Epoxies polyglycol

Glycidyl ethers of aliphatic polyols based on polyglycol, glycerin, and other polyols are flexible epoxy resins. They are used as reactive diluents and flexibihzers for solvent-free epoxy resin formulations. Epoxy-polyglycol resins that are produced from the reaction of epichlorohydrin and polyester polyols based on ethylene or propylene oxide are the most common of these types of flexible epoxy resins. Examples of typical commercial aliphatic epoxy resins are shown in App. C. 

The aliphatic epoxy resins formed from reaction with hydrogen peroxide or peracetic acid include epoxidized polybutadiene, epoxidized soya or linseed oil, and epoxidized polyglycols. The resulting products have too low a functionality for use as base polymers. They are almost always used in combination with other epoxy resins to improve properties such as cure rate, flexibility, and heat deflection temperature. Therefore, these resins are often considered to be reactive diluents and flexibilizers. 

Special grades of glycidyl ether epoxies have been made with components such as glycerol, polyglycols, pentaerythritol, and cashew nut oil. Other epoxy-polyglycidol resins have been produced from the reaction of epichlorohydrin and polyester polyol based on... 

The polyglycol diepoxies are used primarily as flexibilizers and reactive diluents. Commercial products are available where n varies from 2 to 7. Generally, these are used in the range of 10 to 30 percent by weight with DGEBA or epoxy novolac resins to improve flexibility without a significant loss in physical properties. 

TABLE 4.4 Properties of an Epoxy Resin Formulation Based on a Blend of Polyglycol Diepoxy Flexibilized Resin and Standard DGEBA Resin, Cured with Methylene Dianiline5... 

Commercial products are available where n varies from 2 to 7. The flexible epoxy resins based on polyglycol also make excellent reactive diluents because they have a viscosity of 100 cP at 25°C. Table 4.4 shows the effect of two polyglycol diepoxides on the physical properties of a cured epoxy system. Another type of flexible epoxy resin is derived from dimerized unsaturated fatty acid, cashew nut oils, and other vegetable oils. Other flexible epoxy resins can be made with thiols, aliphatic acids, and hydroxyl-terminated compounds. Applications where flexible epoxy resins are valued include... 

Other anhydrides such as dodecyl succinic anhydride (DDS A) or adducts of DDS A with polyglycols, can also be used for formulating heat cured epoxy adhesives. These have excellent electrical properties and good thermal shock resistance. Anhydride cured epoxies are also useful for bonding plastics, notably polyester such as Mylar.8... 

Chem. Descrip. Polyglycol diepoxide epoxy resin CAS 25928-94-3... 

Figure 54 IR spectra of (a) phenol Novolac-type epoxide, (b) Ciba-Geigy s tetrafunctional epoxy resin, (c) alicyclic epoxide, and (d) polyglycol epoxide.

It has been shown that polyglycols (which are found in water-soluble fluxes) diffuse into the epoxy during soldering. This absorption has been shown to reduce electrical performance by increasing moisture uptake by the substrate. Jachim et al. were the first to link the use of polyglycols in soldering fluxes and fusing fluids to increased susceptibility to CAF formation. 

---