Postpress film, also known as laminating, is a form of decorative processing on the surface of printed paper. It mainly refers to the thickness of laminating machine is 12 to 20 um (the thickness of PuR glue is about 4 m. The adhesive of the transparent adhesive film is affixed to the surface of the printed product together to form a processing technology of a paper-plastic product.
Film coating process development overview
Lamination process was introduced to China in the 1970s. The first is the introduction of oil-based solvent-based adhesive coating process. Since the toluene in the solvent is harmful to the human body and the environment is seriously polluted, it was later changed to a water-based glue that is a coating type coating process (ie, an aqueous acrylic adhesive is used). Because of the strong hygroscopicity of the paper and laminating equipment, the tension between the film and the paper is not easy to adjust. Quality problems are difficult to solve.
China began to introduce and use pre-film coating technology from the early 1990s, and introduced advanced pre-film coating equipment from Europe and the United States in early 2000. In terms of environmental protection and product processing quality, this process is much more advanced than previously used oily or water-based adhesives. It is a more advanced film coating process.
Precoat film coating process features
(1) Process environmental protection: The use of EvA hot melt adhesive will not cause harm to the environment and human body; there is no paper and ink on the quality of the coating film, no pollution, low loss, can process food packaging boxes and children's books and other products.
(2) Reliable quality: It is not easy to produce wrinkles, bubbles, and curls. And the separation of paper and film.
(3)Easy to use: Only three steps of feeding, filming, and cutting are applied when coating the film, and there is no glue drying part: the pre-coated film coating equipment is small in size, low in price, and simple in operation.
The inadequacies are that the cost is high, and the price of film-covered materials is about 0.60 yuan/m. If the price can be effectively improved, the market demand will be great.
At ChinaPrint 2005 and China International Print Exhibition, a new type of PUR adhesive automatic laminating machine was demonstrated. The equipment is produced by the Swiss company Stan Limon and it has established a joint venture plant in Shanghai. From the aspects of environmental protection, quality, cost price, material use, etc., PUR adhesive coating type coating equipment is currently a coating technology equipment with international advanced level.
It is not difficult to see that China's film coating technology has undergone several stages of oil-based solvent-based adhesive coating, water-based adhesive coating and EVA coating. At present, it has developed into a new phase of advanced PUR adhesive coating technology. .
PUR adhesive coating process
PuR glue coating process is: preheat PuR glue adhesive storage paper storage film an adjustment pressure (tension) a send paper film coating glue automatically remove print dust removal a static one compound one automatic points Cut to automatically pile up the finished product.
PUR adhesive coating process characteristics
(1) Advanced equipment: The use of advanced servo devices is easy to use. Just set according to the data standards used to obtain the desired results (including various rules, thickness, and glue volume adjustment). Automatic powder removal is convenient and completely eliminates static electricity. The paper is conveyed smoothly, and the error is automatically segmented automatically. The automatic tension adjustment ensures that the quality of the film is stable and reliable.
(2) Good quality: The high strength of -T-PUR adhesive film is generally free of wrinkles, blisters, curls, etc. The equipment has a high degree of automation, can effectively control and ensure uniform tension between the paper and the film, automatic powder removal device It can ensure the complete removal of printing and dusting; automatic thermal cut film quality guarantees that PUR glue has good fluidity and adsorption capacity, there is no confrontational problem when cold and hot glue is processed, and it can withstand the temperature of 40-250°C for quantitative The paper has a good adhesion effect above 100g/m because the adhesive layer is thin and uniform. Therefore, after the film is clear, the transparency is good, and the color is more vivid and vivid.
(3) Fast speed: 60 to 80 meters/minute can be achieved, and off-paper can reach ~8000 to 10,000 sheets/hour.
(4) Environmental protection: The use of PUR adhesive has no pollution to the environment and no harm to the human body.
(5) Low cost: Both the film and adhesive materials have been made locally, the price is low and only about 4g PUR glue per square meter, the coating thickness is 3 ~ 4m, the price is 0 36 ~ 0 39 yuan / Square meters. While citing PUR adhesive film coating equipment, in order to better understand and confirm the advanced reliability of this equipment process, I went to Hong Kong in February of last year to use PUR plastic film coating equipment for more than 5 years. Cheng Zhi Film Co., Ltd. conducted a field visit to understand the use of the equipment for several years. The company's general manager, Mr. Gu Qifa, was pleased to tell me that although the price for buying this equipment was relatively high at the time, this was the wisest decision I made, because it brought us amazing benefits.
Film coating market perspective
Since the initial adoption of the oil-based solvent-based adhesive coating process in China, it has caused a lot of trouble for processing companies, and quality has become the most troublesome issue and has not really been solved for more than 20 years. The appearance of the pre-coated film was slightly improved, but its cost was high and it could not be widely used. PUR glue is the coating film process. Film quality and production costs have a turning point. As far as the current situation is concerned, only the Swiss Stan Limon Company has a higher production price for such laminating equipment, which is only applicable to professional laminating companies and enterprises with large-volume processing business.
At present, there are tens of thousands of domestic film processing companies. About 40% of the nearly 70 million books and periodicals published annually in China are coated with a cover film, and various types of packaging boxes are also widely used. Keep its delicate and detailed appearance without being damaged. Although the problem of separation and recycling of paper and plastic has not been solved yet, the application of the oil-based solvent-based glue coating has not been completely improved, but the number of applications of domestic coating technology is still increasing. It is understood that some printing and packaging companies are still using a large amount of solvent-based glue coating process. For example, in the Zhejiang area, the owner of a printing company uses a solvent-based glue coating process in order to reduce costs regardless of the health hazards of workers and environmental pollution, and uses a three-year rotation system to evade the burden of responsibility. Because workers are exposed to solvent-based materials for a long time, it may cause leukemia after 3 to 4 years. There are many such cases. It can be seen that the elimination of the solvent-based glue coating process is imperative and the relevant departments should strictly implement it.
The long-term practice proves that the lamination technology has its own necessity but must comply with the general trend of environmental protection. At present, some advanced countries have eliminated the backward solvent-based adhesive coating process, using EVA adhesive pre-film coating and higher-level PUR adhesive coating technology. Under limited conditions, China can also gradually free itself from the laminating process and integrate it with international advanced technology as soon as possible to advance the environmental protection and product quality of its production, completely solve the problem of film quality that has existed for many years, and enter internationally as soon as possible. Go ahead.
Reprinted from: Printing Information