EP1976767A1

EP1976767A1 - Container / closure package having improved seal

Info

Publication number: EP1976767A1
Application number: EP06830672A
Authority: EP
Inventors: Galen German; James L Martin
Original assignee: Crown Packaging Technology Inc
Current assignee: Crown Packaging Technology Inc
Priority date: 2005-12-30
Filing date: 2006-12-15
Publication date: 2008-10-08
Also published as: CA2628619A1; WO2007077110A1; US20070163988A1; WO2007077110A8; AR066179A1

Abstract

A container / closure package 10 comprising a container 12 and a composite closure 40. The container 12 includes a finish portion 16 that terminates in an opening having a peripheral circular lip 26. A taper 36 is formed on an internal surface of the finish portion 16 and this taper 36 merges into the lip 26. The closure 40 includes a circular skirt or band 42, an insert disk 44, and a sealant 74. The insert disk 44 includes a peripheral bead 60, a raised channel 62 inboard of the peripheral bead and a circular centre portion 64 inboard of the channel. The raised channel 62 has an outer wall 66, a substantially flat top portion 68, and an inner wall 70 sloped at approximately the same angle as the taper angle of the container finish portion 16.

Description

Description CONTAINER / CLOSURE PACKAGE HAVING IMPROVED

SEAL Technical Field

[0001] This invention relates to a container and closure package and more particularly to a container and closure package configuration for improving sealing, and method of making such a package.

Background Art

[0002] Container threads may be formed during injection moulding of a preform for a container or may be formed during blow moulding of an injection moulded or extruded preform. The process for forming blow-moulded threads often includes forming an intermediate article that includes a structure above the container finish. For example, Patent Citation 0001 : US 6228317 B -. discloses a moil stricture, formed during blow moulding, that is severed from the container.

[0003] Regardless of the method of forming a container and its threads, composite closures are well known for use for products that are hot filled, retorted, pasteurized, or undergo like heat treatment.

Disclosure of Invention

[0004] A goal of the present invention is to provide a package including a container and composite closure having improved sealing capabilities and a corresponding method for manufacture of such a package.

[0005] A retortable package according to the invention includes a container and a composite closure. The container includes a finish portion that terminates in an opening having a peripheral circular lip. A taper is formed on an internal surface of the finish portion and this taper merges into the lip. The taper in transverse cross section forms an angle of 6° to 14° to the vertical. The closure includes a circular skirt, an insert disk, and a sealant. The insert disk includes a peripheral bead, a raised channel inboard of the peripheral bead and a circular centre portion inboard of the channel. The raised channel has an outer wall, a substantially flat top portion, and an inner wall sloped at approximately the same angle as the taper angle of the container finish portion.

[0006] Sealant is disposed in the channel and is at least partially deformed upon ap- plication of the closure to the container. Thus, the sealant forms a seal between the closure and each of (i) an outer wall of the finish portion proximate the lip, (ii) the lip, and (iii) the taper. After retorting, the seal between the finish portion taper and the channel inner wall is enhanced by the contraction of the finish portion diameter. Preferably, the sealant is groove-less prior to application of the closure to the container. [0007] The taper on the finish portion of the container is preferably spaced apart from the channel inner wall of the closure by a gap of between 0.13 mm and 0.38 mm (0.005" and 0.015") prior to retorting. Preferably, after retorting this gap is reduced to between 0 mm and 0.38 mm (0.00" and 0.015") more preferably between 0.051 mm and 0.25 mm (0.002" and 0.010") and most preferably between 0.076 mm and 0.20 mm (0.003" and 0.008"). The slope of the inner wall of the channel preferably defines a first point on the inner wall proximate the top portion and a second point on the inner wall proximate its centre portion. The uppermost portion of the container lip preferably forms and angle of between 1° and 12° from the horizontal, more preferably between 2° and 8° from the horizontal and most preferably between 2° and 5° from the horizontal.

[0008] A method of forming a container / closure package is also suggested including the steps of:

Providing a moil-trimmed container having a finish portion; reaming a taper on an internal surface of the finish portion; providing a composite closure and applying the closure to the container such that the sealant is deformed by the container finish portion and forms a seal between the closure and each of (i) an outer wall of the finish portion proximate the lip, (ii) the lip, and (iii) the taper; and retorting the container / closure package such that the container finish portion decreases in diameter to diminish a gap between the finish portion taper and the channel inner wall to enhance the seal therebetween.

[0009] The preferred composite closure employed in this method includes a circular skirt, an insert disk, and a sealant. The insert disk includes a peripheral bead, a raised channel inboard of the peripheral bead, and a circular centre portion inboard of the channel. The raised channel includes an outer wall, a substantially flat top portion, and an inner wall sloped at approximately the same angle as the taper angle. The sealant is disposed in the channel.

Brief Description of Drawings

[0010] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0011] [fig.]Figure 1 (Prior At) is a cross section view of a container / closure package including a container and composite closure;

[fig.]Figure 2 is a cross section view of a container package including a container and composite closure illustrating an embodiment of the present invention; and [fig.]Figure 3 is an enlarged view of a portion of the package shown in [fig.]Figure 2.

[0012] Figure 1 illustrates the potential problems with prior art container / closure packages and related methods of manufacture. A prior art container and composite closure package 110 includes prior art container 112 and composite closure 140. Container 112 includes threads 122 formed on an outboard side of the finish and a lip 126 at the uppermost portion of the finish. Closure 140 includes a plastic band 142 and a metal disk 144. Disk 144 includes a peripheral bead or curl 160, a downwardly facing raised channel 162, and a centre portion 164. Sealant 174 is disposed in channel 162. Preferably, sealant 174 is groove-less prior to application of the closure to the container.

[0013] Preferably, container threads 122 are formed by blow-moulding or injection moulding. A projection 113, which protrudes substantially radially inwardly from lip

126, is the lower portion of a stricture formed to locate a blade in a moil trimming operation.

Patent Citation 0002: US 6228317 B -. describes the forming of the container lip and illustrates an inward projection sirh as projection 113. Because lip 126 is pressed into sealant 174, projection 113 inhibits or prevents the flow of sealant 174 toward the inner surface of the container neck, which diminishes or prevents sealing or sealing contact at the container neck, especially at the inner surface.

[0014] Referring to Figure 2, which illustrates an embodiment of the present invention, a container / closure package 10 includes a container 12 and composite closure 40. Closure 40 is provided to illustrate an embodiment of the present invention, and the present invention is not limited to any particular type or material of closure, nor is it limited to any particular closure configuration, and includes for example closures formed in one piece.

[0015] Container 12 has a sidewall 14 that forms an enclosed bottom portion (not shown in the figures). A finish portion 16 extends upwardly from sidewall 14 and includes, in transverse cross section, an outboard side 18 and an inboard side 20. Container threads 22 are formed on the outboard side 18 of the finish portion 16. Preferably, the threads 22 of container 12 are formed by a blow-moulding process. Above the threads, outboard side 18 includes an upper outer sidewall 24 that slopes toward a lip 26. Preferably, container 12 is formed of a thermoplastic, such as polypropylene, or other material suitable for retorting or like heat treatment.

[0016] Lip 26 includes an outer curved transition portion 30 and an inner curved transition portion 32. Preferably, an upper face 34 is disposed between curved transition portions 30 and 32. Upper face 34 may be substantially planar in transverse cross section or may be curved. Transition portions 30 and 32 may be defined by a single radius or multiple radii or may be a substantially flat bevel or like configuration lacking curved surfaces. Transition portion 30 need not have the same configuration as that of transition portion 32. Inner transition portion 32 yields to a taper 36, which merges into the inner surface 38 of the finish portion.

[0017] As best shown in Figure 3, upper face 34 is sloped inwardly and downwardly at an angle C and preferably is straight in transverse cross section. Preferably, angle C is between 1° and 12° from a horizontal line H, more preferably, between 2° and 8°, most preferably between 2° and 5°. The present invention also encompasses an upper face of the finish having a substantially horizontal top as well as an upper face formed of a curve or curves, multiple straight portions, or a combination thereof (not shown in the figures). In such alternative configuration, the angle C may be measured from an outermost point of the upper face to an innermost point of the upper face.

[0018] Preferably, taper 36 (as shown in Figures 2 and 3) is formed by a reaming process that removes projection 113. Taper 36 is substantially flat in transverse cross section or frustoconical and inclined from a vertical line at an angle A. Preferably, angle A is between 6° and 14°. The present invention encompasses configurations of the portion between transition portion 32 and container inner surface 38 other than flat, such as curves, multiple flat surfaces, or a combination thereof. Such alternative configurations (not shown in the figures) are encompassed by the term "taper" as used herein. For such alternative configurations, the angle A may be measured between an upper point where the taper meets transition portion 32 and a lower point where the taper meets inner surface 38.

[0019] Composite closure 40 includes a band 42, which preferably is formed of a plastic, and an insert disk 44, which preferably is formed of a metal. Band 42 includes a skirt 46 and a flange 48 extending radially inwardly from an upper portion of skirt 46. A tamper evident band 50 extends from a lower portion of skirt 46. An inboard surface of skirt 46 includes closure threads 52 and, preferably, a retaining bead 54 that is spaced apart from disk 44 when the closure is applied to the container.

[0020] Pads 56 are formed on the underside of the flange 48 and the space between the pads 56 and retaining bead 54 enables disk 44 to float during application and removal of closure 40. Floating disk 44 enables the initial unscrewing of closure 40 to occur in sequence. First, a torque is required to disengage closure threads 54 from container threads 22, then a torque is required to breake the frangible bridges of the tamper evident band 50 and then retaining bead 54 urges upwardly against disk 44 as the closure 40 is unscrewed. The present invention is not limited to sequential opening configurations, but sirh configuration is employed for illustration. For example, the present invention may be employed with closure / container combinations that employ ratchets rather than spaced pads.

[0021] Disk 44 includes a peripheral bead 60, a downwardly-opening channel 62 disposed radially inward of bead 60 and a circular centre portion 64 disposed radially inward of channel 62. Channel 62 is composed by an outer wall 66, a top 68 extending from outer wall 66 and an inner wall 70 extending from top 68. Preferably, top 68 is linear in transverse cross section. Top 68 may be sloped inwardly and downwardly at an angle sirh that top 68 forms a frustum of a cone. Preferably, the angle C is between 1° and 12° from a horizontal line H, more preferably, between 2° and 8°, most preferably between 2° and 5°. Preferably, the angle of slope of top 68 matches angle C of container upper surface 34, and the shape in transverse cross section of top 68 matches that of upper surface 34. The present invention also encompasses a channel having a substantially horizontal top and a curved top (not shown in the figures).

[0022] As shown in Figure 2, channel inner wall 70 forms an angle B with the vertical.

Preferably, inner wall 70 is straight-sided in transverse cross section. The invention encompasses a curved or irregularly-shaped wall, in which configuration angle B may be measured between a first point on inner wall 70 proximate a transition to top 68 and a second point on inner wall 70 proximate centre portion 64. Preferably, channel inner wall angle B is substantially the same as that angle A of taper 36.

[0023] As best shown in Figure 2, taper 36 is spaced apart from channel inner wall 70 by a gap G. Gap G for the embodiment illustrated may be 0 mm to 0.51 mm (0.000 to 0.020") preferably between 0 mm and 0.38 mm (0.00" and 0.015") more preferably between 0.05 mm and 0.25 mm (0.002" and 0.010") and most preferably between 0.076 mm and 0.20 mm (0.003" and 0.008"). The container 12 often is not circular after retorting and gap G may vary around the circumference. Accordingly, the dimensions quoted above for gap G are averages. Sealant 74 forms an outside seal against an outboard side of finish portion 16 (preferably on transition 30 and outboard side 18) a top seal against upper face 34, and an inboard seal against an inboard side of finish portion 16 (preferably on transition 32 and taper 36). The inside seal is enhanced because projection 113 from the moil trimming operation has been removed upon formation of the taper 36.

[0024] Because package 10 may be subjected to retorting, pasteurizing, or other sterilizing or heat-treatment step, the plastic material of container 12 may shrink upon application of heat while the metal disk maintains its dimensions. The inner radius, shown schematically as dimension R in Figure 2, of container 12 will diminish after such heating step and the gap (dimension G) will decrease, thereby enhancing the inner seal.

[0025] The present invention also encompasses a method of forming a container package having an improved seal. In this regard, container 12 is provided with a moil (not shown in the figures) that is removed by a moil trimming operation. Patent Citation 0003: US 5617768 B -. discloses apparatus and methods for moil trimming. The interior portion of the container neck is reamed to form a taper 36 on an interior portion of the finish.

[0026] A composite closure 40 is applied to container 12 and the sealant 74 is deformed by the container finish portion 16. Thus, sealant 74 forms a seal against each of (i) an outer wall of the finish portion 16 proximate the lip 26, (ii) the lip 26, and (iii) the taper 36, as described above. Container / closure package 10 is retorted or otherwise heat treated such that container finish 16 decreases in diameter to diminish the gap G between the finish portion taper 36 and channel inner wall 70 to enhance the seal therebetween.

[0027] Aspects of container / closure package, such as the retorting process or like heat treatment, the formulation and processing of the container such that it is suitable for reforming, manufacture and well-known structure and functional aspects of the closure and methods and apparatus for the reaming processes are all understood by persons familiar with container and£>r closure manufacture, and any of such processes may be applied to produce the structure described herein.

[0028] The embodiments described herein are employed to illustrate the present invention. The present invention, however, is not limited to the particular structure disclosed herein.

Claims

[0001] A retortable container / closure package 10 comprising: a container 12 having a finish portion 16; having an outboard side 18, an inboard side 20 and a lip 26, a composite closure 40 comprising a band 42 and an insert disk 44; the insert disk 44 having a channel 62 defined by an outer wall 66, a top 68 and an inner wall 70, and a sealant 74 disposed in the channel 62, the sealant being partially deformed upon application of the closure 40 onto the container 12 characterised in that the inboard side 20 of the finish portion 16 defines a taper 36, which merges into the lip 26, the inner wall 70 of the channel 62 is sloped at approximately the same angle as the angle of the taper 36, and the sealant 74 forms a seal between the closure 40 and the container 12 at each of

(i) the outboard side 18 of the finish portion 16 proximate the lip 26, (ii) the lip

26 and (iii) the taper 74. [0002] A retortable container / closure package 10 according to claim 1, wherein the taper 36, in transverse cross section, is at an angle of 6° to 14° to the vertical. [0003] A retortable container / closure package 10 according to claim 1 or claim 2, wherein the taper 36 is spaced from the inner wall 70 of the channel 62 by a gap

G of between 0.13 mm and 0.38 mm (0.005" and 0.015") on application of the closure 40 to the container 12. [0004] A retortable container / closure package 10 according to any of the preceding claims, wherein the inner wall 70 of the channel 62 is curved. [0005] A retortable container / closure package 10 according to any of the preceding claims, wherein the uppermost surface of the container lip 26 is arcuate. [0006] A retortable container / closure package 10 according to any of the preceding claims, wherein the uppermost surface of the container lip 26 forms an angle of between 1° and 12° from the horizontal. [0007] A method of forming a container / closure package 10 comprising the steps of; providing a moil-trimmed container 12 having a finish portion 16; reaming a taper 36 on an inner surface 38 of the finish portion 16; providing a composite closure 40 comprising a band 42 and an insert disk 44; the insert disk 44 having a channel 62 defined by an outer wall 66, a top 68 and an inner wall 70, and having a sealant 74 disposed in the channel 62 and applying the closure 40 to the container 12 such that the sealant 74 is deformed by the container finish portion 16 and forms a seal between the closure 40 and each of (i) an outer wall of the finish portion 16 proximate the lip 26, (ii) the lip 26, and (iii) the taper 36; and retorting the container / closure package 10 such that the container finish portion 16 decreases in diameter to diminish the gap G between the taper 36 and the inner wall 70 of the channel 62 to enhance the seal therebetween.

[0008] A method of forming a container / closure package 10 according to claim 7, wherein the gap G is between 0 mm and 0.38 mm (0.00" and 0.015") after retorting.

[0009] A method of forming a container / closure package 10 according to claim 7, wherein the gap G is between 0.05 mm and 0.25 mm (0.002" and 0.010") after retorting.

[0010] A method of forming a container / closure package 10 according to claim 7, wherein the gap G is between 0.07 mm and 0.2 mm (0.003" and 0.008") after retorting.