footwearthe Huntsman story

Huntsman Polyurethanes is part of Huntsman International LLC, a dynamic public company with operations in more than 22 countries. originally known for pioneering innovations in packaging and later rapid and integrated growth in petrochemicals, the Huntsman group of companies today employs over 11,000 people throughout the world and generates revenues of approximately $11 billion. with the resources of a global company, security of supply and product quality are assured. our technical experts based in regional Development Centers in europe, asia Pacific and the americas are working closely together and sharing their expertise to the benefit of our customers. this cross-learning means that, while being sensitive to local needs, our company can offer global knowledge and capabilities to help formulators establish new uses for their products and to deliver growth by driving differentiation and innovation.

as a supporter of responsible Care, the international chemical industry initiative, Huntsman is committed to improving all aspects of environmental, health and safety activities.

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footwearfirst steps for polyurethanes

one of the immediate attractions of polyurethanes for shoe-making is that they allow manufacturers to produce lighter and more comfortable footwear.However, the introduction of polyurethanes to the footwear industry was not without its challenges.In the late 1960’s shoe producers had little experience with ‘reaction polymerization’ (the process whereby polyurethane materials are produced) and their favored materials required completely different equipment, manufacturing processes and raw materials handling.

for those who did make the ‘leap’ into new technology, the tremendous advantages were soon apparent. with relatively low capital investment, they could achieve high output and reduce unit costs. the technology generated a range of unique and almost limitless properties that could be manipulated to meet specific needs.Huntsman was the first to introduce polyurethanes to the footwear industry. It built on this lead with further innovations including the first water-blown polyether systems which completely eliminated the use of ozone-depleting CfC’s and HfC’s.

In the middle of the 1990’s, the Huntsman footwear focused technology program broke new ground with the first universal prepolymer for use with both polyester and-polyether based systems. this has seen widespread use particularly in the manufacture of all Polyurethane wellington boots and low density foams for sports footwear.

at the turn of the century, Huntsman pioneered the aVaLoN® Duo soling concept combining thermoplastic polyurethane (tPU) with reaction molded polyurethane (PU) in a combination sole.

this drive for continuous innovation continued with the pioneering launch of smartLite® a new generation of lightweight high performance thermoplastic soling.

Polyurethanes are either polyester or polyether-based depending on the physical and mechanical properties required and can be injected into closed molds or cast into open moulds. they are easy to process, require relatively low tooling and manpower costs, offer flexibility for long and short production runs and are in line with environmental standards.add together the extra scope they give to be creative and fast off the mark with new designs, production advantages and user benefits of comfort, abrasion-resistance and durability, and you have a material that outperforms all others in terms of versatility.

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footwearUnmatched versatility

the unique versatility of polyurethanes as a soling material stems from the almost limitless chemical formulation combinations which give designers and manufacturers the freedom to create innovative designs that are in step with fashion and technological change. Polyurethanes can be made light, tough, comfortable, flexible, insulating, waterproof, slip-resistant, hardwearing and shock absorbent as required, simply by varying the formulation. they can have an almost endless variety of shapes, surface textures and colors and incorporate air-bags, inserts or gels for extra comfort and support. furthermore, PU bonds well to many types of shoe upper (leather, textile) as well as a range of complimentary soling materials (rubber, leather).

In recent times, footwear design has become something of a science, with specialist shoes being developed for a wide range of work and leisure applications. Using polyurethanes, the manufacturer is well placed to address special needs such as energy management, anti-static properties, improved abrasion resistance, low temperature flexibility and resistance to hydrolysis, microbial attack and premature ultraviolet yellowing.

thermoplastic (tPU), rather than reaction molded polyurethanes, offer footwear manufacturers a material even more flexible and abrasion resistant. available in a full range of different hardnesses, tPUs are especially suitable for applications such as safety boot outsoles, sports plates for soccer & golf, molded shells for in-line skates as well as heels and top pieces for fashion shoes.

Huntsman is the only major global supplier that has developed a range of tPU dedicated to the footwear industry. this premium shoe soling material is marketed under the aVaLoN brand.

taking the excellent properties of tPU to the next level, Huntsman responded to the market needs for a lightweight yet high performance thermoplastic soling material with the latest development and successful launch of the smartLite® brand. this material offers designers and manufacturers an unrivalled combination of lightness and performance with the aesthetics demanded by today’s discerning consumers.

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footwearthe rise of unit soles

Increased specialization in the footwear industry has led to the strong growth of unit sole manufacturing. Nowadays, it is the biggest single production method for polyurethanes in footwear.

The key benefits offered are• low density • hardness (low to hard)• very high production efficiency• speed of new developments and design• versatility of colors and finish• easy adhesion to uppers• abrasion resistance• flex performance

Huntsman Polyurethanes offers high quality technology in either polyester or polyether-based liquid systems. Personalized formulations can be developed to suit the required application.

where the highest levels of quality are required, unit soles can also be produced in tPU or smartLite®. aVaLoN grades down to 55 Shore a have been specifically developed for unit sole production, providing stunning design possibilities combined with comfort and excellent grip. Significantly, unit soles produced in aVaLoN tPU or smartLite® achieve perfect bonding to shoe uppers without priming, roughing or halogenation.

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In the manufacturing process, shoe soles are direct molded onto uppers. If the bottom of the sole requires enhanced mechanical properties, a thin layer of almost compact polymer is molded in combination with a midsole to create a dual density sole which is light, comfortable and hard-wearing.

Polyurethane Wellington boots aimed primarly at the construction, agricultural and cold store worker, polyurethane wellington boots offer good flex properties right down to low temperatures; tough, hard-wearing, anti-slip outsoles; oil, biological and hydrolitic resistance; and insulation of both foot and leg, which is particularly important in the cold store sector. wellington boots are produced on purpose-designed high or low pressure machinery with separate injection of leg and sole.

footwearDirect-molded production

the direct-molded process allows manufacturers to produce a fully assembled shoe in one step. the inherent adhesive property of polyurethane is used in combination with a shoe upper in a closed mould. this process is typically used for reaction injection PU but can equally be used for aVaLoN tPU as well as for smartLite®.

Using the direct injection process, the shoe maker can adjust the color, density and hardness of the sole and produce multi-layer soles (three colors and densities) in one step, on a single machine.

Sole weight versus performance

Desma roundtable Machine for Direct Injection

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Polyester or polyether ? Huntsman supplies a range of poly-urethane systems based on both polyester and polyether technolo-gies. the choice of technology is usually determined by the per-formance requirements of the end product.

Polyester systems are characterized by superior strength and abrasion resistance. these properties combined with excellent processing benefits make them the ideal choice for safety footwear, high performance casual shoes and high productivity unit soles.

Polyether systems on the other hand have an inherent resistance to hydrolysis and microbial attack making them ideally suited to many midsole applications as well as unit soles and sockliners. they generally produce higher definition soles with fewer air bubbles and a rubber-like look and feel. In addition, safety boot midsoles combined with aVaLoN tPU or rubber outsoles have proved popular with certain types of safety and military footwear.

Dual density soles combine the benefits of a hardwearing outsole with the comfort and lightness of a low density cushion midsole. the outsole is molded first or a previously molded sole is placed into the mould. the polyurethane midsole is then injected or poured on top. In the case of an integrated polyurethane process this is done without further preparation of the outsole. where the outsole is tPU or rubber, an additional heat activation step is usually included to ensure consistent bonding between the layers. In the case of aVaLoN tPU, perfect bonding is achieved without the need for priming, roughing or halogenation.

TPU Huntsman provides a full range of thermoplastic polyurethane grades under the aVaLoN tradename. Known for their high durability and aesthetics, aVaLoN tPU grades can be supplied from hardnesses as low as 55 Shore a for unit soles up to 65 Shore D for top-pieces and sport shoe stabilizers.

aVaLoN Soft : a range of soft, durable injection moldable materials suitable for unit soles or combining with polyurethane midsoles to produce hardwearing dual density outsoles. aVaLoN Soft grades are also ideal for molding logos, inserts and decorative trims.

aVaLoN Perform : a wide variety of grades where the emphasis is on performance. widespread use in soccer plates, top-pieces, stabilizers, in-line skate shells and outsoles whereaVaLoN Perform grades exhibit exceptional abrasion resistance and low temperature performance, are easy to process and give long term durability.

aVaLoN Crystal : this range of transparent grades is suitable for applications from sports plates to casual shoes and logos. aVaLoN Crystal grades show a high degree of transparency up to 6mm in thickness and are stabilized against premature color degradation from sunlight.

aVaLoN reflex : designed for the sports industry offering a relatively high degree of stiffness compared to normal tPU grades, the aVaLoN reflex range is available in a range of hardnesses from 37 Shore D to 60 Shore D. the unique properties allow the producer to reduce the thickness of parts whilst maintaining a high degree of rigidity

Polyether systems combine an inherent resistance to hydrolysis with excellent pattern definition.

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footwearsmartLite®

smartLite® offers today’s footwear brands a combination of durable, good-looking and comfortable soling with outstanding slip resistance at a weight up to 50% lighter than rubber soles.

smartLite® combines :• Comfort through lightness and softness• Durability from thermoplastic polyurethane technology • Versatility and uniqueness for exclusive designs• anti-slip through surface roughness down to micron level

smartLite® has been highly successful in the high quality casual and fashion arena. further developments to improve the comfort and combine additional features such as antistatic properties have created additional opportunities in the sports, safety footwear and outdoor leisure markets.smartLite® is an easy to use one-bag solution. It can be combined with many other soling materials, such as compact aVaLoN tPU, to create special effects including multi-colors or densities.

Careful development and choice of raw materials means that smartLite® soles can be used as an approved component in eco-label footwear.the thermoplastic nature of smartLite® makes it fully recyclable in the production process. Production waste and sub-standard moldings may be re-granulated and used back in virgin material.Since the molding of smartLite® soles does not require the application of external release agents, there is no need for post-mold washing or degreasing.

www.smartlite.biz

smartLite® technology offers consumers and brand owners a unique anti-slip solution. the microcellular nature of

smartLite soles improves the slip performance even in the wet, an attribute that actually gets better with wear.

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smartLite® soles are easily and reliably bonded to most upper materials with minimal preparation.

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aVaLoN Duo is the Huntman terminology for combining the benefits of a hardwearing aVaLoN tPU outsole with the lightness and comfort of a reaction molded polyurethane midsole in a single operation.

aVaLoN tPU is cast or injected into the outsole mould. thicknesses down to 0.5mm are possible in a casting process. after a short cooling period, typically less than 60 seconds, the mould is opened and liquid PU is either injected or cast directly onto the freshly moulded tPU surface. the upper can be incorporated at this stage to produce a direct molded shoe or a unit sole can be produced for later assembly.

aVaLoN Duo helps to create original, cutting-edge footwear designs, enabling the shoe producer to penetrate the high quality end of the casual and safety footwear markets. efficiency is also key as the production process can be achieved in one step.aVaLoN Duo : a superb alliance of design, performance and comfort.

footwearaVaLoN Duo the perfect combination

abrasion resistance (DIN 53516)

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Key Benefits

Performance • abrasion resistance• Cold flex properties• Slip resistance • Good adhesion to upper• antistatic options

Comfort• Shock absorption• Lightweight• Insulation

Design • Perfect surface definition• Matt or glossy effects• wide color range• transparent grades available

Plus Rubber-like look & feel

Applications• Casual and fashion• Safety and military• Hiking boots• Sports shoes

footwearaVaLoN Duo the perfect combination

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footwearworking shoes

whether they are cowboy boots, wellington boots, or boots for the construction site, working feet require footwear built to withstand very specific environments. International standards for safety shoes are very precise and polyurethanes meet the requirement for resistance to abrasion, oil and solvents while providing excellent resistance to slip and flexural fatigue.

In recent years, the work shoe has become more sophisticated with aesthetics providing a balance between the primary consideration of function. the expanded structure of microcellular polyurethanes means that they are almost three times lighter than other elastomer soling materials and molded soles can be produced in a wide range of colors. today’s working man and woman can now enjoy softer grades of shoe soles with a higher level of comfort, thermal insulation and energy absorbing properties.

In the manufacturing process, shoe soles can be direct molded onto uppers. If the bottom of the sole requires enhanced mechanical properties, a thin layer of almost compact polymer is molded in combination with a midsole to create a dual density sole which is light, comfortable and hard-wearing.

for the ultimate in durability and design Huntsman introduced the aVaLoN Duo concept to industrial footwear combining the advantages of a tPU/PU combination.

Polyurethane wellington bootsaimed primarly at the construction, agricultural and cold

store worker, polyurethane wellington boots offer good flex properties right down to low temperatures; tough,

hard-wearing, improved anti-slip outsoles; oil, micro-cellular biological and hydrolitic resistance; and

insulation of both foot and leg, which is particularly important in the cold store sector. wellington boots are

produced on purpose-designed high or low pressure machinery with separate injection of leg and sole.

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Serious sport enthusiasts and professionals require footwear which will both protect and enhance performance. Microcellular polyurethanes are the ideal material for producing high quality midsoles, which reduce the risk of leg joint and muscular injury without impeding performance. In addition, the ability to encapsulate inserts within the mould has allowed leading sports shoe manufacturers to enhance cushioning by inserting energy return devices into the midsole.

the versatility of polyurethanes enables extremely high performance systems to be developed which can provide the required combination of energy absorption and return.

Some of the world’s best football shoes demand the performance provided from aVaLoN Perform. Improved abrasion grades are used on the integral studs, resulting in improved durability on aggressive playing surfaces.

transparent grades from the aVaLoN Crystal range of thermoplastic polyurethane bridge the gap between fashion and function in exciting designs.

footwearSports shoes

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