Water-based film products have their own unique features. For saddle stitched covers, especially thinner covers, the water-based film will not curl when damp. At the same time, it also has the following advantages: low production adaptability requirements, suitable for mass production line production; low investment cost, low comprehensive cost and other advantages, economical. The most commendable is that it is not easy to pollute the environment, it is an environmentally friendly product, which is the development direction of the film, and it will have a place in certain products. If the defects of the current water-based glue can be solved, its application prospect is broad. However, due to its inherent characteristics, there are inherent deficiencies, so it should be used with caution in some products.
1. Not suitable for large area (especially large field) graphic product overlay
The glue of the water-based film contains a certain amount of moisture. When it is used for laminating large-area (especially large-field) graphic products, it will show a large area of ​​snowflake-like spots on the surface of the graphic, which affects the appearance quality of the product . Although increasing the amount of sizing is not much improvement, it can only be replaced by oily or hot-pressed pre-coating film coating process.
2. Not easy to use for sizing of offset paper
The author has used water-based film glue from different regions and manufacturers for batch trial production. After comparing with oily, especially two-component glue film, the film is coated on offset paper products. Water-based film products are easy to cause paper plastic When it is detached, sometimes it is torn lightly, and the film and the printed product can be completely separated, which is easy to cause quality accidents.
3. Products with double-sided coating are used with caution
Some products require double-sided lamination due to customer requirements, such as water-based lamination process, because the water content of the glue is more, the moisture of the printed product is difficult to evaporate quickly after lamination, resulting in soft printed crystals, which cannot be achieved The customer's request brings unexpected quality accidents.
4. It is not easy to process bumps after coating
When the concave-convex process of the water-based coated product is processed, white spots and bow wrinkles will occur on the contact surface, the adhesion is not firm, and it will foam in severe cases, which is more prominent on the coated paper. We can pay attention to the cover of some glue binding books. The rubber line on the cover side after water-based coating is not very straight, and there are uneven impression marks, which seriously affect the appearance of the product.
5. Subsequent processing waits and preparation time is too long
The water-based film-covered products must be laid flat for 24-48h after being divided by large sheets. Sometimes it can only flow into the next process after being baked at 40-500 degrees. The main purpose is to stabilize the adhesive strength and stiffness of the coated product after evaporating the moisture of the glue. Sometimes some special auxiliary means are needed to meet the requirements of post-press processing.
In order to save costs for a certain product, 105gm2 double-sided coated paper is used for the cover. After the water-based single-sided coating, the cover is too soft and it is easy to cause static electricity. The method of baking for 72h and lightly coating talc powder also failed to solve the problem that the cover cannot be automatically transported on the disc binder. Finally came up with a trick: put it in a -40 degree freezer for quick freezing. After freezing for 2 hours, it will become straight, and after a certain degree of stiffness, it will be bound by a binding machine to complete the production task.
6. Printing graphics and text change color
Mainly manifested in the coating of large-area spot color prints, such as gold and silver ink products after water-based coating, the color will change unexpectedly. The reason is that this is due to a chemical reaction between some chemicals in the glue and water and gold ink (more copper powder) or silver ink (more aluminum powder). At this time, only the coating process can be changed, and the oily or hot-press pre-coating process is used instead.
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