Stapling after digital printing

Digital printing created 250 billion sheets of printed business in 1999, of which 10% to 20% of printed materials required bookbinding, bookbinding, saddle stitching, and even hardcover binding. Most of the digital printing so far is software manuals and training manuals. Stapling only occupies a very small part of digital printing. However, there are tens of thousands of businesses that cannot be arranged every year according to the time requirements of customers. This means that the bookbinding industry has a lot of room for development in this market.

The library is a big customer of digital printing binding. They generally need hardcover. Therefore, the bindery companies value this business and hope to provide better services.

Unlike the binding of traditional prints, binding of digital prints often encounters some problems. The main causes of failure are the following three aspects:

First, the issue of paper fiber

Digital printing uses a narrow web width of 18 inches. Four layouts are printed head to head. Due to the limited width of the paper, the orientation of the paper fibers leaves room for folding. Similarly, a typical sheet-fed laser printer is best when printing a 9-in. x 12-in. (or 9-in. x 14-in.) two-page head-to-head typesetting product. Unless the digital printer is familiar with the glue-binding process and knows that the direction of the paper fiber should be parallel to the direction of the spine, he must be: what kind of paper is used in the paper bucket, and it does not consider the fiber orientation of the paper. This means It is very likely that the direction of the paper fibers is perpendicular to the spine, which is very troublesome for folding and gluing.

Today's sheetfed printers do not care much about whether the direction of the paper fibers runs parallel or perpendicular to the direction of the paper feed. Therefore, the printer knows that the layout of the printing layout matches the direction of the paper fibers.

The situation of the web printing press is a bit more complicated. The paper feeding direction cannot be changed. Only the orientation of the layout can be grasped so that the direction of the paper fibers can be considered as parallel as possible to the spine.

Second, the book's "foliage" issue

Books that are digitally printed on sheet-fed paper and then bound (glued or hard-packed) often have a "foliar" phenomenon on the periphery of their pages. This is mainly because the paper is quickly dried when it passes through the heating roller of the printing press, causing unevenness in the internal stress of the paper. Other reasons are: improper preservation of paper before printing, excessive water content in the paper, and dampness during printing and binding. The orientation of paper fibers perpendicular to the direction of the spine can also cause such problems.

To avoid this problem, the binder must coordinate with the printer to keep track of the production process during the printing and transport to the binding plant; create relatively stable and controllable environmental conditions.

In general, the “foliage” phenomenon of a book page will gradually disappear within one week after binding, but in today’s fast-paced era of “on-demand printing”, people need to wait and wait, who has the patience to wait for so long. ?

Third, the fastness of binding

Most sheetfed digital presses use toner instead of traditional inks. When the toner passes through the heating roller, it is melted by heat and the ink is fixed on the paper surface. In the process of hot-melting, there is a small amount of solvent released. Although the amount of such solvents is small, they are all adsorbed on the paper surface and affect the adhesion of the binding glue and the paper. The fastness of binding is sometimes related to the fastness of the film. Digitally printed book covers are often colored. Because of the small number of prints, it is also printed using a color toner digital printer. Toner is less sticky to coated paper, and toner peeling is often seen at the turn of the spine.

In general, this short version of the business is not suitable for surface coating and lamination, because the surface of the toner is poorly adherent, slightly crumpled, and the plastic film and the paper are separated. Usually, the film is used only for the cover of a book printed with traditional ink. If the customer insists on the requirement, it is more reasonable to cover the outside of the cover. This will not cause the book block and cover to fall off.

the solution

What can be done to solve the above digital print binding problems?

1. Adjust the thermal melting temperature of the toner of the digital color printer to achieve the best adhesion.

2. With appropriate cover materials, there are a variety of cover materials available, and one that has the strongest affinity with toner is selected and tested. Usually this material has been surface treated and coated with a layer of specially adsorbed toner.

3. The plastic film itself is surface-treated to improve its adhesion to the toner.

(Fortunately, these problems are not related to inkjet printing.) The development of digital printing will change the structure of the bookbinding business, and the proportion of such businesses will increase. Strengthening technical training and material selection is the key to improving product quality and increasing productivity.