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The history of polyurethanes

The manufacturing method for making polyurethanes (PU) using the polyaddition method was invented in the year 1937, by the research team led by Otto Bayer. They succeeded in manufacturing polymers forming fibres, by using the reaction between aliphatic diols and aliphatic di-isocyanates. The first polyurethane rubbers were manufactured by Pinten in Germany in 1940. As a result of further research, the manufacturing of foams, coating materials and glues also became possible.

The use of polyurethanes is growing rapidly. Since the beginning of the 1980's, the use of PU has multiplied all over the world.

 

Finn-Valve Oy and polyurethanes

Finn-Valve Oy is specialised in the production of polyurethane elastomers (sometimes also referred to as urethane rubbers). We manufacture cast, vulcanised polyurethane elastomer products.

Finn-Valve Oy is the only company in Finland licensed by Covestro (former Bayer) to use the raw materials of Vulkollan®. Vulkollan is the perfect elastomer for heavily loaded dynamic and static applications.

 

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General information about polyurethanes

Polyurethanes is the general term for a large group of polymers, including very different material compositions, and thereby also very different properties. Polyurethane can be impermeable or porous, soft or hard, available in moulded pieces, films, coating materials, or layers. The most common applications for use are: soft cell foam in furniture and mattresses, semi-hard integral cell foam in car interiors, wall and roof element insulation in buildings, and technical insulation in fridges, for example. Approximately two thirds of all polyurethane in use is used for these four applications.  

 

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Polyurethane elastomers, characteristics

An elastomer is a large-molecule substance, which quickly returns to its original dimensions and shape after deformation caused by low pressure, and after the release of pressure.

Polyurethane elastomers have high strength, great wear resistance, great tolerance of gases, oils and aromatic hydrocarbons, and exceptional tolerance of acid and ozone, but in some cases, they can be prone to microbe attacks. High temperatures (>80 °C) combined with humidity can considerably reduce the lifespan of PU, due to the effect of hydrolysis, particularly when using PU mixtures based on polyester polyols.

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Raw materials


The ingredients used for manufacturing polyurethane elastomers can be divided into four main groups:

  • isocyanates
  • polyols, i.e. high molecular weight glycols
  • chain extenders, i.e. cross linkers
  • additives

The isocyanates are generally di-isocyanates, and mixtures of di-isocyanates of different values. The most widely-used di-isocyanates are MDI (methylene diphenyl di-isocyanate), TDI (toluene di-isocyanate), and NDI (naphthalene di-isocyanate). Di-isocyanates often arrive at the manufacturing company as a ready-made prepolymer mixture. In the prepolymer, the di-isocyanates and polyols have been mixed, and they have finished reacting to each other.

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VULKOLLAN® urethanes

The oldest and best-known urethane elastomer is trademarked as Vulkollan®. Vulkollan® is a registered trademark of Bayer MaterialScience AG. Despite having been on the market ever since the beginning of the history of polyurethane elastomers, Vulkollan has maintained its superiority to other types of polyurethane elastomers, thanks to the properties that have made PU-elastomers a breakthrough material:

  • load-bearing capacity in heavy dynamic use
  • wear resistance regarding abrasive wear
  • great tear resistance, particularly further tear resistance
  • very small hysteresis

The manufacturing process of Vulkollan is different from the manufacturing of other urethane elastomers, and it is not possible to use it in all possible applications. The most important characteristic (but not sufficient information for choosing a certain quality of urethane elastomers) is strength. The strength can vary between 10 Shore A – 80 Shore D. The main portion of use is concentrated in the strength range 65 - 95 Shore A.

In many cases, the wear resistance is multifold compared to steel and other elastomers.