NL2033574B1

NL2033574B1 - Sustainable Composite Materials

Info

Publication number: NL2033574B1
Application number: NL2033574A
Authority: NL
Inventors: Dwarshuis Pieterjan; Erik Janssen Sven
Original assignee: Holland Composites B V
Priority date: 2022-11-20
Filing date: 2022-11-20
Publication date: 2024-05-30

Abstract

The present invention relates to lightweight, fire—resistant plate—like composite material for use in construction products, building elements or furniture applications, comprising: a first layer comprising a crosslinked polyfuranyl resin and mineral fibre fabric; at least one core 5 layer with a cellular structure; and a second layer comprising a crosslinked polyfuranyl resin and mineral fibre fabric; and to a method for preparing the composite material.

Description

P307582NL 1

Sustainable Composite Materials

The present invention relates to a lightweight composite material suitable for use in the manufacture of fire-resistant Insulation panels, comprising a lightweight core layer sandwiched between two composite fibre-reinforced resin layers. The composite material may comprise one or more additional inner or outer layers, on one or both sides, and optional functional layers.

Background of the Invention

Composite materials, in particular shaped articles such as panels are used in various applications, for instance as elements of furniture (e.g. table tops, benches, seating) or interior finishing material in buildings. Such composite materials usually comprise a binder material and a solid filler material, material that offers structural integrity and/or insulation value, as well as external layers facing the environment.

Specifically for furniture and interior finishing materials, the composites have to be durably resistant to the different wearing conditions, including physical abrasion, variations in humidity and temperature, exposure to UV and other radiation, exposure to chemicals and (micro)biological growth.

Composite materials for use in furniture and as interior finishing materials have traditionally been based on medium-density or high-density wooden boards. However, these materials difficult to shape, tend to warp in damp conditions and are combustible. Furthermore, the materials have a high density, which in turn limits their use to applications and constructions that can bear the high weight.

In order to reduce weight and/or to improve mechanical performance, composites based on plywood sheet materials and/or wood chips have been developed. Plywood usually consists of sheets of wood that are glued or cemented together, using for instance thermosetting polyurethane or thermosetting unsaturated polyester and styrene binders, or epoxy resin and amino curing agent binders. Oriented Strand Boards (OSBs) are a type of engineered wood alternative formed by adding adhesives to wood strands (flakes) and then compressing layers of wood strands (flakes) in specific orientations. Oriented strand board is typically manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips compressed and bonded together with wax and synthetic resin adhesives (approximately 95% wood; 5% adhesive, wax and resin). The adhesive resins types used include: urea-formaldehyde (OSB type 1, non-structural, non-waterproof); isocyanate-based glue (or PMD! poly-methylene diphenyl diisocyanate based) in inner regions with melamine-urea-formaldehyde or phenol formaldehyde resin glues at surface (OSB type 2, structural, water resistant on face); phenol formaldehyde resin throughout (OSB

P307582NL 2 types 3 and 4, structural, for use in damp and outside environments).OSB is a material with mechanical properties that make it particularly suitable for load-bearing applications in construction, but whose density and external appearance typically preclude its use in furniture and as an interior finishing material.

However, these composites are still relatively flammable, which limits their use as interior finishing materials and use in furniture, especially in the commercial sector where compliance with fire regulations is a legal requirement. For interior finishing materials, the concept of “flame spread” is used, which specifies the rate at which a flame will spread along the surface of a material. The best-known flame-spread test is the "tunnel test" which has been adopted as ASTM test Standard E-84.

The lowest flame-spread rate (0 to 25) is permitted for areas where fire hazard is most severe, as in vertical exit-ways of buildings without sprinkler systems that are used for public assembly. Materials which rate 26 to 75 are permitted in areas of intermediate fire hazard severity, such as corridors providing exit-ways in commercial and industrial structures. Materials rated at from 76 to 200 are permitted in rooms of most dwelling places, except hospital rooms and the like.

Typical flame-spread ratings for untreated plywood grades range from 75 to 200. Typical flame-spread ratings for untreated Oriented Strand Boards (OSBs) range from 75 to 175. To improve the flame-spread ratings, these composite materials are often treated with fire-retardant chemicals. Plywood can be pressure-impregnated with fire-retardant salts to inhibit combustion.

Plywood may be impregnated with fire-retardant chemicals in accordance with American Wood

Protection Association Standard U1 to have a flame spread of 25 or less when subjected to a 30- minute test. Fire-retardant treatment involves proprietary chemical formulations that generally reduce the structural properties of plywood.

To provide “lighter” (less dense) composite materials, sandwich-structured composites have been developed. A sandwich-structured composite is a special class of composite materials that is fabricated by attaching two thin, stiff skin layers onto a thicker, lightweight core. The core material is normally low strength material, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density.

Suitable core materials include natural materials such as cork and balsa wood, corrugated cardboard and paper honeycomb, as well as man-made open- and closed-cell-structured foams like polyether sulfone polyvinylchloride, polyurethane, polyethylene or polystyrene foams.

Occasions, the honeycomb structure may be filled with other foams to provide additional strength.

P307582NL 3

Laminates of glass or carbon fibre-reinforced thermoplastics or mainly thermoset polymers (unsaturated polyesters, epoxies...} are widely used as skin materials. The core is typically bonded to the skins with an adhesive.

W02016/016621 discloses layered composite structures comprising a cellular core faced with skin layers, each skin layer comprising a fibre layer and an outermost veneer layer. The application discloses a panel comprising two bio-resin impregnated natural fibre mats on wither side of a paper honeycomb core, with a veneer outer layer. Similarly, WO2016/063011 discloses laminated composite material. The composite material comprises a first skin layer comprising a network of inorganic fibres and a core layer comprising a network of natural fibres at least partially impregnated with a resin-based binder component. The application discloses forming a composite panel suitable for an airline galley cart by combining a core of hemp fibres, aramid (thickness 5 mm, cell diameter about 3 mm) and acid catalysed PFA resin with skin layers of woven basalt fibres, and then pressing and heating at 180 °C for 150 seconds.

WQ2016/067048 concerns a process for manufacturing laminated composites. The laminated composites comprise a honeycomb between skins of natural fibre mats. The process entails contacting a paper honeycomb core with natural fibre mats pre-impregnated with a bio- resin, followed by a single heating and moulding step.

GB2485525A finally concerns composite panels prepared from furan resin-impregnated fibre mats and methods for their manufacture. This application discloses placing a paper honeycomb core between two impregnated natural resin mats, wherein two different resins are employed to impregnate the materials. This is again a cumbersome process, requiring two separate resin applications, and a carefully concerted curing process.

Accordingly, there remains a need to provide lightweight materials that offer high strength and low flammability, ideally based essentially or entirely on sustainable resources, and a single resin formulation.

Brief Summary of the Disclosure

Accordingly, in a first aspect, the present invention relates to a lightweight, fire-resistant plate-like composite material for use in construction products, building elements or furniture applications, comprising: a first layer comprising a crosslinked polyfuranyl resin and a mineral fibre fabric; at least one core layer with a cellular structure; and a second layer comprising a crosslinked polyfuranyl resin and a mineral fibre fabric.

In a second aspect, the present invention relates to an article of sustainable and recyclable fire-resistant furniture, a building exterior or interior panel, or an exterior or interior finishing material comprising the composite material according to the invention.

P307582NL 4

In a further aspect, the present invention relates to a method for the manufacture of a composite panel according to the invention, comprising: a. impregnating a sheet comprising woven of mineral fibres with a liquid polyfuranyl resin composition, to provide an impregnated sheet, b. subjecting the impregnated sheet to conditions inducing gelation of the polyfuranyl resin composition, thereby forming a prepreg sheet; c. optionally depositing a prepreg sheet onto a transport medium, preferably a backing sheet and optionally removing the prepreg sheet on the backing sheet; d. arranging at least a core layer between two prepreg sheets, such that the first and second prepreg sheets such that the top surface of the second sheet opposes the bottom surface of the first sheet; to form a sandwich structure; and e. subjecting the sandwich structure to conditions that allow the gelled polyfuranyl resin composition to cure essentially fully, preferably including heating the sandwich structure to a temperature and for a time period that results in crosslinking and chain growth of the polyfuranyl resin composition.

In a further aspect, the present invention relates to the intermediate prepreg sheets; optionally deposited onto a transport medium, such as a backing sheet.

In a further aspect, the present invention relates to a method for the manufacture of a prepreg sheet for use in formation of composite panel, the mothed comprising the steps of a. impregnating a sheet comprising woven of mineral fibres with a liquid polyfuranyl resin composition; to provide an impregnated sheet; b. subjecting the impregnated sheet to conditions inducing gelation of the polyfuranyl resin composition, thereby forming a prepreg sheet; and c. optionally depositing a prepreg sheet onto a transport medium, preferably a backing sheet and optionally removing the prepreg sheet on the backing sheet; and d. optionally, rolling up the prepreg sheet on the transport medium, to form a reel of a rolled up prepreg sheet.

In yet a further aspect, the present invention relates to the prepreg sheet, or prepreg sheet reel obtainable from the method.

Brief Description of the Drawings

Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a preferred embodiment of the plate-like composite material according to one embodiment of the invention, showing a peel-away section of the core honeycomb, a corner enforcement element, a glass fibre thermoset composite layer, and a top layer attached to the composite.

FIG. 2 is a top view of a preferred embodiment of the invention, showing the internal core layer comprising a honeycomb card-board core and a side element.

P307582NL

FIG. 3 is a cross-sectional view of a preferred embodiment of the invention, showing the composition of a preferred embodiment of a material according to the invention.

Detailed Description of the Invention

Throughout the description and claims of this specification, the words “comprise” and 5 “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

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

The composite material according to the invention was found to be inherently resistant to attack by microbes and insects and thus does not require expensive chemical treatments. Also, the material is resistant to degradation from exposure to ultraviolet light as well as damp and/or freezing conditions.

The materials according to the invention are advantageously prepared using an impregnation and gelation process, also known as a “prepreg process”, wherein resin-impregnated and gelled fiberglass sheets are used in the formation of prepreg sheets, which are then employed to form the composite.

In this process, a fabric material, in particular fiberglass fabric, is impregnated with a thermosetting polyfuranyl resin composition, which is then partially cured to induce gelation. The impregnated fabric may then be sheared to form so called prepreg sheets.

In order to enhance the adhesion of the resin to the fiberglass, often a coupling or sizing agent, such as a silane, is coated onto the surface of the fiberglass fabric, or individual fibres prior to impregnation. One of the particularly desirable characteristics of the present resin-impregnated fiberglass sheets is that the resin-impregnation covers the fibres and can be partially cured to a

P307582NL 6 non-tacky state wherein the sheets can be handled for the lamination process, and roll storage.

This is often referred to as a B-stage, a cure state which allows the sheets to be sufficiently self-supporting to be laid up as a laminate, but not advanced enough in the state of cure that they are rigid or non-flowable when heated, and they can be further cured to a final cure with heat and pressure to form a laminate structure as is well known in the art.

Prepreg materials or sheets, may be directly employed, or removably placed on a polymeric backing sheet, which allows preparing larger coils of prepreg material, whereby each winding is divided by the backing sheet. The thus obtained gelled material may hence be employed directly in line, but usually are coiled, preferably supported by a backing sheet to avoid tacking of the individual layers. As prepreg sheets retain part of their reactivity, sheets and/or coils are usually stored under controlled and suitable conditions.

For use, the prepreg sheets are then laid up with core materials, and laminated by subjecting them to heat and pressure, to fully cure the laid-up laminate with the core material, thereby forming a hardened surface layer and a bond with the core materials.

As indicated above, the lamination process normally includes the lamination of one or more core layers to provide necessary functionality.

Advantageously, sides and edges may be formed, thereby fully encapsulating the core layer, and giving it various shapes useful for the later use.

Accordingly, the resin-impregnated sheet is formed by providing a coil of the fabric, e.g. fibreglass material, which is unwound from the coil and continuously passed through a tank containing an aqueous solution or dispersion of the polyfuranyl resin, and then the coated or impregnated material is passed through a treater tower wherein heat is applied to drive off part of the water, and to the resin material is partially cured by initiating crosslinking. The fabric may be treated in two or more passes.

The thus obtained gelled material may directly be employed, or it may be coiled, preferably supported by a backing sheet to avoid tacking of the individual layers.

Thereafter, the partially-cured material is uncoiled and may either be applied in line, or cut into sheets of the desired length. Such sheets are also known as prepreg sheets, which may then be employed in the lamination process described above.

In forming laminate structures which include resin impregnated glass fibres and core layers, it was found that the polyfuranyl resins showed a surprisingly high adhesion to the core materials, and good penetration, in particular porous materials, thereby obviating the need for tack or adhesive layers, even when applied a thin layers thicknesses. Also, defects that can occur because of poor adhesion to glass fibre were minimized, while at the same time being extremely low in volatile organic compounds.

P307582NL 7

According to the present invention, a method and resultant article are provided which showed an optimal adhesion of the fibrous fabric impregnated with a resin to the interior layer materials, in particular optimal adhesion of the impregnated resin layer to the core layers laminated thereto, even at a low layer thickness.

The inorganic fibres of the first and second skin layer may advantageously be both mineral fibres. Suitable fibres include glass fibres such as e-glass fibres, carbon fibre or fibres based on naturally-sourced minerals.

Suitable naturally-sourced mineral fibres are basalt fibres, for example. Basalt, or other rock-based fibres are of interest in view of their low environmental impact. Basalt fibres are typically formed by crushing quarried or mined basalt, washing the crushed basalt and heating to a melting temperature of above 1400°C. The molten rock is then extruded through fine nozzles to form filaments of basalt fibre. Such fibres are considered to have superior mechanical properties compared with regular glass fibres, and yet be considerably cheaper and more environmentally friendly to produce than advanced glass and carbon fibres.

Preferably, the inorganic fibres of the first and/or second skin layer satisfy one or more of the following properties of a density in the range of from 2.4 to 2.9 g/cm?, a tensile strength in the range of from 4 to 5 GPa; and/or an elastic modulus of from 90 to 120 GPa.

Preferably, before bonding, the first and/or second outer layer has a smaller thickness than the one or more core layers. Before bonding, the thickness of the first and/or second layer is preferably at least 0.1 mm, and preferably at most 2 mm. The thickness of the one or more core layers depends on the desired use.

By the term “glass fibre fabric” is meant one or more layers of unidirectional rovings that are assembled into a fabric or fabric, i.e. a kind of a textile normally being flexible and bendable. Glass fibres are typically composed of glass filaments bundled into a roving. The diameter and number of filaments in a roving may vary leading to the variations of the diameter of a roving. Normally the filaments are coated with a sizing. The glass fibres may be assembled into a fabric by any suitable method, such as by stitching. Useful glass fibre fabrics include those having of one or more layers of fibres, which preferably are multiaxially reinforced. By the term “unidirectional” is meant that the fibres in one layer of fabric are parallel. By the term “multiaxial reinforcements” or simply “multiaxial” is meant fabric made up of multiple plies or layers of parallel fibres. each lying in a different orientation or axis. In a preferred embodiment of the subject invention the glass fibre fabric comprises multiaxial reinforcements, wherein layers of unidirectional fibres are assembled and stitched together, thereby providing strength and stiffness in multiple directions depending on the controlled orientation of the fibres. Useful multiaxial fabrics include unidirectional, biaxial, and triaxial and quadriaxial fabrics, for example those that are tailored to

P307582NL 8 have the reinforcement in four main directions, i.e. 0 degrees, 90 degrees, +45 and -45 degrees.

However, multiaxial fabrics having other directions between 45 degrees and 90 degrees may be employed.

Useful multiaxial fabrics may further comprise a chopped strand mat layer, or different types of surface mats added on one side of the fabric and then it is referred to as combination products. The multiaxial glass fibre fabrics are normally range in weight from 100 g/m? to 2500 g/m}, such as from 200 g/m? to 1200 g/m?.

Useful glass fibre fabrics normally comprise various glass types, including but not limited to E-glass, S-glass, R-glass, H-glass, D-glass and ECR-glass fibres. Alternatively or in combination, non-woven glass fibre materials or felts may also be employed.

For hand-lay-up, the fabric is typically into the desired shape and embedded into a polymeric matrix comprising a resin component before the final shape of the product is made, whereas for industrial applications, a pre-reg process as set out herein below is prefearbly used.

The glass fibre fabric material may have different glass fibre dimensions and different thickness as well a being coated with various types of sizing. Normally, the diameter of a glass filament is about 3-25 um. Furthermore various sizes of rovings may be used, where the term roving is used in it's conventional meaning, namely a bundle of glass fibre filaments.

Similarly, after curing the resin in the mineral fibre fabric, the outer layers are bonded very well to the core layer surfaces. While the outer layers may be applied in a wet laying process, preferably this is done using a prepreg material comprising a gelled polyfuranyl resin composition.

The curing and bonding of the composite material is then preferably performed by a simultaneous pressing and heating step, whereby the outer layer is compressed slightly. Preferably, therefore, the outer layers act not only as resilient composite skin layer once cured, but also as an adhesive layer, thereby strongly adhering and bonding the outer layer effectively to the core later surface. The present inventors have found that this is a surprisingly convenient way to bond inorganic fibre skin layers with core layers.

In order to further improve fire resistance properties, one or more components of the composite material may be treated with a fire retardant. This can have the effect of reducing flame spread, smoke formation and/or heat output during combustion. The fire-retardant treatment may be applied to the inorganic fibre skin, the natural fibre core and/or the low-density core layer. Suitable fire retardants may be selected from the group consisting of: metal hydroxides, and endothermic additives such as: alumina trihydrate, magnesium hydroxide; borates such as ammonium borate, zinc borate, sodium borate, barium borate; halogenated flame retardants, such as brominated or chlorinated additives;

P307582NL 9 antimony trioxide; phosphorous additives including organic and inorganic phosphates as salts or esters, alkylphosphinates, hypophosphite salts; expandable graphite; molybdenum compounds; and/or melamine cyanurate. it was found that the use polyfuranyl resins comprising polyfurfuryl alcohol (PFA) polymers, in particular under acid catalyst, such as p-toluene sulphonic acid, delivered an inherently high flame retarding effect.

Surprisingly, the composite material according to the invention was found to achieve a flame retardancy rating of B S1 DO according to NEN-EN 13501-2018 SBI.

This renders this material particularly suitable for use in articles of sustainable and recyclable fire-resistant furniture, a building exterior or interior panel, or an exterior or interior finishing material. “Furan” or “polyfuran” resins derived from biomass of vegetable origin are one of the solutions used. Such polyfuranyl resins were initially used in the foundry for ensuring setting of moulding sands in the mould, and are now also used as binders for mineral fibres for making insulation products based on mineral wool, see for example WO 93/25490; WO 94/26676; WO 94/26677; or WO 94/26798.

The composite material comprises a first layer and a third layer comprising a polyfuranyl resin as main binder component. The polyfuranyl resin employed in the present invention may be selected from a variety of different binder materials comprising PolyFurfuryl Alcohol (PFA). The selection will largely depend on the cost and performance targets specified.

The polyfuranyl resin composition may be a biologically derived resin. As such, the biologically derived resin advantageously is not a phenolic resin based on mineral oil as may be found in connection with the manufacturing of conventional fire-rated laminates. The biologically derived resin preferably is a resin that derives some or all of its constituent monomers from biological sources.

Preferably, the biologically derived resin comprises PolyFurfuryl Alcohol (PFA) as the polymeric backbone component. In some embodiments, the biologically derived resin does not comprise fire resistant filler or additive material. Advantageously, such systems can be prepared comprising no Volatile Organic Compounds (VOC) as typically found in phenolic or epoxy resins. As aresult, the biologically derived resin may reduce exposure to potential chemical hazards that may otherwise typically occur during manipulation of phenolic or epoxy resin.

Where reference is made to a “biologically derived resin”, it is to be understood that for embodiments of the invention, the biologically derived resin is a furan resin, such as a resin comprising monomer units of furfuryl alcohol. The cured resin may therefore be a poly(furfuryl alcohol). The furanyl resin may be derived from sugar cane, or other sources of sugars, and as

P307582NL 10 such is not only entirely sustainable, but also imparts particularly advantageous properties to the subject assembly. Preferably, the furan resin comprises furfural (furan-2-carbaldehyde) or a derivative of furfural such as furfural alcohol, furan, tetrahydrofuran and tetrahydrofurfuryl alcohol, which are collectively referred to as “furans” herein.

A furan resin may be used in which furfural replaces formaldehyde in a conventional production of a phenolic resin. The furan resin cross links (cures) in the presence of a strong acid catalyst via condensation reactions. Furfural is an aromatic aldehyde, and is derived from pentose (Cs) sugars, and is obtainable from a variety of agricultural by-products. It is typically synthesized by the acid hydrolysis and steam distillation of agricultural by-products such as corn cobs, rice hulls, oat hulls and sugar cane bagasse. Furan resins are of particular interest because they are derived from natural, renewable sources, they bond well to glass fibres and they have good flame- retardancy properties.

Preferably, humins may be added to the furfuryl alcohol. In this specification, humins from biomass sources are understood as the often black or dark coloured carbon-based macromolecular substances obtained from om saccharide-based biorefinery processes, in particular those from conversion of 5-hydroxymethylfurfural (HMF). These humins can be in the form of either viscous liquids or solids depending on the process conditions used.

These compounds can be considered as polymers containing moieties from hydroxymethylfurfural, furfural, carbohydrate and levulinic acid. These coloured bodies are produced as by-products in the partial degrading of carbohydrates by heat or other processing conditions, as described in e.g.

EP 338151 Al. Humins are believed to be macromolecules containing furfural and hydroxymethylfurfural moieties. Further moieties that may be included in humins are carbohydrate, levulinate and alkoxymethylfurfural groups.

The polyfuranyl resin of the first layer or the third layer, or both layers may also include one or more additional compounds, optionally selected from additional monomers, co-catalysts, diluents, fillers and combinations thereof.

Additional monomers may advantageously be selected from 5-hydroxymethyifurfural (HMF), 2-(2-hydroxyacetyl)furan, 5-alkoxymethylfurfural, formaldehyde, methyl formate, levulinic acid, alkyl levulinates, 2,5-diformyi-furan, carbohydrates and furfural and combinations thereof.

The use of these monomers has the advantage that similar moieties can already be present in the humins so that these additional monomers seamlessly integrate with the polymer of furfuryl alcohol and the humins. The relative amount of these additional monomers may vary within wide ranges. When they are elected from the compounds hereinabove, these compounds have groups that are also present in humins. Therefore they can be added to the humins in very small to extremely large quantities. Generally, economic considerations promote that a small amount of

P307582NL 11 additional monomers is used and a large amount of the by-product humins. Commonly, the amount of additional monomers may vary from 0 to 20 %wt, based on the combined amount of furfuryl alcohol and humins.

Accordingly, useful polyfuranylt resins comprise mixtures of monomers, oligomers and polymers obtained by polycondensation of monomers with a furanyl nucleus and optionally other comonomers such as anhydrides, aldehydes, ketones, urea, phenol etc., in an acid medium. Such polyfuranyl resins usually comprise furfural and/or a derivative of furfural such as furfuryl alcohol.

Furfural is an aromatic aldehyde and is derived from pentose (C5) sugars, and is obtainable from a variety of agricultural by-products. It is typically synthesized by the acid hydrolysis and steam distillation of agricultural by-products such as corn cobs, rice hulls, oat hulls and sugar beets and sugar cane bagasse. Polyfuranyl resins are typically prepared by self-polymerisation of furfuryl alcohol and/or furfural. In a preferred embodiment, the resin may comprise a polyfurfuryl alcohol, a liquid polymer which self-crosslinks in the presence of an acid catalyst. Polyfuranyl resins may be modified by using furfural instead of formaldehyde in a conventional production of a phenolic resin. The furan resin then polymerizes in the presence of a strongly acidic catalyst via various condensation reactions. Polyfuranyl resins are inherently sustainable, since they are derived from natural, renewable sources, and were found to bond well to mineral fibres, and they have good flame-retardancy properties.

As set out above, the polyfuranyl resin composition preferably comprises an acid catalyst.

The catalyst promotes curing via condensation reactions, thereby releasing water vapour. During the curing step, preferably means to release the formed vapour or steam are provided. The curing step typically takes place in a heated moulding press. Known moulding presses are known for moulding polyurethane-containing products. Such moulding presses are typically operated in a carefully sealed condition, in view of the health and safety issues surrounding the curing of polyurethane.

Suitable mineral fibres are in particular glass fibres, notably of glass E, C, R or AR (alkali- resistant), or rock fibres, notably of basalt (or wollastonite). These fibres may be fibres containing more than 96 wt % of silica and ceramic fibres based on at least one oxide, nitride or carbide of metal or of metalloid, or a mixture of these compounds, in particular at least one oxide, nitride or carbide of aluminium, of zirconium, of titanium, of boron or of yttrium. More particularly, the mineral fibres according to the invention are aluminosilicate glass fibres, notably aluminosilicate glass fibres comprising aluminium oxide, Al203, in a fraction by weight of between 14% and 28%.

The composite material further preferably comprises a core layer, preferably a porous matrix layer, for increased thermal or otherwise insulation.

P307582NL 12

However, for the materials of the present invention, in particular where thicker surface layers are provided, it is preferred that a steam ventilation is provided. The steam vent may take the form of an additional process step, in which the mould press is opened (at least partially) during the curing step in order to release steam that has been generated during the heating and curing of the material. In that case, the mould press is typically then closed again to complete the curing of the material. The steam vent may take place at 1 minute or less from the closure of the moulding press, more preferably at 45 seconds or less from the closure of the moulding press.

Additionally or alternatively, the steam vent may take the form of suitable openings provided in the mould press throughout the curing step, the openings being placed so as to provide a suitable exit route for steam generated during the heating and curing of the material.

Steam ventilation can also be achieved by the use of holes (e.g. drilled holes} in the tool face, providing a steam exit route out of the tool. it is possible to consider the cycle time of the manufacture of a composite material according to the present invention. The cycle time is considered to be the time between corresponding steps in the manufacture of a first composite material and a subsequent composite material in the same moulding apparatus. Preferably, the cycle time here is 150 seconds or less. More preferably, the cycle time is 120 seconds or less, e.g. about 100 seconds. For large panels, however, the cycle times may be longer, e.g. up to 240 seconds.

Where an exterior application is considered, waterproof membranous materials for use in accordance with the invention may be included in the line-up. Some more specific examples of suitable waterproof membranous materials include; styrene butadiene modified bitumen, atactic polypropylene modified bitumen, polyalphaolefin modified bitumen, ethylene propylene diene monomer, chlorosulphonated polyethylene, polyvinyl chloride, copolymer alloys, polyisobutylene, butadiene acrylonitrile alloys and nitrile butadiene polymers, chlorinated polyethylene and neoprene or chloroprene. Suitable methods for applying these materials to the metal sheet will vary with the material to be used and will no doubt occur to the skilled person. Alternatively, or additionally, fireproof membranes may also be included.

For insulation, the core material preferably is provided in the form of a board of polymeric foam or mineral wood insulation, or a combination thereof. Furthermore, various foils maybe laminated into the exterior of the panels, e.g. for decorative or protective purpose.

For furniture applications, the core material preferably is a lightweight porous materials such as cork and balsa wood, corrugated cardboard and/or paper honeycomb.

Panels may advantageously also contain side portions, such as wooden or polymeric slats or moldings, which may provide additional structure and functionality. Alternatively, the skin may be provided by the exterior sheet.

P307582NL 13

FIG. 1 is a perspective view of a preferred embodiment of the plate-like composite material according to one embodiment of the invention, showing a peel-away section (11) of the exterior sheet comprising a glass fibre thermoset composite layer, and a top layer attached to the outer layer (not shown}; a paper honeycomb core material, a side and corner enforcement element 15, a glass fibre thermoset composite layer, and a top layer attached to the composite.

FIG. 2 is a top view of a preferred embodiment of the invention, showing the internal core layer comprising a honeycomb paper or card-board core (13) and a side element (14).

FIG. 3 shows a cross-sectional view of a preferred embodiment of the invention, a table top comprising a top layer (11), a bottom layer (12), a core layer (13), and a side molding (14) laminated into the panel.

The panels may have various applications, particularly where impermeability to humidity, in particular water, is a desirable feature for a structure. By suitable adaption of the panels to suitable scales and shapes and/or the membranous sheet laminate, they may be used in the efficient assembly of, for example; furniture, such as table tops, door panels, cupboard, kitchen tops and doors, interior decorative panels, lining of various structures, and interior insulation panels.

The present invention also pertains to a structural elements, including a planar surface layer of the composite material. Herein, the at least one core layer may be bonded to surface layers, and include one or more outwardly-extending attachment flanges defined by the thickness of the substrate layer and proximal to the surface layer around two adjacent side edges for receiving fastener elements through the thickness of the core layer and into the support member.

One or more tongue sections may preferably project outwardly from the flange remote from the surface layer, whereas two spaced-apart elements define a groove therebetween extending along adjacent sides of the substrate layer for receiving the tongue of a complementary adjacent structural element. The flange may reside at all points intermediate the tongue and the surface layer for permitting the tongue to fit into the groove of a complementary structural element, for permitting a closed surface once two or more adjacent structural elements are coupled.

The present invention is described below in detail in reference to illustrative examples.

EXAMPLE 1

A biaxial fabric glass fibre mat having an area unit weight of 800 g/m? was coated with a furan resin solution in water comprising an acid catalysts, as obtained from TransFurans Chemicals bvba. The fibre mat was impregnated with the resin to obtain an impregnated mat, and then submitted to a gelation process at a gelation temperature of 85° C and for suitable period to form a semisolid material, which was deposited on a polypropylene backing sheet, and rolled onto a

P307582NL 14 reel. The cover factor of the prepared prepreg was above 95%. Before lamination and fabrication, the tackiness of the prepreg was measured and found to be 0.15 MPa; when storing the prepreg at 15° C and 50% relative humidity for 10 days, the tackiness was 0.12 MPa, showing little temporally caused change.

Example 2

A laminate stack was prepared comprising a cardboard honeycomb core, and side elements were added to form the sidings and corners after the cure; and enveloped in one layer of prepreg sheet. The stack was packed in vacuum. Between the prepreg and the honeycomb core, no adhesive film was placed, and the prepreg was cured to be directly bonded to the honeycomb core. The thus obtained panel proved highly fire resistant, light but strong, highly resilient, highly fire resistant, i.e. with a rating of B S1 DO according to NEN-EN 13501-2018 SBI, and was found useful for furniture, e.g. tabletops or kitchen doors, or as decorative building panels.

Claims

Conclusions

1. Lightweight, fire-resistant, sheet-form composite material for use in building products, in building elements, or in furniture applications, comprising:

a. a first layer comprising cross-linked polyfuranyl resin and an inorganic fibrous fabric;

b. at least one core layer having a density less than the density of the first layer; and c. a second layer comprising cross-linked polyfuranyl resin and an inorganic fibrous fabric.

2. The composite material of claim 1, wherein the at least one core layer has a cellular structure, preferably wherein the core layer comprises a paper, cardboard, and/or polymeric foam material comprising a cellular structure.

3. A composite material according to claims 1 or 2, wherein the composite material further comprises an additional outer coating layer on at least one side of the composite material, preferably an additional outer coating layer on at least two sides of the composite material, and even more preferably an additional coating layer completely encapsulating the first, second, and third layers.

4. Composite material according to any one of claims 1 to 3, wherein the second layer with a cellular structure comprises a cellular honeycomb-shaped structure.

5. Composite material according to claim 4, wherein the honeycomb-shaped structure comprises internal walls provided perpendicular to the plane of the second layer having a cellular structure.

6. Composite material according to any one of claims 1 to 3, wherein the one or more layers have a corrugated structure.

7. A composite material according to any one of claims 1 to 6, wherein the one or more core layers is or are selected from corrugated fibreboard, corrugated paper, or honeycomb cardboard.

8. A composite material according to any one of claims 1 to 8, wherein the one or more core layers comprise a polymeric foam material.

9. Composite material according to any one of claims 1 to 6, wherein the one or more core layers further comprise(s) a layer of mineral wool.

10. Composite material according to any one of claims 1 to 8, wherein the fibres are selected from glass fibres, rock fibres, or carbon fibres.

11. Composite material according to any one of claims 1 to 10, wherein the composite material has a fire class of B S1 DO in accordance with NEN-EN 13501-2018 SBI.

12. A durable and recyclable fire-resistant furniture article, exterior or interior panel for a building, or exterior or interior finishing material comprising a composite material according to any one of claims 1 to 11.

13. A method for manufacturing a composite panel according to any one of claims 1 to 11, comprising:

a. impregnating a sheet comprising woven mineral fibres with a liquid polyfuranyl resin composition to provide an impregnated sheet,

b. subjecting the impregnated sheet to conditions which induce gelling of the polyfuranyl resin composition, thereby forming a pre-preg sheet;

c. optionally applying a pre-preg sheet to a transport medium, preferably a backing sheet, and optionally removing the pre-preg sheet from the backing sheet;

d. providing at least one core layer between two pre-preg sheets, in such a manner that the first and second pre-preg sheets are disposed such that the upper surface of the second sheet is opposite the lower surface of the first sheet, thereby forming a sandwich structure; and e. subjecting the sandwich structure to conditions which allow the gelled polyfuranyl resin composition to substantially completely cure, preferably comprising heating the sandwich structure to a specified temperature and for a specified period of time which results in cross-linking and chain growth in the polyfuranyl resin composition.

14. A method according to claim 13, comprising an additional step of applying pressure to the composite material during curing.

The method of claim 14, wherein the step of applying pressure comprises using a vacuum table, a platen press, a bag press, or a nip rolling device.

16. A method of manufacturing a pre-preg sheet for use in forming a composite panel as claimed in any one of claims 1 to 11, comprising:

c. optionally applying a pre-preg sheet to a transport medium, preferably a backing sheet, and optionally removing the pre-preg sheet from the backing sheet; and d. optionally, winding the pre-preg sheet onto the transport medium to form a roll of rolled-up pre-preg sheet.

17. Pre-preg sheet or roll with pre-preg sheet, obtainable by means of a method according to claim 16.