Permali Gloucester

Processing Guidelines

Tuftane TPU films are easy to work with using traditional techniques for combining, converting, and finishing of plastic and rubber materials.

Techniques include the following:

Adhesive Laminating

Oven lamination, multiple can lamination, large drum lamination, and sometimes a combination of these techniques are popular for combining Tuftane TPU film with similar or dissimilar materials, usually woven and non woven textiles, to create a composite laminate with a wide range of properties.

Acrylic, latex, and silicon adhesive systems are popular, and solvent-based adhesives are also used.

Application of the adhesive can be achieved by many methods, two common methods being Gravure adhesive coating or reverse roll coating. The method used, the substrate the adhesive is applied to, and the type of adhesive used will all influence the soft hand, strength, and appearance of the laminate.

Tuftane TPU film used in this manner is usually of a thin gauge (25 – 50 µm), soft, and extensible which can present handling problems. Experience indicates that good tension control, film support, and braking systems help in avoiding problems originating from wrinkles in the film.

Correct curing time and temperature of the adhesive is critical in ensuring maximum bond strength, washing and dry cleaning durability.

Heat Laminating

Heat and pressure can be used alone to bond Tuftane TPU film to most substrates. By melting the Tuftane TPU at temperatures approaching 200°C Tuftane TPU becomes a high strength hot melt adhesive film. The film is extremely sticky and has little strength at this temperature so care must be taken with what surfaces the film may come into contact with. Nip rollers should be Teflon or Silicon Rubber coated.

Heat lamination is useful for thicker films (125 to 250 µm) or as a first step in bonding two substrates together using heat and pressure.

Flame Laminating

Flame laminating or bonding is a popular method for bonding Tuftane TPU film to urethane foams. The method is fast and reliable and involves the use of an open flame to melt the surface of the urethane foam, creating an adhesive layer for the film to bond with under light nip pressure.

Solvent Bonding

Solvent bonding is a useful technique for joining Tuftane TPU films with other polymers and fabrics which may be sensitive to heat. Tuftane TPU film is treated with a solvent (such as THF) which swells and softens the surfaces and by applying pressure to the joint and with the evaporation of the solvent, the two surfaces bond. Adhesives are not used.

Thermoforming

Thermoforming, also vacuum forming, is a mature technology for moulding Tuftane thermoplastic polyurethane films in the same way many other plastics are thermoformed. The technique remains popular as tooling costs are comparatively low, as are the pressures required, which keep product concept to completion times scales short, and thin walled items are easy to achieve.

Moulds can be made from a variety of materials, typically aluminium or epoxy.

The process involves clamping a sheet of Tuftane TPU over the mould and heating the film to a temperature of approximately 120 -130°C. The forming begins by removing the heat from the Tuftane TPU film and applying pressure and / or a vacuum to force the contact of the mould and the film. The Tuftane TPU film is then cooled in-situ then removed from the mould.

Cutting

Tuftane TPU film can be cut using most conventional cutting methods such as shear cutting, die cutting, punching and stamping. Flat bed CNC cutting machines are used to quickly produce large volumes of complex patterns.

In roll form Tuftane TPU should be converted using a re roll / slitting operation. Crush cutting, razor cutting, and shear cutting can be utilised depending on the grade and thickness of film being handled.

Heat Sealing

Heat sealing is a simple process for joining Tuftane TPU film by using heated bars to apply pressure to the substrates being formed until fusion has occurred.

Radio Frequency (RF)

RF Welding, also known as High Frequency (HF) or Dielectric Sealing, it is a very fast, consistent method of joining or sealing Tuftane TPU film where a weld line is produced that is as strong and flexible as the original film. This type of welding is used to join Tuftane TPU films used in a variety of industries where a strong consistent leak-proof seal is required.

The methodology involves placing two pieces of material on a table press that applies pressure to both surface areas. Dies are used to direct the welding process. When the press comes together, high frequency waves are passed through the small area between the die and the table where the weld takes place. This high frequency (radio frequency) field causes the molecules in Tuftane TPU film to vibrate then melt. The combination of this heat under pressure causes the weld to take the shape of the die.

Ultrasonic Welding

Ultrasonic welding is a similar welding technique to RF welding whereby high-frequency ultrasonic acoustic vibrations are locally applied to Tuftane TPU films being held together under pressure to create a weld. It is commonly used for Tuftane TPU film when thin weld lines are required or when Tuftane TPU film to dissimilar materials.

Printing

Tuftane TPU films have a low surface energy and printing on to them can be tricky if the inks used do not contain the correct solvents. Small scale trials should be undertaken to ensure the print has sufficient adhesive strength and is of an acceptable quality for the Tuftane TPU film being considered.

Traditional methods such as ink jet and pad printing can easily be applied to Tuftane TPU film once the correct ink has been identified.

Embossing

Tuftane TPU film and coated fabrics can be embossed with relative ease. By heating the film / substrate to temperatures of around 150°C using an oven or calrod heaters. The emboss roll temperature should be maintained at around 50°C. For thinner Tuftane TPU film the temperature and pressure between the emboss roll and the rubber nip roll will need to be carefully controlled for subtle patterns.