Preparation of Resins from Bis-phenol

The commercial interest in epoxide (epoxy) resins was first made apparent by the publication of German Patent 676117 by I G Farben in 1939 which described liquid polyepoxides. In 1943 P. Castan filed US Patent 2 324483, covering the curing of the resins with dibasic acids. This important process was subsequently exploited by the Ciba Company. A later patent of Castan covered the hardening of epoxide resins with alkaline catalysts used in the range 0.1-5% This patent, however, became of somewhat restricted value as the important amine hardeners are usually used in quantities higher than 5%. 

Before World War II the cost of the intermediates for the these resins (in most cases epichlorohydrin and bis-phenol A) would have prevented the polymers from becoming of commercial importance. Subsequent improvements in the methods of producing these intermediates and improved techniques of polymerisation have, however, led to wide commercial acceptance. 

By the beginning of the 1980s world capacity for epoxide resins reached about 600000 tonnes per armum but at this time plant utilisation was only about 50-60%. Thus with a global consumption of about 10 million tonnes per annum for thermosetting plastics, epoxide resins had a share of about 3%. Western Europe and the USA each had about 40% of the market and Japan a little over 10%. This situation has not greatly changed since then but by the late 1990s the world market for epoxide resins had risen to about 750 000 t.p.a. 

About half of epoxide resin production is used for surface coating applications, with the rest divided approximately equally between electronic applications (particularly for printed circuit boards and encapsulation), the building sector and miscellaneous uses. In tonnage terms consumption of epoxide-fibre laminates is only about one-tenth that of polyester laminates, but in terms of value it is much greater. 

Whilst the properties of the cross-linked resins depend very greatly on the curing system used and on the type of resin, the most characteristic projrerties of commercial materials are their toughness, low shrinkage on cure, high adhesion to many substrates, good alkali resistance and versatility in formulation. 

Since both phenol and acetone are available and the bis-phenol A is easy to manufacture, this intermediate is comparatively inexpensive. This is one of the reasons why it has been the preferred dihydric phenol employed in epoxide resins manufacture. Since most epoxide resins are of low molecular weight and because 

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

Measurement of conversions of various formulations at various EB doses can be used to rank the reactivity of the formulation. A particularly useful procedure has been to prepare a standard mixture of an acrylate resin with various reactive diluent monomers in order to compare the volatility and reactivity of new monomers. For these studies, a mixture of 40 weight % of a Bis-phenol A epoxy dlacrylate resin with 60% of the test liquid monomer has proved convenient. A viscosity measurement of the mixture also provides information on the relative viscosity reducing ability of the test monomer. Illustrative examples of these measurements are shown in Table I and Figure 1. Mote from these examples that a monofunctional monomer, Monomer B, can be used to provide the low volatility and high reactivity typical of the multifunctional monomers, while also serving to reduce the crosslinking. Many other available monofunctional monomers are found to be either more volatile or less reactive than Monomer B. 

Resins derived from ketones are not nearly as common as those prepared from aldehydes. However, an important industrial dimer is Bis-phenol A, made by the controlled condensation of acetone and phenol. 

Acrylated Melamine resins were prepared by reacting different levels of acrylamide with a fully alkylated coetherified melamine resin containing methyl and butyl groups at an approximate ratio of 1 1. They were prepared with 0.5, 1.0, 1.5, and 2.5 moles of acrylamide per triazine ring. Throughout the paper a bis-phenol A epoxy acrylate resin (Ebecryl 3700 from Radcure Specialties) and an aliphatic urethane acrylate resin (Ebecryl 8800 from Radcure Specialties) are used as controls. 

Epoxide adhesives comprise epoxy resin, many of which are prepared from phenols and epichlorohydrin, for example, the diglycidyl ether of bis-phenol A or bis-phenol F usually, these resins are a mixtnre of molecular weights blended to fit the applications. The most-common cnratives for epoxy resins are polyanfines (used in stoichiometric amounts), usually a chain-extended primary aliphatic amine, for example, diethylene triamine or triethylene tetraamine or chain-extended equivalents, which react rapidly with the epoxy resin at room temperature. Aromatic amines react slowly at room temperature but rapidly at higher temperatures. Most epoxide adhesives also contain catalysts, typically, tertiary amines. Dicyanimide is the most-common curative for one-component high-temperature-cured epoxide adhesives. Mercaptans or anhydrides are used as curatives for epoxide adhesives for specialist applications, for example, for high-speed room-temperature cures or for electronic applications. A smaller number of epoxide adhesive are cured by cationic polymerization catalysed by Lewis acids photogenerated at the point of application. Lewis acid photoinitiators include diaryliodonium and triarly sulphonium salts. See Radiation-cured adhesives. 

The copolymer (Fig. 14.4) is prepared from l,l-bis(4-hydroxyphenyl)-3,3, 5-trimethylcyclohexane (1) and bisphenol A. The cyclohexane containing bisphenol (1) is prepared by the condensation of phenol with 3,3,5-trimethylcyclohexanone and an acidic catalyst. The cyclohexanone can be prepared by the selective hydrogenation of isophorone [113, 114]. The Tg of the copolymers can be varied from 150°C (e.g., BPAhomopolymer) to 240°C [e.g., homopolymer of l,l-bis(4-hydroxyphenyl)-3,3,5-trimethylcydohexane]. And the resins can be prepared by either melt or interfacial processes. For increased ductility, terpolymers have been reported with a sUoxane block [115]. For applications requiring low moisture absorption, the bisphenol (1) has been polymerized with bisphenol M (see the section New Copolymers for Optical Storage Media ). 

Benzoxazi ne Resi ns. Benzoxazine resins are prepared by the reaction of phenol, formaldehyde, and an amine. In one particular example a benzoxazine is prepared from bisphenol A, formaldehyde, and anihne to give 2,2 -bis(3-phenyl-4-dihydro-l,3,2-benzoxazine) propane. When heated to about 200°C the methylene bond to oxygen breaks and reforms onto the available ortho positions of adjacent moieties to give dibenzylamine structures. Resin formulations have been developed and formulated, in some cases with epoxy and phenolic resins to give ternary systems with Tg as high as 170°C (Fig. 4) (43-46). 

Bisphenol A (2,2 -bis (4 -hydroxyphenyl)-propane) can be prepared from a 10 1 mixture of acetone and phenol over cation-exchange resin of which sulfo-groups are partially esterified with mercaptoethanol. ... 

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