GB2546754A

GB2546754A - Wrapper

Info

Publication number: GB2546754A
Application number: GB1601469.8A
Authority: GB
Inventors: Shaw Mark; Beardsall Ian
Original assignee: Parkside Flexibles Europe Ltd
Current assignee: Parkside Flexibles Europe Ltd
Priority date: 2016-01-26
Filing date: 2016-01-26
Publication date: 2017-08-02
Also published as: GB201601469D0

Abstract

A wrapper 1 in the form of a sleeve with a longitudinal axis 5, the wrapper including first 10 and second 20 strips of flexible sheet material. The first strip is wound about the longitudinal axis with adjacent windings of the first strip abutting each other to form a spiral butt joint 11 from a first longitudinal end 3 of the sleeve to a second longitudinal end 4 of the sleeve. The second strip is spirally wound about the longitudinal axis on an inside face of the first strip, such that the second strip bridges the butt joint between the first and second longitudinal ends of the sleeve. The second strip of material is sealed to the first strip on each side of the butt joint. The wrapper may include end seals 6, 7 and the wrapper may be opened by tearing. The first and second strips may be of a different material, and may be of different thickness.

Description

WRAPPER

Background

One type of food product packaging is a wrapper of flexible sheet material. The wrapper typically comprises seals at each end and a longitudinal seal along the package. This type of wrapper is useful for food products such as confectionery, bakery products, tortilla wraps, confectionery and ice creams.

It can be difficult to remove a food product from a conventional wrapper, especially if the wrapper is formed of a polymer material or tightly fitted around the product.

There is a requirement for alternative packaging.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

An aspect of the disclosure provides a wrapper in the form of a sleeve having a longitudinal axis, the wrapper comprising: a first strip of flexible sheet material which is spirally wound about the longitudinal axis with adjacent windings of the first strip abutting each other to form a spiral butt joint from a first longitudinal end of the sleeve to a second longitudinal end of the sleeve; a second strip of flexible sheet material which is spirally wound about the longitudinal axis on an inside face of the first strip of flexible sheet material, with the second strip bridging the butt joint between the first longitudinal end of the sleeve and the second longitudinal end of the sleeve; and wherein the second strip of flexible sheet material is sealed to the first strip of flexible sheet material on each side of the butt joint.

The wrapper may comprise an end seal laterally across a first longitudinal end of the wrapper; a tearable feature in the end seal for allowing a user to tear open the wrapper; and wherein a first end of the butt joint is aligned with the tearable feature.

The tearable feature may be located at, or adjacent to, a corner of the wrapper.

The second strip of flexible sheet material may be sealed to the first strip of flexible sheet material by a permanent seal.

The second strip of flexible sheet material may be configured to tear most easily along a longitudinal axis of the second strip.

The second strip of flexible sheet material may be formed of a polymer material with molecules oriented with the longitudinal axis of the second strip.

The first strip of flexible sheet material may have a first thickness, and the second strip of flexible sheet material may have a second thickness, where the second thickness is less than the first thickness.

The first strip of flexible sheet material may have a first width, and the second strip of flexible sheet material may have a second width, where the second width is less than the first width.

The first strip of flexible sheet material may be configured to tear most easily in a tear direction at an angle to a longitudinal axis of the first strip.

The tear direction may be defined by a line of weakness formed in the first strip of flexible sheet material.

There may be a plurality of the lines of weakness formed at intervals along the longitudinal axis of the first strip of flexible sheet material.

The first strip of flexible sheet material may be formed of a polymer material with molecules oriented in the tear direction.

An aspect of the disclosure provides a method of manufacturing a wrapper in the form of a sleeve, the method comprising: combining a first strip of flexible sheet material and a second strip of flexible sheet material, by partially overlapping the first strip and the second strip to leave a portion of the second strip exposed and sealing the first strip to the second strip; laying the combined strips onto a mandrel at an angle to a longitudinal axis of the mandrel as the mandrel is rotated about the longitudinal axis, such that windings of the combined strips are laid alongside one another with a butt joint; sealing the windings to one another to form a continuous sleeve.

The method may comprise laterally sealing across the sleeve; and cutting the continuous sleeve into discrete lengths.

Sealing the first strip to the second strip and sealing the windings comprises heat sealing.

The first strip of flexible sheet material may be a polymer material. The second strip of flexible sheet material may be a polymer material. A polymer material can provide barrier properties to gas and/or moisture.

The first strip of flexible sheet material may be a different material to the second strip of flexible sheet material.

The first strip of flexible sheet material and/or the second strip of flexible sheet material can be a laminate with more than one layer. The laminate can comprise a barrier layer which provides protection to gas and/or moisture.

Other possible materials for the first strip of flexible sheet material and/or the second strip of flexible sheet material include paper, cellulose, biopolymer.

The wrapper may be formed of polymer materials which are ovenable. In this specification, the term “ovenable” means the wrapper is formed of an oven grade material which is capable of withstanding heating in an oven, such as a conventional oven (gas, electric) and/or microwave oven for a cooking period. Typically the cooking period is less than one hour.

An advantage of at least one example is that the wrapper can be opened progressively by a user, with the user unwinding a portion of the wrapper to reveal the product.

An advantage of at least one example is that the wrapper can be opened more easily by a user.

The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.

Brief Description of the Drawings

Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:

Figure 1 shows an example of a wrapper;

Figure 2 shows a cross-section through part of the wrapper of Figure 1;

Figure 3 shows how the wrapper is opened;

Figure 4 shows tearable properties of the second strip;

Figure 5 shows tearable properties of the first strip;

Figure 6 shows a way of achieving the tearable properties shown in Figure 5 by using lines of weakness in the first strip;

Figure 7 shows another way of achieving the tearable properties shown in Figure 5 by using directional properties of the material of the first strip;

Figure 8 shows an example relationship between the tearable properties of the first strip and the overall wrapper;

Figures 9 shows a manufacturing stage of the wrapper where strips of sheet material are combined;

Figure 10 shows a manufacturing stage of the wrapper where the material is spirally wound;

Figure 11 shows a manufacturing stage of the wrapper where the spirally wound material is sealed;

Figure 12 shows a sequence of stages of laying windings of a wrapper;

Figures 13 and 14 show apparatus used in a manufacturing stage of the wrapper.

Common reference numerals are used throughout the figures to indicate similar features.

Detailed Description

Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

Figure 1 shows an example of a wrapper 1. The wrapper 1 is in the form of a sleeve with a longitudinal axis 5, a first longitudinal end 3 and a second longitudinal end 4. Each longitudinal end 3, 4 of the wrapper is sealed by a seal 6, 7 laterally across the end of the wrapper. The sleeve 1 has a hollow interior for accommodating a product, such as a food product. The sleeve 1 comprises a first strip 10 of flexible sheet material which is spirally wound about the longitudinal axis 5. Adjacent windings of the first strip 10 abut each other in a butt joint 11 (shown in more detail in Figure 2). The butt joint 11 is a spiral butt joint which runs from the first longitudinal end 3 of the sleeve to the second longitudinal end 4 of the sleeve. A tearable feature, such as a notch 8, is provided in the seal 6 at the first end 3 of the wrapper. The tearable feature 8 allows a user to tear open the wrapper. A first end of the butt joint 11 is aligned with the tearable feature 8. In Figure 1, the tearable feature 8 is located at a corner of the wrapper. The wrapper of Figure 1 has a length L and a width W. Typically, the wrapper has a length L > width W.

Figure 2 shows a cross-section through two adjacent spiral windings of the wrapper of Figure 1. Adjacent windings of the first strip 10 abut each other in a butt joint 11. The butt joint may have zero spacing between the adjacent windings, or a negligible spacing between the adjacent windings, as shown in Figure 2. For example, the “negligible spacing” can be less than 1mm, or less than 500pm. A second strip 20 of flexible sheet material is spirally wound about the longitudinal axis 5 of the wrapper on an inside face of the first strip 10 of flexible sheet material. The second strip 20 bridges the butt joint 11. The second strip 20 is spirally wound between the first longitudinal end 3 of the sleeve and the second longitudinal 4 end of the sleeve. The second strip 20 is sealed to the first strip 10 on each side of the butt joint 11.

The first strip 10 of flexible sheet material has a first thickness T1. The second strip 20 of flexible sheet material has a second thickness T2. The wrapper is configured so that it will tear apart along the butt joint 11. If the first strip 10 and the second strip 20 are formed of the same sheet material, then the second thickness T2 can be less than the first thickness T1, i.e. T2 < T1, to help the second strip 20 tear more easily than the first strip 10. If different materials are used for the strips 10, 20, then the thicknesses of the strips 10, 20 can be selected based on the properties of the materials. The thickness of the second strip can be selected based on one or more of the following factors: the thickness of the first strip; the weight of the pack when packed with product; the opening force required. Some applications may require a higher opening force. For example, products which are not to be opened by children may be packaged in a wrapper with a high opening force.

The first strip 10 of flexible sheet material has a first width W1. The second strip 20 of flexible sheet material has a second width W2. In the example shown in Figure 2 the second width W2 is less than the first width W1, i.e. W2 < W1. The second strip 20 can be equally distributed either side of the butt joint 11, such that W3 = 0.5 * W2. By selecting W2 < W1 it is possible to reduce the amount of material used to form the wrapper, and also to reduce the width of the seal required between the strips 10, 20. In other examples, the second strip can have a width W2 which is equal to width W1 of the first strip.

The second strip 20 is sealed to the first strip 10 on each side of the butt joint 11. This seal can maintain a long shelf life of the packaged product. The butt joint 11 remains the line of weakness in the wrapper, due to the smaller thickness T2 of the second strip 20 compared to the thickness T1 of the first strip, or due to properties of the sheet materials used to form strips 10, 20. Therefore, when a tearing force is applied to the butt joint, the second strip 20 will tear along the line of the butt joint 11.

The second strip 20 can be sealed to the first strip 10 in one of various ways. The second strip 20 can comprise a sealant layer, or coating, which allows the second strip 20 to be heat sealed to the first strip 10. Alternatively, an adhesive such as a permanent adhesive can be applied to one face of the second strip 20. Another alternative is to use a peelable adhesive such as a Pressure Sensitive Adhesive (PSA) to seal the second strip 20 to the first strip 10. If a relatively weak peelable bond is formed, the second strip 20 will peel away from the first strip 10 without tearing along the line of the butt joint 11. This may be acceptable for some applications. Alternatively, a stronger bond can be formed, which will allow the second strip 20 to tear along the line of the butt joint 11.

The use of a second strip 20 of flexible sheet material and a butt joint between adjacent windings allows the wrapper to have a smooth outer surface. The second strip 20 forms an effective seal of the wrapper, which can help to provide a long shelf life of the packaged product.

The first strip 10 of flexible sheet material can be an oriented polymer material such as oriented polypropylene (OPP). The first strip of flexible polymer sheet material can be an oven grade material to allow the wrapper to be heated in an oven. The oven grade material is able to withstand heating in an oven for a typical cooking period without melting. Examples of suitable oven grade materials are polyester based film, such as Polyethylene terephthalate (PET), polyactic acid (PLA) film, cellulose, or any other suitable oven-grade polymer. The laminate should not become brittle, melt or release toxins when subjected to temperatures up to 220°C. For a wrapper which is intended for storage in a freezer, the sheet material should also be capable of withstanding low temperatures, such that the material is able to withstand an overall temperature of, for example, -40°C to +220°C.

The second strip 20 of flexible sheet material can be formed of the same material as the first strip 10, or can be formed of a different material.

Figure 3 shows how the wrapper can be opened. A user grasps the end seal 6 at the first end 3 of the wrapper with one hand, and holds the remainder of the wrapper with the other hand (not shown). The user grasps the end seal 6 adjacent the tearable feature 8. The user then pulls the end seal 6. This causes the wrapper to tear along the butt joint 11. The user can tear away as much of the wrapper as desired. For a product which is progressively consumed, such as a food product (e.g. tortilla wrap, bakery product), the wrapper can be torn away in stages. A portion of the wrapper which has been unwound can be removed and disposed of, or can remain.

Figure 4 shows an example of tearable properties of the second strip 20. In this example the second strip 20 is configured to tear along, or parallel to, the longitudinal axis 17 of the strip 20. The second strip 20 is configured so that a tearing force required in a direction along, or parallel to, the longitudinal axis 17 of the strip 20 is less than a tearing force required at an angle with respect to the longitudinal axis 17 of the strip 20. This helps to ensure that the second strip 20 tears along the butt joint 11 when the wrapper is opened and unwound. The tearable properties of the second strip 20 can be achieved, for example, by selection of the material of the second strip 20. For example, the material can be an oriented polymer film where the molecules in the film are oriented along, or parallel to, the longitudinal axis of the film. A suitable example is a monoaxially molecular oriented film such as Monoaxially Oriented Polypropylene (MOPP). In another example, the second strip 20 can be another type of film, such as a biaxially oriented polyethylene (BoPET), which has different tearable properties. For example, a BoPET may be tearable in two directions.

Figure 5 shows an example of tearable properties of the first strip 10. In this example the first strip 10 is configured to tear in a direction which is offset at an angle to the longitudinal axis 12 of the strip 10. The first strip 10 is configured so that a tearing force required in a direction at an angle to the longitudinal axis 12 of the strip 10 is less than a tearing force required along the longitudinal axis 12 of the strip 10. Figure 5 shows two example directions in which the first strip 10 can be configured to tear most easily: a direction 13A perpendicular to the longitudinal axis 12; and a direction 13B at an angle Θ to the longitudinal axis 12. The properties shown in Figure 5 have several advantages. One advantage is that it can allow the unwound portion of the wrapper to be torn away from the wound portion of the wrapper. Another advantage is that it can help to prevent the first strip tearing along the line of the butt joint 11.

Figures 6 and 7 show two possible ways of achieving the tearable properties shown in Figure 5. In Figure 6 lines of weakness 14 are formed in the first strip 10. The lines of weakness can be score lines, scribe lines, crenellated lines or similar lines which weaken the first strip. The lines of weakness can be distributed at intervals along the longitudinal axis 12 of the first strip so that the first strip 10 can tear along one of the lines of weakness 14 when the wrapper is unwound. The lines of weakness 14 can be formed by a laser cutter, die cutter, guillotine or any other suitable cutting apparatus.

In Figure 7 the tearable properties shown in Figure 5 are achieved by directional properties of the material of the first strip. For example, the material can be an oriented polymer film where the molecules in the film are oriented along, or parallel to, the longitudinal axis of the film. A suitable example is a monoaxially molecular oriented film such as Monoaxially Oriented Polypropylene (MOPP).

The first strip 10 can be configured to tear most easily at an angle Θ to the longitudinal axis 12. Figure 8 shows that this angle Θ can be selected such that the tear direction 13 is perpendicular to the longitudinal axis 5 of the wrapper. This has an advantage of providing a neat appearance as the wrapper is progressively unwound. The unwrapped portion of the wrapper is removed by tearing in direction 13. It will be understood that the first strip 10 can be configured at a different angle Θ.

Figures 9 to 14 shows a sequence of stages for manufacturing the wrapper. In this example, a heat seal is formed between the first strip 10 and the second strip 20. Figure 9 shows an initial stage. The first strip of polymer flexible sheet material is provided on a first roll 31. The second strip of polymer flexible sheet material is provided on a second roll 32. The two webs (from roll 31 and roll 32) are fed in together with a required overlap distance (e.g. W3). The overlapped webs are passed directly under a heater 33, such as a thermal ‘horse shoe’ fitted with a Teflon® band. At this point the materials 10, 20 are bonded together by the heater 33. The heat sealed webs are then wound onto an output roll 34.

Figures 10 and 11 show how the material from roll 34 is used to form the wrapper. A mandrel apparatus comprises a mandrel (column) 43 with a longitudinal axis 45, a mandrel boss (support) 41 and a belt drive 42. The belt drive 42 is configured to rotate the mandrel 43 about the longitudinal axis 45. Other types of drive are possible, such as a geared drive or a direct drive. Material 46 from roll 34 (Figure 9) is fed to the mandrel at an angle Φ to the longitudinal axis 45 of the mandrel. The angle Φ is chosen based on the desired angle of the spiral in the final wrapper 1. The material 46 is applied to the mandrel such that an edge of the first strip 10 lies alongside an edge of a previously laid first strip 10. The first strip is laid on top of the exposed part of the second strip 20. As the mandrel rotates, the part of the wrapper with a first strip 10 overlapping a second strip 20 in an unsealed state passes a heater 44. The heater can apply heat to the wrapper by contact with the wrapper, by hot air or a radiant heater, or by any other suitable method. The sealed spirally wound wrapper is delivered from a lower end of the mandrel.

Figure 12 shows the winding process in more detail. At step A, some existing windings have been formed on the mandrel 43. At step B a new winding of the material 46 is laid onto the mandrel 43. The new winding is laid onto the existing winding, with the strip 10 laid onto the exposed portion of strip 20, and with a butt joint 11. Step C shows the resulting windings. At step D heat is applied to the new winding to seal the first strip 10 (of the newly laid winding) to the second strip 20 (of the previously laid winding).

The spirally wound, sealed, wrapper material output from the mandrel is supplied to a cutting and sealing station, shown in Figures 13 and 14. The cutting and sealing station cuts the continuous tube of spirally wound material into discrete lengths for individual wrappers 1. The discrete lengths are sealed at one end 3 and a tear feature 8 is made on the seal 6. The cutting and sealing station 50 comprises a rotary sealing/cutting mandrel 51 which rotates and moves on a sliding carriage. As a length of completed material is supplied from the mandrel 41, the cutting and sealing station 50 moves into position and operates on the material. Figure 9 shows tools carried by the cutting and sealing station 51. The mandrel 51 comprises: a bearing carriage at each end (A); thermal sealing jaws (B) for sealing the end of the wrapper; and a reciprocating guillotine (C) for cutting the continuous material into a discrete wrapper. The end product of this manufacturing process are wrappers which are sealed at one end 3. The wrappers can be filled with a product and then sealed at the other end 4. Typically, the manufacture of the wrapper will occur at a different location to the filling. In an alternative, the end product of the manufacturing process are wrappers which are unsealed at ends 3, 4. Subsequently, the wrappers are filled with a product and sealed at both ends 3, 4. The wrapper shown in the Figures has a butt joint 11 which is aligned with a corner of the final wrapper. This can be achieved by a combination of the package length L and width W (Figure 1), the first strip width (W1, Figure 2) and the spiral winding angle (Φ, Figures 7, 11) to locate the butt joint at the desired longitudinal position. So, for a particular package length & width, it is possible to select the strip width W1 and winding angle Φ to position the butt joint where it is required.

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

Any reference to 'an' item refers to one or more of those items. The term 'comprising' is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.

The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention.

Claims

1. A wrapper in the form of a sleeve having a longitudinal axis, the wrapper comprising: a first strip of flexible sheet material which is spirally wound about the longitudinal axis with adjacent windings of the first strip abutting each other to form a spiral butt joint from a first longitudinal end of the sleeve to a second longitudinal end of the sleeve; a second strip of flexible sheet material which is spirally wound about the longitudinal axis on an inside face of the first strip of flexible sheet material, with the second strip bridging the butt joint between the first longitudinal end of the sleeve and the second longitudinal end of the sleeve; and wherein the second strip of flexible sheet material is sealed to the first strip of flexible sheet material on each side of the butt joint.

2. A wrapper according to claim 1 further comprising: an end seal laterally across a first longitudinal end of the wrapper; a tearable feature in the end seal for allowing a user to tear open the wrapper; and wherein a first end of the butt joint is aligned with the tearable feature.

3. A wrapper according to claim 2 wherein the tearable feature is located at, or adjacent to, a corner of the wrapper.

4. A wrapper according to any one of the preceding claims wherein the second strip of flexible sheet material is sealed to the first strip of flexible sheet material by a permanent seal.

5. A wrapper according to any one of the preceding claims wherein the second strip of flexible sheet material has a longitudinal axis, and the second strip of flexible sheet material is configured to tear most easily along the longitudinal axis of the second strip.

6. A wrapper according to claim 5 wherein the second strip of flexible sheet material is formed of a polymer material with molecules oriented with the longitudinal axis of the second strip.

7. A wrapper according to any one of the preceding claims wherein the first strip of flexible sheet material has a first thickness, and the second strip of flexible sheet material has a second thickness, where the second thickness is less than the first thickness.

8. A wrapper according to any one of the preceding claims wherein the first strip of flexible sheet material has a first width, and the second strip of flexible sheet material has a second width, where the second width is less than the first width.

9. A wrapper according to any one of the preceding claims wherein the first strip of flexible sheet material has a longitudinal axis, and the first strip of flexible sheet material is configured to tear most easily in a tear direction at an angle to the longitudinal axis of the first strip.

10. A wrapper according to claim 9 wherein the tear direction is defined by a line of weakness formed in the first strip of flexible sheet material.

11. A wrapper according to claim 10 wherein there is a plurality of the lines of weakness formed at intervals along the longitudinal axis of the first strip of flexible sheet material.

12. A wrapper according to claim 9 wherein the first strip of flexible sheet material is formed of a polymer material with molecules oriented in the tear direction.

13. A method of manufacturing a wrapper in the form of a sleeve, the method comprising: combining a first strip of flexible sheet material and a second strip of flexible sheet material, by partially overlapping the first strip and the second strip to leave a portion of the second strip exposed and sealing the first strip to the second strip; laying the combined strips onto a mandrel at an angle to a longitudinal axis of the mandrel as the mandrel is rotated about the longitudinal axis, such that windings of the combined strips are laid alongside one another with a butt joint; sealing the windings to one another to form a continuous sleeve.

14. A method according to claim 13 further comprising: laterally sealing across the sleeve; and cutting the continuous sleeve into discrete lengths.

15. A method according to claim 13 or 14 wherein sealing the first strip to the second strip and sealing the windings comprises heat sealing.

16. A wrapper or a method according to any one of the preceding claims wherein the first strip of flexible sheet material is a polymer material and the second strip of flexible sheet material is a polymer material.

17. A wrapper or a method according to any one of the preceding claims wherein the first strip of flexible sheet material is a different material to the second strip of flexible sheet material.