Curling After Lamination? Poor Lamination And Impurities? Have You Noticed Any Of These Problems?

Lamination is one of the more common surface finishing processes for label printing, helping to improve the label's wear resistance, water resistance, dirt resistance, chemical corrosion resistance and other properties.

Although the lamination can effectively improve the label grade, but in the lamination process, often encounter some lamination bad problems, such as wrinkles, bubbles, curling, etc., affecting product quality, resulting in adverse consequences.

In this article, we share with you label printing lamination is not firm, lamination impurities, lamination after the curl problem solution.

Poor lamination

If you encounter a situation where the laminated film comes off from the edges after die-cutting, or even the printed ink sticks back down. Causes of this situation are:

1. Problems with the quality of the film itself

If there are quality problems with the film itself, such as the glue not sticking, it will not press well with the printed material. This situation results in a poorly laminated film, which tends to peel off regardless of the material or the printed graphics. We can do a simple test in production, that is, after the lamination with a knife to cover the good film place cut, with hands gently rub a few times to see if the film will fall off, if not fall off, generally will not have too big a problem.

2. Printing inks not strong

Printing with inks that are not completely dry, or that do not dry firmly, can also easily lead to the laminate coming off. This situation mainly occurs in large areas of field printing, and bleeding die-cutting products above. Because bleed die-cutting requires cutting into the ink, if the ink is not strong enough, it can easily lead to the laminate peeling off. To avoid this, it is advisable to test the ink fastness after printing with tape, usually 3M-610 tape. If the ink can pass the tape test, then the lamination and die-cutting will basically not come off.

3. Surface tension issues on printed materials

Some film-like self-adhesive material surface tension is too low, resulting in printing after the ink adhesion is not solid, in the printing of large areas of field pattern lamination after bleeding die-cutting prone to lamination off phenomenon. In this case, before printing must be used up to sound pen to test the surface tension of the material, in general, the surface tension of the material should reach a minimum of 38 up to sound, the best can reach 42 up to sound. If the surface tension of the material is too low, it is necessary to consider continuous corona, or priming to increase the surface tension of the material before printing. Generally speaking, the surface tension of materials treated in these two ways will increase to varying degrees, and the ink will adhere more firmly after printing, and the laminate will be less likely to peel off afterwards. Therefore, it is important to remember that printing can only be carried out after the surface tension of the material has reached a qualified value.

Laminate impurities

Laminate impurities, which refer to dirt, foreign matter, dust etc. that appear during the lamination process, affect the quality of the product. The main causes of laminating impurities are:

1. Dirty material surfaces

Dirt, dust, paper lint and confetti on the surface of self-adhesive materials can easily lead to laminating impurities. Therefore, the surface of the material needs to be dusted during the production process. This is usually achieved by dusting cloths or dusting rollers, where the dusting rollers consist of polyurethane rollers with their own weak adhesion to stick the dust off the surface of the material in order to reduce the disturbance caused by dust during the printing and laminating process. It is worth noting that in recent years presses have been produced with dust removal rollers as standard and can be used without much thought.

In addition, some paper-based self-adhesive material itself off powder is also very easy to lead to lamination impurities, paper off powder is often because the material itself is not strong enough on the surface, with dust removal roller is also very difficult to completely remove. If you encounter this kind of surface strength of the lower material, in the case of not being able to replace the material in time, you can consider using the bottom coating way to solve, that is, first in the material surface full version of printing a layer of bottom coating ink or remove the light agent, and then print other colours, which can greatly reduce the generation of paper hair, this way not only can improve the quality of printing, but also greatly improve the quality of the laminate after the sequence.

2. Printing float dust

The environment of the print shop also has a greater impact on the quality of the laminate, and if there is too much dust in the shop, it will easily lead to impurities in the laminate. In principle, you need to change your shoes when entering the print shop and mop the floor at least twice a day to ensure a clean floor and thus reduce the dust in the shop.

3. Printing Static

The printing of film-based self-adhesive materials generates a lot of static electricity, which attracts dust from the workshop environment and can lead to impurities when laminating the film. Therefore, in addition to keeping the workshop clean, it is also necessary to control the humidity in the workshop. In principle, the relative humidity of the workshop should be kept at around 50% to 60%. It is recommended that companies with conditions can buy industrial humidifiers to control the humidity in the workshop, and companies without conditions can solve the problem by mopping the floor.

Curling after laminating

Curling after lamination is also a common lamination problem. This problem is characterised by its concealment and is not easily detected, and when die-cutting the curl is often found too late, this problem requires attention. The causes of post-lamination label curling are:

1. Laminate tension

Usually, there are two main types of label curl after lamination: upward curl and downward curl. If the label is curled upwards, the tension in the film is too high; if the label is curled downwards, the tension in the film is too low. During the production process, the tension of the film is constantly changing. Generally speaking, the tension of the film is relatively low when the roll is first opened, and the more it reaches the centre of the roll, the greater the tension of the film. Therefore, the tension of the film needs to be adjusted during the laminating process, with the tension of the film being adjusted upwards when the roll is first opened and downwards when the roll is almost finished.

Here, teach you a way to check whether the tension of the lamination is appropriate: after lamination with a knife to laminate the material according to the size of the finished label cut a few sheets down, and then the label from the backing paper off to see if the label is flat, if the label is flat, it means that the tension of the film is appropriate, if the label is curled upward or downward, it means that the tension of the film is not appropriate, you need to adjust the tension of the film according to the specific situation.

2. Equipment issues

The laminating device on some older printing equipment is of a simpler design and the laminating tension is not adjustable, or has a limited range of adjustment. This equipment can cause problems for the operator, as there is not enough room to adjust the equipment and once the laminating tension is not suitable, it is not possible to make effective adjustments, which can easily lead to laminating curl problems. At present, many new printing machines are available, and their laminating tension is generally adjusted with servo motors, which can solve the problem very well. This shows that the choice of laminating equipment is also important.