METHOD FOR THE MANUFACTURE OF (PER)FLUOROPOLYETHER MODIFIED POLYAMIDES AND POLYAMIDES OBTAINABLE WITH SUCH METHOD

Abstract

A method for providing a fluorinated polyamide is herein provided. The method envisages the copolymerization of a (per)fluoropolyether comprising amino or acid functional groups with a mixture of a hydrogenated dicarboxylic acid and a diamine and/or an aminoacid or lactam in the presence of a hydrogenated monocarboxylic acid and/or a hydrogenated monoamine. By appropriate selection of the functionality of the reaction mixture, fluorinated polyamides having an average molecular weight (M.sub.w) lower than 16,000 and a content of PFPE segments ranging from 5% to 50% wt are obtained. These polyamides can be advantageously used as additives for other polyamides, in particular for non-fluorinated polyamides to provide blends that can be formed into shaped articles.

Claims

1-15. (canceled)

16. A method for making a fluorinated polyamide comprising copolymerizing a mixture comprising: (a) a monomer (A), selected from at least one of: (i) a mixture of: one or more hydrogenated aliphatic, cycloaliphatic, or aromatic diamine(s) or derivative(s) thereof able to form amide groups; and one or more hydrogenated aliphatic, cycloaliphatic, or aromatic dicarboxylic acid(s) or derivative(s) thereof able to form amide groups; (ii) one or more aminoacid(s) or derivative(s) thereof or lactam(s); with (b) a monomer (B), which is at least one fully or partially fluorinated polyether mixture selected from at least one of: a mixture of a PFPE-diamine and a PFPE monoamine or derivative(s) thereof, and a mixture of a PFPE-dicarboxylic acid and a PFPE monocarboxylic acid or derivative(s) thereof, and (c) a compound (C), which is at least one hydrogenated aliphatic, cycloaliphatic, or aromatic monoamine or a derivative thereof able to form amide groups or at least one hydrogenated aliphatic, cycloaliphatic, or aromatic monocarboxylic acid or a derivative thereof able to form amide groups, wherein the average functionality (F.sub.RM) of the mixture of monomers (A), (B) and compound (C), defined as the ratio between the overall equivalents of monomers (A), (B) and compound (C) and the overall moles of monomers (A), (B) and compound (C), is lower than 1.96.

17. The method according to claim 16, wherein the average functionality (F.sub.RM) ranges from 1.90 to 1.95.

18. The method according to claim 16, wherein the monomer (A) is a mixture of: the one or more hydrogenated aliphatic, cycloaliphatic, or aromatic diamine(s) or derivative(s) thereof; and the one or more hydrogenated aliphatic, cycloaliphatic, or aromatic dicarboxylic acid(s) or derivative(s) thereof.

19. The method according to claim 18, wherein the one or more diamine(s) complies with general formula (NN-I):
RHNR.sup.1NHR(NN-I) wherein: R and R, equal to or different from one another, are selected from hydrogen and straight or branched C.sub.1-C.sub.20 alkyl; and R.sup.1 is: (i) a C.sub.2-C.sub.36 straight or branched aliphatic alkylene, optionally comprising one or more divalent cycloalkyl groups or arylene groups; (ii) a divalent cycloalkyl group, or (iii) an arylene group; and the dicarboxylic acid(s) is an aromatic dicarboxylic acid comprising two reactive carboxylic acid groups, or an aliphatic dicarboxylic acid comprising two reactive carboxylic acid groups.

20. The method according to claim 19, wherein the one or more diamine(s) of formula (NN-I) is m-xylylenediamine, and the aliphatic dicarboxylic acid is adipic acid.

21. The method according to claim 16, wherein monomer (B) is at least one fully or partially fluorinated straight or branched polyalkyleneoxy chain (R.sub.f) having two chain ends, wherein one or both chain ends comprise a COOH group or a derivative thereof able to form amide groups.

22. The method according to claim 21, wherein one or both ends of chain (R.sub.f) comprise a group of formula CF.sub.2CH.sub.2OCH.sub.2COOH or a derivative thereof able to form amide groups.

23. The method according to claim 21, wherein chain (R.sub.f) comprises recurring units R having at least one catenary ether bond and at least one fluorocarbon moiety, said repeating units R, randomly distributed along the chain, are selected from the group consisting of: (i) CFXO, wherein X is F or CF.sub.3; (ii) CFXCFXO, wherein X, equal or different at each occurrence, is F or CF.sub.3, with the proviso that at least one of X is F; (iii) CF.sub.2CF.sub.2CW.sub.2O, wherein each of W, equal or different from each other, are F, Cl, H; (iv) CF.sub.2CF.sub.2CF.sub.2CF.sub.2O; (v) (CF.sub.2).sub.jCFZ*O wherein j is an integer from 0 to 3 and Z* is a group of general formula OR.sub.f*T, wherein R.sub.f* is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units are selected from: CFXO, CF.sub.2CFXO, CF.sub.2CF.sub.2CF.sub.2O, CF.sub.2CF.sub.2CF.sub.2CF.sub.2O, with each X being independently F or CF.sub.3 and T being a C.sub.1-C.sub.3 perfluoroalkyl group.

24. The method according to claim 23, wherein chain (R.sub.f) complies with formula (R.sub.fIII):
(CF.sub.2CF.sub.2O).sub.a1(CF.sub.2O).sub.a2(R.sub.fIII) wherein: a1, and a2 are integers >0 such that the number average molecular weight is between 400 and 5,000, with the ratio a2/a1 ranging from 0.3 to 3.

25. The method according to claim 16, wherein compound (C) is a hydrogenated aliphatic, cycloaliphatic, or aromatic monocarboxylic acid.

26. The method according to claim 25, wherein the hydrogenated aliphatic, cycloaliphatic, or aromatic monocarboxylic acid is selected from acetic acid and benzoic acid.

27. A fluorinated polyamide consisting of recurring units derived from: (a) a monomer (A), selected from at least one of: (i) a mixture of: one or more hydrogenated aliphatic, cycloaliphatic, or aromatic diamine(s) or derivative(s) thereof; and one or more hydrogenated aliphatic, cycloaliphatic, or aromatic dicarboxylic acid(s) or derivative(s) thereof; (ii) one or more aminoacid(s) or derivative(s) thereof or lactam(s); with (b) a monomer (B), which is at least one (per)fluoropolyether mixture selected from: a mixture of a PFPE-diamine and a PFPE monoamine or derivative(s) thereof, and a mixture of a PFPE-dicarboxylic acid and a PFPE monocarboxylic acid or derivative(s) thereof, said fluorinated polyamide having: (c) an end-capping group derived from: a compound (C), which is at least one hydrogenated aliphatic, cycloaliphatic, or aromatic monoamine or at least one hydrogenated aliphatic, cycloaliphatic, or aromatic amine or monocarboxylic acid or a derivative thereof able to form amide groups and, optionally, from (PFPE-N) and/or (PFPE-A).

28. The fluorinated polyamide according to claim 27 comprising from 5 to 50% wt. of units deriving from monomer (B) with respect to the weight of the fluorinated polyamide.

29. A polyamide blend comprising: a fluorinated polyamide of claim 27; and a hydrogenated polyamide obtained by copolymerization of: (i) one or more hydrogenated aliphatic, cycloaliphatic, or aromatic diamine(s) or derivative(s) thereof with one or more hydrogenated aliphatic, cycloaliphatic, or aromatic dicarboxylic acid(s) or derivative(s) thereof; or (ii) one or more aminoacid(s) or lactam(s).

30. A shaped article obtained by shaping the polyamide blend of claim 29.

Description

PREPARATION OF POLYAMIDES

Example 1PFPE-Modified Polyamide Comprising 10% Wt PFPE (M.SUB.n.=4,856, M.SUB.w.=10,002, Polydispersity Index 2.06)

[0174] Adipic acid (91.8 g, 0.63 mol, 1.26 eq), benzoic acid (15.0 g, 0.12 mol, 0.12 eq), xylylenediamine (MXDA, 47.65 g, 0.35 mol, 0.7 eq) and PFPE-ester (E-1) (18.8 g, 0.01 mol, 0.02 eq)

were placed in a 1 L four-necked cylindrical glass kettle equipped with a mechanical stirrer, condenser and nitrogen inlet and immersed in an oil bath. Temperature was raised to 100 C., then further 47.65 g of MXDA was added with continuous stirring and the bath temperature was raised up to 200 C. The reaction slurry at 200 C. was then heated up to the final oil bath temperature of 275 C. at the rate of 10 C./5 min. Once this temperature was reached, the reaction was continued until the required torque reached a plateau. The resulting melt was poured from the kettle by quenching in ice-cold water to provide a polymer mass. The mass was then dried and ground for further analyses.

[0175] The acidic content was 94 meq/kg and amine groups were not detected.

Example 1A (Comparative Example)PFPE Modified Polyamide (P-1A) Comprising 20% Wt PFPE (M.SUB.n.=9,140, M.SUB.w.=20,126, Polydispersity Index 2.20)

[0176] Following the procedure of Example 1, a polyamide was prepared with the following reagents:

adipic acid: 99.2 g, 0.68 mol, 1.36 eq;
MXDA: 90.6 g, 0.66 mol, 1.32 eq;
PFPE ester (E-1): 38.58 g, 0.02 mol, 0.04 eq.

[0177] The acidic content was 370 meq/kg and the content of amine groups was 5 meq/kg.

Example 2PFPE-Modified Polyamide Comprising 20% Wt PFPE (M.SUB.n.=7,123, M.SUB.w.=15,083, Polydispersity Index 2.12)

[0178] The following reagents:

adipic acid: 460.5 g, 3.15 mol, 6.30 eq;
MXDA: 456.9 g, 3.42 mol, 6.84 eq;
PFPE ester (E-1): 192.3, 0.10 mol, 0.20 eq;
acetic acid: 20.0 g, 0.33 mol, 0.33 eq
were charged in an autoclave at a pressure of 4.5 Pa and at a temperature from 30 C. to 250 C. for 3 hours. The reaction was considered complete when the torque value reached a plateau. Upon completion of the reaction, the resulting melt was discharged from the autoclave and processed as according to Example 1.

[0179] The acidic content was 125 meq/kg, which corresponded to a conversion of the starting acidic groups of about 98%.

Example 2A (Comparative Example)PFPE-Modified Polyamide Comprising 20% Wt PFPE (M.SUB.n .17,506, M.SUB.w.=42,130, Polydispersity Index 2.41)

[0180] Following the procedure of Example 1, a polyamide was prepared with the following reagents:

adipic acid: 99.2 g, 0.68 mol, 1.36 eq;
MXDA: 96.0 g, 0.70 mol, 1.40 eq;
PFPE ester (E-1): 38.6 g, 0.02 mol, 0.04 eq.

[0181] The acidic content was 107 meq/kg and the amine group content was 32 meq/kg.

Example 3PFPE-Modified Polyamide Comprising 10% Wt PFPE (M.SUB.n.=6,476, M.SUB.w.=13,908, Polydispersity Index 2.15)

[0182] This polyamide was prepared with the following reagents:

adipic acid: 460.48 g, 3.151 mol, 6.30 eq;
MXDA: 458.3 g, 3.37 mol, 6.73 eq;
PFPE ester (E-1): 95 g, 0.051 mol, 0.102 eq;
acetic acid: 20.0 g, 0.333 mol, 0.33 eq
according to the procedure of Example 2.

[0183] The acidic content was 87 meq/kg and the amine group content was 22 meq/kg.

Example 3A (Comparative Example)PFPE-Modified Polyamide Comprising 10% Wt PFPE, M.SUB.n.=22,342 and M.SUB.w.=58,364, Polydispersity Index 2.61)

[0184] This polyamide was prepared according to the procedure of Example 1 with the following reagents:

adipic acid: 460.5 g, 3.15 mol, 6.30 eq,
MXDA: 435.8 g, 3.20 mol, 6.40 eq,
PFPE ester (E-1): 95.0 g, 0.05 mol, 0.10 eq.

[0185] The acidic content was 125 meq/kg and the amine group content was 36 meq/kg.

Example 4PFPE-Modified Polyamide Comprising 20% Wt PFPE (M.SUB.n.=3,352, M.SUB.w.=9,928, Polydispersity Index 2.96)

[0186] This polyamide was prepared according to the procedure of Example 1 with the following reagents:

adipic acid: 89.9 g, 0.61 mol, 1.23 eq
MXDA: 95.3 g, 0.70 mol, 1.4 eq
benzoic acid: 15.0 g, 0.12 mol, 0.12 eq
PFPE ester (E-1): 46.0 g, 0.02 mol, 0.05 eq.

[0187] The acidic group content was 179 meq/kg and the amine group content was 12 meq/kg.

Example 4A (Comparative Example)PFPE-Modified Polyamide Comprising 20% Wt PFPE (M.SUB.n.=25,268, M.SUB.w.=72,643, Polydispersity Index 2.87)

[0188] This polyamide was prepared according to the procedure of Example 1 with the following reagents:

adipic acid: 99.22 g, 0.678 mol, 1.36 eq;
MXDA: 95.3 g, 0.70 mol, 1.40 eq;
PFPE ester (E-1): 38.58 g, 0.021 mol, 0.040 eq.

[0189] The acidic group content was 80 meq/kg and the amine group content was 164 meq/kg.

Example 5Polyamide Comprising 10% Wt PFPE Units from PFPE Ester (E-2) (M.SUB.n.=5,000, M.SUB.w.=11,000; Polydispersity Index: 2.1)

[0190] This polyamide was prepared with the same reagents as example 1, except that PFPE ester (E-2) was used.

[0191] The acid content was 90 meq/kg, which corresponded to a conversion of the starting acidic groups of about 99%.

Example 6Reference Polyamide MDX6

[0192] This polyamide was prepared with the following reagents: [0193] adipic acid: 560 g, 4.44 mol, 1 eq; [0194] MXDA; 605 g, 4.44 mol, 1 eq
following the procedure of Example 1.

[0195] The content of acid groups was 108 meq/kg and the content of amine groups was 25 meq/kg.

[0196] It stems from Examples 1-4 according to the invention and from comparative Examples 1A-4A that, if compound (C) is not used and the average functionality (F.sub.RM) of the reaction mixture is higher than 1.96, the resulting polyamide has a molecular weight (M.sub.w) higher than 20,000.

General Procedure for the Preparation of Polyamide Blends and Molded Specimens for Tests

Extrusion

[0197] Non fluorinated polyamide MXD6 was blended with the fluorinated polyamides of Examples 1-4 and 1A-4A by means of two extrusion cycles.

1.sup.st cycle: mixing of MXD6 with the fluorinated polyamides of Examples 1-4 and 1A-4A to provide a first blend;
2.sup.nd cycle: coextrusion of OCV EC.sub.10 983 glass fiber (4.5 mm) with the first blend (30-60% wt glass fiber with respect to the mixture). The polyamides first blends were fed to the first barrel of zone-1 of an extruder comprising of 12 zones through a loss-in-weight feeder. The barrel settings were in the range of 220-250 C. The glass fibre was fed from zone 7 through a side stuffier via a loss-in-weight feeder. The screw rate was 100 rpm. The extrudates were cooled and pelletized using conventional equipment. The glass fiber content was determined by the ashing technique disclosed in the Methods section.

[0198] For the purpose of comparison, MXD6 was blended with glass fibers only according to the coextrusion cycle 2 described above.

Injection Molding

[0199] The extruded fluorinated polyamides were molded in a Sumitomo 75 TON injection molding machine. The temperature range was 265-280 C. The mold temperature controller was set to 140-165 C. The cooling cycle time was fixed to 35-50 sec. Under these conditions, appropriate specimens such as ISO tensile test pieces (165104 mm), ISO impact bars (unnotched: 80104 mm), notched: 8084 mm) and color plaques (75502.6 mm) were molded.

Polyamide Blends

[0200] Polyamide blends (B-1)-(B-4), (B-1bis), (Comparative Blends (B-1a)-(B1-d) and Reference blend (BR) were prepared according to the above-described general procedure. The ingredients and the glass fiber content (GF) of each blend are reported in the table below.

TABLE-US-00001 TABLE 1 Amount of Weight PFPE (% wt Amount fluorinated ratio with respect of MXD6 polyamide MXD6:fluorinated to the GF Blend Ingredients (g) (g) polyamide composition) (% wt) B.sub.R MDX6 + 1,500 / / / 48.94 Glass fiber (B-1) MDX6 + 600 150 80:20 2 48.02 Glass fiber + Polyamide of Ex. 1 (B-1a) MDX6 + 900 100 90:10 2 49.00 Glass fiber + Polyamide of Ex. 1A (B-2a) MDX6 + 900 100 90:10 2 48.81 Glass fiber + Polyamide of Ex. 2A (B-3a) MDX6 + 700 300 70:30 3 48.03 Glass fiber + Polyamide of Ex. 3A (B-4a) MDX6 + 850 150 85:15 3 49.30 Glass fiber + Polyamide of Ex. 4A (B-2) MDX6 + 900 100 90:10 2 49.88 Glass fiber + polyamide of Ex. 2 (B-3) MDX6 + 840 360 70:30 3 49.39 Glass fiber + polyamide of Ex. 3 (B-4) MDX6 + 850 150 85:15 3 49.88 Glass fiber + 4 (B-2bis) MDX6 + 1,020 180 85:15 3 49.21 Glass fiber + polyamide of Ex. 2

Contact Angles of the Polyamide Blends Versus Water

[0201] Contact angles versus water of specimens obtained from the polyamide blends of the invention, from the comparative blends and from the reference blends were measured according to the procedure disclosed in the Methods section. The results are reported in the Table below.

TABLE-US-00002 TABLE 2 Contact angle versus water PFPE Annealed (at 120 C. Example (% wt) Dry as molded for 10 hours) (B.sub.R) 0 63.2 0.9 72.7 0.4 (B-1) 2 85.8 1.1 90.4 0.9 (B-1a) 2 70.9 0.5 81.3 0.5 (B-2a) 2 76.6 0.9 81.4 1.3 (B-3a) 3 79.0 1.4 86.5 0.4 (B-4a) 3 80.3 1.4 90.0 0.4 (B-2) 2 86.4 1.5 99.4 0.4 (B-3) 3 86.0 0.5 94.0 1.1 (B-4) 3 87.4 1.2 93.2 1.0 (B-2bis) 3 83.3 0.8 93.5 0.6

[0202] The results show that the contact angles of the blends according to the invention are higher than those of reference blend BR and of the comparative blends.

Spiral Flow Length Test

[0203] The results of the spiral flow length test are reported in the Table below for reference blend BR, (B-2) according to the invention and comparative composition (B-2a).

TABLE-US-00003 TABLE 3 PFPE M.sub.n of the fluorinated Spiral length Example (% wt) polyamide (mm) (B.sub.R) 0 / 25 (B-2) 2 7,123 32 (B-2a) 2 17,506 25

[0204] The length (distance travelled) or the weight for polyamide blend (B-2) according to the invention in the spiral mold was higher (which means better and easier flow), than that of reference blend (BR) and of comparative blend (B-2a).

Resistance to Basic Hydrolysis

[0205] This test was carried out to show the improved resistance of polyamide of comprising PFPE segments derived from PFPE ester (E-1) (in which the ester groups are bound to the PFPE chain via a hydrogenated ether spacer) with respect to that of polyamides comprising PFPE segments derived from PFPE ester (E-2) (in which the ester groups are directly bound to the PFPE chain).

[0206] The polyamides of Examples 1 and 5 were submitted to the stability test described above. The polyamide of Example 5 underwent about 8% hydrolysis, while the polyamide of Example 1 underwent about 1% hydrolysis.

Mechanical Tests

[0207] All molded specimens were tested as dry as molded. For this purpose, the specimens were stored after injection molding for at least 48 h at room temperature in a desiccator in sealed aluminium bags. The tensile properties of the materials were measured according to ISO 527 test procedure, while the notched and unnotched Izod impact strengths were measured according to the ISO 180 test procedure. The table below reports the impact strength data for unnotched and notched specimens.

TABLE-US-00004 TABLE 4 Impact strength PFPE Unnotched IZOD Notched IZOD Blend (% wt) impact (kg/m.sup.2) impact (kg/m.sup.2) B.sub.R 0 59.6 3.6 11.8 0.4 B-1 2 55.5 4.6 13.4 0.9 B-1a 2 60.4 3.8 12.9 0.3 B-2a 2 62.2 4.8 13.2 0.9 B-3a 3 62.3 3.3 12.9 0.5 B-4a 3 63.2 5.3 13.0 0.6 B-2 2 65.1 4.5 13.0 0.6 B-4 3 56.2 1.7 13.4 0.3 B-2bis 3 58.8 5.9 13.7 1.2