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Title:
ENHANCED PERFORMANCE OF WOOD AND ENGINEERED WOOD PRODUCTS USING COMBINED DURABILITY AND FLAME RETARDANCY
Document Type and Number:
WIPO Patent Application WO/2019/004846
Kind Code:
A1
Abstract:
Described herein is a treatment method or process and wood products thereof. In particular, a product formulation of a single phase solution combining a wood preservative (durable component) with a Flame Retardant component [FR] to produce a durable Flame Retardant [dFR] treated wood product. The durable component comprises a range of copper based and non-copper based wood preservatives, while the Flame Retardant [FR] component comprises alkali metal silicates and alkali metal aluminate compounds. The durable Flame Retardant [dFR] working solution undergoes chemical impregnation (treatment) followed by a heat (fixation) process step that locks the chemical into the wood making it non-leachable. The durable Flame Retardant [dFR] treated wood products are tested for their enhanced fire performance properties. When heated, wood undergoes thermal degradation and combustion producing gases, vapours, tars and chars. Using the 'cone calorimeter' burn test method (AS/NZS 3837), durable Flame Retardant [dFR] treated wood products show a significant reduction in the following parameters: heat release rate (peak & average HRR values), mass loss rate (M LR) and smoke generated values (Smoke Extinction Area - SEA) compared to untreated radiate pine. The main tests being; accelerated weathering and burn tests (AS/NZS3837) all carried out at BRANZ, New Zealand.

Inventors:
MOON, Ronald Philip (19 Melanesia Road, KohimaramaAuckland, 1071, 1071, NZ)
Application Number:
NZ2018/050092
Publication Date:
January 03, 2019
Filing Date:
June 27, 2018
Export Citation:
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Assignee:
WOOD MODIFICATION TECHNOLOGIES LIMITED (10 Maheke Street, St HeliersAuckland, 1071, 1071, NZ)
International Classes:
B27K3/26; A01N3/00; A01N43/653; A01N59/20; A01P3/00; A01P7/04; B27K3/08; B27K3/20; C09K21/02
Domestic Patent References:
WO2016022032A22016-02-11
WO2005094586A12005-10-13
WO2012072592A12012-06-07
Foreign References:
JP2000108108A2000-04-18
JPS62144902A1987-06-29
US20040091549A12004-05-13
CA2234130A11998-12-18
Other References:
XIMENES, F. A. ET AL.: "Protection of wood using oxy-aluminium compounds", FOREST PRODUCTS JOURNAL, vol. 56, no. 11 / 12, 2006, pages 116 - 122, XP055566915
SULAIMAN, O. ET AL.: "Effect of Incorporation of Flame Retardants on Some of the Properties of Phenol Formaldehyde Medium Density Fiberboard", INTERNATIONAL JOURNAL OF AGRICULTURAL RESEARCH, vol. 3, no. 5, 2008, pages 331 - 339, XP055566919
Attorney, Agent or Firm:
CREATEIP (PO Box, EdgewareChristchurch, 8143, 8143, NZ)
Download PDF:
Claims:
WHAT IS CLAIMED IS:

1. A process of imparting enhanced durability and fire retardancy properties to lignocellulosic material comprising:

a wood preservative; and

a flame retardant [FR], consisting of alkali metal silicates and/or alkali metal aluminates that utilise an impregnation treatment process and/or spray, immersion, deluge system such that there is chemical penetration into the cellular internal voids of the lignocellulosic material which becomes insoluble (fixed) on subsequent heating steps.

2. The lignocellulosic material product produced by the process of claim 1, wherein the product possesses a property of increased Fire Retardancy [FR].

3. The lignocellulosic material product produced by the process of claim 1, wherein the product possesses a property of increased durability to fungal decay, rot, and /or insect attack.

4. The product produced by the process of claim 1, wherein the wood preservative in

combination with the Flame Retardant [FR] generates an incremental increase in durability to fungal decay, rot and/or insect attack.

5. The wood impregnation treatment process of claim 1, wherein the pressure ranges from 0 to 3,500kpa and vacuum 0 to -90kpa.

6. The wood impregnation treatment process of claim 1 or claim 5, wherein the chemical absorption ranges from 15 to 950 Litres/m3 (loading).

7. The process of any one of the preceding claims, wherein the process allows for the wood preservative and Flame Retardant [FR] to co-penetrate during the wood impregnation treatment process.

8. The process of any one of the preceding claims, wherein the wood preservatives are selected from any one of the following: Copper Chrome Arsenate (CCA), dissolved Copper Azoles (dCA), micronized Copper Azoles (mCA), Alkaline Copper Quaternary (ACQ), micronized Copper Quaternary (mCQ), water based Azoles including; tri-azoles - propiconazole, tebuconazole, cyproconazole and carbamates including; iodopropynyl Butyl Carbamate (IPBC) and/or combinations thereof.

9. The wood preservatives of claim 8, wherein the preservatives meet hazard class (H) and/or user categories (UC); H3.1, H3.2, H4, H5 (New Zealand), H3, H4, H5 (Australia), UC3A, UC3B, UC4A, UC4B, UC4C & UC5 (United States of America) and/or other equivalent global categories.

10. The process of any one of the preceding claims, wherein the Flame Retardant [FR] are selected from any one of the following: soluble alkali metal silicates including; sodium silicate (ortho, meta, di & tri-silicates), potassium silicate, lithium silicate and soluble alkali metal aluminates including sodium aluminate and potassium aluminate and/or combinations thereof.

11. The Flame Retardant [FR] of claim 10, further comprising aluminium oxide [Al203] nano- particles (dispersions), aluminium silicate [AI203.Si02] nano-particles (dispersions) and silicon dioxide [Si02] nano-particle dispersions.

12. The Flame Retardant [FR] of claims 10 or 11, wherein the sodium aluminate and potassium aluminate are stabilised using chelating agents as the stabiliser.

13. The stabilisers as claimed in claim 12, wherein the stabilisers are selected from any one of the following amine compounds; Ethylenediaminetetra-acetic acid (EDTA), Ethylene diamine (EN), Diethylenetriaminepenta-acetic acid (DTPA), (N-(hydroxyethyl)- ethylenediaminetriacetic acid) (HEDTA), Ethylene glycol tetra-acetic acid (EGTA); salts of gluconic acid ("gluconates"), sodium gluconate, potassium gluconate, salts of tartaric acid and ethanolamine compounds, monoethanolamine (M EA), diethanolamine (DEA), triethanolamine (TEA) and/or combinations thereof.

14. The Flame Retardant [FR] of claim 11, wherein the aluminium oxide [Al203] nano-particles (dispersions), aluminium silicate [AI2Q3.Si02] nano-particles (dispersions) and silicon dioxide [Si02] nano-particle dispersions are suspensions in water or organic solvents.

15. The organic solvents of claim 14, wherein the organic solvents are selected from any one of: ethanol, mineral oils, high and low aromatic hydrocarbons and glycols (ethylene and propylene) and/or combinations thereof.

12. The process of claim any one of the preceding claims, wherein other additives selected from any one of the following: water repellents, colourants, stabilisers, surfactants, and/or combinations thereof for the impregnation and spray treatment processes enhance properties of increased stability, penetration and colour.

13. The process of any one of the preceding claims, wherein the combination of wood

preservatives (chemical - durable) and Flame Retardant [FR] (alkali metal silicate and alkali metal aluminates) liquids impregnate internal cells voids and applying a heat or drying step causes the liquid durable (chemical) Flame Retardant [dFR] combination to become insoluble, fixed and encapsulated within the lignocellulosic material.

14. The process of any one of the preceding claims, wherein the combination wood preservatives (treated to H3, H4, H5 or equivalent) and Flame Retardants [FR] including alkali metal silicates and alkali metal aluminates produce a working solution required for the impregnation treatment into the wood or engineered wood products.

15. The process of any one of the preceding claims, wherein the combination wood preservatives (treated to H3, H4, H5 or equivalent) and Flame Retardants [FR] including alkali metal silicates and alkali metal aluminates produce the working solution required for impregnation treatment is followed by the application of liquid alkali metal silicates or liquid metal aluminates that is applied either via spray, brush, immersion or deluge systems to the wood or engineered wood products.

16. The process of any one of the preceding claims, wherein the combination wood preservatives (treated to H3, H4, H5 or equivalent) and Flame Retardants [FR] including alkali metal silicates and alkali metal aluminates, to produce the working solution and whereby the wood preservative is the only working solution that undergoes the impregnation treatment and the liquid alkali silicates or liquid metal aluminate is applied either via spray, brush, immersion or deluge systems to the wood or engineered wood products.

17. The process of any one of the preceding claims, wherein the combination wood preservatives (treated to H3, H4, H5 or equivalent) and Flame Retardants [FR], whereby the liquid alkali metal silicates and liquid alkali metal aluminates are applied via spray, immersion or deluge systems at a temperature range of 0°C to 100°C.

18. The process of any one of the preceding claims, wherein the wood preservative chemical retentions range from 0.1kg/m3 copper (Cu) to 20kg/m3 copper (Cu) for the copper based wood preservatives.

19. The process of any one of the preceding claims, wherein the alkali metal silicates (flame

retardants) chemical retentions range from 0.2kg/m3 elemental Si (for Sodium, Potassium & Lithium) to 45kg/m3 elemental Si (for Sodium, Potassium & Lithium).

20. The process of any one of the preceding claims, wherein the alkali metal aluminates (Flame Retardants) chemical retentions range from 0.2kg/m3 elemental Al (for Sodium, Potassium & Lithium) to 45kg/m3 elemental Al (for Sodium, Potassium & Lithium).

21. The process of any one of the preceding claims, wherein the other additives such as water repellents, colourants and the like included in the chemical formulation (working solution) and impregnation treatment process provide other value added properties of wood such as increased dimensional stability and colour.

22. The process of any one of the preceding, wherein the heat (fixation) process temperature for the 'treated flame retardant' is within the range 50°C to 150°C.

23. The process of any one of the preceding claims, wherein the thermal modification temperature is in the range of 150°C to 250°C for durable Flame Retardant [dFR] or Flame Retardant [FR] when thermally modified in a kiln.

24. The process of any one of the preceding claims, wherein the durable Flame Retardant [dFR] treated wood product meets Australian Bushfire Standards (AS3959 BAL29) and USA Forest fire Standards (ASTM E 84) respectively.

The process of any one of the preceding claims, wherein the lignocellulosic material is selected from any one of the following wood species: radiata pine (pinus radiata), western red cedar and other cedars, Douglas fir, southern yellow pine, scots pine, hoop pine, slash pine and all other soft and hard type pines and/or combinations thereof.

Description:
ENHANCED PERFORMANCE OF WOOD AND ENGINEERED WOOD PRODUCTS USING COMBINED

DURABILITY AND FLAME RETARDANCY

RELATED APPLICATIONS

This application derives priority from New Zealand patent application number 733302 incorporated herein by reference.

TECHNICAL FIELD

Described herein is an enhanced performance of wood and engineered wood products (EWP) using varying combinations of wood preservatives (durability) and flame retardants [FR]. More specifically, a treatment method or process and wood products thereof that utilise impregnation, spray, immersion and deluge systems or in varying combinations. The wood preservatives used consist of copper and non- copper based approved formulations and the flame retardants [FR] being based on alkali metal silicates, alkali metal aluminates and other chemical additives to achieve enhanced performance.

BACKGROUND ART

Development in the area of treatment impregnation (wood modification) and other applied spray, immersion and deluge systems has increased significantly due to the demand and need to enhance the performance properties of untreated, treated (durable) and engineered wood products.

Current heat treatment and chemical treatment processes applied to most wood species fail to achieve and meet a combined level of durability (for both fungal decay and insect attack - mainly termites) and flame retardancy prescribed and required by certifiers and territorial authorities globally.

While conventional chemical treated timber (wood preservatives) involves the impregnation of lignocellulosic material such as wood and engineered wood products with chemical preservatives and other like compositions, using various vacuum and pressure cycles, which are generally limited to dry substrates in order to provide 'free space' to accommodate the additional fluid uptake 'working solution' requirements. It is in the addition of the combined Flame Retardant [FR] to the wood preservative in the form of a 'working solution' that is then impregnated into the wood that determines the effectiveness of the treatment penetration throughout the wood substrate.

The wood treatments must meet the required product penetration levels and retentions (i.e. loadings - kg's per m 3 ) outlined within the prevailing durability standards (for example H3, H4, H5). Fire Retardant [FR] penetrations and retentions are not prescriptive but rely on the product performance requirements for Bushfire (Australia) and Forest Fire applications. From the above, it can be seen that there is a global opportunity for enhanced performance of wood and engineered wood products using combined durability and flame retardancy to cover all major treatment hazard classes in H3, H4, H5 (Australia) and the USA equivalents User Categories (UC-3, UC-4 and UC-5). The use of durable Flame Retardant [dFR] treated wood products that meet the Australian Standard (AS3959 - Construction of buildings in Bushfire prone areas, exposed to BAL-29 and BAL-40) is large as it covers much of Australia's highly populated states and territories including; Victoria, New South Wales, South Australia, Australian Capital Territory (ACT) and Western Australia - most of Australia. Currently, wood and wood engineered products has had little presence in the Bushfire prone areas due to the limited availability of indigenous hardwoods and the inability to produce a durable Flame Retardant [dFR] treated product that meets the fire test standards.

The Australian Bushfire market size is approximately AU $400 million per annum and continues to grow with the expansion of "bushfire prone areas". The predominant use of radiata pine to manufacture the durable Flame retardant [dFR] treated wood products is ideally suited as resource (forests) are readily available in Australia, NZ and Chile. Radiata pine it is a regenerative product, relatively low cost and can be readily treated and processed using existing plant and equipment. Both the operating and capital costs to integrate into an existing treatment/wood processing operating is relatively low. The added value to producing a durable Flame Retardant treated wood product is multi-faceted in terms of providing value at the forest (feedstock), chemical manufacture, chemical treatment, wood processing and many more distribution and storage add-ons.

The application for durable Flame Retardant [dFR] wood products includes a wide of outdoor applications including; decking, fencing, structural bearers/joists, landscape and primed products including; weatherboards and trim boards. Also there is the application to provide durable Flame Retardant [dFR] treated wood products into higher retention applications such as fencing, posts and transmission poles and others

The USA Forest fire market is in excess of US $1.5 billion per annum and continues to grow exponentially. Similarly, the USA Forest Fire market for the use of durable Flame Retardant [dFR] treated wood products that meets the relevant USA Standards and could be produced in the same way that the product is produced for the Australian Bushfire market, as the testing requirements are very similar.

With a durable Flame Retardant [dFR] treated wood and a durable Flame Retardant [dFR] or Flame Retardant [FR] thermally modified timber (TMT) it is the inorganic metal oxide component that provide increased fire retardancy to the treated wood.

For 'Impregnation Modification' to occur, the impregnant molecules (chemical(s) must be of a sufficiently small size by which to enter the cell wall (pore diameter less than 5nm). As the wood swells the void volume ('micro-pores') in the cell wall increases which are then filled with liquid chemical(s) (called 'working solution') which fixes chemically via various reaction mechanisms.

From the above, it can be seen that there is a need for an enhanced performance of wood and engineered wood products (EWP) using varying combinations of wood preservatives (durabil ity) and flame retardants [FR] or at least provides the public with a useful choice.

Further aspects and advantages of the treatment method or process and wood products thereof will become apparent from the ensuing description that is given by way of example only.

SUMMARY

Described herein is an enhanced performance of wood and engineered wood products using combined durability and flame retardancy that comprises several aspects. Firstly, in the product formulation to produce a durable Flame Retardant [dFR] single phase 'working solution' for chemical impregnation. Secondly, the wood impregnation treatment process and thirdly, the heat (fixation) process which ensures that the impregnated chemicals are firmly fixed into the wood structure.

In a first aspect there is provided a process of imparting enhanced durability and fire retardancy properties to lignocellulosic material comprising:

a wood preservative; and

a flame retardant [FR], consisting of alkali metal silicates and/or alkali metal aluminates that utilises an impregnation treatment process and/or spray, immersion, deluge system such that there is chemical penetration into the cellular internal voids of the lignocellulosic material which becomes insoluble (fixed) on subsequent heating steps.

In a second aspect there is provided a lignocellulosic material product produced by the process of imparting enhanced durability and fire retardancy properties the lignocellulosic material comprising: a wood preservative;

a flame retardant [FR], consisting of alkali metal silicates and/or alkali metal aluminates that utilises an impregnation treatment process and/or spray, immersion, deluge system such that there is chemical penetration into the cellular internal voids of the lignocellulosic material which becomes insoluble (fixed) on subsequent heating steps.

Advantages of the above include product formulations that combine wood preservatives (chemicals) and Flame Retardants [FR] that provide an enhanced durability and flame retardancy required in Bushfire and Forest Fire prone areas. Flame Retardancy [FR] on its own in outdoor applications has limited value without having the combined durability of fungal decay (rot) and insect attack (termites). Furthermore, the product formulations which include the flame retardants [FR] do not in any way impede or hinder the normal penetration and retention properties of the water borne wood preservatives when applied using the various treatment processes. Treatment using these formulations meets the appropriate industry standards for wood preservation. The advantage of this treatment process is that it incorporates a full impregnation step to achieve both durability and fire retardancy in the treated wood and engineered wood products. A further advantageous effect of this invention being that treated timber (to hazard classes H3, H4 and H5) can achieve a level of flame retardancy that will allow it to meet the Australian Bushfire (AS 3959-2009) and potentially the USA Forest Fire Standards. The treatment process is versatile as a large range of treated timbers can achieve durable Flame Retardants such as; radiata pine, pinus elloitti (slash pine), araucaria (hoop pine), douglas fir (oregon pine), pinus carribaea (yellow pine, yellow southern pine), cedar (western red cedar). Finally, the significance and impact of this invention is that the durable Flame Retardant [dFR] treated wood product is fully impregnated throughout the wood substrate making it acceptable for unpainted and painted treated wood products. Also, the fact that this durable Flame Retardant [dFR] uses a single homogenous 'working solution' that requires a single treatment and heat (fixation) process all of which are able to be achieved in an existing treatment plant is most advantageous.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the enhanced performance of wood and engineered wood products (EWP) using varying combinations of wood preservatives (durability) and flame retardants [FR] will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 illustrates HRR heat curves showing the peak and average HRR values over 1800 sec (30 min.).

In particular, Heat Release Rate (HRR): durable Flame Retardant [dFR] treated wood samples (FH6239-15-25-1/2/3) after Post-Weathering Test (ASTM D2898 Method B modified) and Burn

Test AS/NZS 3837;

Figure 2 illustrates The HRR heat curves showing the peak and average HRR values over 600 sec (10 min.) versus untreated wood. In particular, Heat Release Rate (HRR): durable Flame Retardant treated wood samples (FH6239-15-25-1/2/3) after Post-Weathering versus Untreated wood samples for radiata pine;

Figure 3 illustrates the Mass Loss Rate (MLR): mass loss over the duration of the burn test for durable Flame Retardant [dFR] treated wood samples FH6239-15-25-1, 2, and 3 (all completed post- weathering test ASTM D2898) for radiata pine; and

Figure 4 illustrates a Fire Test Certificate (BRANZ Reference FH10105-001).

DETAILED DESCRIPTION

As noted above, described herein is an enhanced performance of wood and engineered wood products using combined durability and flame retardancy that comprises several aspects. Firstly, in the product formulation to produce a durable Flame Retardant [dFR] single phase 'working solution' for chemical impregnation. Secondly, the wood impregnation treatment process and thirdly, the heat (fixation) process which ensures that the impregnated chemicals are firmly fixed into the wood structure.

For the purposes of this specification, the term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise' and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

The term 'durable Flame Retardant [dFR] treated wood product' or grammatical variations thereof refers the combination of a durable wood (chemical) preservative and a Flame Retardant impregnated into a wood substrate. A durable Flame Retardant [dFR] treated wood product has achieved a global first in meeting the Australian Standard (AS 3959-2009 for construction of buildings in bushfire-prone areas) to withstand exposures up to BAL-29 and BAL-40 conditions (Bushfire Attack Level).

The term 'enhanced durability' or grammatical variations thereof refer to resistance to or fungal decay, rot, insect attack, such as termites and the like.

In a first aspect there is provided a process of imparting enhanced durability and fire retardancy properties to lignocellulosic material comprising:

a wood preservative;

a flame retardant [FR], consisting of alkali metal silicates and/or alkali metal aluminates that utilises an impregnation treatment process and/or spray, immersion, deluge system such that there is chemical penetration into the cellular internal voids of the lignocellulosic material which becomes insoluble (fixed) on subsequent heating steps.

The product formulations may comprise a durable component and Flame Retardant component which may combine as a single phase soluble concentrate and should be understood to be termed "working solution" for chemical (treatment) impregnation. It is in the addition of the combined Flame Retardant [FR] to the wood preservative in the form of a 'working solution' that may be then impregnated into the wood or alternatively applied in conjunction with a sprayed, immersion or deluge systems.

The durable component may comprise a range of wood preservatives both copper based and non- copper based to control fungal decay and insect (termite) attack.

The Flame Retardant [FR] component may comprise of a range of inorganic metal oxides which impart Flame retardancy via various flame retardant mechanisms during fire combustion. Also, the product formulations may be used in conjunction with Thermally Modified Timber (TMT) and may be the same product formulations as used with untreated, treated wood and engineered wood products. Also, the same product formulations may be used as working solutions for treatment impregnation are the same as may be used for spray, immersion or deluge application systems.

In the case of chemical impregnation the combined wood preservatives and flame retardants [FR] may be impregnated into the wood substrate and further undergo a heat or drying process to achieve fixation (non-leaching).

The wood impregnation treatment process may use a wide range of different treatment process schedules which impart differing performance criteria. The standard conventional wood processing treatment schedules that may be used, but not be seen as limited to; Bethel, Lowry, Reuping or modified (low uptake) processes. The inventor has found that all of these processes may be capable of potentially achieving the required wood impregnation that meets the desired standards for penetration and retention for chemical durability and fire retardancy. The inventor has found that using chemical impregnation technology has allowed the facilitation of impregnating the cell wall with a single or combination of chemicals (wood preservative plus flame retardant), which become "fixed" into the cell wall of the wood. In the case of durable Flame Retardant [dFR] treated wood products, the modification is achieved through the addition of inorganic alkali metal oxide flame retardants to a water borne chemical preservatives (approved for use in H3, H4, H5, UC3A, UC3B, UC4 and UC5) followed via a heat (fixation) process.

As above, with a durable Flame Retardant [dFR] treated wood or Flame Retardant [FR] thermally modified timber (TMT), it is the inorganic metal oxide component that may provide increased fire retardancy to the modified wood.

Without being bound by theory, there are various reaction mechanisms that may occur depending on the type of flame retardant used; for example alkali metal silicates operate whereby the liquid soluble silicate monomer may impregnate into the wood voids (cell wall - lumena) as a monomer and on heating may undergo a condensation reaction (dehydration process) whereby unbound water may polymerise to produce a longer chain polymeric flame retardant (larger molecule) species. In the case of alkali metal aluminates, these may operate whereby the liquid (hydrated) stabilised aluminate may impregnate into the wood voids and on heating may undergo a dehydration process to produce an insoluble aluminate oxide.

This same chemical impregnation technology as above may also be applied to Thermally Modified Timber (TMT), where similarly the modification is achieved through the addition of inorganic alkali metal oxide flame retardant in isolation or in combination with chemical preservatives followed via the conventional thermal modification heat process (170-230°C) to achieve chemical fixation.

The heat (fixation) process used may be required to fix the combined durable Flame Retardant [dFR] compounds into the wood or engineered wood products via a range of reaction mechanisms including but not limited to; dehydration, and/or polymerisation, etc. The heat energy sources may be; kilns, steam, hot air, and/or radio frequency.

The wood species for the above treatment process may include, but should not be seen as limited to; radiata pine, pinus elloitti (slash pine), araucaria (hoop pine), douglas fir (oregon pine), pinus carribaea (yellow pine, yellow southern pine), cedar (western red cedar).

The use of durable fire retardant [dFR] or flame retardant [FR] components can also be applied to other building construction systems requiring additional Fire Testing including; AS 5637.1:2015 & ISO 9705 (for internal Wall and Ceiling Linings), ISO 5660 (high rise buildings), AS/NZS 1530.8.1-2007 for fire testing of building materials, components and structures exposed to simulated bushfire attack e.g. BAL 40 and engineered wood products.

Technical Problem

The inventor has found to achieve a durable Flame Retardant [dFR] treated wood product, then three major areas of technical challenge must be identified and resolved.

The Product Formulations used to combine a durable (wood preservative) and a flame retardant (inorganic metal oxide) as [dFR] must achieve; solution stability (no solution phasing out, no solids deposition, low viscosity maintained, no gelification), single phase 'solution concentrate' that after repeated pressure-vacuum treatment cycles (charges) remains stable and not affected by soluble wood extractives, cellulose and lignin species.

The selection of wood preservatives used may be water based in both copper and non-copper active ingredients. The copper based wood preservatives are approved to H3, H4 and H5 hazard classes while the non-copper based are H3 approved only.

The Wood Impregnation Treatment Process may use a wide range of different treatment process schedules which impart differing performance criteria. As above, the standard conventional wood processing treatment schedules used including Bethel, Lowry, and Reuping all have inherent issues, hence the technical challenge of achieving a treatment schedule which after repeated pressure-vacuum treatment cycles (charges) remains stable and not effected by soluble wood extractives, cellulose and lignin species. The final durable Flame Retardant [dFR] treated wood must achieve the required chemical impregnation ('working solution' uptake - litres/m 3 ) that meets the required standards for penetration and retention for chemical durability and fire retardancy.

The inventor has found that the Heat (Fixation) Process and the different reaction mechanisms required to achieve chemical fixation is critically important as potentially any un-fixed chemical will be solubilised and reduce the performance of both the durable and FR components of the formulation. In the case of alkali metal silicate Flame Retardants, the smaller size monomeric state of the soluble alkali silicate on heating (110/80°C) polymerises to a larger species that is insoluble being both chemically and physically bound within the wood structure. In the case of alkali metal aluminate Flame Retardants, the soluble alkali aluminate on heating (90/70°C) undergoes dehydration process to produce an insoluble metal aluminate oxide. The heat energy sources used may be kiln drying.

Solution to Problem

The inventor has unexpectedly found that for the Product Formulation, a wide range of water based wood preservatives in combinations with varying water soluble alkali metal oxide (Silicates and

Aluminates) based flame retardants were formulated to achieve a stable homogenous durable Flame Retardant [dFR] working solutions.

Repeated (600-700) 'screening' tests of the various durable Flame Retardant [dFR] 'working solutions' were conducted using a "Venturi - Filtration Apparatus". This apparatus may create a vacuum filtration - 70 to-80kpa), whereby the working solutions are passed through a l-5micron (Qualitative Grade 1. Filter Paper), where the filtrate rates (measured in seconds /lOOmls) of the treated flame retardant solutions are measured against the treated wood preservative (control) solutions. While this method may not replicate the wood impregnation process it provides an excellent method for 'pre-screening' the durable Flame Retardant [dFR] working solutions. Stability was measured using temperature (ambient to refrigerated, 30°C to +3°C) , viscosity (digital viscometer), specific gravity (hydrometer), solids deposition (via filtration), colour change (visual), agitated and non-agitated over time (4-6 months). Once these working solution met all of the require working solubility criteria, they were taken to the next stage of wood impregnation process via a treatment plant.

For the Wood Impregnation Treatment Process semi-commercial scale treatment plants were used at SCION (Rotorua, NZ) and Koppers Performance Chemicals (Wiri, NZ). Chemical treatment could be carried out on long boards of 2.4 metre length, 150mm wide, and 18 to 45mm thickness covering virtually all commercial size products. Using the 'full cell' Bethel cycles during treatment impregnation process were able achieve uptakes ranging from 550 to 800L/m 3 . However, uptake control in commercial plants is readily controllable, as these semi-commercial plant operate to time/volume. After treatment the returned working solution was tested for stability, viscosity, colour, solids, etc., and any other quality issues that may result from any potential "kickback" attributed to soluble wood extractives, cellulose and lignin species, however, there were none. Many repeated treatment charges were undertaken. Durable Flame Retardant [dFR] samples were tested for compliance with chemical penetration (for both wood preservative and flame retardant) and retention (for copper based wood preservatives only).

The Heat (fixation) Process used Heating Kilns (both large cross-flow and long horizontal kilns) to dry products on a semi-commercial scale at SCION (Rotorua, NZ). The board drying dimensions being; 2.4 metre length, 100-150mm wide, and 18-45mm thickness covering virtually all commercial sizes used. In the case of alkali metal silicate Flame Retardants a heating temperature (110/80°C) was used to polymerise and increase the molecular size whereby ensuring fixation has occurred resulting in non- leachable durable Flame Retardant [dFR] treated wood product. In the case of alkali metal aluminate Flame Retardants the soluble alkali aluminate on heating (90/70°C) undergoes dehydration process to produce an insoluble metal aluminate oxide resulting in non-leachable durable Flame Retardant [dFR] treated wood product. The heat energy sources used are kiln drying.

The following below describes some preferred embodiments of the invention, in relationship to the durable Flame Retardant [dFR] product formulation, wood impregnation treatment process, heat (fixation) process and other applications of spray, immersion or deluge system to provide enhanced durability and flame retardancy performance of wood and engineered wood products. This invention is in no way limited to these embodiments as they are purely to exemplify the invention only and that possible variations and modifications would be readily apparent without departing from the scope of the invention.

The durable Flame Retardant [dFR] product formulation may consist of a durable component and a Flame Retardant [FR] component which may combine to produce a single combined formulation that is further impregnated into the wood and fixed via heat process producing a durable Flame Retardant [dFR] treated wood product.

The wood impregnation treatment process steps may further comprise:

a) Timber is loaded into the wood treatment chamber (can be cylindrical or square vessel), then sealed shut;

b) The chamber is then flooded under vacuum (-85kPa) with the various 'working solutions', whereby allowing absorption (chemical uptake, Litres/m 3 ) to occur;

c) Depending on the treatment process used i.e. Bethel, Lowry, Reuping or modified

processes, then various pressures (1300-1500kpa) and vacuum (-85pka) cycles are applied for 30 to 180 minutes in order to achieve a targeted 'working solution' uptake varying from

400 to 800 litres per m 3 ; and

d) Once the timber has been fully impregnated with the required amount of durable Flame Retardant [dFR], then it progresses to the next Heat (fixation) processing stage.

It should be appreciated by those skilled in the art that the operating parameters stated above are indicative only, and the full range of these operating parameters are outlined further below.

With regard to the Heat (fixation) process, once the treated flame retardant 'working solution' has been impregnated into the wood (via treatment process), then the wood may undergo a heat (fixation) treatment process based on time/temperature schedule. The time/temperature schedule is based on a time range of 24 to 84 hours and a temperature range (input/output) of 130 to 60°C. The

time/temperature range parameters are very critical to optimise chemical fixation and not impair wood strength. To evaluate and quantify the effectiveness of chemical fixation process, leachability tests (Leaching Test EN 84 Method) were conducted on both the wood preservative (dissolved Copper Azole - dCA) and Flame Retardant (alkali metal silicate). The depletion rate results are outlined in later Examples. Alkali metal aluminates chemical fixation was measured by chemical retentions calculated after post- weathering trials (ASTM D2898 method B) and for Flame Retardant measured by the actual burn test carried out (AS/NZS3837).

In a second aspect there is provided a lignocellulosic material product produced by the process of imparting enhanced durability and fire retardancy properties the lignocellulosic material comprising: a wood preservative; and

a flame retardant [FR], consisting of alkali metal silicates and/or alkali metal aluminates that utilises an impregnation treatment process and/or spray, immersion, deluge system such that there is chemical penetration into the cellular internal voids of the lignocellulosic material wh ich becomes insoluble (fixed) on subsequent heating steps.

In the case of chemical impregnation of durable Flame Retardant [dFR] or just a Flame Retardant [FR] to Thermally Modified Timber [TMT]. After chemical impregnation the [dFR] or [FR] products are placed into a specific 'thermal modification heat kiln' where via a series of process steps reaches an elevated temperature of at least 190°C and up to 250°C at which point thermal modification has occurred. The final product being durable Flame Retardant Thermally modified Timber [dFR-TMT] and Flame Retardant Thermally Modified Timber [FR-TMT].

The embodiments described above 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.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as of individually set forth.

WORKING EXAMPLES

The above described enhanced performance of wood and engineered wood products (EWP) using varying combinations of wood preservatives (durability) and flame retardants [FR] are now described by reference to specific examples. EXA M P LE 1

Durable Flame Retardant Chemical formulation

The durable Flame Retardant [dFR] product formulation consists of a durable component and a Flame Retardant [FR] component which combine to produce a single phase formulation called "working solution" that is further impregnated into the wood and fixed via heat process producing a durable Flame Retardant [dFR] treated wood product. The durable and Flame Retardant components are outlined in below, as is Example 1 and 2 of product formulations.

The durable Flame Retardant chemical formulation comprises:

1. Durable component comprising of a range of wood preservatives used in the control of fungal decay, mould and insect attack (termites) attack. The range of wood preservatives extends to both copper and non-copper based formulations, the copper based formulations include; - Copper Chrome Arsenate (CCA), dissolved Copper Azoles (dCA), micronized Copper Azoles (mCA), Alkaline Copper Quaternary (ACQ), micronized Copper Quaternary (mCQ) and the non-copper based formulations include; water based azoles, tri-azoles including; propiconazole, tebuconazole, cyproconazole and carbamates including;

iodopropynyl Butyl Carbamate (IPBC).

2. Flame retardant component comprising of a range of inorganic metal oxides which impart flame retardancy via differing flame retardant mechanisms during combustion (fire burning). The range of inorganic metal oxides includes soluble alkali metal silicates, such as sodium silicate (ortho, meta, di and tri-silicates), potassium silicate, lithium silicate and soluble alkali aluminates including sodium aluminate and potassium aluminate. The range of Flame Retardant [FR] inorganic metal oxides also extends to aluminium oxide nano- particles (dispersions), aluminium silicate nano-particles (dispersions) and silicon dioxide nano-particle dispersions.

To best understand the principles of the invention, the following additional working example are provided for illustrative purposes only.

EXAMPLE 1A. Copper based (durable) Flame Retardant Formulation

28g of sodium aluminate [Na 2 AI 2 0 4 ] is dissolved in a solution of 3g of sodium gluconate (salt of gluconic acid) and 75g of water to produce a clear and stabilised liquid sodium aluminate solution. Then 2g dissolved copper azole (9%m/m - Copper, 0.5%m/m - azole) is added to the stabilised sodium aluminate solution to produce a durable Flame Retardant chemical formulation (working solution), as further outlined in Table 1. below: Table 1. Example of a durable Flame Retardant (working solution) below:

* Stabiliser agent is salt of gluconic acid (sodium gluconate)

EXAMPLE IB. Non-Copper based (durable) Flame Retardant Formulation

12.5g of soluble sodium silicate [40% - Na 2 Si0 3 ] is dissolved in a solution of 2g of water based azoles (Aquazole - PTPm) and 75g of water to produce a milky coloured emulsion. The durable Flame Retardant chemical formulation (working solution), as further outlined in Table 2. below:

Table 2. Example of a durable Flame Retardant (working solution) below:

* Aquazole [PTPm] :10%Propiconazole-[P],10%Tebuconazole-[T],5%Permethrin[Pm]

3. The use of aluminium oxide [Al 2 0 3 ] nano-particles (dispersions), aluminium silicate

[AI 2 03.Si0 2 ] nano-particles (dispersions) and silicon dioxide [Si0 2 ] nano-particle dispersions as flame retardants components in both water and solvent systems. The nano-particle dispersions are suspensions of aluminium oxide [Al 2 0 3 ], aluminium silicate [AI 2 0 3 .SiO 2 ] and silicon dioxide [Si0 2 ] in water or in various organic solvents such as ethanol or mineral oil and typically range in size of 10-200nm (nano-metres). The range of organic solvents that can be used with these nano-particle dispersions includes; ethanol, mineral oils and others including high and low aromatic hydrocarbons and glycols (ethylene and propylene).

4. The use of durable fire retardant [dFR] or flame retardant [FR] components in resin systems such as glue-line additives (GLA), laminates or compressed. Phenolic resins include; phenol formaldehyde, urea formaldehyde, resorcinol, melamine urea formaldehyde. Resin system applications include; plywood, bamboo (laminated and compressed), particle board and Laminated Veneer Lumber (LVL).

EXAM PLE 2

Wood Impregnation Treatment Process

The preservative treatment of wood by pressure methods is the preferred commercial approach as it achieves greater efficiency in controlling the conditions and effectiveness in terms of achieving more uniform, deeper penetration and greater absorption of the working solution. The treatment plant has a door either at one or both ends to receive the untreated wood (charge), which is then loaded into the vessel ready for the treatment to occur. The plant has various accessory equipment in known fashion such as working tanks, flood lines, controls, vacuum and pressure pumps to deliver the various treating schedules.

There are two types of treatment pressure methods; firstly "empty cell process" where compressed air is applied to the timber prior to the wood preservative "working solution" is applied. The wood preservative is added to the vessel from an equalising tank where the air interchanges with the preservative. By trapping the air in the cells and releasing the pressure after treatment, the trapped air expands and forces the preservative out, with a final vacuum to remove any further solution. This process leaves no preservative in cell lumens and recovers much of the preservative used.

The 'full cell process" uses an initial vacuum removing much of air from the cells, thereby removing the air cushion which resists preservative penetration. This process achieves the maximum retention of the chemical preservative in the treatment of the wood.

There is also "modified full-cell process" which is basically the same as the "full-cell process" except that it uses lower levels of initial vacuum and often uses an extended final vacuum. Modified full-cell process is the most commonly used method of treating wood with waterborne preservatives.

In wood treatment being 'Fit for Purpose' is critical and the various hazard classes or user categories (H3, H4, H5, or UC3B, UC4B) must meet compliance through penetration and retention. Both penetration and retention are a function of the treatment process, hence the importance of the correct treatment schedule for the appropriate wood species, grade and size.

The treatment carried out using the durable Flame Retardant [dCA] can be achieved via 'full cell process', 'modified full cell process' and 'low uptake process' to achieve compliance in terms of penetration and retention. To achieve the required durability loading (for H3 dCA) and sufficient loading of Flame Retardancy [FR - kg/m 3 ] needed to meet the heat testing criteria specified by the Australian Bushfire Standard (AS3959-2009) and the USA 'Spread of Flames' testing requirements. Using non-structural grade (decking) and structural (mgp-10) grade (bearers) radiata pine, which is fully impregnated using a 'full cell process' generates the following chemical uptakes (of working solution) and retentions for both copper [H3ca] and Flame Retardant [FR] as outlined in Table 3:

Table 3

Impregnation Treatment data for chemical treatment using durable Flame Retardant [dFR - H3ca metal aluminate] working solution and showing Chemical Uptake (L/m 3 ) and Retention (kg/m 3 )

Based on these chemical uptakes (L/m 3 ) for both the 22mm and 45mm thickness all of the durable component - dissolved Copper Azole [dCA] for H3 hazard class meets the required retention of l. lkg/m 3 (equivalently if based on a wood density range of 440 to 480kg/m 3 the retention becomes 0.025% to 0.023%m/m Copper). Using lower uptake processes the durable Flame Retardant [dFR] 'working solution' increases to achieve similar or higher retentions as required. Similarly the uptakes for the Flame Retardant [FR] in this case an alkali metal oxide can be increased to meet the required Flame

Retardancy. Also higher durable component hazard classes can be used i.e. H4 and H5, whereby increased loadings in the case of soluble copper azole, the loading of H4 increases to 2.0kg/m 3

(0.42%m/m-Cu), H5 increases to 3.6kg/m 3 (0.76%m/m-Cu), however the FR loadings remain the same. EXAM PLE 3

Heat (Fixation) Process

Once the treated flame retardant timber has been treated it has a high moisture content (%mc) in the range 60-200% which requires drying to bring it below 18%mc for resale. It is in the drying process where various kiln schedules are used in the control of temperature (set points), air flow (fans) and relative humidity at pre-determined times. The kiln schedules require temperature range for inlet temperature (wet bulb) to be 60-90°C and the outlet temperature (dry bulb) to be 90-130°C. The time/temperature schedule is based on a time range of 24 to 84 hours and a temperature range (input/output) of 130 to 60°C. The time/temperature range parameters are very critical to optimise chemical fixation and not impair wood strength. Other heat sources can potentially be used like steaming, radio frequency and microwave technology.

In the case of durable Flame Retardant [dFR] - alkali metal silicates [FR] the heat (fixation) process achieves two important processes in firstly reducing the moisture content (<18%mc) and secondly provides the energy to activate the condensation reaction mechanism (dehydration process) whereby the unbounded water molecules in the flame retardant (silicate ions) undergo polymerisation (or partial polymerisation) to produce a larger and bound molecules within the wood cells. The fixation process is supported and validated by the leaching test (Leaching Test EN 84 Method) for both the soluble copper azole and flame retardant (alkali metal silicates), as outlined in Table 4 and 5.

In the case of durable Flame Retardant [dFR] - alkali metal aluminates [FR] the heat (fixation) process (90/70°C) similarly achieves two important processes in firstly reducing the moisture content (<18%mc) and secondly undergoes dehydration process to produce an insoluble metal aluminate oxide resulting in non-leachable durable Flame Retardant [dFR] treated wood product. The fixation process of alkali metal aluminates is supported and validated by chemical retentions calculated after post-weathering trials (ASTM D2898 method B) and for Flame Retardant measured by the actual burn test carried out (AS/NZS3837), refer to Table 6.

To evaluate and quantify the effectiveness of chemical fixation process, leachability tests (Leaching Test EN 84 Method) were conducted on both the wood preservative (dissolved Copper Azole - dCA) and Flame Retardant (alkali metal silicate). The depletion rate results are outlined in Example 3. Heat (Fixation) process Tables 4 and 5. Alkali metal aluminates chemical fixation was measured by chemical retentions calculated after post-weathering trials (ASTM D2898 method B) and for Flame Retardant measured by the actual burn test carried out (AS/NZS3837), refer Table 6. Table 4

Leaching (Fixation): durable Flame Retardant [dFR] with alkali metal silicate shows Copper (wood preservative, pCu) Loss (depletion) Rate from leaching test method EN84 for radiata pine.

The leaching (leachate solutions) results (samples 4, 6, 14) for copper in the durable Flame Retardant (for alkali metal silicates) gives an average gradient drop-off rates of 24% at day 1 (0.48%) to day 8 (0.36%) and 55% drop-off from day 8 (0.36%) to day 14 (0.16%). This copper [Cu] depletion rate is well within an acceptable level to maintain wood durability for the required hazard classes.

The fixation process for treated wood preservatives such as these copper based fungicides is well documented.

Table 5

Leaching (Fixation): Flame Retardant (FR) Loss Rate (leaching test method EN84) for radiata pine.

The leaching (leachate solutions) results (samples 4, 6, 14) for Flame Retardant [FR] (for alkali metal silicates) gives an average gradient drop-off rates of 33% at day 1 (1.5%) to day 8 (1.0%) and 17% dropoff from day 8 (1.0%) to day 14 (0.83%). This Flame Retardant [FR] depletion rate is well within an acceptable level to maintain a high level of Flame Retardancy required to contain fire combustion.

LEACHING TEST EN84 METHOD. Leaching Test samples were conditioned in the same way as it had been done before impregnation (65% RH and 20°C till equilibrium moisture content). Leaching was done according to EN84. Samples were covered with deionized water in an amount of approximately five times the volume of the sample and placed in the impregnation vessel. Samples were held in 0.04 bar of vacuum for 20 min. After vacuum, the samples stayed in the water for 2 hr before the water was changed for the first time. Specimens were submersed in deionized water for 14 days. From every sample's vessel, 5 ml of leaching water was collected, combined and submitted for chemical analyses. Water changes and collecting of water samples were done ten times.

Table 6 Post - Weathering Chemical Retentions - Copper [Cu] and Flame Retardants [FR] for Alkali Metal Aluminates

*Australian Standard AS1604.1-2012 for Penetration and Retentions

Leaching (Fixation): The chemical leaching results were achieved after the accelerated weathering tests [this is in accordance with AS 3959-2009, accelerated weathering test method ASTM D2898 method B, with water flow rate modified to ASTM D2898 Method A]. The Post - Weathering Chemical Retentions for Copper [Cu] and Flame Retardant [FR - alkali metal aluminate] - refer to Table 6.

The copper [Cu] and Flame Retardant [RF] retentions post-weathering achieve the targeted retention levels for copper [H3] and the Flame Retardant [FR] retentions as those required to meet the subsequent burn tests [AS/NZS 3837] required under the Australian Bushfire test in accordance with AS 3959 for construction in bushfi re-prone areas to withstand exposures up to BAL-29 condition. Refer to Figure 4 - Fire Test Certificate (FH10105-001). The Fire Test Certificate is a global first for achieving a pass for the use of a "Durable Flame Retardant [FR] treated wood product".

Reaction Mechanisms - Alkali Metal Aluminates and Alkali Metal Silicates

Alkali Metal Aluminates:

Example: Na 2 AI 2 0 4 (solid)

or hydrated as soluble 2NaAI(OH) 4 + heat (90/70°C) = Al 2 0 3 (insoluble) + Na 2 0

Alkali Metal Silicates:

Example: Na 2 Si0 3 (solid)

or hydrated as soluble Na 2 0:Si0 2 + heat (120/80°C) = Si0 2 (insoluble) + Na 2 0

EXAM PLE 4

Heat Release Rate (HRR)

Under the Australian Bushfire Standard AS 3959-2009 - for construction of buildings in bushfi re-prone areas, it specifies the following:

Appendix F for Bushfire-Resisting Timber (Normative)

Fl GEN ERAL - Bushfi re-resisting timber that is solid, laminated or reconstituted form and is deemed to be acceptable to withstand exposure up to BAL-29 condition. Timber may be 'bushfire-resisting' by means of one or more of - (a) the inherent properties of the material itself; (b) being impregnated with fire-retardant chemicals; or (c) the application of fire-resistant coatings or substrates.

F2 TESTI NG The following applies: (a) to satisfy the requirements for bushfire-resisting timber, timber shall be tested in accordance with AS/NZS 3837 and shall meet the following criteria:

(i) the maximum heat release rate shall be not greater than 100 kW/m 2

(ii) the average heat release rate for 10 min. following ignition shall be not greater than 60 kW/m 2 when the material is exposed to an irradiance level of 25 kW/m 2 .

F3 ACCELERATED WEATHERI NG Where accelerated weathering is required before testing to AS/NZS 3837, external fire-retardant-coated substrates shall be subjected to the ASTM D2898 Method B weathering regime, with the water flow rate modified to be the same as that within ASTM D2898 Method A.

The key determinant to meet the Australian Bushfire Standard (AS3959) is achieving the required peak Heat Release Rate (HRR) and average HRR values as outlined under Appendix F. Heat release rate (HRR) is the rate of heat generation by fire, measured typically kW/m 2 . The cone calorimeter (located at Branz) will evaluate fire performance properties such as heat release rate (HRR), fire degradation, time to ignition (Tg), mass loss rate (MLR) and smoke (SEA) Smoke Extinction Area that calculates the extent of smoke generated during combustion.

5 Table 7 - Heat Release Rate (HRR) and Mass loss (MLR): for durable Flame Retardant [dFR] alkali metal aluminates [FH6239-25-1/2/3] versus Untreated radiata pine samples [FH5777-25-2/3] - also refer Figures 1, 2 and 3.

Time FH623 FH6239-25-2 FH6239-25-3 FH577: '-25-2 FH5777 -25-3 (s) HRR MASS HRR MASS HRR MASS HRR MASS HRR MASS

190 81.4 101.41 88.61 95.05 52.21 82.65 71.63 198.92 88.63 74.84

200 77.48 100.66 77.69 94.10 48.47 82.13 67.33 198.44 85.63 74.21

210 71.13 99.93 70.96 93.50 44.26 81.67 64.65 197.95 82.13 73.62

220 67.80 99.24 66.39 93.08 39.68 81.28 63.01 197.49 77.20 72.99

230 59.87 98.65 62.11 92.08 35.75 80.88 61.66 197.10 74.12 72.42

240 52.86 98.04 57.95 91.43 30.29 80.46 60.82 196.61 73.32 71.88

250 49.32 97.50 54.83 90.99 24.72 79.73 58.80 196.20 70.26 71.34

260 47.65 96.93 51.67 90.76 20.05 79.36 59.57 195.72 66.72 70.79

270 46.48 96.39 46.01 89.89 20.69 78.96 57.31 195.29 62.91 70.22

280 41.57 95.87 45.24 89.34 23.36 78.74 58.29 194.87 62.01 69.75

290 39.79 95.30 43.37 88.71 23.35 78.28 58.58 194.40 60.48 69.20

300 36.51 94.85 37.23 88.33 21.18 77.49 56.35 193.98 57.58 68.64

310 33.42 94.32 34.46 87.52 22.90 77.01 57.58 193.55 54.65 68.10

320 30.08 93.88 33.02 87.30 22.86 76.96 57.44 193.09 53.86 67.58

330 27.53 93.38 27.75 86.51 23.04 76.39 57.01 192.76 52.40 67.08

340 26.35 92.90 20.94 86.28 22.61 76.04 57.21 192.24 50.51 66.59

350 24.03 92.45 21.68 85.61 22.30 75.44 57.09 191.82 49.34 66.09

360 20.58 91.92 21.84 85.16 23.99 74.95 55.57 191.41 46.59 65.53

370 22.37 91.43 21.93 84.68 20.70 74.31 54.75 190.97 48.82 65.07

380 22.38 91.02 21.72 84.08 22.93 73.82 55.36 190.58 48.22 64.56

390 20.65 90.50 22.24 83.64 22.96 73.40 55.56 190.18 47.63 64.07

400 19.40 90.05 21.16 83.29 23.68 72.91 54.06 189.73 46.70 63.57

410 20.19 89.56 21.93 82.64 24.18 72.65 54.59 189.29 44.28 63.10

420 18.58 89.07 21.48 82.15 25.66 72.36 54.01 188.90 43.27 62.59

430 21.09 88.60 21.82 81.72 24.41 71.91 53.96 188.48 44.76 62.18 Time FH623 FH6239-25-2 FH6239-25-3 FH577: '-25-2 FH5777 -25-3 (s) HRR MASS HRR MASS HRR MASS HRR MASS HRR MASS

440 21.05 88.13 24.08 81.15 26.08 71.42 53.82 188.04 44.96 61.68

450 20.10 87.63 23.65 80.79 24.05 71.02 52.49 187.65 44.16 61.18

460 20.69 87.17 22.29 80.36 24.92 70.55 53.42 187.23 44.40 60.70

470 19.90 86.73 22.68 79.71 24.90 70.15 52.66 186.78 44.37 60.27

480 19.15 86.20 22.43 79.24 24.07 69.73 52.64 186.40 44.52 59.79

490 18.52 85.75 22.55 78.75 24.09 68.99 51.81 185.98 43.09 59.30

500 21.66 85.25 23.12 78.37 23.36 68.81 52.32 185.57 43.99 58.84

510 20.96 84.81 23.91 77.74 23.52 68.40 52.06 185.09 43.29 58.42

520 20.01 84.33 25.04 77.16 23.92 67.82 50.61 184.73 44.21 57.94

530 21.08 83.89 24.84 76.84 25.18 67.28 52.22 184.34 44.05 57.46

540 19.04 83.42 25.87 76.28 23.90 67.13 51.38 183.89 42.91 56.96

550 18.67 82.96 24.63 75.51 23.92 66.52 50.09 183.52 46.06 56.54

560 18.32 82.53 24.91 75.17 23.02 66.07 52.55 183.08 45.59 56.07

570 21.20 82.01 24.59 74.90 23.83 65.89 50.04 182.64 43.58 55.63

580 20.05 81.61 23.26 74.35 25.23 65.48 52.18 182.24 43.81 55.19

590 21.52 81.12 23.91 73.89 25.11 64.84 51.71 181.84 46.98 54.70

600 21.22 80.69 24.82 73.27 24.36 64.60 52.93 181.39 46.26 54.22

Table 8. Test Results

The Test Results from HRR (peak and average) and Flame Duration times

*peak and average HRR test results all pass.

The peak and average H RR test results post weathering and after the burn test pass the required HRR values of less than 100 kW/m 2 (for peak HRR) and less than 60 kW/m 2 (for average HRR) as outlined under the Australian Bushfire Standard (AS3959) Appendix F for bushfire-resisting timber.

The achievement of meeting the Bushfire Standard for exposure BAL-29, is the first time that a flame retardant wood product has achieved this milestone let alone a durable Flame Retardant [dFR] treated wood product achieving this milestone.

The HRR heat curves showing the peak and average HRR values over 1800 sec (30 min.) is outlined in

Figure 1. Heat Release Rate (H RR): durable Flame Retardant [dFR] treated wood samples (FH6239-15-25- 1/2/3) after Post-Weathering Test (ASTM D2898 Method B modified) and Burn Test AS/NZS 3837. (Refer to Fire Test Certificate - Figure 4)

The HRR heat curves showing the peak and average HRR values over 600 sec (10 min.) versus untreated wood is outlined in Figure 2. Heat Release Rate (HRR): durable Flame Retardant treated wood samples (FH6239-15-25-1/2/3) after Post-Weathering versus Untreated wood samples for radiata pine - Figure 2.

Burn Test - AS/NZS 3837 (cone calorimeter).

The post-weathering burn test is the most important of all the tests as it establishes the 2 key determinate peak and average HRR values that MUST be less than 100Kw/m 2 (for peak H RR) and less than 60 kW/m 2 (for average H RR). All three results must be within a 10% arithmetic mean variance. The Time to Ignition (Tg) less the Flameout time gives the Flame duration which must be greater than 60 seconds otherwise the igniter is re-inserted.

Flame Retardant [FR] Reaction (Rx) Mechanism

The cone calorimeter test (AS/NZS 3837) used to measure combustion (HRR, Tg, SEA, etc.,) for the various Flame Retardants impregnated into the wood, operates via varying Reaction (Rx) mechanisms. The main operating modes of action being; providing heat insulation to the wood, absorb the surrounding heat or increase the thermal conductivity of wood in order to dissipate the heat from the wood surface.

The alkali metal silicates [FR] on combustion follows a 'ceramification' reaction mechanism, whereby it creates an insulating blanket which at higher temperatures provides a radiation shield, delaying the volatilisation of the pyrolysis products and preventing heat from recirculating back into the wood. The alkali metal silicates have a high heat capacity ('ceramification') to contain heat within the wood substrate, however, as the heat builds up (at the higher temperatures) it gets to point at which energy (heat) is rapidly released producing elevated peak HRR values. After the peak HRR is reached there is a rapid decline in HRR, producing a low average HRR value.

The alkali metal aluminates [FR] on combustion follows a 'hydration' reaction mechanism, whereby hydrated soluble form alkali metal aluminate (e.g. 2NaAI(OH) 4 ) acts as a chemical heat sink for the wood for the wood by absorbing some of the heat of combustion and lowering the temperature near the flame during endothermic decomposition and as a result, the wood is cooled and the time to ignition (Tg) is increased. The water vapour released from the hydrated alkali metal aluminate has the effect of diluting the combustion gases and toxic fumes. The decomposition endothermically releases 35% of its weight as water vapour which condenses (hydration process) and in process reduces the oxygen content of 21% down to 13%. The relationship of increasing the concentration of alkali metal aluminate via the hydration process directly reduces both peak HRR and the average HRR values. EXAM PLE 5

Mass Loss Rate (MLR)

The thermal decomposition behaviour of the mass loss and mass loss rate (MLR) reflects the combustion process and is related to the heat release (H RR) and smoke level generated (SEA). The first stage of mass loss curve is due to the elimination of moisture from the wood, while the second stage (charring) of thermal decomposition process mostly involves combustion of major wood components, including cellulose, hemicellulose and lignin. In achieving a successful pass during the cone calorimeter tests (AS/NZS 3837), the mass loss over the flame duration must exceed 150g/s.m 2 over 60 seconds - refer to Table 9 below:

Table 9: Mass Loss (calc.) over the flame duration for the durable Flame Retardant [dFR] treated wood samples (FH6239-15-25- 1/2/3).

EXAM PLE 6

Smoke Specific Extinction Area (SEA)

A convenient and basic measurement of smoke produced by a given material (e.g. wood) is the Smoke (Specific) Extinction Area (SEA), measured in m 2 /kg. The relationship between heat release rate (HRR) and Smoke Extinction Area (SEA) is very important when relating to the influence and survival of humans (human safety) in a fire. With the Australian Bushfire Standard (AS 3959-2009) smoke generation is not a criteria for the success, however, with Forest Fires (USA) the smoke generation (measured) is a key criteria to meeting the fire standards. Included in this specification is reference to smoke generation (SEA) and the findings of durable Flame Retardant treated wood products versus untreated wood products.

The SEA value for untreated wood (radiata pine) has an average SEA value of 60m 2 /kg compared to durable Flame Retardant [dFR] treated woods that have much lower average SEA values ranging from 1.4, 3.5, 12.0 (average 5.6m 2 /kg). Table 10 shows the impact of the Flame Retardant [FR] component within the durable Flame Retardant treated wood having a significant impact in not only lowering the heat release rate values, but also reducing the smoke release properties (SEA).

Table 10

Smoke (Specific) Extinction Area (SEA): durable Frame Retardant [dFR] treated wood products versus untreated wood (radiata pine).

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.