Epoxide resins flexibilisers

They have found use as hardeners-eum-flexibilisers for epoxide resins (see Chapter 26) and are of interest in the production of thixotropic paints and adhesives. Related higher molecular weight materials are tough and flexible and find use as hot melt adhesives (Versalons). 

For a number of purposes the unmodified epoxide resins may be considered to have certain disadvantages. These disadvantages include high viscosity, high cost and too great a rigidity for specific applications. The resins are therefore often modified by incorporation of diluents, fillers, and flexibilisers and sometimes, particularly for surface coating applications, blended with other resins. 

Even though there are literally hundreds of different epoxide resins and hardeners commercially available, giving countless formulations with a diversity of cured properties, further modifications of a material are sometimes still required. These modifications can be achieved by incorporating a range of compounds known as diluents, flexibilisers and plasticisers into the epoxide resin system during the formulation process. The properties of some typical diluents, flexibilisers and plasticisers are now discussed. 

Flexibilisation of a formulation can also be achieved by using flexi-bilising curing agents or other additives. These materials are similar in their basic structures to the flexible epoxide resins and usually have reactive end groups separated by flexible long chain molecular segments. A typical example is dodecenyl succinic anhydride which has the structure... 

The polyfunctional flexibilisers are comprised largely of difunctional epoxides derived from molecules with flexible structures. The commercially available flexibilising resins are commonly based upon the glycidyl derivatives of glycols and dimerised acids. The general structure of an epoxidised glycol is... 

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