The thickness of the coating applied on the surface of tinplate sheet varies. When drying at the same temperature and speed, it is very easy to cause insufficient hardening at the thickness of the coating and excessive hardening at the thin coating, resulting in the adhesion, hardness, and hardness of the coating. Corrosion resistance, bending resistance, impact resistance, etc. decrease, and for colored coatings, the color of the coating film will be different. The factors that affect the uneven coating on tinplate sheet are as follows.
1) The gap between the two ends of the roller and the roller is different. The tinplate sheet feeding is often caused when the gap adjustment between the rubber reel roller and the pressure coating roller, the feeding roller and the rubber reel, and the gap adjustment between the rollers are inconsistent from left to right. The thickness of the coating on the left and right is different in the direction.
Treatment method: When the thickness of the coating film is different, first use a plug gauge to check whether the gap between the two ends of the feeding roller and the feeding roller is consistent. When they are parallel to each other, adjust the gap between the reel roller and the pressure coating roller, the varnishing head and the glue roller, so that the three rollers and the two rollers are parallel to each other.
2) The viscosity of the paint is too high. The viscosity of the coating is too viscous, and the cohesion between the resin polymers is large. When the cohesion is greater than the adhesive force of the resin on the surface of the electrolytic tinplate sheets, the material cannot be evenly spread on the tinplate sheet, and the higher the speed of the coating machine, the easier it is to cause the electrolytic tinplate sheets,the surface is irregular and unevenly coating
Treatment method: Appropriately reduce the viscosity of the coating, or dilute the surface with a small solvent. The purpose is to reduce the cohesion between the resin polymers, so that the coating can flow evenly on the surface of the tinplate, and slow down the coating speed. Enough time to spread evenly on the surface of tinplate.
3) The rubber roller is not concentric. After the eccentric coating rubber roller is installed on the tinplate sheet coating machine, the different positions of its surface in the circumferential direction are different from the contact pressure between the electrolytic tinplate sheets and the pressure coating roller, which causes the coating film thickness to be different in the feeding direction of the tinplate surface. one pigmented paints have a color gradient from light to dark or from dark to light.
Treatment method: Re-polish the rubber reel roller.
