TUBULAR CASING (S) FOR FOOD, CONTAINING AT LEAST ONE COPOLYAMIDE COMPOSED OF AT LEAST ONE LACTAM, A DICARBOXYLIC ACID AND 1,5-DIAMINO-3-OXAPENTANE

Abstract

The present invention relates to a tubular casing (S) for food produced by polymerizing a lactam (A) and a monomer mixture (M), where the monomer mixture (M) comprises 1,5-diamino-3-oxapentane. The present invention further relates to the use of the tubular casing as a packaging casing, particularly a sausage casing.

Claims

1.-18. (canceled)

19. A tubular casing (S) for food comprising at least one copolyamide produced by polymerizing the following components: (A) 60-95% by weight of at least one lactam and (B) 5-40% by weight of a monomer mixture (M) comprising the following components: (B1) at least one C.sub.4-C.sub.12 dicarboxylic acid and (B2) at least one diamine, where component (B2) comprises 1,5-diamino-3-oxapentane and where the percentages by weight of components (A) and (B) are each based on the sum total of the percentages by weight of components (A) and (B).

20. The tubular casing (S) for food according to claim 19, wherein component (A) is selected from the group consisting of 6-aminohexanolactam and 12-aminododecanolactam.

21. The tubular casing (S) for food according to claim 19, wherein component (A) is 6-aminohexanolactam.

22. The tubular casing (S) for food according to claim 19, wherein component (B) comprises in the range from 45 to 55 mol % of component (B1) and in the range from 45 to 55 mol % of component (B2), in each case based on the total molar amount of component (B).

23. The tubular casing (S) for food according to claim 19, wherein component (B1) is selected from the group consisting of butanedioic acid (succinic acid), pentanedioic acid (glutaric acid), hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid), octanedioic acid (suberic acid), nonanedioic acid (azelaic acid), decanedioic acid (sebacic acid), undecanedioic acid, dodecanedioic acid, terephthalic acid and isophthalic acid.

24. The tubular casing (S) for food according to claim 19, wherein component (B1) is hexanedioic acid (adipic acid).

25. The tubular casing (S) according to claim 19, wherein the copolyamide has a glass transition temperature (TG(c)), where the glass transition temperature (TG(c)) is in the range from 30 C. to 70 C.

26. The tubular casing (S) for food according to claim 19, wherein the tubular casing (S) has a melting temperature (TM(c)), where the melting temperature (TM(c)) is in the range from 100 C. to 210 C.

27. The tubular casing (S) for food according to claim 19, wherein the tubular casing (S) has a thickness in the range from 5 m to 100 m mm.

28. The tubular casing (S) for food according to claim 19, wherein the tubular casing has a water vapor permeability (WVP) in accordance with ASTM F 1249, at 23 C. and 85% RH, of at least 2500 g m/(m.sup.2*d).

29. The tubular casing (S) for food according to claim 19, wherein the tubular casing (S) is produced in a in a multi-blowing process.

30. A process for producing a tubular casing (S) for food according to claim 19, comprising the following steps: i) providing at least one copolyamide produced by polymerizing the following components: (A) 60-95% by weight of at least one lactam and (B) 5-40% by weight of a monomer mixture (M) comprising the following components: (B1) at least one C.sub.4-C.sub.12 dicarboxylic acid and (B2) at least one diamine, where component (B2) comprises 1,5-diamino-3-oxapentane and where the percentages by weight of components (A) and (B) are each based on the sum total of the percentages by weight of components (A) and (B), in molten form in an extruder ii) extruding the at least one copolyamide provided in step i) in molten form from the first extruder through a ring die to obtain a tubular film of the at least one copolyamide in molten form, iii) cooling the tubular film, of the at least one copolyamide in molten form, obtained in step ii), where the at least one copolyamide solidifies to obtain the tubular casing (S), iv) stretching the tubular casing (S) obtained in step iii) by blowing air into the tube of the tubular casing (S) and by simultaneously guiding the tubular casing (S) over at least one roller to obtain a stretched tubular casing (vS).

31. The process for producing a tubular casing (S) for food according to claim 30, wherein the tubular film comprising the at least one copolyamide is guided through a first roller system during the cooling in step iii), where the tube is stretched in its length.

32. The process for producing a tubular casing (S) for food according to claim 30, wherein steps (iii) and (iv) are carried out successively or simultaneously.

33. The process for producing a tubular casing (S) for food according to claim 30, wherein the tubular casing (S) obtained in step iii) is heated before step iv).

34. The process for producing a tubular casing (S) for food according to claim 33, wherein the tubular casing (S) is heated to a temperature above the glass transition temperature (T.sub.G(c)) of the at least one copolyamide present in the tubular casing (S) and below the melting temperature (T.sub.M(c)) of the at least one copolyamide present in the tubular casing (S).

35. The use of a tubular casing (S) for food according to claim 19 as a packaging casing.

36. The use of a tubular casing (S) for food according to claim 19 as a sausage casing.

Description

EXAMPLES

[0306] Molecular weight was determined by gel permeation chromatography against a poly(methyl methacrylate) standard from Polymer Standard Services GmbH, headquartered in Mainz. The solvent was hexafluoro-2-propanol and the concentration of the polymer on injection onto a styrene-divinylbenzene column was 1.5 mg/ml. The number of theoretical plates was 20 000.

[0307] Viscosity numbers of polyamides not comprising any 1,5-diamino-3-oxapentane units were determined in a 0.5% by weight solution in 96% by weight sulfuric acid at 25 C. in accordance with EN ISO 307:2007+Amd 1:2013.

[0308] Viscosity numbers of copolyamides comprising 1,5-diamino-3-oxapentane were determined in a 0.5% by weight solution of phenol/o-dichlorobenzene in a weight ratio of 1:1 at 25 C. in an analogous manner to the method described in EN ISO 307:2007+Amd 1:2013.

[0309] Glass transition temperatures and melting temperatures were determined in accordance with ISO 11357-1:2009, ISO 11357-2:2013 and ISO 11357-3:2011. For this purpose, two heating runs were carried out and the glass transition and melting temperatures were determined on the basis of the second heating run.

[0310] In order to determine the proportion of adipic acid and 1,5-diamino-3-oxapentane in the copolyamide, the copolyamide was hydrolyzed in dilute hydrochloric acid (20%). This protonated the units derived from 1,5-diamino-3-oxapentane, with the chloride ions from the hydrochloric acid forming the counterion. An ion exchanger was then used to exchange this chloride ion for a hydroxide ion with liberation of 1,5-diamino-3-oxapentane. Titration with 0.1 molar hydrochloric acid was then used to determine the concentration of 1,5-diamino-3-oxapentane, from which the proportion of adipic acid and 1,5-diamino-3-oxapentane in the copolyamide was calculated.

[0311] Density was determined in accordance with DIN EN ISO 1183-3 at a temperature of 25 C.

[0312] The statistical distribution of the individual monomers in the copolyamides was determined by .sup.13C NMR. To this end, a sample was dissolved in deuterated hexafluoro-2-propanol and the following carbonyl carbon signals were assigned via 2D NMR: a.) a shift of 183.6 for a caprolactam carbonyl carbon atom adjacent to a 1,5-diamino-3-oxapentane, b.) 182.9 for an adipic acid carbonyl carbon atom adjacent to a 1,5-diamino-3-oxapentane, c.) 181.7 for a caprolactam carbonyl carbon atom adjacent to a caprolactam, and d.) 181.0 for an adipic acid carbonyl carbon atom adjacent to a caprolactam. The .sup.13C NMR signals were measured using an AV 399 instrument from Bruker.

[0313] Water vapor permeability and water vapor transmission were determined in accordance with ASTM F 1249 on a Permatran-W Model 3/33 instrument from MOCON at 23 C. and 85% relative humidity in duplicate measurements.

[0314] The Elmendorf tear propagation resistance was determined in accordance with DIN ISO 6383-2:2004 in the extrusion direction (MD) and at right angles thereto (TD). Prior to measurement, the films were conditioned according to the standard climate for non-tropical countries, described in DIN EN ISO 291:2008. An 8N pendulum weight was used in a Lorentzen & Wettre Tearing Tester.

[0315] Puncture resistance was determined in accordance with DIN EN 14477 using a metal spike with a diameter of 0.8 mm and a speed of 100 mm/min. The films were conditioned prior to measurement according to the standard climate for non-tropical countries, as described in DIN EN ISO 291:2008.

[0316] Oxygen transmission and oxygen permeability were determined in accordance with ASTM F 1927 on an OX-TRAN instrument at 23 C. at 0% relative humidity in duplicate measurements.

[0317] Water permeability was measured using tubes with a length of 12 cm and a width of 6 cm (see FIG. 1, this shows the experimental setup to determine water permeability). These were produced on a Weber blown film system having a nozzle diameter of 50 mm and an extruder length of 25 cm. The thickness of a single tube side was first determined, then one open side of the tube was heat-sealed at 155 C., the tube was filled with 100 cm.sup.2 of distilled water and finally the other side of the tube was also heat-sealed at 155 C. The water-filled, completely closed pouches were attached at both ends to an aluminum dish in order to avoid breakages at the heat-sealed joints (see FIG. 1) and in order to determine their starting weight. The loss in weight at 23 C. and 50% relative humidity was recorded every 24 hours for the first 3 days and then after 7 and 8 days by subtracting the current weight from the original weight.

[0318] The following polymers were used:

Polyamides

[0319] A-1 Polyamide 6 from BASF SE sold under the Ultramid B40L brand name, having a viscosity number of 250 ml/g, a glass transition temperature of 57 C., a melting temperature of 220 C. and a density of 1.15 g/ml.

Copolyamides with 1,5-diamino-3-oxapentane:

[0320] C-1 A copolyamide of caprolactam, adipic acid and 1,5-diamino-3-oxapentane was produced by the following method: [0321] 3230 g of caprolactam (component (A)), 237 g of 1,5-diamino-3-oxapentane (component (B2)), 333 g of adipic acid (component (B1)) and 190 g of water were mixed in a 7.8 I steel reactor and then purged with nitrogen 10 times. The vessel was then closed and heated to an external temperature of 260 C. within 40 min. At this point, the internal pressure was 7 bar and the internal temperature was 208 C. The steel reactor was stirred under pressure for 50 min, then decompressed and stirred for a further 2 h and 45 min. The internal temperature rose to 237 C. during this time. The vessel was then charged with 15 bar of N.sub.2, a valve was opened and the melt strand that formed was pelletized in a water bath. The resulting pellets were extracted with boiling water under reflux for 16 h and then dried under reduced pressure at 70 C. An MW of 59 600 and an Mn of 24 000 were measured. [0322] The pellets were then condensed at 170 C. in a nitrogen stream for a further 10 hours. The copolyamide obtained had a viscosity number of 238 ml/g, a glass transition temperature of 47 C. and a melting temperature of 198 C. The proportion of 1,5-diamino-3-oxapentane.6 in the copolyamide, based on the total weight of the copolyamide, was 15.5% by weight; the density was 1.149 g/ml.

[0323] C-2 A copolyamide of caprolactam, adipic acid and 1,5-diamino-3-oxapentane was produced by the following method: [0324] 3040 g of caprolactam (component (A)), 316 g of 1,5-diamino-3-oxapentane (component (B2)), 444 g of adipic acid (component (B1)) and 190 g of water were mixed in a 7.8 I steel reactor and purged with nitrogen 10 times. The vessel was then closed and heated to an external temperature of 260 C. within 45 min. At this point, the internal pressure was 7 bar and the internal temperature was 207 C. The steel reactor was stirred under pressure for 40 min, then decompressed and stirred for a further 2 h and 30 min. The internal temperature rose to 235 C. during this time. The vessel was then charged with 15 bar of N.sub.2, a valve was opened and the melt strand that formed was pelletized in a water bath. The resulting pellets were extracted with boiling water under reflux for 16 h and then dried under reduced pressure at 70 C. An M.sub.W of 61 900 and an Mn of 25 600 were measured. [0325] The pellets were then condensed at 170 C. in a nitrogen stream for a further 10 hours. The copolyamide obtained had a viscosity number of 235 ml/g, a glass transition temperature of 45 C. and a melting temperature of 192 C. The proportion of 1,5-diamino-3-oxapentane.6 in the copolyamide, based on the total weight of the copolyamide, was 20.3% by weight; the density was 1.142 g/ml. [0326] In the .sup.13C NMR spectrum, signals a.) had a relative integral of 14.7%, b.) of 4.7%, c.) of 63.9% and d.) of 16.8%.

[0327] C-3 A copolyamide of caprolactam, adipic acid and 1,5-diamino-3-oxapentane was produced by the following method: [0328] 2850 g of caprolactam (component (A)), 395 g of 1,5-diamino-3-oxapentane (component (B2)), 555 g of adipic acid (component (B1)) and 190 g of water were mixed in a 7.8 I steel reactor and purged with nitrogen 10 times. The vessel was then closed and heated to an external temperature of 260 C. within 50 min. At this point, the internal pressure was 8 bar and the internal temperature was 205 C. The steel reactor was stirred under pressure for 35 min, then decompressed and stirred for a further 2 h and 15 min. The internal temperature rose to 235 C. during this time. The vessel was then charged with 15 bar of N.sub.2, a valve was opened and the melt strand that formed was pelletized in a water bath. The resulting pellets were extracted with boiling water under reflux for 16 h and then dried under reduced pressure at 70 C. An M.sub.W of 58 400 and an Mn of 25 400 were measured. [0329] The pellets were then condensed further at 170 C. in a nitrogen stream for 13 hours. The copolyamide obtained had a viscosity number of 237 ml/g, a glass transition temperature of 44 C. and a melting temperature of 186 C. The proportion of 1,5-diamino-3-oxapentane.6 in the copolyamide, based on the total weight of the copolyamide, was 25.3% by weight; the density was 1.152 g/ml. [0330] In the .sup.13C NMR spectrum, signals a.) had a relative integral of 19.3%, b.) of 9.2%, c.) of 53.8% and d.) of 17.8%.

[0331] C-4 A copolyamide of caprolactam, adipic acid and 1,5-diamino-3-oxapentane was produced by the following method: [0332] 2660 g of caprolactam (component (A)), 474 g of 1,5-diamino-3-oxapentane (component (B2)), 665 g of adipic acid (component (B1)) and 190 g of water were mixed in a 7.8 I steel reactor and purged with nitrogen 10 times. The vessel was then closed and heated to an external temperature of 260 C. within 15 min. At this point, the internal pressure was 1 bar and the internal temperature was 110 C. The steel reactor was stirred under pressure for 90 min, then decompressed and stirred for a further 3 h and 20 min. The internal temperature rose to 237 C. during this time. The vessel was then charged with 15 bar of N.sub.2, a valve was opened and the melt strand that formed was pelletized in a water bath. The resulting pellets were extracted with boiling water under reflux for 16 h and then dried under reduced pressure at 70 C. An M.sub.W of 60 600 and an Mn of 23 300 were measured. [0333] The pellets were then condensed further at 170 C. in a nitrogen stream for 13 hours. The copolyamide obtained had a viscosity number of 231 ml/g, a glass transition temperature of 42 C. and a melting temperature of 179 C. The proportion of 1,5-diamino-3-oxapentane.6 in the copolyamide, based on the total weight of the copolyamide, was 30.2% by weight; the density was 1.154 g/ml.

[0334] Production of monofilms in the casting process:

[0335] The monofilms made from materials A-1, C-1, 0-2, 0-3 and 0-4 were extruded on a Weber cast extrusion system with an extruder screw having a diameter of 30 mm and a throughput of 5 kg/h. The chill roller was cooled to 20 C. The films had a width of 150 mm.

[0336] The properties of the extruded films were as follows:

TABLE-US-00001 TABLE 1 Material A-1 C-1 C-2 C-3 C-4 Film thickness [m] 51.0 50.2 51.9 50.3 48.4 Content of [%] 0 15.5 20.3 25.3 30.2 1,5-diamino-3- oxapentane.6 Water vapor [g/m.sup.2*d] 48.0 64.8 92.2 89.5 127 transmission Water vapor [g*m/m.sup.2*d] 2448 3253 4785 4502 6147 permeability Tear [mN] 974 58 2845 105 3148 148 3541 228 3435 289 propagation resistance (MD) Tear [mN] 939 61 3136 234 3788 453 4465 471 4920 529 propagation resistance (TD) Puncture [mJ] 20.2 20.2 21.4 22.0 22.5 resistance Oxygen [cm.sup.3/m.sup.2*d*bar] 25.1 27.6 21.5 22.2 18.9 transmission Oxygen [cm.sup.3*m/m.sup.2*d*bar] 1280 1386 1116 1117 1089 permeability

[0337] The above examples show that the copolyamides according to the invention have significantly increased water vapor transmission and tear propagation resistance in films compared to a polyamide 6. The puncture resistance is increased slightly compared to polyamide 6 and the oxygen transmission is even slightly lower for materials C-2, C-3, and C-4.

[0338] The copolyamides are therefore very well suited for packagings in which water is intended to migrate out of the packaging.

[0339] FIG. 2 shows the water permeability from a sealed pouch made of material A-1 having a film diameter of 26.73 m, and made of material C-3 having a film diameter of 24.67 m. Whereas a pouch made of copolyamide C-3 according to the invention had released all the water from its interior to the ambient air after 8 days, the pouch made of material A-1 still contained 82% of the water. Both pouches were stored next to one another at a room temperature of 23 C. and 50% relative humidity.