The use of varnish on self-adhesive labels is beyond your imagination

Printing varnish on the surface of the printed self-adhesive material is a common post-press finishing process in the production of self-adhesive labels. According to incomplete statistics, about 50% of wet glue and self-adhesive labels currently use the glazing process.

The varnish printed on the surface of the self-adhesive label can not only protect the printed ink surface and increase the brightness of the label surface, but also enhance the waterproof performance of the label, so as to have a good moisture-proof effect. In addition, some varnishes with special effects, such as printable varnishes, matte varnishes and scented varnishes, can also make labels have more functional properties. In this article, the author will share with you some common types and application fields of self-adhesive label varnishes, hoping to give readers some inspiration.

Varnish types and application fields
At present, there are various types of varnishes on the market. If they are classified from the drying method, they can be divided into two types: water-based varnishes and UV varnishes. Among them, water-based varnishes are mostly hot air drying, while UV varnishes are mainly UV light curing drying; according to the use, it can be divided into general varnish, high gloss varnish, matte varnish, high temperature varnish, ultrasonic sealing varnish, anti-blocking varnish, printable varnish, high friction resistance Varnish, waterproof varnish, anti-skid varnish, reverse varnish, scented varnish, anti-static varnish, touch varnish and food packaging varnish, etc. Below, the author mainly introduces several commonly used varnish application effects from the perspective of use.

01 Universal Varnish
The self-adhesive label is composed of a surface material, glue and a backing paper, and the surface material and backing paper of the label will show different stretch rates when absorbing or losing moisture. After water loss, curling will occur due to the difference in the expansion and contraction length of the surface material and the bottom paper. The main function of general varnish is to increase the gloss and brightness of the printed matter, and it also has a certain waterproof effect. Printing varnish on the surface of the self-adhesive label can prevent the label from curling due to the influence of environmental humidity.
For example, after some paper self-adhesive labels are labelled in an environment with high air humidity, the label will stretch after absorbing moisture in the air, causing problems such as bulging and wrinkling of the label after labeling. Varnish has a certain barrier effect on moisture in the air, and is less affected by air humidity after labeling, so these problems are not easy to occur.
In daily life, we often see that the surface of some non-staple food seasoning or lubricating oil drum labels is very smooth. These labels are often printed with general-purpose varnish. The purpose is: on the one hand, to make the surface of the label smoother and brighter, and on the other hand The label has a certain waterproof effect to ensure that the label will not expand and wrinkle after labeling.

02 Matte oil
The biggest difference between ordinary matte oil and bright oil is: after matte oil is applied, the surface of the printed matter will have a matte frosted effect. This effect is especially suitable for some special design effects, such as some wine and cosmetic labels. When designing patterns, a matte effect is designed to highlight the grade of the product, and this effect is often obtained by applying matte oil during the printing process. accomplish. In addition, matte oil also has a certain waterproof effect.

03 Printable Varnish
Because ordinary varnish contains silicone oil additives, the surface is relatively smooth, and the printed information is easy to fall off, so it is not suitable for printing on the surface of such varnish. However, in the actual application process, many labels need to print information on the glossy surface, such as food labels, drug labels, etc., the production date, batch number and other information need to be printed on the glossy surface. After the printable varnish is printed on the surface of the material, variable information can be printed on the surface, because the printable varnish can form a high surface energy varnish layer suitable for printing on the surface of the material, so that the printed information can be firmly attached. on the label surface.

04 Anti-rubbing varnish
A rub-resistant varnish is a varnish that makes the surface of the print very smooth. Some label products require anti-friction performance. This is because the labelled bottle body will rub against each other due to vibration during packaging and transportation. If the anti-friction performance of the label is not good, it is easy to cause the printed pattern on the label to be worn out and worn off. For example, some cosmetics or alcoholic products need to be transported long-distance often to reach the store. During the long-distance transport, the bottles in the box rub against each other, which can easily damage the pattern on the surface of the label.
In this case, rub-resistant varnish needs to be used. This varnish contains a lot of silicon additives, so a relatively smooth varnish layer can be formed after printing. Since the surface of the label is protected by a very smooth varnish layer, the abrasion resistance of the label is greatly improved.

05 Reverse Varnish
If you want to make a granular effect on the surface of the printed matter, such as a raindrop-like effect, or a matte surface effect with relatively coarse particles, you can use reverse varnish to achieve it. Reverse varnish is a varnish that has been applied on a large scale in recent years. This varnish consists of two types of varnishes: top coat and base coat.
During use, two kinds of varnishes are printed on the surface of the label at the same time, and a chemical reaction will occur, forming a granular varnish layer on the surface of the printed matter, and the size and thickness of the particles can be adjusted as needed. It can be seen that the reverse varnish is a very special varnish that does not contain silicon additives at all, and the effect of the varnish is only determined by its own chemical properties. Since reverse varnish can play a very good decorative effect, it has been very popular with end users in recent years.

06 Scented Varnish
Some cosmetics or high-end foods need to emit fragrance on the label, and this fragrance often needs to be similar to the fragrance of the product itself. Scented varnishes can then be used to achieve this effect. The principle of scented varnish is to add microcapsules containing fragrance into the varnish. After printing, the microcapsules will remain on the surface of the label. Once squeezed or rubbed, the microcapsules will burst to release the fragrance.
There are many types of scented varnishes, such as varnishes with various fruit flavors and flower flavors, which are often used in food and cosmetic labels. In recent years, some children's books have also begun to use scented varnishes. For example, lavender flowers are printed on the pictures of children's books. If lavender-flavored scented varnishes are printed, children will release scents through friction when reading books. , this design is very popular with children.

07 In addition to static varnish
When printing some film labels, strong static electricity may be generated, which will cause a lot of trouble to the printing and subsequent die-cutting processes. In order to eliminate static electricity problems on the finished label, you can choose static removing varnish. The static-removing varnish contains static-removing additives, which can effectively eliminate the static electricity on the material surface after printing on the material surface, so as to achieve the ideal static-removing effect.

08 Touch Sensitive Oil

The so-called tactile varnish means that the varnish will automatically bulge after being printed on the surface of the material, and it has an obvious tactile feeling when touched by human hands. When it is necessary to achieve an obvious concave-convex effect on the surface of the label, touch-sensitive oil can be used.
There are currently two methods of touch-sensitive oil: screen printing and flexographic printing. The screen printing ink layer is thicker and the touch is more obvious. Touch varnish is mainly used to make some specially designed labels, such as some labels printed with Braille, it is more suitable to use this varnish.

09 Food grade varnish
Traditional varnishes cannot be in direct contact with food, but can only be in indirect contact with food, but in recent years, there have been more and more applications of food-grade varnishes. The main component of food-grade varnish is ethyl ester wax, which meets the current domestic and international requirements for food-grade packaging, so that it can be directly contacted with food. In the past, this type of packaging products mainly used PE coating, but now food-grade varnish can be used instead of PE coating.