13. When the heavy-duty plastic roller has a horizontal blanking, too much paint accumulates at the cut-outs in the horizontal direction, and the cut-out portion forms a drip of the paint. In particular, the white magnetic oil coating is prone to heavy skin.
1) The rubber drum is rubberized. The rubber at the empty slot becomes hard, and it is easy to absorb too much paint at this position, resulting in a thicker upper and lower coating film thickness at the horizontal blanking incision.
Treatment method: Replace the new roller.
2) The viscosity is too low. Because the viscosity is too low, the fluidity of the paint is relatively large, and it is easy to open the paint accumulation at the lateral incision.
Treatment method: To improve the coating viscosity, or to reduce the viscosity of the coating, it is better to use a strong volatile diluent.
3) The amount of coating film is large. When the amount of coating film increases, the notch groove and the material tend to accumulate, and heavy skin appears.
Treatment method: Under the condition of satisfying the quality of the product process, the coating film amount should be reduced as much as possible, so as to reduce the production cost and avoid heavy skin.
14. After the wrinkle tinplate is applied, the wet film is even and smooth, but after the baking, the gloss of some coating film disappears to form a wrinkle surface and a crack pattern appears. This is mainly due to the short time in the preheating zone of the drying room after tinplate coating, and the coating Some of the solvent is not volatilized in the preheating zone of the drying room, and the high-boiling solvent rushes away from the coating surface when entering the constant temperature zone, causing wrinkling. In addition, there is a defect in the exhaust air of the drying room, there is cold air in the furnace, and wrinkles also occur when the hot air cannot fully flow. Wrinkles look like spider nests, dots, frosts, etc. This phenomenon is more obvious in the wet winter.
Treatment method: Make sure that the exhaust gas is fully ventilated in the furnace, reduce the coating speed, prolong the preheating time, and the solvent in the paint slowly evaporates in the preheating zone. Low boiling point solvents are used to adjust the coating viscosity during production. Thinning the coating thickness can also avoid such appearance problems.
15. When tin-coated tinplate coating paint is baked at high temperature, tin layer melts on the surface to form tin spots. The general occurrence of melting tin is due to defects in the surface properties of tinplate, but it cannot be ruled out that the temperature of tinplate in a certain part of the oven is too high, and tin melting occurs.
Treatment method: First check whether the four corners of tinplate and its center are in the same temperature curve in the oven. If they are not the same, you need to adjust the amount of air sent from the burner to the hot air in the direction of inconsistency. . Generally, under the condition that the coating does not affect the polymerization of tinplate in the tinplate, proper lowering of the baking temperature can prevent the occurrence of melting tin.
16. Leakage 1) Grease leaks. The tinplate conveying device, the flower rack conveying device and the receiving device need to be lubricated and lubricated, which easily leads to excessive oiling and oil leakage. When the tinplate passes through the back surface, the back surface of the tinplate is easy to be contaminated. When the tinplate is coated on the back, the oil stain can not be absorbed by the paint. Its surface.
Treatment method: Check whether there is oil in the tinplate conveying device, the flower rack conveying device, and the receiving device. If the oil leaks, you can scrub the oil with gasoline. In addition, due to grease on the hands, when tinplates are moved, the grease on the hands can easily stain the tinplate, causing the coating to be smeared in the next process.
2) Dew point missed. Tinplate is poorly packaged, and it is affected by moist dehumidification during transportation. The surface is prone to dew point. Especially in the spring of heavy humidity in the south, the tinplate is exposed to the surface of the air and dew condensation occurs quickly.
Treatment method: dry baking tinplate can be coated. If there is dew point due to moisture, it is best to open the package when it is opened.
3) Tinplate. In the surface treatment process, tinplate manufacturers have problems with surface properties, so that the surface tension of the coating applied on the surface of the tinplate is inconsistent, resulting in missing coating. In addition, the surface of the tinplate is not evenly or excessively coated with protective oil, and it is also likely to cause leakage coating.
Treatment method: If the tinplate surface performance caused by different tin, can only replace the tinplate; If too much or uneven protection of the oil, generally use high temperature 205 degrees Celsius bake degreasing, and sometimes need to use gasoline to scrub the leaked parts after Coating can eliminate leaking.
17. Dirty 1) Poor production environment. Too much dust in the work environment, the dust of business mixed into the paint, which affects the appearance of the coating, but also affect the physical and chemical properties of the coating.
Treatment method: Before the tinplate is sent to the production workshop, the dust on the outer packaging should be removed, and the workshop environment should be cleaned frequently.
2) There is dust in the oven. The solvent or gas in the coating is incompletely burned in the combustion furnace, producing particulate char, which is adsorbed by the wet coating as the coated tinplate passes.
Treatment method: Make sure that the gas in the combustion furnace is blue, and clean the coal house regularly. Usually use waste tinplate, coat the surface with a layer of waste coating, and put it in the drying room under low-temperature baking conditions. Charcoal exhaustion; reduce the paint viscosity as much as possible without the use of high-flammability macromolecular solvents as a diluent.
3) The residue on the flower stand falls off. The supporting tinplate iron frame is contacted with volatile solvent molecules during long-term production, and a layer of gold-yellow residue is accumulated on the surface area. This layer of residue is accumulated to a certain thickness and can easily fall off, especially when the production is started after shutdown. The object is more easily heated off.
Treatment method: Regularly remove the residue from the flower rack.
4) There is dirt in the paint. The production control of the less-stocked manufacturer is lax and the dirt is mixed; the coating cleaning and coating apparatus is not completely used in the coating production, resulting in the contamination of the latter-stage paint, especially the coating of the colored paint in the previous process. It is especially noticeable when the following process is used to coat colorless materials.
Treatment method: When there is particulate dust in the coating, use fine filter to filter or return the product. When changing the coating in production, try to clean the coating device to avoid contamination of the previous process.
18. White magnetic surface yellowed 1) Varnish coated. After multi-color overprinting of tinplate, a layer of varnish is also applied to the surface of the ink. The coated varnish not only increases the gloss of the tinplate graphic appearance, but also enhances the flexibility, impact resistance, abrasion resistance, and other physical and chemical properties of the ink layer surface. However, in the actual production, different types of resin will cause the surface of the surface to be yellowed due to the low gloss printing surface. Relatively speaking, acrylic resin varnish is not yellowed at high temperatures, followed by amino polyester resin and alkyd resin varnish, and epoxy varnish is most yellowish.
Treatment method: Select the appropriate coating oil, especially for the cold phase white magnetic bottom of the printed matter, when the coating should not use epoxy Varnish.
2) baking temperature. Too high a baking temperature is also one of the reasons that causes the white magnetic surface to yellow.
Approach. Keeping the proper baking temperature and lowering the baking temperature when necessary help prevent the white magnetic surface yellow.
19. Printing ink discoloration In tinplate printing, printed products tend to have different problems in the color before and after the coating after the application of the coating. In particular, the spot color pattern is printed. Since the spot color ink is a combination of several ink colors, the color change is particularly noticeable when the coating is applied.
Treatment method: Before the spot color is printed, try the coating. First, a certain thickness of spot color is printed on the surface of the tinplate, and the coating is applied after drying. The contrast is whether the hue of the drying sample is the same as the hue required by the customer. (To be continued)
1) The rubber drum is rubberized. The rubber at the empty slot becomes hard, and it is easy to absorb too much paint at this position, resulting in a thicker upper and lower coating film thickness at the horizontal blanking incision.
Treatment method: Replace the new roller.
2) The viscosity is too low. Because the viscosity is too low, the fluidity of the paint is relatively large, and it is easy to open the paint accumulation at the lateral incision.
Treatment method: To improve the coating viscosity, or to reduce the viscosity of the coating, it is better to use a strong volatile diluent.
3) The amount of coating film is large. When the amount of coating film increases, the notch groove and the material tend to accumulate, and heavy skin appears.
Treatment method: Under the condition of satisfying the quality of the product process, the coating film amount should be reduced as much as possible, so as to reduce the production cost and avoid heavy skin.
14. After the wrinkle tinplate is applied, the wet film is even and smooth, but after the baking, the gloss of some coating film disappears to form a wrinkle surface and a crack pattern appears. This is mainly due to the short time in the preheating zone of the drying room after tinplate coating, and the coating Some of the solvent is not volatilized in the preheating zone of the drying room, and the high-boiling solvent rushes away from the coating surface when entering the constant temperature zone, causing wrinkling. In addition, there is a defect in the exhaust air of the drying room, there is cold air in the furnace, and wrinkles also occur when the hot air cannot fully flow. Wrinkles look like spider nests, dots, frosts, etc. This phenomenon is more obvious in the wet winter.
Treatment method: Make sure that the exhaust gas is fully ventilated in the furnace, reduce the coating speed, prolong the preheating time, and the solvent in the paint slowly evaporates in the preheating zone. Low boiling point solvents are used to adjust the coating viscosity during production. Thinning the coating thickness can also avoid such appearance problems.
15. When tin-coated tinplate coating paint is baked at high temperature, tin layer melts on the surface to form tin spots. The general occurrence of melting tin is due to defects in the surface properties of tinplate, but it cannot be ruled out that the temperature of tinplate in a certain part of the oven is too high, and tin melting occurs.
Treatment method: First check whether the four corners of tinplate and its center are in the same temperature curve in the oven. If they are not the same, you need to adjust the amount of air sent from the burner to the hot air in the direction of inconsistency. . Generally, under the condition that the coating does not affect the polymerization of tinplate in the tinplate, proper lowering of the baking temperature can prevent the occurrence of melting tin.
16. Leakage 1) Grease leaks. The tinplate conveying device, the flower rack conveying device and the receiving device need to be lubricated and lubricated, which easily leads to excessive oiling and oil leakage. When the tinplate passes through the back surface, the back surface of the tinplate is easy to be contaminated. When the tinplate is coated on the back, the oil stain can not be absorbed by the paint. Its surface.
Treatment method: Check whether there is oil in the tinplate conveying device, the flower rack conveying device, and the receiving device. If the oil leaks, you can scrub the oil with gasoline. In addition, due to grease on the hands, when tinplates are moved, the grease on the hands can easily stain the tinplate, causing the coating to be smeared in the next process.
2) Dew point missed. Tinplate is poorly packaged, and it is affected by moist dehumidification during transportation. The surface is prone to dew point. Especially in the spring of heavy humidity in the south, the tinplate is exposed to the surface of the air and dew condensation occurs quickly.
Treatment method: dry baking tinplate can be coated. If there is dew point due to moisture, it is best to open the package when it is opened.
3) Tinplate. In the surface treatment process, tinplate manufacturers have problems with surface properties, so that the surface tension of the coating applied on the surface of the tinplate is inconsistent, resulting in missing coating. In addition, the surface of the tinplate is not evenly or excessively coated with protective oil, and it is also likely to cause leakage coating.
Treatment method: If the tinplate surface performance caused by different tin, can only replace the tinplate; If too much or uneven protection of the oil, generally use high temperature 205 degrees Celsius bake degreasing, and sometimes need to use gasoline to scrub the leaked parts after Coating can eliminate leaking.
17. Dirty 1) Poor production environment. Too much dust in the work environment, the dust of business mixed into the paint, which affects the appearance of the coating, but also affect the physical and chemical properties of the coating.
Treatment method: Before the tinplate is sent to the production workshop, the dust on the outer packaging should be removed, and the workshop environment should be cleaned frequently.
2) There is dust in the oven. The solvent or gas in the coating is incompletely burned in the combustion furnace, producing particulate char, which is adsorbed by the wet coating as the coated tinplate passes.
Treatment method: Make sure that the gas in the combustion furnace is blue, and clean the coal house regularly. Usually use waste tinplate, coat the surface with a layer of waste coating, and put it in the drying room under low-temperature baking conditions. Charcoal exhaustion; reduce the paint viscosity as much as possible without the use of high-flammability macromolecular solvents as a diluent.
3) The residue on the flower stand falls off. The supporting tinplate iron frame is contacted with volatile solvent molecules during long-term production, and a layer of gold-yellow residue is accumulated on the surface area. This layer of residue is accumulated to a certain thickness and can easily fall off, especially when the production is started after shutdown. The object is more easily heated off.
Treatment method: Regularly remove the residue from the flower rack.
4) There is dirt in the paint. The production control of the less-stocked manufacturer is lax and the dirt is mixed; the coating cleaning and coating apparatus is not completely used in the coating production, resulting in the contamination of the latter-stage paint, especially the coating of the colored paint in the previous process. It is especially noticeable when the following process is used to coat colorless materials.
Treatment method: When there is particulate dust in the coating, use fine filter to filter or return the product. When changing the coating in production, try to clean the coating device to avoid contamination of the previous process.
18. White magnetic surface yellowed 1) Varnish coated. After multi-color overprinting of tinplate, a layer of varnish is also applied to the surface of the ink. The coated varnish not only increases the gloss of the tinplate graphic appearance, but also enhances the flexibility, impact resistance, abrasion resistance, and other physical and chemical properties of the ink layer surface. However, in the actual production, different types of resin will cause the surface of the surface to be yellowed due to the low gloss printing surface. Relatively speaking, acrylic resin varnish is not yellowed at high temperatures, followed by amino polyester resin and alkyd resin varnish, and epoxy varnish is most yellowish.
Treatment method: Select the appropriate coating oil, especially for the cold phase white magnetic bottom of the printed matter, when the coating should not use epoxy Varnish.
2) baking temperature. Too high a baking temperature is also one of the reasons that causes the white magnetic surface to yellow.
Approach. Keeping the proper baking temperature and lowering the baking temperature when necessary help prevent the white magnetic surface yellow.
19. Printing ink discoloration In tinplate printing, printed products tend to have different problems in the color before and after the coating after the application of the coating. In particular, the spot color pattern is printed. Since the spot color ink is a combination of several ink colors, the color change is particularly noticeable when the coating is applied.
Treatment method: Before the spot color is printed, try the coating. First, a certain thickness of spot color is printed on the surface of the tinplate, and the coating is applied after drying. The contrast is whether the hue of the drying sample is the same as the hue required by the customer. (To be continued)
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