Laminating is the combination of 15-20 lJm thick special film and prints to improve the surface gloss, strength and visual aesthetics. Film is generally oily, water-based and hot-press pre-coated three. Aqueous coating is economical and affordable, and it is currently the most popular method for coating in China. However, due to its own characteristics, it is also congenitally deficient and must be used with caution in some products.
1. Not suitable for large area (especially large field) graphic product film
Waterborne film-containing glue contains a certain amount of moisture. When used for laminating large-area (especially large-scale) graphic products, it will have a large area of ​​snowflake-like spots on the surface of the graphic, affecting the appearance of the product. . Although increasing the amount of sizing does not change much, it can only be replaced by an oil-based or hot-press precoat film coating process.
2. It is not easy to use for sizing of offset paper
I have used different areas and manufacturers of waterborne film glue to conduct batch trial production. Compared with oily, especially two-component glue film, the film is coated on offset paper products. Waterborne film products can easily cause paper and plastic products. Detachment, sometimes gently tearing, film and printing products can be completely separated, easy to cause quality accidents.
3 double-sided film products with caution
Some products are required to be coated on both sides due to customer requirements, such as water-based film coating process, because the moisture content of the glue is more, the moisture of the printed film after the film is difficult to evaporate quickly, resulting in ink crystal soft, can not reach The customer's request brings unexpected quality accidents.
4. It is not easy to bump after coating
When the waterborne film products are pressed and embossed, white spots and bow wrinkles are generated on the contact surface, and the paste is not firm, and foaming is severe and the film is prominent on the coated paper. We can pay attention to some rubber book covers. After the water coating, the cover side glue line is not very straight and has uneven marks, which seriously affects the appearance of the product.
5. Wait for the follow-up processing, preparation time is too long
Water-based film products must be laid flat after 24 to 48 hours after being divided into large pieces. Sometimes 40-500 degrees baking can flow into the next process construction. The main purpose is to stabilise the adhesive strength and the stiffness of the coated product after volatilization of its glue. Sometimes special assistance is required to meet the requirements of post-press processing.
To save costs for a certain product, the cover uses 105g/m2 double-sided coated paper. After being coated with water-based one-sided film, the cover is too soft and electrostatic adhesion is generated. The method of baking 72 hours and lightly coating talcum powder also failed to solve the problem that the cover could not be automatically conveyed on the bookbinding machine. Finally came up with the trick: put it into a 40-degree freezer frozen, frozen 2h, become straight, there is a certain degree of stiffness after the plastic bookbinding package, only barely complete production tasks.
6. Print graphic discoloration
Mainly in the large area of ​​the spot color prints when the film, such as the printing of gold, silver ink film after the water will be an unexpected change in color. The reason for this is that some chemical substances in glue and water react with the chemical reaction of gold ink (containing more copper powder) or silver ink (containing more aluminum powder). At this time can only change the coating process, using oil or hot-press pre-film process instead.
Of course, water-based film products also have their own uniqueness. For the saddle-stitched cover, especially the thinner water cover for the cover does not curl up. At the same time, it also has the following advantages: low production applicability, suitable for large-scale assembly line production, low investment cost, low comprehensive cost, and economic benefits. What is most commendable is that it is not easy to pollute the environment and is an environmentally friendly product. It is the development direction of the film and will occupy a place in a particular product. If we can solve the defects of the current water-based glue, its application prospects are broad.