Method

Abstract

A method of manufacture of a fibre-based packaging container, such as a drinking cup. The step a provides quadrilateral blank comprising inner and outer wall surfaces, the inner wall surface having a

Description

The present invention relates to improved methods of producing paperboard containers, such as a disposable cups. More specifically, the present invention relates to methods of producing paperboard containers comprising recyclable and / or compostable coatings and adhesives, preferably using conventional container manufacturing machines. BACKGROUND OF THE INVENTION Historically, disposable beverage cups and drinking containers typically were formed of fibrebased board comprising a layer of polyethylene or other polymeric materials to provide a liquid barrier. However, more recently, the use of polyethylene and certain other polymers has been banned in many countries as the environmental impact of polymeric waste is of serious concern. Therefore, there has been a significant move in the disposable packaging industry towards manufacturing containers using ‘next generation’ alternative, more environmentally friendly materials. During the manufacture of drinking containers, a thin liquid barrier layer is applied to a surface of the fibre-based material before the coated material is spooled into reels. The liquid barrier coating may be organic (for example, polymers or monomers other than those identified as being of environmental concern e.g. polyethylene) or inorganic (for example, comprising mineral materials such as silica) or a mix of both. The reels are printed to apply any required outer decoration and are then carefully machine cut into accurately measured cup sidewall blanks. The blanks are inserted into cup-forming machines that wrap the sidewall blanks into a cup shape and seal them. The cup bottom is subsequently added and heat-sealed in place. The seams of the cups are sealed to make the cups liquid proof. In some cases, folding or crimping of the seam between the wall and base takes place to further strengthen the form of the cup. The portions of the sidewall blanks and cup bases which are sealed to themselves or each other may comprise a sealable lacquer coating to permit a reliable seal to be formed. Such processes are based on and largely replicate processes for manufacturing cups having polyethylene barrier coatings applied thereto. However, many of the more environmentally friendly liquid barrier materials have different properties to polyethylene meaning that machines configured for use with polyethylene coated substrates may perform sub-optimally or produce sub-optimal containers when substrates comprising different liquid barrier materials are used, for example cracking of the coating when the coated substrate is folded or curled, thus reducing liquid barrier function. Additionally, unlike polyethylene, certain next generation liquid barrier materials may not be inherently sealable (e.g. thermosealable) and thus, as mentioned above, a sealable lacquer coating may also need to be used to ensure that a sufficiently durable seal is formed between the components of the containers. A further issue with using machinery developed for use with polyethylene-coated substrates is that many sealable lacquers have a narrower activation window than polyethylene, i.e. a temperature range in which the lacquer must be maintained in order for it to be sealable without damaging the lacquer, resulting in a need to form seals more rapidly once the activation temperature is attained or risk weaker seals being formed. There is therefore a need for optimisation of machinery used conventionally to form containers from polyethylene-coated substrates to permit their effective use with substrates coated with environmentally friendly, ‘next generation’ liquid barrier coatings and sealable lacquers. SUMMARY OF THE INVENTION The present invention seeks to address the problems of the prior art. Aspects of the present invention are set out in the attached claims. According to an aspect of the present invention, there is provided a method of manufacture of a fibre-based packaging container, wherein the method comprises the steps of: a. providing a quadrilateral blank comprising an inner wall surface and an outer wall surface opposing the inner wall surface, the inner wall surface comprising a liquid impermeable layer, the quadrilateral blank further comprising a first edge and second edge opposing the first edge, wherein the first and second edges are linear, and a third edge and a fourth edge opposing the third edge, each of the third and fourth edges defining an arc, wherein a first edge sealing portion extends partially across the inner wall surface from the first edge and a second edge sealing portion extends partially across the outer wall surface from the second edge, and wherein a base sealing portion extends partially across the inner wall surface adjacent the third edge; b. providing a circular base component having an outer edge, an inner base surface and an outer base surface opposing the inner base surface, the inner base surface having a liquid impermeable layer and comprising a wall sealing portion; c. flexing the quadrilateral blank to bring the first and second edges into overlapped engagement with one another, and sealing them to one another to form a tubular wall component with a wall seam, the tubular wall component having an interior, an exterior, an upper end and a lower end at which the base sealing portion is located; d. folding the circular base component at a fold line around the whole of the circular base component to create a circumferentially folded edge extending at 80 to 100 degrees from the rest of the circular base component wherein the circumferentially folded edge comprises the wall sealing portion, and the circumferentially folded edge and the outer base surface define a base interior; e. sealing the wall sealing portion and the base sealing portion to one another to form a base seam between the tubular wall component and the circular base component; wherein 1) prior to step e., hot air is flowed to heat the base sealing portion and I or the wall sealing portion, wherein the base sealing portion and I or the circumferentially folded edge region are positioned within a heat conservation zone prior to creation of the base seal; 2) prior to or during step e., hot air is flowed into the base interior or the interior of the lower end of tubular wall component, wherein a baffle member is positioned around the exterior of the lower end of the tubular wall component which directs hot air escaping the base interior or the interior of the lower end of tubular wall component to the exterior of the lower end of the tubular wall component; and I or 3) the base seal is formed in step e. by positioning the lower end of the tubular wall component in a counterplate exterior of the tubular wall component, the counterplate having a surface extending circumferentially around the exterior of the lower end of the tubular wall component, and applying mechanical pressure to the wall sealing portion, the base sealing portion and the surface of the counterplate from the base interior using a knurling member, wherein the part of the knurling member which applies the mechanical pressure and / orthe surface of the counterplate comprises a resilient material. Those skilled in the art will be familiar with apparatus used to produce fibre-based packaging containers and will recognise that steps a. to e. as detailed above are typically performed using such apparatus. However, the inventors have identified difficulties when utilising such apparatus to form containers from blanks and bases provided with liquid impermeable layers having a low degree of elasticity (or at least a lower degree of elasticity than polyethylene). A further issue with certain ‘next generation’ liquid impermeable layer materials is that, if inherently sealable, the activation windows of these sealable liquid impermeable layers are typically narrower than for polyethylene. Alternatively, a number of ‘next generation’ liquid impermeable layers do not exhibit sufficient inherent sealability to form seals between components of the containers of acceptable strength even if activated, e.g. by heat. Thus, sealable lacquers may be employed to enhance seal strength and the inventors have identified that the activation windows of these lacquers are also typically narrower than for polyethylene. Thus, in embodiments of the invention, one or both of the base sealing portion and the wall sealing portion comprise a sealable lacquer coating and the sealable lacquer coating is present within the base seam. As those skilled in the art will be aware, ‘activation window’ is a term used to describe a temperature range within which a material, e.g. sealable lacquer coating will be sealable without being heated excessively so as to cause damage to the material or reduced sealing function. The term ‘activation temperature’ is used to define a temperature within that range at which a a sealable material, e.g. an inherently sealable impermeable liquid barrier or a sealable lacquer coating will be activated, i.e. sealable. Determining the activation window is a routine matter for the skilled person; such information will either be provided by the manufacturer of the material in question or can be easily determined using conventional testing methodologies. The process optimisations of the present invention advantageously permit conventional container-forming apparatus, configured for use with substrates coated with polyethylene, to be modified in a straightforward manner to permit their use with substrates provided with a broader range of liquid impermeable layer materials and optionally sealable lacquers. For the avoidance of doubt, the present invention is not limited to processes in which steps a. to e. are conducted in the order in which they are presented herein. For example, step d. could be performed prior to or simultaneously with step c. Additionally or alternatively, step c. could be performed prior to or simultaneously with step b. In one embodiment, prior to and I or during step e. of the process of the invention, hot air is flowed (e.g. in a heating step as discussed herein in more detail) to heat the base sealing portion and I or the wall sealing portion, wherein the base sealing portion and I or the wall sealing portion are positioned within a heat conservation zone prior to creation of the base seal. In these embodiments, the base sealing portion and I or the wall sealing portion may be heated to an activation temperature of the liquid impermeable layer or sealable lacquer coating. Additionally or alternatively, the temperature within the heat conservation zone may be an activation temperature of the liquid impermeable layer or sealable lacquer coating. In such embodiments, priorto heating the base sealing portion and / orthe wall sealing portion, the folded circular base component prepared in step d. may be positioned in the interior of the tubular wall component at its lower end, e.g. such that the wall sealing portion of the circular base component and the base sealing portion of the tubular wall component are adjacent to each other, e.g. those portions are facing each other and I or abutting each other. The tubular wall component and I or the circular base component may be retained in place, e.g. on a mandrel. In some embodiments, the heat conservation zone extends from an upstream forming station (e.g. the station at which step c. of the process is performed, the station at which step d. of the process is performed, a heating station, a station in which the circular base component is positioned in the lower end of the tubular wall component and I or the station in which the base sealing portion is folded around the circumferentially folded edge region) to the station in which sealing step e. is performed and the tubular wall component and circular base component are passed through the heat conservation zone from the upstream forming station to the station in which sealing step e. is performed. In the manufacture of containers from polyethylene coated substrates, the polyethylene coating is typically heated to a temperature within the activation window and then the container components are moved to a sealing station for sealing. The inventors have identified that, owing to the narrower activation window of certain ‘next generation’ liquid impermeable layers or sealable lacquers (particularly those which are environmentally friendly), if substrates comprising such materials are processed in the same way, then even if heated to a temperature within the activation window, by the time the container components have been moved to the sealing station, the liquid impermeable layer / lacquer temperature may drop out of the activation window, resulting in inferior seal quality. By locating and maintaining the base sealing portion and I or the wall sealing portion in the heat conservation zone, the liquid impermeable layer I sealable lacquer coating can be maintained within the activation window for a sufficient duration to permit the container components to be moved to the sealing station for the performance of step e., thus facilitating the use of liquid impermeable layers I sealable lacquers having narrower activation windows than polyethylene to form the base seam seal between the tubular wall component and the circular base component. In some embodiments, the heat conservation zone may comprise a channel defined by one or more (e.g. 2) side walls and a base wall. The tubular wall component and circular base component may be passed along the channel to the station at which step e. is performed. The channel may be curved or linear. The width of the channel may be sized to accommodate components of the container being passed through it. In embodiments of the invention, the width of the channel is about 35mm to about 110mm, about 40mm to about 80mm or about 45mm to about 70mm. Additionally or alternatively, the width of the channel may be about 5mm to about 20mm greater than the diameter of the circular base component. The height of the channel may be lower than the height of the tubular wall component. In some embodiments, the height of the channel may be about 20mm to about 200mm, about 25 to about 150mm, about 30mm to about 100mm, or about 35mm to about 80mm. The temperature within the heat conservation zone may be an activation temperature of the liquid impermeable layer or sealable lacquer coating comprised on the wall sealing portion and I or the base sealing portion. In some embodiments, the heat conservation zone may be fed with hot air to maintain an elevated temperature. In such embodiments, the hot air may be vent air from upstream or downstream heating steps which is recycled and fed into the heat conservation zone. Thus, in some embodiments, the heat conservation zone may be provided with one or more hot air inlets to receive hot air. The hot air may be directed by the heat conservation zone from the hot air inlet / s into the channel via openings in the side wall / s and / or base. According to a further aspect of the present invention, there is provided a heat conservation zone comprising a channel defined by a base wall and one or more side walls comprising one or more hot air inlets in fluid communication with openings in the base wall and I or the one or more side walls. The heat conservation zone of this aspect of the invention may comprise any of the features of the heat conservation zone discussed herein in connection with other aspects of the invention, and vice versa. For example, the channel may have a width of about 35mm to about 110mm and I or be curved. According to a further aspect of the invention, there is provided a container forming machine comprising a heat conservation zone as discussed herein. The container forming machine may additionally comprise one or more of the following stations: a wall seam forming station, a heating station, a base folding station and a base seam forming station. In some embodiments, prior to and I or during step e., hot air may be flowed (e.g. in a heating step, as discussed herein in more detail) into the base interior or the interior of the lower end of tubular wall component and a baffle member positioned around the lower end of the tubular wall component which directs hot air escaping the base interior or the or the interior of the lower end of tubular wall component to the exterior of the lower end of the tubular wall component thus advantageously heating the base sealing portion and I or the wall sealing portion from both the interior and the exterior of the tubular wall component. Those skilled in the art will recognise that base seams between tubular wall components and circular base components having polyethylene layers applied thereon may conventionally be formed by heating the polyethylene layers using hot air directed into the base interior of those containers. However, the inventors have now identified that, owing to the narrower activation window of certain liquid impermeable layers and sealable lacquers, it is advantageous to ensure that hot air fed to the base interior or the interior of the lower end of tubular wall component of a container is directed to flow around the exterior of the lower end of the container as well, to ensure heating from the interior and exterior of the container, rather than simply being allowed to dissipate. This direction of the flow of hot air is achieved using a baffle member. In such embodiments, prior to flowing hot air into the base interior or the interior of the lower end of tubular wall component, the circular base component may be positioned in the interior of the tubular wall component at its lower end, e.g. such that the wall sealing portion of the circular base component and the base sealing portion of the tubular wall component are adjacent to each other, e.g. those portions are facing each other and I or abutting each other. Additionally or alternatively, in such embodiments, prior to flowing hot air into the base interior or the interior of the lower end of tubular wall component, the base sealing portion may be folded around the circumferentially folded edge region. When the baffle member is positioned around the lower end of the tubular wall component, the tubular wall component and I or the circular base component may be retained in place, e.g. on a mandrel. In embodiments, the baffle member surrounds the lower end of the tubular wall component. The baffle member may be cylindrical, i.e. it may comprise a cylindrical wall. The diameter of the cylindrical wall of the baffle member may be about about 35mm to about 110mm, about 40mm to about 80mm or about 45mm to about 70mm. The baffle member may be selected such that it is sized to closely fit the size of the container being produced. Thus, in embodiments, the diameter of the cylindrical wall of the baffle member may be about 50mm or lower, about 40mm or lower, about 30mm or lower, about 20mm or lower or about 10mm or lower than the diameter of the tubular wall component at its lower end. The baffle member may be stationary and the lower end of the tubular wall component and the circular base component may be inserted into the baffle member. Alternatively, for this step at least, the lower end of the tubular wall component and the circular base component may be stationary and the baffle member may be moved into position to surround the lower end of the tubular wall component. The baffle member may be formed of any material provided that is heat resistant. In certain embodiments, the baffle member may be formed of metal and I or ceramic. The baffle member may be connected to or formed integrally with means to direct hot air into the base of the container. Those skilled in the art will be familiar with such means, which include a cylindrical cap into which hot air is fed, the cylindrical cap comprising openings therein to direct the flow of hot air to specific locations in the container base, e.g. the wall sealing portion and I or the base sealing portion. An example of such means is depicted in Figure 3. According to a further aspect of the present invention, there is provided a cylindrical baffle member comprising means to direct hot air into the base of a container, the baffle member comprising a cylindrical wall having an upper end and a lower end mounted on a base, wherein the means to direct hot air into the base of the container are located within the cylindrical baffle member. The baffle member of this aspect of the invention may comprise any of the features of the baffle member discussed herein in connection with other aspects of the invention, and vice versa. The means to direct hot air into the base of a container may comprise a cylindrical wall having an upper end which is closed by an upper wall and a lower end which is mounted on the base, the cylindrical wall of the means to direct hot air into the base of a container further comprising openings in the cylindrical wall and I or the upper wall. The base and I or lower end of the cylindrical wall may be provided with connection means or an inlet to permit the flow of hot air into the interior of the cylindrical wall of the means to direct hot air into the base of a container. In embodiments, the means to direct hot air into the base of a container is located within the cylindrical wall of the baffle member and the cylindrical wall has a diameter greater than the cylindrical wall of the means to direct hot air into the base of the container. For example, the diameter of the cylindrical wall of the baffle member may be about 5mm to about 50mm greater than the diameter of the cylindrical wall of the means to direct hot air into the base of the container, or about 10 to about 30mm greater. The diameter of the cylindrical wall of the baffle member may be about about 35mm to about 110mm, about 40mm to about 80mm or about 45mm to about 70mm. According to a further aspect of the invention, there is provided a container forming machine comprising a baffle member as discussed herein. The container forming machine may additionally comprise one or more of the following stations: a wall seam forming station, a heating station, a base folding station and a base seam forming station. In some embodiments of the invention, the base seal is formed in step e. by positioning the lower end of the tubular wall component in a counterplate exterior of the tubular wall component, the counterplate having a surface extending circumferentially around the exterior of the lower end of the tubular wall component, and applying mechanical pressure to the wall sealing portion, the base sealing portion and the surface of the counterplate from the base interior using a knurling member, wherein the part of the knurling member which applies the mechanical pressure and I or the surface of the counterplate (e.g. an operational surface) comprises a resilient material. Those skilled in the art will be familiar with the use of counterplates and knurling members to form base seam seals in the production of containers. In embodiments, the counterplate has a thickness corresponding generally to the radial length of the wall sealing portion of the circular base component. Further, the counterplate may be provided with an opening into which the lower end of the tubular wall component is inserted. In such embodiments, the opening is shaped to correspond to the exterior surface of lower end of the tubular component and the surface of the counterplate is provided by the edge of that opening. The knurling member may be shaped to correspond to the profile of the base interior. In some embodiments, the diameter of the knurling member may be smaller than the diameter of the outer base surface of the circular base component defining the base interior. To form the base seam, the knurling member may be rotated within the base interior to apply mechanical pressure to the wall sealing portion, the base sealing portion and the surface of the counterplate. In some embodiments, the rotation of the knurling member may be erratic. In embodiments, the resilient material may be provided on a portion of the surface of the counterplate. Such embodiments may be preferable where a location on the tubular wall component susceptible to crushing or cracking during knurling operations has been identified. In some embodiments, the resilient material may be provided on the entirety of the surface of the counterplate. Additionally or alternatively, the resilient material may be provided on the part of the knurling member which applies mechanical pressure to the wall sealing portion and the base sealing portion (e.g. an operational surface). In some embodiments, the resilient material may be provided in a continuous form around the knurling member, optionally around its operational surface, e.g. in the form of a band or ring (for example an O-ring). In certain embodiments, multiple continuous sections (e.g. multiple bands or rings (for example O-rings) may be provided on the knurling member, e.g. around its operational surface. In embodiments, the knurling member may be shaped to accommodate the resilient material. For example, in embodiments in which the knurling member comprises the resilient material in the form of one or more continuous sections, the knurling member may be provided with one or more grooves or channels into which the continuous section / s of resilient material can be inlaid and I or seated. Through the provision of resilient material on the surface of the counterplate and I or the knurling member, this permits the effective creation of a base seam seal between the tubular wall component and the circular base component of the container without resulting in damage or a loss of integrity to the liquid barrier layer applied to those components even if the liquid barrier layer has a low degree of elasticity Any resilient material may be employed in the process of the invention provided that it has sufficient hardness to result in the effective formation of the base seam, but also sufficient resilience to permit that seam to be formed without resulting in unacceptable damage to the liquid impermeable layer. Exemplary materials identified by the inventors which may be utilised as the resilient material include silicone rubber and polytetrafluoroethylene (PTFE). Additionally or alternatively, the resilient material may have a Shore A hardness ranging from about 10 to about 500, about 20 to about 300, about 30 to about 200 or about 50 to about 100. Shore A hardness may be measured in accordance with the ASTM D-2240 parameters and methodology. In some embodiments, the resilient material may be transparent or translucent. Additionally or alternatively, the resilient material may be coloured (e.g. it may be white coloured) to match the colour of the exterior surfaces of the container. The knurling member and I or the counterplate may be formed of metal. According to a further aspect of the invention, there is provided a knurling member comprising body having an operational surface, the operational surface of the knurling member comprising resilient material. The knurling member of this aspect of the invention may comprise any of the features of the knurling member discussed herein in connection with other aspects of the invention, and vice versa. In some embodiments, the knurling member may be cylindrical comprising upper circular surface, a lower circular surface and a wall connecting the upper and lower surfaces, wherein the operational surface is comprised on the wall. The wall of the knurling member be be cylindrical or the walls may be tapered to define a conical (e.g. a truncated cone) shape. In such embodiments, the diameter of the cylindrical wall of the knurling member may be about 30mm to about 100mm, about 40mm to about 80mm or about 45mm to about 70mm. The knurling member is preferably solid and / or may be formed of metal. According to a further aspect of the invention, there is provided a container forming machine comprising a knurling member as discussed herein. The container forming machine may additionally comprise one or more of the following stations: a wall seam forming station, a heating station, a base folding station and a base seam forming station. According a still further aspect of the invention, there is provided a counterplate which is substantially planar and has a thickness and comprises a circular opening therein, the edge of the circular opening defining a surface, wherein the surface comprises a resilient material. The counterplate of this aspect of the invention may comprise any of the features of the counterplate discussed herein in connection with other aspects of the invention, and vice versa. The surface of the counterplate may define a cylindrical shape or a truncated conical shape. The surface of the counterplate has a height corresponding to the thickness of the counterplate. The diameter of the opening in the counterplate may be about 30mm to about 100mm, about 40mm to about 80mm or about 45mm to about 70mm. The counterplate may be circular. According to a further aspect of the invention, there is provided a container forming machine comprising a counterplate as discussed herein. The container forming machine may additionally comprise one or more of the following stations: a wall seam forming station, a heating station, a base folding station and a base seam forming station. Steps a. to e. of the process of the invention may be carried out by the same container-forming machine. Alternatively, certain of steps a. to e. may be carried out on a first machine and the remaining steps may be carried out on one or more different machines. For example, the quadrilateral blank provided in step a. may be formed by cutting the blank out of a web. The circular base component may also be provided in step b. by cutting the circular base component out of a web. The machine used to cut the quadrilateral blank out of the web may be the same or different to the machine used to cut the circular base component out of the web. Further, steps c. to e. may be carried out using a conventional container forming machine, which may be the same or different machine as that or those used to cut the quadrilateral blank and / or the circular base component out of their respective webs. Where multiple steps are performed using the same machine, these may be performed at different stations within the same machine. As the process progresses, the components of the container may be moved by the machine from one station to another, e.g. by a conveyor such as a rotary conveyor, conveyor belt or the like. In step a., a quadrilateral blank is provided comprising an inner wall surface and an outer wall surface opposing the inner wall surface, the inner wall surface comprising a liquid impermeable layer. The quadrilateral blank further comprises a first edge and second edge opposing the first edge, wherein the first and second edges are linear, and a third edge and a fourth edge opposing the third edge, each of the third and fourth edges defining an arc. The quadrilateral blank also comprises a first edge sealing portion extending partially across the inner wall surface from the first edge and a second edge sealing portion extending partially across the outer wall surface from the second edge. A base sealing portion is also present which extends partially across the inner wall surface adjacent the third edge. In embodiments, the first and second edges of the quadrilateral wall blank are equal in length to one another. As those skilled in the art will recognise, the use of quadrilateral wall blanks to produce containers is well known, including those in which notches or other portions are cut out in order to facilitate manufacture of the container. For the avoidance of doubt, where reference is made herein to the first and second edges of the quadrilateral wall blank being equal in length to one another, the length of the edge in question should be measured not taking into account the effect of such notches or other cut out portions on the length of the edge, i.e. as if no notches or cut out portions were present. In embodiments, one or both of the first and second edge sealing portions of the quadrilateral blank may comprise a sealable lacquer coating. Additionally or alternatively, the base sealing portion may comprise a sealable lacquer coating The use of quadrilateral blanks to form the walls of containers, e.g. cups, will be familiar to the skilled person. The provision of such blanks may be achieved in processes of the invention by providing a web of fibre-based material and cutting the blank out therefrom, e.g. by diecutting. In embodiments, prior to the quadrilateral blank being cut from the web, the web may comprise the liquid impermeable layer. Alternatively, the liquid impermeable layer may be applied to the blank after being cut from the web. In embodiments in which the base sealing portion and / or the first and / or the second edge sealing portion comprises a sealable lacquer coating, this may be comprised on the web before the quadrilateral blank is cut therefrom. Alternatively, the sealable lacquer coating may be applied to the blank after being cut from the web. Step a. may be carried out in a container-forming machine, e.g. at a sidewall blank cutting station in such a machine. Alternatively, step a. may be carried out using a cutting machine and the quadrilateral blanks obtained therefrom are moved to a container-forming machine which carries out some or all of steps c. to e. In some embodiments, step a. may be performed by sourcing pre-cut quadrilateral wall blanks. In step b., a circular base component is provided comprising an outer edge, an inner base surface and an outer base surface opposing the inner base surface, the inner base surface comprising a liquid impermeable layer and a wall sealing portion. The wall sealing portion may be provided with a sealable lacquer coating. The use of circular base components to form the base of containers, e.g. cups, will be familiar to the skilled person. The provision of such components may be achieved in processes of the invention by providing a web of fibre-based material and cutting the circular base component out therefrom, e.g. by die-cutting. In embodiments, prior to the circular base component being cut from the web, the web may comprise the liquid impermeable layer. Alternatively, the liquid impermeable layer may be applied to the circular base component after it is cut from the web. In embodiments in which the wall sealing portion comprises a sealable lacquer coating, this may be comprised on the web before the circular base component is cut therefrom. Alternatively, the sealable lacquer coating may be applied to the circular base component after it is cut from the web. Step b. may be carried out in a container-forming machine, e.g. at a circular base component cutting station within the machine. Alternatively, step b. may be carried out using a cutting machine and the circular base components obtained therefrom are moved to a containerforming machine which carries out some or all of steps c. to e. In some embodiments, step b. may be performed by sourcing pre-cut circular base components. Step b. may be carried out using the same or different machine than step a. Where steps a. and b. are performed using the same machine, they may be performed at different stations within that machine. In step c., a tubular wall component is formed by flexing the quadrilateral blank to bring the first and second edges into overlapped engagement with one another, and sealing them to one another to form a tubular wall component with a wall seam. The tubular wall component has an interior, an exterior, an upper end and a lower end at which the base sealing portion is located. The quadrilateral blank may be flexed around a mandrel shaped to correspond to the interior of the container. One or both of the first and second edge sealing portions of the quadrilateral blank may comprise a sealable lacquer coating. The wall seam may be formed by applying energy (e.g. mechanical, thermal and I or ultrasonic energy) to the first and second edge sealing portions to seal them together thus forming the wall seam. Step c. may be perfomed in a wall seam forming station in a container forming machine. The tubular wall component formed in step c. may then be moved (e.g. from one station in a container-forming machine to another, or from one machine to another) in order for the subsequent steps of the process of the present invention to be carried out. In step d., the circular base component is folded at a fold line extending around the whole of the base component blank to create a circumferentially folded edge extending generally perpendicularly from the rest of the circular base component. By “generally perpendicularly” it is meant that the wall sealing portion is folded about the fold line by about 80° to about 100°, about 85° to about 95°, or about 90° from the plane of the circular base component. The fold line may or may not be marked and I or visible prior to folding of the wall sealing portion. In some embodiments, the fold line may be scored or marked to facilitate reliable and repeatable positioning of the fold. Folding of the edge of the circular base component may be achieved using any techniques or apparatus known to those of skill in the art. Step d. may be performed at a folding station which may be part of the same machine in which steps c. and I or e. are performed in. Alternatively, step d. may be performed in a different machine to steps c. and I or e. In some embodiments the circular base component may be positioned on a circular, planar mandrel having a smaller diameter than the circular base component (e.g. such that the circumference of the mandrel corresponds to the fold line) such that the edge of the circular base component and the wall sealing portion extend beyond the edge of the mandrel. The circular base component may then be passed through a cylindrical sleeve having a diameter greater than the diameter of the mandrel but smaller than the diameter of the circular base component (or the cylindrical sleeve may be passed over the circular base component and mandrel) which causes folding of the edge of the circular base component to form the circumferentially folded edge. Once step d. has been completed, the folded circular base component may then be moved (e.g. from the folding station to another, or from one machine to another) in order for the subsequent steps of the process of the present invention to be carried out. Prior to step e., the folded circular base component may be positioned within the interior of the tubular wall component at its lower end, e.g. such that the wall sealing portion of the circular base component and the base sealing portion of the tubular wall component are adjacent to each other, e.g. those portions are facing each other and I or abutting each other. The step of positioning the folded circular base component within the interior of the tubular wall component at its lower end may be conducted in a station within the container forming apparatus. Positioning of the circular base component within the lower end of the tubular wall component can be achieved by the circular base component being retained on the mandrel after step d. and the mandrel being moved into the base of the tubular wall component to position the folded circular base component therein. Once the folded circular base component has been moved into the interior of the tubular wall component at its lower end, sealing step e. may be performed. Alternatively, a heating step may then be performed, prior to step e. Alternatively, an additional folding step may be performed in which the base sealing portion of the tubular wall component is folded around the circumferentially folded edge region of the circular base component. In such embodiments, both the inner base surface and the outer base surface of the circular base component may comprise wall sealing portions, one or both of which may be provided with a sealable lacquer coating. In embodiments in which the outer base surface comprises a wall sealing portion comprising a sealable lacquer coating, the weight of the sealable lacquer coating provided in the wall sealing portion may be greater than the weight of the sealable lacquer coating provided in the wall sealing portion of the inner base surface. Folding of the base sealing portion of the tubular wall component around the circumferentially folded edge region of the circular base component may be achieved using means known to a person skilled in the art, e.g. a base folding station. In embodiments, the base folding station may comprise a metal plate (e.g. one having a curved circumferential shape) which is moved toward the base of the tubular wall component, forcing at least a portion of the base sealing portion into the base interior. In embodiments of the invention, the process of the invention includes the step of heating the base sealing portion and I or the wall sealing portion, e.g. using heated air which may be directed into the base interior or the interior of the lower end of tubular wall component. This heating step may be performed as part of step e. or prior to that step. In some embodiments, the heating step may be performed prior to step e. and then a further heating step may be performed as part of step e. The heating step may be performed at a heating station and the tubular wall component and I or circular base component moved to a sealing station for the performance of step e. Alternatively, the heating step and the sealing step may be performed at the same station. The heating step may be performed prior to step e. to facilitate folding of the base sealing portion and I or to prepare the container components (e.g. to enable the liquid impermeable layer or sealable lacquer coating to attain the activation temperature) for sealing step e. In embodiments, the base sealing portion and I or the wall sealing portion may be heated to the activation temperature of the liquid impermeable layer or sealable lacquer coating. In certain embodiments, the process of the invention may comprise multiple heating steps, e.g. one prior to step e. and one during step e. In step e., the wall sealing portion and the base sealing portion are sealed to one another to form a base seam between the tubular wall component and the circular blank. One or both of the base sealing portion of the tubular wall component and the wall sealing portion of the circular base component may comprise a sealable lacquer coating and the sealable lacquer coating is present within the base seam. During step e., the tubular wall component and I or the circular base component may be retained in position, e.g. on a mandrel. Step e. may be performed in a base sealing station. In some embodiments, the base sealing portion comprises a sealable lacquer coating. In alternative embodiments, the wall sealing portion comprises a sealable lacquer coating. In certain embodiments, both the base sealing portion and the wall sealing portion comprise a sealable lacquer coating. The base seam may be formed by applying energy (e.g. mechanical, thermal and I or ultrasonic energy) to the base sealing portion and the wall sealing portion to seal them together forming the base seam. In certain embodiments, the base seam may be formed through the application of thermal and mechanical energy. For example, thermal energy may be applied via a heating step, e.g. in the form of hot air directed into the base interior or the interior of the lower end of tubular wall component and mechanical energy may be applied using a knurling member e.g. by rotating such a member within the base interior to apply mechanical pressure to the base sealing portion and the wall sealing portion. In embodiments, a mandrel is positioned in the interior of the tubular wall component prior to and I or during step e. to retain the tubular wall component in position during the sealing step and I or positioning of the circular base component in the lower end of the tubular wall component and I or folding of the base sealing portion of the tubular wall component around the circumferentially folded edge region of the circular base component. The process of the invention may additionally comprise the step of rolling the fourth edqe of the quadrilateral blank or the upper edge of the tubular wall component, e.g. to provide a more comfortable rim for the user when drinking from the cup. This step maybe performed in a rimforming station in a machine. The skilled artisan will be familiar with techniques for forming rolled rims in containers. Typically, this step is carried out in a rim forming station and as part of the process a lubricant such as paraffin oil is applied to facilitate rim curling I forming. The inventors have advantageously found, however, that by applying liquid impermeable barrier material instead of the lubricant, the liquid impermeable barrier material functions effectively as a lubricant but, once dried, functions as a barrier to provide additional resistance to moisture penetration. Thus, in embodiments of the invention, lubricant (other than the liquid impermeable barrier material) may not be applied during the step of rolling the fourth edge of the quadrilateral blank or the upper edge of the tubular wall component to form a rolled rim. In certain embodiments, liquid impermeable barrier material may be applied to a portion of the inner wall surface or the outer wall surface extending from the fourth edge of the quadrilateral blank or the upper edge of the tubular wall component prior to or during the step of rolling that edge to form a rolled rim. The inner wall surface and I or the inner base surface may comprise a liquid impermeable layer on the entirety or at least substantially all of the entirety of that surface I those surfaces. The liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may be polymeric and I or monomeric. In certain embodiments, the polymer and I or monomer is of natural origin, i.e. the polymer and I or monomer is produced by organisms (e.g. microorganisms, plants or animals) which are optionally not genetically modified. For example, the liquid impermeable layer may comprise micro or nano cellulose, polyhydroxybutyrate (PHB), polyhydroxyalkanoate (PHA), vegetable origin protein, vegetable origin polysaccharide, fatty acid such as stearic acid or mixtures thereof. In embodiments of the invention, the liquid impermeable layer does not comprise polyethylene. Additionally or alternatively, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may be inorganic, for example it may be a mineral liquid impermeable layer, e.g. it may comprise mineral materials such as silica, silica-based materials (e.g. ceramic), calcium carbonate, and / or kaolin. Examples of materials which may be used to provide mineral liquid impermeable layers include those listed in International Patent Publication Nos. WO2022 / 171893, WO2023 / 285499, WO2022 / 112566 and WO2021 / 019220. In preferred embodiments of the invention, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface is biodegradable. In some embodiments, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface comprises a monomer and / ora polymer which is biodegradable. The liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may be metallic, e.g. it may contain metallic particles or a metallic film. However, given that the inclusion of metals will adversely affect the recyclability of the container to which it is applied as well as requiring the use of mined metals which adds to the carbon footprint of the container, the use of metals in the liquid impermeable layer is preferably avoided. Accordingly, in some embodiments, the liquid impermeable layer comprised on the inner wall surface is free of metallic film. In embodiments, the liquid impermeable layer comprised on the inner wall surface is free of metallic particles. In some embodiments, the liquid impermeable layer comprised on the inner base surface is free of metallic film. In certain embodiments, the liquid impermeable layer comprised on the inner base surface is free of metallic particles. In preferred embodiments of the invention, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface is recyclable. In some embodiments, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface comprises a monomer and / or a polymer which is recyclable. The liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may be less elastic than polyethylene. LDPE (low density polyethylene), which has conventionally been used to provide a liquid impermeable layer to fibre based containers such as paper cups has a modulus of elasticity of 0.13 to 0.30 GPa. Thus, in embodiments of the invention, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may have a modulus of elasticity equal to or greater than about 0.3 GPa, equal to or greater than about 0.5 GPa, equal to or greater than about 1 GPa, equal to or greater than about 5 GPa or equal to or greater than about 10 GPa. In some embodiments, the modulus of elasticity of the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may have a modulus of elasticity of about 1 GPa to about 1000 GPa, about 5 GPa to about 500 GPa or about 10 to about 100 GPa. Where reference is made to quantified modulus of elasticity values herein, these are calculated in accordance with ASTM D638 - Standard Test Method for Tensile Properties of Plastics. In embodiments, the liquid impermeable layer comprised on the inner wall surface and the inner base surface is the same. In alternative embodiments, the liquid impermeable layer comprised on the inner wall surface and the inner base surface is different. As discussed below, whether the liquid impermeable layer comprised on the inner wall surface and the inner base surface is the same or different, a sealable lacquer coating may be comprised on the sealing portions of those surfaces. The liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may have any thickness provided that it provides effective liquid barrier properties. The effective thickness of the layer will depend, to a certain extent, on the material used to form the layer. However, in embodiments of the invention, the thickness of the liquid impermeable layer comprised on the inner wall surface and / or the inner base surface may be from about 1 to about 100 pm, about 5 to about 50 pm, about 10 to about 25 pm or about 12 to 20 pm. Additionally or alternatively, the liquid impermeable layer may have a weight of from about 1 to about 20 g / m2, about 2 to about 12 g / m2 or about 3 to about 8 g / m2. In some embodiments, the weight / thickness of the liquid impermeable layer applied to the inner wall surface may be greater than that applied to the inner base surface. In certain embodiments, the weight / thickness of the liquid impermeable layer applied to the inner base surface may be greater than that applied to the inner wall surface. In other embodiments, the weight / thickness of the liquid impermeable layer applied to the inner wall surface may be the same as that applied to the inner base surface. The liquid impermeable layer may be applied in liquid form (e.g. in the form of a solution or an emulsion) and then dry (air-dried, via the application of heat, or the like) to provide the liquid impermeable barrier. In such embodiments, the liquid impermeable barrier may be applied to the inner wall surface and I or the inner base surface using any technique known to those skilled in the art, for example, by printing, brushing, spraying or the like. As explained herein, the function of the liquid impermeable layer is to provide a barrier to moisture and liquid passing into the cup wall or base, which can result in saturation of the wall and I or base paper fibres and leakage of the liquid therefrom. In embodiments, the liquid impermeable layer comprised on the inner wall surface and I or the inner base surface may provide the wall and I or base, respectively, with a Cobbeo value of less than about 10g / m2, less than about 5g / m2, less than about 2g / m2, less than about 1g / m2, or about 0 g / m2. Cobbeo values are measured in accordance with ISO standard 535 (Paper and Board). In a further embodiment, the liquid impermeable layer comprises an inorganic mineral. The outer wall surface and I or outer base surface may or may not comprise a liquid impermeable layer. In embodiments, the outer wall surface and I or outer base surface may comprise a varnish (for example an overall protective varnish). This may be the same material or different to the sealable lacquer employed in aspects of the present invention. In embodiments, the liquid impermeable layer may be inherently sealable. Whether it is or not, a sealable lacquer may be applied to the quadrilateral blank (e.g. along the first and I or second edge sealing portion) and I or the base (e.g. along the wall sealing portion). In embodiments, one or both of the base sealing portion and the wall sealing portion comprise a sealable lacquer coating and the sealable lacquer coating is present within the base seam. Additionally or alternatively, one or both of the first and second edge sealing portions comprise a sealable lacquer coating and the sealable lacquer coating is present within the wall seam. In certain embodiments of the invention, the sealable lacquer coating is provided on top of the liquid impermeable layer, for example on the wall sealing portion, on the base sealing portion, on the first edge sealing portion and I or the second edge sealing portion. Any type of food approved sealable lacquer coating may be employed in the present invention provided that it is capable of providing a liquid resistant seal upon activation. In some embodiments, the lacquer coating may be heat sealable (e.g. at a temperature of around 100°C to about 250°C), for example it may be sealable via contact with hot pressured air. Additionally or alternatively, the lacquer coating may be ultrasonically sealable (e.g. at a frequency of around 20mHz to about 40mHz). Other types of sealable lacquer coating could also be employed, e.g. pressure sealable lacquer coatings. In certain embodiments, the sealable lacquer coating and I or the liquid impermeable layer may be free of fluorinated compounds. In some embodiments, the sealable lacquer coating and I or the liquid impermeable layer may be free of poly- and perfluoroalkyl substances (PFAS), for example perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). In embodiments of the invention, the sealable lacquer coating materials that may be employed are those which are environmentally friendly, for example which are biodegradable. Advantageously, unlike conventional fibre based containers comprising polyethylene based liquid impermeable layers, this permits containers to be composted at home or industrially following disposal of the container. Specific lacquer coating materials which may be utilised include polyvinylacetate and acrylic lacquers. The sealable lacquer coating may be applied at a coating weight of about 1 to about 50 g / m2, about 3 to about 30 g / m2, about 5 to about 25 g / m2, about 6 to about 22 g / m2, about 8 to about 20 g / m2 or about 10 to about 15 g / m2. In embodiments in which the base sealing portion and the wall sealing portion both are provided with sealable lacquer, the weight of the sealable lacquer provided in the wall sealing portion may be greater than the weight of the sealable lacquer provided in the base sealing portion. For example, the weight of the sealable lacquer provided in the wall sealing portion may be about 5 to about 20 g / m2, about 6 to about 15 g / m2 or about 10 to about 15 g / m2. Additionally or alternatively, the weight of the sealable lacquer provided in the base sealing portion may be about 3 to about 15 g / m2, about 5 to about 10g / m2 or about 6 to about 8 g / m2. In certain embodiments, the thickness of the sealable lacquer coating applied to the inner base surface is consistent. For example, the thinnest part of the sealable lacquer coating applied to the inner base is no less than about 20%, no less than about 30%, no less than about 40%, no less than about 50%, no less than about 60%, no less than about 70% or no less than about 80% of the thickness of the thickest part of the sealable lacquer coating applied to the inner base surface. The sealable lacquer coating preferably is elastic. In preferred embodiments, the sealable lacquer coating is more elastic than the liquid impermeable layer, i.e. it has a lower modulus of elasticity than the liquid impermeable layer. For example, the sealable lacquer coating may have a modulus of elasticity of less than about 5 GPa, less than about 2 GPa, less than about 1 GPa, less than about 0.5 GPa, less than about 0.2 GPa or less than about 0.1 GPa. In some embodiments, the sealable lacquer coating has a modulus of elasticity of about 0.01 GPa to about 1 GPa, about 0.012 GPa to about 0.5 GPa or about 0.015 to about 0.1 GPa. Where reference is made herein to the sealable lacquer coating being comprised on or in a region or portion of a component, the sealable lacquer coating may be comprised on the entirety of that region or portion or a substantial part thereof. In embodiments, the entirety of the inner base surface does not comprise the sealable lacquer coating, i.e. the inner base surface comprises a central portion which does not comprise sealable lacquer coating. The quadrilateral blank (and thus tubular wall component) and I or the circular base component may comprise any suitable fibre based substrate, but preferably comprise a paperboard substrate, such as, but not limited to, cupstock and the like. In embodiments of the invention, the material from which the quadrilateral blank I tubular wall component and the base component are formed may be the same or different. In some embodiments, the fibre based substrate is clay-coated, optionally on the inner wall surface. The quadrilateral blank / tubular wall component and the circular base component may have any thickness which provides sufficient structural strength to the assembled container. In embodiments, the quadrilateral blank I tubular wall component and I or the circular base component may have a thickness (excluding the impermeable liquid layer and any sealable lacquer coating) of about 200pm to about 2000pm, about 250pm to about 1000pm, about 300pm to about 500pm or about 350pm to about 500pm. Additionally or alternatively, the quadrilateral blank I tubular wall component and I or the circular base component may be formed from fibre based substrate having a weight of about 150 to about 500 g / m2, about 180 to about 350 g / m2, about 200 to about 330 g / m2 or about 250 to about 300 g / m2. In embodiments the circular base component is formed from fibre based substrate having a weight greater than 250 g / m2, greater than 255 g / m2 or greater than 260 g / m2. In some embodiments, the fibre based substrate comprised in the tubular wall component I quadrilateral blank has a heavier weight than the fibre based substrate comprised in the circular base component. In certain embodiments, the fibre based substrate comprised in the circular base component has a heavier weight than the fibre based substrate comprised in the tubular wall component I quadrilateral blank. In other embodiments, the fibre based substrate comprised in the tubular wall component I quadrilateral blank has the same weight as the fibre based substrate comprised in the circular base component. In embodiments of the invention, the circular base component is substantially planar, save for the folded portion which is folded at an angle from the remainder of the circular base component. The circular base component may have a diameter of from about 30mm to about 100mm, about 35mm to about 80mm, or about 40mm to about 65mm. As those skilled in the art will recognise, the tubular wall component may be perfectly cylindrical. In other embodiments, the tubular wall component may not be perfectly cylindrical. For example, it may be tapered, e.g. in the form of a truncated cone and I or such that the diameter of the tubular wall component at the end at which the base seal is formed is smaller than the diameter of the tubular wall component at its opposite end. The process of the invention as defined herein comprises 3 parts, one or more of which may be comprised in the process. For example, in embodiments, part 1) is performed, part 2) is performed, or part 3) is performed. In some embodiments, two of the claimed parts may be performed, for example part 1) and part 2), part 1) and part 3) or part 2) and part 3). In other embodiments, all of parts 1) to 3) are performed. The present application discloses multiple aspects of the invention, e.g. methods of preparing a container, apparatus which may be employed in such methods, etc. Unless otherwise stated, the disclosure of features in connection with one aspect of the invention is not limited to those features only being provided in connection with that aspect. To the contrary, where a feature of a component is disclosed in connection with one aspect of the invention, it may also be provided in the corresponding component of any other aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of part of a container-forming machine comprising a heating station, heat conservation zone and sealing station; Figure 2 is a perspective view of a heat conservation zone; Figure 3 is a perspective view of a conventional heating apparatus employed in containerforming apparatus; Figure 4 is a perspective view of a heating apparatus comprising a baffle member of the present invention; and Figure 5 is a side cross-section view of a knurling member of the present invention comprising a resilient material on its operative surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to, but not limited to, the aforementioned figures. Figure 1 illustrates several stations of a container-forming apparatus that may be utilised to perform the process of the present invention. More specifically, heating station (10), heat conservation zone (20) and sealing zone (30) are depicted. Tubular wall components (40) formed in upstream stations (not shown) are retained on conic mandrels (42) which are mounted on a rotary conveyor (44). The rotary conveyor (44) moves the tubular wall components (40) from one station to another. In the heating station (10), hot air is directed into the base interior (not shown) to heat the base sealing portion of the tubular wall component (40) and the wall sealing portion of the circular base component (not shown) such that the sealable lacquer coating comprised thereon attains a temperature equal to orgreaterthan the activation temperature. This may be achieved using the heating apparatus shown in Figures 3 and 4. Heating stations configured in this way will be known to those skilled in the art of producing containers from polyethylene-coated substrates. However, while polyethylene benefits from a wide activation window, meaning that it will remain activated, i.e. sealable, for the period in which the tubular wall component (40) is moved from the heating station (10) to the sealing station (30), the inventors have found that certain sealable lacquers do not, owing to narrower activation windows. Therefore, the inventors have recognised that use of a heat conservation zone (20) can beneficially maintain the sealable lacquer within the activation window while the tubular wall component (40) is moved from a heating station (10) to the sealing station (30). The heat conservation zone (20) comprises a channel defined by two sidewalls and a base wall (shown in more detail in Figure 2). The heat conservation zone (20) also comprises inlets (22) via which hot air can be fed into the heat conservation zone (20). The hot air may be exhaust hot air from upstream ordownstream steps in the container forming process. The tubular wall components (40) and circular base components (not shown) are moved via the rotary conveyor (44) from the heating station (10) , via the heat conservation zone (20) to the sealing station (30). The sealing station comprises a counterplate (32) having an opening shaped to correspond to the exterior surface of the lower end of the tubular wall component (40). Once located in the opening of the counterplate (32), a knurling member (not shown) is moved upwardly into the base interior and rotated erratically to apply mechanical pressure to the wall sealing portion, the base sealing portion and the counterplate (32) to form a watertight seal between the tubular wall component (40) and the circular base component (not shown). Figure 2 shows the heat conservation zone (20) in more detail. As can be seen, the heat conservation zone (20) comprises a curved channel via which the tubular wall component (40) may be moved. Hot air is fed via inlets (22) which then is flowed underneath the channel where it can enter the channel via elongate openings (24), thus maintaining an elevated temperature within the channel. Figure 3 depicts part of a conventional heating station as employed in container forming machines configured for use with polyethylene-coated substrates. That station comprises a heating member (50) which is positioned within the base interior of the folded circular base component or the interior of the lower end of the tubular wall component (40). Hot air is then fed into the interior of the heating member (50) which passes through the openings in the wall of the heating member. The openings are positioned to direct hot air to the wall sealing portion and I or the base sealing portion to activate the polyethylene and render it sealable. While such configurations can be effectively used to form base seams between polyethylene-coated container components, as shown with dotted lines, heat can dissipate from within the interior of the base interior or the lower end of the tubular wall component (40). While this is not problematic when such apparatus is used with polyethylene-coated substrates, for container components comprising certain sealable lacquer coatings, owing to the narrower activation window, this loss of heat can result in sub-optimal seal formation. Additionally, the inventors have found that by heating the sealing portions from within the interior of the tubular wall component (40) or base interior and from the exterior of the tubular wall component (40), this advantageously permits such lacquers to be effectively employed in the formation of container base seams. This can be achieved through use of a baffle member (52) as shown in Figure 4. More specifically, baffle member (52) prevents the dissipation of hot air from the base interior / lower end of the tubular wall component (40) and instead directs that hot air to the exterior of the lower end of the tubular wall component, heating the wall sealing portion and base sealing portion from outside the container and within. In the embodiment shown in Figure 4, a circular base component is not present. Such an embodiment may be useful in processes in which a heating step to activate sealable lacquer provided on the base sealing portion of the tubular wall component (40) is conducted prior to the folded circular base component (not shown) being positioned within the lower end of the tubular wall component (40) and the subsequent sealing step. However, in other embodiments, such a heating step could be employed following the step of positioning the folded circular base component within the lower end of the tubular wall component (40) which advantageously would result in activation of sealable lacquer coatings applied to both the wall sealing portion and the base sealing portion. Figure 5 is a side cross-section view of a knurling member (60) of the present invention comprising a resilient material (62) on its operative surface, i.e. the part of the knurling member (60) which applies mechanical pressure to the base sealing portion, the wall sealing portion and the counterplate during step e. of the process of the invention. The resilient material (62) is provided in the form of three O-ring seals (62) which are seated within three grooves formed into the surface of the knurling member (60). As can be seen, the operative surface of the knurling member (60) is not exactly cylindrical but has a truncated cone shape to match the profile of the base interior. Advantageously, the inventors have found that the use of a knurling member (60) comprising resilient material (62) such as O-rings (62) on its operative surface is preferable to conventional metal knurling members as this minimises the risk of pin holes and cuts being formed in the liquid impermeable layer, particularly at or around the area where the wall seam is located.

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