As we all know, the film is to print the surface of the printed matter, to improve the print surface roughness, strength, enhance the aesthetic effect, so that it is water-resistant, wear-resistant, improve the quality of printed materials and the effective means of the product, so the quality of the film to measure the pros and cons, Also mainly from the product's brightness, strength, adhesion and other aspects of examination.
Since the development of the water-based laminating machine in 1996, the water-based laminating machine technology has been promoted and applied. The water-based wet laminating film has been favored by customers because of its high brightness, high quality, easy recycling, and no pollution.
When the water-based laminating process was just promoted, due to the customer's lack of understanding of the process, concerns, fear of problems, in view of this, many customers have done a lot of tests, such as: Hubei Xinhua printing plant, in order to test the printed water-based coating The temperature, humidity, oil resistance and other properties, in the initial use of the machine to do the relevant coating test, regardless of temperature, humidity, oil, can reach the coating process requirements. (For details of the test process, contents, and results, see "Printing Technology", No. 9, 1999, etc.)
The lamination process is more complicated and the following points need to be noted in normal production:
Because the water-based glue can dissolve powder on the surface of the printed matter, the printed product will feel incomprehensible when the film product has snow spots. In fact, the reason is very simple. The water-based glue itself is also limited by the solubility. If the print is too dusty, The excess will not be completely dissolved by the glue and a large area of ​​snow will appear.
There are three ways to encounter this situation:
One is to coordinate the upper and lower processes and minimize the amount of dusting during printing;
Second, the amount of glue should be increased appropriately to increase the ability of glue to dissolve and spray powder.
The third is to clean up the surface of the printed matter before spray coating.
Cleaning Because the water-based film glue dries quickly, if it does not flow at rest, it will dry into rubber and form a solid block. If it is attached to the applicator roller or the pressure roller, local application of glue is too small, or local pressure is too large when pressure is applied. Therefore, the coating roller and the pressure roller should be kept clean during the lamination process.
If there is too much dust in the surrounding environment or there is dry rubber and glued film fragments in the glue, the coated product will have snow, so it should pay attention to environmental sanitation. The glue should be used up and should be poured back into the plastic barrel to seal it, or to take it. Pre-gel filtration method.
Discoloration of printed products This is mainly manifested in large-area gold printing and bronzing products. This is due to the chemical reaction of the chemically active elements in the glue and the gold powder.
The solution is: for gold products, special gold ink or special glue, or change the technology, bronzing products after the first foil bronzing, many manufacturers use this process, the effect is very good.
Paper detachment This phenomenon is easy to appear in the full version of the printed matter, because the surface of the ink layer is thick, the glue is difficult to wet, diffusion, penetration, and thus the bond is not strong.
The solution is: First, for this product, the glue manufacturer is required to increase the solid content of the glue;
Second, appropriately increase the thickness of the glue layer;
Third, increase the external temperature during film coating and product drying;
Fourth, check whether the glue is deteriorating, check the date of manufacture and shelf life of the glue;
5. Whether the film exceeds the shelf life and check whether the corona treatment of the film is not effective;
Deformation There are several reasons for this situation:
First, the amount of glue is too large, because the large glue will inevitably make the paper absorb moisture. When any paper absorbs a lot of water, it will be deformed. So, if there is no snow point, try to reduce the amount of glue.
Second, the film tensile deformation is serious, this time should be properly adjusted to the film's loose tension, as long as the film can be very smooth and fit the paper, the tension is as small as possible;
Third, the winding tension is too large, in order to ensure that the product will be rolled after winding, the smaller the better the rolling force;
4. The temperature difference and the humidity difference of the external environment of the product are too great;
At present, there is also a kind of glue between the oiliness and the water in the country. The price is very cheap. It does not need to be dried and dried naturally after coating. The brightness and flatness of the product can meet the requirements, but it has strong Irritating odor, unstable quality and can be used for paper products, high-end products suggest the use of white manufacturers environmental protection glue. With the rapid development of the printing and packaging industry, waterborne coatings will have a broader perspective. (Shengtian Printing & Packaging Machinery Co., Ltd. Yang Guojun)
Water-based coating process analysis
December 22 09:08:30, 2023
Calculator Writing Tablet,Calculator Guangdong Jishengke Industrial Co.,Ltd , https://www.jskpad.com