DESMA House Fair 2014 - Polyurethane brings a revolution in shoemaking

Developments in robotics and automated machinery may have been the focus of this year’s Desma house fair but polyurethane was the material of choice for its innovative QuadWrap trainer.

Jane Denny reports.

Around 50 exhibitors used the 2014 Desma House Fair to promote innovative applications for polyurethane and developments in processing materials or equipment for shoe manufacturing.

Desma showcased its revolutionary QuadWrap trainer, a new kind of footwear made from two different Bayer MaterialScience (BMS) polyurethane systems.

It was around 2012 that the machinery maker approached Bayer MaterialScience with its idea of creating a shoe. The chemical giant considered its range of thermoplastic polyurethanes before engineering newer grades of existing products for the shoe.

BMS' Baytec is a polyurethane-urea material used to protect wastewater tanks from corrosive compounds and as such, its durability is assured. According to Bayer, a Norwegian fishing boat deck sprayed with Baytec in 1967 was intact and corrosion-free 17 years later. Recently, a new Baytec grade was chosen for the Volvo car hood. According to publicity material produced for the hood, the two-part PU system increases elasticity, which can cushion the impact in the event of a collision.

Bayflex is used in to make interior panels for the automotive market as well as agricultural and construction equipment, according to its technical data sheet.

Because the trainer is produced as a one single part, the process involves no bonding or manual stitching. From start to finish, the entire trainer – minus its necessary laces – is created by four steps on one machine. According to Desma’s technical manager Karsten Stoebener, it can produce a trainer in around three minutes.

At the time of going to press, Soebener said the company had entered into negotiations with big brands for projects with the shoe. Desma is currently working on moulds and running production tests for these projects, Stoebener said.

“QuadWrap samples could find their way onto retail desks as early as next year and when people pick up the shoe, they cannot believe how light it is,” he added.

Current shoe production trends 

The production of just one shoe by traditional methods, according to Desma, can involve up to 360 separate processing steps.  That can be a labour intensive process, requiring precision in each step, which is not always guaranteed in traditional mass manufacturing methods.

Furthermore, traditional mass manufacturing relies upon a skilled but cost effective workforce explained ceo Christian Decker. Decker was delivering his keynote presentation at the event, which was held in September at the Germany-based company’s site in Achim.

Decker told delegates that some Chinese firms experienced 100% staff turnaround each year and that the availability of China’s working age population was dwindling. It has fallen by 30% over 20 years.

Decker said the development of technology for the QuadWrap Trainer, which was specially designed for automated manufacturing, shows “current technology which can be switched immediately into reality of urban production even in highest labour cost environments such as downtown Shanghai, Paris or New York.”

The technology offers a reduction in a company’s carbon footprint and the elimination of large warehouse space, added Decker.

Automated shoe production value

Stoebener said the development offers the possibility of dramatically reducing labour requirements for mass shoe production due to the fact that only one or two operatives are needed at the machine.

Instead of a typical shift of 200 workers producing 1200 athletic shoes in an eight-hour shift, the same number of Quadwrap shoes can be made in 24 hours by bare minimum of workers.

He said the company had calculated the time a person takes in minutes to make a pair of shoes at around 80 minutes/pair.

QuadWrap, which Desma worked on for a year with Bayer MaterialScience, offers a solution to rising labour costs in Asia. Wage costs are currently rising at 10% to 20%/year said Stoebener.

He added that the development could enable the reshoring of footwear manufacturing to countries where wages have not been as low as they have been in Asia. The opportunity is greater when import/export processes are eliminated from the cycle, he added.

“The complete shoe – sole and upper – is produced by polyurethane casting and injection moulding,” said Stoebener.

“The PU layers of shoe are joined in the production process – avoiding adhesives and volatile organic compounds,” he added.

The production of Desma’s QuadWrap concept shoe was demonstrated on a specially adapted machine at the housefair. It was the demonstrable success of Desma’s proprietary automated material flow with integrated robots (AMIR) technology that inspired the QuadWrap trainers’ development.

AMIR is already used in advanced footwear factories worldwide said Stoebener. Its advantages include high production output, improvement to the quality of the shoe produced and low production costs, he said.

The micro dosing unit used to inject the polyurethane is a 5-valve head and mini-flush mounted on a robot arm. The unit was developed and built at and Desma. According to Stoebener, the machine’s 6-axis robot is also suitable for multi spot casting and its throughput is between 1g and 8g/second.

Also, the concept can be developed to suit a number of types of shoe and the polyurethane offered in a variety of colours, said Stoebener.

“We wanted the industry to wake up to the idea that there is much more that can be done in the production of shoes than just making soles with polyurethane,” he added.

 The Bayer MaterialScience PU system in the QuadWrap trainer

The QuadWrap Concept trainer has been created from Bayer MaterialScience polyurethane systems.

Karsten Mueller, marketing manager at BMS, said Desma approached the firm with the idea of creating a concept shoe two years ago.

The shoe’s cast elastomer production process uses a Baytec polyurethane elastomer for the more rigid elements of the shoe.

Bayer’s Bayflex S was chosen for the QuadWrap’s sole and shaft elements. Mueller said the Bayflex S formulation has a density of 220kg/m³ – (13.7 lbs/cu ft). It is this which renders it such an advantageous alternative to the lightweight material EVA - ethyl vinyl acetate – which has traditionally been used to make the soles for shoes.

According to Mueller, QuadWrap shoes can be produced using a physical blowing agent – for smaller production schedules – or through CO₂ lightweight technology.

The shoe’s inner frame is made from Baytec 89-500. This high strength material has an adjustable Shore hardness (A 65 to A 90), “excellent flow and mould filling properties” as well as a short curing time,” said Stoebener.

Its upper frame and mid-sole is made from Bayflex 98-100. The material forms a “dense skin” that offers excellent hydrolysis stability and is also UV-stable, according to Bayer MaterialScience’s promotional brochures.

The shoe’s out-sole pads are made from Baytec CC 85-103 which offers excellent abrasion and slip resistance with a short curing time.

Two sets of moulds allow production on a single machine.

The polyurethane was tailored to meet the requirements of each element’s function, said Mueller. According to him, it is the tensile strength of the first layer that allows for comfortable fastening. Meanwhile, he said, the abrasive quality of the trainer’s outsole pads will help to prevent slips and falls.

“This dual density system combines to make the trainer’s external structure extremely lightweight, flexible and shock absorbent,” added Mueller.

Lightweight sole innovation

Footwear platform manager EAME and India at Huntsman, Johan van Dyck told delegates that PU offered a lightweight solution closer to EVA than any other material used in sole production.

Huntsman has recently developed two types of polyurethane for soling, he said.

Daltoped Grip, which is new this year, and Daltoped Lite, developed in 2013, offers the “best suitable EVA replacement,” said van Dyke.

He said Huntsman had rolled out a state-of-the-art footwear development centre in Belgium and that the company’s latest investment was a Desma RGE 4011 machine. This is a four-station round table TPU casting/injection unit, which it installed around a year ago

He said currently, only 5.5% of shoe soles were made with polyurethane, compared with 24% vulcanised rubber and 8% EVA. For TPU the figure is 1.5%. However, van Dyke also said that the footwear industry was growing at a faster rate than the world’s population.

Comparison of an injection moulded EVA sole and a Daltoped Lite sole, he said emphasises how much easier it is to bond and process polyurethane, and less expensive to make moulds than for EVA soles.

Desma house fair co-exhibitors  

Polyurethane-focused businesses exhibiting at the event included North American military shoe manufacturers, LP Royer and Rocky Brands.

The latter, based in Nelsonville, was awarded a $14.9m contract modification by the US Defense Logistics Agency Troop Support for hot weather combat boots for army soldiers and marines.

David Dixon, Rocky Brands senior vp, manufacturing and distribution operations, told utech-polyurethane that the fair had, as usual, presented many new thoughts and ideas to him as a delegate.

Dixon said: “The QuadWrap project was interesting and I had Desma send me a sample to show our development department. The team was very impressed with it and it definitely started them thinking of ways to incorporate this into our hunting or hiking concepts.

“The idea of making a complete polyurethane shoe with little to no labour required for lasting or finishing is very appealing, especially in higher wage markets such as the US,” Dixon added.

LP Royer, as utech-polyurethane.com reported in the days after the house fair, is currently fulfilling a contract to produce 72,000 pairs of boots for the US military to use from next year.

A UK firm was invited to exhibit its innovation in protective headwear at Desma’s house fair. D3O, based in Brighton, has developed what it claims is a high shock-absorption helmet liner.

The polyurethane material’s molecules lock together upon impact – thereby providing the protection. In standard conditions, the material flow freely rendering the molecules flow freely, rendering the material soft and flexible. Utech-polyurethane.com reported the innovation, and its testing processes, at the time.