DE102024000536A1 - Material plate and method for producing a material plate and use of a material plate - Google Patents

Abstract

The invention relates to a material plate (1) and a method for producing the same, wherein the material plate has a pressed core layer (2) and at least one first cover layer (3) and optionally a second cover layer (4) on the opposite side of the first cover layer, each of which is formed from a mixture (7, 8) formed from lignin-containing particles (5, 6) and a binder, which is formed into a solid structure in a chemical and/or mechanical bonding process, wherein the lignin-containing particles (5) of the mixture of the core (7) are formed essentially from chip material and the lignin-containing particles (6) of the mixture of the at least one cover layer (3, 4) are formed from fiber material. In order to provide a material plate which has a cover layer surface which is largely homogeneous in terms of color for easy decoration and which can nevertheless be produced with low production expenditure, it is provided that for the mixture of the core (7) the chip sizes in chip size layers decrease towards the at least one cover layer (3, 4) from a layer of coarse chip material (2b) with the individual chip dimensions length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a layer (2a, 2c) of fine chip material with the individual chip dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm, wherein up to 20% of the fine chip material can still be contained in the spaces between the coarse chip layers (2b).

Description

The invention relates to a material plate which has a pressed core layer and at least one first cover layer and optionally a second cover layer on the opposite side of the first cover layer, each of which is formed from a mixture formed from lignin-containing particles and a binder which is formed into a solid structure in a chemical and/or mechanical bonding process, wherein the lignin-containing particles of the mixture of the core are formed essentially from chip material and the lignin-containing particles of the mixture of the at least one cover layer are formed from fibrous material.

The invention further relates to a use of a material panel for interior construction of apartments.

The invention further relates to a method for producing a material board which has at least one core layer and at least one first cover layer and optionally a second cover layer on the opposite side of the first cover layer, each of which is formed from a mixture formed from lignin-containing particles and a binder, wherein this is formed into a solid structure in a chemical and/or mechanical bonding process under the influence of pressure and temperature, and wherein chip material is used as the lignin-containing particles of the mixture of the core and fibre material is used as the lignin-containing particles of the mixture of the at least one cover layer.

The production of material sheets takes place either in a cyclical or continuous manner. Since the compaction units, or the combined joining and compaction units, generally operate with significant pressures during material sheet production, these units are usually referred to by those skilled in the art as a press section with reference to an entire system. When producing material sheets as defined in this document, the working pressures here, depending on the material and size of the material sheet to be produced, are usually in the range between approximately 50 N/ ^cm² and approximately 500 N/ ^cm² , and advantageously between 100 N/ ^cm² and 400 N/ ^cm² . The mode of operation of the joining and/or compaction unit determines whether the overall process is described as a cyclical or continuous process. In cyclical production, the material sheets are pressed as flat objects with finite dimensions in all three spatial directions, whereas the material sheets produced in a continuous process represent cut-to-length sections of a continuously pressed web.

Wood-based panels occupy a special position among material boards, both economically and in terms of their technical suitability. Wood-based panels are manufactured in a wide variety of forms for different applications. Particularly widespread are particleboard, OSB, and MDF, as well as hybrid panels constructed from individual layers of such composites.

These boards are usually made from wood particles of different shapes and sizes, whereby the wood particles are bonded together by stimulating their own adhesion mechanisms and adding binding agents (usually glue).

Recently, efforts have been made to use annual plants, particularly grass-like plants, in addition to wood-based materials, which take many years to regrow, for the production of composite panels. Multilayer composite panels, whose individual layers are composed of annual plants, are also known from the state of the art.

However, the processing of annual plants is significantly more complicated than wood particle-based material boards. The high release of silicates during the manufacturing process, which have an abrasive effect on plant construction, poses a major obstacle.

• MDF-Platten aus gehackten und gewaschenen Hackschnitzeln, die zum Teil thermodynamisch in Refinern zerfasert werden und zu einem Vlies gestreut werden, das gepresst wird. MDF-Platten haben den Vorteil hoher Festigkeiten,
• glatter und gleichförmiger Oberflächen und einer guten Fräsbarkeit.

In the field of wood-based panels made from perennial wood, there are numerous state-of-the-art technologies regarding layer construction. Examples include:

• MDF boards made from chopped and washed wood chips, some of which are thermodynamically shredded in refiners and then spread into a fleece that is pressed. MDF boards have the advantage of high strength,
• smooth and uniform surfaces and good millability.

OSB boards with the typical OSB strand separation (coarse on the outside, fine in the core) are also well known. These offer high flexural strength and low product densities.

Pure particle boards (for example with a fine surface layer and a coarser middle layer) have the advantage of high material yield and offer the possibility of using lower-quality wood assortments on the inside, while on the outside they have smooth and uniform product surfaces.

Among hybrid boards, OSB with an MDF top layer plays a significant role in this invention. Its advantage over OSB alone is its smoother and more closed surface. This is also the case with OSB with a fine particle board top layer.

However, the spread mat with at least one outer OSB layer close to the covering layer, which is provided with fine covering layer particles, i.e. very small chips or short fibers, will have a color-uneven surface after the pressing process, which severely limits the further uses, for example coating or coloring in dry construction, especially in residential building construction.

In addition, with a chipboard top layer, the strength values, for example in terms of bending, would be reduced far too much.

Accordingly, one object of the invention is to provide a material board that has a largely homogeneous surface layer for easy decoration, yet can be manufactured with low production costs. Furthermore, the material board should have higher flexural strength than a known material board with an OSB core and a fine chipboard top layer.

The object of the invention is achieved with regard to a material plate of the type mentioned at the outset with the features of claim 1 and in particular in that for the mixture of the core, the chip sizes in chip size layers decrease towards the at least one cover layer from a layer of coarse chip material with the individual chip dimensions length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a layer of fine chip material with the individual chip dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm, wherein up to 20% of the fine chip material can still be contained in the spaces between the coarse chip layers.

The inventors recognized that a layer of fine fiber material on a surface of a layer of large OSB chips leads to uneven compaction of the fiber material in the press. Unlike with pure MDF boards, this causes undesirable shading in the surface due to uneven compaction across the entire surface of the top layer, as the gaps between the coarse OSB chips are too large. The pressure on the fiber material beneath which an OSB chip lies is different from the pressure on areas of the fiber material that lie above a gap between the OSB chips. The inventors then attempted, in accordance with their invention, to significantly reduce the chip sizes towards the top layer. This leads to a noticeably more homogeneous and smoother surface onto which the fine fiber material can be scattered. Conversely, the fiber material can of course also be scattered first, followed by a core whose chip size increases towards the top. In both cases, the fine fiber layer lies on a smoother outer surface of the core than the chips inside the core could create. During the subsequent hot pressing, this arrangement of the chips in the core layer results in significantly more uniform compaction than with a conventional OSB core, resulting in a significantly more homogeneous surface and virtually eliminating color shading.

The inventors have also recognized that the load-bearing capacity of a material board, particularly with regard to its flexural rigidity, depends to a particularly high degree on the design of the respective outer layers, in particular the respective cover layer(s). The known procedure of producing a cover layer from extremely fine chips is therefore not envisaged; instead, fiber material is used as the cover layer, which generates significantly higher flexural strength, particularly in the outer layer, than fine chip material. Due to the interweaving of the fibers, MDF layer types are suitable for developing high flexural rigidity and also have the advantage of being suitable as a carrier material for high-strength and permanently resilient screw connections. Such layers are particularly easy to process. For example, MDF (and HDF) layers form particularly clean cut edges when machined and, thanks to their smooth surface, are particularly suitable for coating with foils or painting. The scattered cover layers of fibers were broken down using thermomechanical processes according to known methods.

With a core comprising particles derived at least predominantly from perennial plants, an OSB layer type can be created by a layer of so-called strands or maxi-chips, often also called flat or coarse chips. Such strands have an average length of more than 50 mm, a width of more than 5 mm, and a thickness of more than 0.4 mm. These chip sizes are too large to create a smooth and visually homogeneous fiber surface layer because too many interstices are created.

Therefore, during scattering, it is ensured that the chip sizes near the surface layer are less than 50 mm long, less than 15 mm wide and less than 1 mm thick.

For a scattered mat or pressed board, which usually has two cover layers, one obtains a core layer, or also called core for short, which consists of at least three layers, with the middle layer consisting of coarse chips and at least the layers adjacent to the cover layers consisting of fine chips, each as a mixture with binding agents.

In many cases, the material board should be paintable on both sides and therefore it is advantageous if there is a covering layer of fiber material on both sides of the material board.

It is further advantageous if an intermediate layer is arranged between the core and at least one cover layer, said intermediate layer comprising a mixture of lignin-containing particles and a binder, wherein the particles belonging to the mixture of the intermediate layer consist of fine chip material. The core formed from chips and binder is thus essentially expanded and multi-layered. All layers can be multi-layered, i.e., with different chip sizes in the layers. It is ensured that the intermediate layer, in its mixture with a binder, consists of particles of fine chip material in the layer adjacent to the cover layer.

This allows pre-sorted chips to be scattered into a core. While the coarse chips are scattered in the center of the core, separate layers of fine chips are scattered toward the outer layers. This simplifies the design of the scattering heads, which do not have to separate the chip sizes during scattering.

But fundamentally, there are two ways for the core layer spreading device of the core to carry out the appropriate fractionation so that the boundary layer to the outer layers of the fiber mats is formed predominantly from fine chips. The fractionation of the chips can take place either by pre-sorting the chips into several scattering devices connected in series, or by a separating scattering technology. For example, direct scattering is used after a bunker, whereby the chips are guided directly onto a forming belt by means of guide plates, or indirect scattering is used via so-called scattering roller systems. With indirect scattering, the chips discharged from the bunker fall onto so-called scattering rollers, which divide the scattering material and, if necessary, sort and/or align it, also known as orient it. The variety of scattering devices used for this purpose has already been adequately described in the patent literature.

Accordingly, the chip size transition within the core can occur gradually or smoothly across multiple layers. As already described, the innermost core layer contains the largest chips, i.e., the coarse chip layer referred to here. Since the gaps between the chips are also the largest due to the chip size, it is understandable that up to 20% of these fine chips fall into the gaps during subsequent scattering. This increases the density but also the strength.

Furthermore, it is advantageous if the mixture of the core layer and the mixtures of the cover layers comprise binders from the same binder group, preferably the same binder.

In this way, the load-bearing capacity of the material board can be further increased. Even if the binder may not be ideally matched to the respective particles, it is preferable that the core mixture and the mixtures of the cover layers contain binders from the same binder group, preferably the same binder. In particular, this can prevent the material board from losing load-bearing capacity due to unwanted chemical processes.

It may also be preferred that the fiber material of the covering layers comes from annual plants.

A material panel designed in this way offers great advantages not only from an ecological and economic point of view, since the surface layer is made of rapidly renewable raw materials that are available worldwide quickly, inexpensively and without high transport costs, and such a material panel can also achieve high strength values, in particular high flexural rigidity values.

It is preferred that the first cover layer and, if applicable, the second cover layer form a volume fraction of between 7% and 30% of the volume of the material plate.

Preferably, the volume fraction should be between 12% and 30%. This ensures that the top layer is thick enough to provide the expected functional properties, even for thin material panels.

With regard to the use of a material panel for residential construction, the object of the invention is achieved by using a material panel according to one of the claims relating to the material panel.

The resulting advantages can be taken from the description of the advantages of the material plate according to the invention and its preferred design options.

With regard to a method of the type mentioned at the outset, the object of the invention is achieved in terms of the method by the features of claim 8 and in particular in that, in order to form a pressed material mat on and/or under the cover layer for the core layer, the chip sizes are scattered in chip size layers decreasing towards the at least one cover layer and optionally also towards the second cover layer by means of a core layer scattering device onto a forming belt, namely from a layer of coarse chip material with the individual chip dimensions of length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm within the core layer to a layer of fine chip material with the individual chip dimensions of length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm in a layer which borders on a cover layer, wherein up to 20% of the fine chip material can still be contained in the spaces between the coarse chip layers.

With such a process, a material board can be produced that offers great advantages, as it can achieve high flexural rigidity values thanks to the fiber cover layers and a visually uniform appearance even after pressing thanks to the fine chip layers near the edge of the cover layers.

The inventors recognized that the load-bearing capacity of a material board, particularly with regard to its flexural rigidity, depends to a particularly high degree on the design of the respective outer layers, especially the respective cover layer(s). Material boards whose two outer cover layers are formed from a binder-fiber mixture offer the best properties, especially when a homogeneous surface is paramount. Surprisingly, tests have shown that homogeneity in the appearance of the surface of the material boards can be achieved when the chip sizes of the scattered core layers decrease significantly towards the cover layers.

In any case, it is preferred that all layers are formed by free-flowing mixtures of lignin-containing particles and binders before the formation of the solid structure of the material plate.

In this case, it is possible to easily convert even older systems, because most systems for the production of material panels already have usable spreading heads.

There are two alternative approaches to reducing the chip size in the core during scattering toward the outer layer. This involves specifically influencing the chip size distribution from the mat core to the boundary layer of the fiber mats to be scattered, so that the boundary layer to the fiber mats is predominantly composed of fine chips. The fractionation of the chips can be achieved either by pre-sorting the chips on several scattering machines connected in series, or by a separation scattering technique. Both separation methods can also be used simultaneously.

For example, size separation devices can be provided in a spreading device, such as conventional sparing rollers, so that small chips are spread first and then larger ones for a later newspaper, or vice versa. Since the forming belt with the spread mat continuously runs toward the press, layers of unequal chip sizes are deposited on top of each other.

The other possibility is for at least one spreading device to spread exclusively coarse chips for the core layer, and for at least one additional spreading device to spread fine chips between the core layer and the cover layers before and after the spreading device. These intermediate layers are assigned to the core layer because they also consist of chips.

In order to achieve the highest possible volume fraction of the particles obtained from annual plants, which are preferred for ecological and economic reasons, it is particularly preferable for the fiber material of the cover layer to be obtained from annual plants. The cover layer thicknesses together can constitute at least 45% of the volume of the material board.

A possible preferred pressing profile within a manufacturing process in a continuous press, i.e. the mechanical bonding process under the influence of pressure and temperature to form a solid structure, can consist of the pressure acting on the core and the two cover layers in the inlet area of a continuously operating press being between 35 bar and 50 bar, before the pressure is adjusted to a constant value during the further course of the pressing process, which preferably decreases and can be adjusted to values around 20 bar before a calibration range of the press used. In a calibration range, the pressing pressure can then be increased again to a value above 20 bar, for example up to 25 bar. or 30 bar before the material plate leaves the pressing area of the material plate production plant.

Preferably, however, the cover layers are not exposed to temperatures exceeding 240°C, whereby the temperature load can advantageously be set to decrease down to the calibration range, so that the resulting material plate is only exposed to temperatures of approximately 170°C to approximately 190°C before leaving the pressing area.

This results in a material board, especially a wood-based board, characterized by a smooth and closed surface, making it easy to directly and easily improve, for example, by applying a coating (paper or thin veneers) or by varnishing or painting. A particularly advantageous feature is that the flexural rigidity of the material board is only slightly impaired, even in its inner transition areas, because the surface layers and the core layer form very homogeneous transitions.

In relation to a plant, the invention is pursued by the features that the forming station has a core layer spreading device for applying at least one free-flowing, core-forming pressed material mat layer made of a chip-binder mixture and at least one cover layer spreading device for applying at least one cover layer-forming pressed material mat layer made of a fiber-binder mixture, wherein the core layer spreading device is suitable for spreading the chip sizes for the mixture of the core in chip size layers towards the at least one cover layer and optionally also towards the second cover layer in a decreasing fractional manner onto a forming belt, namely from a layer of coarse chip material with the chip dimensions length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a layer of fine chip material with the chip dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm

Such a system is ideally suited to provide a material plate whose advantages have already been described

• 1a und 1b: eine schematisch dargestellte erfindungsgemäße Holzwerkstoffplatte in einem einfachen Vertikalschnitt,
• 2: eine schematisch vereinfacht dargestellte erfindungsgemäße Anlage zur Herstellung einer Werkstoffplatte

The invention is explained in more detail below with reference to a drawing which represents only one exemplary embodiment. In the drawings:

• 1a and 1b : a schematically illustrated wood-based panel according to the invention in a simple vertical section,
• 2 : a schematically simplified representation of a system according to the invention for producing a material plate

The figures serve to illustrate, by way of example, the method according to the invention for producing a material board, as well as the (wood) material board itself and a system suitable for its production. Such a material board 1 has a core or a core layer 2 and a (e.g., upper) first cover layer 3 and, if appropriate, a lower second cover layer 4. The mixtures 8 of the particles 6 belonging to the two cover layers 3, 4 consist of at least 70%, preferably at least 80%, very preferably at least 90% fibers, while the particles 5 belonging to the mixture 7 of the core 2 consist of at least 70%, preferably at least 80%, very preferably at least 90% chips. In addition to the lignin-containing particles (5, 6), the mixtures predominantly contain binding agents. In the illustrated embodiment of the material board in sections 1A and 1B, the core layer 2 itself is again formed in multiple layers. It has an upper layer 2a, a middle layer 2b and a lower layer 2c, each of which consists of chips, but with different orientations.

Due to these different orientations, two sectional drawings 1A and 1B shown, where 1A shows a section in the production direction, i.e. in a ZX plane and 1b a cut at right angles to it, i.e. in a ZY plane.

While the chips of the upper layer 2a and the lower layer 2c are oriented transversely to the production direction X or in the longitudinal direction P of the board, the chips of the middle layer 2b are essentially oriented along the production direction X or the longitudinal direction P of the board, i.e. in the X direction. By comparing the two 1A and 1B The essential element of the invention is that the chips of the middle layer 2b are significantly larger than the chips of the two layers 2a and 2c, which border on the cover layers 3, 4. In the 1A and 1B The chips in layers 2a and 2c have a length of 0.5 to 50 mm, a width of 0.5 to 15 mm, and a thickness of 0.2 to 1.0 mm. Layer 2b mainly comprises chips with a length of 50 to 200 mm, a width of 5 to 45 mm, and a thickness of 0.4 to 2.5 mm.

The orientation of the chips in the layers is not limited to this embodiment. Rather, the chips could also be oriented longitudinally in layers 2a and 2c, and transversely in layer 2b to the production direction. The invention even protects the scattering of the chips without orientation. if they have a length of more than 50 mm, preferably more than 100 mm, only at the height center of the mat in core layer 2', and a maximum length of less than 50 mm in the layers adjacent to the boundary layers. Any number of layers can be arranged in between.

Such a manufacturing process is based on 2 explained in more detail. First, the multi-layer or multi-ply pressed material mat 1' is produced on a forming belt 13, wherein this pressed material mat 1' contains a (middle) scattered core layer 2', an upper cover layer 3', and a lower cover layer 4'. This multi-layer pressed material mat 1' produced on the forming belt 13 is introduced into a press 14 and pressed into the material plate 1 in the press 14 using pressure and heat. In the illustrated embodiment, a continuously operating press 14 in the manner of a double-belt press is shown, which is marketed by the applicant under the name ContiRoll.

As in the prior art, the pressed material mat required as a basis for the inventive material plate is also produced in a conventional manner from scatterable, free-flowing particles in a forming station which contains a plurality of conventional scattering heads, so that the individual layers are scattered one after the other onto the forming belt 13.

What is new compared to the prior art, however, is that in the system according to the invention, at least one scattered cover layer 3', 4' is produced with fibers sprayed with a binder, and the scattered core layer 2' is scattered with a mixture of scatterable chips provided with a binder. It is essential that the chips in the interior of the core, for example, layer 2b, are significantly coarser than the layers adjacent to the cover layers, for example, 2a and/or 2c. In the inventive concept, this is done in the form that for the mixture of the core, the chip sizes in chip size layers decrease towards the at least one cover layer from a layer of coarse chip material with the dimensions length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a layer of fine chip material with the dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm, whereby up to 20% of the fine chip material can still be contained in the spaces between the coarse chip layers.

For this purpose, the system 10 according to the invention comprises a forming station 15, which has the core layer spreading devices 16a, 16b, 16c and the cover layer spreading devices 17a, 17b. While the spreading devices 16a, 16b, 16c for the spread core layer 2' can be designed as conventional spreading heads for oriented or non-oriented chips, the spreading devices 17a, 17b for the cover pressed material layers 3', 4' are configured for spreading a fiber-binder mixture 8.

In this way, the lower cover layer 4' made of a fiber-binder mixture is first applied to the forming belt 13. The core layer 2' is spread over the lower cover layer 4' in the conventional manner using the core layer spreading devices 16a to 16c designed as spreading heads. In the embodiment according to 2 A total of three spreading heads are indicated, namely for the production of a multi-layer, accordingly oriented core pressed material layer 2'. Thus, with the first spreading head 16a, oriented chips for a lower layer 2a of the core pressed material layer 2' can be scattered, and with the second spreading device 16b, the possibly differently oriented coarse chips for the central layer 2b of the core pressed material layer 2' can be scattered, and finally with the third spreading device 16c, the oriented chips for the upper layer 2c of the core pressed material layer 2' can be scattered. The last core layer spreading device 16c is followed by the cover layer spreading device 17 for the cover pressed material layer 3'. In simplified form, the exemplary embodiment shows a three-layer structure of the core layer 2'. The already pressed lower layer 2a with fine grit is previously spread onto the forming belt 13 by the core layer spreading device 16a, the middle layer 2b with coarse grit is spread onto the forming belt 13 by the core layer spreading device 16b and the upper layer 2c was spread onto the forming belt 13 by the core layer spreading device 16c before the pressing process.

The described embodiment shows the simplest form for forming the core layer 2' according to the invention. Three uniform layers 2a, 2b, 2c are formed. The coarse chips are on the inside, and the fine chips are on the outside, facing the cover layer 3', 4'. In practice, the method according to the invention can, of course, be extended to a separating scattering process, in which the chips are scattered in fractions, so that the chip size decreases continuously from the core interior to the cover layer. This is achieved using size separation means 18, for example, known scattering rollers.

The pressed material mat 1' produced in this way is then introduced into the press 14 and pressed into the material sheet 1. Of course, additional system components can be arranged between the forming station 15 and the press 14, e.g., devices for processing the mat, a pre-press and/or preheating device, detection devices for foreign body detection and/or misfill detection. Details are not shown.

Regardless of the 2 In the system shown, material panels according to the invention can also have a core 2 made of chips and a mixture 7 formed by a binder, and a cover layer 3, 4 made of a mixture 8, 9 of fibers and a binder, the fibers being obtained from annual plants.

List of reference symbols

1

Material plate

1'

Press mat

2

Pressed core layer

2'

Scattered core layer

2a

upper layer

2b

middle position

2c

lower layer

3

(first) pressed top layer

3'

(first) scattered top layer

4

(second) pressed top layer

4'

(second) scattered top layer

5

Particle core layer

6

Particle top layer

7

Mixture (nucleus-forming mixture)

8

Mixture (top layer forming mixture)

9

Mixture (interlayer-forming mixture)

10

Attachment

11, 11'

(first) intermediate layer

12, 12'

(second) intermediate layer

13

Forming tape

14

press

15

Forming station

16a, 16b, 16c

Core layer scattering device

17a, 17b

Top layer spreading device

18

Size separation agents, spreading rollers

P

Plate longitudinal direction

X

Spatial direction, longitudinal direction

Y

Spatial direction, transverse direction

Z

Spatial direction, height direction

Claims (15)

Material plate (1) comprising a pressed core layer (2) and at least one first cover layer (3) and optionally a second cover layer (4) on the opposite side of the first cover layer, each of which is formed from a mixture (7, 8) formed from lignin-containing particles (5, 6) and a binder, which is formed into a solid structure in a chemical and/or mechanical bonding process, wherein the lignin-containing particles (5) of the mixture of the core (7) are essentially formed from chip material and the lignin-containing particles (6) of the mixture of the at least one cover layer (3, 4) are formed from fiber material, characterized in that for the mixture of the core (7), the chip sizes in chip size layers decrease towards the at least one cover layer (3, 4) from a layer of coarse chip material (2b) with the individual chip dimensions of length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a Layer (2a, 2c) of fine chips with the individual chip dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm, whereby up to 20% of the fine chips can still be contained in the spaces between the coarse chip layers (2b). Material plate according to Claim 1 , characterized in that it has a covering layer on both sides made of a mixture (8) of fiber material and binder. Material plate (1) according to Claim 1 or 2 , characterized in that an intermediate layer (11, 12) comprising a mixture (9) formed from lignin-containing particles (5, 6) and a binder is arranged between the core (2) and at least one cover layer (3, 4), and the particles (5) belonging to the mixture (9) of the intermediate layer (11, 12) consist of fine chip material. Material plate (1) according to Claim 1 , 2 or 3 , characterized in that the mixture (7) of the core (2) and the mixtures (8) of the cover layers (3, 4) comprise binders from the same binder group, preferably the same binder. Material plate according to one of the Claims 1 until 4 , characterized in that the fiber material of the cover layers (3, 3', 4, 4') comes from annual plants. Material plate according to one of the Claims 1 until 5 , characterized in that the first cover layer (3) and optionally the second cover layer (4) form a volume proportion between 7% and 30% of the volume of the material plate. Use of a material plate (1) for interior construction of a dwelling, characterized in that a, according to one of the Claims 1 until 6 formed material plate (1) is used. Method for producing a material board (1) having at least one core layer (2) and at least one first cover layer (3) and optionally a second cover layer (4) on the opposite side of the first cover layer (3), each of which is formed from a mixture (7, 8, 9) formed from lignin-containing particles (5, 6) and a binder, wherein said mixture is formed into a solid structure in a chemical and/or mechanical bonding process under the influence of pressure and temperature, and wherein substantially chip material is used as the lignin-containing particles (5) of the mixture of the core (7) and fiber material is used as the lignin-containing particles (6) of the mixture (8) of the at least one cover layer (3, 4), characterized in that , to form a pressed material mat (1') on and/or under the cover layer (3', 4') for the core layer (2'), the chip sizes are arranged in chip size positions towards the at least one cover layer (3') and optionally also towards the second cover layer (4'). are scattered in fractions onto a forming belt (13) by means of a core layer scattering device (16a, 16b, 16c), namely from a layer of coarse chip material with the individual chip dimensions length 50 to 200 mm, width 5 to 45 mm and thickness 0.4 to 2.5 mm to a layer of fine chip material with the individual chip dimensions length 0.5 to 50 mm, width 0.5 to 15 mm and thickness 0.2 to 1.0 mm, whereby up to 20% of the fine chip material can still be contained in the spaces between the coarse chip layers. Method according to the preceding claim, characterized in that all layers and plies (2', 2a, 2b, 2c, 3', 4') are formed into a pressed material mat (1') by free-flowing mixtures of lignin-containing particles (5, 6) and binding agents before the formation of the solid structure of the material plate (1). Procedure according to Claim 8 or 9 , characterized in that with means for size separation (18) in a core layer scattering device (16a, 16b, 16c) first fine and at a later time coarser chip material (7, 9) is scattered or vice versa. Procedure according to Claim 8 or 9 or 10 , characterized in that at least one core layer scattering device (16a, 16b, 16c) scatters exclusively coarse chip material (7) and, before and after this, at least one further scattering device scatters intermediate layers (11', 12') between the core layer (2') and the cover layers (3', 4') with fine chip material (9). Procedure according to one of the Claims 8 until 11 , characterized in that the same binder is used both for the mixture (8) of fiber material and binder for the cover layer (3') and for the mixture (7, 9) of chips and binder for the core layer (2'). Procedure according to one of the Claims 8 until 12 , characterized in that the fiber material of the covering layer (3, 3', 4, 4') is obtained from annual plants. Procedure according to one of the Claims 8 until 13 , characterized in that the mechanical bonding process takes place under the influence of pressure and temperature to form a solid structure in a continuous press (14) with pressures between two rotating press belts between 20 and 35 bar and temperature loads between 170°C and 240°C, before the material plate leaves the pressing area of the material plate production plant (10). Procedure according to one of the Claims 8 until 14 , characterized in that the process for producing a according to one of the Claims 2 until 6 formed material plate (1).