A balloon

Abstract

A balloon comprising one or more balloon sheets connected together to form a body of the balloon. The or each balloon sheet comprises at least one foundation sheet. Each foundation sheet comprises a common base compound and is provided with a lower density surface and a higher density surface.

Description

[0001] A BALLOON

[0002] Technical Field of the Invention

[0003] The present invention relates to a balloon. In particular, but not exclusively, the present invention relates to a foil style balloon.

[0004]

[0005] to the Invention

[0006] Balloons formed of plastic instead of latex and, in particular, foil style balloons which are typically formed of two sheets bonded together, comprise a non-porous body. As such, they are useful in situations where it is desired that the balloon remains inflated for an extended period.

[0007] Such balloons are made of sheets which form the body of the balloon, each sheet being a layer of nylon and a layer of polyethylene bonded together (or alternatively a layer of biaxially-oriented polyethylene terephthalate and a layer of polyethylene bonded together). The nylon layer (or biaxially-oriented polyethylene terephthalate layer) forms the outer layer of the balloon sheet, being hard enough to provide structural integrity to the balloon and to hold helium within the balloon for longer. The outer layer may or may not be metalised. Metalising the outer layer means the helium will be held within the balloon for even longer. The polyethylene forms the relatively soft inner layer of the balloon sheet, that it is suitable for being easily heat sealed to the inner layer of the other sheet to form the body of the balloon.

[0008] Such balloons have the disadvantage of being difficult to recycle given the multiple types of plastic within the balloon which are hard to separate and therefore not accepted by domestic or standard retail recycling facilities. As such they fill landfill sites, which is not a sustainable solution, or even end up littering the environment. Such plastic products are a particular threat to marine life if they end up in oceans.

[0009] Embodiments of the present invention seek to overcome these or other disadvantages and provide an improved balloon.

[0010] Summary of the Invention

[0011] According to a first aspect of the present invention there is provided a balloon comprising one or more balloon sheets connected together to form a body of theballoon, wherein the or each balloon sheet comprises at least one foundation sheet, each foundation sheet comprising a common base compound and provided with a lower density surface and a higher density surface.

[0012] A balloon according to the first aspect of the present invention is particularly advantageous as the lower density surface may be used for heat sealing foundation sheets together to form the balloon body. The higher density surface may then provide additional structural integrity to the balloon body and assist in the retention of helium within the balloon. Such a balloon may be formed from a single base compound so may be easily recycled.

[0013] The density profile of the or each foundation sheet may vary from the lower density surface to the higher density surface. The density profile of the or each foundation sheet may vary continuously from the lower density surface to the higher density surface. The density profile of the or each foundation sheet may vary discontinuously from the lower density surface to the higher density surface.

[0014] The common base compound may be polyethylene (PE). The common base compound may be machine directionally oriented polyethylene (MDOPE). This may assist in providing a foundation sheet having greater strength and pressure resistance. Alternatively, the common base compound may be polypropylene, polyvinyl alcohol, polylactic acid, or biaxially-oriented polyethylene terephthalate.

[0015] The or each foundation sheet may be formed by a blown film extrusion process utilising a mixture of different density components. The or each foundation sheet may comprise a mixture of different density components comprising the common base compound. In some embodiments the foundation sheet may comprise a mixture of two different density components. In such cases, the foundation sheet may comprise a mixture of a lower density component and a higher density component. In further embodiments, the foundation sheet may comprise a mixture of three or more different density components. In such cases, the foundation sheet may comprise a mixture of one or more lower density components and one or more higher density components; or may comprise a mixture of one or more lower density components, one or more intermediate density components and one or more higher density components. Provision of a foundation sheet comprising a mixture of different density components may assist inproviding a gradual change in the density profile of each foundation sheet, minimising the presence of sudden changes in the density profile and subsequent material properties of the foundation sheet.

[0016] In one example, the common base compound may comprise polyethylene. In such cases, the lower density components may comprise: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE) or the like. In such cases, the intermediate density components may comprise: high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low-density polyethylene, or metallocene linear low density polyethylene or the like. In such cases, the higher density components may comprise: bimodal polyethylene, high-density polyethylene (HDPE), ethylene-vinyl acetate (EVA), low-density polyethylene or the like.

[0017] The one or more lower density components may comprise a mixture of LLDPE and LDPE. The mixture of lower density components may comprise at least 45 wt.% of LLDPE, at least 50 wt.% of LLDPE, or at least 55 wt.% of LLDPE. The mixture of lower density components may comprise between 45-55 wt. % of LLDPE. The mixture of lower density components may comprise at least 45 wt.% of LDPE, at least 50 wt.% of LDPE, or at least 55 wt.% of LDPE. The mixture of lower density components may comprise between 45-55 wt. % of LDPE.

[0018] The one or more intermediate density components may comprise HDPE. The one or more intermediate density components may comprise at least 90 wt.% of HDPE, at least 95 wt.% of HDPE, or at least 99 wt.% of HDPE. The one or more intermediate density components may comprise between 90-99 wt. % of HDPE. Alternatively, the one or more intermediate density components may comprise a mixture of LLDPE and MLLDPE. The mixture of intermediate density components may comprise at least 40 wt.% of LLDPE, at least 50 wt.% of LLDPE, or at least 60 wt.% of LLDPE. The mixture of intermediate density components may comprise between 40-60 wt. % of LLDPE. The mixture of intermediate density components may comprise at least 30 wt.% of MLLDPE, at least 37.5 wt.% of MLLDPE, or at least 45 wt.% of LLDPE. The mixture of intermediate density components may comprise between 30-45 wt. % of MLLDPE.The one or more higher density components may comprise a mixture of bimodal polyethylene, HDPE, EVA, and LDPE. The mixture of one or more higher density components may comprise at least 20 wt.% of bimodal polyethylene, at least 24 wt.% of bimodal polyethylene, or at least 28 wt.% of bimodal polyethylene. The mixture of one or more higher density components may comprise between 20-28 wt. % of bimodal polyethylene. The mixture of one or more higher density components may comprise at least 6 wt.% of HDPE, at least 8 wt.% of HDPE, or at least 10 wt.% of HDPE. The mixture of one or more higher density components may comprise between 6-10 wt. % of HDPE. The mixture of one or more higher density components may comprise at least 25 wt.% of EVA, at least 30 wt.% of EVA, or at least 35 wt.% of EVA. The mixture of one or more higher density components may comprise between 25-35 wt. % of EVA. The mixture of one or more higher density components may comprise at least 10 wt.% of LDPE, at least 11 wt.% of LDPE, or at least 12 wt.% of LDPE. The mixture of one or more higher density components may comprise between 10-12 wt. % of LDPE.

[0019] The mixture of different density components may comprise at least one additive. Examples of applicable additives may include, but are not limited to: scolecite, SiCE monox, poly oxethylene 10 lauryl ether, PP nano particle, flexibilizer (POE-g-MAH), polyisobutylene, calcium carbonate, poly(styrene-butadiene-styrene) (SBS) or the like.

[0020] The or each foundation sheet may have a thickness between 0.016 mm-0.2 mm. The or each foundation sheet may have a thickness between 0.016 mm- 0.15 mm. The or each foundation sheet may have a thickness between 0.022 mm- 0.028 mm. The or each foundation sheet may have a thickness of 0.025 mm.

[0021] The difference in density between the lower density surface and the higher density surface may be selected such that the lower density surface may be at least partially melted for heat sealing without adversely impacting the structural integrity of the higher density surface. The lower density surface may be suitable for heat sealing foundation sheets together. The higher density surface may not be suitable for heat sealing foundation sheets together. A foundation sheet having a lower density surface with a lower melting point and a higher density surface with a higher melting point is advantageous as it enables the single foundation sheet to be capable of both heat sealing and providing structural integrity to the balloon. Therefore, the manufacturing processof such a balloon may be simplified as it is not necessary to bond two layers of different materials to create a single sheet whereby each layer is suited to either heat sealing or providing structural integrity.

[0022] The lower density surface may form an internal surface of the body of the balloon. The higher density surface may form an external surface of the body of the balloon.

[0023] The or each foundation sheet may be translucent. The or each foundation sheet may be transparent. The or each foundation sheet may be coloured.

[0024] One or more foundation sheets may be connected together to form the body of the balloon. The lower density surface of the one or more foundation sheets may be connected together to form the body of the balloon. The one or more foundation sheets may be connected together at or adjacent to their edges to form the body of the balloon. The one or more foundation sheets may be connected together continuously at or adjacent to their edges to form the body of the balloon. There may be a gap in the continuous connection. The one or more foundation sheets may be sealed together. The one or more foundation sheets may be heat sealed together. By heat sealing the foundation sheets a further material to form the seal (e.g. adhesive) is not required, making it easier to recycle the balloon.

[0025] The balloon may be provided with a layer of pigmented material. The layer of pigmented material may be provided on the higher density surface of the one or more foundation sheets. The layer of pigmented material may form one or more images. The layer of pigmented material may comprise at least one of a white wash, a black blocking, or one or more layers of coloured ink. Provision of the layer of pigmented material on the higher density surface is particularly advantageous as it minimises the interference of the layer of pigmented material on connecting the or each foundation sheet to form the body of the balloon.

[0026] Alternatively, two or more foundation sheets may be bonded together to form a balloon sheet. The two or more foundation sheets may be laminated together to form the balloon sheet. The two or more foundation sheets may be heat laminated together to form the balloon sheet. The two or more foundation sheets may be bonded by anadhesive to form the balloon sheet. Each of the foundation sheets may have the same density profile. Alternatively, each of the foundation sheets may have a different density profile.

[0027] The layer of pigmented material may be provided between each of the two or more foundation sheets. In such instances, the layer of pigmented material may be laminated between each of the two or more foundation sheets. Alternatively, the layer of pigmented material may be integrally formed with or between the or each foundation sheet. The layer of pigmented material may form one or more images. The layer of pigmented material may comprise a single colour or multiple colours. A single colour layer of pigmented material may be substantially white, grey, black or any other suitable colour. A multiple colour layer of pigmented material may have two, three or more colours. A multiple colour layer of pigmented material may comprise a pattern, image or the like. The layer of pigmented material may comprise ink. Providing a layer of pigmented material between the foundation sheets is particularly advantageous as the layer of pigmented material is less likely to be damaged or removed by abrasion during use.

[0028] The balloon may be provided with a gas blocking layer. The gas blocking layer may be provided between each of the two or more foundation sheets. In such instances, the gas blocking layer may be laminated between each of the two or more foundation sheets. Alternatively, the gas blocking layer may be integrally formed with or between the or each foundation sheet. Where the blocking layer is integrally formed, there may be a gradual change in the density profile of each foundation sheet including the blocking layer as a result of the manufacturing process. The layer of pigmented material may be provided adjacent to the gas blocking layer. The layer of pigmented material may be provided on either side of the gas blocking layer. The gas blocking layer may assist in the retention of gas within the balloon during use, helping the balloon remain inflated for an extended period of time, for example, up to seven days. This is particularly advantageous in relation to balloons comprising an illumination device which may be heavier than a standard balloon. As such, when the ballon begins to deflate, the illumination device may cause the buoyancy of the balloon to decrease at agreater rate than a standard balloon, thereby causing the balloon to sink at a greater rate than a standard balloon.

[0029] The gas blocking layer may be formed from a material having a low gas permeability. The gas blocking layer may be formed from ethylene vinyl alcohol (EVOH). Alternatively, the gas blocking layer may be formed from an alternative material such as but not limited to nylon. Nevertheless, the skilled person will appreciate that forming the gas blocking layer from ethylene vinyl alcohol (EVOH) is particularly effective and may provide a blocking layer up to fifty times more effective than alternative materials such as nylon. In particular, providing a gas blocking layer formed from EVOH is particularly advantageous when used for foil style balloons adapted to be filled with Helium as this may assist in the retention of Helium within the balloon for an extended period of time.

[0030] The gas blocking layer may form at least 1 wt.% of each balloon sheet, at least 2 wt.% of each balloon sheet, at least 3 wt.% of each balloon sheet, at least 4 wt.% of each balloon sheet, or at least 5 wt.% of each balloon sheet. The gas blocking layer may form no more than 7 wt.% of each balloon sheet, no more than 6.5 wt.% of each balloon sheet, no more than 6 wt.% of each balloon sheet, no more than 5.5 wt.% of each balloon sheet, or no more than 5 wt.% of each balloon sheet. The gas blocking layer may form between 1-7 wt.% of each balloon sheet, between 2-6.5 wt.% of each balloon sheet, between 3-6 wt.% of each balloon sheet, or between 4-5.5 wt.% of each balloon sheet. Preferably, the gas blocking layer may form 5 wt.% of each balloon sheet. Provision of a gas blocking layer forming a percentage weight of each balloon sheet within the abovementioned values is particularly advantageous as it provides a balloon which is capable of retaining gas within the balloon during use thereby extending the period of time for which the balloon may remain inflated, whilst enabling the balloon to be recycled after use.

[0031] One or more balloon sheets may be connected together to form the body of the balloon. The one or more balloon sheets may be connected together at or adjacent to their edges to form the body of the balloon. The one or more balloon sheets may be connected together continuously at or adjacent to their edges to form the body of the balloon. There may be a gap in the continuous connection. The one or more balloonsheets may be sealed together. The one or more balloon sheets may be heat sealed together. By heat sealing the balloon sheets a further material to form the seal (e.g. adhesive) is not required, making it easier to recycle the balloon.

[0032] The balloon may comprise a valve. The valve may be positioned in the gap. The valve may form an airtight seal within the gap, such that the only way for air to enter the balloon through the gap is through the valve. The balloon may comprise a neck. The neck may form the gap.

[0033] The valve may be formed of plastic. The valve may comprise the same base compound as the or each foundation sheet.

[0034] The balloon may be a foil style balloon. The balloon may be a foil style balloon adapted to be filled with Helium. The balloon may comprise an illumination device operable to illuminate an internal space of the balloon. The illumination device may comprise an LED. The illumination device may comprise a power source. The power source may comprise a battery. The balloon may comprise a tab operable to be pulled out of the illumination device, thereby to turn the illumination device on. The illumination device may be positioned within the neck of the balloon. The tab may extend out of the balloon. The tab may extend out of an end of the neck of the balloon.

[0035] According to a second aspect of the present invention there is provided a balloon comprising one or more balloon sheets connected together to form a body of the balloon, wherein the or each balloon sheet comprises at least two foundation sheets, each foundation sheet comprising a common base compound and provided with a lower density surface and a higher density surface, and further comprising a gas blocking layer between the at least two foundation sheets.

[0036] The balloon according to the second aspect of the present invention may optionally comprise any optional feature of the balloon according to the first aspect of the present invention.

[0037] Detailed Description of the Invention

[0038] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:Figure 1 shows a balloon according to the present invention;

[0039] Figure 2 shows a section of a balloon sheet of the balloon of figure 1;

[0040] Figure 3 shows an embodiment of the balloon sheet of figure 2;

[0041] Figure 4 shows a section of an alternative balloon sheet for the balloon of figure 1;

[0042] Figure 5 shows an embodiment of the balloon sheet of figure 4; and

[0043] Figure 6 shows a section of an alternative balloon sheet for the balloon of figure 1.

[0044] As shown in figure 1, a balloon 1 comprises two balloon sheets 2 which are connected together to form a body 3 of the balloon 1. The balloon sheets 2 are heat sealed together in a continuous line adjacent to the edges 4 of the balloon sheets 2. The skilled person will appreciate that corresponding techniques can be used to construct balloons of more complex shapes. A gap 5 is provided in the continuous line which forms a neck 6 of the balloon 1. Heat sealing the balloon sheets 2 means a further material to form the seal (e.g. adhesive) is not required, making it easier to recycle the balloon 1. In this particular embodiment, the balloon 1 is a foil style balloon 1.

[0045] A valve (not shown) may be provided within the neck 6 of the balloon 1. The valve seals the neck 6 such that air may only enter the internal volume of the balloon 1 through the neck 6 via the valve.

[0046] An illumination device (not shown) may be provided within the neck 6 of the balloon 1. A tab may extend out of the balloon 1 through the neck 6. In use, the tab may be pulled out of the balloon 1 causing the illumination device to turn on.

[0047] As shown in figure 2, each balloon sheet 2 comprises a single foundation sheet 7 which comprises a lower density surface 8 and a higher density surface 9. The density profile of each foundation sheet 7 varies continuously from the lower density surface 8 to the higher density surface 9 such that there are no sudden changes in the density and subsequent material properties throughout the thickness of the foundation sheet 7.

[0048] Each foundation sheet 7 comprises a common base compound which in this particular embodiment is polyethylene although the skilled person will appreciate thatalternative common base compounds including polypropylene, polyvinyl alcohol, polylactic acid, or biaxially-oriented polyethylene terephthalate may also be used. The valve also comprises the same base compound as each foundation sheet 7. Each foundation sheet 7 is formed by a blown film extrusion process utilising a mixture of different density components. The mixture of different density components incorporates the common base compound, polyethylene. In this particular embodiment, the mixture of different density components comprises three or more different density components; a mixture of one or more lower density components, one or more intermediate density components and one or more higher density components. Use of a mixture of different density components provides each foundation sheet 7 with a gradual change in density profile from the lower density surface 8 to the higher density surface 9.

[0049] The mixture of lower density components assists in forming the lower density surface 8 of each foundation sheet 7 and the mixture of higher density components assists in forming the higher density surface 9. The mixture of intermediate density components assists in forming an intermediate section 10 of each foundation sheet 7 provided between the lower density surface 8 and the higher density surface 9. In this particular embodiment, the mixture of lower density components comprises linear low-density polyethylene and low-density polyethylene. The mixture of intermediate density components comprises high-density polyethylene, linear low-density polyethylene, and metallocene linear low density polyethylene. The mixture of high density components comprises bimodal polyethylene, high-density polyethylene, ethylene-vinyl acetate, and low-density polyethylene. The skilled person will appreciate that alternative density components comprising the common base compound, polyethylene may also be used such as medium-density polyethylene, and the quantities of each different density component may vary depending on the desired material properties of each foundation sheet 7.

[0050] The mixture of different density components may further comprise one or more additives which may assist in improving the processing, performance and / or appearance of each foundation sheet. In this particular embodiment, the mixture of different density compounds comprises scolecite, SiCh monox, poly oxethylene 10lauryl ether, PP nano particle, flexibilizer (POE-g-MAH), polyisobutylene, calcium carbonate, and poly(styrene-butadiene-styrene) (SBS).

[0051] In this particular embodiment, each foundation sheet 7 has a thickness of approximately 0.025 mm. The difference in density between the lower density surface 8 and the higher density surface 9 is selected such that the lower density surface 8 may be at least partially melted such that it is suitable for heat sealing the two foundation sheets 7 together to form the body 3 of the balloon 1. This is particularly advantageous as the higher density surface 9 which is not suitable for heat sealing, retains its structural integrity, forming an external surface of the body 3 of the balloon 1, assisting in the retention of helium within the balloon 1.

[0052] With reference now to figure 3, a layer of pigmented material 11 forming one or more images is provided on the higher density surface 9 of each foundation sheet 7. Although not shown, a protective coating such as a varnish or lacquer may be applied over the layer of pigmented material.

[0053] Furthermore, although in this particular embodiment each foundation sheet 7 is translucent, at least one foundation sheet 7 may alternatively be transparent or coloured.

[0054] A gas blocking layer 12 is provided on the lower density surface 8 of the foundation sheet 7. In this embodiment, the gas blocking layer 12 is provided as a layer of ethylene vinyl alcohol (EVOH) having a low gas permeability. This assists in retaining gas within the balloon during use such that the balloon may remain inflated for an extended period of time, for example, up to 7 days. The skilled person will appreciate that although other materials such as nylon may also be used as a gas blocking layer 12, forming the gas blocking layer 12 from ethylene vinyl alcohol (EVOH) is particularly effective and may provide a blocking layer 12 up to fifty times more effective than alternative materials such as nylon. The skilled person will appreciate that the gas blocking layer 12 may be integrally formed with the foundation sheet 7 or may alternatively be laminated onto the foundation sheet 7.

[0055] With reference now to figure 4, an alternative embodiment of a balloon sheet 2 is shown. In this particular embodiment, the balloon sheet 2 comprises two foundationsheets 7. Each foundation sheet 7 of the second embodiment has similar features to those of the first embodiment. As such, only new features will be discussed herein.

[0056] To form each balloon sheet 2, two foundation sheets 7a, 7b are laminated together. The higher density surface 9 of the first foundation sheet 7a is adjacent to the lower density 8 surface of the second foundation sheet 7b. Each foundation sheet 7a, 7b has the same density profile.

[0057] With reference now to figure 5, a layer of pigmented material 11 forming one or more images is provided between the first foundation sheet 7a and the second foundation sheet 7b. This is particularly advantageous as the second foundation sheet 7b acts as a protective layer, minimising the likelihood of the layer of pigmented material being damaged or removed by abrasion during use.

[0058] Although not shown, the skilled person will appreciate that the body 3 of the balloon 1 may comprise a foundation sheet 7 connected to a balloon sheet 2 comprising two or more foundation sheets 7a, 7b.

[0059] With reference now to Figure 6, a balloon sheet 2 according to an alternative embodiment of the present invention is shown. The balloon 1 shares many like features with the embodiments of the balloon sheet 2 shown in Figures 2-5 and as such, only differing features will be discussed herein.

[0060] In this particular embodiment, the balloon sheet 2 comprises two foundation sheets 7a, 7b. Each foundation sheet 7a, 7b has similar features to those of the first embodiment.

[0061] The gas blocking layer 12 is provided between the two foundation sheets 7a, 7b, and a layer of pigmented material 11 forming one or more images is provided between the first foundation sheet 7a and the gas blocking layer 12. Although in this particular embodiment the layer of pigmented material 11 is provided between the first foundation sheet 7a and the gas blocking layer 12, the skilled person will appreciate that the layer of pigmented material 11 may additionally or alternatively be provided between the gas blocking layer 12 and the second foundation sheet 7b. Both the gas blocking layer 12 and the layer of pigmented material 11 are laminated between the two foundation sheets 7a, 7b. However, in alternative embodiments, the skilled person will appreciate that thelayer of pigmented material 11 may also be integrally formed with or between the or each foundation sheet 7.

[0062] The gas blocking layer 12 in this particular embodiment forms no more than 5 wt.% of each balloon sheet 2. Such a weight percentage of EVOH in each balloon sheet 2 is low enough to enable the balloon 1 to be recycled after use.

[0063] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMS1. A balloon comprising one or more balloon sheets connected together to form a body of the balloon, wherein the or each balloon sheet comprises at least one foundation sheet, each foundation sheet comprising a common base compound and provided with a lower density surface and a higher density surface.

2. A balloon according to claim 1 wherein the density profile of the or each foundation sheet varies continuously from the lower density surface to the higher density surface.

3. A balloon according to either claim 1 or claim 2 wherein the common base compound is polyethylene (PE).

4. A balloon according to any preceding claim wherein the or each foundation sheet comprises a mixture of different density components comprising the common base compound.

5. A balloon according to claim 4 wherein the foundation sheet comprises a mixture of two different density components.

6. A balloon according to claim 5 wherein the foundation sheet comprises a mixture of a lower density component and a higher density component.

7. A balloon according to claim 4 wherein the foundation sheet comprises a mixture of three or more different density components.

8. A balloon according to claim 7 wherein the foundation sheet comprises a mixture of one or more lower density components and one or more higher density components; or from a mixture of one or more lower density components, one or more intermediate density components and one or more higher density components.

9. A balloon according to either claim 6 or claim 8 wherein the lower density components comprise: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE) or the like.

10. A balloon according to claim 8 wherein the intermediate density components comprise: high density polyethylene (HDPE), medium density polyethylene(MDPE), linear low-density polyethylene, or metallocene linear low density polyethylene or the like.

11. A balloon according to either claim 6 or claim 8 wherein the higher density components comprise: bimodal polyethylene, high-density polyethylene (HDPE), ethylene-vinyl acetate (EVA), low-density polyethylene or the like.

12. A balloon according to any of claims 4 to 11 wherein the mixture of different density components comprises at least one additive.

13. A balloon according to claim 12 wherein the additives include: scolecite, SiCE monox, poly oxethylene 10 lauryl ether, PP nano particle, flexibilizer (POE-g- MAH), polyisobutylene, calcium carbonate, poly(styrene-butadiene-styrene) (SBS) or the like.

14. A balloon according to any preceding claim wherein the or each foundation sheet has a thickness between 0.016 mm-0.2 mm.

15. A balloon according to any preceding claim wherein the difference in density between the lower density surface and the higher density surface is selected such that the lower density surface may be at least partially melted for heat sealing without adversely impacting the structural integrity of the higher density surface.

16. A balloon according to any preceding claim wherein the lower density surface of the one or more foundation sheets are connected together to form the body of the balloon.

17. A balloon according to claim 16 wherein the one or more foundation sheets are heat sealed together.

18. A balloon according to claim 16 or 17 wherein a layer of pigmented material is provided on the higher density surface of the one or more foundation sheets.

19. A balloon according to any of claims 1 to 15 wherein two or more foundation sheets are laminated together to form a balloon sheet.

20. A balloon according to claim 19 wherein each of the foundation sheets has the same density profile.

21. A balloon according to either claim 19 or claim 20 wherein a layer of pigmented material is provided between each of the two or more foundation sheets.

22. A balloon according to any of claims 19 to 21 further comprising a gas blocking layer provided between each, or integrally formed with or between, each of the two or more foundation sheets.

23. A balloon according to claim 22 wherein the gas blocking layer is formed from ethylene vinyl alcohol (EVOH).

24. A balloon according to claim 22 or 23 wherein the gas blocking layer forms between 1-7 wt.% of each balloon sheet.

25. A balloon according to any of claims 19 to 24 wherein one or more balloon sheets are connected together to form the body of the balloon.

26. A balloon according to any preceding claim wherein the balloon comprises a valve comprising the same base compound as the or each foundation sheet.

27. A balloon according to any preceding claim wherein the balloon is a foil style balloon.

Images