Polyethers shoe solings

Another major use for semi-rigid polyurethane foams is as shoe soles. In this application, their light weight, abrasion resistance, and shock absorbing properties are important. In safety shoes, chemical and oil resistance are important. Polyether-based foams are used in applications where microbial attack is common, such as shoes intended primarily for use on soil or grass. 

The polyether polyols based exclusively on ACN are commercialised because of their high glass transition temperature (T ) of the polyacrylonitrile solid fraction. However, they are not used for production of slabstock foams, but for PU elastomers (microcellular elastomers for shoe soles) and integral skin foams. 

Quasi-prepolymer systems based on polyester polyols and polyether polyols are becoming important in shoe soling, the former being most wear resistant and the latter the easiest to process. 

Polyester polyols are used widely in urethane adhesives because of their excellent adhesive and cohesive properties. Compared to polyether-based polyols, polyester-based polyol adhesives have higher tensile strengths and improved heat resistance. These benefits come at the sacrifice of hydrolytic resistance, low-temperature performance, and chemical resistance. One of the more important application areas for these products is in the solvent-borne thermoplastic adhesives used in shoe sole binding. These products are typically made from adipic acid and various glycols (see Fig. 15). 

David Ho, Williams Gill, Charles Huang. High performance Light-weight PU Shoe Sole Material Based on New Polyether Polyols. Proceeding of PU-tech Asia, 1997, (5) 221 223. 

Microcellular polyurethanes for shoe soling are of both the polyester and polyether types. Polyester types were developed first and owing to their generally superior mechanical properties they tend to be used in the thinner sole, high quality section of the market. Such polyester systems are usually based on quasi-prepolymers (made from part of the polyester and the MDI) and a resin blend made up of the rest of the polyester, the chain extender (usually butane diol), catalysts, surfactants and water to produce carbon dioxide to blow the foams. The use of a quasi-prepolymer enables the two... 

Two basic types of polyurethanes are available as shoe-soling products polyester- and polyether-based systems. The polyester systems were first... 

B Polyether-polyurethane 85 A to 64 D Flexible at low temperatures, resistant to wear, good mechanical properties, wide range of physical properties Shoe soles and accessories, tubing, technical parts... 

S Polyether-polyurethane 60 A to 74 D Resistant to wear, good mechanical properties, tear and abrasion resistant, UV-stable Shoe soles, tubing, castor tyres... 

Uses Surfactant for reduced shrinkage in PU elastomers, shoe soles surfactant for microcellular foam improves dimensional stability in low-dens, polyether systems... 

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