Sealing Compounds with Scavenger Materials of Small Particle Size

Abstract

PVC-free polymer compound for producing seals containing scavengers for screw caps, in particular twist crown corks, characterized in that the Shore A hardness of the polymer compound lies between 50 and 90 and, in a compression set test analogous to ASTM D395-97, Method B, the polymer compound has a compression set of between 30% and 90% after it has been left for 22 hours at 70 C. under a compression of 25%.

Claims

1-20. (canceled)

21. A polymer-based composition for a PVC-free sealing insert for a twist crown cap, comprising: at least one oxygen-scavenging substance; at least 20% of at least one block copolymer, wherein the block copolymer is an interpolymer of ethylene and at least one C.sub.3-C.sub.20 alpha-olefin or a copolymer of ethylene and one C.sub.3-C.sub.20 alpha-olefin, optionally in combination with other unsaturated monomers; wherein the Shore A hardness of the polymer-based composition is between 50 to 90 and the polymer-based composition exhibits a compression set of 30-90% in the compressive deformation test analogous to ASTM D395-97 Method B after 22 hours of storage at 70 C. and a compression of 25%.

22. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises thermoplastic elastomer, polyolefin and white oil.

23. The polymer-based composition according to claim 21, wherein the polymer-based composition is free of plasticizer.

24. The polymer-based composition according to claim 21, wherein the polymer-based composition has a Shore A hardness of 60 to 80.

25. The polymer-based composition according to claim 21, wherein the oxygen-scavenging substance is sodium sulfite having an average particle size smaller than 20 m.

26. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 1% to 10% sodium sulfite as oxygen-scavenging substance.

27. The polymer-based composition according to claim 21, wherein the polymer-based composition exhibits a compression set between 30% to 60% in the compressive deformation test after 22 hours of storage at 70 C. and a compression of 25%.

28. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 2% to 20% copolymer consisting of polypropylene and polyethylene.

29. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 5% to 25% low-density polyethylene.

30. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises not more than 10% of lubricants.

31. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 10% to 40% thermoplastic elastomers based on styrene-ethylene-butylene-styrene having a fixed styrene content of 31%.

32. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 20% to 45% white oil.

33. The polymer-based composition according to claim 21, wherein the polymer-based composition comprises between 10% to 30% linear low-density polyethylene.

34. The polymer-based composition according to claim 21, further comprising an additive selected from the group consisting of waxes, silicones, and combinations thereof.

35. The polymer-based composition according to claim 21 which can be foamed by chemical or physical blowing agents.

36. A sealing insert for a twist crown cap comprising the polymer-based composition according to claim 21.

37. A sealing insert for a twist crown cap comprising the polymer-based composition according to claim 21 which exhibits opening values in the range of 0.678 Nm (6 lbf.Math.in) to 1.130 Nm (10 lbf.Math.in) with a target value of 0.791 Nm (7 lbf.Math.in) before and after the pasteurization.

38. A sealing insert for a twist crown cap comprising the polymer-based composition according to claim 21 which exhibits a pressure maintenance of higher than 8 bar after pasteurization.

39. A container closure with a sealing insert which comprises the polymer-based composition according to claim 21.

Description

EXAMPLES

[0040] The oxygen uptake was determined by the Total Oxygen method (Orbisphere technology). For this, bottles are filled with a beer simulant (in terms of pH and CO.sub.2 content) in a glove box and the total oxygen content is measured non-destructively.

[0041] Total package Oxygen (ppm) in this context is the total concentration of oxygen in the filling container (bottle).

[0042] Pasteurized means that the beer simulans has been pasteurized before closing.

TABLE-US-00001 Actega PVC-free oxygen test of Miller twist-off bottles (U.S.) with and without pasteurization Days A [ppm] B [ppm] C [ppm] D [ppm] 6 0.097 0.051 0.086 0.051 26 0.220 0.098 0.215 0.132 53 0.247 0.158 0.265 0.141 94 0.614 0.253 0.689 0.306 146 1.130 0.309 1.231 0.298 181 1.244 0.218 1.493 0.325 A: Svelon TC VP 642394 white B: Svelon TC VP 849189 T/A C: Svelon TC VP 642394 whitepasteurized D: Svelon TC VP 849189 T/Apasteurized Svelon TC VP 642394 white does not contain sodium sulfite/Svelon TC VP 849189 T/A contains sodium sulfite, the material composition is otherwise identical In all experiments, the same amount of material from Svelon TC VP 642394 white/Svelon TC VP 849189 T/A was used