EP2889112A1 - Verfahren zur hydrothermalen Behandlung von Holz - Google Patents

Verfahren zur hydrothermalen Behandlung von Holz Download PDF

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Publication number
EP2889112A1
EP2889112A1 EP13199729.8A EP13199729A EP2889112A1 EP 2889112 A1 EP2889112 A1 EP 2889112A1 EP 13199729 A EP13199729 A EP 13199729A EP 2889112 A1 EP2889112 A1 EP 2889112A1
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EP
European Patent Office
Prior art keywords
wood
temperature
during
steam
present
Prior art date
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.)
Withdrawn
Application number
EP13199729.8A
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English (en)
French (fr)
Inventor
Ingeborga Andersone
Bruno Andersons
Dace Cirule
Vladimirs Biziks
Jelena Cirkova
Juris Grinins
Ilze Irbe
Nina Kurnosova
Errj Sansonetti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
"Latvian State Institute of Wood Chemistry" Derived public person
Original Assignee
"Latvian State Institute of Wood Chemistry" Derived public person
Priority date (The priority date 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 date listed.)
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Application filed by "Latvian State Institute of Wood Chemistry" Derived public person filed Critical "Latvian State Institute of Wood Chemistry" Derived public person
Priority to EP13199729.8A priority Critical patent/EP2889112A1/de
Publication of EP2889112A1 publication Critical patent/EP2889112A1/de
Withdrawn legal-status Critical Current

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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
    • B27K1/00—Damping wood
    • 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
    • B27K5/001—Heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/005—Drying-steam generating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2210/00—Drying processes and machines for solid objects characterised by the specific requirements of the drying good
    • F26B2210/16—Wood, e.g. lumber, timber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air

Definitions

  • the present invention relates to a woodworking industry and may be used for hydrothermal treatment of wood, wood materials, and woodware.
  • Wood is one of the most popular building materials.
  • the decisive factor of applicability of woodware is the effect of fungal infection because of natural moisture content therein. Therefore, the risk of fungal infection, which especially becomes apparent under the influence of weather conditions, and also because of moisture content of permanent or changing nature, shall be obligatory taken into account.
  • the conventional methods of wood protection for example, varnish-and-paint coating, have several disadvantages.
  • Natural wood hygroscopicity which manifests itself as swelling and shrinkage thereof in a medium with changing moisture content, is the reason of tensioning and subsequent surface cracks, which may destroy protective varnish-and-paint coating, and hence, deteriorate hydrophobic properties and strength.
  • the use of chemical protection in some cases may result in washing out of protective substances, lowers the effectiveness of protection as a whole and causes a negative influence on the environment.
  • the disadvantage of this composition is that the activity thereof is manifested only in high concentration in water solutions.
  • the antiseptic agent relates to the first class of hazard, i.e. it is environmentally toxic substance. Moreover, antiseptic properties of the composition are maintained only during constant feeding of working solutions, while wood quality is decreased that worsens the process of treatment thereof.
  • It is known a method of wood treatment by applying impregnating liquid in the form of extracts of natural substances on wood surface Methodhod of Making a Mordant (Stain) for Wood. USSR Author's Certificate No. 52527, 1935, IPC C09D 15/00,). Such treatment allows making low value wood specie look like high value ones.
  • the dye enters wood to a depth of approximately 1 mm.
  • Compositions for wood staining modify only a surface appearance of wood that makes impossible a mechanical treatment of stained woodware.
  • the closest is the known method for hydrothermal treatment of wood of broadleaved tree species, wherein at the first stage wood is heated up to 130-165°C by hot air at a rate of 0.5-0.75°/min followed by the seasoning in obtained steam atmosphere at a temperature of 165°C during 0.5-1.75 hour. At the next stage wood is heated again up to 200°C in steam-air mixture during 4-8 hours, and then the product is treated by water steam at a temperature of 120-160°C ( EP1696193 ).
  • the known method provides not only the modification of the appearance of wood but also increases hydrophobicity thereof and resistance to fungal microorganisms.
  • the method is a complicated one from technological point of view because it consists of many stages with their own temperature conditions, and requires significant energy consumption.
  • the object of the present invention is to increase hydrophobicity of wood.
  • the object is achieved by that wood is heated up to 120-160°C in a steam atmosphere, in which it is seasoned, and then wood is cooled up to room temperature, and heated during the first stage at a rate 0.16-0.22°/min up to 100°C, and then the heating rate of obtained steam is decreased up to 0.11-0.13 °/min until the temperature of 160°C is reached, and wood is seasoned at the temperature of 160°C during 1-3 hours at a steam pressure 0.6-0.7 MPa, and cooled up to the temperature of 20°C during 6-8 hours.
  • the material of cell wall of lignocellulosic biomass represents interpenetrating space polymeric network, the main components of which are natural polymers of three types: cellulose, lignin and hemicelluloses. Intra- and intermolecular bond inside lignin-carbohydrate network is made by both chemical covalent bonds and hydrogen bonds due to polar hydroxyl groups in all components composing thereof. Conditions of treatment according to the present invention allow almost completely destroying hemicelluloses and, correspondingly, increasing microbiological resistance to fungal microorganisms, for which hemicellulose is a source of nourishment. At the same time due to the modification of the structure the hydrophobicity of wood is increased. Conditions of treatment according to the present invention do not result in heating of samples higher than 160°C, therefore, it fails to initiate the process of thermal destruction of wood and increase energy density thereof as the result of torrefaction.
  • Fig.1 is the curve of pressure and temperature change depending upon the time of treatment.
  • Fig.2 are the curves of the change of hydrophobicity of wood depending upon the time; curve 1 - unprocessed wood, curve 2 - impregnated wood, curve 3 - hydrothermally treated samples of wood.
  • the method according to the present invention is carried out as follows.
  • Samples of wood are loaded into an autoclave filled with water, and the temperature is increased at a rate of 0.16-0.22°/min up to the temperature of 100°C, then the rate of heating of obtained steam is decreased up to 0.11-0.13°/min until the temperature of 160°C is reached.
  • Such heating conditions prevent micro-cracking in cell membrane (fibrilla) of wood.
  • steam temperature of 160°C is reached the heating is stopped and wood is seasoned during 1-3 hours at a steam pressure 0.6-0.7 MPa.
  • the following hardwood species were used for heat treatment: European grown Grey alder (Alnus incana), birch (Betula pendula) and aspen (Populus tremula).
  • Standard cross section had a thickness of 28-30 mm and a width of 100-105 mm.
  • the length of the boards was approx. 1.0 m.
  • the moisture content of the boards was relatively low (10-12%).2 boards per wood species were selected and 5 specimens per board were used for the investigation of dimensional stability of hardwood after each thermal treatment. All samples before the tests were oven dried according to the test methodology.
  • the heat treatment was performed in one stage heat treatment process with three sub-stages, namely, (1) heating up to the modification temperature; (2) holding at the modification temperature and (3) cooling of the reactor.
  • the treatment was done in a 540 litre WTT pilot scale autoclave, and the treatment temperature and holding time varied between 140 and 160°C and 1h and 3h, respectively.
  • wood was treated in a saturated steam under superatmospheric conditions (0.6-0.7 MPa). The saturated steam was used as the heating medium to increase the heat transfer between the autoclave wall and the boards.
  • water evaporated from the wood and from additionally filled water in the autoclave generates the high-pressure steam.
  • the amount of filled water was calculated by taking into account the initial moisture content of wood and the volume of the autoclave.
  • Cooling down of the autoclave was accomplished by a slow during 6-8 hours and controlled release of pressure and temperature to atmospheric conditions.
  • the hydrophobicity is determined as follows.
  • Contact angle has been measured using the sessile drop technique. It consists in a deposition of a drop of water on the sample surface and then the spread of the drop is recorded and the corresponding contact angle is obtained. The volume of the drop is 10 ⁇ l and one drop per second is recorded. According to the properties of the wood surface, the drop of water will stay for a short or long time and the contact angle will be large or small depending on the surface hydrophobicity.
  • the graph represents the contact angle value for impregnated wood samples, untreated control wood samples and thermally treated wood samples.
  • Samples have been selected choosing those with similar surface properties (without defects or knots, similar annual growth rings density) and then planed and sanded to obtain a smooth surface.
  • Wood rapidly absorbs water drop during measurements.
  • the contact angle rapidly decreases in few seconds for untreated wood, as is seen from the graph after 9 seconds it is not possible to measure further contact angle.
  • Contact angle is slightly better for impregnated wood, but also in this case the time of measurement is 14 seconds.
  • Thermally treated wood gives the largest values of contact angle, due to increased hydrophobicity thereof, in this case the drops remain on wood for a longer period of time before absorbing in the wood.
  • the method of hydrothermal treatment of wood according to the present invention allows increasing hydropphobicity of wood by several times along with saving energy costs. Moreover, hydrophobicity values of treated wood are higher than those of impregnated wood.

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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)
EP13199729.8A 2013-12-27 2013-12-27 Verfahren zur hydrothermalen Behandlung von Holz Withdrawn EP2889112A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP13199729.8A EP2889112A1 (de) 2013-12-27 2013-12-27 Verfahren zur hydrothermalen Behandlung von Holz

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP13199729.8A EP2889112A1 (de) 2013-12-27 2013-12-27 Verfahren zur hydrothermalen Behandlung von Holz

Publications (1)

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EP2889112A1 true EP2889112A1 (de) 2015-07-01

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017084884A1 (de) * 2015-11-18 2017-05-26 SWISS KRONO Tec AG Osb (oriented strand board)-holzwerkstoffplatte mit verbesserten eigenschaften und verfahren zu deren herstellung
WO2017097506A1 (de) * 2015-12-07 2017-06-15 SWISS KRONO Tec AG Holzwerkstoffplatte mit reduzierter emission an flüchtigen organischen verbindungen (vocs) und verfahren zu deren herstellung
US11007668B2 (en) 2017-04-25 2021-05-18 SWISS KRONO Tec AG Process for the production of OSB wood-based boards with reduced emission of volatile organic compounds (VOCs)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1810659A (en) * 1929-02-14 1931-06-16 Kritchevsky Wolf Process of treating wood
US2280560A (en) * 1936-03-28 1942-04-21 Pierre Schelameur Protective treatment for wood
GB822958A (en) * 1955-03-09 1959-11-04 Iroszergyar An improved process for the manufacture of pencil wood from non-cedar woods

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1810659A (en) * 1929-02-14 1931-06-16 Kritchevsky Wolf Process of treating wood
US2280560A (en) * 1936-03-28 1942-04-21 Pierre Schelameur Protective treatment for wood
GB822958A (en) * 1955-03-09 1959-11-04 Iroszergyar An improved process for the manufacture of pencil wood from non-cedar woods

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017084884A1 (de) * 2015-11-18 2017-05-26 SWISS KRONO Tec AG Osb (oriented strand board)-holzwerkstoffplatte mit verbesserten eigenschaften und verfahren zu deren herstellung
EP3170635B1 (de) * 2015-11-18 2017-12-13 SWISS KRONO Tec AG Osb (oriented strand board)-holzwerkstoffplatte mit verbesserten eigenschaften und verfahren zu deren herstellung
US10730202B2 (en) 2015-11-18 2020-08-04 SWISS KRONO Tec AG OSB (oriented strand board) wood material panel having improved properties and method for producing same
WO2017097506A1 (de) * 2015-12-07 2017-06-15 SWISS KRONO Tec AG Holzwerkstoffplatte mit reduzierter emission an flüchtigen organischen verbindungen (vocs) und verfahren zu deren herstellung
EP3178622B1 (de) * 2015-12-07 2018-07-04 SWISS KRONO Tec AG Verfahren zur herstellung einer holzwerkstoffplatte mit reduzierter emission an flüchtigen organischen verbindungen (vocs)
US10399245B2 (en) 2015-12-07 2019-09-03 SWISS KRONO Tec AG Wood material board with reduced emission of volatile organic compounds (VOCs) and method for the production thereof
US11148317B2 (en) 2015-12-07 2021-10-19 SWISS KRONO Tec AG Wood material board with reduced emission of volatile organic compounds (VOCs) and method for the production thereof
US11007668B2 (en) 2017-04-25 2021-05-18 SWISS KRONO Tec AG Process for the production of OSB wood-based boards with reduced emission of volatile organic compounds (VOCs)
US11904496B2 (en) 2017-04-25 2024-02-20 SWISS KRONO Tec AG Process for the production of OSB wood-based boards with reduced emission of volatile organic compounds (VOCs)

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