RU2776715C1 - Wood board with oriented chips, method for production, and apparatus for producing such a board - Google Patents

Abstract

FIELD: woodworking.

SUBSTANCE: group of inventions relates to the manufacture of wood boards with oriented chips. Wood board with oriented chips comprises a top surface layer containing or consisting of oriented strands interconnected by means of a binder, an inner layer containing shavings produced from recycled wood and interconnected by means of a binder, and a bottom surface layer containing or consisting of oriented strands interconnected by means of a binder. The inner layer is located between the two surface layers. A mat made of scattered particles is produced by manufacturing a surface layer mat, scattering at least one inner layer mat onto the surface layer mat, and manufacturing an additional surface layer mat on at least one inner layer mat. In order for the binder to be cured and hardened, the mat made of scattered particles is then pressed at an elevated temperature relative to the standard conditions so as to produce a wood board with oriented chips.

EFFECT: mechanical strength of the wood board is increased.

48 cl, 5 dwg

Description

The present invention relates to a new oriented strand board (OSB) containing, at least in the core layer, recycled wood chips obtained by grinding recycled wood. The present invention also relates to a method for the production of a corresponding oriented strand board and to a device with which the proposed wood board can be obtained or with which the proposed production method can be implemented.

Oriented strand boards have hitherto always been produced from virgin wood. For this purpose, tree trunks are used, which, after peeling off the bark, are crushed to obtain large-sized chips or “strands”. This is done using so-called OSB chippers. The resulting strands are sorted by size, usually into two fractions, with the coarse strand fraction being used to produce the surface layers of the oriented strand board, and the finer chip fraction usually being used in the core layer of the oriented strand board or being omitted from the production process. OSB. The resulting strands are usually dried before sorting. The dried individual fractions of the strands are then glued and stacked on top of each other to form strand mats. The production of oriented strand board is completed after pressing and simultaneous curing of the binder.

Many different processes are known for the production of boards from wood raw materials, such as oriented strand boards.

For example, AU 2010-209995 A1 describes a composite board containing wood strips and a binder, where the wood can optionally include raw wood, recycled wood, OSB wafer board, particle board, structurally oriented board, natural wood board, wood structured panel. , solid fibreboard, fibreboard, particle board, LVL or any other suitable wood.

DE 4 224 629 A1 describes a process for processing wood-based materials glued with urea-formaldehyde binders, with or without polymer coating, by breaking the elements into small fragments in the pre-treatment stage and separating metal parts such as fasteners, etc. , after which, in the deaggregation step, the fragments are placed in an atmosphere of preferably saturated steam, where they are under high pressure and at high temperature during the deaggregation period. During this time, the fragments break down into components of a fibrous base, which can be glued together to obtain new elements.

DE 10 130 526 A1 relates to a method for the production of boards from wood raw materials, according to which fine fractions, for example finely chopped sawdust or small chips, are applied to the surface layers of a wood-based board with oriented strands. To this end, it is possible to improve the sliding and adhesion properties of oriented strand boards.

DE 19 751 326 A1 relates to a board made from wood raw material containing used amino resins, residual and waste wood materials, as well as methods for their production and methods for disposing of used residual and waste wood materials. These waste wood materials are crushed and used for the production of chipboard.

DE 10 2008 059 527 A1 discloses a medium density fibreboard (MDF) in which decorative particles are embedded to form an aesthetically pleasing appearance.

EP 2 216 149 A1 discloses a process for the production of particle boards, in which, among other materials, chips from recycled wood can be used.

Thus, the possibility of using recycled wood materials as a raw material is already known from particle board production technology. However, this possibility has been abandoned in the production of oriented strand boards due to the expected low mechanical strength of a suitably manufactured wood board.

It is therefore an object of the present invention to provide oriented strand boards, which can be produced from raw material sources alternative to pure virgin wood sources and in no way deviating from the mechanical requirements of DIN EN 300:2006.

This object is achieved by providing an oriented strand board according to claim 1, a method for producing a corresponding oriented strand board according to claim 20, and an apparatus for producing a corresponding oriented strand board according to claim 43. each of these objects is characterized by their development, which has advantages.

Thus, in a first aspect, the present invention relates to an oriented strand board comprising at least the following three layers:

a) an upper surface layer containing or consisting of oriented strands connected to each other,

b) at least one inner layer containing chips obtained by grinding recycled wood (recycled wood chips) and which are bonded to each other,

c) the lower surface layer containing oriented strands or consisting of oriented strands connected to each other,

moreover, the specified at least one inner layer is located between two surface layers.

According to the invention, the respective chips, strands and layers are bonded to each other by means of a binder to form an oriented strand wood panel.

The previously widespread prejudice that the mechanical properties of oriented strand boards leave much to be desired when other raw materials than primary wood is used in processing has not been confirmed. The oriented strand boards of the present invention are in no way inferior to oriented strand boards made from 100% virgin wood and meet all the mechanical properties specified for OSB according to DIN EN 300:2006: the offered wood boards with oriented strands, depending on the specific structure, can meet all the requirements of DIN EN 300:2006, for example for OSB/1, OSB/2, OSB/3 or even OSB/4 boards.

A particular advantage of the oriented strand boards of the present invention is that they can be produced in a resource-saving manner, so that less virgin wood is required for their production. It also opens up access to another source of raw materials, namely recycled wood (or used wood), which until now was considered suitable only for particle board production or heat generation.

A feature of the oriented strand board according to the present invention is that at least the core (if the oriented strand board has only one core) or the cores (if the oriented strand board has multiple cores) comprise recycled wood chips obtained by grinding recycled wood or that at least one said inner layer or inner layers was/were completely formed from recycled wood chips.

The expression "recycled wood" is used here in the meaning of "Altholz" in the legislation of the Federal Republic of Germany concerning the requirements for the disposal and destruction of recycled wood ("Verordnung uber Anforderungen a die Verwertung und Beseitigung von Altholz", Altholzverordnung, published in the BGBI. [Federal Law Gazette Germany] I, No. 59, pp. 3302-3317).

The present invention is applicable to all processed wood, and for the purposes of the present invention, particular preference is given to the use of Category A I and/or Category A II processed wood.

The configuration of the recycled wood used is not relevant here, so recycled wood chips can be obtained by recycling any suitable wood products, such as used furniture, window frames, cladding, chipboard, pallets, etc.

In contrast, the term "virgin wood" means wood that has not been processed, but has been obtained directly from forest products. One form of primary wood is "virgin wood", i.e. primary round timber, which especially includes freshly felled and debranched, but not necessarily debarked, tree trunks.

Preferably, according to the present invention, said at least one inner layer comprises or is formed from a mixture of mutually bonded recycled wood chips and strands.

It is also possible that the two surface layers also contain or are formed from a mixture of mutually bonded recycled wood chips and strands. In this embodiment, however, it is advantageous for the proportion of recycled wood chips in the surface layers to be less than the proportion of recycled wood chips in the core layer.

In a further preferred embodiment, it is advantageous if the strands present in said at least one inner layer have a shorter average length (number average) than the strands present in the upper and lower surface layers.

Under the length of the particles, such as chips, in the context of the present invention refers to the greatest length of the particles, such as chips. Average length is a numerical weighted average. It can be determined, for example, using optical analysis.

Under the width of the particles, such as chips, in the context of the present invention refers to the second largest length of the particles, such as chips. Average width refers to a numerical weighted average. It can be determined, for example, using optical analysis.

The thickness of a particle, such as a chip, in the context of the present invention means the smallest extent of a particle, such as a chip. Average thickness refers to a numerical weighted average. It can be determined, for example, using optical analysis.

The oriented strand board of the present invention may have exactly one inner layer, or alternatively exactly three inner layers, namely a middle inner layer delimited by the two outermost layers. Thus, in each of the aforementioned preferred cases, the oriented strand board has a symmetrical structure and therefore has well-balanced mechanical properties.

In addition to recycled wood chips, it is also possible to include virgin wood chips, which in this case replace part of the recycled wood chips. Here virgin wood refers to wood that has not been recycled, but obtained directly from forest products. If not only recycled wood chips are included, but also virgin wood chips, the preferred weights for recycled wood chips, which are detailed below, refer to the total mass fraction of recycled wood chips and virgin wood chips.

The geometry of any virgin wood chips present is preferably identical to that of recycled wood chips; more specifically, the (average) dimensions given below for recycled wood chips also apply to virgin wood chips. The reason for this may be that virgin wood chips are preferably obtained in the same way as recycled wood chips, namely by grinding virgin wood chips in a knife ring chipper.

If there is some proportional proportion of virgin wood chips that partially replace recycled wood chips, it is preferable to replace a proportion of 0.1 to 80 wt.%, preferably 1 to 70 wt.%, more preferably 5 to 50 wt.% chips from recycled wood shavings from virgin wood. This applies to all embodiments of oriented strand board, which are described below.

In yet another preferred embodiment, the weight fraction of recycled wood chips and any virgin wood chips in said at least one inner layer, in particular exactly one inner layer, relative to all chips in that layer, is at least 5 wt. %, preferably at least 50 wt.%, more preferably at least 60 wt.%, even more preferably at least 70 wt.%, most preferably at least 80 wt.%.

It should be further mentioned here that the inner layer can also be formed from 100% recycled wood chips or from a mixture of recycled wood chips and virgin wood chips.

If the inner layer is formed from a mixture of chips containing recycled wood chips and any virgin wood chips, it is advantageous if strands are also included in the inner layer along with recycled wood chips and any virgin wood chips. The weight fraction of strands in the inner layer here preferably supplements the weight fraction of recycled wood chips and any virgin wood chips; in other words, the mass fraction of strands in the inner layer, especially in exactly one inner layer, referred to all wood particles (that is, the sum of all chips and strands) in said at least one inner layer, is preferably not more than 95 wt.%, preferably not more than 50% by weight, more preferably not more than 40% by weight, even more preferably not more than 30% by weight, most preferably not more than 20% by weight.

In an alternative and also preferred embodiment, the oriented strand board may have three core layers and therefore a total of five layers (including top and bottom skin layers). The three inner layers here constitute the middle inner layer, bounded by the two outermost inner layers. In this embodiment, it is preferred that the weight fraction of recycled wood chips and any virgin wood chips in the middle inner layer is higher than in the outermost layers, and the weight fraction of strands having a shorter average length (number average) compared to strands in the upper and lower surface layers are less in the middle inner layer than in the outermost inner layers.

In the above embodiment, in which the oriented strand board has three inner layers, it is advantageous when the weight fraction of recycled wood chips and any virgin wood chips in the middle inner layer, referred to all wood particles (i.e., the sum of all chips and strands ) in the middle inner layer is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably at least 50 to 90 wt.%, most preferably from 60 to 85 wt.%, and/or wt. the proportion of recycled wood chips in the innermost layers, based on all chips in these layers, is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably from 20 to 80 wt.%, most preferably from 30 up to 70 wt.%, and the mass fraction of chips from recycled wood in the middle inner layer and in the outermost inner layers are different, and the mass fraction of chips from recycled wood on average The innermost layer is preferably larger than in the outermost inner layers.

When configuring the middle and outermost inner layers, it is also possible that, for example, the middle inner layer is formed exclusively from recycled wood chips and any virgin wood chips, and the innermost layers are formed from a mixture of strands and recycled wood chips and any virgin wood chips. wood.

In this case, it is particularly preferred that the strands in the innermost layers are oriented transverse to the orientation of the strands present in the surface layers.

This also includes the possibility that both the middle inner layer and the outermost inner layers are formed 100% from recycled wood chips and any virgin wood chips, in this case preferably using recycled wood chips having smaller average dimensions. (eg, smaller in average number average length) to produce the middle core than to produce the outermost cores.

The strands used for the surface layers preferably have an average length (number average) of 40 to 250 mm, preferably 50 to 250, more preferably 70 to 150 mm, an average width (number average) of 2 to 40 mm, preferably 5 to 25 mm and/or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm.

In a preferred embodiment, the recycled wood chips and any virgin wood chips have an average length (number average) of 5 to 50 mm, preferably 10 to 30 mm, an average width (number average) of 0.2 to 10 mm, preferably 0, 5 to 5 mm and/or an average thickness (number average) of 0.3 to 2 mm, preferably 0.3 to 1.2 mm.

If the inner layer also includes strands, they preferably have an average length (number average) of 10 to 150 mm, preferably 30 to 100 mm, an average width (number average) of 0.5 to 30 mm, preferably 2 to 15 mm, and/ or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm, the average length (number average) being less than the average length of the strands present in the upper and/or lower surface layer.

The recycled wood chips present in the wood board of the present invention are preferably obtained by chipping recycled wood chips, especially using a knife ring chipper. Any virgin wood chips present can be obtained by appropriately shredding virgin wood chips.

Preferably, the strands present in the two surface layers are arranged in an oriented manner. The orientation of the strands imparts high mechanical strength to the oriented strand board, especially in one preferred longitudinal direction. Here it is preferred that the strands are oriented with respect to the longitudinal axis of the oriented strand board, such that at least 60%, preferably at least 70%, most preferably at least 80%, of the strands deviate in their longitudinal alignment by no more than 20 ° from the longitudinal direction of the oriented strand board.

The orientation of the strands can be determined in the usual way, for example, by analyzing samples of finished boards with oriented strands, during scattering during production, as described below, or using optical test methods.

It is particularly preferred here that the oriented strands in the upper surface layer and the lower surface layer have the same orientation, that is, they are oriented in the same way.

The total thickness of the oriented strand board can be from 4 to 100 mm, preferably from 6 to 40 mm.

Here it is also preferred that the total thickness of the top and bottom skin layers is between 20% and 60%, preferably between 25% and 50%, more preferably between 30% and 40% of the total thickness of the oriented strand board and/or a thickness of at least of one inner layer was from 80% to 40%, preferably from 75% to 50%, more preferably from 70% to 60% of the total thickness of the oriented strand board.

The oriented strand board according to the present invention particularly has a filling density of 450 to 750 kg/m 3 , preferably 520 to 670 kg/m ³ .

In another preferred embodiment, the binder used to bind the respective chips is selected from the group consisting of polymeric diphenylmethane diisocyanate (PMDI) binders, melamine formaldehyde urea (MUF) binders, melamine urea phenol formaldehyde (MUPF) binders, phenol formaldehyde binders, natural binders, for example starch-based binders, protein-based binders, tannin-, lignin- or carbohydrate-based binders decomposed into monomers, thermoplastic or cross-linked thermoplastic adhesives, and mixtures and combinations thereof.

The strands present in the surface layers and any strands present in said at least one inner layer can in particular be obtained by grinding primary wood.

In a second aspect, the present invention relates to a method for producing an oriented strand board as detailed above, in which a scattered particle mat composed of multiple mats is first obtained by dispersion and then pressed to obtain an oriented strand board. For the production of a mat from scattered particles, the following steps are performed here:

a) A surface layer mat containing strands or consisting of strands provided with a binder is made by oriented dispersion of strands that have been provided with a binder or a chip mixture containing strands that have been provided with a binder.

b) At least one inner layer mat containing recycled wood chips, which were obtained by grinding recycled wood and provided with a binder, is scattered on the surface layer mat obtained in step a).

c) An additional mat of the surface layer, containing strands or consisting of strands that have been provided with a binder, is obtained or laid on said at least one mat of the inner layer obtained in step b), by oriented scattering of strands that have been provided with a binder or chip mixture containing strands provided with a binder.

The scattered particle mat for curing and solidifying the binder is then pressed at an elevated temperature relative to standard conditions to form an oriented strand board.

Thus, it is an essential feature of the method according to the invention that the mats which have respective layers (i.e. the surface layers or said at least one inner layer of the manufactured oriented strand board) are scattered individually and successively one on top of the other and Finally, the scattered particle mat, composed of the individual mats, is pressed to form a finished oriented strand board. In this case, the recycled wood chips are used at least to produce the inner layer mat.

Recycled wood chips, in particular, can be obtained in the previous step by chipping recycled wood chips, especially using a knife ring chipper. Any used virgin wood chips can be similarly obtained by grinding virgin wood chips.

If the recycled wood chips are obtained by grinding recycled wood chips, it is also preferred that the recycled wood chips be produced by crushing the recycled wood, especially using a chipper such as a drum mill, hammer mill or impact crusher, or obtained from an external source.

Alternatively, it is also possible here that the recycled wood chips may be obtained from external sources.

If recycled wood is being chipped, and the sources of recycled wood are too large for the appropriate crushing devices (e.g. large pieces of furniture, etc.), one option is to perform a coarse pre-crushing of the recycled wood prior to chipping. material in the form of pieces, for example, using a chipper, in which large pieces of recycled wood are broken into smaller pieces.

In order to ensure maximum chipping efficiency, it is also advantageous when the chips (whether produced separately or obtained from external sources) are sorted before chipping, for example, using a sorting machine, i.e. sorted according to size, in particular by means of a disk sorting machine and/or a roller sorting machine, with in this case, a chip fraction is sent for grinding, having an average largest size (number average) from 20 to 150 mm, preferably from 30 to 120 mm.

It is also possible to obtain a larger and/or smaller fraction of chips.

Preferably, chip fractions having an average largest size (number average) of more than 150 mm, preferably more than 120 mm, are sent back to the chipper to produce chips.

Alternatively or additionally, it is also possible that the chip fractions having an average largest size (number average) of less than 20 mm, preferably less than 30 mm, which are obtained in the sorting process, are used for heat production or for particle board production.

Because reclaimed wood is a relatively heterogeneous material, one option is to have at least one purification step prior to use for the purposes of the present invention. This is especially advantageous when at least one of the following steps is carried out before grinding and/or crushing and/or coarse pre-crushing, preferably in any sequence all of the following steps:

• removal of substances having a lower density than wood (eg plastic film, paper, cardboard), for example by pneumatic sorting,

• removal of ferromagnetic metals, for example using magnetic sorting machines,

• removal of non-ferromagnetic metals, especially aluminium, for example using eddy current sorting machines,

• removal of substances having a higher density than wood (stones, glass, sand, minerals) using gravimetric screening, such as air separators, gravity screeners or flotation screeners and/or

• removal of non-woody substances, eg using X-ray sorters and/or video sorters.

According to the proposed method, one or more of the above purification steps is preferably carried out repeatedly.

For example, removal of metals (ferromagnetic or non-ferromagnetic metals) can be performed repeatedly. Re-removal of non-metallic materials is also possible.

A new and separate removal of metallic and/or ceramic materials is particularly advantageous to take place just before chipping, in order to avoid damage to the chipping device.

It is also possible to size recycled wood chips (which were obtained, for example, by chipping recycled wood chips or obtained from external sources) and any virgin wood chips before production of the scattered particle mat. More specifically, the method uses recycled wood chips having an average length (number average) of 5 to 50 mm, preferably 10 to 30 mm, an average width (number average) of 0.2 to 10 mm, preferably 0.5 to 5 mm, and/or an average thickness (number average) of 0.3 to 2 mm, preferably 0.3 to 1.2 mm.

The fines that are produced in the grading step and separated from recycled wood chips and any virgin wood chips (i.e. recycled wood chips having an average length (number average) of less than 5 mm), for example, can be used for heat generation or for chipboard production. It is also possible to sort the fines again and to separate the fraction of chips that are within the above dimensions. This fraction can also be used for the purposes of the present invention.

Any removed coarse fraction (i.e. recycled wood chips and any virgin wood chips having an average length (number average) greater than 50 mm) can be sent back to the milling and further crushed to thereby obtain a chip fraction suitable for the purpose of the present invention.

Particularly suitable for use in the production of the oriented strand board according to the invention is a medium fraction in which the recycled wood chips have, for example, the average dimensions given above.

For the purposes of the present invention, it is possible for the surface layer mats to be made entirely from binder strands, which are obtained, for example, by grinding virgin wood, while one or more inner layer mats can be formed entirely from recycled wood chips and possibly chips. from primary wood.

However, for the production of individual mats, it is most preferable to first mix the obtained strands and chips from recycled wood, as well as any chips from virgin wood, with each other, and then sort the resulting mixture by size and use the individual fractions to produce individual mats.

This most preferred option is detailed below.

If, as described above, a mixture of strands and chips is obtained from recycled wood and any chips from virgin wood, this can be done, for example, by actively mixing the individual types of chips, but preferably this mixture is obtained automatically by transporting or processing the mixture of chips in subsequent stages work, for example as a result of the general storage of various types of chips in a storage hopper or normal transport in a transport device.

More specifically, for example, a mixture of recycled wood chips and any virgin wood chips and strands can be dried, in particular in a tumble dryer.

Thus, in the case of conventional drying of recycled wood strands and chips and any virgin wood chips, only one device is needed to dry the mixture of chips, so that the complexity of the equipment can be minimized.

Obviously, it is also possible to dry the layers separately, for example in separate drum dryers, if these layers can be obtained from the same type of strands or recycled wood chips.

In the case of the aforementioned recycled wood chip mixture, here it is preferable to select mixing ratios of recycled wood chips to strands from 5:95 to 95:5, preferably from 20:80 to 90:10, more preferably from 40:60 to 75:25, most preferably from 45:55 to 60:40.

Thus, the mixture of chips prepared in advance is preferably sorted according to the average size of the recycled wood chips and strands. The fractions obtained according to their size are used in the surface layer mat or inner layer mat(s), wherein the coarser fraction of the mixture of chips is used in the surface layer mats, and the smaller fractions of the mixture of chips in the inner layer mat(s).

In this case, sorting can be carried out, for example, using disc sorters, screens, roller sorters, vibration sorters, or a combination of two or more of the same or different means mentioned above.

Sorted into two or three fractions, namely the fraction of the surface layer, the fraction of the inner layer and, optionally, the fine fraction.

The surface layer fraction is used to produce the surface layer mat and has the largest average chip size (largest average length (number average)). As a rule, sorting is carried out in such a way that the fraction of the surface layer is formed mainly from strands.

In addition, a fraction of the inner layer is formed, which is used to make mat(s) of the inner layer. If the oriented strand board being produced has exactly one core, a fraction of the core is entirely used to make the core mat. If the oriented strand board has a plurality of cores, for example three cores (two outermost cores and one middle core), a fraction of the core is used to make coreboard mats that subsequently form the core. A feature of the fraction of the inner layer is that it contains strands that have a smaller average length (number average) than the strands present in the fraction of the surface layer.

If the oriented strand board also has a middle core, it is made using a middle core mat sandwiched between two end core mats. To do this, use a fine fraction, which consists mainly of chips from recycled wood and, optionally, chips from virgin wood, which in general have the smallest average dimensions (average length (number average)).

Sorting as described above is not required if only one type of strands is used to produce the surface layer mat, and only one type of recycled wood chips is used to produce the inner layer mat, or a specially prepared mixture of recycled wood chips is used to produce the inner layer mat. and strands.

Thus, it is preferable that in step b) described at the beginning, exactly one inner layer mat or three inner layer mats stacked on top of each other, namely one middle inner layer mat bounded on each side by one outermost inner layer mat, is produced.

It is further preferred that in said at least one inner layer mat, especially when it is the only mat, the weight fraction of recycled wood chips and any virgin wood chips, based on all chips in that mat, is at least 5 wt. .%, preferably at least 50 wt.%, more preferably at least 60 wt.%, even more preferably at least 70 wt.%, most preferably at least 80 wt.%, and the mass fraction of strands of smaller average length (number average) in comparison with the strands in the mat of the upper and lower surface layer is not more than 95 wt.%, preferably not more than 50 wt.%, more preferably not more than 40 wt.%, even more preferably not more than 30 wt.%, most preferably not more than 20 wt.%.

If three inner layer mats are made, namely when the middle inner layer mat is limited on each side by two outermost inner layer mats, it is advantageous when (i) the weight fraction of recycled wood chips and any virgin wood chips in the middle inner layer mat is set higher, than in mats of the outermost inner layer, and (ii) the mass fraction of strands having a smaller average length (number average), compared to strands in two mats of the surface layer in the mat of the middle inner layer is set at a lower level than in the mats of the outermost inner layer.

If strands are present in the outermost layer mats, they are preferably scattered across the orientation of the strands in the surface layer mats.

The above embodiment also includes forming a middle core mat entirely from recycled wood chips and any virgin wood chips. It is also possible for the outermost inner layer mats to be strand-free. If three inner layer mats are used and none of the inner layer mats contains strands, it is preferred that recycled wood chips and optional virgin wood chips have large average dimensions (i.e., large average length (number average)) , were used in mats of the outermost inner layer.

In a preferred embodiment, the weight fraction of recycled wood chips and any virgin wood chips in the middle core mats, based on all chips in these mats, is at least 5% by weight, preferably 5 to 100% by weight, more preferably at least 50 to 90% by weight, most preferably 60 to 85% by weight.

Alternatively or additionally, it is also possible that the mass fraction of recycled wood chips and any virgin wood chips in the innermost layer mats, based on all chips in these mats, is at least 5% by weight, preferably between 5 and 100 wt.%, more preferably from 20 to 80 wt.%, most preferably from 30 to 70 wt.%,

moreover, the mass fraction of recycled wood chips and any recycled wood chips in the middle inner layer mat and outermost inner layer mats is different in each case, namely, the mass fraction of recycled wood chips in the middle inner layer mat is preferably greater than in the outermost inner layer mats .

For the manufacture of the mat for the surface layer, strands are used, in particular having an average length (number average) of 40 to 250 mm, preferably from 50 to 250 mm, more preferably from 70 to 150 mm, an average width (number average) of 2 to 40 mm, preferably from 5 to 25 mm and/or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm. In this case, it does not matter whether the strands are of the same type or, if necessary, they are obtained by sorting a mixture of strands and chips from recycled wood.

In addition, it is preferable that the strands present in said at least one inner layer mat have an average length (number average) of 10 to 150 mm, preferably 30 to 100 mm, an average width (number average) of 0.5 to 30 mm ., preferably 2 to 15 mm and/or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm, the average length (number average) being less than the average length of the strands present in mats of the surface layer.

It does not matter whether strands of the same type or strands obtained by sorting a mixture of strands and chips from recycled wood are used in said at least one mat of the inner layer.

In a preferred embodiment, in step a) and step c), the strands are oriented with respect to the longitudinal axis of the oriented strand board such that at least 60%, preferably at least 70%, most preferably at least 80% of the strands deviate in longitudinal direction no more than 20° from the longitudinal direction of the oriented strand board.

It is particularly preferred that the strands in step a) and step c) have the same orientation.

The overall thickness of the oriented strand board is generally set in the range of 4 to 100 mm, preferably 6 to 40 mm. To this end, the dimensions of the scattered particle mat and the compaction factor during pressing are suitably matched to each other.

Preferably the binder is selected from the group consisting of polymeric diphenylmethane diisocyanate (PMDI) binders, melamine formaldehyde urea (MUF) binders, melamine urea phenol formaldehyde (MUPF) binders, phenol formaldehyde binders, natural binders, e.g. starch based binders, protein based binders. binders based on tannin, lignin or carbohydrates decomposed into monomers, thermoplastic or cross-linked thermoplastic adhesives, as well as mixtures and combinations thereof.

In a third aspect, the present invention relates to an oriented strand board production apparatus as described above, with which the method described above can also be carried out.

The device according to the invention comprises at least one scattering device for producing a mat of the first surface layer containing oriented strands or consisting of oriented strands that have been provided with a binder,

at least one scattering device for producing at least one inner layer mat on the first surface layer mat, more specifically one scattering device or two scattering devices for producing exactly one inner layer mat or at least three scattering devices for producing three inner layer mats , namely the mat of the middle inner layer, bounded on each side by one mat of the outermost inner layer, and in front of said at least one scattering device there is a coupling device,

at least one scattering device for making a mat of the second surface layer, containing oriented strands or consisting of oriented strands, which are provided with a binder on at least one mat of the inner layer, and in front of said at least one scattering device for making a mat of the first and of the second surface layers there is a common binder or one separate binder for each, and behind the scattering devices there is a press for pressing a mat of scattered particles at an elevated temperature compared to standard conditions.

The device according to the invention can be made in two alternatives, which can also be combined with each other.

Appropriate binders serve here to apply at least one binder to the chips. Thus, they are gluing devices.

In a first variant, the apparatus according to the invention comprises (i) at least one sorting machine for the production of a coarse fraction, a medium fraction and optionally a fine fraction, placed upstream of the screening devices, the resulting coarse fraction in each case being sent to a specified at least at least one scattering device for making a mat of the first and second surface layer, the middle fraction and, optionally, the fine fraction are sent to said at least one device for making said at least one mat of the inner layer, and in front of said at least one sorting device there is (ii) at least one mixing zone, such as a mixing bin, for mixing strands and recycled wood chips.

The aforementioned first embodiment of the device according to the invention opens the possibility that a mixture of strands and chips from recycled wood and any chips from virgin wood is first produced and then sorted and used in relation to a separate mat for the manufacture of individual layers of oriented strand board.

The second configuration of the device according to the invention, in particular, allows the production of uniform layers in oriented strand board, for example, uniform surface layers formed exclusively from strands and inner layers formed exclusively from recycled wood chips and any chips from primary wood.

The second option can also be used to control the content of certain types of chips (ie strands and chips from recycled wood and any chips from virgin wood) in individual mats, if the mats are made in accordance with the first option. Thus, this option combines the measures of the first and second options. In the aforementioned first variant, it is particularly advantageous if at least one drying device, for example a mixing hopper, is located between said at least one sorting device and said at least one mixing zone.

In the second variant of the device according to the invention, it can advantageously be the case that separate drying devices are installed in turn in front of each of the respective connecting devices, which are installed in front of the scattering devices.

The device according to the invention preferably additionally comprises at least one shredding device for producing strands (OSB chipper), which is usually installed in front of the mixing hopper. Alternatively or in addition to this, the device according to the invention preferably comprises at least one chipper for producing recycled wood chips, in particular at least one chipper with a knife ring for chipping recycled wood chips, installed in front of the mixing hopper.

More specifically, at least one device for producing chips from recycled wood may be located upstream of the recycled wood chip breaker.

In yet another preferred embodiment of the invention, there is at least one recycled wood chip sorter located between said at least one recycled wood chip breaker and the mixing hopper.

In yet another preferred embodiment of the invention, there is at least one recycled wood chip sorting device located between said at least one recycled wood chipping device and said at least one recycled wood chip making device.

The device according to the invention preferably comprises at least one, preferably more than one of the following devices, and particularly preferably all of the following devices for

• removal of substances having a lower density than wood (eg plastic film, paper, cardboard), for example by pneumatic sorting,

• removal of ferromagnetic metals, for example using magnetic sorting machines,

• removal of non-ferromagnetic metals, especially aluminium, for example using eddy current sorting machines,

• removal of substances having a higher density than wood (stones, glass, sand, minerals) using gravimetric sorting, such as air filter sorters, gravity sorters or flotation sorters and/or

• removal of non-woody substances, eg using X-ray sorters and/or video sorters.

The present invention is explained in detail with reference to the drawings below and does not limit the invention to the specific characteristics indicated.

On the drawings:

Fig. 1 shows a first embodiment of the proposed oriented strand board,

fig. 2 shows another embodiment of the proposed oriented strand board,

fig. 3 shows a variant of the device for the production of the proposed wood-based oriented strand board,

fig. 4 shows a production line for processing recycled wood upstream of the apparatus of FIG. 3, and

in fig. 5 shows another version of the device for the production of the proposed wood-based oriented strand board.

In FIG. 1 shows a first configuration of the proposed oriented strand board. This board has a three-layer structure and contains two surface layers, namely the upper surface layer 11 and the lower surface layer 12. The surface layers 11, 12 here consist either of 100% strands (OSB strands) or a mixture of strands and smaller chips of recycled wood, although in the surface layers 11, 12 the mass fraction of strands preferably prevails over recycled wood chips. The oriented strand board according to FIG. 1 also comprises an inner layer 20 formed from 100% recycled wood chips or (as in the present case) a mixture of strands and recycled wood chips, wherein the inner layer 20 has a higher weight fraction of recycled wood chips than strands. All chips within the individual layers are bonded to each other using a suitable binder and pressed. Oriented strand board is made by pressing a scattered particle mat composed of different strand mats that are provided with a binder to bond to each other.

A corresponding mat of scattered particles is also shown in FIG. 1. In this case, the mat 12' of the lower surface layer is laid first. Since the surface layer mat is formed either from 100% strands or from a mixture of mainly strands and recycled wood chips as described above, the strands are laid in a manner known in the art so that the chips are given a preferred direction and hence in a mat 12 ' the oriented alignment of the strands takes place in the lower surface layer. An inner layer mat 20', consisting, for example, of 100% recycled wood chips or a mixture of recycled wood chips and strands, is laid on top of the lower surface layer mat 12', the inner layer mat 20' having a mass fraction of recycled wood chips preferably greater than the proportion of strands. A further upper surface layer mat 11' is laid on top of the inner layer mat 20', the chips used in the upper surface layer mat being preferably identical to those also used in the lower surface layer mat 12'.

This is also true for any chip mixtures used in the respective upper and lower skin mats 11', 12'. In the production of individual mats, the used chips or chip mixtures have already been provided with a binder. The resulting scattered particle mat is finally pressed in a manner known in the art to form a finished oriented strand board.

In FIG. 2 shows another embodiment of the oriented strand board according to the invention which, in contrast to the oriented strand board shown in FIG. 1 has a five-layer configuration.

The oriented strand board here - and similarly to the board according to FIG. 1 - has upper and lower surface layers 11, 12, which are formed either 100% from strands or from a chip mixture formed with a predominant proportion of strands, as well as with a smaller proportion of chips from recycled wood.

The oriented strand board according to FIG. 2 comprises three inner layers, namely a middle inner layer 22 delimited by two outermost inner layers 21, 23. The middle inner layer 22 is formed either from 100% by weight recycled wood chips or includes, along with recycled wood chips, a small share of strands. In the extreme inner layers 21, 23, the proportion of strands may be greater than in the middle inner layer, but less than in the surface layers 11, 12.

In FIG. 2 also illustrates the sequence of mats used in the manufacture of the oriented strand board shown in FIG. 2.

First of all, a bottom surface layer mat 12' is produced, on which the first innermost layer mat 23' is laid. A mat 22' of the middle inner layer is scattered onto it, then another mat 21' of the surface layer, and finally a mat 11' of the upper surface layer. The resulting scattered particle mat is then pressed to form a finished oriented strand board.

In FIG. 3 shows the general configuration of an oriented strand board machine according to the present invention. Using the device according to FIG. 3, it is possible to produce the three-layer chipboard shown in FIG. one.

For the manufacture of the respective mats, there are three separate diffusers, each of which is intended for the manufacture of the respective mat. Using the diffuser 112, a lower surface layer mat 12' containing oriented strands can be obtained. The diffuser 120 serves to produce an inner layer mat 20' which is laid on top of the lower surface layer mat 12'. Using the diffuser 111, a mat 11' of the upper surface layer can be formed on the mat 20' of the inner layer. More specifically, the continuous production of mats is possible by applying individual mats 11', 20', 12', for example, to a conveyor belt (not shown). The mats are subsequently fed in a similar manner to a pressing device 200, in which the individual layers of mat, consisting of chips, which have been provided with a binder, are pressed to form a finished oriented strand board.

If additional mats are to be formed, for example to obtain the oriented strand board shown in FIG. 2 include additional diffusers to diffuse the respective mats. Here, in front of the diffusers 111 and 112, there is a common bonding device 310 in which the strands used in the respective surface layer mats 11' and 12' are glued together. For example, this apparatus may comprise conventional large sizing drums (drum sizing machines). The spreader 120 for gluing the chips used in the inner layer mat 20' also has a forward bonding device 320. device 320 of a standard mixing device for gluing chips.

Chips can be fed into the binders in two different ways, which are detailed below.

The first option is to supply a pre-sorted mixture of chips containing strands (which are preferably obtained by chipping virgin wood, for example, in an OSB chipper) and recycled wood chips (which are obtained, for example, by chipping chips from used wood in a chipper with ring knife).

This option is shown in Fig. 3 in the part shown above. In this case, first of all, the recycled wood chips are used to produce recycled wood chips (referred to as recycled wood chips) in the shredding device 800, for example, in a knife ring device. This is preferably followed by sorting of the recycled wood chips obtained in the sorting device 850. For this, for example, disc or roller sorting machines, but also screening devices can be used. A combination of the above sorting methods is also possible. In the example shown in FIG. 3, using the sorter 850, the production of three fractions of recycled chips is achieved, including the fine fraction 851, including, for example, dust and very fine particles. The fine fraction 851 can be used, for example, for heat production. The resulting coarse fraction 853 can preferably be returned to the grinding device 800 for further use as a raw material. The resulting medium size fraction 852, which satisfies the required chip size requirements of recycled wood, can be used to produce the present oriented strand board.

The medium size fraction 852 of recycled wood chips is sent to a mixing hopper 600. The hopper 600 is also fed with strands that have been produced, for example, in a VFW chipper 700, such as an OSB chipper. The mixing hopper 600 may be an active or passive mixing device. In the case of an active mixing hopper, the chips are actively moved to produce a mixture of chips. In a passive mixing bin, in contrast, active mixing does not occur; instead, the chips are mixed by themselves, including, if necessary, during transport. An example of a passive mixing zone here is a hopper with a moving conveyor belt, into which the appropriate strands or recycled wood chips are introduced, stored for further processing.

In particular, it is also possible to introduce into the mixing hopper 600 (input variant 601) chips that have been obtained by chipping virgin wood chips, so that the mixture of chips in this case contains three different types of chips.

The mixture of chips stored in the mixing hopper 600 is then fed to the dryer 500, in which the mixture of chips is dried together. The most suitable devices for this are drum or belt dryers.

In some cases, it is also possible for the dryer 500 to also function as a mixing bin 600, so that individual types of chips, i.e., strands and the average fraction of recycled wood chips 852, are individually fed into the dryer 500 and mixed therein as they dry. In this case, the mixing hopper and the dryer are identical.

The dried mixture of chips is then sent to the sorting device 400, in which the mixture of chips, in the example of the device according to FIG. 3 is separated into two fractions, namely, a surface layer fraction 410 and an inner layer fraction 420. The sorting device, in particular, may be roller or disk; it is also possible to use screening devices or a combination of the above devices.

The inner layer fraction 420 obtained in this case contains a larger proportion by weight of recycled wood chips than the surface layer fraction 410. The strands present in the inner layer fraction 420 are preferably smaller (ie, have a smaller number average length) than the strands present in the surface layer fraction 410.

If it is desired to manufacture the oriented strand board shown in FIG. 2, the dried mixture of chips is divided into three fractions, in which case a fine fraction is also obtained, which, after gluing, can in particular be used to produce a mat of the middle inner layer. This option is not shown in Fig. 3.

The individual fractions, i.e., the surface layer fraction 410 and the inner layer fraction 420, are sent to the respective binders 310 and 320 and then dispersed as described above to form separate surface layer mats 11' and 12' or inner layer mat 20'.

Alternatively or additionally, it is also possible to feed the respective recycled wood chips obtained using the chipper 800 or strands obtained using the chipper 700 into separate dryers 501 and 502. This embodiment is shown in FIG. 3 dotted arrows.

For example, it is possible to feed the resulting middle cut 852 to a separate dryer 502 without pre-mixing with the strands. The same variant is also possible for strands made using the shredder 700. These chips can also be fed into a separate dryer 501, for example. Suitable uniform strands or recycled wood chips can then each be fed into the binders 310 and 320 and dispersed. . It is thus possible to obtain uniform mats of the surface layer 11', 12' or mats of the inner layer 20'. It is also possible to mix homogeneous chips with fractions 410 and 420 to increase or decrease the proportion of the respective types of chips. These options make sense in particular when the thickness of the oriented strand board needs to be changed during the workflow, so that the total proportion of recycled wood chips in the oriented strand board can also be changed if necessary.

Similarly, virgin wood chips 601 can be introduced into a recycled wood chip processing line.

The section of the plant, indicated by the dashed lines labeled A, which is used to produce chips from recycled wood shredded in apparatus 800, is shown separately in FIG. 4 and, preferably, is also part of the device shown in FIG. 3.

In FIG. 4 is a block diagram illustrating how the PD processed wood feed is used to produce processed wood chips that can be chipped in the apparatus 800 shown in FIG. 3.

Feed processed wood, if desired, is first coarsely pre-crushed using a crushing device 1100, such as a chipper. This is especially necessary when the recycled wood is supplied, for example, in the form of solid pieces of furniture or large wooden beams, wood-based panels (eg oriented strand boards). Recycled wood is, in particular, wood of categories A I and A I I in accordance with the Altholzverordnung legislation of the Federal Republic of Germany. The crusher 1100 produces smaller fragments that can later be processed into chips.

Thus, behind the chipper 1100, a corresponding device 1000 for the production of chips is installed. In particular, chippers, such as disc or drum chippers, or a hammer mill can be used as such a device.

It is also possible for one or more devices to be installed between the crusher 1100 and the chipper 1000 to remove foreign matter, such as ferromagnetic metals (especially iron), non-ferromagnetic particles (especially aluminum), non-wood materials, especially stones, glass, ceramics. or plastics. In the example device according to FIG. 4, the removal of ferromagnetic materials in this case is performed, for example, using permanent magnets or electromagnets 910, and the removal of aluminum components, if necessary, is performed, for example, using an eddy current sorting machine 920.

The chips obtained using the chipper 1000 are preferably sorted in the sorting device 950 into three fractions 951, 952, 953. The fraction of chips having the smallest average dimensions 951 can be sent, for example, to the production of particle board or used to produce heat .

The largest average chip size 953 can be sent back to chipper 1000.

Fraction 952 chips with suitable average largest sizes can be used for further processing and final grinding to obtain chips from recycled wood. If the recycled wood chips are produced elsewhere, they can be introduced into the device 950. This possibility is illustrated in FIG. 4 designation C.

Before grinding in the chipper 800, the chips are preferably subjected to multiple cleanings.

To do this, for example, substances having a lower specific gravity than wood, such as plastic films or a wide range of different paper or cardboard materials, can be removed by pneumatic sorting 905. Ferromagnetic metals are also removed using the 910 magnet, and non-ferromagnetic metals, such as aluminum, using the 920 eddy current sorter. In addition, density separation 930 is also possible, in which, for example, substances having a higher specific gravity than wood are removed, especially stones, ceramics and glass. The remaining impurities, which are mainly polymeric materials, can be removed, for example, by x-ray sorting and/or video sorting 940. The various purification steps can also be performed more than once or be performed more than once. The manufactured chips, as also shown in FIG. 4 with the designation A is fed into the grinder 800 shown in FIG. 3. In addition, in the case of injection option 954, virgin wood chips can be additionally added together with recycled wood chips and crushed together in the chipper 800.

In FIG. 5 shows a further embodiment of the proposed device for producing oriented strand board. The device configuration differs from the device shown in FIG. 3, there is a sorting device 400 for sorting the mixture of chips. The components located in front of the proposed device, as before, are not shown for clarity. However, interfaces with components not shown per se are shown (dryers 500, 501, 502). The device according to FIG. 5, in contrast to the device according to FIG. 3 has a total of five diffusers 111, 121, 122, 123, 112, and thus allows the production of a five-layer oriented strand board such as that shown in FIG. 2. A particular advantage of the device according to FIG. 5 that should be mentioned is that it can be operated flexibly and also enables the production of a three-layer oriented strand board, which is shown, for example, in FIG. 3. The device shown in FIG. 5 includes a sorter 400 for sorting the dried mixture of chips obtained from the dryer 500.

Unlike the device according to FIG. 3, the sorting device 400 separates the mixture of chips into three fractions, namely the surface layer fraction 410, the middle fraction 420 and the fine fraction 421. Fractions 410, 420 and 421 are characterized by reduced average chip sizes (number average), especially a reduced average chip length (number ). The surface layer fraction 410 contains mainly strands and is used to make the surface layer mats 11', 12'. Middle cut 420, as configured, contains some recycled wood strands and chips (and optionally some virgin wood chips, which can be used when feed means 601 are used) and is used to make mat of the extreme inner layer 21', 23'. The 421 fines are essentially strand free and consist primarily of recycled wood chips (and any virgin wood chips). The inner layer fraction 420 can also be adjusted to be substantially strand free.

In this case, the core fraction 420 essentially consists of recycled wood chips (and any virgin wood chips). In this case, the average chip size (number average), especially the average length (number average) of the recycled wood chips (and any virgin wood chips) present in the inner layer fraction 420, is greater than the average size (number average), especially the average length (number average) , recycled wood chips (and any virgin wood chips) present in the fines 421. To remove dust or extra fines 460, this fraction can, if necessary, be sent to an appropriate sorting device 450, for example, a screening device, to obtain a fine fraction 422, which will be essentially completely free of dust, which can preferably be used for the purposes of the present invention. The dust can, for example, be used to produce heat or to produce particle board.

The fraction 410 of the surface layer is fed into the binder 310 and provided with a binder therein. It is also possible to separately dose the strands into the binder 310, for example from a dryer 501, which is not shown in FIG. 5. The surface layer fraction 410, which is provided with a binder, is introduced into the two scattering devices 111, 112 and scattered there to obtain the respective surface layer mats 11', 12'.

The device according to Fig. 5 contains two additional binders 320, 322, of which, in the case of the production of a three-layer oriented strand board, only the binder 320 is used, and in the case of the production of a five-layer oriented strand wood board, both binders 320, 322 are used.

If a three-ply oriented strand board is being produced, the block diagram shown in solid lines starting from the binders 310, 320, 322 is used, and in the case of the production of a five-ply oriented strand board, the block diagram shown in dashed lines. First of all, the production of a three-layer oriented strand wood board using the apparatus shown in FIG. 5. Inner layer fraction 420 is sent to binder 320. At the same time, fines 422 (or, if fines 421 is not sorted further (450), fines 421) are introduced into binder 320. Combined fractions 420 and 422 (or 421) are glued in the binder 320 and then inserted into the diffuser 122 to form the mat 20' of the inner layer (the only one in this case). Chip mixtures do not enter the two scattering devices 121 and 123, as well as the binder 322.

For the production of a five-layer oriented strand board, only the fraction 420 of the inner layer is introduced into the binder device 320, then the fraction of the inner layer provided with the binder is introduced in equal parts into each of the scattering devices 121, 123 to disperse the respective mats 21', 23' of the outermost inner layer . The fines 422 (or the fines 421 if the fines 421 is not further sorted (450)) are introduced into the binder 322, then the fines 422 or 421 provided with the binder are introduced into the dispersion device 122 and an inner layer mat 22' is produced.

In each case, the fabricated scattered particle mat, as illustrated in FIG. 3 is sent to an oriented strand board press 200.

List of symbols

11 top surface layer

12 lower surface layer

20 inner layer

21, 23 extreme inner layer

22 middle inner layer

11' top layer mat

12' bottom layer mat

20' inner layer mat

21', 23' outer layer mat

22' mat middle inner layer

111, 112, 120, 121, 122 diffusers

200 press

310, 320, 322 couplers

400 chip sorter

410 surface layer fraction

420 fraction of the inner layer, fraction of the outermost layer

421 fines for further sorting

422 fine fraction, middle inner layer fraction

450 fines sorter 421

460 wood dust fraction/extra fine

500, 501, 502 dryer

600 mixing hopper

601 virgin wood chip feeding options

700 OSB shredder

800 chipper for chipping recycled wood / virgin wood chips

850 recycled wood chip sorter

851 recycled wood chips

852 medium fraction of recycled wood chips

853 coarse fraction of recycled wood chips

905 pneumatic sorting

910 magnet

920 eddy current sorting machine

930 gravimetric sorting

940 x-ray/video sorting

950 wood dust

951 fine chips

952 medium fraction of wood chips

953 coarse chips

954 virgin wood chip input option

1000 chipper

1100 crusher.

Claims (49)

1. Wood board with oriented strands, containing at least the following three layers: a) the upper surface layer (11), containing or consisting of oriented strands connected to each other by means of a binder, b) at least one inner layer (20, 21, 22, 23) containing chips that were obtained from recycled wood (HR) and which are bonded to each other by means of a binder, c) the lower surface layer (12) containing or consisting of oriented strands bound to each other by means of a binder , wherein said at least one inner layer (20, 21, 22, 23) is located between two surface layers (11, 12). 2. Wood board according to claim 1, characterized in that said at least one inner layer (20, 21, 22, 23) contains a mixture of chips obtained from recycled wood and strands connected to each other by means of a binder, or formed from this mixture. 3. Wood board according to claim 1 or 2, characterized in that the strands present in said at least one inner layer (20, 21, 22, 23) have a shorter average length (number average) than the strands present in the upper and lower surface layers (11, 12). 4. Wood board according to any one of the preceding claims, characterized in that it has exactly one inner layer (20) or three inner layers, namely the middle inner layer (22) delimited by two extreme inner layers (21, 23). 5. Wood board according to any one of the preceding claims, characterized in that the mass fraction of chips obtained from recycled wood in said at least one inner layer (20, 21, 22, 23), especially in exactly one inner layer (20) , referred to all strands and chips in this layer (20, 21, 22, 23), is at least 5 wt.%, preferably at least 50 wt.%, more preferably at least 60 wt.%, even more preferably at least 70% by weight, most preferably at least 80% by weight. 6. Wood board according to any of the preceding claims, characterized in that if it has three inner layers, namely the middle inner layer (22), limited by the two extreme inner layers (21, 23), the mass fraction of chips obtained from recycled wood in the middle inner layer (22) is higher than in the outermost inner layers (21, 23), and the mass fraction of strands with a shorter average length (number average) compared to strands in the upper and lower surface layers (11, 12) is less in the middle inner layer (22) than in the extreme inner layers (11, 12). 7. Wood board according to claim 6, characterized in that the mass fraction of chips obtained from recycled wood in the middle inner layer (22), referred to the sum of all strands and chips in this layer (22), is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably at least 50 to 90 wt.%, most preferably from 60 to 85 wt.%, and/or the mass fraction of chips obtained from recycled wood in the outermost layers (21, 23), referred to all chips in the outermost inner layers (21, 23) is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably from 20 to 80 wt.%, most preferably from 30 to 70 wt.%, and the mass fractions of chips , obtained from recycled wood, in the middle inner layer (22) and in the outermost inner layers (21, 23) are different, so that the mass fraction of chips obtained from recycled wood in the middle inner layer (22) is preferably greater than in the outermost inner layers (21, 23). 8. Wood board according to any one of the preceding claims, characterized in that if the oriented strand board has three inner layers, namely a middle inner layer (22) delimited by two outermost inner layers (21, 23), and at least the outermost inner layers (21, 23) contain strands, the strands in the outermost inner layers (21, 23) are located across the orientation of the oriented strands in the surface layers (11, 12). 9. Wood board according to any one of the preceding claims, characterized in that the strands present in the upper and/or lower surface layer (11, 12) have an average length (number average) of 40 to 250 mm, preferably 70 to 150 mm, average a width (number average) of 2 to 40 mm, preferably 5 to 25 mm, and/or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm. 10. Wood board according to any of the preceding claims, characterized in that the chips obtained from recycled wood have an average length (number average) from 5 to 50 mm, preferably from 10 to 30 mm, an average width (number average) from 0.2 to 10 mm, preferably 0.5 to 5 mm, and/or an average thickness (number average) of 0.3 to 2 mm, preferably 0.3 to 1.2 mm. 11. Wood board according to any one of the preceding claims, characterized in that the strands present in said at least one inner layer (20, 21, 22, 23) have an average length (number average) from 10 to 150 mm, preferably from 30 up to 100 mm, average width (number average) from 0.5 to 30 mm, preferably from 2 to 15 mm, and/or average thickness (number average) from 0.3 to 1.5 mm, preferably from 0.5 to 1, 2 mm, and the average length (number average) is less than the average length of the strands present in the upper and/or lower surface layers (11, 12). 12. Wood board according to any one of the preceding claims, characterized in that the recycled wood chips are obtained by chipping recycled wood (HRW) chips, in particular using a knife ring chipper. 13. Wood board according to any of the preceding claims, characterized in that the strands present in the upper surface layer (11) and in the lower surface layer (12) are oriented with respect to the longitudinal axis of the wood board so that at least 60%, preferably at least 70%, most preferably at least 80%, of the strands deviate in their longitudinal alignment from the longitudinal direction of the wood board by no more than 20°. 14. Wood board according to any one of the preceding claims, characterized in that the oriented strands in the upper surface layer (11) and the lower surface layer (12) are oriented in the same way. 15. Wood board according to any one of the preceding claims, characterized in that the total thickness of the wood board is from 4 to 100 mm, preferably from 6 to 40 mm. 16. Wood board according to any one of the preceding claims, characterized in that the thickness of the upper and lower surface layers (11, 12) is from 20 to 60%, preferably from 25 to 50%, more preferably from 30 to 40%, and/or the thickness of said at least one inner layer (20, 21, 22, 23) is 80 to 40%, preferably 75 to 50%, more preferably 70 to 60% of the total thickness of the wood board. 17. Wood board according to any one of the preceding claims, characterized in that the density of the backfill of the wood board is from 450 to 750 kg/m ³ , preferably from 520 to 670 kg/m ³ . 18. Wood board according to any one of the preceding claims, characterized in that the binder used to bind the respective chips is selected from the group consisting of binders based on polymeric diphenylmethane diisocyanate (PMDI), binders based on melamine formaldehyde urea (MUF), binders based on melamine urea phenol formaldehyde (MUPF ), phenol formaldehyde-based binders, natural binders, such as starch-based binders, protein-based binders, decomposed tannin, lignin or carbohydrate binders, thermoplastic or cross-linked thermoplastic adhesives, and mixtures and combinations thereof. 19. Wood board according to any one of the preceding claims, characterized in that the strands present in the upper surface layer (11) and/or in the lower surface layer (12), as well as the strands that may be present in said at least one inner layer , obtained by milling virgin fiber wood (VFW). 20. A method for producing an oriented strand board according to any one of claims 1 to 19, wherein the scattered particle mat is obtained by a) making (112) a surface layer mat (12') containing strands or consisting of strands provided with a binder, by oriented scattering of strands that have been provided with a binder, or a chip mixture containing strands that have been provided with a binder, b) scattering (120, 121, 122, 123) of at least one mat of the inner layer (20', 21', 22' , 23') containing chips, which were obtained by grinding recycled wood (WP) and provided with a binder, on the mat of the surface layer (12') obtained in step a), c) of manufacturing (111) an additional mat (11') of the surface layer containing strands or consisting of strands that have been provided with a binder, on said at least one mat (20', 21', 22', 23') of the inner layer obtained in step b), by oriented dispersion of the strands that were and provided with a binder, or a chip mixture containing strands that have been provided with a binder, and then a mat of dispersed particles to cure and harden the binder is pressed (200) at an elevated temperature relative to standard conditions to obtain an oriented strand board. 21. Method according to claim 20, characterized in that the recycled wood chips are obtained by chipping recycled wood chips (800), in particular using a knife ring. 22. The method according to claim 21, characterized in that the chips from recycled wood (WP) are obtained by crushing (1000) recycled wood (WP), especially using a chipper, such as a drum or screw, hammer mill or impact crusher, or receive from an external source. 23. The method according to claim 22, characterized in that the processed wood (WP) is roughly pre-crushed (1100) to form chips (1000) before crushing, for example, using a chipper. 24. The method according to any one of claims 21 to 23, characterized in that the strands are sorted (950) before grinding using a sorting machine (sorting by size), especially using a disk sorting machine and/or a roller sorting machine, wherein the fraction (952 ) chips having the largest size (number average) from 20 to 150 mm, preferably from 30 to 120 mm, are sent for grinding (800), and preferably a chip fraction (953) having an average largest size (number average) of more than 150 mm, preferably more 120 mm is sent back to the crushing operation (1000) for the production of chips and/or preferably the fraction of chips (951) having an average largest size (number average) of less than 20 mm, preferably less than 30 mm, is used for the production of heat or for the production of wood chips plates. 25. The method according to any one of claims 21 to 24, characterized in that before grinding (800) and / or before crushing (1000) at least one of the following steps is carried out in any sequence, preferably all subsequent steps: removal of substances having lower density than wood (e.g. plastic film, paper, cardboard), e.g. by pneumatic sorting (905), removal of ferromagnetic metals (910), e.g. using magnetic sorters, removal of non-ferromagnetic metals (920), especially aluminum eg using eddy current sorters, removal of substances having a higher density than wood (stones, glass, sand, minerals), gravimetric sorting (930), e.g. air separators, gravity sorters or flotation sorters and/or removal of non-woody substances, for example using X-ray sorters and/or video sorters (94 0). 26. The method according to any one of claims 20 to 25, characterized in that the recycled wood chips are sorted by size (850) before the production of the scattered particle mat, using the medium fraction (852) to produce the scattered particle mat and especially with the removal of fine fraction (851) and, for example, using it for the production of heat and/or removing the coarse fraction (853), which is sent back to grinding. 27. A method according to any one of claims 20 to 26, characterized in that the recycled wood chips, after they have been obtained by grinding (800), are mixed (600) with strands, in particular those obtained by grinding (700) virgin fiber wood (VFW). 28. The method according to any one of claims 20 to 27, characterized in that the chips obtained from recycled wood and / or strands, especially a mixture of chips obtained from processed wood and strands, are dried (500), especially in a drum dryer, or the chips used in the mats (11', 12') of the surface layer and in the corresponding mats (20', 21', 22', 23') of the inner layer are dried in each case separately before applying the binder. 29. The method according to claim 27 or 28, characterized in that the mass fraction of chips obtained from recycled wood to strands in the mixture is selected from 5:95 to 95:5, preferably from 20:80 to 90:10, more preferably from 40:60 to 75:25, most preferably 45:55 to 60:40. 30. Method according to any one of claims 27 to 29, characterized in that, before producing the scattered particle mat, the mixture is sorted (400) according to the average size of the recycled wood chips and strands, and in particular sorted using disc sorters , screens, roller sorters, vibrating sorters or a combination of two or more of the same or different above, per fraction (410) of the surface layer, which contains strands and which is used to produce mats (11', 12') of the surface layer, and the fraction of the inner layer (420), which is used to produce said at least one mat (20', 21', 22', 23') of the inner layer, in particular said exactly one mat (20') of the inner layer or mats (21', 23' ) of the extreme inner layer, and the fraction of the inner layer (420) may include strands having a smaller average length (number average) than the strands present in the fraction of the surface layer and, optionally, fines (421), which is partly or wholly formed by recycled wood chips and which is used to produce the mat (22') of the middle inner layer. 31. The method according to claim 29 or 30, characterized in that in step b) exactly one mat (20') of the inner layer or three mats of the inner layer, located one on top of the other, namely the mat (22') of the middle inner layer, bounded on each side by one mat (21', 23') of the outermost inner layer. 32. The method according to any one of claims 20-31, characterized in that in said at least one mat (20', 21', 22', 23') of the inner layer, the mass fraction of recycled wood chips, especially in said exactly one mat (20') of the inner layer, referred to all the chips in the specified at least one mat (20', 21', 22', 23') of the inner layer, is at least 5 wt.%, preferably at least 50 wt. .%, more preferably at least 60 wt.%, even more preferably at least 70 wt.%, most preferably at least 80 wt.%, and the mass fraction of strands of a smaller average length (number average) compared to the strands in the mat (11', 12') of the upper and lower surface layer is not more than 95 wt.%, preferably not more than 50 wt.%, more preferably not more than 40 wt.%, even more preferably not more than 30 wt.%, most preferably not more than 20 wt.%. 33. A method according to any one of claims 20 to 32, characterized in that if three mats of the inner layer are made, namely the mat (22') of the middle inner layer, delimited on each side by one mat (21', 23') of the outermost inner layer layer, the mass fraction of chips obtained from recycled wood in the mat (22') of the middle inner layer is set higher than in the mats (21', 23') of the outermost inner layer, and the mass fraction of strands having a smaller average length (number average) compared with the strands in the two mats (11', 12') of the surface layer, the mat (22') of the middle inner layer is set at a lower level than in the mats (21', 23') of the outermost inner layer. 34. A method according to any one of claims 20 to 33, characterized in that the mass fraction of recycled wood chips in the mat (22') of the middle inner layer, related to all chips in this mat, is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably at least 50 to 90 wt.%, most preferably from 60 to 85 wt.%, and/or the mass fraction of recycled wood chips in mats (21', 23') of the extreme of the inner layer, related to all the chips in these mats, is at least 5 wt.%, preferably from 5 to 100 wt.%, more preferably from 20 to 80 wt.%, most preferably from 30 to 70 wt.%, and the mass fraction of recycled wood chips in the mat (22') of the middle inner layer and in the mats (21', 23') of the outermost inner layer are different in each case, so that the mass fraction of recycled wood chips in the mat (22') of the middle inner layer preferably more than in the mats (21', 23') of the innermost layer . 35. A method according to any one of claims 20 to 34, characterized in that if a mat (22') of the middle inner layer is produced, which is limited (21', 23') by two mats of the outermost inner layer, and at least in mats ( 21', 23') of the innermost layer contains strands, the outer middle chips in the mats (21', 23') of the outermost layer are located across the orientation of the oriented strands in the mats (11', 12') of the surface layer. 36. Method according to any one of claims 20 to 35, characterized in that the strands present in the mats (11', 12') of the surface layer have an average length (number average) of 40 to 250 mm, preferably 70 to 150 mm, an average width (number average) of 2 to 40 mm, preferably 5 to 25 mm, and/or an average thickness (number average) of 0.3 to 1.5 mm, preferably 0.5 to 1.2 mm. 37. The method according to any one of claims 20 to 35, characterized in that the chips obtained from recycled wood have an average length (number average) from 5 to 50 mm, preferably from 10 to 30 mm, an average width (number average) from 0, 2 to 10 mm, preferably 0.5 to 5 mm, and/or an average thickness (number average) of 0.3 to 2 mm, preferably 0.3 to 1.2 mm. 38. The method according to any one of claims 20-37, characterized in that the strands present in said at least one mat (20', 21', 22', 23') of the inner layer have an average length (number average) of 10 to 150 mm, preferably from 30 to 100 mm, an average width (number average) from 0.5 to 30 mm, preferably from 2 to 15 mm, and/or an average thickness (number average) from 0.3 to 1.5 mm, preferably from 0.5 to 1.2 mm, the average length (number average) being less than the length of the strands present in the mats (11', 12') of the surface layer. 39. The method according to any one of claims 20-38, characterized in that in step a) and step c) the strands are oriented relative to the longitudinal axis of the oriented chipboard so that at least 60%, preferably at least 70%, most preferably at least 80%, the strands deviate in the longitudinal direction from the longitudinal direction of the oriented chipboard by no more than 20°. 40. Method according to claim 39, characterized in that the strands in step a) and step c) have the same orientation. 41. Method according to any one of claims 20 to 40, characterized in that the total thickness of the oriented strand board is from 4 to 100 mm, preferably from 6 to 40 mm. 42. The method according to any one of claims 20 to 41, characterized in that the binder is selected from the group consisting of binders based on polymeric diphenylmethane diisocyanate (PMDI), binders based on melamine formaldehyde urea (MUF), binders based on melamine urea phenol formaldehyde (MUPF), binders based on phenol formaldehyde, natural binders, such as starch-based binders, protein-based binders, decomposed tannin, lignin or carbohydrate binders, thermoplastic or cross-linked thermoplastic adhesives, and mixtures and combinations thereof. 43. A device for producing oriented strand board according to any one of claims 1 to 19 and/or for implementing a method according to any one of claims 20 to 42, comprising at least one scattering device (112) for producing a first mat (12' ) a surface layer containing oriented strands or consisting of oriented strands that have been provided with a binder, at least one scattering device (120, 121, 122, 123) for the manufacture of at least one mat (20', 21' 22', 23 ') of the inner layer on the first mat (12') of the surface layer, in particular one scattering device (120, 121, 122, 123) or two scattering devices to produce exactly one inner layer mat (20') or at least three scattering devices for the manufacture of three mats of the inner layer, namely the mat (22') of the middle inner layer, bounded on each side by one mat (21', 23') of the outermost inner layer, moreover, before said at least one scattering at least one binding device (320, 322) for applying the binder to the chips of the specified at least one mat (20', 21', 22', 23') of the inner layer, wherein the device for the production of wood board also contains at least one scattering device (111) for the production of the second mat (11') of the surface layer containing oriented strands or consisting of oriented strands, which were provided with a binder, on the specified at least one mat (20', 21', 22', 23') of the inner layer, and in front of the specified at least one scattering device (111) for the manufacture of the first (12') and second (11') mats of the surface layer, there is a common binding device (310 ) for applying a binder to the chips of the mats (11', 12') of the surface layer or one separate binder for each mat, while the device for the production of wood board also contains a press (200), located behind the scatterers (112, 120, 121, 122, 123, 111) for pressing the scatter mat at an elevated temperature relative to standard conditions, characterized in that a) it comprises at least one sorter (400) installed in front of scattering devices (112, 120, 121, 122, 123, 111), to obtain a fraction of the surface layer (410), a fraction of the inner layer (420) and, optionally, a fine fraction (421, 422), and the resulting fraction of the surface layer (410 ) is sent in each case to said at least one scattering device (111, 112) for the production of the first and second mat (11', 12') of the surface layer, the middle fraction (420) and, optionally, the fine fraction (421, 422) sent to the specified at least one scattering device (120, 121, 122, 123) for the production of at least one mat (20', 21', 22', 23') of the inner layer, and before the specified at least one sorting device (400) installed according to at least one mixing hopper (600) for mixing strands and chips from recycled wood and/or b) before each at least one scattering device (111, 112) for manufacturing the first and second mat (11', 12') of the surface layer is located chopping device (700) for producing strands from virgin wood, and before said at least one scattering device (120, 121, 122, 123) for manufacturing at least one mat of the inner layer (20', 21', 22', 23 ') is located at least one chipping device (800) for grinding recycled wood (WP) to obtain shavings from recycled wood. 44. The device according to claim 43, characterized in that a) between said at least one sorting device (400) and said at least one mixing bin (600) is located at least one drying device (500) and / or b ) before each of the respective connecting devices (310, 320, 322) located in front of the scattering devices, in turn, a separate drying device (501, 502) is located. 45. Apparatus according to claim 43 or 44, comprising at least one shredding device (700) for producing strands (OSB chipper), which is specially installed in front of the mixing hopper (600), and/or at least one shredding device (800 ) for the production of chips from recycled wood, in particular at least one chipper with a knife ring for chipping chips from recycled wood (WP), which is specially installed in front of the mixing hopper (600). 46. Apparatus according to any one of claims 43 to 45, characterized in that at least one apparatus for producing recycled wood (WP) chips is located upstream of the chipper (800) for producing recycled wood chips. 47. Device according to any one of claims 43-46, characterized in that there is at least one device (850) for sorting chips obtained from recycled wood, located between said at least one chipping device for producing chips obtained from recycled wood. and a mixing bin (600), and/or there is at least one recycled wood chip sorting device (950) installed between said at least one chipping device for producing recycled wood chips and said at least one device for the production of chips from used wood. 48. A device according to any one of claims 43-47, characterized in that it comprises at least one device, preferably all of the following devices, for removing substances having a density lower than that of wood (e.g. plastic film, paper, cardboard) e.g. by pneumatic sorting (905), removal of ferromagnetic metals (910), e.g. using magnetic sorters, removal of non-ferromagnetic metals (920), especially aluminum, e.g. using eddy current sorting machines, removal of substances having a higher density, than the density of wood (stones, glass, sand, minerals), gravimetric sorting (930) such as air separators, gravity sorters or float sorters, and/or removal of non-wood substances, for example using x-ray sorters and/or video sorters (940).

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