Glycidyl ether resins

The cycloahphatic products are generally Hquids of lower viscosity than the standard glycidyl ether resins. The peroxidized resins contain no chlorine and low ash content and their ring-contained oxirane group (cyclohexene oxide type) reacts more readily with acidic curing agents than the bisphenol A-derived epoxy resins. 

The epoxidation is generally conducted in two steps (/) the polyol is added to epichlorohydrin in the presence of a Lewis acid catalyst (stannic chloride, boron triduoride) to produce the chlorohydrin intermediate, and (2) the intermediate is dehydrohalogenated with sodium hydroxide to yield the aliphatic glycidyl ether. A prominent side-reaction is the conversion of aliphatic hydroxyl groups (formed by the initial reaction) into chloromethyl groups by epichlorohydrin. The aliphatic glycidyl ether resins are used as flexibilizers for aromatic resins and as reactive diluents to reduce viscosities in resin systems. 

It will be observed that in these cases hydroxyl groups will be formed along the chain of the molecule. The general formulae for glycidyl ether resins may thus be represented by the structure shown in Figure 26.5. 

Typical data for some commercial glycidyl ether resins are given in Table 26.2. 

Curing of Glycidyl Ether Resins 751 26.3 CURING OF GLYCIDYL ETHER RESINS... 

Since this reaction may occur at both ends of the molecule (in case of glycidyl ether resins) a cross-linked structure will be built up. 

Table 26.4 Some characteristics of amine hardeners for use in low molecular weight glycidyl ether resins...

Glycidyl ether resins are formed by reaction of epichlorohydrin with polyhydroxy compounds. In addition to the dominant use of bis-phenol A several other polyhydroxy compounds have been used. In particular there has been... 

Because of their low viscosity the liquid cyclic aliphatic resins find use in injection moulding and extrusion techniques, as used for glass-reinforced laminates. They are also very useful diluents for the standard glycidyl ether resins. 

As with the other non-glycidyl ether resins the absence of the ether oxygen near to the epoxide group results in low reactivity with amine hardemers whereas activity with acid anhydride proceeds at reasonable rates. 

Since these factors can have a considerable influence on properties it is difficult to give typical figures. Table 26.11 shows some quoted figures for glycidyl ether resin cured with diaminophenylmethane. The laminates were pressed at 400 Ibf/in (2.75 MPa) for one hour at 160°C and post-cured for eight hours at 60°C. 

Preparation of Resins from Bis-phenol A Curing of Glycidyl Ether Resins... 

In adhesive formulations, aliphatic amines are most commonly used to cure the DGEBA type of epoxy resin. Aliphatic amines are not widely used with the non-glycidyl ether resins, since the amine-epoxy reaction is slow at low temperatures. The reaction usually requires heat and accelerators for an acceptable rate of cure. Aliphatic amines are primarily used with lower-viscosity DGEBA resins because of the difficulty in mixing such low-viscosity curing agents with the more viscous epoxy resins. 

S mil coating on aluminum Resin 1 = Ciz-i alkyl glycidyl ether Resin 2 = Rutanediol diglycidyl ether... 

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