Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2001-05-18
2004-02-10
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S157000
Reexamination Certificate
active
06689893
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a shelf stable haze free liquid of an alkaline earth metal salt of a fatty acid and a process of producing the liquids. Mixed metal stabilizers containing the overbased liquids and metal carboxylates of zinc, cadmium or alkyltin are provided and used as stabilizers for halogen-containing polymers such as polyvinyl chloride (PVC).
BACKGROUND OF THE INVENTION
The preparation of overbased calcium or barium salts of carboxylic acids, alkyl phenols, and sulfonic acids are disclosed in the following U.S. Pat. Nos. 2,616,904; 2,760,970; 2,767,164; 2,798,852; 2,802,816; 3,027,325; 3,031,284; 3,342,733; 3,533,975; 3,773,664; and 3,779,922. The use of these overbased metal salts in the halogen-containing organic polymer is described in the following U.S. Pat. Nos. 4,159,973; 4,252,698; and 3,194,823. The use of overbased barium salt in stabilizer formulations has increased during recent years. This is due, in the main, to the fact that overbased barium salts possess performance advantages over the neutral barium salts. The performance advantages associated with overbased barium salts are low plate-out, excellent color hold, good long-term heat stability performance, good compatibility with the stabilizer components, etc. Unfortunately, most of the overbased barium salts are dark in color and, while these dark colored overbased barium salts are effective stabilizers for halogen-containing organic polymer, their dark color results in the discoloration of the end product. This feature essentially prohibits the use of dark colored overbased barium salts in applications where a light colored polymer product is desired.
According to the teachings of U.S. Pat. No. 4,665,117, light colored alkali or alkaline earth metal salts are prepared where alkyl phenol is used as a promoter. However, alkyl phenol is also a major cause for the development of color in the final product. This problem is overcome by the use of propylene oxide which displaces the hydrogen of the phenolic hydroxyl group and thereby restricts the formation of colored species. However, there are disadvantages associated with this approach, principally due to the toxic nature of propylene oxide. Propylene oxide is classified as a possible carcinogen and laboratory animal inhalation studies have shown evidence of a link to cancer. Propylene oxide is also listed as a severe eye irritant, and prolonged exposure to propylene oxide vapors may result in permanent damage to the eye. Furthermore, propylene oxide is extremely flammable and explosive in nature under certain conditions. Propylene oxide boils at 94° F. and flashes at −20° F. As a result, extreme precautions are required to handle propylene oxide at the plant site. Special storage equipment is required for propylene oxide and other safety features are necessary. U.S. Pat. No. 4,665,117 describes the use of propylene oxide at 150° C. At this temperature, propylene oxide will be in the gaseous phase. Under these operating conditions, more than stoichiometric amounts of propylene oxide are required to carry the reaction to completion because propylene oxide will escape from the reaction mixture and this requires additional handling of the excess propylene oxide.
With the movement in the plastics industry to remove heavy metals, liquid calcium-zinc stabilizers are desirous, but not practical, as replacements for barium-cadmium or barium-zinc. Low metal concentrations, poor compatibility, haziness in clear products and plate out during processing in PVC have severely limited the universal acceptance of calcium based liquid stabilizer compositions. Problems are encountered in the stability of these compositions upon standing or storage. Storage stability is due to the incompatibility among the metal salts employed in the composition and is exhibited by increased turbidity, viscosity, or insoluble solids over time. As a result, the liquid calcium compositions are no longer homogeneous or readily pourable and must be specially treated in order to be used. U.S. Pat. No. 5,322,872 is directed to stabilized compositions of mixed metal carboxylates having improved storage stability. According to this patent, a complexing agent is added to the mixed metal carboxylate in order to improve shelf stability. Complexing agents disclosed in this patent include phosphines, phosphites, aromatic cyanides, aromatic hydroxy compounds, oximes and other compounds. U.S. Pat. Nos. 5,830,935 and 5,859,267 have also issued as directed to processes for improving basic metal salts and stabilizing halogen-containing polymers therewith.
Notwithstanding the state of the art as exemplified by the above patents, there is a need for further improvements in making shelf stable compositions of overbased alkaline earth metal carboxylates and in methods for their use in stabilizing halogen-containing polymers.
SUMMARY
The present invention relates to a shelf stable haze free liquid of an overbased alkaline earth metal salt of a fatty acid. In a preferred form, these liquids contain an alkaline earth metal carbonate, an alkaline earth metal carboxylate of a fatty acid, a liquid hydrocarbon, and an aliphatic alcohol having at least 8 carbon atoms. These liquids are referred to sometimes hereinafter more simply as “overbased alkaline earth metal salt(s)” or “overbased alkaline earth metal carboxylate(s)/carbonate(s)”. Liquid overbased calcium and barium salts are preferably provided and, in a preferred form of the invention, the liquids are essentially free of a phenol or a phenolic derivative.
The invention also relates to a process for preparing the shelf stable haze free liquid of an overbased alkaline earth metal salt of a fatty acid. The process involves reacting an alkaline earth metal base and a fatty acid with an equivalent ratio of metal base to fatty acid being greater than 1:1 in the presence of a liquid hydrocarbon. A surfactant and catalyst are used to promote the reaction. The mixture is acidified, preferably by carbonation, to produce an amorphous alkaline earth metal carbonate. During carbonation, a dispersion of alkaline earth metal base, a liquid hydrocarbon, and an aliphatic alcohol having at least 8 carbon atoms, is added in relative amounts to produce a stable haze free liquid reaction product. Water is removed from the reaction product to obtain a shelf stable haze free liquid overbased alkaline earth metal salt.
It has been found important during carbonation to add the dispersion of metal base, liquid hydrocarbon and aliphatic alcohol in relative amounts at a controlled rate to produce the stable haze free reaction product. There are a number of reasons which are believed to contribute to the formation of a stable haze free liquid which is then filterable to remove impurities and byproducts of the reaction. Up to the discoveries made in accordance with the principles of this invention, it was not considered possible to make in a practical or commercial operation an overbased calcium fatty acid salt, for example, that may be filtered at commercial or practical rates to remove unwanted impurities and byproducts of the reaction to produce a shelf stable haze free liquid. In contrast, it has been found that by the continuous addition of the dispersion or slurry of base during carbonation, such results are achievable. It is believed that the metal base slurry prevents the formation of undesirable calcium carbonate crystals or byproducts in the desired overbased metal salt. These undesirable moieties prevent the formation of stable haze free products which are filterable. In other words, the metal base slurry is added at a controlled rate which does not exceed the rate of the desired product-forming reaction. The reaction is controlled by continuous or incremental addition of the metal base to make the calcium ions immediately available for the desired reaction as opposed to allowing the metal base, for example lime, to react and form a byproduct. Excessive byproduct or lime coated with calcium carbonate is believed to render the liquid product
Dominey Lawrence A.
Ramey Chester E.
Reddy James E.
Carr Deborah D.
OMG Americas, Inc.
Wood Herron & Evans L.L.P.
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