Polyurethanes 

Polyol

The name polyoles is given to a group of organic compounds containing several hydroxyl groups (-OH). They are the primary reactants of isocyanates. Polyester polyoles or polyether polyoles are used in manufacturing polyurethane.

 

MDI

Methylene diphenyl diisocyanate is an essential raw material for PUR applications or insulating foams.

 

TDI

Toluene diisocyanate (TDI), especially 2,4-TDI, is one of the most important isocyanates, and an important intermediate product of the plastic industry. Apart from other isocyanates, TDI is an ideal base substance for polyaddition reactions, and is primarily used for manufacturing foams (polyurethanes).

 

Resins, hardeners

Resins are more or less liquid products composed of different chemical substances, and are for instance used for manufacturing paints, soaps, drugs and turpentine. In the industrial sector, primarily synthetic resins are used. Applications, in which the solidity providing and adhesive characteristics are used, like for adhesives and glues, are typical. Another typical application is the use for finishing and sealing of surfaces, but also the use for moulding.

 

According to DIN 55958 (from December 1988), synthetic resins are manufactured by polymerisation, polyaddition or polycondensation reactions. Synthetic resins are usually composed of two primary components. Mixing both components (resin and hardener) provides the reactive resin bulk. Viscosity increases while hardening, and once the hardening process is completed, you’ll obtain an infusible (duroplastic) plastic material.

 

Synthetic resins (or short resins) are often processed in casting processes. The casting resin is poured into a reusable or lost mould, in this case.

In most cases, pourable bulk materials, which are processed in a warm moulding process including an immediately following irreversible hardening process at increased temperatures for obtaining moulded parts and semi-finished products, are called hardenable moulding compounds. In this process, often high pressures are required for completely filling the mould.

 

Binders

Binders are substances, by means of which solid materials separated into fine consistency grades (e.g. into powders) are glued with each other or glued on top of a substrate. Binders are in most cases added in liquid form to the filler substances to be bound.

 

Both substances are mixed intensely, so that they distribute evenly and that all particles of the filler substance are evenly moistened with the binder. By selecting a certain type of binder, the filler substance can be provided with new processing and material characteristics.

 

Glues, bitumen

Bitumen is a naturally existing material appearing in different types of rocks and almost nonvolatile. The so-called mineral pitch is an adhesive and sealing substance, and shows elastoviscous characteristics, depending on the temperature. In toluole, bitumen is almost entirely soluble. By using the vacuum distillation process, bitumen can also be derived from oil.

 

This material is for instance used in order to protect sensitive materials from water, since bitumen is practically insoluble in water. It is chemically nonreactant to non-oxidising acids and bases, but strongly reacts with oxygen in the event of a fire.

 

Bitumen primarily consists of high-molecular hydrocarbons and contains, apart from them, chemically bound sulphur, oxygen, nitrogen and some traces of metals. As a thermoplastic substance, it becomes brittle when chilled, and runs seamlessly through all states from solid via semifluid to thin fluid when heated. With increasing temperatures, it slowly starts to disintegrate. It has no clearly determined melting point, since the components of this hydrocarbon mixture have different melting points.

 

Acids and bases

In the narrower sense, acids are all compounds able to transmit protons (H+) to a reactant – they can also act as proton donators. In a watery solution, the reactant is basically water. Hydroxoniums (H3O+) are formed and the pH-value of the solution is decreased, as a result.

 

Acids react with so-called bases (alcaline solutions or so-called lyes are in the narrower sense watery solutions of alkali hydroxides, like for instance of sodium hydroxide (caustic soda) or of potassium hydroxide (caustic potash). In the broader sense, the term is also used for any solution of bases.) under formation of water and salts. That means, a base is the counterpart of an acid and may be able to neutralise it.

 

Activators

An activator is a substance in biochemistry, which accelerates catalytic reactions, but in itself is no catalyst.

 

Catalysts

A catalyst in chemistry is a substance which influences the reaction speed of a chemical reaction without being itself consumed in that process. This happens by reducing the activation energy. Catalysts change the kinetics of chemical reactions without changing their thermodynamics. They accelerate the chemical forward reaction and backward reaction likewise, and as a result, don’t change anything in the equilibrium of a reaction.

 

Fire protection

Fire protection agents (or fire retardants) are substances which restrict, slow down or prevent the propagation of a fire. Fire protection agents are applied in all those cases, where potential sources of ignition are present, amongst others in complex plants of the resin manufacturing and chemical industry.