Pre polymers

Prepolymers are used to produce polymers and are therefore precursors that can still be soluble and meltable.

Prepolymers are the precursors of polymers. It is a molecule made up of several building blocks that is not yet the size of a polymer. The prepolymer is usually a collective term for reactive oligomers from which polymers are produced.

The possible uses and applications are versatile. One example is the so-called aerosol cans with one-component insulating foam. They contain isocyanate and polyol that form a prepolymer. By shaking the can, the components mix and harden after application.

Prepolymer process

In practice, a polyurethane can be produced in two ways: in a one-step process by reacting a polyol with a polyisocyanate, or in a two-step process. The first step is the production of the prepolymer. In a second step, this reacts by linking the functional groups to form the desired polymer. New technologies use hardeners that cure certain prepolymers at room temperature, which saves energy and ultimately CO₂ emissions. This is an important point, since high energy costs are incurred in PU processing.

Prepolymer manufacture

The various raw materials, polyol and NDI or additives and MDI, are mixed in the reactor of the prepolymer plant to create a homogeneous mass. Thanks to the fully automatic dosing technology, all substances enter the system in the right amount. Depending on the recipe, the result is a wide range of high-performance polymers.

The decisive factor for the quality of the end products is the optimal course of the reaction, i.e. the temperature control and the exact mixing of the raw materials. The best possible point in time for further processing of the prepolymer in the process is also important.

Difference between polyurethane and prepolymer

A prepolymer is an intermediate product (polymerization equipment) produced from a polymerization reaction. It is formed from the joining of two or more monomer units. It is an intermediate compound, while polyurethane is the end product.

Prepolymers are therefore precursors in polyurethane production and, in contrast to the end product, can still be meltable or soluble. They are the starting point for block copolymers or for shaping before crosslinking leads to a duroplastic state as polymerization progresses. Two polymers that are combined to form one polymer in the future often carry at least two reactive functionalities that are identical. These only lead to the desired end product, such as polyurethane, after the prepolymers have been mixed during production.