Brief introduction of hot melt adhesive
Published:2010-04-14 12:58:09    Text Size:【BIG】【MEDIUM】【SMALL

HMA is short for hot melt adhesive, which is an important adhesive category, with characteristics of 100% solids and without solvent, environmental friendly, non-toxic and fast curing etc. Usually it refers to the adhesive which is solid at room temperature, and melt into sticky liquid when heated to a certain temperature. With ability of finishing bonding in a few seconds after coating or wetting the material. It is widely used in such industries as automatic packaging, sanitary products, label tape, medical and pharmaceutical, automotive interior decoration, building waterproof, furniture, printing and binding, shoes, clothing etc.

Classification of HMA
①Divided by difference of main material: polyethylene - ethylene vinyl acetate (EVA) hot melt adhesive, polyamide (PA) hot melt adhesive, polyurethane (PU) hot melt adhesive, polyolefin (PO) hot melt adhesive, styrenic block copolymer (SBC) hot melt adhesive etc.
②Divided by difference of shape: Hot melt adhesive granule, hot melt adhesive stick, hot melt adhesive block, hot melt adhesive film, hot melt adhesive powder etc.
③Divided by difference of usage: filter hot melt adhesive, automatic package hot melt adhesive, automobile interior decoration hot melt adhesive, label hot melt adhesive, tape hot melt adhesive, plaster hot melt adhesive etc.

Character of HMA
①Fast curing speed, with characteristics of melting when heated and sticking when cooled, which is convenient for continuous and automatic high-speed operation, hence it could improve the production efficiency and reduce the cost at the same time.
②100% solid content, without solvent, environmental protection, non-toxic, energy saving, no secondary pollution to the environment.
③Non-reactive hot melt adhesive could be repeatedly melted and bonded, especially suitable for some component bonding with special technological requirements, such as the restoration of some cultural relics.
④Could be applied to a wide range of objects, with good adhesion to paper, plastics, metals, ceramics etc.
⑤It is convenient to use, cause the equipment covers a small area, and saving labor. All is available of spray, roll paint, scratch paint, point paint, line paint etc.

Tackifying of HMA
It is all known that adhesive property to base material is one of the most important performance indicators of hot melt adhesive, to determine whether hot melt adhesive is qualified, usually the first test is cohesive force. The factors affecting bonding power are formula design, bonding theory, substrate treatment etc. In order to improve the adhesive strength of HMA, the most commonly used method is to add tackifying resin in the formula.
There are many kinds of tackifying resin, according to the source they can be divided into natural tackifying resin and synthetic tackifying resin, the common tackifying resin used for hot melt adhesive are: rosin and its modifier, terpene resin, petroleum resin, alkyl phenolic resin, etc. The compatibility of tackifying resin is good, which could improve the cohesion of hot melt adhesive, the surface cohesion of substrate, as well as the flowability, wetting and permeability of matrix.
In the future, under the trend of hot melt adhesive industry globalization, the demand will be more diversified. Gradually large-scale hot melt adhesive enterprises will have enough strength to do basic research, so as to gain an advantage in the market of serious product homogeneity, therefore development of technology is almost inevitable.

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