Glycidyl ether type epoxies

Previous work (5) has been limited to the glycidyl ether type epoxies, requiring catalytic curing rather than the conventional hardener type curing to facilitate formation of the desired rubbery particles. 

TaMe 16. Mechanical properties of composites made of the PAFO cured epoxy compounds (glycidyl ether type) [64]... 

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. 

Cold curing unsaturated resin was obtained in the following way. A mixture of BPA, BPA monocyanate and BPA dicyanate was cyclotrimerized and reacted with BMI. The obtained prepolymer with phenolic hydroxyls (cf. Scheme 9) was then treated with epichlorohydrin and alkali. The phenolic hydroxyls were thus transformed into glycidyl ether groups. Then the addition of methacrylic acid to the epoxy groups was carried out. The obtained vinyl ester (epoxyacrylate) type resin was dissolved in styrene and cured with the usual benzoyl peroxide/dimethylaniline system [131],... 

In addition to the DGEB A resins, there are several other types of epoxy resins of commercial significance. The most common of these are epoxy novolacs, glycidyl ether of tetraphe-nolethane, bisphenol F-based resins, and aliphatic and cycloaliphatic resins. 

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. 

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. 

Effects of Epoxy Type and Amount. Three different types of epoxies were investigated, two of them more extensively. The epoxies were 1) a bis(glycidyl ether) of bisphenol A (DER 330, Dow Chemical), 2) an epoxy novolac (DEN 431, Dow Chemical Co.), and 3) a tetra-functional epoxy, tetraglycidyl ether of 4,4 -methylene bis(aniline), (Araldite MY720, Ciba-Geigy Co.). The tetrafunctional liquid epoxy was eliminated early in the study due to the fact that too much stiffness and therefore very little loss (i.e. low damping) was imparted into the IPN. It was believed that the use of the tetrafunctional epoxy resulted in too high a crosslink density in the IPN. 

The third type of composition is exemplified acrylate- and methacrylate-ester derivatives of epoxy resins combined with a photoinitiator 1. Epo prepolymers (e. g., glycidyl methacrylate-allyl glycidyl ether copolymers or Ciba ECN 1299) combined with a photosensitive aryldiazonium compound (e.g.,... 

The third type of composition is exemplified by acrylate- and methacrylate-ester derivatives of epoxy resins combined with a photoinitiator 1. Epoxy prepolymers (e. g., glycidyl methacrylate-allyl glycidyl ether copolymers or Ciba ECN 1299) combined with a photosensitive aryldiazonium compound (e.g., -nitrobenzenediazonium hexaflourophosphate) (38,39) 2. Epoxy prepolymers (e.g., a diglycidyl ether of disphenol A-(3,4-epoxycyclohexyl)-methyl-3,4-epoxycyclohex-anecarboxylate-alkyl glycidyl ether mixture) combined with a photosensitive aryldiazonium compound (e.g., -chlorobenzenediazonium hexaflourophosphate) and l-methyl-2-pyrrolidone gelation inhibitor (40) ... 

The polymerization of ethylene oxide and propylene oxide with various active hydrogen compounds is the primary thrust of the present chapter. However, other epoxy compounds also undergo this type of reaction as is detailed in the chapter Polymerization of Epoxides and Cyclic Ethers of this series [5]. An example of the polycondensation of a complex glycidyl ether with a polyol, taken from the patent literature, is cited here for reference only. 

Epoxy resins have been used successfully as strong binders in some special mixtures. A suitable type is Epon 828 (Shell Oil Co.) diluted with the active additive AGE (allyl glycidyl ether) that reduces the viscosity to less than one-tenth and about 8% DETA (diethytene-triamine) as a cold-curing catalyst (actually a cross-linking agent). This mixture can be used very much like a polyester resin. For less rigid compositions, a poly functional mercaptan such as LP-2 and LP-3 (Thiokol Chemical Corp.) can be used and such a resin can be combined with epoxy resin. A number of these types of resins are claimed as pyrotechnic binders in a patent by Hart, Eppig, and Powers. ... 

Cresyl glycidyl ether is a reactive diluent added in epoxy resins of the Bisphenol A type. 

Epoxy resins of the bisphenol A type are synthesized from bisphenol A and epichlorhydrin. Hardeners, such as amines (ethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, triethy-lenetriamine and 4,4 -diaminophenylmethane) or acid anhydrides (phthalic anhydride) are added. Reactive diluents may be added, such as allyl glycidyl ether, butanediol diglycidyl ether, -butyl glycidyl ether, o-cresyl glycidyl ether, hexanediol diglycidyl ether. 

As has been noted previously, most commercial epoxy resins are, at present, prepared by reaction of bisphenol A and epichlorhydrin. However, other types of resin have become available and some of these are described below. These resins are conveniently divided into two groups, namely glycidyl ethers and non-glycidyl ethers. 

Two types of non-glycidyl ether epoxy resins are commercially available, namely cyclic aliphatic and acyclic aliphatic resins. 

Being a glycidyl ether of a novolac type phenol formaldehyde resin, epoxy phenol novolac resins (Figure 2.39 (a)) are the polymeric multifunctional counterpart of bisphenol F resin. They are supplied as highly viscous through semisolid to solid resins. They are generally prepared by reacting epichlorohydrin with novolac type phenol formaldehyde resins. 

Poor light fastness (exterior durability) of BPA type epoxy resins, due to the presence of aromatic ether linkages, limits their outdoor applications. Epoxy resins with improved weathering performance can be obtained by using aliphatic epoxy resins. One of the important epoxy resins in this class is the glycidyl ether of hydrogenated bisphenol A. These resins have lower viscosity, lower reactivity and higher cost compared to BPA epoxy resins. 

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