EP3900902B1 - Minéralisation du bois ou de matériau en bois à l'aide d'acétate de calcium - Google Patents
Minéralisation du bois ou de matériau en bois à l'aide d'acétate de calcium Download PDFInfo
- Publication number
- EP3900902B1 EP3900902B1 EP21169977.2A EP21169977A EP3900902B1 EP 3900902 B1 EP3900902 B1 EP 3900902B1 EP 21169977 A EP21169977 A EP 21169977A EP 3900902 B1 EP3900902 B1 EP 3900902B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- wood
- wooden material
- impregnation
- mineralized
- calcium acetate
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000002023 wood Substances 0.000 title claims description 106
- 239000000463 material Substances 0.000 title claims description 83
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 title claims description 21
- 239000001639 calcium acetate Substances 0.000 title claims description 21
- 235000011092 calcium acetate Nutrition 0.000 title claims description 21
- 229960005147 calcium acetate Drugs 0.000 title claims description 20
- 230000001089 mineralizing effect Effects 0.000 title claims description 3
- 238000000034 method Methods 0.000 claims description 41
- 238000005470 impregnation Methods 0.000 claims description 24
- 238000001035 drying Methods 0.000 claims description 19
- IRXRGVFLQOSHOH-UHFFFAOYSA-L dipotassium;oxalate Chemical compound [K+].[K+].[O-]C(=O)C([O-])=O IRXRGVFLQOSHOH-UHFFFAOYSA-L 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 12
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 241000219492 Quercus Species 0.000 description 27
- 241000208140 Acer Species 0.000 description 17
- 229910001868 water Inorganic materials 0.000 description 17
- 240000000731 Fagus sylvatica Species 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 235000010099 Fagus sylvatica Nutrition 0.000 description 14
- QXDMQSPYEZFLGF-UHFFFAOYSA-L calcium oxalate Chemical compound [Ca+2].[O-]C(=O)C([O-])=O QXDMQSPYEZFLGF-UHFFFAOYSA-L 0.000 description 12
- 230000033558 biomineral tissue development Effects 0.000 description 11
- 150000003839 salts Chemical class 0.000 description 11
- 230000008961 swelling Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- 239000011121 hardwood Substances 0.000 description 8
- 238000012545 processing Methods 0.000 description 7
- 239000011575 calcium Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 6
- 238000002411 thermogravimetry Methods 0.000 description 6
- 240000009089 Quercus robur Species 0.000 description 5
- 235000011471 Quercus robur Nutrition 0.000 description 5
- 239000000835 fiber Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 4
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 210000004027 cell Anatomy 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- -1 halogen ions Chemical class 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- 241000218922 Magnoliophyta Species 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 230000009970 fire resistant effect Effects 0.000 description 3
- 239000003063 flame retardant Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 235000011056 potassium acetate Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 231100000331 toxic Toxicity 0.000 description 3
- 230000002588 toxic effect Effects 0.000 description 3
- 235000004994 Fagus sylvatica subsp sylvatica Nutrition 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- XQKKWWCELHKGKB-UHFFFAOYSA-L calcium acetate monohydrate Chemical compound O.[Ca+2].CC([O-])=O.CC([O-])=O XQKKWWCELHKGKB-UHFFFAOYSA-L 0.000 description 2
- 229940067460 calcium acetate monohydrate Drugs 0.000 description 2
- 210000002421 cell wall Anatomy 0.000 description 2
- 230000001143 conditioned effect Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 235000021388 linseed oil Nutrition 0.000 description 2
- 239000000944 linseed oil Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 150000004682 monohydrates Chemical class 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 231100000167 toxic agent Toxicity 0.000 description 2
- 239000010876 untreated wood Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 101100509468 Arabidopsis thaliana JASON gene Proteins 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 206010063601 Exposure to extreme temperature Diseases 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 description 1
- 241000446313 Lamella Species 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 241000218657 Picea Species 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229920003180 amino resin Polymers 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- QCPTVXCMROGZOL-UHFFFAOYSA-L dipotassium;oxalate;hydrate Chemical compound O.[K+].[K+].[O-]C(=O)C([O-])=O QCPTVXCMROGZOL-UHFFFAOYSA-L 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009408 flooring Methods 0.000 description 1
- 235000013373 food additive Nutrition 0.000 description 1
- 239000002778 food additive Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920001864 tannin Polymers 0.000 description 1
- 239000001648 tannin Substances 0.000 description 1
- 235000018553 tannin Nutrition 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 230000004584 weight gain Effects 0.000 description 1
- 235000019786 weight gain Nutrition 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
- B27K3/02—Processes; Apparatus
- B27K3/0207—Pretreatment of wood before impregnation
- B27K3/0214—Drying
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
- B27K3/02—Processes; Apparatus
- B27K3/0278—Processes; Apparatus involving an additional treatment during or after impregnation
- B27K3/0292—Processes; Apparatus involving an additional treatment during or after impregnation for improving fixation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
- B27K3/34—Organic impregnating agents
- B27K3/36—Aliphatic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K2240/00—Purpose of the treatment
- B27K2240/30—Fireproofing
Definitions
- the invention relates to a method for producing a mineralized wood or mineralized wooden material.
- fire resistance of wood or wooden material is of high importance. Accordingly, different processes have been developed to render wood or wooden material more fire resistant. These processes rely on substances which result in delayed ignition, reduced heat release rate and slower spread of flames. They act on different levels, most of the time combined: promotion of char formation at lower temperature than wood usually degrades, free-radicals trapping in the flame, dilution of combustible gases coming from wood with non-combustible gases, reduction of heat content of the volatile gases, or coating protection of the wood surface. The most commonly used fire retardants for wood products are inorganic salts, of which some can absorb moisture promoting decay and destruction of metal joints.
- Intumescent coatings are easier to apply and less costly but their susceptibility to cracks, abrasion and wear results in the loss of efficiency.
- Methods for treating wood are disclosed in WO 2018/065335 , GB 244 178 and in KRAMB JASON ET AL: "Modeling of the catalytic effects of potassium and calcium on spruce wood gasification in CO2 ".
- a further disadvantage of wood or wooden materials containing additives to increase fire resistance are the adverse effects of the additives, such as salt deposits, on subsequent steps involving further processing of the wood or wooden material.
- processing of wood or wooden material containing such additives with a circular saw may lead to corrosion on the circular saw or other instruments involved in processing of the wood or wooden material as a result of the additives, including salt deposits.
- certain process for increasing fire resistance and/or for protecting the wood employ toxic components or precursors. which may be transformed into toxic compounds upon exposure to extreme temperatures.
- the general objective of the present invention to advance the state of the art with respect to wood protection.
- the disadvantages of the prior art are overcome fully or partly.
- an environmentally friendly and non-toxic method to improve the fire resistance of wood and wooden materials is provided.
- This new method ideally also minimizes undesired swelling of the wood or wooden material upon treatment.
- the new method would ideally lead to minimal changes in the coloration of the wood or wooden material, including after subsequent surface coating using common surface coating agents such as linseed oil.
- toxic components and/or the generation of toxic compounds, particularly under extreme temperatures such as in a fire are avoided.
- the invention aims at providing a method for the protection of wood and wooden materials by mineralization.
- This method relies on water soluble reactants penetrating the material in a stepwise fashion and reacting with each other to form water insoluble salts.
- These salts often present in crystalline form, are generated in situ within the cells themselves, in the cell walls, in the pits and in the middle lamellas.
- the general objective is achieved in a first aspect of the invention by a method comprising (i) a first impregnation step, comprising a first impregnation of wood or wooden material with an aqueous solution of potassium oxalate, (ii) a first drying step, comprising drying of the wood or wooden material, (iii) a second impregnation step, comprising a second impregnation of wood or wooden material with an aqueous solution of calcium acetate, (iv) and a second drying step, comprising drying of the wood or wooden material.
- a first impregnation step comprising a first impregnation of wood or wooden material with an aqueous solution of potassium oxalate
- a first drying step comprising drying of the wood or wooden material
- a second impregnation step comprising a second impregnation of wood or wooden material with an aqueous solution of calcium acetate
- a second drying step comprising drying of the wood or
- halogen ions such as chloride or bromide may under extreme temperatures, i.e. under fire exposure generate toxic gases such as HCl or HBr. Therefore, the inventive method provides wood or wooden material which is safer. Additionally, calcium acetate can be used as an aqueous solution and therefore its handling is easier and safer than handling of gaseous materials. Furthermore, the generated calcium oxalate significantly improves the fire resistance of the mineralized wood or wooden material.
- drying may be achieved by exposing the impregnated wood or wooden material to increased temperatures, for example by using hot air or an oven. Alternatively, drying may be achieved by maintaining the wood or wooden material at ambient temperature until a certain water content is reached. Additionally, or alternatively, drying may be achieved by application of an underpressure, i.e. applying a vacuum.
- impregnation may be achieved by any suitable method, such as dipping, particularly under pressure, spraying or spreading. However, preferably, impregnation is achieved by filling an autoclave with wood or wooden material and the corresponding solution and applying a pressure. Typically, the first and second impregnation are separate impregnation steps. The intermediate drying step makes the second impregnation step significantly more efficient.
- the concentration of potassium oxalate dissolved in the solution lies in the range of 20%-100%, preferably 90%-100% of its saturation concentration.
- the concentration of calcium acetate dissolved in the solution may lie in the range of 1 5-90%, preferably 65-90% of its saturation concentration.
- the saturation concentration is the maximum possibly quantity of a substance that can dissolve in the solvent, i.e. in water.
- concentration has been found beneficial, as a calcium acetate solution with a concentration below the saturation concentration penetrates the wood or wooden material faster and deeper, i.e. the impregnation is more effective.
- the concentration is high enough to enable sufficient generation of calcium oxalate.
- the first and/or the second impregnation comprises a phase of overpressure during which the pressure is selected in the range of 5-10 ⁇ 10 5 Pa (5-10 bar), preferably 8 bar, and the temperature is selected to be in the range of 15-50 °C, preferably in the range of 15-25 °C, more preferably 20°C.
- the duration of the phase of overpressure in the first and/or the second impregnation step is ⁇ 1 hour, typically 1-24 h, preferably 2-8 h.
- the first and/or the second impregnation is preceded by a vacuum phase, during which the wood or wooden material is exposed to underpressure, preferably of 1-3 ⁇ 10 4 Pa (100-300 mbar), preferably for 30 minutes, preferably at 20 to 60 °C.
- underpressure refers to a pressure below atmospheric pressure, preferably to a pressure of up to 300 mbar.
- the first and/or second drying step comprises a vacuum phase, during which the wood or wooden material is exposed to underpressure, preferably for a time period lying in the range of 30 minutes to 4 hours, more preferably 45 minutes to 3 hours, preferably at a temperature of 20-70 °C, more preferably 30-60 °C, and preferably at an underpressure of 1 -3 ⁇ 10 4 Pa (100-300 mbar), more preferably 100-150 mbar.
- the wood or wooden material is dried to a wood moisture of 612%, preferably 8% in the second drying step.
- a second aspect of the present disclosure not according to the invention, comprises wood or wooden material which is mineralized in a method according to any of the embodiments described herein, which is characterized in that it comprises calcium oxalate deposits and is essentially free of chloride deposits, such as potassium chloride, calcium chloride or the like.
- Essentially free of potassium chloride means that the content of chloride ions of the total salt content in the wood or wooden material is below 5%, i.e. below 1%, i.e. below 0.1 %, i.e. below 0.01 %, preferably 0%.
- wood or wooden material which is mineralized according to the present invention contains potassium acetate deposits.
- the molar ratio of the potassium acetate deposits and the calcium oxalate deposits is in the range of 1.5:1 to 3:1, preferably 2:1.
- the content of calcium oxalate in the wood or wooden material which is mineralized in a method according to the present invention lies in the range of 10-20 weight percent, preferably 13-16 weight percent, more preferably 1 5-16 weight percent.
- the wood or wooden material comprises European oak, beech or maple, mixtures thereof or consists thereof.
- oak is used as wood or wooden material for the mineralization method described herein, wherein the content of calcium oxalate in the mineralized wood lies in the range of 12-17 weight percent, preferably 15-16 weight percent.
- the critical heat flux as determined according to ISO 9239-1 (version of 2010-11), exceeds 10.5 kW/m 2 for mineralized oak, wherein the content of calcium oxalate lies in the range of 12-17 weight percent, preferably 15-16 weight percent.
- the burning distance as determined according to ISO 9239-1 (version of 2010-11), lies between 100 mm and 10 mm, preferably between 30 mm and 20 mm, for mineralized oak, wherein the content of calcium oxalate lies in the range of 12-17 weight percent, preferably 15-16 weight percent.
- the tangential swelling coefficient at 20 °C and in the presence of 65% relative humidity lies in the range of 1%-3%, preferably 2.0%-2.6%, more preferably 2.2% and 2.4%, for mineralized oak, wherein the content of calcium oxalate lies in the range of 12-17 weight percent, preferably 15-16 weight percent.
- beech is used as wood or wooden material for the mineralization method described herein.
- maple is used as wood or wooden material for the mineralization method described herein.
- the mineralization with calcium oxalate is based on two separate impregnation steps.
- the material is impregnated in an aqueous solution with potassium oxalate (C 2 O 4 K 2 ).
- the material is dried and then impregnated with calcium acetate (Ca(CH 3 COO) 2 .).
- the potassium oxalate already present in the material to be mineralized and the calcium acetate form calcium oxalate ⁇ CaC 2 O 4 ⁇ solid , which is practically not soluble in water, and potassium acetate as by product.
- a molar ratio of 1:1.12 of potassium oxalate/calcium acetate was employed.
- the molecular weight of K 2 C 2 O 4 -6H 2 O is 184.23 g/mol, the water solubility 38.7 g/100g H 2 O.
- the molecular weight of Ca(CH 3 COO) 2 is 158.166 g/mol, the water solubility 34.7 g/100g in H 2 O at 20°C.
- the potassium oxalate solution was prepared by dissolving 360 g Potassium oxalate hydrate in 1
- Calcium acetate in its anhydrous form, is a white solid at room temperature. It is a hygroscopic compound and forms solutions in water dissociating in calcium and acetate ions. It is commercially available in anhydrous and hydrous form as Ca(CH 3 COO) 2 ⁇ H 2 O. The properties will evidently depend on its hydration degree. For the tests performed calcium acetate monohydrate was employed.
- calcium acetate and its aqueous solutions may be considered as harmless. Indeed, calcium acetate is commonly employed as food additive (E 263). Calcium acetate is therefore suited for wood impregnation and does not pose a significant danger in the event that the impregnated wood or wooden material displays residual calcium acetate.
- Potassium oxalate is a salt of oxalic acid and is commercially available as a colorless solid. In aqueous solutions it can dissociate to form oxalate and potassium ions. Oxalate ions can be combined with calcium, magnesium, and iron ions to form less soluble or insoluble salts. Potassium oxalate is commercially available in anhydrous form or as its monohydrate. In the current experiments, the monohydrate (K 2 C 2 O 4 ⁇ H 2 O) was used. Once the oxalate anion has reacted with the cation from the calcium acetate solution, it forms a heavy soluble salt (CaC 2 O 4 ) that is retained in wood or wooden material, providing the protection effect.
- aC 2 O 4 heavy soluble salt
- the three hard-wood species commonly used as decorative wood for interior applications are European oak ( Quercus spp .), beech ( Fagus sylvatica ) and maple (Acer spp.). They are representative species of European hardwood and grow across European countries.
- the woods preferably used in the method according to the invention include: European oak, beech and maple.
- European oak Quercus spp. is a hardwood belonging to the division of angiosperms. As it is characteristic for hardwoods, oak is composed by vessel elements, fibers (tracheids), parenchyma and ray cells. Vessels are arranged in a ring porous structure. Density varies from 0.43 - 0.69 - 0.96 g/cm 3 . Characteristic for oak is a high amount of water extractives (up to 12%) including a high amount of tannins. European oak heartwood ( Quercus spp.) is classified as heavily treatable. Treatability is the ease with which a wood can be penetrated by a liquid.
- Beech Fagus sylvatica
- beech is a hardwood belonging to the division of angiosperms. As it is characteristic for hardwoods, beech is composed by vessel elements, fibers (tracheids), parenchyma and ray cells. Vessels are arranged in a non-specific pattern, resulting in a semi-porous to diffuse porous distribution. Growth ring limits are demarked by dark colored late wood. Density varies from 0.48 - 0.68 - 0.88 g/cm 3 . Beech ( Fagus sylvatica ) is classified as easily treatable.
- Maple (Acer spp.) is a hardwood belonging to the division of angiosperms. As it is characteristic for hardwoods, maple is composed by vessel elements, fibers (tracheids), parenchyma and ray cells. Vessels are arranged in a non-specific pattern, resulting in a semi-porous to diffuse porous distribution. The density of maple varies from 0.53 - 0.63 - 0.79 g/cm 3 . Maple (Acer spp.) is classified as easily treatable.
- the samples are placed vertically into the holding device and the burner is installed in front of the sample tilted 45°.
- the distance of the burner from the unprotected edge of the sample is 16mm.
- the flame has a length of 20mm.
- the wood or wooden material obtained from mineralization may be characterized by different parameters, including the following:
- MEE moisture excluding efficiency
- Thermogravimetric analysis was performed using a TG50 instrument (Mettler Toledo). The weight of the tested mineralized wood powder varies between 10-15 mg.
- the fiber saturation level is defined as the moisture content of wood which is determined at a theoretical relative humidity of 100%.
- the fiber saturation point represents the wood moisture content at which the cell wall cannot increase its moisture content any further.
- the wood moisture content is defined as the current amount of water in the wood based on the absolute dry weight of the wood.
- the absolute dry weight of the wood (abbreviated as abs. dry) is defined as the mass which occurs after drying the wood at 103 °C until weight constancy. Weight constancy is defined as a weight change less than 0.1 % in 6 hours.
- Moisture Content weight wood at the current moisture content ⁇ weight absolute dry weight absolute dry
- the wood equilibrium moisture content is defined as the moisture content which occurs if the wood is exposed under stable temperature and relative humidity.
- the parameters described above were determined for oak ( Quercuss spp .) mineralized according to the process described above (see process steps of mineralisation at an industrial level).
- thermogravimetric analysis 245 °C
- Critical heat flux as determined according to DIN EN ISO 9239-1 (version of 2010-11): 11.0 kW/m 2 in product direction and 11.0 kW/m 2 in direction perpendicular to the first direction
- the mineralized oak was subjected to a modified ISO norm 11925-2 test, where the specimens were conditioned at 20 °C and 65% relative humidity instead of 23 °C and 50 % relative humidity involving exposure to an ignition source for 30 seconds. The time of burning after elimination of the ignition source was determined to be 0 seconds, as reproduced with 5 specimens).
- the critical heat flux of the mineralized beech is 8.0 kW/m 2 (length) and 7.5 kW/m 2 (perpendicular), as determined according to ISO 9239-1 (version of 2010-11).
- the burning distance of the mineralized beech is 220 mm (length) and 160 mm (perpendicular).
- maple (Acer spp.) mineralized according to the process described above (see process steps of mineralisation at an industrial level).
- the critical heat flux of the mineralized maple is 10.0 kW/m 2 (length) and 10.5 kW/m 2 (perpendicular), as determined according to ISO 9239-1 (version of 2010-11).
- the burning distance of the mineralized maple is 200 mm (length) and 150 mm (perpendicular).
- a further advantage of the mineralized wood or wooden material obtained from the mineralization method outlined above is that the mineralized wood or wooden material displays remarkable color fastness.
- the untreated wood or wooden material hardly differs from the mineralized wood or wooden material in either color or color structure.
- mineralized wood or wooden material, particularly oak, that has been subjected to subsequent surface coating using common surface coating agents such as linseed oil also hardly differs from the respective untreated wood or wooden material in either color or color structure.
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Chemical And Physical Treatments For Wood And The Like (AREA)
Claims (8)
- Procédé de minéralisation du bois et des matériaux en bois comprenant :i) une première étape d'imprégnation, comprenant une première imprégnation du bois ou du matériau en bois avec une solution aqueuse d'oxalate de potassium,ii) une première étape de séchage, comprenant le séchage du bois ou du matériau en bois,iii) une deuxième étape d'imprégnation, comprenant une deuxième imprégnation du bois ou du matériau en bois avec une solution aqueuse d'acétate de calcium,iv) une deuxième étape de séchage, comprenant le séchage du bois ou du matériau en bois.
- Procédé selon la revendication 1, caractérisé en ce que la concentration d'oxalate de potassium dissous dans la solution est comprise entre 20 % et 100 %, de préférence entre 90 % et 100 % de sa concentration de saturation.
- Procédé selon la revendication 1 ou 2, caractérisé en ce que la concentration d'acétate de calcium dissous dans la solution est comprise entre 15 % et 90 %, de préférence entre 65 % et 90 % de sa concentration de saturation.
- Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la première et/ou la seconde imprégnation comprend une phase de surpression au cours de laquelle la pression est choisie dans la gamme de 5-10×105 Pa (5-10 bar), de préférence 8×105 Pa (8 bar), et la température est choisie dans la gamme de 15-50 °C, de préférence dans la gamme de 15-25 °C, plus préférentiellement 20 °C.
- Procédé selon la revendication 4, caractérisé en ce que la durée de la phase de surpression dans la première et/ou la deuxième étape d'imprégnation est ≥ 1 heure, typiquement 1-24 h, de préférence 2-8 h.
- Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la première et/ou la seconde imprégnation est précédée d'une phase de vide, au cours de laquelle le bois ou le matériau en bois est exposé à une dépression, de préférence de 1-3×104 Pa (100-300 mbar), de préférence pendant 30 min, de préférence à une température de 20 à 60 °C.
- Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la première et/ou la deuxième étape de séchage comprend une phase de vide, au cours de laquelle le bois ou le matériau en bois est exposé à une dépression, de préférence pendant une durée comprise entre 30 minutes et 4 heures, plus préférentiellement entre 45 minutes et 3 heures, de préférence à une température de 20 à 70 °C, plus préférentiellement entre 30 et 60 °C, et de préférence à une dépression de 1 à 3×104 Pa (100 à 300 mbar), plus préférentiellement entre 100 et 150 mbar.
- Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le bois ou le matériau en bois est séché jusqu'à une humidité du bois de 6 % à 12 %, de préférence 8 %, lors de la deuxième étape de séchage.
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GB244178A (en) * | 1924-09-12 | 1925-12-14 | Novocrete And Cement Products | Improvements in or relating to the induration or mineralization of organic matter |
IE32392B1 (en) * | 1967-10-12 | 1973-07-25 | Sutton Res Corp | Smoking products,and processes for making such products |
EP3519147B1 (fr) * | 2016-10-03 | 2021-10-27 | Berner Fachhochschule - Biel Architektur, Holz und Bau | Minéralisation du bois et de matières cellulosiques |
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