GB2585226A

GB2585226A - Compression moulding

Info

Publication number: GB2585226A
Application number: GB1909600.7A
Authority: GB
Inventors: M Weager Brendon; M Hare Christopher; Abbasian Tala
Original assignee: NETCOMPOSITES Ltd
Current assignee: NETCOMPOSITES Ltd
Priority date: 2019-07-03
Filing date: 2019-07-03
Publication date: 2021-01-06
Also published as: GB201909600D0

Abstract

A method of forming a shaped article by compression moulding comprises: (a) locating a unitary component 2 comprising first and second fibrous sheets 21, 22, and a core of resin material 23 in a compression mould comprising one or more recesses 33a, 33b, 33c; (b) heating the unitary component; (c) applying pressure to the unitary component within the mould; and (d) removing the shaped article from the compression mould (3). During compression, the resin material forming the core is able to penetrate through the fibrous sheets to fill the one or more recesses such that placement of separate discrete portions of resin material adjacent the recesses is not required. A unitary component for use in compression moulding comprising first and second fibrous sheets and a core of resin material is further provided.

Description

COMPRESSION MOULDING

This invention relates generally to a method of forming a shaped article using compression moulding and to a component for use in a method of forming a shaped article using compression moulding.

Compression moulding is a widely known technique used to form shaped articles. In a typical process, a polymer-based material is placed in the cavity of an open two-part mould. The polymer-based material may be either a thermoset resin or a thermoplastic resin, which io may be added to the cavity of the mould in the form of granules, putty, or preforms. The mould is then closed, and pressure is applied to force the polymer-based material into contact with all areas of the cavity of the closed mould. The two-part mould is then opened, and the resulting shaped article is removed.

It is known to form composite shaped articles using compression moulding. Compression moulding processes using composite materials may be used to fabricate large and intricate components, for example, automotive interior components, e.g. door panels, dashboard panels. These components require a range of intricately shaped protrusions and rebates to be formed during the moulding process.

GB2502413 A discloses the use of two individual pre-consolidated fibrous sheets (each of which comprise a woven fabric and a polymer) and a feature forming material (comprising a polymer), which is provided separately to the fibrous sheets, for use in a compression moulding process. It is taught that, ideally, the feature forming material is positioned adjacent a recess in the mould, having a similar volume so that is forms a feature on the final article. It is also taught that the fibrous sheets need not be pre-consolidated and instead, matrix-forming material (e.g. polymer) may be provided in a granular or powder form to the mould.

The compression moulding process described in GB2502413 A is effective for fabricating shaped articles comprising composite materials. However, the process requires several individual components (i.e. the individual fibrous sheets and separate feature forming material), which must be carefully positioned in the mould to correspond to the recesses such that the features in the final shaped article are effectively formed.

It is therefore a first non-exclusive object of the invention to provide a simplified method of compression moulding a shaped article formed from composite materials, and a component for use in the method.

Accordingly, a first aspect of the invention provides a method of forming a shaped article by moulding (e.g. compression moulding or vacuum moulding), the method comprising: a. locating a unitary component comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material in a mould, e.g. a compression mould, which comprises one or more recesses; b. heating the unitary component; c. applying pressure to the unitary component within the mould, e.g. compression mould; d. removing a shaped article formed from the unitary component from the mould, e.g. compression mould.

It has been surprisingly found that, during step c. of the method in which the compression mould is closed and pressure is applied to the unitary component, the resin material forcing the core is able to penetrate through the first fibrous sheet and/or the second fibrous sheet to fill the one or more recesses in the compression mould to form the shaped article. This is in direct contrast to the teachings of the prior art, which teaches that placement of specific discrete portions of resin material adjacent the recesses is crucial to successfully forming those features of the shaped article. In an embodiment, step b is performed before step a.

A further aspect of the invention provides a method of forming a or the unitary component, the unitary component may be fabricated in a process comprising the following steps: (i) extruding a sheet of polymer material; (ii) locating a first fibrous sheet on the first major surface of the extruded sheet of polymer material, and locating a second fibrous sheet on the second major surface of the extruded polymer material to form a sandwich sheet; (iii) preferably feeding the sandwich sheet through one or more temperature-controlled rollers.

In embodiments, the method may further comprise pre-heating the unitary component to at least partially melt the resin material.

In embodiments, step b. may comprise heating the unitary component within the compression mould at a constant or non-constant temperature.

In embodiments, Step c. may comprise applying a minimum pressure of 0.3 MPa (3 bar) to the unitary component within the compression mould.

In embodiments, Step c. comprises applying a pressure of between 0.3MPa (3 bar) to 15 MPa (150 bar), e.g. between any one of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, or 14.0 MPa to any one of 15.0, 14.0, 13.0, 12.0, 11.0, 10.0, 9.0, 8.0, 7.0, 1() 6.0, 5.0, 4.0, 3.0, 2.0, or 1.0 MPa. In embodiments, Step c. comprises applying a pressure of 2.0 MPa.

The method may further comprise step e. shearing the edges of the unitary component to form the shaped article. In embodiments, step e. may be performed before step d.

A further aspect of the invention provides a shaped article formed using the method of the invention.

A yet further aspect of the invention provides a shaped article comprising a planar portion and at least one shaped portion, the shaped article comprising a first fibrous sheet and a second fibrous sheet encased within a matrix of resin material, the first and second fibrous sheets being in substantially parallel relations in the planar portion, wherein a portion of one of the fibrous sheets extends into the at least one shaped portion such that the first and second fibrous sheets are in non-parallel relations in the at least one shaped portion.

The planar portion may be a flat portion or may, for example, be formed as a smoothly curved portion. The shaped portion is characterised by the non-parallel relations of the first and second fibrous sheet materials.

We have surprisingly found that when moulding a unitary component comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material the core of resin material is able to penetrate through the respective fibrous sheet into the shaped cavity of the mould and, when it does so, causes the fibrous sheet to deform into the shaped cavity. This is beneficial because it provides strength to the so-formed shaped portion.

A yet further aspect of the invention provides a unitary component for use in a moulding process (e.g. compression moulding or vacuum moulding) to form a shaped article, the unitary component comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material.

Advantageously, the unitary component of the invention may be may be used in a moulding process, e.g. a compression moulding process, to form a shaped article comprising a range of differently sized and located recesses. The same unitary component may be used without modification to form a variety of differently shaped articles.

In embodiments, the first fibrous sheet and/or the second fibrous sheet are provided as peripheral layers on the major outer surfaces of the component. In alternative embodiments, the first fibrous sheet and/or the second fibrous sheet are at least partially or fully embedded within the core of resin material.

In embodiments, the unitary component further comprises an nth fibrous sheet, e.g. a third, fourth, fifth, sixth and so on, fibrous sheet.

The first fibrous sheet, the second fibrous sheet, and where present the nth fibrous sheet may comprise or consist of the same material or materials. In alternative embodiments, the first fibrous sheet and the second fibrous sheet may comprise or consist of different materials. Alternatively, the first fibrous sheet and the second fibrous sheet comprise or consist of the same material. In embodiments, the nth fibrous sheet comprises or consists of a different material or different materials to one or both of the first fibrous sheet and/or the second fibrous sheet.

In embodiments, the nth fibrous sheet may be located between, for example substantially centrally between, the first fibrous sheet and the second fibrous sheet. In alternative embodiments, the nth fibrous sheet may be located closer to, for example adjacent or proximate, the first fibrous sheet than the second fibrous sheet. In alternative embodiments, the first fibrous sheet may be located between the nth fibrous sheet and the second fibrous sheet.

In embodiments, each of the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet may comprise threads or yarns arranged substantially parallel to one another.

In embodiments, each of the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet may comprise a sheet of woven and/or comingled fabric, i.e. comprising warp and weft yarns. In embodiments wherein each of the first fibrous sheet and the second fibrous sheet comprise a sheet of woven fabric, the weave of the first fibrous sheet may be aligned or may be offset with the weave of the second fibrous sheet.

In embodiments comprising a woven fabric, the orientation of the weave may comprise fibres running at 0 degrees, 45 degrees and/or 90 degrees, or any combination of these.

In embodiments, each of the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet may comprise a sheet of non-woven material, e.g. each of the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet may comprise a sheet of stitched, needle-punched, and/or bonded textiles.

In embodiments, the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet comprise or consist of synthetic fibres, e.g. glass fibre, carbon fibre, aramid fibre, basalt fibre, and/or one or more polymer fibres, for example polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyether ether ketone (PEEK), Nylon 6 (PA6), Nylon 66 (PA66).

In embodiments, the first fibrous sheet and/or the second fibrous sheet comprise or consist of natural fibres, e.g. cotton, wool, flax, hemp, bamboo, jute, sisal, kenaf or a combination thereof. In embodiments, the first fibrous sheet and/or the second fibrous sheet may comprise or consist of man-made cellulose fibres, e.g. viscose and/or Rayon.

In embodiments, the core of resin material comprises a polymer, e.g. a thermoplastic resin or a thermoset resin. For example, the core of resin material may comprise one or more of polyether ether ketone (PEEK), polyamide, polyvinylchloride (PVC), polystyrene, polyethylene, polypropylene, polyacrylonitrile, acrylonitrile butadiene styrene (ABS), epoxy resin, melamine resin, silicone resin. The core of resin material may include a thermoset resin selected from one or more of an unsaturated polyester resin, a vinylester resin, a PolyFurfurylAlcohol (PFA), and/or a polyurethane variant. The core of resin material may include a thermoplastic resin selected from one or more of a polycarbonate, a polyester, a polyethylenimine (PEI), a polyaryletherketone (PAEK).

In embodiments, the resin material may further comprise reinforcing fibres, e.g. discontinuous reinforcing fibres. The reinforcing fibres within the resin material comprise between 1 to 60 wt.% of the core of resin material, e.g. between any one of 1, 2, 3, 4, 5, 10, 20, 30, 40, or 50 wt.% to any one of 60, 50, 40, 30, 20, 10, 5, 4, 3, 2 wt.% of the core of resin material. The reinforcing fibres may have a length of 1 nm to 3 mm. e.g. between 10 nm to 3 mm, or 100 nm to 3 mm.

In embodiments, the first fibrous sheet and/or second fibrous sheet may comprise a combination of fibres (e.g. carbon and/or glass fibres) commingled or mixed with polymer fibres.

In embodiments, the reinforcing fibres comprise or consist of one or more of cotton, wool, flax, hemp, bamboo, jute, sisal, kenaf, carbon fibres, glass fibres, aramid fibres, wood fibres, cellulose fibres, nano-cellulose, and/or basalt.

The core of resin material and/or the reinforcing fibres may further include other constituents, for example, to improve the aesthetics (e.g. the colour), the flow, adhesion, fire retardance, and/or UV functionality such as carbon black, talcum, maleic anhydride, aluminium, and/or phosphorous.

In embodiments, the core of resin material is between 0.5 to 5 mm thick. In embodiments, the unitary component has a total thickness of 0.7mm to 5 mm.

In embodiments, the tensile modulus of the unitary component may be from 3 to 75GPa, e.g. between any one of 3, 4, 5, 10, 20, 30, 40, 50, 60, 70 GPa, to any one of 75, 70, 60, 50, 40, 30, 20, 10, 5, or 4 GPa. Advantageously, the tensile modulus may be controlled depending on the selection of materials used for the fibrous sheets and/or the core of resin material. This may depend on the application of the resulting shaped article.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms "may", "and/or", "e.g.", "for example" and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any io originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1A is a method of compression moulding a door panel component according to the prior art; Figure 1B is a further method of compression moulding a door panel component according to the prior art; Figure 2 is a component for use in compression moulding to form a shaped article; Figure 3 is the component of Figure 2 located in a compression mould; Figure 4 is a shaped article formed using the component of Figure 2 with the compression mould of Figure 3; Figure 5 is a method of compression moulding the component of Figure 2 using the compression mould of Figure 3 to form a shaped article; Figure 6 is a photograph of a shaped article according to an Example of the invention; Figure 7 is a photograph of a shaped article according to an Example of the invention Referring now to Figure 1A and Figure 1B, there is shown two methods 1A, 1B of compression moulding a door panel component, according to the prior art document GB2502413.

Referring first to Figure 1A, there is shown a mould 10 comprising a first mould part 10a and a second mould part 10b. The second mould part 10b comprises a recess 13. There is also shown a first woven flax sheet 11a, a second woven flax sheet 11b, and a polypropylene sheet 12.

The prior art method 1A shown in Figure 1A comprises sequentially positioning the first woven flax sheet 11a, the polypropylene sheet 12, and the second woven flax sheet 11b between the first mould part 10a and a second mould part 10b. The first woven flax sheet 11a, the polypropylene sheet 12, and/or the second woven flax sheet 11b may be preheated before positioning in mould 10 to melt the polypropylene sheet 12 such that the polypropylene polymer flows into the first and second woven flax sheets 11a, 11b.

io Additionally or alternatively, heat may be applied within the mould 10. The mould 10 is then closed and pressure P is applied in the direction indicated by the arrows shown. The polypropylene sheet 12 forms a flowable mass, which is able to fill the recess 13 of the second mould part 10b. After an appropriate amount of time, the mould 10 is opened to remove the door panel component (not shown), which comprises a feature (not shown) formed by the recess 13.

Referring now to Figure 1 B, there is shown a second method 1B of compression moulding a door panel component (not shown), according to the prior art, wherein like-references to those described for Figure 1A are indicated with a prime (I The differences are described below.

In this prior art method 1B, the first mould part 10a' comprises a first recess 13a and the second mould part lOb' comprises a second recess 13b. The polypropylene sheet in this method is provided as a first polypropylene sheet 12a and a second polypropylene sheet 12b.

In the prior art method 1B shown in Figure 1 B, the first woven flax sheet 11 a' and the second woven flax sheet 11 b' are positioned between the first mould part 10a' and a second mould part lOb'. The first polypropylene sheet 12a is positioned adjacent the first recess 13a and the second polypropylene sheet 12b is positioned adjacent the second recess 13b.

Once the mould 10' is closed for the application of heat and/or pressure P' in the direction indicated by the arrows shown, the molten polypropylene of the first polypropylene sheet 12a is able to flow into the first recess 13a of the first mould part 10a' and the molten polypropylene of the second polypropylene sheet 12b is able to flow into the second recess 13b of the second mould part 10b', such that a first feature (not shown) is formed by the first recess 13a, and a second feature (not shown) is formed by the second recess 13b in the door panel component (not shown) fabricated in this process.

This prior art method teaches selectively placing the polypropylene sheets 12a, 12b adjacent the recesses 13a, 13b such that the molten polypropylene is able to flow to form features in the resulting door panel component.

We understand that the material forming the fibrous sheets is not displaced out of parallel io relations during the moulding operation.

Referring now to Figure 2, there is shown a component 2 for use in compression moulding to form a shaped article. The component 2 comprises a first fibrous sheet 21, a second fibrous sheet 22, and a core of resin material 23.

In this embodiment, each of the first fibrous sheet 21 and the second fibrous sheet 22 are provided as peripheral layers on the major outer surfaces of the component 2.

The first fibrous sheet 21 and the second fibrous sheet 22 are embedded within the core of resin material 23 such that the component 2 is unitary. The first and second fibrous sheet 21, 22 may be partially embedded in the core of resin material 23.

Referring now to Figure 3, there is a shown the component 2 of Figure 2 located in a compression mould 3. The compression mould 3 comprises a first mould part 31 and a second mould part 32.

The compression mould 3 further comprises a first recess 33a, a second recess 33b, and a third recess 33c. The first recess 33a and the second recess 33b are located in the first mould part 31. The third recess 33c is located in the second mould part 32.

The component 2 is located in between the first mould part 31 and the second mould part 32.

Referring also to Figure 4, there is shown a shaped article 4 formed using the compression mould 3. The shaped article 4 comprises moulded features 34a, 34b, 34c corresponding to the first, second, and third recesses 33a, 33b, 33c of the compression mould 3. It can be seen that the fibrous mats 21, 22 has been forced out of the plane in the region of the moulded features 34a, 34b, 34c. [NOTE JC -These need to be pointed out on the pictures] Referring also to Figure 5, there is shown a method of compression moulding a shaped article 4 from the component 2 of Figure 2 using the compression mould 3 of Figure 3, according to a second embodiment of the invention.

The method 4 comprises the following steps: io Step 1: Providing a unitary component (2) comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material.

Step 2: Locating the unitary component (2) in a compression mould (3) comprising one or more recesses (33a, 33b, 33c).

Step 3: Heating the unitary component (2). This enables the core of resin material (23) of the unitary component (2) to at least partially melt.

Step 4: Applying pressure to the unitary component (2) within the compression mould (3). Step 5: Removing the shaped article (4) from the compression mould (3).

It has been surprisingly found that during Step 4 of the method of the invention, the core of resin material 23 flows through the first and second fibrous sheets 21, 22 into recesses 33a, 33b, 33c to form the moulded features 34a, 34b, 34c of the shaped article 4. This was unexpected because the prior art specifically teaches that additional portions of resin material are required to form moulded features of the shaped article. We have also found that the first and second fibrous sheets 21, 22 are deformed out of the plane parallel relations in the region of the adjacent recesses 33a, b, c of the mould which beneficially increases the robustness (e.g. strength) of the shaped portion.

To further exemplify the invention, reference is also made to the following non-limiting Examples:

Example 1

Referring now to Figure 6, there is shown a shaped article according to Example 1 of the invention. The shaped article 6 was formed in a method according to the invention. The unitary component had carbon fibre sheets and a core of polypropylene and short carbon fibres.

There is shown a formed portion 61 comprising a first fibrous sheet 62 and a core of resin material 63. It is shown that the core of resin material 63 has penetrated through the first fibrous sheet 62 such that the first fibrous sheet 62 is deformed into the shaped cavity to form the formed portion 61. This is beneficial because it provides strength to the formed portion 61.

The core of resin material 63 comprises carbon fibres and polypropylene. It is advantageous for the carbon fibre to penetrate through the first and/or second fibrous sheets. It has been found that shaped articles formed in this way exhibit greater mechanical performance.

It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention.

It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.

Claims

CLAIMS1. A method of forming a shaped article by compression moulding, the method comprising: e. locating a unitary component in a compression mould comprising one or more recesses, the unitary component comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material; f. heating the unitary component; g. applying pressure to the unitary component within the compression mould; h. removing the shaped article from the compression mould.
A method according to Claim 1, further comprising pre-heating the unitary component to at least partially melt the resin material.
3. A method according to any preceding Claim, wherein step b. comprises heating the unitary component within the compression mould at a constant temperature.
A method according to any preceding Claim, step c. comprises applying a minimum pressure of 20 bar to the unitary component within the compression mould.
A method according to any preceding Claim, further comprising step e. shearing the edges of the unitary component to form the shaped article.
A method according to Claim 5, wherein step e. is performed before step d.
A shaped article formed using the method of any of Claims 1 to 6.
8. A unitary component for use in compression moulding to form a shaped article, the unitary component comprising a first fibrous sheet, a second fibrous sheet, and a core of resin material.A unitary component according to Claim 8, wherein the first fibrous sheet and/or the second fibrous sheet are provided as peripheral layers on the major outer surfaces of the component.A unitary component according to Claim 8 or 9, further comprising an n1 fibrous sheet.A unitary component according to Claim 8 to 10, wherein the nth fibrous sheet is located substantially centrally between the first fibrous sheet and the second fibrous sheet.A unitary component according to Claim 8 to 11, wherein each of the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet comprise a sheet of woven fabric.A unitary component according to Claim 8 to 12, wherein the first fibrous sheet and/or the second fibrous sheet and/or a or the nth fibrous sheet comprise synthetic fibres, e.g. glass fibre, carbon fibre, aramid fibre.A unitary component according to Claim 8 to 13, wherein the first fibrous sheet and/or the second fibrous sheet comprise natural fibres, e.g. cotton, wool, flax, hemp, bamboo, jute, sisal, kenaf or a combination thereof A unitary component according to Claim 8 to 14, wherein the core of resin material comprises a polymer, e.g. a thermoplastic resin or a thermoset resin.A unitary component according to Claim 8 to 15, wherein the core of resin material comprises one or more of polyether ether ketone (PEEK), polyethylenimine, polyamide, polyvinylchloride, polystyrene, polyethylene, polypropylene, polyacrylonitrile, acrylonitrile butadiene styrene, epoxy resin, melamine resin, silicone resin.17. A unitary component according to Claim 8 to 16, wherein the resin material further comprises reinforcing fibres, e.g. discontinuous reinforcing fibres.18. A unitary component according to Claim 17, wherein the reinforcing fibres within the resin material comprise between 1 to 60 wt.%, e.g. between 5 to 50 wt.%. 10. 11. 12. 13. 14. 15. 16.19. A unitary component according to Claim 8 to 18, wherein the reinforcing fibres comprise or consist of one or more of cotton, wool, flax, hemp, bamboo, jute, sisal, kenaf, carbon fibres, glass fibres, aramid fibres.20. A unitary component according to Claim 8 to 19, wherein the core of resin material is between 0.5 to 5 mm thick.21. A unitary component according to Claim 8 to 20, wherein the unitary component has a total thickness of 0.7mm to 5 mm.22. A unitary component according to Claim 8 to 21, wherein the tensile modulus of the component is between 3 to 75GPa, e.g. between 10 to 75 GPa.