The present invention relates to a method for manufacturing a paperboard cup having a container part, connectable to a base part. Further, the present invention relates to a paperboard cup having a con- tainer part connectable to a base part, the container part having a circular cross-section narrowing from a circular mouth to a bottom portion, the mouth having a larger diameter than the bottom portion. The container part is connectable to the base part from the bottom portion.

BACKGROUND OF THE INVENTION

Disposable cups are well known for various uses. One specific use for disposable cups are cups for drinks, especially champagne glass-type cups hav ing a conical container part and a base, such as a stem or a foot. These type of disposable drinking cups have been made of plastic. Once used, the cups may cause environmental problems if they are not carefully recycled. Disposable champagne glass-type cups made of plastic can be too expensive for some uses.

OBJECTIVE OF THE INVENTION

The objective of the invention is to allevi- ate the disadvantages mentioned above.

In particular, it is an objective of the pre sent invention to provide a paperboard cup which has a conical container part connectable to a base part. SUMMARY OF THE INVENTION

According to a first aspect, the present in vention provides a method for manufacturing a paper- board cup having a container part connectable to a base part, the container part having a circular cross- section narrowing from a circular mouth to a bottom portion, the mouth having a larger diameter than the bottom portion.According to the invention the contain- er part is made of a liquid packaging board having thermoplastic polymer coating on one or both sides, the method comprising steps of: a) cutting a piece of planar elongated curved blank for the container part from a liquid packaging board sheet or web, the blank having a first end, a second end, a first curved longitudinal edge and a second curved longitudinal edge, b) securing the first end of the blank to a rotatable mandrel having a rotation axis and an outer shape corresponding to the shape of the container part to be manufactured, c) rotating the mandrel about its rotation axis to wind the blank spirally onto the mandrel, so that the first curved longitudinal edge overlaps the second curved longitudinal edge, d) applying heat-sealing energy, such as hot air, and pressure, while rotating the mandrel, onto the first curved longitudinal edge to seal the first curved longitudinal edge together with the second curved longitudinal edge to form a sealed spiral seam and to form a monolithic shape of the container part, e) cutting a mouth of the container part to be straight and even, f) removing the mandrel from inside the con tainer part, g) applying heat-sealing energy, such as hot air, and pressure to the bottom part of the container part to form a sealed container bottom and a connec tion part.

According to a second aspect, the present in vention provides a paperboard cup having a container part connectable to a base part, the container part having a circular cross-section narrowing from a cir cular mouth to a bottom portion, the mouth having a larger diameter than the bottom portion. According to the invention the container part is made as a mono lithic structure of liquid packaging board having thermoplastic polymer layer on one side or both sides, and that the container part is a spiral-wound struc ture of a piece of planar curved longitudinal blank cut from said liquid packaging board and the container part having a spiral seam, and that a connecting part is formed in the bottom portion of the container part and extending from the bottom portion for connecting the container part to the base part.

The technical effect is that the spiral-wound struc ture of the paperboard cup is able to withstand well external and internal pressures caused by a user or contents of the cup. The paperboard cup has also all the advantages of sustainable packaging. The liquid packaging board is fully recyclable. The parts of the paperboard cup can be made from same material. Accord ing to another embodiment, parts of the paperboard cup are made of different materials.

In an embodiment of the method, the method further comprises a step of connecting the container part to base part.

In an embodiment of the method, the method further comprises steps for making the base part: a) cutting a piece of planar blank for the base part from packaging board sheet or web, the blank having a first end, a second end, a first curved edge and a second curved edge, b) securing the second end of the blank for a base part to a rotatable mandrel having a rotation axis and an outer shape corresponding to the shape of the base part to be manufactured, c) rotating the mandrel about its rotation axis to wind the blank for a base part spirally onto the man drel, so that the first curved edge overlaps the sec ond curved edge, d) applying heat-sealing energy, such as hot air, and pressure, while rotating the mandrel, onto the first curved edge to seal the first curved edge together with the second curved edge to form a spiral seam and to form a monolithic shape of the base part.

In an embodiment of the method, the method further comprises a step of cutting a lower edge of the base part to be straight and even.

In an embodiment of the method, the method further comprises a step of folding an upper edge the base part inwards with a tool.

In an embodiment of the method, the method further comprises a step of cutting a piece of planar counter part having a centre portion and a connecting point and flips extending from the centre portion, from a packaging board sheet or web, and optionally cutting a disc-like stiffening part having a connecting point from a packaging board sheet or web.

In an embodiment of the method, the method further comprises a step of applying heat energy, such as hot air, and pressure to the counterpart and a stiffening part for connecting them to each other. In an embodiment of the method, the method further comprises a step of applying heat energy, such as hot air, and pressure to the flips of counterpart for con necting the counterpart, optionally with the stiffen ing part, to the inner surface of the base part.

In an embodiment of the method, the method further comprises a step of connecting the container part to base part by inserting the connecting part of the con tainer part through an opening of the upper portion of the base part and through an opening of the connecting point so that the connecting part and edges of the connecting point lock each other.

In an embodiment of the method, the method further comprises a step of protecting exposed cut raw edge of the second curved longitudinal edge against absorption of liquid, before securing the first end to a mandrel.

In an embodiment of the paperboard cup, the liquid packaging board of the cup is a multilayer structure comprising one or more layers made of bleached sul phate pulp.

In an embodiment of the paperboard cup, the base part is made of liquid packaging board having thermoplastic polymer layer on one side or both sides, and that the base part is a spiral-wound structure of a piece of planar curved longitudinal blank cut from said liquid packaging board and the base part having a spiral seam, and that a counterpart having a connection point for receiving the connecting part of the container part is arranged to the base part.

In an embodiment of the paperboard cup, the base part comprises a wall having an opening in the upper por- tion, and that an edge of the opening form a support surface for the container part.

In an embodiment of the paperboard cup, the counter part is arranged to be supported on an inner surface of the wall of the base part.

In an embodiment of the paperboard cup, that as assem bled the connection part of the container part extends through an opening of the connection point of the counterpart of the base part so that a connection is formed between the container part and the base part.

It is to be understood that the aspects and embodiments of the invention described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illus trate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Figure 1 is a slanted view of a cup, accord ing to one embodiment of the invention,

Figure 2 is a slanted view of a cup, accord ing to one embodiment of the invention,

Figure 3 is a slanted view of parts of a cup before assembly, according to one embodiment of the invention,

Figure 4 is a slanted view of parts of a cup before assembly, according to one embodiment of the invention, Figure 5 is a plan view of a blank for making a container part of a paperboard cup according to one embodiment of the invention by a method according to one embodiment of the invention,

Figure 6a is a plan view of a blank for mak ing a base part of a paperboard cup according to one embodiment of the invention by a method according to one embodiment of the invention,

Figure 6b is a plan view of a blank for mak ing an intermediate part of a base part of a paper- board cup according to one embodiment of the invention by a method according to one embodiment of the inven tion,

Figure 6c is a plan view of a blank for mak ing a counterpart part of a base part of a paperboard cup according to one embodiment of the invention by a method according to one embodiment of the invention,

Figure 7 shows a step winding the blank for making the container part spirally on the container shaped mandrel to form a spiral-wound container part, according to one embodiment of the invention,

Figure 8 shows one alternative for the spiral seam in section VII-VII from Figure 1.

DETAILED DESCRIPTION

The present invention relates to a method for manufacturing a conical paperboard container. Further, the present invention relates to a conical paperboard container, such as a drinking cup, having a hollow conical container part, having a circular cross- section narrowing from a circular mouth towards a bot tom portion having a smaller diameter than the mouth, and a base part. The container part is connectable to a base part from the bottom portion of the container part. Reference is made to Figures 1 to 8.

The paperboard cup 1 has a conical container part 2 with a side wall having a circular cross-section nar rowing from a mouth 6 towards a bottom portion 4. The mouth 6 forms an edge of an opening 7 from outside to a container space 15 of the container part 2. The bot tom portion 4 of the container part may have a smaller diameter than the mouth 6 of the container part. The bottom portion 4 may be formed as a tip of the cone. The conical container part 2 may be connected to a base part 3. The bottom portion 4 of the container part may be provided with a connecting part 41 for connecting the container portion 2 to a base part 3.

The container part 2 may be made as a monolithic structure of liquid packaging board having thermo plastic polymer layer on one side or both sides. The container part 2 may be a spiral-wound structure of a piece of planar curved longitudinal blank 5 cut from said liquid packaging board and the container part 2 having a spiral seam. The connecting part 41 may be formed in the bottom portion 4 of the container part and formed to extend from the bottom portion 4 for connecting the container part 2 to the base part 3.

The base part 3 may be formed as a conical form with a side wall having a circular cross-section. The base part 3 may comprise a lower portion 32 and an upper portion 31. The lower portion 32 of the base part 3 may have a larger diameter than the upper por tion 31. The base part 3 may have an opening in the upper portion 31. At least the connecting part 41 of the container part 2 may be arranged to extend through the opening of the upper portion 31 of the base part 3 to a counterpart 34 so that the base part 3 and the container part 2 form a combination that is the paper- board cup 1. In one embodiment of the invention the paper- board cup 1 may be configured for foodstuffs or drinks, especially for beverages. In one embodiment the combination of the conical paperboard container part and the base part may have a form similar to a champagne glass or a sparkling wine glass.

The counter part 34 may be fitted in a space formed between wall of the base part and the lower portion 32 and the upper portion 31 of the base part 3. The coun terpart 34 may be a wall with a circular form. The counterpart 34 may have support flaps 35 extending ra dially from the circular wall portion. The flaps 35 may be same piece i.e. monolithic with the circular wall. The flaps may be bendable by bending lines 38. The counterpart 34 may be connected to the wall of the base part 3. The counterpart 34 may be connected to an inner surface of the wall via flaps 35. The counter part 34 may be supported on the inner surface of the wall of the base part by the flaps 35. The flaps may be connected to the inner surface of the base part. The counterpart 34 may have a connecting point 36 for receiving the connecting part 41 of the container part 2. The connecting point 36 may be an aperture formed through the wall of the counterpart 34. The connecting point may be a cut, or several cuts, or an opening formed on the wall of the counterpart. The connecting part 41 of the container part 2 may extend through the connecting point 36 of the wall of the counterpart and connect the container part 2, counterpart 34 and base part 3 relative to each other.

In one embodiment of the invention the wall of the container part 2 may be supported on an edge of the opening 31 of the upper portion of the base part. In an embodiment of the invention a stiffening plate 33 may be arranged between counterpart 34 and the opening 31 of the upper portion of the base part.

The stiffening plate 33 may have an aperture 36 through the wall of the stiffening plate.

In an embodiment of the invention the axis of the con tainer part and the axis of the base part are coaxial. The connecting part 41 of the container part 2 may be arranged to extend through on opening of the upper portion 31 of the base part 3 and through an aperture

36 of the stiffening part 33 and the connecting point

37 of the counterpart 34 and lock the container part and base part relative to each other with help of the counterpart 34 and stiffening part 33.

The paperboard cup may be made of a liquid packaging board. In an embodiment of the invention the liquid packaging board may have a thermoplastic polymer coat ing on one side or on both sides. The paperboard cup 1 may be a spiral-wound structure of a piece of planar blank 5 cut from said liquid packaging board and wound so that the cup 1 has a spiral seam.

In the method, a piece of planar elongated blank 5 is cut from a liquid packaging board sheet or web. Refer ring to Figure 5, the blank 5 has a first end 8, a second end 9, a first curved longitudinal edge 10 and a second curved longitudinal edge 11. The blank 5 has a curved shape as shown in Figure 5.

The next step in the method is shown in Figures 7 and

8.

The second end 9 of the blank 5 is secured to a rotat able mandrel 12 having a rotation axis x and an outer shape corresponding to the shape of the container part 2 of the cup to be manufactured. The mandrel 12 is ro tated about its rotation axis x to wind the blank 5 spirally onto the mandrel 12, so that the first curved longitudinal edge 10 overlaps the second curved longi tudinal edge 11. At the same time while rotating the mandrel 12 heat-sealing energy, such as hot air, and pressure is applied onto the first curved longitudinal edge 10 to seal the first curved longitudinal edge 10 together with the second curved longitudinal edge 11 to form a sealed spiral seam 13 and to form a mono lithic shape of the container part 2 of the cup 1. Af ter the winding process is completed, the mandrel 12 is removed from inside the container part 2 of the cup 1. According to one embodiment a thermoplastic film or coating 14 may be arranged on the blank 5 so that the film or coating appear on the inner surface facing to a container space 15 of the container part 2.

In one embodiment of the method a cutting a mouth of the container part to be straight and even may be made before removing the mandrel 12 from inside the con tainer part 2.

In one embodiment of the method heat-sealing energy, such as hot air, and pressure may be applied to the bottom part 4 of the container part 2 to form a sealed container bottom and a connection part 41. A shape of the connection part 41 may vary according to embodi ments. The connection part may have solid structure that is monolithic with the container part 2.

The connecting of the container part 2 to base part 3 may be arranged to be made by a user or in the manu facturing phase or in a separate phase before the cup is delivered to the user.

In one embodiment, the method may further comprise steps for making the base part 3. Figures 6a, 6b and 6c illustrate one embodiment of blanks of parts for the base part 3. A piece of planar blank for the base part 3 may be cut from packaging board sheet or web. The blank may have a first end 3a, a second end 3b, a first curved edge 3c and a second curved edge 3d. The form of the base part may be made by securing the first end 3a of the blank for a base part to a ro tatable mandrel having a rotation axis and an outer shape corresponding to the shape of the base part to be manufactured. The mandrel may be rotated about its rotation axis to wind the blank for the base part spi rally onto the mandrel, so that the first curved edge 3c overlaps the second curved edge 3d. In one embodi ment by applying heat-sealing energy, such as hot air, and pressure, while rotating the mandrel, onto the first curved edge 3c to seal the first curved edge to gether with the second curved edge 3d to form a spiral seam and to form a monolithic shape of the base part 3. In one embodiment, the method may further comprise a step of cutting a lower edge 32 of the base part to be straight and even.

In one embodiment, the method may further comprise a step of folding an upper edge the base part 3 inwards with a tool.

In one embodiment, the method may further comprise a step of cutting a piece of planar counter part 34 having a centre portion and a connecting point 37 and flips 35 extending from the centre portion, from a packaging board sheet or web. In one embodi ment, optionally a disc-like stiffening part (33) hav ing a connecting point (36) may be also cut from a packaging board sheet or web.

In one embodiment, the method may further comprise a step of applying heat energy, such as hot air, and pressure to the counterpart 34 and the stiff ening part 33 for connecting them to each other.

In one embodiment, the method may further comprise a step of applying heat energy, such as hot air, and pressure to the flips 38 of counterpart 34 for connecting the counterpart, optionally with the stiffening part 33, to the inner surface of the base part 3.

In one embodiment, the method may further comprise a step of connecting the container part 2 to the base part 3 by inserting the connecting part 41 of the container part through an opening of the upper portion of the base part 3 and through an opening of the connecting point 37 so that the connecting part 41 and edges of the connecting point 37 lock each other.

In one embodiment, the method may further comprise a step of protecting exposed cut raw edge of the second curved longitudinal edge 11 against absorption of liq uid, before securing the first end to a mandrel.

In an embodiment of the method, the step of rotating includes overlapping the first curved longitudinal edge by the second curved longitudinal edge.

In an embodiment of the method, the step of applying heat-sealing energy and pressure may include sealing the second curved longitudinal edge together with the first curved longitudinal edge.

In an embodiment of the method, the method may further comprise a step of protecting exposed cut raw edge of the second curved longitudinal edge against absorption of liquid, before securing the first end to a mandrel. That may, for example, include a hemming of the second curved longitudinal edge of the blank to form a hemmed edge having an over-bent portion.

In an embodiment of the paperboard cup, the cut raw edge of the second curved longitudinal edge may be covered with a plastic foil or with an adhesive plas tic tape.

The liquid packaging board may be, for example, a mul tilayer structure comprising one or more layers made of bleached sulphate pulp. The liquid packaging board may comprise a top layer made of bleached sulphate pulp, a middle layer made of chemi-thermomechanical pulp CTMP, a back layer of made of bleached sulphate pulp and a polyethylene PE layer on the outer side of the top layer and/or the back layer. As the liquid packaging board can be used e.g. products of the Finn ish company Stora Enso marketed with trademarks Natur- a™ 2PE Board or Natura™ Barr. Natura™ 2PE Board is a bleached liquid packaging board with a three-layer fi bre construction, with two outer layers made of bleached sulphate pulp and a middle layer made of CTMP (chemi-thermo-mechanical pulp). Its top and reverse sides are polyethylene PE coated. Natura™ Barr is a bleached liquid packaging board with a three-layer fi bre construction, with two outer layers made of bleached sulphate pulp and a middle layer made of CTMP (chemi-thermo-mechanical pulp). It has a polyethylene PE coating on the top side and a multilayer high- barrier coating on the reverse side.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.