Ballistic-resistant article

Abstract

Ballistic-resistant article A ballistic-resistant article comprising: a first layer comprising a first polymer material reinforced with basalt fibres; and a second layer laminated on the first layer, the second layer comprising a second polymer material reinforced with one or more of resin particles, carbon fibres, graphene particles, graphene-based particles and ceramic particles.

Description

[0001] Ballistic-resistant article

[0002] The present invention relates to a ballistic-resistant article, a method of manufacturing a ballistic-resistant article, a method of manufacturing a structural shell, a structural shell, and a method of manufacturing a structural shell using resin transfer moulding.

[0003] Composite materials comprising fibre-reinforced resins are known, typically reinforced with fiberglass and / or carbon fibre. Such fibre-reinforced resins are strong, light weight and easy to mould into a desired shape.

[0004] KR20190079109A discloses a method of fabrication of a composite for a boat comprising basalt fibres, and a boat fabricated using the same. CN109370186A relates to a production method of a low-temperature-resistant and environmentfriendly glass fiber-reinforced plastic septic tank. CN111098528A relates to a system for producing a fully impregnated thermoplastic prepreg.

[0005] US2019 / 330432A relates to a two-component hybrid matrix system made of polyurethanes and polymethacrylates for the production of short-fibre-reinforced semi-finished products. US 2020 / 047427A relates to a process for manufacturing thermoplastic polymer composite parts, and an object obtained by said process. WO 2020 / 088173A1 relates to a porous composite material capable of generating an electric arc in a microwave field, a preparation method therefor, and use thereof. JPH11335929A relates to a highly electroconductive carbon fiber and its production. JP2003012857A relates to a treatment method for a waste fiber-reinforced plastic material and a treatment apparatus.

[0006] GB2602444A and WO2022 / 101003A1 , the contents of which are hereby incorporated by reference, disclose a recyclable structural shell for a hull, structural grid and / or deck for a marine vessel or a wind turbine blade and the like, a method of manufacturing a structural shell and a method of disassembling a structural shell. The structural shell comprises a basalt fibre-reinforced material, wherein the basalt fibre-reinforced material comprises a polymer material, the polymer material being capable of at least partially thermally cracking at a temperature of from 200 to 600°C. The structural shell may be manufactured with high flexural strength per unit area for use in a hull for a marine vessel and the like, wherein the basalt fibres are recoverable at end of life, without substantial, or preferably any, deterioration in physical and / or mechanical properties of the basalt fibres. While the structural shell may exhibit ballistic-resistance, there is a need to improve further the ballistic-resistance of the structural shell. There is also a need to improve the fire-retardance of the structural shell. Furthermore, there is a need to improve the method of manufacturing the structural shell.

[0007] Incorporating fillers, such as a flame retardant, to a resin of a composite material is known. However, the addition of such fillers may adversely increase the viscosity of the resin, meaning that manufacture of the composite material may be difficult. Furthermore, when the composite material is a fibre-reinforced composite material, the fibres may act as a particle filter preventing the incorporation of the additive and preventing infusion of the resin into the fibres. FR3108554A1 describes a composite structure comprising reinforcing fibres and a resin. The resin may contain fillers, such as a fire retardant. Accordingly, the composite structure may exhibit fire retardance. In order to successfully infuse the resin into the fibres and incorporate the filler into the composite structure, gaps are provided between adjacent fibres. However, this may compromise the strength of the composite material. Accordingly, there is a need to provide a structural shell having a combination of high fire retardance and high strength that can be manufactured more easily.

[0008] US2007 / 224401 A1 describes in accordance with its abstract a spaced, multilayer article of manufacture comprising a first layer comprising about 10% to about 80% by weight basalt particles, about 2% to about 50% by weight reinforcing fibers, and about 5% to about 50% by weight of an adhesive resin binder; a second layer comprising about 10% to about 80% by weight basalt particles, about 2% to about 50% by weight reinforcing fibers, and about 5% to about 50% by weight of an adhesive resin binder; and an intermediate spacing layer that separates the first and second layers. The present invention seeks to tackle at least some of the problems associated with the prior art or at least to provide a commercially acceptable alternative solution thereto.

[0009] In a first aspect, the present invention provides a ballistic-resistant article comprising: a first layer comprising a first polymer material reinforced with basalt fibres; and a second layer laminated on the first layer, the second layer comprising a second polymer material reinforced with one or more of resin particles, carbon fibres, graphene particles, graphene-based particles and ceramic particles.

[0010] Each aspect or embodiment as defined herein may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any features indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0011] The term “ballistic-resistant article” as used herein may encompass an article capable of stopping, or reducing the velocity of, a bullet or other high-velocity projectile (e.g. shrapnel). The term “ballistic-resistant” may encompass, bulletresistant and / or bullet-proof.

[0012] The term “a first polymer material reinforced with basalt fibres” as used herein may encompass a composite material reinforced with basalt fibres. Typically, the composite material comprises a matrix of the first polymer material reinforced with basalt fibres, i.e. having basalt fibres dispersed therein.

[0013] The term “basalt fibre” as used herein may encompass a material made from extremely fine fibres of basalt, which is composed of the minerals plagioclase, pyroxene, and olivine. The basalt fibres may be manufactured by a method comprising melting bulk basalt, homogenising the basalt and extracting the fibres by extrusion of the molten basalt, for example. Preferably, basalt of high acidity (over 46% silica content) and low iron content is used for the manufacture of the basalt fibres. Typically, the bulk basalt is crushed and washed before melting. The basalt fibres typically have a filament diameter of between 10 and 20 pm. The basalt fibres preferably have a density of from 100 to 300 gsm, more preferably from 150 to 250 gsm, even more preferably about 200 gsm. The basalt fibres preferably have a tensile strength of from 3 to 6 GPa, more preferably from 4 to 5 GPa, even more preferably about 4.5 GPa.

[0014] Then term “layer” as used herein in relation to the first and second layers may encompass a sheet.

[0015] The second layer is laminated on the first layer. The second layer is typically laminated directly on the first layer, i.e. the first and second layers are in direct contact. However, in some situations, the first and second layers may be separated by a further layer.

[0016] The article may comprise more than one of each of the first and second layers. In such case, the first and second layers may form a stack of alternately stacked first and second layers.

[0017] The resin particles and ceramic particles may be in the form of, for example, fibres or a powder. The resin particles and ceramic particles may have a weight or density of from 100 to 300 gsm, preferably from 150 to 250 gsm, more preferably about 200 gsm.

[0018] The inventors have surprisingly found that the ballistic-resistant article may exhibit a particularly high ballistics resistance and may exhibit a ballistic resistance greater than that exhibited by the structural shells disclosed in GB2602444A and WO2022 / 101003A1 . The ballistic-resistant article may exhibit a ballistic resistance satisfying up to NIJ-STD-0108.01 Level III. Surprisingly, the ballistic resistance of the article may be greater than an article comprising only the first layer or only the second layer, for the same total thickness. Without being bound by theory, it is considered that this improved ballistics resistance may result from a synergistic relationship between the two layers. In particular, it is considered that the first layer may provide structural support to the article and helps to dissipate the impact energy across the entire article. The second layer may provide the majority of the article’s ballistic resistance. By dissipating the impact energy across the entire article, the ballistic resistance provided by the second layer may be improved.

[0019] Advantageously, the presence of the first layer may render the article more lightweight and / or durable in comparison to an article of the same thickness having only the second layer. Accordingly, the presence of both the first and second layers may provide a favourable combination of high ballistic resistance, high durability and low weight.

[0020] The second polymer material is preferably reinforced with resin particles. This may provide a particularly high ballistic resistance. When the second polymer material is reinforced with resin particles, the second polymer material may be reinforced with resin particles only, or with resin particles and one or more of carbon fibres, graphene particles, graphene-based particles and ceramic particles.

[0021] The resin particles preferably comprise: polyethylene, preferably ultra high molecular weight polyethylene (UHMWPE); and / or aromatic polyamide (aramid), preferably para-aromatic polyamide, more preferably poly(azanediyl-1 ,4- phenyleneazanediylterephthaloyl). Suitable commercial examples of such species include Kevlar® and Twaron®. Such resin particles may provide a particularly high ballistic resistance. The UHMWPE preferably has a tensile strength of from 2 to 5 GPa, more preferably from 2.5 to 4.5 GPa, even more preferably from 3 to 4 GPa, still even more preferably about 3.5 GPa. The UHMWPE preferably has a density of from 0.5 to 2 g / cm3, more preferably from 0.7 to 1 .5 g / cm3, even more preferably from 0.9 to 1 .1 g / cm3.

[0022] The resin particles are preferably in the form of fibres. This may improve the ballistic resistance. The second polymer material is preferably reinforced with ceramic particles. This may provide a particularly high ballistic resistance.

[0023] The ceramic particles preferably comprise one or more of alumina, a carbide, a nitride and a cermet, more preferably one or more of aluminium oxide (AI2O3), boron carbide (B4C), silicon carbide (SiC), tungsten carbide (WC), zirconium carbide (ZrC), titanium carbide (TiC), cobalt chromium carbide (CoCrCr3C2), aluminium nitride (AIN). The ceramic particles may comprise glass fibres. Such particles may provide a particularly high ballistic resistance.

[0024] The first polymer material and / or the second polymer material preferably comprises a thermoplastic polymer. The term “thermoplastic polymer” as used herein may encompass a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. A thermoplastic may be particularly suitable as the first and / or second polymer material. The use of a thermoplastic in the first layer may be contribute to dissipating the impact energy across the entire article. The use of a thermoplastic in the second layer may contribute to the high ballistic resistance.

[0025] The first polymer material and / or the second polymer material preferably comprises one or more of polyether ether ketone (PEEK), poly amide imide (PAI), methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA) and a styrenic block copolymer (SBC) formed of polystyrene blocks and rubber blocks, more preferably wherein the rubber blocks consist of polybutadiene, polyisoprene, or their hydrogenated equivalents (e.g. Kraton™ elastomers).

[0026] The second polymer material is preferably reinforced with carbon fibres. This may provide a particularly high ballistic resistance.

[0027] The second polymer material is preferably reinforced with graphene particles and / or graphene-based particles. This may provide a particularly high ballistic resistance. The graphene may be single layer graphene or bilayer graphene or few layer graphene (FLG) or multilayer graphene (MLG). The graphene-based particles may comprise graphene oxide and / or functionalised graphene.

[0028] The first polymer material may be different to the second polymer material. However, preferably the first polymer material is the same as the second polymer material. This may simplify manufacturing and may help to avoid delamination of the first and second layers, thereby decreasing the durability and / or structural integrity of the article.

[0029] The ballistic-resistant article preferably comprises at least 10 each of the first and second layers, preferably at least 20 each of the first and second layers, the first layers and the second layers being alternately stacked. This may improve the ballistic resistance of the article.

[0030] The ballistic-resistant article preferably satisfies NIJ-STD-0108.01 Level IIIA, more preferably Level III.

[0031] The ballistic-resistant article preferably further comprises outer polymer layers. This may improve the durability and / or structural integrity of the article and / or allow a desired surface finish to the article. The outer polymer layers may be different to one or both of the first and second polymer materials. Typically, the outer polymer layers are formed of the first and second polymer materials, i.e. the polymer of the outer polymer layers is the same as the polymer of first and second polymer material.

[0032] The first layer and / or the second layer preferably comprises one or more additives selected from: a catalyst, a dye, a pigment, a flame-retardant additive, a hardening agent, a filler, a deoxidiser, an elastomer, UV Stabilizers, and antioxidant, an antimicrobial agent, an impact modifier, a plasticizer, an anti-static agent, and an adhesion promotor.

[0033] In a preferred embodiment, the second polymer material is reinforced with UHMWPE fibres and the ballistic-resistant article further comprises a third layer laminated on the second layer, the third layer comprising a third polymer material reinforced with ceramic particles, preferably boron carbide particles. Such an embodiment may exhibit a particularly favourable combination of high ballistic resistance, high durability and low weight. The boron carbide preferably has a Vickers hardness of from 10 to 50 GPa, more preferably from 20 to 40 GPA, even more preferably from 25 to 35 GPa, still even more preferably around 30 GPa. The boron carbide preferably has a density of from 1 to 4 g / cm3, more preferably from 1 .5 to 3.5 g / cm3, even more preferably from 2 to 3 g / cm3, still even more preferably about 2.5 g / cm3.

[0034] In a preferred embodiment, the second layer is sandwiched between two first layers. Such an embodiment may exhibit a particularly favourable combination of high ballistic resistance, high durability and low weight.

[0035] In a preferred embodiment, the first layer is sandwiched between two second layers. Such an embodiment may exhibit a particularly favourable combination of high ballistic resistance, high durability and low weight. In a particularly preferred embodiment, the first layer is sandwiched between two second layers, wherein the second layers comprise alumina.

[0036] The first layer and or the second layer preferably has a thickness of from 0.05 mm to 5 mm, more preferably from 0.08 mm to 4 mm, even more preferably from 0.1 mm to 3 mm. Such thicknesses may help to provide a particularly favourable combination of high ballistic resistance, high durability and low weight.

[0037] The thickness of the ballistic-resistant article is preferably from 0.5 mm to 150 mm, more preferably from 0.8 to 120 mm, even more preferably from 1 mm to 100 mm. Such thicknesses may help to provide a particularly favourable combination of high ballistic resistance, high durability and low weight.

[0038] In the first layer, the ratio of first polymer material to basalt fibres by weight is preferably from 20 % to 60 % based on the total weight of first polymer material and basalt fibres. In other words, the first layer may comprise from 20 % first polymer material / 80 % basalt fibres to 60 % first polymer material / 40 % basalt fibres. This may result in particularly favourable impact force dissipation and / or ballistic resistance and / or structural integrity. In particular, this may improve the first layer’s contribution to the overall ballistic resistance of the article.

[0039] In the second layer, the ratio of second polymer material to one or both of resin particles and ceramic particles by weight is from 20 % to 60 % based on the total weight of second polymer material and resin particles and ceramic particles. In other words, the second layer may comprise from 20 % second polymer material 180 % resin particles and ceramic particles to 60 % second polymer material polymer 140 % resin particles and ceramic particles. This may result in particularly favourable ballistic resistance.

[0040] In a further aspect, the present invention provides body armour comprising the ballistic-resistant article described herein. The body armour may be in the form of a bullet-proof vest.

[0041] The advantages and preferable features of the first aspect apply equally to this aspect.

[0042] In a further aspect, the present invention provides a helmet comprising the ballistic-resistant article described herein. The helmet may be a military helmet, for example an infantry helmet. The helmet may be a motorcycle helmet.

[0043] The advantages and preferable features of the first aspect apply equally to this aspect.

[0044] In a further aspect, the present invention provides a vehicle comprising the ballistic-resistant article described herein. The vehicle may be a military vehicle, such as, for example, an armoured car, armoured personnel carrier (APC), infantry fighting vehicle, tank, motorcycle, armoured recovery vehicle, armoured repair vehicle, artillery vehicle, armoured truck or ambulance. The advantages and preferable features of the first aspect apply equally to this aspect.

[0045] In a further aspect, the present invention provides an aircraft comprising the ballistic-resistant article described herein. The aircraft may be a fixed wing or a rotary wing aircraft. The aircraft may be a miliary aircraft such as, for example, a bomber aircraft, a fighter aircraft, a drone, a reconnaissance aircraft, a surveillance aircraft, a transport aircraft or an electronic warfare aircraft.

[0046] The advantages and preferable features of the first aspect apply equally to this aspect.

[0047] In a further aspect, the present invention provides a watercraft comprising the ballistic-resistant article described herein. The watercraft may be a boat or a hovercraft. The watercraft may be a military watercraft such as, for example, an army work boat, a combat support boat, a mexaflote, a warship, a tanker, a landing craft, a RIB, a raiding craft, an aircraft carrier, a destroyer, a frigate, a mine hunter, a transport craft or an icebreaker.

[0048] The advantages and preferable features of the first aspect apply equally to this aspect.

[0049] In a further aspect, the present invention provides a building comprising the ballistic-resistant article described herein.

[0050] The advantages and preferable features of the first aspect apply equally to this aspect.

[0051] In a further aspect, the present invention provides a method of manufacturing the ballistic-resistant article described herein, the method comprising: providing a mould; forming a layup in the mould, the layup comprising a layer of basalt fibres and a layer of ceramic particles and / or resin particles; contacting the layup with a mixture comprising a resin and a hardening agent at a relative pressure of -0.65 bar to provide a ballistic-resistant article; and recovering the ballistic-resistant article from the mould.

[0052] The advantages and preferable features of the first aspect apply equally to this aspect.

[0053] The method preferably comprises pultrusion and / or resin transfer moulding (RTM).

[0054] The method preferably further comprises machining the ballistic-resistant article. This may be carried out to provide the article with a desired shape and / or finish.

[0055] In a further aspect (“fire retardant aspect”), the present invention provides a method of manufacturing a structural shell, the method comprising: providing in a mould; introducing into the mould a stack comprising a first layer of reinforcing fibres and a second layer of fire retardant filler; contacting the first and second layers with a mixture comprising a resin and a hardening agent at a relative pressure of -0.65 bar to provide a structural shell; and recovering the structural shell from the mould.

[0056] The advantages and preferable features of the first aspect apply equally to this aspect.

[0057] Surprisingly, the method may result in a structural shell having a favourable combination of high strength and high fire retardance. In particular, in contrast to the method described in FR3108554A1 , the method of the present invention results in a structural shell having high fire retardance while retaining its high strength. Without being bound by theory, it is considered that by having separate layers of the reinforcing fibres and fire retardant filler, the structural shell may comprise fire retardant filler without preventing or inhibiting infusion of the resin into the reinforcing fibres. By avoiding large gaps between the fibres, in contrast to the method of FR3108554A1 , the strength of the structural shell is high.

[0058] The term “structural shell” as used herein may comprise a laminar sheet or layer of material having a thickness significantly smaller than a major surface area. The structural shell may therefore be a thin walled body. The structural shell may be for withstanding external loads, such as fluid pressure, aerodynamic loads and / or impacts, applied to the major surface area of the material. In particular, the structural shell may be a hull and / or deck of a marine vessel, a blade of a wind turbine, ski and / or ski pole, a fuselage of an aircraft, a body of a land vehicle and the like. The structural shell may be supported by a frame.

[0059] The fire retardant filler may be in the form of fibres or a powder, typically a powder.

[0060] The term “mould” as used herein may encompass a hollow container or shell used to give shape to the resin on curing into the basalt fibre-reinforced material. The mould may be suitable for shaping the resin into a shape such as, for example, a hull and / or deck of a marine vessel, a blade of a wind turbine, a fuselage of an aircraft, a body of a land vehicle and the like.

[0061] The reinforcing fibres may be introduced into the mould in a regular arrangement, preferably wherein the reinforcing fibres are introduced into the mould so that the resulting fibre-reinforced material comprises a plurality of layers of substantially parallel reinforcing fibres, wherein the average direction of the substantially parallel reinforcing fibres is different in adjacent layers. More preferably, the reinforcing fibres are introduced into the mould so that the average direction of the substantially parallel reinforcing fibres in each layer is about 45° or about 90° relative to the average direction of the substantially parallel reinforcing fibres in adjacent layers. Most preferably, the reinforcing fibres are introduced into the mould so that the the layers of substantially parallel reinforcing fibres are arranged quadri-axially, preferably with relative directions of the basalt fibers of - 45°, 90°, 0-90° and 0°, tri-axially, preferably with relative directions of the reinforcing fibres of -45°, 90° and 45°, bi-axially, preferably with relative directions of the reinforcing fibres of 0° and 90°, or uni-directionally. Such an arrangement of the reinforcing fibres within the structural shell may provide a quasi-isotropic composite material which exhibits substantially equal mechanical properties in all planar directions. Such an arrangement of the reinforcing fibres may also provide a structural shell with desirably high flexural strength per unit area and resistance to wear.

[0062] Without wishing to be bound by theory, it is thought that the negative relative pressure applied during the contacting step may enable the resin to fully encapsulate the reinforcing fibres, while also eliminating substantially all of the gas voids from the reinforcing fibre-reinforced material. Thus, a structural shell may be provided which may be substantially free of gas voids. Such a structural shell may exhibit desirably high flexural strength per unit area and / or impact resistance and / or reduced likelihood of delamination on flexing or bending.

[0063] The method may advantageously comprise one or more of: the application of ultrasonic sound waves during the contacting step so as to improve resin flow during infusion; hand lay-up of composite elements; pultrusion; a prepreg process; resin transfer moulding; and vacuum-assisted resin transfer moulding.

[0064] The term “resin” as used herein may encompass a fluid comprising monomers and / or polymers that, when mixed with the hardening agent, is capable of polymerisation and / or crosslinking to provide a solid polymer material. The term “hardening agent” as used herein may encompass a substance that causes the resin to harden, for example by polymerisation and / or crosslinking, or otherwise. Preferably, the resin comprises methacrylate monomers, more preferably methyl methacrylate monomers, and even more preferably from 50 to 85 wt.% methyl methacrylate monomers and / or from 10 to 50 wt.% acrylic polymers.

[0065] Preferably, the hardening agent comprises an organic peroxide, preferably benzoyl peroxide. A commercially available organic peroxide that is particularly suitable for use in the present invention is Perkadox® GB-50X from Nouryon. Other organic peroxides and / or Perkadox® hardeners may be used. For example, di(2,4-dichlorobenzoyl) peroxide, di(4-methylbenzoyl) peroxide, di(tert- butylperoxyisopropyl)benzene and / or dicumyl peroxide, or mixtures thereof, including or not including benzoyl peroxide. Other commercially available organic peroxides that are particularly suitable for use in the present invention are Elium® 191XO / SA (for longer polymerisation time of circa three hours) and Elium® 158XO / SA (for shorter polymerisation time of circa one hour) from Arkema. These are three component all liquid systems, including two resins and a hardener (mekp type Butanox M50).

[0066] Preferably, the mixture comprises the hardening agent in an amount of from 0.5 to 30 phr, more preferably from 1 to 15 phr, even more preferably from 1 .5 to 4 phr, still more preferably from 2.5 to 4 phr (wherein “phr” mean parts per hundred by weight in the present context). This is typically the amount required to provide satisfactory hardening of the resin to obtain the basalt fibre-reinforced material described herein.

[0067] Typically, the reinforcing fibres are contacted with the mixture at a relative pressure of from -0.65 to -1 .15 bar. Preferably, the reinforcing fibres are contacted with the mixture at a relative pressure of from -0.7 to -1 .15 bar, more preferably from -0.85 to -1 .15 bar, even more preferably from -0.9 to -1 .1 bar, still even more preferably from -0.95 to -1 .05 bar. A relative pressure of greater than - 0.65 bar, or for some materials -0.85 bar, typically does not eliminate substantially all of the gas voids from the basalt fibre-reinforced material and / or enable a strong bond to be formed between the polymer material and the reinforcing fibres. In general, the lower the relative pressure, the denser the resulting basalt fibre-reinforced material and the stronger the bond formed between the reinforcing fibres and the polymer material. This lower pressure is particularly critical when the structural shell comprises a polymer core. Without wishing to be bound by theory, this is so that the resin may be sucked substantially through all of the voids in the foam of the polymer core, preferably through all of the voids in the foam. However, a relative pressure of less than - 1 .15 bar may deform the mould and / or the basalt fibre-reinforced material. Moreover, such a low relative pressure may damage the vacuum bag. For some structural shell designs, a relative pressure of less than -1 .05 bar may deform the mould and / or the structural shell.

[0068] Typically, the reinforcing fibres are contacted with the mixture at a temperature of from 10 to 40°C, preferably from 14 to 30°C. Such a temperature range enables significant cost savings during the manufacturing process at least because less complex equipment may be required.

[0069] Typically, the reinforcing fibres are contacted with the mixture at a humidity of from 30 to 70%, preferably from 40 to 50%.

[0070] Preferably, the reinforcing fibres are contacted with the mixture under the applied pressure for from 5 minutes to 12 hours, preferably for from 1 hour to 6 hours, more preferably for from 90 minutes to 3 hours. The reinforcing fibres are contacted with the mixture under the applied pressure for a time suitable for providing a solid structural shell. This may be to enable the structural shell to fully solidify before being removed from the mould. Higher contacting temperatures may require shorter contacting times.

[0071] Once the structural shell has been recovered from the mould, it may be subjected to a temperature of from 50 to 150 °C, typically for a time of from 1 to 10 hours. This may constitute a “post curing” step.

[0072] Contacting the first and second layers with a mixture comprising a resin and a hardening agent typically comprises introducing the resin and hardening agents into a bag containing the mould. Typically, the resin and hardening agent are exposed to atmospheric pressure to cause the resin and hardening agent to enter the (reduced pressure) bag. Alternatively, the resin and hardening agent are exposed to a positive pressure of from +0.1 to +15 bar, preferably from +0.2 t +0.6 bar, to cause the resin and hardening agent to enter the bag.

[0073] In a further embodiment, the method further comprises forming a gelcoat in the mould prior to the introduction of the stack into the mould.

[0074] In a further embodiment, the method further comprises introducing a polymer core into the mould prior to contacting the first and second layers with the mixture. Typically, the polymer core is introduced into the mould between two or more reinforcing fibres, preferably wherein the polymer core is introduced into the mould to form a layer separating two or more layers of reinforcing fibres. The polymer core may be introduced into the mould and surrounded by the reinforcing fibres. Alternatively, the polymer core may be sandwiched between layers of reinforcing fibres.

[0075] In some embodiments, the mixture further comprises a rheology modifier and / or release agent. Rheology modifiers may improve the flow of the resin into the mould and release agents may help make removing the structural shell and the like from the mould easier. Examples of such additives include Cirex® 388 and Chemtrend® R&B.

[0076] Moreover, the method of manufacturing the structural shell and the like described herein may also be safer than those of the prior art. This may be because the reaction of the resin and hardening agent used herein is less exothermic than those of the prior art for making hulls for marine vessels and the like, particularly when the resin and hardening agent used are as described above. Thus, the method may pose less of a fire risk during the vacuum infusion process, because the structural shell or the like being manufactured may heat up to a lower temperature. The first and second layers are preferably in contact via an adhesive. The adhesive may be, for example, a solvent-based adhesive or a water-based adhesive. The adhesive may be applied, for example, via an aerosol spray or a brush.

[0077] The reinforcing fibres preferably comprise basalt fibres. The fibres may be weaved, for example unidirectional, biaxial, triaxial or quadraxial. Particular suitable basalt fibres are biaxial basalt fibres having a density of from 400 to 800 g / m3, preferably 500 to 700 g / m3, more preferably 550 to 650 g / m3.

[0078] The fire retardant filler preferably comprises one or more of aluminium hydroxide (AI(OH)3), magnesium hydroxide (Mg(OH)2), huntite (Mg3Ca(CO3)4), hydromagnesite (Mg5(CO3)4(OH)2-4H2O), red phosphorus, zinc borate, aluminium phosophate (AIPC ), melamine cyanurate, antimony trioxide (SbC ), hindered amine light stabilizers (HALS), graphene and a graphene-based material.

[0079] The resin preferably comprises methacrylate monomers, preferably methyl methacrylate monomers, more preferably from 50 to 85 wt.% methyl methacrylate monomers and / or from 10 to 50 wt.% acrylic polymers.

[0080] The hardening agent preferably comprises an organic peroxide, preferably benzoyl peroxide.

[0081] The mixture preferably comprises the hardening agent in an amount of from 0.5 to 30 phr, more preferably from 1 to 15 phr, even more preferably from 1 .5 to 4 phr, still even more preferably from 2.5 to 4 phr.

[0082] The first and second layers are preferably contacted with the mixture at a relative pressure of from -0.7 to -1 .15 bar, preferably from -0.9 to -1 .1 bar, more preferably from -0.95 to -1 .05 bar. The first and second layers are preferably contacted with the mixture at a temperature of from 30 to 70 °C, preferably from 40 to 60 °C, more preferably from 45 to 55 °C. This may result in curing of the resin.

[0083] The first and second layers are preferably contacted with the mixture at a humidity of from 30 to 70%, preferably from 40 to 50%.

[0084] The first and second layers are preferably contacted with the mixture under the applied pressure for from 5 minutes to 12 hours, more preferably for from 1 hour to 6 hours, even more preferably for from 90 minutes to 3 hours.

[0085] The method preferably further comprises forming a gelcoat in the mould prior to introducing into the stack into the mould.

[0086] The gelcoat preferably comprises a fire retardant filler.

[0087] The stack preferably comprises at least two of the first layers and at least two of the second layers, the first and second layers being alternately stacked, preferably wherein the stack comprises at least three of the first layers and at least three of the second layers.

[0088] The stack preferably comprises five of the first layers each separated by a second layer.

[0089] Preferably, in the composite material, the second layer comprises, based on the total weight of the second layer, from 5 to 50 wt.% of the fire retardant filler, more preferably: from 8 to 16 wt.% of the fire retardant filler, more preferably from 10 to 14 wt.% the fire retardant filler; or from 20 to 28 wt.% of the fire retardant filler, more preferably from 22 to 26 wt.% the fire retardant filler. In a further aspect, the present invention provides a structural shell obtainable by the method described herein.

[0090] The advantages and preferable features of the fire retardant aspect apply equally to this aspect.

[0091] In a further aspect, the present invention provides a structural shell comprising a stack of a first layer of reinforcing fibres and a second layer of fire retardant filler, the first and second layers being infused with a polymer material comprising a methyl methacrylate.

[0092] The advantages and preferable features of the fire retardant aspect apply equally to this aspect.

[0093] The polymer material preferably comprises a poly(methyl methacrylate).

[0094] The composite material preferably meets the requirements of EC45545.

[0095] In a further aspect, the present invention provides a train, tram, hull, deck, structural grid, watercraft, aircraft, vehicle, building, ski, ski pole, ballistic resistant panel or helmet comprising the structural shell described herein.

[0096] The advantages and preferable features of the fire retardant aspect apply equally to this aspect.

[0097] In a further aspect (“RTM aspect”), the present invention provides a method of manufacturing a structural shell using resin transfer moulding, the structural shell comprising a basalt fibre-reinforced material, wherein the basalt fibre-reinforced material comprises a polymer material, the polymer material being capable of at least partially thermally cracking at a temperature of from 200 to 600°C, the method comprising: providing a closed mould comprising two mould surfaces defining a mould cavity therebetween; introducing basalt fibres into the mould cavity; closing the mould by bringing the two mould surfaces towards each other such that the mould cavity defines a desired shape of the structural shell; contacting the basalt fibres with a mixture comprising a resin and a hardening agent; curing the resin to form a structural shell; and recovering the structural shell from the mould.

[0098] The advantages and preferable features of the earlier aspects apply equally to this aspect.

[0099] The resin fills the mould, impregnating the reinforcement materials, and then cures to form the final composite part. Resin transfer moulding (RTM) offers advantages such as precise control over resin flow, excellent surface finish, and the ability to produce complex shapes. Depending on the shape it can be compressed by two metal shells or more complex shapes (e.g. helmets), for example by using a balloon. In comparison to conventional methods of manufacturing structural shells, in particular structural shells for motorcycle helmets, the method is particularly efficient.

[0100] The structural shell is preferably in the shape of a helmet, more preferably a motorcycle helmet. The method of the present invention is particularly suitable for manufacturing a structural shell for a motorcycle helmet.

[0101] Preferably, the two mould surfaces comprise an inner mould surface and an outer mould surface, the inner mould surface comprises a balloon, and bringing the two mould surfaces towards each other comprises inflating the balloon. In other words, the balloon functions as a male mould. The balloon is preferably inflated to a pressure of from +2 to +8 bar, more preferably from +3 to +7 bar, even more preferably from +4 to +6 bar, still even more preferably from +4.5 to +5.5 bar, still even more preferably about +5 bar. Curing the resin preferably comprises heating the resin to a temperature of from 50 to 100 °C, preferably from 60 to 90 °C. The heating may comprise heating the mould. The mould may be pre-heated before contacting the basalt fibres with the mixture comprising a resin and a hardening agent. The pre-heating may take place before the resin fibres are introduced into the mould cavity.

[0102] Contacting the basalt fibres with a mixture comprising a resin and a hardening agent is preferably carried out at a pressure of from 1 to 10 bar, more preferably from 2 to 8 bar.

[0103] Preferably, the method further comprises machining the structural shell. This may be carried out to achieve a final desired shape, texture and / or surface finish.

[0104] The term “fibre-reinforced material” as used herein may encompass a composite material reinforced with fibres. The basalt fibre-reinforced material comprises a polymer material. Typically, therefore, the composite material comprises a polymer matrix reinforced with basalt fibres.

[0105] The polymer material is capable of at least partially thermally cracking at a temperature of from 200 to 600°C. The term “thermally cracking” as used herein may encompass pyrolysis of the polymer material by depolymerisation and / or removal of crosslinks in the polymer material, for example. Without wishing to be bound by theory, it is understood that the polymers in the polymer material at least partially depolymerise due to the homolytic fission of carbon-carbon bonds in the polymer backbone of the polymers during the thermal cracking. In other words, in some embodiments, for example, the polymer material is capable of at least partially depolymerising and / or un-crosslinking at a temperature of from 200 to 600°C.

[0106] Preferably, the polymer material is a thermoplastic material. The thermoplastic material may be a thermoplastic, or a material which exhibits the properties of a thermoplastic. The term “thermoplastic” as used herein may encompass a material which becomes softer when heated and harder when cooled, as defined in the art.

[0107] Preferably, the polymer material of the present invention comprises a polymethacrylate, more preferably a poly(methyl methacrylate). A commercially available polymethacrylate that is particularly suitable for use in the present invention is Elium® from Arkema. The polymer material may comprise other (thermoplastic) polymers, such as, for example, other polyacrylates, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamides, polyesters, and polyurethanes, polyetherether ketones, liquid crystalline polymers, polysulfones, and polyphenylene sulfide, provided that the polymer material is capable of at least partially thermally cracking at a temperature of from 200 to 600°C.

[0108] The use of basalt fibres to reinforce a material comprising a polymer material, wherein the polymer material is capable of at least partially thermally cracking at a temperature of from 200 to 600°C, enables a structural shell to be manufactured with high flexural strength per unit area for use in a hull for a marine vessel and the like, wherein the basalt fibres are recoverable at end of life, without substantial, or preferably any, deterioration in physical and / or mechanical properties of the basalt fibres. The polymer material and / or resin used to manufacture the polymer material is also recoverable on heating. Without wishing to be bound by theory, it is thought that this is because the basalt fibres have a melting temperature of about 1500°C or greater. Accordingly, the resulting at least partially thermally cracked polymer material and / or the basalt fibres may be independently recovered from the heated structural shell. Without wishing to be bound by theory, it is also thought that this is because the basalt fibres absorb substantially no resin, preferably no resin. Thus, the basalt fibre-reinforced material can be heated to at least partially thermally crack the polymer material, thereby forming a liquid from which the basalt fibres can be recovered. It is further thought that the bond formed between the polymer material and the basalt fibres is broken when the polymer material is at least partially thermally cracked, thereby enabling the basalt fibres to be separated from the at least partially thermally cracked polymer material with substantially no polymer material residue remaining on the basalt fibres. Thus, the recovered basalt fibres may be recovered without substantial, or preferably any, deterioration in physical and / or mechanical properties. This may enable the basalt fibres to be fully recycled for use in a further structural shell or the like, for example. Preferably, the at least partially thermally cracked polymer material is a liquid at 20°C, i.e. room temperature. This property may enable the basalt fibres and the at least partially thermally cracked polymer material to be more easily separated. For example, this property may enable the basalt fibres and the at least partially thermally cracked polymer material to be more easily separated once the heating process is complete, and the at least partially thermally cracked polymer material is allowed to cool. This is particularly easily achieved when the polymer material comprises a polymethacrylate, even more particularly when the polymer material comprises Elium® from Arkema.

[0109] As a result, a structural shell can be manufactured wherein at the end of life, the resin and basalt fibre starting materials can each be recovered in a state that is capable of being used again in, for example, another structural shell or the like. In other words, it is surprising that the structural shell of the present invention may be sufficiently strong for commercial use, while also being recyclable. One would not expect that it would be possible to manufacture a composite material in which the fibres do not substantially absorb the resin so that they can be recycled, and wherein the composite material has sufficient, and preferably desirable, flexural strength for use in a structural shell for a boat hull for a marine vessel and the like. It will be appreciated, however, that the structural shell described herein may also have any suitable use outside of the marine sector. For example, the structural shell described herein may be used in any of the following, non-limiting list of applications: wind, manual, electric and combustion propelled vessels (e.g. dinghy, kayak, powerboat, sailing yacht, powerboat etc.); skis; ski poles; construction poles (e.g. scaffolding); spinnaker poles and / or bowsprits (e.g. for sailing vessels); trains, tramway and metro components (e.g. nose, side panels etc.); wind turbine blades; furniture (e.g. chairs, tables, closets); automotive structures and body parts; radar / antenna covers; house building materials (e.g. walls, roofs, floors etc.); flagpoles; window frames; doors; suitcases; or flight simulators.

[0110] Preferably, the basalt fibres are fully encapsulated by the polymer material. However, typically, it is possible to see fibre print through on the surface of the basalt-fibre reinforced material. Such a structural shell may have high flexural strength per unit area and be suitable for use in the hull and / or deck of a marine vessel, a blade of a wind turbine, a ski, a ski pole, a fuselage of an aircraft, a body of a land vehicle and the like.

[0111] Preferably, the basalt fibre-reinforced material comprises substantially no voids. In particular, preferably, the basalt fibre-reinforced material comprises less than 1 vol.% voids, more preferably less than 0.5 vol.% voids, most preferably substantially no voids. Such a material may exhibit high flexural strength and be less likely to delaminate on flexing or bending.

[0112] The ratio by weight of basalt fibres to polymer material in the structural shell is preferably from 80:20 to 40:60, more preferably from 75:25 to 50:50, even more preferably from 70:30 to 55:45. Such ratios provides the optimal balance between cost, weight and strength per unit area of the structural shell due to the reduction in the amount of resin needed.

[0113] Preferably, the basalt fibres are dispersed in the polymer material in a regular arrangement, preferably wherein the fibre-reinforced material comprises a plurality of layers of substantially parallel basalt fibres, wherein the average direction of the substantially parallel basalt fibres is different in adjacent layers. More preferably, the average direction of the substantially parallel basalt fibres in each layer is about 45° or about 90° relative to the average direction of the substantially parallel basalt fibres in adjacent layers. Most preferably, the layers of substantially parallel basalt fibres are arranged quadri-axially, preferably with relative directions of the basalt fibers of -45°, 90°, 0-90° and 0°, tri-axially, preferably with relative directions of the basalt fibres of -45°, 90° and 45°, bi- axially, preferably with relative directions of the basalt fibres of 0° and 90°, or uni- directionally. Such an arrangement of the basalt fibres within the polymer material may provide a quasi-isotropic composite material which exhibits substantially equal mechanical properties in all planar directions. Such an arrangement of the basalt fibres within the polymer material may also provide a structural shell with desirably high flexural strength per unit area and resistance to wear. In particular, during the manufacture of the basalt fibre-reinforced material of the present invention, the Inventor has made a selection of several weaves of basalt fibres, based on weight ratio and fibre direction. Three types of fibre directions were made: (i) UNI (uni-directional or one direction strings of fibre), (ii) Bl (bi-axial or two directions strings of fibre at 90°) and (iii) TRI (tri-axial or three directions of fibres (45-90°). In some embodiments, these weaves of basalt fibres may be layered on top of one another to form a layered structure which may exhibit quasi-isotropic properties, i.e. substantially equal mechanical properties in all planar directions. The loading of each weave relative to each other can also be varied, depending on the required properties and / or the purpose of the resulting composite material. However, it will be appreciated that the invention is not limited to a particular type of basalt-fibre weave and any conventional weave used in the art may be used in the basalt-fibre reinforced material described herein. Typical basalt fibre loadings in the weaves may be from 100 to 1200 g / m2, preferably from 200 to 700 g / m2for use in boat hulls and the like.

[0114] In some embodiments, the structural shell further comprises a core, preferably a polymer core. The polymer core typically comprises a polyester, the polyester preferably comprises polyethylene terephthalate) (PET) and the PET preferably comprises a PET foam. The term “PET foam” as used herein may encompass a material comprising PET, wherein the PET comprises a plurality of gas-filled voids. However, in the structural shell described herein, the voids may be substantially filled with the polymer material, preferably entirely filled with the polymer material. The polymer core may form a layer within the structural shell. Typically, such a layer may be in the centre of the structural shell. For example, the polymer core may form a layer which is sandwiched between two or more layers of the basalt fibre-reinforced material, or may form a layer which is fully surrounded by the basalt fibre-reinforced material. Advantageously, when the structural shell further comprises a polymer core, the thickness of the structural shell may be increased without increasing the weight per unit area of the structural shell as much as when the structural shell does not comprise a polymer core. It will be appreciated that the tensile strength per unit area may be decreased by including the polymer core. However, such a structural shell may be particularly desirable when used for a deck for a marine vessel, for example, where such a loss is tensile strength may be compensated for by an increase in flexural strength. In some embodiments, other materials may be used for the polymer core instead of a PET core, for example PVC or a balsa. However, a PVC core is less desirable in the present invention, as it cannot be recycled. The polymer core may be of any thickness, depending on the particular application on the structural shell. However, typically, the polymer core may have a thickness of from 1 mm to 300 mm, preferably from 1 mm to 100 mm, more preferably from 5 to 50 mm, even more preferably from 10 to 30 mm.

[0115] As an alternative to a PET core, the polymer core may comprise the same polymer material as the basalt-fiber reinforced material. In other words, the core may be formed of the polymer material without basalt fibers. Such a core may be recovered at the same time as the polymer material of the basalt fiber reinforced material.

[0116] As an alternative to a polymer core, the structural shell may comprise a core comprising, for example, aluminium (melting point: approximately 650 °C), Rockwool or balsawood.

[0117] Preferably, the polymer material is capable of at least partially melting at a temperature of from 150 to 300°C, preferably from 200 to 250°C and / or is capable of at least partially melting at a lower temperature than it is capable of at least partially thermally cracking. This is particularly desirable when the structural shell comprises a polymer core. Moreover, the polymer material is preferably capable of at least partially thermally cracking at a temperature of from 300 to 500°C, more preferably from 350 to 400°C. In addition to the above-described advantages, this is also particularly desirable when the structural shell comprises a polymer core. With the above-outlined properties, for example, when disassembling the structural shell, it may be possible to more easily recover the polymer core. This is particularly easier when the melting temperature of the polymer core is from 200 to 300°C, for example. This is because, on heating, the polymer material may melt at a lower temperature than the polymer core, and so the polymer core may be separated and recovered from the heated structural shell more easily. In particular, the solid polymer core may be more easily removed from the liquid polymer material. This may also reduce the likelihood of cross-contamination of the polymer core and the at least partially thermally cracked polymer material when heated to a higher temperature, so that the at least partially thermally cracked polymer material can be recycled. This may be because the polymer core can be removed from the heated structural shell before the structural shell is heated such that the polymer material at least partially thermally cracks (thereby avoiding the melting of the polymer core and mixing of the melted polymer core into the melted and / or at least partially thermally cracked polymer material). In this case, the polymer core, the at least partially thermally cracked polymer material and basalt fibres can each be recovered separately.

[0118] The polymer material is described as being capable of at least partially melting and / or at least partially thermally cracking at the recited temperatures. Typically, the polymer material is capable of substantially melting or thermally cracking at the recited temperatures, more typically completely melting or thermally cracking at the recited temperatures.

[0119] In some embodiments, the structural shell may further comprise a gelcoat, typically on an outer surface. Typically, the gelcoat comprises unsaturated polyester resins and / or vinyl esters. Preferably, the gelcoat comprises a pigment. The use of a gelcoat may advantageously provide a high-quality finish on the visible surface of the basalt fibre-reinforced material. Typically, the gelcoat provides a coloured, glossy surface which improves the aesthetic appearance of the structural shell, such as the surface of a boat hull, for example. The use of a gelcoat may also substantially reduce the number of labour hours to produce a final structural shell for use in, for example, a hull for a marine vessel. This is because the use of a gelcoat may eliminate the need to paint and / or polish the basalt fibre-reinforced material. The gelcoat typically has a thickness of from 1 to 3 mm.

[0120] Preferably, the structural shell exhibits a flexural strength of from 600 to 800 MPa before ageing. This is typically measured using a three point bending set-up. Ageing of the structural shell may include sea-water ageing, for example.

[0121] In a preferred embodiment, the structural shell comprises a basalt fibre-reinforced material, wherein the basalt fibre-reinforced material consists of basalt fibres, a polymer material, and optionally a hardening agent, the polymer material being capable of at least partially thermally cracking at a temperature of from 200 to 600°C, and wherein the polymer material comprises a polymethacrylate.

[0122] The invention will now be described in relation to the following non-limiting example.

[0123] Example 1

[0124] A structural shell was prepared using the following method:

[0125] 1 . Mix gelcoat with 25% ATH (pending on result after mixing. When doughy, just fireguard gel coat without ATH)

[0126] 2. Apply 3 layers of gelcoat on an infusion table

[0127] 3. Add first layer of BIAX 600 on the gelcoat

[0128] 4. Spray light layer of aerosol adhesive

[0129] 5. Spread ATH (12% of total ATH weight) over the Bl AX layer

[0130] 6. Add second layer of BIAX 600

[0131] 7. Spray light layer of aerosol adhesive

[0132] 8. Spread ATH (12% of total ATH weight) over the Bl AX layer

[0133] 9. Add third layer of BIAX 600

[0134] 10. Spray light layer of aerosol adhesive

[0135] 11 .Spread ATH (12% of total ATH weight) over the BIAX layer

[0136] 12. Add fourth layer BIAX 600 13. Spray light layer of aerosol adhesive

[0137] 14. Spread ATH (12% of total ATH weight) over the BIAX layer

[0138] 15. Add fifth layer Bl AX 600

[0139] Before, during and after the infusion the panel surface was warmed up to about 50 degrees Centigrade to help the resin to cure with the Perkadox. ATH will absorb the increasing temperature and won't let the resin cure in a room temperature environment.

[0140] Test results for fire retardance meet the standards for a tram or city train.

[0141] Increasing the ATH to 24% per layer may meet the standards for a high speed train or a train travelling through tunnels.

[0142] The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

Claims

Claims:1 . A ballistic-resistant article comprising: a first layer comprising a first polymer material reinforced with basalt fibres; and a second layer laminated on the first layer, the second layer comprising a second polymer material reinforced with one or more of resin particles, carbon fibres, graphene particles, graphene-based particles and ceramic particles.

2. The ballistic-resistant article of claim 1 , wherein the second polymer material is reinforced with resin particles.

3. The ballistic-resistant article of claim 2, wherein the resin particles comprise: polyethylene, preferably ultra high molecular weight polyethylene (UHMWPE); and / or aromatic polyamide (aramid), preferably para-aromatic polyamide, more preferably poly(azanediyl-1 ,4-phenyleneazanediylterephthaloyl).

4. The ballistic-resistant article of any preceding claim, wherein the resin particles are in the form of fibres.

5. The ballistic-resistant article of any preceding claim, wherein the ceramic particles comprise one or more of alumina, a carbide, a nitride and a cermet, preferably one or more of aluminium oxide (AI2O3), boron carbide (B4C), silicon carbide (SiC), tungsten carbide (WC), zirconium carbide (ZrC), titanium carbide (TiC), cobalt chromium carbide (CoCrCr3C2), aluminium nitride (AIN), preferably wherein the ceramic particles comprise glass fibres.

6. The ballistic-resistant article of any preceding claim, wherein the first polymer material and / or the second polymer material comprises a thermoplastic polymer.

7. The ballistic-resistant article of any preceding claim, wherein the first polymer material and / or the second polymer material comprises one or more of polyether ether ketone (PEEK), poly amide imide (PAI), methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA) and a styrenic block copolymer (SBC) formed of polystyrene blocks and rubber blocks, more preferably wherein the rubber blocks consist of polybutadiene, polyisoprene, or their hydrogenated equivalents.

8. The ballistic-resistant article of any preceding claim, wherein the second polymer material is reinforced with graphene particles and / or graphene-based particles.

9. The ballistic-resistant article of any preceding claim, wherein the first polymer material is the same as the second polymer material.

10. The ballistic-resistant article of any preceding claim, comprising at least 10 each of the first and second layers, preferably at least 20 each of the first and second layers, the first layers and the second layers being alternately stacked.11 . The ballistic-resistant article of any preceding claim, wherein the ballistic- resistant article satisfies NIJ-STD-0108.01 Level III.

12. The ballistic-resistant article of any preceding claim further comprising outer polymer layers.

13. The ballistic-resistant article of any preceding claim, wherein the first layer and / or the second layer comprises one or more additives selected from: a catalyst, a dye, a pigment, a flame-retardant additive, a hardening agent, a filler, a deoxidiser, an elastomer, UV Stabilizers, and antioxidant, an antimicrobial agent, an impact modifier, a plasticizer, an anti-static agent, and an adhesion promotor.

14. The ballistic-resistant article of any preceding claim, wherein the second polymer material is reinforced with UHMWPE fibres and wherein the ballistic- resistant article further comprises a third layer laminated on the second layer, the third layer comprising a third polymer material reinforced with ceramic particles, preferably boron carbide particles.

15. The ballistic-resistant article of any preceding claim, wherein the second layer is sandwiched between two first layers.

16. The ballistic-resistant article of any preceding claim, wherein the first layer and or the second layer has a thickness of from 0.05 mm to 5 mm, preferably from 0.08 mm to 4 mm, more preferably from 0.1 mm to 3 mm.

17. The ballistic-resistant article of any preceding claim, wherein the thickness of the ballistic-resistant article is from 0.5 mm to 150 mm, preferably from 0.8 to 120 mm, more preferably from 1 mm to 100 mm.

18. The ballistic-resistant article of any preceding claim, wherein in the first layer the ratio of first polymer material to basalt fibres by weight is from 20 % to 60 % based on the total weight of first polymer material and basalt fibres.

19. The ballistic-resistant article of any preceding claim, wherein in the second layer the ratio of second polymer material to one or both of resin particles and ceramic particles by weight is from 20 % to 60 % based on the total weight of second polymer material and resin particles and ceramic particles.

20. Body armour comprising the ballistic-resistant article of any preceding claim.21 . A helmet comprising the ballistic-resistant article of any of claims 1 to 19.

22. A vehicle comprising the ballistic-resistant article of any of claims 1 to 19.

23. An aircraft comprising the ballistic-resistant article of any of claims 1 to 19.

24. A watercraft comprising the ballistic-resistant article of any of claims 1 to 19.

25. A building comprising the ballistic-resistant article of any of claims 1 to 19.

26. A method of manufacturing the ballistic-resistant article of any of claims 1 to 19, the method comprising: providing a mould; forming a layup in the mould, the layup comprising a layer of basalt fibres and a layer of ceramic particles and / or resin particles; contacting the layup with a mixture comprising a resin and a hardening agent at a relative pressure of -0.65 bar to provide a ballistic-resistant article; and recovering the ballistic-resistant article from the mould.

27. The method of claim 26, wherein the method comprises pultrusion and / or resin transfer moulding (RTM).

28. The method of claim 26 or claim 27, further comprising machining the ballistic-resistant article.

29. A method of manufacturing a structural shell, the method comprising: providing in a mould; introducing into the mould a stack comprising a first layer of reinforcing fibres and a second layer of fire retardant filler; contacting the first and second layers with a mixture comprising a resin and a hardening agent at a relative pressure of -0.65 bar to provide a structural shell; and recovering the structural shell from the mould.

30. The method of claim 29, wherein the first and second layers are in contacted via an adhesive.31 . The method of claim 29 or claim 30, wherein the reinforcing fibres comprise basalt fibres.

32. The method of any of claims 29 to 31 , wherein the fire retardant filler comprises one or more of aluminium hydroxide (AI(OH)3), magnesium hydroxide (Mg(OH)2), huntite (Mg3Ca(CO3)4), hydromagnesite (Mg5(CO3)4(OH)2-4H2O), red phosphorus, zinc borate, aluminium phosophate (AIPC ), melamine cyanurate, antimony trioxide (SbC ), hindered amine light stabilizers (HALS), graphene and a graphene-based material.

33. The method of any of claims 29 to 32, wherein the resin comprises methacrylate monomers, preferably methyl methacrylate monomers, more preferably from 50 to 85 wt.% methyl methacrylate monomers and / or from 10 to 50 wt.% acrylic polymers.

34. The method of any of claims 29 to 33, wherein the hardening agent comprises an organic peroxide, preferably benzoyl peroxide.

35. The method of any of claims 29 to 34, wherein the mixture comprises the hardening agent in an amount of from 0.5 to 30 phr, preferably from 1 to 15 phr, more preferably from 1 .5 to 4 phr, even more preferably from 2.5 to 4 phr.

36. The method of any of claims 29 to 35, wherein the first and second layers are contacted with the mixture at a relative pressure of from -0.7 to -1 .15 bar, preferably from -0.9 to -1 .1 bar, more preferably from -0.95 to -1 .05 bar.

37. The method of any of claims 29 to 36, wherein the first and second layers are contacted with the mixture at a temperature of from 30 to 70 °C, preferably from 40 to 60 °C, more preferably from 45 to 55 °C.

38. The method of any of claims 29 to 37, wherein the first and second layers are contacted with the mixture at a humidity of from 30 to 70%, preferably from 40 to 50%.

39. The method of any of claims 29 to 38, wherein the first and second layers are contacted with the mixture under the applied pressure for from 5 minutes to 12 hours, preferably for from 1 hour to 6 hours, more preferably for from 90 minutes to 3 hours.

40. The method of any of claims 29 to 39, wherein the method further comprises forming a gelcoat in the mould prior to introducing into the stack into the mould.41 . The method of claim 40, wherein the gelcoat comprises a fire retardant filler.

42. The method of any of claims 29 to 41 , wherein the stack comprises at least two of the first layers and at least two of the second layers, the first and second layers being alternately stacked, preferably wherein the stack comprises at least three of the first layers and at least three of the second layers.

43. The method of any of claims 29 to 42, wherein the stack comprises five of the first layers each separated by a second layer.

44. The method of any of claims 29 to 43, wherein, in the composite material, the second layer comprises, based on the total weight of the second layer, from 5 to 50 wt.% of the fire retardant filler, preferably: from 8 to 16 wt.% of the fire retardant filler, more preferably from 10 to 14 wt.% the fire retardant filler; or from 20 to 28 wt.% of the fire retardant filler, more preferably from 22 to 26 wt.% the fire retardant filler.

45. A structural shell obtainable by the method of any of claims 29 to 44.

46. A structural shell comprising a stack of a first layer of reinforcing fibres and a second layer of fire retardant filler, the first and second layers being infused with a polymer material comprising a methyl methacrylate.

47. The structural shell of claim 46, wherein the polymer material comprises a poly(methyl methacrylate).

48. The structural shell of any of claims 45 to 47, wherein the composite material meets the requirements of EC45545.

49. A train, tram, hull, deck, structural grid, watercraft, aircraft, vehicle, building, ski, ski pole, wind turbine blade, ballistic resistant panel or helmet comprising the structural shell of any of claims 45 to 48.

50. A method of manufacturing a structural shell using resin transfer moulding, the structural shell comprising a basalt fibre-reinforced material, wherein the basalt fibre-reinforced material comprises a polymer material, the polymer material being capable of at least partially thermally cracking at a temperature of from 200 to 600°C, the method comprising: providing a closed mould comprising two mould surfaces defining a mould cavity therebetween; introducing basalt fibres into the mould cavity; closing the mould by bringing the two mould surfaces towards each other such that the mould cavity defines a desired shape of the structural shell; contacting the basalt fibres with a mixture comprising a resin and a hardening agent; curing the resin to form a structural shell; and recovering the structural shell from the mould.51 . The method of claim 50, wherein the structural shell is in the shape of a helmet.

52. The method of claim 51 , wherein the helmet is a motorcycle helmet53. The method of claim 51 or claim 52, wherein: the two mould surfaces comprise an inner mould surface and an outer mould surface, the inner mould surface comprises a balloon, and bringing the two mould surfaces towards each other comprises inflating the balloon.

54. The method of any of claims 50 to 53, wherein curing the resin comprises heating the resin to a temperature of from 50 to 100 °C, preferably from 60 to 90 °C.

55. The method of any of claims 50 to 54, wherein contacting the basalt fibres with a mixture comprising a resin and a hardening agent is carried out at a pressure of from 1 to 10 bar, preferably from 2 to 8 bar.

56. The method of any of claims 50 to 55, further comprising machining the structural shell.