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
  • B27K3/15—Impregnating involving polymerisation including use of polymer-containing 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
  • 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
  • B27K3/15—Impregnating involving polymerisation including use of polymer-containing impregnating agents
  • B27K3/156—Combined with grafting onto wood fibres
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
  • C08L91/005—Drying oils
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L97/00—Compositions of lignin-containing materials
  • C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/05—Alcohols; Metal alcoholates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof

Definitions

• the present invention concerns a method according to the preamble of claim 1 for binding oil to wood.
• the invention also relates to a composition according to the preamble of claim 11, which is suitable for oil treatment of wood.
• the surface of wood treated with oil is often tacky, which makes the use of the wood rather uncomfortable.
• the oil has therefore been bound to the wood so as to prevent any seeping from taking place.
• One way of binding oil is based on oxidation of its double bonds.
• different methods based on chemical swelling of the wood have been used. The newest methods are based on chemical reactions with the hydroxyl groups in wood by using a mixture of, e.g., maleic anhydride and glycerol.
• the invention is based on the concept of formulating a treatment substance composition containing at least one vegetable oil, at least one anhydride and at least one alcohol which is miscible with the oil and the anhydride.
• the anhydride is mixed with the oil by using the alcohol as an auxiliary solvent.
• the wood product is impregnated with a desired amount of the composition and the oil is bound to the wood by means of heat.
• the method according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.
• composition according to the invention is characterized by what is stated in the characterizing part of claim 11.
• Essential features of the invention comprise polymerizing absorbed oil in the interior parts of the wood to form a solid substance, which does not submerge to the surface of the wood even at temperatures up to 100 °C, and reducing swelling and retaining the form of compressed wood.
• the vegetable oils used in the invention can be derived from annual or perennial plants. Typical oils pressed from plant seeds can be obtained, for example, from rapeseed, rubsen, sunflower, linen, soybean, cotton, peanut, pumpkin, ricinus, sesame, coconut, cocoa and almond. It is also possible to use oils produced from oil-containing fruits, such as olives.
• oils suitable are also raw tall oil obtained as a side product of cellulose pulping, and oils which can be separated from wood by, for example, steam distillation, such as pine oil, fore-runs of pine oil and mixtures of turpentine oil.
• a common feature of all the above mentioned oils is that they contain at least one double bond. Many of the vegetable oils are, however, multi- unsaturated, i.e. they contain several, usually conjugated, double bonds.
• oils instead of the afore-mentioned oils, synthetic oils containing at least one double bond can be used. These oils can be prepared from short- and long-chained olefins by oligomerization.
• compositions containing mixtures of two or more oils at least one of which belongs to the above mentioned oils.
• anhydrides are used for binding oily substances to wood.
• the anhydrides can be aliphatic or aromatic.
• Pre- ferably anhydrides derived from dicarboxylic acids are used.
• aromatic anhydrides it is preferred to use compounds containing one benzene ring, and of the aliphatic, it is preferred to use saturated or unsaturated anhydrides containing 4 to 6 carbon atoms. These compounds are solid substances at room temperature.
• Particularly preferred examples are maleic anhydride, succinic anhydride, glutaric anhydride and phthalic anhydride.
• the alcohol used in the invention is an aliphatic or aromatic alcohol or phenol, pre ⁇ ferably a lower aliphatic alcohol containing 1 to 6 carbon atoms, such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol or a pentanol or hexanol. It is required that the alcohol is miscible with the oil and the anhydride. Most of the suitable alcohols are capable of at least partially dissolving the anhydride used. Without an intermediate or auxiliary solvent the anhydride or the corresponding esterifying component and the oil do not mix with each other. Ethanol has found to be a particularly advantageous auxiliary solvent.
• the alcohol used in the invention contains at the most small amounts of water.
• Preferably absolute alcohol is used having a water content corresponding to amount of water in an azeotropic mixture of alcohol and water.
• concentration of the alcohol is, thus, above 90 %, preferably above 95 %.
• auxiliary solvent comprises all solvents which are miscible with the other components of the compositions, in particular with the oil (oils) and the anhydride
• compositions according to the invention are typically emulsions which contain an oil and an anhydride phase. At least a part of the anhydride and even of the oil can, however, be dissolved in the alcohol. For the sake of simplicity, in the following the compositions are called emulsions rather than solutions.
• the term "the wood product to be treated” denotes a product made of wood whose shape or properties are to be changed. Thus, it may be desired to bring the wood product into, e.g., a plastic form in order to shape it, or wood is treated in order to improve its dimensional stability, in particular its surface hardness.
• the wood product can also comprise a structure wherein uniform wood layers are bonded together to form a laminate.
• wood product denotes a layered or laminated product which can be impregnated either before it is formed into a product or thereafter.
• the method according to the invention comprises three stages, viz. a treatment of wood pieces with a composition according to the invention; drying of the wood pieces; and heat treatment of them (in order to bind the oil component to wood by means of heat).
• the wood pieces are typically impregnated with an emulsion containing anhydride, oil and alcohol.
• the emulsion can also contain additives known from the use of anhydrides, such as glycerol.
• a mixture of the present kind is prepared by mixing together 1 to 1000 parts by weight of an anhydride, 1 to 1000 parts by weight of vegetable oil and 1 to 1000 parts by weight of alcohol.
• Preferred mixing ratios are the following: 1 to 20 : 1 to 100 : 1 to 100.
• me wood raw material is impregnated with an emulsion of the presented kind having a weight ratio between the maleic anhydride and oil amounting to from 1:10 to 10:10.
• a rather concentrated composition is used containing the afore ⁇ mentioned components at a concentration of about 1 to 99 weight- %, preferably about 20 to 85 % , in particular about 40 to 70 % .
• the amount of emulsion to be impregnated into the wood product depends on application of the wood product and on the raw material (species, density and moisture) of the wood. Usually so much substance is impregnated into the wood substance that it penetrates essentially deeper than superficially into the wood.
• the wood product contains a large amount of oil.
• the said composition is impregnated in an amount of at least about 20 kg, preferably about 25 to 300 kg and in particular about 30 to 140 kg.
• the moismre content of the wood which is to be subjected to impregnation is preferably 5 to 30 % , in particular about 6 to 7 % .
• the impregnation can be carried out by removing air from the wood at reduced pressure in a pressure vessel.
• liquid which is to be used for impregnation is fed into the vessel and the wood is impregnated therewith at normal pressure or, possibly, at overpressure (a method known as the vacuum-pressure-method).
• the wood material is immersed into an impregnation liquid for such a long time that the composition has ample time to penetrate deep into the wood (the immersion method).
• the impregnation can also be carried out by surface coating.
• the wood product is dried slowly at a low temperature in order to remove the auxiliary solvent and to deposit the active chemical in the wood. Drying is continued until the moisture content of the wood product is at least below 20 % , preferably even below 15 to 17 % . Drying can be carried out at room temperature, but it is preferred to carry it out at an elevated temperature which is below 100 °C. The temperature depends on the alcohol used. In particular in the case of ethanol drying is preferably carried out at a temperature in the range of 20 to 99 °C, advantageously 30 to 95 °C, typically at about 70 °C. Any known device can be used for the heat treatment such a drying oven, a heating chamber or an equivalent apparatus which can be used for drying the wood piece in the presence of steam or without it.
• the oil-treated wood product is dried by continuously determining the interior temperature and the temperature on the surface of the wood product and by continuously maintaining the difference between them rather small.
• Advantageously said temperature difference is 30 °C at the most.
• the interior temperature of the wood is meant the temperature which can be measured in the wood at some distance from the outer surface of it.
• the "interior temperature” is typically measured at a depth of at least about 2 to 5 cm.
• the term “outer temperature” is meant the temperature on the wood surface or slightly below it. In many cases, the "outer temperature” thus essentially corresponds to ambient temperature.
• the temperature is gradually increased so that the temperature difference between the surface of the wood and the interior parts thereof remains constant with a deviation of about 5 °C at the most and not greater than 30 °C.
• the temperature difference is kept at 10 to 30 °C.
• This solution can be carried out by attaching at least two sensors to a test specimen, one of the sensors measuring the interior temperature of the wood and the other the surface temperature thereof.
• a suitable heating program is determined for each group of lumber, whereby the heating program takes account of the initial moisture content on the process.
• a temperature of at least about 150 °C usually about 150 to 250 °C.
• a preferred temperature range comprises 160 to 180 °C.
• the duration of the heat treatment is typically about 10 min to 24 h; the binding or fixing time depends, however, on the size of the piece and the components of the treatment composition. Longer or even shorter periods of time can be used. In practice, it has been found that particularly advantageous results are obtained if the temperature of the whole piece corresponds to the temperature of the oven for a time period of at least 2 hours.
• the invention will provide a modified wood product which contains (in addition to solvent residues, if any) anhydride and vegetable oil and, possibly, reaction products thereof.
• Wood products which have been treated according to the invention which a free from seeping oil, can advantageously be used for the following applications: furniture, boat boards, wooden bridge beams, constructions in humid spaces, outdoor furniture, environmental constructions (noise barriers) etc.
• test specimens were treated as follows:
• Solutions consisting of a vegetable oil, maleic anhydride and an auxiliary solvent were formulated. Their compositions are indicated in Tables 1 and 2. Pieces of wood having the dimensions 20x40x400 mm were impregnated with the solutions. After impregnation the treated samples were subjected to an intermediate drying step at 70 °C. Then, the samples were hardened at a temperature of 160 °C. The hardening time depended on the size of the sample (about 2 to 6 hours). The temperature of the whole sample was, however, the above-mentioned oven temperature for at least 2 hours.
• the (thickness and lateral) swelling of the samples was determined by measuring the dimensions of the samples at absolute dryness and after immersion into water.
• Pieces of wood that had been subjected to a conventional treatment with oil and drying at an increased temperature were used as controls. No anhydride had been used for the binding of the oils nor was the temperature raised above 150 °C.
• the samples treated with linseed oil were first kept for 3 days at 50 °C. Then, for 1 day, they were subjected to a temperature of 70 °C. As a result some 1.5 % oil (calculated on basis of the weight of the sample) seeped out of the sample. When the samples were subjected to a further treatment for 1 day at 70 °C, their weight dropped by a further 0.4 %.
• Control samples also comprised test specimens impregnated with linseed oil which had not been kept in a heating chamber. The weight of these changed by about 3 % at 70 °C (1 day). The surface of the test specimens was greasy.
• test series according to the invention contained at least one sample which had been treated at a temperature above 150 °C but which did not contain acid anhydride.
• Table 1 there is indicated the swelling of birch samples impregnated according to the invention with different compositions (maleic anhydride, oil, ethanol) and immersed for 1 day and 21 days, respectively, into water.
• the surface of the samples according to the invention was dry and no oil seeped out of them, not even at a temperature of 70 °C.
• the swelling of the samples is also very small. It clearly appears from the table that the addition of an anhydride to a treatment composition decreases swelling by over 50 %. The more anhydride the composition contained the less swelling of the wood could be noticed.

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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Materials Engineering (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Adhesives Or Adhesive Processes (AREA)

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Cited By (9)

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Citations (2)

• 1995
  • 1995-05-31 FI FI952654A patent/FI104706B/sv not_active IP Right Cessation
• 1996
  • 1996-05-31 WO PCT/FI1996/000329 patent/WO1996038275A1/en active Application Filing
  • 1996-05-31 AU AU58237/96A patent/AU5823796A/en not_active Abandoned
• 1997
  • 1997-11-28 SE SE9704395A patent/SE509980C2/sv not_active IP Right Cessation

Patent Citations (2)

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