GB2507508A

GB2507508A - Tear resistant moulded articles

Info

Publication number: GB2507508A
Application number: GB1219558.2A
Authority: GB
Inventors: James Bishop; Tony Rhoades
Original assignee: Seatriever International Holdings Ltd
Current assignee: Seatriever International Holdings Ltd
Priority date: 2012-10-30
Filing date: 2012-10-30
Publication date: 2014-05-07
Anticipated expiration: 2032-10-30
Also published as: MY182399A; GB201219558D0; EP2914355B1; EP2914355A1; CA2928876C; CN104797313B; ES2758926T3; WO2014068311A1; DK2914355T3; RU2687628C2; BR112015009767A2; PL2914355T3; JP2015532865A; AU2013340604A1; GB2507508B; BR112015009767B1; CN104797313A; RU2015120289A; US11000774B2; AU2013340604B2

Abstract

A tear resistant moulded article, such as a balloon 10, extends generally axially from an opening 14 at a first end. The article comprises an elastomeric film 11 having a first thickness and a plurality of intersecting ribs 12 of a second, greater thickness formed on the film. The ribs are adapted so as to be angled with respect to the axis 13 of the article and any axis perpendicular thereto. Such an article has increased tear resistance, and can be manufactured with conventional moulding techniques without compromising the integrity of the film. The ribs may comprise a plurality of helices. There is also disclosed a mould for making such an article and a method of using such a mould to make such an article.

Description

Tear Resistant Moulded Articles The present invention relates to tear resistant elastomeric moulded articles, In particular, the present invention relates to tear resistant elastomeric inflatable moulded articles such as balloons.

Many articles such as balloons, disposable gloves and prophylactic sheaths are manufactured from elastomeric film. Typically such articles are formed by dipping a generally axial mould into a liquid compound. The liquid compound clings to the mould and can then be cured and subsequently peeled away from the mould. This thereby provides an article having a desired shape. As the article is formed from elastomeric film it is capable of stretching in use to accommodate a user's body (in co the case of gloves/sheaths) or to enable inflation (in the case of balloons).

r As an artefact of the moulding process, the article extends generally axially r from an opening at a first end. The moulding process also limits the complexity of r shapes that can be formed. In particular, formations perpendicular to the axis of the mould tool can provide places where air bubbles form or contaminants gather affecting the integrity of the fIlm formed on the mould. Such bubbles or contaminants can weaken the film or reduce its elastic properties.

A problem common to such articles is the fact that if an elastomeric film is stretched under beyond a particular limit, for instance by becoming caught by a sharp edge, a tear can form which will propagate rapidly across the parts of the film under tension. On many occasions the tear will propagate sufficiently far and fast to substantially destroy the article. A particular example of the above effect occurs in an inflated balloon. In such cases, the tear typically propagates at a rate of the order of the speed of sound, resulting in the familiar bang' sound when a balloon is burst. As a result of the speed of propagation of the tear and subsequent recoil of the opposing edges the balloon can be propelled some distance upon bursting. The propelled balloon fragments following bursting are rarely considered a significant danger since they are typically very light and are not rigid. In recent years balloons have been devdoped incorporating internal illumination means such as those described in W02008/l 10832. If such balloons should burst, the illumination means can be propelled at a significant velocity and thus may pose an injury risk to nearby persons.

It is therefore an object of the present invention to provide an dastorneric moulded article which at least partially overcomes or alleviates the above problems.

According to a first aspect of the present invention there is provided a tear v" resistant moulded article extending generally axially from an opening at a first end, r the article comprising: a elastomeric film having a first thickness; and a plurality of r intersecting ribs of a second, greater thickness formed on the film, wherein the ribs r are adapted so as to be angled with respect to the axis of the article and any axis perpendicular thereto.

This thereby provides an elastomeric article with improved tear resistance. It further provides such an article that can be manufactured with conventional dip moulding techniques without compromising the integrity of the film.

The intersecting ribs may be elongate. Preferably, the ribs have a substantially constant profile along their length. Preferably each rib has substantially the same profile. Most preferably, the profile is curved. In such instances, the curved profile may comprise an arc of a circle or ellipse.

hi some embodiments different ribs may be adapted to have different thicknesses. Preferably in such embodiments, ribs have two different thicknesses.

Preferably. in such embodiments alternate ribs are of each different thickness.

At intersection points, the profile of each rib may remain substantially identical. Alternatively, at intersection points, the profile of each rib may vary. This variation may include smoothing of edges or vertices between nbs.

The ribs may be aligned at and/or intersect at any desired angle. Preferably, the ribs are aligned at angles to the artide axis of, say, between 50 and 700. By providing ribs at such angles. the likelihood of trapping air bubbles or other containments in the ribs is reduced. C1)

v" The ribs may comprise any particular pattern. Preferably, the ribs comprise a r plurality of helices. Most preferably, the ribs comprise equal numbers of oppositely r pitched helices.

r In a preferred embodiment, the helices each originate at a cap. The cap may be provided at the distal end of the article. The cap may comprise an area of thickness substantially equal to the rib thickness. In the event that the article has multiple distal ends, a cap may be provided at each distal end.

Preferably, the ribs are adapted such that each rib ends at an intersection with another rib. In the above embodiments, this may be achieved by having oppositely directed helices meet at their ends.

The article may comprise any desired moulded article. In particular, the article may comprise a glove, a sheath or a balloon. In a particularly preferred embodiment, the artide may comprise a balloon provided with an illumination device mounted inside the balloon. In such a balloon, the illumination device may comprise a light emitting diode (LED) and may be powered by at least one battery. The illumination device may have a projection whereby it is attached to the elastomeric film, inside the ba'loon, by a dip or 0-ring fitted onto the projection from outside the balloon. A strip of insulating material may be initially located between the battery or batteries and the LED, the strip being capable of being withdrawn, prior to or upon inflation of the balloon, to light up the LED and the balloon.

According to a second aspect of the present invention there is provided a mould for making a tear resistant moulded article from elastomeric material comprising: a body portion extending generally axially from a base and conforming to the shape of the article to be moulded; and a plurality of intersecting grooves provided on said body portion wherein the groves are adapted so as to be angled with respect to r the axis of the body and any axis perpendicular thereto. r

This thereby provides a mould for making an elastomeric article with improved tear resistance. It further enaNes such an article to be manufactured with conventional dip moulding techniques without compromising the integnty of the film.

The intersecting grooves may be elongate. Preferably, the grooves have a substantially constant profile along their length. Preferably each groove has substantially the same profile. Most preferably, the profile is curved. In such instances, the curved profile may comprise an arc of a circle or ellipse.

In some embodiments different grooves may be adapted to have different depths. Preferably in such embodiments, grooves have two different depths.

Preferably, in such embodiments alternate grooves are of each different depth.

At intersection points, the protile of each groove may remain substantially identical. Alternatively, at intersection points, the profile of each groove may vary.

This variation may include smoothing of edges or vertices between grooves.

The grooves may be aligned at andlor intersect at any desired angle.

Preferably. the grooves are aligned at angles to the article axis of, say, between 5° and 7Q0 By providing grooves at such angles, the likelihood of trapping air bubbles or other containments in the grooves is reduced.

The grooves may comprise any particuInr pattern. Preferably, the grooves comprise a plurality of helices. Most preferably. the grooves comprise equal numbers of oppositely pitched helices.

In a preferred embodiment, the helices each originate at a cap. The cap may r be provided at the distal end of the mould. The cap may comprise an area of depth r substantially equal to the groove depth. In the event that the mould has multiple distal r ends, a cap maybe provided at each distal end.

Preferably, the grooves are adapted such that each groove ends at an intersection with another groove. In the above embodiments, this may be achieved by having oppositely directed helices meet at their ends.

The mould may be adapted for the forming of any desired moulded article. In particular, the article may comprise a glove, a sheath or a balloon.

The mould may be formed from any suitable substance. In particular. the mould may be formed from metal, plastic or ceramic material as desired or required.

According to a third aspect of the present invention there is provided a method of making an artide according to the first aspect of the present invention using mould according to the second aspect of the present invention, the method comprising the steps of: providing a mould according to the second aspect of the second invention; introducing said mould into a suitable container of liquid elastomeric material in a direction substantially parallel to the axis of the body; removing the mould from the container of liquid elastomeric matena in a direction substantially parallel to the axis of the body; curing the elastomeric material; and removing the cured dastomeric matenal from the mould.

The method of the third aspect of the present invention may incorporate any or all of the features of the first and second aspects of the present invention as desired or as appropriate.

Curing may be achieved by exposure to radiation, heat or the atmosphere. The v" elastomeric material may comprise latex.

r In order that the present invention is more clearly understood, a specific r embodiment will now be described, with reference to the accompanying drawings, in r which: Figure 1 is a schematic illustration of a balloon according to the present invention; and Figure 2 is a schematic illustration of a mould for making a ba'loon according to the present invention.

Turning now to figure 1, a tear resistant balloon 10 is shown. The balloon 10 is formed from an elastomeric film of a first thickness and a plurality of intersecting ribs 12 of a second, greater thickness formed on the film 11 and formed of the same material. Typically, the balloon is formed from a suitable elastomeric material such as latex.

The balloon 10 extends generally axially about axis 13 from an opening 14 to an end cap or root 15 which is also of the greater thickness. The ribs 12 are angled with respect to the axis 13 and any axis perpendicular thereto. Typically, the angle between the ribs 12 and the axis 13 falls in the range 5°-70°. Angling the ribs 12 in such a manner allows the balloon i0 to be manufactured with conventional dip moulding techniques without compromising the integrity of the balloon 10 generally or the ribs 12 particularly.

The ribs 12 are elongate with a substantially constant profile along their C1) length. As is shown in the expanded cross-section of figure Ia, the profile has a curved form. In the example shown, the ribs 12 comprise equal numbers of r oppositely pitched helices originating at cap 15. Each rib 12 ends at the meeting point r I 2a with another rib 12 adjacent to the opening 14.

In use, air can be introduced to the balloon 10 through the opening 14 to inflate the balloon. As a result of the introduced air, the air pressure inside the balloon 10 increases and the elastomeric ifim 11 expands in response to the increased pressure. When sufficient air has been introduced, the opening 14 can be sealed, typically by tying a knot.

If the inflated balloon 10 is subject to a piercing impact (or indeed, if the pressure within the inflated balloon 10 exceeds a particular level) a tear can form in the thinner film II. In a conventional balloon, this tear would rapidly propagate across the film, with a maximum speed of a few hundred meters/second. In the present balloon 10, any tear propagates freely only as far as the nearest nb 12.

Having hit the rib 12, as the rib 12 is thicker (and hence stronger) than the film 11, the tear is diverted and propagates alongside the rib 12 at much reduced speed. When the tear reaches an intersection between two ribs 12, the intersection concentrates the stress related to the expanding tear. As such, the crack is able to propagate across the intersection. 1-lowever, since the intersection is much thicker than the bulk film 11.

this propagation is much slower than the earlier propagation of the tear and absorbs a much larger proportion of the energy powering the propagation than would be the case for a tear travelling an equivalent distance across the film II.

After propagating across an intersection, the tear will continue to propagate across the film 11 until it reaches another intersection. As a result of the slowing by co the first intersection, the tear will propagate across this film with a reduced speed.

r Upon reaching another intersection, the propagation speed of the tear will once again r be reduced as the tear crosses the intersection. In testing, it has been found that an r initial tear propagation speed of -360m/s can be reduced to the range 50-lOOm/s by the ribs 12 in a balloon 10 according to the present invention.

As such, whilst a balloon 10 according to the present invention will still be destroyed by a penetrating impact when inflated, the propagation speed of the tear is significantly reduced. This has the consequence of reducing the recoil speed of the balloon 10 (or balloon fragments) after propagation of the crack is completed. As such, the likelihood of injuly or damage being caused by the balloon 10 (or balloon fragments) is reduced.

In view of the above, the balloon 10 of the present invention is particularly well suited to being provided with an illumination device mounted therein (not shown). The illumination device may compnse a light emitting diode (LED) powered by at least one battery. The illumination device typically has a projection whereby it is attached to the elastomeric film 11 (or end cap 15), inside the balloon 10, by a clip or 0-ring fitted onto the projection from outside the balloon 10. In a preferred version of such a balloon, a strip of insulating material is initially located between the battery or batteries and the LED, the strip being capable of being withdrawn, prior to or upon inflation of the balloon, to light up the LED and the balloon. Typically, the strip extends through the opening 14 to an outer end region of enlarged width. The strip may also have a second region of enlarged width at a spacing from the enlarged outer end region, the width of said second region being chosen so that it tends to remain inside the opening 14 of the balloon 10, with the rim of the balloon membrane lodged co between the respective enlarged width regions, unless a significant force is used to r pull the strip outwardly of the balloon 10. r

Turning now to figure 2, a mould 20 for making a balloon 10 is shown. The r mould comprises a bulb 21 with a substantially smooth curved bulk surface and a plurality of grooves 22. The bulb 21 extends axially about and axis 23 from a shaft 24 to an end 25.

The grooves 22 are angled with respect to the axis 23 and any axis perpendicular thereto. Typically, the angle between the grooves 22 and the axis 23 falls in the range 5°-70°.

The grooves 22 are elongate with a substantially constant profile along their length. As is shown in the expanded cross-section of figure 2a, the profile has a curved form. In particular, the grooves 12 may be defined by a depth d and radius r, as shown in figure 2a. In a typical example, the depth d may be in the range 0-3mm and the radius r may be in the range 0.5-2.5 mm.

hi the example shown, the grooves 22 comprise equal numbers of oppositely pitched helices originating at end 25. Each groove 22 ends at the meeting point 22a with another groove 22 adjacent to the shaft 24. For a typical balloon mou'd of length in the range 50-100 mm and maximum diameter in the range 50-100 mm.

There may be between 2 and 24 helical grooves 12. In a typical example the separation L of successive grooves 12 may be in the region of 5-20 mm.

In order to use the mould 20 to manufacture a balloon 10, the mould is introduced into a suitable container of liquid elastorneric material in a direction substantially parallel to the axis 23. Subsequently, the mould 20 is removed from the container of liquid elastomeric material in a direction substantially parallel to the axis co 23. This results in a film of liquid elastomeric material clinging to the surface of the r mould 20 in particular the bulk surface of the bulb 21 and filling the grooves 22. The r elastomeric material is subsequently cured and thereby forms a solid film 11 over the r buTh surface of the bulb 21 with a plurality of ribs 12 corresponding to the grooves 22.

The cured elastomeric material can then be removed from the mould 20 to provide a balloon 10 according to the present invention. As a consequence of the angling of the grooves 22, air bubNes or contaminants do not become trapped in the grooves 22 when the mould is introduced to the liquid elastomeric material. As such, the ribs 12 of the balloon 10 can be formed without voids or discontinuities, improving their structural integrity.

Whilst the above examples describe a balloon and a balloon mould, the skilled man will appreciate that other axially moulded articles can be manufactured incorporating intersecting ribs by use of a suitable mould. The provision of the intersecting ribs would ensure that such articles would also provide the improved tear resistance of the balloons of the present invention. k particular, such articles may include gloves or sheaths. In the event that such articles are not subject to similar tension to an inflated balloon, the ribs may suffice to stop. rather than merdy slow, propagation of a crack.

It is of course to be understood that the invention is not to be restricted to the details of the above embodiment, which is described by way of example only. C') r r aD r

Claims

Claims 1. A tear resistant moulded article extending generally axially from an opening at a first end, the article comprising: a elastomeric film having a first thickness; and a plurality of intersecting nbs of a second, greater thickness formed on the film, wherein the ribs are adapted so as to be angled with respect to the axis of the article and any axis perpendicular thereto.
2. A tear resistant moulded article as claimed in claim I wherein the intersecting ribs are elongate.
3. A tear resistant moulded article as claimed in claim 1 or claim 2 wherein the ribs have a substantially constant profile along their length. C1)
4. A tear resistant moulded article as claimed in claim 3 wherein each rib has r substantially the same profile. r
5. A tear resistant moulded article as claimed in claim 3 or claim 4 wherein the r profile is curved.
6. A tear resistant moulded article as claimed in any preceding claim wherein different ribs are adapted to have different thicknesses.
7. A tear resistant moulded article as claimed in claim 6 wherein ribs have two different thicknesses and wherein alternate ribs are of each different thickness.
8. A tear resistant moulded article as claimed in any preceding claim wherein at intersection points, the profile of each rib remains substantially identical.
9. A tear resistant moulded article as claimed in any one of claims 1 to 7 wherein the profile of each rib includes smoothing of edges or vertices between ribs.
10. A tear resistant moulded article as claimed in any preceding claim wherein the ribs are aligned at aligned at angles to the article axis of between 5° and 70°.
11. A tear resistant moulded article as claimed in any preceding claim wherein the ribs comprise a plurality of helices.
12. A tear resistant moulded artide as claimed in claim 11 wherein the ribs comprise equal numbers of oppositely pitched helices.
13. A tear resistant moulded article as claimed in claim 11 or claim 12 wherein the helices each onginate at a cap provided at the distal end of the article.
14. A tear resistant moulded article as claimed in claim 13 wherein in the event that the article has multiple distal ends, a cap is provided at each distal end.
15. A tear resistant moulded article as claimed in any one of claims 12 to 14 wherein the ribs are adapted such that each rib ends at an intersection with another rib. cov"
16. A tear resistant moulded article as claimed in any preceding claim wherein the r article comprises a glove or a sheath. r17. A tear resistant moulded article as claimed in any one of claims I to 15 r wherein the article comprises a balloon.18. A tear resistant moulded article as claimed in claim 17 wherein the balloon is provided with an illumination device mounted inside the balloon.19. A mould for making a tear resistant moulded article from elastorneric material comprising: a body portion extending generally axially from a base and conforming to the shape of the article to be moulded; and a plurality of intersecting grooves provided on said body portion wherein the groves are adapted so as to be angled with respect to the axis of the body and any axis perpendicular thereto.20. A mould as claimed in claim 19 wherein the intersecting grooves are elongate.21. A mould as claimed in claim 19 or claim 20 wherein the grooves have a substantially constant profile along their length.22. A mould as claimed in claim 21 wherein each groove has substantially the same profile.23. A mould as daimed in claim 21 or claim 22 wherein the profile is curved.24. A mould as claimed in any one of claims 19 to 23 wherein different grooves are adapted to have different depths.25. A mould as claimed in claim 24 wherein grooves have two different depths and alternate grooves are of each different depth.26. A mould as daimed in any one of claims 19 to 25 wherein at intersection points, the profile of each groove remains substantially identical.27. A mould as claimed in any one of claims 19 to 25 wherein at intersection co points, the profile of each groove includes smoothing of edges or vertices between r grooves. r28. A mould as claimed in any one of claims 19 to 27 wherein the grooves are r aligned at ang'es to the article axis of between 5° and 70°.29. A mould as claimed in any one of claims 19 to 28 wherein the grooves comprise a plurality of helices.30. A mould as claimed in claim 29 wherein the grooves comprise equal numbers of oppositely pitched helices.31. A mould as claimed in claim 29 or claim 30 wherein the helices each originate at a cap provided at the distal end of the mould.32. A mould as claimed in claim 31 wherein in the event that the mould has multiple distal ends, a cap is provided at each distal end.33. A mould as claimed in any one of claims 29 to 32 wherein the grooves are adapted such that each groove ends at an intersection with another groove.34. A mould as claimed in any one of claims 19 to 33 wherein the mould is adapted to fonTi a glove or a sheath.35. A mould as claimed in any one of claims 19 to 33 wherein the mou'd is adapted to form a balloon.36. A method of making an artide according to any one of claims I to 18 using mould according to any one of claims 19 to 35, the method comprising the steps of: providing a mould according to any one of claims 19 to 35; introducing said mould into a suitable container of Uquid elastomeric material in a direction substantially parallel to the axis of the body; removing the mould from the container of liquid elastomeric material in a direction substantially parallel to the axis of the body; curing the elastomeric material; and removing the cured elastomeric material from the mould. r37. A method as claimed in claim 36 wherein curing is achieved by exposure to r radiation, heat or the atmosphere.38. A method as claimed in claim 36 or claim 37 wherein the elastomeric material comprises latex.39. A method as claimed in any one of daims 36 to 38 wherein the article is a balloon and the method contains the further step of mounting an illumination device inside the balloon.40. A method as claimed in claim 39 wherein the mounting step involves attaching a projection of the illumination device to the elastomeric film, inside the balloon, by a clip or O-nng fitted onto the projection from outside the balloon.