GB2264959A

GB2264959A - Moulding fibrous articles

Info

Publication number: GB2264959A
Application number: GB9204934A
Authority: GB
Inventors: Anthony Michael Bedford; Thomas Rodney Wilshaw
Original assignee: John Cotton
Current assignee: John Cotton
Priority date: 1992-03-06
Filing date: 1992-03-06
Publication date: 1993-09-15
Anticipated expiration: 2012-03-06
Also published as: GB9204934D0; GB2264959B

Abstract

In a method of manufacturing fibrous matting for use in the manufacture of moulded articles, e.g. vehicle panels, fibres are carded (10, 11) and needled (21), and lubricant materials (17) is incorporated into the matting to assist the fibres in sliding smoothly over one another during a subsequent moulding process. The lubricant material (17) preferably comprises a plastics film which is sandwiched between the layers of fibres, for example prior to needling. The matting may be electrostatically sprayed with bonding agent prior to moulding. The perimeter of the matting is tightly clamped in the mould to prevent the escape of steam and gases and assist permeation of the bonding agent. The moulded article may be made by moulding a plurality of layers of the matting, the layers having different orientations. The fibres may be of alignocellulose material, e.g. jute. <IMAGE>

Description

MOULDING The invention relates to moulding, and particularly though not exclusively, to the moulding of panels and other components for the automotive industry.

It is well known to mould panels which comprise fibrous lignocellulosic material bonded together with resin. However the existing products are associated with a number of problems, including the following :1. A very high proportion of resin has to be used, with consequent cost and health hazard problems.

2. It is difficult to thoroughly coat the fibres with resin.

3. Relatively toxic resins have to be used.

We have now developed a novel method and apparatus which offers a number of advantages over the prior art.

According to a first aspect, the invention provides a method of manufacturing fibrous matting for use in the subsequent manufacture of moulded articles, in which fibres are carded and needled, and lubricant material is incorporated into the matting to assist the fibres in sliding smoothly over one another during a subsequent moulding process. This enables a much higher proportion of fibres to be used than in prior art methods, without the matting tearing or cracking during subsequent deep drawing moulding processes.

Preferably the lubricant material comprises a plastics film which is sandwiched between layers of fibres, for example prior to needling.

Preferably the plastics film is in the form of a scrim.

According to à second aspect, the invention provides a method of moulding an article from resin bonded fibres, comprising electro-statically spraying the fibres with a bonding agent in liquid form, the proportion of liquid comprising from 8% to 30% by weight with respect to the weight of the fibres.

Preferably the proportion of liquid is from 10% to 20% by weight.

The fibres may comprise lignocellulosic fibres and the bonding agent may comprise an MDI polymer, as described hereinafter.

The fibres may comprise jute fibres.

Preferably the fibres contain, prior to moulding, from 5% to 150to by weight of moisture.

The preferred moisture content is 10% by weight.

According to a third aspect, the invention provides a method of moulding an article from resin bonded fibres, using moulding tools having a perimeter which is such that the perimeter of the moulded article is tightly clamped, to prevent the escape of steam or other gases during the moulding process, thus assisting permeation of the resin through the fibres.

According to a fourth aspect, the invention provides a method of manufacturing moulded panels, each panel comprising a laminate made up from a plurality of layers, each layer comprising a sheet of fibrous material having different strength and stretch characteristics in different directions, and each sheet being orientated with respect to at least one adjacent sheet such that the laminate has substantially uniform stretch and strength characteristics.

The invention includes apparatus for carrying out the different aspects of the method.

The invention includes moulded articles when produced by the method and/or apparatus of the invention.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which : Figure 1 is a perspective view of a first stage of apparatus for manufacturing moulded articles according to an embodiment of the invention; and Figure 2 is a perspective view of a second stage of the apparatus.

The method and apparatus of this embodiment have been developed for use in manufacturing moulded articles in the form of panels moulded to a specific shape, for example for use as interior panels for automobiles and other vehicles. The primary component of the panels is textile or other fibrous material, for example jute, bonded together by means of a resin, for example comprising methylene bridged polyphenyl polyisocyanates containing diisocyanate, triisocyanate and higher functionality polyisocyanates, referred to hereinafter as MDI.

Referring to Figure 1, the first stage of the method involves producing a substantial supply of needled fibrous matting which can be stored in a roll.

It is well known to produce fibrous matting by a carding, cross-lapping and needling process, but it is an important aspect of this embodiment of the invention that a mat is produced which has at least one layer of plastics film within the matting, and so the apparatus according to this embodiment utilises two carding machines 10 and 11. These are each fed with fibres from a conventional fibre blending bin 12.

A first web 13 of carded fibres is produced by the carding machine 10 and is cross-lapped at 14, in a conventional manner, to produce a bottom layer 15 of cross-lapped fibres suitable for needling. At this point a plastics film feed mechanism 16 lays on to the top of the fibres a plastics film 17, drawn from a supply roll 18. The plastics material, which is thermo-plastic, may be in the form of a continuous sheet but it is preferred that the plastics material is in the form of a scrim. Polypropylene or polyethylene may be used for example.

The second carding machine 11 produces a second layer of carded fibres 19 which is cross-lapped at 20 on to the top of the plastics film 17.

The fibre and plastics sandwich then enters a conventional needling machine 21 and emerges as a continuous coherent mat. The edges of the mat are trimmed by a conventional edge trimming machine 22, and the matting is then wound on to a take up beam by a winding stand 23. Finished rolls of matting can be taken away for storage, for subsequent use in the second stage of the method.

The apparatus shown in Figure 2 carries out several further steps in the method.

Firstly, a roll 24, comprising matting prepared by the apparatus of Figure 1, is mounted on the apparatus and is fed through a spray apparatus 25. Arrangements are made, involving pre-drying of the fibres if necessary, to ensure that the matting 24 contains from 5% to 15%, and preferably 10%, of moisture by weight.

In the spray apparatus 25, two spray arms 26 and 27 rotate in a horizontal plane, about a central axis, spraying a bonding agent onto the fibres. Harmful emissions are reduced by exhaust ducting 28 connected to a protective hood 29. The preferred bonding agent is an MDI polymer.

The arms 26 and 27 carry an electrostatic charge and the conveyor belt 30 which carries the matting is earthed. The bonding agent is thus dispersed electrostatically throughout the thickness of the matting. This is assisted by the fact that the central plastics film is in the form of a scrim.

The bonding agent is added in a ratio of some 10 to 20% of liquid by weight, with respect to the weight of the fibres.

After emerging from the spray apparatus, the continuous matting is cut into panel sections by a guillotine 31. Each panel section 32 is then picked up by a turn-over apparatus 33 and deposited on a stacking table 34. The stacking table 34 is rotatable, according to another important aspect of this embodiment of the invention.

Each panel 32 has quite different strength and stretch characteristics in its longitudinal and transverse planes, because of the way the fibres are orientated during the conventional carding and lapping process. The apparatus and method according to the invention seeks to provide panels having uniform strength and stretch characteristics and this is achieved in this embodiment of the invention by building up a laminate, each layer of the laminate having strength and stretch characteristics which are different to the adjacent laminates. Thus after one laminate 32 has been placed on the stacking table 34, the table is rotated through 900 before the next laminate is placed in position. The table 34 is rotated through 900 each time another laminate is placed on the table. Any desired number of laminates may be stacked up on the table, dependent upon the thickness of panel which it is desired to produce as the end product.

Once an appropriate number of laminates have been stacked, the stack is fed by a conveyor 35 into a specially designed moulding machine 36. The moulding machine 36 includes a press 37 which has an upper tool 38 and a lower tool 39, shaped according to the shape of panel which it is desired to produce.

In the moulding machine 36, pressure is applied to the built-up laminate, as well as heat. The moulding temperature may for example be of the order of 200 C.

According to another important aspect of this embodiment, we have discovered that the MDI reacts with the moisture remaining in the fibres in an expansion process, involving the production of steam, which causes the bonding agent to be rapidly and thoroughly propelled through the fibres. The process has been found to be particularly effective in coating and impregnating jute fibres. Jute fibres are hollow, and it is normally difficult to impregnate their interior.

The process is assisted by ensuring that the perimeters of the upper and lower tool clamp the perimeter of the panel tightly, thus reducing the escape of steam or other gases, and assisting in a pressure build-up within the fibres of the panel.

Conventional impregnation processes have to utilise a substantially greater proportion of resin than of fibre, to ensure that the fibres of the finished panel are thoroughly sealed against the introduction of moisture.

However the use of the spraying technique and moulding technique of the invention enables a much lower percentage of resin to be used, with very considerable cost savings and also a reduction in health hazard.

However, if a panel having a very high proportion of fibres is moulded into a shape which involves significant deformation, using deep drawing tools, the panel is likely to tear. This is where our introduction of the thermoplastics scrim becomes important. During the moulding process, the thermo plastics scrim melts and coats the fibres in a lubricating manner. Thus, even during a deep drawing process, the fibres tend to slide smoothly over one another and a neat, coherent moulded panel is produced, without any rips or cracks.

The process can be used to produce a fairly hard or fairly soft panel, dependent upon the degree of pressure applied. In a typical example, the fibres may be compacted from a normal loft of substantially 10 mm down to a thickness of only 2 to 2.5 mm. The total working range might involve a finished density of from 0.1 to 1.0 kg per cubic centimetre. A density of 0.3 would produce a particularly soft panel and a density of from 0.9 to 1.0 would produce a particularly hard panel.

The reaction of the fibre moisture with the MDI not only produces a propellant effect, but it also accelerates the curing of the MDI.

While the above embodiment has been described with particular reference to jute fibres and MDI, it will be appreciated that the invention could be adapted for use with other fibres and material, for example other lignocellulosic material and for use with other binding agents.

If desired, additional additives may be used, for example biocides, to reduce the risk of the panels deteriorating as a result of mildew if the panels should become damp during use.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of manufacturing fibrous matting for use in the subsequent manufacture of moulded articles, in which fibres are carded and needled and a lubricant material is incorporated into the matting to assist the fibres in sliding smoothly over one another during a subsequent moulding process.

2. A method according to Claim 1 in which the lubricant material comprises a plastics film which is sandwiched between layers of fibres.

3. A method according to Claim 2 in which the plastics film is sandwiched between the layers of fibres prior to needling.

4. A method according to Claims 2 or 3 in which the plastics film is in the form of a scrim.

5. A method of moulding an article from resin bonded fibres, comprising electro-statically spraying the fibres with a bonding agent in liquid form, the proportion of liquid comprising from 8% to 30% by weight with respect to the weight of the fibres.

6. A method according to Claim 5, in which the proportion of liquid is from 10% to 20% by weight.

7. A method according to Claim 5 or 6, in which the fibres comprise lignocellulosic fibres.

8. A method according to any one of Claims 5 to 7, in which the fibres comprise jute fibres.

9. A method according to any one of Claims 5 to 8, in which the fibres contain, prior to moulding, from 5% to 15% by weight of moisture.

10. A method according to Claim 9, in which the fibres contain, prior to moulding, 10% by weight of moisture.

11. A method according to any one of Claims 5 to 10, in which the bonding agent comprises an MDI polymer.

12. A method of moulding an article from resin bonded fibres, using moulding tools having a perimeter which is such that the perimeter of the moulded article is tightly clamped, to prevent the escape of steam or other gases during the moulding process, thus assisting permeation of the resin through the fibres.

13. A method of manufacturing moulded panels, each panel comprising a laminate made up from a plurality of layers, each layer comprising a sheet of fibrous material, having different strength and stretch characteristics in different directions, and each sheet being orientated with respect to at least one adjacent sheet such that the laminate has substantially uniform stretch and strength characteristics.

14. Fibrous matting manufacturing apparatus for use in the subsequent manufacture of moulded articles, the apparatus comprising: means for carding and needling fibres; and means for incorporating lubricant material into the matting to assist the fibres in sliding smoothly over one another during a subsequent moulding process.

15. Apparatus according to Claim 14, in which the lubricant material comprises a plastics film which is sandwiched between layers of fibres.

16. Apparatus according to Claim 15, in which the plastics film is sandwiched between the layers of fibres prior to needling.

17. A method according to Claim 15 or 16, in which the plastics film is in the form of a scrim.

18. Apparatus for moulding an article from resin bonded fibres, comprising means for electro-statically spraying the fibres with a bonding agent in liquid form, in which the proportion of liquid comprises from 8 % to 30% by weight with respect to the weight of the fibres.

19. Apparatus according to Claim 18, in which the proportion of liquid is from 10% to 20% by weight.

20. Apparatus according to Claim 18 or 19, in which the fibres comprise lignocellulosic fibres.

21. Apparatus according to any one of Claims 18 to 20, in which the fibres comprise jute fibres.

22. Apparatus according to any one of Claims 18 to 21, in which the fibres contain, prior to moulding, from 5% to 15% by weight of moisture.

23. Apparatus according to Claim 22, in which the fibres contain, prior to moulding, 10% by weight of moisture.

24. Apparatus according to any one of Claims 18 to 23, in which the bonding agent comprises an MDI polymer.

25. Apparatus for moulding an article from resin bonded fibres, the apparatus comprising moulding tools having a perimeter which is such that the perimeter of the moulded article is tightly clamped to prevent the escape of steam or other gases during moulding, thus assisting permeation of the resin through the fibres.

26. Apparatus for manufacturing moulded panels, each panel comprising a laminate made up from a plurality of layers, each layer comprising a sheet of fibrous material, having different strength and stretch characteristics in different directions, the apparatus having means for orientating each sheet with respect to at least one adjacent sheet such that the laminate has substantially uniform stretch and strength characteristics.

27. A method of manufacturing fibrous matting substantially as described herein with reference to Figure 1.

28. A method of moulding an article from resin bonded fibres substantially as described herein with reference to Figures 1 and 2.

29. Fibrous matting manufacturing apparatus for use in the subsequent manufacture of moulded articles, substantially as described herein with reference to Figure 1.

30. Apparatus for moulding an article from resin bonded fibres substantially as described herein with reference to Figures 1 and 2.

31. An article produced in accordance with the methods of any one of Claims 1 to 4 or any one of Claims 5 to 11, or Claims 12, 13, 27 or 28, or using the apparatus of any one of Claims 14 to 17, 18 to 24, or 25, 26, 29 or 30.