Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B7/00—Drying solid materials or objects by processes using a combination of processes not covered by a single one of groups F26B3/00 and F26B5/00
• • 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
• • 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
  • B27K3/44—Tar; Mineral oil
  • B27K3/48—Mineral oil
• • 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
  • B27K5/0085—Thermal treatments, i.e. involving chemical modification of wood at temperatures well over 100°C
• • 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

Definitions

• the invention relates to a wood treatment process in which lignocellulose-containing Materials are immersed in hot oil for a specified amount of time.
• a wood treatment process of the above type is the subject of DE 1 000 592. Das The impregnation process described in this document is used to remove oil or wood as quickly as possible other impregnating agents to change the properties of the wood Use of high frequency is said to soak at a temperature of the oil bath of 200 ° C in a few minutes. Resistance can be achieved by such a process only increase compared to wood-destroying fungi, provided that the biocides corresponding to the oil Adds funds.
• This type of heat treatment is disadvantageous however, in particular that at the required high temperatures (160-260 ° C) in a gas atmosphere due to the relatively poor heat transfer of gases and sensitivity of the entire remuneration process often an inhomogeneous remuneration with partial reduced resistance to wood-destroying fungi is achieved.
• Boiler pressure impregnation is particularly widespread as a wood preservation process.
• the Pressure impregnation has proven to be a very effective wood preservation process, however there are increasing concerns about the use of solutions containing heavy metals for reasons of environmental protection, because it cannot be excluded that these substances can be washed out of the wood over time and thereby into the ground and in reach the groundwater. There may be a hazard when performing the procedure of the persons entrusted with it and cause environmental damage from waste water.
• Wood preservation processes of the above type are recommended for wood products, that are exposed to the weather, for example in wooden buildings, fences or outdoors banks to be set up.
• Impregnation of tar oils practiced e.g. DE 4112643
• Heat treatments also for additional hardening of modified vegetable oils in impregnated wood e.g. WO 96/38275
• these procedures are only applicable to easily soakable types of wood applicable; types of wood that are difficult to soak cannot be compensated.
• the invention is based on the problem of a wood treatment method at the outset to develop the type mentioned, which leads to the highest possible, uniform protective effect of the material over the entire cross-section, but not for health reasons or requires substances of concern for environmental protection reasons, advantageous properties of the wood changed as little as possible and which with a the simplest possible system can be carried out.
• the method according to the invention occurs exactly as in the thermal treatment under protective gas to a preservative effect, without this for reasons of Environmentally harmful wood preservatives must be used. Because as a heat transfer medium however hot oil is used instead of protective gas, can be carried out during the implementation of the method work with relatively simple facilities, so that even smaller companies can apply the method according to the invention. Unlike other wood preservation processes, whose protective effect is based on impregnation with various substances, can also use this process to process impregnable, lignocellulosic materials such as. Spruce, poplar or bamboo due to the thermal transformation over the whole Cross-section can be coated homogeneously since no substances are introduced into the material Need to become.
• the protective effect is achieved by thermal conversion of the lignocellulose-containing Substance caused, the oil serves as a heat exchanger and shields that to be remunerated Material before exposure to oxygen. Escaping gases prevent penetration of the oil during the thermal treatment, e.g. just a few millimeters of wood oil-soaked and can be planed off so that oil-free tempered wood products are manufactured If necessary, easily soakable types of wood such as Pine sapwood be impregnated by cooling the oil after the thermal treatment.
• the treatment according to the invention is very homogeneous in oil and additionally for increased resistance to wood-destroying fungi, there is high dimensional stability of the wood.
• the necessary heating of the oil is usually possible for woodworking companies without significant additional costs, since waste wood is often generated in such companies, which can be burned to generate the required heat.
• the heated oil can be pumped out at the end of the treatment, as a result of which the thermal energy stored in the oil can be quickly transferred to other reactor vessels with little energy loss.
• the high oil temperatures of 180-260 ° C do not lead to any crack formation when in contact with moist lignocellulose-containing products. For example, freshly sawn, large-sized spruce scantlings with the dimensions 100x100x1350 mm 3 were thermally converted in hot rapeseed oil over the entire cross-section without cracks in an oil bath.
• the method according to the invention has so far been tested in practice in the case of pine and spruce wood, with improved dimensional stability and increased resistance to wood-destroying fungi being found in laboratory tests.
• a few hours are usually sufficient for the treatment; however, the remuneration period depends on the material moisture and the dimensions and can be several days if the values are high.
• a treatment time of 4.5 hours on samples with the dimensions 50x25x15 mm 3 and an initial wood moisture of 6% was tested and found to be sufficient.
• Fresh, untreated pine ( Pinus sylvestris L.) and spruce ( Picea abies L. Karst.) Were cut to the dimensions given in Table 1.
• the samples were heated with a wood moisture content of 6% at three temperatures (180 ° C, 200 ° C and 220 ° C) without pressure in an oil bath made of pressed, refined linseed oil with exclusion of oxygen. After reaching the desired temperature, the wood samples were immersed in the hot oil for 4.5 hours. The samples cooled in the oil bath for 15 minutes. Comparative samples were also treated in the drying cabinet at appropriate temperatures in an air atmosphere for 4.5 hours (no protection claim is made for the treatment in air).
• Mass change The mass increase WPG (Weight Percent Gain) of the oil-heat-treated samples was 50-70% (Table 2).
• the heat-treated samples in an air atmosphere showed mass losses depending on the treatment temperature of up to 10%. Since the oil content caused a mass increase, a possible loss of wood substance as a result of the oil heat treatment could not be determined exactly.
• ASE improvement of samples treated at 220 ° C was of a similar order of magnitude for both types of treatment, around 40% (Table 4). The degree of improvement was dependent on the relative humidity. The ASE decreased with increasing humidity, whereby samples treated with higher temperatures showed smaller differences than samples treated with lower temperatures.
• lignocellulose-containing material treated by the process according to the invention has increased dimensional stability, paint on the wood surface is better than untreated material.
• the lignocellulose-containing material treated by the process according to the invention has due to the oil loading in the later processing compared to the previously known Processed material has the advantage, among other things, that it is easier to machine edit and nails can be driven into it more easily. On top of that prevented by the oil from the formation of health-threatening fine dust or is at least greatly reduced.
• the oil loading in the process according to the invention easily adapted to the respective intended use of the products and for example for wood products to be brought into the ground are chosen higher than for those that are only exposed to weathering without earth contact.
• Another advantage of the method according to the invention is that the oil after Treatment is absorbed very quickly, so that a few minutes after the treatment results in a dry surface of the wooden parts.
• the resin stains that often occur during heat treatment in gas atmospheres on the Wood surface are avoided in the treatment according to the invention in an oil bath, because the leaking resin is evenly distributed in the oil.
• Linseed oil and rapeseed oil have been tried out in practice, with comparably good protective effects let achieve.
• An undesirable embrittlement of the lignocellulose-containing material can be reduced if the heat treatment is carried out in an oil bath in the absence of oxygen.
• the oil can also function as a surface coating agent take over when the liquid bath after heat treatment cooled with the material in it and then in the room climate air-conditioned and then heated to 60 to 180 ° C. By this cooling and Subsequent heating creates a closed, hardened surface on wood Oil film. This also means that the brown color created by the oil can be achieved the surface is more permanent, while otherwise oiled wood surfaces in the Nature quickly fades.
• the oil has an initial temperature of at least 180 ° C.
• fast energy-saving compensation is possible without causing cracking on the wood surface of materials containing lignocellulose, also with moisture content comes about fiber saturation and larger dimensions.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)

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• 1998
  • 1998-11-17 DE DE19852827A patent/DE19852827A1/de not_active Withdrawn
• 1999
  • 1999-11-06 DE DE59908408T patent/DE59908408D1/de not_active Expired - Lifetime
  • 1999-11-06 EP EP99122192A patent/EP1002630B1/fr not_active Expired - Lifetime
  • 1999-11-06 AT AT99122192T patent/ATE258486T1/de active
  • 1999-11-17 US US09/441,370 patent/US6217939B1/en not_active Expired - Lifetime
  • 1999-11-17 CA CA002289867A patent/CA2289867C/fr not_active Expired - Lifetime

Patent Citations (7)

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