Advantages of PUR hot melt adhesive

1. The book is very flat

According to the recommended thickness of the glue, the thickness of the book block is about 0.025cm. At this time, the PUR glue layer is much softer than the EVA hot melt glue, so the book is very smooth to open. You do n’t have to press the book with your hands when reading, the flatness of the book is improved The reader's reading comfort. Therefore, PUR is favored by some large companies, such as Microsoft and Texas Instruments, which use PUR hot-melt adhesive to bind product user manuals.

2. High temperature and low temperature resistance

Put a booklet bound with PUR hot-melt adhesive and a booklet bound with EVA hot-melt adhesive into the refrigerator for one night. Remove the two books from the refrigerator the next day and open the booklet. When you hear the cracking sound of EVA hot-melt adhesive booklets, PUR hot-melt adhesive booklets are intact.
The refrigerator test simply compares the environmental conditions that the book may face in winter. To test the durability of PUR bound booklets under summer environmental conditions, the booklets can be placed on the back of the trolley during the day, and the ambient temperature can reach 43 ° C. Under this temperature condition, the booklets bound by EVA hot-melt adhesive begin to loosen The pages fell off, and the PUR-bound book remained intact.

Even if the PUR bound booklet is placed in a high or low temperature environment, it will not be affected at all, and even reaching 94 ° C or minus 40 degrees is no problem.

3. Spine leveling

When using ordinary hot-melt glue to bind those artistic paper book blocks with irregular texture, a lot of wrinkles will be generated in the groove. Because PUR hot melt adhesive is a cold adhesive, the working temperature is low, so the moisture of the paper at the spine will not be lost. At the same time, the PUR adhesive layer has a certain ductility during the drying process, so that the paper fibers can be restored.

In addition, due to the small amount of PUR hot-melt adhesive used during binding, few adhesives are squeezed out on the encapsulation table, and the splints on both sides firmly wrap the cover on the book block, forming a sturdy spine.

4. Book block incision is smooth without trapezoid

Because the coating thickness of PUR hot melt adhesive is only half of the thickness of other hot melt adhesives, the cut is smooth without trapezoid when cutting, and the edge of the book cover is also very smooth.

5. Solvent resistance

Some binding experts believe that PUR is the only binding material that is resistant to solvents and grease. Immerse the dried and fixed PUR adhesive layer in the solvents and greases used in the printing industry, such as methyl ethyl ketone and alcohol. These chemicals have no effect on the PUR layer. On the other hand, some solvents used in the printing industry will completely soften or even dissolve frequently used hot melt adhesives, such as EVA.

6. Cost-saving for hardcover

For many years, the book blocks of the hardback books with round backs have been set with lock threads, and a layer of adhesive with good toughness is brushed on the book blocks with the lock threads before the round. According to the usage of some users, flatten the book block with the lock thread and then brush it with PUR hot melt adhesive. This binding method can save about 30-40% of the cost.

7. Good rounding performance and the arc is not easy to deform

Many hardcover books use round spine backs to improve the beauty and durability of the books. Brush PUR adhesive on the book block, then round and ridge, you can get a more beautiful round ridged book back. Because the PUR adhesive layer and book block are dried in a round state, the durability of the round book back is maximized. However, when binding the book blocks of ordinary hot-melt adhesives, the glue is generally brushed first, and then rounded, so the durability of the round cannot reach the effect of PUR bonding.