FI104706B - Ways to attach oil to wood - Google Patents

Abstract

The invention relates to a method for binding oil to wood and to a composition used in the method. According to the invention a wood product is contacted with a composition containing a solid anhydride, vegetable oil and alcohol. The treated wood product is dried and then subjected to a heat treatment at a temperature above 150 DEG C in order to bind the oil. The vegetable oil used preferably comprises at least one double bond, such as linseed oil, tall oil or rapeseed oil, and the anhydride used comprises maleic anhydride, succinic anhydride or phthalic anhydride. An auxiliary solvent, i.e. a lower aliphatic alcohol is used in order to help mixing the oil with the anhydride. By means of the invention the oil is so well bound to the wood that no oil seeps out of the wood even if it is heated above 70 DEG C. The oil-treated products can be used for outdoor furniture and boat boards.

Description

104706

A method of attaching oil to wood

The present invention relates to a method for attaching an oil Ί 5 to a wood according to the preamble of claim 1.

The invention also relates to a modified wood product according to the preamble of claim 9.

Wood products have long been treated with various oils to reduce water absorption and provide a water and dirt repellent surface.

Oil often leaves behind a sticky surface that is uncomfortable to use. Therefore, according to the application, the oil has been fixed to the wood so that no seepage occurs. One way to fix the oil is by oxidizing its double bonds. On the other hand, various methods for chemical swelling of wood have been used to reduce humidity living. The latest ones are based on a chemical reaction with hydroxyl groups of wood using a mixture of, for example, maleic anhydride and glycerol.

There are significant drawbacks to known fastening methods. Thus, the double bonds I

the oxidation process is slow and not reliable. The method does not work at all,.:. if the temperature rises high enough. Oil leaks out of the wood. Chemical edema; . . The methods are generally water soluble (PEG) and leach over time or are "very toxic." In acid anhydride methods, the anhydride is dissolved in alcohol or in the

25 to another solvent which together with water can be made into a useful I

• * ^ ·. · · Non-precipitating solution. The pH of such a solution is very low, e.g. maleic glycerol • · · V: about 1. As a result of the low pH (1-2), the strength of the wood is reduced, the 'r' acidity remaining in the wood may affect long-term durability and cause e.g. iron rust “··· • · · - where. _ '3o _.........

It is an object of the present invention to overcome the drawbacks of the prior art and to provide a novel solution for fixing oil to wood.

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2 104706

The invention is based on the idea of providing a treatment composition comprising at least one vegetable oil, at least one acid anhydride, and at least one alcohol miscible with the oil and the acid anhydride. The acid anhydride is then mixed with the oil using alcohol as a cosolvent. The composition is impregnated with the desired amount of 5 wood products, the treated wood product is dried and the oil is fixed to the wood by heat at temperatures above 150 ° C.

More specifically, the method according to the invention is essentially characterized in what is stated in the characterizing part of claim 1.

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The wood product according to the invention, in turn, is characterized by what is stated in the characterizing part of claim 9.

It is essential for the invention to polymerize the oil absorbed into the wood to form a solid which does not penetrate the wood surface even at a temperature of 100 ° C, as well as to reduce the humidity of the wood and maintain the compression form.

The vegetable oils used in the invention may be derived from annual or perennial plants.

Typical oils from plant seeds are obtained, for example, from rapeseed, rape, 20 sunflowers, flax, soybean, cotton, peanut, pumpkin, castor oil. · Sesame, coconut, cocoa and almond. Oils derived from oil-containing fruits such as olives may also be used. In addition to these, the following are also suitable: .j .: Crude tall oil obtained as a by-product of pulp cooking and, eg, steam distillation from wood, eg · · ·. **: Oils to be separated, such as tall oil, tall oil premix and turpentine oils. For all the above oils, it is typical that they contain at least one double bond.

• ♦ · '· *' However, many vegetable oils are polyunsaturated, meaning they have multiple, usually ... conjugated double bonds.

• · · 9 9 9 <II '- I I t I i; It will be appreciated that synthetic oils containing at least one double bond may be used in place of the above-described oils. These oils may be prepared from oligomers of short and long chain olefins.

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Mixtures containing two or more oils, at least one of which is mentioned above, may be used in the compositions of the invention.

Vegetable oil is used in combination with an acid anhydride or similar reactive compound '5 which is capable of effecting esterification reactions in wood (esterifying component). In one aspect, the invention includes the use of acid anhydrides for attaching oily substances to wood. The acid anhydrides may be aliphatic or aromatic. Anhydrides derived from dicarboxylic acids are preferred. Of the aromatic acid anhydrides, those containing one benzene ring are preferred, and of the aliphatic acid, the saturated or unsaturated acid anhydrides containing from 4 to 6 carbon atoms are preferred. At room temperature these substances are solid. 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, preferably a lower aliphatic alcohol having from 1 to 6 carbon atoms, such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol or any pentanol or hexanol. Alcohol is required to be miscible with oil and acid anhydride. Most suitable alcohols are capable of dissolving, at least to some extent, the acid anhydride used.

20 Without an intermediate or co-solvent, the acid anhydride or the corresponding esterifying component and the oil can be seen ~; do not mix. Ethanol has proven to be a particularly advantageous co-solvent.

·:: The alcohol used in the invention contains up to a small amount of water.

: .I '. Most preferably, absolute alcohol is used, wherein the amount of water corresponds to the amount of alcohol / water azeotrope. Typically, the alcohol has a concentration of greater than 90%, preferably greater than 95% .25%.

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The term "co-solvent" includes all solvents, i.e., solvents, which are miscible with other components of the compositions, mainly oil (s) and acid anhydride. The compositions of the invention are typically emulsions having oil and anhydride phases. However, at least some of the anhydride, and even oil, may be present dissolved in alcohol. However, for simplicity, the compositions will hereinafter be referred to as emulsions rather than solutions.

4 104706 By "wood product to be treated" is meant a wood product according to the present invention whose shape or properties are to be altered. For example, it is desired to place the wood product in a plasticizable or plastic space for shaping it or to treat the wood to improve its shape stability and especially its surface hardness. Typically, the product to be treated according to the invention 5 will have at least a moderate thickness, usually greater than about 5 mm (= massive piece of wood). It may be a solid piece of solid wood, but it may also comprise a layered product (e.g., particle board or fibreboard) formed of wood veneer or chips, e.g. The wood product may also consist of a structure in which uniform layers of wood are bonded together to form a laminate. In the latter case, a wood product is defined as a laminate or laminate product which can be impregnated either before or after product formation.

The process of the invention comprises three steps, treating the wood pieces with the composition of the invention, drying the wood pieces and heat treating them (attaching the oil component to the wood by heat).

In the first step, the wood pieces are typically impregnated with an acid anhydride, oil, and alcohol emulsion. The emulsion may also contain additives known from the use of acid anhydride, such as glycerol. Such a mixture is prepared by mixing together; 1 to 1000 parts by weight of acid anhydride, 1 to 1000 parts by weight of vegetable oil and 1 to 1000 parts by weight of alcohol. Preferred mixture ratios are as follows (in the order of acid anhydride: oil: alcohol): 1-20: 1-100: 1-100.

Preferably, the wood emulsion is impregnated with the emulsion shown, wherein the weight ratio of maleic acid * anhydride to oil is 1:10 to 10:10. Preferably, a moderately concentrated composition is used wherein the concentration of the above-mentioned components is about 1 to 99% by weight, preferably about 20 to 85%, most preferably about 40 to 70%.

• · · '·' ··. 30 The amount of emulsion to be impregnated into the wood product varies with the application of the wood product and f ♦ · •. according to the wood raw material (wood species, density and moisture content of the wood). Usually wood ... so much substance is always absorbed into the substance that it can penetrate substantially

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5, 104706

deeper than the surface of the wood product. Wood Moisture Reduction and Compressed Wood I

it is important for stabilization that the wood product contains a lot of oil. Thus, preferably, at least about 20 kg, preferably about 25 to 300 kg, and particularly preferably about 30 to 140 kg, of the disclosed composition are always absorbed per cubic meter. Preferably, the moisture content of the wood 5 to be introduced is maintained at a value of 5-30%, particularly preferably at a value of 6-7%.

The impregnation may be carried out by first removing air from the wood material in a vacuum vessel under vacuum, after which the liquid to be absorbed is introduced into the vessel and allowed to be absorbed at normal pressure or possibly at a pressure (so-called vacuum method).

Alternatively, the wood material is immersed in the impregnation fluid for such a time that the composition 10 is able to be absorbed deep into the wood (immersion method). When it is desired to apply the vegetable oil / acid anhydride only to the surface of the wood, the impregnation may also be carried out as a surface coat.

After the oil / modification chemical treatment, the wood product is slowly dried at a low temperature whereby the co-solvent is removed leaving the active chemical in the wood. The drying is continued until the moisture content of the wood product is at least less than 20%, preferably even less than 15-17%. The drying may be carried out at room temperature, but it is preferable to perform it at an elevated temperature of less than 100 ° C, in particular 50 to 100 ° C. The temperature is determined by the alcohol used. Particularly in the case of ethanol, it is preferable to carry out drying at about 70 ° C. For heat treatment, any apparatus known in the art, such as a drying oven, oven, etc., can be used to dry a piece of wood, with or without water vapor.

According to a preferred alternative, drying of the oil-treated wood product is carried out; 25 so that the temperatures of the interior of the wood product and of the outer surface of the wood, respectively, are continuously determined and the difference between them is kept consistently low. Most preferably, said temperature difference is at most about 30 ° C. The "indoor temperature" of a wood is then · · * the temperature at which it is at some distance from the outside of the wood.

Depending on the shape of the piece of wood, the "indoor temperature" is typically measured at a depth of at least about 2 to about 5 cm. "Outdoor temperature" means the temperature of the wood surface or slightly I

below. Thus, in many cases, the "outdoor temperature" corresponds substantially to the ambient temperature. The temperature is gradually increased so that the temperature difference between the wood surface and the inner part is constant at least about 5 ° C and does not increase to 30 ° C. Preferably, the temperature difference is maintained at 10-30 ° C. This solution can be implemented by providing at least two sensors 5, one for measuring the internal temperature of the wood and one for the surface temperature. When drying larger quantities of wood, more specimens should be equipped with sensors. The industrial scale formula preferably operates by determining from the measurement results a suitable heating program for each timber, which takes into account the effect of the initial humidity on the process.

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After drying, the oil component is fixed to the wood product, for example, in a heating cabinet at at least about 150 ° C, usually at about 150-250 ° C. For maleic anhydride, a preferred temperature range has been found to be 160-180 ° C. The heat treatment time is typically about 10 min to 24 h; however, the setting or curing time varies according to the size of the article and the components of the treatment composition; Pite spiders or even shorter times can be used. In practice, it has been found that particularly advantageous results are obtained if the temperature of the whole piece is the above-mentioned furnace temperature for at least 2 hours.

20 During heat treatment, the volatile constituents evaporate, which promotes crosslinking reactions in wood.

• ·

The invention provides considerable advantages. Thus, the oil is well bonded to • 1 · · · wood and does not ooze out at elevated temperatures (even at temperatures above 100 ° C • 1 1 I · · *: 2.25 ° C). The treatment reduces the moisture content of the wood by up to 1/5 and stabilizes the compressed • 1 1 wood to be moisture resistant. The pH of the solution used remains neutral.

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The invention provides a modified wood product containing (in addition to any possible solvent residues) acid anhydride and vegetable oil and optionally their reactants. 30 thio products.

3 · 2 ... Wood products treated by the invention which do not substantially exude an oil may be present

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i. 1 7 104706 is particularly advantageously used for furniture, boat boards, wooden bridge beams, structures for wet areas, outdoor furniture, environmental structures (noise barriers) and the like.

1 The invention will now be explained in more detail by way of an exemplary embodiment.

5

Example

The specimens were processed as follows: 10 Solutions of vegetable oil, maleic anhydride and co-solvent were prepared, the compositions of which are shown in Tables 1 and 2. The solutions were impregnated into 20x40x400 mm pieces of wood. After soaking, the treated specimens were intermediate dried at 70 ° C. The specimens were then cured at 160 ° C in a heating cabinet. The cure time varied according to the size of the piece (about 2 to 6 hours). However, the temperature of the piece 15 as a whole was the above-mentioned furnace temperature for at least 2 hours. - = The moisture content (thickness and width swelling) of the specimens was determined by measuring the dimensions of the specimens in absolute dryness and after soaking.

20

; For the purpose of comparison, wood pieces oiled and dried at elevated temperature were also produced in the conventional manner. No anhydride or I was used to fix the oils

(· Above 150 ° C.) The linen oil-impregnated pieces were first kept for 3 days at 50 • 1 1 «t« ° C. They were then transferred for 1 day to 70 ° C, whereby the oil oozed out I · fj III - 25 removed about 1.5% of the weight of the specimen, and the specimens were dropped for another day at 70 Ϊ · ° C, and the weight dropped by 0.4%, as compared to those impregnated with linseed oil that were not stored in the oven. At 3 ° C (1 day), the specimens were greasy.

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In each set of experiments according to the invention, there was also at least one sample which was treated at &gt; 150 ° C but which did not contain acid anhydride.

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The following Table 1 shows the swelling of birch bodies impregnated with various mixtures (maleic anhydride, oil, ethanol) according to the invention for 1 day and 21 days in aqueous solution.

5 Table 1. Wood Moisture Life

Thickness swelling,% Width swelling,% M-ÖF * Γ - 1 day 21 day 1 day 21 day

Linseed Oil 10 (1: 1: 1) 0.80 1.82 1.42 3.07 (0: 1: 1) 2.35 7.44 2.52 7.54

Rapeseed oil (1: 1: 1) 0.35 0.41 0.59 1.23 15 (0: 1: 1) 1.78 5.11 3.50 10.58 Tall oil (1: 1: 1) 0, 49 0.90 1.17 3.35 (1: 2.5: 2.5) 0.66 2.34 1.15 4.52 (1: 5: 6) 1.02 3.08 1.26 3 , 74 20 (0: 1: 1) 1.14 3.12 1.68 4.73. Control 8.52 8.89 11.53 12.51 25 *) M = maleic anhydride \ 'ί Ö = vegetable oil i E = ethanol «m t ···; 30

The samples according to the invention had a dry surface and did not leak oil even at a temperature of 70 ° C. The humidity of the pieces is also very small. The table still holds «Il page! It is clear that the addition of an acid anhydride to the treatment composition reduces the amount of swelling over 50%. The more acid anhydride contained in the composition, the less; '· The 35-year-old tree swelled.

»>« · · 4 ♦ j '·': Table 2 below shows the various mixtures (maleic anhydride, oil, ethanol) i *

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ϊ 9 104706 thickness swelling of impregnated and then 30% compressed birch bodies in 1 day and 21 days in aqueous solution.

Table 2. Stabilization of Compressed Wood 5

Thickness swelling,% M: Ö: E * f __l_vrk__21 days__

Linseed Oil (1: 1: 1) 3.42 5.79 10 (0: 1: 1) __ 3UJ_ 33.71_

Rapeseed oil (1: 1: 1) 1.41 6.83 (0: 1: 1) 28.51 35.97 Tall oil 15 (1: 1: 1) 1.82 9.50 (1: 2.5: 2) , 5) 1.43 12.14 (1: 5: 6) 3.54 17.59 (0: 1: 1) 26.44 37.07 20. *) M = maleic anhydride δ = vegetable oil. ; ; E = ethanol. Table 2 shows, even more clearly than Table 1, the beneficial effect of the acid anhydride on i ... ...

>, · · Wood stabilization.

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Claims (9)

A process for bonding oil to wood, according to which process - a wood product is contacted with a composition containing a solid acid anhydride, a vegetable oil and an alcohol, characterized in that - the wood product treated with said composition is dried at a temperature of about 50-100 ° C, and then it is subjected to a heat treatment which occurs at a temperature above 150 ° C to bind the oil to the wood. 10 Process according to Claim 1, characterized in that as plant oil an oil containing at least one double bond is used. 3. Process according to claim 1 or 2, characterized in that as vegetable oil 15, rape, rapeseed, sunflower, lime, soy, cotton, peanut, pumpkin, castor, sesame, coconut, cocoa, almond or olive oil, or crude tall oil, distilled tall oil, a distillate of tall oil or turpentine oil or a mixture thereof. 4. A process according to claim 1, 2 or 3, characterized in that, as aliphatic alcohol, a lower aliphatic alcohol such as ethanol is used. . Process according to any one of claims 1-4, characterized in that as an anhydride • 1 ·. maleic anhydride, succinic anhydride or phthalic anhydride were used. • · · • · · • • • «r •« r • e: 25 Process according to any of the preceding claims, characterized in that the composition contains at least a small amount of glycerol. · · Rt1 Process according to any of the preceding claims, characterized in that the wood product is treated with the composition by impregnating, pressure-impregnating the wood or; . Vacuum is impregnated with the composition. I f «·, 3 104706 8. A method according to any one of claims 1-7, characterized in that a wood product is used which is used for interior and exterior furniture, wooden boards, wooden beams, wet room structures and environmental constructions. 9. Modified wood product, characterized in that it is manufactured by a method according to any of claims 1-8. • • • • • • • • • • • • • • • • • • • • • • • • f • 1 • · • · · · · «· · '··« • · «_ • · ·» ♦ · »1 #« t «« I • «·» I ~ • · • «· · I» «• · ·