The film coating process of paper bags is important for making the paper bag. The film coating technology of paper bags is a process of making paper bags, also known as “post-press over-plastic”, “post-press laminating”,  “post-press coating”.  That is, after the paper is printed, the surface of the printed paper is covered with a transparent plastic film by hot pressing with a laminating machine. The thickness of this film is about 0.012-0.02mm. At present, the matt film lamination and gloss film lamination are made into the coating process through environmentally friendly water-based solvents, which improve the environmental protection of the coating process.

Kraft paper and specialty paper do not need film coating, Kraft paper bag ink absorption capacity is strong, and the surface is rough, paper toughness, so there is no need to use film coating to protect the printed content on the kraft paper bag. Moreover, the film coating process also requires the paper surface to be smooth, without blistering and aesthetic defects, so that the film can stick closely with the paper. Ivory paper, art paper, black cardboard, and grey cardboard are printed and need to be coated with film to protect the printed content of the paper bag, and then made into a paper bag.

After the paper is coated with the film, the color and brightness will change a little.

After the paper is coated with gloss film, the color of the printed pattern on the paper bag will be brighter than before.

After the paper is covered with matt film, the color of the printed pattern on the paper bag will be darker than that before, making the paper bag and brand look elegant, solemn, and calm. Suitable for high-end products and brands.

If the designer is told in advance by the salesman that the paper bag needs to be covered with matt film, he will appropriately increase the color purity and brightness of the design drawing when designing the paper bag pattern file.

What are the effects of film lamination on paper bags?

1. Moistureproof, prevent paper bags from wear, oxidation and erosion.

A film is coated on the printing surface of the paper bag to isolate the printing surface from the air, protect the paper from wear and tear, reduce the oxidation and erosion of the printing surface by air, and prolong the duration of the printing color on the paper bag. the printing pattern on the paper bag can be maintained for longer.

2.Easy to clean:

Cover the paper bag with film to facilitate wiping and cleaning the dirt on the surface of the paper bag.

3.Increase the toughness, tensile force and load-bearing capacity of paper bags:

Because the film has the advantage of stretching, covering the paper bag with film can improve the tensile force and toughness of the paper bag, so that the paper bag is not easy to be damaged in use, and the load-bearing capacity of the paper bag is increased.

To sum up, covering the paper bag with film can increase the concentration of the printing color of the paper bag, make the paper bag waterproof, anti-aging, anti-tearing, anti-piercing, and improve the fastness, strength, and bearing capacity of the paper bag. Covering the paper bag with matt film can also increase the visual softness of the paper bag, making the paper bag look high-grade and comfortable.

The paper coating technology was introduced into China in the 1980s. Because the film coating can protect the paper bag from tearing, it is very popular with the paper bag manufacturers.

4. Because the film can be waterproof, the peritoneum of the paper bag can enhance the waterproof effect of the paper bag and increase the service life of the paper bag.

The materials used to cover paper bags are mainly divided into two kinds, one is gloss film, the other is matt film.

The difference between gloss film and matt film lies in the treatment of light.

The matt film is treated with matte scrub, and the reflection of the film to the optical fiber is not high so that the surface of the printed paper bag is not too bright. Cover the surface of the printed paper bag with matt film, which can make the surface of the paper bag soft and three-dimensional. If you look at the paper bag from any angle, you can see the printing effect on the paper bag, which makes people feel a high-grade atmosphere. You can find that almost many major brands of paper bags, such as LV, Gucci, etc., are covered with matt film.

The gloss film is not frosted and is highly reflective to light, and the printed content on the paper bag can be seen only at a non-reflective angle. Although the surface of the paper bag covered with gloss film is brighter, the printed surface has high reflectivity.

The glossy paper bag does not look very high-end and is generally used on the more common advertising paper bag.

you need to pay attention to when covering a paper bag?

1. To cover the paper bag, you need to choose the right adhesive.

Suitable glue can make the coating effect better and make the printing pattern of the paper bag look more vivid and colorful.

2. Control the running speed of the laminating machine.

3. According to the running speed of the laminating machine, control the amount of adhesive used between the paper bag and the film.

4. If too much powder is sprayed on the paper during printing, the powder removal should be carried out before the film is covered.

5. Before you cover the film, you need to make sure that the printed paper is dry.

6. After the film lamination, you need to put the coated paper for a period of time before doing the follow-up process: such as cutting, cutting,gold hot stamping, silver hot stamping,embossing&debossing, and so on.

7. In the process of film lamination, the staff need to observe the degree of adhesion of the film on the paper at all times to ensure a good coating effect.

The placement time is adjusted according to the air humidity at that time. If it is cloudy and rainy and the air humidity is very high, it can be placed for about 1-2 days. If the air is dry and the weather is sunny at that time, you can leave it for half a day.

A good control of the above 7 points can effectively reduce the paper stripping, blistering, pitting, defects, etc., quality problems, and reduce the loss caused by poor film mulching.

This kind of film lamination process has a wide range of uses, not only in paper bags, but also in books, albums, wall calendars, maps and many other aspects.

Comparison of film lamination and UV process:

The cost of UV glazing process is lower than that of film lamination, and it is generally used to UV the local pattern or position of the paper bag. Local UV glazing process can improve the grade of paper bags.

Most of the time, customers choose to first cover the paper bag with film, and then do the UV glazing process on the paper bag. Before the UV process, the solvent-based film must be used in the film lamination.

UV is a glazing effect on printed paper bags, mainly decorating and protecting the printed patterns on the paper bags. The use frequency of UV is lower than that of film lamination, and although UV technology is often used in paper bags, it is not as effective as film lamination in terms of protection, folding resistance and wear resistance. UV glazing needs to be put into printing equipment and UV curing equipment, UV varnish in the coating process, will volatilize odor, this special gas will harm the health of the operator. These limitations of UV glazing and the treatment of the process above determine that the UV process can not completely replace the film lamination.

There are two kinds of film coating processes for paper bags:

1. Dry coating method:

The dry coating method is to apply an adhesive on the plastic film, evaporate through the drying channel of the laminating machine, remove the solvent in the adhesive and dry it, and use this hot pressing process to cover the film on the printed paper. This coating method is the most widely used.

2. Wet coating method:

The wet coating method is to coat the surface of the plastic film with a layer of adhesive, which is bonded with the printed paper through the pressing roller to form a coating.

The operation of the two kinds of the film coating process is very simple, the amount of adhesive is relatively small, the organic solvent used to cover the film will not damage the environment, the film lamination effect is good, and it is eco-friendly.

The above is the introduction of paper bag film lamination. My next blog will introduce the gold hot stamping, silver hot stamping, Embossing&Debossing, and so on. I hope you can come and read my article.

We are a paper bag manufacturing factory in China, we can customize paper bags of various shapes and sizes for you. You can contact us for inquiry (sale01@wepaperbag.com) and we will quote you a satisfactory price as soon as possible.