ADVANTAGES AND DISADVANTAGES OF THE USE OF THE POLYURETHANE THERMOFUSIBLE (PUR) IN FRONT OF THE HOT-MELT STANDARD IN BOOK BINDING. Disadvantages of PUR: Stiffer, the book can effect stash (closes alone and costs to keep it open) There are few varieties of PUR and for thick books are not very appropriate. They can not be used for rounding the back of the book. Deteriorates in approximately one hour with ambient humidity According to the glue application system, machine stops deteriorate a certain amount of adhesive that crosslinks and is unusable. It does not always react the same as it depends on the humidity and humidity of the paper. In summer it reacts faster than in winter. If the paper is very dry it reacts little. This results in differences in the setting time (crosslinking) of the adhesive to be fully manageable. The book is not completely manipulated until 24 hours. Falls in the collection of the book or other manipulations deform the book. Contains isocyanate, even those called ecological contain a small amount and this product is toxic and can cause skin and eye irritations. Prolonged inhalation may produce asthma. Normal hotmelt allows to work at higher application speeds so you get more efficiency and productivity than with PUR. Much higher price with respect to hotmelt (on the order of 3 or 4 times more) It generates cans of waste from the container, which have to be destroyed in an authorized landfill, which represents a cost, while the bags are domestic waste or can be sold. Advantages of PUR: More resistant chemical bond in the PUR. The union of the hotmelt is physical. The PUR reacts with the humidity and moisture of the paper, which is chemically bound to the paper fiber. It withstands more extreme temperatures, especially below zero. It is best for low-absorbency or high-gloss or very glossy or highly varnished papers and for cross-fiber paper where normal hotmelt adhesive is difficult for paper to penetrate. CONCLUSION: PUR adhesives are excellent for problematic papers such as very varnished, very high gloss and / or low absorption ink such as catalogs and the like, but for other books or magazines with more normal papers is not justified by price or Performance or toxicity. In addition there are many more varieties of standard hot-melt for all types of book, machine or rounding, while PUR is much more limited and makes books with low flexibility.