MXPA01000334A

MXPA01000334A - Liquid carbon dioxide cleaning utilizing natural and modified natural solvents.

Info

Publication number: MXPA01000334A
Application number: MXPA01000334A
Authority: MX
Inventors: M Purer Edna
Original assignee: Raytheon Co
Priority date: 1999-06-11
Filing date: 2000-05-11
Publication date: 2002-04-24
Also published as: JP2003502135A; AU5440200A; ID28922A; EP1144565A3; EP1144565A2; IL139799A0; AU2003231689A1; CN1320183A; WO2000077135A3; WO2000077135A2; CA2337529A1

Abstract

An article having soil in contact therewith is cleaned by treating at least a portion of the article with a bio diesel compound, and agitating the article in contact with dense phase carbon dioxide to dislodge the soil from the article. The bio diesel compound may be used in a pre treatment step, during the agitation step, or both. The bio diesel compound may be mixed with water and or a cleaning enzyme.

Description

CLEANING WITH LIQUID CARBON DIOXIDE USING MODIFIED NATURAL AND NATURAL SOLVENTS BACKGROUND OF THE INVENTION This invention relates to the cleaning of articles and, more specifically, to a method for improving cleaning processes with carbon dioxide. Conventional organic cleaning solvents historically used in the domestic, industrial and commercial markets, such as perchlorethylene, CFC-113, 1,1,1-trichloroethane and petroleum-based solvents, present health and safety risks, because they can be carcinogenic or flammable. Solvents can also be environmentally damaging, because they deplete the ozone layer or produce smoke. The strong regulatory controls exercised over the manufacture and use of these solvents have resulted in an escalation of operating costs and responsibilities for all market segments related to these products. As a result, alternative cleaning means have been developed and implemented to reduce the health and environmental risks associated with cleaning. Water as a degreasing medium has limitations, because it requires a drying step after cleaning, and the cleaning process is often prolonged and requires intensive use of energy. Water also has a poor solvency of organic stains, so additives and vigorous stirring are usually required to remove organic stains. The treatment of the effluent can be expensive, before its discharge. Carbon dioxide is a cheap and unlimited natural resource that is non-toxic, non-flammable, does not produce smoke, and does not deplete ozone. In its dense phases, both liquid and supercritical, it exhibits solvation properties typical of hydrocarbon solvents. The dissolved matter of carbon dioxide in dense phase can be easily recovered in its concentrated form by gassing carbon dioxide. There is no secondary residual flow such as that associated with the use of conventional solvents. Carbon dioxide does not damage fabrics or dissolve common dyes, and its properties make it a good means of dry cleaning for fabrics and clothing. It is also suitable as a degreasing / cleaning agent for the removal of light oils from commercial and industrial parts and components. The dense phase carbon dioxide has been referred to as a cleaning fluid for garments and components in numerous patents, including, for example, U.S. Patent 5,013,366; 5,316,591; 4,012,194; 5,467,492; and 5,267,455. One disadvantage of dense phase carbon dioxide is that it is a relatively moderate solvent, not very suitable for oils and heavy fats. Also, it does not remove hydrophilic stains. As a result, some processes with dense phase carbon dioxide have incorporated additives that increase or modify the total solvency of carbon dioxide itself by organophilic stains, or help to cosolvate hydrophilic stains by their ability to carry water to the dioxide medium. carbon in dense phase. The use of such additives is referred to in numerous patents, including, for example, U.S. Patents 5,683,977; 5,683,473; 5,676,705; 5,866,005; and 5,789,505. The typical additives used to increase the solvation potency of organic compounds of dense phase carbon dioxide have been the same compounds that are being displaced due to their hazardous nature. Examples include cosolvents such as lower alkanes, terpenes, alcohols, ketones, benzene, toluene, xylenes, and chlorinated, fluorinated, or chlorofluorinated compounds. Also typically, the separation or removal of ionic or water soluble stains has been improved by the molecular design of surfactants designed to carry water to the carbon dioxide medium. The disadvantage of these additives is their cost, since they require an elaborate synthesis. Surfactants may also require the use of cosolvents discussed above, which makes fail the beneficial nature for the health and environmental associated with the use of carbon dioxide in dense phase. There is a need to improve the efficiency of cleaning processes with liquid carbon dioxide, which are aimed at the removal of oils, fats, and heavier hydrophilic stains, while still maintaining the health and environmental benefits of the solvent of carbon dioxide in dense phase in bulk. The present invention satisfies this need, and further provides related advantages.

BRIEF DESCRIPTION OF THE INVENTION This invention provides a method and apparatus for cleaning articles with dense phase carbon dioxide. The method of the invention retains a good effectiveness in the removal of particulate stains from articles, and has greater effectiveness in the removal of grease, oil and hydrophilic stains compared to the use of dense phase carbon dioxide only. The method makes use of modified natural and natural additives with good solvation properties. The additives are environmentally friendly, non-toxic, biodegradable, and free of sulfur and aromatic compounds. They can be rinsed with water and form stable emulsions with other phases such as water, mineral spirits, alcohols and some terpenes. The additives can be used in conjunction with known dense phase carbon dioxide cleaning processes. According to the invention, a method for cleaning an article comprises the steps of providing an article having a stain in contact with it, treating at least a portion of the article with a biodiesel compound, and contacting the article with dioxide. carbon in dense phase to detach the stain from the article. Optionally, the article can be rinsed to remove the biodiesel compound, if present after completing the contact. The "biodiesel compounds" are a recognized class comprising alkyl monoesters of vegetable oils, preferably the methyl esters of vegetable oils. Examples of suitable vegetable oils are safflower, sunflower, canola and soybean oils. The biodiesel compounds are completely compatible with carbon dioxide in dense phase (liquefied or supercritical). The term "biodiesel" originates from an unrelated use of such compounds as ingredients in a synthetic diesel fuel. The item to be cleaned may be a fabric or other items such as metal, ceramic or plastic parts to be degreased and cleaned. The contact of the biodiesel compound with the article and the agitation of the article may be carried out completely or partially in series, or simultaneously, as appropriate for the particular applications. Thus, for example, the article can be pretreated with a biodiesel compound and subsequently placed in a dense phase carbon dioxide source in a pressurized and agitated chamber. The biodiesel compound can instead be added to the source of dense phase carbon dioxide in an in itself treatment. A combination of pretreatment and treatment in itself can be used. The pretreatment may be a general pretreatment such as washing or a localized pretreatment such as "staining" of a fabric. The biodiesel compound can be formed in an emulsion with water and / or enzymes, and is used in any of those alternatives of pretreatment and treatment in itself. The contact and agitation may be effected by any operable method, such as, for example, the force of the dense phase carbon dioxide liquid jets directed towards the source, the bubbling as some of the dense phase carbon dioxide is removed. evaporates, a tumbling action, agitation of the source by an impeller, circulation of the carbon dioxide with a pump, and ultrasonic cavitation. Thus, a variety of treatment and agitation methods using the biodiesel compound are within the scope of the invention. The invention provides an improved method for cleaning processes using dense phase carbon dioxide as a cleaning medium. The method is directed to the use of specific natural additive compounds (for example enzymes) and modified natural ones (for example, biodiesel) that increase the cleaning efficiency and solvate power of carbon dioxide (liquid) in dense phase. The function of the biodiesel compound, alone or in conjunction with additives such as water and / or enzymes, is solvate and mobilize organic compounds such as oils and fats, as well as hydrophilic particle stains, so that they can be detached more easily from the article being cleaned by the agitation of carbon dioxide in dense phase. These additives, alone or as carriers of enzymes and / or water, are environmentally friendly, non-toxic, biodegradable, and free of sulfur or aromatic compounds. The method of the invention increases the effectiveness of the liquid carbon dioxide cleaning medium to remove oils, fats and heavy hydrophilic stains, and retains both its health and environmentally benign properties as a solvent. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention, however, is not limited to this preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow block diagram of a preferred embodiment of a method according to the invention; Figure 2 is a schematic diagram of the system of an apparatus used in the method of Figure i; and Figure 3 is a representation of a chemical reaction used to produce a biodiesel compound.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 describes a preferred method for practicing the invention. An apparatus, number 20 is provided. The apparatus may be of any operable type to carry out the remaining steps of the process, and Figure 2 describes a preferred apparatus mode 40 most suitable for commercial fabric cleaning operations. The apparatus 40 includes a cleaning chamber 42 having a pressure vessel 44 and a pressure port 46 which seals the pressure vessel 44. The cleaning chamber 42 is designed to withstand the internal pressures used in the subsequent steps, typically in the range of about 550 pounds per square inch (psi) (3792.08 kPa) to about 100 psi (689.47 kPa), preferably about 700-800 psi (4826.29-5515.76 kPa), and is made of steel. A perforated basket 48 with openings therein is supported within the cleaning chamber 42, with an open end facing the pressure door 46, so that the articles can be placed and not removed from the perforated basket 48 when the door pressure 46 opens. In the illustrated embodiment, the pressure vessel 44 and the perforated basket 48 are symmetrically cylindrical about a cylindrical shaft 50. The dense phase carbon dioxide cleaning means is released into the cleaning chamber 42 by one or more multiple 52. The additives are mixed with the dense phase carbon dioxide, as will be discussed later. Each manifold 52 has one or more jet orifices 54 therein through which dense phase carbon dioxide flows. The orifices of the jet 54 are preferably arranged so that the flow of cleaning mode of the jet orifices 54 is directed towards the interior of the perforated basket 48 through the openings therein and consequently around the articles that are being cleaned. In the operation of the apparatus 40, the dense phase carbon dioxide is pumped through the manifolds 52 and into the cleaning chamber 42 by a main pump 56 which operates through the appropriate valves 58 and 60. The cleaning medium The dense phase carbon dioxide is initially pumped to a pre-set depth within the cleaning chamber 42 to form a source of liquefied cleaning medium. After reaching the depth of the desired source, additional dense phase carbon dioxide is forced through the jet orifices 54 to agitate the source and the articles therein. After passing through the cleaning chamber 42, the dense phase carbon dioxide cleaning medium flows into a separate particle trap 62, which filters the solid matter from the cleaning medium. (The separate particle trap 62 can be omitted where fabric articles are not cleaned). A valve 66 allows the dense phase carbon dioxide to be routed to a more thorough filtration train 68, to a condenser 70 having a cooling system 72, and again to the inlet side of the main pump 56 through a valve 74. In a "bypass" arrangement, valve 66 allows dense phase drained carbon dioxide to be recovered. The liquefied cleaning medium is supplied to the main pump 56 from a storage tank 76, which operates through the valve 74. Optional additives to the liquefied cleaning medium to be discussed later, such as water, enzymes, are supplied on the inlet side of the main pump 56 from an additive supply 78 through an additive pump 80. The cleaning means can also flow from the cleaning chamber 42 back to the inlet side of the main pump 56 to through a drain line 82 that operates through the valve 74, during the "drained" portion of the process. The apparatus 40 further includes a vent valve 84 which allows the cleaning chamber 42 to be vented to the atmosphere. A return path for the gaseous carbon dioxide is provided through a compressor 86 to the condenser 70 or to the storage tank 76 with appropriate valves 88, 90 and 91. During the cleaning of articles, the soluble non-particulate spots are Dissolve in the cleaning medium. To separate the soluble non-particulate dirt from the cleaning medium, a distillation column 92 is provided with the appropriate valving 94 and 96. The distillation is typically carried out off-line, when the cleaning chamber 42 is not in use for cleaning articles. . This apparatus 42 is particularly designed to clean fabrics but can be used to clean other articles as well. The apparatus is commonly used for the type of item to be cleaned. In a typical cleaning cycle, the material to be cleaned is placed in the perforated basket 48 within the cleaning cavity 42, and the pressure door 46 is closed. The valve 91 is opened, and the pressure between the storage tank 76 and the cleaning chamber 42 is equalized. The valve 74 is in a "chamber" position, and the fluid in the storage tank 76 is pumped into the cleaning chamber 42 by the main pump 56 through the valve 58 (in a "chamber" position), up to - that the chamber 42 reaches the desired liquid level. The valves 88 and 90 are closed at this time, and a recirculation circuit is established through the solid particle trap 62, the filtration train 68, the condenser 70, and back to the main pump 58. The main pump 58 releases the necessary flow and pressure drop of the dense phase carbon dioxide (and additives, if present), through the orifices 54 to agitate the load to be cleaned by a dense phase carbon dioxide flow. At the end of the agitation cycle, valves 88 and 90 are opened, valve 58 is changed to "drain", and valve 66 is changed to "deviation". The liquid phase carbon dioxide is drained and recovered again from the cleaning chamber 42 to the storage tank 76 by the main pump 56, through the drain line 82 and the valve 74 (which is now in the position of "drained"). At this point, the cleaning chamber 42 contains the charge that has been cleaned, and gaseous carbon dioxide. The cleaning chamber 42 decompresses to atmospheric pressure after the gas compressor 86 recovers the carbon dioxide vapors back to the storage tank 76. The residual gaseous carbon dioxide is vented through the ventilation valve 84. , the pressure door 46 opens, and the clean load is removed. The method of the present invention can be carried out with this exemplary apparatus 40 when applied to cleaning articles such as fabrics or clothing, but is not limited to this apparatus. For example, other types of agitation contact devices may be used such as a impeller for agitating the source of liquid in the cleaning chamber 42, an ultrasonic excitation transducer to produce the cavitation of the liquid source, or any other techniques discussed here. Returning to Figure 1, an article to be cleaned is provided, number 22. The article can be of any type or operable configuration, as long as it fits inside the perforated basket 48. A preferred application of the present invention is the cleaning of articles. of cloth such as garment, and another preferred application is in the cleaning and degreasing of parts and components.

There are several operable methods for carrying out the cleaning of the articles using the present invention. in one method, the article is optionally pretreated, number 24. In the pretreatment, the article is brought into contact with a pretreatment fluid. The contact may comprise, for example, a spot in contact with the pretreatment fluid or a print and soak in the pretreatment fluid. The article is kept in contact with the pretreatment fluid for a period of time, typically from about 1 minute to about 24 hours, preferably from about 1 minute to about 60 minutes, to allow the pretreatment fluid to solubilize any spots or particulate dirt attached to the article. The pretreatment fluid, where it is used, preferably comprises a biodiesel compound. The biodiesel compounds are alkyl monoesters (specifically, the methyl and ethyl esters) of vegetable oils or fats, preferably the methyl esters of vegetable oils. Examples of suitable vegetable oils are rape, safflower, sunflower, canola, and soybean oils. The biodiesel compounds can be prepared from used frying oil, in a reuse of this residual product. Each of the vegetable oils consists of glycerides derived from many different carboxylic acids, but each oil has its > characteristic composition that does not differ substantially from sample to sample. The biodiesel compounds are obtained by the transesterification reaction where the glycerin molecule in the untreated vegetable oil is replaced by methanol or ethanol as indicated in the reaction described in Figure 3, where R, Rl and R2 are acidic long chain saturated or unsaturated fatty acids. In practice, the chemical reaction of Figure 3 can be effected by mixing the vegetable oil with methanol (or alternatively, ethanol) in the presence of potassium hydroxide, then allowing the mixture to settle. The biodiesel compound is decanted from the top of the reactor, leaving the heavier glycerin at the bottom. This transesterification reaction is referred to in Robert T. Morrison, Organic Chemistry, published by Allyn & Bacon, Inc., 1966, on page 686. Biodiesel compounds have the advantage that they have low viscosities, have low vapor pressures, have densities similar to those of liquefied carbon dioxide, are biodegradable, are not toxic, are sulfur-free and aromatic compounds, and have a relatively high Kaui butanol value of about 60 (compared to perchlorethylene, which is about 90) indicating that they are good organic solvents. They are rinsable in water and easily form emulsions with water, mineral spirits, and some terpenes. They are compatible with a carbon dioxide in dense phase, they have approximately the same specific gravity of 0.9. The biodiesel pretreatment fluid can optionally be mixed with other components, such as water and / or cleaning enzymes. Enzymes are proteins that accelerate (catalyze) a reaction that involves the creation or rupture of a covalent bond. The enzymes act by lowering the temperature under which a given bond is unstable. There are numerous examples where well-defined molecules accelerate reactions between other molecules, but not all enzymatic reactions are specific. For example, several enzymes that degrade proteins in their amino acids are uniquely specific in the sense that they degrade the peptide bond. The enzymes typically work in aqueous medium and have been used for a number of years in cleaning processes and in the formulations of many soaps and detergents. Some examples for the use of formulations that contain enzymes are staining compounds that help to remove stains based on protein (such as blood) from clothing., and detergents that have specific enzymes to help remove grease and oil stains in domestic laundry. More recently, enzymes have been used in aqueous cleaners to promote the degreasing of parts and components. In addition, enzymes are typically not soluble or easily miscible in a dense phase carbon dioxide solvent, and a "carrier" compound, here the biodiesel compound, is necessary to facilitate its introduction into a carbon dioxide process in phase dense Any relative operable amounts of the biodiesel compound and other components can be used. Preferably, the biodiesel compound, or a mixture of the biodiesel compound with enzymes or water in any ratio, is present in the dense phase carbon dioxide in an amount of about 0.01 to about 5 volume percent. Minor quantities are not effective, and larger amounts are wasteful and lead to residual contamination of the cleaned item with the biodiesel compound, which may need to be removed. The pretreatment, if used, can be carried out within the cleaning chamber 42 or in a separate container. The article, which optionally can be pretreated in step 24, is placed in the cleaning apparatus 40, number 26, in this case preferred in the perforated basket 48 of the cleaning chamber 42. The pressure door 46 is closed and sealed A cleaning medium is introduced into the sealed cleaning chamber 42 to form a source therein, number 28, by pumping the cleaning medium of the storage tank 76 using the main pump 56 in the manner described above. The source preferably partially or completely covers the article in the perforated basket 48. The cleaning medium comprises the liquefied carbon dioxide with the addition of one or more of the biodiesel compounds discussed above. The cleaning medium introduced in step 28 may be of the same composition as the cleaning medium of the pretreatment used in step 24, or a medium containing a different biodiesel may be used. Other additives can also be added, such as water and / or enzymes discussed at the beginning. The previous discussion of these different materials is incorporated here. The total amount of additives is, typically from about 0.01 to about 5.0 percent, with a preferred range from about 0.1 to about 1.0 percent, of the total carbon dioxide and additives. The source and the article therein are agitated, number 30. Agitation is achieved in the illustrated apparatus 40 by the action of the cleaning medium pumped through the manifold 52 and the liquid jet orifices 54. For this purpose, the holes of the liquid jet 54 are directed towards the interior of the perforated basket 48 through the openings in it, to collide on the articles to be cleaned therein. The agitation continues for a period of time sufficient to remove the particulate dirt adhered to the article, and to solubilize and remove non-particulate matter such as oils, grease and dirt and hydrophilic stains. This stirring time varies according to the nature of the article, the ability to produce powder from the article, and other factors, but is typically from about 5 to about 30 minutes. The agitation can be effected by any operable method, such as the preferred liquid jets, but also the hydrodynamic cavitation generated by a propellant, impeller, or blade, circulation with a pump or compressor, ultrasonic cavitation produced by transducers, sonic whistles, or a combination of those techniques. After completing the agitation, the cleaning medium is drained from the cleaning chamber 42, number 32. Optionally, the article may be wiped, number 34, by introducing a rinsing medium such as pure liquefied carbon dioxide in the cleaning chamber 42. and shaking the items with the unmodified liquefied carbon dioxide. This step is carried out if the cleaning medium was used with additives, and it is desirable to remove those additives completely from the article before the article is used. For example, if the article is a cloth such as a garment, and the cleaning medium contained some biodiesel compound, it is usually desirable to rinse the biodiesel compound with unmodified liquefied carbon dioxide. In other cases, such as degreasing articles, it may be desirable to leave the biodiesel compound in place as a temporary corrosion resistant coating on the articles. After completing the rinsing step 34, the rinsing medium is drained from the cleaning chamber 42. After recovering most of the liquid and gaseous carbon dioxide back into the store, the residual pressure within the cleaning chamber 42 it is ventilated to atmospheric pressure using the vent valve 84, and the articles are removed from the cleaning chamber 42. Any carbon dioxide is previously evaporated during this ventilation and removal, leaving the article dry and clean after the removal of the cleaning camera. The following examples illustrate the application of the invention, but should not be construed as limiting the scope of the invention in any respect.

Example 1 A load of stainless steel metal parts was treated with various fats, such as CRC Industries No. MSDS SL3310, 3160, 3131, 3141, and Exxon L / M 487211, and with thread cutting oil type C10326 made by W.H. Harvey. The parts were placed in a liquid carbon dioxide cleaning chamber with a capacity of 12 gallons (45.42 liters) 42. Sufficient carbon dioxide was introduced liquid in the chamber to submerge the load. In some cases, a biodiesel compound, commercially sold by Charbon Group, Huntington, CA, was added as SSW-1000, chamber 42 in an amount of 0.1 percent, 0.5 percent, 1.0 percent, or 2.0 percent of the total carbon dioxide and the biodiesel compound. The liquid carbon dioxide cleaning medium (and the biodiesel compound, where it was present) was stirred for 10 minutes at temperatures in the range of 0-85 ° F (0-29.4 ° C), using a cavitation blade and a propellant, to accelerate the removal of grease and oil. The solvent was then drained, the chamber was decompressed, and the parts were removed and examined for the presence of visual and tactile debris. Where a biodiesel compound was not used, only the mineral oil component of the fats was removed, and the extraction soaps and other additives in the fats continued to contaminate the parts in the form of a coating similar to a resistant film. The thread cutting oil remained as an adhesive residue on the parts. Where the biodiesel compound was present, the removal of fats and oils improved in all cases. Some improved removal of grease and oil was observed for 0.1 percent of biodiesel compounds, but complete removal of fats required at least approximately 1.0 percent biodiesel compound. The cut oil residue was removed from 0.2 percent or more of the biodiesel compound. After the treatment, the parts were dried, and there was no evidence of residual biodiesel compound on the parts yet for the 2.0 percent biodiesel compound additive.

Example 2 A charge of stainless steel parts was treated with a polishing compound consisting of heavy waxes and aluminum powder in the range of 20-40 micrometers. The charge was pretreated (step 24) for 30 minutes in biodiesel compound of the same type used in Example 1. After pretreatment, and without drying, the load was placed in the same cleaning chamber used in Example 1, and treated in the same manner as described for Example 1 (steps 26, 28, 30 and 32). Where no biodiesel compound was used in the pretreatment or stirring steps, no substantial removal of the polishing compound was observed. Where the biodiesel compound was present, there was some removal of the polishing compound still for a concentration of 0.1 percent of the biodiesel compound. The complete removal required 1 percent or more of biodiesel compound.

The example was repeated without a pretreatment, for concentrations of the biodiesel compound of 0.1 percent, 0.5 percent, 1.0 percent, 2 percent, and 5 percent in the liquefied carbon dioxide used in steps 28 and 30. The removal The complete polishing compound required a concentration of 5 percent of the biodiesel compound, substantially greater than the 1.0 percent required when a pretreatment was employed. When a 5 percent concentration of the biodiesel compound was used, it was necessary to conduct a post-stir rinse (step 34), because there was a light film of the biodiesel compound remaining on the parts after stirring and draining. Examples 1-2 demonstrate that the biodiesel compound improves the cleanliness of the parts. Example 2 shows that pretreatment decreases the amount of biodiesel required in the subsequent treatment and agitation, reducing the need for rinsing after draining.

Example 3 A charge of stainless steel part was immersed in an aqueous, saline, saturated solution, stirred, and allowed to dry. The charge was then placed in the cleaning chamber discussed in Example 1. A solution of liquid carbon dioxide and biodiesel / water compound (0.5% biodiesel compound plus water, 1: 1 volume ratio of biodiesel compound) was introduced. to water) in the chamber and stirred for 10 minutes to solubilize the salt and remove it from the part. The treatment was under the same conditions as discussed for example 1. The chamber was then drained and the parts were removed and inspected. The same experiment was carried out without the presence of biodiesel and water. Where the biodiesel compound and water were present, in the cleaning medium, the salt was removed. Where the biodiesel compound and water were not present in the cleaning medium, the salt was not removed.

EXAMPLE 4 The same polishing compound used in Example 2 was applied to a charge of stainless steel parts, and the filler was placed in the cleaning chamber discussed in Example 1. A solution of liquid carbon dioxide and composed of biodiesel / water / Bacto-zyme enzyme (0.5% biodiesel / water compound / Bacto-zyme enzyme, with a ratio of 1: 1: 1 by volume of biodiesel compound: water: Bacto-zyme enzyme) in the chamber and was stirred for 10 minutes under the conditions discussed in Example 1, except that the temperature was in the range of 40-85 ° F (9.28 ° C-29.44 ° C). The Bacto-zyme discussed in MSDS 1113, is a natural multi-faceted enzymatic agent, which has a complex non-bacterial organic formulation that promotes the penetration and emulsification of oily substances or fats and commercialized by the Charbon Group. The presence of water and Bacto-zyme increased the degreasing compared to the control test where water and Bacto-zyme were not present.

Example 5 A cloth load was stained with thread cutting oil, the stains were treated with concentrated biodiesel compound fluid, and the filler was placed in the cleaning chamber discussed in Example 1. Liquid carbon dioxide was introduced to 55-65 ° F (12.77-18.33 ° C) in the cleaning chamber, and the chamber was stirred for 10 minutes. The fluid was drained, the system was decompressed, and the fabrics were removed for evaluation. No residual cutting oil was visible on the fabrics, which were free of stains and dried when removed. Although the particular embodiments of the invention have been described in detail for purposes of illustration, various modifications or improvements may be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited except by the appended claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property. A method for cleaning an article, characterized in that it comprises the steps of: providing an article that has stains or dirt in contact with it; treat at least a portion of the article with a biodiesel compound; and contacting the article with carbon dioxide in dense phase to remove the stain or dirt from the article.
2. The method according to claim 1, characterized in that the start of the treatment step is prior to a start of the contact step.
3. The method according to claim 1, characterized in that the conclusion of the treatment step is prior to the start of the contact step.
4. The method according to claim 1, characterized in that at least a portion of the treatment step is carried out simultaneously with the contact passage.
5. The method according to claim 1, characterized in that it includes the additional step, after completing the contact step, of rinsing the article to remove the biodiesel compound therefrom.
The method according to claim 5, characterized in that the rinsing step includes the step of rinsing the article with carbon dioxide in dense phase, after having completed the treatment step.
The method according to claim 1, characterized in that the article is selected from a group consisting of a piece of cloth, a metal, a ceramic and a plastic.
The method according to claim 1, characterized in that the contact passage is carried out at a pressure greater than the ambient atmospheric pressure.
The method according to claim 1, characterized in that the treatment step includes the step of mixing the biodiesel compound with water.
10. The method according to claim 1, characterized in that the treatment step includes the step of mixing the biodiesel compound with a cleaning enzyme and water.
The method according to claim 1, characterized in that the article is in contact with a source comprising dense phase carbon dioxide during the contacting step.
The method according to claim 11, characterized in that the source also comprises the biodiesel compound.
The method according to claim 1, characterized in that the contact passage includes the step of directing a flow of liquefied gas around the article.
A method for cleaning an article, characterized in that it comprises the steps of: providing an article having stains or dirt in contact therewith; pre-treating at least a portion of the article with a biodiesel pretreatment cleaning medium; and shaking the article in contact with the carbon dioxide in dense phase to remove the stains or dirt from the article.
15. The method according to claim 14, characterized in that the dense phase carbon dioxide is mixed with a biodiesel compound.
The method according to claim 15, characterized in that the dense phase carbon dioxide is mixed with an additional additive selected from the group consisting of water, an enzyme and mixtures thereof.
The method according to claim 14, characterized in that it includes the additional step, after completing the stirring step, of rinsing the article to remove the biodiesel compound therefrom.
18. A method for cleaning an article, characterized in that it comprises the steps of: providing an article that has stains or dirt in contact with it; stir the article in contact with a mixture of dense phase carbon dioxide and a compound of
19. The method according to claim 18, characterized in that it includes an additional step, after completing the stirring step, of rinsing the article for Remove the biodiesel compound from it. The method according to claim 18, characterized in that the treatment step includes the step of mixing the biodiesel compound with an additional additive selected from the group consisting of water, enzyme and mixtures thereof.