SEALABLE CARD BASED CONTAINER AND BLANK THEREFOR

Abstract

A card based container has a tubular sidewall of laminate material and first and second end closures, sealed to the tubular sidewall to form a hermetically sealed package. The sidewall has an outer card layer, an inner hygienic layer and one or more sealing strips provided at an inner surface of the inner hygienic layer, located at connection locations where the sidewall seals to itself or to the respective end closures. The sealing strips include a heat-sealable polymer. The overall amount of non-paper content in the sidewall and in the package may thus be reduced.

Claims

1. A card based container comprising a sidewall of laminate material and first and second end closures, sealed to the tubular sidewall to form a hermetically sealed package, wherein the sidewall comprises: an outer structural layer comprising predominantly cellulose material; an inner hygienic layer comprising a layer of food quality polymer material having a thickness of between 2 microns and 20 microns; and one or more sealing strips provided at an inner surface of the sidewall, located at connection locations where the sidewall seals to itself or to the respective end closures, the sealing strips comprising a heat-sealable polymer.

2. (canceled)

3. (canceled)

4. The container according to claim 1, wherein the outer structural layer has a weight of between 100 g/m2 and 500 g/m2.

5. The container according to claim 1, wherein the sidewall comprises greater than 95% cellulose pulp content.

6. The container according to claim 1, comprising an oxygen barrier layer.

7. The container according to claim 6, wherein the oxygen barrier layer is a polymeric layer exhibiting an oxygen transmission rate of less than 0.1 cc/m2.Math.day.

8. The container according to claim 1, wherein the outer structural layer is a laminate comprising at least one layer of card material.

9. The container according to claim 1, wherein the sealing strips have a thickness of between 30 microns and 200 microns.

10. The container according to claim 1, wherein the sealing strips have a width of between 3 mm and 30 mm.

11. The container according to claim 1, wherein the sealing strips cover between 4% and 20% of the area of the sidewall.

12. The container according to claim 1, wherein one or both of the end closures comprises an outer structural layer and an inner hygienic layer.

13. The container according to claim 1, wherein the sidewall is tubular and comprises a longitudinal seal extending from the first end closure to the second end closure.

14. The container according to claim 1, wherein the sidewall has an upper rim that is rolled over and a sealing strip is provided around the upper rim.

15. The container according to claim 13, wherein the first or second end closure is applied across and sealed to the upper rim.

16. A method of manufacturing a card based container, the method comprising: providing a blank of laminate material having longitudinal edges and upper and lower edges, the laminate material comprising an outer structural layer comprising predominantly cellulose material and an hygienic layer at an inner side of the blank, applying one or more sealing strips of heat-sealable polymer to the inner side of the blank, rolling the blank with the hygienic layer facing inwards and connecting the longitudinal edges together to form a sidewall having first and second ends; closing the first end with a first end closure; filling the container with product through the second end; and sealing the container by applying a second end closure to the second end whereby connecting, closing and/or sealing takes place by heat sealing the strip of heat-sealable polymer.

17. The method of claim 16, wherein a longitudinal sealing strip is applied to one of the longitudinal edges and the longitudinal edges are connected in an overlap seam.

18. The method of claim 16, wherein a lower sealing strip is applied to the lower edge of the blank and the first or second end closure is heat-sealed to the lower edge of the blank.

19. The method of claim 16, wherein the heat-sealed lower edge is rolled over inwards such that the container can stand on a lower rim of card material.

20. The method of claim 16, comprising applying a sealing strip at or adjacent to the upper edge of the blank, rolling over the upper edge of the blank to form an upper rim with the sealing strip uppermost and sealing the first or second end closure across the upper rim.

21. A blank of card based laminate material for forming a container for oxygen sensitive food materials, the blank comprising an outer structural layer comprising predominantly cellulose material, an inner hygienic layer and an oxygen barrier layer, wherein sealing strips of heat-sealable polymer material are provided at an inner surface of the blank at sealing locations such that the blank can be sealed to itself or to another component to form the container.

22. The blank of claim 21, wherein the inner hygienic layer comprises a layer of food quality polymer material having a thickness of between 2 microns and 20 microns; and the sealing strips comprise a heat-sealable polymer having a thickness greater than that of the inner hygienic layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

[0037] FIG. 1 shows in perspective view a container according to an embodiment of the present invention;

[0038] FIG. 2 shows the container of FIG. 1 prior to assembly;

[0039] FIG. 3 shows a cross-section through the sidewall of FIG. 2 at III-III, and FIG. 3A shows an enlarged detail of FIG. 3 at IIIA;

[0040] FIG. 4 shows a detail of the container of FIG. 1 taken at IV-IV

[0041] FIG. 5 shows a cross-sectional view through an upper part of a container according to a second embodiment of the invention;

[0042] FIGS. 6A to 6C show in schematic views, steps in making the longitudinal seam of the container of FIG. 5 at the location VI-VI; and

[0043] FIG. 7 shows a cross-sectional view through the laminate used in the sidewall of the container 100 of FIG. 5.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0044] FIG. 1 shows a perspective view of a container 1 according to the invention. The container comprises a tubular sidewall 2, closed at its lower end 4 by a first end closure 6. At its upper end 8, the container is closed by a second end closure 10. The container 1 has a longitudinal seam 12 extending from the lower end 4 to the upper end 8 and has a rim 9 on which it can stably stand.

[0045] FIG. 2 shows the component parts of the container 1 of FIG. 1 prior to their assembly. The sidewall 2 is in the form of a flat, rectangular blank 20 of card based material, to be described in further detail below. An inner hygienic layer 30 of the blank 20 is visible, namely the layer that will be at the interior of the container 1 once assembled. The blank 20 has longitudinal edges 22A,B an upper edge 24 and a lower edge 26. Applied onto the inner hygienic layer at the lower edge 26 is a lower sealing strip 27. An upper sealing strip 25 is applied at the upper edge 24 and a longitudinal sealing strip 23 is applied along one of the longitudinal edges 22A.

[0046] FIG. 2 also shows the first end closure 6 and the second end closure 10. For the illustrated container, both end closures 6, 10 are oblong in shape, corresponding to the cross-section of the final container 1. It will be understood that various shapes are possible, including circular, elliptical, square, triangular and the like, although all polygonal shapes will preferably be provided with rounded corners. The first end closure 6 has a circumferential edge 7 and a structure that will be described further below. The second end closure 10 is an aluminium sealing film provided with a tear strip 11. It may be the sort of closure as described in EP3085636. It will be understood that other closures may also be used and that the second end 10 closure may also be identical to the first end closure 6.

[0047] FIG. 3 shows a cross-section through the sidewall 2 taken in the direction III-III in FIG. 2. The inner hygienic layer 30 is uppermost. This is a thin layer of PE having a thickness of 20 microns. On its surface, can be seen the upstanding lower sealing strip 27 and upper sealing strip 25. These are also the same PE material and have a thickness of 40 micron and a width of 5 mm. It will be understood that these dimensions are exemplary and FIG. 3 is not to scale.

[0048] Beneath the inner hygienic layer 30 is an oxygen barrier layer 33, which comprises an aluminium barrier film 31 and an EVOH barrier film 32. At the outer side of the oxygen barrier layer is an outer structural layer 37. In the illustrated embodiment, the outer structural layer 37 is composed of an outermost card layer 36, an adhesive layer 35 and a thin paper layer 34. The outermost card layer 36 is a 200 g/m2 kraft card layer and the overall card/paper content exceeds 95 wt %.

[0049] Manufacture of the blank 20 may take place in otherwise conventional fashion. In the illustrated exemplary embodiment, the thin paper layer 34 is delivered from a roll to a deposition station where EVOH is spray coated as an aqueous dispersion and subsequently dried to a thickness of 15 micron. The aluminium barrier film 31 is then applied by vapour deposition onto the EVOH layer to a thickness of 5 micron. Finally, the PE inner hygienic layer 30 is applied by spray coating over the metallized aluminium barrier film 31.

[0050] In a subsequent lamination step, the coated, thin paper layer 34 and the outermost card layer 36 are assembled together with the adhesive layer 35 to form a continuous laminate of sidewall material that can be cut into blanks 20. In the illustrated embodiment, the strips 23, 25, 27 are applied to the blank 20 in a slot coating process prior to forming the sidewall. It will however be understood that they may also be applied earlier to the laminate of sidewall material prior to cutting.

[0051] FIG. 4 shows a partial cross-section through the container 1 of FIG. 1 at the location of the longitudinal seam 12 taken in the direction IV-IV.

[0052] As can be seen, at this location the longitudinal edge 22B having the longitudinal sealing strip 23 overlies the other longitudinal edge 22A. The longitudinal sealing strip 23 is heat sealed to the outer structural layer 37 of the longitudinal edge 22A. In this view, the outer structural layer 37 and the oxygen barrier layer 33 are schematically shown, distinguished by a dashed line, while the inner hygienic layer 30 cannot easily be distinguished from the sealing strip 23 where heat sealing has taken place.

[0053] Also visible in FIG. 4 is the first end closure 6, applied to the lower end 4 of the tubular sidewall 2. The first end closure 6 is formed of the same laminate material as the sidewall 2 as described above in relation to FIG. 3. It is distinguished in this embodiment only in that it is not provided with sealing strips.

[0054] The first end closure 6 is oriented with the inner hygienic layer 30 uppermost. The circumferential edge 7 is folded downwards into engagement with the lower end 4 of the sidewall 2 at the position of the lower sealing strip 27 and is heat sealed thereto. The combined structure of the lower end 4 of the sidewall 2 is rolled over inwards to form the lower rim 9. At this location of the seam 12, the rim 9 is formed of three layers of card material. Around the remainder of the circumference of the container 1, only two layers of material will be rolled to form the lower rim 9.

[0055] FIG. 5 shows a cross-sectional view through an upper part of a container 100 according to a second embodiment of the invention. Distinguishing features over the first embodiment will be described and designated with the same reference numeral preceded by 100. Aspects of the container not described may be considered otherwise identical.

[0056] The container 100 comprises a sidewall 102 which, at its upper end 108, is rolled over outwardly to form an upper rim 140. An upper sealing strip 125 is applied at the crest of the upper rim 140 and extends around its full circumference. The container 100 is closed by a second end closure 110 that is sealed across the upper rim 140 and extends outwardly therefrom to a tab 142. The bottom of the container is closed by a first end closure (not shown).

[0057] The container 100 has a longitudinal seam 112 that can be seen from the inside of the container 100, extending above the level of the contents P. As in the previous embodiment, the sidewall 102 comprises an inner hygienic layer 130 and an outer structural layer 137. In this embodiment, the second end closure 110 is also manufactured of a similar laminate material and also has an inner hygienic layer 130 that engages with the upper sealing strip 125 and an outer structural layer 137. As previously discussed, the outer structural layer 137 is a multi-layer laminate as will be discussed further below. In this embodiment, the second end closure 110 is not provided with a tear strip but is instead removed in its entirety by pulling on the tab 142.

[0058] FIG. 6C shows a schematic view of the longitudinal seam 112 of the container 100 of the second embodiment at the location VI-VI. FIGS. 6A and 6B show similar views during steps in the construction of the longitudinal seam 112. As shown in FIG. 6A, the longitudinal seam 112 is made in a skiving process, whereby a portion of material is removed from the outer structural layer 137 at a first of the longitudinal edges 122A. In FIG. 6B, this first longitudinal edge 122A is hemmed by folding over the skived edge with the inner hygienic layer 130 outwards. In FIG. 6C the second longitudinal edge 122B is applied in an overlap onto the skived and hemmed first longitudinal edge 122A. The inner surface of the second longitudinal edge 122B carries a longitudinal sealing strip 123, which seals to the outer surface of the first longitudinal edge 122A. Due to the skiving and hemming, the longitudinal sealing strip 123 is heat sealed to the inner hygienic layer 130, ensuring a fully compatible seal. It will be understood that this ensures that the inner hygienic layer 130 forms a continuous seal and that engagement to the outer surface of the outer structural layer is avoided.

[0059] FIG. 7 shows a cross-sectional view through the laminate used in the sidewall 102 of the container 100 of the second embodiment. In this case, the sidewall comprises from outside in an outermost card layer 136, an adhesive layer 135, a primer layer 139, a metallized barrier film 131, an EVOH barrier film 132, a thin paper layer 134 and an inner hygienic layer 130. The lower sealing strip 127 is shown applied to the inner hygienic layer.

[0060] In this embodiment, it can be seen that the oxygen barrier layer 133, which comprises the metallized barrier film 131 and EVOH barrier film 132 is laminated within the outer structural layer 137. The skilled person will be well aware that various other laminate constructions may be contemplated and the individual layers may be adapted in thickness and construction as required.

[0061] Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art. Many modifications in addition to those described above may be made to the structures and techniques described herein without departing from the scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.