Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
1999-06-29
2001-05-01
Dentz, Bernard (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C424S070310, C514S547000, C514S847000, C554S219000, C554S164000
Reexamination Certificate
active
06225485
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to personal care products, and, more particularly, to skin and hair care compositions containing a high purity adduct of castor oil and a cyclic carboxylic acid anhydride, which provides a substantive skin feel for the user, and to a method for making such useful adducts with no free acid anhydride therein.
2. Description of the Prior Art
Reaction products of castor oil and dehydrated castor oil with maleic anhydride have been disclosed in the literature. However, they usually involve other components in the reaction mixture which are present to provide the product with suitable properties for use, for example, as hardening agents for epoxy resins, or for leather fat liquoring, or as emulsifiers for the polymerization of vinyl chloride and other aqueous polymer compositions, and as lubricants for rolling mills. For example, SU 445688, published Feb. 26, 1975, described paint compositions containing the reaction product of castor oil and maleic anhydride having a substantial amount of free maleic anhydride, particularly, about 1-4%; and DE 3202408, published Aug. 4, 1983, disclosed the use of castor oil and cyclic anhydride adducts as flexibilizing agents for epoxy resins.
Accordingly, it is an object of the invention to provide a high purity adduct of castor oil and a cyclic carboxylic acid anhydride characterized by the absence of free acid anhydride, and a process for making such advantageous adduct, which is carried out with no significant side reactions.
Another object of the invention is to afford personal care products, particularly for skin care, which provide a highly substantive skin feel, as well as moisturization benefits, and hair care, particularly hair conditioning, in both leave-on and rinse-off applications, which products include a high purity adduct of castor oil and carboxylic acid anhydride having no free acid anhydride.
These and other objects and features of the invention will be made apparent from the following description thereof.
SUMMARY OF THE INVENTION
The invention herein provides a high purity adduct of castor oil and a cyclic carboxylic acid anhydride characterized by the absence of free acid anhydride therein. The mole ratio of anhydride to castor oil in the high purity adduct is in the range of 0.5:1 to 2.5:1, with 1:1 being the preferred ratio.
The adduct is made by a process which is carried out with no significant side reactions, including (a) reacting castor oil and cyclic carboxylic acid anhydride at a temperature of 75-120° C. for 4 to 24 hours, and then (b) continuing the reaction at room temperature for at least 1 week to react any remaining acid anhydride. Preferably step (a) is carried out at about 100° C. for about 6-8 hours, and (b) is carried out at room temperature for about 1-2 weeks. Preferably, the product of (a) is held at 50-80° C. for 24 hours while drumming the batch, as it decreases the time required for step (b).
The product of such a process is the desired high purity, 1:1 adduct with no free acid anhydride detectable by ordinary gas chromatography (GC).
The adduct of the invention finds commercial application in personal care products, which are suitable for both leave-on and rinse-off modes of application. These include skin care cleansing and treatment products, which provide the user with a substantive skin feel and moisturization benefits; and in hair conditioning compositions.
DETAILED DESCRIPTION OF THE INVENTION
Castor oil is one of three triglycerides that contain principally one fatty acid; it is about 90% ricinoleic acid, or 12-hydroxyoleic acid. The other two are tung oil, which is about 80% eleostearic acid, and oiticica oil, which is about 80% licanic acid. The hydroxyl group of the ricinoleic acid reacts like a typical secondary alcohol, i.e. it can be eliminated or esterified.
Elimination is a dehydration reaction which gives rise to about a 60:40 mixture of non-conjugated-to-conjugated linoleic acid isomers in the product, which is called dehydrated castor oil and sold as a drying oil. The conjugated linoleic acid residues are suitable for a Diels-Alder reaction with dienophiles such as maleic anhydride, maleic acid or fumaric acid. Both dehydration and Diels-Alder reactions are considered undesirable side reactions in this invention. Crosslinking is another undesirable side reaction, which becomes significant in the temperature range of 125-150° C.
Esterification of castor oil can occur by reaction with an anhydride. When the anhydride is cyclic, e.g. maleic or succinic anhydride, the carboxylic acid group formed during the reaction remains attached in the product. At any given temperature, an equilibrium is established between starting materials and product where the higher the temperature, the more starting materials are observed. For example, at 100° C., the equilibrium concentration of maleic anhydride in such a reaction is 1% of the starting amount. At room temperature, the equilibrium is far on the side of the desired product; however the reaction time is inordinately long.
In this invention, reaction between castor oil and cyclic carboxylic acid anhydride is suitably run at about 75-120° C., preferably at about 100° C. for maleic anhydride and 120° C. for succinic anhydride. The reactions reach 98-99% conversion in 6-8 hours. Upon cooling slowly and standing for a day or two at room temperature, the conversion is >99%, and after 1 week or longer, it is quantitative, i.e. no free acid anhydride can be detected by GC.
This reaction cannot be forced to completion by holding it for a longer time at 100° C., or by increasing the temperature, owing to the presence of a significant back-reaction. Furthermore, if the reaction temperature is increased, undesirable crosslinking is observed in the product, which is detected by size-exclusion chromatography (SEC). Eventually, the ester is eliminated to afford a partially dehydrated castor oil and carboxylic acid, which in the case of maleic acid can undergo the Diels-Alder reaction, as described above. Crosslinking is observed at about 125-150° C. and the Diels-Alder reaction at about 150-170° C. Accordingly, the reaction with maleic anhydride can be run at 120° C. for 4 hours with negligible crosslinking; however, the amount of free acid anhydride present at 120° C. is higher (about 1.5-2%) than at 100° C. (about 0.8-1.2%), and the time required for its disappearance at room temperature is correspondingly much longer.
Thus, a reaction temperature of about 75-120° C. is considered suitable, for a reaction time of about 4 to 24 hours; however, a temperature of about 100-120° C., depending on the carboxylic acid anhydride, is much preferred, for an initial reaction time of about 6-8 hours and a subsequent room temperature reaction time of about 1-2 weeks.
REFERENCES:
patent: 2551352 (1951-05-01), Tawney
patent: 445688 (1975-02-01), None
Bertz Steven H.
Miksza Frank M.
Zucker Elliott
Davis William J.
Dentz Bernard
ISP Investments Inc.
Katz Walter
Maue Marilyn J.
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