Proper use of EVA hot melt adhesive, open the perfect binding machine and analysis of common problems (two)
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Second, the environment and conditions of using EVA hot melt
Nowadays, there are more and more manufacturers using EVA hot melt for processing books, etc. No matter how large, medium or small processing plants are used, there is still an upward trend in the future. This is because the use of this adhesive has the advantages of fast book release, short cycle, good book appearance, and saving manpower and material resources. However, some manufacturers are often eager to launch, and strive to do more work, more processing, and neglect the suitability of the use of EVA hot melt adhesive environment and conditions, so there are many problems in the processing that are incomprehensible and difficult to understand. Here are some suggestions based on your own experience for the reference of the unit.
1. Production plant temperature and humidity
EVA hot melt adhesive is a kind of hot melt adhesive bonding material. The opening time and curing time after application are affected by indoor temperature and humidity. Generally, the temperature in indoor (ie working workshop) should be kept at a constant temperature of 15 ° C-27 °C time is appropriate (foreign requirements 22 ° C-27 ° C) / humidity should be maintained at around 50% RH. It is understood that in the use of hot melt adhesives in the country, there are very few such requirements. Therefore, in some areas, there are hot melt adhesives. In summer, there are often bubbles in the glue, which are difficult to cure and cool, sticky tapes, sticky knives, etc. When the temperature in winter drops, the adhesive is often opened, the curing time is shortened, the sticking is not strong or the sticking is not good, and the book is often indeterminate after the cover, and the finished product cannot be cut. The occurrence of these problems is directly related to the temperature and humidity of the work plant, so it is required:
1 For the modeling of the temperature of the wireless binding processing plant, it must first be taken care of by the management personnel.
2 Conditional units should install thermostats and humidity instruments to ensure normal temperature and humidity standards, especially in workshops that use hot melt adhesives. This is a must for exemplary production.
3 Unconditional units must strive to create conditions and educate students in scientific and standardized management. Temporarily adopt some methods when there is no condition. For example, when the temperature is high in summer, the temperature of hot melt adhesive can be lowered by 5°C-10°C to help accelerate the curing speed; when the temperature is low in winter, the temperature of the glue can be increased by 5°C-10°C. Therefore, the glue opening and curing time is slower to ensure that the expected reasonable requirements are basically met.
4 The finished book or book, which is processed by wireless binding, should be kept at a temperature between 1 °C and 40 °C in the warehouse or factory. It is strictly forbidden to accumulate on the wall for a long time, rely on heating (cold weather), by the window and In the open air, in case the paper is damp and deformed after being heated, the adhesive changes, resulting in irreparable damage.
Third, the use of EVA hot melt adhesive precautions
EVA hot melt adhesive material is a kind of thermoplastic glue, which is very different from ordinary cold glue. According to its characteristics, the following points must be grasped and paid attention to during use:
1. To understand and master the various models and technical performance (each parameter) of EVA hot melt adhesive. Different types of hot melt adhesives have different opening, solidification, and cooling time. It is also necessary to distinguish the appropriate period of use of summer rubber and winter glue due to different regions. When the temperature is different, the opening and curing time will also change.
2, use EVA hot melt to avoid direct fire (like porridge) directly heated, must be heated with a spacer oil bath (boiling point should be 100 ° C) or with a sealed electric heating plate heating device.
3. The solid EVA hot melt adhesive must be preheated to the standard before use, and then released to the glued working plastic box. The preheating time is generally 2 hours. During the glue process, the solid rubber block (the pre-heated rubber block) should not be directly mixed into the rubberized work box to prevent the gel temperature from being uneven, the fluidity is not good, or the gel which is not completely melted is applied on the back of the book. It causes uneven coating or difficult bonding and affects the appearance quality of the book.
4, the amount of glue in the pre-molding pot should be properly controlled, not too much. Excessive use can not be used, the colloids melted, causing deterioration and aging, viscosity reduction, affecting adhesion; can not be added too little and not enough, causing waiting for melting to affect normal production.
5. During the opening time of the hot melt adhesive, complete the bonding process. In case of downtime, the book holder is to be glued or removed immediately in the book core above the rubberizing wheel to prevent the occurrence of defective products.
6. In the long-term repair stage of the wireless perfect binding machine, the pre-molding pot and the working plastic box should be closed to stop the colloidal wheel melting and not deteriorate.
7. The temperature of the hot melt colloid should be strictly controlled within the scope of use. The temperature of the glue should not be arbitrarily changed. In special cases, the maximum tolerance is ±10 °C.
8. The pre-molding pot and the working plastic box should be cleaned regularly to ensure the cleaning in the plastic pot (box), to ensure the cleaning inside the pot glue (box), to prevent the precipitation and accumulation of impurities in the glue liquid and affect the accuracy of temperature control. Even the malfunction of the thermostat causes the phenomenon of colloidal combustion to occur. In the normal normal production operation, the preheating rubber pot should be cleaned every three months; the working plastic box should be cleaned once every half month to ensure smooth processing and prevent carbonization, smoke and powder fire. It is necessary to set up a system for cleaning the rubber pot, check it on time, and implement it carefully.
Fourth, the analysis of common quality problems of wireless binding
Common quality problems of wireless binding are mainly dropped pages, uneven backs, broken book cores, foaming, and perforations at both ends of the book. They are often found on single or linked lines, which are mainly caused by the following reasons:
1, the reason for the page drop analysis
1 The milling groove is too shallow and narrow, and the glue does not penetrate;
2 When the folds, the creases are emptied, and the innermost pages are not milled;
3 book stickers are not neatly arranged;
4 paper or paper scraps are not removed, blocked and milled;
5 paper is unstable or there is no difference between the book version and the glue used for the copper paper;
6 improper use of glue, such as fluid, temperature control or poor quality of glue;
7 The edge of the book clip has the adhesive pulled off and the back sheet;
8 The temperature and humidity errors in the working room are too large.
2. Analysis of the reasons for the unevenness of the book
(1) The back of the book itself is not flush and has unevenness;
(2) improper adjustment of the book board;
(3) the glue layer is too thick;
(4) The design of the writing board is unreasonable, and the book is not set to fall and is hit;
(5) The clamping work was not completed within the opening time;
3. Analysis of the reasons for the break of the book core after the schoolbag
1 uneven coating (circle);
2 milling cutter milling back is not parallel (circle);
3 adhesive aging or rubber temperature is too high;
4 improper use of glue (such as the pursuit of low prices, excessive rosin in the rubber), the glue does not match the processed paper;
5 The cover paper is too thick and hard, the book core paper is too thin, the cover and the book paper are thick and thick, and the mutual tension is not the same, causing the front and back pages to break.
4. Analysis of the cause of bubbles
1 The height of the rubber roller or the rubber roller is improperly adjusted;
2 The height of the book holder is improper;
3 The glue temperature is too high or the gel is not good;
4 The sticky cover time is slightly later, not completed within the opening time, causing the drooping after the glue is applied, and the creamy cream of the glue appears, such as a bubble.
5. Analysis of the reasons for the perforation at the back of the book
1 The thickness of the back of the book is inconsistent, resulting in the book is not parallel, and the glue is uneven;
2 The rubber wheel is improperly adjusted, and there is a stalactite shape after the glue is applied, which cannot be controlled and stuffed with the book back glue;
3 The rubber roller is not in contact with the back layer of the book;
4 The adjustment of the rubber roller is unreasonable;
5 The bookboard slope is too large, and the book is not parallel (joint).
6. Analysis of the cause of drawing and dirty tape
1 There is no glue breaking device in the rubberized part of the wireless nailing machine;
2 The length of the cover is less than the length of the book core, causing the glue to leak at both ends;
3 The amount of glue applied is too thick.
7. Analysis of the causes of smoke and burning of hot melt adhesive
1 The glue is heated and melted in the rubber pot for a long time;
2 The thermostat fails;
3 The rubber pan is not cleaned up according to the specified time;
4 The hot melt adhesive is charred and pulverized into flammable materials.
5. How to smoothly open the perfect binding equipment
At present, the wireless binding technology has been popularized all over the country. The number of wireless plastic nailing equipment is unprecedented, and the processing volume accounts for the first place in various other installation methods. However, how to smoothly open this kind of equipment, and how to cooperate with the previous process, but pay less attention to it, so there are often problems that should not occur.