Analysis of the Causes of the Rubber Binding Book Back Wild Glue and Dirty Glue

In recent years, in order to improve the binding quality of paperback books and periodicals, book printing companies have generally adopted and promoted the glue-binding process. The glue-binding process is favored by various printing and printing companies because of its short process flow, fast publication, smooth and beautiful books, stable binding quality, and high production efficiency. At present, rubber books and magazines have occupied an increasing proportion in the total number of publications.

The glue binding process is a type of paperback book binding method that uses an adhesive as a joining material to bind a booklet and make it into a booklet. The adhesive used is a hot melt adhesive that is 100% fusible polymer solids. Heating and melting to a certain temperature (generally 160 °C ~ 180 °C), to achieve the desired fluidity and adhesion, the glue through the glue wheel according to a certain thickness of the adhesive layer, brushing length, the correct starting position On the back of the back-slotted book, after being adhered to the cover, the glue-binding process is completed after the forming.

Since the perfect binding is “sticky” for “booking”, the materials used for the bonding are different types of adhesives, which are used in various parts of the booklet to run and hand over during production, especially in the hitting and forming mechanism, the book transfer belt, and the inverting transport chain board. Inadvertently, adhesives will adhere to the place. When the book is run and transported to these parts, the adhesive adhering to it will be transferred to the back of the book or the cover to form wild glue and dirty glue, and the appearance of the book will be affected. The result is that the sticky cover and the back of the book are uneven, a phenomenon that has become a common problem that affects the quality of the binding. As to the reasons for this, we believe there are mainly the following aspects.

1 caused by improper operation adjustment

1 The amount of glue is too much, the length of the glue and the starting position of the glue are unsuitable. In the fixed clamp, too much glue is squeezed into the ends of the book. Part of the glue sticks to the forming mechanism, and part of it is transferred to the output with the book. On the conveyor belt, a cycle of natural rubber and dirty rubber is formed.

2 The temperature control in the plastic pot is too high, causing the viscosity of the glue liquid to decrease and the fluidity to increase, delaying the cooling and conjunctival time of the hot melt glue.

3 The glue was not removed in a timely manner and the glue was stuck on the forming mechanism, the delivery conveyor belt, and the inverting conveyor chain board.
4 speed control (too fast) and hot melt adhesive coagulation drying time does not adapt.

2 Causes of Process Management

1 The size of the book block paper is not compatible with the size of the cover sheet. Generally, the length of the book block is long and the cover is short. When the bottom cover is formed, the glue at the short end of the cover is stuck on the forming mechanism, and the book is glued after the book is opened. Attached to the surface of the conveyor belt and the book guide plate.

2 Optional hot melt adhesives, technical indicators (mainly time parameters, viscosity index) are not compatible with the type of equipment and product structure used.

3 Equipment maintenance, adjustment is not in place, the position and accuracy of each component do not meet the requirements.

3 hot melt adhesive itself has a problem

1 Hot melt adhesives with the same type and different lot numbers have inconsistent technical performance, and sometimes even have large differences.

2 The viscosity index is too high, resulting in poor fluidity and permeability. When applied to the back of the book, drawing and dragging occur.

3 The curing and drying time is too slow, and the adhesive cannot be solidified in time after clamping and shaping.
The main reasons for the book's back wild glue and dirty glue are nothing more than the above, how to overcome and reduce this phenomenon in the whole process of product production. Let's talk about a few experiences.

1 First of all, the production efficiency of different equipment (the normal operation speed and the time required for the hot melt adhesive to brush on the back of the book to hit the molding mechanism, generally 4 to 6 seconds for the medium speed machine; 3 to 5 seconds for the low speed machine) Product structure, ambient temperature, and proper selection of hot melt adhesives that meet the requirements of various technical indicators, especially when selecting suppliers, should give priority to manufacturers with strong strength, stable product quality, and reputable manufacturers, and control the inspection of incoming goods. If there should be product certification, technical parameters, instructions and other information.

2 The operation should strictly control the technical performance of different types of hot-melt adhesives. All kinds of adhesives should be stacked and marked. When using, the hot-melt adhesives must be properly selected according to different equipment and different products. Attention should be paid to not Use glue.

3 During the production, the temperature of the glue should be controlled properly. According to the condition of the paper used for the product, the thickness of the book, and the ambient temperature, the coating temperature can be appropriately reduced or the speed can be reduced within the allowable range. Due to the fact that most gluebeater gel temperature display values ​​are inaccurate with the actual glue temperature in the glue pan (20°C, as many as 70-80°C), it cannot be based on the meter display value and can only be used as a reference. Re-purchase the temperature gauge to 300°C and insert the glue pot to monitor the actual temperature of the glue to keep the temperature stable.

4 Control the amount of glue coating, the length of brushing, the starting position of brushing (can be achieved by adjusting the scraping rubber plate, the distance between the rubber wheel and the back of the book, the rubber wheel and the rubber cam working surface, generally the distance between the rubber wheel and the book back Between 2mm ± 0.5, brushing length is about 5mm shorter than the cover).

5 Remove the molding mechanism, the conveyor belt and the glue on the turnover conveyor board in time. For ease of removal, apply a little silicone oil on these areas. Be diligent, diligent, and diligent.

6 In the process planning, try to make the length of the cover longer than the length of the book block or the book block and the cover. This is a difficult and important link, involving paper size, publishers, customers, factories, multiple departments, need to communicate in time Consultation and settlement.

(7) Air-cooling device (in the form of air pump, air compressor, air blower, fan, etc.) can be installed at the place where the molding mechanism is opened to open the book, so that the excess glue extruded from the back of the book can quickly cool the conjunctiva.

8 to strengthen the binding machine maintenance work, due to book clips, brushing mechanism, cover conveyor positioning, supporting the formation of institutions are mostly used chain drive, running a period of time after the chain, the sprocket will wear, thus affecting the transmission accuracy, These locations should be regularly checked, maintained, adjusted, and compensated to maintain their delivery accuracy.

Finally, there is a point that after the actual production of the selected hot melt adhesive meets the requirements, it is best not to change it frequently. In short, there are many factors that produce wild rubber and dirty rubber in production. Some problems are not easy to solve. When this happens, it may be necessary to analyze and find the above reasons in turn, and take active measures to solve them. (Text / Wang Shaoren)