GB2534278A - Nozzle for sealant cartridge - Google Patents

Abstract

There is a nozzle 2 for a sealant cartridge (100 figure 7), the nozzle comprising an elongate tube (4 figure 1) of circular cross section having a principle axis (6 figure 1) coinciding with its length. The tube has an inlet end (10 figure 1) having attachment means (12 figure 2) configured to mate with attachment means at an outlet end of a sealant cartridge. The nozzle has an outlet (52 figure 1) located at the tube outlet end (20 figure 1), the nozzle outlet having a tube of defined length 58, the tube of defined length having the cross sectional shape of the outlet 52. The tube of defined length has a cross-section which increases in cross-sectional area going away from the elongate tube (4) inlet end (10). The nozzle provides an optimised profile for extruded sealant, mastic or adhesive particularly when intended for use in sealing a perpendicular joint formed where sheets of material meet.

Description

Nozzle for sealant cartridge The present invention provides an improved nozzle for a sealant cartridge, in particular a nozzle suited to the provision of a regular concave bead of sealant at a perpendicular meeting of two planar surfaces.

It is well-known that in the construction of buildings in particular there are many instances where a joint between two surfaces meeting at 90° to one another needs to be sealed. Typical examples include the wall of a shower and a shower tray, a wall and a sink attached to that wall. The purpose of sealing is typically to stop water entering a joint between two surfaces. To this end a wide variety of sealants are provided commercially and these are usually provided packaged in a sealant cartridge. A sealant cartridge is typically an elongate cylinder of around 300m1 volume having a slidable piston in one end, for actuation by a sealant gun and having at the other end an outlet, typically in the form of a cylindrical extension of smaller diameter having an external thread. Such sealant cartridges are often supplied with a nozzle. The nozzle is attached by a mating screw thread to that on the cartridge at the cylindrical extension. These nozzles are well-known and typically comprise said thread on a first inlet end of a cylindrical portion, followed at the other end by a tapering frusto conical portion to provide a smaller outlet than the inlet. The frusto conical portion typically ends in an outlet of generally circular or elliptical cross section, for example as formed by cutting of the frusto conical portion at an angle.

The above requirement for sealing perpendicular surfaces with a sealant using an attachable nozzle is well-known and a number of disadvantages and limitations are present. The principal limitations are that a profile of sealant which is dispensed gives rise to areas liable to retain water and, over time, to accumulate debris. These areas typically give rise to the growth of mould. Such moulds are typically of the Cladosporium sp. group, such as C. sphaerospermum. Whilst these moulds give rise to aesthetically undesirable effects they can also be associated with health problems. There is therefore a perceived need for the better application of sealant by means of a nozzle attached to a sealant cartridge.

The above problem is long established and a number of solutions have been proposed. A first route is to use a tool of some description to work the sealant which has been extruded onto a joint to be sealed. These gadgets tend to be gimmicks and few, if any, have had continued life in the marketplace, which is indicative of their lack of usefulness. A second route is to provide a nozzle of defined shape so as to form the sealant into a preferred shape on extrusion. There are many examples of this approach. W02006/134161 provides a conventional nozzle with a pre-shaped cutaway, as opposed to the typical diagonal cut provided in situ by a utility knife. This type of applicator gives rise to a pyramidal bead. For application between perpendicular surfaces this is not particularly desirable as it gives rise to high points which can be difficult to clean on either side and being proud of the surfaces to which it is attached, the sealant can be dislodged during cleaning. Another example is found in EP 0784018. This provides a hemispherical nozzle outlet and a flexible applicator blade. This gives rise to a predominantly flat bead of sealant when applied at a perpendicular joint, but does not readily seal the inner portion of the joint without the applicator blade being actively used to press down the material. This gives rise to surplus material push out on either side of the applicator blade. That surplus material is difficult to remove and is typically present as parallel secondary beads on either side of the main bead, frequently in the form of blobs etc. with high surface area. A further disclosure is found in WO 97/41968. This provides an elliptical end face for the nozzle in which a small central aperture is placed from which sealant is extruded. Part of the face acts as a flexible applicator blade. This arrangement makes it difficult to extrude any significant volume of sealant under moderate pressure and is slow to operate. As with the previous reference the applicator blade gives variable performance depending upon the pressure and angle of application and as mentioned, tends to give rise to lateral secondary beads of sealant if it is used to avoid a raised sealant profile. A yet further disclosure is found in WO 2010/093490 in which the problem of the flexible applicator blade is overcome by having a ball and socket type joint to provide continuity between the nozzle and an applicator shoe, one form of which is suitable for use between perpendicular surfaces. This arrangement is unduly complex for a simple device and is not possible to be readily manufactured in large quantity using minimal material to make it cost effective for what is essentially a disposable item. A yet further disclosure can be found in WO 2004/024342. This provides a nozzle in which the normally frusto conical portion is replaced by a portion having either a hemispherical, a crescent or a triangular profile. A first disadvantage with this design is that the surface area of the nozzle is high per cross-sectional unit volume as the surface area to volume ratio of the internal pipe of the nozzle is higher than if a circular cross-section is used, this gives rise to high backpressure. A further effect of this is that, when the sealant exits the nozzle it tends to expand (as the high compression pressure is released) and it is difficult to perform application evenly, particularly with a manual applicator (due to the high manual force required) which itself provides uneven application pressure except in skilled, or at least strong, hands. The hemispherical design suffers from the same problems as mentioned previously. The triangular design overcomes the problem with the hemispherical design not reaching the sealant into the corner of a joint but otherwise provides the same flat surface as the hemispherical. The crescent shape provides a desirable surface profile but fails to reach into the corner of the joints, much as with the hemispherical profile.

As can be seen, much attention has been paid to the problem of sealing surfaces using a sealant extruded from a cartridge via an attachable nozzle, particularly surfaces meeting perpendicularly. Ultimately, the inadequacy of the above designs is primarily validated by their relative absence from the marketplace. There is therefore a need, addressed by the present invention to provide: an improved nozzle for use with sealant, particularly in a sealed cartridge, the nozzle serving to allow extrusion of a sealant into a perpendicular joint so that the sealant both seals the corner of the joint whilst providing a desirable profile; without defective edges; without significant back pressure on extrusion; and preferably with a concave profile.

S

The present invention provides: a nozzle for a sealant cartridge the nozzle comprising: an elongate tube of circular cross section having a principle axis coinciding with its length, the tube having; S an inlet end having attachment means configured to mate with attachment means at an outlet end of a sealant cartridge; an outlet end remote from the inlet end and having, an end face comprising an outlet, which outlet when viewed perpendicular to, or substantially perpendicular to, said principle axis has two sides equating to two sides of an equilateral triangle with a third straight side or a third concave side; the end face being perpendicular to or angled at an angle greater than 30°to said principle axis.

The novel geometry of this nozzle gives rise to the possibility of extruding sealant from a nozzle attached to a sealant cartridge in which the sealant reaches down to where perpendicular surfaces abut but also gives rise to a surface profile which is either flat or concave but without peripheral tracks of sealant or a ledge in which debris can accumulate.

The novel geometry of the nozzle gives rise to the possibility, when the concave 20 sided shape is used that a profile having a concave surface is provided which reduces further the chance of debris accumulating and water retention.

The nozzle may further comprise a rigid extension, or nose, of the end face being in the direction of the elongate axis extending away from the outlet.

This extension provides a smoothing effect for the surface of extruded sealant and enhances or creates a concave profile.

The nose is preferably not flexible as the applicator type blade noted from the prior art tends to give a wavy profile exacerbating changes in flow of this sealant exiting the nozzle (for example when applied manually). Such a wavy profile, as previously, increases the chances of water and debris retention.

The nose whether or not flexible may be present as a continuation of the frusto conical profile of hemispherical cross section having rounded edges.

This taper, a continued taper of the frusto conical profile, avoids the formation of peripheral tracks from the nose impinging upon the sealant. The rounded edges, rounded in the sense of curvature being from 20 to 50% of the curvature of the outlet radius, give a smoothing effect. These features may be optionally combined with nose inflexibility.

The nozzle's elongate tube of circular cross section is preferably frusto conical between a smaller end coinciding with the outlet and the larger end toward or coinciding with the inlet end. This feature is not present in the WO 2004/024342 as the whole nozzle has a cross-section representative of the outlet shape and gives rise to higher backpressure as mentioned previously.

This nozzle may comprise a cylindrical portion between the inlet and the beginning of the frusto conical portion. Whilst this arrangement is conventional for a nozzle it nevertheless provides what may be termed 'reach' for the nozzle to reach less accessible places without unnecessarily increasing backpressure. This feature is not present in the WO 2004/024342 as the whole nozzle is tapered.

The above description provides a number of features for the nozzle, features which are not incompatible and as such the features may be used in combination, such as in the specific example described below.

The nozzle of the present invention may additionally comprise a number of conventional features, namely, a lip around the inlet end of the nozzle; features to enhance grip around the inlet end of the nozzle, such as vanes parallel to the principal or longitudinal axis of the nozzle.

The nozzle of the present invention is preferably injection moulded from a flexible thermoplastic. Suitable materials include polyethylene and polypropylene but also polyvinylchloride. A degree of flexibility in the walls of the nozzle, provided by having walls of thickness between 0.25 and 1 mm thickness, preferably around 0.5 mm thickness, for a nozzle of conventional dimensions (12cm to 20 cm long, 0.75cm to 1.5 cm maximum diameter) enhances the delivery from a functional manual hand gun used with a sealant cartridge using the nozzle of the present invention. This occurs by giving a degree of flexibility and buffering of the fluctuating pushing forces created by manual operation. Relevant prior art devices with non-circular outlets are understood to use generally thicker walls of more rigid material, which was initially thought beneficial as this best maintains the specific geometry (a circular geometry being self-maintaining due to internal pressure) of non-circular features. However, this has not necessarily been found beneficial and provided the final outlet aperture is rigid enough to maintain the outlet shape in use it has been found preferable to have a circular profile as a precursor to that final outlet. This is preferably provided in the present invention particularly as the external profile remains circular throughout the whole length of the tube whilst the aperture is of the desired geometry, the intervening space between the internal and external surfaces at the aperture being s solid.

Brief Description of the Drawings

In order that the invention may be more readily understood, a description is now given, by way of example only, reference being made to various embodiments of the present invention, in which:-FIGURE 1 is a front plan view of a sealant nozzle embodying the present invention; FIGURE 2 is cross-sectional view of the nozzle of Figure 1 along the line 6-6; FIGURE 3 is an enlarged view of the upper part of the nozzle as seen in Figure 2; FIGURE 4 is a view from above of the nozzle of Figure 1; FIGURE 5 is a perspective view from above and to the left relative to the position in Figure 1 of the nozzle embodying the present invention; FIGURE 6 is a cross-sectional view of the sealant profile as applied by the nozzle of Figure 1 to a tile-bath interface; FIGURE 7 shows the operation of a sealant gun fitted with the nozzle of Figure 1 applying sealant to a tile-bath interface; and FIGURE 8a is a cross-sectional view of the sealant profile as applied by a conventional nozzle to a tile-bath interface; FIGURE 8b is a cross-sectional view of the sealant configuration of Figure 8A after a smoothing operation, such as using a finger or equivalent; FIGURE 8c is a cross-sectional view of the sealant configuration of Figure 8A after a smoothing operation using an, particularly non-tapering, applicator blade or equivalent manual tool; FIGURE 8d is a cross-sectional view of the sealant profile as applied by a nozzle of the present invention having a triangular outlet and nose feature; FIGURE 8e is a cross-sectional view of the sealant profile as applied by a nozzle of the present invention with a triangular outlet; and FIGURE 8f is a cross-sectional view of the sealant profile as applied by a nozzle of the present invention having the third concave side.

Features of the device of the present invention, as shown in figures, include: 2: Nozzle 4: Elongate Tube 6: Principle Axis of Nozzle 10: Inlet End 12: Internal Screw Thread, Attachment Means 14: Collar 16: Elongate Vanes 18: Passageway formed by tube of defined length 58 20: Outlet End 30: Cylindrical Pipe Portion 40: Frusto Conical Portion 50: End Face 52: Outlet 54, 54': Sides of Outlet / Tube of Defined Length 56: Third side of Outlet 52, linear or convex 58: Tube of Defined Length Forming Outlet 52 60: Nose 62: End or Tip of Nose 64: Shoulder 82: Base or leading edge of Outlet 52 84, 86, 88: Rounded corners of Outlet 52 100: Sealant Cartridge 120: Manual Pump Action Sealant Gun 180: Bead of Sealant 182: First Surface of Perpendicular Joint to Be Sealed 184: Second Surface of Perpendicular Joint to Be Sealed 186: Wall or Substrate 188: Undercut Filled by Sealant Extruded from Nozzle of the Invention.

Detailed Description of the Drawings

Referring now to figures 1 to 5. The nozzle 2 of the present invention comprises an elongate tube 4 having a circular cross-section and a principal axis 6-6 (which on figure 1 also serves as an indication of the point at which the cross-section is made) and having an inlet end 10 and an outlet end 20. The inlet end 10 has a screw thread attachment 12 for attaching to a sealant cartridge 100. Between the inlet end 10 and the outlet end 20 is a collar 14 for accommodating the screw thread 12, further along the elongate tube 4 are vanes 16 for assisting the grip of a user.

The elongate tube 4 comprises two principal portions a hollow cylindrical pipe portion 30 which is connected to a frusto conical portion 40 towards the outlet end 20. The frusto conical portion 40 terminates at the outlet end 20 which comprises end face 50 having an outlet of generally triangular cross-section when viewed perpendicular to the principal axis 6. The end face is angled to said principal axis at an angle of 50°. The outlet 52 comprises a tube of defined length 58 that tube diverging in a direction away from the frusto conical portion 40 at an angle of 1°. Protruding from the end face 50 is nose 60, which terminates in a rounded end 62. In the illustrative embodiments the frusto conical portion 40 is a greater diameter at its junction with the tube of defined length 58, thus creating a shoulder 64, shown as step 64 in cross-section. This step 64 maximises the diameter of the frusto conical portion so as to reduce backpressure from sealant being extruded whilst enabling the required profile to be obtained from outlet 52 on end face 50 which is then potentially shaped by nose 60 particularly if end 62 is directed downward towards an extruded bead.

In one embodiment, the triangular cross-section of passageway, being the tube of defined length 58, has increasing dimensions with increased distance from inlet end 10, until that passageway 58 opens out to end face 50 which at its base is inclined at an angle of 40 degrees from principal axis 6-6. End face 50 has a complex surface profile in three dimensions as follows: as end face 50 extends upwardly away from base 82, the angle of inclination increases to about 45 to 50 degrees, and then the angle of inclination decreases substantially (to about 10 to 20 degrees) just before reaching nose 62 with upper corners 84 and 86 of a nose portion of end face 50 at the outlet of triangular passageway 58, thereafter continuing upward until reaching nose 62.

In use the nozzle 2 is attached to a sealant cartridge 100 by means of screw thread 12 and as illustrated in figure 7, when used in a manual sealant gun is used to direct sealant to a perpendicular joint between surfaces, a tile surface and an edge of a bath are illustrated. Figure 6 shows a profile of sealant obtainable from the embodiment described when the nose is directed toward the junction of the perpendicular surfaces.

Figures will now be considered which illustrate the profiles of sealant obtainable lo using different apparatus and methods.

Figure 8A shows the profile of sealant when applied to a tile/bath interface using a conventional nozzle, typically with an aperture produced by cutting the conical outlet at an angle to the base of that cone. As is evident from Figure 8A, the resultant profile of sealant 200 inevitably uses a large amount of sealant material and results in areas 202 and 204 in which debris can accumulate and water be retained.

Such profiles of sealant are therefore typically smoothed using a tool or, simply a finger of a person, to provide a profile as shown in figure 8B.

Clearly, the resultant profile 210 then extensions 212, 214 which are relatively weak and on subsequent use can become detached and result in ingress of moisture, retention of debris and deterioration of the bond. A diligent user of this technique will either apply tape in regions 212, 214, tape which is subsequently removed, so as to avoid the thin tapering extensions 212, 214. However, this is obviously an extra step, as is the shaping with the tool, and in any case usually results in a step at the edge of the profile when the tape is removed. This step, while small, once again, results in the accumulation of debris and the retention of moisture usually resulting in mould growth over time. An alternative approach is to use a tool to avoid such a step. This can result in the profile shown in figure 8C. This is also the profile which results where a nozzle, such as that described in the description of the prior art above, comprises an applicator blade, in particular an applicator blade of dimensions s broader than the nozzle outlet. As can be seen from the illustration this profile has a central portion which is of concave profile, does not retain water or debris and has edges which are also steeply inclined to the surfaces they meet and so also do not tend to retain water or debris. However, there is a strong tendency in this situation for the previously mentioned peripheral beads 222, 224 to form which removes the benefits of the efficient central profile 220.

The present invention gives rise to the profiles shown in figures 8d, 8e and 8f. Figure 8d shows a profile 240 having clean edges 242, 244 and an indented profile a central portion 246 provided by the nose portion but not giving an overall concave surface. Use of a triangular nozzle outlet gives rise to the profile shown in figure 8e, is a profile which is not readily achievable by the equivalent nozzle outlets from prior art WO 2004/024342 since the invention provides low backpressure and the stress relief tube of defined length which is increasing in cross-section towards the outlet rather than decreasing. However profile shown in figure 8e only results in the absence of the action of nose 60. The profile 260 shown in figure 8f results when the third side of said outlet 52 is a concave side.

As can be seen none of profiles shown in figures 8d, 8e and 8f have regions where debris may readily accumulate and water may be retained, thus the profiles are advantageous and make optimal use of any given sealing composition used to seal a perpendicular joint.