Processing of ink drop during label printing of non dry glue

Many non dry glue label manufacturers will encounter the same problem in printing. In the process of label printing of film materials, it is very easy to print ink in surface layer, which greatly affects the quality of printed materials and even delay the date of delivery. This article tries to sum up and enumerate the common causes and improvement methods of ink drop from the experience of daily printing for the people in the industry to find out the best solution.

Problem one: coating defects

The conventional thin film is divided into two kinds with coating and no coating, and the reason of the ink drop caused by the defect of the film coating is also divided into two cases. For the film material with the coating, the adhesion of the coating is poor if the surface coating firmness is poor, and the uncoated film material is not bound to the surface with the ink. The ink is caused by the ink. 

The ink drop caused by the coating defects can be solved by the following ways: using the surface layer Polish printing treatment, protecting the ink surface, and preventing the ink drop. The surface layer adopts corona reprocessing, the corona value of the material surface should not be less than 38mm/m, and the cause value lower than 36mm/m will directly affect the printing ink. The strength of the surface layer, or with a strong adhesive force of ink (about 3%), can also improve the ink power of the film surface layer; some subsurface synthetic paper materials are not suitable for testing with 3M tape because the surface coating has a certain paper coating.

Question two: Tension

For the film materials on the printed surface to be corona treated, to achieve a good ink wetting, the value usually needs more than 38mm/m, and the ink drop problem is easy to appear below 36mm/m; at the same time, the value of the material will fade away with time, and the printing ink problem appears. The essence of this problem is the problem of tension.

In this case, there are several solutions: using a satellite wheel with a on-line corona function to improve the surface energy of the film like material by using a combined corona process to improve the surface energy of the film. It is necessary to use corona to deal with it, but the size of the value does not fully represent the adhesion between the ink and the surface material. The receding period of the general value is 3 months -6 months, so it is suggested to minimize the long-term storage of the stock.

Finally, it is recommended that the ink with greater adhesion be recommended for ink suppliers.

Problem three: ink drying and tension

During printing, ink drying and tension may also cause ink drop. It is divided into: the printing ink is too thick to dry; the energy of the UV lamp is not enough, the light pipe is aging, the lamp tube is aging, the drying of the UV lamp is not enough, the ink layer is not dry, the ink is too dry, the material is deformed and the ink layer falls off.

The ink drop problem can be solved in the following three ways:

First, the use of deep ink and thin printing, which is commonly known as reducing the amount of ink, such as special color sub ink, can match the depth, in the formal printing of small amount of ink to achieve a sample effect, at the same time, increase the output power of the UV lamp, reduce the speed of printing, increase the exposure time of the UV lamp, to achieve the drying effect. This scheme is suitable for old intermittent or satellite rotating machines and old UV lamp solutions.

Second, check whether the UV tube is aging and clean the reflector. Usually, the life of the domestic UV tube is about 500-1000 hours, and the life of the imported lamp is about 1000-2500 hours. It is suggested that the printing factory should carry out UV lamp cleaning work every half a year to ensure normal use.

Third, reduce the output power of UV lamp, the specific operation for the general printing works, most of the color sequence before the color order or small words, the light is limited, can open the offset UV light, dry, can not be upscale excessive radiation, because the film material absorption heat energy is limited, excessive irradiation will cause film materials curl change The effect of deformation brittleness, ink adhesion and so on can be followed by the principle of low grade and high grade UV lamps.

Problem four: the matching of ink and material

Finally, the matching degree of ink and material will also cause ink to a certain extent. For example, the use of ink molecular tension is too large to form a uniform ink layer on the surface of the material on the substrate, or the use of the type of ink over the shelf life or the inferior domestic brand ink will cause printing ink.

A summary of the influence factors of ink drop

Through the above analysis, we can conclude eight reasons for ink drop.

1, coated film materials, poor surface coating fastness;

2, uncoated thin film materials, after printing and ink bonding fastness is not good;

3. The value of DDD is low. For film materials with corona treatment on the printing surface, good ink wetting is required, and the 38mm/m value is usually more than the value.

4, the value of the DAS is subsided, the printed material is corona treated film material, the value of which may gradually dissipate with time, and the extinction period is 3-6 months.

5, the ink layer is too thick and the power of UV lamp is insufficient.

6, too much ink tension can not form a uniform solidified ink layer on the surface of the printed material.

7. Use overdue ink or inferior domestic ink;

8, the ink is overly irradiated and overdrying.

In the case of the above conditions, it can be switched to ink that matches the printed material, such as the special ink of the film and the light resistant and light resistant ink (which can be consulted with the ink manufacturer). Some low-grade products; printing large area of the field and full version of dot net line pattern, recommend the use of good brand, high adhesion ink.