When machining molded soles of thermoplastic rubber (TPE), ruffling of the adhesive edge is generally not required. The surfaces of the soles to be bonded are treated with a halogen solution. Halogen is applied with a brush with a sheared pile. At the same time, special care should be taken in the dosage of this chlorine-containing product, to avoid overflow on the sole material and stagnation of the excess in the voids and hollows of the inner profile of the soles. If there are voids in the sole body that lighten its weight, the sole, after the application of halogen, should be held with the running surface upward to avoid cracking and subsequent destruction of the material. The curing time of the sole before the adhesive is applied should be at least 40-60 minutes.
Some important rules for the use of halogen solution:
Halogen should not be stored in the light;
Halogen should not be poured into metal containers;
Brushes for application should not have metal frames;
Do not return the residues the time of use of the open working volume no more than 8 hours, then its properties will be lost.
For gluing TPE material you must use classic polyurethane adhesive, one- or two-times application is possible, depending on the density of the sole material.
When activating the adhesive film and the subsequent installation efforts on TPE soles, in which rants and other very small cross-section (such as Courtney, Allegra, Irida, Vera-3) are used, there are high risks of deformation of small cross-section elements, their displacement, warping and/or lagging. Possible disclosure of the locking of the ends of the rant due to significant overheating of the sole body (see photo). To avoid this type of problem, the heating of the sole should be limited. At the same time, the activation of the adhesive layer must be done for the glue to work properly.
In these cases, we recommend using adhesives with a low activation temperature threshold (low-temperature polyurethane adhesives).
In such products the activation level of adhesive film starts from 45-50*С . Crimping and setting operations on heated sole, carried out manually are accurately, without pressure on the rant and small details of the relief of the working tool. Hot crimping of material at the edge of the welt is performed with due consideration of possible displacement or separation of the welt.
GLUING OF LIGHTWEIGHT TR
An important point when working with foamed FEP is to understand its porous, "air-blown" structure and to react adequately to this factor!
1. the adhesive edge must be cleaned and halogenated.
2. Pause from 40 minutes to 60 minutes for weathering of halogen, depending on its type
Application of a specialised polyurethane primer (e.g. ROSER 760) to seal the surface structure of the adhesive surface. 4.
4. 4. Curing time of 15-20 minutes for the priming coat to dry.
5. Application of the basic PU glue (Desmacol type). 6.
6. 6. 15-20 minutes drying time of the main adhesive.
7. Activation of the adhesive film according to the requirements of the technical card on the adhesive*.
The process of glue film activation, positioning and installation of the sole on the workpiece should be conducted with increased attention. The task is not to allow the sole material to overheat to preserve the integrity and shape of the sole.
We recommend using low temperature modifications of PU adhesives for gluing operations. Glue film activation temperature of such glue lies in the range 50-55*C, which will give you a significant gap in capabilities. Consult your chemical suppliers for availability of such adhesives.
Separately, I would like to dwell on the operational limitations of TPE soles. It is worth reminding the end Client about some unacceptable actions in the operation of finished shoes. In particular, it is unacceptable to place shoes (soles) near existing heating devices with their subsequent operation. In such cases, thermal deformation and delamination of the material of the soles is possible (and sometimes inevitable).
