thereof. If employed, the organic liquid reaction diluent is generally employed in an amount from about 5 to about 300 percent based on the total weight of all the reactants. 

The reaction of the dihydric phenol and the epoxy resin, anhydride or amine is advantageously carried out at an elevated temperature, preferably, from about 60° C. to about 200° C., more preferably from about 100° C. to about 150° C. and, more preferably, from about 120° C. to about 140° C. The reaction is continued until the desired conversion, as determined by measuring the residual epoxy and terminal hydroxyl content in the resin, is achieved, at which point, the reaction is effectively terminated. 5 

Any method which effectively inhibits the reaction upon reaching the desired degree of conversion can be employed herein. The reaction is effectively inhibited when the rate of reaction of the hydroxyl and epoxy group is sufficiently reduced such that further reaction, if any, does not signifi› cantly and deleteriously affect the product or its handling characteristics. Preferably, the reaction is sufficiently inhib› ited such that the solution viscosity of the CCR resin remains essentially constant or increases only marginally with time. For example, upon reaching the desired degree of conversion, the reaction mixture can be quenched to stop the reaction. However, the rapid quenching of the reaction mixture must be conducted carefully to prevent clotting or lumping of the CCR resin and to prevent the CCR resin from forming a large solid mass which cannot subsequently be used. 

A convenient method for quenching the reaction mixture comprises the addition of a solvent to the mixture, thereby diluting the mixture and reducing its temperature. The amount of organic solvent to be added is dependent on the reaction temperature and the temperature at which reaction is effectively terminated. The addition of organic solvent to the reaction mixture is particularly preferred when the CCR resin is subsequently to be applied from solution. 

A most preferred method for inhibiting the reaction com› prises adding a material to the reaction mixture which effectively inhibits further reaction such as by deactivating the catalyst, or by interrupting the reaction mechanism, thereby inhibiting further reactions between the polyol and the polyepoxide. 

Strong inorganic and organic acids and the anhydrides and esters of said acids (including half esters and part esters) have been found to be particularly effective as reaction inhibitors. By the term "strong acid" it is meant an organic acid having a pKa value below about 4, preferably below about 2.5. Representative reaction inhibitors include inor› ganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; inorganic acid anhydrides such as phos› phoric acid anhydride; esters of inorganic acids such as dimethyl sulfate; the organic acids such as alkyl, aryl and aralkyl and substituted alkyl, aryl and aralkyl sulfonic acids such asp-toluene sulfonic acid and phenyl sulfonic acid and stronger organic carboxylic acids such as trichloroacetic acid and alkyl esters of said acids, such as the alkyl esters of p-toluene sulfonic acid, e.g., methyl-p-toluene sulfonate, and ethyl-p-toluenesulfonate, methanesulfonic acid methy› lester and mixtures thereof. An example of an acid anhydride of a strong organic acid that can be employed herein is p-toluene sulfonic acid anhydride. Of the reaction inhibitors, the alkyl esters of sulfuric acid: the aryl or aralkyl sulfonic acids and the alkyl esters of said acids are preferably employed herein. Most preferably, an alkyl ester of para› toluene sulfonic acid, particularly methyl or ethyl-p-toluene sulfonic acid is employed as the reaction inhibitor herein. 

The amounts of reaction inhibitor added to the reaction mixture are dependent on the specific inhibitor employed and the catalyst employed in preparing the CCR resin. In general, the inhibitor is added in an amount sufficient to overcome the catalytic activity of the catalyst. Preferably, at least about 0.9, more preferably at least about 2, equivalents of the inhibitor are added for each equivalent of the catalyst employed. Although the maximum amount of inhibitor added to the reaction mixture is dependent on the desired properties of the resin and the expense of adding excess inhibitor, the inhibitor is preferably added in an amount not exceeding about 5 equivalents for each equivalent of catalyst in the reaction mixture. 

The reaction is terminated at a point such that the resulting CCR resin contains the desired amounts of epoxy groups and terminal hydroxyl groups. In this invention, the CCR resin will contain at least about 0.25 percent, by weight, of each of the epoxy and terminal hydroxyl groups. The epoxy resins which can be employed in the practice of the present invention for preparing the CCR resins include the digly› cidyl ethers of dihydric phenols, such as those described in U.S. Pat. Nos. 5,246,751; 5,115,075; 5,089,588; 4,480,082 and 4,438,254, all of which are incorporated herein by reference, or the diglycidyl esters of dicarboxylic acids such as those described in U.S. Pat. No. 5,171,820. 

The diglycidyl ethers of dihydric phenols are preferably the diglycidyl ethers of resorcinol, hydroquinone, 4,4’› isop ropy lidene bisphenol (bisphenol A), 4,4’› dihydroxydi pheny le thy lme thane, 3 ,3’ -dihydroxy- diphenyldiethylmethane, 3,4’-dihydroxydiphenyl› methylpropylmethane, 4,4’-dihydroxydiphenyloxide, 4,4’› dihydroxydiphenylcyanomethane, 4,4’-dihydroxy-biphenyl, 4,4’-dihydroxybenzophenone (bisphenol-K), 4,4’› dihydroxydiphenyl sulfide, 4,4’-dihydroxydiphenyl sulfone, 2,6-dihydroxynaphthalene, 1,4’-dihydroxy-naphthalene, catechol, 2,2-bis( 4-hydroxyphenyl)-acetamide, 2,2-bis( 4- hydroxypheny l)ethanol, 2,2-bis( 4-hydroxyphenyl)-N› methy lacetamide, 2,2-bis( 4-hydroxy-phenyl)-N ,N› dimethylacetamide, 3,5-dihydroxyphenyl-acetamide, 2,4- dihydroxyphenyl-N-(hydroxyethyl)-acetamide, and other dihydric phenols listed in U.S. Pat. Nos. 3,395,118, 4,438, 254 and 4,480,082 which are hereby incorporated by refer› ence as well as mixtures of one or more of such diglycidyl ethers. Of these preferred diglycidyl ethers, those of bisphenol-A, hydroquinone, and resorcinol are more preferred, with the diglycidyl ether of bisphenol-A being most preferred. 

The diglycidyl esters of dicarboxylic acids are preferably the diglycidyl esters of terephthalic acid, isophthalic acid, 2, 6 - naphtha 1 en e di car boxy 1 ix acid, 3, 4’ - biphenyldicarboxylic acid, 4,4’-biphenyldicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pumelic acid, suberic acid, azaleic acid, sebasic acid, 1,4- cyclohexanedicarboxylic acid, 1,10-decanedicarboxylic acid, tartaric acid, malic acid, citramalic acid and hydroxy› glutaric acid. The more preferred diglycidyl esters are the diglycidyl esters of terephthalic acid, isophthalic acid, adipic acid, 1,4-cyclohexanedicarboxy lie acid and 1, 10- decanedicarboxylic acid. 

Other suitable epoxy resins include a, w-diglycidyloxyisopropylidene-bisphenol-based epoxy res› ins (commercially known as D.E.R.™ 300 and 600 series epoxy resins), a, w-diglycidyloxy tetrabromoisopropy lidene-bisphenol-based phenoxy resins, such as D.E.R. 542, both are products of The Dow Chemical Company. Preferred epoxy resins are the epoxy resins hav› ing an epoxy equivalent weight of from about 100 to about 

