Detailed Product Description

 

One of the most versatile of all plastics is perhaps the polyurethanes. They can be formulated hard or soft, solid or foamed and they are used in a lot of different applications. The polyurethanes can be divided into the following main groups of materials.

-          Rigid foams

-          Flexible foams

-          Microcellular foams

-          Coatings, Adhesives, Sealants and Elastomers (C.A.S.E)

EXPANCEL microspheres are used in most of these areas.

WHAT IS EXPANCEL?

EXPANCEL microspheres consist of a polymeric shall encapsulating a blowing agent, which is a hydrocarbon.

EXPANCEL microspheres can be delivered unexpanded, EXPANCEL DU, or expanded EXPANCEL DE. Unexpanded microspheres are white, spherically formed particles with a mean particle diameter of 10-16 microns.  When heated the polymeric shell gradually softens, the liquid hydrocarbon starts to evaporate, thus expanding the microspheres.

The pre-expanded microspheres are expanded to a very low density, the lowest being 30 kg/m³. The mean particle size is 40 microns.

WHAT IS UNIQUE ABOUT EXPANCEL?

Ultra low density

Even small amount of EXPANCEL DE give a considerable weight reduction. It is impossible to get a drastic reduction of the density of a cast elastomer with many other microspheres. The viscosity increase soon prohibits further additions. Thanks to the extremely low density of EXPANCEL DE a reduction of the density of the polyurethane is possible far beyond what heavier microspheres can achieve.

Elasticity

EXPANCEL DE withstands hard mechanical process. EXPANCEL DE will remain intact due to its elasticity.

In flexible polyurethanes the elastic EXPANCEL microspheres do not break during bending, thus giving the material good mechanical properties.

Size

In comparison with many other light weight fillers EXPANCEL microspheres are very small.

Some of the properties that are effected by adding microspheres

Foam Structure

Compression set

Density

Surface properties

APPLICATIONS

Rigid PU foams

EXPANCEL DE microspheres are used in a variety of rigid polyurethane foams, for example, simulated wood, such as decorative crown mouldings, sound and vibration damping and model making materials. The microspheres in these foams produce a closed cell structure that is very uniform compared to conventional foams. These polyurethanes are typically made from two component systems. The EXPANCEL DE microspheres are generally added and premixed into the polyol component.

For the application in the model making materials, the addition levels of 1-3% of EXPANCEL 551 DE 40 d42 or EXPANCEL 091 DE 40 d30 are recommended. This provides good machineability or workability of the model materials with improved weight reduction.

Microcellular foams

In microcellular foams in applications such as shoe soles, an addition of EXPANCEL DU creates a durable foam with reduced density and improved foam structure when expanded. The spheres can be premixed with the polyol or mixed to a paste with some other liquid component such as a plasticizer and be added directly to the mixing head.

Microspheres with as low expansion temperature as possible are preferred. A use of slow catalyst in the PU system is a beneficial in order to give

the spheres time to expand. EXPANCEL 053 DU 40 is recommended in these types of pplications.

Coatings

 

EXPANCEL DE and WE are used to improve thermal insulation and to reduce density. We recommend EXPANCEL 551 DE 40 d42. An addition of approximately 3% of weight will cut the density to half the density of the solid polyurethane.

For surface modification or surface effects smaller amounts of spheres are required. Both pre-expanded and unexpanded grades could be used depending on the process. For this purpose EXPANCEL 091 DE 40 or EXPANCEL 051 DE 40 or the unexpanded versions of these could be used.

Adhesive and sealants

EXPANCEL DE can be used in sealants to reduce density and raw material costs.

EXPANCEL DU can also be used as a debonding agent by adding them to an adhesive without expanding them. When the product is heated afterward the microspheres expand and the detail will thereby de-laminate.

In sealing strips the compression set recovery is improved since the microspheres rebound to original shape on removing applied pressure.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Elastomers

In cast elastomers EXPANCEL DE can be used to reduce density and cost.

Thermoplastic elastomers

In thermoplastic elastomers TPU EXPANCEL DU are used to reduce density and improve compression properties.

Depending on processing temperature EXPANCEL  092 DU 120, EXPANCEL 093 DU 120, EXPANCEL 095 DU 120 or EXPANCEL 098 DUX 120 could be chosen. Addition should be between 1 5% of weight.

All of the mentioned grades of EXPANCEL should only be seen as first choice recommendations. In special cases other grades may be more suitable.