Analysis of PUR Technology Concept and Its Latest Development Trend

The new type of adhesive for adhesive tapes, the active polyurethane (PUR) hot melt adhesive, was first introduced at the Drupa exhibition in 1988. At the time, experts alleged that it was an irresistible adhesive product. It was an innovation and would certainly Beyond the traditional wireless glue-binding process, the processing production of difficult operations is elevated to a new level.

After more than ten years of development, PUR adhesives have become more and more popular in UV coated papers and high-filled papers. It is also very suitable for bookbinding such as computer manuals that may require high-strength external forces, and some may Exposure to bookbinding areas with extreme temperature or temperature fluctuations, such as car manuals and maps.

What is PUR technology? Why is it so successful? This article will briefly introduce the development of PUR technology and its latest development trends.

What is PUR technology?

PUR hot melt adhesives are mass-produced PUR toppers with active terminal groups. Cross-linking reactions occur when the active terminal group is exposed to moist air or the moisture of the paper reaches a certain level. After the top polymer is wetted, it penetrates well into the paper, achieving a higher viscosity and a higher paper tension.

After cross-linking, the PUR film exhibits a higher intrinsic strength (cohesion) so that a very durable adhesive film can be formed. PUR film is not only insensitive to printing inks and solvents, but also has extremely strong durability.

If you use PUR hot melt binding book, you can use in ultra-cold or super hot environment. PUR wireless books can be safely stored in a 120°C environment without any loss of quality. In addition, they can maintain good plasticity even at minus 40 degrees.

Adhesive equipment

Despite so many advantages, by the end of 1988, only two German bookbinding companies were using PUR hot melt adhesive technology for wireless adhesive bonding. To be sure, performance is not a problem. PUR technology has been well validated in many market segments. One of the biggest obstacles to development is the need to transform the equipment, especially the system that reacts to this technology.

For example, the plastic box will be covered with thick adhesive after being used for a period of time, and can only be removed after cleaning. In addition, the pressure of the adhesive must be reduced, and the operating temperature must be optimized.

The two German book binding companies that first mentioned the use of PUR technology used the DIY method to modify the structure of the equipment themselves.

In addition to equipment issues, the need for new hot melt equipment has also hindered the growth of PUR technology. Since the PUR adhesive is a moisture-cured system, the adhesive must be isolated and kept absolutely dry. Therefore, the transportation and application of the adhesive must be done with care. This is why the PUR is always transported in full containers and applied by a dedicated melter. The dedicated melter always seals the seal of the tank, avoids contact between the glue and air, and conveniently provides PUR on-demand supply. Due to the need to take glue as needed, the pressure of the system temperature is avoided.

PUR is a perfect process

There are currently more than 150 bookbinding companies in Germany, and hundreds of binding companies worldwide have switched from traditional hot melt adhesives to PUR hot melt adhesives. The new binding device, combined with the latest PUR hot melt adhesive technology, ensures the smooth and complete binding process.

Users of PUR are no longer limited to traditional roller coating applications, but have introduced many new processes and technologies, such as the use of a nozzle system to effectively apply glue to the bottom of each book.

With these nozzles, the binding plant can reduce the thickness of the coating to 0.3 mm, making the book unfolded very well.

The thickness of the PUR film can be reduced by 50% or less compared to the standard EVA hot melt adhesive. Although it is more expensive, it is relatively thin, so the two can be complementary.