Screw Threads

Containers are often provided with a closure, such as a cap or lid. Such closures may be single use, for example a film may be fixed across an opening of a container using an adhesive. In other examples closures may be reusable, such that the container may be openable by removing the closure and it may be closed again by replacing the closure. For example a lid or cap may be fitted to an opening of a container using push fit, a screw thread or other reusable closure method. An opening of a container may be provided with a screw thread to engage a lid or a cap with a corresponding screw thread to close the container.

A molded fiber object may be an object formed using a fiber molding process, such as a wet pulp molding process or a dry fiber molding process.

In a wet pulp molding process, the object may be formed on a pulp molding die comprising a screen, and a form which supports the screen. The screen may comprise a plurality of small openings, or pores, which allow liquid to flow through. The screen may be separable from the form. The form may comprise any element which provides structural support for the screen which helps it to maintain its shape while forming an object. The form may also comprise holes or channels through which fluids may flow to and from the screen. In some examples the pulp molding die may be formed from a metallic material or from a plastic material. In some examples they may be manufactured using machining techniques, such as CNC (Computer Numerical Control) milling or additive manufacturing. The screen may be a woven mesh formed from a plurality of fine metal wires.

Wet pulp molding processes may comprise covering the screen of a pulp molding die with a slurry, or pulp, comprising a liquid component, such as water, and a solid, fibrous material. The screen of the pulp molding die may comprise a surface having a shape which corresponds to the shape of a surface of an object to be formed using the die. The die may be submersed in a bath of the slurry to cover the screen of the die. The screen of the pulp molding die may comprise pores (i.e. small holes, or porous zones) in the surface which allow the liquid component of the slurry to pass through, but are sufficiently small that the solid, fibrous material accumulates on the surface of the screen to form the object. The formed object may then be dried, for example by heating in an oven or between dies (e.g. metal dies), to form the finished molded fiber object.

In some examples heating between dies may be referred to as hot pressing the object. Hot pressing may provide a higher surface quality and/or more precise dimensions than forming an object without hot pressing.

In other examples a dry molded fiber process may be used to form a molded fiber object. In a dry molding process, loose, dry fibers may be provided between sheets of a tissue material and the object may be formed by applying heat and/or pressure to the sheets of tissue material while the sheets of tissue material and fibers is on a mold.

In order to reduce the amount of plastics used in packaging and to increase the ease of recycling packaging, molded fiber has been used as packaging for a wide variety of products. However, molded fiber objects are often formed from materials, such as recycled paper or cardboard, which are susceptible to damage when exposed to moisture. Furthermore providing a closure which is suitable for containing liquids may be challenging. To provide molded fiber packaging for wet products, a waterproof layer may be added to an interior surface of the packaging, for example a coating or a film, or in other examples a waterproof container, such as a plastic container may be provided within the molded fiber packaging.

As used herein, a closure is an item which may be used to close, or seal, a container. For example a closure may be a lid, cap or sealing film. Closures have been provided for molded fiber containers, for example by sealing a film to an opening of the container using an adhesive or by providing an insert, made from a material such as plastic or metal, which is secured around the opening of the container. Such inserts may have a screw thread to allow a lid or cap to be screwed on to the container, however, they can add substantial cost and complexity to manufacture of the container. Furthermore, they significantly increase the complexity of recycling the container because the different types of material may be to be separated into different recycling streams.

Inserts have been used to provide a thread for attaching a closure to molded fiber containers because it is challenging to form a thread directly in the container. Generally, forming small features with precise dimensions using molded fiber materials is more difficult compared with other manufacturing techniques (e.g. injection molding or blow molding which may be used to form plastic bottles with screw threads). It may be particularly challenging to form the screw thread around a circular opening of a container. Furthermore, molded fiber containers may be formed from multiple parts which are subsequently assembled. In such examples if the screw thread was formed with the body of the container, it may extend over multiple parts of the container resulting a need to accurately align the multiple parts of the container resulting in further manufacturing challenges.

show a closure engaging part.shows an outer surface of the closure engaging parti.e. the surface which faces away from a container the closure engaging partis affixed to when in use.shows an inner surface of the closure engaging parti.e. the surface which faces towards a container when the closure engaging partis affixed to when in use.

In some examples the closure engaging partis formed from a compostable material. In some examples the closure engaging partis a molded fiber part i.e. a closure engaging molded fiber part. Such a closure engaging molded fiber partmay be formed using a pulp molding process, for example from a material such as recycled paper or cardboard.

The closure engaging partmay be intended to be used to reversibly attach a closure, such as a lid with a screw thread, to a container to seal the container. The closure engaging partmay be attached to a container such that when a lid is arranged on the closure engaging part, the closure engaging partengages the lid to hold it in a position that closes the container. For example a closure may be rotated about an axis and a screw thread of the lid may engage a screw thread of the closure engaging partto secure the closure in position at an opening of the container.

The closure engaging partcomprises a plurality of threaded portions-. A portion of a screw thread is provided on each threaded portion-. As used herein a screw thread is a helical structure which provides linear movement or force when an object, such as a lid, with a corresponding screw thread is rotated about the screw thread. When the closure engaging partis wrapped around an opening of a container, the portions of screw thread on adjacent threaded portions may align such that they collectively form a screw thread around the opening i.e. the portions of screw thread may be colinear with portions of screw thread on an adjacent threaded portion(s). In some examples, the portions of screw thread are raised portions of material, such as molded fiber material. For example, the screw thread may comprise oblique raised linear features, or ‘ridges’, which when wrapped around an opening of a container align to provide a (partial) screw thread for the container. In some examples, at least one or each threaded portions-may comprise a plurality of substantially parallel ridges, each ridge forming part of the screw thread. The ridges on a threaded portion-may be substantially straight, or may have a curved or arc-like form. When the closure engaging part is in use, the raised portions of material may align to form a screw thread which may extend around a substantial part of an opening of a container to which the closure engaging partis affixed.

In examples wherein the closure engaging partis a closure engaging molded fiber part, the portions of screw thread may be defined in a pulp molding screen which is used to form the closure engaging molded fiber part. For example the screen may comprise raised portions which cause the closure engaging molded fiber partto have corresponding raised portions when it is formed on the screen. In some examples the closure engaging molded fiber partmay undergo further processing after being formed in the fiber molding process to define the screw threads, for example as described in relation to.

The closure engaging partcomprises a flexible portion-between and connecting pairs (e.g. adjacent pairs) of threaded portions. As shown in thethe flexible portions-may not comprise a screw thread. In some examples the flexible portions-may be free of any raised topography, for example be substantially planar. The flexible portions-are more flexible than the threaded portions-. The absence of any raised topography on the flexible portions-may allow them to be more flexible than the threaded portions-. In some examples the flexible portions may comprise some topography, for example debossed, engraved or raised features, but it may be such that it allows the flexible portions-to remain more flexible than the threaded portions-. For example the topography of the flexible portions-may be smaller than the topography of the threaded portions-i.e. the topography may be of a smaller height and/or cover a smaller proportion of the surface area of the flexible portions-relative to the threaded portions-. In some examples the flexible portions-may comprise debossed, engraved or raised topography that extends substantially parallel to the axis of the screw thread (i.e. a central axis of the screw thread when the closure engaging partis arranged around a container opening and about which a closure may be rotated to cause a screw thread of the closure to engage with the axis) and therefore allows the flexible portions-to bend or curve along this axis. In examples wherein the flexible portions comprise some topography the height of the topography may be sufficiently small that it does not interfere with operation of the screw thread i.e. it does not obstruct a threaded cap from engaging with the screw thread.

In some examples the flexible portions-may be thinner than the threaded portions-to allow then to have greater flexibility. In other words, the thickness of thematerial forming the threaded portions-may be greater than the thickness of the material forming the flexible portions-. For example the material forming the flexible portions-may have a thickness of 0.6 mm and the material forming the threaded portions-may have a thickness in the range of 0.6 mm to 1.8 mm. For example the thickest parts of the threaded portions-(e.g. the raised threads) may have a thickness of 1.8 mm and other parts of the threaded portions-(e.g. between the threads) may have a thickness of 0.6 mm. Therefore in some examples only parts of the threaded portions-may be thicker than the flexible portions-. In some examples most, or all, of the threaded portions-may be thicker than the flexible portions-

In some examples, for example as shown in, rather than varying the thickness of the threaded portions-to provide the screw thread, the threaded portions-may have a substantially constant thickness but have an undulating or ‘wavy’ profile to provide the screw thread.

In some examples, the increased flexibility of the flexible portions-may be provided by removing material from these sections. For example an opening or openings (e.g. holes) may be provided in the flexible portions. In some examples these openings may be formed as part of a fiber molding process. In some examples these openings may be cut out of the flexible portions-after the closure engaging partis formed. In some examples the openings may be notches extending from a top and/or bottom edge of the flexible portions-. In other words a notch may be a hole which is not entirely surrounded by material.

In some examples the closure engaging partcomprises at least three threaded portions-and two flexible portions-. The closure engaging partshown incomprises three threaded portions-and two flexible portions-. However, in other examples there may be more or fewer threaded portions and/or flexible portions. For example a closure engaging part may comprise two threaded portions with one flexible portion between the threaded portions, or a closure engaging part may comprise four threaded portions with three flexible portions between the threaded portions. In some examples the closure engaging part may comprise a further flexible portion (or portions) at one end (or both ends) of the closure engaging part attached to a single threaded portion. Therefore, for a closure engaging part with N threaded portions, the number of flexible portions may be N−1 if there are no end flexible portions, N if there is one end flexible portion, or N+1 if there are flexible portions at both ends.

When there are fewer threaded portions-, the curvature of the threaded portions is larger and therefore manufacture may be more challenging. However, reducing the curvature of the threaded portions by increasing the number of threaded portions results in reduced total threaded area on the closure engaging partdue to the increased number of flexible portions. As shown in, the closure engaging part may comprise three threaded portions-and two flexible portions-. This may provide a balance between a closure engaging partwhich has sufficient ease of manufacturing and flexibility to be easily wrapped around an opening of a container (i.e. by providing a larger area of flexible portions) and a closure engaging partwhich has a substantial threaded area (i.e. by providing a larger area of threaded portions).

In some examples, for example as shown in, the threaded portions-may be larger than the flexible portions-. This may provide a relatively large threaded area on the closure engaging part, thereby providing better engagement with a closure. In some examples the threaded portions-may form at least 60%, 70%, 80% or 90% of the area of the closure engaging part.

As shown inthe screw thread of the threaded portions-may be formed by substantially linear raised portions of material extending along the threaded portions of the closure engaging partin a substantially helical pattern. The dimensions of the screw thread may be defined according to a standard, for example as defined by the Glass Packaging Institute (GPI), the Society of Plastics Industry (SPI) or International Society of Beverage Technologists (ISBT) Threadspecs.

In some examples each threaded portion-has a circular arc shaped cross section. For example when the closure engaging partis viewed in a direction parallel to the axis of the screw thread (wherein the axis is the axis about which a closure may be rotated to engage with the screw thread) the cross sectional shape of the threaded portions may be of an arc of a circle so that when the closure engaging partis affixed to a container with a circular opening, the relatively rigid threaded portions conform to the shape of the opening. Therefore the internal radius of curvature of the threaded portions-may be equal to the exterior radius of the opening of the container. For example a container may have an opening with an exterior radius of 1.5 cm. The threaded portions-of a corresponding closure engaging partmay have an internal radius of curvature of 1.5 cm.

The closure engaging partmay have a generally rectangular shape. For example when in a plan view, prior to wrapping the closure engaging partaround a container, the closure engaging partmay have a rectangular shape. Furthermore each of the threaded portions-and each of the flexible portions may also have a generally rectangular shape from this view.

The total length of closure engaging partin a direction perpendicular to the axis of the screw thread may be equal to or less than an outer circumference of an opening of a container the closure engaging partis to be affixed to, so that when the closure engaging partis affixed to the container, a screw thread is provided around a substantial portion of the opening of the container. In the example above, for a container with an opening with an outer radius of 1.5 cm, the length of the closure engaging partmay be 9.4 cm (i.e. almost as long as the outer circumference of the opening of the container).

The length of each threaded portion-in the direction perpendicular to the axis of the screw thread may be greater than the length of each flexible portion-in this direction to provide a relatively large area of screw thread. In the example described above, for a container with an opening with an outer radius of 1.5 cm, and a closure engaging partcomprising three threaded portions-separated by two flexible portions-, the length of the threaded portions may be 2.4 cm and the length of the flexible portions may be 1.1 cm to provide the total length of 9.4 cm

In some examples the screw thread of the closure engaging partis at least partially formed using a hot pressing process. Hot pressing the closure engaging partmay comprise placing the closure engaging partbetween heated dies (e.g. metal dies), wherein the shape of the surfaces of the dies corresponds to the intended shape of the finished closure engaging part. The dies may define the shape of the screw thread i.e. at least one die may comprise surface topography that corresponds to the intended shape of the screw thread. When the closure engaging partis placed between the dies, heat and/or pressure may be applied so that the closure engaging partconforms to the shape of the dies. When the closure engaging part is a molded fiber object, hot pressing may allow more accurate shapes to be formed compared with molded fiber objects which do not undergo a hot pressing process. In particular hot pressing may allow more accurate and finely detailed shapes to be formed in the object. Therefore hot pressing may allow better definition of the screw thread. The hot pressing process may also partially or wholly dry the closure engaging molded fiber part, such that it may be formed with or without a further drying process (e.g. in an oven).

Hot pressing may also be referred to as fiber thermoforming. Molded fiber objects which are formed using a hot pressing process may be referred to as Type-3 Molded Fiber Products, Thermoformed products or thin wall products. Such molded fiber objects may have a wall thickness of less than 4 mm. For example the flexible portions-of the closure engaging molded fiber partmay have a thickness of 0.6 mm and the threaded portions of the closure engaging molded fiber partmay have a thickness in the range of 0.6 mm to 1.8 mm. For example the total thickness at the locations of the raised threads may be 1.8 mm and the thickness of the threaded portions-may be 0.6 mm between the threads.

In some examples cold pressing may be performed instead of hot pressing to form the portions of screw thread. Cold pressing may comprise applying pressure to an object being formed between dies without heating.

By providing the screw thread on a closure engaging molded fiber partrather than directly on a molded fiber container body, hot pressing may be performed on the relatively small closure engaging molded fiber partrather than on the relatively large container body. In some examples, this may avoid subjecting the container body to hot pressing in order to accurately define a screw thread. Hot pressing is an additional process and therefore adds additional cost and time to manufacture. Furthermore, by providing the screw thread on a closure engaging molded fiber partrather than directly on the container body, a single design of container body may be used for threaded and non-threaded containers. This provides manufacturing flexibility because the decision to add the closure engaging molded fiber part to a container may be made after the parts are manufactured. Furthermore, costs are reduced because the same fiber molding toolsets can be used for both threaded and non-threaded containers.

In some examples the flexible portions-and threaded portions-are integrally formed in a fiber molding process, for example they may be formed in a single fiber molding process. This fiber molding process may define the screw thread, however, in some examples the threaded portions-may be formed with a roughly defined screw thread or with no screw thread in the fiber molding process and definition of the screw thread may be provided by an additional hot pressing process.

In some examples the closure engaging partfurther comprises a securing means. For example the securing means may comprise an adhesive or mechanical fixing. The securing means may be provided to allow the closure engaging partto be affixed to a container, in particular to allow it to be affixed around an opening of a container to provide a screw thread for attaching a closure to the container. The closure engaging partmay be glued (for example, permanently, or substantially permanently) to the container using an adhesive. For example an industrial labelling process may be used to apply a coating of adhesive to the closure engaging part, to the container or both and then the closure engaging partmay be wrapped around the opening of the container to affix the closure engaging part to the container.

In some examples a mechanical fixing may be used to attach the closure engaging partto the container, either alone or in combination with an adhesive. The mechanical fixing may comprise an additional component such as a ring, which may be formed from plastic or metal, which is inserted over the opening of the container after the closure engaging partis wrapped around the opening to hold the closure engaging partin position. In other examples the mechanical fixing may comprise spikes, clips or other means to hold the closure engaging partin position. In other examples the mechanical fixing may comprise a ratcheting means which secures the closure engaging partin position, for example a cable tie or similar device may be secured around the closure engaging partwhen it is wrapped around the opening of the container. In other examples the mechanical fixing device may have elastic properties, for example it may be an elastic band or O-ring type rubber ring which is placed around the closure engaging partwhen it is wrapped around the opening.

In some examples the closure engaging partmay be formed with a groove and/or protrusion to align such a mechanical fixing device.

shows an example of a container. The containermay comprise a molded fiber body. In this example the bodyis a bottle however, in other examples the bodymay be a jar or any other container with a circular opening.

The containercomprises a closure engaging partsecured around the opening of the body, in this example around the neck of the bottle. The closure engaging partmay be a closure engaging partas described in relation to. In some examples the closure engaging partis a closure engaging molded fiber part. In some examples at least one of the closure engaging partand the containerare formed from molded fibers. In some examples both the closure engaging partand the containerare formed from molded fibers.

The closure engaging partcomprises a first threaded portioncomprising a first portion of a screw thread and a second threaded portioncomprising a second portion of a screw thread. In other examples the closure engaging partmay comprise more than two threaded portions-, for example it may comprise three threaded portions.

The closure engaging partalso comprises a flexible portionwithout a screw thread connecting the first and second threaded portions-. In other examples, in particular although not exclusively, when there are more than two threaded portions, the closure engaging partmay comprise more than one flexible portion. When the closure engaging partis initially formed, the flexible portion may be substantially flat, but when assembled by wrapping the closure engaging partaround the opening of the bodyof the containerthe flexible portionmay bend to conform to the shape of the opening. The closure engaging partmay therefore encircle the opening. The closure engaging partmay therefore provide a screw thread around a substantial portion of the opening such that a lid with a corresponding screw may be fitted to the opening to seal the opening.

The closure engaging partmay be secured around the opening of the body. The closure engaging partmay be secured using at least one of an adhesive, a tape or a mechanical fixing. An adhesive or a tape (e.g. double sided tape) may be applied to the closure engaging partor to the bodythen the closure engaging partmay subsequently be relatively wrapped around the body. Pressure may be applied to the closure engaging part to ensure the closure engaging partadheres to the body. For example a die or dies may surround the body(and in some examples may fit inside the opening of the body) to exert a force on the closure engaging parttowards a central axis of the body. In some examples an industrial labelling process may be used to apply the adhesive or tape, or to wrap the closure engaging partaround the body. For example a labelling machine may be modified to handle the closure engaging part, the adaptions to the labelling machine being to allow it to handle the closure engaging partwhich is relatively thick compared with other labels.

In an example, the internal radius of curvature of the threaded portions-is 11.9 mm and the exterior radius is 12.5 mm. The thickness of the flexible portions may be 0.6 mm and the thickness of the threaded portions may be 0.6 mm to 1.8 mm. The height of the closure engaging partin a direction parallel to the axis of the screw thread may be 17.97 mm (for both the threaded portions-and flexible portion). The length of the flexible portionin a direction perpendicular to its height may be 5.45 mm and the length of the threaded portions-in a direction perpendicular to their height may be 18.39 mm.

shows another example of a container. The containermay comprise the features described in relation to the containerof.

In this example the containerfurther comprises a sealing memberarranged around the opening of the body. In this example the sealing memberis a ring-like structure which is positioned on top of the closure engaging part. The sealing membermay be formed of a material such as plastic, rubber or metal. For example the sealing membermay comprise Polyethylene terephthalate (PET), Polypropylene (PP) or Polyethylene (PE). In other examples a sealing member may be provided on or by the closure.

In some examples containermay comprise a lining material, in particular when the containeris a molded fiber container. The liner may be a water resistant or waterproof material and may allow the container to carry wet products, such as liquids or food without damaging the molded fiber material. The liner may be a coating applied to the interior of the container body, a film laminated to the interior of the container bodyor may be a separate bag-like body which is inserted into the container. The sealing membermay be bonded to the liner to provide a liquid proof seal between the liner and the sealing member. The sealing membermay be bonded to the liner using an adhesive or by welding the materials (i.e. melting at least one of the liner or sealing memberto cause them to fuse together).

A closuremay be screwed onto the screw thread. In this example the closure is a lid comprising an internal screw thread. However, in other examples other configurations may be possible e.g. the closure engaging partmay be arranged around the inside of the opening and the closuremay have an external screw thread. The closuremay be rotated relative to the containerso that a screw thread of the closure engages with the screw thread of the closure engaging part. When the closureis screwed onto the screw thread, the sealing memberprovides a seal between the containerand the closure. In this example sealing is achieved when the sealing memberabuts an internal surface of the closure. The screw thread allows a force to be exerted between the sealing memberand the inside of the closureto provide a liquid proof seal. The sealing membermay also protect the opening of the containerand the edge of the closure engaging partfrom being damaged by this force, in particular when the closure engaging partis formed from materials such as molded fibers. Sealing may also be achieved without the presence of the sealing member, however, the sealing member may provide a more reliable and durable means for sealing the container.

is an example of a method, which may comprise a method for forming a closure engaging object, such as a closure engaging molded fiber object. The closure engaging object may be a closure engaging part as described in relation toor may be a part of the container described in.

The methodcomprises, in block, forming a plurality of threaded portions of a closure engaging object, each comprising a portion of a screw thread. The plurality of threaded portions may be formed in a fiber molding operation. For example a fiber molding screen may be arranged on a fiber molding form and submersed in a slurry comprising a mixture of fibrous material and liquid. The shape of the screen may correspond to the intended shape of the threaded portions to be formed on the screen. When submersed in the slurry, the liquid may be drawn through the screen causing fibrous material to accumulate on the screen to form the threaded portions. When the threaded portions are formed, the screen may then be removed from the slurry.

The threaded portions may be the threaded portions described in relation to,and/or.

The methodcomprises, in block, forming a flexible portion, wherein the flexible portion provides a flexible connection between two of the threaded portions. Forming the plurality of threaded portions and forming the flexible portion may comprise performing a fiber molding operation and the flexible and threaded portions may be formed on a fiber molding screen. The flexible portion may be formed in the same fiber molding operation as the threaded portions. For example a portion of the screen may define the intended topography of the flexible portion and when the screen is submersed in the slurry fibrous material may also accumulate on the screen to form the flexible portion such that the flexible portion connects with, and is formed integrally with, the threaded portions.

In other examples the flexible portion may be formed separately from the threaded portions and subsequently attached to the threaded portions. For example the flexible portion may be formed from a different or the same material as the threaded portions. For example the flexible portions may comprise a paper material and the threaded portions may comprise molded fiber material. The flexible portion may be an adhesive tape, such as a paper tape, and the closure engaging part may be formed by adhering the threaded portions to the tape such that the threaded portions are spaced apart on the tape and the portion of tape between the threaded portions forms the flexible portion.

The flexible portion may be more flexible than the threaded portions, for example (and as discussed in greater detail in relation to) due to an absence of topography, or lower amount of topography on the flexible portion. In some examples (and again as discussed in greater detail in relation to) forming the flexible portion may comprise forming holes or notches in the flexible portion to reduce the amount of material in the flexible portion, thereby increasing the flexibility of the flexible portion.