Chemistry: natural resins or derivatives; peptides or proteins; – Natural resins or derivatives – Tall oil or derivative used as starting material in process,...
Reexamination Certificate
1999-07-29
2001-02-13
Nutter, Nathan M. (Department: 1711)
Chemistry: natural resins or derivatives; peptides or proteins;
Natural resins or derivatives
Tall oil or derivative used as starting material in process,...
C530S223000, C562S512000, C562S512400, C560S205000, C585S365000, C585S803000
Reexamination Certificate
active
06187903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of preparing dimeric fatty acids and/or esters thereof from unsaturated monomeric fatty acids and/or esters thereof. More particularly, the invention herein relates to a method of preparing dimeric fatty acids and/or esters thereof having a relatively low residual content of interesters, and to the dimeric fatty acid and/or dimeric fatty ester product which can be used to prepare higher molecular weight polymers than that obtained by polymerizing dimeric fatty acids and/or esters thereof with higher interester content.
2. Brief Description of the Prior Art
It is known that monomeric unsaturated fatty acids and the alkyl esters of these fatty acids can be utilized to manufacture dimeric fatty acids and dimeric fatty esters, which in turn, can be used to manufacture polyamide, epoxy and polyester resins for use, inter alia, in thermographic inks and coatings for plastic films, papers, and paperboard. Production of dimeric fatty acids and their esters typically comprises heating monomeric unsaturated monocarboxylic acids and/or their alkyl esters having from about 11 to about 24 carbon atoms, e.g., oleic acid, linoleic acid, esters of these fatty acids and the like, in the presence of a mineral clay and water, as described, e.g., in U.S. Pat. Nos. 3,632,822, 3,422,124, 2,793,219, 2,793,220, 2,955,121, and 4,776,983, the contents of each of which are incorporated by reference herein. A typical end product of these methods is a 36-carbon dicarboxylic dimeric fatty acid or ester thereof. Dimeric fatty acids can also be produced from dimerizing dicarboxylic acids and combinations of mono- and dicarboxylic acids as described, e.g., in U.S. Pat. Nos. 5,001,260 and 4,895,982, the contents of each of which are incorporated by reference herein.
Such methods of preparing dimeric fatty acids and dimeric fatty esters also result in the formation of one or more interesters, which result from the reaction of a double bond of an unsaturated fatty acid and ester thereof with water to form an alcohol which in turn reacts with a mole of acid to form interester. The presence of interesters in the dimeric fatty acid and fatty ester product has been found to hinder the formation of more desirable higher molecular weight polymers when the dimeric fatty acids and esters thereof are polymerized. Interesters cannot be readily removed from the dimeric fatty acids or their esters by simple methods, e.g., distillation, stripping, etc. Accordingly, an efficient, low cost method of preparing dimeric fatty acids or dimeric fatty esters of substantially reduced interester content is highly desired.
SUMMARY OF THE INVENTION
The present invention provides a method of preparing dimeric fatty acids and/or esters thereof having a low residual content of interesters. The method comprises:
a) dimerizing monomeric unsaturated fatty acids and/or esters thereof to provide a first mixture containing dimeric fatty acids and/or esters thereof, unreacted and/or rearranged monomeric fatty acids and/or esters thereof and interesters;
b) separating the unreacted and/or rearranged monomeric fatty acids and/or esters thereof from the first mixture to provide a second mixture containing dimeric fatty acids and/or esters thereof and interesters;
c) subjecting the second mixture to hydrolysis conditions to hydrolyze at least a portion of the interesters therein to monomeric fatty acids and alcohols thereby providing a third reaction mixture containing dimeric fatty acids and/or esters thereof, monomeric fatty acids and alcohols; and,
d) separating monomeric fatty acids and alcohols from the third mixture to provide a dimeric fatty acid and/or dimeric fatty ester product having a reduced content of interesters relative to the interester content of the second mixture.
The foregoing method of preparing dimeric fatty acids and/or esters thereof results in the formation of a dimeric fatty acid and/or dimeric fatty ester product of reduced interester content. This product is especially useful for the manufacture of dimeric fatty acid and/or dimeric fatty ester polymers of relatively high molecular weights which cannot be obtained from dimeric fatty acids and/or esters thereof produced by known and conventional methods such as those referred to above.
As used herein, the term “unsaturated fatty acids” refers to monocarboxylic and/or polycarboxylic acids, e.g., dicarboxylic acids, having at least one double bond.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
The method of preparing dimeric fatty acids and/or fatty esters thereof having a low residual content of interesters as described herein can be utilized to dimerize any monomeric mono- or polyunsaturated fatty acid, esters of these fatty acids or mixtures thereof. Such monomeric unsaturated fatty acids and/or esters thereof can be obtained from an animal, vegetable, marine or synthetic source and typically have a chain length of from about 11 to about 24 carbon atoms. Suitable monounsaturated fatty acids and esters thereof include, but are not limited to, monounsaturated monocarboxylic acids such as oleic acid, elaidic acid and palmitoleic acid, monounsaturated polycarboxylic acids including dicarboxylic acids such as hexadec-8-enedioic acid, octadec-9-enedioic acid and 7-vinyl-tetradecanedioic acid, methyl, ethyl and other esters of the aforementioned fatty acids and mixtures thereof. Suitable polyunsaturated fatty acids and esters thereof include, but are not limited to, polyunsaturated monocarboxylic acids such as linoleic acid and linolenic acid and polyunsaturated polycarboxylic acids including dicarboxylic acids such as eicose-8,12-dienedioic acid, 8-vinyl-octadec-10-enedioic acid and 8,13-dimethyleicose-8,12,-dienedioic acid, methyl, ethyl and other esters of the aforementioned fatty acids and mixtures thereof. Suitable mixtures of both monounsaturated and polyunsaturated fatty acids and esters thereof include tall oil fatty acids, soybean fatty acids, corn oil fatty acids, canola fatty acids, cottonseed oil fatty acids, tallow fatty acids, rapeseed oil fatty acids, fish oil fatty acids and methyl, ethyl and other esters of the aforementioned fatty acids. This method can also be practiced on various mixtures of unsaturated fatty acids and/or esters thereof which also contain saturated fatty acids and/or esters thereof. For example, commercial oleic acid of high quality includes a minor amount, e.g., from about 5 to about 10 weight percent, of saturated fatty acids such as stearic and palmitic acids. The saturated fatty acids are not dimerized and are separated together with unreacted and/or rearranged monomeric unsaturated fatty acids. The rearranged monomeric fatty acids are formed during dimerization from rearrangement of the substrate monomeric unsaturated fatty acids utilized in dimerization. For example, oleic acid utilized as the substrate monomeric unsaturated fatty acid can rearrange during dimerization to form isostearic acid.
The method of preparing dimeric fatty acids or esters thereof initially involves dimerizing monomeric unsaturated fatty acids and/or esters thereof to provide a first mixture containing dimeric fatty acids and/or esters thereof, unreacted monomeric fatty acids and/or rearranged monomeric fatty acids and/or esters thereof and interesters. Methods of dimerizing fatty acids and/or esters thereof are well known in the art as described, e.g., in aforesaid U.S. Pat. Nos., 4,776,983, 3,422,124, 2,793,219, 2,793,220, 2,955,121, 3,632,822, 5,001,260 and 4,895,982. The dimerization of fatty acids and/or esters thereof typically involves charging a reaction vessel with unsaturated fatty acid and/or an ester thereof, e.g., oleic acid and methyl oleate, and heating the fatty acid and/or ester thereof at an elevated temperature, e.g., from about 230 to about 270° C., under autogenous pressure, e.g., from about 70 to about 175 psi, in the presence of a mineral clay, and preferably water and an alkali or alkaline earth metal salt, e.g., a lithium salt such
Elsasser A. Fred
McCargar Laura A.
Cognis Corporation
Drach John E.
Hess Susan L.
Nutter Nathan M.
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