Background of the Invention In a number of industrial applications, it is often desirable to treat the surface of an article or substrate in order to protect the substrate from contaminants. This typically includes controlling and enhancing the barrier properties of a surface to, for example, oils, grease, lipophilic materials, water, hydrophilic solutions, and dirt.

Examples of such applications include SCOTCH GUARD and STAIN MASTERS surface coating materials for textile articles such as furniture, clothing, and carpets to impart resistance to staining, and also treating articles formed from metal such as precision parts. It is often desirable to apply a surface treatment to an article in order to protect an article from foreign matter while also preserving the desirable physical properties of the article. With respect to textile-related articles for example, it is particularly desirable to maintain aesthetic properties relating to hand, drape, and texture.

The application of surface treatment components to a variety of substrates from a carbon dioxide system is described in U. S. Patent No. 6,030,663 to J. McClain et al. However, there remains a need for a convenient way to deliver the coating material into the carbon dioxide system.

Summary of the Invention The present invention provides a process for applying coating materials to surfaces using a benign intermediate delivery vehicle in place of water or organic solvents. The delivery vehicle, referred to as transfer vehicle", has a large surface area to weight ratio. The active coating or treatment material is deposited onto the coating sheet by whatever means are desired. The coating sheet is added to a C02 coating apparatus containing the coating sheet, along with articles to be treated. C02 in the gaseous, liquid, or supercritical state is then added to the vessel. Preferably, the substrates are then agitated in a manor that facilitates direct contact with the surface of the coating sheet consistently over all surfaces.

A first aspect of the present invention is, accordingly, a method for coating or impregnating a substrate with a treatment material. The method comprises the steps of (a) combining a substrate and an inert transfer vehicle in a pressure vessel, the inert transfer vehicle carrying the treatment material; (b) pressurizing the vessel with a carbon dioxide medium (typically comprising at least 30,40 Or 50 percent by weight of carbon dioxide); and then (c) agitating the substrate and the inert transfer vehicle together in the pressure vessel with the substrate and the inert transfer vehicle at least periodically immersed in the carbon dioxide medium so that the treatment material is transferred from the inert transfer vehicle to the substrate.

A second aspect of the present invention is a method for concurrently cleaning a substrate and coating or impregnating the substrate with a treatment material. The method comprises the steps of : (a) combining a substrate and an inert transfer vehicle in a wash vessel, the inert transfer vehicle carrying the treatment material; (b) pressurizing the vessel with a carbon dioxide cleaning medium; and then (c) agitating the substrate and the inert transfer vehicle in the vessel, with the substrate and the inert transfer vehicle at least periodically immersed in the carbon dioxide cleaning medium, so that the substrate is concurrently (i) cleaned by the cleaning medium and (ii) coated or impregnated with the treatment material.

A particular embodiment of the foregoing is a method for concurrently cleaning a textile fabric and imparting stain and water resistance to that textile fabric.

The method comprises the steps of : (a) combining a textile fabric with an inert transfer vehicle in a wash vessel, the inert transfer vehicle carrying a surface treatment component, the surface treatment component comprising a C02-philic segment

selected from the group consisting of fluorine-containing segments, siloxane- containing segments, and mixtures thereof ; (b) pressurizing the vessel with a carbon dioxide cleaning medium; and then (c) agitating the textile fabric and the inert transfer vehicle in the vessel, with the textile fabric and the inert transfer vehicle at least periodically immersed in the carbon dioxide cleaning medium, so that the substrate is concurrently (i) cleaned by the cleaning medium and (ii) coated or impregnated with the treatment material.

The foregoing and other objects and aspects of the present invention are explained in greater detail in the specification set forth below.

Detailed Description of the Preferred Embodiments The invention will now be further described by the preferred embodiments presented herein. It should be understood however that the embodiments are to be interpreted as being illustrative of the invention and not as limiting the invention.

Various substrates may be treated in the process of the invention. Such substrates include, but are not limited to, textile fabrics, porous and non-porous solid substrates such as metals (e. g., metal parts), glass, ceramics, synthetic and natural organic polymers, synthetic and natural inorganic polymers, other natural materials, and composite mixtures thereof. In particular, textile substrates are treated by the process, and encompass a larger number of materials. Such substrates are preferably knit, woven, or non-woven fabrics such as garments, upholstery, carpets, tents, clean room suits, parachutes, footwear, etc. formed from natural or synthetic fibers such as wool, cotton, silk, acetate, etc. Articles (e. g., ties, dresses, blouses, shirts, and the like) formed of silk or acetate are particularly well suited for treatment by the process of the invention. The application of the treatment material is advantageous with respect to medical devices, semiconductors, medical implants, and other articles of manufacture.

1. Carbon Dioxide Media.

The fluid employed in the method of the invention is pressurized fluid preferably comprising carbon dioxide, which is defined to be at a pressure greater than ambient pressure, typically at least 20 bar. For the purposes of the invention, the fluid contains carbon dioxide in a liquid, gaseous, or supercritical phase. If liquid

C02 is used, the temperature employed during the process is preferably below 31°C.

If gaseous C02 is used, it is preferred that the phase be employed at high pressure. As used herein, the term"high pressure"generally refers to C02 having a pressure from about 20 to about 500 bar. With respect to C02, the pressure of the gas is typically greater than 20 bar and less than its critical pressure.

In the preferred embodiment, the C02 medium is utilized in a dense (i. e., "supercritical"or"liquid"or"compressed gas") phase. Such a phase typically employs C02 at a density greater than the critical density, typically greater than 0.5 g/cc. As used herein,"supercritical"means that a fluid medium is at a temperature that is sufficiently high that it cannot be liquified by pressure. The thermodynamic properties of C02 are reported in Hyatt, J. Org. Chem. 49: 5097-5101 (1984); therein, it is stated that the critical temperature of C02 is about 31 °C. For the purposes of the invention, the temperature and pressure conditions of the fluid are defined by the thermophysical properties of pure carbon dioxide.

The carbon dioxide containing fluid used in the process of the invention may be employed in a single (e. g., non-aqueous) or multi-phase system with appropriate liquid components. Such components generally include, but are not limited to, a co- solvent or modifier, a surfactant, a co-surfactant, and other additives such as bleaches, optical brighteners, enzymes, rheology modifiers, sequestering agents, chelants, biocides, antiviral agents, fungicides, acids, polishes, radical sources, plasma, deep UV (photoresist) materials, crosslinking agents (e. g., difunctional monomers), metal soaps, sizing agents, antistatics, antioxidants, UV stabilizers, whiteners, fabric softener builders, detergents, dispersants, hydrotropes, and mixtures thereof. Any or all of the components may be employed in the process of the present invention prior to, during, or after the substrate is contacted by the C02 fluid.

For the purposes of the invention, multi-phase systems refers to processes in which the substrate may be treated in the fluid that contains a solid or fluid phase other than a carbon dioxide fluid phase. Other components in such systems include, for example, water, head pressurizing gases, etc., the selection of which is known in the art. Nonaqueous systems are preferred for sensitive substrates such as metal parts and semiconductor devices.

Examples of suitable co-solvents or modifiers include, but are not limited to, liquid solutes such as oils such as soybean oils (including derivatives thereof) alcohols

(e. g., methanol, ethanol, and isopropanol); fluorinated and other halogenated solvents (e. g., chlorotri-fluoromethane, trichlorofluoromethane, perfluoropropane, chlorodifluoromethane, and sulfur hexafluoride); amines (e. g., N-methyl pyrrolidone); amides (e. g., dimethyl acetamide); aromatic solvents (e. g., benzene, toluene, and xylenes); esters (e. g., ethyl acetate, dibasic esters, and lactate esters); ethers (e. g., diethyl ether, tetrahydrofuran, and glycol ethers); aliphatic hydrocarbons (e. g., methane, ethane, propane, ammonium butane, n-pentane, and hexanes); oxides (e. g., nitrous oxide); olefins (e. g., ethylene and propylene); natural hydrocarbons (e. g., isoprenes, terpenes, and d-limonene); ketones (e. g., acetone and methyl ethyl ketone); organosilicones; alkyl pyrrolidones (e. g., N-methyl pyrrolidone); paraffins (e. g., isoparaffin); petroleum-based solvents and solvent mixtures; and any other compatible solvent or mixture that is available and suitable. Mixtures of the above co-solvents may be used. The above components can be used prior to, during, or after the substrate is contacted by the C02 fluid.

A surfactant or co-surfactant may be used in the fluid in addition to the surface treatment component. Suitable surfactants or co-surfactants are those materials which typically modify the action of the surface treatment component, for example, to enhance contact of the surface treatment component with the substrate. Exemplary co-surfactants that may be used include, but are not limited to, longer chain alcohols (i. e., greater than C8) such as octanol, decanol, dodecanol, cetyl, laurel, and the like; and species containing two or more alcohol groups or other hydrogen bonding functionalities; amides; amines; and other like components. Potentially surface active components which also may be employed as co-surfactants include, but are not limited to, fluorinated small molecules, fluorinated acrylate monomers (e. g., hydrogenated versions), fluorinated alcohols and acids, and the like. Suitable other types of materials that are useful as co-surfactants are well known by those skilled in the art, and may be employed in the process of the present invention. Mixtures of the above may be used.

2. Coating and Impregnation of Substrates.

As noted above, the present invention typically comprises the steps of combining a substrate and an inert transfer vehicle in a pressure vessel, the inert transfer vehicle carrying the treatment material, pressurizing the vessel with a carbon dioxide medium (e. g., as described above) and then agitating the substrate and the

inert transfer vehicle together in the pressure vessel with the substrate and the inert transfer vehicle at least periodically immersed in the carbon dioxide medium so that the treatment material is transferred from the inert transfer vehicle to the substrate.

After agitation, the carbon dioxide medium may be removed from the vessel, the vessel opened, and substrates removed with the treatment material coated thereon or impregnated therein.

Agitation may be carried out by any suitable means, such as by providing carbon dioxide medium outlet jets within the vessel, providing an impeller or reciprocating stirring device, other mechanical device within the vessel for agitation of the fluid, a horizontal or vertical rotating or reciprocating basket within the vessel to contain the inert transfer vehicle and the substrate to be agitated, etc. Particular examples are given in conjunction with cleaning apparatus, below.

Transfer vehicles. Transfer vehicles or transfer substrates used to carry out the invention may be in any suitable form, including but not limited to spheres, particles, shaped objects, sheets, etc. The substrates may be solid or porous (e. g., a natural or synthetic sponge). Porous vehicle substrates are advantageous in that they carry the treatment material on internal sites and have a greater surface area, which provides greater carrying capacity and a more gradual delivery of the treatment agent as it is initially released from external surfaces and subsequently released from internal surfaces. The substrates are inert in that they are insoluble in the carbon dioxide medium. In one preferred embodiment, the transfer substrates are transfer sheets.

Transfer sheets. The transfer sheets used to carry out the present invention are preferably thin, flexible sheets that may be formed of any suitable sheet, including but not limited to woven and non-woven textile fabrics formed from materials such as cotton, polyester, polypropylene, cellulose (e. g., paper), etc. In addition, the transfer sheet can be formed from a porous or nonporous polymer film. Nonpolar materials such as polyester and polypropylene are particularly preferred. The treatment material can be coated and/or impregnated into the transfer sheet by any suitable technique, such as by drying a solution of the material onto the sheet, adhering the material onto the sheet with another adhesive material that is soluble in carbon dioxide, etc. The transfer sheet itself is insoluble in liquid, gas or supercritical carbon dioxide medium.

The amount of treatment material carried by the inert transfer vehicle is preferably predetermined or premeasured, so that a given size, quantity or amount of transfer vehicle will deliver a given amount of treatment material to the vessel. The transfer vehicle may be provided individually or (for sheets) in rolls, spools or the like, and the transfer sheets may be marked with printed indicia to identify the material that is carried, to identify where the material should be cut for a given measure of treatment material. The transfer vehicles may be color-coded by printing different colors on different vehicles to indicate different treatment materials carried thereby, so that the user may add a variety of different combinations of transfer sheets to a vessel for the treatment of a particular load of substrates. The transfer sheets may have scores, perforations or the like formed therein for separating individual portions from a larger segment (e. g., a roll). A plurality of transfer vehicles such as sheets, either physically separate or joined together in a roll or the like, may be provided in a single package for convenient end use.

The transfer vehicles may be coated or impregnated with one or a variety of different treatment materials. Suitable treatment materials include, but are not limited to, sizing agents, surface treatment agents such as hydrophobic agents for imparting water and/or stain resistance, fragrances, etc. Particular treatment materials are discussed in greater detail below.

Sizing agents. While any sizing agent can be used to carry out the present invention, low molecular weigh hydrocarbon resins are particularly advantageous for use as sizing agents in carbon dioxide cleaning processes. These materials are particularly advantageous because of their solubility in carbon dioxide, combined their relatively high deposition rate on the articles to be cleaned without undue removal or extraction from the articles. Further, these materials are advantageous because, the deposition of relatively low amounts provides the desired feel and appearance to the articles to be cleaned.

In general, low molecular weight hydrocarbon resins are resins characterized by a molecular weight of about 500,600 or 800 up to about 1500,2000 or 3000 grams per Mole. In general, such hydrocarbon resins are characterized by a chain length of C4 or C5 to C9 or C10. Suitable resins are available from a variety of sources, such as the ESCOREZTM hydrocarbon resins available from Exxon Chemical, Houston,

Texas, USA, and PICCOTAC BTM, hydrocarbon resin (MW=1650), available from Hercules Inc., Wilmington, Delaware USA.

Surface treatment components. Various surface treatment components may be used in the process of the present invention. A surface treatment component is a material which is entrained in the fluid so as to treat the surface of the substrate and lower the surface tension of the substrate as set forth herein.

The term"treat"refers to the coating or impregnating of the substrate or substrate surface with the surface treatment component, with the surface treatment component tenaciously or permanently adhering to the surface after removal from the fluid, so that it serves as a protective coating thereon for the useful life of the coated substrate (e. g., is able to withstand multiple wash cycles when the substrate is a fabric or garment; is able to withstand a corrosive environment when the substrate is a part such as a metal part), until the substrate is discarded or must be re-treated. If desired, the surface active component may polymerize on the surface, or may be grafted onto the surface. Suitable surface treatment components include, but are not limited to, various monomer and polymer materials. Exemplary monomers include those which may be reactive or non-reactive, and contain fluorinated groups, siloxane groups or mixtures thereof.

Polymers which are employed as surface treatment components may encompass those which contain a segment which has an affinity for carbon dioxide ("CO2-philic") along with a segment which does not have an affinity for carbon dioxide ("C02-phobic") which may be covalently joined to the C02-philic segment.

Reactive and non-reactive polymers may be used. Exemplary C02-philic segments may include a fluorine-containing segment, a siloxane-containing segment, or mixtures thereof.

The fluorine-containing segment is typically a"fluoropolymer". The term "fluoropolymer,"as used herein, has its conventional meaning in the art. See generally Fluoropolymers (L. Wall, Ed. 1972) (Wiley-Interscience Division of John Wiley & Sons) ; see also Fluorine-Containing Polymers, 7 Encyclopedia of Polymer Science and Engineering 256 (H. Mark et al. Eds., 2d Ed. 1985). The term "fluoromonomer"refers to fluorinated precursor monomers which make up the fluoropolymers. Any suitable fluoromonomer may be used in forming the fluoropolymers, including, but not limited to, fluoroacrylate monomers, fluoroolefin

monomers, fluorostyrene monomers, fluoroalkylene oxide monomers (e. g., perfluoropropylene oxide, perfluorocyclohexene oxide), fluorinated vinyl alkyl ether monomers, and the copolymers thereof with suitable comonomers, wherein the comonomers are fluorinated or unfluorinated.

Fluorostyrenes and fluorinated vinyl alkyl ether monomers which may be polymerized by the method of the present invention include, but are not limited to, a- fluorostyrene; (3-fluorostyrene ; a, p-difluorostyrene ; ß, p-difluorostyrene ; a, p, p- trifluorostyrene; a-trifluoromethylstyrene; 2,4,6-Tris (trifluoromethyl) styrene; 2,3,4,5,6-pentafluorostyrene; 2,3,4,5,6-pentafluoro-a-methylstyrene; and 2,3,4,5,6- pentafluoro-p-methylstyrene.

Tetrafluoroethylene copolymers can be used and include, but are not limited to, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene- perfluorovinyl ether copolymers (e. g., copolymers of tetrafluoroethylene with perfluoropropyl vinyl ether), tetrafluoroethylene-ethylene copolymers, and perfluorinated ionomers (e. g., perfluorosulfonate ionomers; perfluorocarboxylate ionomers). High-melting C02-insoluble fluropolymers may also be used.

Fluorocarbon elastomers (see, e. g, 7 Encyclopedia of Polymer Science & Engineering 257) are a group of amorphous fluoroolefin polymers which can be employed and include, but are not limited to, poly (vinylidene fluoride-co- hexafluoropropylene); poly (vinylidene fluoride-co-hexafluoropropylene-co- tetrafluoroethylene); poly [vinylidene fluoride-co-tetrafluoroethylene-co- perfluoro (methyl vinyl ether)]; poly [tetrafluoroethylene-co-perfluoro (methyl vinyl ether)]; poly (tetrafluoroethylene-co-propylene; and poly (vinylidene fluoride-co- chlorotrifluoroethylene).

The term"fluoroacrylate monomer,"as used herein, refers to esters of acrylic acid (H2C=CHCOOH) or methacrylic acid (H2C=CCH3COOH), where the esterifying group is a fluorinated group such as perfluoroalkyl. A specific group of fluoroacrylate monomers which are useful may be represented by formula (I): H2C=CR'COO (CH2) nR2 (I) wherein: n is preferably from 1 to 3;

Rl is hydrogen or methyl; and R2 is a perfluorinated aliphatic or perfluorinated aromatic group, such as a perfluorinated linear or branched, saturated or unsaturated C, to CIO alkyl, phenyl, or naphthyl.

In a particular embodiment of the invention, R is a C, to C8 perfluoroalkyl or -CH2NR3S02R4, wherein R3 is Cl-C2 alkyl and R4 is Cl to C8 perfluoroalkyl.

The term"perfluorinated,"as used herein, means that all or essentially all hydrogen atoms on an organic group are replaced with fluorine.

Monomers illustrative of Formula (I) above, and their abbreviations as used herein, include the following: 2- (N-ethylperfluorooctanesulfonamido) ethyl acrylate ("EtFOSEA"); 2- (N-ethylperflooctanesulfonamido) ethyl methacrylate ("EtFOSEMA"); 2- (N-methylperfluorooctanesulfonamido) ethyl acrylate ("MeFOSEA"); 2- (N-methylperflooctanesulfonamido) ethyl methacrylate ("MeFOSEMA"); 1,1-Dihydroperfluorooctyl acrylate ("FOA"); 1,1-Dihydroperfluorooctyl methacrylate ("FOMA"); 1,1,2,2-tetrahydro perfluoroalkyl acrylates; 1,1,2,2-tetrahydro perfluoroalkyl methacrylates; 1,1,2,2,3,3-hexahydro perfluoroalkyl acrylates; and 1,1,2,2,3,3-hexahydro perfluoroalkyl methacrylates.

Fluoroplastics may also be used and include those materials which are and are not melt processable such as crystalline or high melting or amorphous fluoroplastics.

Exemplary siloxane-containing segments include alkyl, fluoroalkyl, chloroalkyl siloxanes such as, but not limited to, polydimethyl siloxanes, polydiphenyl siloxanes, and polytrifluoro propyl siloxanes, Copolymers of the above may be employed which includes various types of monomers. Mixtures of any of the above may be used.

Exemplary C02-phobic segments may comprise common lipophilic, oleophilic, and aromatic polymers, as well as oligomers formed from monomers such as ethylene, a-olefins, styrenics, acrylates, methacrylates, ethylene and propylene oxides, isobutylene, vinyl alcohols, acrylic acid, methacrylic acid, and vinyl pyrrolidone. The C02-phobic segment may also comprise molecular units containing various functional groups such as amides; esters; sulfones; sulfonamides; imides;

thiols; alcohols; dienes; diols; acids such as carboxylic, sulfonic, and phosphoric; salts of various acids; ethers; ketones; cyanos; amines; quaternary ammonium salts; and thiozoles.

Surface treatment components which are suitable for the invention may be in the form of, for example, random, block (e. g., di-block, tri-block, or multi-block), blocky (those from step growth polymerization), and star homopolymers, tapered polymers, tapered block copolymers, gradient block copolymers, other copolymers, and co-oligomers. Exemplary surface treatment components include, but are not limited to, poly (l, l-Dihydroperfluorooctyl methacrylate) ("poly FOMA"); (1,1- Dihydroperfluorooctyl methacrylate)-co-methyl methacrylate ("FOMA-co-MMA"); (1, 1-Dihydroperfluorooctyl methacrylate)-block-methyl methacrylate ("FOMA-block- MMA") ; poly-1, 1, 2,2-tetrahydro perfluoroalkyl acrylate (PTA-N or TA-N); poly [1, 1, 2,2-tetrahydro perfluoroalkyl acrylate-co-poly (ethylene glycol) methacrylate] (TA-N/PEG); polydimethylsiloxane-polyethylene glycol (PDMS-PEG); poly (1, 1, 2,2- tetrahydro perfluoroalkyl acrylates); poly (1, 1, 2,2-tetrahydro perfluoroalkyl methacrylates); poly (1, 1-dihydro perfluoroalkyl acrylates); poly (1, 1-dihydro perfluoroalkyl methacrylates); poly (1, 1, 2,2,3,3-hexahydro perfluoroalkyl acrylates); and poly (1,1,2,2,3,3-hexahydro perfluoroalkyl methacrylates). For the purposes of the invention, two or more surface treatment components may be employed in the fluid containing carbon dioxide.

Other surface treatment components may be used which do not have distinct C02 philic and C02 phobic segments, e. g., perfluoropolymers. Exemplary surface treatment components which may be used include, but are not limited to, those described in Rao et al., Textile Finishes and Fluorosurfactants, Organofluorine Chemistry : Principals and Commercial Applications, Banks et al. (eds.) Plenum Press, New York (1994).

The surface treatment component may be applied in various amounts. In the instance where the component is applied as a low level surface treatment, it is preferred to employ the surface treatment component such that the weight of the substrate is less than about 5 percent of surface treatment component, and more preferably less than about 1 weight percent. In the instance where the surface treatment component is applied as a high level surface treatment, it is preferred that

the surface treatment component is employed in amounts such that the weight of the substrate is greater than about 2 weight percent of surface treatment component.

Other additives may be employed with the carbon dioxide, preferably enhancing the physical or chemical properties of the fluid or acting on the substrate.

Such additives may include, but are not limited to, bleaching agents, optical brighteners, bleach activators, corrosion inhibitors, enzymes, builders, co-builders, chelants, sequestering agents, and rheology modifiers. Mixtures of any of the above may be used. As an example, rheology modifiers are those components which may increase the viscosity of the fluid. Exemplary polymers include, for example, perfluoropolyethers, fluoroalkyl polyacrylics, and siloxane oils, including those which may be employed as rheology modifiers. Additionally, other molecules may be employed including Cl-Cl0 alcohols, Cl-Cl0 branched or straight-chained saturated or unsaturated hydrocarbons, ketones, carboxylic acids, N-methyl pyrrolidone, dimethylacetyamide, ethers, fluorocarbon solvents, and chlorofluorocarbon solvents.

For the purposes of the invention, the additives are typically utilized up to their solubility limit during the contacting of the substrate.

In accordance with the invention, by virtue of the application of the surface treatment component, the surface tension is lowered such that contaminants exhibit reduced adherence or absorbency onto the substrate surface during, for example, commercial use. These contaminants are numerous and include, for example, water, inorganic compounds, organic compounds, polymers, particulate matter, and mixtures thereof.

In another aspect, the invention relates to a method of imparting stain resistance or stain release properties to a fabric. The method includes immersing the fabric in a fluid containing carbon dioxide and a surface treatment component. As defined herein, the surface treatment component is entrained in the fluid upon contacting the fabric to lower the surface tension of the fabric. The pressure of the fluid may then be decreased such that the surface treatment component treats the fabric and imparts stain resistance to the fabric. The term"decreasing the pressure of the fluid"refers to lowering the fluid to low pressure (e. g., ambient) conditions such that the surface treatment component is no longer dissolved in the fluid. It should be understood that it is not necessary to drive the surface treatment component onto the

surface. For example, the chemistry of the surface treatment component may be possibly engineered such that it"bites" (e. g., bonds/binds) to the surface.

One desired aspect of a coating for textiles or other substrates is durability throughout the use and exposure of the substrate to various cleaning methods. To this end, it is often desirable to create a chemical bond (a covalent bond) between the active coating material and the substrate. Alternatively, particularly in the case of aqueous emulsion applied textile repellant treatments, the active coating is formulated with other materials that form a resin on the substrate that essentially creates a net around the active repellant fixing it to the surface. For aqueous formulations these resin precursors are often aldehyde or urea-based condensation materials.

Some chemical functionalities that enable chemical bonding between a coating material and a substrate can not be used in water because of hydrolytic instability.

Therefore, the ability to create a chemical bond between a coating material and a substrate can be limited by the use of aqueous emulsions. Since other solvents such as organic hydrocarbons and CFC's are also limiting, it can be difficult to apply repellant coatings to substrates so as to create chemical bonding between the substrate and the active material. Exemplary cases include isocyanate containing cross-linking agents, chlorosilane, alkoxysilane, and silanol containing materials. These chemical functionalities have limited stability when formulated in aqueous media. Other functionalities exemplary of this method that are stabile in aqueous formulations include epoxides, organic acids and esters, and amines.

Thus, coating components employed in the present invention can further comprise a functional group or substituent such as an isocyanate, chlorosilane, alkoxysilane, silanol, epoxide, acid, ester, or amide group. The particular functional group employed to form a covalent bond between the coating component and the substrate will depend, among other things, on the particular coating component and substrates involved. Numerous examples of suitable functional groups are known, including those described in U. S. Patent No. 5,453,540, titled Isocyanate Derivatives Comprising Fluorochemical Oligomers (Describes the use of isocycantes in reaction with nucleophiles such as alcohols, amines, or thiols to generate stain repellent coatings that can be formulated and applied in aqueous emulsions); U. S. Patent No.

4,788,287, titled High Performance Water and Oil Repellant (Discusses the use of various organic isocyanates to produce urethane containing fluorocarbon coatings);

U. S. Patent No. 5,442,011, titled Polymer Fluorocarbon Siloxane, Emulsions and Surface Coatings Thereof (Discusses the hydrolysis of silicon halide or Si-O-alkyl linkages present on hydrocarbon and fluorocarbon radicals in the presence of water and other adjuncts that form a stable emulsion preventing polycondensation prior to the application of the meterials to various substrates); U. S. Patent No. 5,397,597, titled Optical Recording Medium and Method of Manufacturing the Same (Discusses the use of Silicon halide containing fluorocarbon radicals in the surface treatment of inorganic oxides producing polymeric nanolayer surface coatings); U. S. Patent No.

3,639156, titled Siloxane Polymers for Soil-Repellant Soil and Soil-Release Textile Finishes (Describes the use of Fluorocarbon and Hydrocarbon alkylene oxide materials with pendant Si-halide groups or Si-alkoxide groups to generate polymeric coatings for textile substrates) The process of the invention may be used in conjunction with other steps, the selection of which are known in the art. For example, the process may be used simultaneously with or subsequent to a cleaning process, which may remove contaminants from a substrate. Cleaning processes of this type include any technique relating to the application of a fluid or solvent to a substrate, with the fluid or solvent typically containing a surfactant and other cleaning or processing aids if desired.

After the contaminant is removed from the surface, the surface treatment component may be applied to the substrate surface in accordance with the invention. Prior to using a cleaning process, it should be understood that a pre-treatment formulation may be applied to the substrate. Suitable pre-treatment formulations are those which may include solvents, chemical agents, additives, or mixtures thereof. The selection of a pre-treatment formulation often depends on the type of contaminant to be removed or substrate involved.

Operations subsequent to the treating of the substrate with the surface treatment component may also be performed, the operations of which are known by the skilled artisan. For example, the method may also include the step of washing the fabric with a suitable solvent subsequent to the treatment of the fabric with the surface treatment component. Other post-treatment (i. e., conditioning) steps may be carried out. For example, the substrate may be heated to set the surface treatment component.

In an alternative embodiment, the substrate may be exposed to a reduced pressure.

Also, the substrate may be exposed to a chemical modification such as being exposed to acid, base, UV light, and the like.

The process of the invention may be carried out using apparatus and techniques known to those skilled in the art. The process typically begins by providing a substrate in an appropriate pressurized system (e. g., vessel) such as, for example, a batchwise or semi-continuous system. The inert transfer vehicle carrying the_ surface treatment component is also usually added to the vessel at this time. A fluid containing carbon dioxide is then typically added to the vessel and the vessel is heated and pressurized. The surface treatment component and the fluid may be added to the vessel simultaneously, if so desired. Additives (e. g., co-solvents, co- surfactants, and the like) may be added at an appropriate time.

After charging the vessel with the fluid containing carbon dioxide, the fluid contacts the substrate and the surface treatment component treats the substrate.

During this time, the vessel is preferably agitated by known techniques including, for example, mechanical agitation; sonic, gas, or liquid jet agitation; pressure pulsing; or any other suitable mixing technique.

The present invention is particularly advantageous when the treatment component is insoluble (the term"insoluble"including the case where a substantial portion or fraction of the treatment component is insoluble) in the carbon dioxide medium. When the treatment component is soluble, then care must be taken to insure that the treatment component is in fact deposited on the substrate, rather than carried away from the substrate as in a cleaning system. In general, four different techniques for depositing the treatment component, or coating material, onto the substrate, can be employed. In each, the coating is preferably initially provided in the fluid as a stable solution, suspension or dispersion, for subsequent deposition on the substrate, as follows: (A) The coating is dissolved or solubilized in the fluid at a given temperature and pressure, followed by contacting the fluid to the substrate and reduction of fluid pressure. This effects a lowering of the fluid density below a critical level, thus depositing the coating onto the substrate. The system pressure may be lowered by any suitable means, depending upon the particular equipment employed.

(B) The coating is deposited onto a substrate by contacting a fluid containing the coating to the substrate, and then diluting the fluid to a point that destabilizes the coating in the fluid resulting in deposition of the coating onto the substrate.

(C) The coating-containing fluid is contacted to the substrate at sub-ambient temperature and a given pressure, followed by increasing the temperature of the fluid to a point at which the coating destabilizes in the fluid and the coating is deposited onto the substrate.

(D) The coating is provided in the fluid at a sub-ambient temperature in a high pressure vessel, then metered into a second high pressure vessel containing a substrate and the fluid at a temperature sufficiently higher to destabilize the metered fluid and cause the deposition of the coating onto the substrate.

In all of the foregoing, the depositing step is followed by separating the carbon dioxide fluid from the substrate by any suitable means, such as by pumping or venting the fluid from the vessel containing the substrate after the deposition step. As will be appreciated, it is not necessary that all, or even a major portion of, the surface treatment component be deposited onto the substrate, so long as a sufficient quantity is deposited to achieve the desired coating effect on the substrate after it is separated from the fluid.

The foregoing control techniques in paragraphs A through D above may also be used when the treatment component is insoluble in the carbon dioxide medium, to control the partitioning of the treatment component from the inert transfer vehicle to the substrate.

The above delivery and deposition method works best for active coatings that have slight to significant affinity for CO2. In the case where the material has slight affinity for C02, the active coating may adsorb C02 causing the coating to swell.

This process facilitates the transfer of the coating to the substrate by surface to surface contact and/or dispersion of the active coating in a densified gas medium. In the case where the coating material has strong affinity for the densified gas medium, the active coating may become dispersed or dissolved in the medium. Deposition is then accomplished by controlled fluctuations in the density on the C02 medium, as described above.

The invention is advantageous because it does not require organic solvents or water in the delivery of the coating to the substrate. Furthermore, it provides a simple means of control over the level of coating applied to substrates in a batch mode.

This invention also provides ways to control deposition rate of the coating onto the substrate. In a first embodiment, the gas or liquid temperature or density can be adjusted to effect the behavior of the active coating in C02. In general, for certain types of active coatings characterized as amorphous fluoropolymers or siloxane polymers, as the density of the C02 medium increases, polymer swelling also increases. Many of these materials form completely homogenous solutions or suspensions under reasonable conditions. Thus, adjusting C02 density provides control over the rate of swelling and subsequent transfer of the active coating.

In a second control technique, the active materials themselves can be modified to control CO2-philic character. For example, this can be done with acrylic polymer systems by controlling the incorporation of fluorinated groups in the polymer, or by incorporating C02-philic surfactants with the coating sheet. In the case of a high- fluorocarbon acrylic polymer where solubility may be high in a C02 liquid medium, co-monomers can be added to reduce the philic character of the coating. Monomers containing polar functional groups such as-OH,-CN,-COOH,-NR2,-NR3+,-N (R)- S02R and-SO3RX where X is a cation such as H+, NH4+, etc. (wherein R is H or Cl- C4 alkyl, an aryl group, an alkylaryl group, etc.) are exemplary.

3. Cleaning Processes.

As noted above, the coating processes described herein may be conveniently carried out concurrently with a cleaning process, in the same pressure vessel, with the same carbon dioxide medium. The inert transfer vehicle may simply be placed in the vessel along with articles to be cleaned at the beginning of the cleaning cycle, with cleaning of the articles and transfer of the treatment component to the articles being cleaned being carried out concurrently therein.

In the alternative, substrates to be cleaned may be placed in a cleaning vessel and cleaned therein with a carbon dioxide cleaning medium, the cleaning medium removed from the vessel, the vessel opened and the inert transfer vehicle placed therein, the vessel closed and carbon dioxide medium added to carry out a subsequent coating cycle.

The term"clean"as used herein refers to any removal of soil, dirt, grime, or other unwanted material, whether partial or complete. The invention may be used to clean nonpolar stains (i. e., those which are at least partially made by nonpolar organic compounds such as oily soils, sebum and the like), polar stains (i. e., hydrophilic stains such as grape juice, coffee and tea stains), compound hydrophobic stains (i. e., stains from materials such as lipstick and candle wax), and particular soils (i. e., soils containing insoluble solid components such as silicates, carbon black, etc.).

Articles that can be cleaned by the method of the present invention are, in general, garments and fabrics (including woven and non-woven) formed from materials such as cotton, wool, silk, leather, rayon, polyester, acetate, fiberglass, furs, etc., formed into items such as clothing, work gloves, rags, leather goods (e. g., handbags and brief cases), etc.

Metal parts and other substrates as described above can be cleaned and coated concurrently, but (in those cases where necessary) with a nonaqueous carbon dioxide cleaning medium.

The invention may be carried out in any suitable carbon-dioxide based dry cleaning system, such as those described in U. S. Patents Nos. 5,858,022 to Romack et al. or 5,683,473 to Jureller et al., the disclosures of which are incorporated by reference herein in their entirety.

Liquid dry-cleaning compositions useful for carrying out the present invention typically include water. The source of the water is not critical in all applications. The water may be added to the liquid solution before the articles to be cleaned are deposited therein, may be atmospheric water, may be the water carried by the garments, etc.

In one embodiment of the invention, better particulate cleaning may be obtained in the absence of water added to the dry-cleaning composition. There is inherently water present on or in the garments or articles to be cleaned as they are placed in the cleaning vessel. This water serves in part to adhere particulate soil to the articles to be cleaned. As the water is removed from the garments into the cleaning composition during the cleaning process, the removal of water from the article to be cleaned facilitates the removal of particulates from the articles to be cleaned. Thus, decreasing the amount of water originally in the cleaning system can

serve to facilitate the cleaning of particulate soil from the articles to be cleaned by the action of the water inherently carried by the article to be cleaned.

Liquid dry-cleaning compositions useful for carrying out the present invention typically comprise : (a) from zero (0), 0.02,0.05 or 0.1 to 5 or 10 percent (more preferably from. 1 to 4 percent) water; (b) carbon dioxide (to balance; typically at least 30 percent); (c) surfactant (preferably from 0.1 or. 5 percent to 5 or 10 percent total, which may be comprised of one or more different surfactants); and (d) from 0.1 to 50 percent (more preferably 1,2 or 4 percent to 30 percent) of an organic co-solvent.

(e) a sizing agent (discussed below), preferably in an amount of from about 0.1% to 25%, preferably between 1 and 5%.

Percentages herein are expressed as percentages by weight unless otherwise indicated.

The composition is provided in liquid form at ambient, or room, temperature, which will generally be between zero and 50° Centigrade. The composition is held at a pressure that maintains it in liquid form within the specified temperature range. The cleaning step is preferably carried out with the composition at ambient temperature.

The organic co-solvent is, in general, a hydrocarbon co-solvent. Typically the co-solvent is an alkane co-solvent, with CIO to C20 linear, branched, and cyclic alkanes, and mixtures thereof (preferably saturated) currently preferred. The organic co-solvent preferably has a flash point above 140°F, and more preferably has a flash point above 170°F. The organic co-solvent may be a mixture of compounds, such as mixtures of alkanes as given above, or mixtures of one or more alkanes. Additional compounds such as one or more alcohols (e. g., from 0 or 0.1 to 5% of a Cl to C15 alcohol (including diols, triols, etc.)) different from the organic co-solvent may be included with the organic co-solvent.

Examples of suitable co-solvents include, but are not limited to, aliphatic and aromatic hydrocarbons, and esters and ethers thereof, particularly mono and di-esters and ethers (e. g., EXXON ISOPAR L, ISOPAR M, ISOPAR V, EXXON EXXSOL, EXXON DF 2000, CONDEA VISTA LPA-170N, CONDEA VISTA LPA-210, cyclohexanone, and dimethyl succinate), alkyl and dialkyl carbonates (e. g., dimethyl carbonate, dibutyl carbonate, di-t-butyl dicarbonate, ethylene carbonate, and

propylene carbonate), alkylene and polyalkylene glycols, and ethers and esters thereof (e. g., ethylene glycol-n-butyl ether, diethylene glycol-n-butyl ethers, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and dipropylene glycol methyl ether acetate), lactones (e. g., (gamma) butyrolactone, (epsilon) caprolactone, and (delta) dodecanolactone), alcohols and diols (e. g., 2- propanol, 2-methyl-2-propanol, 2-methoxy-2-propanol, 1-octanol, 2-ethyl hexanol, cyclopentanol, 1,3-propanediol, 2,3-butanediol, 2-methyl-2,4-pentanediol) and polydimethylsiloxanes (e. g., decamethyltetrasiloxane, decamethylpentasiloxane, and hexamethyldisloxane), etc.

Any surfactant can be used to carry out the present invention, including both surfactants that contain a C02-philic group (such as described in PCT Application W096/27704) linked to a C02-phobic group (e. g., a lipophilic group) and (more preferably) surfactants that do not contain a C02-philic group (i. e., surfactants that comprise a hydrophilic group linked to a hydrophobic (typically lipophilic) group). A single surfactant may be used, or a combination of surfactants may be used.

Numerous examples are set forth in U. S. Patents Nos. 5,858,022 to Romack et al., U. S. Patent No. 5,683,473 to Jureller et al, and McCutcheon's Volume 1: Emulsifiers & Detergents (1995 North American Edition) (MC Publishing Co., 175 Rock Road, Glen Rock, NJ 07452). Thus the present invention may be carried out using conventional surfactants, including but not limited to the anionic or nonionic alkylbenzene sulfonates, ethoxylated alkylphenols and ethoxylated fatty alcohols described in Schollmeyer German Patent Application DE 39 04514 Al, that are not soluble in liquid carbon dioxide and which could not be utilized in the invention described in U. S. Patent No. 5,683,473 to Jureller et al. or U. S. Patent No. 5,683,977 to Jureller et al.

As will be apparent to those skilled in the art, numerous additional ingredients can be included in the dry-cleaning composition, including detergents, bleaches, whiteners, softeners, sizing, starches, enzymes, hydrogen peroxide or a source of hydrogen peroxide, fragrances, etc.

In practice, in a preferred embodiment of the invention, an article to be cleaned and a liquid dry cleaning composition as given above are combined in a closed drum. The liquid dry cleaning composition is preferably provided in an amount so that the closed drum contains both a liquid phase and a vapor phase (that

is, so that the drum is not completely filled with the article and the liquid composition). The article is then agitated in the drum, preferably so that the article contacts both the liquid dry cleaning composition and the vapor phase, with the agitation carried out for a time sufficient to clean the fabric. The cleaned article is then removed from the drum. The article may optionally be rinsed (for example, by removing the composition from the drum, adding a rinse solution such as liquid C02 (with or without additional ingredients such as water, co-solvent, etc.) to the drum, agitating the article in the rinse solution, removing the rinse solution, and repeating as desired), after the agitating step and before it is removed from the drum. The dry cleaning compositions and the rinse solutions may be removed by any suitable means, including both draining and venting.

Any suitable cleaning apparatus may be employed, including both horizontal drum and vertical drum apparatus. When the drum is a horizontal drum, the agitating step is carried out by simply rotating the drum. When the drum is a vertical drum it typically has an agitator positioned therein, and the agitating step is carried out by moving (e. g., rotating or oscillating) the agitator within the drum. A vapor phase may be provided by imparting sufficient shear forces within the drum to produce cavitation in the liquid dry-cleaning composition. An apparatus that may be used to carry out the technique is set forth in U. S. Patent No. 6,049,931 to McClain et al. Finally, in an alternate embodiment of the invention, agitation may be imparted by means of jet agitation as described in U. S. Patent No. 5,467,492 to Chao et al., the disclosure of which is incorporated herein by reference. As noted above, the liquid dry cleaning composition is preferably an ambient temperature composition, and the agitating step is preferably carried out at ambient temperature, without the need for associating a heating element with the cleaning apparatus.

Particularly preferred apparatus for carrying out the present invention, in which sizing can be added in like manner to detergent, is disclosed in commonly owned, copending patent application of James P. DeYoung, Timothy J. Romack, and James B. McClain, Serial No. 09/312,556, titled Detergent Injection Systems for Carbon Dioxide Cleaning Apparatus, filed May 14,1999, the disclosure of which is incorporated by reference herein in its entirety.

The present invention is explained in greater detail in the following non- limiting Examples.

Example 1 Transfer of Fluoroacrylate copolymer to Wool Suites Approximately 75 grams of a fluoroacrylate copolymer consisting of about 70% by weight fluorocarbon containing repeat units is applied to 3 woven polyester delivery sheets approximately 12-inches square. The sheets are added to a commercial liquid C02 dry cleaning machine (the MIC02TM Model G200 cleaning apparatus, available from Micell, Inc. 7516 Precision Drive, Raleigh, NC 27613 USA) along with 8 woolen suits that total approximately 10 pounds. A cycle is initiated that exposes the garments to liquid carbon dioxide and mechanical action, generated with a tumbling basket. During the process the fluoroacrylic copolymer becomes swollen and slightly dispersed in the fluid medium. The polymer is transferred first from the polyester delivery sheets to garments that come in direct contact with the sheets, then from garment to garment generating an even distribution of polymer on all garments. After approximately 10 minutes of tumbling the fluid is drained and the C02 vapor is recovered. The garments are removed from the machine and finished using standard pressing and steaming processes. The treated garments now show consistent repellency to aqueous and oily soils. AATCC test methods 22- 1996,'water spray test'and 118-1992,'oil repellency: hydrocarbon resistance test' are used to determine repellency. All woolen garments receive no lower than a 90 (ISO 4) rating on the water spray test and a 6 rating on the oil repellency test. Before treatment the wool garments showed repellency ratings of 50 (ISO 1) and 0 on the spray test and oil repellency test respectively.

AATCC 22-1996 100 (ISO 5)-No sticking or wetting of upper surface 90 (ISO 4)-Slight randon sticking on upper surface, no wetting 80 (ISO 3)-Wetting of upper surface at spray points 70 (IS02)-Partial wetting of whole upper surface 50 (ISO 1)-Complete wetting of whole upper surface 0-Complete wetting of upper and lower surfaces

AATCC 118-1992 0-no repellency (fails Kaydol) 1-Kaydol 2-65: 35 Kaydol: n-heexadecane by volume 3-n-hexandecane 4-n-tetradecane 5-n-dodecane 6-n-decane 7-n-octane 8-n-heptane Example 2 Transfer of Fluoroacrylate Copolymer to Silk Garments Approximately 150 grams of a fluoroacrylate copolymer consisting of about 70% by weight fluorocarbon containing repeat units is applied to 6 woven polyester delivery sheets approximately 12-inches square. The sheets are added to a commercial liquid C02 dry cleaning machine along with 20 pounds of silk garments including blouses, skirts, sweaters, and suits. A cycle is initiated that exposes the garments to liquid carbon dioxide and mechanical action, best generated with a tumbling basket. After the cycle is completed the garments are removed from the machine and finished with standard pressing and steaming the garments are tested for water and oil repellency and show no lower than 100 (ISO 5) on the water spray test, and 6 on the oil repellency tests. Prior to processing the garments tested showed no water or oil repellency, 0-water spray test and 0-hydrocarbon resistance test.

Example 3 Transfer of Fluoroacrvlate Copolymer to Cotton and Cotton/Polvester Garments Approximately 150 grams of a fluoroacrylate copolymer consisting of about 70% by weight fluorocarbon containing repeat units is applied to 6 woven polyester delivery sheets approximately 12-inches square. The sheets are added to a commercial liquid C02 dry cleaning machine along with 20 pounds of cotton and cotton polyester

blended garments. A cycle is initiated that exposes the garments to liquid carbon dioxide and mechanical action, best generated with a tumbling basket. After the cycle is completed the garments are removed from the machine and finished with standard pressing and steaming the garments are tested for water and oil repellency and show no lower than a 80 (ISO 3) on the water spray test and 5 on the oil repellency test.

Prior to processing the garments tested showed no water or oil repellency, 0-water spray test and 0-hydrocarbon resistance test.

Example 4 Transfer of Fluoroacrvlate Copolymer to Nylon and Nylon Blend Outerware Nylon, nylon/polyester, polyester/cotton, and nylon/cotton blended outer wear such as jackets, sleeping bags, and rain coats were treated as in the above examples.

After the process all treated substrates showed dramatically improved repellency to water based and oily soils.

Example 5 Transfer of Fluoroacrylate Copolymer to A Standard Dry-Cleaninv Load A mixture of garments composing a standard dry cleaning load including synthetic and natural fabrics is cleaned and coated as in the above examples. After the cleaning and coating process all garments show substantially improved repellency properties.

Example 6 Cleaning of Previously Treated Fabrics A test is run where 3 silk, 3 wool, 3 nylon, and 3 cotton swathes are coated in a process like those described above with a fluoroacrylic containing copolymer.

These swatches are then soiled along with 3 silk, 3 wool, 3 nylon, and 3 cotton swatches that have not been treated. All swatches are soiled with carbon soot according to AATCC Evaluation procedure 2,"Gray Scale for Staining". Both set, treated and not treated, were heavily soiled to a staining grade of'1-2'on the gray scale. Both sets of swatches were then cleaned using a liquid C02 dry cleaning process. After the cleaning process all swatches were evaluated based on the same AATCC evaluation procedure. For the non-coated swatches the average staining grade after cleaning was a'3'. For the coated set the average staining grade after cleaning was a'4-5'. This demonstrates the superior soil release qualities provided with the C02 coating process.

Stain Grade Color Difference (CIELAB Units) 5 0 4-5 2.2 4 4.3 3-4 6.0 3 8.5 2-3 12.0 2 16.9

1-2 24.0 1 34. 1 Example 7 Coating of Garments with COr Gas Approximately 150 grams of a fluoroacrylate copolymer consisting of about 70% by weight fluorocarbon containing repeat units is applied to 6 woven polyester delivery sheets approximately 12-inches square. Approximately, 20 pounds of mixed garments are added to a C02 based dry cleaning machine along with the delivery sheets. C02 gas is the added to the cleaning chamber until a pressure of 700 psig at a temperature of 78°F is reached. The garments and delivery sheets are then tumbled in the cleaning chamber. The dense C02 gas causes the copolymer on the delivery sheet to swell. The mechanical action provided by the tumbling results in the even distribution of the polymer on the garments. After the C02 vapor is recovered the garments are removed and tested for repellency. All garments demonstrate substantially improved oil and water repellency.

The foregoing is illustrative of the present invention, and is not to be construed as limiting thereof. The invention is defined by the following claims, with equivalents of the claims to be included therein.