EP3934869B1 - Verfahren zur holzmineralisierung unter verwendung von acetoacetatlösungen zur verbesserung der wesentlichen eigenschaften von holz - Google Patents

Verfahren zur holzmineralisierung unter verwendung von acetoacetatlösungen zur verbesserung der wesentlichen eigenschaften von holz Download PDF

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EP3934869B1
EP3934869B1 EP20859629.6A EP20859629A EP3934869B1 EP 3934869 B1 EP3934869 B1 EP 3934869B1 EP 20859629 A EP20859629 A EP 20859629A EP 3934869 B1 EP3934869 B1 EP 3934869B1
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wood
impregnation
mineralization
caco
mgco
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French (fr)
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EP3934869A1 (de
EP3934869C0 (de
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Andreja PONDELAK
Andrijana SEVER SKAPIN
Natasa KNEZ
Rozle REPIC
Luka SKRLEP
Tomaz PAZLAR
Friderik KNEZ
Andraz LEGAT
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Zavod Za Gradbenistvo Slovenije
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Zavod Za Gradbenistvo Slovenije
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    • 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
    • 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
    • B27K3/08—Impregnating by pressure, e.g. vacuum impregnation
    • 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
    • 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
    • B27K3/50—Mixtures of different organic impregnating agents
    • 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
    • B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
    • B27K5/003—Treating of wood not provided for in groups B27K1/00, B27K3/00 by using electromagnetic radiation or mechanical waves
    • B27K5/0065—Ultrasonic treatment
    • 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 presented relates to the field of wood modification, specifically to the mineralization of wood i.e. the incorporation of CaCO 3 , MgCO 3 , SrCO 3 into the structure of the wood, and methods for such mineralization.
  • FR flame-retardants
  • FR coatings Compounds used as FR may be nitrogen, phosphorus, boric acid and borax compounds, inorganic salts such as borates, stannates and silicates, and aluminum and magnesium based minerals.
  • Some processes for incorporating CaCO 3 into the structure of wood in order to reduce its flammability, increase hydrophobicity, and improve mechanical properties, are already known.
  • One such wood mineralization process is the in-situ formation of CaCO 3 , achieved by immersing the wood in an aqueous CaCl 2 solution for 1 hour, then in an aqueous NaOH solution for 1 hour, and finally in supercritical CO 2 in a high pressure vessel for 1 hour.
  • the result of the process is reduced flammability of the wood ( C . Tsioptsias, C. Panayiotou, Thermal stability and hydrophobicity enhancement of wood through impregnation with aqueous solutions and supercritical carbon dioxide: Journal of Materials Science, 2011, vol.
  • the impregnation process can take varying lengths of time (a shorter reaction cycle lasts 2 hours, a longer one 24 hours), and consists of one or more (of up to 4) cycles. As the cycle length, or the number of reaction cycles increases, so does the mass of CaCO 3 introduced and consequently the total mass of the wood increases. Using 24-hour cycles, for example, the mass of a piece of spruce was shown to increase by 20% after one cycle and by approximately 35% following 3 cycles ( I. Burger, M. Chanana, V. Merk, U.S. Pat. 0043497 A1, 2017 ) .
  • the main disadvantage of the above-mentioned methods of wood mineralization is the formation of by-products (i.e. NaCl), which can affect the appearance of wood and can also corrode metal elements (e.g. binders), which are often embedded in wood and wooden products.
  • by-products i.e. NaCl
  • binders corrode metal elements
  • toxic methanol is formed.
  • the procedure is time consuming, as it takes place in two stages, with one cycle lasting several hours (up to 24 hours), and there is a need to use repeated cycles (up to 4 times).
  • the wood needs to be washed several times to remove the by-product, i.e. NaCl.
  • wood and wood composites include wood of any moisture content, for example freshly-cut wood, wood at the fiber saturation point, air-dried, or absolutely dry wood, wood of any tree species, and wood subjected to any type of fiber pre-treatment, such as thermally-modified wood or wood previously exposed to ultrasound, used wood or wood composites.
  • the wood improves its resistance to fire, resistance to fungi, mechanical properties, durability and other properties.
  • the term 'reference wood' will be used to represent any wood that has not been treated or modified, and will be used for comparison with the modified wood (that which has been mineralized or thermally modified or treated in some other way).
  • the term 'thermally modified wood' is used to describe wood prepared by the commercial Silvapro ® process ( G. Rep, F. Pohleven in S. Kosmerl, Wood modification - A promising method for wood preservation, Proceedings of the 6th European Conference on Wood Modification, University of Ljubljana, Slovenia, str. 11-17, 2012 ).
  • Wood mineralization takes place in two phases - namely, in the first phase, the wood is impregnated with an impregnating solution, an aqueous solution of acetoacetates, with one of the known impregnation methods (the most commonly used impregnation method involves exposing wood to an impregnating solution in an environment with varying vacuum and overpressure) so that the impregnating solution penetrates deep into the structure of the wood.
  • the process of changing vacuum and overpressure generally results in the best impregnation properties (i.e. a more homogeneous distribution, deeper penetration, and greater absorption of the impregnating solution into the wood; H. Yorur, K.
  • the wood mineralization process according to the invention comprises the following phases:
  • the metal beta-carboxylate is a metal acetoacetate selected from calcium acetoacetate Ca(OAcAc) 2 , magnesium acetoacetate Mg(OAcAc) 2 orstrontium acetoacetate Sr(OAcAc) 2 , or mixtures thereof in any weight ratio.
  • the solvent is water
  • the metal acetoacetate solution is selected from aqueous solutions of calcium acetoacetate Ca(OAcAc) 2 , magnesium acetoacetate Mg(OAcAc) 2 or strontium acetoacetate Sr(OAcAc) 2 or mixtures thereof in any weight ratio.
  • the process of impregnation using vacuum and/or overpressure involves impregnation of the wood using either the "full-" or "empty-" cell process. In the process of the "full” cell method, or the so-called "Bethell process", the wood is placed in an impregnation chamber and exposed to a vacuum below 100 mbar for a period of 30 to 60 minutes to remove air from the wood and impregnation chamber.
  • the impregnating solution is then poured into the chamber while maintaining a constant vacuum. This is followed by exposure to a overpressure of above 10 bar, causing the impregnation solution to penetrate deep into the structure of the wood. Preferably, the wood is exposed to an overpressure above 10 bar for at least 180 minutes. Optionally, the excess impregnation solution is drained out using an additional vacuum below 100 mbar for at least 5 minutes ( Emission Factor Documentation for AP-42 Section 10.8, Wood Preserving, Final Report, MRI project No. 4945, 1999, https://www3.epa.gov/ttn/chief/ap42/ch10/bgdocs/b10s08.pdf) .
  • the most commonly used processes are “Rueping” and “Lowry”.
  • the wood is first placed in an impregnation chamber and exposed to a pressure between 172 and 690 kPa for a period of a few minutes to 1 hour, then an impregnating solution is poured into the chamber at a maintained pressure in order to increase the pressure in the chamber and thus allow the solution to penetrate deep into the wood. The procedure continues until a sufficient amount of solution is absorbed. This is followed by removal of the impregnating solution, and, optionally, exposure of the samples to a vacuum.
  • an impregnating solution is poured into the chamber without maintaining the vacuum or overpressure. This is followed by exposure to overpressure until a sufficient amount of the solution has been absorbed into the wood. The final stage involves removal of the solution and optional exposure of the samples to a vacuum.
  • the wood is exposed to vacuum and/or overpressure until a sufficient amount of solution penetrates into the wood.
  • the exposure time depends on the type and quality of the wood or wood composites.
  • the wood should be exposed to an overpressure above 10 bar for at least 180 minutes.
  • the wood can then be exposed to an additional vacuum below 100 mbar for at least 5 minutes in order to remove any excess solution.
  • the exposure to the additional vacuum takes place at a vacuum between 50 and 60 mbar, for a period between 20 and 30 minutes.
  • a modified "full" cell process can be used, where the wood is placed in an impregnation chamber filled with an impregnating solution, then first exposed to a vacuum below 100 mbar for between 30 and 60 min. The wood is then exposed to an overpressure above 10 bar until a sufficient amount of solution penetrates into the structure of the wood.
  • the impregnation phase may consist of one step or multiple steps.
  • the solution of a single metal acetoacetate for example only Ca(OAcAc) 2 or only Mg(OAcAc) 2
  • a solution of a mixture of different metal acetoacetates in any weight ratio for example a mixture of Mg(OAcAc) 2 and Ca(OAcAc) 2 in a weight ratio of 50 : 50
  • a single metal acetoacetate for example only Ca(OAcAc) 2 or only Mg(OAcAc) 2
  • a solution of a mixture of different metal acetoacetates in any weight ratio for example a mixture of Mg(OAcAc) 2 and Ca(OAcAc) 2 in a weight ratio of 50 : 50
  • the impregnation phase consists of multiple steps (a two-step or a multi-step impregnation)
  • a solution of a single metal acetoacetate or a solution of a mixture of different metal acetoacetates in any weight ratio may be used, wherein the individual steps may follow each other in any order.
  • the wood or wood composites may be impregnated with the same metal acetoacetate(s) solution in each step, e.g. using a solution of either Ca(OAcAc) 2 , Mg(OAcAc) 2 or Sr(OAcAc) 2 , or alternatively using a solution containing a mixture of Ca(OAcAc) 2 and Mg(OAcAc) 2 in a 50:50 weight ratio.
  • the wood or wood composites may be impregnated with different solutions in each step (containing different metal acetoacetates and/ or various mixtures thereof in any weight ratio).
  • the wood or wood composite may be impregnated with a Mg(OAcAc) 2 solution, followed by a second impregnation with a Ca(OAcAc) 2 solution; or, for example, in the first step, the wood or wood composite may be impregnated with a solution of Mg(OAcAc) 2 , in the second step a solution containing Mg(OAcAc) 2 and Ca(OAcAc) 2 mixed in a weight ratio of 50:50 may be used; or, for example, in the first step the wood or wood composite may be impregnated with a solution containing a mixture of Mg(OAcAc) 2 and Ca(OAcAc) 2 in a weight ratio of 50:50, followed by a second step using a solution containing Mg(OAcAc) 2 and Sr(OAcAc) 2 mixed in a weight ratio of 50 : 50.
  • the impregnation phase is one-step and follows a modified "full" cell process, where the wood is placed in an impregnation vessel filled with an impregnating agent which is a 20% by weight aqueous solution of the metal acetoacetate(s). This is followed by 30 minutes exposure to a vacuum between 50 and 60 mbar, and 180 minutes at an overpressure between 10 and 12 bar. Optionally, a vacuum between 50 and 60 mbar is applied for another 20 to 30 minutes to remove any excess impregnation solution from the wood's structure.
  • an impregnating agent which is a 20% by weight aqueous solution of the metal acetoacetate(s).
  • a vacuum between 50 and 60 mbar is applied for another 20 to 30 minutes to remove any excess impregnation solution from the wood's structure.
  • the effectiveness of wood impregnation i.e. the depth of penetration of the impregnating agent into the wood, and the amount of absorbed impregnating agent (degree of uptake), can be adjusted by the impregnation method, i.e. by choosing the impregnation process selected, most commonly by changing the values of overpressure and vacuum inside the chamber and the time of exposure of wood to these conditions.
  • Another way to increase the efficiency of impregnation is to pre-treat the wood with ultrasound, preferably at a frequency of 28 kHz to 40 kHz and an intensity of 300 W, at a temperature between 40 °C and 100 °C for at least 30 minutes.
  • a third way to increase the efficiency of impregnation is to add surfactants to the impregnating agents, which allow the impregnating agent to penetrate deeper into the wood structure.
  • the impregnation phase may be followed by an intermediate phase, which is a drying phase of the impregnated wood, in which the impregnated wood is dried at room temperature for at least 1 day, preferably for 3 days, at room temperature, before entering the after-treatment phase.
  • an intermediate phase which is a drying phase of the impregnated wood, in which the impregnated wood is dried at room temperature for at least 1 day, preferably for 3 days, at room temperature, before entering the after-treatment phase.
  • the impregnation phase is followed by the after-treatment phase, in which the impregnating agent s converted to carbonate(s).
  • the acetoacetate in the impregnated wood is converted to the corresponding carbonate depending on the metal acetoacetate solution selected in the impregnation phase, i.e. CaCO 3 , MgCO 3 , SrCO 3
  • Impregnated wood can also be exposed to higher temperatures (T> 100 ° C) and lower relative humidity (RH ⁇ 35%) for a suitable length of time.
  • the conversion of acetoacetate(s) to carbonate(s) can also be accelerated through exposure to ultrasound, preferably at a frequency of 28 kHz - 40 kHz and an intensity of 300 W for at least 60 min, at an elevated temperature of between 40 °C and 100 °C.
  • the after-treatment phase can also take place under variable conditions, by dividing the entire phase into time intervals and defining a temperature and relative humidity for each interval.
  • Time intervals can be the same length or different lengths.
  • conditions may be alternated using intervals of the same length, namely: 1 st step 8 h at 80 ° C and 90% RH, 2 nd step 8 h at 80 ° C and 40% RH, 3 rd step 8 h at 80 ° C and 90% RH, 4 th step 8 h at 80 ° C and 40% RH, 5 th step 8 h at 80 ° C and 90% RH, 6 th step 8 h at 80 ° C and 40% RH , and the 7 th stage 8 h at 80 ° C and 90% RH.
  • Ca(OAcAc) 2 , Mg(OAcAc) 2 and Sr(OAcAc) 2 decompose into their corresponding carbonate, according to the following formulas: Ca(OAcAc) 2 + H 2 O - CaCO 3 + CO 2 + 2 CH 3 COCH 3 Mg(OAcAc) 2 + H 2 O - MgCO 3 + CO 2 + 2 CH 3 COCH 3 Sr(OAcAc) 2 + H 2 O - SrCO 3 + CO 2 + 2 CH 3 COCH 3
  • the amount of impregnation solution introduced depends on the type, geometry, humidity and pre-treatment of the wood composite the impregnation process selected and any potential additives in the impregnating solution.
  • Larger amounts of carbonates can be introduced by adjusting the conditions (for example by increasing the vacuum and overpressure values) and by prolonging the impregnation time, by increasing the concentration of acetoacetate(s) in the impregnation solution(s), or by repeating the impregnation process (two or more times) using either the same or a different solution (for example by using a solution of Ca(OAcAc) 2 followed by a solution of Mg(OAcAc) 2 ), or even with a mixture of different impregnating solutions (for example an aqueous solution of Ca(OAcAc) 2 and Mg(OAcAc) 2 mixed in a 50:50 weight ratio).
  • carbonates e.g. CaCO 3 , MgCO 3 , SrCO 3
  • the incorporation of carbonates into the structure of the wood reduces the flammability of wood, wood composites or wooden products, because decomposition of carbonates at higher temperatures is an endothermic process, which, together with the release of CO 2 and/or H 2 O, cools flammable gases in the event of a fire.
  • the carbonate(s) thermally decompose(s) into CO 2 and metal oxide.
  • the thermal decomposition of CaCO 3 , MgCO 3 and SrCO 3 is shown in the formulas below.
  • MgCO 3 can thermally decompose into MgO, CO 2 and H 2 O, as the conversion of Mg(OAcAc) 2 to MgCO 3 can result in the hydrated crystalline modification(s) of MgCO 3 (e.g. nesquehonite, which has the chemical formula MgCO 3 ⁇ 3H 2 O).
  • Example 2 The impregnation phase in wood and wood composites
  • the impregnation phase was carried out using a one-step impregnation process, by directly placing the wood samples in a 20% by weight Ca(OAcAc) 2 , Mg(OAcAc) 2 or Sr(OAcAc) 2 solution, prepared according to the procedure described in Example 1. The samples were then exposed to a 50-60 mbar vacuum for 30 minutes, followed by 3 hours at 8-10 bar and subsequently another 20-30 min at a vacuum of 50-60 mbar.
  • the penetration in the grain direction was prevented by coating based on epoxy resin.
  • the impregnated wood samples (prepared according to Example 2) were first dried at room temperature for at least 3 days, then exposed to an elevated temperature and relative humidity for the following amounts of time: 1 st step 8 h at 80 °C and 90% RH, 2 nd step 8 h at 80 °C and 40% RH, 3 rd step 8 h at 80 °C and 90% RH, 4 th step 8 h at 80 °C and 40% RH, 5 th step 8 h at 80 °C and 90% RH, 6 th step 8 h at 80 °C and 40% RH, 7 th step 8 h at 80 °C and 90% RH.
  • the mineralized wood was then aged at room temperature for one week.
  • Samples of spruce and beech wood were prepared as described in examples 1 to 3. With a single impregnation of Mg(OAcAc) 2 solution we were able to introduce 110 wt.% Mg(OAcAc) 2 into spruce, meaning 9.2 wt.% of the resulting MgCO 3 (dry intake) was absorbed into the structure of the wood. In the same wood, using a single impregnation of Ca(OAcAc) 2 solution, we were able to introduce 137 wt.% Ca(OAcAc) 2 , meaning 12.1 wt.% of the CaCO 3 formed in the wood's structure.
  • Table 1 Mass of spruce or beech samples before impregnation, mass of samples after impregnation, calculated proportions re wet uptake of impregnating solutions (aqueous solutions of Mg(OAcAc) 2 and Ca(OAcAc) 2 ), and share of the dry uptake (proportion of MgCO 3 / CaCO 3 ) by weight in mineralized spruce and beech samples.
  • Example 5 Determining the penetration depth of the impregnating agent
  • the penetration depth of the impregnating solution was checked in both the fiber direction and perpendicular to the fibers by impregnating a 140 mm (l) ⁇ 100 mm (w) ⁇ 10 mm (h) mm wood sample with an aqueous solution of Ca (OAcAc) 2 , according to Examples 1 and 2. Following this, the samples were dried at room temperature for 2 days, after which the impregnated samples were cut through the middle both transversely and longitudinally, as shown in Figure 1 .
  • An indicator i.e.
  • aqueous sodium nitroprusside solution Na 2 [Fe(CN) 5 (NO)] ⁇ 2H 2 O; Sigma Aldrich
  • the red colour which identifies the presence of acetoacetates, develops in about 30 minutes.
  • the impregnating solution evenly penetrates into the spruce to a depth of at least 5 mm in the direction perpendicular to the fibers and at least 7 cm in the direction of the fibers. In this particular case, the entire depth of the sample was impregnated.
  • MgCO 3 formed in an elongated shape ( Figure 2b , Figure 3b ), while CaCO 3 was spherical ( Figure 2d , Figure 3d ), occurring in varying sizes up to 100 ⁇ m in diameter.
  • Figure 4 shows the diffractograms of reference spruce (a), CaCO 3 mineralized spruce (b), reference beech (c), and CaCO 3 mineralized beech (d), each prepared as described in Examples 1 to 3.
  • the patterns of spruce mineralized with CaCO 3 correspond to vaterite crystal modification.
  • the diffractograms on the right are marked with dots where the patterns do not overlap with those of the reference spruce or beech but instead are characteristic for vaterite CaCO3 crystal modification (marked with V).
  • Reaction to fire was determined using a cone calorimeter according to ISO 5660-1:2015, for all of the following samples in both beech and spruce, each prepared as described in examples 1 to 3: (a) reference, (b) mineralized with MgCO 3 or CaCO 3 or SrCO 3 , (c) thermally modified then mineralized with MgCO 3 or CaCO 3 , (d) twice mineralized with MgCO 3 (beech only), and (e) mineralized with a mixture of either MgCO 3 and SrCO 3 or MgCO 3 and CaCO 3 , each in a 50 : 50 mass ratio.
  • Specimens of dimensions 100 mm (1) ⁇ 100 mm (w) ⁇ 10 mm (h) were exposed to a heat flux of 50 kW/m 2 .
  • the results are shown in Table 2; average values and standard deviations of ignition time, total heat release in the first 600 seconds of the test (THR 600s ), and smoke growth rate index (FIGRA) are listed for all specimens.
  • Figures 5 and 6 show two examples of heat release rate (HRR) in the specimens made of spruce, while Figures 7 to 11 show examples of beech wood.
  • An example of the smoke growth rate index (SMOGRA) in a specimen from beech wood is shown in Figure 12 .
  • thermally modified beech and spruce has an ignition time of 20.0 s, THR 600s of 30.4 MJ and FIGRA of 488.6 Ws -1 .
  • T- MgCO 3 the ignition time increased to 32.4 s, while the THR 600s and FIGRA decreased to 15.6MJ and 191.5 Ws -1 respectively.
  • Table 2 Ignition time, total heat release, THR 600s and fire growth rate index (FIGRA) for the various spruce and beech samples: reference (R); thermally modified (T); mineralized with MgCO 3 (MgCO 3 ), CaCO 3 (CaCO 3 ), or SrCO 3 (SrCO 3 ); thermally modified and mineralized with MgCO 3 (T-MgCO 3 ) or CaCO 3 (T-CaCO 3 ); twice mineralised with MgCO 3 (MgCO 3 - 2x-beech only); mineralized with mixtures of MgCO 3 and SrCO 3 (Mg:Sr) or MgCO 3 and CaCO 3 (Ca:Mg) (results are presented as the average value and standard deviation of five measurements).
  • Example 9 Contact angle and pH value measurements for spruce wood
  • the pH values of wood samples mineralized with MgCO 3 , CaCO 3 or SrCO 3 , and thermally modified wood samples additionally mineralized with MgCO 3 , CaCO 3 or SrCO 3 were measured by applying 3 ml of water on wood surface. The pH was then measured using a pH meter (Basic Titrino) with a flat electrode, and the average of five measurements calculated for the results.
  • the unmodified spruce had a pH value of 5.5, compared to 6.8 for the thermally modified spruce (Table 4). Following mineralization with MgCO 3 the pH value increased to 9.4, after mineralization with CaCO 3 to 8.2 and after mineralization with SrCO 3 to 7.9.
  • Example 10 Durability against decay fungi
  • the first set of samples consisted of 5 parallels of reference wood (spruce or beech) and 5 parallels of thermally modified wood
  • the second set contained 5 parallels of reference wood and 5 parallels of wood mineralized with CaCO 3
  • the samples were dried to an absolutely dry state and weighed.
  • Prior to exposure to the fungi the samples were conditioned under laboratory conditions for two weeks. Samples were exposed to 3 different wood decay fungi: Gloeophyllum trabeum (GT), Poria monticola (PM) and Trametes versicolor (TV).
  • GT Gloeophyllum trabeum
  • PM Poria monticola
  • TV Trametes versicolor
  • Hemicellulose which is an excellent food for microorganisms, is decomposed during the process of thermal modification. Mineralization of wood that has been previously thermally modified further increases its resistance to GT fungus. The smallest mass losses were determined in samples which had been first thermally modified and then mineralized with CaCOs; approximately 5% in beech and 10% in spruce. The resistance of wood samples to PM and TV fungi exhibited a similar trend to that of those with GT. The highest mass loss was exhibited in the reference samples of spruce and beech, while samples which had been thermally modified, mineralized, or both, showed a significantly better resistance to the PM and TV fungi ( Figure 14b-c ).
  • Example 11 Determining the resistance to indentation (Brinell hardness)

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Claims (11)

  1. Verfahren zur Holzmineralisierung, das die folgenden Phasen umfasst:
    - eine Imprägnationsphase, wobei das Holz unter Anwendung von Vakuum und/oder Überdruck mit einem Imprägnierungsmittel imprägniert wird, das eine wässrige Lösung von mindestens einem Metall-beta-Ketocarboxylat oder einer Mischung verschiedener Metall-beta-Carboxylate ist, wobei die Konzentration von Metall-beta-Carboxylat oder einer Mischung verschiedener Metall-beta-Carboxylate in der wässrigen Lösung bis zu 30 Gew.-% beträgt, wobei das Metall-beta-Carboxylat ein Metall-Acetoacetat ist, ausgewählt aus Calciumacetoacetat Ca(OAcAc)2, Magnesiumacetoacetat Mg(OAcAc)2 oder Strontiumacetoacetat Sr(OAcAc)2 oder Mischungen davon in jedem Gewichtsverhältnis, und wobei das Imprägniermittel tief in die Struktur des Holzes eindringt;
    - eine Nachbehandlungsphase des imprägnierten Holzes, bei der durch die Regulierung der Temperatur, der Feuchtigkeit und der Einwirkzeit auf das imprägnierte Holz oder durch die Einwirkung von Ultraschall auf das imprägnierte Holz das/die Metallacetoacetat(e) in Carbonat(e) umgewandelt wird/werden, wobei die Brandeigenschaften, die Widerstandsfähigkeit gegen holzzerstörende Pilze und/oder die mechanischen Eigenschaften des Holzes verbessert werden.
  2. Verfahren zur Holzmineralisierung nach Anspruch 1, wobei das Imprägnierverfahren unter Anwendung von Vakuum und/oder Überdruck die Imprägnierung von Holz entweder nach dem "Voll"- oder "Leer"-Zellenverfahren umfasst, wobei das Holz mindestens 180 Minuten lang einem Überdruck von 10 bar ausgesetzt wird.
  3. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei die Imprägnationsphase ein- oder mehrstufig ist, wobei als Imprägniermittel in jeder einzelnen Stufe entweder die Lösung eines einzelnen Metallacetoacetats oder die Lösung einer Mischung verschiedener Metallacetoacetate verwendet wird und wobei die einzelnen Stufen in beliebiger Reihenfolge aufeinander folgen.
  4. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, bei dem das Holz nach der Imprägnationsphase zusätzlich mindestens 5 Minuten lang einem Vakuum unter 100 mbar ausgesetzt wird, um die überschüssige Imprägnierlösung zu entfernen.
  5. Verfahren zur Holzmineralisierung nach den vorhergehenden Ansprüchen, bei dem die Imprägnationsphase einstufig ist, wobei das Holz in ein Imprägniergefäß gegeben wird, das mit einem Imprägniermittel gefüllt ist, das eine 20 gewichtsprozentige wässrige Lösung des/der Metallacetoacetate(s) ist, gefolgt von 30 Minuten Einwirkung eines Vakuums zwischen 50-60 mbar, und dann 180 Minuten Einwirkung eines Überdrucks zwischen 10-12 bar, gefolgt von weiteren 20 bis 30 Minuten Einwirkung eines Vakuums zwischen 50-60 mbar zur Entfernung der überschüssigen Imprägnierlösung.
  6. Verfahren zur Holzmineralisierung nach den vorhergehenden Ansprüchen, wobei sich an die Imprägnationsphase eine Zwischenphase anschließt, die eine Trocknungsphase des imprägnierten Holzes ist, in der das imprägnierte Holz mindestens 1 Tag, vorzugsweise 3 Tage, bei Raumtemperatur getrocknet wird.
  7. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei das imprägnierte Holz in der Nachbehandlungsphase einer Temperatur zwischen 40 °C und 100 °C und einer relativen Luftfeuchtigkeit von mindestens 35 % ausgesetzt wird.
  8. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei die Nachbehandlungsphase unter konstanten Bedingungen durchgeführt wird, wobei das imprägnierte Holz während der gesamten Nachbehandlungsphase gleichbleibenden Bedingungen, d. h. der gleichen Temperatur und der gleichen relativen Luftfeuchtigkeit, ausgesetzt ist.
  9. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei die Nachbehandlungsphase unter variablen Bedingungen durchgeführt wird, wobei die Dauer der Nachbehandlungsphase in Zeitintervalle unterteilt ist und jeder Zeitintervall eine definierte Temperatur und relative Feuchtigkeit aufweist und die Zeitintervalle gleich oder unterschiedlich lang sind.
  10. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei das imprägnierte trockene Holz in der Nachbehandlungsphase in eine Kammer verbracht wird, in der es einer erhöhten Temperatur von T = 80 °C ausgesetzt wird, und wobei sich die relative Feuchtigkeit von 40 % und 90 % in gleichen Zeitintervallen abwechselt.
  11. Verfahren zur Holzmineralisierung nach einem der vorhergehenden Ansprüche, wobei das imprägnierte Holz in der Nachbehandlungsphase mindestens 60 Minuten lang bei einer Temperatur zwischen 40 °C und 100 °C mit einer Frequenz von 28 kHz - 40 kHz und einer Intensität von 300 W beschallt wird.
EP20859629.6A 2019-12-24 2020-12-22 Verfahren zur holzmineralisierung unter verwendung von acetoacetatlösungen zur verbesserung der wesentlichen eigenschaften von holz Active EP3934869B1 (de)

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SI201900260A SI25943A (sl) 2019-12-24 2019-12-24 Postopek mineralizacije lesa z uporabo raztopin acetoacetatov za izboljšanje bistvenih lastnosti lesa
SI202000239A SI25944A (sl) 2019-12-24 2020-12-16 Postopek mineralizacije lesa z uporabo raztopin acetoacetatov za izboljšanje bistvenih lastnosti lesa
PCT/SI2020/050029 WO2021133262A1 (en) 2019-12-24 2020-12-22 A process of wood mineralization using acetoacetate solutions to improve the essential properties of wood

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