Bisphenol epichlorohydrin reaction

In addition, glycidyl esters are produced by the reaction of cycloahphatic carboxyUc acids with epichlorohydrin, followed by dehydrohalogenation with caustic. Such products are characterized by low viscosities (ca 500 mPa-s (=cP)). Reactivity of the glycidyl esters more closely resembles the standard bisphenol—epichlorohydrin resins. 

The reaction actually involves the sodium salt of bisphenol A since polymerization is carried out in the presence of an equivalent of sodium hydroxide. Reaction temperatures are in the range 50-95°C. Side reactions (hydrolysis of epichlorohydrin, reaction of epichlorohydrin with hydroxyl groups of polymer or impurities) as well as the stoichiometric ratio need to be controlled to produce a prepolymer with two epoxide end groups. Either liquid or solid prepolymers are produced by control of molecular weight typical values of n are less than 1 for liquid prepolymers and in the range 2-30 for solid prepolymers. 

Thiadiazoles readily undergo photochemical reactions (see Section 4.24.3.1) which have been utilized in polymer chemistry. For instance, polymers of type (46), formed by condensation of bisphenol epichlorohydrin copolymers and a l,2,3-thiadiazole-4-carboxylic acid, undergo photochemically induced crosslinking (70SST(1)444). This type of process is useful in the printing and electronic industries. 

Vinyl ester resins are produced by the addition of ethylenically unsaturated carbo acids (methacrylic or acrylic acid) to an epoxide resin (usually of the bisphenol epichlorohydrin type). The reaction of acid addition to the epoxide ring (esterification exothermic and produces a hydroxyl group without the formation of by-products. Appropriate diluents and polymerization inhibitors are added during or after esterification. 

Polymeric products [117] are obtained when the mole ratio is less than 2 for the epichlorohydrin-bisphenol A reaction and a molecular weight of 1420 is reported at a mole ratio of 1.2 [118]. High molecular weight resins (30,000 or more) are known as phenoxy resins, and these thermoplastic resins are used for coatings, adhesives, and various molding applications. 

Epoxy Resins. The chemistry of epoxy resin adhesives is quite varied. However, the most widely used is that formed from the reaction of 4,4 -isopropyhdene diphenol (bisphenol A) [80-05-7] and epichlorohydrin [106-89-8] C H CIO. This epoxy resin is more commonly known as... 

Epichlorohydrin and Bisphenol A-Derived Resins. Liquid epoxy resins maybe synthesized by a two-step reaction of an excess of epichl orohydrin to bisphenol A in the presence of an alkaline catalyst. The reaction consists initially in the formation of the dichi orohydrin of bisphenol A and further reaction by dehydrohalogenation of the intermediate product with a stoichiometric quantity of alkaH. 

Liquid epoxy resin based on the reaction product of epichlorohydrin and bisphenol A or bisphenol F mild to moderate irritants mild to moderate sensitizers low volatility, exposure unlikely unless heated, sprayed, or spread over large unventilated surface low toxicity... 

Epoxy resins are produced by reacting epichlorohydrin and a diphenol. Bisphenol A is the diphenol generally used. The reaction, a ring... 

This reaction is quite general and, since the organic group R can be aliphatic, cycloaliphatic, or aromatic, there is wide scope for variation in the composition of epoxy resins. In practice, however, the most frequently used materials are those based on bisphenol A and epichlorohydrin, which represent over 80% of commercial resins. 

Virtually all epoxy resins are made with starting materials based on epichlorohydrin, principally by reaction with bisphenol A. It is also used for the preparation of resins to increase the wet strength of paper. Both epichlorohydrin and glycidol are used in the manufacture of pharmaceuticals. 

The epoxy polymers are basically poly ethers. One type of epoxy polymer (or epoxy resins) are prepared from epichlorohydrin and bisphenol-A. The reaction is carried out with excess of epichlorohydrin. The various reactions for the preparation of an epoxy polymer are given in the following discussion. 

Epoxy resins. The reaction of Bisphenol A and epichlorohydrin gives a low molecular weight linear polymer. This polymer further reacts with an amine-curing agent, R-NH2, to give a general-purpose thermoset. See Figure 24-2.) Now that s not as complicated as it sounds. First of all, you d think... 

This type of thermoset polymer is typically made first by reaction of the sodium salt of bisphenol A and excess epichlorohydrin, which forms a low molecular weight polymer with terminal epoxy groups n is between 1 and 4. 

The reaction is generally carried out in the presence of a base such as sodium hydroxide. Bisphenol A is a phenol and, as such, a weak acid. The generated RO reacts with the electron-poor chlorine-containing carbon on epichlorohydrin, creating a cyclic ether end group. The phenoxy moiety can also react with the cyclic ether, eventually forming the polyether structure. This sequence is described in Figure 4.8. 

Epichlorohydrin is reacted with a variety of hydroxy, carboxy, and amino compounds to form monomers with two or more epoxide groups, and these monomers are then used in the reaction with bisphenol A [Lohse, 1987]. Examples are the diglycidyl derivative of cyclohex-ane-l,2-dicarboxylic acid, the triglycidyl derivatives of p-aminophenol and cyanuric acid, and the polyglycidyl derivative of phenolic prepolymers. Epoxidized diolefins are also employed (Sec. 9-8). 

Epoxy resins are usually understood to be products of reaction of polyfunctional hydroxy compounds with l-chloro-2,3-epoxypropane (epichlorohydrin) in basic medium. In the simplest case two mol of epichlorohydrin react, for example, with one mol of bisphenol A, according to the following scheme ... 

The commercially most important epoxy resins are those prepared from 4,4 -isopropylidenediphenol (bisphenol A) and epichlorohydrin. They have molecular weights between 450 and 4000 [n in formula (II) between 1 and 12] and softening points between 30 and 155 °C. Such epoxy resins are still soluble, but become insoluble and infusible through subsequent crosslinking reactions. 

Schlack [2] and Castan [3,4] are credited with the earliest U.S. patents describing epoxy resin technology. Greenlee [5] further emphasized the use of bisphenols and their reaction with epichlorohydrin to yield diepoxides capable of reaction with crude tall oil resin acids to yield resins useful for coatings. The use of diepoxide resins that are cured with amines was reported by Whittier and Lawn [6] in a U.S. patent in 1956. 

Synthesis Epoxy resins consisting ofglycidyl ether, ester and amines are generally prepared by the condensation reaction between diol, dibasic acid or amine and epichlorohydrin in the presence of sodium hydroxide with the elimination of hydrochloric acid. The commercially available epoxy resins are, however, made by the reaction of epichlorohydrin and bisphenol-A. Cashew nut shell liquid (CNSL)-based novolac epoxy resins have also been reported [342]. 

Cross-Linked Polymers. In the 1980s, not only glass and BPA-PC but also uv-curable cross-linked polymers, eg, epoxy resins, were used as substrate material for optical mass storage disks with laige diameters (12 in., 14 in.) (219). The epoxy resins consisted of compounds containing one or several highly reactive epoxy or hydroxyl groups. The common epoxy resins (EP) mainly are reaction products of bisphenol A and epichlorohydrin ... 

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