NZ209750A

NZ209750A - Flat die for production of multi-coloured,multilayer,plastics films

Info

Publication number: NZ209750A
Application number: NZ209750A
Authority: NZ
Inventors: R Scheibling
Original assignee: Siamp Cedap Reunies
Priority date: 1983-10-03
Filing date: 1984-10-02
Publication date: 1986-05-09
Also published as: FR2552707A1; ES290734Y; IE55733B1; BR8404965A; EP0136959A3; DE3465269D1; ES290734U; EP0136959A2; EP0136959B1; FR2552707B1; ATE28820T1; AU564920B2; JPH0527530B2; AU3378084A; IE842465L; JPS6096430A

Abstract

1. A flat die for the extrusion of multi-layered and multi-coloured films, sheets or plates of plastics material, in which die channels (12, 13, 14), for supplying plastics materials of different colours to an intermediate layer (A, B, C), open into a cavity positioned transversely with respect to the direction of extrusion, which leads into a smooth passage (15) in which the intermediate layer of the film, sheet or plate is formed, and which, before emerging from the outlet (6) of the die, joins with two other ducts (16, 19) which are linked to channels (18, 22) for distributing the plastics materials intended for forming a support layer (D) and a covering layer (E) respectively, the above-mentioned cavity containing a means for spreading out, in the intermediate layer (A, B, C), the streams of plastics material admitted by the supply channels (12, 13, 14), the flat die being characterised in that said means comprises a thin fixed plate (7) the upper face of which is provided with raised teeth (9) having a height and a width which decrease from their upstream end to their downstream end where they end in a point, the teeth (9) delimiting trapezoidal spaces (10), the profile of which, considered in a plane which is parallel to the base plane of the plate (7), increases from upstream to downstream in such a way that the spaces (10) are in contact at their downstream ends, each of these spaces (10) being supplied with coloured plastics material (A, B, C) by the channels (12, 13, 14) which introduce the plastics material into the trapezoidal spaces at their upstream ends and moving in the direction of extrusion.

Description

Priority Date(s): . IQ Complete Specification Filed: <?. .iCJ.24" Publication Date P.O. Journal, No: Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "MULTI-LAYER DIE FOR THE PRODUCTION OF MULTI-COLOURED PLASTIC FILMS, SHEETS OR PANELS" -i, WE SIAMP CEDAP REUNIES, a Societe Anonyme, of 4 Quai Antoine ler - Monte-Carlo (Monaco), France, hereby declare the invention, for which -I-/we pray that a patent may be granted to me-Zus, and the method by which it is to be performed, to be particularly described in and by the following statement (folfowed by page I A.} - ^ar MULTI-LAYER DIE FOR THE PRODUCTION OF MULTI-COLOURED PLASTIC' FILMS, SHEETS OR PANELS The subject of the invention is a die making it possible to produce plastic films, sheets or panels which 5 take the form of contiguous longitudinal strips of different colour from one another and which appear on one and the same supporting layer of a single colour and under one and the same layer of transparent material.

Such films, sheets or panels have many uses, es-10 pecially in the packaging industry, since they are suitable, among other things, for the manufacture of boxes or pots by means of forming, and these boxes can each have several shades or have different colours from one box to another in the same set of boxes.

To obtain the same effects in these particular uses, it is known to use either plastic sheets on which strips of different colours are printed side by side, or plastic sheets on which strips of different colours are laminated. In both cases, the sheets are very expensive, 20 and their quality is not sufficient to enable them to withstand thermoforming operations.

The invention overcomes these disadvantages by means of a special arrangement made in a die belonging to the category of flat mult i-layer dies, that is to say 25 those in which several plastic feed channels open into flattened transverse chambers which are made in the body of the die and which themselves open into a common gap delimited by the lips of the die and determining the thickness of the multi-layer film or sheet. 209750 According to the Invention, there is placed 1n the body of the die a plate of which the transverse edge teeth, located downstream possesses/ in the manner of a comb, which teeth end in a point and which delimit trapezoidal 5 spaces '- , the cross-section of which increases in a downstream direction, in such a way that these spaces are contiguous at their downstream ends, and into each of respective which opens a/coloured-plastic feed channel, these spaces communicating directly with a flattened transverse passage, farms . in which a sheet or fiIm/resuIting from the juxtapo sition of streams of plastic coming from the abovementioned spaces, this flattened passage subsequently communicating further feed with other* passages connected to/: channels feeding supporting-layer material and :a covering materia I, respectively 15 before opening into b gap in the die. ;This plate arranged in the form of a comb constitutes an essential element of the die, since it acts as a distributor of the coloured plastic, to produce a sheet or a film formed by strictly contiguous strips differing 20 from one another in their colour. ;If the sheet or film has only two colours for its various strips, the comb alone is sufficient to distribute the coloured plastic. If, on the other hand, the number of colours is greater than two, according to another 25 characteristic of the invention the comb is then associated with at least one other plate which is located above it and in the same chamber as the latter in the die and which, in combination with it, carries out the distrir / - ;i < • ;bution of a plastic of a certain colour. ;* • The number of these superimposed plates depends on the number of colours to be provided in the film or the sheet. The comb and one plate correspond to three colours, the comb and two plates to four colours/ and so 5 on and so forth .

Moreover, the invention will be properly understood and its advantages as well as other characteristics will emerge clearly from the following description made with reference to the attached diagrammatic drawing which 10 illustrates an embodiment of this die and in which: Figure 1 is a perspective view of a portion of a sheet according to the invention; Figures 2 and 3 are highly diagrammatic views, in perspective and in plan respectively, illustrating the 15 arrangement which makes it possible to manufacture this sheet; ,Figures 4 and 5 are views of a die for manufacturing this sheet, in longitudinal section along 4-4 of Figure 5 and in cross-section along 5-5 of Figure 4 20 respectively.

As shown in Figure 1, a sheet according to the invention comprises six plastic strips (A, B, C, A, B, C) included between an opaque base layer CD) and a transparent covering layer (E> . The strips (A, B, C) are of 25 different colours and show through the transparent layer (E). The various materials used can be of any type, for example polystyrene.

A flat die is used for the manufacture of this multi-layered and multi-coloured sheet, and as is known this die comprises an upper body (1), a middle body (2) , a lower body (3) and two lips (4, 5) which delimit the gap (6) of adjustable height determining the thickness of the sheet.

The plastic feed channels are arranged in the various bodies of the die, and there are five of these channels, that is to say three channels for the three coloured plastics, one channel for the opaque base layer plastic and one channel for the transparent covering 10 plastic.

It is the arrangement of these various channels and of the system for distributing the various streams of plastic which constitutes the special feature of the die.

The upper body (1) and the middle body (2) de-15 limit a chamber which opens out on the rear face of the die and in which two plates (7 and 8) are superimposed. One (7) has on its front edge a profile similar to that of a comb, since it is provided with teeth (9) ending in a point and delimiting trapezoidal spaces (10), into 20 each of which opens a coloured-plastic feed channel. With regard to the three coloured plastics (A, B, C), these are distri-buted via three longitudinal channels (12, 13, 14) which are each subdivided into two channels within the die, since the sheet must possess six coloured strips. To make 25 it easier to understand this arrangement, the channels distributing the plastic of colour (A) are represented by broken lines in Figure 3, those distributing the plastic of colour (B) are represented by solid lines, and those distributing the plastic of colour (C) are represented by 209750 dot-and-dash Lines.

Of these channels, the one (12) intended fop the plastic of colour (A) is arranged in the upper face of the middle body (2) of the die and in the lower face of 5 the comb plate (7); the one (13) intended for the plastic of colour (B) is arranged in the lower face of the upper body (1) and in the upper face of the intermediate plate (8); and the one (14) intended for the plastic of colour (C) is arranged in the upper face of the comb plate 10 (7) and in the lower face of the intermediate plate (8).

Each channel (12, 13, 14) is profiled in the downstream direction, in order to open by each of its two branches into a space (10) delimited between two teeth (9) of the comb plate (7) . As shown in Figure 3, it is 15 possible, from that moment, for the plastic coining from each channel to be transformed in this space (10) into a strip which is joined, at the end of each tooth of the co;nb, to the adjacent strip, thus forming a web.

Downstream of the comb (7), this web formed as a 20 result of the juxtaposition of these strips moves into a passage (15) which is delimited by the upper $>ody (1) and the middle body (2) of the die and which opens into another passage (16) delimited by the middle body (2) and the upper lip (4).

This passage (16) communicates at its front end with a transverse channel (17), into which opens a longitudinal channel (18), via which the plastic intended for X- . . L: /v" constituting the covering layer (d) of is introduced; at its downstream end, 209750 opens into the gap (6) between the two lips (4, 5) of the die; furthermore, there opens into this gap apassage (19) which extends from a transverse channel (21) fed via a longitudinal channel (22) with plastic intended for 5 constituting the supporting layer (e) of the final multi-co loured sheet.

It goes without saying that the invention is not limited to the sole embodiment of this die described above by way of example; on the contrary, it embraces all its 10 alternative embodiments, in particular whatever the means provided for adjusting the speed of movement of the various streams and strips of plastic, and these means can consist especially of individual valves associated with various ch anne I s . 7 209750

Claims

WHAT WE CLAIM IS:

1. Multi-layer die of the flat type, for the production of multi-coloured plastic films, sheets or panels, in which several plastic feed channels open into flattened transverse chambers which are arranged in the body of the die and which themselves open into a common gap delimited by the lips of the die and determining the thickness of the multi-layer film or sheet, characterised in that there is placed in the body of the die a plate of which the transverse edge located downstream possesses teeth, in a manner of a comb, which teeth end in a point and delimit trapezoidal spaces the cross-section of which increases in a downstream direction, in such a way that these spaces are contiguous at their downstream ends, and into each of which opens a respective feed channel for introducing a stream of coloured plastic, these spaces communicating directly with a flattened transverse passage, in which a sheet or film forms resulting from the juxtaposition of the streams of plastic coming from the above-mentioned spaces, this flattened passage subsequently communicating with other passages connected to further feed channels for a supporting-layer material and a covering material, respectively, before opening into a gap in the die.

2. Die according to claim 1, for the production of a film, sheet or panel having more than two colours, characterised in that the comb is associated with at least one other plate which is located above it and ] - 8 - 209750 in the same chamber as the latter in the die and which, in combination with it, carries out the distribution of a plastic of a certain colour.

3. Die according to claim 2, characterised in that 5 it consists of three bodies, namely an upper body, a middle body and a lower body, of which the upper body and middle body delimit a parallele-piped chamber which receives, from the bottom upwards, the comb plate and said other plate or plates, said feed channels for introducing streams of 10 coloured plastic into the spaces of the comb being arranged respectively (a) under the comb plate, (b) between this plate and one of said other plates and (c) above another of said other plates, the spaces of the comb which are fed by said feed channels opening into said transverse 15 passage delimited by the upper body and the middle body of the die, and in that two of said further channels arranged in the upper body and the lower body for introducing the streams of supporting-layer plastic and covering plastic respectively, open into said other passages said 20 communicating with/transverse passage, said other passages ending in said common gap delimited by the two lips of the die.

4. Die according to any one of claims 1 to 3, characterised in that a valve for adjusting the flow of plastic 25 is placed on each of the said feed channels and further feed channels.

5. Die according to claim 1 substantially as herein described with reference to the^accompanying drawings. AP REUNIES