Method for dissolution of polymerized soil

Abstract

A method for removing polymerized soil by adding to the soil a composition which includes: (a) from 4 to 30 wt % of a hydroxide or alkoxide, (b) from 10 to 96 wt % of a C1-C12 primary alcohol; and (c) from 0 to 75 wt % of an organic solvent which is not a C1-C12 primary alcohol; wherein the composition contains no more than 40 wt % water.

Description

BACKGROUND

This invention relates generally to a method for dissolution of polymerized soil, especially residue from unsaturated triglycerides.

Cleaners which claim to be effective in removal of polymerized triglycerides have been reported, e.g., in U.S. Pat. No. 8,246,696. However, known cleaning products do not remove polymerized triglycerides efficiently. A composition capable of removing polymerized triglycerides quickly would be a desirable product.

STATEMENT OF INVENTION

The present invention is directed to a method for removing polymerized soil; said method comprising adding to the soil a composition which comprises: (a) from 4 to 30 wt % of a hydroxide or alkoxide, (b) from 10 to 96 wt % of a C₁-C₁₂ primary alcohol; and (c) from 0 to 75 wt % of an organic solvent which is not a C₁-C₁₂ primary alcohol; wherein the composition contains no more than 40 wt % water.

DETAILED DESCRIPTION

All percentages are weight percentages, and all temperatures are in ° C., unless otherwise indicated. Operations are performed at room temperature (20-25° C.) unless otherwise indicated. “Triglycerides” are natural fats or oils comprising glycerine triesters of fatty acids. Preferably, triglycerides are in the form of vegetable oils. Fatty acids are acyclic aliphatic carboxylic acids containing from 8 to 22 carbon atoms; typically, they contain from 12 to 22 carbon atoms. In most natural triglycerides, at least 95% of the fatty acid residues have from 16 to 18 carbon atoms. With respect to carbon-carbon bonds, the fatty acids may be saturated, monounsaturated or polyunsaturated (typically 2 or 3 carbon-carbon double bonds). Preferably, the polymerized soil is an oxidation product of a triglyceride comprising esterified polyunsaturated fatty acids, especially those having some esterified fatty acids with two non-conjugated double bonds. Preferred triglycerides include soybean oil, corn oil, sunflower oil, canola oil, hempseed oil, flaxseed oil, peanut oil, safflower oil, cottonseed oil and palm oil. Particularly preferred triglycerides include soybean oil, corn oil, sunflower oil, canola oil and safflower oil. The triglyceride can be isolated from naturally occurring seed sources or from genetically modified seed sources which may have enhanced levels of certain fatty acids, e.g., monounsaturated fatty acids or conjugated polyunsaturated fatty acids. A “glycol” is an aliphatic compound having two hydroxyl groups, preferably ethylene glycol, propylene glycol or oligomers thereof. An “organic solvent” is a compound or mixture of compounds that is liquid at 25° C. and 101 kPa, and contains no elements other than carbon, hydrogen and oxygen, except for trace levels of impurities.

Preferably, the soil is a triglyceride which has been polymerized by oxidation at high temperatures, such as those encountered in a deep fryer. Preferably, the polymerization occurred at a temperature of at least 250° C., preferably at least 300° C.

Preferably, the hydroxide or alkoxide is a salt of an alkali metal ion, ammonium hydroxide or tetraalkylammonium hydroxide or alkoxide, preferably sodium or potassium hydroxide or alkoxide, preferably potassium hydroxide or alkoxide. Preferred alkoxides include methoxide, ethoxide, propoxide and butoxide; preferably methoxide, ethoxide, n-propoxide and n-butoxide; especially methoxide and ethoxide. Preferably, component (a) is a hydroxide, preferably sodium or potassium, preferably potassium. Weights of hydroxides or alkoxides are on an “as is” basis, i.e., including any water present in commercial solid products. The composition may contain more than one hydroxide or alkoxide. Preferably, the composition comprises at least 5 wt % hydroxide or alkoxide, preferably at least 6 wt %, preferably at least 7 wt %, preferably at least 8 wt %; preferably no more than 25 wt %, preferably no more than 20 wt %, preferably no more than 15 wt %.

A C₁-C₁₂ primary alcohol is an alcohol having a C₁-C₁₂ hydrocarbyl chain containing no oxygen atoms. Preferably, the C₁-C₁₂ primary alcohol is limited to a C₁-C₈ primary alcohol; preferably methanol, ethanol, n-propanol, n-butanol, isobutanol, n-pentanol, isoamyl alcohol, n-hexanol, 2-ethylhexanol, 3-cyclohexene-1-methanol, hydroxymethylcyclohexane, 6-methyl-3-cyclohexene-1-methanol or benzyl alcohol; preferably methanol, ethanol, n-propanol, n-butanol or benzyl alcohol; preferably methanol, ethanol or benzyl alcohol; preferably methanol or ethanol. Combinations of alcohols may be used. When ethanol is used, it may be in the form of a 95% ethanol/5% water mixture and/or contain small amounts of denaturants such as methanol, toluene, methyl isobutyl ketone, etc. Preferably, the composition comprises at least 20 wt % C₁-C₁₂ primary alcohol, preferably at least 25 wt %, preferably at least 30 wt %, preferably at least 35 wt %, preferably at least 40 wt %; preferably no more than 92 wt %, preferably no more than 90 wt %, preferably no more than 85 wt %, preferably no more than 80 wt %, preferably no more than 75 wt %, preferably no more than 70 wt %, preferably no more than 65 wt %. In a preferred embodiment of the invention, the primary alcohol may be added to the composition partially or completely in the form of an alkoxide.

Preferably, the organic solvent is a glycol, glycol ether (including oligomers of ethylene oxide and/or propylene oxide) or ester; preferably a glycol mono-ether having at least a three-carbon alkyl group. Mixtures of solvents may be used. Preferably, the organic solvent is aliphatic. Preferably, the organic solvent is not an alcohol. Preferably the organic solvent has from 5 to 22 carbon atoms; preferably at least 6 carbon atoms, preferably at least 7 carbon atoms, preferably at least 8 carbon atoms; preferably no more than 18 carbon atoms, preferably no more than 16 carbon atoms, preferably no more than 14 carbon atoms. Preferably, the organic solvent has at least one oxygen atom, preferably at least two. The organic solvent may contain water, but preferably the water content of the entire composition is no more than 35 wt %, preferably no more than 30 wt %, preferably no more than 25 wt %, preferably no more than 20 wt %, preferably no more than 15 wt %, preferably no more than 10 wt %, preferably no more than 5 wt %. Preferably, the composition comprises at least 5 wt % organic solvent, preferably at least 10 wt %, preferably at least 15 wt %, preferably at least 20 wt %, preferably at least 25 wt %, preferably at least 30 wt %; preferably no more than 70 wt %, preferably no more than 65 wt %, preferably no more than 60 wt %, preferably no more than 55 wt %.

In one preferred embodiment of the invention, the primary alcohol(s) also acts as a solvent and the composition comprises from 4 to 30 wt % of a hydroxide or alkoxide and from 70 to 96 wt % of a C₁-C₁₂ primary alcohol. Preferably, the composition comprises at least 5 wt % hydroxide or alkoxide, preferably at least 6 wt %, preferably at least 7 wt %, preferably at least 8 wt %; preferably no more than 25 wt %, preferably no more than 20 wt %. Preferably, the composition comprises at least 75 wt % C₁-C₁₂ primary alcohol, preferably at least 80 wt %; preferably no more than 95 wt %, preferably no more than 94 wt %, preferably no more than 93 wt %, preferably no more than 92 wt %.

EXAMPLES

Soybean oil was held at a temperature of 350° C. for 24 hours in a 3-4 mm layer on an aluminum pan. The resulting soil was an orange-brown material with a rubbery consistency. The cleaning compositions described below were contacted with the soil at ambient temperature and the results are recorded in the table. Experiments below the double line are comparative.

alcohol/wt %	base/wt %	solvent/wt %	result
methanol/47	KOH/7	ethyl laurate/47	removed soil in 13 min
methanol/47	KOH/7	DOWANOL	removed soil in 18 min
		DPnB/47
ethanol/56	KOH/6	DOWANOL	removed soil in 30 min
		DPnB/39
ethanol/87	KOH/13	none	removed soil in 15 min
benzyl	KOH/6	water/9	removed soil in 1 h (10
alcohol/85			min @ 65° C.)
methanol/47	KOH/7	water/47	soil was not removed in
			24 h
methanol/47	KOH/7	none, CTAC/47	soil was removed after 2 h
isopropanol/47	KOH/7	water/47	soil was removed after 2 h
isopropanol/47	KOH/7	none, CTAC/47	soil was removed after 2 h
none	KOH/7	ethyl laurate/47,	soil was not removed in
		CTAC/47	24 h
isopropanol/47	KOH/7	ethyl laurate/47	soil was removed after 2 h
methanol/4	KOH/7	ethyl laurate/47,	precipitate-did not remove
		CTAC/43	soil
methanol/50	none	ethyl laurate/50	soil was not removed in
			24 h
none	DMDA/50	DOWANOL	soil was not removed in
		DPnB/50	24 h
methanol/4	KOH/7	DOWANOL	soil partially removed in
		DPnB/89	24 h
isopropanol/62	KOH/5	DOWANOL	soil was removed after 2 h
		DPnB/33
none	NaOEt/23	DOWANOL	not soluble, soil not
		DPnB/77	removed
PG/67	KOH/4	DOWANOL	soil was not removed in
		DPnB/28	24 h
PG/51	KOH/6	DOWANOL	soil was not removed in
		DPnB/43	24 h
DEG/59	KOH/5	DOWANOL	soil was not removed in
		DPnB/36	24 h
methanol/4,	KOH/5	DOWANOL	soil was not removed in
DEG/57		DPnB/34	24 h
methanol/3,	KOH/5	ethyl laurate/35	soil was not removed in
DEG/57			24 h
n-octanol/78	KOH/3	DOWANOL	soil was not removed in
		DPnB/19	24 h
DOWANOL DPnB is dipropylene glycol mono-butyl ether;
CTAC is cetyl trimethylammonium chloride;
DMDA is N,N-dimethyldecylamine;
NaOEt is sodium ethoxide;
DEG is diethylene glycol

Claims

1. A method for removing polymerized soil; said method comprising adding to the soil a composition which comprises: (a) 6 to 30 wt % of a hydroxide or alkoxide, (b) from 10 to 96 wt % of a C1-C12 primary alcohol; and (c) from 0 to 75 wt % of an organic solvent which is not a C1-C12 primary alcohol; wherein the composition contains no more than 40 wt % water; wherein the soil is a triglyceride which has been polymerized by oxidation at a temperature at least 250° C.

2. The method of claim 1 in which the composition contains no more than 30 wt % water.

3. The method of claim 2 in which the composition comprises from 30 to 95 wt % of a C1-C12 primary alcohol.

4. The method of claim 3 in which the composition comprises from 5 to 20 wt % of a hydroxide or alkoxide.

5. The method of claim 4 in which the composition comprises from 20 to 60 wt % of said organic solvent.

6. The method of claim 4 in which the composition comprises no more than 15 wt % water.

7. The method of claim 4 in which the composition comprises from 80 to 95 wt % of a C1-C12 primary alcohol.

8. The method of claim 1 in which the C1-C12 primary alcohol is methanol, ethanol, n-propanol, n-butanol, isobutanol, n-pentanol, n-hexanol, 2-ethylhexanol, 3-cyclohexene-1-methanol, hydroxymethylcyclohexane, 6-methyl-3-cyclohexene-l-methanol or benzyl alcohol.

9. The method of claim 8 in which the composition comprises no more than 15 wt % water.