EP3354430A1 - Osb plate material and method for producing an osb plate material - Google Patents

Abstract

The invention relates to a method for producing an OSB board material with the steps of producing OSB strands, gluing the OSB strands and producing a grit mat from the OSB strands and pressing the grit mat to an OSB board material. In order to propose a method for producing an OSB board material which enables the production of an aesthetically pleasing surface, it is envisaged that at least a portion of the strands be bleached.

Description

The invention relates to a method for producing an OSB panel material according to the preamble of claim 1 and an OSB panel material according to claim 15.

OSB board materials or so-called chipboard are glued together and pressed wood chips. Compared with conventional chipboard, significantly larger, particularly long and slim chips, so-called strands, are used. These are glued in the known method after their preparation and sprinkled to a grit mat. The scattering of the strands takes place in a predetermined direction. Subsequently, the stratified and present in the grit mat beach are pressed together in a press to a plate material.

Due to the existing raw material capacities, the associated low costs and the advantageous low density usually coniferous woods, especially pine, used for the production of the beach. In addition, the softwoods enable the achievement of very good technological properties in OSB board materials.

The beaches made of conifers have a different color image. This is based, on the one hand, on the color differences between the core and sapwood, and, on the other hand, also on discolorations which are caused by a fungus attack that is frequently present or by improper storage of the raw wood or of the beach. Visually particularly serious are discolorations caused by fungal attack, such as blue mold. A major aesthetic problem here is that due to the discoloration of the strand and the resulting OSB board materials have no uniform color surface, but give the impression due to the red, gray or black colors of a variety of strands that for the OSB boards inferior Wood was used.

The invention is therefore based on the object to propose a method for producing an OSB panel material, which allows the production of an aesthetically pleasing surface. Furthermore, the invention has for its object to provide a corresponding OSB panel material.

The invention achieves the object by a method having the features of claim 1 and the features of claim 15. Advantageous developments of the invention are specified in the dependent claims. In this case, all the features described in principle or in any combination are fundamentally the subject of the invention, regardless of their summary in the claims or their dependency.

The method according to the invention for producing an OSB board material comprises the steps of producing OSB strands, gluing the OSB strands and producing a spreading material mat from the OSB strands, pressing the spreading material mat into an OSB board material, at least one portion of which being on the outside bleached visible beach.

The inventive method allows the production of optically high-quality and aesthetically pleasing-looking surfaces in the OSB board materials. The bleaching of the beaches causes dark strands (eg reddish, gray and / or black strands) to become light, and even light strands experience only a slight change in their hue, resulting in an overall color adaptation of the strands used. Thus, in the manufacture of the board materials by means of the inventive method, in particular the impression is avoided that poor quality wood grades are used in the production of the OSB strands.

The abbreviation OSB stands for "oriented strand board" and describes materials made from coarse chips, which - in contrast to common chips for chipboard - are suitable for being aligned in the material. In particular, the invention relates to coarse particle boards with aligned large chips (strands). Strands are in particular between 100-250 mm long, 10-75 mm wide and 0.6-2 mm thick and are preferably arranged by the throwing method. The strands can with their longitudinal axis in the longitudinal axis direction of the OSB board material or transverse to the longitudinal axis direction of the OSB board material be aligned. Under a plate material is a plate-shaped, flat material to understand. An OSB panel material is understood to mean a corresponding OSB defined in DIN EN 300: 2006-09. The OSB panel material is also referred to below as plate, panel material or OSB.

The production of the strands is carried out by customary methods, for example by debarking after the provision of the suitable round wood, cutting into strands and, if appropriate, then drying them, for example by drying them. The further gluing of the strands, scattering of the strands into a spreading material mat, the pressing of the strands to the spreading material mat from scattered strands, for example, under the action of heat and pressure likewise takes place according to common methods. The invention particularly relates to beaches of coniferous wood, more preferably OSB strands of pine wood, but can also be applied to OSB beaches of hardwood or other conifers. Adhesives used for gluing are, in particular, adhesives containing isocyanates.

By at least a portion of the strands it is understood that at least the strands are bleached which has a hue different from the usual hue of the strands, for example a light yellow hue in pinewood. In particular, strands are subjected to bleaching, which have a color which deviates from a customary shade, for example reddish and / or gray-black. Of course, all strands of an OSB board material can also be bleached, resulting in a particularly uniform color impression.

According to a development of the invention, the spreading material mat is produced with outer cover layers, wherein at least parts of the visible cover layer strands are bleached. If the board material is produced, for example, as a multilayer, in particular with an odd number of layers, for example three layers, then an OSB board material produced by the inventive method has in particular two outer cover layers and one middle layer or several middle layers. In this case, the layers are shut off from each other, that is aligned with each other. Thus, the strands of the cover layers are preferably arranged with their longitudinal axis in the longitudinal direction of the plate (in particular in the production direction) and the strands of the middle layer (s) with their longitudinal axis transversely, for example substantially as far as 90 ° to the cover layers. By the Limitation of the bleaching on the strands of the cover layers or on the strands of the cover layers, which have unwanted discolorations, in particular reddish or gray-black discolorations, the bleaching can be particularly easily integrated into conventional procedures.

The strands are particularly preferably bleached by means of an oxidative bleaching agent, the bleaching being carried out for this purpose in particular by means of hydrogen peroxide, and / or organic oxidizing agents such as, for example, aliphatic peroxide and / or hydroperoxide. By means of oxidative bleaching in particular reddish discolored strands can be lightened in a particularly efficient manner. In this case, in particular a 15% by weight to 25% by weight, advantageously a 20% by weight, solution of hydrogen peroxide is used.

For decolorization (bleaching) of gray-black discolorations, which are caused in particular by fungal attack, according to a development of the invention, the beaches are bleached by means of a reductive bleaching agent, the reductive bleaching in particular by means of sulfur-containing bleach, such as, for example, ammonium sulfite, Ammonium thiosulfate, formamidinesulfinic acid is performed. In the case of reductive bleaches, in particular ammonium thiosulfate or formamidinesulfinic acid, preference is given to using 5% by weight to 15% by weight, advantageously 10% by weight, solutions of, for example, ammonium thiosulfate or formamidine sulfinic acid.

According to a development of the invention, the bleaching is carried out in several stages, whereby both the oxidative bleaching and the reductive bleaching can be carried out several times, in particular at least twice in succession. However, most preferably the strands are bleached by both an oxidative and a reductive bleach, i. H. subjected to an at least two-stage bleaching process. The individual bleaching stages are carried out in succession and the strands are, for example, washed with water between the bleaching stages in order to improve the lightening of the strands.

According to a development of the invention, the bleaching of the strands takes place before the gluing of the strands. That is, the strands become after the cutting of the debarked roundwood and bleached with a possibly subsequent drying process with the bleaching agent. This is done, for example, in the multi-stage bleaching process. Bleaching is most preferably carried out by passing the strands through a bleach bath, ie, a liquid bleach. In a multi-stage bleaching process, the strands can also be repeatedly passed through the same bleaching agent or different bleaching agents, for example by an oxidatively acting bleaching agent and / or a reductive bleaching agent. Alternatively or additionally, the bleaching agent can also be applied to the strands, for example sprayed on. It is also conceivable, in a multi-stage bleaching process, to guide the strands through a bleach bath and in a further bleaching stage to spray the same bleach or another bleach onto the strands. This can of course also be done in reverse order.

In forming a multilayer OSB panel material, prior to bleaching, the strands are screened for suitability and / or separation of the strands in facing strands and middle strands. Accordingly, in a subsequent bleaching, preferably only the top layer strands are bleached.

Alternatively or additionally, the bleaching of the strands can also take place after the production of the spreading material mat and before the pressing of the spreading material mat to the board material. In this case, the bleaching agent is applied to the finished scattered material mat, for example. Sprayed, and can, before the compression takes place, a predetermined time act on the beach and lighten it.

The exposure time of the bleaching agent (the bleaching process) to the strands lasts for a further development of the invention for a maximum of 10 to 20 minutes, preferably 15 minutes +/- 2 minutes. The exposure time begins with the immersion or application of the bleaching agent on the beach and ends with the removal of the beach from the bleach and a. For example. Rinsing with water or with the introduction and the beginning of the pressing process in the hot press. The preferred bleaching time of 10 to 20 minutes, preferably 15 minutes +/- 2 minutes, has surprisingly been found to be particularly effective because against each experience a particularly high average bleaching effect / per unit time is achieved.

The bleaching agents are used, in particular, as liquid bleaching agents, for example aqueous solutions used. In order to shorten the necessary exposure time and to increase the degree of whitening of the strands, ie the degree of bleaching, according to a development of the invention, the bleaching agent contains catalysts. These may be, for example, when using hydrogen peroxide as a bleaching agent iron-containing catalysts or activating salts, in particular manganese dioxide. Preferably, when hydrogen peroxide is used as the liquid bleaching agent in a bleaching bath, tanks containing ferrous components are used.

The bleaching is coordinated with the wood-containing strands and the respective bleaching agent according to a development of the invention with a temperature of 15 ° C to 25 ° C. The temperature range of 15 ° C to 25 ° C has surprisingly been found to be particularly suitable for an effective and high bleaching effect of the beach. In this case, the particular temperature range allows a particularly high bleaching effect in a short period of time, so that the bleaching can be integrated particularly easily into existing process sequences. In addition, structural damage to the wood structure due to high temperatures is successfully avoided.

To further improve the bleaching result while maintaining high mechanical quality of the board materials, the bleaching with strands is carried out according to a development of the invention, which have a residual moisture content of 80 wt.% To 120 wt.%. The high humidity ensures a good wettability of the beach with the bleach, whereby the bleaching effect (brightening) is significantly improved. It should be noted that all moisture data of the beach refers to dry wood (absolutely dry wood).

The drying of the beaches can be done in one or more stages. When bleaching is carried out before bleaching by means of a bleaching bath and / or by applying the bleaching agent, preferably at least one drying process takes place after bleaching, so that the bleached strands for gluing have a residual moisture in the range of, for example, from 3% by weight to 6% by weight. atro (Beleimfeuchte). In addition, a drying process and / or moistening process can also be carried out before the bleaching in order to set the strands, for example, to a residual moisture content of 80% by weight to 120% by weight, for the bleaching process.

When a bleaching of the surfaces of the spreading material mat, which can be carried out alternatively or in addition to bleaching before gluing, also a drying process after bleaching and before pressing the grit mat is feasible to prevent, for example, excessive moisture in the press , This can be done, for example, by means of a hot air drying of the surface.

The separation and screening of the strands is carried out in particular depending on the structure of the production line and the product to be produced. In a multi-layered product, such as an OSB panel material with middle layer and two outer layers, the middle layer and outer layer strips are produced either on separate production lines or on a common production line.

In the production on separate production lines, no separation of the top layer and middle layer strands, but primarily only a screening and sorting out of the strands suitable for the respective layer in each production line is performed. In this case, the screening and sorting takes place, for example, in each production line by itself and before the drying of the strands on the Beleimfeuchte (3 wt.% To 6 wt.% Atro), i. at the outer layer strands preferably before bleaching and subsequent drying to the Beleimfeuchte and at the middle layer strands before drying on the Beleimfeuchte.

In the production of cover layer and middle layer strands on a production line, at least in the production of multilayer materials, a sorting of the strands in middle layer strands and cover strands, if appropriate in addition to, for example, subsequent separation and sorting. If bleaching is carried out before gluing, the sorting is preferably carried out before the bleaching of the strands (for example the cover layer strands). If only a bleaching of the surface of the spreading material mat takes place, the sorting and / or separation can take place, for example, before the gluing of the strands.

It is noted that regardless of whether the strands of the overcoat layers and middle layer (s) are made together or separately and / or in one or more stages be dried, the strands are advantageously set to bleaching before gluing to a residual moisture content of 80 wt.% To 120 wt.% Atro (dried or moistened) and advantageously for gluing to a residual moisture of 3 wt.% To 6 wt.% Atro dried.

In order to minimize the use of bleaching agents, according to a development of the invention, the discoloration of the strands is determined by color recognition (visually or camera-based), color-striking strands, in particular cover strands, are removed and subjected to bleaching. In addition, the strands are preferably sorted into reddish and gray-black discolorations, with strands having a reddish discoloration, in particular an oxidative bleaching, and strands having a gray-black discoloration, in particular a reductive bleaching. The color recognition and the sorting of the strands are carried out in particular after the cutting or drying of the strands. In particular, the color recognition and separation takes place in connection with the separation of the strands in cover stratum strands and middle stratum strands and / or with the sighting and sorting out of the respective strands. In this case, the color recognition and discharge is preferably carried out at cover layer strands. The color detection can be either visually, d. H. be performed by a person, or by a camera-based color detection system, for example, in combination with a fully automatic discharge device.

In this case, a color measurement can be carried out to determine the discoloration and / or also for a control of the bleaching result on the untreated and / or bleached strands. The color measurement takes place, for example, by determining the L * a * b * values. The L * a * b * color space is a color space that covers all areas of perceptible colors. The L * a * b * color space is described by a three-dimensional coordinate system. The L * axis describes the brightness (luminance) of the color with values from o (black) to 100 (white). The a * axis describes the green or red portion of a color, with negative values for green and positive values for red. The b * axis describes the blue or yellow part of a color, with negative values for blue and positive values for yellow. For example, with the inventive bleaching of the OSB strands, in particular pinewood strands, an L * value between 77-82 is achieved for the discolored OSB strands, which is approximately the L * value of a conventional pale yellow hue of pinewood strands equivalent. The measurement of the L * a * b * values is carried out according to EN ISO 11664-4 "Colorimetry - Part 4: CIE 1976 Color Space" 20011-07.

Further, the object of the invention is achieved by an OSB panel material produced according to claim 1. The panel material has at least two visible outsides formed by the strands. The visible strands are at least partially bleached. As a result, the OSB panel material has a much more homogeneous, aesthetically pleasing and valuable, visible surface.

Fig. 1

einen schematisch dargestellten Ablauf des Verfahrens mit einer Bleichung vor der Beleimung der Strands;

Fig. 2

einen weiteren schematisch dargestellten Ablauf des Verfahrens mit einer Bleichung der Strands nach dem Herstellen der Streugutmatte.

Furthermore, the invention will be described in more detail with reference to exemplary embodiments. Show it:

Fig. 1

a schematically illustrated procedure of the method with a bleaching before gluing the beach;

Fig. 2

a further schematically illustrated procedure of the method with a bleaching of the strands after the production of the grit mat.

FIG. 1 and 2 schematically show the sequence of possible manufacturing processes of an OSB board material, which can be carried out in each case or in partial combination with each other. The procedures comprise the following steps: providing 1 of the roundwood, debarking the roundwood 2, cutting 3 the roundwood in strands. Optionally, drying / moistening 4 of the strands takes place on, for example, bleaching moisture (80% by weight to 120% by weight of atro). Subsequently, a separation 5a and / or sighting 5b of the strands takes place in which the strands are divided into middle layer and outer layer strands and the respective strands are checked for their suitability. The separated cover layer strands are then subjected to bleaching 10, for example in the bleaching bath or by applying the bleaching agent. Before the gluing 6a, 6b, a drying 12a, 12b of the strands takes place on the glueing moisture, ie on a residual moisture of 3% by weight to 6% by weight of dry.

It should be noted that the drying / moistening 4 of the strands to the bleaching moisture (80% by weight to 120% by weight atro) is optional and, alternatively or in addition, for example also after the separation 5a / sighting 5b and, for example, limited to the cover layer strands can be.

In addition, a color detection, for example, the cover layer strands, be performed before, with or after the separation 5a / sighting 5b, so that at the top layer strands in addition to the sighting (and sorting) 5b on suitability (especially the size) in addition a discharge of the discolored and to be bleached beach. In this case, only the discharged strands of the overlay strands are subjected to bleaching. The unbleached and bleached outer layer strands can then be dried separately or together to the Beleimfeuchte. After gluing 6a, 6b, the scattering 7 of the covering layer and middle layer strands takes place to a spreading material mat.

Alternatively or in addition to bleaching 10 ( FIG. 1 ) before the gluing 6a, 6b, a bleaching 11 (see FIG. 2 ) of the surface of the grit mat, ie the visible outer layer strands, eg. By rolling / spraying and exposure to the bleaching agent. Optionally, the bleached surface of the spreading material mat can still be subjected to a drying process 13.

After the preparation of the spreading material mat or the bleaching / drying of the surface of the grit mat, this is pressed in a press, especially a hot press, to a plate material 8. After pressing 8 and the execution of the plate material from the press can optionally still have a control 9, bspw a color measurement is carried out by determining the L * a * b * values of the surfaces of the OSP board material.

The production of an OSB board material with two production lines for the separate production of the cover layer strands and middle layer strands can be carried out analogously to this, in particular starting from the gluing 6a, 6b of the strands. The division of the manufacturing process into cover strands and middle strands takes place with the provision 1, debarking 2 or the cutting 3. The sighting 5b (and sorting) or the color recognition of the cover stratum or all subsequent production steps can as FIG. 1 and or FIG. 2 be described described.

LIST OF REFERENCE NUMBERS

1

Providing roundwood

2

debarking

3

Machining in beaches

4

Adjustment of the beach moisture

5a

separation

5b

Sighting and sorting

6a

Gluing middle layer beach

6b

Gluing of cover layer strands

7

Scattering of the spreading material mat

8th

Pressing the spreading material mat

9

control

10

Bleaching before gluing

11

Bleaching the surface of the spreading material mat

12a

Dry before gluing

12b

Drying after bleaching and before gluing

13

Drying of the spreading material mat surface

Claims (15)

Method for producing an OSB panel material with the steps - manufacturing OSB beaches, Gluing (6a, 6b) the OSB strands and producing a grit mat from the OSB strands, - Pressing (8) of the grit mat to an OSB board material, wherein - at least a portion of the beaches is bleached. A method according to claim 1, characterized in that the spreading material mat is produced with outer cover layers and at least portions of the visible cover layer strands are bleached. Method according to one of the preceding claims, characterized in that the strands are bleached oxidatively, wherein the bleaching (10, 11) by means of hydrogen peroxide and / or organic oxidizing agents such as, for example, aliphatic peroxide and / or hydroperoxide takes place. Method according to one of the preceding claims, characterized in that the strands are bleached reductively, wherein the reductive bleaching (10, 11) in particular by means of sulfur-containing bleaching agent such as, for example, ammonium sulfite, ammonium thiosulfate, formamidinesulfinic acid is performed. Method according to one of the preceding claims, characterized in that the strands are bleached in two stages, the strands being bleached in particular oxidatively and reductively. Method according to one of the preceding claims, characterized in that the strands are bleached before gluing (6a, 6b). Method according to one of the preceding claims, characterized in that the strands are passed through a bleach bath. Method according to one of the preceding claims, characterized in that the strands are sprayed with a bleaching agent. Method according to one of the preceding claims, characterized in that the bleaching (10, 11) of the strands takes place after the production of the spreading material mat and before pressing (8) into a board material. Method according to one of the preceding claims, characterized in that the bleaching (10, 11) of the strands lasts for a maximum of 10 - 20 min, preferably 15 min +/- 2 min. Method according to one of the preceding claims, characterized in that the bleaching agent contains catalysts, in particular iron-containing catalysts, activating salts, in particular manganese dioxide. Method according to one of the preceding claims, characterized in that the bleaching (10, 11) at a temperature of 15 ° C to 25 ° C, more preferably at 20 ° C +/- 1 ° is performed. Method according to one of the preceding claims, characterized in that the bleaching (10, 11) with strands having a residual moisture content of 80 wt.% To 120 wt.% Is performed. Method according to one of the preceding claims, characterized in that the discoloration of the strands is determined by a color detection and color-striking cover layer strands discharged and the bleaching (10) are subjected, in particular an oxidative bleaching (10, 11) in a reddish discoloration and a reductive bleaching (10, 11) is performed on a gray-black discoloration. OSB board material produced according to claim 1, having two visible outer sides which are at least partially bleached.

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