The colors of hot melt adhesive for wireless binding of books and periodicals are milky white, transparent, light yellow, grayish white translucent and dark yellow.

Hot melt adhesives for books and periodicals are divided into edge adhesives and back adhesives according to their uses.

Edge glue: rubber cover, generally softer than back glue, with low color requirements. High viscosity is required. Adhesive: The color requirement is slightly higher. The hardness requirement is higher.

By shape: cylindrical particles, round particles and blocks are the most common. Generally speaking, the yellower the hot melt adhesive used for book binding, the stronger its stickiness.

Extended data:

Hot melt adhesive is a kind of plastic adhesive, which is solid at room temperature and can be quickly bonded after heating and melting.

Its characteristics:

( 1)? Quick bonding? Usually, it takes only a few tens of seconds, or even a few seconds, from gluing to cooling bonding.

(2)? Wide bonding range? For many materials, even for recognized viscous materials (such as polyolefin! Waxed paper! Carbon paper, etc. ) can also be bonded, especially the joint bonded with hot melt adhesive can withstand bending above 105~ 106 without cracking?

(3)? Can be repeatedly heated and bonded.

(4)? Stable performance? Convenient storage and transportation

(5)? Low cost? Hot melt adhesive has no solvent consumption, which avoids the deformation of the adherend due to the existence of solvent! Dislocation shrinkage helps to reduce costs!

Improve product quality "However, hot melt adhesive also has some shortcomings" mainly due to its low heat resistance and bonding strength, and it is not suitable for structural adhesive ". Because of its high melt viscosity and poor wettability to the adhered materials, hot melt adhesives usually need pressure bonding.

So as to improve the bonding strength; In addition, the use of hot melt adhesive requires special equipment, such as hot melt glue gun of glue coater, which limits its application scope to some extent. The physical state of hot melt adhesive changes with the change of temperature in a certain temperature range.

However, the chemical characteristics remain unchanged, and it is non-toxic and tasteless, belonging to environmental protection chemical products.

EVA hot melt adhesive is a solid meltable polymer, which needs no solvent and contains 100% water. It is a solid at room temperature, and when it is heated and melted to a certain temperature, it becomes a flowable viscous liquid. The melted EVA hot melt adhesive is light brown or white.

EVA hot melt adhesive consists of basic resin, tackifier, viscosity regulator and antioxidant.

The basic resin of hot melt adhesive is the polymerization of ethylene and vinyl acetate at high temperature and high pressure, that is, ethylene-vinyl acetate copolymer. This kind of resin is the main component of making hot melt adhesive, and the proportion and quality of basic resin determine the basic properties of hot melt adhesive.

Generally, the VA content is 18-33, and the MI is 6-800. The lower the VA content, the higher the crystallinity and hardness. In the same case, the higher the VA content, the lower the crystallinity and the higher the elasticity. The choice of EVA finger is also very important. The smaller the melting finger, the worse the fluidity, and the higher the melting temperature, the worse the wettability and permeability of the adherend.

On the contrary, if the melting finger is too large, the melting temperature of the adhesive is low and the fluidity is good, but the bonding strength is reduced. The selection of additives should be based on the proper ratio of ethylene to vinyl acetate.

References:

Encyclopedia-hot melt adhesive