[0001] The present invention relates to fire-retardant composite materials and, in particular, materials comprising wool powder.

BACKGROUND ART

[0002] Residential fires are a significant issue worldwide. In 2015, the US Federal Emergency Management Agency (FEMA) reported that 30.4% of all fires reported were residential and, of those, 74.5% resulted in at least one fatality. This is attributed to people being asleep when fires started. Causes of residential fires were dominated by cooking (42.3%). Such fires, however, only accounted for 3.7% of fatalities. Smoking (the leading cause of bedroom fires), electric appliances and open flames, such as candles, accounted for a corrected 34.3% of known-cause fire deaths. The FEMA statistics show that in the US between 2005-2009 there were 10260 fires where the mattress was the first source of ignition, resulting in 1340 injuries and 371 fatalities.

[0003] Fire retardancy (FR) is, therefore, an important physical property, particularly in interior furnishings.

[0004] Currently, the industry standard for mattresses is to use fire‘barriers’ around the mattress. Fire barriers are able to surround the mattress core without making the mattress stiff. Such barriers may comprise natural products, such as wool or wool/cotton blends, or non-natural products, such as rayon or polybrominated diphenyl ethers (PBDEs). PBDEs have been found to disrupt human thyroid functionality and have been banned by most nations. PentaBDE and octaBDE were banned in 2004, and decaBDE in 2010.

[0005] Wool is a fibre produced by various animals including sheep, goats, camels and rabbits. Wool is well known for its ability to be naturally flame resistant due to several key factors. Wool has a high nitrogen content, high moisture content (a natural regain of 16-17%wt), does not melt, forms a protective outer char and produces a low amount of smoke and fumes during combustion. Wool also has high ignition point of 570-600°C, compared to polyester at 252-292°C and nylon at 160-260°C.

[0006] The complex structure of the microfibril-matrix in wool plays a significant role in determining the mechanical properties. Wool is primarily composed of keratin protein. Keratin is distinguished from other fibrous proteins because its structure has a high physical and thermal stability created not only by the hydrogen bonds and van der Waals forces, but also by the high content of the amino acid cysteine. The natural cysteine content of wool is about 15%wt. Other natural keratin-based fibres contain cysteine, but the cysteine content is relatively low compared to wool. For example, human hair comprises about 7.6%wt cysteine and feathers about 7%wt cysteine. In addition, the relatively high sulphur (3-4%wt) and nitrogen (15-16%wt) contents present in the amino acids are thought to contribute to the low flammability of wool.

[0007] There is a need for effective fire-retardant composite materials that retain the desirable properties of the original material while improving the fire retardancy of the material.

Accordingly, it is an object of the present invention to go some way to avoiding the above disadvantages; and/or to at least provide the public with a useful choice.

[0008] Other objects of the invention may become apparent from the following description which is given by way of example only.

[0009] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date.

SUMMARY OF THE INVENTION [0010] In a first aspect, the invention provides a fire-retardant composite material comprising wool powder. Preferably, the composite material is a foam.

[0011] In another aspect, the present invention provides a fire-retardant composite material comprising wool powder, wherein the composite material is a solid unitary construct. In another aspect, the present invention provides a fire-retardant composite material comprising wool powder, wherein the composite material is self-supporting.

[0012] In another aspect, the present invention provides an article of furniture, upholstery or bedding comprising the fire-retardant composite material of the invention.

[0013] In another aspect, the present invention provides a method of improving the fire- retardant properties of a composite material, the method comprising incorporating wool powder in the composite material. The invention also provides a method of improving the fire-retardant properties of a material, the method comprising incorporating wool powder in the material to provide a fire-retardant composite material.

[0014] In another aspect, the present invention provides wool powder for use as a fire retardant. In another aspect, the present invention provides wool powder when used as a fire retardant. In another aspect, the present invention provides use of wool powder as a fire retardant.

[0015] In another aspect, the present invention provides a fire-retardant additive, the additive comprising wool powder. [0016] This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. [0017] In addition, where features or aspects of the invention are described in terms of

Markush groups, those persons skilled in the art will appreciate that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0018] As used herein the term“wool powder” means animal wool powder and excludes powder prepared from mineral wool, such as kaowool or glass wool, or prepared from metal wool, such as steel wool. The term“wool powder” therefore includes, but is not limited to, animal wool powders such as sheep wool powder, goat wool powder, camel wool powder, rabbit wool powder, and mixtures thereof. Preferably, the wool powder is sheep wool powder.

[0019] As used herein“(s)” following a noun means the plural and/or singular forms of the noun. [0020] As used herein the term“and/or” means“and” or“or” or both.

[0021] The term“comprising” as used in this specification means“consisting at least in part of’. When interpreting each statement in this specification that includes the term“comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and“comprises” are to be interpreted in the same manner. [0022] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2,

3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0023] Although the present invention is broadly as defined above, those persons skilled in the art will appreciate that the invention is not limited thereto and that the invention also includes embodiments of which the following description gives examples.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Since the introduction in the United States of standard 16 CFR 1633 by the Consumer Product Safety Commission in 2007 for whole mattress burn testing, many attempts have been made to find an integrated solution for fire retardancy. An integrated solution would be an additive to the construction of the mattress in place of a‘barrier’, which is current industry practice.

[0025] Advantageously, the inventor has found that the fire-retardant properties of a material can be improved by incorporating wool powder.

[0026] Accordingly, in one aspect, the present invention provides a fire-retardant composite material comprising wool powder.

[0027] In another aspect, the present invention provides a method of improving the fire- retardant properties of a composite material, the method comprising incorporating wool powder in the composite material. The invention also provides a method of improving the fire-retardant properties of a material, the method comprising incorporating wool powder in the material to provide a fire-retardant composite material.

[0028] In another aspect, the present invention provides wool powder for use as a fire retardant. In another aspect, the present invention provides wool powder when used as a fire retardant. In another aspect, the present invention provides use of wool powder as a fire retardant. [0029] A powder is a generally granular material that has a fine grain size, and flows freely when shaken or tilted.

[0030] Wool powder may be prepared from wool by methods known to those persons skilled in the art. In one embodiment, the wool is sheep wool. The diameter of sheep wool typically ranges from about 10 pm to about 45 pm. Fibre diameter is an important characteristic of wool in relation to its quality and price. For example, finer wools are softer and suitable for use in garment manufacturing.

[0031] Wool powder has primarily been used in the cosmetic sector, for example, as a base in setting powders and foundations.

[0032] In one embodiment, wool powder is prepared by the method described in Weilin et al. (Weilin Xu, Weigang Cui, Wenbin Li, Weiqi Guo. (2003). Development and characterizations of super -fine wool powder. Powder Technology, Vol. 140, pp. 136-140), the entire disclosure of which is incorporated by reference herein. The method described in Weilin et al. comprises a 0.5% sodium hypochlorite (NaCIO) pre-treatment of short wool fibres (25 pm in diameter) followed by grinding into a powder having a particle size of about 2 pm. Various other methods of preparing wool powder are known to those persons skilled in the art. For example, wool powder may also be prepared by cryogenically freezing wool, followed by grinding to a powder. Those persons skilled in the art would appreciate that wool powder prepared by any of those other methods may be useful in the current invention.

[0033] In one embodiment, the wool powder has an average particle size of about 1-40 pm. In various embodiments, the wool powder has an average particle size of about 1-10 pm, or about 1-5 pm, or about 1-4 pm. In one embodiment, the wool powder has an average particle size of about 1-3 pm. In one embodiment, the wool powder has an average particle size of about 4 pm or less. Preferably, the wool powder has an average particle size of about 2 pm.

[0034] Average particle size may be readily determined by a person skilled in the art using well-known techniques, for example, scanning electron microscopy (SEM).

[0035] The fire-retardant properties of a material can be determined using tests and apparatus that are well-known to those persons skilled in the art. Such tests generally measure the response of a material to fire or smoke. [0036] One such test is set out in 16 CFR Part 1633 (as revised in January 2011), which sets a standard for the flammability (open flame) of mattress sets. The test method, set out in 16 CFR Part 1633.7, measures the flammability performance of a mattress set specimen during exposure to a specified flaming ignition source when the mattress set is allowed to burn freely in a specified test area.

[0037] Another such test is set out in ISO 5660-1 :2002 (Reaction-to-fire tests - Heat release, smoke production and mass loss rate - Part 1 : Heat release rate (cone calorimeter method)). ISO 5660-1 :2002 specifies a method for assessing the heat release rate of a specimen exposed in the horizontal orientation to controlled levels of irradiance with an external igniter. The heat release rate is determined by measurement of the oxygen consumption derived from the oxygen concentration and the flow rate in the combustion product stream. The time to ignition (sustained flaming) is also measured in this test. The ISO 5660-1 :2002 standard has been revised by ISO 5660-1 :2015, which includes smoke production rate (dynamic measurement). The dynamic smoke production rate is calculated from measurement of the attenuation of a laser light beam by the combustion product stream. Smoke obscuration is recorded for the entire test, regardless of whether the specimen is flaming or not.

[0038] Yet another test is set out in UK standard British BS 5852:2006. According to this testing standard, the material being tested is placed on a rig simulating a chair and then the material is subjected to an ignition source. There are 8 classes of ignition sources, each class doubling in heat intensity compared to the preceding class. The ignition sources used most frequently are sources 0: smouldering cigarette, 1 : simulated match and 5: wooden crib. The material passes the test if no flaming or progressive smouldering is observed on both cover and interior material after being subjected to the ignition source.

[0039] While such tests may be used to determine the fire-retardant properties of a material, the present invention is not limited to any particular method of testing.

[0040] Accordingly, in one embodiment the composite meets UK standard British BS 5852:2006 source 0. In another embodiment, the composite meets UK standard British BS 5852:2006 source 1. In another embodiment, the composite meets UK standard British BS 5852:2006 source 5.

[0041] Typically, the composite comprises an amount of wool powder sufficient to increase the fire-retardant properties of the composite compared to the corresponding material without wool powder. In one embodiment, the composite comprises an amount of wool powder sufficient to lower the peak heat release of the composite by at least about 50% compared to the corresponding material excluding wool powder. In one embodiment, the composite comprises an amount of wool powder sufficient to lower the peak heat release of the composite by at least about 50% compared to the corresponding material excluding wool powder when tested in accordance with the ISO Standard 5660.1 :2002 Reaction-to-fire tests - Heat release rate. In one embodiment, the composite comprises an amount of wool powder sufficient to meet UK standard British BS 5852:2006 source 0. In another embodiment, the composite comprises an amount of wool powder sufficient to meet UK standard British BS 5852:2006 source 1. In another embodiment, the composite comprises an amount of wool powder sufficient to meet UK standard British BS 5852:2006 source 5.

[0042] In one embodiment, the composite comprises about 5-30%wt wool powder. In one embodiment, the composite comprises about 5%wt wool powder, or about 6%wt wool powder, or about 7%wt wool powder, or about 8%wt wool powder, or about 9%wt wool powder, or about 10%wt wool powder, or about 1 l%wt wool powder, or about 12%wt wool powder, or about 13%wt wool powder, or about 14%wt wool powder, or about 15%wt wool powder, or about 16%wt wool powder, or about 17%wt wool powder, or about 18%wt wool powder, or about 19%wt wool powder, or about 20%wt wool powder, or about 21%wt wool powder, or about 22%wt wool powder, or about 23%wt wool powder, or about 24%wt wool powder, or about 25%wt wool powder, or about 26%wt wool powder, or about 27%wt wool powder, or about 28%wt wool powder, or about 29%wt wool powder, or about 30%wt wool powder. The invention is not, however, limited to this range and other ranges may also be useful.

[0043] In one embodiment, the composite comprises about 15-25%wt wool powder. In one embodiment, the composite comprises about 15%wt wool powder, or about 16%wt wool powder, or about 17%wt wool powder, or about 18%wt wool powder, or about 19%wt wool powder, or about 20%wt wool powder, or about 21%wt wool powder, or about 22%wt wool powder, or about 23%wt wool powder, or about 24%wt wool powder, or about 25%wt wool powder. In one embodiment, the composite comprises about 15%wt wool powder. In another embodiment, the composite comprises about 18%wt wool powder. In another embodiment, the composite comprises about 20%wt wool powder. In another embodiment, the composite comprises about 25%wt wool powder. [0044] In one embodiment, the fire-retardant composite material comprises a foam comprising wool powder.

[0045] Preferred foams are those commonly used in the manufacture of furniture, upholstery and bedding. In one embodiment, the foam is produced from a form setting material. Preferably, the foam is a polyurethane foam or a latex foam.

[0046] In one embodiment, the foam is a polyurethane foam. In one embodiment, the foam is a rigid polyurethane foam. In another embodiment, the foam is a flexible polyurethane foam.

[0047] Polyurethane is a polymer composed of organic units joined by carbamate (urethane) links. Advantageously, the wool powder may be combined with the liquid monomer(s) and other components prior to polymerisation to form a fire-retardant composite material.

[0048] While polyurethane is a preferred foam, those persons skilled in the art will appreciate that the invention is not limited thereto, and fire-retardant composite materials comprising other polymer foams are also contemplated.

[0049] In another embodiment, the foam is a latex foam.

[0050] As used herein,“latex” is an emulsion of polymer in an aqueous medium, and includes natural latex, such as from a rubber tree, and synthetic latex. Natural latex is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins, and gums that coagulate on exposure to air. Advantageously, the wool powder may be combined with the liquid latex prior to curing to form a fire-retardant composite material.

[0051] A person skilled in the art would appreciate that other components may be

incorporated in the foam. For example, the foam may also comprise foaming agents, gelling agents such as pectin or sodium silicofluoride, stabilising agents such as ammonia, curing agents such as sulfur or 2-mercaptobenzothiazole, antioxidants, and anti-ozonants.

[0052] The invention also contemplates layered fire-retardant composite materials. For example, materials in which one or more layers of foam excluding wool powder is surrounded or encapsulated by a layer of foam comprising wool powder. In one embodiment, the layer of foam comprising wool powder is at least about 5 mm thick, preferably about 25 mm thick. [0053] The fire-retardant composite material may be a solid unitary structure. For example, in one embodiment, the material is in the form of a rigid unitary structure, such as a rigid panel, board or sheet. In another embodiment, the material is in the form of an elastomeric unitary structure, such as an elastically deformable or elastically compressible structure. Those persons skilled in the art will appreciate that once the unitary structure is formed, the structure may be combined with other elements to form an article. For example, the unitary structure may be layered with one or more composite materials of the invention and/or other materials, or the unitary structure may be coated with one or more other materials.

[0054] The fire-retardant composite material may be self-supporting. As used herein, the term “self-supporting” means the material is capable of holding itself together and maintaining its shape without additional support. For example, the term“self-supporting” excludes materials that are intended for application, or applied, to substrates, such as paints and coatings. The term “self-supporting” does not, however, exclude materials that are optionally combined with other materials, for example in layered fire-retardant composite materials.

[0055] In one embodiment, the wool powder is dispersed in the fire-retardant composite material. The wool powder may be dispersed in the composite material homogeneously or at least substantially homogeneously. Accordingly, in one embodiment the fire-retardant composite material is homogeneous or substantially homogeneous.

[0056] The fire-retardant composite material may comprise other known fire-retardants. In one embodiment, the fire-retardant composite material does not comprise fire-retardants other than wool powder.

[0057] The fire-retardant composite material may be useful in variety of furniture, upholstery and bedding articles. For example, the fire-retardant composite may be useful in a mattress, pillow or cushion.

[0058] In one embodiment, the fire-retardant composite material is a composite wood product comprising wool powder.

[0059] Composite wood products are manufactured by mixing wood strands, particles, chips, fibres, flakes, veneers, or boards with adhesives. Medium-density fibreboard is a type of composite wood product manufactured by mixing wood fibres with wax, such as paraffin wax, and a resin binder to form panels. Particleboard is a type of composite wood product manufactured by mixing wood chips with a resin binder to form panels. Oriented strand board is similar but uses machined wood flakes.

[0060] Resin binders may include amino-formaldehyde, urea resin, modified urea resin, urea- formaldehyde resin, modified urea-melamine resin, modified urea-phenol resin, melamine resin, modified melamine resin, modified melamine-phenol resin, phenol resin, or modified phenol resin.

[0061] Wood composite materials comprising wool powder may be manufactured by, for example, mixing the wool powder with one or more of the component materials before or during manufacture. In one embodiment, the wool powder is mixed with the dry solid components before adding the adhesive.

[0062] In another aspect, the present invention provides a fire-retardant additive, the additive comprising wool powder.

[0063] The following non-limiting examples are provided to illustrate the present invention and in no way limit the scope thereof.

EXAMPLES

Wool powder/latex blend

Open flame testing

[0064] Wool powder, prepared from 100% New Zealand super white wool (30-35 pm in diameter, 25-75 mm in length, having 0% vegetable matter prior to processing) by the methodology described by Weilin et al. (Weilin Xu, Weigang Cui, Wenbin Li, Weiqi Guo. (2003). Development and characterizations of super -fine wool powder. Powder Technology,

Vol. 140, pp. 136-140), was obtained from Seiwa Kasei Co., Ltd.

[0065] Wool powder was mixed in four different ratios with liquid latex rubber (The

Fibreglass Shop, Hamilton, NZ). The ratios used were 15%wt, 18%wt, 20%wt and 25%wt wool powder in latex. The wool powder was mixed with the latex using a Braun 400 watt whisk to aerate and mix at the same time. All samples were mixed with the Braun whisk for 5 minutes, except the 25% wool variants as these started to become hard and difficult to mix after 2 minutes so they were mixed for 1.5 minutes. The mixtures were poured into stainless steel trays measuring 25.4 x 25.4 x 2.5 cm in two layers. The first layer of 500 g was vulcanised at 104°C for 45 minutes using a Sanyo convection oven and then allowed to cool to ambient temperature. Then a second layer was added and vulcanised for another 45 minutes at this temperature and allowed to cool. The two layers were then vulcanised for a further 45 minutes at this

temperature. The wool composite samples were tested against latex only control samples having similar dimensions and curing conditions.

[0066] An open flame test replicating closely the conditions used in the National Mattress Standard test 16 CFR Part 1633 (as revised January 2011) was used to compare the bum time of the samples. A propane burner was constructed as per the instructions for one of the burners in the technical manual for 16 CFR 1633 - Standard for the flammability (open flame) of mattress sets. Samples were conditioned for 48 hours at 18-25°C and relative humidity below 55% as per the instructions in the same technical manual.

[0067] The propane burner and was applied on the horizontal plane against an edge of the square composite samples and ignited for separate tests of 30 seconds and 60 seconds and the samples were observed for 5 minutes after ignition.

[0068] The latex only control sample burned vigorously even at a lower flame exposure time of 30 seconds. The sample sputtered vigorously and the molten latex dripped continuously during the bum procedure. The composite sample with 15%wt wool powder showed a lower rate of burning when compared with the control. The sputtering of the sample and the latex drip during the bum procedure was reduced. However, the flame kept on progressing through the sample and did not extinguish by itself.

[0069] For the composite sample with 18%wt wool powder, the flame completely

extinguished after 2 minutes from the time of exposure. The duration of flame exposure did not influence the burn time of this composite.

[0070] Inclusion of 20%wt or 25%wt wool powder in the latex composite increased the rigidity of the sample. But, as noted above, a higher percentage of wool powder also proved difficult to mix and a homogeneous mixture could not be obtained. Both of these composite samples compared well with the composite sample with 18%wt wool powder, but it took longer for the flames to extinguish in these samples. This is attributed to the inhomogeneous nature of both these composite samples. More specifically, longer than expected burning may be due to regions having a lower ratio of wool to latex due to incomplete mixing, or a propensity of wool powder to agglomerate. [0071] A clear link was identified between the addition of wool powder to the latex to form a composite material and the improvement of the fire-retardant properties of the composite compared to the 100% latex control sample. The composite materials could hold a flame for a period of time, but the composite sample with 18%wt wool powder self-extinguished after 2 minutes. In a practical application, this could prevent other objects in a room combusting and inhibit the ability of a fire to spread.

Cone calorimetry testing

[0072] Samples were also prepared in the same ratios for cone calorimetry testing with AWTA Melbourne. The ratios used again were 15%wt, 18%wt, 20%wt and 25%wt wool powder in latex. Samples were tested in accordance to ISO Standard 5660.1-2002 Reaction-to-fire tests - Heat release rate.

[0073] Table 1. Cone calorimeter results.

[0074] The 100% latex sample in the cone calorimetry testing burned out in 210 seconds of the 1800 second test, while the wool composite samples lasted approximated 430 seconds of the 1800 second test.

[0075] The data in Table 1 shows there was a 59.6% lower peak heat release (kW/m ² ) after ignition for the 15%wt composite material compared to the 100% latex sample. A plot of the heat release rate versus time for these two materials also showed that the 15%wt composite material had a flatter, less intense heat release. This would be expected to reduce the risk of a fire spreading to neighbouring objects.

[0076] The smoke production rate of a material is an important characteristic, both for visibility and air quality during a fire. A lower smoke production rate increases the survivability of a house fire as well. A plot of smoke production rate versus time showed the 100% latex sample at 200 seconds produced about 500% more smoke per second compared to the 15%wt composite material.

[0077] The average effective (corrected for weight) heat of combustion (MJ/kg) is the total energy released when a substance undergoes combustion. The data in Table 1 show a 13% improvement when the amount of wool powder in the composite material is increased from 0%wt to 15%wt, and a 20% improvement when the amount of wool powder in the composite material is increased from 0%wt to 25%wt.

Fire retardancy testing

[0078] A sample comprising 25%wt wool powder in latex was prepared for testing according to UK standard British BS 5852:2006. Theatrical Foam Latex System (obtained from The Monster Makers Inc., Cleveland, Ohio, USA) was used to prepare the latex foam. Accordingly, 500 g latex foam was prepared by blending of 75%wt high solids foam latex base, 13%wt foaming agent and 7%wt curing agent. The blend was mixed using an industrial mixer with a fan mixing blade at 600 rpm for 30 seconds, then at 900 rpm for 6 minutes, 30 seconds to

incorporate as much air as possible. The speed was then decreased to 600 rpm for 5 minutes until an ammonia smell dissipated. The blend was mixed for a further 4 minutes to refine the blend. 25wt% wool powder was added through a sieve to separate any clumps. The blend was mixed continuously at 600 rpm until no wool powder was visible (approximately 60 seconds). 5%wt gelling agent was added to the blend over 15 seconds and the blend mixed at 600 rpm for 2 minutes, before pouring the mixture into the required moulds. The moulds were cured at 100°C for 60 minutes, before removing the foam and allowing the sample to condition for 24 hours.

[0079] Test method source 5: wooden crib was used as the ignition source, which is the highest standard of the frequently used ignition sources. The sample material was placed on the test rig. A wooden crib was then place upright on top of the sample material and ignited to produce a flame. After about 4 minutes, the ignited wooden crib had completely extinguished with no spread of the flame along the surface of the test material. This result demonstrates the sample material meets UK standard British BS 5852:2006 source 5.

[0080] It is not the intention to limit the scope of the invention to the abovementioned examples only. As would be appreciated by a skilled person in the art, many variations are possible without departing from the scope of the invention as defined in the accompanying claims.