Comparison of PUR hot melt adhesive and EVA hot melt adhesive
Compared with EVA hot melt adhesive, PUR hot melt adhesive has less adhesive coating amount. Although the adhesive coating amount is less, the strength is not reduced but increased. PUR hot melt adhesive is much softer than EVA hot melt adhesive, so books and periodicals are very smooth and can be spread out well without hand pressure when reading. The smoothness of the book improves the reader's reading comfort.
PUR hot melt adhesiveCompared with EVA hot melt adhesive, the amount of back glue is less, although the amount of glue is less, but the strength is not reduced but increased. PUR hot melt adhesive is much softer than EVA hot melt adhesive, so books and periodicals are very smooth and can be spread out well without hand pressure when reading. The smoothness of the book improves the reader's reading comfort.
PUR hot melt adhesive binding books on the environment adaptability, especially high temperature, low temperature resistance. We can prove this with experiments. The temperature adaptability of rubber hardcover books in winter was simulated. Put the two books packed with PUR hot melt adhesive and EVA glue into the freezer compartment of the refrigerator at the same time, set the temperature at minus 20 degrees, and place them for 12 hours. After 12 hours, take out the two books from the refrigerator, open the pages, and the pages packed with EVA hot melt adhesive will make a brittle sound. The pages have been pasted and degummed, while the pages packed with PUR hot melt adhesive are still intact. The high temperature durability of PUR hot melt adhesives can be tested under hot environmental conditions.
Hot melt adhesive binding and EVA hot melt adhesive binding books can be placed in the baking room under the same conditions. The baking room temperature is 50 degrees to 55 degrees. And the PUR hot melt plastic book is still intact. In the ideal case of sheet material, PUR hot melt adhesive binding is not a problem at a temperature of -40 degrees to 120 degrees. This is its excellent characteristic of adapting to hot and cold environments, which is far superior to other hot melt adhesives and solves the problem of book binding. The trouble of the influence of temperature on the quality.
When using ordinary hot melt glue to bind the book block of paper with horizontal thread and special paper with irregular texture, there will be many wrinkles in the groove. The PUR hot melt adhesive temperature is low (normal working temperature is 120 degrees), will not make the paper spine internal moisture evaporation, at the same time, the hot melt adhesive layer in the drying process has a certain degree of ductility, so that the paper fiber can be restored.
With PUR hot melt adhesive binding books and periodicals as long as the hair, slotting method is correct, properly operated, there will be no peeling phenomenon, binding the appearance of the whole book and periodicals. In addition, because PUR hot melt adhesive consumes more than other adhesives, a small amount of adhesive on the back, side adhesive and cover holder is squeezed out of soft mud on the package, and uneven phenomenon or gap will not appear on the edge of light cutting, thus keeping the shape of the spine in good condition.
PUR hot melt adhesive layer is firmly formed, has strong solubility, is a kind of adhesive material with both solubility and oil resistance. After drying and curing, the PUR hot melt adhesive layer can penetrate into the printing oil and solvent, such as methyl ethane ketone, alcohol, etc., so that it slowly softens or even dissolves. As the EVA hot melt softens and decreases in strength, serious quality consequences such as page shedding will occur. It can be seen that the hot melt adhesive is not affected by the solvent, maintains the original bonding strength, and promotes the improvement of the quality of book binding.
For many years, the hardcover core of the book spine has been using a lock thread sleeve. Before picking the circle, the lock thread should be put into the core with a layer of adhesive with good toughness. In the European market survey, it was found that the book core was picked with PUR hot melt adhesive, which was directly shaped and cross-linked and dried to maintain the ridge shape and lasting deformation. It is a good choice to make a round back with PUR hot melt adhesive.
PUR hot melt adhesive has so many benefits, but it has not been widely used. The main problem is cost. Although the cost of PUR hot melt adhesive is about three times that of ordinary hot melt adhesive, the use amount is only half of that of ordinary hot melt adhesive.
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