Polyurethane based shoe adhesive formulation.

Polyurethane based shoe adhesive formulation.

Polyurethane-based shoe adhesives are made from a combination of isocyanates, polyols, and solvents. The exact formulation depends on the desired properties of the adhesive, such as its volatility, cost, and adhesion strength. 

Ingredients

• Isocyanates
• Tolylene diisocyanate is one example of an isocyanate used in shoe adhesives 
• Polyols
• Polyester polyol is a common polyol used in shoe adhesives 
• Solvents
• Methyl ethyl ketone (MEK), acetone, toluene, 1-methylpropylacetate, 2-butyl acetate, and 3-ethyl acetate are all solvents that can be used in shoe adhesives 
• Other additives
• Fumed silica, fumaric acid, vinyl emulsion, and organic dyestuffs can also be added to shoe adhesives 

Formulation

• The formulation of a solvent-based adhesive can be based on a 1:1:1 ratio of MEK, acetone, and toluene 
• The amount of acetone can be increased for faster volatility, or toluene can be increased to reduce cost 
• The adhesive can be cured with a mixture of urea, methylenedianiline, and sodium chloride 

Application 

• The adhesive can be applied in a thin layer using a brush
• The brush should be used to move the adhesive in the same direction to allow air to escape and strengthen the adhesive's viscosity