Transparent ink in the use of packaging and printing methods (2)

Transparent ink selection and application
The selection and application of transparent ink should be based on the requirements of different substrates and customer requirements. To sum up, the following three aspects should be taken into consideration and a transparent ink should be reasonably selected.

1 According to the printing materials used to adapt to the choice of ink: If the printing table printed aluminum film must be selected table printing transparent ink: printing BOPP film and composite aluminum plating should use printed transparent (composite) ink. Therefore, it can be said that the type of printing materials determines the type of ink used, even if it is the same type of film material, it often varies depending on the type and grade. Also note that printing with clear ink generally does not use a white bottom underneath the color case because the white will have a delustering effect that will greatly reduce its effectiveness and value. Relatively speaking, the transparent ink printing color is thinner than that of the white ink pad, O.Olmm.

2. According to the sample provided by the customer choose to adapt to the transparent ink: the choice of transparent ink includes hue and color. To deploy spot color transparent ink, you must consult the production supplier because the deployment of transparent ink spot color is different from the general spot color ink, The difficulty is significantly higher than the opacity ink tone matching.

3. Select the appropriate transparent ink according to the actual situation and use of the packaging: If the packaging prints are resistant to high temperature, light, permeation resistance and other parameters, these must be included in the consideration of the selection. In addition, transparent ink printing requires high brightness and vivid colors without aluminum film or aluminum foil, aluminum foil, etc. Since the transparency of the transparent ink is extremely high and the aluminized film is composited or directly printed on the above materials, it will change. In order to reveal the gloss and color of the metal, yellow is yellow, green is greener, and red is redder.

Nowadays, transparent ink has developed a variety of transparent golden, transparent yellow, transparent light blue. The transparent golden compound is even more glittering when it is laminated on aluminized film: transparent golden Because transparency is extremely high, it is often used in self-aligning gold, and it can also be lined with gold powder. According to the customer's request, the golden ink which is prepared with the ratio of 1:3:2 of gold powder, gold transfer oil, and transparent golden ink for self-made golden ink can be selected not only for gold but also greatly enhances its adhesion. . At present, transparent ink is mainly used for printing colorful flowers, color bars, ribbons, and other gift gold paper. These wrapping papers are printed in transparent ink (red, yellow, green, blue, etc.) or printed with an aluminum-plated film. They are single-stick films. After the transparent ink is printed, the inner layer is made of aluminized film to form a flexible packaging bag or a small inner bag made of aluminized film is made into a conjunctiva. This is a film that belongs to more than two layers and has been widely used in the food industry. There are also printed papers, carton boxes, New Year pictures and other high-end packaging printed products made of transparent ink and printed on aluminum after being re-applied to paper. The printed products have the advantages of waterproof and moisture-proof. The use of anti-counterfeit materials printed and then printed with transparent ink and then re-launched laser holographic film can not only increase the security effect, while making the appearance of colorful, shining. In order to achieve the best results, the transparent ink may not be fully used at the time of design, and only a partial transparent ink printing may be used to obtain better results. Transparent ink is a dry special ink, because of its different formulations, so the use of methods and general ink also have some differences.

Transparent ink must be fully stirred before printing If in the colder winter, the table printing transparent ink should not be added with too much thinner because of the low drilling degree, and the drilling degree is generally controlled at 18-22 seconds and 3 cups is appropriate. Then according to the depth of the printing plate Adjust the blade angle and the pressure of the impression cylinder and the distance between the doctor blade and the embossing point.

If the misalignment of solvent misalignment control or process operation errors are very likely to cause many failures, so every link can not be sloppy.

Troubleshooting of common faults in clear ink printing
In the process of printing flexible packaging, transparent ink is mostly used with aluminum film or aluminum foil bottom to improve printing and visual effects. However, some quality phenomena often occur during the actual use process, such as the phenomenon that the clear ink has pitting and uneven inking after printing, which greatly reduces its expected effect. Therefore, it is necessary to be familiar with the nature and printing characteristics of the clear ink, and analyze and eliminate it.

1. Produce "pitting" phenomenon when printing transparent ink
The main reason and the solution to this failure is that after the printed product has been coated with an aluminum film, the flash effect will come out. However, if you look closely, you will find that the surface has a pinhole, as if it is not printed. The main reason for this failure is:

1 The surface of the embossing roller is not delicate enough, or there is foreign matter such as dust, which causes the ink to be thick enough here. Check the embossing roller for dirt and wipe the surface clean; check the quality of the roller. Replace the rubber roller.

2 Plasticizers, lubricants, etc. contained in the film float to the surface to prevent the normal transfer and lubrication of the ink. Before printing, prepress the preheating of the plastic film, and if the film is not warmly printed, replace the appropriate plastic film.

3 The ink is too high in rheology, too dry, or lack of drilling agent causes ink transfer and poor wet adaptability. The ink titer should be reduced appropriately and slowly using thousands of solvents.

4 printing pressure is too small. The printing pressure can be appropriately increased and the printing pressure can be controlled (generally about 4 kg).

5 Problems of printing plate or embossing roller (expressed as regular pitting) The plate and embossing roller should be carefully inspected for defects. If any, re-plate or replace the roller.

2. Adhesion after printing transparent ink
The main reason and solution: In the high temperature, high humidity of the rainy season, the plastic film is prone to sticking during the reeling after the gravure printing, and the transparent ink is stuck in pieces, and the ink cannot even be separated from the underlying plastic film. Cause a lot of waste products. Most of the adhesions produced by printing products are caused by ink drilling, high ambient humidity, and high pressure, which are caused mainly by the following turbulences. 1 Insufficient heat resistance of the ink itself produces greater drillability under high temperature conditions. When the ink is dry, it cannot be seen with the naked eye. Since the printed product is rolled up, the residual solvent is difficult to evaporate. The resin in the ink cannot be dried and solidified to cause severe blocking of the finished product. Excessive residual solvent in the ink will cause severe blocking of the finished product after winding up. Too much residual solvent will not only affect its firmness, but also be extremely unfavorable to the food, causing odor in the package. 2 Because the ambient temperature is too high, the ink will be softened, resulting in adhesion of the print. At room temperature, many prints using clear ink are normal in handling and use, but when printed at high temperatures, the ink softens and causes blocking. Therefore, it is required that the operating temperature of the printed matter and its use should not exceed 50 degrees Celsius and it is better to control the temperature below 45 degrees Celsius. In addition, if the winding is too tight and the winding tension is too large, the adhesion solution may be caused by controlling the printing drying temperature and relaxing the tension. The winding should not be too tight. 3 The ink and the substrate do not have good adhesion. The ink on the substrate is not adhered firmly. The solution is to choose the correct ink. Control the quality of the ink to adapt it to the substrate. In addition, the substrate surface can be treated to improve its affinity for the ink is also a method to reduce the occurrence of ink adhesion. It is generally necessary to ensure that the BOPP surface tension should be 38 Dyne.

3. Printing transparent ink is not high gloss after aluminum composite
Main reasons and solutions: The main reasons for this phenomenon are: (1) The transparency of the ink itself should be replaced with a good transparency ink.

2 If the solvent volatilization during printing is too fast, the appropriate slow-drying solvent should be selected according to the requirements, so as to inspect and improve the ink rheology. 3 poor uniformity of the aluminized layer, resulting in poor anti-glaze to replace the aluminized film and ensure that the surface is uniform, no pinholes. 4 The squeegee angle is too large The plate hole is shallow. To adjust the angle of the squeegee, the angle is generally controlled at about 35 degrees.

4. Blocking phenomenon of transparent ink
Main reasons and solutions: This phenomenon usually occurs when the temperature is low. In this case, the ink should be heated at room temperature of 35°C. In order to prevent accidents, it must also be guarded by special personnel.

In short, the misalignment of solvents, improper control of the degree of boring, or misoperation of the process are all very likely to result in many failure phenomena. Therefore, every link cannot be sloppy. Therefore, in the use of transparent ink printing, in order to obtain the desired effect of all aspects must be strictly controlled, and according to the actual situation of printing choose the right ink.