What should I do if the pages of a perfect-bound book fall out? It turns out I overlooked this detail.
As a common binding method, perfect binding is not uncommon, but in daily life, we also often encounter problems such as loose pages or pages falling out after perfect binding, which greatly affect the reader's experience. So how exactly do printing companies operate during the perfect binding process to avoid these issues? Let's take a look!01Hollow SpineA hollow spine greatly affects the appearance of a book and can seriously lead to pages loosening or falling out. The causes of a hollow spine may be due to serious issues with the hot melt glue itself, such as impurities in the hot glue causing bubbles during melting; it could also be due to insufficient glue application or uneven glue distribution, poor contact between the glue roller surface and the book block, or misalignment of the glue roller. Additionally, if the scraping rubber contacts the book block too tightly or is too hard, it can scrape off the applied glue, resulting in a hollow spine.
Solutions are as follows:(1) Choose high-quality hot melt adhesive, and conduct a small batch trial before making a final decision;(2) Adjust the machine so that the surface of the glue roller makes proper contact with the book block. First, loosen the connecting rod nut, raise the height of the glue plate, then loosen the glue plate fixing nut to ensure the book block is parallel to the glue roller surface and in good contact;(3) Adjust the distance between the rubber and the book block so that the rubber does not press too tightly against the book block, or soften the rubber accordingly.02Glue SeparationGlue separation refers to the poor adhesion between the cover and the glued edge of the book block. Specifically, it may manifest as the front side or back side edge glue detaching, detachment of glue on both sides, or partial glue detachment. In severe cases, it can cause separation of the cover from the book block, affecting the reader's use.
If a small number of books show side glue peeling, it may be due to excessive stoppages during equipment operation, the cover not being bonded in time within the open period of the glue, or inconsistent thickness in the batch of books, causing poor contact of the thin side glue.The solutions are as follows:(1) Minimize stoppages during normal equipment operation;(2) Removed books can be reheated and pressed using a hot press method to become qualified products, without needing to tear the covers and discard them;(3) After folding, the pages should be clamped and pressed to reduce air inside the booklets, ensuring the batch thickness is basically consistent.If a batch of books shows side glue peeling, the reasons may include: first, improper adjustment of the distance between the side glue rollers, leading to poor contact with the spine of the book block; second, incorrect selection of the side glue type; third, side glue temperature not set according to technical parameters; fourth, the clamping distance being too large when clamping the book block.The solutions are as follows:(1) Choose the type and model of adhesive correctly according to the paper;(2) Adjust the distance between side glue rollers according to the actual thickness of the book block to ensure uniform, stable, and appropriate gluing;(3) When using glue, strictly follow the technical parameters for the specific type and model; do not arbitrarily change usage data;(4) Correctly adjust the distance of the clamping blocks according to the actual thickness of the book, ensuring it is neither too large nor too small.03Falling Pages / Loose PagesSome perfect binding machines may have individual pages fall out when flipping through the book. The main reasons are: first, the book block was not properly milled on the spine or glue was not applied during trimming; second, the inserted paper does not match the original book block, especially when inserting single coated paper pages into a book block made of regular paper, making page loss more likely; third, paper scraps or dust not cleaned properly can block the grooves, preventing glue from penetrating; fourth, improper choice of adhesive type, substandard adhesive quality, or incorrect usage temperature.
Solutions are as follows:(1) Increase the depth of milling the spine and the slotting, and at the same time change the ordinary glue to copperplate glue, so that the adhesive can penetrate to the innermost pages.(2) Adjust the folding paper feed roller pressure, parallelism, and vertical alignment with the gauge to ensure that the pages are correctly fed into place, achieving tight folds without gaps.(3) Increase the vibration of the vibrator to properly align loose-leaf booklets;(4) Clean the equipment regularly to ensure the milling spine device is clean, allowing smooth production.(5) Select the correct type and model of adhesive according to the usage standards of hot melt glue and the type of paper used.04Exposed Glue BaseOpening the first and second pages of a perfect-bound book, sometimes you can see the hot melt glue in the spine groove, commonly referred to as "exposed glue base," which affects the book's appearance and usability. The main causes for this phenomenon are as follows: first, the cover paper is too hard and thick while the book block paper is too thin and soft, with a significant difference in strength and tensile force, causing the pages to break apart; second, the pressure for creating the fold crease is too light, failing to form the proper crease; third, the selected type and model of adhesive is inappropriate or the adhesive quality is poor; fourth, the adhesive has aged or deteriorated, or the glue temperature is incorrectly adjusted.
The solutions are as follows:(1) Choose adhesives that meet the standards and are suitable in type and model according to different types of paper, and check the technical parameters of the adhesive according to the standards;(2) Clean the glue pot regularly, ensure the glue quantity is reasonable, and avoid repeatedly melting the glue for a long time;(3) When using different types and qualities of paper within the same book, select the type and model of adhesive based on the best quality paper, and do not mix adhesives of different models;(4) When the cover and the book block have significant differences in paper type, thickness, or weight, the process design should include additional endpapers to transition the tension between them;(5) When the cover paper is thick and stiff, make the cover crease (side glue flipping crease) as deep as possible without leaving marks or cracking the paper.05The book block is not centeredThe binding edge refers to the finished product's binding side, and the binding edge width refers to the distance from the text area to the binding edge of the finished product. Some people believe that adhesive-bound books do not have a binding edge, which can result in a book where the book block is not centered on the page. In actual practice, especially in books with flyleaf title pages, this issue is particularly noticeable.This is mainly because adhesive-bound books cannot be opened to the spine like thread-sewn books. For flat and glued binding, a certain width must be accounted for during binding, and the binding edge width should be slightly wider than the cut width. The depth of the groove for flat glued books is generally 1.0–1.2 mm. Some printing companies have concluded from practice that when the binding edge is about 3 mm, the book block is perfectly centered, which also basically meets the standard sizes for milling and grooving.