Composition of (per)fluoropolyethers for the treatment of cellulosic substrates Cross-reference to related applications

[0001] This application claims priority to US 62/268894 provisional application filed on 17 Dec 2015 and EP 16156567.6 filed on 19 Feb 2016, the whole content of these applications being incorporated herein by reference for all purposes.

Technical field

[0002] The present invention relates to a composition for the treatment of cellulosic substrates, in particular to a composition for imparting grease and oil repellence to cellulosic substrates.

Background art

[0003] The use of fluorochemicals for the treatment of packagings, in particular

packagings comprising a cellulosic substrate, to confer grease and oil repellence thereto is known in the art.

[0004] Among the fluorochemicals used for such purpose, (per)fluoropolyether

derivatives stand out for their favourable toxicological properties.

[0005] EP 0687533 A (AUSIMONT S.P.A.) 20/12/1995 , EP 1 138826 A

(AUSIMONT S.P.A.) 04/10/2001 , EP 1371676 A (SOLVAY SOLEXIS S.P.A.) 17/12/2003 , EP 1327649 A (SOLVAY SOLEXIS S.P.A.) 16/07/2003 and WO 2010/000715 A (SOLVAY SOLEXIS S.P.A.) 07/01/2010 disclose methods for conferring oil repellence to substrates, in particular cellulosic substrates, using (per)fluoropolyethers comprising phosphate groups and EP 1225178 A (AUSIMONT S.P.A.) 24/07/2002 specifically discloses a process for the manufacture of mixtures of phosphoric mono- and diesters of

(per)fluoropolyethers. WO 2010/000715 A further discloses the use of (per)fluoropolyether carboxylates and of (per)fluoropolyethers comprising at least one urethane moiety for conferring oil repellence to substrates. Such use of (per)fluoropolyether carboxylates is also known from EP 1690882 A (SOLVAY SOLEXIS S.P.A) 16/08/2006 , EP 1484445 A (SOLVAY SOLEXIS S.P.A.) 08/12/2004 and EP 1489124 A (SOLVAY SOLEXIS S.P.A.)

22/12/2004 , while such use of (per)fluoropolyethers comprising at least one urethane moiety is also disclosed in EP 1273704 A (AUSIMONT S.P.A.) 08/01/2010 .

[0006] Said (per)fluoropolyether derivatives are typically used in the form of a

composition (or formulation) with other ingredients and are incorporated into a cellulose substrate during the manufacture of the same at the paper mill. Actually, said derivatives are generally introduced in the formulations employed in size-press treatment, coating treatment, calender water box treatment or in wet-end treatment in the paper machines.

[0007] A paper machine is actually a large de-watering device consisting generally of a head box, a wire section, press section and dryer section wherein, starting from a dilute suspension of fibres (and possibly fillers, dyes and other chemicals) which is homogenously fed onto a fine mesh through which the water drains, a fibres web forms and is conveyed onto subsequent pressing and drying stages.

[0008] In the wet-end treatment, the (per)fluoropolyether derivatives are introduced in the initial fibres suspension dispersion and caused to deposit onto the fibres during web formation.

[0009] When used in the size-press treatment, the (per)fluoropolyether derivatives are caused to impregnate the web of paper fibers by passing this latter into a sizing liquid pond located above a roll nip. As a result, the paper web absorbs the sizing liquor including the (per)fluoropolyether derivatives.

[0010] When used in a coating treatment, the (per)fluoropolyether derivatives are caused to impregnate the web of paper fibers by passing this latter through a coater, typically a rod or metering blade. As a result, a thin film of coating of (per)fluoropolyether derivative is applied to the surface of the paper web.

[001 1] When used in a calendar water box, the (per)fluoropolyether derivatives are caused to impregnate the web of paper fibers by passing this latter through a calender stack equipped with a water box. The water box applies a dilute solution of (per)fluoropolyether derivative to the calender roll which is then transferred to the paper web.

[0012] In the above processes, the (per)fluoropolyether derivative is used in the form of a liquid composition comprising an aqueous or a solvent medium. The composition may contain additional ingredients, such as water-dispersible or water-soluble organic polymers, latexes, hydrosols, starch, sodium alginate, carboxy methyl cellulose, proteins, pigments, dyes and other additives, such as clays, dispersants, lubricants, defoamers, film-formers, antifoamers, cross- linkers, chelating agents and water-sizing agents.

[0013] However, in all such processes, a significant amount of (per)fluoropolyether derivative is caused to penetrate the entire thickness and surface of the substrate, while grease and oil repellence are required only at the surface of certain areas of the finished substrate, in particular of paper. Also,

(per)fluoropolyether derivatives are lost with broken and trimmed paper.

Actually, for cellulosic substrates, (per)fluoropolyether derivatives costs contribution represents a high fraction of the final cost of the finished substrate: even if present in amounts ranging from 0.1 to 1 % by weight with respect to the dry cellulose fibres, the (per)fluoropolyether derivatives represent from 10% up to 50% of the total costs (including the process water, the energy and the cellulose). It is thus essential to reduce consumption of such derivatives, their recycle and improper sizing.

[0014] There is therefore still a continuous need to improve the grease and oil

repellence of substrates while keeping the amount of (per)fluoropolyether derivative as low as possible.

Disclosure of the invention

[0015] The Applicant has surprisingly found out that compositions comprising a

(per)fluoropolyether phosphate, a polysaccharide and a hydroxy-carboxylic acid comprising at least one carboxylic acid group and at least one hydroxyl group, confer remarkably higher grease and oil repellence to substrates, in particular cellulose substrates, than compositions which do not contain the said carboxylic acid and that this effect is achieved at concentrations of (per)fluoropolyether lower than 1 % with respect to the weight of the composition.

[0016] Accordingly, the present invention relates to a composition [composition (C)] which comprises:

- at least one (per)fluoropolyether phosphate [PFPE-phosphate (P1 )];

- at least one polysaccharide [polymer (P2)]; and

- at least one hydroxy-carboxylic acid comprising at least one carboxylic acid group and at least one hydroxyl group [hydroxy-carboxylic acid (A)].

[0017] The invention further relates to a method [method (M)] for imparting grease and oil repellence to a substrate, in particular a cellulosic substrate, which comprises applying to said substrate a composition (C) and to a substrate [substrate (S)], in particular a packaging, treated with composition (C).

Meaning of certain expressions, symbols and abbreviations

[0018] Throughout the present description, (per)fluoropolyether means "fully or

partially fluorinated polyether". The acronym "PFPE" stands for "

(per)fluoropolyether".

[0019] The use of parentheses "(...)" before and after symbols or numbers

identifying compounds or chemical formulae, like, for example "composition (C)", "PFPE-phosphate (P1 )", "chain (R _f )" has the mere purpose of better distinguishing those symbols or numbers from the rest of the text; thus, said parentheses could also be omitted.

[0020] When ranges are indicated, range ends are included.

[0021 ] The expression "as defined above" is intended to comprise all generic and specific or preferred definitions referred to by that expression in preceding parts of the description, unless indicated otherwise.

The (per)fluoropolyether phosphate [PFPE-phosphate (P1)]

[0022] For the purpose of the present invention, the expression "(per)fluoropolyether phosphate" [PFPE-phosphate (P1 )] denotes a polymer comprising at least one fully or partially fluorinated fluoropolyoxyalkylene chain [chain (Rf)] and at least one phosphate group. In greater detail, the PFPE-phosphate (P1 ) is an ester of phosphoric acid [P(0)(OH)3] with at least one a PFPE comprising at least one free hydroxy group [herein after "PFPE alcohol"]. The -OH groups of phosphoric acid which are not esterified with the PFPE alcohol can be in the free -OH form or in the form of derivatives thereof, such as organic or inorganic salts or esters with other non-PFPE alcohols.

[0023] Chain (Rf) comprises repeating units (R°) selected from the group consisting of: -CFX-O-, -CF2-CFX-O-, wherein X is -F or -CF ₃ ; -CFX'-CF ₂ -O-, wherein X' is -CF ₃ ; -CF2-CF2-CF2-O-; -CF2-CF2-CF2-CF2-O- and -(CR ₄ R ₅ CF ₂ CF ₂ O)-, wherein R ₄ and R5, equal to or different from one another, are selected from H, CI or perfluoroalkyl from 1 to 6 carbon atoms; and mixtures thereof.

[0024] Should PFPE-phosphate (P1 ) comprise recurring units R° of different types, advantageously said recurring units are randomly distributed along the fluoropolyoxyalkene chain.

[0025] PFPE-phosphate (P1 ) may also contain one or more functional groups

comprising other heteroatoms than phosphorus, for example nitrogen and silicon. A preferred example of such other functional groups is the amido group.

[0026] Preferably, chain (Rf) is a straight (per)fluoropolyoxyalkylene chain having two ends, wherein at least one end is bound, directly or through a spacer, to a phosphoric acid moiety via an ester bond.

[0027] The (per)fluoropolyoxyalkylene chain (Rf) has a number average molecular weight (M _n ) typically higher than 1 ,000, preferably ranging from 1 ,000 to 5,000, and is preferably selected from the following structures:

(A) -(CF ₂ CF(CF ₃ )O)a(CFYO) _b - wherein Y is F or CF ₃ ; a and b are both integers or a is an integer and b is 0, such that the molecular weight is within the above range and with the proviso that, when b is other than 0, a/b is equal to or higher than 40;

(B) (CF2CF(CF ₃ )O)a(CFYO)b-CF2(R'F)CF2-O-(CF2CF(CF ₃ )O)a(CFYO)b- wherein RV is a Ci _-4 (per)fluoroalkylene group;

(C) -(CF ₂ CF2O)c(CF2O)d(CF2(CF ₂ )zO)h- wherein c, d and h are integers >0 such that the molecular weight is within the above range; c/d is between 0.1 and 10; h/(c+d) is between 0 and 0.05; z is 2 or 3;

(D) -(CF2CF(CF3)0)e(CF2CF ₂ 0)f(CFYO)g- wherein Y is F or CF ₃ ; e, f, g are integers≥0 such that the molecular weight is within the above range; e/(f+g) is between 0.1 and 10, f/g is between 2 and 10;

(E) -(CF2(CF2)zO)s- wherein s is an integer such to give the above molecular weight, z has the above defined meaning;

(F) -(CR ₄ R5CF2CF20)j- wherein R ₄ and Rs are equal to or different from each other and selected from H, CI or Ci-6 perfluoroalkyl, j' being an integer >0 such that the molecular weight be that above indicated;

(G) -(CR R5CF ₂ CF20)p'-R'F-0-(CR R5CF2CF ₂ 0)q', wherein RV is a Ci _-6 (per)fluoroalkylene group; p' and q' are integers≥0 such that the molecular weight be that above mentioned;

(H) -(CF(CF ₃ )CF20) _r -(R'F)-0-(CF(CF ₃ )CF ₂ 0) _r , j" and j'" being integers >0 such to give the above molecular weight, RV is a Ci-6 (per)fluoroalkylene group.

According to a preferred embodiment, the PFPE-phosphate (P1 ) complies with formula (P1 -A) or (P1 -B):

(P1 -A) [Rfi-CFY-L-0] _m P(0)(OXp) _3-m

(P1 -B) (XpO)2P(0)[0-L-CFY-0-Rf-CFY-L-0-P(0)(OXp)]m (OXp) wherein:

- Rfi is equal to -Rf-Tt, wherein T _t is a Ci _-3 (per)fluoroalkyl group, optionally comprising H or CI atoms, and Rf has the same meaning as defined above;

- m is an integer ranging from 1 to 3, preferably 1 or 2;

- m' is an integer ranging from 0 to 20, preferably from 0 to 4;

- Y is F or CF ₃ ;

- L is a bond or a divalent organic group;

- X _p is H, a metal, preferably an alkaline or alkaline-earth metal, or an ammonium group of formula N(R _P ) ₄ , wherein each of R _p , equal or different at each occurrence, is H, an alkyl group or a hydroxyalkyl group. [0029] Divalent group L is preferably selected from -CH2(OCH ₂ CH ₂ )n- and -CONR'- (CH2)q-, wherein n and q are integers ranging from 0 to 8, preferably from 0 to 3. More preferably, divalent group L is a -CH2(OCH2CH2) _n - group in which n is as defined above.

[0030] The PFPE-phosphate (P1 ) more preferably complies with formula (P1 -C) or (P1 -D):

(P1 -C) [rp-(CF2CF(CF3)0) _a i(CFYO)bi-CF2-CH2(OCH ₂ CH2)n-0]mp-

(P1 -D)

(XpO)2P(0)[0-(CH2CH20)n€H2-CF2-0-(CF2CF20)ci(CF ₂ 0)di-CF2-

CH2(OCH ₂ CH2)n-0-P(0)(OXp)]mp-(OXp)

wherein:

- T _p is a C-1-3 (per)fluoroalkyl group, optionally comprising one or more CI atoms, a1 > 0, b1≥0, a1 + b1 being such that the molecular weight ranges from 500 to 10,000; a1/b1 preferably ranging 10 from 100; n' ranges from 0 to 3; mp' is 1 or 2; c1 > 0, d1≥0, c1 + d1 being such that the molecular weight ranges from 1 ,000 to 5,000; c1/d1 being preferably between 0.1 and 10, mp" ranges from 1 to 10 and n' is as defined above.

[0031] PFPE phosphates (P1 ) and methods for their manufacture are known in the art, for example from the aforementioned patent documents EP 0687533, EP 1 138826, EP 1371676, EP 1327649, WO 2010/000715 and EP 1225178.

[0032] Preferred (P1 ) phosphates comply with formula (P1 -D); such phosphates are marketed by Solvay Specialty Polymers Italy S.p.A. as water dispersion in admixture with propylene glycol [20 wt % of (P1 ) phosphate and 6% propylene glycol] with trademark Solvera ^® .

[0033] Advantageously, PFPE phosphate (P1 -D) is one marketed as Solvera ^® PT 5045, said phosphate complying with formula:

(HO)2P(0)[0-(CH2CH20)nCH2-RF-CH2(OCH ₂ CH2)n-0-P(0)(OH)]o.iO-

(CH2CH20)nCH2-RF-CH2(OCH ₂ CH2)nO-P(0)(OH)2

wherein RF is CF2-O-(CF2CF2O) _c i(CF2O)di-CF2, d and d1 are selected in such a way as the number average molecular weight is 1 ,500, the c1/d1 ratio ranges from 2 to 3 and n' is 1.8.

The polysaccharide [polymer (P2)]

[0034] For the purpose of the present invention, the expression "polysaccharide

polymer (P2)" denotes a straight or branched polymeric carbohydrate molecule comprising a plurality of monosaccharide units bound together by glycosidic linkages. The glycosidic linkages can be either alpha- or beta- glycosidic linkages.

[0035] Non limiting examples of polysaccharides (P2) are cellulose, starch, chitin, pectin, alginic acid and derivatives thereof.

[0036] In one preferred embodiment, the polysaccharide (P2) is cellulose, a linear polysaccharide wherein a plurality of D-glucose units are linked together by beta (1→4) glicosidic linkages. More preferably, the cellulose is carboxymethyl cellulose, a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the monosaccharide units in the cellulose skeleton; carboxymethyl cellulose can be used in the form of a salt with an alkali metal, typically as sodium salt. Another suitable derivative of cellulose is hydroxyethyl cellulose, a cellulose derivative with hydroxyethyl groups (-CH2CH2OH) bound to some of the hydroxyl groups of the

monosaccharide units in the cellulose skeleton.

[0037] In another preferred embodiment, the polysaccharide is alginic acid, a linear copolymer comprising homopolymeric blocks of (1 -4)-linked beta-D- mannuronate (M) and its C-5 epimer alpha-L-guluronate (G) residues, respectively, covalently linked together in different sequences or blocks. The homopolymeric blocks can be formed by consecutive G-residues (G-blocks), consecutive M-residues (M-blocks) or alternating M and G-residues (MG- blocks).

[0038] In still another preferred embodiment, the polysaccharide is starch or a

derivative thereof; suitable examples of starch derivatives are carboxymethyl starches, like those marketed by Western Polymer Corporation as Wescote ^® 3300 and 3090.

[0039] More preferably, the polysaccharide polymer (P2) is carboxymethyl cellulose. The hydroxy-carboxylic acid (A)

[0040] For the purpose of the present invention, a "hydroxy-carboxylic acid (A)" is an organic acid comprising at least one carboxylic acid group and at least one hydroxyl group.

[0041] Preferably, the hydroxy-carboxylic acid (A) is a straight or branched aliphatic mono- or polycarboxylic acid comprising one or more hydroxyl groups.

Examples of suitable hydroxy-carboxylic acid (A) are HOCH2COOH (glycolic acid; 2-hydroxyethanoic acid), CH3CHOHCOOH (lactic acid; 2- hydroxypropanoic acid), HOOCCH2CHOHCOOH (malic acid;

hydroxybutanedioic acid), HOOCC(CHOH) ₂ COOH (tartaric acid; 2,3- dihydroxybutanedioic acid), HOC(COOH)(CH ₂ COOH) ₂ (citric acid; 2- hydroxypropane-1 ,2,3-tricarboxylic acid) and

HOOCCHOHCH(COOH)CH ₂ COOH (isocitric acid; 1 -hydroxypropane-1 ,2,3- tricarboxylic acid).

[0042] Preferably, hydroxy-carboxylic acid (A) is a polycarboxylic acid comprising at least one hydroxyl group.

[0043] Advantageously, hydroxy-carboxylic acid (A) is citric or isocitric acid; more advantageously, hydroxy-carboxylic acid (A) is citric acid.

Composition (C)

[0044] As stated above, composition (C) according to the present invention

comprises:

- at least one (per)fluoropolyether phosphate [PFPE-phosphate (P1 )] as defined above;

- at least one polysaccharide [polymer (P2)] as defined above;

- at least one hydroxy-carboxylic acid (A) as defined above.

[0045] Preferably, the polymer (P1 ) in the composition is a PFPE-phosphate of formula (P1 -D) as defined above. [0046] Preferably, the polymer (P2) is carboxymethyl cellulose or alginic acid;

advantageously, the polymer (P2) is carboxymethyl cellulose.

[0047] Preferably, the hydroxy-carboxylic acid (A) is citric or isocitric acid; more

preferably, the hydroxy-carboxylic acid (A) is citric acid.

[0048] Composition (C) is typically a liquid aqueous composition in a medium

wherein water amounts to more than 50% wt of the medium. A polar organic solvent is typically present in the medium in order to dissolve or emulsify the polymer (P1 ). The polar organic solvent is, for example, at least one of alcohols, glycols, ethers. As alcohols, isopropanol, ethanol, methanol, t- butanol can be used; as ethers, mention can be made of dipropyleneglycol monomethylether; as glycols, ethylene or propylene glycols can be mentioned. Preferably, the solvent is a glycol. The polar solvent is usually present in an amount ranging from 1 to 8 %wt with respect to the weight of the composition.

[0049] Optionally, the composition might comprise additional components or

ingredients.

[0050] The composition may notably comprise the polymer (P1 ) in combination with at least one water-dispersible or water-soluble cationic polymer.

[0051] Said cationic polymers have typically a charge density of at least 1 meq/g of dry polymer; they are generally selected among polyamines and/or polyamido-amines. Cationic polymers suitable to the purposes of the invention are notably those disclosed in the aforementioned EP 1690882.

[0052] Also, the composition may contain any suitable latex known in the art. By way of example, suitable latexes include styrene-acrylic copolymer, acrylonitrile styrene-acrylic copolymer, polyvinyl alcohol polymer, acrylic acid polymer, ethylene vinyl alcohol copolymer, ethylene-vinyl chloride copolymer, ethylene vinyl acetate copolymer, vinyl acetate-acrylic copolymer, styrene-butadiene copolymer and acetate-ethylene copolymer; styrene-acrylic copolymer, styrene-butadiene copolymer, or vinyl acetate-acrylic copolymer are preferred. [0053] Also, the composition may optionally comprise one of more of hydrosol, proteins and the like.

[0054] The composition may optionally comprise a pigment or a dye. Suitable

pigments include kaolin clay, delaminated clays, structured clays, calcined clays, alumina, silica, aluminosilicates, talc, calcium sulfate, ground calcium carbonates, and precipitated calcium carbonates. Suitable dyes are typically organic dyes, comprising e.g. chromophores, like, for instance, derivates of acridine, anthraquinone, diphenyl or triphenylmethane, azo-compounds, nitro- or nitroso-substituted compounds, quinone, phthalocyanines, thiazin, thiazole, oxazin, oxazone, xanthene, fluorine.

[0055] Also, the composition may comprise other additives including clays,

dispersants, lubricants, defoamers, film-formers, antifoamers and

crosslinkers.

[0056] Composition (C) typically contains PFPE-phosphate (P1 ) in an amount

ranging from 0.01 % to 1 % wt with respect to the weight of the composition, preferably from 0.1 to 1 % wt. Advantageously, the amount ranges from 0.1 % to 0.9%wt, from 0.1 % to 0.8%wt, from 0.1 % to 0.7%wt, from 0.1 % to 0.6%wt, from 0.1 % to 0.5%wt of the weight of the composition. In a preferred embodiment, the amount of PFPE-phosphate (P1 ) is 0.25%wt with respect to the weight of composition (C); in another embodiment, the amount is 0.5% wt with respect to the weight of composition (C).

[0057] Composition (C) typically contains polymer (P2) in an amount ranging from 0.1 to 1.5 %wt with respect to the weight of the composition.

[0058] Composition (C) typically contains hydroxy-carboxylic acid (A) in an amount ranging from 0.1 % to 5%wt, preferably from 0.1 % to 1 .5 %wt with respect to the weight of the composition.

[0059] According to a preferred embodiment, composition (C) comprises, preferably consists of:

- a PFPE-phosphate (P1 -D) as defined above;

- carboxymethyl cellulose;

- citric acid; - water and

- a polar organic solvent, preferably a glycol.

[0060] According to another preferred embodiment, composition (C) preferably

consists of:

- a PFPE-phosphate (P1 -D) as defined above;

- alginic acid;

- citric acid;

- water and

- a polar organic solvent, preferably a glycol.

Method (M) and substrates (S)

[0061] As stated above, the invention also relates to a method [method (M)] for imparting grease and oil repellence to a substrate, preferably a cellulosic substrate, said method comprising applying composition (C) to a substrate.

[0062] Composition (C) can be applied to a substrate according to known methods, including the aforementioned wet-end treatment, size-press treatment, printing-press treatment, coating treatment and treatment in a calendar water box. Preferably, method (M) comprises applying composition (C) by size- press treatment, according to procedures known in the art.

[0063] Non limiting examples of substrates which can submitted to method (M) are cellulose substrates typically used in packaging applications, for example paper-like substrates, solid bleached sulphite paper boards and other cellulosic fibre assemblies.

[0064] Substrates, preferably cellulose substrates, treated with composition (C) [substrates (S)] are also part of the present invention. More preferably, a substrate is a paper packaging, for example a paper food packaging.

[0065] The Applicant surprisingly found out that substrates treated with a

composition (C) according to the present invention are endowed with improved oil and grease resistance with respect to substrates treated with PPFE-phosphate (P1 ) only or substrates treated with PPFE-phosphate (P1 ) and polymer (P2) together; this was observed even if the amount of PPFE- phosphate (P1 ) in the composition is low and even if the pH of composition (C) is acidic, typically below 4. This is surprising, because, for stability reasons, PPFE-phosphate water compositions having a pH of about 7 to 8 have been used.

[0066] The invention is disclosed in greater detail in the following experimental

section by means of non-limiting examples.

[0067] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

EXPERIMENTAL SECTION

Materials

[0068] Solvera ^® PT5045 PG (in the following PT5045 PG) is a water formulation

comprising:

- a PFPE phosphate of formula:

(HO)2P(0)[0-(CH2CH20)nCH2-RF-CH2(OCH ₂ CH2)n-0-P(0)(OH)]o.iO-

(CH2CH20)nCH2-RF-CH2(OCH ₂ CH2)nO-P(0)(OH)2

wherein RF is CF2-0-(CF2CF20) _c i(CF20)di-CF2, d and d1 are selected in such a way as the number average molecular weight is 1 ,500, the c1/d1 ratio ranges from 2 to 3 and n' is 1.8 and

- propylene glycol (20% wt PFPE phosphate and 6% wt propylene glycol relative to the weight of the formulation) available from Solvay Specialty Polymers Italy S.p.A.

[0069] Solvera ^® PT5045 EA (in the following "PT5045 EA") is a water formulation comprising a PFPE phosphate of the above formula and ethyl acetate (20% wt PFPE phosphate and 6 - 8% ethyl acetate relative to the weight of the formulation).

[0070] Carboxylmethyl cellulose (CMC) of MW = 250 kDa was purchased from

Sigma Aldrich and was used as 3-5 wt% dispersion in distilled water. [0071 ] Scogin ^® MV alginic acid was purchased from FMC BioPolymer and was used as 2-3 wt% dispersion in water.

Preparation of the compositions and of the test paper sheets

[0072] The compositions (size press solutions) of the comparative examples were prepared by dissolving PT5045 PG or PT5045 EA, optionally in combination with carboxymethyl cellulose or with Scogin ^® MV alginic acid in water and citric acid. The compositions were mixed for about five minutes at room temperature before they were used to treat the paper substrates.

[0073] The compositions of the examples were prepared by dissolving PT5045 PG or PT5045 EA, carboxymethyl cellulose or Scogin ^® MV alginic acid and citric acid in water.

[0074] The test paper sheets (A - K) were prepared with the above mentioned size press solutions by using laboratory sheet fed size press (Mathis HF-350 # 59002). Then the treated sheets were dried on a bench top drier at 105°C. The sheets samples were tested with different oil/grease resistance tests. The nip pressure was 4.5 bar and the roller speed was 10m/min.

[0075] The nature and the amount of each ingredient in the compositions (wt% with respect to the weight of the composition) used in each sheet are reported in Table 1 below. For the sake of clarity, in the "PT5045 PG" and "PT5045 EA" columns, the reported percentage indicates the amount PFPE-phosphate polymer as such over with respect to the weight of the composition.

[0076]

Table 1

Sheet Composition Citric CMC Scogin ^® PT5045 PT5045 acid MV alginic PG EA

acid

A* A* - - - 0.25 -

B* B* 0.50 - - 0.25 - c* C* - 1 .50 - 0.25 -

D D 0.50 1 .50 - 0.25 -

E* E* - - 0.587 0.25 -

F F 0.50 - 0.587 0.25 -

G* G* - - - 0.50 -

H H 0.50 1 .50 - 0.50 -

1 1 0.50 - 0.587 0.50 -

J J 0.50 1 .50 - - 0.50

K K 0.50 1 .50 - - 0.25

[0077] * comparative sheets and compositions

Kit test (Determination of oil repellence)

[0078] Paper sheets A* - K were submitted to the so-called 'kit-test' or 'Grease

Resistance Test for Paper and Paperboard' according to TAPPI Test Method T 559 cm-02 standard. This industry standard test evaluates oil/grease resistance properties of paper. In practice, grease resistance is evaluated with respect to twelve solutions with varying strengths of castor oil, toluene, heptane and turpentine (the solutions are numbered from 1 to 12; 1 is being the least aggressive and 12 is being the most aggressive). The higher the rating, and the higher the oil repellence of the paper sheet.

FATTY ACID TEST (N FA test)

[0079] The resistance of paper sheets A* - K to fatty acids was determined as

follows. Fatty acids solutions (FA solutions) numbered from 1 to 1 1 (from less to most aggressive) were prepared blending different amounts of castor oil, oleic acid (C18: 1 ) and octanoic acid (C8:0). Specimens paper sheets A* - K were introduced in an oven maintained at 60° C and 5 drops of each FA solution were dipped onto each specimen. After 5 minutes at 60°C, the oil drops were removed with absorbent tissue and the specimens were inspected for darkening of the surface.

The rating of each paper sheet corresponds to the highest number of the fatty acid solution that causes no alteration to the surface.

Determination of the fluorine concentration on the paper sheets surface

[0080] The fluorine concentration on each paper sheet surface was determined by oxygen-combustion, followed by potentiometric analysis using a standardized fluoride ion selective electrode.

Test results and discussion

[0081 ] The results of the Kit Test, NFA test and of the determination of the fluorine content are reported in Table 2 below.

[0082]

Table 2

Sheet Composition Kit test NFA test Fluorine pH of the

content Composition

A* A* 7 6P 0.0945 8.32

B* B* 8.5 6P 0.1 136 2.49

C* C* 7.5 9P 0.0949 8.08

D D 12 1 1 P 0.1201 3.96

E* E* 7 1 P 0.1 194 7.56

F F 9.5 8P 0.1488 3.48

G* G* 8.5 8P 0.1633 8.13 H H 12 11 S 0.2054 3.90

1 1 10.5 10P 0.2654 3.35

J J 12 10P 0.2196 3.86

K K 12 11 P 0.1199 3.93

[0083] The results reported in the table show that sheets treated with the

compositions according to the invention, comprising PT5045 PG or PT5045 EA, CMC or Scogin ^® MV alginic acid with citric acid have significantly higher performance in the Kit test and NFA Test with respect to comparative compositions containing only the same amount of PT5045 PG or PT5045 EA (compare composition D with composition A ^* and compositions H - K with composition G ^* ) and to comparative compositions containing the same amount of PT5045 PG or PT5045 EA in combination with CMC or Scogin ^® MV alginic acid (compare composition D with compositions B ^* and C ^* ) and composition F with composition E ^* ). It is noted that high performance was achieved at very low concentrations of PFPE-phosphate (0.25%wt in compositions A ^* -C ^* and E ^* and 0.50%wt in composition G ^* ) and even if the pH values of the compositions was below 4.

[0084] The results also show that the sheets treated with the compositions according to the invention have a significantly higher fluorine content than sheets treated with compositions comprising only the PFPE-phosphate or compositions comprising the PFPE-phosphate, CMC and alginic acid

(compare D with compositions A ^* -C ^* , composition F with composition E ^* and compositions H - K with composition G ^* ).