Patent Application
20140243547
This application claims priority to European patent application No. 11183716.7 filed on Oct. 3, 2011, the whole content of which is incorporated herein by reference for all purposes.
The present invention relates to fluoropolyethers, in particular to linear (per)fluoropolyethers having functionalised end groups and to a process for preparing them.
Linear (per)fluoropolyethers containing —CF2O—, —CF2CF2O—, —CF2CF2CF2O— and —CF2CF2CF2CF2O— units randomly distributed along the polymer chain are characterised by a lower glass transition temperature (Tg) than that of (per)fluoropolyethers containing also branched —CF(CF3)— or —CF2CF(CF3)— units, having pendant perfluoroalkyl groups. In particular, linear (per)fluoropolyethers containing, or essentially consisting of, —CF2O— and —CF2CF2O— units are particularly flexible and are endowed with a Tg usually lower than −90° C., due to the presence of the —CF2O— units.
Linear (per)fluoropolyethers containing —CF2O— and —CF2CF2O— units are conveniently obtained by photopolymerization of tetrafluoroethylene in the presence of oxygen, followed by reduction of the peroxy groups present in the resulting polymer; this process leads to linear functionalised (per)fluoropolyethers containing —CF2COF end groups, which can be converted into further functionalised (per)fluoropolyethers according to reactions known in the art. In these further functionalised (per)fluoropolyethers, a functional group is linked to the (per)fluoropolyether chain through a —CF2— moiety. Usually, these further functionalised (per)fluoropolyether are endowed with good chemical resistance; however, it has been observed that, under severe conditions, derivatives like esters or amides undergo hydrolysis.
U.S. Pat. No. 4,115,367 (US AIR FORCE) 19 Ser. 1978 and U.S. Pat. No. 4,064,109 (US AIR FORCE) 20 Dec. 1977 disclose thermooxidatively and hydrolytically stable perfluoroalkylether bisbenzoxazole polymers containing a perfluoroalkyl ether chain and benzoxazole end groups, wherein the benzoxazole end groups are linked to the perfluoroalkyl ether chain through —CF(CF3)— units; however, the polymers disclosed in U.S. Pat. No. 4,115,367 contain a perfluoroalkylether chain that does not comprise —CF2O— units, while the polymers disclosed in U.S. Pat. No. 4,064,109 contain a perfluoroalkylether chain containing —(CF)CF3— units. Accordingly, these compounds have a Tg higher than that of linear (per)fluoropolyethers containing —CF2O— units.
It is also noted that functionalised (per)fluoropolyethers in which functional end groups are linked to the (per)fluoropolyether chain through —CF(CF3)— moieties can be prepared by addition of hexafluoropropylene oxide (HFPO) to (per)fluoropolyethers containing —COF end groups in the presence of suitable initiators; however, yields are poor, due to the fact that HFPO undergoes oligomerization, giving rise to mixtures of mono- or polyaddition products, i.e. products containing one or more HFPO or units at each end of the polymer chain these mixtures are difficult to separate. For instance, US 2004116742 (3M INNOVATIVE PROPERTIES CO) 17 Jun. 2004 discloses a process for preparing linear fluorinated compounds, including (per)fluoropolyether compounds having a —CF(CF3) COF terminal group, by reaction of HFPO with a precursor having a —COF terminal group; however, also this process, which is carried out in the presence of a fluoride salt as catalyst and a polar solvent and which makes use of an excess of at least 10% precursor, affords poor yields, as it leads to a mixture that contains, in addition to a product containing one HFPO unit, products containing more HFPO units and a significant amount of unreacted precursor. In fact, US 2004116742 discloses only the separation of a monoaddition product obtained from a precursor of formula CF3—O—CF2CF2COF and does not specifically disclose the preparation of (per)fluoropolyethers comprising a linear (per)fluoropolyether chain having two chain ends, each chain end comprising one HFPE end group.
U.S. Pat. No. 4,053,498 (US AIR FORCE) 11 Oct. 1977, which relates to perfluoroalkylene ether-imidate and thioimidate esters, teaches to prepare diacyl fluorides of formula FOCF(CF3)[OCF2CF(CF3)]mO(CF2)5[CF(CF3) CF2O]nCF(CF3)COF, wherein m+n is 4 or 5, by reaction of exafluoroglutaryl fluoride, in the presence of CsF as catalyst and tetraglyme as solvent, according to what disclosed in U.S. Pat. No. 3,250,807 (DU PONT). According to this patent, acyl fluorides of formula:
FOC—R′f—O[CF(CF3)CF2O]nCF(CF3)COF and FOCCF(CF3)[OCF2CF(CF3)]mOCF2R′fCF2O[CF(CF3)CF2O]pCF(CF3)COF
wherein R′f is a perlfluoroalkylene radical of 1 to 20 carbon atoms, n is a number from 0 to 35 inclusive and m and p are numbers whose sum is from 0 to 35 inclusive are prepared by reaction of mono- or diacyl fluorides with HFPO in a polar organic solvent, using a fluoride salt as catalyst in an amount which is at least 0.01% by weight of the HFPO, at temperatures ranging from −80° C. to 200° C. This patent teaches that the degree of polymerization depends on various factors, namely the catalyst, the temperature and the acid fluoride/HFPO ratio; in particular, it teaches that a lower degree of polymerization is obtained at the low end of the temperature range and that the monoaddition product is obtained when the acid fluoride/HFPO ratio is one or greater than one. Nevertheless, it also states that the control on the amount of HFPO units inserted is not absolute and that products with higher or lower molecular weight can also be obtained.
U.S. Pat. No. 3,311,658 (DU PONT DE NEMOURS AND CO.) discloses omega-iodofluorocarbon ether acid fluorides of formula:
I(CF2)n+1—O—[CF2CF2O]p+1—[CF(CF3)CF2O]m—CF(CF3)C(O)F
wherein n is an integer from 1 to 8 inclusive, m is an integer from 1 to 5 inclusive and p is an integer from 1 to 5 inclusive. Such compounds are said to be capable of being converted into vinyl ethers which can in turn be copolymerized to provide fluorocarbon resins that can be cross-linked. The ethers alone are said to be useful as dispersing agents (col. 4, lines 34-37).
JP 2001207183 (MATSUSHITA ELECTRIC CO LTD) discloses a lubricant composition for magnetic recording media which comprises linear PFPE derivatives, among them PFPE carboxylic derivatives; however, such derivatives do not have carboxylic end groups bound to —CF(CF3)— moieties.
There is therefore the need to provide (per)fluoropolyethers that are endowed with both low Tg and high chemical resistance and that can be prepared according to a convenient process, which allows to control the number of HFPO units inserted at the polymer end(s).
The present invention relates to mono- or bi-functional (per)fluoropolyethers comprising a linear (per)fluoropolyether chain having two ends, wherein one or two ends contain —CF(CF3)COF groups, to a process for preparing them and to their use as precursors in the preparation of further functionalised (per)fluoropolyethers. The invention also relates to these further functionalised (per)fluoropolyethers.
For the purposes of the present invention, the term “(per)fluoropolyether” means a (per)fluoropolymer containing a (per)fluoropolyether chain, i.e. a fully or partially fluorinated polyoxylakylene chain [herein after also referred to as (Rf) chain] which comprises, preferably consists of, recurring units having at least one catenary ether bond and at least one fluorocarbon moiety.
The (per)fluoropolyethers according to the present invention contain a linear (per)fluoropolyoxyalkylene chain (Rf) comprising, preferably consisting of, repeating units R°, randomly distributed along the (per)fluoropolyoxyalkylene chain, selected from the group consisting of:
(i) —CF2O—;
(ii) —CF2CF2O—;
(iii) —CF2CF2CF2O—;
(iv) —CF2CF2CF2CF2O—.
Preferably, the Rf chain contains, preferably consists of, both —CF2O— and —CF2CF2O— units.
For the avoidance of doubt, in the present description, the term (per)fluoropolyether indicates a fully or partially fluorinated polyether and the acronym “PFPE” stands for (per)fluoropolyether as defined hereinabove.
Typically, the mono- or bifunctional (per)fluoropolyethers having —CF(CF3) COF end groups according to the present invention comply with formula (I) below:
X—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—COF (I)
wherein:
Preferably, chain Rf complies with formula: (CF2O)n(CF2CF2O)m, in which m and n are 0 or integers equal to or higher than 1, preferably ranging from 1 to 4 and preferably selected in such a way that the number average molecular weight ranges from 400 to 10,000, preferably from 600 to 5,000, with the proviso that at least one of m and n is other than 0; preferably, m and n are other than 0 and the m/n ratio ranges from 0.1 to 10, preferably from 0.2 to 5, more preferably from 0.1 to 2.5.
In a first preferred embodiment, x is 0. In a second preferred embodiment, x is an integer equal to or higher than 1; for example, x may range from 1 to 100, preferably, from 1 to 50, more preferably from 1 to 20, even more preferably from 1 to 5.
The compounds of formula (I) in which x is 0 can be prepared by reaction of a compound (herein after also referred to as acyl precursor) of formula (II):
X1—O—Rf—CF2COF (II)
in which:
It has indeed been observed that, thanks to the use of such a solvent mixture, the process according to the invention has a high mono-addition selectivity, usually higher than 90%, i.e. it allows to insert only one HFPO unit at each —COF end group of the acyl fluoride precursor of formula (II) as defined above. Furthermore, the process allows to achieve more than 90% conversion of the —COF groups of the acyl precursor of formula (II) into —CF(CF3)COF groups.
The acyl fluoride precursor of formula (II) above can be synthesised according to U.S. Pat. No. 3,847,978 A (MONTEDISON SPA), U.S. Pat. No. 5,164,517 (AUSIMONT SPA) or U.S. Pat. No. 5,371,272 (AUSIMONT SPA)
The inorganic fluoride catalyst used in the preparation of the compounds of formula (I) as defined above is typically selected from LiF, NaF, KF, CaF2, BaF2, MgF2, CsF2; according to a preferred embodiment, the inorganic fluoride is CsF. The organic fluoride catalyst can be, for instance, a quaternary alkylammonium fluoride or an alkali metal perfluoroalkoxide. A preferred example of alkylammonium fluoride is tetrabutylammonium fluoride. The molar amount of catalyst typically ranges from 0.1 to 100%, preferably from 0.1 to 50%, more preferably from 0.5 to 30% with respect to the equivalents of acyl fluoride precursor (II).
Typically, the equivalent ratio between the acyl fluoride precursor (II) and HFPO ranges from 1:1.1 to 1:3, preferably from 1:1.3 to 1:1.8, while the weight ratio of fluorinated solvent to oxygen-containing hydrogenated solvent typically ranges from 0.1 to 10, preferably from 0.5 to 2. The reaction is usually carried out at a temperature ranging from −40° C. to 100° C., preferably from −30 to +40° C., more preferably from −25° C. to +20° C.; pressure usually ranges from ambient pressure to 1013.25 kPa.
Upon completion of the reaction, the solvents, any unreacted HFPO, any by-products are removed by distillation, either under ambient pressure or at reduced pressure, according to the boiling point of the solvents used.
The fluorinated solvents to be used in the process according to the present invention are usually selected from hexafluoroxylene (bis-trifluoromethylbenzene), hydrofluoroethers, for example those marketed as Novec® by 3M® and hydrofluoropolyethers marketed as H-Galden® by Solvay Solexis. As oxygen-containing hydrogenated solvents, (poly)alkylene glycol ethers like diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether can be mentioned in particular.
The compounds of formula (I) in which x is equal to or higher than 1 can be prepared by submitting a compound of formula (I) in which x is 0 to reaction with one or more equivalents of HFPO under the conditions described above. These compounds are particularly useful in the preparation of further functional derivatives used for imparting hydro- or oleo-repellency, because the presence of a plurality of HFPO end units lowers surface energy and improves barrier effect.
The compounds of formula (I) can be used as precursors of functionalised (per)fluoropolyethers in which functional groups other than —COF are linked to one or to both ends (depending on whether the compound of formula (I) is mono- or bifunctional) of the (per)fluoropolyether chain through one or more HFPO units and, optionally, through a linking bridge. These functional groups are such as to confer reactivity towards co-reactants or substrates, so that further compounds can be obtained or so that substrate surfaces can be modified. Substrates can be both natural and synthetic; among them, paper, cotton, wood, stony materials, polymeric materials, metal or inorganic substrates can be mentioned.
Typically, the functionalised (per)fluoropolyethers according to the present invention which can be obtained from compounds (I) comply with formula (III) below:
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)-(A)q-(T)p (III)
in which:
With regard to the definition of A:
Preferred groups A in which the alkyl or alkylene chain contains one or more O atoms are (poly)alkyleneoxide chains containing repeating units of formula —CH2CH2O—, —CH2CH(CH3)O—, —(CH2)3O— or —(CH2)4O—, more preferably repeating units of formula —CH2CH2O—, —CH2CH(CH3)O—.
With regard to the definition of T:
A first particularly preferred group of compounds of formula (III) above is represented by compounds in which q is 0, p is 1 and T is a —COOR′ group in which R′ is defined above. These compounds, herein after referred to as compounds or esters (III) of formula:
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—COOR′ (IIIa)
in which X2, Rf x and R′ are as defined above can be conveniently obtained from a compound of formula (I) as defined above by reaction with an alcohol R′OH, in which R′ is as defined above, according to known methods. Most conveniently, after the synthesis of a compound of formula (I) according to the procedure reported above, the solvents, any unreacted HFPO and any by products are not removed from the reaction mixture and an alcohol R′OH is added; in a preferred embodiment, the alcohol is ethanol. A tertiary amine can also be added as an HF scavenging agent.
Esters (IIIa) can be conveniently used as precursors of other compounds of formula (IIIa) or of further derivatives.
Esters (IIIa) can be, for instance, hydrolysed according to known methods to provide the corresponding carboxylic acids, i.e. compounds of formula (III) in which q is 0, p is 1 and T is —COOH. These compounds will be also herein after referred to as compounds or acids (IIIb), having formula:
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—COOH (IIIb)
in which X2, Rf and x are as defined above.
Acids (IIIb) can be used as such or in the form of derivatives like salts, acyl halides, anhydrides of further reactive compounds, for the preparation of further compounds of formula (III) or derivatives thereof.
The preparation of exemplary functional derivatives of formula (III), in particular amido-containing derivatives, starting from esters (IIIa) and acids or acid derivatives (IIIb) is schematically resumed in table 1 below. This tables and the following tables 2-4 report the co-reagent and the -(A)p-(T)q group in the resulting compound (III).
Esters (IIIa) can also be reduced according to known methods to provide compounds of formula (III) in which q is 0, p is 1 and T is a —CHO group, hereinafter also referred to as compounds or aldehydes (IIIc), having formula:
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—CHO (IIIc)
in which X2, Rf x and R′ are as defined above.
Aldehydes (IIIc) can in turn be used as such or in the form of their respective acetals or thioacetals as precursors of other compounds of formula (III) or further derivatives.
The preparation of functional derivatives of formula (III) from aldehydes (IIIc) is schematically illustrated in table 2 below:
Esters (IIIa) can also be reduced according to known methods to provide compounds of formula (III) in which A is —CH2-q is 1, p is 1 and T is a —OH group, herein after also referred to as compounds or alcohols (IIId), having formula:
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—CH2OH (IIId)
in which X2, Rf and x are as defined above.
This reduction can be carried out according to conventional methods and with conventional reagents, for example by reaction with a hydride, preferably NaBH4 or LiAlH4, more preferably NaBH4.
Alcohols (IIId) can be in their turn used as precursors of other compounds of formula (III) or of further derivatives, according to conventional methods and with conventional reagents; for example, they can be transformed into compounds in which q is 0, p is 1 and T is thio, amino or carbonate. The —OH group can also be transformed into a leaving group, typically a (per)fluoroalkylsulfonyl group like CF3SO2O—, as illustrated in table 3, entry 5 below, or CH3(CF2)3—SO2O—, and the resulting compound can be reacted with a nucleophile compound, as illustrated in table 4 below. Alcohols (IIId) can also be used as nucleophile reagents with compounds bearing a leaving group or they can be reacted with organic acids, such as carboxylic acids, to provide ester derivatives. Alcohols (IIId) can also be reacted, for example, with one or more ethylene or propylene oxide units in order to provide compounds of formula OM in which p and q are 1, A is a straight or branched aliphatic chain containing one or more oxygen atoms and T is —OH; these hydroxyalkyleneoxide compounds can be represented by formula (IIIe)
X2—O—Rf—CF2CF2O—[CF(CF3)CF2O]x—CF(CF3)—CH2O—(CHYCHYO)yH (IIIe)
in which X2, Rf and x are as defined above and Y is hydrogen or methyl and y is an integer equal to or higher than 1, preferably an integer ranging from 1 to 5, more preferably 1.
Compounds (IIIe) can in turn be useful for other functional derivatives of formula (III) in which T has one of the meanings defined above other than oxygen or for the preparation of further functional compounds, according to reactions known in the art, for example they can be subjected to the same reactions as those mentioned above for alcohols (IIId).
The preparation of exemplary functional derivatives of formula (III) starting from alcohols (IIId) is schematically represented in table 3 below.
Table 4 below schematically represents the preparation of exemplary compounds of formula (III) that can be prepared starting from an alcohol (IIId) wherein the —OH group has been converted into a leaving group, such as a —CH2OSO2CF3 group inserted according to entry 5 of table 3.
Table 5 below schematically represents the conversion of certain functional derivatives obtained according to table 4 above into further functional derivatives.
Additional preferred examples of further functional derivatives that can be prepared from the compounds of formula (III) are polyesters, polyamides, polyurethanes, polyacrylates and phosphazenes.
Polyesters can be prepared according to known methods from the compounds of formula (III) in which T is —OH or a hydroxyl-containing group as defined above by reaction with a polycarboxylic acid, preferably a dicarboxylic acid, according to methods known in the art. Polyesters can also be prepared from compounds of formula (III) in which T is a carboxy or a carboxy-containing group as defined above or an ester or ester-containing group as defined above with a polyalcohol, typically a diol, according to methods known in the art.
Polyamides can be prepared according to known methods by reaction of compounds of formula (III) in which T is a carboxy or a carboxy-containing group as defined above or an ester or ester-containing group as defined above with a polyamine, typically a diamine, according to methods known in the art. In a preferred embodiment, the diamine is selected from hexamethylenediamine, diethylenediamine and ethylenediamine.
Polyacrylates can be prepared according to known methods from the compounds of formula (III) in which T is acrylate or (meth)acrylate by radical polymerization with an acrylic or (meth)acrylic acid derivative in the presence or a radical initiator, according to methods known in the art.
Polyurethanes can be prepared according to known methods by reaction of compounds of formula (III) in which T is a group of formula —OH or a hydroxyl-containing group with a diisocyanate or a polyisocyanate, optionally in the presence of a chain extender selected from a diol or a diamine or a mixture thereof, according to methods known in the art.
Phosphazene derivatives can be prepared, for example, by reactions of compounds of formula (III) in which T is a group of formula —OH or a hydroxyl-containing group with a cyclic phosphazene of formula (IV) or (V) below:
according to known methods, such as those disclosed in EP 1336614 A (SOLVAY SOLEXIS SPA) or in EP 0287892 A (HITACHI METALS LTD [JP]; MARUWA BUSSAN KK [JP), followed by hydrolysis by treatment with a base in an alcoholic medium.
The compounds of formula (III) or derivatives thereof can be used in a variety of applications; one of them is the treating of surfaces when it it desidered to impart hydro- or oleo-repellency to synthetic or natural substrated. Accordingly, the present invention further related to manufactured or synthetic articles treated with a compound of formula (III).
The invention will be now illustrated in greater detail in the following experimental section and non-limiting examples.
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.
The acyl precursors of formula (II) were synthesised according to U.S. Pat. No. 3,847,978; other chemical and solvents were commercially available; in some instances, the solvents were distilled before use.
1.1 Determination of Molecular Weight and Structure
Molecular weight and structure were determined by 1H-NMR and 19F-NMR analysis. The spectra were recorded on solvent-free samples, by means of a Varian Mercury instrument operating at 288 and 300 MHz with respect to the product. Chemical shifts are reported with respect to CFCl3 and TMS used as external standards.
1.2. Determination of the Glass Transition (Tg)
Glass transition was determined according to ASTM D3418, the standard method for determining the transition temperature of polymers through thermal analysis (DSC). DSC analysis was carried out using a Perkin-Elmer Pyris 2 instrument under He atmosphere.
1.3. Titration
Titration was carried out using Potentiometric titrator Tritini 716 GPD (Metrohm) and a Glass Electrode Metrohm 6.0262.100 (pH 0-13/0-80° C.—3M KCl). The purpose of the method consisted in the determination of the percentage of the terminal groups (ester or amido groups) hydrolized under neutral or basic conditions. Details of the procedure are reported in the following paragraph.
1.4. Stability to Hydrolysis
A selected amount of compound of formula (III) or a polymeric material obtained therefrom was immersed in water at constant pH, at temperature usually ranging from room temperature to 75° C. and for a time usually ranging from 6 to 8 hours, typically of 7 hours; thereafter, the tested compound of formula (III) or material was submitted to 19-NMR quantitative analysis and to titration of the hydrolysed groups. The procedures reported below were followed for evaluating the stability of esters or amides complying or obtained from the compounds of formula (III) (test compounds). In such procedures, hydrolysis is expressed as equivalent percentage of hydrolysed groups.
Stability Test at Neutral pH
A round-bottom two-neck flask, equipped with magnetic stirrer, condenser and thermometer, was charged with 2 g test compound and 10 ml distilled water. This mixture was then heated at 70° C. and left under stirring at this temperature for 7 hours.
Thereafter, the mixture was cooled down to room temperature and the hydrolysis percentage was determined measuring the amount of resulting (in the case of esters compounds) or the amount of ammonium salt (in the case of amido compounds) by direct titrimetric analysis, using a 0.02 N solution of triethylamine in methanol or a 0.1N solution of tetrabutylammonium hydroxide in isopropyl alcohol respectively.
Stability Test at Basic pH
1 g test compound and 1.5 equivalents NaOH (0.1 M solution) were charged in a flask equipped with magnetic stirrer and condenser. The resulting mixture was left under stirring for 7 hours, unless indicated otherwise. In the case of esters, the hydrolysis percentage was determined through titration of the residual NaOH with a 0.1 N HCl solution in isopropanol, while in the case of amides it was determined by treatment with an excess of HCl and back titration of the resulting ammonium salt with a 0.1N solution of tetrabutylammonium hydroxide in isopropyl alcohol.
In the following examples, the expression “title compound” refers to the compound indicated in the title of each example; the expression “the compound of example (example number) refers to the compound indicated in the title of each example. The expressions “mono addition product” or “mono adduct” indicate the product obtained by addition of one HFPO unit at one or two ends of the mono or di-acylfluoride of formula (II) used as precursor in each example. The expression “bis-addiction product” and “bis adduct” indicate the product obtained by addition of two HFPO units at one or both ends of the mono or di-acylfluoride precursor. Likewise, the expressions “mono addition” or “mono addition reaction” indicate a reaction whereby one HFPO unit is added at one or two ends of the mono- or di-acylfluoride of formula (II) respectively used as precursor in each example and the expression “poly addition” or “polyaddition reaction” indicate a reaction whereby more than one HFPO unit is added at one or two polymer ends of the mono- or di-acylfluoride precursor.
Method 1
1.85 g CsF (MW=52, 12.2 mol), 70 g diethylene glycol dimethyl ether, 140 g bis trifluoromethyl benzene and 50.5 g diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (M_W=1650, Mw/Mn=1.2, m/n=1.5, 30.6 mmol) were charged under nitrogen atmosphere into an 0.5 l AISI 316 reactor equipped with agitator, sampling device, thermocouple and manometer. The resulting mixture was heated to 40° C. and left under stirring for two hours, then cooled down to −25° C. and nitrogen was removed by connecting the reactor to a vacuum pump. 15 g hexafluoropropylene oxide (MW=166, 90.4 mmol) was added over 2 hours and the resulting mixture was left under stirring for 4 hours.
After this time, the mixture was allowed to warm up to room temperature and 3.5 g of a low-boiling product were recovered in a dry ice trap; 19F NMR confirmed that the product was CF3CF2COF. The reaction crude was then poured into a separatory funnel under inert atmosphere; separation of two phases, an upper inorganic phase and a lower organic phase was observed. The latter was recovered and distilled, to provide the following fractions:
The distillation residue was submitted to thin layer distillation at a temperature ranging from 200 to 250° C. at a pressure lower than 1.33 Pa, to provide 56.3 g FC(O)CF(CF3)OCF2CF2O(CF2CF2O)m(CF2O)nCF2CF2 OCF(CF3)COF (MW 1960, 28 mmol) containing:
The thin layer distillation residue (4.8 g) was analysed by 19F-NMR; the results confirmed that the residue consisted of: —FC(O)CF(CF3)OCF2CF2O(CF2CF2O)m(CF2O)nOF2CF2O—CF(CF3) CF2OCF(CF3)COF (MW 2120) (81%) in admixture with —FC(O)CF(CF3)OCF2CF2O(CF2CF2O)m(CF2O)nOF2CF2O—CF(CF3)COF (MW 1960) (19%).
The yield of title compound with respect to the starting diacyl fluoride was 91.4%; purity was 96% and Tg (midpoint) was −110° C.
The overall mono-addition selectivity (expressed as % of meq of —CF2COF end groups reacted with one HFPO unit with respect to the meq of —CF2 COF end groups reacted with more HFPO units) was 96%.
Method 2
The synthesis was carried out according to method 1, using 1.78 g CsF (MW=152, 11.7 mmol), 70 g diethylene glycol dimethyl ether, 120 g o H Galden® PFPE (grade A), 50 g diacyl fluoride of formula FC(O)CF2O(CF2 CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.2, m/n=1.5, 30.3 mmol) and 15.5 g HFPO (MW=166, 93.4 mmol).
Upon completion of the reaction, the low-boiling fluorinated by-products and the solvents were removed by distillation at room pressure as described in method 1. The distillation residue was submitted to thin layer distillation, to provide 55.2 g of a mixture containing: 95% title compound (MW 1960, 28.3 mmol) in admixture with:
The thin layer distillation residue (approx. 5.2 g) was analysed by 19F-NMR; the results confirmed that this residue consisted of:
The yield of title compound amounted to 88% and the selectivity of mono-addition (defined as in method 1) was 96%. Conversion was therefore higher than 90%.
Method 3
Method 2 was followed, using 0.3 g CsF (MW=152, 2 mmol), 70 g diethylene glycol dimethyl ether, 140 g bis-trifluoromethyl benzene, 55 g diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.1, m/n=1.5, 33.3 mmol) and 15 g HFPO (MW=166, 90 mmol), with the difference that, before addition of HFPO, temperature was lowered to 20° C. and that, after the addition, the mixture was stirred at this temperature for 8 hours.
Upon completion of the reaction, the low-boiling fluorinated by-products and the solvents were removed by distillation at room pressure as described in method 1, to provide 62.1 g of a product containing:
The distillation residue (approx. 4.9 g) was analysed by 19F-NMR and the results confirmed that it contained 15% title compound.
The overall yield of title compound was 92.3% (97% purity) and the selectivity of mono-addition (as defined in method 1) was 96%. Conversion was therefore higher than 90%.
This compound was synthesised according to method 2, using 2.0 g CsF (MW=152, 13 mmol), 70 g diethylene glycol dimethyl ether, 110 g of H Galden® PFPE (grade A), 50 g diacyl fluoride of formula FC(O)CF2O(CF2 CF2O)m(CF2O)nCF2COF (MW=750; Mw/Mn 1.1 m/n=1.8, 67 mmol) and 35 g HFPO (MW=166, 211 mmol).
After removal of the low-boiling fluorinated by-products and solvents by distillation at room pressure, the distillation residue was submitted to thin layer distillation, to provide 67.8 g of a mixture containing (19F-NMR analysis):
The thin layer distillation residue (approx. 4.7 g) consisted of:
The yield of title compound was 90.2% and the selectivity (defined as in Example 1, method 1) was 96%.
Tg (midpoint): −105° C.
Conversion was therefore higher than 90%.
1.78 g CsF (MW=152, 11.7 mmol), 70 g diethylene glycol dimethyl ether, 140 g bis-trifluoromethyl benzene and 48.4 g diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.2, m/n=1.5, 29.3 mmol) were charged under nitrogen atmosphere in a 0.5 l AISI 316 reactor, equipped with agitator, sampling device, thermocouple and manometer. The resulting mixture was heated to 40° C. and left under stirring for two hours, then cooled down to −25° C. Nitrogen was removed by connecting the reactor to a vacuum pump.
14 g HFPO (MW=166, 84.3 mmol) was added over 2 hours and the resulting mixture was left under stirring for 4 hours. After this time, the mixture was added with 30 g ethanol and 6 g triethylamine (59.4 mmol), keeping the temperature at −25° C.; upon completion of the addition, the temperature was raised to 20° C. and the resulting reaction solution was poured into a plastic separation funnel containing 50 ml water. Formation of an upper inorganic phase and a lower organic phase was observed; the latter was recovered and distilled at room pressure.
The following fractions were isolated:
The distillation residue was submitted to thin layer distillation at a temperature ranging from 200 to 270° C. and at a pressure lower than 1.33 Pa, to provide 54.9 g (26.8 mmol) of title compound with 96% purity. The impurities consisted of:
The thin layer distillation residue (approx. 5 g) was analysed by 19F-NMR. The results confirmed that this residue consisted of:
The yield of title compound with respect to the starting product amounted to 89%. The overall monoaddition selectivity (defined as in Example 1, method 1) was 96%.
Tg: −108° C. (midpoint).
Conversion was therefore higher than 90%.
The title compound was prepared from the compound of example 2 following the procedure described in example 3 above.
50.0 g of a 3% wt NaBH4 (MW=38, 39.5 mmol) solution in absolute ethanol was charged into a 4-neck round-bottom flask, equipped with agitator, thermometer, condenser and dropping funnel; thereafter, the compound of example 3 (40 g, 19.4 mmol) was added drop-by-drop, keeping the temperature between 10 and 15° C.
Upon completion of the addition, the mixture was left under stirring for 30 minutes, allowing the temperature to rise up to room temperature. After this time, 15 g of a 10% HCl solution was added to neutralise any NaBH4 excess and to hydrolyse any boric esters. The resulting reaction crude was poured into a separation funnel to allow separation of two phases; the lower one was recovered and the solvent was removed at 80° C. at a pressure of about 2.67 kPa (20 mmHg), to recover 36.3 g (18.4 mmol) title compound.
Yield: 94.9% with respect to the starting compound.
Tg: −105° C. (midpoint).
Conversion was therefore higher than 90%.
This compound was synthesised following the procedure described in example 3, using 5 g CsF (MW=152, 33 mmol), 40 g diethylene glycol dimethyl ether, 80 g bis trifluoromethyl benzene, 25 g diacyl fluoride of formula FC(O)CF2OCF2CF2OCF2COF (MW 326, 77 mmol), 35 g HFPO (MW 166, 210 mmol) and 30 g ethanol. Upon completion of the synthesis, the resulting solution was poured into a plastic separation funnel containing 60 ml water. Separation of two phases was observed, an upper aqueous phase and a lower organic phase; the latter one was recovered and submitted to distillation, to provide 51 g of a mixture containing:
The distillation residue (approx. 5 g) was analysed by 19F-NMR analysis and the results confirmed that it contained 85% of product containing one HFPO unit at one end chain and two moieties of formula —CF(CF3)CF2 OCF(CF3)C(O)OCH2CH3 at the other end chain in admixture with 15% title compound.
The overall yield of title compound was approximately 90% and the selectivity of mono-addition (defined as in Example 1, method 1) was 95%.
The title compound, in which m and n are as defined in the description and z is an integer higher than 1, was prepared by reacting under vacuum the compound of example 3 with hexamethylenediamine in a 1:1 molar ratio at 150° C. The structure was confirmed by 19F-NMR and IR analysis.
1.85 g CsF (MW=152, 12 mmol), 110 g diethylene glycol dimethyl ether, 50 g diacyl fluoride of formula: FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.2, m/n=1.5, 30.3 mmol) were loaded in a 0.5 l 316 AISI reactor, equipped with agitator, sampling device, thermocouple and manometer under nitrogen atmosphere.
The resulting mixture was then heated to 40° C. and left under stirring for two hours, then cooled to −25° C.; nitrogen was removed by connecting the reactor to a vacuum pump. 15 g HFPO (MW=166, 90 mmol) was added over two hours and the resulting mixture was left under stirring for 4 hours. After this time, the temperature was allowed to rise to room temperature and the mixture was submitted to nitrogen purge cycles. Thereafter, the reaction crude was added with 40 g absolute ethanol and the reaction was continued according to example 3 above.
The low-boiling by-products and solvents were then removed by distillation at room temperature and the distillation residue was submitted to thin layer distillation under reduced pressure to afford 52.5 g of a mixture of products that, according to 19F-NMR analysis, had only 35% conversion and in which 30% of the end groups contained two or more HFPO moieties. As a consequence, the mixture contained only 5% of title compound, which could not be isolated in pure form.
Synthesis and purification were carried out as described in comparative example 1 above, using 9.2 g (i.e. a higher amount with respect to that example) CsF (MW=152, 61 mmol), 100 g diethylene glycol dimethyl ether, 50 g diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.2, m/n=1.5, 30.3 mmol) and 15 g HFPO (MW=166, 90 mmol).
Thin layer chromatography afforded 55 g of a mixture of products with 60% conversion, in which 30% of the reacted —COF groups of the diacyl fluoride precursor contained at least two HFPO moieties, as confirmed by 19F-NMR analysis. Statistically, 15% of this product consisted of the title compound which, however, could not be separated from the mixture.
Synthesis and purification were carried out as described in comparative example 1, using 1 g CsF (MW=152, 6.6 mmol), 100 g diethylene glycol dimethyl ether, 25 g of diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=750; Mw/Mn 1.1 m/n=1.8, 33.3 mmol) and 32 g (193 mmol, i.e. a large excess) HFPO.
Thin layer chromatography afforded 50 g of a product which, from 19F-NMR analysis, showed 99% conversion and wherein terminal groups statistically contained 2.5 HFPO units, i.e. a product of formula:
CH3CH2OC(O)CF(CF3)[OCF2CF(CF3)]sOCF2CF2O(CF2CF2O)m(CF2O)nCF2CF2O[CF(CF3)CF2O]CF(CF3)C(O)OCH2CH3
wherein s=2.5 and m and n were as defined above.
Accordingly, the product containing one HFPO moiety at each end of the polymer chain could not be separated from the mixture.
The Tg (midpoint of the mixture) was −78° C.
1.20 g KF (MW=58.1, 20.6 mmol) and 50 g diethylene glycol dimethyl ether were loaded, under nitrogen atmosphere, in a 0.5 l AISI 316 reactor equipped with agitator, thermocouple and sampling device and the resulting mixture was stirred at −17° C.
101 g diacyl fluoride of formula FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.2, m/n=1.5, 61.2 mmol) was added and the resulting mixture was stirred for 30 minutes, then 15.2 g (92 mmol) HFPO was added to the reaction mass over a time period of one hour; a temperature increase up to −4° C. was observed. After 30 minutes the internal temperature was raised to 20° C.
The reaction mass was unloaded from the reactor and the lower fluorinated phase (113 g) was separated and submitted to distillation. According to 19F-NMR analysis, this phase contained a mixture of products having only 25% unreacted end groups of formula —OCF2COF; 69% of the product mixture consisted of the monoaddition product and 4% of the bis-addition product. This composition statistically corresponds to the following products:
a) 6% unreacted acyl fluoride precursor;
b) 50% title compound;
c) a mixture of FC(O)CF2O(CF2CF2O)m(CF2O)nCF2CF2OCF(CF3)COF (36%), FC(O)CF2O(CF2CF2O)m(CF2O)nCF2CF2O[CF(CF3)CF2O]xCF(CF3)COF (2%), with x being equal to or higher than 1; FC(O)CF(CF3)OCF2CF2O(CF2CF2O)m(CF2O)nOF2CF2O[CF(CF3)CF2O]x CF(CF3)COF (6%), with x being equal to or higher than 1.
The fluorinated phase was subjected to distillation; however, neither the title compound nor any other compounds could be isolated in pure form.
The procedure described in comparative example 4 above was followed using a lower amount of HFPO; in fact, 8.6 g (52 mmol) HFPO was added instead of 15.2 g (92 mmol). The amounts of all other reagents and solvents remained unchanged.
The fluorinated phase (106 g) obtained upon completion of the reaction contained 60% unreacted acyl fluoride precursor with end groups of formula —OCF2COF, 37% of mono-addition product with end groups of formula —CF(CF3)COF and 3% of bis-addition product with end groups of formula —CF(CF3)CF2OCF(CF3)COF. This composition statistically corresponds to the following mixture:
a) 36% unreacted acyl fluoride precursor;
b) 14% title compound;
c) a mixture of FC(O)CF2O(CF2CF2O)m(CF2O)nCF2CF2OCF(CF3)COF (44%), FC(O)CF2O(CF2CF2O)m(CF2O)nCF2CF2O[CF(CF3)CF2O]xCF(CF3)COF (3.6%), with x being equal to or higher than 1; FC(O)CF(CF3)OCF2CF2O(CF2CF2O)m(CF2O)nCF2CF2O[CF(CF3)CF2O]xCF(CF3)COF (2.2%), with x being equal to or higher than 1.
The fluorinated phase was subjected to distillation; however, neither the title compound nor any other compounds could be isolated in pure form.
The procedure described in comparative example 4 above was followed using the following amounts of reagents and solvents:
Upon completion of the reaction, the lower fluorinated phase obtained (107 g) contained a mixture of products having 30% unreacted —OCF2COF end groups, 65% end groups of formula —CF(CF3)COF and 4% groups of formula —CF(CF3)CF2OCF(CF3)COF.
This phase was subjected to distillation; however, it was not possible to isolate the desired title compound, due to the fact that polydispersivity is high and does not allow to differentiate the vapour tension of the phase components.
The procedure described in comparative example 4 above was followed using the following amounts of reagents and solvents: 1.20 g KF (MW=58.1, 20.6 mmol), 50 g diethylene glycol dimethyl ether, 96 g acyl fluoride of formula CF3O(CF2CF2O)m(CF2O)nCF2COF (MW=800, Mw/Mn=1.4, m/n=1.5, 120 mmol) and 15.2 g (92 mmol) HFPO.
The lower fluorinated fraction (105 g), obtained upon completion of the reaction contained a mixture of products having 30% unreacted —OCF2 COF end groups, 60% of monoaddition product and 8% bis-addition product with end groups of formula —CF(CF3)CF2OCF(CF3)COF.
This fraction was submitted to distillation, but the desired title compound could not be isolated.
Hydrolysis Tests
Test 1—Resistance to Hydrolysis of the Ester of Example 4 at Neutral pH
Resistance to hydrolysis of this ester was evaluated at neutral pH as described in general procedure 1.3 above in comparison with CH3CH2OC(O)CF2O(CF2CF2O)m(CF2O)nCF2C(O)OCH2CH3 (reference compound), obtained from FC(O)CF2O(CF2CF2O)m(CF2O)nOF2COF (MW=750).
The title diethyl ester underwent <0.1% hydrolysis, while about 45% reference compound was hydrolysed.
Test 2—Resistance to Hydrolysis of the Ester of Example 4 at Basic pH
Resistance to hydrolysis of this ester was evaluated at basic pH as described above in comparison with CH3CH2OC(O)CF2O(CF2CF2O)m(OF2O)nCF2C(O)OCH2CH3 (reference compound), obtained from FC(O)CF2O(CF2CF2O)m(CF2O)nOF2COF (MW=750).
The title diethyl ester underwent <5% hydrolysis, while about 40% reference compound was hydrolysed.
Test 3—Resistance to Hydrolysis of the Polyamide of Example 7
Resistance to hydrolysis of the polyamide of example 7 (in the present example referred to as polyamide A) was determined in comparison with a reference polyamide of formula: [(O)CCF2O(CF2CF2O)m(CF2O)nCF2C(O)NH(CH2)6NH—]z— (polyamide B), which was obtained by polycondesation reaction of the diethyl ester of FC(O)CF2O(CF2CF2O)m(CF2O)nCF2COF (MW=1650, Mw/Mn=1.1, m/n=1.5) with an equimolar amount of hexamethylenediamine, according to the procedure reported in example 7.
Polyamides A and B were submitted to hydrolysis at basic pH for 3 weeks, then the hydrolysis percentage was evaluated through acid/base titration. Polyamide A underwent <1% hydrolysis, while polyamide B underwent about 8% hydrolysis. This demonstrated that the polyamide according to the present invention is eight times more stable than a polyamides obtained from a diacyl fluoride precursor that does not contain HFPO terminal units.
Test 4—Resistance to Hydrolysis of the Diacetate of the Compound of Example 5 at Basic pH
The alcohol compound of example 5 was transformed into the corresponding diacetate by reaction with acetic anhydride according to a known procedure. This diacetate was subjected to hydrolysis at basic pH as described in general procedure 1.3 above. After 7 hours, less than 1% hydrolysis was observed.
Similarly, Fluorolink® D PFPE from Solvay Solexis was transformed into the corresponding diacetate (chain ends of formula —CF2CH2OC(O)CH3) and submitted to hydrolysis under the same conditions. After 7 hours, 5% hydrolysis was observed.
Test 5—Resistance to Hydrolysis of the Diethyl Ester of Example 6 at Neutral pH
The diethyl ester of example 6 was submitted to a comparative test of resistance to hydrolysis with respect to the diethyl ester of formula CH3CH2OC(O)CF2O(CF2CF2O)3CF2C(O)OCH2CH3 (reference compound), prepared from a diacyl precursor of formula: FC(O)CF2O(CF2CF2O)3CF2 COF.
After about 7 hours at 70° C. less than 5% diethyl ester of example 6 underwent hydrolysis, while more than 95% reference compound underwent hydrolysis.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11183716.7 | Oct 2011 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/068884 | 9/25/2012 | WO | 00 | 4/3/2014 |
