WO2021224164A1 - Polyamide/fluoroelastomer blends and corresponding articles and formation methods - Google Patents

Abstract

Described herein are polymer compositions (PC) including a semi-aromatic, semi- crystalline polyamide (PA) and from 1 wt.% to 40 wt.% of an uncured fluoroelastomer (FE), where the polymer composition (PC) is free of metal hydroxides. It was surprisingly found that the polymer compositions (PC) had increased mechanical performance and increased mechanical thermal aging performance, relative to corresponding polymer compositions. Still further, the polymer compositions (PC) had desirably chemical resistance (e.g. to fuel), relative to corresponding polymer compositions. It was also surprisingly discovered that, relative to analogous polymer compositions in which the fluoroelastomer is cured, the polymer compositions (PC) had increased tensile elongation at break. At least in part due to the improved mechanic properties, mechanical thermal aging performance and chemical resistance, the polymer compositions (PC) can be desirably incorporated into articles including, but not limited to, pipes to convey oil and gas.

Description

POLYAMIDE/FLUOROELASTOMER BLENDS AND CORRESPONDING ARTICLES

AND FORMATION METHODS

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to Indian provisional patent application No. 202021019485, filed on 07 May 2020, the whole content of which is incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The invention is directed to polymer compositions including a semi-aromatic, semi crystalline polyamide and an uncured fluoroelastomer. The invention is also directed to articles including the polymer composition and corresponding formation methods.

BACKGROUND OF THE INVENTION

Polyamides are highly desirable for articles used in fuel and oil contact applications. In particular, due to the relatively high chemical resistance of semi -aromatic, semi -crystalline polyamides, articles formed therefrom have excellent barrier properties with respect to fuel and oil permeation. Nevertheless, semi -aromatic, semi -crystalline polyamides are relatively brittle and susceptible to undesirable degradation of mechanical performance after prolonged exposure to heat. In conjunction with automotive and oil and gas industry demands for polymer compositions with increased flexibility and toughness, there is a need for polyamide compositions that have improved mechanical performance and mechanical heat aging performance, while retaining excellent chemical resistance.

SUMMARY OF INVENTION

In a first aspect, the invention is directed to a polymer composition (PC) comprising (1) a semi-aromatic, semi -crystalline polyamide (PA) having a recurring unit (RPA) represented by the following formula:

wherein Ri is selected from the group consisting of a C4 - C15 alkyl and Ri, at each location, is selected from the group consisting of a hydrogen, a halogen, a C1-C12 alkyl, a C7-C24 alkylaryl, a C7-C24 aralkyl, a C6-C24 arylene, a C1-C12 alkoxy, and a C6-C18 aryloxy and (2) 1 wt.% to 40 wt.% of an uncured fluoroelastomer (FE); wherein the polymer composition (PC) is free of metal hydroxides. In some embodiments, the polymer composition (PC), -Ri- in recurring unit (RPA) is a diradical of 1,9-diaminononane. 4. Additionally or alternatively, in some embodiments, the polyamide (PA) comprises an additional recurring unit (R*PA) that is distinct from (RPA) and represented by a formula (1), where wherein -Ri- in recurring unit (R*PA) is a diradical of 2- methyl-l,8-diaminooctane. In some embodiments, the uncured fluoroelastomer (FE) is a vinylidene fluoride copolymer. In some such embodiments, the uncured fluoroelastomer (FE) comprises a fluorine content of at least 60 wt.%, preferably at least 68 wt.%, as determined by nuclear magnetic resonance (“NMR”) spectroscopy.

In some embodiments, the polymer composition (PC) has a tensile elongation at break of from 1% to 80% and a tensile modulus of from 1.0 GPa to 2.2 GPa. In some embodiments, the polymer composition (PC) has a notched impact strength of at least 100 J/m. In some embodiments, the polymer composition (PC) has an apparent viscosity of at least 1000 Pa s at a shear of 1 s ¹ to 100 s ¹ and a temperature of 290° C. In some embodiments the polymer composition (PC) has a tensile strength of at least 50 MPa.

In a second aspect, the invention is directed to a tube comprising the polymer composition (PC). In some such embodiments, the tube is a flexible riser.

DETAILED DESCRIPTION OF THE INVENTION Described herein are polymer compositions (PC) including a semi-aromatic, semi crystalline polyamide (PA) and from 1 wt.% to 40 wt.% of an uncured fluoroelastomer (FE), where the polymer composition (PC) is free of metal hydroxides. It was surprisingly found that the polymer compositions (PC) had increased mechanical performance ( e.g . tensile strength, tensile elongation at break and notched impact strength) and increased mechanical thermal aging performance, relative to corresponding polymer compositions. As used herein, a corresponding polymer composition refers to a polymer composition having further semi -aromatic, semi crystalline polyamide (PA) in place of the uncured fluoroelastomer (FE). Still further, the polymer compositions (PC) had increased flexibility ( e.g . lower tensile modulus), and desirable chemical resistance (e.g. to fuel), relative to corresponding polymer compositions. It was also surprisingly discovered that, relative to analogous polymer compositions in which the fluoroelastomer is cured, the polymer compositions (PC) had increased tensile elongation at break. Herein, sometimes “uncured fluoroelastomer (FE)” is referred to simply as “fluoroelastomer (FE)”. It will be understood that reference to “fluoroelastomer (FE)” is also a reference to “uncured fluoroelaster (FE).” At least in part due to the improved mechanic properties, mechanical thermal aging performance and chemical resistance, the polymer compositions (PC) can be desirably incorporated into articles including, but not limited to, pipes to convey oil and gas. Still further, at least because the polymer compositions (PC) have desirably viscosities relative to corresponding polymer compositions, the polymer compositions (PC) are especially desirable for pipe extrusion.

As used herein, a semi-crystalline polymer is a polymer having a heat of fusion (“D¾”) of at least 5 J/g at a heating rate of 20° C/min. DH_G can be measured according to ASTM D3418.

Additionally, as used herein, the term “alkyl”, as well as derivative terms such as “alkoxy”, “acyl” and “alkylthio”, include within their scope straight chain, branched chain and cyclic moieties. Examples of alkyl groups are methyl, ethyl, 1 -methyl ethyl, propyl, 1,1 dimethyl ethyl, and cyclo-propyl. Unless specifically stated otherwise, each alkyl or aryl group may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, sulfo, C1-C6 alkoxy, C1-C6 alkylthio, C1-C6 acyl, formyl, cyano, C6-C15 aryloxy or C6- Ci₅ aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. The term “halogen” or “halo” includes fluorine, chlorine, bromine and iodine, with fluorine being preferred.

The term “aryl” refers to a phenyl, indanyl or naphthyl group. The aryl group may comprise one or more alkyl groups, and are called sometimes in this case “alkylaryl”; for example may be composed of an aromatic group and two C₁-C₆ groups (e.g. methyl or ethyl). The aryl group may also comprise one or more heteroatoms, e.g. N, O or S, and are called sometimes in this case “heteroaryl” group; these heteroaromatic rings may be fused to other aromatic systems. Such heteroaromatic rings include, but are not limited to furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, isoxazolyl, oxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazyl, pyrimidyl, pyrazinyl and triazinyl ring structures. The aryl or heteroaryl substituents may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, C1-C6 alkoxy, sulfo, C1-C6 alkylthio, C1-C6 acyl, formyl, cyano, C6-C15 aryloxy or Cr,-C 15 aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied.

The expression “derivative thereof’ when used in combination with the expression “dicarboxylic acid” is intended to denote whichever derivative which is susceptible of reacting in polycondensation conditions to yield an amide bond. Examples of amide-forming derivatives include a mono- or di-alkyl ester, such as a mono- or di-methyl, ethyl or propyl ester, of such carboxylic acid; a mono- or di-aryl ester thereof; a mono- or di-acid halide thereof; a carboxylic anhydride thereof and a mono-or di-acid amide thereof, a mono- or di-carboxylate salt.

As used herein, wt.% is relative to the total weight of the polymer composition (PC), unless explicitly stated otherwise.

THE POLYMER COMPOSITION (PC)

The polymer composition (PC) includes a semi-aromatic, semi-crystalline polyamide (PA) and from 1 wt.% to 40 wt.% of an uncured fluoroelastomer (FE). In some embodiments, the polymer composition (PC) can further include one or more additives.

As noted above, the polymer compositions (PC) have increased mechanical performance and mechanical heat aging performance, relative to corresponding polymer compositions. In some embodiments, the polymer composition (PC) has a tensile elongation at break of at least 10%, at least 15% or at least 20%. In some embodiments, the polymer composition (PC) has a tensile elongation at break of no more than 80%, no more than 70% or no more than 65%. In some embodiments, the polymer composition (PC) has a tensile elongation at break of from 10 % to 80%, from 10% to 70%, from 10% to 65%, from 15% to 65% or from 20% to 65%. In some embodiments, the polymer composition (PC) has a tensile elongation at break from 13% to 50 %, from 15% to 25% or from 10% to 65%. In some embodiments, the polymer composition (PC) has a notched impact strength of at least 100 J/m, at least 120 J/m, at least 130 J/m, at least 150 J/m, at least 200 J/m, at least 500 J/m, at least 750 J/m or at least 900 J/m. Additionally or alternatively, in some embodiments the polymer composition (PC) has a notched impact strength of no more than 1300 J/m, no more than 250 J/m, no more than 170 J/m or no more than 150 J/m. In some embodiments, the polymer composition (PC) has a notched impact strength of from 100 J/m to 1200 J/m, from 100 J/m to 250 J/m, from 110 J/m to 250 J/m, from 120 J/m to 250 J/M, from 130 J/m to 250 J/m, from 130 J/m to 160 J/m, from 180 J/m to 1,100 J/m, from 900 J/m to 1,100 J/m, from 1000 J/m to 1,350 J/m or from 1,000 J/m to 1,350 J/m. In some embodiments, the polymer composition (PC) has a tensile strength at break of at least 50 MPa. Additionally or alternatively, in some embodiments, the polymer composition (PC) has a tensile strength at break of no more than 100 MPa, no more than 90 MPa, no more than 85 MPa or no more than 80 MPa. Tensile strength at break, tensile elongation at break and notched impact strength can be measured as described in the Examples section. Also as noted above, the polymer compositions (PC) have increased flexibility (reduced tensile modulus), relative to corresponding polymer compositions. In some embodiments, the polymer composition (PC) has a tensile modulus of at least 1.0 GPa, at least 1.2 GPa, at least 1.3 GPa or at least 1.5 GPa. In some embodiments, the polymer composition (PC) has a tensile modulus of no more than 2.2 GPa, no more than 2.1 GPa or no more than 2.0 GPa. In some embodiments, the polymer composition (PC) has a tensile modulus of from 1.0 GPa to 2.2 GPa, from 1.2 GPa to 2.2 GPa, from 1.3 GPa to 2.2 GPa, from 1.5 GPa to 2.2 GPa, 1.0 GPa to 2.1 GPa, from 1.2 GPa to 2.1 GPa, from 1.3 GPa to 2.1 GPa, from 1.5 GPa to 2.1 GPa, 1.0 GPa to 2.0 GPa, from 1.2 GPa to 2.0 GPa, from 1.3 GPa to 2.0 GPa, or from 1.5 GPa to 2.0 GPa. Tensile modulus, elongation and strength, as well as notched impact strength, can be measured as described in the Examples section.

In some embodiments, the polymer compositions (PC) also have improved mechanical performance after heat aging. Heat aging consists of heating the polymer composition (PC) at a temperature of 125° C for 500 hours. In some embodiments, the polymer composition (PC) has a tensile strength at break after heat aging of at least 60 MPa or at least 70 MPa. In some embodiments the polymer composition (PC) has a tensile strength at break after heat aging of no more than 100 MPa, no more than 90 MPa or no more than 85 MPa. In some embodiments, the polymer composition (PC) has a tensile strength at break after heat aging of from 60 MPa to 100 MPa, from 60 MPa to 90 MPa, from 60 MPa to 85 MPa, from 70 MPa to 100 MPa, from 70 MPa to 90 MPa or from 70 MPa to 85 MPa. In some embodiments, the polymer composition (PC) has a tensile elongation at break after heat aging of at least 6% or at least 10%. In some embodiments, the polymer composition (PC) has a tensile elongation at break after heat aging of no more than 15%. In some embodiments, the polymer composition (PC) has a tensile elongation at break after heat aging of from 6% to 15 % or from 10% to 16%. In some embodiments, the polymer composition (PC) has a notched impact strength after heat aging of at least 110 J/m or at least 115 J/m. In some embodiments, the polymer composition (PC) has a notched impact strength after heat aging of no more than G00 J/m, no more than 200 J/m or no more than 190 J/m. In some embodiments, the polymer composition (PC) has an notched impact strength of from 110 J/m to 1200 J/m, from 115 J/m to 1200 J/m, from 115 J/m to 200 J/m or from 115 J/m to 190 J/m.

In some embodiments, the polymer composition (PC) has a tensile modulus after heat aging of at least 1.0 GPa, at least 1.3 GPa or at least 1.5 GPa. In some embodiments, the polymer composition (PC) has a tensile modulus after heat aging of no more than 2.2 GPa. In some embodiments, the polymer composition (PC) has a tensile modulus after heat aging of from 1.0 GPa to 2.2 GPa, from 1.3 GPA to 2.2 GPa or from 1.5 GPa to 2.2 GPa.

The polymer compositions (PC) also have desirably viscosity for pipe ( e.g . tube) extrusion. In some embodiments, the polymer composition (PC) gas an apparent viscosity of at least 1000 Pa s, at least 1500 Pa s or at least 2000 Pa s, at a shear of 1 s ¹ to 100 s ¹ and a temperature of 290° C. Apparent viscosity can be measured as described in the Examples sections.

The Semi-Aromatic. Semi-Crystalline Polyamide (PA)

The polymer composition includes a semi-aromatic, semi -crystalline polyamide having a recurring unit (R_PA) represented by the following formula:

where Ri is selected from the group consisting of a C4 - C15 alkyl and Ri, at each location, is selected from the group consisting of a hydrogen, a halogen, a C1-C12 alkyl, a C7-C24 alkylaryl, a C7-C24 aralkyl, a C6-C24 arylene, a C1-C12 alkoxy, and a C6-C18 aryloxy. Preferably Ri is a C5 - C10 alkyl. Most preferably, Ri is a C9 alkyl. Preferably, Ri at each location, is a hydrogen. In some embodiments, the polyamide includes at least 50 mol%, at least 57 mol%, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 99 mol%, or at least 99.9 mol% of recurring unit (R_PA). AS used herein, mol% is relative to the total number of recurring units in the indicated polymer ( e.g . the polyamide or the fluoroelastomer). For ease of reference, sometimes the semi-aromatic, semi-crstyalline polyamide (PA) is simply referred to as “polyamide (PA).”

In some embodiments, -Ri- is the diradical of a diamine selected from the group consisting of 1,4-diaminobutane, 1,5-diaminopentane, 2-methyl-l,5-diaminopentane, 1,6-diaminohexane, 3- methylhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2, 2, 4-trimethyl - hexamethylenediamine, 2,4,4-trimethyl-hexamethylenediamine, 1,7-diaminoheptane, 1,8- diaminooctane, 2,2,7,7-tetramethyloctamethylenediamine, 1,9-diaminononane, 2-methyl- 1,8- diaminooctane, 5-methyl-l,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12- diaminododecane, and 1,13-diaminotridecane. Preferably, -Ri- is the diradical of 1,9- diaminononane or 2 -methyl- 1,8-diaminooctane. As used herein, the diaradical of a diamine is the diradical that is formed from removal of the two amine (-NFh) groups. For example, the diradical of 1,4-diaminobutane is represented by the formula: *-(ϋ¼)4-*, where “*” denotes a bond to the explicit -NH- group in formula (1).

Of course, in some embodiments, the polyamide (PA) can include one or more additional recurring units (R*_PA_I), where i runs from 1 to the number of additional recurring units. In some such embodiments, each additional recurring unit (R*_PA_I) is represented by a formula (1) and is distinct from each other and from recurring unit (R_PA). In some such embodiment, the polyamide (PA) includes recurring units (R_PA) and (R*_PA_I). In one embodiment, -Ri- in recurring unit (R_PA) is a C9 alkyl and -Ri- in recurring unit (R*_PA_I) is a distinct C9 alkyl. In some embodiments, -Ri- in recurring unit (R_PA) is the diradical of 1,9-diaminononane and -Ri- in recurring unit (R*_PA_I) is the diradical of 2-methyl- 1,8-diaminooctane. In one such embodiment, Ri, at each location in recurring unit (R_PA) and (R*_PA_I), is a hydrogen. In some embodiments, in which the polyamide (PA) includes one or more additional recurring units (R*_PA_I) according to formula (1), the total concentration of recurring unit (R_PA) and additional recurring units (R*_PA_I) is within the range given above for recurring unit (R_PA). In alternative such embodiments, the concentration of each recurring unit (R_PA) and (R*_PA_I) is independently within the range given above for recurring unit (RPA). In some embodiments, the concentration of the semi -aromatic, semi-crystalline polyamide (PA) in the polymer composition (PC) is at least 40 wt.%, is at least 60 wt.%, at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, at least 80 wt.%, at least 85 wt.% or at least 90 wt.%. In some embodiments, the concentration of the semi-aromatic, semi -crystalline polyamide (PA) in the polymer composition (PC) is no more than 95 wt.%, no more than 80 wt.%, no more than 70 wt.%, no more than 60 wt.%, no more than 50 wt.% or no more than 60 wt.%. In some embodiments, the semi-aromatic, semi-crystalline polyamide (PA) concentration is from at least 60 wt.% to 95 wt.%, from 70 wt.% to 95 wt.%, from 80 wt.% to 95 wt.% or from 85 wt.% to 95 wt.%.

In some embodiments, the semi-aromatic, semi-crystalline polyamide (PA) has a melting temperature (“Tm”) of at least 170° C, at least 190° C, at least 200° C, at least 210° C, at least 220° C, at least 230° C, at least 240° C, or at least 250° C. In some embodiments the semi-aromatic, semi-crystalline polyamide (PA) has a Tm of no more than 400° C, no more than 390° C, no more than 380° C, no more than 370° C, no more than 360° C, or no more than 350° C. In some embodiments the semi-aromatic, semi-crystalline polyamide (PA) has a Tm of from 170° C to 400° C, from 190° C to 400° C, from 200° C to 400° C, from 210° C to 390° C, from 220° C to 380° C, from 230° C to 370° C, from 240° C to 360° C or from 250° C to 350° C. Tm can be measured according to ASTM D3418.

In some embodiments, the semi-aromatic, semi -crystalline polyamide (PA) has a glass transition temperature (“Tg”) of at least 50° C, at least 60° C, at least 100° C, at least 120° C, at least 130° C, or at least 140° C. In some embodiment, the semi -aromatic, semi-crystalline polyamide (PA) has a Tg of no more than 190° C, no more than 180° C, no more than 170° C, or no more than 165° C. In some embodiments, the semi-aromatic, semi-crystalline polyamide (PA) has a Tg of from 50° C to 190° C, from 60° C to 190° C, from 100° C to 190° C, from 110° C to 190° C, 120° C to 190° C, from 130° C to 180° C, from 130° C to 170° C, from 140° C to 170° C, from 145° C to 170° C, or from 145° C to 165° C.

In some embodiments, the semi-aromatic, semi-crystalline polyamide (PA) has a number average molecular weight (“Mn”) ranging from 1,000 g/mol to 40,000 g/mol, for example from 2,000 g/mol to 35,000 g/mol, from 4,000 to 30,000 g/mol, or from 5,000 g/mol to 20,000 g/mol. Mn can be determined by gel permeation chromatography (GPC) using ASTM D5296 with polystyrene standards. The Fluoroelastomer

As used herein, the term “fluoroelastomer” designates a fluoropolymer resin serving as a base constituent for obtaining a true elastomer, the fluoropolymer resin including more than 10 wt.%, preferably more than 30 wt.%, of recurring units derived from at least one ethylenically unsaturated monomer comprising at least one fluorine atom (hereafter, (per)fluorinated monomer) and, optionally, recurring units derived from at least one ethylenically unsaturated monomer free from fluorine atom (hereafter, hydrogenated monomer), where wt.% is relative to the total weight of the fluoroelastomer.

True elastomers are defined by the ASTM, Special Technical Bulletin, No. 184 standard as materials capable of being stretched, at room temperature, to twice their intrinsic length and which, once they have been released after holding them under tension for 5 minutes, return to within 10 % of their initial length in the same time.

Fluoroelastomer (A) is, in general, an amorphous product or a product having a low degree of crystallinity (crystalline phase less than 5 % by volume) and a glass transition temperature (“T_g”) below room temperature. In most cases, the fluoroelastomer (A) has advantageously a T_g below 10° C, preferably below 5° C, more preferably 0° C, even more preferably below -5° C.

In some embodiments, fluoroelastomer (A) includes at least 15 mol%, preferably at least 20 mol%, more preferably at least 35 mol% of recurring units derived from vinylidene fluoride (“VDF”). In some embodiments, fluoroelastomer (A) includes no more than 85 mol%, preferably no more than 80 mol%, more preferably no more 78 mol% of recurring units derived from VDF. In some embodiments, the fluoroelastomer (A) includes from 15 mol% to 85 mol%, from 20 mol% to 80 mol%, from 35 mol% and 78 mol% of recurring units derived from VDF.

Suitable (per)fluorinated monomers, include, but are not limited to:

(a) C2-C8 perfluoroolefins , such as tetrafluoroethylene (“TFE”) and hexafluoropropylene (“HFP”);

(b) hydrogen-containing C2-C8 olefins different from VDF, such as vinyl fluoride (“VF”), trifluoroethylene (“TrFE”), perfluoroalkyl ethylenes of formula CFh = CH-R_f, wherein R_f is a Ci- C₆ perfluoroalkyl group;

(c) C2-C8 chloro and/or bromo and/or iodo-fluoroolefms such as chlorotrifluoroethylene (“CTFE”); (d) (per)fluoroalkylvinylethers (“PAVE”) of formula CF₂=CFOR_f, wherein R_f is a C₁-C₆ (per)fluoroalkyl group, e.g. CF₃, C₂F₅, C₃F₇;

(e) (per)fluoro-oxy-alkylvinylethers of formula CF₂ = CFOX, wherein X is a C₁-C₁₂ ((per)fluoro)-oxyalkyl comprising catenary oxygen atoms, e.g. the perfluoro-2-propoxypropyl group;

(f) (per)fluorodioxoles having formula :

wherein each of Rf3, Rf4, Rf5, Rf6, equal or different each other, is independently a fluorine atom, a C1-C6 fluoro- or per(halo)fluoroalkyl, optionally comprising one or more oxygen atom, e.g. - CF₃, -C2F5, -C₃F7, -OCF₃, -OCF2CF2OCF₃; and

(g) (per)fluoro-methoxy-vinylethers (“MOVE”) having formula:

CFX₂ = CX₂OCF₂OR"_f, wherein R"_f is selected among C₁-C₆ (per)fluoroalkyls , linear or branched; C₅-C₆ cyclic (per)fluoroalkyls; and C₂-C₆ (per)fluorooxyalkyls, linear or branched, comprising from 1 to 3 catenary oxygen atoms, and X₂ = F, H; preferably X₂ is F and R"r is -CF₂CF₃ (“MOVE1”); - CF₂CF₂OCF₃ (“MOVE2”); or -CF (“MOVE3”).

In some embodiments, fluoroelastomer (A) includes recurring units derived from VDF and HFP. In some such embodiments, fluoroelastomer (A) further includes recurring units derived from TFE.

In some embodiments, fluoroelastomer (A) may further include recurring units derived from one or more than one monomer free from fluorine (“hydrogenated monomer”). Desirably hydrogenated monomers include, but are not limited to, C₂-C₈ non-fluorinated olefins (01), in particular C₂-C₈ non-fluorinated alpha-olefins (01), including ethylene, propylene, 1 -butene; diene monomers; styrene monomers; C₂-C₈ non-fluorinated alpha-olefins (01), and more particularly ethylene and propylene, will be selected for achieving increased resistance to bases.

In some embodiments, fluoroelastomer (A) includes recurring units derived from at least one bis-olefm [bis-olefm (OF)] having general formula:

wherein Ri, R₂, R₃, R₄, Rs and R₆, equal or different from each other, are H, a halogen, or a Ci- C5 optionally halogenated group, possibly comprising one or more oxygen group; Z is a linear or branched C1-C18 optionally halogenated alkylene or cycloalkylene radical, optionally containing oxygen atoms, or a (per)fluoropolyoxyalkylene radical, e.g. as described in EP 661304 A (AUSIMONT SPA) 5/07/1995, incorporated herein by reference .

The bis-olefm (OF) is preferably selected from the group consisting of those complying with formulae (OF-1), (OF-2) and (OF-3):

(OF-1)

wherein j is an integer between 2 and 10, preferably between 4 and 8, and Ri, R₂, R₃, R₄ equal or different from each other, are H, F or C1-C5 alkyl or (per)fluoroalkyl group;

(OF-2)

wherein each of A, equal or different from each other and at each occurrence, is independently selected from F, Cl, and H; each of B, equal or different from each other and at each occurrence, is independently selected from F, Cl, H and OR_B, wherein R_B is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atom, optionally fluorinated, which may be inserted with ether linkages; preferably E is a -(CF2)_m- group, with m being an integer from 3 to 5; a preferred bis-olefm of (OF-2) type is F2C=CF-0-(CF2)5-0-CF=CF2.

(OF-3)

wherein E, A and B have the same meaning as above defined; Rs, R₆, R₇, equal or different from each other, are H, F or C1-C5 alkyl or (per)fluoroalkyl group.

In some embodiments, fluoroelastomer (A) suitable include, in addition to recurring units derived from VDF and HFP, one or more of the followings:

- recurring units derived from at least one bis-olefin [bis-olefm (OF)] as above detailed;

- recurring units derived from at least one (per)fluorinated monomer different from VDF and HFP ( e.g . TFE); and

- recurring units derived from at least one hydrogenated monomer.

Among specific monomer compositions of fluoroelastomer (A) suitable for the purpose of the invention, mention can be made of fluoroelastomers having the following monomer compositions (in mol %) :

(i) vinylidene fluoride (VDF) 35-85 %, hexafluoropropene (HFP) 10-45 %, tetrafluoroethylene (TFE) 0-30 %, perfluoroalkyl vinyl ethers (PAVE) 0-15 %, bis-olefin (OF) 0- 5 %;

(ii) vinylidene fluoride (VDF) 50-80 %, perfluoroalkyl vinyl ethers (PAVE) 5 50 %, tetrafluoroethylene (TFE) 0-20 %, bis-olefin (OF) 0-5 %;

(iii) vinylidene fluoride (VDF) 20-30 %, C2-C8 non-fluorinated olefins (01) 10 30 %, hexafluoropropene (HFP) and/or perfluoroalkyl vinyl ethers (PAVE) 18-27 %, tetrafluoroethylene (TFE) 10-30 %, bis-olefm (OF) 0-5 %;

(vii) tetrafluoroethylene (TFE) 33-75 %, perfluoroalkyl vinyl ethers (PAVE) 15 45 %, vinylidene fluoride (VDF) 5-30 %, hexafluoropropene HFP 0-30 %, bis-olefin (OF) 0-5 %;

(viii) vinylidene fluoride (VDF) 35-85 %, fluorovinyl ethers (MOVE) 5-40 %, perfluoroalkyl vinyl ethers (PAVE) 0-30 %, tetrafluoroethylene (TFE) 0-40 %, hexafluoropropene (HFP) 0-30 %, bis-olefm (OF) 0-5 %.

In some embodiments, the fluoroelastomer (FE) has a fluorine content of at least 60 wt.%, at least 63 wt.%, at least 66 wt.%, at least 67 wt.%, at least 68 wt.% or at least 69 wt.%. Fluorine content can be calculated from the monomer composition determined by nuclear magnetic resonance (“NMR”) spectroscopy.

The concentration of the fluoroelastomer (FE) in the polymer composition (PC) is from 1 wt.% to 40 wt.%. In some embodiments, the concentration of the fluoroelastomer in the polymer composition (PC) is from 2 wt.% to 40 wt.%, from 3 wt.% to 40 wt.%, from 5 wt.% to 40 wt.%, from 5 wt.% to 35 wt.% or from 7 wt.% to 35 wt.%. It was surprisingly discovered that when the concentration of the fluoroelastomer (FE) in the polymer composition (PC) was from 1 wt.% to 15 wt.%, the polymer composition (PC) had increased tensile strength and tensile elongation, relative the polymer compositions (PC) having higher concentrations of the fluoroelastomer (FE). In some such embodiments, the concentration of the fluoroelastomer (FE) in the polymer composition (PC) is from 2 wt.% to 15 wt.%, from 3 wt.% to 15 wt.%, from 4 wt.% to 15 wt.%, from 5 wt.% to 15 wt.%, from 2 wt.% to 12 wt.%, from 3 wt.% to 12 wt.%, from 4 wt.% to 12 wt.% or from 5 wt.% to 12 wt.%.

Optional Components

The polymer composition (PC) optionally includes, in addition to the polyamide (PA) and fluoroelastomer (FE), one or more additives including, but not limited to, reinforcing fillers (e.g. carbon black), acid scavengers, thickeners, pigments, antioxidants, stabilizers and the like.

Reinforcing fillers include, but are not limited to carbon black and carbon fibers. When carbon black is used as a reinforcing filler, it’s concentration is at least 10, preferably at least 15, more preferably at least 20 weight parts; and/or at most 50, preferably at most 45, more preferably at most 40 weight parts per 100 weight parts of the fluoroelastomer (FE).

With respect to carbon fibers, the term includes graphitized, partially graphitized, and ungraphitized carbon reinforcing fibers or a mixture thereof. The carbon fibers can be obtained by heat treatment and pyrolysis of different polymer precursors such as, for example, rayon, polyacrylonitrile (PAN), aromatic polyamide or phenolic resin; carbon fibers may also be obtained from pitchy materials. The term “graphite fiber” is intended to denote carbon fibers obtained by high temperature pyrolysis (over 2000°C) of carbon fibers, wherein the carbon atoms place in a way similar to the graphite structure. The carbon fibers are preferably chosen from the group consisting of PAN-based carbon fibers, pitch based carbon fibers, graphite fibers, and mixtures thereof.

When glass fibers or carbon fibers are present in the polymer composition (PC), the concentration is less than 50 wt. %, more preferably less than 45 wt. %, even more preferably less than 42 wt. %, most preferably less than 40 wt. %). Additionally or alternatively, in some embodiments, the concentration of the carbon fibers is at least 8 wt. %, preferably at least 10 wt. %, preferably at least 12 %, most preferably at least 15 wt. % of reinforcing filler. In some embodiments, the polymer composition (PC) includes at least one additive different from the reinforcing filler and selected from the group consisting of (i) colorants such as a dye (ii) pigments such as titanium dioxide, zinc sulfide and zinc oxide (iii) light stabilizers, e.g. UV stabilizers, (iv) heat stabilizers, (v) antioxidants such as organic phosphites and phosphonites, (vi) acid scavengers, (vii) processing aids, (viii) nucleating agents, (ix) internal lubricants and/or external lubricants, (x) flame retardants, (xi) smoke-suppressing agents, (x) anti-static agents, (xi) anti-blocking agents, (xii) conductivity additives such as carbon black and carbon nanofibrils, (xiii) plasticizers, (xiv) flow modifiers (xv), extenders, (xvi) metal deactivators and (xvii) flow aid such as silica. In some embodiments including the aforementioned additives, the total concentration of additives is less than 5 wt.%.

As noted above, the fluoroelastomer (FE) is not cured. Accordingly, the polymer composition (PC) is free of any crosslinking agents. More specifically, the polymer composition (PC) contains free of any crosslinking agent normally used for ionic-curable or for peroxide- curable fluoroelastomers. Though the fluoroelastomer (FE) can be ionic curable, the polymer composition (PC) is free of any typical ionic crosslinking agents, such as aromatic or aliphatic polyhydroxylated compounds, or derivatives thereof. Similarly, though the fluoroelastomer (FE) can be peroxide curable, the polymer composition (PC) is free of any radical cross-linking agents. More specifically, the polymer composition (PC) is free of any peroxide that is capable of generating radicals by thermal decomposition. Still further, the polymer composition (PC) is free of any curing co-agent, such as triallyl cyanurate, or triallyl isocyanurate (TAIC) or others. As used with respect to crosslinking agents and curing co-agent, “free of’ refers to a total crosslinking agent and curing co-agent concentration, relative to the number of parts of the fluoroelastomer (FE), of no more than no more than I phr or no more than 0.5 phr.

The polymer composition (PC) is also free of metal hydroxides. Metal hydroxides are generally incorporated into polymer compositions as a curing accelerant for ionic-curable fluoroelastomers. Metal hydroxides for use in curing include, but are not limited to, alkali metal hydroxides (e.g. Ca(OH)2), Sr(OH)2 and Ba(OH)2. However, it was surprisingly found that incorporation of the metal hydroxides into the polymer composition (PC) has a significant deleterious effect on tensile elongation at break and notched impact strength. Furthermore, the presently described polymer compositions (PC) are uncured. Accordingly, in some embodiments, the polymer composition (PC) is free of metal hydroxides. As used herein with respect to metal hydroxides, “free of’ refers to a total metal hydroxide concentration, relative to the number of parts of the fluoroelastomer (FE), of less than 2 phr, less than 1 phr, or less than 0.5 phr. In some embodiments, the total metal hydroxide concentration is 0 phr.

Similarly, in some embodiments, the polymer composition (PC) has a total accelerant concentration, relative to the . Accelerants include, but are not limited to organic P, As, Se or S- onium compound, amino-phosphonium derivatives, phosphoranes, and diphosphine-iminium compounds. Examples of accelerants include, but are not limited to: quaternary ammonium or phosphonium salts as notably described in EP 335705 A (MINNESOTA MINING) 4/10/1989 and US 3876654 (DUPONT) 8/04/1975 ; aminophosphonium salts as notably described in US 4259463 (MONTEDISON SPA) 31/03/1981 ; phosphoranes as notably described in US 3752787 (DUPONT) 14/08/1973 ; diphosphine-iminium compounds as described in EP 0120462 A (MONTEDISON SPA) 3/10/1984 or as described in EP 0182299 A (ASAHI CHEMICAL) 28/05/1986; each of the foregoing incorporated herein by reference.

Similarly, in some embodiments, the polymer composition (PC) is free of metal oxides. Metal oxides are used in polymer compositions as a HF scavenger for ionic-curable fluoroelastomers. Metal oxides include, but are not limited to, ZnO, CaO, BaO, MgO, PbO, and Na₂0.

All features described above for the components of the polymer compositions (PC) are equally features of corresponding components of the methods for making the polymer composition (PC)

METHODS OF MAKING THE POLYMER COMPOSITIONS (PC)

Also described herein are making the polymer composition (PC). In general, the polymer composition (PC) can be made by methods known in the art. In general, the method for making the polymer composition (PC) includes melt-blending the polyamide (PA), the fluoroelastomer (FE) and any optional components, for example, a filler, a toughener, a stabilizer, and of any other optional additives.

Any melt-blending method may be used for mixing polymeric ingredients and non polymeric ingredients in the context of the present invention. For example, polymeric ingredients and non-polymeric ingredients may be fed into a melt mixer, such as single screw extruder or twin screw extruder, agitator, single screw or twin screw kneader, or Banbury mixer, and the addition step may be addition of all ingredients at once or gradual addition in batches. When the polymeric ingredient and non-polymeric ingredient are gradually added in batches, a part of the polymeric ingredients and/or non-polymeric ingredients is first added, and then is melt-mixed with the remaining polymeric ingredients and non-polymeric ingredients that are subsequently added, until an adequately mixed composition is obtained. If a reinforcing agent presents a long physical shape (for example, a long glass fiber), drawing extrusion molding may be used to prepare a reinforced composition.

Notably, the fluoroelastomer (FE) is an uncured fluoroelastomer (FE). In general, fluoroelastomers are cured. More particularly, as explained above, fluoroelastomers are generally heated to a temperature of at least 155° C in the presence of curing agents (including accelerants) to crosslink the fluoroelastomer. The methods of making the polymer compostions (PC) are free of such steps.

ARTICLES

The polymer composition (PC) can be desirably incorporated into articles. As noted above, due at least in part to the improved mechanical properties, improved mechanical aging performance and desirable chemical resistance, the polymer compositions can be desirably incorporated into articles exposed to elevated temperatures or fuel (or fumes thereof) that require flexibility. In some embodiments, the article is a tube, for example, for automotive applications or oil and gas production, namely where significant mechanical strength, mechanical heat aging performance and chemical resistance is required.

In embodiments in which the polymer composition (PC) is incorporated into a flexible tube, the tube can include the polymer composition (PC) as a layer. In some embodiments, the layer formed from the polymer composition is the sole layer. In alternative embodiments, the layer formed from the polymer composition (PC) is one of a plurality of layers of the tube, for example, an innermost layer, an outermost layer or a layer between the innermost and outermost layer. Preferably, regardless of the number of tube layers, the layer formed from the polymer composition (PC) is in contact with oil or liquefied hydrocarbons, or vapors thereof, ( e.g . kerosene, petrol, diesel, liquefied propene, liquefied butane and liquefied natural gas) when the tube is in normal operation. In some embodiments, the tube is selected from a fuel hose, a down-hole pipe for subterranean (including sub-sea) oil or gas extraction. In some embodiments, the tube is a flexible riser or a marine umbilical. A marine umbilical is a flexible tube used to transport materials and information between a control or processing facility (such as a platform or surface vessel) and an undersea oil wellhead. In general, the articles can be formed from methods known in the art. Preferably, the articles ( e.g . tubes) are formed by extrusion. As noted above, the viscosity of the polymer composition (PC) is particularly suited for extrusion.

EXAMPLES

The examples demonstrate the processability and mechanical performance of the polymer compositions described herein.

For the examples, the following components were used.

Polyamide: “PA9T” obtained from Kuraray under the trade name Genestar® and derived from the polycondensation of the terephthalic acid, 1,9-diaminononane and 2-methyl- 1,8- diaminooctane.

Fluroelastomer 1 (“FE1”): A bisphenol curable fluoroelastomer (copolymer with 66% of fluorine), obtained from Solvay Specialty Polymers Italy S.p. A under the trade name Tecnoflon® N535.

Fluoroelastomer 2 (“FE2”): A peroxide curable fluoroelastomer (terpolymer with 70% of fluorine), obtained from Solvay Specialty Polymers Italy S.p. A. under the trade name Tecnoflon® P549L.

Fluoroelastomer 3 (“FE3”): A bisphenol curable fluoroelastomer (terpolymer with 70% of fluorine), obtained from Solvay Specialty Polymers Italy S.p. A. under the trade name Tecnoflon® T439.

Example 1 - Processability

This example demonstrates the processability of the polymer compositions.

To demonstrate performance, 13 samples were formed. For each sample composition, 50 wt.% to 100 wt.% of PA and 10 wt.% to 50 wt.% of either FE1 , FE2 or FE3 were melt compounded and extruded in a 26 mm twin-screw, co-rotating extruder. In particular, for each sample composition, the fluoroelastomer and polyamide pellets were fed into a Coperion ZSK26 twin- screw extruder and processed at a temperature of 290° C. The extruded strands were cooled and pelletized into pellets having a length of 2 mm to 3 mm to form the sample compositions. The sample compositions and processing performance results are displayed in Table 1. In Table 1, instability indicates high die swelling during extrusion. High die swelling indicates significant phase separation of the polyamide and the fluoroelastomer (FE1 to FE3). Furthermore, as used in the Table 1, and throughout the Examples, Έ” refers to an example and “C” refers to a counter example.

TABLE 1

Referring to Table 1, the samples having greater than 40 wt.% fluoroelastomer content had significant instability, while samples having less than 40 wt.% fluoroelastomer were stably processed. For example, samples C2 to C4, including 50 wt.% fluoroelastomer had significant instability while samples El to E9, having from 10 wt.% to 35 wt.% fluoroelastomer were stably processed. Fig. 1 and Fig. 2 are scanning electron microscopy (“SEM”) images of, respectively, samples E2 and C2 after processing. Referring to the figures, C2 shows a blend with significant heterogeneities, relative to E3. The significant heterogeneity in C2 leads to the processing instability observed during sample formation. Example 2 - Mechanical Performance

This example demonstrates the mechanical performance of the polymer compositions.

To demonstrate performance, testing bars were formed from the sample compositions shown in Table 1. In particular, pellets of sample compositions were molded into ASTM D638 tensile bars. Tensile properties (modulus, strength at break and elongation at break) were measured according to ASTM D638. Notched impact testing was performed according to ASTM D256. Table 2 displays the results of mechanical testing.

TABLE 2

Referring to Table 2, the polymer compositions including a fluoroelastomer had significantly improved elongation and notched impact strength, relative to the polyamide alone. For example, El to E3 had about a 230% to about 1200% increase in elongation at break and about a 80% to about 1500% increase in notched impact strength, relative to polyamide alone. Moreover, PA/FE blends having 10 wt.% fluoroelastomer (El, E4 and E7) had similar or increased tensile strength relative to polyamide alone. Still further, comparison of the tensile moduli demonstrate that El to E2 had improved flexibility relative to Cl.

Example 3 - Heat Aging and Chemical Resistance The present example demonstrates the heat aging performance and chemical resistance of the polymer compositions.

To demonstrate heat aging performance and chemical resistance, ASTM D648 tensile bars were formed from several of the sample compositions displayed in Table 1. Tensile properties were tested as described above in Example 2, prior to and after heat aging in air at 125° C for 500 hours. Results of heat aging performance are shown in Table 3.

TABLE 3

* Reproduced from Table 2. Surprisingly, for the samples tested, the polymer compositions including a fluoroelastomer had increased tensile strength after heat aging, relative to the polyamide alone. For example, samples El to E9 all had increased tensile strength after heat aging. On the other hand, Cl exhibited a decrease in tensile strength after heat gaining. Furthermore, though samples E2, E4, and E8 had similar or lower initial tensile strength relative to Cl, E2, E4 and E8 had similar or increased tensile strength after heat aging relative to C 1. With respect to tensile elongation, though samples El to E4 and E6 to E9 had reduced elongation at break after heat aging, the final tensile elongation at break was still significantly increased relative to that of Cl. Similar results were observed for the notched impact strength. With respect to tensile modulus, El to E9 all had superior flexibility (lower tensile modulus) relative to Cl after heat aging.

To demonstrate chemical resistance, again ASTM D648 tensile bars were formed from several of the sample compositions displayed in Table 1. The tensile bars were immersed in diesel fuel in a closed vessel for 30 days. The diesel fuel was maintained at a temperature of 125° C. Results of chemical resistance testing are shown in Table 4.

TABLE 4

Referring to Table 4, it was surprisingly found that there was not a significant difference in the diesel fuel uptake of PA/FE blends and polyamides. Notably, the uptake values in Table 4 have an uncertainty of about ± 1%. Accordingly, within error, the uptake values in Table 4 are comparable. Example 4 - Rheological Performance The present example demonstrates the rheological performance of the polymer compositions.

To demonstrate performance, the apparent viscosities of Cl and El at 290° C, using a Dynisco capillary rheometer (LCR 7001), equipped with a circular die having a 1 mm diameter, a length/diameter ratio of 20 and a cone angle of 120° C. Results of the rheological testing are displayed in Table 5.

TABLE 5

Referring to Table 5, the polymer composition including the fluoroelastomer maintained desirable apparent viscosity over the range of shear rates tested. Notably, the polymer composition having a fluoroelastomer had apparent viscosities that are desirable for pipe ( e.g . tube) extrusion.

Example 5 - Effect of Metal Hydroxides The present example demonstrates the effect of metal hydroxides on the polymer compositions described herein.

To demonstrate performance, a further counter example, CE5 was prepared. CE5 was identical to E2, except for the inclusion of 6 phr of Ca(OH)2 (metal hydroxide) in CE5. More particularly, CE5 consisted of 75 wt.% PA, 25 wt.% FE1 and 5.5 wt.% of Ca(OH)2. Tensile elongation and impact properties were tested as described above. The results of tensile and impact properties are displayed in Table 6. TABLE 6

Referring to Table 6, surprisingly the sample including a metal hydroxide had significantly reduced tensile elongation at break and notched impact strength, relative the sample without the metal hydroxide. For example, C5 had about a 55% reduction in tensile elongation at break and a 25% reduction in notched impact strength, relative to E2.

The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognized that changes can be made in form and detail without departing from the spirit and scope of the invention. Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein.

Claims

1. A polymer composition (PC) comprising:

- a semi-aromatic, semi-crystalline polyamide (PA) having a recurring unit (RPA) represented by the following formula:

wherein Ri is selected from the group consisting of a C₄ - C₁₅ alkyl and Ri, at each location, is selected from the group consisting of a hydrogen, a halogen, a C₁-C₁₂ alkyl, a C7-C24 alkylaryl, a C7-C24 aralkyl, a C₆-C24 arylene, a C1-C12 alkoxy, and a C6-C18 aryloxy,

- 1 wt.% to 40 wt.%, relative to the total weight of the polymer composition (PC), of an uncured fluoroelastomer (FE), and

- 0 parts per hundred (“phr”) to no more than 5 phr of a metal hydroxide, wherein phr is relative to the number of parts of the fluoroelastomer (FE).

2. The polymer composition (PC) of claim 1, wherein -Ri- in recurring unit (RPA) is a C9 alkyl.

3. The polymer composition (PC) of either claim 1 or 2, wherein -Ri- in recurring unit (RPA) is a diradical of 1,9-diaminononane.

4. The polymer composition (PC) of any one of claims 1 to 3, wherein the polyamide (PA) comprises an additional recurring unit (R*PA) that is distinct from (RPA) and represented by a formula (1).

5. The polymer composition (PC) of claim 4, wherein -Ri- in recurring unit (R*PA) is a diradical of 2-methyl-l,8-diaminooctane.

6. The polymer composition (PC) of any one of claims 1 to 5, wherein the uncured fluoroelastomer (FE) is a vinylidene fluoride copolymer.

7. The polymer composition (PC) of any one of claims 1 to 6, wherein the uncured fluoroelastomer (FE) comprises a fluorine content of at least 60 wt.%, preferably at least 68 wt.%, as determined by nuclear magnetic resonance (“NMR”) spectroscopy.

8. The polymer composition (PC) of any one of claims 1 to 9, wherein the uncured fluoroelastomer (FE) concentration is from 1 wt.% to 15 wt.%, relative to the total weight of the polymer composition (PC).

9. The polymer composition (PC) of any one of claims 1 to 8, wherein the a semi -aromatic, semi-crystalline polyamide (PA) concentration is from 60 wt.% to 95 wt.%, relative to the total weight of the polymer composition (PC).

10. The polymer composition (PC) of any one of claims 1 to 9, comprising a tensile elongation at break of from 1% to 80% and a tensile modulus of from 1.0 GPa to 2.2 GPa.

11. The polymer composition (PC) of any one of claims 1 to 10, comprising a notched impact strength of at least 100 J/m.

12. The polymer composition (PC) of any one of claims 1 to 11, comprising an apparent viscosity of at least 1000 Pa s at a shear of 1 s ¹ to 100 s ¹ and a temperature of 290° C

13. The polymer composition (PC) of any one of claims 1 to 12, comprising a tensile strength of at least 50 MPa.

14. A tube comprising a layer comprising the polymer composition (PC) of any one of claims 1 to 13.

15. The tube of claim 14, wherein the tube is a flexible riser.