Second, the environment and conditions of using EVA hot melt
Nowadays, there are more and more manufacturers using EVA hot-sol to process books and books, no matter large, medium and small processing plants are in use, and there will be an upward trend in the future. This is because the use of this adhesive has the advantages of fast book publishing, short cycle, good book appearance, and saving manpower and material resources. However, some manufacturers are often eager to get started, strive for more work and more processing, and ignore the suitability of the environment and conditions of using EVA hot melt adhesive, so there are many inexplicable and incomprehensible problems in processing. Based on your own experience, here are some suggestions for users to use.
1. Production plant temperature and humidity
EVA hot-melt adhesive is a hot-melt adhesive material. The opening time and curing time after application are affected by the indoor temperature and humidity. Generally, the indoor temperature (that is, the working workshop) should be kept at a constant temperature of 15 ℃ -27 ℃ time is appropriate (22 ℃ -27 ℃ abroad) / Humidity should be kept at about 50% RH. It is understood that in the units using hot melt adhesives across the country, very few can meet this requirement, so when there are hot melt adhesives in some areas, there are often bubbles in the summer, which are not easy to cure and cool, sticky tape, sticky knife, etc. ; In winter, when the temperature drops, the adhesive is often opened, the curing time is shortened, and it is not sticky or sticky. After the cover, the book is often not shaped, and the finished product cannot be cut. The occurrence of these problems is directly related to the temperature and humidity of the working plant, so the requirements are:
â‘ For the modelization of the temperature of the wireless binding processing plant, it must be paid attention to by the management personnel first.
â‘¡ Units with conditions should install constant temperature equipment and humidity instruments to ensure the normal temperature and humidity standards, especially the workshops using hot melt adhesive processing must have such equipment. This is a necessary condition for exemplary production.
③ Unconditional units should strive to create conditions and carry out education on scientific and standardized management of production. Temporarily adopt some methods when there are no conditions. For example, when the temperature is high in summer, the temperature of the hot melt adhesive can be reduced by 5 ℃ -10 ℃ to help accelerate the curing speed; when the temperature is low in winter, the temperature of the adhesive can be increased by 5 ℃ -10 ℃ , So that the opening time of the glue and curing time is slower to ensure that the expected reasonable requirements are basically met.
④ The finished books or books produced by the wireless binding process should be kept in the warehouse or factory building at a temperature between 1 ° C and 40 ° C. It is strictly forbidden to pile up against the wall, heating (cold weather), window and In the open air, to prevent the paper from being damp and deformed after heating, and the adhesive changes, causing irreparable losses.
3. Precautions for using EVA hot melt adhesive
EVA hot melt adhesive bonding material is a thermoplastic adhesive, which is very different from general cold adhesive. According to its characteristics, the following points must be grasped and noted in use:
1. To understand and master the various models and technical performance (various parameters) of EVA hot melt adhesive. Different types of hot melt adhesives have different opening, curing, cooling time, etc., and it must be distinguished due to different regions. The appropriate period of time to use summer rubber and winter rubber. When the temperature is different, the opening, curing time, etc. will also change.
2. When using EVA hot melt, avoid direct heating with an open flame (like porridge). It must be heated with an oil bath (boiling point should be 100 ° C) or a sealed electric heating plate heating device.
3. Before using the solid EVA hot-melt adhesive, it must be preheated with a preheating device to meet the standard, and then released to the glued working plastic box for use. The preheating time is generally 2 hours. Do not mix solid rubber blocks (rubber blocks without preheating) directly in the glue working rubber box during the glue application process to prevent uneven temperature of the colloid, poor fluidity, or coating the incompletely melted colloid on the back of the book. It may cause uneven coating or difficult bonding and affect the appearance of books.
4. The amount of glue in the pre-glue pot must be properly controlled and not excessive. If the dosage is too much, the colloid will melt in turn, causing its deterioration and aging, and the viscosity will be reduced, which will affect the adhesion. It may not be too small to be sufficient, which will cause the waiting for melting to affect the normal production.
5. During the opening time of the hot melt adhesive, complete the bonding process. In case of downtime, the book holder is about to be glued or the book core above the glue wheel should be taken out immediately to prevent defective products.
6. In the long-term repair stage of the wireless perfect binding machine, the pre-glue pot and working glue box should be closed to stop the colloid wheel melting and deterioration.
7. The temperature of the hot-melt colloid should be strictly controlled within the scope of use, and the temperature of the glue used cannot be arbitrarily changed. In special cases, the maximum tolerance is ± 10 ℃.
8. The pre-glue pot and working plastic box should be cleaned regularly to ensure the cleaning in the glue pot (box) and the cleanness of the pot glue (box) to prevent the precipitation and accumulation of impurities in the glue liquid and affect the accuracy of temperature control. It may even cause the thermostat to malfunction and cause the colloid to burn. Under normal normal production and operation conditions, the preheated plastic pot should be cleaned every three months; the working plastic box should be cleaned once every half a month to ensure the smooth processing and prevent the carbonization of smoke, pulverization and fire. To clean up the glue pot, a system must be set up, checked on time, and carefully implemented.
4. Analysis of common quality problems of wireless perfect binding
Common quality problems of wireless perfect binding mainly include page falling, uneven back of the book, broken book core after the package, blistering, and perforations at both ends of the back of the book, etc., which often occur on the stand-alone or linkage line. The reasons are mainly caused by
1. Analysis of the reason for page dropping
â‘ The milling groove is too shallow and narrow, and the glue liquid has not penetrated;
â‘¡ When folding, the crease runs away, the innermost page is not milled through;
â‘¢ The stickers are not neatly organized;
â‘£The paper wool or paper scraps are not removed, blocking the milling through;
⑤ The paper is unstable or there is no difference. The book version is also different from the glue used for coated paper;
â‘¥ Improper use of glue, such as fluid, temperature control or poor quality of glue, etc .;
⑦ After the adhesive is pulled out from the edge of the book holder and the back pages;
⑧The temperature and humidity errors in the working room are too large.
2. Analysis of the causes of uneven book back
â‘´ The back of the book itself is uneven and has unevenness;
⑵ Improper adjustment of the support board;
⑶The adhesive layer is too thick;
â‘·The design of the writing board is unreasonable, and the books are not set down and hit, etc .;
⑸ The clamping work was not completed within the opening time;
3. Analysis of the cause of the broken book core after the schoolbag
â‘ The coating is uneven (round);
â‘¡The back of the milling cutter is not parallel (circle);
â‘¢ Adhesive is aging or the adhesive temperature is too high;
â‘£ Improper use of glue (such as pursuing low prices and too much rosin in the glue), the quality of the glue does not match the paper quality of the books and periodicals processed;
⑤The cover paper is too thick and the book core paper is too thin and soft. The cover and the book core paper are very different. The mutual pulling force is unequal, causing the front and back pages to break and leak glue.
4. Bubble analysis
â‘ Improper height adjustment of rubber roller or rubber roller;
â‘¡ Improper height of the supporting table;
â‘¢ The glue temperature is too high or the glue quality is not good;
â‘£ The cover sticking time is a little late, and it is not completed within the opening time, causing the sagging of the stalactite makeup, such as bubbles.
5. Analysis of the reasons for the holes in the back of the book
â‘ The thickness of the back of the book is inconsistent up and down, causing the book clips to be not parallel to the book and the glue is uneven;
â‘¡ The rubber wheel is improperly adjusted, and it has a stalactite shape after being glued, which cannot be controlled and filled with book back glue liquid;
â‘¢ The glue roller is not in contact with the back layer of the book;
â‘£ The glue roller adjustment is unreasonable;
⑤ The slope of the lower book board is too large, and the lower books are not parallel (joint).
6. Analysis of the cause of overflowing rubber wire drawing and dirty belt
â‘ There is no glue breaking device for the glue part of the wireless glue nail machine;
â‘¡ The length of the cover is less than the length of the book block, causing glue leakage at both ends;
â‘¢ The amount of glue applied is too thick.
7. Analysis of the causes of smoke and burning of hot melt adhesive
â‘ The glue liquid is heated and melted in turns in the glue pot for a long time;
â‘¡ Thermostat failure;
â‘¢ The glue pot has not been cleaned within the prescribed time;
â‘£ Carbonization and pulverization of hot melt adhesive become flammable.
Fifth, how to open the wireless perfect binding equipment
At present, the wireless binding technology has been popularized throughout the country. The number of wireless binding equipment is unprecedented, and the processing volume accounts for the first place in various other installation methods. However, we have paid less attention to how to successfully open this equipment and how to cooperate with the previous process, so there are often problems that should not occur. So how to open the wireless binding equipment to ensure the stability and reliability of product quality?
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