EP2627811A1

EP2627811A1 - Fibre mats

Info

Publication number: EP2627811A1
Application number: EP11773307.1A
Authority: EP
Inventors: Karim Behlouli
Original assignee: Eco Technilin Sas
Current assignee: Eco Technilin Sas
Priority date: 2010-10-13
Filing date: 2011-10-12
Publication date: 2013-08-21
Also published as: GB201017306D0; WO2012049457A1

Abstract

A method of making a fibre mat, such as a non-woven fibre mat, comprising: (i) laying a plurality of layers of fibre web in a stack, each of the layers having a first surface edge, wherein each layer is laid at a position offset from the previous layer such that a first surface of the stack includes the first surface edge of each layer; and (ii) providing reinforcing yarn to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. The product of the method is a stack of layers of fibre web, each of the layers having a first surface edge, each layer of the stack being offset from the adjacent layers such that a first surface of the stack includes the first surface edge of each layer, the stack having reinforcing yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. Also disclosed is an apparatus for carrying out the method.

Description

FIBRE MATS

BACKGROUND TO THE INVENTION Field of the invention

The present invention relates to fibre mats, methods for making fibre mats, and the use of fibre mats. Related art

Fibre mats, such as non-woven fibre mats, are known. For example, non-woven fibre mats may be made from synthetic fibres, such as glass and/or

polypropylene fibres. Alternatively or additionally, non-woven mats may be made from natural fibres, such as flax and/or hemp fibres.

Many non-woven mats are made by a process which includes a consolidation step, for example a mechanical consolidation step such as needle punching. In an example process, fibres may be carded by passing them through a card, which is a comb-like structure, to form a fibre web. This can serve to disentangle and straighten the fibres. Subsequently, the fibres are consolidated into a mat, for example by needle punching. The fibres of several layers of fibre web may be consolidated together. In order to strengthen non-woven mats, reinforcement may be provided. For example, TenCate Polyfelt PGM-G, available from TenCate, is a mechanically bonded polypropylene non-woven reinforced with glass filament (provided in a woven layer). The glass filament reinforcement is applied to the surface of the nonwoven mat after it has been manufactured, for example after mechanical bonding.

Providing reinforcement to nonwoven mats after formation requires an additional processing step or steps, which can increase the time and cost of manufacture. Separate manufacturing equipment and space may be required. Reinforcing yarn provided to a non-woven mat after it is formed may not be sufficiently integrated into the mat to provide desired structural integrity. SUMMARY OF THE INVENTION

The inventors have devised the present invention in order to address one or more of the above problems.

The inventors have realised that an improved fibre mat can be produced if the fibres of the mat are consolidated (e.g. mechanically such as by needle punching) after a reinforcing yarn is provided. This can lead to better integration of the reinforcing yarn in the mat and consequently can provide mats with improved mechanical properties.

Therefore, in a first preferred aspect, the present invention provides a method of making a fibre mat, for example a non-woven fibre mat, the method comprising providing a reinforcing yarn to the mat and then performing consolidation of the fibres of the mat. The consolidation step may be mechanical, for example needle punching the mat. Alternatively, the consolidation step may be thermal, for example some of the fibres or components of the fibres may be melted by heating, e.g. in an oven. The present inventors have also devised an adaptation to a standard method of making a fibre mat which allows reinforcing yarn to be provided to the mat without the need for additional processing steps or significant adaptation of the equipment. Fibre mats are often produced by a method including a step of laying down layers of fibre web, for example web produced in a carding machine, by spunbonding or by meltblowing, in a stack of overlying layers. For example, these layers can be laid using equipment known in the art as a cross-lapper. Typically, the layers are laid such that each subsequent layer is offset from the previous layer. In this way, as the stack of layers is generated, an edge of each layer remains exposed on the top surface of the stack.

The present inventors have realised that reinforcing yarn may be provided to a fibre web layer near to the edge of the layer. The stack is then generated in a manner which ensures that the edge of the fibre web layer is located at or near to the top surface of the stack. Consequently, the reinforcing yarn is located at or near to the top surface of the stack. In turn, the reinforcing yarn is located at or near to a surface of the fibre mat.

Similarly, it will be understood that the opposite edges of the fibre web layers end up on the bottom surface of the stack, and so reinforcing yarn provided near to these edges of the fibre web layers consequently is located at or near to the bottom surface of the stack. In turn, the reinforcing yarn is located at or near to a surface of the fibre mat. Conveniently, in the present invention, the reinforcing yarn can be provided as the layers are laid, or just before they are laid, without the need for significant changes to the laying equipment.

Accordingly, in a second preferred aspect, the present invention provides a method of making a fibre mat, such as a non-woven fibre mat, comprising:

(i) laying a plurality of layers of fibre web in a stack, each of the layers having a first surface edge, wherein each layer is laid at a position offset from the previous layer such that a first surface of the stack includes the first surface edge of each layer; and

(ii) providing reinforcing yarn to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer.

In this way, the reinforcing yarn may lie at or near to the first surface of the stack. As described in more detail below, the location of reinforcing yarn at or near to the surface of a stack and/or a fibre mat can provide particularly advantageous bending properties. In contrast, EP-A-1900863 describes a method of making textile comprising the formation of an electrodeposited intercalated layer across the whole width of a fibre web, in order to produce a textile combining the physical properties of the fibre web and the intercalated layer. As the

intercalated layer is formed across the whole width of the fibre web, if this fibre web is laid into a stack as described above, the intercalated layer will extend through the depth of the stack. The present invention is particularly advantageous as it can provide mats which exhibit comparable or improved tensile strength, improved bending properties (e.g. increased bending modulus) and improved impact resistance, for example compared to non-reinforced mats. The present inventors have realised that the stack of layers of fibre web produced in the method of the second preferred aspect is a novel product.

Accordingly, in a third preferred aspect the present invention provides a stack of layers of fibre web, each of the layers having a first surface edge, each layer of the stack being offset from the adjacent layers such that a first surface of the stack includes the first surface edge of each layer,

the stack having reinforcing yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. In this way, the reinforcing yarn may lie at or near to the first surface of the stack.

It will be understood that the stack of layers may subsequently be processed further in order to produce a fibre mat. For example, the further processing may include compression to reduce height (e.g. by apparatus known in the art as a tacker), consolidation of the fibres for example by mechanical processing such as punching, impregnation with a binder or other chemical and/or shaping/moulding. For example, the fibre mat may be pressed and formed into a panel (and it will be understood that the term fibre mat as used herein includes such a panel.) Accordingly, it is understood that the stack of the third aspect may be an intermediate product.

However, the layers may remain discernable in the fibre mat product, depending on the effect of any subsequent processing of the stack after the layers are laid. Accordingly, it is understood that the stack of layers of the third preferred aspect may be a fibre mat, for example a non-woven fibre mat. (Here, a non-woven fibre mat includes a mat in which the fibres have been consolidated, for example mechanically consolidated such as by needle punching.) Description herein of preferred features of the stack are to be understood to apply equally to fibre mats (whether or not layers are discernable), and vice versa, unless the context demands otherwise.

In a fourth preferred aspect, the present invention provides a fibre mat, such as a non-woven fibre mat, obtained or obtainable by a method according to one of the first or second preferred aspects.

In a further preferred aspect, the present invention provides apparatus for making a fibre mat such as a non-woven fibre mat, the apparatus comprising a laying assembly for laying a plurality of layers of fibre web in a stack, each of the layers having a first surface edge, the laying assembly being arranged to lay each layer at a position offset from the previous layer such that a first surface of the stack includes the first surface edge of each layer; and

a yarn source arranged to provide reinforcing yam to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. In this way, the reinforcing yarn lies at or near to the first surface of the stack. In another aspect, the present invention provides use of a stack according to the third preferred aspect or a fibre mat according to the fourth preferred aspect in a constructional application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc. In another aspect, the present invention provides use of a stack according to the third preferred aspect or a fibre mat according to the fourth preferred aspect in an acoustical control application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc. In another aspect, the present invention provides use of a stack according to the third preferred aspect or a fibre mat according to the fourth preferred aspect in a fire safety application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc. In another aspect, the present invention provides use of a stack according to the third preferred aspect or a fibre mat according to the fourth preferred aspect in a thermal insulation application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc. Further optional features relating to the present invention will now be set out. These may be combined (either singly or in any combination) with any aspect of the invention unless the context demands otherwise.

The stack may have a second surface, opposed to the first surface. For example, the first surface may be the top surface of the stack, and the second surface may be the bottom surface of the stack. Similarly to the first surface, the second surface may include a second surface edge of each layer. Reinforcing yarn may be supplied to the second surface, in a similar manner to the first surface. Accordingly, further reinforcing yarn may be provided to one or more of the layers at a position away from the centre of the layer toward or at the second surface edge of the layer, such that the reinforcing yarn lies at or near to the second surface of the stack.

In this way, reinforcing yarn may be provided to two surfaces of the stack, for example opposing surfaces of the stack. For example, reinforcing yarn may be provided to top and bottom surfaces of the stack. Consequently, a fibre mat having reinforcing yarn at or near to two surfaces, for example two opposing surfaces, may be produced.

(For brevity, features relating to the first and/or second surface edges of the layers, and features relating to the first and/or second surfaces of the stack, may be described herein with reference to one surface only. It is understood that such features are equally applicable to the first and second surface, and to the first and second surface edges. The preferred features may apply to one or both of the first and second surfaces, and to one or both of the first and second surface edges.)

As described above, each fibre web layer of the stack is offset from the previous layer, such that a first surface edge of each layer lies at the first surface of the stack. For example, each subsequent layer may be offset from the previous layer in a direction substantially parallel to the plane of the previous layer. In this way, a portion of the previous layer (including the first surface edge) remains exposed at the first surface after the subsequent layer is laid.

The offsetting may be achieved by movement of the stack as the layers are laid. For example, the fibre web may be provided to the forming stack in a feeding direction. As the layers are laid, the forming stack may be moved in a stack direction.

Preferably, the stack direction is not parallel to the feeding direction. For example, the angle between the stack direction and the feeding direction may be about 5 degrees to about 175 degrees. It is preferred that the stack direction is approximately perpendicular to the feeding direction. For example, the angle between the stack direction and the feeding direction may be from 60, 65, 70, 75, 80 or 85 degrees to 120, 115, 1 10, 105, 100 or 95 degrees. For example, the angle may be between 80 and 100 degrees, such as about 90 degrees. The layers may be laid by folding an elongate fibre web to provide the plurality of layers. Preferably, opposing elongate edges of the elongate fibre web form the first and second surface edges of the layers. Alternatively, the folds of the elongate web may form the first and second surface edges of the layers. The folding of the elongate web may be carried out using an assembly known in the art as a cross-lapper. The laying assembly of the apparatus of the present invention may be a cross-lapper. It may be preferable that one or more of the layers of fibre web, for example each layer, comprises two, three or more overlying veils of fibre web. The reinforcing yarn may be provided to the layer at a position interposed between the veils of fibre web. This can improve the incorporation of reinforcing yarn into the stack and into the fibre mat, as the reinforcing yarn will lie beneath one of the veils on the surface of the stack.

It will be understood that the elongate fibre web described above may comprise two or more overlying elongate veils of fibre web. The fibre web may comprise fibres of any suitable material.

For example, the fibre web may comprise natural fibres, such as plant-derived fibres. The plant derived fibres may be selected from the following: hemp, jute, flax, ramie, kenaf, rattan, soya bean fibre, okra fibre, cotton, vine fibre, peat fibre, kapok fibre, sisal fibre, banana fibre or other similar types of bast fibre material, and mixtures thereof. Such plant-derived fibres are fibrous and are flexible.

Alternatively or additionally, other fibres, such as synthetic fibres, may be used. Suitable fibres include glass fibres, and polymer fibres. Such fibres may be extruded fibres (i.e. formed by extrusion, for example extrusion of molten fibre material). Where the fibre comprises a polymeric material, this may be for example a thermoplastic polymeric material, or a thermosetting polymeric material. Preferred is a thermoplastic polymeric material. Examples of suitable polymeric materials include polyethylene, polypropylene, poly lactic acid, polyester materials such as polyethylene terephthalate and polyamide materials such as nylon.

The fibre web may comprise a single type of fibre, or may comprise a mixture of different fibres. For example, the mixture may include fibres of thermoplastic polymeric material. In one preferred embodiment, a mixture of polypropylene fibres and glass fibres is used.

The fibre web may be produced by any suitable method. Suitable methods are well known to those skilled in the art. For example, the fibre web may be produced by carding. The fibres may be cut to a suitable length prior to carding. Accordingly, the methods of the present invention may include a step of forming the fibre web, e.g. by carding. Similarly, the apparatus may include a

web-forming assembly, e.g. a carding assembly.

As an alternative to carding, the fibre web may be formed by a technique known in the art as spunbonding. Accordingly, the web-forming assembly may be a spunbonding assembly. In an example spunbonding process, polymer melt is extruded then spun and drawn in order to provide fibres. These fibres are then deposited on a substrate, to form a fibre web. Fibres may be carried to the substrate for example by gas flow or by electrostatic charge. The fibres of the web may be bonded together, for example by heating the fibres as or after they are deposited in a web. As a further alternative to carding, the fibre web may be formed by a technique known in the art as melt blowing. Accordingly, the web-forming assembly may be a melt blowing assembly. In an example melt blowing process, polymer melt is passed through a die into a high velocity gas stream. The die forms the polymer into fibres. The gas stream carries the fibres and deposits them in a web on a substrate. The fibres of the web may be bonded together, for example by heating the fibres as or after they are deposited in a web.

One or more of the layers may be provided with a single reinforcing yarn at its first surface edge, and optionally a single reinforcing yarn at its second surface edge. In addition, it may be preferred to provide one or more further reinforcing yarns toward or at one or both of the first and second surface edges. For example, one or more of the layers, for example a plurality of the layers, e.g. each of the layers, may be provided with one, two, three, four, five or more reinforcing yarns at a position away from the centre of the yarn toward or at the first surface edge of each of those layers. In this way, the one, two, three, four, five, or more reinforcing yarns provided to the layer will lie at or near to the first surface of the stack. Similarly, one, two, three, four, five or more reinforcing yarns may be provided toward or at the second surface edges of one or more of the layers, for example a plurality of the layers, e.g. each of the layers. It may be preferred that the reinforcing yarn extends in a direction substantially parallel to the first surface edge of the layer to which it is provided. Preferably, the yarn is tensioned as it is provided to the layers. In this way, the yarn may lie in a substantially straight line. This can improve the strengthening effect of the yarn.

Preferably, the reinforcing yarn extends from one side of the first surface to the other, i.e. preferably it spans the first surface of the stack.

As described above, reinforcing yarn is provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. Preferably, the reinforcing yarn is positioned at least 40% of the distance from the centre of the layer to the first surface edge, more preferably at least 50%, at least 60%, at least 70%, at least 80% or at least 90%.

(The distance from the centre of the layer may be measured in a direction substantially perpendicular to the first surface edge of the layer. The centre of the layer may be located at a position half of the distance (e.g. half of the shortest distance) from the first surface edge of the layer to the opposite edge of the layer, for example in a direction substantially perpendicular to the first surface edge.) For example, the reinforcing yarn may be positioned not more than 5mm, not more than 20mm, not more than 30mm, not more than 40mm, not more than 50mm, not more than 60mm, or not more than 70mm from the first surface edge.

The same piece of reinforcing yarn may be provided to more than one of the layers. For example, the same piece of reinforcing yarn may be provided to two or more of the layers, e.g. each of the layers. The reinforcing yarn may be doubled over in order to be provided to two or more layers, e.g. each of the layers. In this way, reinforcing yarn may be supplied substantially continuously as the layers are laid. This is particularly preferred in embodiments wherein the layers are laid by folding an elongate fibre web to provide the plurality of layers.

Preferably, as the reinforcing yarn is supplied to the layers, it is at least twice as long as the average length of the fibres in the fibre web. For example, the yarn may be at least 3, 4, 5, 6, 7, 8, 9, 10, 15 or 20 times as long as the average length of the fibres.

The fibres may have an average length of at least 10mm, more preferably at least 20mm, at least 30mm, at least 40mm, at least 50mm, at least 60mm or at least 70mm. The fibres may be processed (e.g. cut) to have a maximum length of up to 150mm, for example.

When supplied to the layers, each reinforcing yarn may have a length of at least 250mm, at least 500mm, at least 600mm, at least 700mm, at least 800mm, at least 900mm, at least m, at least 2m, at least 3m, at least 4m, at least 5m or at least 10m.

The above preferences for fibre length, and for yarn length as it is supplied to the layers, and their ratio, also apply to fibres and yarns of the stacks and/or fibre mats of the present invention. However, the stack and/or the fibre mat may be cut smaller or into a desired shape, at some point during or after its manufacture. This may result in reinforcing yam of the fibre mat being cut, and consequently being shortened to have a length lower than the preferred lengths described above.

Accordingly, in the stacks and/or fibre mats of the present invention, each reinforcing yarn may have a length of at least 50mm, at least 00mm, more preferably at least 250mm, at least 500mm, at least 600mm, at least 700mm, at least 800mm, at least 900mm or at least 1 m. In any event, it is preferable that reinforcing yarn spans the first surface of the stack. For example reinforcing yarn may extend from one side of the first surface to the other.

The reinforcing yarn may be provided to the layer for example as the layer is laid on the stack, or before (for example immediately before) the layer is laid on the stack.

The reinforcing yarn may be provided from one or more yarn sources, for example from one or more spools. Where more than one yarn is provided to the layers, there may be more than one yarn source. For example, if reinforcing yarn is supplied to both the first and second surface edges of the layers, there may be two yarn sources, for example one arranged to provide yarn to the first surface edge and one arranged to provide yarn to the second surface edge. In another example, there may be four yarn sources, for example two arranged to provide yarn to the first surface edge and two arranged to provide yarn to the second surface edge.

There may be one, two, three, four, five, six, seven, eight, nine, ten or more yarn sources. It will be understood that it may be preferable to provide one yarn source for each reinforcing yarn supplied to the layers. For example, when four reinforcing yarns are supplied to each layer, it may be preferable to provide four yarn sources. It will be understood that yarn sources arranged to supply yarn to the first surface edge of the layers may be positioned to the opposite side of the laying assembly from yarn sources arranged to supply yarn to the second surface edge of the layers. Reinforcing yarn may be guided to the layers, for example by a yarn guide. In this way, the yarn is provided at the desired position in relation to the layers. The yarn guide may also provide tensioning to the yarn.

The reinforcing yarn may be made from any suitable material or mixture of material. For example, the yarn may comprise a material selected from glass (e.g. glass fibre); polymeric materials including polyethylene, polypropylene, poly lactic acid, polyester materials such as polyethylene terephthalate and polyamide materials such as nylon; natural materials, including fibrous natural materials such as flax or hemp; and mixtures thereof. Where the yarn comprises a polymeric material, this may be for example a thermoplastic polymeric material, or a thermosetting polymeric material. Preferred is a thermoplastic polymeric material.

Particularly preferred is yarn which comprises a mixture of glass fibre and a polymeric material, or a mixture of natural fibre and polymeric material. In these mixtures, preferably the polymeric material is a thermoplastic polymeric material. The polymeric material may be selected from, for example, polyethylene terephthalate, polypropylene, polyethylene and poly lactic acid. The reinforcing yarn may comprise filaments. For example, the yarn may be a bundle of filaments. The filaments may be twisted or wound together in order to form the yarn. The yarn may comprise filaments of the materials described above. One particularly preferred yarn is a bundle comprising filaments of glass fibre and filaments of polymeric material, such as polypropylene and/or polyethylene terephthalate. Yarn comprising these filaments is available from OCV

Reinforcements (Owens Corning), under the product name Twintex.

Another particularly preferred yarn is bundle comprising filaments of flax and filaments of polymeric material. Suitable yarn comprising a bundle of flax filaments and polymer filaments (polypropylene or poly lactic acid) is available from Composites Evolution, Chesterfield, UK, under the product name Biotex.

It may be preferred to use the same material(s) for the yarn and the fibres of the fibre web. This can make it simpler to recycle the mats. For example, a yarn comprising filaments of glass fibre and filaments of polymeric material may be used to reinforce a fibre mat comprising glass fibres and polymer fibres. The present inventors have found that the combination of glass and polypropylene yarn and glass and polypropylene fibres provides particularly good adhesion between the yarn and the mat.

Alternatively, the yarn and the fibres may be made from different materials.

Similarly, a yarn comprising filaments of natural material such as flax may be used to reinforce a fibre mat comprising natural fibres. In this way, the mat may comprise a significant proportion, for example substantially entirely, natural materials.

It may be preferred also to include filaments of a natural polymer in the yam and/or to include fibres of a natural polymer in the fibre mat. The natural polymer may be, for example, poly lactic acid. As described above, in the present invention yarn is provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. In this way, the reinforcing yarn may lie at or near to the first surface of the stack. Locating the reinforcing yarn at or close to the surface of the stack may be desirable, as it can improve the bending properties of the stack. Similarly, in embodiments wherein yarn is provided to both the first and second surfaces of the stack, it is desirable that there is a separation between the reinforcing yarn of the first surface and the reinforcing yarn of the second surface, as this too can improve bending properties.

Accordingly, it is preferred that substantially all of the first surface yarn lies at the first surface, or at a position not more than 20% of the stack depth away from the first surface. Here, the stack depth may be measured in a depth direction substantially perpendicular to the plane of the first surface. More preferably, substantially all of the first surface yarn provided to the first surface lies at the first surface, or at a position not more than 15%, 10%, 5%, 4%, 3%, 2% or 1 % of the stack depth away from the first surface. It will be understood that this applies equally to the second surface, and to second surface yarn.

(It will be understood that first surface yarn may be a label for describing the yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. Similarly, second surface yarn may be a label for describing the yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the second surface edge of the layer.) Where reinforcing yarn is supplied to both first and second surfaces of the stack, and particularly where the first and second surfaces are opposing surfaces of the stack, preferably substantially all of the first surface yarn is separated from substantially all of the second surface yarn by at least 60% of the stack depth. More preferably, the first surface yarn is separated from the second surface yarn by at least 70%, 80%, 90%, 95%, 96%, 97%, 98% or 99% of the stack depth.

It will be understood that the above discussion of yarn position in the stack applies equally fibre mats. In this case, the depth of the stack may be

understood to be the depth of the fibre mat.

After the reinforcing yarn has been provided, further processing steps may be carried out.

The fibres may be consolidated to form the mat. For example, they may be consolidated mechanically, for example by punching the mat. This may by needle punching, or by punching with pressurised jets of gas or liquid, such as air or water. Alternatively or additionally, the fibres may be consolidated thermally, by heating the mat for example in an oven. In this case, it is preferable that the fibres are thermoplastic. In one particularly preferred embodiment, the fibres may comprise two (or more) components. For example, the fibres may have first component which melts at a fibre consolidation temperature (e.g. 150°C). Heating to the consolidation temperature may be employed to bind the fibres together. A second component of the fibres may melt at a moulding temperature which is higher than the fibre consolidation temperature (e.g. 200°C). The mat may be heated to this moulding temperature when it is pressed or moulded into a shape into later in its manufacture. For example, the first component may form an outer layer of the fibres, and the second component may form a core of the fibres.

Prior to the consolidation step, the mat may be densified, for example to reduce its height. For example, the densification may be performed by an assembly known in the art as a tacker.

After consolidation, the mat may be treated with a binder, for example by impregnation. A wetting agent may be provided to assist with impregnation. The binder may be curable. It may be heat activated. It may be a thermoplastic or thermosetting material.

It may be preferred that the binder is a plant-derived material. For example, the binder may be furfural (furan-2-carbaldehyde) or a derivative of furfural such as furfural alcohol, furan, tetrahydrofuran and tetrahydrofurfural alcohol (collectively referred to as furans). In particular, it is preferred that the binder is a furan resin, such as a resin comprising prepolymers of furfuryl alcohol. The cured resin may therefore be a poly(furfuryl alcohol). For example, a furan resin may be produced in which furfural replaces formaldehyde in a conventional production of a phenolic resin. The furan resin cross link (cure) in the presence of a strong acid catalyst via condensation reactions. Furfural an aromatic aldehyde, and is derived from pentose (C5) sugars, and is obtainable from a variety of agricultural byproducts. It is typically synthesized by the acid hydrolysis and steam distillation of agricultural byproducts such as corn cobs, rice hulls, oat hulls and sugar cane bagasse. Further details relating to furan resins whose use is contemplated in the present invention is set out in "Handbook of Thermoset Plastics", edited by Sidney H. Goodman, Edition 2, Published by William Andrew, 1998, ISBN 0815514212, 9780815514213, Chapter 3: Amino and Furan Resins, by Christopher C. Ibeh, the content of which is incorporated herein by reference in its entirety.

Furan resin can be obtained, for example, from TransFurans Chemicals bvba, Industriepark Leukaard 2, 2440 GEEL, Belgium, under the trade name BioRez™, for example BioRez™ 050525-S-1 B. It is preferred that this resin is cured via a heat-activated catalyst. The curing temperature of this resin is in the range 140- 190 degrees C. Storage of this product at 20-25 degrees C is possible for extended periods, e.g. up to one month or longer.

A suitable catalyst is maleic acid. This is preferred, particularly where the mat comprises natural fibres, since it is considered not to have an adverse effect on natural fibres of the mat. An alternative catalyst is citric acid. Suitable furan resin can be obtained by the following process. Hemicellulosic agricultural waste (e.g. waste from sugar cane) is rich in pentose sugars.

Controlled hydrolysis of pentose sugars gives furfural. This is converted to furfuryl alcohol by catalytic hydrogenation. Furfuryl alcohol can then be formed into prepolymers of furfuryl alcohol, which is the base material of the resin.

One particular advantage of furan resin is that it is substantially free from volatile organic solvents. Furthermore, during the curing process, water is formed from condensation reactions which occur as the resin crosslinks. Furan resins are of particular interest because they are derived from natural, renewable sources, they bond well to natural fibres and they have good flame- retardancy properties. It may be preferred that substantially all of the materials of the mat originate from natural, renewable sources. Alternatively, a polyurethane binder may be used.

There are various possible routes to achieve full or partial impregnation of the fibre mat with binder such as resin. One suitable approach is to dip coat the natural fibre mat with the resin. This can be one-sided or two-sided dip coating. Alternatively, the natural fibre mat can be coated with resin by roller coating or foam coating. In these methods, and particularly for dip coating, it can be advantageous to use a doctor blade, scraper blade or similar to make more uniform the amount of resin coated on the natural fibre mat per unit area.

Alternatively or in addition to the binder, additives may be supplied to the mat, for example to provide desired properties such as flame retardancy, water repellence etc.

The fibre mat may be cut, for example cut to a convenient size and shape for transport and/or storage.

The fibre mat may be shaped, for example by heating and moulding the panel. The presence of a curable binder, or a thermoplastic binder, may be desirable for this shaping process. For example, the fibre panels may be moulded for interior panels of vehicle or buildings.

In another aspect, the present invention provides a method of manufacturing a non-woven fibre mat, the method including forming a stack of offset overlying layers of fibre web by cross-lapping, wherein reinforcing yarn is added to each layer at the same time as, or immediately before, the layer is laid, the reinforcing yarn being provided only at or near one or more edge of the layer, so that after cross-lapping, the reinforcing yarn is located only at positions at or near to one or more surfaces of the stack.

Preferably each layer of fibre web comprises two or more overlying veils, and wherein the reinforcing yarn is provided at a position interposed between the veils. The reinforcing yarn may be tensioned as it is provided to the layers.

In another aspect, the present invention provides an apparatus for making a fibre mat, comprising:

(i) a cross-lapper arranged to lay a plurality of layers of fibre web in a stack; and

(ii) one or more yarn sources arranged to provide reinforcing yarn to each layer at the same time as, or immediately before, the layer is laid,

wherein each yarn source is arranged to provide reinforcing yarn only at or near one or more edge of the layer, so that after cross-lapping, the reinforcing yarn is located only at positions at or near to one or more surfaces of the stack. Preferably, the reinforcing yarn is provided from one or more spools, the spools being positioned relative to the cross-lapper in order to provide the yarn at the same time as, or immediately before, the layer is laid. Any of the preferred or optional features of any aspect may be combined, either singly or in combination, or with any other aspect, unless context demands otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram illustrating a method and apparatus according to an embodiment of the invention.

Fig. 2 shows a stack of layers according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS, AND FURTHER OPTIONAL FEATURES

Figure 1 illustrates apparatus for carrying out a method according to an embodiment of the present invention. Fibres 1 are fed into a mixer 2, which deposits the fibres 1 onto a chute feed 3. The chute feed 3 carries the fibres to a carding machine 4. The carding machine 4 cards the fibres 1 in order to form two veils of fibre web 5a, 5b (shown in the inset to Fig. ). Two lengths of first surface edge reinforcing yarn 6a, 6b are supplied near to the first surface edge 7 of the veils 5a, 5b. Two lengths of second surface edge reinforcing yarn 8a, 8b are supplied to the second surface edge 9 of the veils 5a,5b.

The veils 5a,5b are then fed together into a cross-lapper 10. They are folded to form a stack 11 of overlying layers. As the stack 11 forms, it is moved in a stack direction 12, which is substantially perpendicular to the direction from which the veils 5a, 5b are fed into the cross-lapper 10. In this way, a portion of each layer, including the first surface edge 7, remains exposed on the top (first) surface 13 of the forming stack 1. Thus, the first surface edge reinforcing yarn 6a, 6b lies at or near to the top (first) surface 13 of the stack 11. Similarly, a portion of each layer including the second surface edge 9 remains exposed on the bottom (second) surface 14 of the stack 11. Thus, the second surface edge reinforcing yarn 8a, 8b lies at or near to the bottom (second) surface 14 of the stack 11.

The reinforcing yarns 6a,6b,8a,8b are each supplied in a continuous piece from yarn spools 15a,15b,16a,16b. As the veils of fibre web 5a,5b are folded by the cross-lapper 10, the reinforcing yarns 6a,6b,8a,8b are doubled over. As such, the same piece of reinforcing yarn is provided to many layers.

The stack 1 1 then passes into a tacker 17. The tacker 17 serves to reduce the height of the stack 1 1 by densifying it, and may also cause some bonding of the fibres of the stack 11. The stack then passes into a needle-punch 8, where mechanical consolidation of the fibres is carried out in order to form a fibre mat. The needle punching can also serve to bond the fibres of the mat to the reinforcing yarn. This is enhanced by the fact that the top veil 5a lies on top of the reinforcing yarn 6a,6b,8a,8b on the first and second surfaces 13, 1 of the stack. Layers of covering

material 19,20 may be provided to provide protection and strengthening during the needle punch process.

Figure 2 shows a schematic sectional view through a stack 1 . The stack 11 has a plurality of layers 21a,21b,21c. The first surface edges 7a,7b,7c of these layers lie on the first surface 13 of the stack 11. The first surface edge reinforcing yarns 6a, 6b lie near to the first surface 13 of the stack 11.

Similarly, the second surface edges 9a,9b,9c of the layers 2 a,21 ,21c lines on the second surface 14 of the stack 11. The second surface edge reinforcing yarns 8a,8b lie near to the second surface 14 of the stack 11.

Example

Samples of glass and polypropylene non-woven fibre mats were formed by carding polypropylene fibres and glass fibres to produce two overlying veils of fibre web, and feeding the fibre web into a cross-lapper to form a stack of layers of fibre web. The stack was then passed through a tacker to densify it, and needle punched. A 300mm x 300mm sample was heated then compressed in a cold press with a 3mm spacer. TwinTex, obtained from OCV Reinforcements, was supplied to the fibre mats and located at the surface of the mats. The yarn was provided before the fibre web was fed into the cross-lapper. The TwinTex yarn was constituted from glass filaments and polypropylene filaments.

Reference samples were made similarly, but not provided with reinforcing yarn.

Strength tests were carried out on the samples made as described above. The results are given below. Reference samples are labelled "CF 13", and reinforced samples "CF414".

The reinforced and reference samples had similar surface weight, shown in Table 1.

Table 1:

Tensile Test

A tensile test was carried out on the reference and reinforced mats, according to the standard test procedure ISO 527/4. The mats were tested in a longitudinal direction, which was the longitudinal direction of the reinforcing yarn, and in a transverse direction, which was perpendicular to the longitudinal direction.

The results are shown in Table 2 (longitudinal) and Table 3 (transverse).

Table 2:

These results show that, in the longitudinal direction, the reinforcement leads to an increase in the modulus (in the elastic deformation region) of the mat, and a reduction in extension at break. Table 3:

The results show that the reinforced and reference mats have similar tensile strength in the transverse direction.

Bending test

A bending test was carried out on the reference and reinforced mats, according to the standard test procedure ISO 14125/2. The mats were tested in a longitudinal direction, which was the longitudinal direction of the reinforcing yarn, and in a transverse direction, which was perpendicular to the longitudinal direction. The results are shown in Table 4. Table 4:

The results show that the reinforcement provides an improvement in bending strength in the longitudinal direction, and that the reinforced and reference mats have similar bending strength in the transverse direction.

Impact test

The impact resilience of the reference and reinforced mats was carried out. The results are shown in Table 5. Table 5:

The results show a 26% increase in impact resilience in the longitudinal direction when the mats are reinforced.

The present invention has been described with reference to preferred

embodiments. Modifications of these embodiments, further embodiments and modifications thereof will be apparent to the skilled person and as such are within the scope of the invention.

Claims

CLAIMS:

1. A method of making a fibre mat, such as a non-woven fibre mat, comprising:

2. A method according to claim 1 wherein the layers are laid by folding an elongate fibre web. 3. A method according to claim 2 wherein an elongate edge of the elongate fibre web forms the first surface edges of the layers.

A. A method according to claim 2 or claim 3 wherein the layers are laid by a cross-lapper.

5. A method according to any one of the preceding claims wherein one or more of the layers of fibre web comprises two or more overlying veils of fibre web. 6. A method according to claim 5 wherein the reinforcing yarn is provided at a position interposed between the veils of fibre web.

7. A method according to any one of the preceding claims wherein one or more of the layers is provided with two or more reinforcing yarns at a position away from the centre of the yarn toward or at the first surface edge of the layer.

8. A method according to any one of the preceding claims wherein each layer comprises a second surface edge and a second surface of the stack includes the second surface edge of each layer, and wherein further reinforcing yarn is provided to one or more of the layers at a position away from the centre of the layer toward or at the second surface edge of the layer.

9. A method according to claim 8 wherein one or more of the layers is provided with two or more reinforcing yarns at a position away from the centre of the yarn toward or at the second surface edge of the layer. 10. A method according to any one of the preceding claims wherein the yarn is tensioned as it is provided to the layers.

11. A method according to any one of the preceding claims wherein the same piece of reinforcing yarn is provided to two or more of the layers.

12. A method according to any one of the preceding claims wherein the reinforcing yarn is at least twice as long as the average length of the fibres of the fibre web. 13. A method according to any one of the preceding claims wherein the yarn is provided from one or more spools.

14. A stack of layers of fibre web, each of the layers having a first surface edge, each layer of the stack being offset from the adjacent layers such that a first surface of the stack includes the first surface edge of each layer,

the stack having reinforcing yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer. 15. A stack according to claim 14 which is a fibre mat product.

16. A stack according to claim 14 or claim 15 wherein substantially all of the first surface yarn lies at the first surface or at a position not more than 20% of the stack depth away from the first surface.

17. A stack according to any one of claims 14 to 16 wherein each of the layers has a second surface edge, and a second surface of the stack includes the second surface edge of each layer, and wherein the stack has reinforcing yarn provided to one or more of the layers at a position away from the centre of the layer toward or at the second surface edge of the layer.

18. A stack according to claim 17 wherein substantially all of the first surface yarn is separated from substantially all of the second surface yarn by at least 60% of the stack depth.

19. A non-woven fibre mat obtained or obtainable by a method according to any one of claims 1 to 1 1. 20. Apparatus for making a fibre mat such as a non-woven fibre mat, the apparatus comprising

a laying assembly for laying a plurality of layers of fibre web in a stack, each of the layers having a first surface edge, the laying assembly being arranged to lay each layer at a position offset from the previous layer such that a first surface of the stack includes the first surface edge of each layer; and

a yarn source arranged to provide reinforcing yarn to one or more of the layers at a position away from the centre of the layer toward or at the first surface edge of the layer.