CLOSURE FOR A PRODUCT-RETAINING CONTAINER

Abstract

A closure for a container is disclosed. The closure comprises a core member comprising at least one thermoplastic polymer, and at least one peripheral layer at least partially surrounding and intimately bonded to at least one surface of the core member, said peripheral layer comprising at least one styrene block co-polymer, wherein the core member has a density in the range of from about 100 kg/m.sup.3 to 350 kg/m.sup.3 and the peripheral layer has a density in the range of from greater than 350 kg/m.sup.3 to about 1,500 kg/m.sup.3 and a thickness in the range of from 0.15 mm to less than 0.50 mm.

Claims

1. A closure for a product-retaining container constructed for being inserted and securely retained in a portal forming neck of said container, said closure comprising: A. a core member comprising at least one thermoplastic polymer and being devoid of a styrene block copolymer; and B. at least one peripheral layer at least partially surrounding and intimately bonded to at least one surface of the core member, said peripheral layer comprising at least one styrene block co-polymer, and at least one further polymer or copolymer different from the at least one styrene block copolymer and selected from the group consisting of thermoplastic polyolefins, thermoplastic polyurethanes, thermoplastic polyamides, thermoplastic copolyesters and thermoplastic vulcanisates, wherein the at least one styrene block copolymer is present in an amount in the range of from about 15 wt. % to about 88 wt. %, and the at least one further polymer and/or at least one further copolymer is or are present in an amount in the range of from about 12 wt. % to about 85 wt. % wt. %, based on the total weight of the at least one styrene block copolymer and the at least one further polymer and/or the at least one further copolymer, wherein the core member is foamed and the at least one peripheral layer is not foamed, wherein the core member has a density in the range of from about 100 kg/m.sup.3 to 350 kg/m.sup.3 and the peripheral layer has a density in the range of from greater than 700 kg/m.sup.3 to about 1,500 kg/m.sup.3 and a thickness in the range of from 0.15 mm to less than 0.50 mm, wherein said closure is formed by extrusion, and wherein said core member and said peripheral layer are extruded substantially simultaneously or said core member is extruded separately and subsequent thereto said peripheral layer is formed in extrusion equipment peripherally surrounding and enveloping the pre-formed core member.

2. (canceled)

3. The closure according to claim 1, wherein the at least one styrene block copolymer is selected from the group consisting of styrene ethylene butadiene styrene block copolymers, styrene ethylene butylene styrene block copolymers, styrene ethylene butylene block copolymers, styrene butadiene styrene block copolymers, styrene butadiene block copolymers, styrene isoprene styrene block copolymers, styrene isobutylene block copolymers, styrene isoprene block copolymers, styrene ethylene propylene styrene block copolymers, styrene ethylene propylene block copolymers and combinations of two or more thereof.

4.-6. (canceled)

7. The closure of claim 1, having an extraction force determined according to the herein described Extraction Force test method of not more than 400 N.

8. The closure of claim 1, having an oxygen transfer rate (OTR) in axial direction as determined by Mocon measurement using 100% oxygen of from about 0.0001 to about 0.1000 cc/day/closure.

9. The closure of claim 1, wherein the closure has a leakage value measured according to the herein described test method of not more than 900 mm.sup.2.

10. The closure of claim 1, wherein: the core member has a density in the range of from about 100 kg/m.sup.3 to less than 235 kg/m.sup.3 and the closure has a leakage value measured according to the herein described test method of not more than 900 mm.sup.2, or the core member has a density in the range of from 235 kg/m.sup.3 to 260 kg/m.sup.3 and the closure has a leakage value measured according to the herein described test method of not more than 300 mm.sup.2, or the core member has a density in the range of from greater than 260 kg/m.sup.3 to 350 kg/m.sup.3 and the closure has a leakage value measured according to the herein described test method of not more than 200 mm.sup.2.

11. The closure of claim 1, wherein the core member comprises a plurality of cells.

12. The closure according to claim 11, wherein at least one of the size and the distribution of the plurality of cells in the core member is substantially uniform throughout at least one of the length and the diameter of the core member.

13. The closure according to claim 11, wherein the plurality of cells is a plurality of substantially closed cells.

14. The closure according to claim 11, wherein the plurality of cells comprises a cell size in a range of from about 0.025 mm to about 0.5 mm.

15. The closure of claim 1, wherein said core member comprises at least one of closed cells having an average cell size ranging from about 0.02 millimeters to about 0.50 millimeters and a cell density ranging from about 8,000 cells/cm.sup.3 to about 25,000,000 cells/cm.sup.3.

16. The closure of claim 1, wherein said closure has a substantially cylindrical shape comprising substantially flat terminating surfaces forming the opposed ends of said closure and the substantially flat terminating surfaces of the core member are substantially devoid of the peripheral layer.

17. The closure of claim 1, wherein the core member comprises at least one thermoplastic polymer selected from the group consisting of polyethylenes, metallocene catalyst polyethylenes, polybutanes, polybutylenes, polyurethanes, silicones, vinyl-based resins, thermoplastic elastomers, polyesters, ethylenic acrylic copolymers, ethylene-vinyl-acetate copolymers, ethylene-methyl-acrylate copolymers, thermoplastic polyurethanes, thermoplastic olefins, thermoplastic vulcanizates, flexible polyolefins, fluorelastomers, fluoropolymers, polyethylenes, polytetrafluoroethylenes, and blends thereof, ethylene-butyl-acrylate copolymers, ethylene-propylene-rubber, styrene butadiene rubber, ethylene-ethyl-acrylic copolymers, ionomers, polypropylenes, and copolymers of polypropylene and copolymerizable ethylenically unsaturated comonomers, olefin copolymers, olefin block copolymers and mixtures thereof.

18. The closure of claim 1 having an overall density of from about 100 kg/m.sup.3 to about 800 kg/m.sup.3.

19. (canceled)

20. (canceled)

21. A method for producing a closure according to claim 1, said method comprising: A. providing a first composition comprising at least one thermoplastic polymer and being devoid of a styrene block copolymer; B. providing at least one blowing agent to the composition comprising at least one second thermoplastic polymer to obtain a composition comprising at least one thermoplastic polymer and being devoid of a styrene block copolymer and at least one blowing agent; C. at least one of before, during and after method step B, heating the composition obtained in method step B to obtain a heated composition, wherein the heating occurs to a temperature at which the composition obtained in method step B is soft enough to enable foaming to a density of from about 100 kg/m3 to 350 kg/m3 and extrusion of the composition; D. extruding a continuous, elongated, substantially cylindrically shaped length of the heated composition obtained in method step C to obtain, as core member, a continuous elongated length of thermoplastic polymer having a cylindrical surface; E. providing a second composition comprising at least one styrene block co-polymer and at least one further polymer or copolymer different from the at least one styrene block copolymer and selected from the group consisting of thermoplastic polyolefins, thermoplastic polyurethanes, thermoplastic polyamides, thermoplastic copolyesters and thermoplastic vulcanisates, wherein the at least one styrene block copolymer is present in an amount in the range of from about 15 wt. % to about 88 wt. %, and the at least one further polymer and/or at least one further copolymer is or are present in an amount in the range of from about 12 wt. % to about 85 wt. %, based on the total weight of the at least one styrene block copolymer and the at least one further polymer and/or the at least one further copolymer; F. extruding a separate and independent peripheral layer of the composition provided in method step E separately to, co-axially to and in intimate bonded engagement with the continuous, elongated length of thermoplastic polymer obtained in method step D, said separate and independent peripheral layer peripherally surrounding and substantially enveloping the cylindrical surface of the continuous, elongated length of thermoplastic polymer to obtain a multi-component elongated structure having a cylindrical surface; G. cutting the multi-component elongated structure obtained in method step F in a plane substantially perpendicular to the central axis of said multi-component elongated structure to obtain a closure; H. optionally printing, coating, or post-treating at least one of the continuous elongated length of thermoplastic polymer obtained in method step D, the multi-component structure obtained in method step F and the closure obtained in method step G.

22. A closure for a product-retaining container constructed for being inserted and securely retained in a portal forming neck of said container, said closure comprising at least: A. a core member comprising at least one foamed thermoplastic polymer, and B. at least one peripheral layer at least partially surrounding and intimately bonded to at least one surface of the core member, wherein the core member has a density in the range of from about 100 kg/m.sup.3 to about 250 kg/m.sup.3 and the closure has a leakage value measured according to the herein described test method of not more than 300 mm.sup.2.

23. A closure for a product-retaining container constructed for being inserted and securely retained in a portal forming neck of said container, said closure comprising at least A. a core member comprising at least one foamed thermoplastic polymer, and B. at least one peripheral layer at least partially surrounding and intimately bonded to at least one surface of the core member and having a thickness in the range of from 0.15 mm to less than 0.50 mm, wherein the core member has a density in the range of from about 100 kg/m.sup.3 to about 350 kg/m.sup.3 and the closure has a leakage value measured according to the herein described test method of not more than 500 mm.sup.2.

24. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0129] For a fuller understanding of the nature and objects of the present disclosure herein described, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

[0130] FIG. 1 is a perspective view of a synthetic closure according to an aspect of the present disclosure;

[0131] FIG. 2 is a cross sectional-side elevation of a synthetic closure according to an aspect of the present disclosure;

[0132] FIG. 3 is a schematic depiction of the jaws of a bottling machine which have been adjusted in order to misalign the jaws, before compression;

[0133] FIG. 4 is a schematic depiction of the jaws of a bottling machine which have been adjusted in order to misalign the jaws, during compression;

[0134] FIG. 5 is a schematic depiction of a jaw of a bottling machine showing the assembling screws; and

[0135] FIGS. 6A and B show schematically particular steps of the skin adhesion test method.

DETAILED DESCRIPTION

[0136] By referring to FIGS. 1-6B, along with the following detailed disclosure, the construction and production method for the synthetic closures of the present disclosure can best be understood. In these Figures, as well as in the detailed disclosure herein, the synthetic closure of the present disclosure, and its method of production, is depicted and discussed as a bottle closure for wine products. However, as detailed herein, the present disclosure is applicable as a synthetic closure for use in sealing and retaining any desired product in any desired closure system. However, due to the stringent and difficult demands placed upon closures for wine products, the detailed disclosure herein focuses upon the applicability of the synthetic bottle closures of the present disclosure as a closure for wine bottles. However, it is to be understood that this detailed discussion is provided merely for exemplary purposes and is not intended to limit the present disclosure to this particular application and embodiment.

[0137] In FIGS. 1 and 2, the exemplary construction of a synthetic closure 20 is depicted comprising a generally cylindrical shape formed by core member 22 and peripheral layer 24 which peripherally surrounds and is intimately bonded to core member 22. In the exemplary aspect, core member 22 comprises a substantially cylindrically shaped surface 26, terminating with substantially flat end surfaces 27 and 28. Whenever applicable, the following detailed description of a synthetic closure having a layered structure, i.e. a core member and a peripheral layer, shall also apply to multilayer closures having more than one peripheral layer.

[0138] In an exemplary aspect, peripheral layer 24 is intimately bonded directly to core member 22, peripherally surrounding and enveloping surface 26 of core member 22. Peripheral layer 24 incorporates exposed surface 29, which comprises a substantially cylindrical shape and forms the outer surface of synthetic bottle closure 20 of the present disclosure, along with surfaces 27 and 28 of the substantially flat terminating ends.

[0139] In order to assist in assuring entry of synthetic bottle closure 20 into the portal of the bottle into which closure 20 is inserted, terminating edge 31 of peripheral layer 24 may be beveled or chamfered. Similarly, terminating edge 32 of peripheral layer 24 also may comprise a similar bevel or chamfer. Although any desired beveled or chamfered configuration can be employed, such as a radius, curve, or flat surface, it has been found that by merely cutting ends 31 and 32 with an angle of about 45° or about 60° the desired reduced diameter area is provided for achieving the desired effect.

[0140] By incorporating chamfered or beveled ends 31 and 32 on synthetic bottle closure 20, automatic self-centering is attained. As a result, when synthetic bottle closure 20 is compressed and ejected from the compression jaws into the open bottle for forming the closure thereof, synthetic bottle closure 20 is automatically guided into the bottle opening, even if the clamping jaws are slightly misaligned with the portal of the bottle. By employing this configuration, unwanted difficulties in inserting bottle closure 20 into any desired bottle are obviated. However, in applications which employ alternate stopper insertion techniques, chamfering of ends 31 and 32 may not be needed. Further, in order to facilitate the insertion of the closure into the bottle neck, the outer surface can fully or partly be coated with suitable lubricants, in particular with silicones. Coating with lubricants such as silicones can be effected by a variety of techniques known in the art, including tumbling and/or extrusion coating.

[0141] In order to produce the attributes suitable for use in the wine industry, core 22 is formed from foam plastic material as described herein using a continuous extrusion process. Although other prior art systems have employed molded foamed plastic material, these processes have proven to be more costly and incapable of providing a final product with the attributes of the present disclosure.

[0142] In order to demonstrate the efficacy of the present disclosure, samples of synthetic bottle closures 20, manufactured in accordance with the present disclosure and having a foamed core member and a solid peripheral layer were produced and tested.

Exemplary Test Methods

[0143] The tests for extraction force and compression recovery were carried out on a random sample selection according to the methods described in WO 03/018304 A1 (compression test, p. 45, 1. 9-p. 48, 1. 12; extraction test, p. 48, 1. 13-p. 49, 1. 10), which are herewith incorporated and form part of the present disclosure.

Extraction Force

[0144] Six clean “Bordeaux” style wine bottles were filled with wine to the 20° C. fill mark using a 63 mm fill gauge. The insides of the bottlenecks were dried with a paper towel to remove wine splashes. The closures were inserted into the bottles using a semi-automatic corking machine (Model 4040 from GAI S.p.A., Italy). Insertion was carried out under a vacuum of less than −20 mm Hg, as read on the corking machine's vacuum gauge. There was approximately 17 mm ullage after insertion of the closures. The bottles were stored for 48-72 hours. The closures were then extracted at ambient temperature using a Dillon AFG-1000N force gauge (from Dillon/Quality Plus, Inc., USA) to measure the force required for extraction.

Instantaneous Diameter and Compression Recovery

[0145] The instantaneous diameter is determined using an optical micrometer (Keyence 7650 and DATAQ 158-U Analog to Digital converter) positioned at the outlet of the corking machine, which measures the diameter of the closure immediately after the closure has exited the corking machine into the bottle. The percent recovery (compression recovery) can be calculated based on the original, uncompressed diameter of the closure and the diameter measured as for instantaneous diameter, but at two minutes after the closure has been compressed and exited the corking machine into the bottle, according to the equation:

% recovery=(diameter at 2 minutes post-compression/original diameter)×100.

Leakage

[0146] A Monobloc Comet 200 Multi bottling machine, manufactured by Costral S.A. (Riquewihr, France) was used in the tests. The line speed was 2025 bottles/hour, the program selected was Liege 4 and the compression diameter was 15 mm. The fill level was set to 63 mm and checked throughout the test. By reference to FIGS. 3 to 5, the compression jaws 40 (two fixed jaws 41 and two mobile jaws 42) were adjusted by tightening the assembling screws 43 in order to set a gap 44 of 0.2 mm between the mobile 42 and the fixed jaws 41. This gap 44 mimics the wear observed on industrial bottling machines after many hours of working without adjustment. Such wear is a typical source of damage to closures which can cause leakage. In all other respects the bottling machine was operated according to the operating instructions. Bottle racks were prepared with a white folded paper towel at the bottom. Clean 750 ml bottles were prepared. The filling hopper was filled with red wine at ambient temperature, about 22° C. The bottles were filled and corked without vacuum, using closures and comparative closures as described below. Directly after bottling and corking the bottleneck was wiped to remove any wine splash. The bottles were placed upside down in the bottle rack for 30 minutes, then removed from the bottle rack. If any red wine spot or spots were visible on the white paper towel, this leakage area was measured as follows: it is assumed that the leakage areas are ellipses. The smallest (di) and the largest (Di) diameters are measured in mm. The total leakage area is calculated according to formula (I):

Area=Π*Σ(Di*di)/4  (I)

[0147] Nine closures were used per sample lot, and the average values determined. In addition, a control lot was systematically tested at the end of each measurement session.

Skin Adhesion (Peel Force)

[0148] This test provides a measure of the strength of adhesion of the peripheral layer to the core. Reference is made to FIGS. 6A and B. A closure 20 to be tested is scored along the length of the closure parallel to the longitudinal axis thereof, with two parallel cuts 50 at a distance of approx. 8 mm from each other, to a depth equating approximately to the thickness of peripheral layer 24. The cuts are made using a tool having two parallel blades in order to maintain the same distance between the two cuts along the length of the closure. A 5-10 mm portion of peripheral layer 24 is then peeled away from core 22 without detaching, as shown in FIG. 6A. A clamp 51 is attached to an Tinius Olsen force gauge (Model HSKS, from Tinium Olsen, Horsham, Pa., USA) or to an Imada force gauge (Model DS2, equipped with a MV 220 motorized test stand and a RS-232 connection kit) and the force gauge zeroed (not depicted in the Figure). The speed is set to 300 mm/minute. The closure 20 is placed in cork holder 52 with the cut lines 50 aligned within the open area 53 of cork holder 52. The peeled portion of peripheral layer 24 is then held firmly in clamp 51, with the clamp wing nut 54 pointing upwards (FIG. 6B), and the measurement is started. The measurement is stopped either when the entire strip of peripheral layer 24 has been peeled off or when the force gauge stops moving. The test is repeated two more times at different positions for the same closure. At least two closures are tested, giving in total at least six measurements. Each measurement gives up to 200 or more pieces of data, which are averaged for each reading, to give individual averages for each measurement. An average value is then calculated based on these individual averages. A larger value indicates a better adhesion of peripheral layer 24 to core 22.

Example 1

[0149] The sample products were produced on conventional co-extrusion equipment. Core member 22 was produced by employing low density polyethylene (LDPE) using an inert gas as physical blowing agent. The degree of foaming was adjusted so as to produce samples having a density of 231 kg/m.sup.3 (0.231 g/cm.sup.3), 241 kg/m.sup.3 (0.241 g/cm.sup.3) or 261 kg/m.sup.3 (0.261 g/cm.sup.3). In forming peripheral layer 24, a mixture of varying amounts of Maxelast® D01-048E (SEBS polymer from Nantong Polymax Elastomer Technology Co., Ltd) and Dow Affinity 8200 (metallocene polyethylene polymer from Dow Chemical Company) was employed. Each polymer component of the peripheral layer was supplied to a separate reservoir and fed directly from this reservoir to the extrusion equipment, where the respective peripheral layer polymer components were blended with each other and extruded. In the forming process, peripheral layer 24 was formed in the extrusion equipment peripherally surrounding core member 22 and being intimately bonded thereto. The resulting products were cut into lengths suitable for forming bottle closure 20, followed by a chamfer being formed in edges 31 and 32. The resulting closures had a diameter of 22.5 mm or of 23 mm and a length of 37 mm. The Mocon test (OTR measurement system using 100% oxygen) showed that the OTR of the respective closures was not affected by the materials of the peripheral layer.

[0150] For comparison, samples were prepared in an identical manner, with the differences that in forming peripheral layer 24, a mixture of EPDM and PP and metallocene PE was employed, referred to as TPV. The details of the products and the comparative products are shown in Table 1. The product numbers in Table 2 refer to the product numbers as defined in Table 1.

TABLE-US-00001 TABLE 1 Peripheral Layer Peripheral Core Composition (wt. %) layer Product Density Dow thickness No. (g/cm.sup.3) Maxelast 8200 TPV (mm) 1 0.231 0 0 100 0.5 (comp.) 2 0.231 100 0 0 0.4 3 0.231 95 5 0 0.4 4 0.231 90 10 0 0.4 5 0.231 90 10 0 0.3 6 0.231 85 15 0 0.4 7 0.231 85 15 0 0.3 8 0.231 75 25 0 0.4 9 0.231 50 50 0 0.4 10 0.241 0 0 100 0.5 (comp.) 11 0.241 75 25 0 0.4 12 0.261 0 0 100 0.6 (comp.) 13 0.261 75 25 0 0.4 14 0.261 75 25 0 0.5

Example 2

[0151] Samples were tested for the properties of extraction force, compression recovery, skin adhesion and leakage. The comparative closures were subjected to the same tests as the closures according to the present disclosure. The results of the tests are shown in Table 2.

TABLE-US-00002 TABLE 2 Inst. Average Skin Product Diameter % extraction Leakage adhesion No. (mm) Recovery force (N) (mm.sup.2) (N) 1 19.5 96.6 269 500 11.5 (comp.) 2 19.3 96.3 268 100 5.6 3 19.3 96.9 n.d..sup.+ 100 7.5 4 19.3 96.3 n.d..sup.+ 100 7 5 19.3 96.3 n.d..sup.+ 100 6.3 6 n.d..sup.+ n.d..sup.+ n.d..sup.+ 200 n.d..sup.+ 7 n.d..sup.+ n.d..sup.+ n.d..sup.+ 300 n.d..sup.+ 8 19.4 97.1 276 200 n.d..sup.+ 9 19.8 97.1 287 200 10.4 10 n.d..sup.+ n.d..sup.+ n.d..sup.+ 200 n.d..sup.+ (comp.) 11 n.d..sup.+ n.d..sup.+ n.d..sup.+ 100 n.d..sup.+ 12 n.d..sup.+ n.d..sup.+ n.d..sup.+ 100 n.d..sup.+ (comp.) 13 n.d..sup.+ n.d..sup.+ n.d..sup.+ 100 n.d..sup.+ 14 n.d..sup.+ n.d..sup.+ n.d..sup.+ 0 n.d..sup.+ .sup.+n.d. = not determined

[0152] It is expected that leakage values improve (decrease) with increased core density. Surprisingly, the leakage values can be improved with the closures according to the disclosure, compared to known closures, even with a thinner peripheral layer, without impairment or even with improvement of other performance properties of the closure such as extraction force, compression recovery and instantaneous diameter. The diameter recovery and the adhesion of the peripheral layer to the core can be improved by including a proportion of metallocene catalyst polyolefin in the peripheral layer composition.

[0153] It can thus be seen that the samples prepared according to the present disclosure have significantly better resistance to bottling conditions, as measured by the test methods described herein, in particular as measured by the amount of leakage, compared to the comparative samples, without significantly worsening or even with improvement in other performance properties measured. It is thus possible, using the present disclosure, to reduce the overall amount of materials in a closure, by reducing core densities and/or the thickness of the peripheral layer, while maintaining or even improving performance properties of the closure.

[0154] It will thus be seen that the needs set forth above, among those made apparent from the preceding description, are efficiently obtained and, since certain changes may be made in carrying out the above method without departing from the scope of this disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Furthermore, it should be understood that the details of the disclosure described in the foregoing detailed description are not limited to the specific embodiments shown in the drawings but are rather meant to apply to the present disclosure in general as outlined in the summary of the present disclosure and in the claims.

[0155] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present disclosure herein described, and all statements of the scope of the present disclosure which, as a matter of language, might be said to fall there between.