Water-based film processing technology

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. It is not suitable for large area (especially large field). The textual product is covered with a water-based film. The glue contains a certain amount of moisture. When used for laminating large area (especially large field) graphic products, it will be shown in the figure. The surface of the text presents a large area of ​​snowflake-like spots, which affects 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 sizing for offset paper. I have used mass-produced water-based coating glue in different regions and manufacturers. Compared with oily, especially two-component glue-laminated films, I used to overlay films on offset paper products. Waterborne film-coated products can easily cause paper-plastic detachment. Sometimes, it can be easily torn off. Films and prints can be completely separated, which can easily cause quality accidents.

3. The products with double-faced film are used with caution. Some products must be coated on both sides due to customer requirements. For example, if water is used in the laminating process, the water content in the glue is higher, and the water content of the printed film is harder to evaporate. , resulting in India Crystal soft, not meet the requirements of customers, bringing unexpected quality accidents.

4. It is not easy to carry out embossing after laminating. When embossing the product on the water-based film, it will produce white spots and bow wrinkles on the contact surface, and the paste will be weak. When it is severe, it will blistering, and it will be prominent on 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 The product of the water-based coating film must be laid flat after 24-48 hours after being divided by a large sheet. 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. Discoloration of printed graphics is mainly reflected in the coating of large-area spot-color prints. For example, the color of ink and silver ink products will undergo unexpected changes after water-based lamination. 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.