Polyurethane Systems for Soling
Polyurethane systems for footwear soling can be based on either polyester or polyether polyols. These two system types have individually unique performance characteristics, and system selection is determined by end use of the shoe sole product. Polyesters tend to be cheaper, lower in viscosity, and more reactive. Polyether polyols tend to give better abrasion and chemical resistance properties, are higher in viscosity, and are typically higher priced. Polyester polyols are common in the Coatings, Adhesives, Sealants and Elastomers (CASE) polyurethane applications. The shoe sole industry is one area where some applications use polyester polyols to achieve the desired physical properties. Based upon Chem-Trend’s experience, and abilities to customize products based on customer need we can make adjustments to the mold release chemistries to provide better release properties and improved surface finish (uniformity, gloss, etc.) as required by the customer.
Polyester systems are generally fast to react due to the fact that they are solid at room temperature and must be heated prior to use. The need for elevated temperatures to maintain a liquid form can make handling of polyester polyols difficult. Since the foam system is heated, mold temperature and cure times are generally reduced. Another advantage is that polyester systems are less expensive than a polyether system. However, soles made with polyester polyols are less durable and can be susceptible to biological (bacteria/fungi) attack. These attributes are best suited to footwear markets with rapidly changing designs and where consumers frequently purchase new footwear styles to keep up with current fashion trends.
Polyether based polyols are more resistant to oil and chemical attack and are more temperature resistant. The foam system is liquid at room temperature and does not require any special handling techniques. Molding temperature and cure time is usually increased (compared to polyester) for polyether-based foam systems. Soles manufactured with these foam systems are well suited to markets where durability is important, such as safety shoes.
Chem-Trend’s Global Support Network
When customers purchase Chem-Trend release agents, and related products, they also gain access to a worldwide support network of industry professionals committed to providing the right product for their application. We make our global expertise available locally to our customers through our sales, technical and support professionals. Our production facilities use leading development, testing and production equipment and processes to assure consistent batch-to-batch products. Do you have a unique application that requires something more? Chem-Trend can formulate custom solutions to meet your shoe sole manufacturing needs.
To learn more about how our products and expertise in the area of shoe sole molding operations can help you improve quality and efficiency read our sections on release agents for shoe soling or ancillary molding products for shoe soling. Otherwise, contact us to speak with one of our shoe soling experts.