GB2109354A - Container closure and assembly - Google Patents

Abstract

An unlined one-piece synthetic plastics closure cap for a container having an open neck, is formed with a centrally depressed top wall forming a projection 27 adapted to extend into and close the neck of the container and a flat surface 33 surrounding the projection for full surface abutment with the end edge or face 16 of the neck 15 of the container when the cap is screwed onto the container. The cap may be made from polypropylene, and the container may be integrally blow moulded from PVC. The cap may be used as a measure. <IMAGE>

Description

SPECIFICATION Container closure and assembly The present invention relates to removable closures for containers and particularly to special closure structures and the assembly thereof with certain containers.

In its preferred embodiment the invention will be described in association with a container assembly of the type disclosed in U.S.

Letters Patent No. 4,269,722 issued 26th May, 1981 to Joshi et al. As will appear the container may be the same as disclosed in Joshi et al except for the neck arrangements.

According to the present invention a container closure structure is integrally formed of a stiff synthetic plastics material, such as polypropylene having its top wall indented to provide an internal projection that is adapted to close the open end of the container neck when installed thereon. The projection is preferably surrounded at its base by an annular flat surface adapted to seat tightly in full surface direct engagement with and all the way round the upper edge or face of the opening at the end of the neck of the container.

The invention also extends to a container assembly consisitng of a container and a closure in accordance with the present invention wherein the closure is secured upon the container by a threaded connection located so as to pull the flat sealing surface of the closure tight upon the edge of the container neck.

The invention also extends to a generally cylindrical container closure having an indented top wall providing an internal cylindrical neck-closing projection surrounded by an annular planar surface adapted to seat tightly upon the end edge or face of the container neck and to coact with a correspondingly located external thread formed on the container neck just below the edge of the dispensing opening.

Suitable synthetic plastics materials for the cap include polypropylene and other materials having similar inherent flexibility.

The invention may be put into practice in various ways and one specific embodiment will be described by way of example to illustrate the invention with reference to the accompanying drawings in which: Figure 1 is a side view showing a container closure cap according to a preferred embodiment of the invention; Figure 2 is a plan view looking up into the interior of the closure of Fig. 1; Figure 3 is a section on line 3-3 of Fig. 2; Figure 4 is an enlarged partial section showing coaction of the closure of Fig. 1 with the container neck; and Figure 5 is an illustrative side view showing a filled and closed container in its normal disposition after packaging for shipment.

Referring to the drawings a closure cap 11 in accordance with the invention is provided for the container 1 2. The cap 11 is integrally formed of polypropylene while the container is integrally formed of polyvinylchloride, for example by blow moulding and is transparent so that the colour of it contents may show.

Clearly other suitable synthetic plastics materials can be used and the container need not be transparent.

The container 1 2 is of any desired shape and dimensions and except for the location of the external threads on the container neck, may be essentially the same as used prior to the invention and shown in the Joshi et al patent.

The container 12 comprises a body 1 3 defining a through-opening having rounded edges and affording a handle 14 at one side of the body One end of the body is preferably provided with assymmetrically disposed inclined shoulders leading to a neck 1 5 which is thus offset to the other side of the centre line of the container from the handle.

The neck is of reduced diameter and is cylindrical and terminates in an open mouth surrounded by an annular axially facing flat smooth end surface 1 6. The end surface 16 lies in a plane perpendicular to the axis A of the neck of the container (see Fig. 4). The inner surface 1 7 of the neck 1 5 is smooth and cylindrical, and it contacts or intersects with or runs into the end surface 1 6 in a circular line indicated at 1 8.

A substantially helical external thread 1 9 consisting of a single revolution with a slight overlap is integrally formed on the neck 1 5 adjacent the edge thereof just downwardly of the opening or mouth. A flat shoulder 21 lying in a plane parallel to the surface 1 6 is provided at the juncture between the neck 1 5 and the inclined shoulders of the body 13, and an external shallow finishing groove 22 is formed in the neck 1 5 just above the shoulder 21. This finishing groove is adapted to coact with a trimming apparatus (not shown) which cutssthe end surface 1 6 and which has lying opposite it an internal continuous rib 23 which maintains the wall thickness of the neck and gives it rigidity.

The cap 11 is symmetrical about an axis B (see Fig. 3) and comprises a top wall 24 and a depending generally cylindrical side wall 25.

The top wall is indented to form a central depressed relatively shallow recess 26 that exhibits an annular side wall 27 and a bottom wall 28. As shown, the walls 27 and 28 are of uniform thickness and substantially maintain the thickness of the side wall 25 of the cap.

The outer peripheral surface 29 of the side wall 27 of the recessed portion 26 is smooth and preferably either cylindrical or with a slight inwardly converging conical taper. Thus there is provided within the cap a substantialy cylindrical inwardly directed projection 30 which, as will appear, is dimensioned so as to be adapted to fit snugly within the neck opening of the container 1 2 so as to form a cylindrical seal therewith.

The end portion 31 of the side wall 25 of the cap is, where it joins the top wall 24 of the cap, of about the same thickness as the side wall 27 and the bottom wall 28. The end portion 31 uniformly surrounds the side wall of the recess and defines with the top wall 24 and the side wall 27 an annular recess which surrounds the projection 30 and as will appear receives the end 39 of the neck 4 5 of the container when the cap is on the container, so as to form a ring-like or annular seal with the end surface 1 6 of the neck.

The bottom of the recess 32 is a smooth flat annular surface 33 that is planar, smooth and accurately disposed at right angles to the central axis of the cap. The surface 33 extends right round the base of the projection 30 and perpendicularly intersects the surface 29.

A generally helical thread 34 is integrally formed inside the cap side wall 25 and extends from the recess 32 to the neck portion of the cap. The thread 34 matches the thread 19 on the neck of the container and preferably extends for more than two revolutions as shown.

The outer surface 35 of the recess 26 in the cap is curved, and the inner surface 36 thereof is correspondingly curved intersecting the lower end of the outer peripheral surface 29 of the side wall of the recess in a circle as indicated at 37. This provides a bowed, inverted dome central region for the top wall of the cap, which strengthens that wall against lateral collapse when the cap is screwed onto the neck of the container as will appear. The recess 32 thus surrounds the domed internal projection 30 in the cap.

The skirt portion of the side wall of the cap below the thread may, as indicated at 38, be thinner than the other portions of the cap because it is not subjected to appreciable stress when the cap is installed, thus permitting a savings in material. If desired, light, stiffening ribs 43 may be provided to make the skirt somewhat more rigid. The outer side and end surfaces of the closure may be fluted as shown at 41 similarly to the closure cap in Joshi et al.

In a cap having a diameter of about 1.75 inches (4.4 cms) and a side wall length of about 1 1/16 inches (2.7 cms) the depth of the recess 32 may be about 0.25 inch (0.64 cms).

The container 1 2 is normally used to package a relatively heavy detergent powder such as that disclosed in the said Joshi et al patent, and the cap 1 2 is employed as a measuring device since only small quantities of this detergent are required for normal washing machine loads.

For example the cap here defined has a volume of 1/8 cup, so that two fillings will supply the normal i cup of this detergent which is usually used.

As the cap is placed over the container neck it is turned about its axis and engagement of the threads pulls the cap axially onto the neck until the projection 30 enters the open mouth of the neck and the flat end surface 1 6 of the neck is in tight full surface engagement or ring-like contact all around with the flat surface 33 of the cap. The inherent flexibility of the plastics materials involved compensates for slight tolerances in moulding whereby the projection 30 fits snugly and tightly with the inside surface 1 7 of the neck of the container to provide a longitudinal or cylindrical seal between surfaces 1 7 and 29 that is substantially continuous with the axial seal between the surfaces 16 and 33.

Thus the interior surface 1 7 of the neck 1 5 is perpendicular to the distal surface of the neck 1 5 and the sealing arrangement provides for double contact, that is to say the corresponding portions of the cap, interior side wall 27 and interior surface 33 are also perpendicular and when in sealing engagement the perpendicular surfaces of the neck are in tight contact with the corresponding perpendicular surfaces of the cap.

In addition the projection 30 helps to maintain the cylindrical shape of the neck of the container whilst the cap is being turned on the thread on the neck, and the assembly is made increasingly tight.

By locating the screw thread connection near the outer end of the neck of the container which is also where the cap wall thickness is greatest, a more efficient coupling of the cap with the container is achieved.

By indenting the top wall of the closure with the recess the available internal volume of the closure for accurate dosage measure ment may be accurately controlled, while preserving the height appearance of the cap relative to the container.

Thus in summary the advantages of the closure and assembly disclosed over that disclosed in the said Joshi et al patent are: (1) An unlined cap is provided which ex hibits a better seal with the container neck. In addition the mechanical advantages, elimination of a liner reduces manufacturing time and other costs.

(2) The new structure provides a stronger closure of better external appearance and bet ter holding of the closure on the container neck in the assembly.

(3) Cap damage during transit is practi cally elminated. As shown in Fig. 5 these detergent containers are shipped disposed up side down in cartons. Previously, when a carton was slammed down onto a rigid sur face such as that at 42 in Fig. 5, the impact could result in considerable breakage of the prior design of the cap. However, where in accordance with the invention, the end edge of the container neck is in solid abutment with the bottom wall of the cap as shown in Fig. 4, a considerable reduction in cap damage has been observed under comparable circumstances.

(4) The new construction is so proportioned that it requires considerably less plastics material, thereby effecting an appreicable saving.

(5) By indenting the top wall of the cap, accurate control of the volumetric capacity thereof is attained while preserving the external appearance of the cap design. For example in the case of a known detergent, the volumetric capacity of the cap is 1/8 cup, and accuracy is important to avoid wasting expensive detergent.

Claims (10)

1. A one-piece synthetic plastics container closure cap having a top wall and a depending side wall, the said top wall being indented to form a projection extending into the interior of the cap the projection having a cylindrical periphery surrounded at its base by an annular flat surface lying in a plane at right angles to the axis of the cap and internal thread means on the inner periphery of the said depending side wall.

2. A one-piece cup-shaped synthetic plastics container closure cap having a top wall and a depending side wall, said top wall being centrally indented to form an internal shallow projection having a cylindrically periphery surrounded at its base by an annular flat surface lying in a plane at right angles to the periphery of the projection, and internal thread means on the inner periphery of said side wall.

3. A closure cap as claimed in Claim 1 or Claim 2 in which the said thread means is adjacent the said projection.

4. An integral synthetic plastic closure cap adapted for use with a container having an externally threaded open annular neck, the said cap being cup-shaped and having a top wall with an annular side wall extending from the outer periphery of the said top wall, means providing an indented depressed region centrally of the said top wall forming with adjacently surrounding region of the said side wall an annular recess for receiving the open end of the said neck of the container, the said annular recess having a flat bottom adapted to receive in direct full surface abutment the axially facing end edge or face of the said open neck, the said depressed region of the cap providing a projection adapted to extend into the open end of the neck of the container to fit within the inner surface of the said neck, internal thread means within the side wall of the cap located adjacent to and extending downwardly from the said annular recess and adapted to coact with the said external thread around the neck, the cap being so constructed and arranged that when it is placed over the said neck and screwed on tight the said projection will close the neck opening and the end edge or face of the said neck will be in solid abutment with the flat bottom of the said annular cap recess.

5. A closure cap as claimed in Claim 4 in which the said projection provides within the said recess a substantially cylindrical surface that intersects the flat bottom of said recess substantially perpendicularly.

6. A closure cap as claimed in Claim 4 or Claim 5 in which the said bottom wall and the region of the said side wall that surrounds the said recess and bears the said thread means are of substantially uniform thickness.

7. A closure cap as claimed in Claim 1 substantially as specifically described herein with reference to Figs. 1 to 4 of the accompanying drawings.

8. A container assembly comprising a container having an open generally cylindrical neck having a flat end or face and external thread means adjacent the open end of the said neck, a one piece cup-shaped having a top wall with an annular side wall extending from the outer periphery of the said top wall, means providing an indented depressed region centrally of the said top wall and forming with the adjacently surrounding region of the said side wall an annular recess adapted to receive the open end of the said neck of the container, the said annular recess having a flat bottom adapted to engage in direct full surface abutment the axially facing end edge of the said open neck, the said depressed region of the cap providing a projection adapted to extend snugly within the open end of the neck of the container, and to tightly fit in the inner periphery of the said neck, internal thread means within the side wall of the cap located adjacent to and extending downwardly from the said annular recess and adapted to coact with the said external thread means around the neck, the said parts being so constructed and arranged that when the said cap is placed over the said neck and screwed on tight the said projection closes the open end of the said neck, the end edge of the said neck is in solid abutment with the flat bottom of the said annular recess in the said cap.

9. An assembly as claimed in Claim 8 in which the region of contact between the peX phery of the said projection and the internal periphery of the said neck intersects substantially at right angles the region of contact between the said end edge of the said neck and the bottom surface of the said recess.

10. A container assembly as claimed in Claim 8 substantially as specifically described herein with reference to Figs. 4 and 5 ot the accompanying drawings.