CH713651A2 - Process for producing impregnated lumber products. - Google Patents

Abstract

The invention relates to a method for the production of obliquely cut lumber products with respect to longitudinally cut wood parts increased hardness and increased absorption capacity for liquid wood-modifying substances, wherein an elongated wooden blank with longitudinally arranged Baumleitgefässen at an angle between 3 and 30 degrees, relative to its longitudinal axis , is cut obliquely, so that at least a part of the tree guide vessels located in the timber blank is cut or cut through the incision obliquely. The invention further relates to sawn timber products thus produced and their use.

Description

description

TECHNICAL FIELD The present invention relates to a method for producing sawn timber with increased absorbency for liquid wood-modifying substances.

PRIOR ART The trend in the wood industry is moving away from layer-forming paints towards wood treatment processes, in particular surface treatments, which allow the wood-modifying substances to penetrate into the wood. The wood produced in this way looks more natural and the substances cannot peel off.

Normally, tree trunks are cut as precisely as possible along the longitudinal axis of the trunk or parallel to the longitudinal axis of the trunk and processed to saw products such as boards, planks, posts, prisms or veneers. It is also known and customary that wood is cut transversely to the trunk axis, that is to say at an angle of 90 degrees to the trunk axis, as what is known as “end grain”, which can be used, for example, to produce end grain floors.

Woods that are cut parallel to the trunk axis, however, have only a very limited absorption capacity and loading capacity for liquid wood-modifying substances, in short: impregnating agents. There is therefore a need for a method which can increase the absorption capacity and loading capacity of sawn timber for loading with impregnating agents of all kinds and which is suitable for use in industrial sawn timber production and processing. Such a method is defined in claim 1, further advantageous embodiments are described in the dependent claims.

DESCRIPTION OF THE INVENTION In the course of the present invention, it has been found that in the case of woods which are cut parallel to the trunk axis, the absorption capacity for liquid impregnating agents which are intended to penetrate the wood is very limited. However, as soon as the tree guide vessels - quasi the "veins" of the tree - are cut, the absorption capacity increases immediately, even at very small, flat cutting angles, in relation to the longitudinal axis of the tree trunk or branch. Since tree trunks and branches do not always run straight and the tree guide vessels do not run strictly straight, there can also be several such zones with diagonally cut tree guide vessels in a longer board, with slightly different orientations, so that different loading properties occur over the length of the board, as well as one varied, visual appearance is created.

By a pre-selected incision angle, these desired properties can be induced on the entire board. Overall, this measure in any case results in a significantly increased absorption capacity for liquid impregnation materials compared to wood which is conventionally cut along the longitudinal axis of the trunk or parallel to it. This also improves the uniformity of the surface treatment.

The invention therefore relates, in a first embodiment, to a method for increasing the absorption capacity of sawn timber for liquid wood-modifying substances, an elongated wood blank with tree guide vessels arranged in the longitudinal direction, in particular a tree trunk, branch or an elongated part of a tree trunk or branch, is cut at an angle between 0 and 75 degrees, in particular from 3 to 30 degrees, with respect to its longitudinal axis, so that at least a part, as a rule the whole, of the tree guide vessels located in the wood blank is cut or cut obliquely through the cut.

Wooden parts made in accordance with this invention are typically cut at an angle between 0 and 75 degrees, preferably in a range of 3 to 30 degrees, to the longitudinal axis. As a further, positive side effect, this cutting direction results in a new, characteristic sectional image with a certain sequence of open or closed, oval or elliptical annual rings, which is reminiscent of a rift or semi-rift pattern. It is surprising that even structurally poor woods such as beech, maple or birch not only get a new cut pattern due to the diagonal cut, but also a detailed, differentiated wood drawing that they are completely lacking in conventional longitudinal cuts.

The invention also relates to such obliquely cut wooden parts and sawn timber products with increased absorption capacity for liquid wood-modifying substances, in which at least part, usually all, of the tree guide vessels present in the sawn timber product are cut or cut obliquely through the incision. This is the result of the oblique incision of an elongated wood blank, which has tree guiding vessels running in the longitudinal direction, at an angle between 0 and 75 degrees, in particular at an angle of 3 to 30 degrees, with respect to the longitudinal axis of the wood blank. The wooden blank can be a tree trunk, a branch or an elongated part of a tree trunk or branch made therefrom according to the conventional incision method.

The wooden parts produced according to the invention can be loaded with all conventional wood-modifying substances of natural or synthetic origin. These are primarily lacquers, mordants, colorants, natural resins, synthetic resins, bleaches, substances for changing the pH, waxes, oils, tannins and / or other wood-modifying substances.

CH 713 651 A2 Processes for treating wood, in particular sawn wood, with wood-modifying substances are known in the prior art (see, for example, EP 0 891 244 B1, entire document) and include processes such as spraying, coating, soaking by immersion or Immersion and others. Also known from EP 0 891 244 B1 are numerous substances that can be used for wood modification, such as cited in claims 2 to 6 of EP 0 891 244 B1.

These include, for example, biodegradable polymers such as polyhydroxybutyric acids, polycaprolactones, polylactic acids, polyesters based on diols and dicarboxylic acids, polyamides, polyester urethanes, chemically modified natural polymers such as e.g. cellulose acetates; but also fats, oils, waxes, lignin, alcohols. The fats can be hardened or modified, animal and vegetable fats, e.g. hydrogenated vegetable fats, epoxidized oils, wool fat, tallow, but also salts of various fatty acids, e.g. Stearic acid, behenic acid, or lauric acid.

Various salts, such as. B. phosphates, borates, sulfates, chlorides, or silicates can be used together with the liquid substances or substance mixtures for wood impregnation. They can have a positive influence on the reduction in swelling and shrinking behavior, but are also flame-retardant and / or fungicidal.

Glycerin can be used as a «solvent», plasticizer or humectant, while alkali and alkaline earth metal salts act as drying agents, but can also be used as wetting agents and emulsifiers and thereby promote the penetration behavior of molten resins into the wood.

To change the pH, for example sodium hydroxide solution or citric acid can be used. “Other wood modification substances” include substances such as acetic anhydride or furfuryl alcohol.

Insofar as reference is made to “liquid” wood-modifying substances, this is to be understood to mean both liquid agents at room temperature and those which are solid at room temperature but melted by heating or heating and then used in liquid form to impregnate the woods can be. This includes e.g. most resins and waxes.

The impregnation of the wooden parts according to the invention differs significantly from that for conventionally cut saw products, since the absorption capacity of the wooden parts according to the invention is considerably increased for any type of wood-modifying substances. This is particularly evident in the fact that most substances penetrate deep into the wood and form an intimate connection with the wood substance. This surprisingly makes it possible to color wooden parts over the entire cross-section or to load them with tannins, which is practically impossible with conventionally produced sawn wood parts.

An effect of this substantially increased substance absorption is that these wooden parts even with larger layer thicknesses, i.e. in a range of 5 to 20 mm, can be made translucent. On the other hand, because of this increased absorption capacity, it becomes somewhat more difficult to achieve a greater layer thickness of a desired impregnating agent on the wood surface, as is usually desired, for example, with lacquered wood surfaces. Here you can manage with a multi-layer paint structure and / or by increasing the viscosity of the corresponding paint.

Contrary to the previous experience in the impregnation of covered woods, such as spruce, it is now possible to load these types of wood with a wide variety of substances, that is, to modify and thus significantly improve their performance properties. “Hiding” means the spontaneous closure of the tree guide vessels immediately after felling, as can be seen particularly in spruce wood. Another positive side effect of this type of cut is that the hardness, in contrast to wooden parts made from longitudinal cuts, is significantly increased or can be increased by hardness-modifying substances.

The production of the wooden parts according to the invention can be carried out in that a wooden blank, usually a tree trunk or branch, is clamped in a suitable saw, for example a band saw, in such a way that a cutting angle in a range between 0 and 75 degrees, in particular in one Range of 3 to 30 degrees to the longitudinal axis of the tree trunk is reached in one operation.

Alternatively, you can also use a first saw, e.g. a frame saw, produce elongated wooden blanks in the form of posts, planks or prisms according to the conventional longitudinal section, which are then connected to a second saw, e.g. a circular or band saw, cut obliquely at the desired angle to the longitudinal axis of the trunk in the range between 0 and 75 degrees, in particular in a range of 3 to 30 degrees.

The thickness of the bevel cut timber thus produced can vary widely, but is usually in a range from 1 to 40, in particular from 5 to 30 millimeters. It is also possible to use suitable knives to produce veneers typically 0.5 to 8 mm thick with the corresponding novel woodcut and the improved loading properties.

The wooden parts produced in this way, including the veneers, can be glued to other conventional wooden parts or wooden materials as a carrier. This is especially the case with layer thicknesses in the lower range, i.e. in the range of 0.5 to 10 mm, since the resistance to bending of the bevel sawn timber is reduced in comparison to conventional longitudinally cut wooden parts. The use of bevel cut timber for construction purposes is possible, but limited,

CH 713 651 A2

i.e. Depending on the layer thickness, it may be necessary to add support material for mechanical reinforcement. In contrast, the bevel sawn timber produced according to the invention seems to be predestined for use in the production of multi-layer parquets.

The following examples show a comparison of the loading of different types of wood cut at an angle with different wood treatment agents.

EXAMPLE 1: Loading different woods with oil

Oil used: Legno oil from Adler.

The loading was carried out by immersion of the wood samples in the oil pressure-free at a temperature of about 22-25 ° C (room temperature). As a reference value, the amount of oil absorbed under identical conditions of a wood cut along the trunk axis according to conventional incisions is given as 100%, the cutting angle is 0 degrees.

A) Wood species spruce

Table 1

Cutting angle in degrees Oil absorption in% 0 100 15 220 30 260 45 270 60 280 75 320 90 300 B) Wood type ash Table 2 Cutting angle in degrees Oil absorption in% 0 100 15 140 30 180 45 220 60 260 75 320 90 370 C) Type of wood beech Table 3 Cutting angle in degrees Oil absorption in% 0 100 15 220 30 230 45 230

CH 713 651 A2

Cutting angle in degrees Oil absorption in% 60 240 75 240 90 350

EXAMPLE 2: Loading different woods with wood varnish

Lacquer used: Floor Classic from Adler. The loading was carried out by immersing the wood samples in a tub filled with lacquer, pressure-free, at a temperature of approx. 22-25 ° C. (room temperature). As a reference value, the amount of lacquer absorbed under identical conditions of a wood cut along the trunk axis according to a conventional incision type is given as 100%, the cutting angle is 0 degrees.

A) Wood species fir

Table 4

Cutting angle in degrees Paint absorption in% 0 100 15 190 30 210 45 210 60 310 75 320 90 300 B) Type of wood pine Table 5 Cutting angle in degrees Paint absorption in% 0 100 15 200 30 190 45 210 60 200 75 360 90 370 C) Type of wood oak Table 6 Cutting angle in degrees Paint absorption in% 0 100 15 210 30 230

CH 713 651 A2

Cutting angle in degrees Paint absorption in% 45 240 60 240 75 240 90 230

EXAMPLE 3: Loading with Resin and Wax The substance mixture consists of 66% by weight tall resin (Sacotan 85, from Krems Chemie) and 34% by weight montan wax (Iscoblend 207, from Schliekum), the softening point is 80 degrees Celsius. Before the wooden parts are loaded, both the substance mixture and the wooden parts are heated to 110 degrees Celsius. The melt is then applied to the wooden parts until no further absorption takes place.

As a reference value, the amount of resin-wax mixture recorded under identical conditions of a wood cut according to a conventional incision along the trunk axis is given as 100%, the cutting angle is 0 degrees.

A) Wood species fir

Table 7

Cutting angle in degrees Substance absorption in% 0 100 5 280 15 300 30 310 45 300 60 310 75 320 90 300 B) type of wood pine Table 8 Cutting angle in degrees Substance absorption in% 0 100 5 200 15 200 30 220 45 210 60 230 75 330 90 340

C) Wood species oak table 9

CH 713 651 A2

Cutting angle in degrees Substance absorption in% 0 100 5 180 15 210 30 220 45 210 60 230 75 220 90 240

The tests and experiments carried out in the course of the invention have also brought the following findings:

- Bevel sawn timber that is produced at an incision angle of more than 30 degrees is difficult to process industrially. It is difficult to manipulate, transport or cut because some of their mechanical properties, in particular their bending strength properties, are reduced compared to those of conventionally slit wood. The industrial planing of such bevel cut timber is practically impossible, or only from layer thicknesses of 10mm and more, because they break easily and may even destroy the planing machine.

So if you want to work with thin bevel sawn timber that has been made with incision angles of more than 30 degrees, you first have to glue it onto a stable support, typically a support wood, before you can plan it.

However, it has also been shown that these mechanical properties, e.g. the breaking strength, only at large incision angles, i.e. with incision angles of more than 30 degrees, in particular with incision angles of 45-75 degrees, can be changed very significantly, whereas with incision angles of 3 to 30 degrees they differ only slightly from those of the conventionally longitudinally cut woods (= incision angle 0 degrees).

- The advantages of the bevel cut timbers according to the invention with regard to their modifiability by natural or artificial chemical substances become apparent even at very small incision angles. It is surprising that the absorption capacity for such substances is disproportionately increased even in the lowest incision angle range of approximately 3-20 degrees. There is also no linear relationship between the incision angle and the loading capacity, as can also be clearly seen from the examples. Rather, there are discontinuities or abrupt changes, which include the type of wood, the hardness of the wood, the cutting angle, the straightness or calmness and restlessness of the internal wood structure including the tree guide vessels, the content of resins and moisture, a possible covering up of the wood, and other factors, if any.

Overall, it can also be seen that approximately half to two thirds of the maximum possible loading capacity can be achieved even at incision angles between 0 and 30 degrees. This is particularly evident with types of wood that hardly absorb wood-modifying substances in a conventional longitudinal cut, such as Spruce. With such types of wood, the absorption capacity is unexpectedly high even at very small cutting angles.

- Wood-modifying substances can, for example, increase the surface and / or the total hardness of the sawn timber product in a very targeted manner, since the hardness-modifying substances are absorbed into the wood in liquid form, where they then chemically or physically harden. Likewise, the swelling and shrinking properties of the bevel sawn timber can be improved by impregnation with water-repellent substances, since less moisture can be absorbed.

Because of the diagonally cut tree guide vessels of the bevel cut timbers according to the invention, such wood-modifying substances can be absorbed quickly even without applying pressure, since they preferentially suck into the wood along the tree guide vessels. If you also apply pressure, it is correspondingly faster. Advantageously, the loading with wood-modifying substances can be carried out without pressure or at significantly lower pressures than would be customary or required for the loading of conventionally slit woods.

The absorption capacity can of course also be supported by heating the wood-modifying substances and / or the piece of wood to be processed.

- Cutting angles between 0 and 30 degrees, in particular from 3 to 30 degrees, are also preferred because only as long as possible can be cut bevelled timber of up to 3 meters in length, as is usually desired or even required by the panel industry , The parquet industry also prefers 50-90 cm

CH 713 651 A2 long friezes. Even when using tree trunks with large trunk diameters, i.e. relatively expensive wood, there are practical limits to the choice of cutting angles in industrial sawn timber production, which are sufficient due to the range from 0 to 30 degrees, in particular from 3 to 30 or 5 to 30 degrees be covered.

A carpenter or carpenter can of course also use other cutting angles if this corresponds to the customer's request. Most of the advantages mentioned above, however, already result in a cutting angle range of approximately 3-30 degrees, which is why this range is particularly preferred.

The bevel cut timbers and wood products produced according to the invention can be used for many purposes, for example for the production of parquets, paneling, ceilings, stair elements, veneers, decorative elements, panels, boards, and / or of two-layer or multi-layer wood-based materials in various forms, e.g. in sheet form as so-called cross plywood.

Claims (9)

claims 1. A method for increasing the absorption capacity of sawn timber for liquid wood-modifying substances, characterized in that an elongated wood blank with tree guide vessels arranged in the longitudinal direction, in particular a tree trunk, branch or an elongated part of a tree trunk or branch, at an angle between 0 and 75 degrees, is cut diagonally, in particular from 3 to 30 degrees, with respect to its longitudinal axis, so that at least some of the tree guide vessels located in the wood blank are cut or cut diagonally through the incision. 2. The method according to claim 1, characterized in that the wood blank is clamped in a suitable saw so that its longitudinal axis with respect to the cutting direction of the saw includes an angle between 0 and 75 degrees, in particular from 3 to 30 degrees, and in this position is cut. 3. The method according to claim 1 or 2, characterized in that in a first step on a first saw, for example a gang saw, wood blanks are sawn in the form of conventional posts, planks or prisms from a tree trunk or branch, from which then on a second saw , for example a circular or band saw, bevel cut wood with an incision angle between 0 and 75 degrees, in particular from 3 to 30 degrees. 4. sawn timber product with increased absorption capacity for liquid wood-modifying substances, characterized in that the sawn timber product has tree guide vessels, some or all of which are cut or cut at an angle, as a result of an oblique incision in an elongated wood blank equipped with longitudinal tree guide vessels in one Angles between 0 and 75 degrees, in particular from 3 to 30 degrees, based on its longitudinal axis. 5. Lumber product according to claim 4, loaded with at least one liquid wood-modifying substance from the group of varnishes, mordants, colorants, natural resins, synthetic resins, bleaches, substances for changing the pH, waxes, oils, alcohols and tannins. 6. Lumber product according to claim 4 or 5, with a layer thickness of 0.5 to 40 mm. 7. Lumber product according to one of claims 4 to 6, glued to a carrier material, preferably a carrier material made of wood. 8. Lumber product according to claim 4, produced by a method according to one of claims 1 to 3. 9. Lumber product according to one of claims 4 to 8, for use in the manufacture of parquets, paneling, ceilings, stair elements, veneers, decorative elements, panels, boards, and / or two- or multi-layer wood-based materials.