PROCESS FOR CONTINUOUSLY PREPARING COPOLYAMIDES FROM LACTAMS, DIAMINES AND DIMER ACIDS

Abstract

A process for continuously preparing copolyamides by copolymerizing at least one lactam (A) and monomers (M), comprising the steps of a) mixing at least one lactam (A) with monomers (M) at a temperature of 60 to 150 C. and b) passing the mixture obtained in step a) from the top downward through a vertical polymerization tube at polyamide-forming temperatures to obtain a copolyamide, wherein the monomers (M) comprise at least one C32-C40 dimer acid (B1) and at least one C4-C12 diamine (B2) and optionally at least one C4-C20 diacid (B3).

Claims

1.-16. (canceled)

17. A process for continuously preparing copolyamides by copolymerizing at least one lactam (A) and monomers (M), comprising the steps of a) mixing at least one lactam (A) with monomers (M) at a temperature of 60 to 150 C. and b) passing the mixture obtained in step a) from the top downward through a vertical polymerization tube at polyamide-forming temperatures to obtain a copolyamide, wherein the monomers (M) comprise at least one C32-C40 dimer acid (B1) and at least one C4-C12 diamine (B2) and optionally at least one C4-C20 diacid (B3).

18. The process according to claim 17, wherein the mixing in step a) comprises a premixing of the at least one lactam (A) with component (B1) to obtain a premixture and subsequently adding component (B2) and optionally (B3) to the premixture.

19. The process according to claim 17, wherein the component (B1) is a C32-C40 dimer acid mixture, obtainable by dimerizing unsaturated fatty acids selected from the group consisting of unsaturated C16 fatty acids, unsaturated C18 fatty acids and unsaturated C20 fatty acids.

20. The process according to claim 17, wherein the at least one lactam (A) is initially charged and the monomers (M) are added separately or together.

21. The process according to claim 17, wherein the lactam (A) comprises 0 to 10% by weight of water, based on the lactam (A), and the monomers (M) comprise 0 to 5% by weight of water, based on the sum total of their components.

22. The process according to claim 17, wherein the molar number of the amine groups from (B2) is essentially equal to the molar number of the sum total of the carboxyl groups from (B1) and optionally (B3).

23. The process according to claim 17, wherein the at least one lactam (A) is present in an amount in the range from 15 to 84% by weight and the monomers (M) are present in an amount of 16 to 85% by weight, where the sum total of the percentages by weight of components (A) and (M) adds up to 100% by weight.

24. The process according to claim 17, wherein the lactam (A) is selected from the group consisting of 3-aminopropanolactam, 4-aminobutanolactam, 5-aminopentanolactam, 6-aminohexanolactam, 7-aminoheptanolactam, 8-aminooctanolactam, 9-aminononanolactam, 10-aminodecanolactam, 11-aminoundecanolactam and 12-aminododecanolactam.

25. The process according to claim 17, wherein 6-aminohexanolactam (-caprolactam) is used as lactam (A).

26. The process according to claim 17, wherein component (B2) is selected from the group consisting of 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane and 1,12-diaminododecane.

27. The process according to claim 17, wherein component (B2) is 1,6-diaminohexane (1,6-hexamethylenediamine).

28. The process according to claim 17, wherein monomers (M) do not comprise polyoxyalkylene groups.

29. The process according to claim 17, wherein before step b) (aa) the mixture obtained in step a) is supplied to a heated helical tube evaporator, in which a liquid phase and a vapor phase form at a temperature of 140 to 300 C., where a stream consisting of water vapor and/or inert gas is optionally also introduced into the mixture upstream of the helical tube and (ab) the vapor phase formed in step (aa) is separated off from the liquid phase and separated in a column into water vapor and into organic components comprising components (B1), (B2), optionally (B3) and lactam (A), and (ac) the liquid phase from the helical tube of step (aa), mixed with the organic components of step (ab).

30. A copolyamide obtained by the process according to claim 17.

31. A method comprising producing fibers, films, or molded articles utilizing copolyamides as defined in claim 30.

32. The process according to claim 31 for producing films in the agricultural sector, films in the food packaging sector or films in the industrial applications sector.

Description

EXAMPLES

[0138] The properties of the polymer films were determined as follows.

[0139] The viscosity number of the copolyamides was determined in a 1% by weight solution of phenol/o-dichlorobenzene in a weight ratio of 1:1 at 25 C. according to DIN EN ISO 307:2007. In contrast to DIN EN ISO 307:2007, a solvent other than those disclosed must be chosen in order to bring the copolyamides into solution. Also deviating from DIN EN ISO 307:2007, instead of 0.5% by weight solutions, 1% by weight solutions were used.

[0140] As described in DIN EN ISO 307:2007 on page 15, the relative viscosities were determined from the arithmetic mean of the flow times, whereas the relative viscosity is (RV)=(ttc/T0T0c). Deviant from ISO: 307:2007, a solvent other than the described solvents must be chosen in order to bring the copolyamides into solution. The chosen solvent was phenol/o-dichlorobenzene in a weight ratio of 1:1. Furthermore, the polyamide solutions used contained 1% by weight of polyamide, instead of 0.5% by weight solutions disclosed in DIN EN ISO 307:2007.

[0141] The melting temperatures were determined according to ISO 11357 1: 2009 and ISO 11357-3: 2011. Two heating runs were conducted and the melting temperatures determined on the basis of the second heating run.

[0142] The densities of the polyamides were determined according to the immersion method described in EN ISO 1183-1A: 2012 using water as solvent.

[0143] In order to determine the proportion of nylon-6,36 in the copolyamide, the copolyamide was hydrolyzed in dilute hydrochloric acid (20%). This protonates the units derived from hexamethylenediamine, with the chloride ion from the hydrochloric acid forming the counterion. This chloride ion was then exchanged by means of an ion exchanger for a hydroxide ion, releasing hexamethylenediamine. The hexamethylenediamine concentration, from which the proportion of nylon-6,36 in the copolyamide can be calculated, is then quantified by titrating with 0.1 molar hydrochloric acid.

[0144] Copolyamides according to the claimed process:

Example E-1

[0145] To 185 kg/h of caprolactam containing 2% of water at a temperature of 95 C. were added 70 kg/h of Pripol 1009 from Croda (C36 dimer acid mixture, hydrogenated), likewise heated to 95 C. Subsequently, 70% aqueous hexamethylenediamine solution was added to the transparent solution at a speed of 20 kg/h. The still transparent mixture was heated to 200-205 C. and transferred at a pressure of 7 bar into a helical tube evaporator via a pressure regulation valve. The pressure at the inlet of the helical tube evaporator was approximately 1-2 bar. The mixture emerging from the helical tube evaporator at a temperature of 195-205 C. at a slightly elevated pressure of 250 mbar was transferred to the top of a VK tube. Defoamer was simultaneously injected to the top of the VK tube at a concentration of 30-40 ppm relative to the overall input. The temperature at the top of the VK tube was approximately 260 C. The vapor phase was led to a column at the top of the VK tube and discharged after condensation. The remaining monomer mixture passed through the VK tube, which was heated in segments, wherein the temperature decreases stepwise from 265-280 C. to approximately 250 C. at the outlet of the VK tube. The VK tube was operated at the hydrostatic system pressure that the system self-established.

[0146] At the outlet of the VK tube, a nylon-6/6.36 melt was obtained, which was transferred directly via a discharge pump to an underwater pelletizing system with a subsequent extraction step and a subsequent drying step. Drying was followed by postcondensation.

[0147] The copolyamide obtained exhibited a viscosity number of 218 ml/g and a melting temperature of 199 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 30.4% by weight, the density was 1.052 g/ml.

Example E-2

[0148] The process described in example 1 was altered to a throughput of 160 kg/h caprolactam, 60 kg/h Pripol 1012 (C36 dimer acid mixture, unhydrogenated) and 17 kg/h of aqueous hexamethylenediamine solution.

[0149] The copolyamide obtained had a viscosity number of 217 ml/g and a melting temperature of 198 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 28.0% by weight, the density was 1.054 g/ml.

Example E-3

[0150] The process described in example 1 was altered to 260 kg/h of caprolactam, 50 kg/h of Pripol 1012 (C36 dimer acid mixture, unhydrogenated) and 16 kg/h of aqueous hexamethylenediamine solution.

[0151] The copolyamide obtained had a viscosity number of 222 ml/g and a melting temperature of 208 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 16.7% by weight, the density was 1.084 g/ml.

[0152] Comparative Copolyamides:

Comparative Example C-4

[0153] 932 kg of caprolactam, 323.2 kg of Pripol 1009 (C36 dimer acid mixture, hydrogenated) from Croda (C36 dimer acid, hydrogenated), 77.84 kg of 85% by weight hexamethylenediamine solution in water and 153 kg of water were mixed in a 1930 l vessel and covered with nitrogen. The vessel was heated to an external temperature of 290 C. and the mixture was stirred at this temperature for 11 hours. Stirring was performed under elevated pressure for the first 7 h and under reduced pressure for the following 4 hours while the water formed was simultaneously distilled off. The copolyamide obtained was discharged from the vessel, extruded and pelletized. The pellets of the copolyamide obtained were extracted with 95 C. hot water for 4 times for 6 hours and subsequently dried at 90 to 140 C. under a nitrogen stream for 10 hours.

[0154] The copolyamide obtained had a viscosity number of 200 ml/g and a melting temperature of 201 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 29.3% by weight, the density was 1.057 g/ml.

Comparative Example C-5

[0155] 932 kg of caprolactam, 322 kg of Pripol 1012 from Croda (C36 dimer acid mixture, unhydrogenated), 77.84 kg of 85% by weight hexamethylenediamine solution in water, 100 g of antifoam reagent Polyapp 2557-CTW from Polystell do Brazil and 153 kg of water were mixed in a 1930 l vessel and covered with nitrogen. The vessel was heated to an external temperature of 290 C. and the mixture was stirred at this temperature for 11 hours. Stirring was performed under elevated pressure for the first 7 h, and under reduced pressure for the following 4 hours, while water formed was simultaneously distilled off. The copolyamide obtained was discharged from the vessel, extruded and pelletized. The pellets of the copolyamide obtained were extracted with 95 C. hot water 4 times for 6 hours and subsequently dried at 90 to 140 C. under a nitrogen stream for 10 hours.

[0156] The copolyamide obtained had a viscosity number of 184 ml/g and a melting temperature of 199 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 30.1% by weight, the density was 1.060 g/ml.

Comparative Example C-6

[0157] 1039 kg of caprolactam, 216 kg of Pripol 1009 from Croda (C36 dimer acid mixture, hydrogenated), 51.7 kg of 85% by weight hexamethylenediamine solution in water, 100 g of antifoam reagent Polyapp 2557-CTW from Polystell do Brazil and 142 kg of water were mixed in a 1930 l vessel and covered with nitrogen. The external temperature of the vessel was heated to 290 C. and the mixture was stirred at this temperature for 11 hours. Stirring was performed under elevated pressure for the first 7 hours, and under reduced pressure for the following 4 hours, while the water formed was simultaneously distilled off. The copolyamide obtained was discharged from the vessel, extruded and pelletized. The pellets of the copolyamide obtained were extracted with 95 C. hot water 4 times for 6 hours and subsequently dried at 90 to 140 C. under a nitrogen stream for 10 hours.

[0158] The copolyamide obtained had a viscosity number of 240 ml/g and a melting temperature of 206 C. The proportion of nylon-6,36 in the copolyamide, based on the total weight of the copolyamide, was 19.8% by weight, the density was 1.078 g/ml.

[0159] Determination of the Optical Quality of Films Obtained Using the Copolyamides Prepared in Examples E-1 to E-3 and Comparative Examples C-4 to C-6:

[0160] The optical quality of the thermoplastics (copolyamides) obtained in the above-described experiments was determined on the commercially available FQTS SFA-100 system from OCS. For this purpose, polymer films were produced in a casting process using a nozzle head width of 100 mm. The system had a screw with a diameter of 25 mm and a length of 625 mm. The different extruder zone temperatures were between 240-260 C. and the nozzle temperature was 260 C. The chill roll was cooled to room temperature. The 50 m-thick, transparent polymer films were subsequently continuously transilluminated with a 50 W halogen light radiator and the defects located in the film were monitored using a CCD line-scan camera from Nikon having 2048 pixels. The resolution of the pixels was 1010 m.sup.2 on the cast film. Two square meters of film were examined from each material. The optical defects counted on these two square meters are listed in table 1 according to their size:

TABLE-US-00001 TABLE 1 E1 E2 E3 C4 C5 C6 <200 m 349 968 2511 7052 11800 31994 200-400 m 154 230 810 1843 2977 9687 400-600 m 28 41 103 129 187 559 600-800 m 1 4 27 32 24 42 800-1000 m 1 2 10 4 4 3 >1000 m 0 2 4 4 3 1 533 1247 3465 9094 14995 42286

[0161] The optical quality of the copolyamides prepared according to the inventive continuous process is considerably improved compared to the discontinuous process described in the literature, and enables the use of the copolyamides in optically transparent molded articles.