20 tips for successful wireless gluing

20 tips for successful wireless gluing

Non-coated paper has more exposed fibers on the surface than coated paper, making it easier to bond with adhesives. The coating paper with a lot of sizing is hard, the cut is smooth and bright, and the adsorption of the adhesive is poor, which increases the difficulty of binding, but it can be achieved by increasing the thickness of the glue layer, appropriately increasing the temperature of the glue, increasing the grooving depth and density, and reducing the angle of the groove edge, etc., to achieve good binding quality. It should be noted that if the paper quantity exceeds 150g/m2 and the thickness of the book core exceeds 15mm, it is recommended to use the locking and binding process; Recycled paper has shorter fibers than pulp paper and is not easy to bond with ordinary adhesives. If you are not sure, you should test the paper first.

2. Pay attention to the direction of the paper threads

After the paper absorbs water and then dehydrates, the radial change of paper fibers is greater than the longitudinal change, so it is necessary to try to keep the direction of all paper materials, including the main text, in the same direction as the back of the book, so as to effectively avoid problems such as uneven book core, book core cannot be flattened when flipping, book back service life is short, and the outer incision of the book is arced. As far as folding is concerned, if the direction of the paper threads is inconsistent with the back of the book, it will cause uneven creases and fibers are easy to break. Moreover, the above symptoms tend to be more severe with the increase of paper quantity.

3. Avoid full-format varnishing

The paper fiber must be directly combined with the adhesive to bond firmly, and the full-format glazed bookpost, whether it is water-based varnish, UV varnish, Fanli water, or wax varnish, will be weakly bonded due to the adhesive repulsion. For this purpose, the varnishing area should be at least 3mm away from the stapling.

4. The inner seal is not laminated, and printing and varnishing are avoided within the indentation line

The bond between the cover and the book core is very important, and this area should be free of ink, avoiding varnishing and laminating. For the inner seal of full bleeding, a 1.5mm blank can be left at the seam with the book core.

5. Spread images and lines must be aligned

If the fold is not correct, it is difficult to remedy at the binding stage. Therefore, at least 3mm of blank space should be left so that the image on the opposite page can be pulled into the binding.

6. The layout should be consistent

All book posts, inserts, sticky pages, and set pages should have certain blank margins.

7. Accurately calculate the thickness of the book back

In order to deepen the visual experience of readers, many designers have made special designs for the color and style of the back of the book, and the color of the cover and back of the book is often different, but this careful design may fall short due to the inaccurate thickness of the back of the book. Therefore, before designing the cover, be sure to make a blank binding sample. Because the paper used by different manufacturers is different, even if it is the same brand of paper, the thickness of the book may be different, and changes in air temperature and air humidity will also affect the thickness of the book core.

8. Leave appropriate hanging edges on the cover

The hanging edges of the cover can store excess glue. In order to improve production efficiency and quality, the top and foot of the cover should have a hanging edge of more than 3mm.

9. Protect the outer cover

The cover and back cover printed with black ink or metallic ink should preferably be laminated or UV varnished, and at least protected by calendering. If lamination is chosen, a thicker, flatter film should be chosen. Films with different transparency have an impact on color balance, and glossy film, matte film or matte film can be selected according to needs. When laminating, first ensure that the surface of the printing sheet is clean to avoid melting toner caused by high temperature, resulting in foaming and wrinkling of the film. And the film should not be pulled too tightly, and stay for 4 hours after rewinding before splitting to ensure that the laminated cover is not curled. Try not to use polypropylene film as it is thin and easy to scratch. Under normal circumstances, several samples can be mulched first, and then batch processing can be carried out after confirming the effect.

10. Design the book poster folding label

Subtract the conventional 3mm milling back amount and extend the folding label to the book core by 3mm, so that the folding label can play a better role. Thick paper above 70g/m2 is designed to be trifolded or bifolded to ensure the alignment of page numbers and page images. Coated paper color pages must be thoroughly dried before folding, matching and cutting, otherwise the pictures and texts are easy to stick.

11. Preflight components

Check beforehand to make sure all components – covers, bookposts, inserts, etc. are in place and placed correctly. Carefully check whether the pagination is correct, whether the image is aligned and whether the cropping size is wrong.

12. Correct pages

The folded book must be bundled before the pages can be matched. The common quality problems of matching pages are: inverted head, string version, string variety, more posts and fewer posts. The key to solving these problems is to strengthen the sense of responsibility of the operators, and the page assignee should be familiar with the content of the book page, and choose a few sensitive places to make eye-catching notes; Different products are stacked separately and marked separately to prevent mixing.

13. Control the milling back and grooving size

The folded book sheet must be milled on the back before it can be divided into loose pages, which is conducive to gluing. Generally, the milling back depth is 3mm, and some manufacturers will mill the back deeper in order to get superior binding quality. Generally speaking, the grooving spacing between coated paper and offset paper above 80g/m2 is 2~4mm and the groove depth is 1.5~2mm; the grooving spacing between offset paper and writing paper below 80g/m2 is 3~6mm, and the depth is 1~1.5mm. High-quantitative coated paper generally does not use the milling process for backing. Before the folding machine folds the last fold, you can use the flower wheel knife on the folding machine to roll out the small openings with an interval of 5mm along the folding seam, so as to remove the air in the book, make it flat, fold accurately, and the finished product is of the same thickness. Then, remove the back milling cutter, use only the milling groove component, and draw the back of the book into grooves with an interval of 3mm and a depth of 0.8~1mm, and then brush the glue. The book sheet after the folding machine has good glue permeability, which greatly improves the adhesive fastness of the book page.

14. Discharge the air between the tanks

Only by squeezing out the air left between the back slots can the back clip be clamped, parallel, and tight and consistent. Moreover, the force should be uniform during support to avoid bubbles and cavities.

15. Choose the right adhesive

Different adhesive materials are suitable for different papers. There are three main types of glue for wireless glue: traditional EVA hot melt adhesive, PVA white latex (cold glue) and new PUR glue. EVA glue is relatively cheap, cures quickly, and bonds firmly at room temperature, but high and low temperatures should be avoided, and coated paper above 105g/m2 should be avoided. PVA glue cures in a semi-soft state, and the resin in it penetrates into the paper to form a strong connection with the paper fibers, and the back of the book is soft, but not as strong as PUR glue. The polyurethane polymer in PUR adhesive cross-links with paper through chemical reaction with water, thereby promoting the adhesion of the pages, increasing tensile strength, enhancing its ability to withstand high and low temperatures, and reducing the waves caused by the incorrect direction of the paper filaments.

16. Carefully design die-cutting positioning

Die-cutting the printed product can increase the added value of the product and attract the reader's attention. If the operation is correct, the die cutter is exactly aligned with the die cutting line for better results. If the cover is to be die-cut, as with the back design, there should be a pre-production sample. If the first page die-cutting is to be set to the third page, the rule line should be carefully designed, and pay close attention to the operation status of the die-cutting equipment to ensure the die-cutting accuracy.

17. Cut correctly

When using a paper cutter, keep the blade sharp so as not to affect the cutting accuracy. In addition, the ambient temperature should be maintained at about 20°C and the relative humidity should be about 50%, so that the paper performance can be stable for a certain period of time, and then the cutting parameters should be determined according to its characteristics.

18. Books cannot be flipped through immediately after binding

After the book is glued into a book, the adhesive needs a certain amount of time to continue to cure, sometimes several hours. Therefore, do not flip through the book immediately after binding, but at least 15 minutes later.

19. Carefully perform product testing

Each batch of products should select pages with equal spacing from the front, middle and back of the book, use special tensile test instruments to test, divide the average tensile force of multiple tests by the total length of the book back, that is, get the tensile strength of the book page (expressed in N/cm). Industry standard requirements: After the book is glued into a book, the binding strength of the adhesive layer and the inner page of the book should be greater than the tensile strength of the paper used. Specifically, the measured value between 4.5~6.2N/cm is qualified, the measurement value is good between 6.2~7.2N/cm, and it is better than 7.2N/cm. In fact, with reference to the above points, correctly planning and executing the binding procedure, this indicator is not difficult to achieve.

20. Pack correctly

The packaging requirements are suitable for tightness. packing too loosely and easily spreading out, scratching and scratching the book; Packing too tightly can easily bend the corners of the book and scratch the cover.