GB2492644A

GB2492644A - Polymer fabrics

Info

Publication number: GB2492644A
Application number: GB1211737.0A
Authority: GB
Inventors: Martin Reid
Original assignee: Don and Low Ltd
Current assignee: Don and Low Ltd
Priority date: 2011-07-04
Filing date: 2012-07-03
Publication date: 2013-01-09
Anticipated expiration: 2032-07-03
Also published as: GB201211737D0; GB2492644B

Abstract

A thermoplastic composite comprises first elongate elements 4 with a polymer base 8 and at least one polymeric surface layer 10, and second elongate elements 6 at least a surface of which comprises a material dissimilar to that of polymeric surface layer of the first element. The polymeric surface layer 10 has a lower softening temperature than the base 8. The first and second layers are mutually interspersed such as by weaving, and the first and second elements are fusible together at intersections. The second elongate elements may comprise a material which is dissimilar to the base of the first elements. The second elongate elements may comprise polyesters, polyamides, aramids, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes such as UHMWPE or UHMWPP, glass fibres, multifilament nucleated polypropylenes, basalt, and/or carbon fibres. The elongate elements may be in the form of a tape. The material may be consolidated into articles or fabric for anti-ballistic and/or defensive purposes requiring high-impact resistance. The base of the first element may comprise a molecularly oriented thermoplastic polymer and the surface layer may be thermoplastic compatibly bonded to the base by molecular interspersion between the surfaces of base and layer. At least a surface of the second element may comprise polyalkylene with a density of less than 1g/m3 and a tensile modulus of 13 N/tex (150 g/denier)

Description

IMPROVED POLYMER FABRICS

FIELD OF INVENTION

This invention relates to a thermoplastic composite material or fabric and a method of producing same. The composite material or fabric is suitable for a variety of applications. For example, composite materials or fabrics of the present invention may be comprised in articles used for anti-ballistic and/or defensive purposes. Composite materials or fabrics of the present invention may be comprised in articles to afford high-impact resistance properties. This invention relates to a means of producing composite elongated elements, such as tape, which may be used to produce a fabric incorporating dissimilar materials in the warp and weft, such fabric being suitable for consolidating into multilayer structures under the action of heat and pressure without the need for additional resin or adhesive.

BACKGROUND OF INVENTION

Fibre reinforced composites (FEC) find many forms, from metal rod reinforcement of concrete to short cut glass reinforcement of thermoset resins. When considering polymeric matrices, a FRC usually comprises of a continuous matrix which is reinforced with a fibrous component. The fibrous component may take the form, amongst others, of a continuous or shortcut mono or multifilament yarn, a scrim, a nonwoven mat or a woven mat, for example. These may be composed of a single type or a multiplicity of types of fibre within one composite. Layering up multiple layers of FEC will normally require the application of further uncured resin or some separate adhesive with a subsequent curing stage. The present Inventors have identified a need or desire to produce FRC without the requirement for a liquid resinous phase or application of an adhesive in order to achieve consolidation.

WO 91/11324 (DON & LOW (HOLDINGS) LIMITED) discloses a thermoplastic composite material comprising at least one mat of mutually intersecting elongate elements fusible together at least at their intersections, each of said elements comprising a molecularly-oriented thermoplastic polymer base having at least one thermoplastic surface polymeric layer compatibly bonded to said polymer base by molecular interspersion between the contiguous surfaces of the adjoining base and surface layers, and said surface polymeric layer having a softening temperature lower than that of the polymer base.

By "molecular interspersion" is meant the intimate molecular compatibility of molecules of the surface layer and the adjacent polymer and vice versa, so that there is intermingling or fusion at their contiguous boundaries. It is believed that such molecular interspersion effectively forms an amorphous sheath which protects the polymer base against fracture during drawing, thus providing mutual mechanical reinforcement.

Mutual mechanical reinforcement involves the surface material being capable of high elongation when drawn in the solid state (or even being drawn at a temperature above its softening point, i.e. in the molten state). With a polymer layer of high modulus, crystalline or oriented material sandwiched between amorphous high elongation surface layers, propagation of transverse fractures is inhibited allowing the total composite to be highly drawn.

It is an object of at least one embodiment of at least one aspect of the present invention to obviate or at least mitigate one or more problems or disadvantages in the

prior art.

It is an object of at least one embodiment of at least one aspect of the present invention to provide a fabric or material that may be formed without the use of, for example, a resin matrix material, a film or an adhesive. The fabric or material may therefore be self-adhering or self-supporting.

SUMMARY OF INVENTION

According to a first aspect of the present invention there is provided a material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein at least a surface of the second elongate elements comprises a material or materials dissimilar to the polymeric surface layer, and the first elongate elements are fusible together with the second elongate elements at least at intersections.

According to a second aspect of the present invention there is provided a material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein the second elongate elements comprise a material or materials dissimilar to the base layer; and the first elongate elements are fusible together with the second elongate elements at least at intersections.

The present invention provides a fabric or material that may be formed without the use of, for example, a resin matrix material, a film or an adhesive.

As used herein, fabric", "mat" and "material" are interchangeable.

The expression elongate element" as used herein may refer to a tape, thread, fibre, filament, strand, or the like. The expression "elongate element" may encompass bundles of tapes, threads, fibres, filaments, strands, or the like.

The second elongate elements may comprise a single (e.g. homogenous) layer.

Alternatively, the second elongate elements may comprise a plurality of layers.

Preferably the second elongate elements comprise a material or materials dissimilar to the polymeric surface layer.

In one embodiment, the first elongate elements and the second elongate members may be formed as tapes. The tex of the first and/or second elongate element may be between 50 and 800 tex. The width of the first and/or second elongate element may be between 1 mm and 14mm.

The first elongate elements may comprise one or two surface layers, e.g. two opposing surface layers. The first elongate elements may comprise a layered structure comprising a base polymer sandwiched by two polymeric surface layers.

The elongate elements may be preferably woven, or alternatively, knitted, stitched, be laid out to form a random fibrous web or be randomly interspersed to form the material. In one advantageous implementation the elongate elements may be The first elongate elements may comprise a molecularly-oriented thermoplastic polymer base having at least one thermoplastic surface polymeric layer compatibly bonded to said polymer base by molecular interspersion between contiguous surfaces of the adjoining based surface layers.

It is to be appreciated that the skilled person would understand that warp (or machine direction) elongate elements are usually beamed for weaving purposes. Welt (or cross-direction) elements are woven through warp elements to produce the woven fabric. In some embodiments, the warp may be formed of first or second elongate elements and the weft may be formed of the other. For example, the warp may be formed of first elongate elements and the weft may be formed of second elongate elements. Alternatively, the warp may be formed of second elongate elements and the weft may be formed of first elongate elements. In other embodiments, the warp and/or the weft may comprise a mixture of first and second elongate elements. The mixture may be a random arrangement of first and second elongate elements. The mixture may be a regular alternation of first and second elongate elements.

Warp and weft densities of the first and second elongate elements may be between 10 tapes/lU cm and 124 tapes/lU cm.

The first elongate elements may comprise a molecularly-oriented thermoplastic polymer base. Representative examples include, but are not limited to, polypropylene, polyesters (such as polyethyleneterephthalate), polyamides (such as Nylon 6 or 6.6), or a polyethylene having a density in the range 0.940 to 0.970 or linear low density polyethylene. In one embodiment, the polymer base may comprise a molecularly-oriented polyolefin polymer. In one embodiment, the first elongate element comprises a high melting point polypropylene base or core. For example, the polypropylene base polymers may have a melting point in the range of 160 -165 C. For example, the molt flow rate (MFR) of the polypropylene base polymers may be in the range of 2 to 5 g/2.16 kg at 230°C in 10 minutes.

The surface layer(s) may be compatibly bonded to the polymer base by molecular interspersion between the contiguous surfaces of the adjoining base and surface layers.

The surface layer may comprise a thermoplastic polymer. The surface layer may comprise a thermoplastic co-polymer. Representative examples include, but are not limited to, ethylene-propylene co-polymer, polybutylene, polybutene-1 or a co-polymer comprising two or more of butylene, ethylene and propylene, co-polyesters and co-polyamides. The MFR of the co-polymers may be 5-15 g/2.16 kg at 230 00 in minutes. Typically the melting points of the co-polymers may be in the range of 80-O e.g. 90-140 CC.

In one embodiment, when the polymer base is polypropylene, the surface layer may comprise an ethylene-propylene co-polymer, a polybutylene such as polybutene-1 or a co-polymer comprising two or more of butylene, ethylene and propylene.

In one embodiment, when the polymer base is a polyester, the surface layer(s) may comprise a co-polyester. In one embodiment, when the polymer base is a polyamide, the surface layer(s) may comprise a co-polyamide.

The second elongate elements, or at least a surface thereof, may have a higher melting point than that of the polymeric surface layer. The second elongate elements or at least a surface thereof may comprise or consist of one or more of, but not be limited to: polyesters, polyamides, aramids, thermoplastic polymers, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes (UHMWPA) such as ultra high molecular weight polyethylene (UHMWPE) or ultra high molecular weight polypropylene (UHMWPP), multifilament nucleated polypropylenes, glass fibres, basalt fibres and/or carbon fibres.

The second elongate elements may be formed of hybrid yarns. Hybrid yarns may be formed of at least two different materials or fibres comprising polyesters, polyamides, aramids, thermoplastic polymers, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes (UHMWPA) such as ultra high molecular weight polyethylene (UHMWPE) or ultra high molecular weight polypropylene (UHMWPP), multifilament nucleated polypropylenes, glass fibres, basalt fibres and/or carbon fibres. For example, the second elongate elements may be formed of hybrid yarns comprising aramids and UHMWPE. For example, the second elongate elements may be formed of hybrid yarns of polypropylene and glass. For example, the second elongate elements may be formed of comingled yarns of glass and polypropylene strands mechanically entwined together or of glass cores with polypropylene sheaths. In such embodiments, the second elongate elements present an enhanced ability for bonding and/or fusing with the surface layer of the first elongate elements than if the second elongate elements had comprised glass alone.

The second elongate elements may comprise or consist of polyalkylene polymers wherein the molecular weight of the polyalkylene is greater than approximately 30,000. For instance, the molecular weight of the polyalkylene may be between 30,000 and 15 million.

The second elongate elements may comprise or consist of polyalkylene polymers wherein the molecular weight of the polyalkylenes is greater than approximately 500,000, for example the molecular weight of the polyalkylenes may be greater than approximately 1 million, greater than approximately 2 million or, for example, greater than 3 million. In the art such polymers are commonly known as ultra high molecular weight polymers. The molecular weight of the ultra high molecular weight polyalkylene may be between 500,000 and 15 million. For instance, the ultra high molecular weight polyalkylene may have a molecular weight between 1 million and million, between 2 million and 8 million, or, for example, between 2 million and 6 million.

The ultra high molecular weight polyalkylenes may typically be formed from the polymerization of over 10,000 monomers, the polymerization of over 50,000 monomers or even the polymerization of over 100,000 monomers. In particular, the ultra high molecular weight polyalkylenes may contain between 50,000 and 500,000 monomer units. For example, the ultra high molecular weight polyalkylenes may contain between 100,000 and 250,000 monomer units.

The ultra high molecular weight polyalkylenes may have a tensile strength above 0.35 N/tex (4g/denier). For instance, a tensile strength above 0.62 N/tex (7 g!denier) or even above 2.2 N/tex (25 g/denier). The ultra high molecular weight polyalkylenes may have a tensile strength between 0.35 Nltex (4 g/denier) and 8.8 N/tex (100 g/denier). For example, a tensile strength between 1.8 N/tex (20 g/denier) and 4.4 N/tex (50 g/denier).

The ultra high molecular weight polyalkylenes may have a high tensile modulus.

For instance, the ultra high molecular weight polyalkylenes may have a tensile modulus over 13 N/tex (150 g/denier), over 26 Nitex (300 g/denier) and typically over 53 N/tex (600 g/denier). The ultra high molecular weight polyalkylenes may have a tensile modulus between 8.8 Nltex (100 g/denier) and 177 N/tex (2000 g/denier), in particular a tensile modulus between 53 N/tex (600 g/denier) and 177 N/tex (2000 g/denier).

Second elongate elements comprising or consisting of ultra high molecular weight polyalkylenes may have a density below 1.5 g/cm3, in particular below 1 g/cm3.

The ultra high molecular weight polyalkylenes may have a density between 0.1 g/cm3 and 1.5 g/cm3. For instance, a density between 0.1 and 1 g/cm3, between 0.5 and 1 g/cm3 or between 0.8 and 1 g/cm3. For example, a density of approximately 0.97 g/cm3 Second elongate elements comprising or consisting of ultra high molecular weight polyalkylenes may have an elongation value between 0 and 20%, in particular an elongation value between 0.1 and 15%, or between 0.1 and 10%. For example, the ultra high molecular weight polyalkylenes may have an elongation value below 10% and typically an elongation value below 5%.

The ultra high molecular weight polymers may be obtained by polymerizing monomer units in the presence of a metallocene catalyst.

The second elongate elements may comprise or consist of oriented strand synthetic fibres of ultra high molecular weight polyalkylene. Representative examples of ultra high molecular weight polyalkylenes include, but are not limited to, ultra high molecular weight polyethylene, ultra high molecular weight polypropylene and the like.

Oriented strand synthetic fibres of ultra high molecular weight polyalkylene may be formed by a gel spinning through a spinneret. The second elongate elements may comprise or consist of ultra high molecular weight oriented polyalkylene, for example, ultra high molecular weight oriented polyethylene and/or ultra high molecular weight oriented polypropylene.

It is to be appreciated that second elongate elements comprising or consisting of ultra high molecular weight polyalkylenes and/or oriented fibres of polyalkylenes may comprise a smooth or slippery surface which causes obvious difficulties when attempting to weave with such elements. These technical obstacles can be overcome by experiment with the choice of accumulator, yarn tension, loom timing and also the avoidance of excess lubrication.

The second elongate elements may comprise or consist of polyethylene polymers wherein the molecular weight of the polyethylene is greater than approximately 500,000, greater than approximately one million, 2 million or even greater than approximately 3 million. In the art such polymers are commonly known as ultra high molecular weight polymers. The molecular weight of the ultra high molecular weight polyethylene may be between 500,000 and 10 million. For instance, the molecular weight of the ultra high molecular weight polyethylene may be between one million and six million. The second elongate elements may comprise or consist of oriented strand synthetic fibres of ultra high molecular weight polyethylene. Oriented strand synthetic fibres of ultra high molecular weight polyethylene may be formed by a gel spinning through a spinneret. Second elongate elements may comprise ultra high molecular weight oriented polypropylene.

The second elongate elements may comprise or consist of polypropylene polymers wherein the molecular weight of the polypropylene may be greater than approximately 500,000. For instance, the molecular weight of the ultra high molecular weight polypropylene may be greater than 1 million, greater than 1.5 million, greater than 2 million or greater than 3 million. The molecular weight of the ultra high molecular weight polypropylene may be between 1 million and 15 million, between 2 million and million, or, for example, between 3 million and 8 million.

The second elongate elements may comprise or consist of nucleated polypropylene. The second elongate elements may comprise or consist of multifilament nucleated polypropylene elements (such as yarns), such as those described in US patents US 7445842 B2, US 7445834 32 and US 7074483 B2. In certain embodiments of the present invention, beneficially multifilament nucleated polypropylenes have a higher strength than conventional oriented polypropylene yarns.

The multifilament nucleated polypropylenes may have a high tensile strength.

For instance, the multifilament nucleated polypropylenes may have a tensile strength above 0.35 N!tex (4 g/denier) in particular a tensile strength above 0.62 Nltex (7 g/denier). The multifilament nucleated polypropylenes may have a tensile strength between 0.35 N/tex (4 g/denier) and 0.62 Nltex (20 g/denier).

The multifilament nucleated polypropylenes may have a high tensile modulus.

For instance, the multifilament nucleated polypropylenes may have a tensile modulus between 8.8 N/tex (100 g/denier) and 35 N/tex (400 g/denier), in particular a tensile modulus above 13 Nltex (150 g/denier).

Second elongate elements comprising or consisting of multifilament nucleated polypropylenes may have an elongation value between 0 and 20%, in particular an elongation value between 0.1 and 15%, or between 0.1 and 10%. For example an elongation value below 10%.

Second elongate elements comprising or consisting of multifilament nucleated polypropylenes may have a density less than 1.5 g/cm3, in particular less than 1 g/cm3.

For instance, the second elongate elements may have a density between 0.1 and 1.5 g/cm3, or even 0.5 and 1 g/cm3, or between 0.8 and 1 g/cm3. In certain embodiments, second elongate elements comprising or consisting of multifilament nucleated polypropylenes may have a density of approximately 0.84 g/cm3.

Second elongate elements comprising or consisting of multifilament nucleated polypropylenes may comprise polypropylenes with a molecular weight between 30,000 and 300,000.

The polypropylene may be a polymer formed by the polymerisation of propene monomers. Polypropylenes may be isotactic, syndiotactic or atactic or a combination of these forms. A short repeating segment of an isotactic polypropylene is shown in Formula (I). A short repeating segment of a syndiotactic polypropylene is shown in Formula (II).

Cl-I3 H OH3 H Cl-I3 H OH3 H CH3 H

H H H H H H H H H H

CH3 H H H CH3 H H H CH3 H H H OH3 H H H OH3 H H H In an atactic polypropylene, the position of the methyl group is randomly positioned on either side of the polymer chain.

The second elongate elements may comprise or consist of basalt elements, e.g. basalt fibres. Basalt fibres may be formed by melting basalt stones at a high temperature and extruding the melt through a spinneret block with narrow apertures.

Basalt fibres may be formed as a continuous roving without twisting or strands of basalt may be twisted together to form basalt yarns. In certain embodiments of the present invention, basalt fibres do not melt or shrink when exposed to flame and/or heat.

Second elongate elements comprising basalt fibres may withstand temperatures up to about 650 00.

Second elongate elements comprising basalt fibres may have a comparable density to E and S glass. For example, the basalt fibres may have a density between 1 and 3 g/cni3, typically basalt fibres may have a density of approximately 2.7 g/cm3.

Second elongate elements comprising basalt fibres may have a higher tensile strength than E glass, aramid and certain carbon fibres. Basalt fibres may have a tensile strength between 1 and 8 OPa, or between 2 and 6 OPa, or between 3 and 5 GPa. Typically, basalt fibres may have a tensile strength of approximately 4.8 OPa.

Basalt fibres may have a tensile strength above 0.35 N/tex, e.g. above 0.6 N/tex.

The second elongate elements may have a low density. The second elongate elements may have a density less than 1.5 g/cm3, in particular less than 1 g/cm3. For instance, the second elongate elements may have a density between 0.1 and 1.5 g/cm3, or even 0.5 and 1 g/cm3, or between 0.8 and 1 g/cm3.

The second elongate elements may have a high tensile strength. For instance, the second elongate elements may have a tensile strength above 0.35 N/tex (4 g/denier) in particular a tensile strength above 0.62 N/tex (7 g/denier). The second elongate elements may have a tensile strength between 0.62 N/tex (7 g/denier) and 4.4 N/tex (50 g/denier).

The second elongate elements may have a high tensile modulus of above approximately 13 N/tex (150 g/denier). For example, a tensile modulus between 13 N/tex (150 g/denier) and 177 N/tex (2000 g/denier).

The second elongate elements may be chemically compatible with at least the polymeric surface layer of the first elongate elements. The second elongate elements may have a high bonding potential with at least the polymeric surface layer of the first elongate elements. The second elongate elements may comprise or consist of a material which is capable of forming bonds with at least the polymeric surface layer of the first elongate elements by molecular interspersion between contiguous surfaces of the second elongate elements and the polymeric surface layer of the first elongate elements. For instance, the second elongate elements may comprise of consist of ultra high molecular weight polyalkylenes and/or multifilament nucleated polypropylenes.

The second elongate elements may be high modulus strength, low density polyalkylenes. Representative examples include, but are not limited to, ultra high molecular weight polyalkylenes and multifilament nucleated polypropylenes.

"Nucleated" as used herein refers to a polymer formed upon cooling a polymer melt in the presence of a nucleating agent.

"Oriented" as used herein refers to a polymer wherein there is a greater than 50% alignment of polymer molecules in a parallel orientation. For example, there may be a greater than 75%, or greater than 90% alignment of polymers in a parallel orientation. Oriented" as used herein may also refer to a polymer wherein there is a greater than 50% degree of crystallinity. For example, the polymer material may be more than 75% crystalline, more than 80% crystalline, or even more than 90% crystalline.

"Intersection" as used herein refers to any point and/or area of contact between one elongate element and another elongate element.

According to a third aspect of the present invention there is provided a material or fabric comprising at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and polymeric surface layer, wherein the surface layer has a softening temperature lower than that of the polymer base; and wherein the second elongate elements comprise a material selected from one or more of polyesters, polyamides, aramids, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes such as UHMWPE and UHMWPP, glass fibres, multifilament nucleated polypropylenes, basalt fibres and/or carbon fibres; and wherein the first elongate elements are fusible together with the second elongate elements at least at their intersections.

According to a fourth aspect of the present invention there is provided a composite material which comprises at least one layer of fabric according to the first and/or second aspects of the present invention.

Preferably the composite material comprises a plurality of layers. In a preferred embodiment, the composite material comprises a plurality of layers according to the first and/or second aspects of the present invention which are fusible together at least at their interfaces.

Interface" as used herein refers to any area wherein two surfaces meet and contact one another.

According to a fifth aspect of the present invention there is provided a method of making or forming a material or fabric according to the first or second aspect of the present invention, the method comprising the steps of: mutually interspersing the elongate elements to form a fabric; and fusing the elongate elements together at least at their intersections.

Mutually interspersing the elongate elements may comprise weaving, knitting, stitching, the laying down of a random web. In one embodiment, mutually interspersing the elongate elements may comprise weaving the elements together.

In one embodiment, fusing the elongate elements together may comprise subjecting the fabric to different treatments. Fusing may comprise one or more of: heating, pressurising, cooling and/or depressurising. Fusing may comprise heating the fabric above the melting temperature of the polymeric surface layer. Fusing may comprise cooling the fabric to allow the surface layer to solidify. Upon heating, the surface polymer may melt and allow fusion between individual elongate elements at least at their intersections. Upon cooling, the surface layer polymer may solidify and bond the different elongate elements together. In one embodiment, fusing the elements may comprise subjecting the fabric to pressure.

Fusing may be referred to as consolidation. Consolidation may be achieved by single closure press with flat or contoured plates, continuous belt press, induction heated press or via vacuum bagging and autoclaving. For example, for fabrics which utilise tapes based on a polypropylene core with co-polymer surface layer, typical consolidation conditions on a single closure press might be a ramp time of 30 to 120 minutes, consolidation temperature of 120 to 145 °C, dwell time of 10 to 60 minutes, cooling times of 5 to 60 minutes and consolidation pressure of 50 to SOOpsi.

According to a sixth aspect of the present invention there is provided a method for making a composite material which comprises a fabric according to the first and second aspects of the present invention which comprises the steps of: layering of the fabrics; and fusing the layers of fabric together at least at their interfaces.

Layering of the fabrics may comprise stacking of two or more fabric layers. The fabric layers may be superimposed. The axes of orientation of the first elongate elements may be angularly displaced relative to the axes of orientation of the first elongate elements in an adjacent fabric layer. For example, axes of orientation of the first elongate elements may be angularly displaced by substantially 90° relative to the axes of orientation of the first elongate elements in an adjacent fabric layer. Positioning of the fabric layers in such a way may provide a cross-laid balanced structure.

Fusing as used herein refers to the fusing of individual elongate elements to each other. Fusing may refer to the bonding of individual elongate elements within a fabric at least at their intersections. Fusing may refer to the bonding of individual elongate elements present in different fabric layers at least at their interfaces.

Fusing may comprise heating, pressurising, cooling and/or depressurising.

Fusing may comprise heating above the melting temperature of the polymeric surface layer. Fusing may comprise cooling to allow the polymeric surface layer to solidify.

Upon heating, the polymeric surface layer may melt and allow fusion between individual elongate elements. Upon cooling, the polymeric surface layer may solidify and bond individual elongate elements together. In one embodiment, fusing the elements may comprise subjecting the fabric to pressure.

Heating may be effected within or in relation to a mould or the like whereby on cooling, the material may assume a predetermined three-dimensional form.

According to a seventh aspect of the present invention there is provided an article which comprises a fabric or a composite material according to any of the first, second or third aspects.

Articles may have high-impact resistance properties. Articles may be made for antiballistic purposes. Articles may comprise bulletproof vests, body armour, panels suitable for the protection of military and commercial vehicles, bin liners, blast basket or blast blankets to contain fragmentation debris from the detonation of explosive devices.

Articles may be used as carpet backings. Articles may be used in automotive or aerospace applications. For example, articles may comprise panels suitable for use on automotive vehicles. Articles may comprise toe-caps for protective footwear, connecting straps of the handles of intermediate bulk containers or the containers themselves, tarpaulins, packaging, luggage, protective cases, pipes.

According to an eighth aspect of the present invention there is provided a thermoplastic composite material comprising at least one mat of mutually intersecting first elements and second elements fusible together at least at their intersections, each of said first elements comprising a molecularly-oriented thermoplastic polymer base having at least one thermoplastic surface polymeric layer compatibly bonded to said polymer base by molecular interspersion between the contiguous surfaces of the adjoining base and surface layers, and said surface polymeric layer having a softening temperature lower than that of the polymer base, and said second elements comprising at least one surface made from a different material to the thermoplastic surface polymer layer of the first element.

According to a ninth aspect of the present invention, there is provided a material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein at least a surface of the second elongate elements comprises a polyalkylene having a density less than 1 g/cm3 and a tensile modulus above 13 N/tex (150 g/denier), and the first elongate elements are fusible together with the second elongate elements at least at intersections.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 a first schematic representation of a side view of a first elongate element according to a first embodiment of the present invention; Figure 2 a schematic representation of a side view of a woven fabric according to a first embodiment of the present invention; Figure 3 a schematic representation of a side view of a woven fabric according to a modification of the first embodiment of the present invention; and Figure 4 a schematic representation of a side view of a composite material according to one embodiment of the present invention.

DETAILED DESCRIPTION OF DRAWINGS

Referring to Figures 1 to 3, there is shown a material or fabric 2 according to a first embodiment of the present invention. The fabric 2 comprises first elongate elements 4 and second elongate elements 6 that are woven together.

First elongate elements 4 take the form of a tape. The tape is formed of a polymer base Band polymeric surface layers 10. The polymeric surface layers 10 have a softening temperature lower than that of the polymer base 8. In one implementation the polymer base B is a molecularly-oriented polypropylene. In one implementation of the present invention the polymeric surface layer 10 is a thermoplastic polymer, e.g. an ethylene-propylene co-polymer, a polybutylene such as polybutene-1 or a co-polymer comprising two or more of butylene, ethylene and propylene.

Second elongate elements 6 take the form of a tape. The tape is formed from a material selected from one or more of, but not be limited to polyesters, polyamides, aramids, molecularly-oriented thermoplastic polymers, ultra-high molecular weight polyalkylenes such as ultra high molecular weight polyethylene (UHMWPE) or ultra high molecular weight polypropylene (UHMWPP), multifilament nucleated polypropylenes, glass fibres, basalt fibres and/or carbon fibres.

In one implementation of the present invention, the first elongate elements 4 form the warp and second elongate elements 6 form the weft, as is best illustrated in Figure 2.

In another implementation of the present invention the second elongate elements 6' form the warp and the first elongate elements 4' form the weft, as is illustrated in Figure 3.

Referring now to Figure 4, there is shown a composite material 100 according to a second aspect of the present invention. The composite material 100 consists of two layers of fabric 2 and/or 2'. The layers may be offset from each other so that weft elements do not lie directly one above the other as depicted in Figure 4. Also, the layers may be offset by an angle during layup, including cross-plying by laying up layers at 90 degrees.

Examples falling within the scope of the invention wilt now be described.

EXAMPLE 1

A fabric is formed from a film of mono-axially oriented polyolefin polymer such as polypropylene. The film is formed by extrusion and stretched along a single axis.

The polypropylene film has a softening range of around 165 °C. The pre-formed polypropylene film is then coated on both sides thereof with a surface layer of a polymeric material such as an ethylene-propylene co-polymer which has a softening range lower than that of the polypropylene core, for example of the order of 90-140 0i On the application of heat at a temperature sufficient to soften the surface layers but not the polypropylene, molecular interspersion takes place at the contiguous boundaries between the polypropylene and its surface layers which may serve to protect the polypropylene against breakage during subsequent drawing operations.

After cooling, the composite film is then slit to form a plurality of separate first elongate elements in the form of first tapes, each first tape consisting of a central polypropylene base or core having bonded thereto on each face thereof a surface layer of the ethylene-propylene co-polymer having a lower softening temperature than that of the polypropylene. The first tape thus formed is then drawn at a draw ratio of the order of 12:1 in order to effect molecular orientation of the polypropylene and consequently increase correspondingly the strength of the polypropylene component of the tape and therefore the tape itself. During drawing, the molten co-polymer surface layers permit this degree of consistent drawing to an extent which is greater than that which would be permitted if, for example, polyethylene was used as a surface layer. This teaching is contained in US Patent 5,578,370 (Don and Low, 1976).

The second elongate elements, or at least a surface thereof, have a higher melting point than that of the polymeric surface layer. The second elongate elements comprise one or more of, but not be limited to, polyesters, polyamides, aramids, thermoplastic polymers, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes such as ultra high molecular weight polyethylenes and/or ultra high molecular weight polypropylenes, multifilarrent nucleated polypropylenes, glass fibres, basalt fibres and/or carbon fibres.

The second elongate elements advantageously comprise polyalkylene polymers wherein the molecular weight of the polyalkylene is greater than approximately one million. In the art such polymers are commonly known as ultra high molecular weight polymers. The molecular weight of the polyalkylene is typically between one million and six million.

The second elongate elements advantageously comprise polyethylene polymers wherein the molecular weight of the polyethylene is greater than approximately one million. In the art such polymers are commonly known as ultra high molecular weight polymers. The molecular weight of the polyethylene is typically between one million and six million. The second elongate elements typically comprise oriented strand synthetic fibres of ultra high molecular weight polyethylene. Oriented strand synthetic fibres of high molecular weight polyethylene can be formed by a gel spinning through a spinneret. Second elongate elements can alternatively comprise ultra high molecular weight oriented polypropylene.

The second elongate elements can alternatively comprise comingled yarns of glass and polypropylene strands mechanically entwined together or glass cores with polypropylene sheaths. Advantageously, these hybrid yarns present an enhanced ability for bonding and/or fusing with the surface layer of the first elongate elements than if the second elongate elements had comprised glass alone.

The second elongate elements can alternatively comprise multifilament nucleated polypropylene yarns, such as those described in US patents US 7445842 B2, US7445834B2 and US 7074483 B2. The multifilament nucleated polypropylene yarns have a tenacity above 0.62 N/tex (7 g/denier), a tensile modulus over 13 N/tex (150 g/denier) and an elongation value of less than 10%. Advantageously, these multifilament nucleated polypropylenes have a higher strength than conventional oriented polypropylene yarns.

The second elongate elements can alternatively comprise basalt fibres.

Advantageously, basalt fibres do not melt or shrink when exposed to flame and can withstand temperatures up to about 650 °C.

The first tape is then woven with the second tape in the known manner to form a fabric or mat. The first and second tapes comprise warp and weft or weft and warp tapes respectively. The warp and weft tapes may be fibrillated to ease needle penetration. The weave pattern would normally be plain, but the skilled person would readily appreciate that twill or sateen weaves are also possible for this invention.

In the embodiment described above, the surface polymeric layers can be an amorphous layer constituted preferably by an ethylene-propylene co-polymer but other polymers such as polybutene-1, or a co-polymer of two or more polymers selected from butylene, ethylene and propylene can also be employed.

In the above-mentioned embodiment, the mat is described as being formed with a surface polymeric layer on both faces of the polypropylene film. It would, of course, be possible to provide a surface layer only on one side of the polypropylene film. Also, the polypropylene film can be oriented bi-axially rather than mono-axially.

Also, instead of the surface layer or layers being subsequently applied to a preformed polypropylene film, the composite film can be produced by co-extrusion of separate melt streams which are brought together and cooled to form a core layer of polypropylene to which is bonded on one or both sides a surface polymeric layer having a lower softening point than the polypropylene.

EXAMPLE 2

In a second embodiment of the present invention, the composite first tapes are formed as in Example 1 described above and woven with the second tapes in the usual way to form a mat. In a heat fusion stage, however, the mat is heated whilst constrained in a shaped mould or former. The applied heat then softens the thermoplastic outer layers and the product is then allowed to cool thereby producing an object having a three dimensional form dictated by the shape of the mould or former.

EXAMPLE 3

This Example relates to the manufacture of a self-reinforcing thermoplastic composite material suitable for general engineering applications.

In this Example, the material is produced from a first tape having a polypropylene (PP) core provided on both sides with a surface layer or cap coat of a random co-polymer of ethylene-propylene (ER). The polypropylene core is a polypropylene homo-polymer of 3.5 melt flow index (MFI). The ER/PR/ER tape structure has relative cross-sectional thickness of 7/86/7 where such thicknesses are expressed as a percentage of the total cross-sectional thickness of the tape.

The polymers are cast as a film on to chill rolls, slit and drawn in a hot air oven at a draw ratio of 12:1 prior to annealing and winding on to packages suitable for weaving. The first tapes thus produced are 130 tex, 2.5mm wide with a breaking force of 80 Newtons (N) and extension at failure of 15%. The surface layers are compatibly bonded to the polypropylene core by molecular interspersion between the contiguous surface of the layers and the core.

The first tapes were used as the warp or weft and the second tapes were used as the warp or weft to produce a plain woven fabric having a tape count of 40 tapes per cm width in the warp direction and 40 tapes per 10 cm width in the weft direction.

A plurality of layers or mats of this woven material were superimposed on each other and formed under heat and pressure in a single daylight press (e.g. 10 Bar at °C) to produce a self-reinforcing laminate on cooling. It will be readily apparent that any suitable number of layers can be incorporated depending on the desired strength and application of the fabric.

The first tapes can have a mono-axial or biaxial orientation and when the mats are superimposed upon each other, the axes of orientation of the woven tapes in each adjacent mat can be angularly displaced relative to each other so as to provide a cross-laid balanced structure having high impact strength.

In the above example, it is self-reinforced polypropylene (SRPP) which fulfils the function of a binder material to bond together the composite of dissimilar materials.

A self-reinforcing thermoplastic composite material comprising second tapes of UHMWPE was made. The fabric layers were overlapped in offset mode and each layer was turned through 90° relative to the layer below. So, for instance half of the sheets were orientated with warp running North-South with each alternating sheet having warp running East-West. The sheets were loaded into a flat-bed press which was closed at room temperature and loaded to a pressure of 100 psi. The temperature was then raised to 120 °C over a 40 minute period. The material was held at 120 °C for 15 minutes before being cooled to below 25 DC over a 20 minute period. The press was opened and the consolidated panel removed.

EXAMPLE 4

A self-reinforcing thermoplastic composite fabric is produced as described above in Example 3 with the difference that the first tapes during the extrusion process, are drawn at a draw ratio of 20:1 for the same film constituents. The increased draw ratio gives the 130 tex 2.5 mm wide first tape an improved breaking load of 100 N and reduced extension at failure of 10%.

EXAMPLE 5

A self-reinforcing thermoplastic composite fabric is produced as described in foregoing Example 4 with the difference that the surface layers or cap coats of the first tape are of a random co-polymer of ethylene/butylene instead of a co-polymer of ethylene/propylene.

EXAMPLE 6

This Example relates to the manufacture of an impact resistant sheet suitable for anti-ballistic protection.

In this Example, first tapes are co-extruded having a structure in which a polypropylene core has surface or cap layers on either side thereof of a random co-polymer of ethylene-propylene. The polypropylene is a homo-polymer having a melt flow index (MEl) of 3 and the EP/PP/EP tape structure has relative cross-section thicknesses of 7/86/7 where such thicknesses are expressed as a percentage of the total cross-sectional thickness of the tape.

The molten polymers are cast on to a chill roll to produce a composite film in which the surface layers are compatibly bonded to the polypropylene core by molecular interspersion between the contiguous surfaces of the layers and core. The composite film emanating therefrom is then slit and drawn in a hot air oven at a draw ratio of 12:1 before being annealed and wound up on to a package as a 130 tex tape of width 2.5 mm with a breaking force of 80 Newtons (NJ) and extension at break of 15%.

These first tapes are used for the warp (or weft), while the second tapes are used for the weft (or the warp) of a woven plain weave fabric having 40 tapes per 10 cm width in the warp direction and 40 tapes per 10 cm width in both warp and weft directions.

A plurality of layers or mats of the fabrics thus formed are superimposed on each other, crosslaid if desired, as described in Example 3, and formed under heat and pressure to produce, on cooling, a rigid, self-reinforcing, thermoplastic laminated composite material. The number of layers used to form the composite material can be varied in accordance with requirements.

Panels made from plain weave tapes as described above were subjected to attack from a 9 mm weapon using full service charge to propel a ball at normal impact from 15 metres range. Strike or impact velocities were in the range of 456-465 metres/second for a panel made at an areal density of lOkg/m2 from first tapes only. A standard impact velocity was measured in the tests, being the impact speed at which 50% of the ballistic missiles were stopped by the panel whilst the remaining 50% were passed through. This was 444 mIs for a panel made at an areal density of 1 Okg/m2 from first tapes only. For a panel made from first fibres with a second fibre of high tenacity multifilament nucleated polypropylene the V50 value measured was 40Gm/s.

A panel comprising first fibres with a second fibre of UHMWFE was ballistically tested against a 1.1 grain fragment simulating projectile (fsp). At an areal density of 10 kg/m2, the panel had a V50 measurement of 720 mIs. For an equivalent panel made from first tapes only, the V50 value measured was 573 mIs.

Above Examples 3 to 6 give specific relative percentage thicknesses for the surface layers and core. These relative thicknesses are not thought to be critical but it has been found that a surface layer having a thickness of 3% to 20% of the overall thickness of the first tape is satisfactory.

The multilayered composite sheet material as described above in Examples 3 to 5 can be used for a variety of other applications where strength is of importance e.g. for protective applications such as toe-caps for protective footwear, connecting straps of the handles of intermediate bulk containers or the containers themselves, tarpaulins, packaging, luggage, protective cases, pipes, fragmentation protection, ballistic protection, blast protection, packaging and general fabrication or in automotive or aerospace applications.

It will be appreciated that the embodiments of the present invention herein before described are given by way of example only and are not meant to be limiting to the scope of the invention in any way.

The above-described embodiments describe a composite material in which the constituent elongate elements such as tapes are intersected by weaving. It will be readily apparent that the mats or layers of elongate elements can be caused to intersect with each other by other processes e.g. by knitting or by the random laying down of fibrous webs. Furthermore, the mat or mats of fabrics formed in accordance with the present invention can be moulded into a variety of shapes. For example, the fabric can be formed into a tube or pipe by spirally winding the fabrics or tapes about a cylindrical mandrel.

Claims

<claim-text>CLAIMS1. A material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first eiongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein at least a surface of the second elongate elements comprises a material or materials dissimilar to the polymeric surface layer, and the first elongate elements are fusible together with the second elongate elements at least at intersections.</claim-text> <claim-text>2. A fabric or material as claimed in claim 1 that is formed without the use of, for example, a resin matrix material, a film or an adhesive.</claim-text> <claim-text>3. A fabric or material as claimed in any preceding claim, wherein the elongate elements are selected from tapes, threads, fibres, filaments, strands, or the like.</claim-text> <claim-text>4. A fabric or material as claimed in any preceding claim, wherein the elongate elements are selected from bundles of tapes, threads, fibres, filaments or strands.</claim-text> <claim-text>5. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise a single layer or homogenous layer.</claim-text> <claim-text>6. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise a plurality of layers.</claim-text> <claim-text>7. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise a material or materials dissimilar to the polymeric surface layer.</claim-text> <claim-text>8. A fabric or material as claimed in any preceding claim, wherein the first elongate elements and the second elongate members are formed as tapes.</claim-text> <claim-text>9. A fabric or material as claimed in any preceding claim, the first elongate elements comprise one or two surface layers or two opposing surface layers.</claim-text> <claim-text>10. A fabric or material as claimed in any preceding claim, wherein the first elongate elements comprise a layered structure comprising a base polymer sandwiched by two polymeric surface layers.</claim-text> <claim-text>11. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven, knitted, stitched, or are laid out to form a random fibrous web or are randomly interspersed to form the material.</claim-text> <claim-text>12. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven together to form a fabric.</claim-text> <claim-text>13. A fabric or material as claimed in any preceding claim, wherein the first elongate elements comprise a molecularly-oriented thermoplastic polymer base having at least one thermoplastic surface polymeric layer compatibly bonded to said polymer base by molecular interspersion between contiguous surfaces of the adjoining based surface layers.</claim-text> <claim-text>14. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven together to form the fabric or material and wherein the warp is formed of first or second elongate elements and the weft is formed of the other.</claim-text> <claim-text>15. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven together to form the fabric or material and wherein the warp is formed of first elongate elements and the weft is formed of second elongate elements.</claim-text> <claim-text>16. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven together to form the fabric or material and wherein the warp is formed of second elongate elements and the weft is formed of first elongate elements.</claim-text> <claim-text>17. A fabric or material as claimed in any preceding claim, wherein the elongate elements are woven together to form the fabric or material and wherein the warp and/or the weft comprise a mixture of first and second elongate elements.</claim-text> <claim-text>18. A fabric or material as claimed in claim 17, wherein the mixture of first and second elongate elements is a random arrangement of first and second elongate elements.</claim-text> <claim-text>19. A fabric or material as claimed in claim 17, wherein the mixture of first and second elongate elements is a regular alternation of first and second elongate elements.</claim-text> <claim-text>20. A fabric or material as claimed in any preceding claim, wherein the first elongate elements comprise a molecularly-oriented thermoplastic polymer base.</claim-text> <claim-text>21. A fabric or material as claimed in any preceding claim, wherein first elongate elements are selected from polypropylene, polyesters, polyethyleneterephthalate, polyamides, Nylon 6 or 6.6, or a polyethylene having a density in the range 0.940 to 0.970 or linear low density polyethylene.</claim-text> <claim-text>22. A fabric or material as claimed in any preceding claim, wherein the polymer base comprises a molecularly-oriented polyolefin polymer such as a polypropylene polymer.</claim-text> <claim-text>23. A fabric or material as claimed in any preceding claim, wherein the polymeric surface layer(s) is compatibly bonded to the polymer base by molecular interspersion between the contiguous surfaces of the adjoining base and surface layers.</claim-text> <claim-text>24. A fabric or material as claimed in any preceding claim, wherein the polymeric surface layer comprises a thermoplastic polymer or co-polymer.</claim-text> <claim-text>25. A fabric or material as claimed in any preceding claim, wherein the surface layer comprises ethylene-propylene co-polymer, polybutylene, polybutene-1 or a co-polymer comprising two or more of butylene, ethylene and propylene, co-polyesters and co-polyamides.</claim-text> <claim-text>26. A fabric or material as claimed in any preceding claim, wherein the polymer base is polypropylene and the surface layer comprises an ethylene-propylene co-polymer, a polybutylene such as polybutene-1 or a co-polymer comprising two or more of butylene, ethylene and propylene.</claim-text> <claim-text>27. A fabric or material as claimed in any preceding claim, wherein the polymer base is a polyester and the polymeric surface layer(s) comprise a co-polyester or wherein the polymer base is a polyamide and the surface layer(s) comprise a co-polyamide.</claim-text> <claim-text>28. A fabric or material as claimed in any preceding claim, wherein the second elongate elements, or at least a surface thereof, have a higher melting point than that of the polymeric surface layer.</claim-text> <claim-text>29. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise one or more of: polyesters, polyamides, aramids, thermoplastic polymers, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes (UHMWFA), such as ultra high molecular weight polyethylene (UHMWFE) or ultra high molecular weight polypropylene (UHMWPF), multifilament nucleated polypropylenes, glass fibres, basalt fibres and/or carbon fibres.</claim-text> <claim-text>30. A fabric or material as claimed in any preceding claim, wherein the second elongate elements are formed of hybrid yarns.</claim-text> <claim-text>31. A fabric or material as claimed in any preceding claim, wherein hybrid yarns are formed of at least two different materials or fibres comprising polyesters, polyamides, aramids, thermoplastic polymers, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes (UHMWPA), such as ultra high molecular weight polyethylene (UHMWPE) or ultra high molecular weight polypropylene (UHMWPP), multifilament nucleated polypropylenes, basalt fibres, glass fibres and/or carbon fibres.</claim-text> <claim-text>32. A fabric or material as claimed in any preceding claim, wherein the second elongate elements are formed of hybrid yarns selected from hybrid yarns comprising aramids and UHMWPE or hybrid yarns comprising polypropylene and glass.</claim-text> <claim-text>33. A fabric or material as claimed in any preceding claim, wherein the second elongate eiements comprise or consist of ultra high molecuiar weight poiyalkyienes selected from UHMWPE or UHMWPP.</claim-text> <claim-text>34. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise or consist of polyalkylenes having a molecular weight greater than approximately 30,000, greater than 500,000, greater than 1 million, greater than 2 million or greater than 3 million.</claim-text> <claim-text>35. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise or consist of polyalkylenes having a molecular weight between 30,000 and 15 million.</claim-text> <claim-text>36. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise polyethylene polymers wherein the molecular weight of the polyethylene is greater than approximately 500,000, greater than one million, greater than 2 million or greater than 3 million.</claim-text> <claim-text>37. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise polyethylene polymers wherein the molecular weight of the polyethylene is between 500,000 and 10 million, or between 1 million and 6 million.</claim-text> <claim-text>38. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise oriented strand synthetic fibres of ultra high molecular weight polyethylene.</claim-text> <claim-text>39. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise oriented strand synthetic fibres of ultra high molecular weight polyethylene which are formed by a gel spinning through a spinneret.</claim-text> <claim-text>40. A fabric or material as claimed in any preceding claim, wherein second elongate elements comprise high molecular weight oriented polypropylene.</claim-text> <claim-text>41. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise or consist of multifilament nucleated polypropylene elements.</claim-text> <claim-text>42. A fabric or material as claimed in any preceding claim, wherein the second elongate elements have a tensile strength above 0.35 N/tex (4g/denier), or above 0.62 Nltex (7 g/denier).</claim-text> <claim-text>43. A fabric or material as claimed in any preceding claim, wherein the second elongate elements have a tensile modulus above 13 N/tex (150 g/denier).</claim-text> <claim-text>44. A fabric or material as claimed in any preceding claim, wherein the second elongate elements have a density below 1.5 g/cm3, or below 1 g/cm3.</claim-text> <claim-text>45. A fabric or material as claimed in any preceding claim, wherein the second elongate elements have an elongation value between 0 and 20%, between 0.1 and 15%, or between 0.1 and 10%.</claim-text> <claim-text>46. A fabric or material as claimed in any preceding claim, wherein the second elongate elements comprise or consist of a polyalkylene having a density less than 1 g/cm3 and a tensile modulus above 13 N/tex (150 g/denier).</claim-text> <claim-text>47. A material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed: wherein the first elongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein the second elongate elements comprise a material or materials dissimilar to the base layer; and the first elongate elements are fusible together with the second elongate elements at least at intersections.</claim-text> <claim-text>48. A material or fabric comprising at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and polymeric surface layer, wherein the surface layer has a softening temperature lower than that of the polymer base; and wherein the second elongate eiements comprise a material selected from one or more of polyesters, polyamides, aramids, molecularly-oriented thermoplastic polymers, ultra high molecular weight polyalkylenes such as UHMWPE or UHMWPP, glass fibres, multifilament nucleated polypropylenes, basalt fibres and/or carbon fibres; and wherein the first elongate elements are fusible together with the second elongate elements at least at their intersections.</claim-text> <claim-text>49. A composite material which comprises at least one layer of fabric as claimed in any preceding claim.</claim-text> <claim-text>50. A composite material as claimed in claim 49, wherein the composite material comprises a plurality of layers.</claim-text> <claim-text>51. A composite material which comprises a plurality of layers of fabric as claimed in any of claims 1 to 48 which are fusible together at least at their interfaces.</claim-text> <claim-text>52. A method of making or forming a material or fabric as claimed in any of claims 1 to 48, the method comprising the steps of: mutually interspersing the elongate elements to form a fabric; and fusing the elongate elements together at least at their intersections.</claim-text> <claim-text>53. A method as claimed in claim 52, wherein mutually interspersing the elongate elements comprises weaving the elements together, knitting, stitching and/or the laying down of a random web.</claim-text> <claim-text>54. A method as claimed in any of claims 52 to 53, wherein fusing the elongate elements together comprises subjecting the fabric to different treatments.</claim-text> <claim-text>55. A method as claimed in any of claims 52 to 54, wherein fusing comprises one or more of: heating, pressurising, cooling and/or depressurising.</claim-text> <claim-text>56. A method as claimed in any of claims 52 to 55, wherein fusing comprises heating the fabric above the melting temperature of the polymeric surface layer.</claim-text> <claim-text>57. A method as claimed in any of claims 52 to 56, wherein fusing comprises cooling the fabric to allow the surface iayer to solidify.</claim-text> <claim-text>58. A method as claimed in any of claims 52 to 57, wherein fusing the elements comprises subjecting the fabric to pressure.</claim-text> <claim-text>59. A method as claimed in any of claims 52 to 58, wherein fusing is achieved by single closure press with flat or contoured plates, continuous belt press, induction heated press or via vacuum bagging and autoclaving.</claim-text> <claim-text>60. A method for making a composite material which comprises a fabric as claimed in any of claims 1 to 48 which comprises the steps of: layering of the fabrics; and fusing the layers of fabric together at least at their interfaces.</claim-text> <claim-text>61. A method as claimed in claim 60, wherein layering of the fabrics comprises stacking of two or more fabric layers.</claim-text> <claim-text>62. A method as claimed in claims 60 and 61, wherein the fabric layers are superimposed.</claim-text> <claim-text>63. A method as claimed in any of claims 60 to 62, wherein the axes of orientation of the first elongate elements may be angularly displaced relative to the axes of orientation of the first elongate elements in an adjacent fabric layer.</claim-text> <claim-text>64. A method as claimed in any of claims 60 to 63, wherein axes of orientation of the first elongate elements may be angularly displaced by substantially 900 relative to the axes of orientation of the first elongate elements in an adjacent fabric layer.</claim-text> <claim-text>65. A method as claimed in any of claims 60 to 64, wherein fusing refers to the fusing of individual elongate elements to each other.</claim-text> <claim-text>66. A method as claimed in any of claims 60 to 65, wherein fusing refers to the bonding of individual elongate elements within a fabric at least at their intersections.</claim-text> <claim-text>67. A method as claimed in any of claims 60 to 66, wherein fusing refers to the bonding of individual elongate elements present in different fabric layers at east at their interfaces.</claim-text> <claim-text>68. A method as claimed in any of claims 60 to 67, wherein fusing comprises heating, pressurising, cooling and/or depressurising.</claim-text> <claim-text>69. A method as claimed in any of claims 60 to 68, wherein fusing comprises heating above the melting temperature of the polymeric surface layer.</claim-text> <claim-text>70. A method as claimed in any of claims 60 to 69, wherein fusing comprises cooling to allow the polymeric surface layer to solidify.</claim-text> <claim-text>71. A method as claimed in any of claims 60 to 70, wherein fusing the elements comprises subjecting the fabric to pressure.</claim-text> <claim-text>72. A method as claimed in any of claims 60 to 71, wherein heating is effected within or in relation to a mould or the like whereby on cooling, the material may assume a predetermined three-dimensional form.</claim-text> <claim-text>73. An article which comprises a fabric or a composite material as claimed in any of claims ito 51.</claim-text> <claim-text>74. An article as claimed in claim 73 which has high-impact resistance properties.</claim-text> <claim-text>75. An article as claimed in claims 73 and 74 which is made for antiballistic purposes and/or which comprises bulletproof vests, body armour, panels suitable for the protection of military and commercial vehicles, bin liners, blast basket or blast blankets to contain fragmentation debris from the detonation of explosive devices..</claim-text> <claim-text>76. An article as claimed in any of claims 73 to 75 which is used as carpet backing, which is used in automotive or aerospace applications or which comprises panels suitable for use on automotive vehicles.</claim-text> <claim-text>77. An article as claimed in any of ciaims 73 to 76 which comprises toe-caps for protective footwear, connecting straps of the handles of intermediate bulk containers or the containers themselves, tarpaulins, packaging, luggage, protective cases, pipes.</claim-text> <claim-text>78. A thermoplastic composite material comprising at least one mat of mutually intersecting first elements and second elements fusible together at least at their intersections, each of said first elements comprising a molecularly-oriented thermoplastic polymer base having at least one thermoplastic surface polymeric layer compatibly bonded to said polymer base by molecular interspersion between the contiguous surfaces of the adjoining base and surface layers, and said surface polymeric layer having a softening temperature lower than that of the polymer base, and said second elements comprising at least one surface made from a different material to the thermoplastic surface polymer layer of the first element.</claim-text> <claim-text>79. A fabric or material substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>80. A method of making a fabric or material substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>81. A composite material substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>82. An article comprising a fabric or material substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>83. A material or fabric comprising: at least first elongate elements and second elongate elements that are mutually interspersed; wherein the first elongate elements comprise a polymer base and at least one polymeric surface layer, wherein the at least one polymeric surface layer has a softening temperature lower than that of the polymer base; and wherein at least a surface of the second elongate elements comprises a polyalkylene having a density less than 1 glcm3 and a tensile modulus above 13 Nltex (150 g/denier), and the first eiongate elements are fusible together with the second elongate elements at least at intersections.</claim-text>