Offshore rig cleaner - Patent Review 5336428

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This invention is devoted to an offshore platform cleaner for offshore rigs. Where the oil industry removes oil from underneath the Gulf or ocean some necessary criteria for such a platform cleaner dictate that it contain a good solvent for hydrocarbon and grease solubilization, a surfactant for degreasing and coupling the solvent into a water system, a thickening agent to allow the product to cling to vertical surfaces, and a dye for esthetic reasons.

PRIOR ART

U.S. Pat. No. 4,336,152 Like, et al. (American Cyanamid Company)--a disinfectant cleaner including a nonionic surfactant, d-limonene, a phosphate building, and a quaternary ammonium compound and optionally a lower aliphatic alcohol. The surplusage of components here renders this reference of limited applicability.

U.S. Pat. No. 4,362,638 Caskey, et al. (S. C. Johnson & Son)--uses 8 moles of ethylene oxide reacted with nonyl phenol, d-limonene, butoxy propanol, and water. Utilization of this reference would apply a shotgun disclosure which is not close to applicant's invention.

The differences between the prior art cited and the present invention are clearly shown in the composition below, known as Composition A.

______________________________________ Component Description Weight Percent ______________________________________ Soft Water 78.716 9-10 Mole Ethoxylated 15.000 Nonyl Phenol d-Limonene 5.000 Acid Blue 9 Dye 0.004 Ethyl acrylate methacrylic acid 1.000 50% Sodium Hydroxide 0.180 12M Hydrochloric Acid 0.100 ______________________________________

The solvent selections turn to terpenes which are a class of organic solvents derived from woody plants or citrus fruits. They are known to possess good solvency characteristics without having the adverse environmental and safety concerns often associated with many solvents derived from petrochemical sources. Mammalian toxicity is relatively low and many terpenes are listed on the Federal Food and Drug Administration's GRAS ( generally regarded as safe) list as food additives and flavorings.

In Table 1 are terpenes examined for use in Composition A.

TABLE 1 ______________________________________ Terpene Manufacturer ______________________________________ TABS-C* Union Camp TABS-D* Union Camp Acintine LS-160A* Arizona Chemical Company Acintine LS-160B* Arizona Chemical Company Acintine LS-160D* Arizona Chemical Company Acintine LS-165D* Arizona Chemical Company d-Limonene (untreated grade) Florida Chemical Company d-Limonene (lemon-lime grade) Florida Chemical Company d-Limonene ("0" grade) Florida Chemical Company ______________________________________ *Naturally occurring from pine trees

All the terpenes in Table 1 would be adequate. d-Limonene was selected. ##STR1##

d-Limonene had the solvency power, pleasant citrus odor, and comparatively low price required for incorporation into the Composition A solvent. It is produced commercially by expression of citrus (mainly orange, lemon, and grapefruit) peel and pulp. In the final component description, d-limonene was utilized in 5-7% by weight.

SURFACTANT SELECTION

The selection of the proper surfactant for Composition A posed some difficulties due to clouding at different temperatures caused by the presence of d-limonene. It was early found that a ratio of 3:1 surfactant to d-limonene was found to be necessary to give clear solutions over the entire temperature range from freezing to the cloud point. The 5-7% range for d-limonene thus required at least 15-21% of the surfactant, chosen to be a non-ionic surfactant. The best and most satisfactory surfactant was 9-10 mole % ethoxylated nonylphenol, which is available from various sources such as Triton N-101 (Rohm & Haas), Surfonic 95 (Texaco), and L-237M (Nalco Chemical). Also, the comparative 8-10 mole ethoxylated octylphenol is a surfactant of choice. Since we earlier decided to use a 5% d-limonene in a composition according to this invention, 15% of the surfactant was needed as the coupling agent.

Table 2 shows the proper ratio of Triton N-101 to d-limonene in Composition A.

TABLE 2 ______________________________________ Proper Ratio of Triton N-101 to d-Limonene in Composition A Ratio of Triton N-101 Appearance on Cooling to d-Limonene to 34.degree. F. ______________________________________ 1.0:1 Cloudy 2.0:1 Cloudy 2.4:1 Cloudy 2.8:1 Hazy 3.0:1 Clear 3.2:1 Clear 3.6:1 Clear ______________________________________

THICKENER SELECTION

One of the attributes of any general purpose cleaner used for rig degreasing is enhanced viscosity. This property allows a cleaner to cling to vertical surfaces for longer time periods. Viscosity is also associated with increased activity by many customers.

Some testing work was done to evaluate powdered thickeners such as Aqualon's CMC. 7MT, a carboxymethyl cellulose. Although the CMC thickened nicely, it was difficult to disperse and dissolve. A convenient liquid thickener that gave good enhanced viscosity was Rohm & Haas' acrylic copolymer emulsion, Acrysol ASE-95, believed to be a copolymer of ethylacrylate and methacrylic acid in emulsion form.

The pH must be raised initially to hydrolyze ethyl acrylate/methacrylic acid in order to clear up the solution. Without at least an initial pH elevation, the solution will not thicken.

DYE SELECTION

In the dye selection, since the primary use sites for Composition A will be offshore, it was decided to color the product with a bright blue colorant. Acid Blue 9 dye was utilized in the final Visclean formula.

The first formulations of Composition A were made by adding the surfactant to the d-limonene and then diluting the mixture with water. The order of addition was later changed to water then surfactant then d-limonene to facilitate manufacture. This order of addition also worked well and was used for all subsequent large scale preparations.

TABLE 3 ______________________________________ Partial List of Surfactants Examined for Composition A Surfactant* Reason for Rejection ______________________________________ Triton X-45 Formed "strings` on dilution 5 mole ethoxylated octyl- phenol from Rohm & Haas Triton X-100 Clouded on cooling 10 mole ethoxylated octyl- phenol from Rohm & Haas Triton N-101 Good dissolution, but 9-10 mole etholyated clouded on cooling nonylphenol from Rohm & Haas Bio Terge PAS-85 Not soluble in d-limonene Sodium 1-octane sulfonate from Stepan A-22F Clouded on cooling Blend of surfactants from Nalco - ethoxylated nonyl- phenol and castor oil Aromox DM16 Clouded on cooling Dimethylhexadecylamine oxide from Akzo Chemie Tween 20 Milky on cooling POE (20) sorbitan mono- laurate from ICI Tween 80 Clouded on cooling POE (20) sorbitan mono- oleate from ICI DDBSA Fumes emitted on mixing with Dodecylbenzene sulfonic d-limonene acid from Nalco Na DDBS Clouded on cooling Sodium dodecylbenzene sulfonate from Nalco ______________________________________ *All were used at a ratio of 1 part surfactant to 1 part dlimonene

TABLE 4 ______________________________________ Final Formula for Composition A A blend of the following components: Component Description Weight Percent ______________________________________ Soft Water 78.716 9-10 Mole Ethoxylated 15.000 Nonyl Phenol d-Limonene 5.000 Acid Blue 9 Dye 0.004 Ethyl acrylate/methacrylic acid 1.000 50% Sodium Hydroxide 0.180 12M Hydrochloric Acid 0.100 ______________________________________

It has been found that is these compositions, that 5-7% d-limonene is optimal and that it requires about 3 times that much or 15-21% of surfactant to clarify the composition.

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