Polyurethane in the area of refrigeration

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The main focus of attention for polyurethane (PU) in the area of refrigeration has up to now been chiefly in relation to insulation. In the shape of its coolpure 1.0, BASF Polyurethanes has introduced a refrigerator concept that displays further potential applications for the material, coupled with the use of further unusual plastics solutions. All the user needs to worry about is filling it up.

The initial idea as far as the coolpure 1.0 concept was concerned was to approach in a completely new way something old and familiar, a piece of household equipment that has barely changed over time in terms of its shape and colour. The concept is intended to provide stimuli for the design and application of materials, not only as regards refrigerators but also for other domestic equipment, kitchen cupboard fronts, washing machines or furniture. Hence there is also an emphasis on decor: in the case of the coolpure 1.0, both the external surface and the inner surfaces, including the bottles shelf, are covered with Permaskin film. Compounds for the manufacture of white films or those coloured all the way through and based on TPU for finishing 3-dimensional components, serve to protect surfaces and can be used for a wide range of substrates such as wood, metal, plastic or even rigid PU foam. They can even be used on different surface structures and geometries or complex contours (the possibilities reportedly include drawer handles and grip recesses as well as undercuts). Back printing of these long-term resistance, transparent films with wooden or technical decorative finishes is said to be possible without any problems. The solvent-free approach to processing calls for minimum tooling costs and incorporates only a few operational stages.

concept fridge

The concept fridge demonstrates the versatility of polyurethane and its diverse fields of application (photos: BASF Polyurethanes)

Economical, soft light with flexible conductor optic

As a visual highlight, the shelves of coolpure 1.0 light up with light from rear-mounted LEDs, which is emitted at the cut surfaces. The internal illumination and the external “ambient light“ have been achieved by means of a flexible light conductor made from Elastollan. The use of special aliphatic isocyanate gives crystal clear products that only dim the light to a very small extent. Due to its flexibility by comparison to other materials Elastollan offers a number of possibilities for configuration when it comes to shape and colour and can be adapted to any contour. By overprinting of reflective surfaces (inkjet) or structuring the surface, targeted control of the light (decoupling) can be achieved.
Optimised insulation

Rising standards in energy efficiency in refrigerators demand an increasing improvement in insulation. Vacuum insulation panels (VIP) offer an attractive solution. Fixing them with an adhesive strip (the standard solution) is not the best way of going about things as, up to now, it has only been possible to mount them manually on flat surfaces. The PU foam Balindur is reportedly offering a new type of solution for this, as it has not only has an adhesive effect but also smoothes out any unevenness of the substrate. The special feature here is that it is not only possible to attach the vacuum insulation panels to the side walls, but above all the fact that they are fixed to the inliner on the fridge door. The VIP fixing is said to prevent the panels being visible on the outside wall or the development of any delamination. The positioning ofthe VIP on the inliner may be instrumental in improving the energy efficiency of the refrigerator by up to 4%. In this way the new PU system will make a higher level of automation in production possible and is capable of ultimately reducing costs.

Elastopor H, an open cell PU rigid foam, is said to be suitable as a core material for VIPs due to its low density and its high pressure resistance. It can be manufactured in the form of sheet material with precise contours and can be processed without any problems. In addition, the PU rigid foam is easy to recycle.

In the shape of Elastocool Advanced, the company is showcasing a new generation of well-known PU rigid foam systems featuring optimised characteristics. It has proved possible to reduce heat conductivity, and this makes a reduction in energy consumption possible. The advantage of Elastocool Advanced does, however, lie predominantly in relation to production: the shortening of demoulding time which increases the capacity of the foam moulding plant and ensures greater flexibility in the production process. In addition, the pressure resistance of the system is increased and this makes a reduction in the density and thus the consumption of material possible.

Resistant sealing profiles

Furthermore, thermoplastic polyurethanes with good resistance to hydrolysis, low temperature flexibility and resistance against micro-organisms have come to be used for the extrusion of profiles and seals. These plasticizer-free sealing profiles can be used in continous seals as surrounds.

handle element

Detail of handle element

Soft touch door handles

A light-resistant TPU has been identified which makes it possible to produce surface reproductions that are accurate in every detail. The soft, aliphatic Elastollan, a TPU with a good flow rating, is also pleasantly soft to the touch. A further convincing feature is its resistance to abrasion and scratching as well as its resistance to a wide range of external influences. It has also proved possible to make savings in terms of additional spraying applications.

Drawer compartment on coolpure

Drawer compartment on coolpure

High transparency shelves

The shelves are made from thermoplastic polyether-polyurethane and stand out as a result of their resistance to hydrolysis and low temperature flexibility, whilst at the same time demonstrating a high level of rigidity and resistance to micro-organisms. A further feature is their high transparency, including also increased wall thickness, plus an abrasion- and scratch-resistant surface. And a further additional visual effect – the shelf is illuminated because light streams in from behind due to LEDs and subsequently emitted at the cut surfaces.

Freedom of design for seating elements

For those who would rather not stray too far away from their refrigerator, the coolpure 1.0 incorporates seating elements that feature a range of variable adjustments designed to meet individual requirements. With its flexible (and at the same time elastic) characteristics, Elastoflex I incorporates a high level of seating comfort, linked with pleasing haptics, good skin formation and resistance to abrasion. The material‘s flow characteristics make the reproduction of fairly complex structures a possibility and make a unit of furniture out a purely functional refrigerator.

Window spray technology

There is a further special highlight hidden away in the top of the freezer drawer and that is “Window spray technology“, also known by the name of Colofast WST. This is a glass-encapsulation material for pressure-free application to glass panes in an open mould which combines sealing and edging in one.

 

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