Troubleshooting related to tension
The tension of plastic film directly affects the printing quality. If it is not controlled properly, it will bring quality problems to printed products and even cause waste products. In summary, the tension affects the quality of printed matter and causes the following failures.
(1) The overprint is not accurate. Overprint quality is the most intuitive index of printed matter. There are many factors affecting the inaccurate overprint of plastic film, including the objective factors such as mechanical equipment, ink suitability, environmental temperature, etc., and the subjective factors such as the quality awareness of operators. That is to say, in addition to the film material thickness uniformity is not good; the imprint roller deformation; plate roller design is unreasonable, processing accuracy is poor; printing speed change; drying temperature is too high; guide roller sticking and other factors, the change of printing tension is also one of the main factors. We should pay attention to observe and analyze the phenomenon of overprint inaccuracy and take corresponding measures. If the longitudinal (movement direction) register of plastic film is not accurate, it may be caused by the change of tension during film traction, which may be caused by the change of longitudinal printing registration. The reasons are: improper adjustment of drum brake of Uncoiler device; excessive drum material or too large diameter of cylinder material; improper setting of three roller speed; decrease of surface friction force of three rollers; improper setting of roller speed; When the tension of rewinder changes, it is necessary to check and adjust the control devices to ensure the tension balance and stability during traction. The main reason for the shrinkage and displacement of the longitudinal pattern size during printing is that the shrinkage allowance is insufficient. Due to the influence of plastic film tension and heating and drying, the longitudinal size of the film is larger than that of the printed picture and text, so that the image and text can not be printed in a certain position during printing. The solution is to keep appropriate shrinkage size in plate making and fully reduce film tension. In a word, overprint is closely related to tension. Therefore, attention should be paid to the change of tension in printing, and the tension should be adjusted and controlled to ensure the stability of tension in the whole printing process. In order to avoid or reduce the loss caused by overprint, we should not only ensure that the tension between unwinding and rewinding of substrate is consistent, but also pay attention to the trend of overprint inaccuracy, and then take corresponding solutions.

(2) Poor fastness of printing ink. The reason of poor printing fastness of plastic film is that the affinity between the printing ink and the material to be printed is not good, and the ratio of mixed solvent is not up to the requirements; If the printing environment temperature and relative humidity can not meet the requirements and produce static electricity, the room temperature of the workshop should be controlled at 18 ~ 23 ℃ and the relative humidity should be controlled between 50% ~ 60% to prevent the influence of static electricity and keep the environment clean. Besides, the main reason is that the surface tension of plastic film can not meet the requirements, including poor printability of the film itself and poor corona treatment The surface tension can not meet the printing requirements. Film surface tension and surface wet force are very clear standards for accurately measuring the adhesion of printing ink and other materials on the surface. According to practical experience, the surface tension of plastic film can reach the viscosity requirement when the surface tension is controlled at 39 ~ 42mn / m, while many white pages (no printing content) will be produced when the surface tension is below 37Mn / m, and the viscosity is not good when it is below 35MN / m After corona treatment, the surface tension of plastic film is tested to see if it meets the requirements. If the surface tension is still unqualified after treatment, the film material should be replaced. In addition, attention should be paid to the adjustment and control of tension in printing to ensure its stability in line with the printing requirements.

(3) Adhesion and back rub dirty. The main performance is that the printing surface adheres to the back of the other layer between the upper and lower layers of the winding film, so that the ink on the printing surface is transferred to the back of the other layer. This fault may be caused by excessive winding tension. Attention should be paid to adjusting and reducing the winding tension. In addition, it may be caused by the slow drying speed of the ink and the residual solvent. Therefore, it is necessary to adjust the control drying device, confirm the temperature of the dryer and other control factors, add anti fouling agent in the ink or use the appropriate ink formula to improve the drying speed of the ink, pay attention to the suitability and dosage of the solvent, or use the appropriate fast drying solvent.
(4) The winding is misplaced. That is, the film winding has a lateral deviation from the center of the press. This fault may be caused by the failure of the horizontal paper winding alignment device. Check the device first. In addition, in addition to the uneven thickness of the material, the material should be replaced; if the film is excessively heated, the temperature of the winding paper should be reduced; if the center of the printing machine and the roller are not found correctly, the alignment of the center of the printing machine and each drum should be checked. There are more ink, plastic scraps or foreign matters adhered on the drum. Besides, these dirt and foreign matters adhered to the drum should be removed, and the winding force of the winding paper is too high Low is also the main cause of failure, so pay attention to adjust and control the winding tension.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service. The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries. We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.