Keywords: EVA hot melt adhesive bonder open time curing time cooling hardening time signature page matching machine how to properly use EVA hot melt adhesive, open a good binder, is currently a very important issue in China's printing and binding professional . It is related to the product quality and social impact of the books in our country and the benefits of the factories. For how to use EVA hot melt adhesive properly, open a good equipment for binding, and ensure that the product quality meets the standard requirements. Let me talk about your opinions.
First, EVA hot-melt adhesives and the use of EVA hot-melt adhesives is the most widely used adhesive binding material in China and even the world. The reason why it is used the most is that it has many advantages, and the wireless glue binding process adapts to the needs of the modern society, that is, shorten the cycle, and produce books quickly. The following is a brief introduction to EVA hot melt adhesives and their use for your reference.
1. What is EVA Hot Melt Adhesive EVA hot melt adhesive is a 100% solids fusible polymer that requires no solvent and no moisture. It is a solid at room temperature, heated and melted to a certain degree and can flow, becoming a viscous liquid, ie, an adhesive body. The melted EVA hot melt adhesive is a light brown translucent or semi-white adhesive.
The composition of the EVA hot melt adhesive consists of a basic resin, a tackifier, a viscosity modifier, an antioxidant, a heat-resistant or cold-resistant agent. The basic resin is made of ethylene-vinyl acetate after high temperature and high pressure copolymerization.
2. Characteristics of EVA Hot Melt Adhesive The reason why EVA hot melt adhesive is selected by the majority of users, and the amount is gradually increasing, it is because it has the following characteristics:
1 It is usually a solid at room temperature. When it is heated to a certain degree, it melts into a liquid state. Once it cools below the melting point, it quickly becomes a solid (ie, hardens), and is easy to store and store.
2EVA hot melt adhesive is fast curing, low pollution and strong adhesion; the adhesive layer has certain flexibility and certain hardness, which is very suitable for bonding books and other uses.
3 there is again sticky. When the glue is applied to the adherend (back or sticky mouth), the colloid is solidified or hardened, it can be heated to soften or gel, and then re-bonded, which can reduce the waste and loss caused by sticking.
4 easy to use. When used, the plastic block is put into the reservoir for proper preheating, melted into the desired temperature and liquid adhesive, and smeared on the adherend, after being neatly pressed and shaped, it can be completed in a few seconds. Bonding and solidification can be achieved in three minutes or so by hardening, drying, and drying.
3. Use of EVA Hot Melt Adhesives EVA hot melt adhesives that are currently produced and used are suitable for bookbinding applications and are generally classified into high-speed adhesives and low-speed adhesives. High-speed glue curing speed is slightly faster, low-speed glue curing speed is slightly slower. According to the difference in the materials to be glued, it can be divided into glue for offset paper and glue for coated paper; and it can be divided into back glue and side glue (ie glue for book back and glue for side glue) to adapt to the strength and need of adherend. , to achieve a good bonding effect.
Use EVA hot melt adhesive to do a good job before use, such as storage rubber, pre-adhesive, adjust the glue temperature and so on.
1 storage rubber storage glue material according to the speed of the device and the material to be glued to choose the type and type of glue. The amount of glue to be stored should be added according to the amount of processing as appropriate. It must not be caused by excessive amounts of glue, colloidal heating, or premature aging. It is also not possible to add too little and cause the amount of glue to be insufficient to cause shutdown and wait for the melting time.
2 Preheat EVA hot melt adhesive must be preheated and melted before use; the rubber block that has not been preheated can not be put into the working glue pot and used with melting. There are two ways to warm up. One type of preheating with oil is preheating with a jacketed pot; the other is preheating with a hot plate, which is a method of directly preheating with a hot plate device in a preheated pot. The preheating time is generally 2 hours. After the colloid reaches the required heating temperature, has good fluidity, and passes the preheating, it is released through a constant temperature pipe to 160-200°C (or 130-170°C). Work glue pot, for glue binding book this book use.
3 books This book paper and glue temperature EVA hot melt adhesive in the use of temperature control is very strict. The type and texture of the paper used to produce the book are different. Therefore, the requirements for the type and model of the glue are different, and the temperature requirements for the glue are also different. This is not only the reason for the different paper fibers, but more importantly the difference in the thermal conductivity of the colloids produced by different paper and the change in the cooling rate. Taking the thermal conductivity of coated paper and book paper as an example, the former cools the glue faster than the latter because the inorganic content contained in the coated paper is about 10 times higher than that of book paper, newsprint paper, etc. With good thermal conductivity, it can make hot melt faster.
If the sizing temperature is also 170 °C, the hot-melt adhesive's tensile strength, the version of the paper can reach 8.83N/cm, and the coated paper, such as coated paper, can only reach 1.86N/cm (65-70g). /m2) and 1.46 N/cm (100 g/m2). The low pull value of coated paper is obviously not ideal. Therefore, increasing the temperature of the sizing and increasing the strength of the glue, that is, the temperature of the EVA hot-melt adhesive varies depending on the texture of the book.
The opening time of the 4EVA hot melt adhesive and the operating speed of the production equipment are fixed in the processing. The use of EVA hot melt adhesive must be strictly controlled for three times.
The first is the opening hours. Refers to the time the glue is applied to the back of the book. The opening time is usually 7 to 13 seconds. This time is the work that the binder machine carries behind the milling to the glued and fixed end of the cover and the back of the book from the start of glueing. That is, it must be within 13 seconds. To complete these tasks, the use of hot melt adhesive can get a good bonding effect. If the book is not glued and fixed within the prescribed time, there will be tackiness, stickiness, page drop, and inequality.
Followed by the curing time. EVA hot melt curing time and opening time are basically the same, usually 7 to 14 seconds. In other words, more than 14 seconds, the cover and the back of the book can not be bonded. Because the surface of the glue is cured at this time, there is no adhesive ability and the book cannot be fixed.
The last is the cooling hardening time, also called the drying time. In addition to the requirements of open time and curing time, the cooling hardening time after curing is required to be fast and basically accurate. In particular, glue is used on the linkage production line because the operation of each part of the linkage production line is consistent with the beat of certain movements. The time required for the book to be placed on the front cover of the package to be sent to the book-cutting site must be guaranteed, and there must be certain rules in order to achieve the desired effect after the book is cut. That is, the time of delivery of the book is to ensure that when the book reaches the part of the stapler, the glue liquid on the back of the book is cooled, hardened and dried, so that the quality of the finished product can be guaranteed. This time should be about 3 minutes, less than this time will result in knife, book back deformation, broken head, dimensional instability and other phenomena when cutting. Therefore, the length of the conveyor belt of the book delivery device of the linkage line should be selected according to the speed of the device. There are two common types of conveyors. One is the length of the conveyor belt for cooling. The size of the conveyor is generally about 50m. The other method is to use the method of stacking in the conveyor to make the books run slowly after being stacked, and the transfer time is extended. This can reduce the length and floor area of the conveyor belt, and its length specification is generally about 20m.
4. The Environment and Conditions of Using EVA Hot Melt Adhesive for Wireless Adhesives Nowadays, more and more wireless adhesive bonding processes are being performed using EVA hot melt adhesives. No matter whether large, medium or small processing plants are used in the country, they will increase in the future. the trend of. But often due to eager to launch, the use of EVA hot melt adhesive manufacturers ignore the environment and the scientific nature of the conditions, especially the lack of knowledge in the management of this area, so there are many problems in the processing and can not be solved. East strange West. Here are some points to remind you about:
1 The temperature and humidity of the production plant EVA hot melt adhesive is a hot melt adhesive. The open time after painting is controlled by the room temperature; and the curing time and cooling hardening time are controlled by the indoor temperature and humidity, so the change of temperature and humidity has a direct impact on the binding quality of the wireless glue binding. According to China's current conditions and use conditions, the indoor temperature should generally be maintained between 19 ~ 29 °C is appropriate (very strict requirements of foreign countries, controlled at 22 ~ 27 °C); humidity should be maintained at about 50%. (To be continued)
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