Analysis of PUR glue technology and its application

With the continuous and rapid development of the national economy, the demand for all kinds of professional books continues to increase, and the variety of books published by various publishing houses has increased significantly every year to the provincial book quality inspection stations. By the end of 2004, there were more than 6,500 types of bound binding in the test.

Judging from the overall design of the book, the previous situation that only attached importance to pre-press and despised binding processing has changed a lot. People in the industry generally recognize that for a high-quality book, not only must it have good, plate-making technology, exquisite printing effects, but also a refined binding appearance, it can complement its overall design and book content, and it can have a longer life. Use and preservation value. Judging from the book synthesis and post-press processing techniques recommended by publishing houses and various manufacturers in recent years, there are more and more books printed with paper of different weights, printed with plastic films and decorated with varnish and special inks. From the test results of books, it can beautify through pre-press and printing during processing. Basically can receive the desired effect. And for post-press processing, due to the current range of material choices? ⒐ ひ ヒ bad quality embankment? Naopu is a bad shovel 戓 普? 笮 Ч? The traditional squid persimmon cough Bi Shannan scorpion shelter crab ⑸? 4 You Ji Ji 『蠹 庸 さ 墓 ひ 沼 τ 美 纯 矗? Shell bar banana? ∮≈Fenjiji mallet? Doro roasted? Barwon wonton? VA hot-melt glue order varieties, so far have not seen a family with other types The post-press processing technology of enterprises whose mechanized mass production of adhesive materials is relatively simple. Post-press processing technology) is already running against the current, because the commonly used EVA hot-melt adhesive is suitable for the binding of a single variety of paper, which can ensure the quality of the book. It is more effective to bond books synthesized by multiple papers and printing methods. It's difficult. In response to this situation, I will briefly introduce a PUR binding process that is being used in industrialized countries. I hope that it will be helpful for the research and application of new processes and new materials, and it will be beneficial to promote the improvement of the overall quality of books.

PUR adhesive is designed to adapt to printing paper, plastic film varnish and ink of different weights. It is a low temperature hot melt adhesive with both rigidity and flexibility. Its main components are polyhydric alcohols with active hydrogen (polyester, polyether, etc.), low molecular weight diols (chain extenders) and addition polymers of isocyanates. The isocyanate group encounters moisture in the air and produces an irreversible literary literary reaction to form a strong adhesive layer. This is an inherent feature of PUR glue. The application of PUR adhesive in the printing industry is gradually promoted with the increasing diversification of printed products. It can bond a variety of materials, including varnish coatings, UV curing layers, plastic films and coating paper. It will not be volatilized by various materials. Performance degradation and product quality. From the currently collected data and samples, it can be seen that the books and journals drilled with PUR glue and the books and journals bonded with EVA hot-melt adhesive are now more obvious.

According to the thickness of EVA hot melt adhesive recommended by this site, EVA hot melt adhesive should reach a certain strength (the thickness of the book block brush glue depends on the paper and the thickness of the book). The adhesive layer should be controlled between 0.6 and 2mm. Under the same circumstances, the PUR adhesive layer can achieve the same strength as EVA hot-melt adhesive at 0.25mm regardless of the thickness of the book and the paper, and it is much softer. The book is very flat after it is opened, which can greatly improve the reader's reading. Comfort is a new technology that solves the problem of uneven binding of paperback bound books that has plagued us for many years.

High temperature and low temperature resistance, strong environmental adaptability

The author collected a few paperback books bound with PUR glue brought by a friend from a printing company in Taiwan. The bookbinding technology was promoted in the same year, and the method of testing EVA hot-melt glued books was compared. The experiment will be a book bound with PUR glue. Put the book in the refrigerator for more than 4 hours, and then take it out of the refrigerator intact. You will not hear the cracking sound of the EVA hot-melt glue bound book after refrigeration. The refrigerator experiment simply tested the adaptability of the book to the low temperature environment that the book may face in winter. So, how durable is the PUR-bound booklet under high temperature conditions in summer? After the thermostat experiment, when the temperature reaches 40 ℃ or more, the hand feels heat to the endurance (normal human hands can withstand 70 ℃). The PUR glue book can remain undeformed and not scattered, and the EVA hot melt adhesive begins to soften. The loose pages of the book come off. Information shows that PUR glue can adapt to 94 ℃ or minus 40 ℃ environment. Books bonded with PUR glue can ensure effective internal and appearance quality without affecting reading, whether in the hot south or the northeast region with very low temperature, which greatly expands the scope of book distribution and solves the problem of regional temperature of EVA hot melt adhesive. The problem of limitation.

The spine is flat, and the appearance quality of the finished book is greatly improved

When using EVA hot-melt adhesive to bind art paper book blocks with irregular texture and long paper fibers, glue with a temperature of 180 ℃ is applied to the groove on the back of the book. Due to the temperature, the paper moisture content will change sharply, causing the paper A large number of wrinkles are generated on the back of the book. The unevenness on the back of the book after the cover is significantly affected the appearance of the entire book. Because PUR glue is a low-temperature adhesive with a low working temperature (within 120 ° C), the moisture of the paper at the spine will not be lost. At the same time, the PUR adhesive layer has a certain ductility during the drying process to restore the paper fibers. In addition, due to the small amount of PUR glue, few adhesives are squeezed out when the cover of the package is squeezed. The resulting spine is straight and the appearance is straight, which can greatly improve the appearance quality of the book.

The use of PUR must adopt some processes different from EVA hot melt adhesives. At present, there are already open glue pots and closed pressure nozzle systems specially used for PUR glue. A number of foreign post-press machinery manufacturers have developed special equipment and units combined with EVA hot-melt adhesives. After modification, they can be applied to both EVA hot-melt adhesive processing technology and PUR glue processing technology. It is not complicated and can be operated well with the existing technical level. In addition, according to some binding experts, PUR glue has many advantages that the current process cannot be completed, such as the resistance to grease solubility and the softness of forming for hard-covered rounds. With the popularity of PUR glue binding technology, some publishers have already felt the many advantages of PUR glue. They will increasingly use PUR glue to bind books to ensure the quality of book binding and the durability of books. The same content books are in different regions. Adaptability.

I believe that more and more books will be bound by PUR glue. I also hope that the above introduction will attract the attention of the printing industry.