Thursday, March 29, 2012

Neoprene Rubber Phenolic Resin Adhesive

Neoprene rubber, more particularly in the form of a solution than as a latex,  in a well known cold setting contact adhesive but when it is used in conjunction with a phenolic resing and hot cured it comes into a higher strength class. The first two polymer structural adhesive used on a commercial scale for bonding metal was probably of this type. In recent years, however, it has been superseded in importance by nitrile rubber and polyvinyl acetal as the thermoplastic component in two polymer adhesives.

A number of types of neoprene polymer are available but many of these differ more in their additives than in the structure of the basic polymer. Thus there are grades that can be cured or vulcanized under different conditions, some at room temperature. But the properties that are important when the rubber is used in conjunction with a phenolic resin are compatibility with the resin and solubility, there related properties will be considered as one.

The solubility of neoprene varies recording to the type of polymer, and especially with the ratio of sol and gel. Neither sol nor gel are easy to define but in this contest the effect they produce may be considered as that resulting largely from different length of polymer chain. Some polymer chains can be shortened by mechanical processes. In its substantially gel form, neoprene is practically insoluble.

The grades of neoprene commonly used with phenolic resins are those known as AC and AD. Both of these are soluble not only in hydrocarbons such as toluene but also in certain mixture of toluene and ketone especially methyl ethyl ketone, and other polar/non polar solvent such as ethyl acetate and hexane.