CONTAINER MADE FROM POLYBUTYLENE TEREPHTHALATE HAVING A LOW OXYGEN PERMEABILITY

Abstract

Container made from a thermoplastic molding composition comprising A) from 59.8 to 99.8% by weight of a polyester composed of from 30 to 100% by weight of a polybutylene terephthalate and 0 to 70% by weight of a polyester derived from 1,4-butanediol and a C.sub.2-12-aliphatic dicarboxylic acid and/or C.sub.6-12-cycloaliphatic dicarboxylic acid, B) 0.1 to 10% by weight of an oxidizable polyester-ether, C) 5 to 10000 weight-ppm of a salt of a transition metal, D) 0 to 40% by weight of other additional substances, where the total of the percentages by weight of components A) to B) is 100% by weight.

Claims

1. Container made from a thermoplastic molding composition comprising A) from 59.8 to 99.8% by weight of a polyester composed of from 30 to 100% by weight of a polybutylene terephthalate and 0 to 70% by weight of a polyester derived from 1,4-butanediol and a C.sub.2-12-aliphatic dicarboxylic acid and/or C.sub.6-12-cycloaliphatic dicarboxylic acid, B) 0.1 to 10% by weight of an oxidizable polyester-ether, C) 5 to 10000 weight-ppm of a salt of a transition metal, D) 0 to 40% by weight of other additional substances, where the total of the percentages by weight of components A) to B) is 100% by weight, and the intrinsic viscosity of the polybutylene terephthalate and of component A is in the range from 50 to 220 measured in 0.5% by weight solution in a phenol-o-dichlorobenzene mixture of ratio by weight 1:1 at 25 C. in accordance with ISO 1628.

2. Container according to claim 1, wherein component A) is polybutylene terephthalate.

3. Container according to claim 1, wherein component B) comprises at least one polyether segment comprising poly(tetramethylene-co-alkylene ether), in which the alkylene group is a C.sub.2-C.sub.4 alkylene group.

4. Container according to claim 1, wherein the metal of component C) is chosen from the first, second or third periods of the periodic table of the elements.

5. Container according to claim 1, comprising as additional substance from 0.01 to 2% by weight of an acrylic acid polymer, composed of from 70 to 100% by weight of acrylic acid and from 0 to 30% by weight of at least one other ethylenically unsaturated monomer copolymerizable with acrylic acid, selected from the group of monoethylenically unsaturated carboxylic acids.

6. Container according to claim 1, which is injection-molded.

7. Container according to claim 1, which is compression-molded.

8. Container according to claim 1, which has a wall thickness of below 1 mm.

9. Container according to claim 1, which has an oxygen permeability of less than 5 cc/m.sup.2/d/atm, determined according to DIN 53380-9:1998-D7.

10. Container according to claim 1, which has a filling volume of less than 250 ml.

11. Container according to claim 1, which is in the form of a capsule.

12. Container according to claim 11, wherein the thermoplastic molding composition comprises at least 79.4% by weight of component A), and wherein the container has an oxygen permeability which is at least 30% lower than the oxygen permeability of a container made from component A) alone.

13. Container according to claim 1, wherein the thermoplastic molding composition does not contain any zinc acetate and the polybutylene terephthalate is not prepared by employing a zinc compound selected from the group consisting of zinc oxide, zinc hydroxide, zinc alkoxide, aliphatic acid salt of zinc, zinc carbonate, zinc halide and a complex compound of zinc.

14. A process for producing a container according to claim 1 by melt-mixing components A) to D) and forming the container from the melt.

15. The process of claim 14, including: a. preparation of a master batch of component C) in polybutylene terephthalate by extrusion or melt-kneading, b. melt-blending components A) and B), c. dry-blending the materials from steps a. and b., d. injection-molding or compression-molding of the material of step c. or including a. preparation of a master batch of component C) in polybutylene terephthalate by extrusion or melt-kneading, b. dry-blending the master batch from step a. with component A), component B) and optionally component D), c. injection-molding or compression-molding of the material of step b., or including a. melt-mixing the components A) to D), b. injection-molding or compression-molding of the material of step a.

16. (canceled)

17. A capsule comprising a container according to claim 1 containing ingredients for making beverages.

18. A capsule according to claim 12, wherein the ingredients are coffee powder, tea powder, tea leaves, milk, milk powder, cocoa powder or soft drink components.

19. A thermoplastic molding composition as defined in claim 1.

20. The container according to claim 6, wherein component A) has a viscosity number in the range of from 70 cm.sup.3/g to 130 cm.sup.3/g.

Description

EXAMPLES

[0108] The following components were used.

Component A)

[0109] Polybutylene terephthalate (PBT) having a melt volume rate (MVR) of 110 cm.sup.3/10 min (in accordance with ISO 113 at 250 C. and 2.16 kg) and a viscosity number of 86 ml/g (in accordance with ISO 1628). The material can be obtained from BASF SE, Germany (Ultradur B1520 FC UN).

Component B)

[0110] The polyester-polyether copolymer contains a fraction of polyether (polytetramethylene), equivalent to 25% by weight of the polyester-polyether copolymer. The IV of the copolymer in question was 0.961 dl/g (according to ASTM D4603). The polyester-ether can be obtained from Point Plastic S.R.L., Italy (Passipet 112).

Component C)

[0111] A 6.0% by weight cobalt stearate master batch based on polybutylene terephthalate (Ultradur B2550 FC of BASF SE). The master batch can be obtained from Point Plastic S.R.L (Osmopet 7128).

Component D)

[0112] Polyacrylic acid having a molar mass of 5000 g/mol determined by gel permeation chromatography (GPC), a pH of 2 and a viscosity of 500 mPas. The polyacrylic acid is a 49% by weight solution in water and can be obtained from BASF SE (Sokalan PA 25 X S).

[0113] Component A) was extruded with various additives in a twin-screw extruder at a melt temperature of from 265 to 275 C. through 5 kg/h, and rotational speed of 300 min.sup.1.

[0114] Component D) was added by a pump and an injection vault in zone 4 of the extruder.

[0115] As an alternative, component D) (0.55% by weight) was premixed with component A) (99.45% by weight) to give the master batch Exp. 1.

[0116] The extruded material was then injection-molded to give plaques measuring 60601.0 mm.

Quantitative Emission Analysis

[0117] Quantitative emission analysis was carried out in accordance with VDA 277, a standard method of the German Association of the Automotive Industry (VDA) for the determination of TOC (=total organic carbon emission). VDA 277 is used to investigate the carbon emission of non-metallic materials used in motor vehicles. In this method, the injection-molded plaques, or the pellets after packaging, are comminuted and charged to a glass vessel, which is sealed. The specimen is then stored at 120 C. for 5 hours. The gas volume above the specimen is then analyzed in the gas chromatograph (headspace GC). Emission is determined here in g of carbon (TOC) per gram of specimen.

[0118] The oxygen permeability (OTR) was determined according to DIN 53380-9:1998-D7. The determination of the oxygen permeability followed an oxygen-specific carrier gas process with a MOCON OX-TRAN at a temperature of 23 C. The relative humidity of measuring gas (oxygen) and carrier gas (forming gas) was 50%. All test specimens were conditioned prior to measuring for at least 72 h.

[0119] The tables show the constituents of the molding compositions and the results of the measurements.

TABLE-US-00001 TABLE 1 Reference Comp. 1 Comp. 2 Exp. 2 Exp. 3 Exp. 4 [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] Ultradur 100 99.9 97.90 95.90 B1520 FC UN Exp. 1 99.9 95.90 Osmopet 1 2 2 7128 Passipet 112 1 2 2 Talcum 0.1 0.1 0.1 0.1 0.1

TABLE-US-00002 TABLE 2 (TOC) Composition TOC VDA 277 [ppm] Reference 187 Comp. 1 163 Comp. 2 31 Exp. 2 134 Exp. 3 155 Exp. 4 59

TABLE-US-00003 TABLE 3 (Oxygen Transmission Rate (OTR)) Composition OTR [cc/m.sup.2/d/atm] Reference 1.49 Comp. 1 1.16 Comp. 2 1.19 Exp. 2 0.12 Exp. 3 <0.05 Exp. 4 <0.05

[0120] It is evident from table 2 that by using polyacrylic acid, the TOC value can be reduced significantly. This reduction can also be obtained in combination with components B) and C).

[0121] Table 3 shows that the OTR can be very significantly lowered (in experiments 3 and 4, two values of lower than 0.05) by employing 1200 weight ppm cobalt stearate through component C).