Green bonding material of PUR rubber book
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PUR adhesive material is another new type of bonding material after EVA hot melt adhesive. It is called: one-component wet-initiating polyurethane hot melt adhesive. It is a reactive prepolymer with chemical bonding. When the adhesive is opened, it is in contact with the moisture of the air or the substrate, and a bonding material which rapidly undergoes polymerization crosslinking reaction in an instant (or for a certain period of time).
There are several types of PUR glue types, and the book used in the book is hot-melt. PUR adhesive is a new type of bonding material used in the world in the past few years. It has been used in China and is gradually becoming popular. In recent years, we have become more and more aware of this material, and found that the effect obtained after bonding is far superior to that of EVA hot melt adhesive, and the price is not uneconomical.
The following are the characteristics of PUR glue, cost calculation, equipment modification and use:
First. A PUR glue features
1 Low carbon energy saving and environmental protection
At present, the most bonding material used in China's bonded books is EVA hot melt adhesive, which is used at about 17,000 tons per year. EVA hot melt adhesive resin is mainly made of petroleum and plant rosin, which consumes a lot of resources (not meeting low carbon requirements). ), EVA glue will also emit a small amount of odor during processing. As for PUR glue, it does not contain plant rosin, contains only a very small amount of petroleum components (compared to EVA), and is made of resin. When it is melted, it uses all sealing devices. The power consumption for heating is lower than that of EVA hot melt adhesive. Therefore, it is more environmentally friendly. If PUR glue is used instead of the lock line (or partially replaced), it can save the energy of the lock machine, reduce the waste of process and processing costs, and shorten the processing cycle.
The preheating temperature of PUR glue is about 130 °C, the preheating time is about 15 minutes, and the temperature of EVA hot melt adhesive is 150 °C-180 °C, and the preheating time is more than 2 hours. Therefore, PUR glue is used for lower carbon environmental protection.
2 good temperature resistance
The high temperature resistance of EVA hot melt adhesives is generally around 80 °C (some are only about 60 °C). When the temperature in the southern region is high, the colloid is not hard to be hardened after application, and the finished product cannot be cut, or the back of the book is wrinkled, broken, deformed, scattered, and the like. In the northern region, the temperature is low, and the adhesive will not harden in advance after being coated with the adhesive, or the book will break loose due to the change of the rosin in the rubber, which seriously affects the quality.
It is made of PUR adhesive bonded book, which is resistant to high temperature and low temperature. It can withstand temperatures ranging from -40 ° C to 140 ° C. It is not affected by temperature and humidity. It can also be used in workshops in China and without constant temperature and humidity devices. . This adhesive does not require processing, storage, packaging, transportation and reading environment changes will not affect the book's adhesion fastness; however, EVA hot melt adhesives are generally only between 0 ° C and 60 ° C. There is no bonding material that binds the book, and its moisture resistance is compared with that of PUR.
3 Good safety and reliability
When the PUR glue is preheated in the preheating rubber drum, it is fully enclosed partial preheating (all preheating is used when the film is coated). When the barrel is replaced with a new one after the adhesive is used, no surplus will be generated. Unsafe hidden dangers caused by aging, carbonization, etc., and tasteless and non-toxic. The preheating rubber cooker of EVA hot melt adhesive is used for a long time and stored by itself. If the material is not stored according to the rules or does not imply the cleanup of the surplus, the excessive amount of storage, repeated melting, etc., will cause the edge of the plastic pot. The rubber is aging and carbonized, and there is a smoke phenomenon. When it is serious, the colloid will be powdered and become a flammable material to form a fire (both examples at home and abroad).
4 The book is sticky and easy to read.
Because PUR rubber rubber has excellent performance and good flexibility, books are easy to flatten when reading, and are not affected by the thickness and hardness of paper and books. The book of EVA hot-melt adhesive can not be comfortably flattened, and the handwriting and the picture between the cores cannot be read. This is the disadvantage caused by rosin in EVA hot melt adhesive.
Second, use PUR glue economic cost accounting
Many publishers and processing units believe that PUR adhesives are easy to use, but they are costly, and they need to invest hundreds of thousands of yuan when renovating equipment. They are reluctant to use such environmentally friendly materials. Nowadays, China has been able to make PUR glue and glue coating equipment that meets international standards, and the price is also cheap. Imported PUR and glue coating equipment have also been reduced. The price comparison between EVA hot melt adhesive and PUR adhesive is now calculated as follows:
1 glue price cost comparison
The current maximum consumption of EVA hot melt adhesive is about 25,000 yuan per ton, PUR glue is about 100,000 yuan per ton (imported 130,000 yuan, domestically produced 75,000 yuan), after use, the comparison is:
(1) EVA Hot-melt adhesive coating (for example, the thickness of the adhesive backing) is usually 1.2±0.2mm thick after drying. The ton of glue can be received for about 5,500 orders per ton of glue. The price of each ton of paper is 3.5 yuan. Excluding the waste caused by high-priced glue and surplus).
(2) The thickness of the glue layer after drying of PUR glue (back glue) is only about 0.4mm, only one-third of EVA glue, and between 15,000 and 17,000 orders per ton of glue can be bonded to each other. There are two kinds of paper prices: 6.5 to 7 yuan for imported rubber and 305 yuan for domestic glue. The average price of two kinds of glue (import and domestic) is 5 to 6 yuan. In addition, the price of domestic glue used for bonding textbooks is only ton. 55,000 yuan, which is only 2.8 to 3 yuan per revolution.
2 Process cost comparison
(1) Some lock wire flat and hardcover can be made of PUR glue, which has the effect of firm and reliable bonding. Its firmness and shelf life can reduce the cumbersome and troublesome process of waste-by-bond line compared with chemical fiber line, and save The sewing machine and the energy used, and speed up the book.
(2) Proper use of PUR adhesive bonding books and magazines can make the book binding, without loose pages, falling pages, breaks, etc., improve product quality, avoid complaints from customers and users, improve corporate reputation, and expand the scope of living.
(3) If you encounter different paper and different thickness books when using PUR glue, you do not need to change the type of glue (EVA does not have this advantage, or you should use high-priced glue), omitting the time of changing glue or changing glue The trouble caused by improper.
Three. transformation and investment in the use of PUR glue on the binding equipment
To switch to PUR glue binding equipment, there are two main points that need to be modified:
1 Modification of pre-glue and glue applicator
The pre-adhesive device of PUR glue is used for the glue barrel and the glue of the device. The pre-adhesive barrel is fully enclosed when used, and is packed and stored by the rubber factory. Different specifications are selected according to the dosage. In the sol, it is divided into two forms according to the amount of the required process. One is to use a large amount of glue when the film is coated (the amount of one time is large), and the way in which the colloid in the barrel is completely melted can be used; the other is in the processing of books and periodicals. In this book, when the rubber area is small (small amount of rubber is used in a single time), the column type local melting method can be adopted. There are two kinds of gluing methods: one is roller type, which is basically the same as EVA glue; the other is nozzle type, which is sprayed on the back of the book according to the length of the book and the width of the book back, but the spraying speed is slow. .
2 Transformation of the milling back
The most used EVA hot melt adhesive on the equipment is the milling back "slot", and the PUR glue is the "raw" of the milling back. The rake cutter of the milling back device is removed, replaced with a pulling device, and the book back is replaced with hair. Just install it. Because the PUR glue fluid is fast and the adhesion is very strong, it is not necessary to infiltrate too much glue into the 1.5mm groove, and the amount of glue that binds the strength of the book can be achieved.
Use PUR glue as long as it is on the binding machine of the existing equipment (except the disc and the long machine), whether it is a single machine, a linkage production line or other different types of machines, as long as the pre-adhesive, rubberized and napped can be modified. .
As for the price of the retrofit assembly, the import price (US Nordson products) is about 550,000 yuan per unit, and the domestic price is only about 270,000 yuan. If you use PUR glue, the investment office is here, you can benefit from one investment, which can increase the source of life, ensure quality, and be environmentally friendly.
Fourth. Use PUR adhesive bonding book to prepare for processing
If you use PUR glue processing, preparation before processing is an important factor to ensure quality, so make the following preparations:
1 pre-glue requirements
(1) Pre-adhesive barrel specifications should be appropriately selected according to the amount of processing book
(2) The pre-glue time is generally about 15 minutes, and the pre-glue and glue temperature is generally between 110 ° C and 120 ° C.
2 Gluing requirements
(1) The length of the glue is based on the length of the manual, and the glue should be left in the gap.
(2) The nozzle type (suitable for medium and low speed machines) is based on the width of the book back; the roll type (suitable for high speed machine) is basically the same as the EVA.
(3) The amount of glue applied is generally about 0.9mm.
3 requirements for signatures
(1) The folded posts should be tied and leveled, and the air in the signatures should be excluded as much as possible to ensure the smooth processing of the binding.
(2) The storage should be accurate and tidy, with appropriate height and no leakage, so as to ensure that the product is not stopped due to storage.
4 Start-up requirements and coordination with the whole line or the whole machine
(1) Correctly grasp the use temperature, opening and curing time of the glue.
(2) No downtime or minimal downtime to ensure the firmness of bonding. If it is stopped, the book that has not been glued to the cover will be removed.
(3) The conveyor belt should be lengthened when processing the joint production line, and a drying device should be added above the conveyor to ensure the ideal curing of the PUR glue and the smoothness of the finished product.
(4) Stand-alone operation should ensure that the book after the package is flat and not deformed
Five PUR adhesive usage
The use of PUR abroad has been nearly 10 years old, and the amount of use has gradually increased. In the amount of bonded books and magazines, the amount has reached 60%, and will increase in the future. In Brazil, for example, PUR glue textbooks have been used, and 200 million copies of PUR glue are used each year. China has also used PUR adhesive bonding books for more than 4 years, mainly for processing orders in Guangdong. In the near future, the use of single orders has also begun, the number has gradually increased, and the scope of use has also expanded.
Since PUR glue has just begun to be produced and used in China, with little experience, it has not fully grasped the best rules of production and use, such as curing time and speed of use. These problems need further exploration and improvement.
Last year, the National Printing Standards Committee held a meeting on the use of PUR adhesives in Shanghai on August 29, 2010 in order to better use the new low-carbon and environmentally-friendly bonding materials in line with the green printing proposed by the Press and Publication Administration. Established a national industry standard writing group discussion meeting on "PUR-type hot-melt adhesive requirements and testing methods for bookbinding". The development of PUR adhesive use standards is a great boost to the use of new environmentally friendly materials in the printing industry and the early realization of green printing. It also lays an important foundation for China to develop international postpress standards.