Method for preventing corrosion of metal articles Cross-reference to related applications

[0001 ] This application claims priority to European patent application No.

16196301 .2 filed on October 28, 2016, the whole content of this application being incorporated herein by reference for all purposes. Technical Field

[0002] The present invention relates to a method for preventing the corrosion of metal articles and to compositions for carrying out such method. Background Art

[0003] It is known that metals and alloys undergo corrosion when exposed to certain environmental conditions. Usually, metals undergo

electrochemical oxidation by contact with an oxidant, like oxygen or sulfur and convert to more stable forms, such as their oxides, hydroxides or sulfides. The most common example of electrochemical oxidation is rusting, which consists in the formation of iron oxides or salts on a metal surface and imparts a typical orange coloration.

[0004] One of the methods used to prevent the oxidation of metals and metal alloys is to apply a polymeric film on their surface.

[0005] US 2004265603 (SCHLENOFF, JOSEF B) 30/12/2004 discloses an anticorrosion polymer coating to be applied on a metallic surface, said coating comprising a positively-charged polyelectrolyte and a negatively-charged polyelectrolyte forming a complex. The polyelectrolytes used for making the coating are copolymers having a combination of charged and neutral repeat units. There is no disclosure or suggestion of polymers comprising a neutral polymer chain and one charged unity at each end of the chain. Furthermore, the coating disclosed in this document can be formed either by exposing a surface to alternating oppositely charged polyelectrolyte solutions or using a pre-formed polyelectrolyte complex, which can be obtained by mixing the oppositely-charged polyelectrolytes. The pre-formed complex precipitates and is then dissolved or resuspended in a suitable solvent/liquid to form a polyelectrolyte complex solution/dispersion. Such solution or dispersion is then applied to the substrate surface and the solvent/liquid is evaporated, leaving behind a film comprising the polyelectrolyte complex.

[0006] It is also known that fully or partially fluorinated polyethers, commonly referred to in the polymer field as (per)fluoropolyethers (herein after abbreviated as "PFPEs"), are very versatile polymers. The most widespreadly known PFPEs can be obtained by means of processes comprising either the homopolymerization of hexafluoropropylene oxide (HFPO) or 2,2,3,3-tetrafluorooxetane or the photooxidation of

tetrafluoroethylene (TFE) and/or hexafluoropropylene (HFP).

[0007] PFPEs comprises a fully or partially fluorinated polyoxyalkylene chain (PFPE chain) that contains recurring units having at least one catenary ether bond and at least one fluorocarbon moiety. PFPEs can be divided into non-functional and functional; the former comprise a PFPE chain having at least two ends, wherein such ends bear (per)haloalkyl groups, while the latter comprise a PFPE chain having at least two ends, wherein at least one end comprises a functional group. Functional PFPEs can be used as starting materials for the manufacture of other functional PFPEs that are used as such for a variety of industrial applications, e.g. as additives for lubricant compositions, or as building blocks for the manufacture of block copolymers.

[0008] For example, the use of functional PFPEs in the lubrication field is

disclosed in US 5498547 (HITACHI, LTD) 12/03/1996, related to a rotary magnetic recording medium having a lubricating film layer on its surface. The lubricating film layer comprises a fluoropolyether lubricant having at least two acidic functional groups in one molecule and a fluoropolyether lubricant having at least two basic functional groups in one molecule. This document teaches that the two fluoropolyether lubricants form a stable network structure on the medium surface by an appropriate combination of the lubricant having the acidic groups and the one having the basic groups. It is herein pointed out that magnetic recording media typically comprise a substrate, a magnetic layer and a protective carbon overcoat laid on the magnetic layer and lubricants are applied onto the carbon overcoat in order to prevent wear by contact with a magnetic head floating over the surface of the medium during recording and reproduction, or by contact with dust generated during such contact. Magnetic materials used in the manufacture of recording media are metal oxides, such as ferromagnetic oxides, in admixture with a binder and further additives.

[0009] EP 1231297 A1 (AUSIMONT SPA) 14/08/2002 discloses the use of mono- and bi-functional PFPE having phosphate or silane terminal groups for the treatment of metals or metal alloys in order to confer anti- calcar properties and prevent corrosion. This document neither discloses nor suggests the use of functional PFPEs other than phosphates and silanes and also neither discloses nor suggest to combine PFPE derivatives having ionisable anionic and cationic groups able to interact or form supramolecular structures.

[0010] WO 2013/017470 (SOLVAY SPECIALTY POLYMERS ITALY SPA) 07/02/2013 discloses compositions comprising two ionisable

fluoropolymers, each comprising recurring fluorinated blocks and recurring blocks comprising at least one ionisable anionic or cationic group, wherein at least one ionizable recurring block is comprised between two fluorinated blocks. The two fluoropolymers in the composition are present at an ionic ratio ranging from 1.1 to 0.9. Such compositions are able to form elastomeric materials which, in certain instances, advantageously show a self-repairing behaviour. There is no disclosure or suggestion of compositions comprising fluoropolymers having a chain of recurring fluorinated blocks, said chain having two ends, each end comprising one ionisable anionic or cationic group. There is also no hint to anti-corrosion properties.

[0011] WO 2014/090646 (SOLVAY SPECIALTY POLYMERS ITALY SPA) discloses compositions comprising:

- two ionisable fluoropolymers, each comprising recurring fluorinated blocks and recurring blocks comprising at least one ionisable anionic or cationic group, wherein at least one ionizable recurring block is comprised between two fluorinated blocks;

at least one fluorinated solvent; and

- at least one alcohol.

[0012] Such compositions are stable even after addition of a cross-linking

agent and can be used for the manufacture of polymeric materials endowed with high chemical stability, improved mechanical properties and, in some instances, self-healing properties. There is no disclosure or suggestion of compositions comprising fluoropolymers having a chain of recurring fluorinated blocks, said chain having two ends, each end comprising one ionisable anionic or cationic group. There is also no hint to anti-corrosion properties.

[0013] International application EP2016/056220, filed by the applicant on

March 22, 2016, discloses a non-aqueous fluoropolymer composition [composition (FC)] comprising:

- at least one fluorinated ionisable polymer [polymer (A)] comprising recurring (per)fluorinated blocks [blocks (F)], recurring functional blocks [blocks (B _a )] and at least one curable group [group (C)], said blocks (B _a ) comprising at least one ionisable anionic group [group (I-)];

- at least one fluorinated ionisable polymer [polymer (B)] comprising recurring (per)fluorinated blocks [blocks (F)], recurring functional blocks [blocks (Bb)] and at least one curable group [group (C)], said blocks (Bb) comprising at least one ionisable cationic group [group (l ⁺ )];

- at least one fluorinated solvent [solvent (F)]; and

- at least one solvent [solvent (S)] different from said solvent (F).

[0014] Composition (FC) can be used for example for preparing polymeric articles, preferably amorphous articles, endowed with elastic properties. In some embodiments, the articles are endowed with self-healing properties.

Summary of invention [0015] The Applicant has now found out that certain compositions comprising definite amounts of ionisable polymers having a defined glass transition temperature (Tg) are able to form particularly effective anti-corrosion coatings on metals and alloys.

[0016] In a first aspect, the present invention relates to a method [method (M)] for preventing the corrosion of metals and alloys, said method comprising applying to a metallic or alloy substrate a composition

[composition (C)] comprising, preferably consisting of:

a) at least one polymer [polymer (P1)] comprising a polymer chain

[chain (R)] consisting of a plurality of non-ionisable recurring units [units (U)], said chain having two ends, each end comprising at least one ionisable acid group;

b) at least one polymer [polymer (P2)] comprising a polymer chain

[chain (R)] consisting of a plurality of non-ionisable recurring units [units (U)], said chain (R) being equal to or different from that of polymer (P1 ) and having two ends, each end comprising at least one ionisable amino group

wherein:

- polymers (P1 ) and (P2) are amorphous and have a Tg lower than - 35°C, preferably ranging from -35 to -120°C and wherein

- the ratio between the equivalents of polymer (P1 ) and the equivalents of polymer (P2) in composition (C) ranges from 1.1 to 0.9.

[0017] Tg is typically measured at midpoint by differential scanning calorimetry (DSC) with a scan rate of 20 °C/min.

[0018] For the avoidance of doubt, the ratio between the equivalents of

polymer (P1 ) and the equivalents of polymer (P2) is referred to the acid/base reaction between the at least one ionisable amino group in each end group of polymer (P1 ) and the at least one ionisable acid group in each end of polymer (P2).

[0019] Without being bound to theory, it is believed that, through this reaction, polymer (P1 ) and polymer (P2) form a supramolecular ionic network which shows a significantly higher experimental viscosity than the theoretical viscosity and which is able to form coatings that are highly resistant to corrosion even at very low thicknesses.

[0020] In a further aspect, the invention relates to certain compositions (C) for performing method (M).

[0021] In a still further aspect, the invention relates to a metallic article [article

(A)] coated with composition (C).

General definitions, symbols and abbreviations

[0022] For the avoidance of doubt, throughout the present application, the acronym "PFPE" stands for "(per)fluoropolyether", i.e. fully or partially fluorinated polyether. When this acronym is used as substantive in the plural form, it is referred to as "PFPEs".

[0023] The term "(per)haloalkyl" denotes a fully or partially halogenated

straight or branched alkyl group.

[0024] Unless otherwise indicated, the term "halogen" includes fluorine,

chlorine, bromine and iodine.

[0025] - a "cycloalkyl group" is a univalent group derived from a cycloalkane by removal of an atom of hydrogen; the cycloalkyl group thus comprises one end which is a free electron of a carbon atom contained in the cycle, which able to form a linkage with another chemical group;

- a "divalent cycloalkyl group" or "cycloalkylene group" is a divalent radical derived from a cycloalkane by removal of two atoms of hydrogen from two different carbons in the cycle; a divalent cycloalkyl group thus comprises two ends, each being able to form a linkage with another chemical group;

- the adjective "aromatic" denotes any mono- or polynuclear cyclic group (or moiety) having a number of π electrons equal to 4n+2, wherein n is 0 or any positive integer; an aromatic group (or moiety) can be an aryl or an arylene group (or moiety);

- an "aryl group" is a hydrocarbon monovalent group consisting of one core composed of one benzenic ring or of a plurality of benzenic rings fused together by sharing two or more neighboring ring carbon atoms, and of one end. Non limitative examples of aryl groups are phenyl, naphthyl, anthryl, phenanthryl, tetracenyl, triphenylyl, pyrenyl, and perylenyl groups. The end of an aryl group is a free electron of a carbon atom contained in a (or the) benzenic ring of the aryl group, wherein an hydrogen atom linked to said carbon atom has been removed. The end of an aryl group is capable of forming a linkage with another chemical group;

- an "arylene group" is a hydrocarbon divalent group consisting of one core composed of one benzenic ring or of a plurality of benzenic rings fused together by sharing two or more neighboring ring carbon atoms, and of two ends. Non limitative examples of arylene groups are phenylenes, naphthylenes, anthrylenes, phenanthrylenes,

tetracenylenes, triphenylylenes, pyrenylenes, and perylenylenes. An end of an arylene group is a free electron of a carbon atom contained in a (or the) benzenic ring of the arylene group, wherein an hydrogen atom linked to said carbon atom has been removed. Each end of an arylene group is capable of forming a linkage with another chemical group.

[0026] CycloalkyI, cycloalkylene, aryl and arylene groups can be substituted with one or more straight or branched alkyl or alkoxy groups and/or halogen atoms and/or can comprise one or more heteroatoms, like nitrogen, oxygen and sulfur, in the ring.

[0027] The use of parentheses "(...)" before and after names of compounds, symbols or numbers identifying formulae or parts of formulae like, for example "polymer (P1 )", "chain (R)", etc., has the mere purpose of better distinguishing those names, symbols or numbers from the rest of the text; thus, said parentheses could also be omitted.

[0028] The expression "average functionality (F)" denotes the average number of functional groups per polymer molecule and can be calculated according to methods known in the art. For example, the average functionality (F) of PFPE alcohols can be calculated following the method reported in EP 1810987 B (SOLVAY SOLEXIS SPA) 7/25/2007 or in S.Turri, E. Barchiesi, M. Levi Macromolecules 28, 7271 , (1995). In particular, the average functionality of polymers (P1) and (P2) according to the present invention was determined following the teaching of the latter reference. [0029] When ranges are indicated, range ends are included.

[0030] 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.

[0031] As intended herein, "corrosion" means the conversion of a metal into its corresponding oxide(s), hydroxide(s) or sulphide(s) or mixtures thereof.

[0032] An alloy is a mixture of metals or a mixture of a metal with another element wherein the metal is the main component.

[0033] The expression "ionisable amino group" and "ionisable acid groups" identify amino or acid groups able to form ionic groups, namely cationic and anionic groups respectively. In greater detail, an ionisable amino group identifies a primary, secondary or tertiary amino group, while an ionisable acid group identifies an acid group comprising at least one hydroxyl function in its protonated form, i.e. a protic acid group.

[0034] The expression "non-ionisable recurring unit" identifies a chemical moiety that is not able to form an ionic group with the at least one ionisable amino group or the at least one ionisable acid group in each end of polymers (P1 ) and (P2).

POLYMER (P1 )

[0035] Polymer (P1 ) can be represented with formula (P1 ) here below:

(P1 ) E1 -R-E1 '

wherein:

- R is a polymer chain consisting of a plurality of non-ionisable recurring units [units (U)], equal to or different from one another and

- E1 and E1 ', equal to or different from one another, are end groups each comprising at least one ionisable acid group. Recurring units (U) are hydrocarbon units, which can further comprise non-ionisable atoms or non-ionisable functional groups, including one or more of halogen atoms, preferably fluorine atoms, ethereal oxygen atoms, alkyl or alkoxy silane groups, carbonate, ester, urethane and acrylate groups.

[0036] Non limiting examples of polymers (P1 ) are those wherein chain (R) is independently selected from a fully or partially fluorinated polyoxyalkylene chain, a polyalkylsiloxane chain, a polyoxyalkylene chain, a polycarbonate chain, a polyester chain, a polyacrylate chain and a polybutadiene chain, as described in greater detail here below. Examples of chains (R)

Fully or partially fluorinated polyoxyalkylene chains (RF)

[0037] As intended herein, a fully or partially fluorinated polyoxyalkylene chain [herein after otherwise referred to as "chain (RF)", "(per)fluoropolyether chain" or "PFPE chain"] comprises recurring units [units (UF)] having at least one catenary ether bond and at least one fluorocarbon moiety; typically, chain (RF) comprises repeating units (UF) selected from:

(U _F - i) -CFXO-, wherein X is F or CF ₃ ;

(UF - ii) -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is -F;

(UF - iii) -CF2CF2CW2O-, wherein each of W, equal or different from each other, is F, CI, H,

(U _F - iv) -CF2CF2CF2CF2O-;

(UF - v) -(CF2)j-CFZ-O- wherein j is an integer from 0 to 3 and Z is a group of general formula -ORf*T, wherein Rf* is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the followings : -CFXO- , - CF2CFXO-, -CF2CF2CF2O-, -CF2CF2CF2CF2O-, with each of each of X* being independently F or CF3 and T being a C1-C3 perfluoroalkyl group.

[0038] When recurring units [units (UF)] are different from one another, they are randomly distributed along the chain.

[0039] Preferably, chain (RF) complies with formula (RF-I):

(RF-I) -

(CFXiO)gi(CFX2CFX3O)g2(CF2CF2CF2O)g3(CF2CF2CF2CF ₂ O)g ₄ - wherein:

- Xi is independently selected from -F and -CF3;

- X2, X3, equal or different from each other and at each occurrence, are independently -F, -CF3, with the proviso that at least one of X is -F;

- g1 , g2 , g3, and g4, equal or different from each other, are

independently integers≥0, selected in such a way that the average number molecular weight (M _n ) ranges from 400 to 10,000; should at least two of g1 , g2, g3 and g4 be different from zero, the different recurring units are generally statistically distributed along the chain. More preferably, chain (RF-I) is selected from chains of formulae (RF-

wherein:

- a1 and a2 are independently integers≥ 0 such that the number average molecular weight (M _n ) ranges from 400 to 10,000, preferably from 400 to 5,000; both a1 and a2 are preferably different from zero, with the ratio a1/a2 being preferably ranging from between 0.1 to 10;

wherein:

- b1 , b2, b3, b4, are independently integers≥ 0 such that the number average molecular weight (M _n ) ranges from 400 to 10,000, preferably from 400 to 5,000; preferably b1 is 0, b2, b3, b4 are > 0, with the ratio b4/(b2+b3) being >1 ;

wherein:

- cw = 1 or 2;

c1 , c2, and c3 are independently integers≥ 0 such that the number average molecular weight (M _n ) ranges from 400 to 10,000, preferably from 400 to 5,000; preferably c1 , c2 and c3 are all > 0, with the ratio c3/(c1 +c2) being generally lower than 0.2;

wherein:

- d is an integer >0 such that the number average molecular weight (M _n ) ranges from 400 to 10,000, preferably from 400 to 5,000;

wherein: - Hal, equal or different at each occurrence, is a halogen selected from fluorine and chlorine atoms, preferably a fluorine atom;

- e1 , e2, and e3, equal to or different from each other, are

independently integers≥ 0 selected in such a way tha the such that the (e1 +e2+e3) number average molecular weight (M _n ) ranges from 400 to 10,000.

[0041] Still more preferably, chain (RF) complies with formula (RF-I I I) here

below:

wherein:

- a1 , and a2 are integers > 0 such that the number average molecular weight (M _n ) ranges from 400 to 4,000, with the ratio a2/a1 generally ranging from 0.2 to 5.

Polyalkylsiloxane chains (Rs)

[0042] As intended herein, a polyalkylsiloxane chain [herein after otherwise referred to as chain (Rs)] comprises recurring units [units (Us)] of formula:

(Us)

in which Ra _s and Rb _s , equal to or different from one another, are independently selected from hydrogen, straight or branched (halo)alkyl and aryl, with the proviso that at least one of Ra _s and Rb _s is not hydrogen. Preferred Ra _s and Rb _s groups are straight or branched alkyl groups comprising from 1 to 4 carbon atoms; more preferably, both Ra _s and Rb _s are methyl, i.e. chain (Rs) is a polydimethylsiloxane chain [chain (Rs-I), which comprises recurring units of formula (Us-i) here below:

(Us-i): -OSi(CH ₃ ) ₂ -.

[0043] Chain (Rs) has a number average molecular weight (M _n ) typically

ranging from 500 to 10,000, preferably from 500 to 5,000. Polyoxyalkylene chains (ROA)

[0044] As intended herein, a polyoxyalkylene chain [herein after otherwise referred to as chain (ROA)] is a straight or branched polymer chain consisting of repeating hydrocarbon units comprising at least one catenary ether bond [units (UOA)]; non-limiting examples of chain (ROA) are polyoxyethylene chains and polyoxypropylene chains, respectively comprising recurring units of formulae (UoA-i) - (UoA-iv) here below:

[0045] Chain (ROA) has a number average molecular weight (M _n ) typically ranging from 500 to 10,000, preferably from 500 to 5,000.

Polycarbonate chains (Rpc)

[0046] As intended herein, a polycarbonate chain [herein after otherwise

referred to as chain (Rpc)] consists of repeating units [units (Upc)] of formula:

wherein R°PC represents:

- a straight or branched alkylene chain, optionally comprising one or more cycloalkyl, divalent cycloalkyl group, aryl or arylene groups as defined above.

[0047] The polycarbonate chain has a number average molecular weight (M _n ) typically ranging from 500 to 10,000, preferably from 500 to 5,000. Polyester chains (RPE)

[0048] As intended herein, a polyester chain [herein after otherwise referred to as chain (RPE)] comprises recurring units [units (UE)] of formula:

(UE) wherein R°PE and R°'PE, equal to or different from one another, represent a straight or branched alkylene chain, optionally comprising one or more cycloalkyl, divalent cycloalkyl group, aryl or arylene groups as defined above.

[0049] Chain (RPE) has a number average molecular weight (M _n ) typically

ranging from 500 to 10,000, preferably from 500 to 5,000.

[0050] According to a preferred embodiment, chain (R) of polymer (P1) is a chain (RF) as defined above, preferably a chain of formula (RF-I), more preferably a chain of formula (RF-I 11).

[0051] According to another preferred embodiment, chain (R) of polymer (P1) is a chain (Rs) as defined above, preferably a chain (Rs-I).

Groups E1 and EV

[0052] End groups E1 and E1 ' typically comprise at least one carboxylic acid group, phosphonic acid group or sulfonic acid group, said at least one acid group comprising at least one hydroxyl group in its protonated form, so that it is capable to form an anionic group via acid/base reaction with the at least one ionisable amino group at one of the ends of polymer (P2). E1 and E1 ' can be equal to or different from one another. Preferably, E1 and E1 ' are equal to one another.

[0053] Preferably, groups E1 and E1 ' comply with formula (E1 -A) here below:

(E1 -A) -B1 -EA

wherein:

- B1 represents a chemical bond or a straight or branched alkylene

chain, said alkylene chain preferably comprising from 1 to 20 carbon atoms, and optionally bearing one or more halogen atoms, one or more further -EA groups and/or optionally comprising i one or more heteroatoms or moieties independently selected from:

- cycloalkylene and arylene groups as defined above, -O-, -S-, - OC(O)O-, -OC(O)NH-, -OC(O)S-, -SC(O)S-, -NHC(O)NH- and - NHC(S)NH- and - EA represents a -COOH, a -P(O)(OREA)2 or a -S(O)2OH group, wherein one of REA is hydrogen and the other one is hydrogen or straight or branched alkyl, preferably Ci-C ₄ alkyl.

In one preferred embodiment, EA is a -COOH group.

POLYMER (P2)

[0054] Polymer (P2) can be represented with formula (P2) here below:

(P2) E2-R-E2'

wherein:

- R is a polymer chain as defined above and

- E2 and E2', equal to or different from one another, are end groups each comprising at least one ionisable amino group.

[0055] Chain (R) of polymer (P2) can be the same or different from chain (R) of polymer (P1 ).

Groups E2 and E2'

[0056] End groups E2 and E2' typically comprise at least one ionisable

primary, secondary or tertiary amino group. Groups E2 and E2' can be equal to or different from one another; preferably, groups E2 and E2' are equal to one another, "lonisable primary, secondary or tertiary amino group" means that the amino group is in its free form, so that it is capable to form a cationic group via acid/base reaction with the at least one a ionisable acid group at one of the ends of polymer (P1 ).

[0057] Preferably, groups E2 and E2' comply with formula (E2-A) here below:

(E2-A) -B2-N(R _P2 ) ₂

wherein:

- B2 represents a chemical bond or a straight or branched alkylene

chain, said alkylene chain preferably comprising from 1 to 20 and optionally bearing one or more halogen atoms, one or more further - N(Rp2)2 groups and optionally comprising one or more heteroatoms or moieties independently selected from:

- cycloalkylene and arylene groups as defined above;

-N(RP2*)- wherein RP2* represents hydrogen or straight or branched alkyl, preferably Ci-C ₄ alkyl, more preferably methyl; -Ο-, -S-, -OC(0)0-, -OC(O)NH-, -OC(0)S-, -SC(0)S-, -NHC(O)NH- and -NHC(S)NH- and

RP2 represents hydrogen or straight or branched alkyl, preferably Ci- C ₄ alkyl.

Polymers (P1) and (P2) wherein chain (R) is a chain (RF) [herein after polymers (P _F 1) and (P _F 2)]

[0058] Polymers (PF1 ) and (PF2) can be prepared according to methods known in the art for the synthesis of PFPEs. In particular, the synthesis of polymers (PF1 ) and (PF2) wherein chain (RF) is a chain of formula (RF-I) can be carried out by oxypolymerization of fluoroolefins, followed by conversion of a resulting -CFXC(O)F terminated polymer ("acyl fluoride- terminated polymer", wherein X is as defined above) into the

corresponding ethyl ester of formula (EF1 ):

(E _F 1 ) (R _F -l)-(CFXC(0)OEt) ₂

[0059] Ester (EF1 ) can be either hydrolyzed to provide an acid polymer (PF1 ) wherein E and E' represent -CFXC(O)OH [herein after (PF1 -A)] or reduced to the corresponding PFPE diol ["diol (DF1 )] of formula (RF-I)- (CFXCH ₂ OH) ₂ [herein after "PFPE diol (D _F 1 -A)"]. The reduction of ester (EF1 ) can be carried out according to methods known in the art, using reducing agents such as NaBH ₄ , or by catalytic hydrogenation, as disclosed, for example, in US 6509509 A (AUSIMONT S.P.A) 7/5/2001 , US 657341 1 (AUSIMONT S.P.A.) 1 1/21/2002, WO 2008/122639 A (SOLVAY SOLEXIS S.P.A.) 10/16/2008.

[0060] Polymer (PF1 -A) can be used as such in the manufacture of

compositions (C).

[0061 ] Diols (DF1 -A) can be reacted with alkylene oxides, typically ethylene oxide and propylene oxide, in the presence of a base, to provide further diols (DF1 -B) - (DF1 -D) of formulae:

(D _F 1 -B) (RF-l)-[CFXCH2O(CH2CH ₂ O)n°DH]2

(D _F 1 -C) (RF-I)-{CFXCH ₂ O[CH(CH3)CH ₂ O] n° _D H} ₂

[0062] (D _F 1 -D) (R _F -l)-{CFXCH2O[CH2CH(CH ₃ )O] n°DH}2

wherein n°D is a positive number, preferably ranging from 1 to 10, more preferably ranging from 1 to 5. Diols (DF1 -B) - (DF1 -D) can also be used as precursors for polymers (PF1 ) and (PF2), as explained below in greater detail.

[0063] Diols (DF1 -A) and (D _F 1 -B) with a chain (RF-I I I) and wherein in (D _F 1 -B) n°D ranges from 1 to 2 are available from Solvay Specialty Polymers Italy S.p.A. with the tradename Fomblin ^® Z DOL. Other diols (D _F 1 -B) - (D _F 1 -D) can be obtained following the teaching of WO2014090649 (SOLVAY SPECIALTY POLYMERS ITALY SPA).

[0064] Throughout the present application, ester (EF1 ), diols (DF1 ) and

polymers (PF1 ) and (PF2) are visually represented as bifunctional compounds. However, it is known to a person skilled in the art that ester (EF1 ) and diols (DF1 ) such are always obtained as mixtures comprising the corresponding mono-functional and neutral esters or alcohols which form in the oxypolymerization reaction, i.e. compounds terminating with (per)haloalkyl groups at one or both ends, typically C1 -C3 perfluoroalkyl groups. Ester (EF1 ) and diols (DF1 ) are thus characterized by an average functionality (F) as defined above; the higher the average functionality, the higher the number of bifunctional species. As a consequence, polymers (PF1 ) and (PF2) obtained from ester (EF1 ) or from diols (DF1 ) are also in admixture with corresponding polymers wherein one end of chain (RF) bears a (per)haloalkyl group and with neutral compounds present in the (EF1 ) or diol (DF1 ) used as starting material. Usually, neutral compounds that comprise (per)haloalkyl groups at both ends are present in an amount lower than 0.04% on a molar basis. For the purpose of the present invention, ester (EF1 ), diols (DF1 ) having an average functionality (F) higher than 1 , preferably of at least 1.5 can be used.

[0065] PFPE ester (EF1 ) and diols (DF1 ) can be used as precursors for the synthesis of polymers (PF1 ) and (PF2) with suitable reaction partners, according to methods known in the art for the manufacture of PFPE derivatives. [0066] For example, PFPE ester (EF1 ) can be used as precursor for polymers (PF1 ) or (PF2) wherein groups (E1 -A) and (E2-A) respectively comply with formulae (E1 -Aa), (E1 -Ab), (E2-Aa), (E2-Ab) here below :

(E1 -Aa) -CF ₂ C(O)NH-B1 ^* -E _A

(E1 -Ab) -CF ₂ C(O)O-B1 ^* -E _A

(E2-Aa) -CF ₂ C(O)NH-B2 ^* -N(R _P2 ) ₂

(E2-Ab) -CF ₂ C(O)O-B2 ^* -N(R _P2 ) ₂

wherein:

- EA and Rp ₂ are as defined above and

- B1 ^* and B2 ^* represent straight or branched alkylene chains, said alkylene chain preferably comprising from 1 to 10 carbon atoms and optionally bearing one or more halogen atoms, and/or optionally comprising one or more heteroatoms or moieties independently selected from:

- cycloalkylene and arylene groups as defined above;

-O-, -S-, -OC(O)O-, -OC(O)NH-, -OC(O)S-, -SC(O)S-, -NHC(O)NH- and -NHC(S)NH-.

[0067] B1 ^* may also comprise one or more further EA groups, while B2 ^* may also comprise one or more further -N(Rp ₂ ) ₂ groups.

[0068] B2 ^* may also comprise one or more -N(Rp ₂ *)- moieties.

[0069] Polymers (P _F 1 ) or (P _F 2) wherein groups (E1 -A) and (E2-A) comply with formulae (E1 -Aa), (E1 -Ab), (E2-Aa), (E2-Ab) as defined above can be manufactured by reacting ester (EF1 ) with compounds of formulae NH ₂ - B1 ^* -E _A and HO-B2 ^* -N(R _P2 ) ₂ , wherein B1 ^* , EA, B2 ^* and N(R _P2 ) ₂ are as defined above.

[0070] Should B1 ^* and B2 ^* polymers (P _F 1 ) or (P _F 2) contain one or more of the aforementioned heteroatoms or moieties, end groups (E1 -Aa), (E1 -Ab), (E2-Aa), (E2-Ab) can also be build up by subsequent reactions of ester (EF1 ) with suitable reaction partners. For example, a polymer (PF1 ) wherein group (E1 -Aa) comprises a -NHC(O) moiety can be obtained by reacting ester (EF1 ) first with a diamine and then with an acid comprising two EA groups. A polymer (PF1 ) wherein group (E1 -Ab) comprises one or more -O-C(O)-NH moieties can be obtained by reacting ester (EF1 ) first with a diol and the with a diisocyanate.

[0071] PFPE diols (DF1 ) can be used, for example, as precursors of polymers (PF1 ) and (PF2) wherein groups (E1 -A) and (E2-A) respectively comply with the formulae listed below:

in which X, EA and Rp ₂ are as defined above and nD is 0 or a positive number, preferably from 1 to 10, more preferably from 1 to 5, while B1 ^** and B2 ^** represent a chemical bond or straight or branched alkylene chains, said alkylene chains preferably comprising from 1 to 10 carbon atoms and optionally bearing one or more halogen atoms, and/or comprising one or more heteroatoms or moieties independently selected from:

-cycloalkylene and arylene groups as defined above;

-O-, -S-, -OC(O)O-, -OC(O)NH-, -OC(O)S-, -SC(O)S-, -NHC(O)NH- and

-NHC(S)NH-.

[0072] B1 ^** may also comprise one or more further EA groups, while B2 ^** may also comprise one or more further -N(Rp ₂ ) ₂ groups.

[0073] B2 ^** may also comprise one or more -N(Rp ₂ *)- moieties.

[0074] For example, starting from a PFPE diol (DF1 -A) or (DF1 -B), polymers (PF2) can be obtained complying with formula (PF2-A):

(PF2-A) (R _F -l)-[CFXCH ₂ (OCH ₂ CH ₂ )nDN(R _P2 ) ₂ ] ₂

in which RF-I, X, Rp ₂ and nD are as defined above.

[0075] Conveniently, polymers (PF2-A) can be obtained by converting a PFPE diol (DF1 -A) or (DF1 -B) into the corresponding sulfonic ester (like the trifluoromethanesulfonyl, perfluorobutylsulfonyl or p-toluenesulfonyl ester) and then reacting the sulfonic ester with an amine of formula HN(R _P2 ) ₂ , following the procedure disclosed in US 6984759 B (SOLVAY SOLEXIS SPA).

[0076] Amines (PF2-A) can be used as such in the manufacture of

compositions (C) or can be used as precursors of other polymers (PF1 ) or (PF2) by reaction with suitable reaction partners according to methods known in the art. For example, convenient polymers (PF1 ) can be obtained by reaction of an amine(Pp2-A) with an aromatic

polycarboxylic acid or a derivative thereof able to form amido bonds, for example with trimellitic acid or a derivative thereof, such as trimellitic anhydride. Good results were obtained using a polymer (PF1 ) obtained by reacting an amine (PF2-A) of formula (RF-I I I)-(CF2CH ₂ N H2)2 with trimellitic anhydride.

[0077] A further example of polymer which can be obtained from a PFPE diol (DF1 ) is a polymer (PF1 ) complying with formula (PF1 -B):

(PF1 -B) (R _F -l)-[CFXCH2(OCH2CH2)nDOCH ₂ COOH]2

wherein (RF-I), X and nD are as defined above

by reaction of diol (DF1 ) with an ester of a 2-halo-acetic acid, for example with 2-chloroethyl acetate. The reaction can be conveniently carried out as disclosed in US 7252740.

[0078] Polymer (PF1 -B) can be used as such in the manufacture of

compositions (C) or it can in turn be used as precursor for the

manufacture of other polymers (PF1 ) and (PF2).

[0079] Further convenient polymers (PF1 ) for the preparation of compositions (C) are those complying with the following formulae (PF1 -C) and (PF1 -D) here below:

(PF1 -C) (RF-l)-[CFXCH2(OCH ₂ CH2)nDOC(O)-RBi-COOH]2

(P _F 1 -D) (RF-l)-[CFXCH2(OCH ₂ CH2)nDNHC(O)-RBi-COOH]2

wherein RF-I , X and nD are as defined above and RBI is C1-C10 straight or branched alkylene, C ₄ -C6 cyloalkylene as defined above or C5-C6 arylene as defined above, optionally comprising one or more -COOH groups. Preferably, chain (RF-I) is a chain (RF-I I I) as defined above, X is F, nD is 0 or ranges from 1 to 5 and RBI is selected from 0-, m-, p- cyclohexylene and 0-, m-, p-phenylene. Polymers (PF1 -C) and (PF1 -D) can be obtained from diols (D _F 1 -A), (D _F 1 -B) and from (PF2-A) by reaction with a diacid of formula HOOC-RBI -COOH wherein RBI is as defined above or with a reactive derivative thereof, like a halide or an anhydride. [0080] A convenient example of compound (PF1 -C) complies with formula (PF1 -Ca) here below:

(P _F 1 -Ca)

[0081] A convenient example of polymer (PF1 -D) complies with formula (PF1 Da) here below:

(P _F 1 -Da)

[0082] Further convenient examples of polymers (P2) for the preparation of compositions (C) are those complying with the following formulae (PF2- B) and (P _F 2-C)

(P _F 2-B) (RF-l)-[CFXCH2(OCH ₂ CH2)nDOC(O)-RBi-N(Rp2)2]2

wherein RF-I , X, nD and N(RP2)2 and RBI are as defined above.

(P _F 2-C) (RF-l)-[CFXCH2(OCH ₂ CH2)nDOC(O)NH-RB2NHC(O)ORB3- N(R _P2 ) ₂

wherein RF-I , X, nD and Rp2 are as defined above, RB2 is straight or branched C1-C6 alkylene chain optionally comprising a C ₄ -C6 cyloalkylene group as defined above or a C5-C6 arylene group as defined above and RB3 is C2-C10 straight or branched alkylene, optionally interrupted by one or more -N(RP2*)- groups as defined above.

[0083] Polymers (P _F 2-B) can be obtained by reaction of a diol (D _F 1-A) or (D _F 1 - B) with an amidoacid or with a reactive derivative thereof, such as an halide or anhydride.

[0084] Polymers (PF2-C) can be obtained by reaction of a diol (D _F 1-A) or (D _F 1 -

B) with a diisocyanate and an aminoalcohol.

[0085] Convenient examples of polymers (PF2-C) comply with the formulae

(P _F 2-Ca) and (P _F 2-Cb) here below:

[0086]

Polymers (P1) and (P2) wherein chain (R) is a chain (Rs) [herein after polymers (Ps1) and (Ps-2)]

[0087] Polymers (Ps1 ) and (Ps2) are available on the market, or can be

obtained according to methods known in the art. In particular, polymers (Ps1 ) and (Ps2) wherein Ra _s and Rb _s are both methyl can be obtained by hydrolysis of dimethyl chlorosilane to provide a dihydroxy-terminated poly(dimethylsiloxane) and derivatization of the same according to methods known in the art for the manufacture of amines and acids.

[0088] A convenient example of polymer (Ps2) is a polydimethyl siloxane of formula (Ps2-A) here below:

(Ps2-A) H2N(CH2)ns*Si(CH3)2O[Si(CH3)2O]nsSi(CH ₃ )2(CH2)ns*NH2 in which ns is a positive number selected in such a way that the number average molecular weight (M _n ) of the [Si(CH3)2O] _ns chain ranges from 500 to 10,000, preferably from 500 to 5,000 and ns* is 0 or a positive number equal to or higher than 1 , preferably ranging from 1 to 10. A polymer (Ps2-A) wherein ns* is 3 is available from Aldrich®.

[0089] Polymer (Ps2-A) can be used as such in the manufacture of

compositions (C) or can be used as precursor for the manufacture of other polymers (Ps1 ) and (Ps2). For instance, convenient polymers (Ps1 ) complying with the following formula (Ps1 -A) here below: (Ps1 -A) Rs-[(CH ₂ )ns*N HC(O)- R _B i-COOH] ₂

wherein ns* and RBI are as defined above and Rs is a chain of formula Si(CH3)2O[Si(CH3)2O]nsSi(CH3)2 can be obtained by reaction of polymer (Ps2-A) with an acid of formula HOOC-RBI -COOH, wherein RBI is as defined above, or with a reactive derivative thereof, such as an halide or anhydride.

[0090] A convenient example of polymer (Ps1 -A) is one complying with formula (Ps1 -Aa) here below:

Ps1 -Aa)

[0091 ]

wherein Rs is a chain (Rs-I).

[0092] A further convenient example of polymer (Ps1 ) is a polymer complying with formula (Ps1 -B):

(Ps1 -B) Rs-[(CH ₂ )ns*OC(O)- R _B i-COOH] ₂

wherein ns* and RBI are as defined above and Rs is a chain of formula Si(CH3)2O[Si(CH ₃ )2O]nsSi(CH ₃ )2.

Polymer (Ps1 -B) can be obtained by reaction of a dihydroxy-terminated silane precursor of formula:

HO(CH2)ns*Si(CH3)2O[Si(CH3)2O]nsSi(CH ₃ )2(CH2)ns*OH

by reaction with an acid of formula HOOC- RBI-COOH, wherein RBI is as defined above, or with a reactive derivative thereof, such as an halide or anhydride.

Polymers (P1) and (P2) wherein chain (R) is a chain (ROA) [herein after polymers

[0093] Polymers (P 1OA) and (P2OA) are available on the market or can be

obtained according to methods known in the art . Preferred examples of polymers (P 1OA) and (P2OA) are those comprising a polyoxyethylene chain, a polyoxypropylene chain or a polytetramethylene glycole chain.

[0094] For example, starting from a polyoxyalkylene diol of formula (DOA1 ):

(DOA1 ) H-(OR*OAVOA-OH

wherein R*OA is a straight or branched alkylene chain, typically an ethylene, propylene or a tetramethylene chain, and Π*ΟΑ is an integer selected in such a way as the number average molecular way ranges from 500 to 5,000, polymers (POA1 ) and (POA2) can be obtained by methods know in in the art by reaction with suitable reaction partners. A diol (DOA-1 ) wherein R*OA is an ethylene chain is commercially available from Aldrich ^® .

[0095] For example, polymers (P1 OA) complying with formula (P1 OA-A):

wherein RBI , R ^* oA and Π*ΟΑ are as defined above, can be obtained by reaction of a diol (DOA1 ) with a halo-alkyl or haloalkylene acid X°-RBI- COOH wherein X° iis halogen and RBI is as defined above or with a corresponding halide or ester. For example, a polymer (P1 OA-A) wherein RBI is -Chb- can be obtained by reaction of diol (DOA1 ) with a 2- halo acetic acid or halide or ester thereof, such as with 2-chloroacetic acid ethyl ester. A polymer (P1 OA-A) wherein R*OA is an ethylene chain and RBI is -Chb- is available from Aldrich ^® .

[0096] Polymers (P1 OA) complying with formula (P1 OA-B)

(P1 oA-B) HOOC-RBI- C(O)-(OR ^* oA) _n *oA-O-C(O)R _B i-COOH can be obtained by reaction of a diol (DOA-1 ) with a diacid of formula HOC(O)-RBI-COOH, wherein RBI is as defined above, or with a reactive derivative thereof, such as an halide or anhydride.

[0097] Polymers (P2OA) complying with formula (P2OA-A):

wherein R*OA and n*ΟΑ are as defined above

can be obtained from a diol (DOA1 ) by conventional reactions for the replacement of the hydroxyl group into an amino group. A polymer (P2OA-A) wherein R*OA IS ethylene is available on the market from Aldrich ^® .

Polymers (P1) and (P2) wherein chain (R) is a chain (Rpc) [herein after polymers

[0098] Polymers (Pipe) and (P2PC) can be manufactured by reaction of a diol of formula (D° _PC 1 ):

(D°PC1 ) HO-(R°PC)-OH wherein (R° _PC ) is a straight or branched alkylene chain, preferably a C2 - C10 alkylene chain, optionally comprising ethereal oxygen atoms and a carbonate, typically diphenylcarbonate,

to provide a dihydroxy-terminated polycarbonate of formula (DPC1 ):

(DPC1 ) H-[O-R ⁰ Pc-OC(O)]nPc-iO-R°Pc-OH

wherein R°PC and npc are as defined above

which is subsequently reacted with suitable reaction partners according to methods known in the art to provide polymers (P1 pc) and (P2 PC).

[0099] Dihydroxy-terminated polycarbonates (DPC1) having an average number molecular weight (M _n ) ranging from 500 to 3,000 are commercially available, for example, from UBE as Ethernacoll ^® PH.

[00100] For example, convenient polymers (Pi pe) can be obtained by reaction of (DPC1 ) with a halo-alkyl or haloalkylene acid ester, preferably with an acid of formula X°-RBI-COOH wherein X° is halogen and RBI is as defined above, or an ester thereof, for example with 2-chloro acetic acid ethyl ester.

[00101] Further convenient polymers (Pi pe) [polymers (P1 PC-B)] can be

manufactured by reaction of diol (DPC1 ) with an acid of formula HOOC- RBI-COOH wherein RBI is as defined above, or with a reactive derivative thereof, such as a halide or an anhydride.

[00102] Convenient polymers (P2PC) complying with formula (P2PC-A):

wherein RP2, R°PC and npc are as defined above

can be manufactured from diol (D°PC1 ) by converting the terminal hydroxyl groups into amino groups according to methods known in the art.

[00103] Polymers (P2PC-A) wherein at least one of Rp2 is hydrogen can be used as precursors of further polymers (Pi pe) and (P2PC). For example, polymers of formula (P1 pc-C):

can be obtained by reaction with a diacid of formula HOOC- RBI-COOH wherein RBI is as defined above or with a reactive derivative thereof, such as a halide or anhydride. Polymers (P1) and (P2) wherein chain (R) is a chain (RPE) [herein after polymers

(P1PE) and (P2 _PE )"

[00104] Polymers (P1PE) and (P2PE) can be prepared according to methods known in the art starting from a polyester diol [diol (DPE1 )]. Diols (DPE1 ) can be obtained by polycondensation of dicarboxylic acids or lactams and diols. Polyester diols are commercially available; for example, polycaprolactone diols are available from Perstop under the tradename Capa™. Convenient polymers (P1 PE) can be obtained by reaction of a diol (DPE1 ) with a halo-alkyl or haloalkylene acid ester, preferably with an acid of formula X°-RBI-COOH wherein X° is halogen and RBI is as defined above, or an ester thereof, for example with 2-chloro acetic acid ethyl ester. Further convenient polymers (PPE1 ) can be obtained by reaction of a diol (DPE1 ) with an acid of formula HOOC- RBI-COOH wherein RBI is as defined above, or with a reactive derivative thereof, such as a halide or anhydride

[00105] Polymers (PPE2) with -N(RP2)2 end groups can be obtained from diols (DPE1 ) according to methods known in the art for the replacement of the hydroxyl group with an amino group. Polymers (PPE2) thereby obtained can be in turn used as precursors for other polymers (PPE1 ) or (PPE2) by reaction with suitable precursors according to methods known in the art.

Polymers (P1) and (P2) wherein chain (R) is a polybutadiene chain (RPBD) [herein after "polymers (PPBD 1) and (PPBD2)"]

[00106] Polymers (PPBD1 ) and (PPBD2) can be obtained from dihydroxy

terminated polybutadienes according to methods disclosed in the art. Such polybutadienes are available, for example, from Cray Valley; one of them is marketed as Poly bd ^® R-45HTLO.

[00107] Convenient polymers (PPBD1 ) can be obtained by reaction of a

dihydroxy terminated polybutadiene [diol (DPBDI)] with a halo-alkyl or haloalkylene acid ester, preferably with an acid of formula X°-RBI- COOH wherein X° is halogen and RBI is as defined above, or an ester thereof, for example with 2-chloro acetic acid ethyl ester. Further convenient polymers (PPBD1 ) can be obtained by reaction of a dihydroxy terminated polybutadiene with an acid of formula HOOC- RBI-COOH wherein RBI is as defined above, or a reactive derivative thereof.

[00108] Polymers (PPBD2) with -N(RP2)2 end groups can be obtained from a dihydroxy terminated polybutadiene (DPBDI) according to methods known in the art for the replacement of the hydroxyl groups with an amino group. Polymers (PPBD2) thereby obtained can be in turn used as precursors for other polymers (PPBD1 ) or (PPBD2) by reaction with suitable precursors according to methods known in the art.

Composition (C) and its manufacture

[00109] Composition (C) for carrying out method (M) can be prepared by mixing a polymer (P1 ) and a polymer (P2) according to conventional mixing techniques at an equivalent ratio between polymer (P1) and polymer (P2) ranging from 1.1 to 0.9. Mixing can be carried out with or without solvents, using appropriate mixing equipment.

[00110] One or more polymers (P1 ) can be used in the manufacture of

composition (C). "More polymers" means that polymers (P1 ) can be used which can differ from one another in the kind of units (U) of chain (R), in the kind of end groups (E1 ) and (Ε1 ') or both.

[001 1 1] One or more polymers (P2) can also be used in the manufacture of composition (C). "More polymers" means that polymers (P2) can differ from one another in the kind of chain (R), in the kind of end groups (E2) and (Ε2') or both.

[001 12] According to a preferred embodiment, one polymer (P1 ) and one

polymer (P2) are used in the manufacture of composition (C); chains (R) of polymer (P1 ) can be the same or different from chain (R) of polymer (P2).

According to one embodiment, chain (R) in either (P1 ) or (P2) is a chain (RF) as defined above, preferably a chain of formula (RF-I) as defined above, more preferably a chain of formula (RFI-I I I) as defined above, while chain (R) in the other polymer is a chain (Rs) as defined above, preferably a chain (Rs-I) as defined above. [001 13] According to another embodiment, chain (R) is the same in the polymers (P1 ) and (P2).

[001 14] Convenient compositions (C) for carrying out method (M) comprise a polymer (P1 ) and a polymer (P2) wherein, in both polymers, chains (R) is a (per)fluoropolyether chain (RF) as defined above, preferably a chain of formula (RF-I) as defined above, more preferably a chain of formula (RFI-I I I) as defined above.

[001 15] Further convenient compositions for carrying out method (M) comprise a polymer (P1 ) and a polymer (P2) wherein chain (R) is a

polyalkylsiloxane chain (Rs) as defined above, preferably a

polydimethylsiloxane chain.

[001 16] Compositions (C) per se represent a further embodiment of the

invention, with the exception of those comprising a polymer (P1) and a polymer (P2) wherein, in both polymers, chain (R) is a

(per)fluoropolyether chain (RF) as defined above.

[001 17] Composition (C) may further comprise one or more organic polar protic or aprotic solvents. Non limiting examples of solvents are alcohols, ketones, acetates, dimethylacetamide (DMA) and hydrofluoroethers. Preferred organic solvents are ketones, like methylethylketone (MEK) and acetates, like ethylacetate and butyl acetate).

[001 18] When present, the one or more organic solvent is comprised in

compositions (C) in an amount ranging from 1 % to 99.9%wt with respect to the overall weight of the composition. The amount of solvent will be selected by the person skilled in the art according to the thickness of the coating (or film) obtained from the composition, being understood that the higher the amount of solvent, the lower the thickness of the film obtainable therefrom.

[001 19] Without being bound to theory, it is believed that when a polymer (P1 ) and a polymer (P2) are mixed in the above equivalent ratio the at least one ionisable acid group at each end of polymer (P1) undergo acid/base reaction with the at least one ionisable amino group at each end of polymer (P2). It will thus be understood by a person skilled in the art that any optional ingredient in composition (C) will have to be selected in such a way and amount that it does salify the ionisable acid and amino groups of polymers (P1 ) and (P2).

Method (M) and articles (A) coated with composition (C)

[00120] Method (M) can be carried out by applying composition (C) to a metal article or a part thereof, according to conventional techniques. For example, composition (C) can be applied by casting composition (C) and drying or evaporating of any solvent upon heating, or can be applied by means of a dip-coater followed and drying or evaporation of any solvent upon heating. Composition (C) can also be applied by spray coating.

[00121] Metal articles obtained by method (M) represent a further aspect of the present invention.

[00122] As intended herein "a metal article" is an article consisting of a metal or a metal alloy, without limitation in its dimension and shape. For the sake of clarity, magnetic means are not metallic articles for the purpose of the present application.

[00123] Films of composition (C) may have a thickness ranging from 0.1 to 100 μηη.

[00124] Non limiting examples of metal articles which can be coated with

composition (C) are metallic articles used in architecture, industrial plants, in the automotive industry.

[00125] In one preferred embodiment, a metal article is an article made of iron, zinc, nickel and alloys thereof.

[00126] Metal articles coated with compositions (C) showed highly resistant to corrosion. Without being bound to theory, it is believed that this high resistance is due to the high viscosity of compositions (C), which is significantly higher than the sum of the viscosities of polymers (P1 ) and (P2).

[00127] The inventions is described in greater detail in the following

experimental section by means of non-limiting examples. [00128] 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 and methods

Materials

[00129] Isophorone diisocyanate (IPDI), dibutyltindilaurate (DBTDL), 1 ,4- diazabicyclo[2.2.2]octane (DABCO); Fascat 4100 ^® (Butyltin hydroxide oxide hydrate); methy-ethylketone (MEK), hexafluoroxylene (HFX), 2- ((2-(dimethylamino)ethyl)methylamino)ethanol (DMEMAE); Ν,Ν'- dimethyl-ethanolamine (DMEA), hexahydrophthalic anhydride, trimellitic anhydride, adipic acid, ethyl chloroacetate, 2-propanol (IPA) were purchased from Aldrich ^® and used as received.

[00130] Fomblin ^® ZDOL PFPE: HOCH2CF2(OCF2CF2O)ai(CF2O)a2CF2CH ₂ OH (a1/a2 =2.0; M _n 2000) and

Fomblin ZDOL TX ^® PFPE:

HO(CH2CH2O)nDCH2CF2(OCF2CF2O)al(CF2O)a2CF2CH2(OCH ₂ CH2)nDO

H (nD=1 ,5; M _n 1 ,500)

are available from Solvay Specialty Polymers.

[00131] Fomblin ^® diamine [herein after (P2-Ex7)]

NH2CH2CF2(OCF2CF2O)ai(CF2O)a2CF2CH ₂ NH2 (nD=1.5; M _n 2,500) was prepared following the procedure disclosed in US 6984759 B

(SOLVAY SOLEXIS SPA)

[00132] Hydrofluoroether Novec ^® HFE 7500 was purchased from 3M and was used as received.

[00133] Poly(dimethylsiloxane), bis(3-aminopropyl) terminated (M _n 2500) [herein after (P2-Ex8)] was purchased from Aldrich ^® and was used as received.

Methods

[00134] Analytical procedure for the titration of acid polymers (P1 ) (direct

acid/base titration) [00135] Sample: 1 - 3 g (exactly weighed)

Solvent: HFX/IPA 50 /10 ml

Titrating agent: tetramethylammonium hydroxide TMAI 0.1 M in CH3OH Electrode: DG1 15SC Mettler Toledo

[00136] Analytical procedure for basic polymers (P2) (direct acid/base titration) Sample: 1 -3 g (exactly weighed)

Solvent: HFX/IPA 50 /10 ml

Titrating agent: HCI 0.1 M in IPA

Electrode: DG1 15SC Mettler Toledo

Viscosity

[00140] Corrosion tests were performed on treated and untreated metal

samples immersed in sea water at room temperature for 72h (or for a different time when indicated) according to ASTM D 1 141 -98, with the exception that the following sea water composition was used:

[00141] The test was performed on iron and stainless steel samples with two different thicknesses (> 30 microns and < 1 micron, respectively).

[00142] Visual inspection was carried out after 72 hrs immersion.

Synthesis examples

Exam le 1 - Synthesis of a olymer (PF2) of formula:

containing 0.74 eq/kg of amino groups starting from Fomblin ^® Z DOL PFPE M, 2000 [herein after (P _F 2)-Ex1]

- Synthesis of a diisocyanate compound of formula:

[00143] A glass reactor was charged with IPDI (50 g, 450 meq), Fomblin ZDOL ^® PFPE (1 12.8 g, 1 10 meq, containing 5 % on a molar base of monofunctional PFPE alcohol). The reaction mass was warmed up to 50°C, under mechanical stirring, then dibutyltin dilaurate (DBTDL, 0.43 ml, 5% w/w solution in MEK) was added; a spontaneous increase of the internal temperature to 55°C was observed. Thereafter, the temperature was increased to 65°C and kept at this value for two hours. The completion of the reaction was monitored by ¹⁹ F-NMR. The excess of IPDI was removed by washing with n-hexane, separation of the bottom fluorinated layer and removal from this layer of the trace of residual solvent by vacuum distillation at 80°C.

Step 2: reaction with Ν,Ν'- dimethyl-ethanolamine

[00144] 120 g (98 meq) of the diisocyanate compound prepared in the first step was charged in a reactor under mechanical stirring, heated at 50°C and then dibutyltindilaurate (DBTDL) (0.43 ml, 5% w/w solution in MEK) was added. A solution of Ν,Ν'- dimethyl-ethanolamine (DMEA, 9.0 g, 100 meq), in MEK (30ml) was added dropwise. Then the temperature was increased again to 65°C and the completion of the reaction was monitored by IR, until disappearance of the typical -NCO band (2270 cm- ¹ ). The organic phase then was dried and the title polyurethane was obtained (125 g). The amine content, measured by titration according to the procedure disclosed in the Methods section, was 0.74 eq/kg; the result of this analysis was in accordance with the ¹ H-NMR and GPC analyses and confirmed the obtainment of the target product (I) with 95% purity.

Example 2 - Synthesis of a olymer (PF2) of formula:

containing 1,44 eq/Kg of amino groups, starting from Fomblin ^® Z DOL PFPE M _n 2000 [herein after (P _F 2-Ex2)]

[00145] This polymer was prepared following the same as in Example 1 , using the reagents and solvents indicated below:

- IPDI (45 g, 400 meq);

- Fomblin ZDOL ^® PFPE (102.6 g, 100 meq, containing 5% on a molar basis of monofunctional PFPE alcohol);

- MEK (30 g);

- dibutyltin dilaurate (DBTDL, 0.39 ml, 5% solution in AcOEt);

- 2-((2-(dimethylamino)ethyl)methylamino)ethanol (DMEMAE, 14.9 g, 102 meq) [00146] The content of amino groups (measured by titration according to the procedure disclosed in the Methods section) was 1.44 eq/Kg. The result of this analysis was in accordance with the ¹ H-NMR and GPC analyses and confirmed the obtainment of the target product, with 95% purity.

[00147] The M _n determined by ¹ H and ¹⁹ F-NMR was 2,830.

Exam le 3 - Synthesis of a polymer (PF1) of formula:

containing 1. 10 eq/kg of acid groups [herein after (PF1-EX3), starting from

Fomblin ^® Z DOL TX PFPE M _n 1500 (B)

[00148] A glass reactor was charged with Fomblin ZDOL TX ^® PFPE (103.1 g, 133 meq, with 6% on a molar base of monofunctional PFPE alcohol) and was warmed up to 70°C, under mechanical stirring, and dried under vacuum for 2 hours. Hexahydro-phthalic anhydride (21.3 g, 135 meq) was melt at 40°C and was added in the glass reactor with Fascat 4100 ^® butyltin hydroxide oxide hydrate. The reaction mass was warmed up to 130°C and kept at this value for two hours. The completion of the reaction was monitored by ¹ H-NMR. The acid content, measured by titration as described in the Methods section, was 1.10 eq/kg. All analyses confirmed the obtainment of the target product.

[00149] The M _n of this polymer (PF1 ) determined by NMR analyses was 1 ,760 (Ew 900) and its purity was 94%.

Example 4 -Synthesis of a polymer (PF1) of formula:

containing 0.94 eq/kg of acid groups [herein after (PF1-EX4)], starting from

Fomblin ^® Z DOL PFPE M _n 2000

[00150] This polymer (P1 ) was prepared from Fomblin ZDOL ^® PFPE following the procedure described in Example 2 of US 7252740. NMR analyses confirmed the obtainment of a the target product. The Mn of this polymer (PF1 ) determined by NMR analyses was 1 ,950 (Ew 1063) and its purity was 95%.

Example 5 - Synthesis of a polymer (Ps1) of formula:

wherein Rs is a chain (Rs-I)

[herein after after (Ps1-Ex5)] containing 1. 19 eq/kg of acid groups

[00151] A glass reactor was charged with 20 g (13 meq) poly(dimethylsiloxane), bis(3-aminopropyl) terminated (M _n 3,000) and was warmed up to 70°C, under mechanical stirring, and dried under vacuum for two hours.

Trimellitic anhydride (3.0g 15 meq) was melt at 40°C and was added in the glass reactor. The reaction mass was warmed up to 130°C and kept at this temperature for two hours. The completion of the reaction was monitored by ¹ H-NMR. The acid content, measured by titration according to the procedure described in the Methods section, was 1.19 eq/kg. All analyses confirmed the obtainment of the title product, with a purity higher than 98% and M _n 3,350.

Example 6 - Synthesis of a polymer (PF1) of formula:

containing 1.38 eq/kg of acid groups [herein after (PF1-EX6)]

[00152] A glass reactor was charged with Fomblin ^® diamine (30 g, 24 meq) and was warmed up to 70°C, under mechanical stirring, and dried under vacuum for two hours. Trimellitic anhydride was melt at 40°C and was added (4.9 g 25 meq) in the glass reactor. The reaction mass was warmed up to 130°C and kept at this temperature for two hours. The completion of the reaction was monitored by ¹ H-NMR. The acid content, measured by titration as described in the Methods section, was 1 .38 eq/kg. All analysesconformed the obtainment of the title product with a purity higher than 97% and M _n 2,900.

Preparation and properties of the compositions of the invention

[00153] All compositions were prepared by mixing at 50°C in a reactor equipped with a mechanical stirrer, a polymer (P1 ) and a polymer (P2) at an equivalent ratio of 1 [i.e. nr acidic groups of polymer (P1 ) = nr basic groups of polymer (P2)].

Table 1 below reports the eq/kg of each polymer and their respective viscosities.

Table 2 below reports the ingredients of the compositions and their viscosity.

Table 3 below compares the actual viscosity value of the compositions with the theoretical values. Theoretical viscosity vas calculated as average of the viscosities of the single polymers, taking into account their reciprocal volume fractions in the composition, according to the following calculation:

Theorethical viscosity = [Viscosity of (P1 ) x volume fraction of (P1 ) in the composition + viscosity of (P2) x volume fraction of (P2) in the composition]/2

When indicated in the Tables, 5% w/w of propylene

glycolmethyletheracetate (PMA) was added.

[00154] The viscosity of the compositions was measured one week after their preparation.

Table 1

[00155]* = 5%w/w PMA

Table 2

Table 3

[00157] The results reported in Table 3 demonstrate that the compositions of the invention have an experimental viscosity higher than the calculated theoretical viscosity.

Anticorrosion tests

Comparative corrosion test

[00158] An untreated iron slab was immersed in sea water at room temperature according to the standard procedure described above. After 5 hours, start of corrosion (formation of red iron oxides on the surface) was observed by visual inspection; corrosion reached a maximum after 24 hours.

Corrosion test 1

[00159] Composition (C-3) was added with a mixture of HFE 7500 and IPA at a 10: 1 volume ratio until reaching a solid content of 90% wt (90% wt polymers with respect to the overall weight of the composition). The resulting composition was cast on an iron slab and the solvents were evaporated at 80-100°C for 3 hours. The thickness of the coating was about 50 microns.

[00160] The coated iron slab was immersed in sea water for 72 hours. No

corrosion was observed.

Corrosion test 2

[00161 ] Composition (C-3) was added with a mixture of Novec® HFE 7500 and IPA at a 10: 1 volume ratio until reaching a solid content of 1 % wt (1 % wt polymers with respect to the overall weight of the composition).

[00162] The resulting composition was applied by dipping with a dip-coater onto an iron slab and the solvents were evaporated at 80-100°C for 3 hours. The thickness of the coating was lower than 1 micron.

[00163] The coated iron slab was immersed in sea water for 72 hours. No

corrosion was observed.

Corrosion test 3 [00164] Composition (C-5) was added with a mixture of HFE 7500 and IPA at a 10: 1 volume ratio until reaching a solid content of 80% wt. The resulting composition was cast on an iron slab and the solvents were evaporated at 80-100°C for 3 hours. The thickness of the coating was about 40 microns.

[00165] The coated iron slab was immersed in sea water for 200 hours. No

corrosion was observed.

Corrosion test 4

[00166] Composition (C-5) was dissolved in MEK until reaching a solid content of 1 % wt and applied by dipping with a dip-coated onto an iron slab; the solvent was evaporated at 80-100°C for 3 hours. The thickness of the coating was lower than 1 micron.

[00167] The coated iron slab was immersed in sea water and no corrosion was observed after 24 hours.

[00168]

Corrosion test 5

[00169] Test 4 was repeated with the difference that the solid content of the composition dissolved in MEK was 0.1 %wt.

[00170] No corrosion was observed after immersion in sea water for 24 hours.

[00171 ] The results reported in the corrosion tests show that effective protection of corrosion can be achieved with films of compositions (C) lower than 1 μηη.