The present invention relates to an improved closure device for tubes, and relates particularly, though not exclusively, to such a device for use in tubes for dispensing adhesive substances.

Background to the Invention

Tubes containing adhesives, silicone sealant or other chemical substances are in frequent use in building and construction applications, either on an industrial scale or in home handyman situations. The relatively rigid tubes are adapted to be received in an applicator or 'gun' designed to push the adhesive from the tube. The gun has a piston, which is typically spring- loaded or pneumatically driven, adapted to slide inside the tube so that when released by a trigger it applies a constant pressure to the rear end of the tube. A tube of adhesive is typically sold with the dispensing end sealed shut. The dispensing end has a threaded connector for attaching a nozzle to the tube by means of a screw threaded arrangement. Prior to use the sealed end of the threaded connector must be punctured to form an opening to allow the contents of the tube to be dispensed through the nozzle.

A problem with this type of tube arises when only part of the contents of the tube is used in a particular job. In that case the tube may be removed from the gun and laid aside and stored for later use. Typically a nail or screw is inserted in the open end of the threaded connector in an attempt to seal the contents from exposure to air and thus prevent the contents of the tube from hardening. However such measures inevitably form a poor seal and do not prevent the ingress of air. Hence when the tube is later retrieved for reuse, the contents are found to have hardened and the tube is useless.

The present invention was developed with a view to providing a means of sealing a tube containing chemical or adhesive substances with a view to preserving the contents of the tube for later reuse. The present invention has also been devised with the intention of providing a tube closure means that allows the partly used tube to be conveniently stored upright in a home handyman or commercial environment, such as on a shelf or in a tool box.

The previous discussion of the background to the invention is provided for illustrative purposes only and is not to be taken as an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge in Australia or elsewhere as at the priority date of this application.

Summary of the Invention According to one aspect of the present invention there is provided a tube closure device for screw-threaded engagement with the threaded end of a tube containing an adhesive or other chemical substance, the tube being in the form of a relatively rigid cylinder of the kind employed in an adhesive gun or applicator, the tube closure device being adapted to seal the threaded end of the tube after use to substantially prevent the ingress of air and hence preserve the contents of the tube for later reuse.

Advantageously the tube closure device is in the form of a cap provided with a sealing means having an internal surface adapted to protrude into an open end of the tube so as to engage with the contents of the tube and form an air-tight seal. Preferably the internal surface of the sealing means is of generally conical or frusto-conical shape. Advantageously the sealing means is formed of resilient material adapted to conform to the shape of the opening formed in the threaded end of the tube. Preferably the cap has a portion formed with an internal thread adapted to match the thread of the threaded end of the tube.

Preferably the tube closure device is in the form of a cap having a body of generally circular shape, the external diameter of the cap body being similar to the external diameter of the tube. Advantageously the body of the cap has a substantially planar surface that lies, in use, substantially orthogonal to a longitudinal axis of the tube, wherein the sealed tube can be stood in a vertical orientation supported on the planar surface of the cap. Advantageously the cap is provided with a cylindrical outer portion, the outer portion having an outer periphery with a grip surface provided thereon to facilitate tightening and loosening of the cap by hand. Typically the grip surface comprises a plurality of indentations.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word "preferably" or variations such as "preferred", will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention.

Brief Description of the Drawings The nature of the invention will be better understood from the following detailed description of a preferred embodiment of a tube closure device, given by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a bottom perspective view of a first embodiment of a tube closure device according to one aspect of the present invention;

Figure 2 is a section view of the tube closure device of Figure 1 and the threaded end of a tube containing an adhesive or other chemical substance prior to closure;

Figure 3 is a section view of the tube closure device of Figure 1 and the threaded end of a tube containing an adhesive or other chemical substance subsequent to closure;

Figure 4 is a bottom plan view of a second embodiment of a tube closure device according to one aspect of the present invention; Figure 5 is a top plan view of the tube closure device of Figure 4; Figure 6 is a side elevation of the tube closure device of Figure 4;

Figure 7 is a section view through the line A-A of the tube closure device of Figure 4;

Figure 8 is a top perspective view of the tube closure device of Figure

4;

Figure 9 is a top perspective view of the tube closure device of Figure 4 and a tube with the nozzle removed;

Figure 10 is a side elevation of the tube of Figure 9 with the tube closure device of Figure 4 attached;

Figure 11 is a section view of the tube and tube closure device through the line A-A of Figure 10; and,

Figure 12 is a top perspective view of the tube and tube closure device of Figure 10.

Detailed Description of Preferred Embodiments

A first embodiment of a tube closure device 10 for screw-threaded engagement with the threaded end of a tube 12, containing an adhesive or other chemical substance, is illustrated in Figures 1 to 3. The tube 12 is of the kind employed in an adhesive gun or applicator (not shown). This type of tube 12 is in the form of a relatively rigid cylinder as shown in Figures 9 to 12.

The tube closure device 10 is adapted to seal the threaded end 14 of the tube 12 after use to substantially prevent the ingress of air and hence preserve the contents of the tube for later reuse.

As can be seen in the Figures 1 to 3, the tube closure device 10 is in the form of a cap 16 provided with a sealing means 18 having an internal surface 20 adapted to protrude into an open end of the tube 12 so as to engage with the contents of the tube and form an air-tight seal. In this embodiment the internal surface 20 of the sealing means 18 is of conical shape, as can be seen in Figures 1 to 3. Advantageously the sealing means 18 is formed of resilient material adapted to conform to the shape of the opening formed in the threaded end 14 of the tube 12. The cap 16 is formed with an internal thread 22 adapted to match the thread of the threaded end 14 of the tube. The cap 16 is also provided with a collar 24.

The tube closure device 10 can be made in any suitable size but typically the tube cap height would be about 16mm, the outside diameter excluding the collar would be about 18mm, the inside diameter about 15mm, and the collar about 3mm in thickness.

A second embodiment of a tube closure device 50 according to the invention is illustrated in Figures 4 to 12. As with the previous embodiment, the tube closure device 50 is designed for screw-threaded engagement with the threaded dispensing end 14 of a tube 12, containing an adhesive or other chemical substance. The tube 12 is in the form of a relatively rigid cylinder, as shown in Figures 9 to 12, of the kind employed in an adhesive gun or applicator (not shown). The tube 12 is provided with a nozzle 32, as shown in Figure 9, for screw-threaded engagement with the dispensing end 14 of the tube. The tube of adhesive is normally sold with the dispensing end 14 sealed shut. Once the sealed dispensing end 14 has been punctured to form an opening, the nozzle 32 is attached to allow the contents of the tube to be dispensed through the nozzle 32. The tube 12 is then placed in a dispensing gun or applicator (not shown) for dispensing the adhesive.

However, if there is still a substantial volume of adhesive remaining in the tube 12 when the job is done, it may be desirable to store the tube for later reuse. The tube closure device 50 is adapted to seal the threaded end 14 of the tube 12 after use to substantially prevent the ingress of air and hence preserve the contents of the tube for later reuse. As can be seen in the Figures 4 to 8, the tube closure device of this embodiment is also in the form of a cap 50. The cap 50 is provided with a body 52 of generally circular shape and having a threaded portion 54 with an internal thread adapted to match the external thread of the dispensing end 14 of the tube 12. The threaded portion 54 has a sealing means 56 provided in connection therewith. The sealing means has an internal surface 58 adapted to protrude into the open dispensing end or threaded end 14 of the tube 12 so as to engage with the contents of the tube 12 and form an air-tight seal as can be seen in Figure 11. In this embodiment the internal surface 58 of the sealing means 56 is of frusto-conical shape, as can be seen most clearly in Figures 7 and 11.

The cap body 52 is also provided with a cylindrical outer portion 59 having an outer diameter approximately equal to the outer diameter of the tube 12 (see Figures 10 to 12). Advantageously the cap body 52 also has a substantially planar surface 60 that lies, in use, substantially orthogonal to a longitudinal axis of the tube, wherein the tube 12 with the cap 50 attached can be stood in a vertical orientation supported on the planar surface 60 of the cap. It is preferred to keep the tube 12 in an upright condition after use (as shown in Figures 10 to 12) so that the adhesive inside the tube remains adjacent the dispensing end 14. This helps to retain an air-tight seal between the cap and the contents of the tube. A further advantage of the planar surface 60 of the cap body 52 is that when the tube 12 is upright the adhesive contents will generally migrate to the dispensing end 14 forming a stable weighted end portion in conjunction with the flat base portion formed by the planar surface 60, which assists in preventing the tube 12 from falling over. Clearly the tube 12 would be unstable if the tube was standing upright and weight of the contents was at the upper end of the tube.

Advantageously the cylindrical outer portion 59 has an outer periphery with a grip surface 62 provided thereon to facilitate tightening and loosening of the cap by hand. Typically the grip surface 62 comprises a plurality of indentations. Preferably a plurality of grip surfaces 62 are provided at spaced intervals about the periphery of the cylindrical outer portion 58. Because of the increased diameter of the outer portion 59 of the cap body 52, the cap 50 can be more easily tightened and removed by hand in view of the increased leverage that can be applied to the threaded portion 54. A plurality of radially- extending ribs 64, connecting the threaded portion 54 to the outer portion 59, provide increased strength and rigidity to the cap 50.

The cylindrical outer portion 59 is provided with a plurality of indented portions 66 arranged around the upper periphery 61 of the outer portion 59, as can be seen in Figure 8. The indented portions 66 are designed to accommodate a screw driver or other elongated tool end when the cap 50 is in use on a tube 12 such as in Figure 10 or 12. In this embodiment, the outer portion 59 is provided with three indented portions 66 as can be seen in Figure 8. The indented portions 66 allow access to a screw driver which is used to engage and securely hold the thread 14, for example in the case when the thread 14 is provided as a separate component to the overall tube 12 such that the thread 14 may spin on the tube 12. In this way, movement of the thread 14 about the tube 12 is prevented but movement of the cap 50 about the tube 12 can still be effected.

The tube closure device can be made of any suitable material but typically would be made of a firm injection-moulded plastics material.

Now that preferred embodiments of the tube closure device have been described in detail, it will be apparent that the embodiments provide a number of advantages over the prior art, including the following:

(i) The tube closure device allows the end of a tube of adhesive or chemical substance to be readily sealed after the contents of the tube have been partially used, thereby ensuring that the remaining contents of the tube are not spoiled by contact with the air.

(ii) The tube closure device is in the form of a cap provided with a sealing means having an internal surface of conical or frusto- conical shape that touches the contents of the tube to form an airtight seal, thereby preventing the adhesive from coming into contact with the air.

(iii) By using the tube closure device, there is no wastage of adhesive remaining in the tube which may have otherwise hardened on contact with air.

(iv) Due to the planar surface of the tube closure device, the tube with the tube closure device attached may be conveniently stored in an upright position such as on a shelf or in a work maintenance vehicle.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, the internal surface of the sealing means may be of a shape other than conical or frusto-concical such as dome shaped that will also ensure a good air-tight seal is formed. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described.