As a sports event held every four years, this year’s World Cup in Qatar continues to attract countless fans. During the September-November period, peripheral products related to the World Cup became the search keywords on Ali International Station, and the number of global buyers of football shoes increased by nearly 100%
How important is the right pair of sneakers? It can not only maximize your football skills, but also protect your feet very well, which greatly enhances your fun and satisfaction in the process of playing football.
01 shoe leaking problem
When it comes to football boots, water leakage is the first problem to be solved. Assuming that in the uncontrollable situation of rain, the shoes leak and the players will not be able to enjoy the game happily.
What happened to the leaking shoe?
Water leakage in shoes is mostly due to the degumming of the joints of the shoe materials. Affected by external factors such as temperature, oxygen, water, acid-base salts, impurities, mechanical damage, etc., the composite coating glue or the bonding layer of the composite surface of the shoe materials is aging, and the polymer is damaged. destroy.
02 The role of grafted compatibilizer in shoe materials
Therefore, in production, composite bonding is one of the key links in shoe production.
It runs through all aspects of shoe production, such as sole bonding, vamp bonding,
insole bonding, etc. The bonding performance of hot melt adhesives is very important.
Hot-melt adhesives are widely used in the shoe industry because of their environmental protection,
solvent-free, extremely low VOC, and convenient processinThe key material that affects the bonding performance of hot-melt adhesives is the grafted phase
with strong polarity and high peel strength. Toner.
There are many types of graft compatibilizers, and there are many monomers used for grafting.
The commonly used ones are: maleic anhydride (MAH), glycidyl methacrylate (GMA), styrene (St), methyl methacrylate (MMA) ), butyl acrylate (BA), acrylic acid (AA), epoxy resin, oxazoline, etc.
These compatibilizers are only different in monomers, and the principle is similar: use free radicals to initiate into the mixture of monomers and polyolefins Grafting reaction can be carried out.
Among them, the maleic anhydride (MAH) graft compatibilizer is the most polar
because of the maleic anhydride monomer, and the graft compatibilizer produced by the same
base material is also the most polar, so it is also the most widely used, and it is widely used in shoe materials. Tons of applications.
03 Classification of Graft Compatible Hot Melt Adhesives
There are five main categories of hot-melt adhesives for footwear: EVA hot-melt adhesive film,
TPU hot-melt adhesive film, PES hot-melt adhesive film, PA hot-melt adhesive film, and PO hot-melt adhesive film. The grafted compatibilizers that can be added include grafted POE, grafted PE, grafted SEBS, and grafted EPDM, in addition to the most widely used grafted EVA.
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04 Specific application of graft compatible hot melt adhesive
The application parts of grafted compatibilizer hot melt adhesive mainly include shoe uppers,
insoles, shoe labels, foot pads, heels, setc.
(1) Fitting of the non-sewn upper to the inner of the shoe
Mainly for sports shoes, it is used for the lamination of shoe uppers, mesh and other materials,
and is used for high-frequency machine hot-press bonding of shoe upper leather and mesh.
The upper does not need needle and thread sewing, and it is mainly used for EVA instead of
traditional glue. Insoles, PU insoles, PU soles, rubber soles, EVA soles, etc. fit the feet and heels.
(2) Bandage
The upper is to nail the inner sole of the shoe to the plant with the upper, and then use an adhesive
to firmly bond the upper and the inner sole. The compatible agent type hot melt adhesive used in
the banding requires short sticking time and high bonding strength, and the bonding process is
completed once on the banding machine. Most of the graft-compatible hot melt adhesives are
pre-formed into strips, and then transported to the bonding part of the upper and the inner sole,
and heated and pressed for a few seconds to complete the bonding operation of the upper.
(3) Sticky outsole
Outsoles account for the largest share of hot melt adhesives used in the shoe industry. Since the
outsole and the upper require high bonding strength, polyester hot-melt adhesives with high
crystallinity and high cohesive strength are generally used.
(4) Bonding the main heel and Baotou
Using graft-compatible hot-melt adhesives to glue the main heel and toe cap can eliminate the
necessary drying procedures for water-based and solvent-based adhesives and shorten the production
cycle. If it is a soft toe cap, use a small extruder to directly extrude the compatible hot melt adhesive
to the toe cap on the inner surface of the upper and spread it into a toe cap shape.
After the hot melt adhesive cools, it becomes a soft toe cap, and there is no need to re-line it.
(5) Adhesion of uppers of shoes and rubber shoes
In addition to environmental protection factors, the use of graft-compatible hot-melt adhesives is also
an important reason for high efficiency, straight shoe materials, moisture-proof, anti-corrosion,
and good hygienic performance. The dot coating process keeps the fabric well ventilated and makes
up for the deficiencies of gasoline glue and latex in these aspects.
