WO2019028544A1

WO2019028544A1 - Coextrusion mandrel with resin channel for extrusion die

Info

Publication number: WO2019028544A1
Application number: PCT/CA2018/050813
Authority: WO
Inventors: Felix Guberman; Alex Mann
Original assignee: Tronoplast Technologies Inc.
Priority date: 2017-08-08
Filing date: 2018-07-04
Publication date: 2019-02-14

Abstract

A mandrel is provided for use with a die in the production of a multi-layered film. The mandrel comprises a body portion having a plurality of resin channels positioned within the body portion, each resin channel permitting the flow of resin from flow distribution passageways to the exterior surface and into a resin passageway. A flow director is positioned within each resin channel. The flow director is configured to assist in distributing resin flowing through the resin channel into a planer formation so as to form a resin sheet within the body portion prior to the resin entering the resin passageway. Resin passing through the plurality of resin channels forms a plurality of resin sheets that together collectively form a resin layer concentric about the exterior surface of the body portion. The resin layer is directed within the resin passageway toward the upper face of the body portion.

Description

TITLE

[0001] COEXTRUSION MANDREL WITH RESIN CHANNEL FOR EXTRUSION DIE

FIELD

[0002] This invention relates generally to extrusion dies and related mandrels, for the extrusion of plastic film.

BACKGROUND

[0003] Typically, the more layers a film has, the better the mechanical and barrier properties the film is expected to have. Multilayer blown film technology is used for producing films, for use as shrink film, stretch/silage film, stretch hood film and for producing shipping bags. Films for these applications traditionally have been comprised of 1 to 3 layers. More recently, a 5-layer film has been developed, demonstrating superior mechanical properties. Following this trend, it has been found that further mechanical enhancements can be achieved with even more layers. Unfortunately, the traditional way of increasing the number of layers in a film, where each extruder feeds an individual layer, can be complicated and costly. [0004] Typical coextrusion dies form an individual layer about a mandrel before that layer joins other layers. The dies, therefore, have a number of mandrels equal to the number of layers. As a result, the greater the number of desired layers, the greater the number of required mandrels. The greater the number of mandrels a die has, generally the longer the distance the melt has to travel. The downside of this is that there is more of a chance for the melt to degrade when it is forced to travel over a greater distance. An increased number of mandrels also increases the complexity of the die assembly, making the die more difficult to clean, repair and service. Furthermore, when one extruder is to deliver the melt to multiple layers, commonly, a splitter block has to be used.

[0005] U.S. Patent Pub No. 2013/0243894 Al discloses a method of creating multiple layers where the melt flows from each extruder and splits to create a plurality of individual layers. Each layer separates from a mandrel or distributing disk before it meets other layers. As a result, the wetted area grows significantly. This has a negative effect on the process as the increase in residence time results in the melt having longer exposure to heat, with the mandrel having poor self- cleaning and high back pressure properties.

[0006] Existing methods of splitting layers and forming a multilayer structure are known in flat die technology. These methods involve sandwiching multiple layers of film simultaneously across the die. Unfortunately, forming a film layer over a round or similar mandrel tends to create a seam line, or lines, which make the multilayer film structure not uniformly distributed.

[0007] Another attempt to split layers before forming is described in US Pat No. 6,409,953 Bl . Here, each layer is formed on a round mandrel and distributed over the mandrel in spiral grooves, with the spirals alternating and belonging to different layers. Unfortunately, the layers are not concentric, creating a nonuniform film.

SUMMARY

[0008] The invention provides a mandrel for a die used in the production of a multi-layered film, the die having a die body with an interior surface and a longitudinal bore for receiving the mandrel, a resin passageway defined between the mandrel and the interior surface of the die body when the mandrel is received within the longitudinal bore. The mandrel comprises a body portion having a longitudinal axis, the body portion having an upper face and a lower face with an exterior surface extending therebetween. One or more flow distribution passageways are oriented generally longitudinally within said body portion, said one or more flow distribution passageways open to said lower face of said body portion for fluid communication with one or more sources of resin. A plurality of resin channels are positioned within said body portion, each resin channel having a first end in fluid communication with one or more of said flow distribution passageways, a second end open to said exterior surface of said body portion permitting the flow of resin from said one or more flow distribution passageways to said exterior surface and into said resin passageway, and a flow director positioned between said first end and said second end, said flow director configured to assist in distributing resin flowing through said resin channel into a planer formation at an angle relative to said longitudinal axis so as to form a resin sheet within said body portion prior to said resin entering said resin passageway. Resin passing through said plurality of resin channels forms a plurality of resin sheets that together collectively form a resin layer concentric about the exterior surface of the body portion, the resin layer directed within the resin passageway toward the upper face of the body portion.

[0009] In another aspect there is provided a method for producing a multi- layered film using a mandrel within a die body, the mandrel having a longitudinal axis and an upper and a lower face with an exterior surface therebetween, the mandrel received within a longitudinal bore of the die body and forming a resin passageway therebetween. The method comprises introducing resin into the mandrel through one or more flow distribution passageways within the mandrel, directing the resin from the one or more flow distribution passageways through a plurality of resin channels towards the exterior surface of the mandrel, distributing the resin, via a flow director in each of said resin channels, into a planar formation at an angle relative to said longitudinal axis so as to form a plurality of resin sheets within said body portion, said plurality of resin sheets together forming a resin layer, and directing the resin layer into the resin passageway and towards the upper face.

[0010] In another aspect, there is provided a die used in the production of a multi-layered film, the die having a die body with an interior surface and a longitudinal bore for receiving a mandrel, a resin passageway formed between the mandrel and the interior surface of the die body when the mandrel is received within the longitudinal bore. The die comprises the die body having a longitudinal axis, an upper end, and a lower end with the interior die surface extending therebetween and defining the longitudinal bore. One or more flow distribution passageways are oriented generally longitudinally within said die body, said one or more flow distribution passageways open to said lower end of said die body for fluid communication with one or more sources of resin. A plurality of resin channels are positioned within said die body, each of said resin channels having a first end in fluid communication with one or more of said one or more flow distribution passageways, a second end open to said interior surface of said die body permitting the flow of resin from said one or more flow distribution passageways to said interior surface and into said resin passageway, and a flow director positioned between said first end and said second end, said flow director configured to assist in distributing resin flowing through said resin channel into a planer formation at an angle relative to said longitudinal axis so as to form a resin sheet within said die body prior to said resin entering said resin passageway. Resin passing through said plurality of resin channels forms a plurality of resin sheets that together form a resin layer concentric about the interior surface of the die body, the resin layer directed within the resin passageway toward the upper end of the die body.

[0011] Further aspects of the invention will become apparent from the following description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of examples, to the accompanying drawings which show exemplary embodiments of the present invention in which :

[0013] Figure 1 is a top perspective view of an extrusion die head according to an example embodiment of the present invention.

[0014] Figure 2 is a cross sectional view of Figure 1 along line C-C.

[0015] Figure 3 is a top perspective view of a mandrel according to an example embodiment of the present invention.

[0016] Figure 4 is a cross section view of Figure 3 along line D-D.

[0017] Figure 5 is an enlarged view of portion E of Figure 4.

[0018] Figure 6 is a side view of the section shown in Figure 4.

[0019] Figure 7 is an enlarged view of portion F of Figure 6.

[0020] Figure 8 is an upper perspective view of a single die layer of the mandrel according to Figure 3.

[0021] Figure 9 is an enlarged view of portion G of Figure 8. [0022] Figure 10 is a plan view of Figure 8.

[0023] Figure 11 is a cross sectional view of Figure 10 along line H-H . [0024] Figure 12 is a cross sectional view of Figure 10 along line J-J. [0025] Figure 13 is a cross sectional view of Figure 10 along line K-K. [0026] Figure 14 is a side view of Figure 10 along line L-L. [0027] Figure 15 is an enlarged view of portion M of Figure 14. DESCRIPTION

[0028] The present invention may be embodied in a number of different forms. The specification and drawings that follow describe and disclose some of the specific forms of the invention.

[0029] In the attached Figures, there is shown a mandrel 100 for use in a die assembly 50, which is used in the production of a multi-layered film (not shown).

Die assembly 50 includes a die body 52 having a longitudinal bore 54 (for receiving mandrel 100. Die body 52 has an interior surface 56. A resin passageway 58 is formed between the exterior surface of the mandrel and interior surface 56 when mandrel 100 is received within longitudinal bore 54. Resin passageway 58 ends at die lip 60, from which the multi-layered film is extruded.

[0030] Die assembly 50 further includes resin sources 62 and 64, which are in fluid communication with mandrel 100. As will be understood by one skilled in the art, one or more resins sources, in fluid communication with mandrel 100, could be used. In some embodiments, resin sources may also be in fluid communication with die body 52.

[0031] Mandrel 100 includes body portion 12 having longitudinal axis Z, the body portion having upper face 16 and lower face 14 with exterior surface 18 extending therebetween. Mandrel 100 includes multiple flow distribution passageways 20 oriented generally longitudinally within body portion 12. Flow distribution passageways 20 are open to lower face 14 of body portion 12 for fluid communication with the sources of resin (not shown) at openings 26. When mandrel 100 is used in association with die assembly 50, flow distribution passageways 20 are in fluid communication with the resin sources via openings 26.

[0032] Mandrel 100 may further include a base 40. When mandrel 100 is received within longitudinal bore 54, lower face 14 is positioned adjacent to the resin sources, and upper face 16 is positioned adjacent to die lip 60, downstream from lower face 14.

[0033] While mandrel 100 is shown as generally cylindrical, it will be understood by one skilled in the art that rather than the generally cylindrical body depicted, mandrel 100 could alternatively be of a different shape, including generally conical, frusto-conical or have a generally symmetrical surface of revolution .

[0034] As will also be understood by one skilled in the art, rather than being oriented parallel within body portion 12, flow distribution passageways 20 may alternatively be non-parallel to longitudinal axis Z. Flow distribution passageways 20 may also maintain their diameter as they extend towards upper face 16 or they may taper as they extend from lower face 14 towards upper face 16.

[0035] Mandrel 100 has a plurality of generally planar resin channels 102 within body portion 12. Each resin channel 102 has a first end 104 in fluid communication with one of flow distribution passageways 20. Each resin channel 102 also has a second end 106, which is open to exterior surface 18 of body portion 12, permitting the flow of resin from flow distribution passageway 20 to exterior surface 18. Each resin channel 102 further has a flow director 108 positioned between first end 104 and second end 106. Flow directors 108 are configured to assist in distributing resin evenly through their associated resin channels 102 into planer formations at an angle relative to longitudinal axis Z. In this manner, resin sheets (not shown) are formed within body portion 12 prior to the resin entering resin passageway 58. As seen in Figures 4-7, resin channels 102 may be positioned generally perpendicular to longitudinal axis Z so that the related resin sheets are formed generally perpendicular to longitudinal axis Z. It will thus be appreciated that resin sheets formed by adjacent resin channels 102 about mandrel 100 will combine as they pass through the respective resin channels to form a single, generally planar, resin layer that enters resin passageway 58.

[0036] As best seen in Figures 8-10, resin channel 102 may be in the shape of an alluvial fan, spreading from first end 104 towards second end 106. Adjacent to, and extending from, first end 104 is a pair of diverging walls 110. Diverging walls 110 form a portion of resin channel 102 and help to divert resin flow towards second end 106 in a generally alluvial flow pattern to aid in the formation of the associated resin sheet.

[0037] Each resin channel 102 further includes a first resin reservoir 112 adjacent its diverging walls 110 and positioned upstream from flow director 108 (see Figures 8 and 9). First resin reservoir 112 diverges away from first end 104 so as to encourage resin to flow radially away from first end 104 or to "pre-distribute" the resin prior to encountering flow director 108. As shown in Figures 11-13, in one embodiment, first resin reservoir 112 decreases in cross-sectional area in a radial and a circumferential direction away from first end 104.

[0038] In the embodiment shown, flow director 108 includes a dam 114, that extends in a circumferential direction relative to longitudinal axis Z, or generally concentric to exterior surface 18, and downstream from first resin reservoir 112. Dam 114 is shown to be an elevated ridge having a height which varies as it extends generally circumferentially away from first end 104, as best seen in Figures 11-15.

[0039] In this particular embodiment, the height of dam 114 symmetrically decreases as it extends away from first end 104. Figure 11 depicts a radial cross- section view through first end 104 where the height of dam 114 is at its highest. Figure 12 shows a radial cross-section that is spaced apart from first end 104, in which the height of dam 114 is lower than in Figure 11. Figure 13 depicts a radial cross-sectional view through a lateral edge of resin channel 102 where there is no dam. It will be appreciated that the described structural dam 114 will assist to evenly and radially direct or spread, without fully obstructing, the resin away from first end 104 towards the corresponding second end 106. The radial spreading of the resin by dam 114 thereby assists in the formation of the resin sheet within body portion 12.

[0040] While flow director 108 is shown to be a dam or an elevated ridge 114 in the depicted embodiment, one skilled in the art would recognize that flow director 108 may instead have a different structure or shape which aids in directing and radially spreading resin away from first end 104 towards second end 106. For example, flow director 108 may instead comprise a ceiling converging towards the floor or ribs radially extending from first end 104.

[0041] Resin channel 102 may also include a second resin reservoir 116 adjacent to its second end 106. As best seen in Figures 11-13, second resin reservoir 116 is generally shallower than first resin reservoir 112 and is positioned downstream from dam 114. Resin which pools in second resin reservoir 116 helps to equalize the melt flow speed and encourages smooth and simultaneous flow of the newly formed resin sheet through second end 106.

[0042] Each resin channel 102 may also include a lip portion 118 at second end 106. As shown, lip portion 118 extends slightly towards upper face 16. Lip portion 118 helps to direct the resin sheet towards upper face 16 when the resin sheet exits through second end 106 into resin passageway 58.

[0043] To form a multi-layered film, after resin is introduced into mandrel 100 through the one or more flow distribution passageways 20, the resin is directed from flow distribution passageways 20 through resin channels 102 toward exterior surface 18. The resin is distributed, radially spread, or the flow is directed, by flow director 108 into a planar formation at an angle relative to longitudinal axis Z to form a resin sheet within body portion 12. In the depicted embodiment, flow director 108 directs the resin into a planar formation generally perpendicular to longitudinal axis Z. The resin sheet, which will join with other adjacent resin sheets to form a unified resin layer, then flows into resin passageway 58 towards upper face 16. In this manner, the resin enters resin passageway 58 as a substantially unified layer.

[0044] The resin sheets which form a unified resin layer flow from resin channels which are positioned an approximately equal distance from lower face 14 of body portion 12. [0045] As best seen in Figures 8-10 and 14-15, each dam is connected to adjacent dams that are positioned within body portion 12 at generally the same distance from lower face 14. The repeating increase and decrease in the height of the dams collectively results in a dam structure that undulates within body portion 12 generally parallel to exterior surface 18.

[0046] In the embodiment shown, each second resin reservoir 116 and each second end 106 is in fluid communication with adjacent second resin reservoirs and adjacent second ends, respectively, and is positioned within body portion 12 at generally the same distance from lower face 14. In this manner, second ends 106 collectively form a ring opening 120 at exterior surface 18.

[0047] Resin channels 102 may be arranged and positioned within body portion 12 at discrete positions along the length of longitudinal axis Z (i.e. at predetermined distances from lower face 14) such that they form individual die layers 38 (see Figure 8). Any one die layer 38 is made up of generally equally spaced resin channels 102. Each of the resin channels within any single die layer 38 are positioned on mandrel 100 generally at the same distance from lower face 14.

[0048] While in Figures 4-7 each die layer 38 is depicted as being positioned on body portion 12 generally parallel to lower face 14, one skilled in the art would understand that as long as resin channels 102 in one die layer are in fluid communication with the adjacent resin channels within the same die layer and form ring opening 120, resin channels 102 may be positioned at differing distances from lower face 14. For example, in an alternative embodiment (not shown), a die layer 38 may be positioned on mandrel 100 at an angle relative to longitudinal axis Z. Because the resin channels in one die layer are in fluid communication with the adjacent resin channels within the same die layer, when resin flows through each of first ends 104 of the die layer and past the dam ring (as depicted by the arrows in Figure 10), the resin will form multiple resin sheets (not shown) within body portion 12. As the resin sheets spread and flow toward their respective second ends 106, each resin sheet will eventually meet a resin sheet flowing from the connected and adjacent resin channel 102. In this manner, the resin sheets will join and form a generally unified resin layer within body portion 12. This unified resin layer is then directed by lip portions 118 into resin passageway 58, towards upper face 16 and die lip 60.

[0049] Die layers 38 are stacked along longitudinal axis Z from lower end 14 towards upper end 16. Resin flowing from each die layer 38 forms a separate unified resin layer, which is directed into resin passageway 58. Resin flowing from the die layer closest to lower end 14 forms a resin layer which enters resin passageway 58 first. Each subsequent die layer 38 stacked above then forms a concentric resin layer between the exterior surface 18 and the resin layer formed by the die layer below. Accordingly, a plurality of resin layers concentric about exterior surface 18 can be simultaneously formed and directed into resin passageway 58 towards upper face 16, and discharged as a multi-layered film (not shown) through die lip 60.

[0050] As additional resin layers are directed into resin passageway 58, it will be understood that the width of resin passageway 58 will increase as it extends towards die lip 60. In the embodiment of in Figure 3 the circumference of mandrel exterior surface 18 decreases as it extends from lower face 14 towards upper face 16. Thus, the circumference of die interior surface 56 may remain essentially the same or may increase as it extends towards die lip 60. Alternatively, the internal diameter of die interior surface 56 could increase as it extends towards die lip 60, while the diameter of the mandrel exterior surface 18 remains the same or decreases from lower face 14 to upper face 16.

[0051] As noted, each flow distribution passageway 20 can be in fluid communication with different resin sources. Different types of resin can be simultaneously fed into mandrel 100 via different flow distribution passageways 20, and delivered by resin channels 102 to form a multi-layered film product (not shown) with layers having different physical and chemical properties. As shown in Figures 1 and 2, a number of resin types can be simultaneously fed into mandrel 100 via the flow distribution passageways. As well, flow distribution passageways 20 can be configured within mandrel 100 such that a wide variety of multi-layered films, with varying resin sequences and a varying number of resin layers, can be created. Multi-layered film products made by using the present invention could have, for example, the following film layer structures, where A, B, and C represent different resin types:

• A-B-C-B-C-B-C;

• A-A-B-B-A-A-B-B-B-A-A-A-B-B-B;

• A-B-B-C-C-C-B-B-A; and

• A-B-C-C-C-C-C-C-C-C-A.

[0052] Each flow distribution passageway could also be in fluid communication with the same resin source so that a multi-layered film product can be formed from n-layers of the same resin, for example: A-A-A-A-A-A-A-A-A-A. Other structures made from other combinations of resins are possible. [0053] The mandrel described herein is oriented vertically. However, it will be understood that the mandrel could be oriented horizontally or in any one of a variety of other orientations.

[0054] Mandrel 100 has been generally described as a single piece or a unitary component. In an alternative embodiment, mandrel 100 may be comprised of separate and separable mandrel components, adapted to fit together such that, when assembled, they form mandrel 100. In this way, the mandrel may be disassembled to facilitate cleaning. Die body 52, in like manner, may also be comprised of separate and separable die body components, which are adapted to fit together such that the die body components may be assembled to form die body 52.

[0055] In the die assembly described above, the mandrel possesses the primary features necessary to form a resin layer (i.e. the flow distribution passageways, and the resin channels, etc.). In an alternative embodiment, not shown, the die body, rather than mandrel 100, may be in fluid communication with the resin sources and the die body could contain the flow distribution passageways and the resin channels etc. to form a resin layer as described above. [0056] In this manner, the die body shares longitudinal axes Z with mandrel

100 and, similar to mandrel 100, has a lower end and an upper end with an interior surface extending therebetween. The die body has one or more flow distribution passageways oriented generally longitudinally therein, with the one or more flow distribution passageways open to the lower end for fluid communication with a source of resin. The die body may also have a plurality of resin channels, each which has a first end in fluid communication with at least one of the flow distribution passageways and a second end open to the interior surface, thereby permitting the flow of resin from the flow distribution passageway to the interior surface in a manner similar to that described above. The plurality of resin channels may be positioned within the die body and be operatively associated with the second end. Each of the resin channels is configured to assist in directing resin exiting the second end into the resin passageway 58 about the interior surface. As in the case of mandrel 100 described above, the resin delivered through the first end of each resin channel of the die body is directed by diverging walls past a first resin reservoir, directed to radially spread within each resin channel by a flow director, in this case a dam, subsequently forming a plurality of resin sheets. The resin sheets are directed past second resin reservoirs and joined together to form a generally unified resin layer. The resin sheets are then directed into the resin passageway 58 by respective lip portions at the second ends, thereby forming a concentric resin layer about the interior surface.

[0057] In a further alternative embodiment, not shown, both the die body and the mandrel may be in fluid communication with the resin sources and comprise the arrangement of features (i.e. the flow distribution passageways and the resin channels etc.) necessary to form a resin layer in the manner described above. In this manner, both the body portion of the mandrel and the die body could include resin channels, about which molten resin could simultaneously flow to form separate concentric resin layers or "ring openings". The resin channels from both the mandrel and the die body would direct their respective resin layers into the resin passageway 58 towards the die lip. Such a "hybrid" system may help to reduce the required height of the mandrel when producing a film with a given number of layers, thereby helping to reduce the overall size of the die assembly.

[0058] It is to be understood that what has been described are the preferred embodiments of the invention. The scope of the claims should not be limited by the preferred embodiments set forth above, but should be given the broadest interpretation consistent with the description as a whole.

Claims

CLAIMS I CLAIM :

1. A mandrel for a die used in the production of a multi-layered film, the die having a die body with an interior surface and a longitudinal bore for receiving the mandrel, a resin passageway being defined between the mandrel and the interior surface of the die body when the mandrel is received within the longitudinal bore, the mandrel comprising :

a body portion having a longitudinal axis, the body portion having an upper face and a lower face with an exterior surface extending therebetween;

one or more flow distribution passageways oriented generally longitudinally within said body portion, said one or more flow distribution passageways open to said lower face of said body portion for fluid communication with one or more sources of resin;

a plurality of resin channels within said body portion, each resin channel having :

a first end in fluid communication with one or more of said flow distribution passageways,

a second end open to said exterior surface of said body portion permitting the flow of resin from said one or more flow distribution passageways to said exterior surface and into said resin passageway; and

a flow director positioned between said first end and said second end, said flow director configured to assist in distributing resin flowing through said resin channel into a planer formation at an angle relative to said longitudinal axis so as to form a resin sheet within said body portion prior to said resin entering said resin passageway;

wherein resin passing through said plurality of resin channels forms a plurality of resin sheets that together collectively form a resin layer concentric about the exterior surface of the body portion, the resin layer directed within the resin passageway toward the upper face of the body portion.

The mandrel as claimed in claim 1, wherein said flow director is configured to assist in distributing resin into said planer formation generally perpendicular to said longitudinal axis.

The mandrel as claimed in claim 2, wherein each of said resin channels includes a pair of diverging walls which configure said resin channel generally in the form of an alluvial fan .

The mandrel as claimed claim 2, wherein said flow director comprises a dam oriented generally concentric to said exterior surface and positioned between said first end and said exterior surface.

5. The mandrel as claimed in claim 4, wherein each of said resin channels further comprises a first resin reservoir adjacent its first end and upstream from said dam.

6. The mandrel as claimed in claim 5, wherein the height of said dam decreases as it extends away from the first end.

7. The mandrel as claimed in claim 6, wherein each of said resin channels further comprises a second resin reservoir positioned between said dam and said second end.

8. The mandrel as claimed claim 7, wherein each of said resin channels further comprises a lip portion at its second end, said lip portion helping to direct said resin sheets towards said upper face when said resin sheets exit through said second end.

9. The mandrel as claimed claim 8, wherein the resin sheets which form a concentric resin layer flow from resin channels which are positioned an approximately equal distance from said lower face.

10. A method for producing a multi-layered film using a mandrel within a die body, the mandrel comprising a body portion having a longitudinal axis, an upper face and a lower face, with an exterior surface extending therebetween, the mandrel received within a longitudinal bore of the die body and forming a resin passageway between the mandrel and the interior surface of the die body, the method comprising :

introducing resin into the mandrel through one or more flow distribution passageways within the mandrel;

directing the resin from the one or more flow distribution passageways through a plurality of resin channels towards the exterior surface of the mandrel;

distributing the resin, via a flow director in each of said resin channels, into a planar formation at an angle relative to said longitudinal axis so as to form a plurality of resin sheets within said body portion, said plurality of resin sheets together forming a resin layer; and

directing the resin layer into the resin passageway and towards the upper face.

The method of claim 10, wherein the resin in each of said resin channels is distributed into a planar formation generally perpendicular to said longitudinal axis.

The method of claim 11, wherein directing of the resin from the one or more flow distribution passageways comprises directing the resin through one or more resin channels which are positioned an approximately equal distance from said lower face.

13. The method of claim 12, wherein the distributing the resin comprises spreading said resin from said first end in an alluvial fan formation towards said second end.

14. Use of the mandrel of claim 1 for performing the method of claim 10.

15. A die used in the production of a multi-layered film, the die having a die body with an interior surface and a longitudinal bore for receiving a mandrel, a resin passageway formed between the mandrel and the interior surface of the die body when the mandrel is received within the longitudinal bore, the die comprising :

the die body having a longitudinal axis, an upper end, and a lower end with the interior die surface extending therebetween and defining the longitudinal bore;

one or more flow distribution passageways oriented generally longitudinally within said die body, said one or more flow distribution passageways open to said lower end of said die body for fluid communication with one or more sources of resin;

a plurality of resin channels within said die body, each of said resin channels having :

a first end in fluid communication with one or more of said one or more flow distribution passageways, a second end open to said interior surface of said die body permitting the flow of resin from said one or more flow distribution passageways to said interior surface and into said resin passageway; and a flow director positioned between said first end and said second end, said flow director configured to assist in distributing resin flowing through said resin channel into a planer formation at an angle relative to said longitudinal axis so as to form a resin sheet within said die body prior to said resin entering said resin passageway;

wherein resin passing through said plurality of resin channels forms a plurality of resin sheets that together form a resin layer concentric about the interior surface of the die body, the resin layer directed within the resin passageway toward the upper end of the die body.

16. The die as claimed in claim 15, wherein said flow director is configured to assist in distributing resin into said planer formation generally perpendicular to said longitudinal axis.

17. The die as claimed in claim 16, wherein each of said resin channels includes a pair of diverging walls which configure said resin channel generally in the form of an alluvial fan.

18. The die as claimed in claim 16, wherein said flow director comprises a dam orientated generally concentric to said interior surface and positioned between said first end and said interior surface.

19. The die as claimed in claim 18, wherein each of said resin channels further comprises a first resin reservoir adjacent its first end and upstream from said dam.

20. The die as claimed in claim 19, wherein the height of said dam decreases as it extends away from the first end.

21. The die as claimed in claim 20, wherein each of said resin channels further comprises a second resin reservoir positioned between said dam and said second end.

22. The die as claimed claim 21, wherein each of said resin channels further comprises a lip portion at its second end, each of said lip portions helping to direct said resin sheet towards said upper end when said resin sheet exits through its second end.

23. The die as claimed claim 22, wherein the resin sheets which form a concentric resin layer flow from resin channels which are positioned at an approximately equal distance from said lower end. A mandrel according to claim 1 in combination with a die according to cla 15, wherein the mandrel is received within the longitudinal bore of the die.