Mendeleev Ltd.

Development and production of paintwork materials

Preservative substances and hydrophobizators for wood and concrete,
automobile chemical goods, paint removers, anticorrosive PM, solvents for printing industry.

Solvent, enhancing adhesion of polyurethane soles to leather uppers

Materials supplier: Mendeleev Ltd.
Applied materials: Turbo-reactive solvent grade “Ya”.
Objective: Remove the process of mechanical preparation of polyurethane soles glossy surface from the technological procedure. Create an agent that would enhance the adhesion of a polyurethane sole to leather.
Date of operation: December, 2011.
Air temperature: from 18ºC.
Relative air humidity: 84%.

Turbo-Reactive Solvent Grade “Ya” helped in enhancement of adhesion when gluing polyurethane soles to leather uppers at one of Saint Petersburg footwear factories.
Works execution procedure:

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.1 – Polyurethane soles, glue, Turbo-reactive solvent grade “Ya”

Soles are produced by moulding. Note the perfectly plane and smooth surface that does not provide necessary adhesion of polyurethane to leather while gluing. Mechanical treatment was used for adhesion enhancement formerly. The process is labor-intensive, time-consuming and requires special skills. So how can we attain effective gluing of polyurethane soles to a leather upper? The answer is simple enough: the gloss should be treated with a mordant. Dichloroethane, acetone and methylene chloride could not cope with that. Turbo-reactive solvent grade “Ya” demonstrated excellent results, irrespective of polyurethane Shore hardness.

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.2 – Turbo-reactive solvent grade “Ya”

Turbo-reactive solvent grade “Ya” is a mixture of organic high-boiling solvents. By appearance it is a homogeneous, colorless liquid, free of foreign matter (mechanical admixtures), with a specific odor.

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.3 – Applying the solvent onto a polyurethane sole

The composition may be applied onto a polyurethane sole by spraying it through a trigger or with a brush, as is shown above. Wait for 3 minutes. During this period Turbo-reactive solvent grade “Ya” stains the surface and evaporates. Using this agent we can attain in a couple of minutes the same result as after a mechanical treatment.

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.4 – Microrelief of a sole before and after staining with Turbo-reactive solvent grade “Ya”

After the chemical staining with Turbo-reactive solvent grade “Ya” the glossy, perfectly plane surface of a polyurethane sole becomes rough and has a porous structure. Such a result was formerly attained by a mechanical treatment, a highly labor-intensive, dirty and uneconomical step. Surface porosity, i.e. availability of multitude of microroughnesses appears due to the micromolecular elastomeric layer being dissolved by the agent, and thus, making high adhesive capacity of the materials possible.

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.5 – One-component polyurethane glue fastening the surfaces rapidly and effectively
 
Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.6 – Applying glue onto a polyurethane piece

Apply semitransparent glue onto a sole piece with a brush.

Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.7 – Stick the polyurethane piece to the polyurethane sole
 
Solvent, enhancing adhesion of polyurethane soles to leather uppers
Pic.8 – The polyurethane piece glued fast to the polyurethane sole

Treatment of a smooth and glossy surface of the sole with Turbo-reactive solvent grade “Ya” is a fundamental step, resulting in considerable adhesion enhancement of the different Shore hardness materials being glued. Due to this solvent the mechanical treatment step was excluded from the works execution procedure. Turbo-reactive solvent grade “Ya”, manufactured by Mendeleev Ltd. improved labor efficiency by means of one item treatment period increase. Polyurethane pieces are glued to each other rather hard. However, after staining the materials with composite Turbo-reactive solvent grade “Ya”, a polyurethane piece was glued to a polyurethane sole so fast that it was impossible to separate them. Materials merged into a single piece due to high rubber adhesion capacity. Thus the polyurethane sole itself is ruptured now, the glued surfaces remaining undamaged.