Bookbinding uses glue-binding technology, which has been raised loudly since the 1970s. However, due to various reasons, the promotion of glue-binding technology in China has not only failed to achieve the expected goal, but the binding quality problem caused by glue-binding has become the main culprit in the quality problems of glue-book publications. According to the statistics of the National Press and Publication Administration's Quality Inspection Center, the quality problems in China's printed publications are not only related to the quality of printing, but also the quality of binding and prepress-making. However, the quality of bookbinding accounts for more than 60% of all quality problems. .
The printing department's editorial department has also often received calls from printing companies and hopes that we can help solve some of the problems in glue-booking. To this end, we interviewed senior engineer Li Jiaxiang of the Printing Quality Inspection Center of the State Press and Publication Administration, Wang Huaizhu, a postpress expert, Cao Hua, head of the preparatory group for the Postpress Technology Innovation Center, Zhou Qiping, director of Wuxi Wanli Adhesives Factory, and Shandong Xinhua Printing. Zhang Shuheng, the deputy director of the factory in Dezhou, investigated a number of users and listened to the opinions of experts on issues raised by everyone. In this issue we focus on the issue of glue used in bookbinding.
First, the characteristics and application of EVA adhesive
The bookbinding process is an advanced technology for binding books and periodicals. It has the advantages of a smooth appearance, a simple process, a high-speed machining process, and a shortened publishing cycle. It has been rapidly developed and applied in recent years.
According to Li Jiaxiang, senior engineer of the Printing Quality Inspection Center of the State Press and Publication Administration, at present, more than 60% of textbooks and editions in China are bound by glue. According to relevant departments, in the next 10 years, one of the development goals of book printing and post-processing technology is to focus on the promotion and application of glue-binding technology, and it is also possible that hardcover books use wireless glue-binding technology to process book blocks.
At present, the glue used for bookbinding in most printing plants in China is mainly EVA (Ethylene Vinyl Acetate) hot melt adhesive. It is a solvent-free thermoplastic compound and its basic compound is EVA resin, namely ethylene. The copolymer of vinyl acetate under high pressure generally accounts for more than 40% of the hot melt adhesive composition. According to Wang Huaizhu introduction, EVA hot melt adhesives mainly have the following characteristics:
1. Solid at room temperature, heated to a certain temperature and melted as a liquid, cooled to a certain temperature and return to a solid. The curing speed is fast, and it can be operated continuously. It is suitable for production with linkage lines.
2. Strong adhesion, a certain degree of hardness and flexibility.
3. With repeated re-adhesion, if there is a problem with the cooling-cured adhesive layer of the adhesive book, it can be reheated after heating, and then cooled.
4. Bonding, curing, and drying time are short. Once applied, pressed, and cooled, bonding can be completed in a matter of seconds, and it can be hardened and dried in a matter of minutes.
Although EVA hot melt adhesive has many advantages, there are also some problems, such as thick coating adhesive layer, high use temperature, aging deterioration, poor flexibility and so on.
Second, China's hot melt adhesive production status and problems
According to related data, in addition to the remote provinces and regions, there are nearly 100 companies that produce hot melt adhesives in more than 20 provinces, autonomous regions, and municipalities directly under the Central Government. However, most of the enterprises are small in scale, low in technology, and have few testing equipment (even No) There are no more than five companies with a certain scale and management. In 1999, the output of hot melt adhesive in China was 18,000 tons, and in 2000 it exceeded 20,000 tons. In 2001, it was estimated to be 25,000 tons.
Although the output of China's hot melt adhesives has increased year by year, it appears that the overall quality is low and the market has serious competition. After investigation, it is understood that the main problems that currently exist are the following:
1. The market for hot melt adhesives is not standardized and lacks uniform and detailed standards. The hot melt adhesives produced by the manufacturers cannot be differentiated based on the climate difference between the north and the south, the binding processing equipment and the applicable paper type, and the corresponding quality grades and specifications have not been divided in detail.
2. Many manufacturers of hot-melt adhesives are not properly aware of the market competition and market competition. They only see the price advantage of single-ton plastic, do not take into account the quality advantages and social reputation of plastics, and are heavy and light in quality when selecting materials. Raw material testing methods are not strict, not fine, the quality of finished products fluctuates, and the overall quality of the glue is poor. Although the hot melt adhesives produced by some rubber factories are of good quality, there are also problems with unstable quality.
3. The use of hot-melt adhesives such as printing plants and bookbinding companies is not correct when it comes to choosing adhesives. The goal is to pursue the low price of single-ton adhesives, ignoring the quality of the adhesive. It should be advocated to reduce production costs by using good quality glue and reducing the amount of glue applied to a single book.
4. There is a lack of communication and communication between producers and users of hot-melt adhesives. People who produce plastics do not know the problem of using glue, and those using glue do not understand the performance of glue. If the manufacturer of the glue uses a lack of understanding of the hot melt adhesive, blindness may occur due to lack of corresponding technical support when selecting the glue and using the glue.
5. Some rubber manufacturers are over-optimistic in their estimates of the wireless glue-binding market, leading to a rapid expansion in the number of hot-melt adhesives manufacturers. Some small companies compete with regular companies at low prices, and the market is in a chaotic order, which is not conducive to domestic hot-melt adhesive products. The improvement of quality level.
