities mixed into the coating.

Solution: Reduce the drying temperature and use qualified coating film materials.

Bubbling (bubbles between the membrane or core)

Reason: Improper curing, rapid drying, or poor adhesion between the film and the underlying surface (or core).

Solution: Improve film-forming conditions, enhance film adhesion, and reduce drying temperature and speed.

Spotting (appearance of mottled spots or patterns on the garment membrane)

Reason: Plasticizers, pigments, etc. in the coating solution formula move during the drying process and are carried to the surface of the coating film.

Solution: Change the coating formula, choose suitable plasticizers, etc., control the film-forming conditions, such as reducing the drying temperature.

There are droplets or oil on the surface of the film

Reason: The formula of the coating solution is inappropriate, and there are compatibility taboos between its components.

Solution: Change the formula.

adhesive sheet

Reason: The spraying volume is too fast, which violates the principle of solvent evaporation equilibrium and causes the sheets to adhere to each other.

Solution: Reduce the spraying amount of coating solution appropriately, increase the hot air temperature, and accelerate the speed of the pot.

Sign the bridge

Reason: The film detached from the marked part of the core, forming a bridge across the mark, making it impossible to confirm the mark.

Solution: Slow down the coating spraying speed, lower the drying temperature, and control the hot air temperature at the same time.

peel off

Reason: Improper selection of clothing material, short feeding interval between two coatings, or physical and chemical properties of the product surface and coating solution that hinder adhesion performance.

Solution: Replace the fabric, adjust the interval time, adjust the drying temperature, and appropriately reduce the concentration of the coating solution.

crack

Reason: The rupture of the film coating around the tablet may be related to the quality of the tablet core and the unreasonable design of the coating solution formula.

Solution: Improve the quality of the tablet core, design the coating solution formula correctly, and choose tablet core excipients with low expansion coefficient.

Exposed edges and hemp face

Reason: Improper use of fabric, high temperature or premature blowing.

Solution: Pay attention to the amount of syrup and powder used. The syrup should be evenly wetted on the center of the tablet, while the powder should be able to adhere evenly on one side. When there is no moisture or brightness on one side, blow air again.

color difference

Reason:Laboratory efficient coating machineThe fan surface sprayed during liquid spraying is uneven, or the solid content of the coating liquid is excessive, or the speed of the coating machine is slow.

Solution: Adjust the angle of the spray gun, reduce the solid content of the coating solution, and increase the speed of the coating machine appropriately.

pinhole

Reason: Too much air was sucked in during the preparation of the coating solution.

Solution: When preparing the solution, avoid getting too much air involved.

bubble

Reason: High humidity of hot air, long spraying process, poor atomization effect.

Solution: Reduce the temperature appropriately, shorten the spraying process, and improve the atomization effect.