Tamper-evident shrink sleeve

Abstract

 A tamper-evident shrink sleeve (9) is described to be shrunk around at least a mouth portion of a container and a closure member closing the mouth portion so as to provide a seal. The shrink sleeve (9) comprises breaking means (17) and a tab (15) arranged adjacent the breaking means (17) for tearing the shrink sleeve (9) as defined by the breaking means (17). The shrink sleeve (9) is formed from heat-shrinkable sheet material having a first end portion (25) and a second end portion (29) overlying the first end portion (25) and being bonded or adhered to the first end portion (25) at a bonding section (27) to define an annularly closed sleeve portion (11) of the shrink sleeve (9). The tab (15) is formed by at least one of the end portions (25, 29) projecting outwardly from the sleeve portion (11). The tab (15) further comprises at least one layer (31) of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material overlying at least a partial section of the at least one end portion (29) and prevents shrinking of the end portion.

Description

[0001] The invention relates to a tamper-evident shrink sleeve and further relates to a container, in particular a bottle, provided with a tamper-evident shrink sleeve and a method of applying a tamper-evident shrink sleeve to the container.

[0002] It is known, for example from GB 2 325 219 A, to seal a bottle by placing a shrink sleeve around the mouth portion or neck of the bottle and the closure member closing the mouth portion, for example a cap screwed onto the mouth portion. The shrink sleeve is shrunk to the bottle to give a close fit so that the content of the bottle cannot readily be tampered with without removing the seal first.

[0003] To assist removal of the seal, the sleeve is provided with weakening means, for example a pair of lines of perforations axially extending along the sleeve. The sleeve material in between the lines of perforations may end in a grabbing tab to assist tearing off. It is also known, for example from GB 2 271 333 A, to include a tear tape in the shrink sleeve to facilitate breaking of the seal.

[0004] Grabbing tabs provided on known shrink sleeves are small and it takes some effort to free them from surrounding sleeve material.

[0005] It is an object of the invention to provide a tamper-evident shrink sleeve which facilitates its removal or at least provides a useful alternative to existing shrink sleeves.

[0006] The invention provides a tamper-evident shrink sleeve to be shrunk around at least a mouth portion of a container and a closure member closing the mouth portion. The shrink sleeve comprises breaking means and a tab arranged adjacent to the breaking means for gripping and tearing the shrink sleeve as defined by the breaking means. The shrink sleeve is formed from heat-shrinkable sheet material having a first end portion and a second end portion overlying the first end portion at a bonding section to define an annular closed sleeve portion of the shrink sleeve, and wherein the tab is formed by at least one of the end portions projecting outwardly from the sleeve portion.

[0007] Preferably, the second end portion overlies the first end portion at the bonding section and is bonded or adhered to the first end portion. The tab is integral with the shrink sleeve and projects from the sleeve portion of the shrink sleeve so that it can easily be gripped. Since the bonding section is part of the tab or is at least adjacent thereto, the double layer of heat-shrinkable sheet material of end portions bonded to each other function like a "tear tape" which is integral with an adjacent edge of the tab for reliably breaking the seal. The tab has a predefined shape and size to make tearing off the shrink sleeve easier. The shrink sleeve may extend only along part of the closure member and/or the mouth portion but may also extend throughout the total axial length of the container. The same applies to the axial length of the tab.

[0008] The heat-shrinkable sheet material is preferably oriented polystyrene (OPS) or oriented polyvinylchloride (PVC) or oriented polyethylene terephthalate (PET) or oriented polyolephine. The heat-shrinkable sheet material can be a mono-layer foil, but can also be a multi-layer foil. Hybrid constructions of a plurality of layers of different materials, for example a laminated foil of OPS/PET/OPS, can be used. The heat-shrinkable sheet material may be bi-axially oriented, but preferably mono-axially oriented heat-shrinkable sheet material should be used. For bonding the end portions of the heat-shrinkable sheet material at the bonding section solvents or pressure-sensitive adhesives are preferably used. The term "bonding" also includes heat-welding techniques. The heat-shrinkable sheet material should be thicker than 15 µm.

[0009] Preferably, the bonding technique used, including the adhesive selected, is such that the strength of bonding is less than the degree of force required to tear the shrink sleeve by the breaking means. Thus, shrink sleeve is removed desirably using the breaking means, rather than torn off untidily by simply ripping the bonding section apart which would typically require greater strength.

[0010] In a preferred embodiment, at least a portion of the tab is a laminate of heat-shrink sheet material and a sheet material that prevents shrinking of the tab during the process of shrinking the shrink sleeve onto the container. Preferably, the tab comprises at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material overlying at least a partial section of the at least one end portion, the at least one layer being bonded or adhered to the end portion so as to prevent shrinking of the end portion.

[0011] The layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material, hereinafter simply referred to as non-heat-shrinkable sheet material, preferably is in the form of a label which is adhered to the second end portion of the heat-shrinkable sheet material during production of the shrink sleeve. Preferably, the label is a pressure-sensitive adhesive label applied to the heat-shrinkable sheet material through a common labelling process and is preferably provided with an imprint for decoration and/or information and/or additional information components, for example a booklet or the like.

[0012] The non-heat-shrinkable (or essentially non-heat-shrinkable) sheet material for restricting the shrinking of the tab is preferably polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) or paper or a metal foil. For bonding or adhering the non-heat-shrinkable sheet material to the heat-shrinkable sheet material, acrylate adhesive or solvent adhesive or hot melt or UV hot melt is preferably used. The thickness of the non-heat-shrinkable sheet material is preferably larger than 15 µm in the case of plastic material. Paper material should have a weight of more than 20 g/m². Of course, also the non-heat-shrinkable sheet material used for labelling can be of a multi-layer construction including metallization layers to improve the aesthetic appearance.

[0013] The heat-shrinkable sheet material forming the sleeve portion can also be provided with an imprint similar to the non-heat-shrinkable sheet material forming the label. The imprint can be applied to the outer visible surface of the sheet material. In the case of transparent sheet material, the imprint provided on the heat-shrinkable sheet material and/or the non-heat-shrinkable sheet material can be provided to an inner surface of the sheet using a reverse imprinting technique. Instead of providing the imprint on the sheet material of the label, the imprint can be made on the heat-shrinkable sheet material of the end portion if the label is made of transparent sheet material.

[0014] It is sufficient to provide the second end portion on only one side with the layer of non-heat-shrinkable sheet material to restrict shrinking at the tab, but in this case the tab may curl like a bi-metallic element due to different contractions of adjacent layers of the laminate. In preferred embodiments of the tamper-evident shrink sleeve, the laminated stack of heat-shrinkable sheet material layers and non-heat-shrinkable sheet material layers are arranged symmetrically to a middle plane of the tab. In a preferred embodiment, the tab may comprise two layers of non-heat-shrinkable or essentially non-heat-shrinkable sheet material overlying and being bonded or adhered to opposite sides of the at least one end portion. The end portion of the heat-shrinkable sheet material may comprise only one layer, i.e. the sheet material of only the second end portion. But to improve the stability of the tab in another embodiment the two layers of non-heat-shrinkable or essentially non-heat-shrinkable sheet material overly and are bonded or adhered to opposite sides of a laminate of both end portions bonded or adhered together through a bonding section between the end portions.

[0015] In another embodiment providing an essentially non-curling tab, the at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material is arranged in between the end portions and is bonded or adhered to both end portions at the bonding section.

[0016] The first end portion and the second end portion may be attached to each other at the bonding section on the same surface side of the heat-shrinkable sheet material. In this case both end portions including the bonding section therebetween project from the sleeve portion to the outer side of the sleeve portion with the result that the tab more or less radially projects from the sleeve portion. Alternatively, a first surface of the heat-shrinkable sheet material at the second end portion may be attached to the opposite surface of the sheet material at the first end portion such that at the bonding section the second end portion overlies the first end portion in the circumferential direction of the sleeve portion. In this case the second end portion projects from the bonding section to the radially outer side of the sleeve portions essentially in the circumferential direction.

[0017] The sleeve portion preferably has at least one axial end edge and comprises adjacent to the bonding section at least one line of perforations or at least one line of a weakening stamp intersecting with the axial end edge and extending essentially along an edge of the tab adjacent thereto so as to form the breaking means assisting the tearing off of the shrinking sleeve by pulling and/or twisting the tab. Additionally or alternatively, the axial end edge of the sleeve portion can be provided with at least one cut or weakening stamp directly at the axial end edge. Preferably, the sleeve portion has two axial end edges at a distance from each other and the at least one line of perforations or the at least one line of a weakening stamp intersects with both axial end edges, wherein the tab extends essentially along the total distance between the axial end edges. Of course, both end edges may be provided with cuts or weakening stamps. Preferably, on both sides of the tab seen in a circumferential direction of the sleeve portion there are provided lines of perforations or lines of weakening stamps.

[0018] In order to prevent stripping off the shrink sleeve from the mouth portion and the closure member without tearing the shrink sleeve in an attempt to tamper with the product, the mouth portion and/or the closure member preferably comprise at least one projection projecting outwardly from a surface of the container or the closure member. Since the shrink sleeve is firmly shrunk onto the projection stripping off without damage to the shrink sleeve is prevented.

[0019] It is also preferred that the sleeve portion, once heat-shrunk onto a container, folds or curves over the top edge of the closure member. This prevents, or at least makes it very difficult, for the top of the sleeve to be pushed aside enabling access to the closure member which could then be opened or removed. This is especially important in the case of the closure member having a lid or top that is lifted or pulled upwardly to open the closure member.

[0020] Usually the sleeve portion of the shrink sleeve is annularly closed before the shrink sleeve is put on the container. To apply the shrink sleeve on an industrial scale specialized sleeve applying machinery is necessary. Common commercial label-applying machinery can be used in the case of a shrink sleeve wherein at the bonding section the second end portion overlies the first end portion in the circumferential direction of the sleeve portion as mentioned above. A method of applying a tamper-evident shrink sleeve preferably comprises the step of wrapping around the mouth portion and the closure member of the container a piece of heat-shrinkable sheet material having a first end portion and a second end portion which is provided with at least one layer of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material and adhering the first end portion to the container and the second end portion to the first end portion with the at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material projecting outwardly. By means of this method the sleeve portion of the shrink sleeve is formed directly on the container, and this can be done by a labelling machine commonly used for applying labels, for example pressure-sensitive labels, to articles. After having formed the sleeve portion directly on the container, the sleeve portion is shrunk onto the container by applying heat to at least a sleeve portion formed from the piece of heat-shrinkable sheet material between the first end portion and the second end portion.

[0021] Here and in the embodiments described above, heat for shrinking the shrink sleeve may be applied through hot air or infra-red radiation or steam or the like.

[0022] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein:

Fig. 1 shows a side view of a container with a tamper-evident shrink sleeve according to a first embodiment of the invention;

Fig. 2 is a cross-sectional view of the container and the shrink sleeve, seen along a line II-II in Fig. 1;

Fig. 3 is a developed plan view of the shrink sleeve shown in Fig. 2;

Fig. 4 is a cross-sectional view of the shrink sleeve seen along a line IV-IV in Fig. 3;

Fig. 5 is a cross-sectional view of a second embodiment of a tamper-evident shrink sleeve;

Fig. 6 is a cross-sectional view of a third embodiment of a tamper-evident shrink sleeve; and

Fig. 7 is a cross-sectional view of a fourth embodiment of a tamper-evident shrink sleeve according to the invention.

[0023] Fig. 1 shows a container in the form of a bottle 1 having a neck 3 ending in a mouth portion 5 which is closed by a removable closure member 7 in the form of a cap screwed onto the mouth portion 5. In order to prevent tampering of the content of the bottle 1, the mouth portion 5 and the closure member 7 are surrounded by a seal in the form of a shrink sleeve 9 having a sleeve portion 11 (see also Fig. 2) which is firmly shrunk onto the mouth portion 5 and the closure member 7 so that removing the closure member 7 without tearing the seal provided by the sleeve portion 11 is not possible. The shrink sleeve 9 thus provides evidence of an attempt to tamper with the product. The mouth portion 5 and the closure member 7 are provided with projections 13 or ribs or the like forming undercuts which prevent relative movement between the sleeve portion 11, the mouth portion 5 and the closure member 7. In the embodiment of Fig. 1 the sleeve portion 11 only partially extends along the closure member 7 and the neck portion 5 in axial direction. The sleeve portion11 of course may completely cover the bottle 1.

[0024] To easily break the seal provided by the sleeve portion 11, the sleeve portion 11 is provided with breaking means explained in detail below and a relatively large tab 15 extending radially outwards from the sleeve portion 11 in an axially longitudinal section of a bottle 1. The tab 15 extends at least 1 cm in the radial direction, and at least 1 cm, preferably more than 1.5 cm in the axial direction. As can be seen from Figs. 2 to 4, the sleeve portion 11 is provided with breaking means in the form of lines of perforations 17 adjacent to the tab 15 on each side thereof as seen in a circumferential direction of the sleeve portion 11. Each line of perforations 17 extends over the total distance between opposed axial end edges 19 of the sleeve portion 11 and ends in a cut 21 at each axial end edge 19. By pulling and/or twisting the tab 15, the sleeve portion 11 will tear along the lines of perforations 17 thus breaking the seal. The cuts 21 may be omitted so that the breaking means for breaking the seal will only be provided by lines of perforations, and, alternatively, the lines of perforations may be omitted such that the cuts 21 will be the only aid in breaking the seal. Instead of perforations having holes going through the sheet material of the sleeve portion 11, lines of stamps weakening the sheet material may be provided. The same applies to the cuts 21 which may be substituted by weakening stamps.

[0025] As can best be seen from Figs. 2 to 4, the shrink sleeve 9 comprises a piece 23 of heat-shrinkable sheet material having a first end portion 25 which is adhered at a bonding section 27 to a second end portion 29 of the piece 23 of heat-shrinkable sheet material. The second end portion 29 also provides a layer of the tab 15 which is integral with the sleeve portion 11. As can be seen from Figs. 3 and 4, the sleeve portion 11 including the lines of perforations 17 and the cuts 21 are arranged between the end portions 25, 29.

[0026] The sleeve portion 11 is heated when applied to the bottle 1 to be shrunk onto the mouth portion 5 and the closure member 7. In order to restrict the shrinking of the end portion 29 and thus the tab 15, the end portion 29 is provided on both sides of the heat-shrinkable sheet material with labels 31 made of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material. The labels 31 have the same size and overly each other on opposite surfaces of the second end portion 29 of the piece 23. The labels 31 are adhered to the second end portion 29 using a pressure-sensitive adhesive. The first end portion 25 is bonded at the bonding section 27 to the second end portion 29 also using a pressure-sensitive adhesive or any other type of adhesive capable of withstanding tampering with the seal. As an alternative, welding may be used instead of an adhesive.

[0027] The labels 31 carry imprints 33 for decoration and information. The imprints 33 may be printed on the external surfaces of the labels 31 or, if the labels are transparent, on an inner surface using a reverse printing technique. As known from pressure-sensitive labels, the labels 31 can be in the form of multi-layer labels including a metallization layer for improving the aesthetic appearance.

[0028] The labels 31 are arranged symmetrically with respect to the end portion 29 so that not only shrinking of the end piece 29 is prevented, but also curling of the tab 15 which might occur under a "bi-metal effect" of two layers having different contraction properties. Suitable materials for the labels 31 are PE, PP, PS, PET and paper or a metal foil, each preferably having a thickness of at least 15 µm, except for paper which should preferably have a weight of at least 20 g/m². The adhesive for bonding the labels 31 to the end portion 29 should be strong enough to withstand the shrinking of the heat-shrinkable sheet material of the end section 29. Suitable adhesives are for example acrylate adhesives, solvent adhesives, hot melt and UV hot melt.

[0029] Suitable materials for the heat-shrinkable sheet material of piece 23 are for example OPS, PVC, PET, polyolephine and also multi-layer constructions of different materials such as for example an OPS-PET-OPS laminated construction. Of course, OPS, PVC, PET and polyolephine films can also be in the form of multi-layer films. The total thickness of the heat-shrinkable sheet material should preferably be more than 15 µm.

[0030] The heat-shrinkable sheet material can be bi-axially oriented so that the material can shrink in two directions perpendicular to each other. Preferably, the heat-shrinkable sheet material of piece 23 is a mono-axially oriented material which means that the material essentially shrinks in only one direction, preferably in a direction extending in the circumferential direction of the sleeve portion 11 which is shown in Fig. 3 by an arrow 35. With respect to the machine direction of the sheet material producing machine, the orientation of the shrink direction 35 is transversal to the machine direction. The advantage of this shrinking orientation is that the labels 31 and the adhesive in the bonding section 27 can be applied in machine direction, i.e. continuously during in-line production.

[0031] Further embodiments are described below. Components of equal function or equal purpose have been assigned the reference numerals of Figs. 1 to 4 and additionally a letter for distinction. Reference is made to the description of Figs. 1 to 4 including the explanation of the embodiment and the variants explained above.

[0032] In the embodiment of Figs. 1 to 4, the bonding section 27 and the labels 31 are arranged radially one behind the other on the second end portion 29. Fig. 5 shows an embodiment wherein both the first end portion 25a and the second portion 29a overly each other over essentially the whole of the tab 15a. Both end portions 25a, 29a on their outer surfaces are covered by labels 31a. The bonding section 27a therefore extends throughout the tab 15a thus strengthening the tab 15a.

[0033] In the embodiments of Figs. 1 to 5, the labels 31a symmetrically cover the end portions of piece 23, 23a of heat-shrinkable sheet material. Fig. 6 shows an embodiment of inverse symmetry. The embodiment comprises a single label 31b of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material which is covered on its opposite surfaces by the first end portion 25b and the second end portion 29b overlying the label 31b. The end portions 25b and 29b are bonded through separate layers of the bonding section 27b to the label 31b. The bonding section 27b thus includes the label 31b in its bonding path bonding the second end portion 29b to the first end portion 25b of piece 23b of heat-shrinkable sheet material. The imprint 33b is shown in Fig. 6 as being imprinted onto the end portions 25b, 29b and of course can be printed onto the label 31b if the piece 23b is a transparent material.

[0034] In the embodiments of Figs. 1 to 6, the tab radially extends from the sleeve portion in an axially extending radial section plane. Fig. 7 shows an embodiment of a shrink sleeve 9c wherein the tab 15c extends outwardly from the sleeve portion 11c in a plane tangential to the sleeve portion 11c. In this embodiment, the second end portion 29c overlies the first end portion 25c in the circumferential direction of the sleeve portion 11c with the bonding section 27c in between. Similar to Fig. 2, the end portion 29c is symmetrically covered by labels 31c each being made of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material as explained above. Again, the label 31c bears an imprint 33c.

[0035] In the embodiment of Fig. 7, the sleeve portion 11c can be prepared in advance before applying the shrink sleeve 9c to the container and heat-shrinking the sleeve portion 11c onto the container while the labels 31c prevent shrinking of the tab 15c. The embodiment of Fig. 7 can also be applied to the container without having bonded the end portions 25c, 29c together to form the sleeve portions 11c in advance. By using a common labelling machine, the sleeve portion 11c can be formed directly on the container if the labelling machine adheres the first end portion 25c for example through a section of adhesives as indicated at 37 to the container and thereafter wraps the piece 23c of heat-shrinkable material around the container until the second end portion 29c reaches and overlies the end portion 25c to be bonded thereto in the bonding section 27c and to annularly close the sleeve portion 11c. Thereupon the sleeve portion 11c may be heated to be shrunk to the container. If the sleeve portion 11c is formed directly on the container as explained above, the piece 23c of heat-shrinkable sheet material is preferably cut from material oriented in machine direction in order to enable supplying the pieces on a liner web to the labelling machine.

Claims

1. A tamper-evident shrink sleeve to be shrunk around at least a mouth portion of a container and a closure member closing the mouth portion, the shrink sleeve comprising breaking means and a tab arranged adjacent to the breaking means for gripping and tearing the shrink sleeve as defined by the breaking means,
wherein the shrink sleeve is formed from heat-shrinkable sheet material having a first end portion and a second end portion overlying the first end portion at a bonding section to define an annularly closed sleeve portion of the shrink sleeve,
wherein the tab is formed by at least one of the end portions projecting outwardly from the sleeve portion.

2. The tamper-evident shrink sleeve according to claim 1, wherein the tab further comprises at least one layer of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material overlying at least a partial section of the at least one end portion, the at least one layer being bonded or adhered to the end portion so as to prevent shrinking of the end portion.

3. The tamper-evident shrink sleeve according to claim 2, wherein the tab comprises two layers of non-heat-shrinkable or essentially non-heat-shrinkable sheet material overlying and being bonded or adhered to opposite sides of the at least one end portion.

4. The tamper-evident shrink sleeve according to claim 3, wherein the two layers of non-heat-shrinkable or essentially non-heat-shrinkable sheet material are bonded or adhered to opposite sides of a laminate of both end portions bonded or adhered together through a bonding section between the end portions.

5. The tamper-evident shrink sleeve according to claim 2, wherein the at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material is arranged between the end portions and is bonded or adhered to both end portions at the bonding section.

6. The tamper-evident shrink sleeve according to claim 5, wherein the bonding section includes the at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material.

7. The tamper-evident shrink sleeve according to any one of claims 2 to 6, wherein the at least one layer of non-heat-shrinkable or essentially non-heat-shrinkable sheet material is provided with a visible imprint or a decoration.

8. The tamper-evident shrink sleeve according to any one of claims 1 to 7, wherein both end portions including the bonding section therebetween project outwardly from the sleeve portion.

9. The tamper-evident shrink sleeve according to any one of claims 1 to 7, wherein at the bonding section the second end portion overlies the first end portion in the circumferential direction of the sleeve portion and projects from the bonding section to the radially outer side of the sleeve portion.

10. The tamper-evident shrink sleeve according to any one of claims 1 to 9, wherein the sleeve portion has at least one axial end edge and, adjacent to the bonding section, comprises at least one line of perforations or at least one line of a weakening stamp intersecting with the axial end edge and extending essentially along an edge of the tab adjacent thereto so as to form the breaking means.

11. The tamper-evident shrink sleeve according to claim 10, wherein the sleeve portion has two axial end edges in a distance from each other and the at least one line of perforations or the at least one line of a weakening stamp intersects with both axial end edges and wherein the tab extends essentially along the total distance between the axial end edges (19).

12. The tamper-evident shrink sleeve according to any one of claims 1 to 11, wherein the sleeve portion has at least one axial end edge and, adjacent to the bonding section, the axial end edge is provided with at least one cut or weakening stamp so as to form the breaking means.

13. The tamper-evident shrink sleeve according to claim 12, wherein the sleeve portion has two axial end edges at a distance from each other and both axial end edges are provided with at least one cut or weakening stamp, and wherein the tab extends essentially along the total distance between the axial end edges.

14. The tamper-evident shrink sleeve according to any one of claims 1 to 13, wherein the sleeve portion folds or curves over the top edge of the closure member.

15. A container, in particular a bottle, the container comprising a mouth portion and a removable closure member for closing the mouth portion, wherein a tamper-evident shrink sleeve according to any one of claims 1 to 14 is placed around at least the mouth portion and the closure member and is shrunk onto the mouth portion and the closure member.

16. The container according to claim 15, wherein, adjacent to the mouth portion, the container and/or the closure member thereof comprise at least one projection projecting outwardly from a surface of the container or the closure member

17. A method of applying a tamper-evident shrink sleeve to a container having a mouth portion and a removable closure member closing the mouth portion, the method comprising the step of wrapping a piece of heat-shrinkable sheet material having a first end portion and a second end portion provided with at least one layer of a non-heat-shrinkable or essentially non-heat-shrinkable sheet material around the mouth portion and the closure member and adhering the first end portion to the container and the second end portion to the first end portion with the at least one layer of the non-heat-shrinkable or essentially non-heat-shrinkable sheet material outwardly,
and further comprising the step of applying heat to at least a sleeve portion formed from the piece of heat-shrinkable sheet material between the first end portion and the second end portion.

Drawing