Use of hot melt adhesives in wireless binding

The simplest type of wireless binding is the tandem printing of form orders. It glues one side of the entire stack of pages to make the multiple pages stick together. Due to the wide range of application forms, it is still one of the most common binding methods for zero offset printing. The glued parts of the form sheet are mostly on the side of the printed page, which is customarily called the glue head. The operation mode of the rubber head is to press the pages firstly, and when the specified number of sets is reached, a backing paper is added to divide the pages into one copy, the number is a stack, the stacks of 3 to 5 are one, and then it is along the ground. One end of the foot is bumped. Since the form sheet is used to prevent page breaks due to the reduction of the page, a cut-off point is usually set at the end of the cutting line, which is used as a basis for trimming the edges of the sky, and neatly or typing the paper. When wiping the tip paper After eliminating the vacuole, wait until it is fully dried, then cut the finished product. The rubber head prints have a very small area for each page, and rely heavily on the sticking effect of the tip paper, not only maintaining its flat shape, but also preventing scattering and page-off. Because each page of the form has a small bonding area between the pages, and the tip paper is extremely thin, it is easy to pull together and it is convenient to use.

The adhesive material of the rubber head is generally a polyvinyl alcohol or polyvinyl acetate emulsion (white glue). Polyvinyl alcohol needs water bath heating and melting, which is troublesome to use, but it is inexpensive. Polyvinyl acetate emulsion is easy to use and can be directly added with plasticizers, which are slightly more expensive.

Prior to the appearance of such synthetic glue, glue heads used mostly animal protein glues such as bone glue, hide glue or tannin extract. The use of animal protein glue is rather troublesome. They must be swelled, heated and dissolved in water, and the melting temperature must also be controlled below the boiling point of water to prevent brittleness. Whether it is the first two types of synthetic glue or the latter three kinds of animal protein glue, there are two common points, one is strong adhesion, and the other is water-soluble slow-drying type adhesive material. Although the plastic head technology is simple, it is the prototype of wireless binding of hot melt glue later.

The wireless binding process for books and periodicals can be traced back to the middle and late Tang period more than 1,000 years ago. At that time, there was a butterfly costume, a kind of binding form developed by the technology of reel loading, folding, and cyclone mounting. It integrates multiple folds of two-page signatures into pages in the order of page numbers, and then pushes them into a trapezoidal shape so that the border between the signatures forms a width of 2 to 3 millimeters of brush, and after uniform brushing, follow along. The creases hit and lie flat on the platen, extruding the excess pulp lake, and after drying, it became a coherent booklet matrix.

Since the butterfly outfit borrows some of the mounting techniques, it uses a thinner paste, so that it can still crash into the signature after brushing. Because the 2 and 3 editions of each book in the butterfly form a unified format, there is still a high practical value in the inscriptions of atlases, reference books, and tour guides.

Another form of wireless binding appeared earlier in the loose-leaf edition, and it was also limited to the series of pages of two ultra-thin books of one fold, two pages and four editions. This kind of product could not be iron-stitched or saddle-stitched because it was used in the text of books. Most of the paper is below 70g/m2. The thickness of the paper is less than 0.11mm. If the bookbinding is used, the stacking thickness of the book pages is less than 0.44mm. If the saddle stitching is used, the thickness of the two-layer paper is less than 0.22mm, and the smallest of the staple iron wires 26 The wire (in English Birmingham Wire Gauge) has a diameter of 0.6mm, the book back is taller than the book block, and it is difficult to cut the finished product. Furthermore, the stress points are all concentrated on the position where the wire penetrates the hole of the paper. The book page is easily Pulling it out and replacing it with sticky folded bags avoids the drawbacks of the above situation.

The structure of the tumbling is similar to the saddle stitching, which is divided into the inner posts of the outer posts and the imposition of the cover pages is used. After the printed sheets are completed, the reverse affixes of the outer placards are printed, the 1 and 4 editions are in the inside, and the editions 2 and 3 are outside. The inner post is folded forward, and then it is overlaid with dozens of copies. After the book is hit with a brown brush, the paste is deliberately pasted into the gap between the signatures, so that the boil width reaches about 1 mm. When the page above is mentioned above, it will be accompanied by a slightly clasped inside quote. If you turn over the page that is lifted, you can wrap the inside quote along the crease. In order to improve the efficiency of turn-ups, often the outer posts are made into small and large sides, and the large sides are placed on the upper page, so that the accuracy of the uncovered pages can be improved. Now that loose-leaf editions are rare, the turn-up process is basically used for post-press processing of documents, orders, and work reports. Both the butterfly and turn-up adhesive materials use starch paste that cannot be dried quickly, and cannot be too thick, which is not conducive to operation.

The plastic head, butterfly head, and turn-turning technique are not complicated. There is no need for too many special tools and equipment, and the post-press work can be performed under light printing conditions.
Wireless binding and hot melt adhesives
This article is based on the wireless binding, which refers specifically to the production of glue-bonded paperback books. Printed paperbacks are printed mostly in full-sheet and half-width format. They need to be folded into a slightly larger booklet than the finished product, and a series of follow-up processes should be completed according to the page number. This paperback book does not include iron wire saddle-stitched books and periodicals. Although the wire saddle stitching is also a type of paperback, the book is too thin to be used for wireless binding. Moreover, the wire saddle stitching has been implemented with the matching, setting, and cutting of the three stations and has automated high-efficiency production capabilities. Wireless binding of books and magazines must reach a certain thickness, that is, between 5 and 50 mm. Prior to the appearance of the hot melt adhesive paperback book, there were two kinds of wireless binding transitions, book back sawing and signature punching. The purpose of these two processes was to focus on the linking process. To compensate for the lack of sewing capacity, it can only be defined as perfect binding.

The bookbinding notch of the back of the book is manually or on the saw table to slot the back of the book bundle. The depth of the groove is determined by the book page where the book is folded. The book page should not be too deep or too shallow. The groove width is 1.2-1.8mm. From 15 to 3mm, the number of slots is selected according to the thickness of the book block and the book block paper. In fact, the number of slots is determined according to the weight of the book block. The larger the weight of the book block is, the larger the slot number is, and vice versa. , The slot distance can be appropriately relaxed, and the number of slots can be reduced.

There are two kinds of operating procedures for the book back saw slot glue binding: the first is to assemble the pages first. After checking the books, the books will be bundled. Then the back of the book bundle is marked with a saw slot, and then the glue is applied. After folding, the different signatures are individually tied with a scribe saw slot, and then the western, woolen, and brushed glues are checked.

The advantage of the first kind of operating procedure is to conduct a macho check. At this time, the trapezoid formed by the signature signatures is complete, and it is easy to identify mismatches. The problem is that the subsequently sawn grooves are all parallel, and grooves of adjacent signatures are used. They are all concentrated in the same slot, which reduces the position of the grooves in the entire book. The groove of each signature is mostly connected to the side of the adjacent signature, thus increasing the adhesion between the signature and the signature. The junctions increase the structural strength of the entire book.

Through the sampling test, the first operating procedure for wireless glue binding products (32 format) hanging weights ≥ 3.5kg tensile, the second operating procedure wireless glue products (32 format) suspension weight tensile> 4.8kg.
The signature punch binding is the use of a knive cutter on the page roller of the knife-type folding machine. Before the last fold of the signature, a line of holes is formed by folding the signature along the crease line, through the last folding, the book The rows of holes on the backs of the posts flaring outwards in a trumpet shape. The inner pages of the rolled perforations turn outwards into trapezoidal or fan-like shapes. The edges of the rolled holes are left with rough paper fibers, which is conducive to the penetration and infiltration of glue. On the one hand, the position of each hole in the signature is difficult to overlap with the position of the adjacent signature. Therefore, the distribution of the hole position in each book is quite uniform. These conditions are conducive to improving the firmness of adhesion and the detection of the sample. In the book, the punching and binding of wireless binding products (32-inch) hangs heavy objects with tensile strength of 4.8kg or more.

However, this kind of wireless glue binding is subject to certain restrictions under certain objective conditions, and there are also some difficulties in product quality control.

1 The signature of the signature must be a sheet of paper that can be folded through a knife folding machine.

2 Paper sheets should not be too bad, and the paper fibers should not be too short. The most typical is paper pulp.

3 The length of the flower wheel cutter is longer than the length of the book signature, and the hole is continuously punched. After the signature is punched, most of the signatures will be scratched. The fuzzy check mark is difficult to remove, such as the serial number check, production. The efficiency will decrease again.

4 It is difficult to rework after punching a book, and the technology is depleted. The book glued to the back squaring and the book-stitched punching must go through two gluing steps. The first gluing glue should be slightly thin, which is conducive to infiltration and infiltration. Before the glue layer begins to dry, it is brushed again. The second glue should be slightly thicker, which can make the adhesive back and the back of the book block more firmly. Towel back paper requires long paper fibers and thick paper to enhance the strong back of the book and also to fill the back of the book. The back paper is generally used for spinning (long fiber paper). For some special books and products, It is also necessary to apply a layer of gauze before the non-woven fabric is applied, and reinforce the back reinforcement. The back drying method is very simple, natural drying in summer and autumn, and drying in winter and spring. After the back of the book is dried, the book is divided, the cover is packaged, and the finished product is cut. (to be continued)