AU2013231119B2 - Cap Closure - Google Patents

Abstract

A container for milk, juice or carbonated drinks has a threaded thin-walled neck and a screw cap for the neck. The screw cap has a seal depending from the cap's crown for the rim of the neck. The seal has a ramp face with a circular groove in the ramp face for reception of the neck rim when the cap is screwed to the neck. The ramp face guides the rim into the groove and establishes a seal. The rim is flared to improve sealing. Extra coaxial seals operate if the containers contents are carbonated. The containers are plastic bottles or milk cartons. 2013 428A9,C:\Users\Sldene\Duens\SPECICATONSIvekcap.wpd.10 2 FIGURE 1 1 18 32 28 34 30t 8 /-- FIGURE 3 T

Description

TITLE OF INVENTION Cap Closure TECHNICAL FIELD

[0001] This invention concerns cap closures for containers such as bottles used in the sale of drinks but is also applicable to bottles and capped bottles used to store carbonated liquids.

BACKGROUND

[0002] Drink bottles are manufactured in large numbers and must survive handling at the point of sale and the shop check out. Leakage is a nuisance to the buyer and seller alike and reliable leakproof operation of the screw caps is desirable. Milk bottles have thin-walled necks and are the main concern of the invention.

SUMMARY OF INVENTION

[0003] One apparatus aspect of the invention provides a container having a threaded thin-walled neck and a screw cap for the neck, wherein the screw cap has a crown and a threaded skirt, a seal for the rim of the neck which depends from the crown and the seal has a ramp face with a circular groove in the ramp face equal in diameter to the neck, whereby upon screw closure the ramp face guides the neck rim into the circular groove and establishes a seal between the rim and the groove.

[0004] The rim of the neck may be inwardly flared, The angle of the flare may be 10-45 degrees, preferably 15-35 degrees. The most preferred angle is 30 degrees but angles of 16,17, 18,19,20, 21, 22, 23, 24, 25, 26, 27, 28 and 29 degrees lead to acceptable sealing. The container material may be HDPE although other polymers give acceptable performance. The thickness of the container including the neck may be 0.5-2.5mm. The diameter of the neck may be 18-63mm. The melt flow index may be approximately 1.8-4.0 mfi.

[0005] The cap may have a tamper-evident ring attached to its perimeter by frangible bridges.

[0006] A second apparatus aspect provides a cap for the neck of a bottle-like container, wherein the crown of the cap has three circular coaxial seals, the inner for contacting the inner surface of the neck, the outer seal for contacting the outer surface of the neck and an intermediate seal for contacting the endmost surface of the neck.

[0007] The inner seal may be of hook section with the end of the hook directed toward the inner surface of the neck.

[0008] The active portions of the three seals are selected to be an interference fit with the rim of the neck in the sense that when the cap is tightened on the neck the seals become urged against different parts of the neck rim.

[0009] The outer seal may be a substantially horizontal flange projecting from the corner which the crown forms with the cap skirt in order to be bent double as the flange obstructs the outer surface of the neck during screwing.

[0010] The intermediate seal may be a circular rib which projects from the crown and has a crest which contacts the endmost part of the neck, namely the annular flat part of the neck.

[0011] While it is the aim of the cap and neck combination to achieve a high sealing score across a large production sample, acceptable sealing scores are achievable by the combination of just two of the seals that is to say a cap with an inner and intermediate seals, a cap with an inner and outer seals and a cap with an intermediate and outer seals.

Advantageous Effects of Invention [0012] 1. Superior sealing of the container contents allow the storage of carbonated liquids or juice.

[0013] 2. The ramp face corrects slight ovality in the neck rim as the cap screws on to the neck. The neck construction is applicable to the moulded necks of milk cartons.

[0014] 3. When the cap is unscrewed the tamper ring tears.

BRIEF DESCRIPTION OF DRAWINGS

[0015] One embodiment of the invention is now described with reference to the accompanying drawings, in which: [0016] Figure 1 is a section of the cap in position on the neck at commencement of sealing.

[0017] Figure 2 is a section of the cap fully screwed on to the neck in order to effect sealing.

[0018] Figure 3 is an enlarged view of the neck and cap with a separate detail showing ridges underlying the tamper-proof band.

[0019] Figure 4 is a cut away perspective of the cap in position on the neck ready to be screwed into the sealing position with the seal inoperative.

[0020] Figure 5 is the same view as Figure 4 but with the tamper-evident band captured by the neck and the seal operative.

[0021] Figure 6 is a close-up of a fragment of the tamper-evident band showing the frangible bridges.

[0022] Figure 7 is a section of a cap with three coaxial seals screwed on to the neck of a thick-walled bottle.

[0023] Figure 8 is a section of a fragment of the cap shown in Figure 7 removed from the bottle.

DESCRIPTION OF EMBODIMENTS

[0024] The embodiment of the invention is described when used as the closure for bottles of milk for sale in a shop. The bottles are of conventional construction with an aperture in the top of the bottles with a moulded neck. A moulded cap is a screw fit on the neck.

[0025] Referring now to the drawings, the neck 2 has a base 4 with a flared portion 6 which creates a stop 8 for insertion into the pack (not shown). An eaves portion 10 underlies a threaded band 12. The neck terminates in an inwardly flared rim 14.

[0026] Cap 16 is a moulding which is double the thickness of the neck, Crown 18 has a depending skirt 20 with threads 22 which engage the band 12. The lower portion of the skirt below bead 24 is constructed as a tamper-evident band 26 to be retained by the eaves portion 10 of the neck. Ridges 27 projecting from the neck assist the capture and removal of the tamperproof band. The crown 18 is spaced from flared rim 14 by depending spigot 28 which is of wedge section. The outer surface 30 of the spigot is inclined such that in Figure 1 the leading edge 32 of the wedge enters the neck rim lying just inside the flared portion.

[0027] The inclined outer surface is interrupted by a circular groove 34 of undercut section. As the spigot descends during cap closure, the flared rim stretches and enters the groove 34. When the cap is screwed further, the rim 14 pushes the groove open and abuts the groove end. This halts the rotation of the cap.

[0028] The spigot’s section is stiff enough to centralise the rim 14 removing any ovality thereby ensuring that the leading edge of the rim fully enters the groove and remains seated therein. The spigot’s leading edge 32 is rounded and the inclined outer face acts like a ramp to progressively direct the rim 14 toward circular groove 34.

[0029] Micro grooves 37 in the sidewalls of circular groove 34 register with micro crests 38 in the spigot when the cap is screwed on to the neck.

[0030] Figure 4 shows the position of the cap after the filling machine has filled the container and the cap tightener is ready to screw the cap onto the neck. The tamper-evident band 26 is resting on the eaves formation 10. Rotation of the cap rotates the band which snaps over the eaves portion 10 to the position shown in Figure 5. In doing so the flared rim 14 has entered the circular groove and is now exerting a seal against the cap. The container is now ready for storage and subsequent sale.

[0031] The band 26 is attached to bead 24 by bridges 36 spaced radially around the cap. These are just strong enough to transmit the torque of initial cap screwing and snapping over the band containing eaves portion 10.

[0032] When the cap is unscrewed an axial pulling force is applied to the bridges which snap immediately. Further unscrewing then breaks the seal.

[0033] Referring now to Figures 7 and 8, the plastic bottle 40 has a thick-walled neck 42 surrounded by circular flange 44 and an eaves configuration 10 for retention of a conventional tamper band 26. The mouth of the bottle is defined by bead 46 which has a cylindrical inner face 48, a tapered outer face 50 and a flat top end 52.

[0034] The moulded screw cap 16 has a crown 18 which incorporates a triple seal. The inner seal has a downwardly depending circular wall 54 which terminates in a hook formation 56 where the end of the hook bears against the cylindrical inner face 48 of the bottle neck.

[0035] The outer seal is a substantially horizontal flange 58 which projects from the comer between the crown 18 and the skirt 20 toward the tapered face 50.

[0036] The intermediate seal is a circular rib 60 with a tapered crest 62 which meets the centre of the bead’s flat top end 52. The cylindrical wall face 54 is separated from the crest 62 by an air gap 64. Likewise the flange 58 is separated from the tapered crest 62 by another air gap 66.

[0037] In Figure 7 the cap has been applied by a capping machine which exerts a predetermined torque on the cap. This ensures that the cap takes up the position shown. The hook 56 tends to fold. The crest 62 is squeezed against the flat end of the bead 46. The flange 58 of the outer seal folds in two as it is squeezed against the inclined face 50 of bead 46. Whereas the inner seal is subjected to the full pressure of the gas dissolved in the bottled drink, the pressure diminishes in stages as it reaches air gaps 68, 64, 66 and 70.

[0038] It is to be understood that the word “comprising” as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word “comprising” does not exclude the addition of other elements.

[0039] It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications and/or additions are therefore considered to fall within the scope of the invention.

Claims (18)

1. A moulded screw cap for a container having a crown and a threaded skirt, a circular seal for the rim of the container neck which seal depends from the crown and the seal has a ramp face with a circular groove in the ramp face equal in diameter to the container rim, whereby upon screw closure the ramp face guides the neck rim into the circular groove such that a leading edge of the rim fully enters the groove and establishes a seal between the rim and the groove.

2. A cap as claimed in Claim l, wherein the circular seal is of wedge section.

3. A cap as claimed in Claim 1 or Claim 2, wherein the ramp face is curved so as to present a convex surface to the container neck.

4. A cap as claimed in any one of Claims 1 to 3, wherein the circular groove is of triangular section.

5. A cap as claimed in any one of Claims 1 to 4, wherein the side walls of the groove which receives the neck have micro crests.

6. A cap as claimed in any one of Claims 1 to 5, wherein the cap has a tamper-evident ring attached to the cap perimeter by frangible bridges.

7. A moulded container when used with the cap of any one of Claims 1 to 6, having a threaded thin-walled neck, wherein the rim portion of the neck is inwardly flared.

8. A moulded container as claimed in Claim 7, wherein the flare angle is 10 to 45 degrees.

9. A moulded container as claimed in Claim 8, wherein the flare angle is 30 degrees.

10. A moulded container as claimed in Claim 8 or Claim 9, wherein the outer edge of the rim portion is inclined imposing a taper on the rim portion.

11. A moulded container as claimed in any one of Claims 7 to 10, wherein the tapered faces of the rim have continuous micro grooves.

12. A moulded container as claimed in Claim n, wherein the micro grooves are 0.2- 0.3mm deep.

13. A moulded container as claimed in any one of Claims 7 to 12, wherein the thin-walled neck is of a thickness which renders it pliable.

14. A moulded container as claimed in Claim 13, wherein the thickness is 0.5-2.5mm.

15. A moulded container as claimed in any one of Claims 7 to 14, wherein the neck diameter is i8-63mm.

16. A moulded container as claimed in any one of Claims 7 to 15, wherein the container is formed from a polymer having a melt flow index of 1.8-4.0 mfi.

17. A moulded container as claimed in any one of Claims 7 to 16, wherein the container is a disposable milk container.

18. A moulded container as claimed in any one of Claims 7 to 17, wherein the container is a carbonated drinks container.