Transparent Ink: Creating a New World for Soft Packing (2)

Reasonable choice of transparent ink

About how to choose transparent ink. We can consider the following three aspects:

â–  Printing should use inks that are compatible with the printing materials. For example, when the printing table is printed with aluminum, the transparent ink must be printed. If it is printed BOPP and composite aluminum, you should use composite ink (transparent). Therefore, it can be said that the type of printing materials determines the type of ink used, even if the same type of film material, often due to different varieties and grades vary, so it should not be mistaken.

â–  The correct choice should be based on the sample provided by the customer. The choice of clear ink includes hue and color. When it comes to the deployment of spot color transparent ink, it is necessary to consult with the production supplier. The difficulty of special color matching for transparent ink is obviously higher than that of opaque ink.

â–  The selection should also be made according to the actual situation. Parameters such as high temperature resistance, light resistance, permeation resistance and so on must be included in the consideration of the selection.

Transparent ink printing and failure phenomenon

â–  It is necessary to stir the clear ink before it is printed. If it is in winter, the weather is relatively cold, because the viscosity of the table printing transparent ink is low, it is not suitable to add too much diluent and viscosity. Generally, the 3# cup is controlled in 18-22 seconds, and then the angle of the doctor blade is adjusted according to the depth of the printing plate. The pressure of the impression cylinder and the distance between the squeegee and the embossing point. If the solvent ratio is misaligned, improper viscosity control, or process failures are very likely to cause many failures, so every link can not be sloppy.

â–  It is easy to produce "pitting" when printing transparent ink. After the printed product is coated with aluminum film, the flash effect comes out, but if you look closely, you will find that the surface of the product is pinhole-shaped, as if it is not printed. There are several factors in this factor:

1 The surface of the printing rubber roller is not sufficiently fine or dust and foreign matter and the printing on the top is caused by the top;
2 The plasticizers, lubricants, etc. contained in the film float to the surface to hinder the normal transfer and lubrication of the ink;
3 The viscosity of the ink is too high, the drying is too fast, or the gap is caused by the adhesive, and the wettability is poorly adapted;
4 increase the pressure of the printing rubber roller, generally about 4kg. If there is regularity in the pitting, you should carefully check whether the plate and the rubber roller are defective, re-plate or replace the roller.

â–  Adhesion after printing transparent ink In the high-temperature, high-humility Meiyu season, after the plastic film is gravure-printed, adhesion phenomenon occurs between the winding positions, the transparent ink blocks fall, and even the transparent ink cannot be separated from the lower plastic film. As for causing waste products.

Most of the adhesion factors are due to the stickiness of the ink, the humidity is too high, and the pressure is too high. The specific factors are as follows:

1. Intrinsic factors: The ink itself is poor in heat resistance. When the paint is dry, we cannot see it with the naked eye. Since the residual solvent is difficult to evaporate after the printed matter is rolled up, the resin in the ink cannot be dried and solidified, causing severe blocking of the finished product. The increase of the residual solvent not only affects its firmness, but also is extremely unfavorable to the food and produces odor. In addition, the auxiliaries in the printed material can also cause the ink to become sticky.

2, external factors: due to improper control caused by adhesions. At room temperature, the finished product with no quality problems in the operation and use of the printed product will soften when exposed to high temperatures. Adhesion builds up. Therefore, it is required that both the operating temperature and the use temperature of the printed matter should not exceed 40°C to 50°C. In addition, too tight winding, winding tension will cause adhesion, the solution is to control the printing drying temperature and tension relaxation, winding should not be too tight.

3, other reasons: ink and substrate sticky, such as the ink and the substrate does not have a good bond. After rewinding, it is easy to transfer and produce adhesion. The solution is to select the ink correctly and control the quality of the ink to make it suitable for the substrate. In addition, treating the surface of the substrate to increase its affinity for the ink is also a method of reducing the occurrence of blocking of the ink. General BOPP surface tension ≥ 38 dyne can be.

The reason why the gloss is not high after brushing transparent aluminum plating composites is as follows:

The ink itself has poor transparency;
The solvent is too fast when printing, the viscosity is too low; the aluminum plating layer is poor in uniformity, resulting in poor anti-gloss:
The squeegee angle is too large, and the plate is shallow. The solution is: a. Replace the ink with good transparency; b. Use slow-drying solvents to increase viscosity; c. Replacement of composite aluminum plating requires that the aluminized layer be uniform without pinholes; d adjust the squeegee blade, generally the angle is controlled at 35 degrees.

When printing transparent ink, you must start from all aspects to get the best results, and you should select and print according to the actual situation.

Source: Export Goods Packaging