320 JOURNAL OF THE SOCIETY O1: COSMETIC CHEMISTS l)ispersions of shellac in borax, especially those made with less than the calculated stoichiometrical equivalent, are receiving a good deal of at- tention by research groups in this country and India. Boric acid esters of shellac are said to be high melting point resins (21), but no details have been divulged. In discussing recent progress made in our own laboratories, we would state that one of our main activities is the preparation of esters and other derivatives. We believe that the most usetiff derivatives will involve a fundamental change in the shellac complex. In trying to bring about such a change, as for example, by reacting shellac directly with polyols and polyacids, we find it almost impossible to avoid producing insoluble gels, useless for any industrial purpose. We like to start with a less complex material. We call it "basic lac substance." OH HO--CH O-- CH HO--B 4- HO-B OH HO CH O- CH q- 2HsO HC---()H O--CH HC--O () CH q- HO -B __ H • B Figure 3.--Chelation ooe aleuritic acid with boric acid. + H•() 'l'his is a liquid substance, produced in good yield fi't,m the same raw materials which we use to make bleached shellac. But the process is materially different. Basic lac substance may be described as a mixture of the building blocks of shellac. Table 3 compares some of its constants with those of orange shellac. Note particularly the low iodine number. The double bond of shellolic acid seems to be mainly responsible for the color reversion ()f bleached shellac under the influence of heat. Aleuritic acid, having no double bond, may be heated for hours at 2(X)øC. without yellowing. ,his(), bleached shellac or samples of basic lac substance with an iodine wfiue of about 10, darken rapicily when heated. However, when the iodine value of basic lac substance is reduced t()al)r)ut 3, the tendency to darken is greatly reduced. We are studying the reactions of basic lac substance with those materials which might be expected to yield resins with higher melting point, greater flexibility, better adhesion, less tendency to yellow, and so on.

PHYSICAl, AND CHEMICAL PROPERTIES OF SHELLAC 32l TABLE 3.--ORANGE SHELI,A(2 AND "BAsic LAc SUBSTANCE" COMPARED Basic l,ac Orange Shellac Substance Acid value 68-75 190-195 Saponification wdue 175-200 235-245 Ester value 100-130 45-50 Hydroxyl value 310-325 375-385 Iodine value 13-16 2-3 TABLE 4.--ORANO, E SHELI,AC AND "BASIC LAC •UBSq'ANCE " RATIOS OF FUNCTIONAL G•,OUPS Basic l.ac Orange Shellac Substance Carboxyl 1.5 4 Ester 2 1 Hydroxyl 6 8 'Fable 4 shows the ratios of carboxyl, ester and hydroxyl groups of orange shellac and basic lac substance. As might be expected, the latter is fat' more tractable than shellac itself. It is far less prone to form insoluble gels. With polyols, such as ethylene glycol, diethylene glycol and sorbitol, we obtain soft products, some of which adhere to metals with surprising tenacity. We expect to develop resins useful in wave sets by carrying this work further with a wide range of reactive polyols and polyacids. Such complex esters can be produced at prices competitive with the most popular wave set resins now in use. Built-in properties of internal plastici- zation, molecular springiness, controlled adhesion, flexibility, removability and reduced corrosiveness are in view. Shellac esters are at present the on}y shellac derivatives available commercially. They are marketed in alcohol solution. All of them give softer fihns than shellac Some are even tacky. Some have very low tolerance for hydrocarbons and aerosol propellants. Our company has developed a very viscous, sticky ester with an acid value of 2-3--an un- usually low value compared to commercial esters, which have a range of 45-65. It can be produced and marketed without a solvent. I,ike other shellac esters, its use so tar is directed toward the industrial coating and fingernail lacquer field, where it enhances adhesion and flexibility. The above esters all involve esterifying, or partially esterifying, the carboxyl groups of shellac. The stearic acid ester has quite different properties. It has been described by the Indian Lac Research Institute (22) as a waxy, nontacky solid soluble in naphthas, toluene, alcohol, esters and ketones. It holds promise for wave set materials. It will soon be available in development quantities. Other fatty acid esters are under investigation.