WO2014059415A1

WO2014059415A1 - Surface modified nanoparticle aqueous dispersions for treating cellulose fiber products

Info

Publication number: WO2014059415A1
Application number: PCT/US2013/064845
Authority: WO
Inventors: Isaac K. Iverson
Original assignee: INVISTA TECHNOLOGIES Sarl; Invista Technologies SARL USA
Current assignee: INVISTA TECHNOLOGIES Sarl; Invista Technologies SARL USA
Priority date: 2012-10-12
Filing date: 2013-10-14
Publication date: 2014-04-17
Anticipated expiration: 2015-04-12

Description

SURFACE MODIFIED NANOPARTICLE AQUEOUS DISPERSIONS FOR TREATING CELLULOSE FIBER PRODUCTS

FIELD OF THE INVENTION

[0001] The invention relates to paper treatment aqueous dispersions comprising surface modified nanoparticles that can be applied to or in paper, paperboard products and cellulose fiber products. Paper, paperboard and cellulose fiber articles that have been modified by these aqueous dispersions, which result in having improved oil and grease resistance and penetration properties, are also disclosed.

BACKGROUND OF THE INVENTION

[0002] Waxes and fluorochemicals have been applied topically, such as on the dry end of the paper process in a size press or coater, to cellulose fiber articles, such as paper and paperboard, in the past to provide oil and grease resistance, but have suffered from high cost accompanying the conversion from C8 telomer fluorochemicals to C6 telomer and perfluoropolyether (PFPE) fluorochemcials. Fluorochemicals have also been applied on the wet end of a process for oil and grease holdout throughout the paper, paperboard and cellulose article thickness. These type applications suffer from higher cost as well with this conversion. These newer fluorochemicals are thought to have lower risk of degradation into products harmful to the environment but are also less efficient. SUMMARY OF THE INVENTION

[0003] There is a desire to reduce the overall usage of fluorochemicals for environmental and cost reasons. Thus, it can be understood that oil and grease resistant compositions that reduce the amount of fluorochemicals used and the total system cost, but still retain good oil and grease resistance, are in demand.

[0004] Alsoit is desirable to further extend the effectiveness of fluorochemicals and to produce a paper or paperboard or cellulose fiber product with improved stiffness, print clarity, adhesion, release and friction characteristics while still retaining desirable oil and grease repellency and holdout attributes.

[0005] In accordance with one aspect of the disclosed composition, it has now been found that certain novel compositions can be produced comprising inorganic nanoparticles which have been surface modified via bi-phasic reaction with liquid fluoroalkylsilane (FAS) reagents in aqueous media. Aqueous dispersions of the disclosed composition are monophasic, optically transparent and stable without significant aggregation or precipitation and with little or no additional solvents or surfactants. The composition comprises: an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles, wherein the nanoparticles comprise at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is:

(F(CF₂)nCH₂CI-l₂)mSi(0-)p, where n is 2, 3 or 4, p is 1 , 2 or 3, and m is (4-p). Also, the composition can further comprise an additional component moiety bonded to the surface of the nanoparticle having the formula: [H(CH₂)M]n-Si-(0-)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, and n is 4-p. The additional component can be methylsilyl. Further, articles comprising the fluoroalkylsilyl surface modified nanoparticle are disclosed. The article can include paper, paperboard or cellulose fiber articles. The article exhibits improved resistance to both grease and oil. Treated paper and paperboard and cellulose fiber products also show improved stiffness, print clarity, adhesion, release and friction characteristics over prior fluorochemical or silicone treated papers and paperboard and cellulose fiber products.

[0006] In yet another aspect, a modified substrate is disclosed. The modified substrate comprises a fluoroalkylsilyl surface modified nanoparticle on at least one surface of the substrate, wherein the nanoparticle comprises at least one member selected from the group consisting of titania, zirconia, layered

magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is (F(CF₂)nCH2CH2)mSi(0-)_p, where n is 2, 3 or 4, where p is 1 , 2 or 3, and where m is (4-p). The substrate can further comprise an additional component moiety bonded to the surface of the

nanoparticle having the formula: [H(CH₂)M]n-Si-(0-)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, and n is 4-p. When the substrate comprises the additional component moiety, the nanoparticle can be selected from the group consisting of silica, zirconia, titania, layered magnesium silicate,

aluminosilicate, natural clay, synthetic clay and mixtures thereof. The substrate can be paper, paperboard, or cellulose fiber. The substrates and articles made therefrom exhibit improved resistance to grease and oil.

[0007] In a further aspect, a process of making an oil and grease resistant cellulose fiber substrate is disclosed. The process comprises (i) applying an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles to the substrate, wherein said aqueous dispersion comprises at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures; and wherein said fluoroalkylsilyl is: (F(CF2)nCH₂CH2)mSi(0-)p, where n is 2, 3 or 4, where p is

1 , 2 or 3, and where m is (4-p); and (ii) drying the substrate. The aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles can also comprise an additional component moiety bonded to the surface of the nanoparticle having the formula: [H(CH₂)_M]n-Si-(0-)p, where M is an integer between 1 and 12, p is 1 ,

2, or 3, and n is 4-p. The fluoroalkylsilyl surface modified nanoparticles can be applied either on one or both surfaces or on the wet end so that it is in the interior of the substrate or a combination of these.

Definitions

[0008] Nanoparticle is defined as a multidimensional particle in which one of its dimensions is less than 100 nm in length.

[0009] FAS means the class of fluoroalkylsilane reagents used to impart fluorinated organic functionality including, but not limited to, the inorganic particles of this invention. FAS reagents specifically include, but are not limited to structures of the formula: (F(CF₂)nCH₂CH₂)mSi(OR)p where n is 2, 3 or 4; where p is at least 1 ; where m is at least 1 ; where m + p = 4; and where R is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or -C(0)CH₃. Although less preferred for the process of making here disclosed, other structures having perflourinated alkyl terminal functionality should also be understood as being contemplated by this disclosure. FAS reagents can also include structures of the formula:

(F(CF₂)nCH₂CH₂)_mSi(X)p where n is 2, 3 or 4; where p is at least 1 ; where m is at least 1 ; where m + p = 4; and where X is a halogen such as chlorine, bromine or iodine. FAS reagents can also include structures of the formula:

(F(CF₂)_nCH₂CH₂)mSiR' _p (X) where n> 2, and m + p = 3, R' is methyl or ethyl bonded to the silicon atom and where X is a halogen such as chlorine, bromine or iodine that is bonded to the silicon atom.

[00010] Clay particles can refer to particles substantially comprising minerals of the following geological classes: smectites, kaolins, illites, chlorites, and attapulgites. These classes include specific clays such as montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, vermiculite, kaolinite, dickite, antigorite, anauxite, indellite, chrysotile, bravaisite, suscovite, paragonite, biotite, corrensite, penninite, donbassite, sudoite, pennine, sepiolite, and polygorskyte. The clay minerals of the invention may be either synthetic or natural and are exfoliated to be capable of forming aqueous micro dispersions. An example of one embodiment of the present invention uses synthetic hectorite clay nanoparticles sold by the trade name Laponite® from Rockwood Additives Ltd. Preferred embodiments of the present invention use Laponite RDS®, Laponite JS®, and Laponite RD®.

[00011] An aqueous dispersion means a colloidal dispersion, which is a system of finely divided particles of small size, such as nanoparticles, which are uniformly dispersed in a manner such that they are not easily filtered or gravitationally separated.

[00012] An aqueous micro dispersion is defined as a dispersion of particles predominately having at least one dimension that is less than about 100 nm in extent.

[00013] A non-solubilized aqueous micro dispersion is an aqueous micro dispersion that is stable for extended periods of time (two or more months) without water compatible surfactants.

[00014] OWPF is weight per weight of paper fiber.

[00015] WPU (wet pick up) is the fraction of the weight of paper added in liquid form in treating a cellulous fibrous substrate (w/w).

[00016] Layered structure is where overlap of nanoparticles is observed, and where flat layers or sheets are observed rather than round, globular or clumped aggregate structures.

DETAILED DESCRIPTION OF THE INVENTION

[00017] A composition for treating paper and paperboard and cellulose fiber substrates to impart hydrophobic and oleophobic behavior, including oil and grease resistance is disclosed. The composition comprises a fluoroalkylated nanoparticle modified at the surface by reaction in water with a specific fluoroalkylsilane (FAS) reagent that is suited to conducting such a reaction efficiently in aqueous media. More specifically, the composition can comprise an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticle, wherein the nanoparticle comprises at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is: (F(CF2)nCH₂CH2)_mSi(0-)p, where n is 2, 3 or 4, p is 1 , 2 or 3, and m is (4-p), including: (F(CF₂)nCH2CH2)_mSi(0-)p, where n can be 4, p can be 3 when m is 1. The nanoparticle can comprise silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, including a synthetic hectorite clay. A mixture can be synthetic hectorite clay and silica. The fluoroalkylsilyl moieties can be covalently bonded to the nanoparticle surface. This composition is formed by reaction of a water immiscible specific

fluoroalkylsilane reagent emulsified in water with preformed inorganic

nanoparticles dispersed in the aquaeous phase such that the fluoroalkylsilane reagent is covalently bonded to the nanoparticles predominantly at the particle surface as described in process above. This dispersion composition can then be applied to a substrate. The composition can optionally comprise a component moiety bonded to the surface of the nanoparticle having the formula: [H(CH₂)_M]n- Si-(0-)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, and n is 4-p. The optional component can be methylsilyl. [00018] The nanoparticle can comprise silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic hectorite clay, for example a mixture can be synthetic hectorite clay and silica. The fluoroalkylsilyl molecules can be covaiently bonded to the nanoparticle surface.

[00019] The fluoroalkylsilyl surface modified nanoparticles can be present at a concentration in the range of from about 0.01% to about 50% by weight of the total composition of the dispersion, for example in the range of from about 1 % to about 40% by weight, including about 1 % to about 8% by weight of the total composition. Stable aqueous dispersions of fluoroalkylsilyl surface modified nanoparticles wherein the nanoparticles are synthetic hectorite clay can be formed at a concentration in the range of from about 0.01 % to about 12% by weight of the total composition, including about 1 % to about 8% by weight of the total composition. Depending on the final use and the substrate to be treated, the dispersion of the present invention can be diluted for more efficient application or to control the level of moisture imparted in the treatment process. Again, depending on the nature of the substrate that is to be treated, its intended use and the process of manufacture, other chemistries as may be known in the art can be combined with the aqueous dispersion of the instant invention at suitable concentration ranges.

[00020] The composition can further comprise a fluorinated resin emulsion, an alkylated inorganic nanoparticle having no fluorine and/or at least one member selected from the group consisting of a wetting agent, fluorochemical resin, surfactant, silicones, optical brighteners, antibacterial components, anti-oxidant stabilizers, coloring agents, light stabilizers, UV absorbers, wetting agents, starch, polyvinyl alcohol, retention aids and wet strength aids and mixtures thereof.

[00021] Optionally, the composition can be blended with additional wetting agents, anti-soil agents, fluorochemical resins, surfactants or mixtures thereof, as known in the art, in order to simplify the manufacturing process at hand. While the aqueous dispersion is generally compatible, it is naturally desirable to avoid the addition of materials that would coalesce or precipitate the nanoparticles or otherwise diminish efficacy or utility.

[00022] The disclosed dispersions are surprisingly stable and exist indefinitely at moderately high concentrations as transparent aqueous mixtures in spite of the intrinsically hydrophobic nature of fluoroalkylated surfaces.

[00023] The compositions can be useful to treat soft paper, paperboard and cellulose fiber articles, either applied to one or both sides on the dry end such as a size press or coater, or to the wet end such that the chemistry is throughout the article, or in both the dry and wet ends of the papermaking process, to impart several valuable attributes. Paper, paperboard and cellulose fiber articles treated with the various dispersions described have also been shown to have increased oil and grease repellency.

[00024] A process for making a fluoroaklysilyl surface modified nanoparticle is also disclosed. The process comprises: (i) creating an aqueous dispersion of at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof; (ii) adding a water immiscible fluoroalkylsilane reagent to the aqueous dispersion to form a heterogeneous mixture where the fluoroalkylsilane reagent is: (F(CF₂)_nCH₂CH₂)mSi(0-R)_p, where n is 2, 3 or 4, p is 1 , 2 or 3, m is (4- p), and R is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and -C(0)CH₃; and (iii) mixing the heterogeneous mixture until it becomes a homogeneous aqueous dispersion of fluoroaklysilane surface modified nanoparticles. The fluoroalkylsilane is: (F(CF₂)_nCH₂CH₂)_mSi(0- R)_p, where n can be 4, p can be 3 when m is 1 and R can be selected from the group consisting of methyl and ethyl. The nanoparticle can comprise silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic hectorite clay, for example a mixture can be synthetic hectorite clay and silica. The

fluoroalkylsilane molecules can be covalently bonded to the nanoparticle surface, creating a fluoroalkylsilyl moiety. The fluoroalkylsilyl surface modified

nanoparticles can be formed at a concentration in the range of from about 0.01% to about 50% by weight of the total composition, for example from about 1 % to about 40% by weight of the total composition or from about 1% to about 8% by weight of the total composition. The process can further comprise adding a fluorinated resin emulsion prior applying the aqueous dispersion. Additionally, the process can further comprise adding an alkylated inorganic nanoparticle having no fluorine prior applying the aqueous dispersion. Moreover, the process can further comprise adding at least one member selected from the group consisting of a wetting agent, anti-soil agent, fluorochemical resin, surfactant and mixtures thereof prior applying the aqueous dispersion. Optionally, a compound having the formula: [H(CH₂)_M]n-Si-(X)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, n is 4-p, and where X is selected from the group consisting of methoxy, ethoxy, propoxy, butoxy, acetoxy, and chloride leaving groups, can be added prior to the addition of the fluoroalkylsilane. A recirculation pump and static mixer may be used in the disclosed process to further increase the interfacial contact between the immiscible fluoroalkylsilane and nanoparticles.

[00025] The fluoroalkylsilane reactant used in step (ii) of the process to create the fluoroalkylsilyl surface modified nanoparticles is: (F(CF₂)_nCH₂CH₂)mSi(O-R)p, where n is 2, 3 or 4; where p is 1 , 2 or 3; where (m + p) = 4; and where R is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and -C(O)CH₃. The fluoroalkyl moiety of the alkylsilane reactant can be a perfluoroalkane of two to four carbons in length, for example a four carbon nanofluoroalkane (n is 4), where m is 1 and p is 3, and where R is either methyl or ethyl. Extended perfluoroalkane chains can be used to achieve greater degrees of hydrophobicity in treated substrates. However, FAS reagents having perfluoroalkane chains longer than four carbon atoms (n value greater than 4) are not suitable for making the disclosed aqueous dispersions and that the addition of undesirable levels of solvents or surfactants would be required to stabilize both reactants and product dispersions in the disclosed process.

[00026] In one aspect of the disclosed process, 1 ,1 ,2,2-tetrahydro- nonafluorohexyl trimethoxysilane can be added slowly with stirring to a 25%(w/w) aqueous dispersion of colloidal silica (20 nm particles) with pH 9 to form a liquid- liquid emulsion of cloudy appearance. Optionally, a recirculation pump and static mixer can be used with or without the mechanical stirrer to increase interfacial contact of the FAS with the colloidal silica. The FAS minor liquid phase is consumed with stirring over a period of hours gradually reducing to a single liquid phase dispersion that remains stable in the absence of stirring. The resulting stable aqueous dispersion contains dispersed silica nanoparticles that have a covalently bonded hydrophobic layer on the particle surface.

[00027] In another aspect of the disclosed process, 1 ,1 ,2,2-tetrahydro- nonafluorohexyl trimethoxysilane can be added slowly to a 5% (w/w) aqueous dispersion of synthetic hectorite clay nanoparticles sold by the trade name Laponite® RDS from Rockwood Additives Ltd. The aqueous hectorite clay dispersion is natively above pH 9 and slow addition of the FAS with high stir rate forms a liquid-liquid emulsion of cloudy appearance. Optionally, a recirculation pump and static mixer can be used with or without the mechanical stirrer to increase interfacial contact of the FAS with the hectorite clay. The FAS minor liquid phase is consumed with stirring over a period of hours gradually reducing to a single liquid phase dispersion that remains stable in the absence of stirring. Optionally, the dispersion of the present invention can be blended with

fluorinated resin emulsions or with dispersions of alkylated inorganic

nanoparticles having no fluorine. For example, the dispersions of the fluoroalkyl modified clay nanoparticles described above can be blended with an aqueous dispersion of colloidal silica nanoparticles which have been surface modified with methyltrimethyoxysilane (MTMS) so that the resulting aqueous dispersion comprises two distinctly different nanoparticles.

[00028] Also disclosed are substrates and processes for making the same using the fluoroalkylsilyl surface modified nanoparticles. The substrate comprises: a fluoroalkylsilyl surface modified nanoparticle on at least one surface, wherein the nanoparticle comprises at least one member selected from the group consisting of: titania, zirconia, layered magnesium silicate,

aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is: (F(CF2)_nCH₂CH2)mSi(0-)p, where n is 2, 3 or 4, p is 1 , 2 or 3, and m is (4-p). The nanoparticle of the present invention can comprise titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic hectorite clay, for example a mixture can be synthetic hectorite clay and zirconia. The fluoroalkylsilyl can also include: (F(CF₂)nCH2CH2)mSi(0-)p, where n can be 4, p can be 3 when m is 1. The fluoroalkylsilyl can be covalently bonded to the nanoparticle surface. The substrate can have pores having an average diameter in the range of from about 100 to about 100,000 nanometers. The fluoroalkylsilane surface modified nanoparticle can form at least one layered structure on the substrate, wherein the layered structure has a thickness of about 10,000 nanometers or less, and a width and length of about 100,000 nanometers or more. The substrate can optionally comprise a component moiety bonded to the surface of the

nanoparticle having the formula: [H(CH₂)_M]n-Si-(0-)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, and n is 4-p. When the nanoparticle comprises the optional component moiety, the nanoparticle can include silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof.

[00029] The substrate can be a paper, paperboard or cellulose fiber articles wherein the composition imparts the same level of oil and grease repeilency with lower levels of elemental fluorine used compared with coatings of traditional fluorochemical resin emulsions. Substrates coated or containing internally, or a combination of both with the present invention have been found to exhibit superior oil and grease repeilency with less elemental fluorine than found in coatings of traditional fluorochemical resins.

[00030] The process of making the substrate with the aqueous dispersion of nanoparticles comprises applying the aqueous dispersion of fluroralkylsilyl surface modified nanoparticles to a substrate; and drying the substrate.

[00031] Also disclosed are articles made from substrates comprising the fluoroalkylsilyl surface modified nanoparticles. More specifically, an article comprises a composition comprising: a fluoroalkylsilyl surface modified nanoparticle, wherein the nanoparticle comprises at least one member selected from the group consisting of titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is: (F(CF₂)nCH₂CH2)mSi(0-)p, where n is 2, 3 or 4, p is 1 , 2 or 3, and m is (4-p), and optionally a component moiety bonded to the surface of the nanoparticle having the formula: [H(CH₂)_M]n-Si-(0-)_p, where M is an integer between 1 and 12, p is 1 , 2, or 3, and n is 4-p. Articles can include but are not limited to paper, paperboard and cellulose fiber articles. When the article is paper, paperboard or cellulose fiber articles , or includes the optional component moiety, the nanoparticles can also include silica. For paper or paperboard or cellulose fiber articles, the total concentration of fluorine is in a range of from about 10 ppm to about 500 ppm w/w of exposed substrate, including about 50 ppm to about 300 ppm w/w of exposed substrate. For paper, paperboard, or cellulose fiber articles, the substrate retains the fluoroalkylsilyl surface modified nanoparticle at a weight in the range of from about 0.01 % to about 2.0% by weight of the exposed substrate, including from about 0.1 % to about 1.0% by weight of the exposed substrate; or wherein the substrate retains elemental fluorine in the range of from about 0.0001 % to about 0.10% by weight of the exposed substrate, including from about 0.0001 % to about 0.010% by weight of the exposed substrate. For paper, paperboard, or cellulose fiber articles, the substrate retains fluoroalkylsilyl surface modified nanoparticles in the range of from about 0.01 to about 3 grams per square meter of surface area, including from about 0.1 to about 2 grams per square meter of surface area.

Test Methods

[00032] TTAPPI Sizing Test Methods including but not limited toT454 om-89 Turpentine Test for Grease Resistance of Paper, T507 cm-85 Grease resistance of Flexible Packaging Materials, T441 om-90 Water Absorptiveness of Sized (Non-Bibulous) Paper and Paperboard (Cobb test), UM 557 Repellency of Paper and Board to Grease, Oil and Waxes (Kit test), etc. Examples

[00033] Aqueous Micro Dispersion Preparatory Example 1: To a 250 ml_ round bottom flask was added 59.6 grams of 40% anionic colloidal silica (LUDOX® AS-40, from W.R. Grace) and 40.0 grams of de-ionized water with stirring to form a liquid-liquid emulsion of cloudy appearance. The pH of the resulting aqueous colloidal silica dispersion was between 9 and 10. The dispersion was stirred at 32°C under nitrogen and 1.798 ml_ of 1 ,1 ,2,2- tetrahydro-nonafluorohexyl trimethoxysilane (density = 1.335 g/mL, from Gelest) was added over 225 minutes via syringe and syringe pump. After stirring for 20 hrs at 32°C the mixture was observed to be a single liquid phase and was then allowed to cool to RT and a clear aqueous dispersion was produced. The product was filtered through 1 micron glass-fiber filter paper and the final concentration of the dispersion was essentially unchanged as only a very slight film of precipitate was observed on the filtration media.

[00034] Aqueous Micro Dispersion Preparatory Example 2: To a 500 ml_ round bottom flask was added 190 grams of de-ionized water and the

temperature was brought to 38 deg C with rapid stirring. 10.00 gram of

Laponite® RDS clay powder (from Rockwood Additives) was added slowly over 15 minutes in small increments and then stirred for 1 hr at 38°C, creating a clear aqueous dispersion with a pH of between 9 and 10. The temperature of the Laponite® RDS dispersion was brought to 32°C while stirring under nitrogen and 2.757 ml_ of 1 ,1 ,2,2-tetrahydro-nonafluorohexyl trimethoxysilane (density = 1.335 g/mL, from Gelest) was added over 336 minutes via syringe and syringe pump with stirring to form a liquid-liquid emulsion of cloudy appearance. After addition, the dispersion was stirred for 35 hrs at 32°C and was observed to be a single liquid phase. It was then allowed to cool to RT and a clear aqueous dispersion was produced. The product was filtered through 1 micron glass-fiber filter paper and the final concentration of the dispersion was essentially unchanged as only a very slight film of precipitate was observed on the filtration media.

[00035] Aqueous Micro Dispersion Preparatory Example 3: To a 3000 ml_ round bottom flask with 3 necks and equipped with overhead stirrer was added 596 grams of 40% anionic colloidal silica (LUDOX® AS-40, from W.R. Grace) and 396 grams of de-ionized water at room temperature with stirring. The pH of the resulting aqueous dispersion was between 9 and 10. The dispersion was brought to 30°C and stirred under nitrogen, and 13.20 ml_ of methyl

trimethoxysilane (density = 0.955 g/mL, from Aldrich) was subsequently added over 127 minutes via syringe and syringe pump. After stirring for 1 hr at 30°C it was allowed to cool to RT and a clear aqueous dispersion was produced. The product was filtered through 1 micron glass-fiber filter paper and the final concentration of the dispersion was essentially unchanged at approximately 25% w/w solids, as only a very slight film of precipitate was observed on the filtration media. [00036] Aqueous Micro Dispersion Preparatory Example 4: To a small beaker was added 59.6 grams of 40% anionic colloidal silica (LUDOX® AS-40 from W.R. Grace) and 40.4 grams of de-ionized water at room temperature with stirring, to produce a solution with 25% solids. 0.744 ml of

methyltrimethylsiloxane (MTMS) was dripped into the stirring beaker using a syringe pump set to deliver 0.01 ml/min. Approximately 135 minutes after addition of MTMS (i.e. about 1 hour after it ended), the FAS addition started. 0.360 ml of FAS was added at 0.01 ml/min, using a 1 ml glass Hamilton gas-tight syringe. The beaker was covered in parafilm and stirred at 1200 rpm for approximately 48 hours. During the 48 hour stirring, a sludge formed that trapped the stir bar. No oil droplets were visible on the top of the liquid surface. The product was filtered through GFA paper, whereby 97 grams of product was collected.

[00037] Aqueous Micro Dispersion Preparatory Example 5: In a 15 liter reactor, 2380 grams of deionized water and 3580 grams of 40% anionic colloidal silica (LUDOX® AS-40 from W.R. Grace) was added to produce a solution with 25% solids. In addition to mechanical stirring, the reactor was fitted with a recirculating pump and tubing drawing the solution through the pump and then through a static mixer tube and then back to the reactor. 24.5 grams of MTMS was added dropwise to the solution over 5 minutes. The solution was allowed to mix for 1 hour. 66.45 grams of FAS was slowly added via glass funnel over 1.5 hours. After 4 hours of mixing, most of the FAS oily phase had disappeared from the water surface indicating a single phase and that the FAS had reacted with the particles. The solution was allowed to stand overnight and was filtered through GFA glass filer paper. Approximately 12 grams of unreacted byproduct was collected. The resulting aqueous dispersion was stable and homogeneous. Upon allowing drops of the dispersion to evaporate on the surface, a surprising hydrophobic film is formed, which is substantially more hydrophobic than comparable amounts of fluorine from Capstone^® RCP (DuPont) or from a treated Ludox® with 100% FAS monolayer (Preparatory Example 1).

Claims

CLAIMS We claim:

1. A composition comprising an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles, wherein the nanoparticles comprise at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is:

(F(CF₂)nCH₂CH₂)_mSi(0-)_p, where n is 2, 3 or 4, where p is 1 , 2 or 3, and where m is (4-p).

2. The composition of claim 1 wherein n is 4.

3. The composition of claim 1 wherein p is 3 and m is 1.

4. The composition of claim 1 wherein the synthetic clay is hectorite clay.

5. The composition of claim 1 wherein the fluoroalkylsilyl is covalently

bonded to the nanoparticie surface.

6. The composition of claim 1 wherein the fluoroalkylsilyl surface modified nanoparticie is present at a concentration in the range of from about 0.01% to about 50% by weight of the total composition.

7. The composition of claim 1 wherein the fluoroalkylsilyl surface modified nanoparticie is present at a concentration in the range of from about 1% to about 40% by weight of the total composition.

8. The composition of claim 1 wherein the fluoroalkylsilyl surface modified nanoparticle is present at a concentration in the range of from about 1 % to about 8% by weight of the total composition.

9. The composition of any of claims 1 -9 further comprising a fluorinated resin emulsion.

10. The composition of any of claims 1 -9 further comprising an alkylated

inorganic nanoparticle having no fluorine.

1 1. The composition of any of claims 1 -9 further comprising at least one

member selected from the group consisting of a wetting agent, anti-soil agent, anti-stain agent, fluorochemical resin, surfactant and mixtures thereof.

12. The composition of any of claims 1-8 further comprising a component moiety bonded to the surface of the nanoparticles having the formula:

[H(CH₂)_M]_n-Si-(0-)p. where M is an integer between 1 and 12, where p is 1 ,2, or 3, and where n is 4-p.

13. A modified substrate comprising: a fluoroalkylsilyl surface modified nanoparticle , wherein the

nanoparticle comprises at least one member selected from the group consisting of titania, zirconia, layered magnesium silicate,

aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is:

(F(CF₂)_nCH₂CH₂)_mSi(0-)p, where n is 2, 3 or 4, where p is 1 , 2 or 3, and where m is (4-p) wherein said substrate comprises a component selected from the group consisting of paper, paperboard and cellulose fiber.

14. The modified substrate of claim 13, wherein the fluoroalkylsilyl surface modified nanoparticle is present on at least on surface of said substrate, inside said substrate, or a combination of both.

15. The modified substrate of claim 13 wherein n is 4.

16. The modified substrate of claim 13 wherein p is 3 and m is 1.

17. The modified substrate of claim 13 wherein the synthetic clay is a hectorite clay.

18. The modified substrate of claim 13 wherein the fluoroalkylsilyl is covalently bonded to the nanoparticle surface.

19. The modified substrate of claim 13 or 15 wherein the fluoroalkylsilyl

surface modified nanoparticle forms at least one layered structure on the surface of the substrate, wherein the layered structure has a thickness of about 10,000 nanometers or less, and a width and length of about 100,000 nanometers or more.

20. The modified substrate of claim 13, wherein the substrate further

comprises a component moiety bonded to the surface of the nanoparticle having the formula:

[H(CH₂)_M]n-Si-(0-)_p. where M is an integer between 1 and 12, where p is 1 ,2, or 3, and where n is 4-p; and further wherein said nanoparticle comprises at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof.

21. An article made from the substrate of claim 13 or 20.

22. The article of claim 21 wherein the article is selected from the group

consisting of paper, paperboard, and cellulose fiber.

23. The article of claim 22 wherein said nanoparticle comprises at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof.

24. The article of claim 22 wherein the total concentration of fluorine on the article is in a range of from about 10 ppm to about 500 ppm w/w .

25. The article of claim 22 wherein the total concentration of fluorine on the article is in a range of from about 50 ppm to about 300 ppm w/w .

26. The article of claim 22 wherein the fluoroalkylsilyl surface modified

nanoparticle is present from about 0.01% to about 2.0% by weight of the article.

27. The article of claim 22 wherein the fluoroalkylsilyl surface modified

nanoparticle is present from about 0.1 % to about 1.0% by weight of the article.

28. The article of claim 22 wherein elemental fluorine is present from about 0.0001% to about 0.10% by weight of the article.

29. The article of claim 22 wherein elemental fluorine is present from about 0.0001 % to about 0.010% by weight of the article.

30. The article of claim 22 wherein the fluoroalkylsilyl surface modified

nanoparticles is present from about 0.01 to about 3 grams per square meter of surface area of the article.

31. The article of claim 22 wherein the fluoroalkylsilyl surface modified

nanoparticles is present from about 0.1 to about 2 grams per square meter of surface area of the article.

32. A process for making a modified paper, paperboard or cellulose fiber

substrate that is oil and grease resistant comprising:

(i) applying an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles to the substrate, wherein said nanoparticles comprises at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof; and wherein said fluoroalkylsilyl is: (F(CF₂)_nCH₂CH₂)_mSi(0-)p, where n is 2, 3 or 4, where p is 1 , 2 or 3, and where m is (4-p); and

(ii) drying the substrate.

33. The process of claim 32 wherein n is 4, p is 3, m is 1 , and the synthetic clay is a hectorite clay.

34. The process of claim 32 or 33 wherein the fluoroalkylsilyl moieties are covalently bonded to the nanoparticle surface.

35. The process of claim 32 or 33 wherein the fluoroalkylsiiyi surface modified nanoparticles are formed at a concentration in the range of from about 0.01 % to about 50% by weight of the aqueous dispersion.

36. The process of claim 32 or 33 wherein the fluoroalkylsilane surface

modified nanoparticles are formed at a concentration in the range of from about 1 % to about 40% by weight of the aqueous dispersion.

37. The process of claim 32 or 33 wherein the fluoroalkylsilane surface

modified nanoparticles are formed at a concentration in the range of from about 1 % to about 8% by weight of the aqueous dispersion.

38. The process of Claim 32 or 33, wherein said aqueous dispersion further comprises a fluorinated resin emulsion.

39. The process of claim 32 or 33, wherein said aqueous dispersion further comprises an alkylated inorganic nanoparticle having no fluorine.

40. The process of claim 32 or 33, wherein said aqueous dispersion further comprises at least one member selected from the group consisting of a wetting agent, anti-soil agent, , fluorochemical resin, surfactant, silicones, optical brighteners, antibacterial components, anti-oxidant stabilizers, coloring agents, light stabilizers, UV absorbers, wetting agents, starch, polyvinyl alcohol, retention aids and wet strength aids and mixtures thereof.

41. The process of claim 32 or 33, wherein said aqueous dispersion further comprises a component moiety bonded to the surface of the nanoparticles having the formula: