FLUOROELASTOMER CURABLE COMPOSITION

Abstract

The invention pertains to certain fluoroelastomer compositions including given amounts of certain aromatic polyamide-imide polymers, having ability to adhere upon curing to various substrates, to a process for their manufacture, to a method for fabricating shaped articles comprising curing the said compositions, to cured articles therefrom, and to assemblies including a substrate and said cured articles.

Claims

1. A composition comprising: at least one fluoroelastomer (A), wherein fluoroelastomer (A) is a (per)fluoroelastomer; at least one cross-linking system; and at least one polymer (PAI), wherein polymer (PAI) is an aromatic polyamide-imide polymer, said polymer (PAI) being present in an amount of at least 0.5 phr, and at most 30.0 phr, with respect to the fluoroelastomer (A).

2. The composition (C) of claim 1, wherein said fluoroelastomer (A) comprises recurring units derived from at least one (per)fluorinated monomer, wherein said (per)fluorinated monomer is selected from the group consisting of: C.sub.2-C.sub.8 fluoro- and/or perfluoroolefins; C.sub.2-C.sub.8 hydrogenated monofluoroolefins, such as vinyl fluoride; 1,2-difluoroethylene, vinylidene fluoride (VDF) and trifluoroethylene (TrFE); (per)fluoroalkylethylenes complying with formula CH.sub.2CHR.sub.f0, in which R.sub.f1 is a C.sub.1-C.sub.6 (per)fluoroalkyl or a C.sub.1-C.sub.6 (per)fluorooxyalkyl having one or more ether groups; chloro- and/or bromo- and/or iodo-C.sub.2-C.sub.6 fluoroolefins; fluoroalkylvinylethers complying with formula CF.sub.2CFOR.sub.f1 in which R.sub.f1 is a C.sub.1-C.sub.6 fluoro- or perfluoroalkyl; hydrofluoroalkylvinylethers complying with formula CH.sub.2CFOR.sub.f1 in which R.sub.f1 is a C.sub.1-C.sub.6 fluoro- or perfluoroalkyl; fluoro-oxyalkylvinylethers complying with formula CF.sub.2CFOX.sub.0, in which X.sub.0 is a C.sub.1-C.sub.12 oxyalkyl, or a C.sub.1-C.sub.12 (per)fluorooxyalkyl having one or more ether groups; functional fluoro-alkylvinylethers complying with formula CF.sub.2CFOY.sub.0, in which Y.sub.0 is a C.sub.1-C.sub.12 alkyl or (per)fluoroalkyl, or a C.sub.1-C.sub.12 oxyalkyl or a C.sub.1-C.sub.12 (per)fluorooxyalkyl, said Y.sub.0 group comprising a carboxylic or sulfonic acid group, in its acid, acid halide or salt form; (per)fluorodioxoles, of formula: ##STR00025## wherein each of R.sub.f3, R.sub.f4, R.sub.f5, R.sub.f6, equal to or different from each other, is independently a fluorine atom, a C.sub.1-C.sub.6 fluoro- or per(halo)fluoroalkyl, optionally comprising one or more oxygen atom.

3. The composition (C) of claim 1, wherein said fluoroelastomer (A) is selected from: (1) VDF-based copolymers, in which VDF is copolymerized with at least one additional comonomer selected from the group consisting of: (a) C.sub.2-C.sub.8 perfluoroolefins; (b) hydrogen-containing C.sub.2-C.sub.8 fluorinated olefins; (c) C.sub.2-C.sub.8 fluoroolefins comprising at least one of iodine, chlorine and bromine; (d) (per)fluoroalkylvinylethers (PAVE) of formula CF.sub.2CFOR.sub.f, wherein R.sub.f is a C.sub.1-C.sub.6 (per)fluoroalkyl group; (e) (per)fluoro-oxy-alkylvinylethers of formula CF.sub.2CFOX, wherein X is a C.sub.1-C.sub.12 ((per)fluoro)-oxyalkyl comprising catenary oxygen atoms; (f) (per)fluorodioxoles having formula: ##STR00026## wherein each of R.sub.f3, R.sub.f4, R.sub.f5, R.sub.f6, equal to or different from each other, is independently selected from the group consisting of fluorine atom and C.sub.1-C.sub.6 (per)fluoroalkyl groups, optionally comprising one or more than one oxygen atom; (g) (per)fluoro-methoxy-vinylethers having formula:
CF.sub.2CFOCF.sub.2OR.sub.f2 wherein R.sub.f2 is selected from the group consisting of C.sub.1-C.sub.6 (per)fluoroalkyls; C.sub.5-C.sub.6 cyclic (per)fluoroalkyls; and C.sub.2-C.sub.6 (per)fluorooxyalkyls, comprising at least one catenary oxygen atom; (h) C.sub.2-C.sub.8 non-fluorinated olefins (Ol); and (2) TFE-based copolymers, in which TFE copolymerized with at least one additional comonomer selected from the group consisting of (c), (d), (e), (g), (h) and (i) as above detailed.

4. The composition (C) of claim 1, wherein fluoroelastomer (A) comprises at least one of chlorine, iodine and bromine cure sites, in an amount such that the chloride, iodine and bromine content in the fluoroelastomer (A).

5. The composition (C) according to claim 1, wherein polymer (PAI) is selected from the group consisting of polymers comprising more than 50% by moles of recurring units (R.sub.PAI), wherein recurring units (R.sub.PAI) comprise at least one aromatic ring, at least one imide group, as such and/or in its amic acid form, and at least one amide group which is not included in the amic acid form of an imide group, which are selected from the group consisting of units of any of formulae (R.sub.PAI-a) and (R.sub.PAI-b): ##STR00027## wherein: Ar is a trivalent aromatic group; and R is a divalent aromatic group. ##STR00028##

6. The composition (C) of claim 5, wherein said recurring units (R.sub.PAI) are selected from recurring units (l), (m) and (n), in their amide-imide (a) or amide-amic acid (b) forms: ##STR00029## wherein the attachment of the two amide groups to the aromatic ring as shown in (l-b) represents the 1,3 and the 1,4 polyamide-amic acid configurations; ##STR00030## wherein the attachment of the two amide groups to the aromatic ring as shown in (m-b) represents the 1,3 and the 1,4 polyamide-amic acid configurations; and ##STR00031## wherein the attachment of the two amide groups to the aromatic ring as shown in (n-b) represents the 1,3 and the 1,4 polyamide-amic acid configurations.

7. The composition (C) according to claim 1, which comprises said polymer (PAI) in an amount of at least 1.0 phr and at most 25.0 phr, with respect to the fluoroelastomer (A).

8. The composition (C) according to claim 1, said at least one cross-linking system is a peroxide-based cross-linking system comprising at least one organic peroxide (O) and at least one polyunsaturated compound (U), and wherein said peroxide (O) is selected from the group consisting of: di(alkyl/alryl) peroxides, percarboxylic acids and esters, peroxycarbonates ketone peroxides organic hydroperoxides, and oil-soluble azo initiators.

9. The composition (C) of claim 8, wherein the amount of peroxide (O) in the composition (C) is of 0.1 to 15 phr, relative to 100 weight parts of fluoroelastomer (A).

10. The composition (C) according to claim 8, wherein compound (U) is selected from the group consisting of: compounds (U) comprising two carbon-carbon unsaturations, which are selected from the group consisting of bis-olefins (OF) having general formula: ##STR00032## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6, equal or different from each other, are H or C.sub.1-C.sub.5 alkyl; Z is a linear or branched C.sub.1-C.sub.18 (hydro)carbon radical (including alkylene or cycloalkylene radical), optionally containing oxygen atoms, and optionally at least partially fluorinated, or a (per)fluoro(poly)oxyalkylene radical comprising one or more catenary ethereal bonds; and compounds (U) comprising three carbon-carbon unsaturations, which are selected from the group consisting of: tri-substituted cyanurate compounds of general formula: ##STR00033## wherein each of R.sub.cy, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.rcy or OR.sub.rcy, with R.sub.rcy being C.sub.1-C.sub.5 alkyl, optionally possibly comprising halogen(s), and each of J.sub.cy, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; tri-substuituted isocyanurate compounds of general formula: ##STR00034## wherein each of R.sub.isocy, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.risocy or OR.sub.risocy, with R.sub.risocy being C.sub.1-C.sub.5 alkyl, optionally comprising halogen(s), and each of J.sub.isocy, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; tri-substituted triazine compounds of general formula: ##STR00035## wherein each of R.sub.az, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.raz or OR.sub.raz, with R.sub.raz being C.sub.1-C.sub.5 alkyl, optionally possibly comprising halogen(s), and each of J.sub.az, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; tri-substituted phosphite compounds of general formula: ##STR00036## wherein each of R.sub.ph, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.rph or OR.sub.rph, with R.sub.rph being C.sub.1-C.sub.5 alkyl, optionally comprising halogen(s), and each of Jo, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; tri-substituted alkyltrisiloxanes of general formula: ##STR00037## wherein each of R.sub.si, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.rsi or OR.sub.rsi, with R.sub.rsi being C.sub.1-C.sub.5 alkyl, optionally comprising halogen(s), each of R'.sub.si, equal to or different from each other and at each occurrence, is independently selected from C.sub.1-C.sub.5 alkyl groups, optionally comprising halogen(s), and each of J.sub.si, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; N,N-disubstituted acrylamide compounds of general formula: ##STR00038## wherein each of R.sub.an, equal to or different from each other and at each occurrence, is independently selected from H or a group R.sub.ran or OR.sub.ran, with R.sub.ran being C.sub.1-C.sub.5 alkyl, optionally comprising halogen(s), and each of J.sub.an, equal to or different from each other and at each occurrence, is independently selected from a bond or a divalent hydrocarbon group, optionally comprising heteroatoms; and compounds (U) comprising four or more carbon-carbon unsaturations, which are selected from tris(diallylamine)-s-triazine of formula ##STR00039## hexa-allylphosphoramide, N,N,N,N-tetra-allyl terephthalamide, or N,N,N,N-tetra-allyl malonamide.

11. The composition according to claim 1, wherein the amount of the compound (U) ranges from 0.1 to 20 weight parts per 100 parts by weight (phr) of fluoroelastomer (A).

12. The composition (C) according to claim 1, wherein the said at least one cross-linking system is a ionic-based cross-linking system comprising at least one polyhydroxylated compound, at least one accelerant, and at least one basic metal oxide.

13. A process for the manufacture of composition (C), according to claim 1, said method comprising mixing: the fluoroelastomer (A); the cross-linking system; and the polymer (PAI).

14. A method for fabricating shaped articles comprising curing the composition (C), according to claim 1.

15. A cured article comprising the composition (C), according to claim 1, said cured article being selected from the group consisting of sealing articles, O(square)-rings, packings, gaskets, diaphragms, shaft seals, valve stem seals, piston rings, crankshaft seals, cam shaft seals, oil seals, piping and tubings, flexible hoses, and conduits for delivery of hydrocarbon fluids and fuels.

16. An assembly including a substrate and at least one cured article, according to claim 15.

17. The composition (C) according to claim 5, wherein Ar is selected from the group consisting of the following structures: ##STR00040## each of which may be optionally substituted, with X being O, C(O), CH.sub.2, C(CF.sub.3).sub.2, or (CF.sub.2).sub.n, and n being an integer from 1 to 5; and R is selected from the group consisting of the following structures: ##STR00041## each of which may be optionally substituted, with Y being O, S, SO.sub.2, CH.sub.2, C(O), C(CF.sub.3).sub.2, or (CF.sub.2).sub.n, and n being an integer from 0 to 5.

18. The composition (C) according to claim 7, which comprises said polymer (PAI) in an amount of at least 2.0 phr, and at most 18.0 phr, with respect to the fluoroelastomer (A).

19. The composition according to claim 11, wherein the amount of the compound (U) ranges from 1 to 10 weight parts per 100 parts by weight of fluoroelastomer (A).

20. The composition (C) according to claim 12, wherein the at least one basic metal oxide is selected from the group consisting of ZnO, MgO, PbO, and mixtures thereof.

Description

EXAMPLES

[0169] Raw Materials

[0170] Tecnoflon P X647 is an iodine-containing peroxide curable fluoroelastomer commercially available from Solvay Specialty Polymers Italy, SpA.

[0171] VAROX DBPH-50 is 2,5-dimethyl-2,5-di (t-butylperoxy)-hexane, available from R. T. Vanderbilt, Norwalk, Conn.

[0172] TAIC DLC-A is a triallyl isocyanurate, silicon-dioxide blend co-agent for peroxide vulcanization, comprising about 72% wt TAIC, commercially available from NATROCHEM, INC.

[0173] N550 BLACK is a N550 semi-reinforcing carbon black commercially available notably from MAKROChem.

[0174] ARMEEN 18D is distilled octadecylamine commercially available from Akzo Nobel.

[0175] Torlon AI-10 is a powdered aromatic polyamideimide commercially available from Solvay Specialty Polymers USA, LLC.

[0176] Torlon 4000TF is a neat resin aromatic polyamide-imide (PAI) fine powder designed for compounding with other polymers and specialty additives, commercially available from Solvay Specialty Polymers USA, LLC.

[0177] Adhesion to Silicone

Comparative Example 1A

[0178] A commercial Tecnoflon grade P X647, compounded as in Table 1, was placed into an ASTM slab mold over a silicone compound. For an half of the slab wax paper was placed so as to keep the silicone and FKM compound joining together in the remaining uncovered part. Then, we closed the mold and added a 25 lb weight on top of the mold to close it. The system was pressed cured for 30 minutes at 177 deg C.

TABLE-US-00001 TABLE 1 Polymer compound phr TECNOFLON PX647 100 VAROX DBPH-50 1.25 TAIC-DLC-A 3.6 N550 BLACK 14 ARMEEN 18D 0.5

Example 1

[0179] A commercial Tecnoflon grade P X647 was blended in open mill with 6 phr of commercial Torlon AI-10 obtaining the Polymer A. Polymer A was compounded in open mill according to the recipe in Table 2. The material was then molded with silicone as described in Comparative Ex 1.

TABLE-US-00002 TABLE 2 Polymer compound phr Polymer A 100 VAROX DBPH-50 1.25 TAIC-DLC-A 3.6 N550 BLACK 14 ARMEEN 18D 0.5

Example 2

[0180] A commercial Tecnoflon grade P X647 was blended in open mill with 6 phr of commercial Torlon 4000TF obtaining the Polymer B. Polymer B was compounded in open mill according to the recipe in Table 3. The material was then molded with silicone as described in Comparative Ex 1.

TABLE-US-00003 TABLE 3 Polymer compound phr Polymer B 100 VAROX DBPH-50 1.25 TAIC-DLC-A 3.6 N550 BLACK 14 ARMEEN 18D 0.5

[0181] Adhesion to Stainless Steel

[0182] Adhesion property of Tecnoflon PX 647, Polymer A and Polymer B against Stainless Steel was measured according to the following molding procedure.

[0183] A sand blasted stainless steel plaque was placed in ASTM D429-Method

[0184] B slab mold with FKM compound. For an half of the slab a wax paper so as to keep the stainless steel and FKM compound joining together in the remaining uncovered part. Then, the assembled mold was closed into a standard compression molding machine. It was cured for 30 minutes at 177 deg C.

TABLE-US-00004 TABLE 4 FORMULATIONS: Comp Ex1 Ex1 Ex2 TECNOFLON PX647 100 Polymer A 100 Polymer B 100 VAROX DBPH-50 1.25 1.25 1.25 TAIC-DLC-A 3.6 3.6 3.6 N550 BLACK 14 14 14 ARMEEN 18D 0.5 0.5 0.5 Rheology properties: MDR (6 @ 177 C.) ML, lb-in 0.7 0.7 0.8 MH, lb-in 20.4 21.8 26.0 Ts2, sec 34 38 35 T90, sec 71 102 84 After press cure: 10 @ 177 C. Physical properties: Hardness Shore A, pts. 65 68 71 Tensile Strength, psi 2842 1277 2209 Elongation, % 466 305 387 Modulus @ 50%, psi 191 221 247 Modulus @ 100%, psi 266 281 486 Modulus @ 200%, psi 810 628 1073 Adhesion to Silicon according the ASTM D1876 180 Peel Test Adhesion after Heat Resistance, 168 hours @ 200 C.: Average Tensile Strength, psi 6.8 8.3 7.9 Median Tensile Strength, psi 6.9 8.3 8.0 Adhesion after Heat Resistance, 168 hours @ 230 C.: Average Tensile Strength, psi 4.5 7.3 6.1 Median Tensile Strength, psi 4.5 7.5 5.9 Adhesion to Stainless steel according to ASTM D429 Method B Initial Adhesion after press cure: Average Tensile Strength, psi No 1732.7 1896.5 Median Tensile Strength, psi adhesion 1887.8 2382.0