With the sustained and rapid development of the national economy, the demand for various types of specialized books continues to increase, and the number of books published by various publishers has increased substantially to the provincial book quality inspection stations. The number of test products participating in the quality assessment increases at an annual rate of about 10%. At the end of 2004, more than 6,500 varieties of glue-binding products participated in the testing.
Judging from the overall design of the book, the previous situation in which only emphasis was placed on prepress and printing and light binding processing has changed a lot. People in the industry generally realize that for a high-quality book, not only good, plate-making technology, exquisite printing effects, but also a fine-grained appearance, can be complemented with its overall design and book content, and it can be even longer. The use and preservation of value. In recent years, more and more books have been printed with different grammage papers, plastic film printings, and varnishes and special inks to decorate the book synthesis situation recommended by publishers and various manufacturers and postpress processing. From the test results of the book, it is realized by prepress and printing in the process of processing. Basically can receive the ideal results. For the post-press processing, due to the fact that the current material selection range is small, and the actual conditions such as the single process cannot meet the requirements of the design requirements and quality defects occur. From the point of view of the process of book printing and processing, currently printed books in Shandong Province are all EVA hot-melt adhesives except for a small number of hardcover books. To date, no one has yet seen a mechanical mass production of other types of adhesive materials. The company's post-press processing technology is relatively single. Post-press processing technology is already being used against water because the currently used EVA hot-melt adhesive is suitable for bonding a single type of paper. It can ensure the quality of books and effectively binds a variety of papers and a variety of printing methods. Difficulties. In view of this situation, we will briefly introduce a PUR glue-binding technology that is being used in industrialized countries and hopes to contribute to the research and application of new technologies and materials, and it can be of benefit to promoting the improvement of the overall quality of books.
PUR adhesive is designed for a variety of different gram printing paper, plastic film coating oil and ink and other materials designed, is a rigid and flexible low-temperature hot melt adhesive. Its main components are polyols with active hydrogen (polyesters, polyethers, etc.), low molecular weight glycols (chain extenders) and addition polymers of isocyanates. The isocyanate base encounters moisture in the air and produces an irreversible textural reaction to form a strong adhesive layer. This is an inherent feature of PUR adhesives. The use of PUR adhesives in the printing industry is gradually promoted with the increasing diversity of printed products. It can bond a variety of materials, including lacquer coatings, UV curing layers, plastic films and coated papers that are not subject to volatilization of various materials. The impact of the material and performance degradation, affect product quality. From the data and samples collected so far, the advantages of books and magazines glued with PUR glue and EVA hot-melt adhesives, which are now widely used, are quite obvious.
Thin, soft gel, easy to read
According to the EVA hot melt adhesive thickness recommended by this site, EVA hot melt adhesive must reach a certain strength (the thickness of the book block brush glue is different according to the situation of paper and the thickness of the book) and the glue layer is controlled between 0.6 and 2 mm. Under the same conditions, the PUR adhesive layer can reach the same strength as the EVA hot melt adhesive, regardless of the thickness of the paper, regardless of the size of the paper. Normally, the thickness of the PUR adhesive layer is much softer, and the book is very flat after opening, which can greatly improve the reading of the reader. The sense of comfort is a new process to solve the problem of inconsistent books that plagued us for many years.
High temperature resistance and low temperature resistance, strong environmental adaptability
The author collected several friends from Taiwanese printing company to bring back a bound paperback book bound with PUR glue to promote the bookbinding process in the past, and to test the method for checking the booklet of EVA hot melt glue. A contrast experiment will bind a book with PUR glue. Put the book in the refrigerator for more than 4 hours, and then remove the book from the refrigerator as it is. You will not hear the cracking sound of the EVA hot melt binding book after refrigerating. The refrigerator experiment simply detects the adaptability to the low temperature environment that the book may face during the winter. So, what is the durability of PUR Binding Book in summer at high temperatures? After the oven test, when the temperature reaches 40°C or more and the hand feels heat to endurance (the normal human hand can withstand 70°C), the PUR book can keep its shape and does not fall, and the EVA hot melt adhesive begins to soften. The booklet fell off. According to data, PUR adhesive can adapt to the environment of 94°C or minus 40°C. Books glued with PUR glue can ensure that the effective intrinsic and apparent quality does not affect reading, either in the hot south or in the northeast region where the temperature is low. This greatly expands the distribution scope of books and solves the problem of EVA hot melt adhesives subject to geographical temperatures. Limitations.
The spine is flat and the appearance of the finished book is greatly improved
When EVA hot-melt adhesives are used to bind an art paper book block with irregular texture and long paper fibers, a temperature of 180°C is applied to the backside of the book. Due to the temperature, the moisture content of the paper will change drastically, causing the paper to deform. Making a large amount of wrinkles on the back of the book and covering the back of the book after the back of the book clearly affects the appearance of the entire book. Since PUR glue is a low-temperature adhesive with a low working temperature (within 120°C), moisture of the paper at the spine is not 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, when the bag cover is beaten, little adhesive is squeezed out, the spine is formed stiff, and the appearance is straight, which can greatly improve the appearance quality of the book.
The use of PUR must be done in different processes than EVA hot melt adhesives. There are currently open gel and closed pressure nozzle systems for PUR adhesives. Many overseas machinery manufacturers have developed special equipment and the combination of EVA hot-melt adhesive linkage unit has been modified to apply to EVA hot melt adhesive processing technology and apply to PUR adhesive processing technology and technology. Uncomplicated is fully operational at the current state of the art. In addition, according to some bookbinding experts, there are many advantages of PUR adhesive that current processes cannot be completed, such as grease-resistant solubility for molding softness of finished rounds. With the popularity of PUR glue binding technology, some publishers have already felt many advantages of PUR glue. They will surely use PUR glue binding books more and more to ensure that book binding quality and book durability guarantee the same content books in different regions. Adaptability.
It is believed that more and more books will be bound using PUR glue, and it is hoped that the above introduction will attract the attention of the printing industry counterparts.
