GB2617583A

GB2617583A - Film forming apparatus

Info

Publication number: GB2617583A
Application number: GB2205461.3A
Authority: GB
Inventors: Smith Jonathan
Original assignee: Printaply Ltd
Current assignee: Printaply Ltd
Priority date: 2022-04-13
Filing date: 2022-04-13
Publication date: 2023-10-18
Anticipated expiration: 2042-04-13
Also published as: GB2617583B; GB202205461D0

Abstract

Film forming apparatus 2 for continuously thermally laminating together at least two sheets of polymeric film material 4, 6. Apparatus 2 comprises sources of a first and second polymeric film material (4, 6), each wound around rollers (4a, 6a). Apparatus 2 further comprises a pair of nip rollers 8, 10 to simultaneously receive the first and second polymeric film materials so as to bind them into a processed laminated film. One of the pair of nip rollers, 8, is metallic and the remaining roller, 10, is formed from a resiliently deformable material. At least one heated idling roller, 14, is located upstream of the nip rollers so as to receive the first polymeric film material and heat it prior to lamination. The resiliently deformable material may be a vulcanised rubber. The heating roller may be heated to a temperature of between 140-180 °C.

Description

FILM FORMING APPARATUS

FIELD OF THE INVENTION

The invention relates to apparatus for forming a processed laminated film from a plurality of polymeric film sources, and in particular to apparatus for forming a processed laminated film which is, for example, suitable for providing an insert that may be incorporated into a container.

BACKGROUND TO THE INVENTION

The lamination of polymer films, such as to form materials suitable for the packaging of goods is a common practice. Lamination enables construction such as a resilient, functional and aesthetically pleasing films, for example a high-gloss outer, to be combined with an inner print layer, optional metallic layers or similar for the protection of goods and an inner layer suitable for contacting the goods or other materials being covered. Widely used, is the vertical form fill seal process in which a laminate on a roller is fed, shaped and sealed around goods. Resulting packages typically bowed outwards to accommodate the contents between typically a notional cylinder of polymer laminate, even if in some instances the cylinder is relatively flat.

This context is important since the combination of layers in a laminate inherently brings about internal tensions, particularly with thermal cycling and binding a laminate onto a role for future use, all tending to create differential tensions across the laminate when it is unwound. The typical laminate when taken off a roll will tend to curl. This is not generally a problem as laminate is normally kept in tension during processing and the resulting cylinder of material has ceiling.

There are, however, applications where eliminated polymer film is required to be and remain planar. An example of this is when the laminate is in the form of tickets, tokens or freestanding labels. This is typically achieved, as is commonplace, and the creation of pass cards, library cards and similar low-volume identification means by delamination of a piece of relatively thick paper or card between similarly relatively thick layers of polymer, the resulting construction being in the order of 1 mm thick and simply being of dimensions no greater than one termed "credit card size". Such structures are both strongly resilient and capable of remaining planar. However, such structures are relatively stiff and not easily deformed, such as for the purposes of placement and use materials inefficiently and are not particularly suitable for volume production, as such uses are typically used in low scale, the actual credit card format being used for higher volumes which, even if laminated, stiff and relatively thick. EP0484818A2 discloses a method for reducing the anisotropy of a liquid crystal polymer (LCP) film and producing a film having modified or more balanced properties. The film is calendered by one or more nip rolls in the transverse direction at a temperature sufficient to soften the polymer film so that it will flow under pressure from the rolls, but not so high as to melt the polymer.

There is therefore a need for the provision of a means for creating planar laminates which are both lightweight and easily resiliently deformable. There is a need for creating planar laminates including suitable indicia, such as may be suitable for creating internal labels for bottles. This is an application where a transparent bottle containing a transparent fluid is labelled by the insertion of a label through the spout (such as by curling a label into a tube) the label then resiliently expands to form a planar surface for the display of the indicia through the bottle (for example the product name and contact information). Current laminates are not suitable for this task as they are either too stiff for curling into a relatively small diameter (such as will be suitable for a soft drinks bottle), or are insufficiently planar such that within such a bottle they cannot act as an efficient means of labelling.

SUMMARY OF THE INVENTION

The invention is set out in accordance with the appended claims. The present invention provides for film forming apparatus for continuously thermally laminating together at least two sheets of polymeric film material, the apparatus comprising: a source of a first polymeric film material wound around a first roller; a source of a second polymeric film material wound around a second roller; a pair of nip rollers, consisting of two rollers of differing diameters, to simultaneously receive the first and second polymeric film materials so as to bind the films into a laminate and form a processed laminated film, one of the pair of nip rollers being formed from metal and the remaining roller of the pair of nip rollers being formed from a resiliently deformable material; wherein at least one heated idling roller is located upstream of the resiliently deformable roller so as to receive the first polymeric film material.

The apparatus allows at least two separate sources of polymeric film material to be heated independently of each other, and brought together so as to thermally laminate the two separate sources of polymeric film material into a processed laminated film by way of the application of pressure from a pair of nip rollers. A first source of polymeric film material is heated prior to making contact with one of the pair of rollers forming the nip rollers, and the second source of polymeric film material is heated by the remaining roller of the pair of nip rollers. The two sources of heated polymeric film materials are then brought together and moulded into a processed laminated film before exiting the apparatus.

The overall problem that the invention seeks to overcome is that of providing a flat sheet of laminate material formed from at least two sources of polymeric film material which are required to be heated in order for the two individual sources of polymeric film to be heated and bonded together. A problem with existing or known apparatus for producing sheets of laminate films is that often the input reels or rollers of the respective polymeric materials have different curvatures due to the roller dimensions, and therefore inherent tensions (forces) arise from the supply of the respective films passing through or over the various components of the apparatus. This gives rise to a further problem with apparatus for producing laminated films in that the force transfer between a pair of nip rollers, the component often used to squeeze the respective film sources together so as to form a processed laminated film and also known as a pair of pinch rollers, needs to be even at the point of contact in order to allow for the respective sources of polymeric material to be moulded together. A solution to this problem is the use of a pair of nip rollers with one of the pair of nip rollers being formed from metal and the remaining roller of the pair of nip rollers being formed from a resiliently deformable material. Having a pair of nip rollers, consisting of two rollers of differing diameters, also reduces the amount of creasing in the processed laminated film during production.

However, the skilled person will appreciate that a roller formed from a resiliently deformable material is much more difficult to heat. The solution to overcome this additional problem is to pass the source of polymeric material over a heated idling roller, so as to heat the polymeric film to the required temperature to minimise stresses in the film, prior to the film being passed over the resiliently deformable roller of the pair of nip rollers. The overall technical effect therefore is the production of a flatter laminated (processed) film, whilst minimising inbuilt stresses in the film during production.

Preferably, the at least one heated idling roller is maintained at a temperature above the metal nip roller temperature so as to heat the first polymeric film material prior to entering the pair of nip rollers.

Preferably, the heated idling roller is heated to at least a temperature of 100 C, preferably at least 110 °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the heated idling roller is heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the heated idling roller is heated in the range from 140 °C to 180 °C. This allows for the source of the first polymeric material to be heated to at least a temperature of 100 °C, preferably at least 110 °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the source of the first polymeric material is heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the source of the first polymeric material is heated in the range from 140 °C to 180 °C.

In an alternative embodiment, at least two heated idling rollers are located upstream of the resiliently deformable roller so as to receive and heat the first polymeric film material prior to it passing between the pair of rollers of the nip roller. In this scenario, each of the at least two heated idling rollers are heated to at least a temperature of 100 °C, preferably at least °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the at least two heated idling rollers are heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the at least two heated idling rollers are heated in the range from 140 °C to 180 °C.

Preferably, the source of second polymeric film material is passed over a second idling roller prior to entering the pair of nip rollers. This allows any tension present to be evened out across the entire surface of the film. The use of an idling roller, either the heated idling roller, the at least two heated idling rollers or the second idling roller, creates a degree of 'wrap around' of either the first or second source of polymeric films passing through/over the respective components of the apparatus, i.e. the film can be oriented so that upon passing over one of the heated idling roller, the at least two heated idling rollers or the second idling roller, it changes run direction by an angle of at least 45 degrees, preferably at least 50 degrees, preferably at least 60 degrees, preferably at least 70 degrees, preferably at least degrees, preferably at least 90 degrees, preferably at least 100 degrees, preferably at least 110 degrees, preferably at least 120 degrees, preferably at least 130 degrees, preferably at least 140 degrees, preferably at least 150 degrees, preferably at least 160 degrees, preferably at least 170 degrees or preferably at least 180 degrees.

Preferably, the metal nip roller comprises a heating element. This encourages even lamination of the processed laminate film. Having a heating element in the metal nip roller allows for faster adjustments to be made so as to modify the temperature of the source of polymeric film passing over the metal roller, either in terms of heating the source of polymeric film, or cooling it. The skilled person will recognise that it is the source of the second polymeric material that is configured to be passed over the metal nip roller which can therefore be easily heated or cooled to the desired temperature.

Preferably, the metal nip roller is heated to at least a temperature of 100 °C, preferably at least 110 °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the metal nip roller is heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the metal nip roller is heated in the range from 140 °C to 180 °C. When heated to temperatures in this range, flatter films can be produced with even lamination throughout.

Preferably, the heating element is a water recirculation apparatus flowing through an internal surface of the metal roller. This allows for greater control over the required temperature of the second source of polymeric film material due to the high heat capacity of water and associated temperature stability.

Preferably, the metal nip roller and the at least one heated idling roller are configured to be heated to the same temperature. In an alternative embodiment, the metal nip roller and the at least one heated idling roller are configured to be heated to similar temperatures within a few degrees of one another so as to create a temperature differential and ensure even lamination.

Preferably, the metal roller has a larger diameter than the resiliently deformable roller. This encourages even lamination of the processed laminate film. A smaller diameter of the resiliently deformable roller reduces the amount of deformation of the roller when pressed against the notionally flatter and larger metal roller of the pair of nip rollers.

Preferably, a ratio of the diameters of the metal roller to the resiliently deformable roller is at least 1.25:1, preferably at least 1.5:1, preferably at least 2:1, preferably at least 2.5:1, preferably at least 3:1 or preferably at least 4:1. Preferably, a ratio of the diameters of the metal roller to the resiliently deformable roller is at most 4:1, preferably at most 3:1, preferably at most 2.5:1, preferably at most 2:1, preferably at most 1.5:1 or preferably at least most 1.25:1. Preferably, a ratio of the diameters of the metal roller to the resiliently deformable roller is in the range 4:1 to 2:1.

Preferably, the metal roller has a diameter of at least 100 mm, preferably at least 150 mm, preferably at least 200 mm, preferably at least 250 mm, preferably at least 300 mm, preferably at least 350 mm, preferably at least 400 mm, preferably at least 450 mm, preferably at least 500 mm, preferably at least 550 mm or preferably at least 600 mm. Preferably, the metal roller has a diameter of at most 300 mm, preferably at most 350 mm, preferably at most 400 mm, preferably at most 450 mm, preferably at most 500 mm, preferably at most 550 mm, preferably at most 600 mm, preferably at most 650 mm, preferably at most 700 mm, preferably at most 750 mm or preferably at most 800 mm. Preferably, the metal roller has a diameter in the range 200 mm to 500 mm.

Preferably, the resiliently deformable roller has a diameter of at least 50 mm, preferably at least 100 mm, preferably at least 150 mm, preferably at least 200 mm, preferably at least 250 mm, preferably at least 300 mm, preferably at least 350 mm, preferably at least 400 mm, preferably at least 450 mm, preferably at least 500 mm, preferably at least 550 mm or preferably at least 600 mm. Preferably, the resiliently deformable has a diameter of at most 200 mm, preferably at most 250 mm, preferably at most 300 mm, preferably at most 350 mm, preferably at most 400 mm, preferably at most 450 mm, preferably at most 500 mm, preferably at most 550 mm, preferably at most 600 mm, preferably at most 650 mm or preferably at most 700 mm. Preferably, the resiliently deformable roller has a diameter in the range 100 mm to 300 mm.

Preferably, the metal roller is formed from steel. A steel roller can be easily heated and its temperature controlled so as to quickly heat or cool the source of polymeric film passing over it.

Preferably, the resiliently deformable roller is formed from vulcanised rubber. A roller formed from vulcanised rubber can impart a more even pressure to the source of polymeric film passing over it.

Preferably, the apparatus further comprises a cooling means for the processed laminated film downstream of the pair of nip rollers. Cooling the processed film quickly as it exits the pair of nip rollers is essential to ensure a uniform film of processed laminate is produced.

Preferably, the cooling means comprises a pair of cooling rollers configured to cool the processed laminated film. This allows both surfaces of the processed laminated film to be cooled as each is passed over a respective surface of the pair of cooling rollers. Preferably the processed laminated film is cooled to ambient temperature. In addition, a pair of cooling rollers permits a change run direction by an angle of at least 45 degrees, preferably at least degrees, preferably at least 60 degrees, preferably at least 70 degrees, preferably at least 80 degrees, preferably at least 90 degrees, preferably at least 100 degrees, preferably at least 110 degrees, preferably at least 120 degrees, preferably at least 130 degrees, preferably at least 140 degrees, preferably at least 150 degrees, preferably at least 160 degrees, preferably at least 170 degrees or preferably at least 180 degrees.

Preferably, the film forming apparatus further comprises a colour print roller to apply ink to at least one of the first or second polymeric film materials. Black and white or coloured images or 'inserts' can therefore be applied to at least one of the first or second polymeric film materials, which become part of the finished processed laminated film in due course.

Preferably the insert is an image, a serial number or a combination of both. The inserts may preferably be computed generated. For example, in the case of a series of serial numbers, the apparatus may be configured with a starting value and an end value for the serial numbers and the computer will sequentially apply serial numbers between the starting value and the end value onto at least one of the first or second polymeric film materials.

Preferably, the colour print roller applies ink to the first polymeric film material.

Preferably, the operating speed of the apparatus is configured to function at an output rate of laminated material of 0.1 m/min, preferably at least 1 m/min, preferably at least 10 m/min, preferably at least 50 m/min, preferably at least 100 m/min, preferably at least 150 m/min, preferably at least 200 m/min, preferably at least 250 m/min or preferably at least 300 m/min. Preferably, the rate of production of processed laminated film is configured to be in the range of 100-150 m/min.

The sources of the first and second polymeric film materials may be selected from any suitable materials including, but not limited to monoaxial polypropylene (OPP), biaxially-oriented polypropylene (BOPP), polytrimethylene terephthalate (PTT), polyethylene terephthalate (PET) or polyethylene (PE).

OPP is a film formed from a polypropylene material which is stretched in a transverse or longitudinal direction. Polypropylene is harder and more heat resistant than polyethylene and is very often used for packaging. BOPP refers to the production process that stretches the film over two directions, making it stronger and more transparent. PTT is a semicrystalline polymer that has many of the same advantages as its polyester cousins, PBT (polybutylene terephthalate) and PET. Compared to PBT, compounds composed of PTT exhibit better tensile strengths, flexural strengths, and stiffness. They also have excellent flow and surface finish. PET is the chemical name for polyester. PET is a clear, strong, and lightweight plastic that is widely used for packaging foods and beverages, especially convenience-sized soft drinks, juices and water.

Two main types of PE are known, these being high-density polyethylene (HDPE) and low-density polyethylene (LDPE). HDPE is a thermoplastic polymer produced from the monomer ethylene. HDPE is known for its high strength-to-density ratio. The density of HDPE ranges from 0.93 to 0.97 g/cm3. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder, more opaque and can withstand somewhat higher temperatures (120 °C/248 °F for shorter periods). HDPE is resistant to many different solvents, so it cannot be glued, pipe joints must be made by welding, but this makes objects constructed out of HDPE ideally suited for transporting drinking water and waste water (storm and sewage). LDPE is a thermoplastic also made from the monomer ethylene. LDPE is defined by a density range of 0.917 to 0.93 g/cm3. At room temperature it is not reactive, except to strong oxidizers; some solvents cause it to swell. It can withstand temperatures of 65 °C (149 °F) continuously and 90 °C (194 °F) for a short time. Made in translucent and opaque variations, it is quite flexible and tough. LDPE has more branching (on about 2% of the carbon atoms) than HDPE, so its intermolecular forces (instantaneous-dipole induced-dipole attraction) are weaker, its tensile strength is lower, and its resilience is higher. The side branches mean that its molecules are less tightly packed and less crystalline, and therefore its density is lower. When exposed to consistent sunlight, the plastic produces significant amounts of two greenhouse gases: methane and ethylene. Because of its lower density (high branching), it breaks down more easily than other plastics; as this happens, the surface area increases. Production of these trace gases from virgin plastics increases with surface area and with time, so that LDPE emits greenhouse gases at a more unsustainable rate than other plastics. When incubated in air, LDPE emits methane and ethylene at rates about 2 times and about 76 times, respectively, more than in water. Preferably, the source of the first and second polymeric film material is polyethylene.

Preferably, the processed laminated film exiting the nip rollers is cut into portions. This avoids the need to roll the processed film around a re-wind roller for storage so a flatter processed laminated film can be produced.

Preferably, the processed laminated film exiting the nip rollers is wound around a re-wind roller. This allows the processed laminated film to be stored for subsequent use as and when required. Re-winding the processed laminated film around a re-wind roller ensures that the processed laminated film is held under tension as it exits the pair of nip rollers so as to reduce tension in the film, both laterally and longitudinally.

Preferably, the processed laminated film is free of adhesive. This ensures that the process of producing a processed laminated film avoids the use of expensive adhesives which may be toxic.

In an alternative embodiment of the invention, the apparatus preferably comprises a chill assembly cooling table so as to cool the processed laminated film exiting the pair of nip rollers. This ensures that the processed laminated film produced is flat and straight in readiness for cutting.

Preferably the apparatus further comprises a die cut station downstream of the chill assembly cooling table. This allows the processed laminated film to be cut into discrete units depending on an end user's requirements.

Preferably the processed laminated film passing through the chill assembly cooling table is reversed back upon itself by passing the processed laminated film over a pair of cooling rollers for further chilling prior to entry into the die cut station.

In a further alternative embodiment, the processed laminated film can preferably be fed and wrapped around a re-wind roller. This provides for the processed laminated film to be stored for subsequent use instead of being directed towards the die cut station immediately for cutting and further processing.

Preferably the apparatus further comprises an optional centrifugal blower positioned underneath the chill assembly cooling table so as to blow ambient air into the chill assembly cooling table. This allows provides for additional cooling of the processed laminated film.

Preferably the optional centrifugal blower can be replaced with an air conditioning unit so as to cool the processed laminated film. This is desirable if ambient air is insufficient in order to cool the processed laminated film.

Preferably the apparatus further comprises an indexing take-off table downstream of the die cut station. This provides for an area for cut sections of the processed laminated film to be collected in batches for packing as per a user's requirements.

The present invention also provides for a system comprising the apparatus as previously described, suitable for continuously thermally laminating together at least two sheets of polymeric film material.

The present invention also provides for a method of continuously thermally laminating together at least two sheets of polymeric film material, the method comprising the steps of: feeding a first source of a polymeric film material and a second source of a polymeric film material simultaneously between a pair of nip rollers; applying pressure from the pair of nip rollers, consisting of two rollers of differing diameters, to the first and second sources of polymeric film material so as to bind the films into a processed laminated film, one of the pair of nip rollers being formed from metal and the remaining roller of the pair of nip rollers being formed from a resiliently deformable material; and cooling the processed laminated film downstream of the pair of nip rollers; wherein the first source of polymeric film material is passed over a heated idling roller prior to being fed between the pair of nip rollers.

The method allows at least two separate sources of polymeric film material to be heated independently of each other, and brought together so as to thermally laminate the two separate sources of polymeric film material into a processed laminated film by way of the application of pressure from a pair of nip rollers. A first source of polymeric film material is heated prior to making contact with one of the pair of rollers forming the nip rollers, and the second source of polymeric film material is heated by the remaining roller of the pair of nip rollers. The two sources of heated polymeric film materials are then brought together and moulded into a processed laminated film before exiting the apparatus.

Preferably, the at least one heated idling roller is heated to a temperature above the metal nip roller temperature so as to heat the first polymeric film material prior to entering the pair of nip rollers.

Preferably, the heated idling roller is heated to at least a temperature of 100 °C, preferably at least 110 °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the heated idling roller is heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the heated idling roller is heated in the range from 140 °C to 180 °C. This allows for the source of the first polymeric material to be heated to at least a temperature of 100 °C, preferably at least 110 °C, preferably at least 120 °C, preferably at least 130 °C, preferably at least 140 °C, preferably at least 150 °C or preferably at least 160 °C. Preferably, the source of the first polymeric material is heated to at most a temperature of 150 °C, preferably at most 160 °C, preferably at most 170 °C, preferably at most 180 °C, preferably at most 190 °C, preferably at most 200 °C, preferably at most 210 °C or preferably at most 210 °C. Preferably, the temperature of the source of the first polymeric material is heated in the range from 140 °C to 180 °C.

Preferably, the rate of production of processed laminated film is in the range of 100-150 15 m/min.

Preferably, the processed laminated film is cooled downstream of the pair of nip rollers. Cooling the processed film quickly as it exits the pair of nip rollers is essential to ensure a uniform film of processed laminate is produced.

Preferably, the cooling means comprises a pair of cooling rollers configured to cool the processed laminated film. This allows both surfaces of the processed laminated film to be cooled as each is passed over a respective surface of the pair of cooling rollers. Preferably the processed laminated film is cooled to ambient temperature. In addition, a pair of cooling rollers permits a change run direction by an angle of at least 45 degrees, preferably at least 50 degrees, preferably at least 60 degrees, preferably at least 70 degrees, preferably at least 80 degrees, preferably at least 90 degrees, preferably at least 100 degrees, preferably at least 110 degrees, preferably at least 120 degrees, preferably at least 130 degrees, preferably at least 140 degrees, preferably at least 150 degrees, preferably at least 160 degrees, preferably at least 170 degrees or preferably at least 180 degrees.

The present invention also provides for a system for performing the method as previously described, suitable for continuously thermally laminating together at least two sheets of polymeric film material.

BRIEF DESCRIPTION OF THE DRAWINGS

The description is given with reference to the accompanying drawings where like numerals are intended to refer to like parts as follows: 2 film forming apparatus 4 source of a first polymeric film material 4a first roller 4b first roller cover 6 source of a second polymeric film material 6a second roller 6b second roller cover 8, 10 pair of nip rollers 11 protective cover 12 processed laminated film 14 heated idling roller 16 second idling roller 18 pair of cooling rollers re-wind roller 20a re-wind roller cover 22 air-compressed bellows 23 chill assembly 24 centrifugal blower web path 26 die cut station 27 indexing take-off table and in which: Figure 1 shows a front view of the apparatus according to a first embodiment of the invention; Figure 2 shows a front view of the component parts of the apparatus according to Figure 1; Figure 3 shows a front view of the apparatus according to an alternative embodiment of the invention; and Figure 4 shows a front view of the component parts of the apparatus according to Figure 3.

DESCRIPTION OF THE INVENTION

Figure 1 shows a front view of the apparatus 2 according to a first embodiment of the invention. The apparatus 2 comprises a first roller 4a with a source of a first polymeric material (not shown) having a first cover 4b, and a second roller 4a with a source of a second polymeric material (not shown) having a second cover 4b.

A protective cover 11 surrounds and protects the inner workings of the apparatus which comprises a pair of nip rollers, a heated idling roller, a second pair of idling rollers, a pair of cooling rollers and a set of air compressed bellows (all of which are not shown) which are interlinked and configured to simultaneously receive the first and second sources of polymeric film material so as to heat and bond them together into a processed laminated film. Details as to how the various component parts are interlinked are described in more detail with reference to Figure 2 below. The advantages of having a protective cover 11 are that it helps to maintain an even operating temperature of the pair of nip rollers within the confines of the protective cover 11.

Also shown in Figure 1 is a re-wind roller 20 with a cover 20a for receiving the finished processed laminated film after the first and second sources of polymeric film material have been heated and bonded to each other under pressure by way of the pair of nip rollers so as to transform the first and second sources of polymeric material into a processed laminated film.

Figure 2 shows a front view of the component parts of the apparatus 2 according to the first embodiment of the invention. The apparatus 2 comprises a source of a first polymeric film material 4 wound around a first roller 4a, and a source of a second polymeric film material 6 wound around a second roller 6a. Both the source of the first polymeric film material 4 and the source of the second polymeric film material 6 are rolls of polyethylene.

The apparatus 2 also comprises a pair of nip rollers 8, 10, consisting of two rollers of differing diameters, to simultaneously receive the first 4 and second 6 polymeric film materials so as to bind the films 4, 6 into a laminate and form a processed laminated film 12, one of the pair of nip rollers 8, 10 being formed from metal 8 and the remaining roller of the pair of nip rollers 8, 10 being formed from a resiliently deformable material 10. In Figure 2, the metal roller 8 is formed from steel and the resiliently deformable material roller 10 is formed from vulcanised rubber.

A heated idling roller 14 is located upstream of the resiliently deformable roller 10 so as to receive the first polymeric film material 4, prior to the first polymeric film material 4 passing over the resiliently deformable material roller 10 of the pair of nip rollers 8, 10. The source of the second polymeric film material 6 is passed over a second idling roller 16 prior to entering the pair of nip rollers 8, 10. The second polymeric film material 6 passes over the metal roller 8 of the pair of the nip rollers 8, 10. The metal nip roller 8 comprises a heating element (not shown). The metal nip roller 8 and the heated idling roller 14 are configured to be heated to temperatures in the range of 140-180 °C. A set of air-compressed bellows 22 is linked to the pair of nip rollers 8, 10 so as to control the gap between the metal roller 8 and the resiliently deformable roller 10.

From Figure 2 it is clear that the metal roller 8 has a larger diameter than the resiliently deformable roller 10. A ratio of the diameters of the metal roller 8 to the resiliently deformable roller 10 is in the range 4:1 to 2:1. The metal roller 8 has a diameter in the range 200 mm to 500 mm, and the resiliently deformable roller 10 has a diameter in the range 100 mm to 300 mm.

The apparatus further comprises a cooling means for the processed laminated film 12 downstream of the pair of nip rollers 8, 10, wherein the cooling means comprises a pair of cooling rollers 18 configured to cool the processed laminated film 12. After passing through the pair of cooling rollers 18, the processed laminated film 12 exiting the nip rollers 8, 10 is wound around a re-wind roller 20.

All individual components and processes of the apparatus are configured to be automated and controlled by way of a computer (not shown).

In use, a supply of the first polymeric material 4 from the first roller 4a is passed around and over the heated idling roller 14 prior to being fed into the gap formed between the metal roller 8 and the resiliently deformable roller 10. Simultaneously, a supply of the second polymeric material 6 from the second roller 6a is passed around and over the second idling roller 16 prior to being passed around the metal roller 8 and into the gap formed between the metal roller 8 and the metal roller 8. The first 4 and second 6 sources of polymeric material, having been heated by the heated idling roller 14 and metal roller 8 respectively, are then bonded to each other under pressure by way of the pair of nip rollers 8, 10 so as to transform the first 4 and second 6 sources of polymeric material into a processed laminated film 12. The processed laminated film 12 exiting the pair of nip rollers 8, 10 is fed into and passed over a pair of cooling rollers 18, so as to cool both sides of the processed laminated film 12, before being fed and wrapped around a re-wind roller 20 for storage/subsequent use.

Figures 3 and 4 show front views of an alternative embodiment of the apparatus 2 according to the invention, but with the following additional features. Figure 3 is analogous to Figure 1 in that it shows the apparatus 2 of the invention, and Figure 4 shows in detail the component parts of the apparatus 2 according to the alternative embodiment of the invention. The apparatus 2 further comprises a chill assembly cooling table 23 and a die cut station 26 in order to cool the processed laminated film 12 exiting the pair of nip rollers 8, 10, rather than passing the processed laminated film 12 over and through the pair of cooling rollers 18.

In use, the processed laminated film 12 exiting the pair of nip rollers 8, 10 is fed into and passed over a pair of cooling rollers 18, so as to cool both sides of the processed laminated film 12 in a manner similar to that previously discussed for the embodiment according to Figure 2.

The processed laminated film 12 exiting the pair of nip rollers 8, 10 travels horizontally through a chill assembly cooling table 23 so as to ensure a finished product which is flat and straight in readiness for cutting by the die cut station 26. Figure 4 also shows that the processed laminated film 12 is reversed back upon itself by passing the processed laminated film 12 over a pair of cooling rollers 18 for further chilling prior to passing along the web path 25 for entry into the die cut station 26. A die cut station 26 is able to cut the processed laminated film 12 into a variety of sizes and shapes as per a user's requirements.

In a further alternative embodiment (not shown), the processed laminated film 12 can be fed and wrapped around a re-wind roller 20 for storage/subsequent use instead of being directed towards the die cut station 26.

An optional centrifugal blower 24 is positioned underneath the chill assembly cooling table 23 in order to blow ambient air into the chill assembly cooling table 23, so as to cool the processed laminated film 12. This can be replaced with an air conditioning unit (not shown) if ambient air is insufficient in order to cool the processed laminated film 12.

Finally, Figure 4 shows an indexing take-off table 27 which simply provides an area for cut sections of the processed laminated film 12 to be collected in batches for packing as per a user's requirements.

Claims

CLAIMS: 1. Film forming apparatus 2 for continuously thermally laminating together at least two sheets of polymeric film material 4, 6, the apparatus 2 comprising: a source of a first polymeric film material 4 wound around a first roller 4a; a source of a second polymeric film material 6 wound around a second roller 6a; a pair of nip rollers 8, 10, consisting of two rollers of differing diameters, to simultaneously receive the first 4 and second 6 polymeric film materials so as to bind the films 4, 6 into a laminate and form a processed laminated film 12, one 8 of the pair of nip rollers 8 being formed from metal and the remaining roller 10 of the pair of nip rollers 8, 10 being formed from a resiliently deformable material; wherein at least one heated idling roller 14 is located upstream of the resiliently deformable roller 10 so as to receive the first polymeric film material 4.
2. Film forming apparatus 2 according to claim 1, wherein the at least one heated idling roller 14 is maintained at a temperature above the metal nip roller 8 temperature so as to heat the first polymeric film material 4 prior to entering the pair of nip rollers 8, 10.
3. Film forming apparatus 2 according to claim 1 or claim 2, wherein the source of second polymeric film material 6 is passed over a second idling roller 16 prior to entering the pair of nip rollers 8, 10.
4. Film forming apparatus 2 according to any of claim 1 to claim 3, wherein the metal nip roller 8 comprises a heating element.
5. Film forming apparatus 2 according to claim 4, wherein the heating element is a water recirculation apparatus flowing through an internal surface of the metal roller 8.
6. Film forming apparatus 2 according to claim 4, wherein the metal nip roller 8 and the at least one heated idling roller 14 are configured to be heated to temperatures in the range of 140-180 °C.
7. Film forming apparatus 2 according to claim 6, wherein the metal nip roller 8 and the at least one heated idling roller 14 are configured to be heated to the same temperature.
8. Film forming apparatus 2 according to any preceding claim, wherein the metal nip roller 8 has a larger diameter than the resiliently deformable roller 10.
9. Film forming 2 apparatus according to claim 8, wherein a ratio of the diameters of the metal nip roller 8 to the resiliently deformable roller 10 is in the range 4:1 to 2: 1.
10. Film forming 2 apparatus according to any preceding claim, wherein the metal nip roller 8 has a diameter in the range 200 mm to 500 mm.
11. Film forming 2 apparatus according to any preceding claim, wherein the resiliently deformable roller 10 has a diameter in the range 100 mm to 300 mm.
12. Film forming 2 apparatus according to any preceding claim, wherein the metal nip roller 8 is formed from steel.
13. Film forming 2 apparatus according to any preceding claim, wherein the resiliently deformable roller 10 is formed from vulcanised rubber.
14. Film forming 2 apparatus according to any preceding claim, wherein the apparatus 2 further comprises a cooling means for the processed laminated film 12 downstream of the pair of nip rollers 8, 10.
15. Film forming 2 apparatus according to any claim 14, wherein the cooling means comprises a pair of cooling rollers 18 configured to cool the processed laminated film 12.
16. Film forming 2 apparatus according to any preceding claim, further comprising a colour print roller to apply ink to at least one of the first 4 or second 6 polymeric film materials.
17. Film forming 2 apparatus according to claim 16, wherein the colour print roller applies ink to the first polymeric film material 4.
18. Film forming 2 apparatus according to any preceding claim, wherein the rate of production of processed laminated film 12 is configured to be in the range of 100-150 m/min.
19. Film forming 2 apparatus according to any preceding claim, wherein the source of the first 4 and second 6 polymeric film material is polyethylene.
20. Film forming 2 apparatus according to any preceding claim, wherein the processed laminated film 12 exiting the pair of nip rollers 8, 10 is cut into portions.
21. Film forming 2 apparatus according to any of claim 1 to claim 19, wherein the processed laminated film 12 exiting the pair of nip rollers 8, 10 is wound around a re-wind roller 20.
22. Film forming 2 apparatus according to any preceding claim, wherein the processed laminated film 12 is free of adhesive.
23. A system comprising the apparatus 2 according to any preceding claim, for continuously thermally laminating together at least two sheets of polymeric film material.