Laminating is to compound the special film
with the thickness of 15-20ljm with the printed matter, so as to improve the
surface gloss and strength of the printed matter and enhance the visual
aesthetic feeling. There are three kinds of film mulching: oil-based,
water-based and hot-pressing precoating. Water based film mulching is the most
popular way in China at present. However, due to its inherent defects, it
should be used with caution in some products like the printing books in China.
1. Not suitable for large area (especially
large field) graphic products
The water-based laminating glue contains a
certain amount of moisture. When applied to large-scale (especially
large-scale) graphic products, it will present large-area snowflake like spots
on the surface of graphics and texts, thus affecting the appearance quality of
the products. Although increasing the amount of sizing is not much, it can only
be replaced by oiliness or hot pressing pre coating process.
2. It is not easy to use in the sizing of
offset paper
The author has used the water-based
laminating glue from different regions and manufacturers for batch trial
production. Compared with oil-based, especially two-component glue, laminating
on offset paper products, water-based laminating products are easy to cause
paper and plastic separation, and sometimes gently tear, the film and printing
can be completely separated, which is easy to cause quality accidents when printing books in China.
3. Being careful to use the products
covered with double-sided film
Some products have to be coated on both
sides due to customers' requirements. For example, water-based lamination
process is used for production. Due to the large amount of water content in the
glue, the water content of the printed matter is difficult to volatilize
quickly after the film covering, resulting in the softening of the printing
crystal, which fails to meet the requirements of the customers, and brings
unexpected quality accidents of printing books in China.
4. It is not easy to carry out concave
convex processing after laminating
When the water-based coated products are
pressed and concave convex, the contact surface will produce white spots, bow
wrinkles, and the paste is not firm, and it will blister in serious cases,
which is more prominent on the coated paper. We can pay attention to some
binding book covers. After water-based film covering, the side glue bar line of
the cover is not very straight, there are uneven indentation marks, which
seriously affect the product appearance.
5. The waiting time and preparation time
for subsequent processing are too long The product should be laid for 48
hours after being stretched. Sometimes it can be baked at 40-500 degrees to the
next working procedure. The main purpose is to volatilize the water of the
glue, stabilize the adhesive strength and the stiffness of the coated products.
Sometimes some special auxiliary means are needed to meet the requirements of
post press processing.
6. Color change of printing text when printing books in China
It is mainly reflected in the large area of
spot color printing, such as printing gold, silver ink products after water-based
coating, the color will occur unexpected changes. The reason is that some
chemicals and water in the glue react with gold ink (containing more copper
powder) or silver ink (containing more aluminum powder). At this time, we can
only change the laminating process, using oil or hot pressing pre coating
process instead.
Of course, water-based film products also
have their own unique. For the cover of horseback riding, especially the
thinner cover, the water-based film will not be affected by moisture and curl.
At the same time, it also has the following advantages: low production
suitability requirements, suitable for mass production line production; low
investment cost, low comprehensive cost, etc. The most praiseworthy is that it
is not easy to pollute the environment, belongs to the environmental protection
product, is the development direction of the film covering, will occupy a place
in the specific product. If the defects of water-based glue can be solved, its
application prospect will be broader.
