CN106808555B

CN106808555B - Method and device for producing a multilayered material sheet and material sheet

Info

Publication number: CN106808555B
Application number: CN201611050261.XA
Authority: CN
Inventors: G·冯哈斯
Original assignee: Dieffenbacher GmbH Maschinen und Anlagenbau
Current assignee: Dieffenbacher GmbH Maschinen und Anlagenbau
Priority date: 2015-11-27
Filing date: 2016-11-24
Publication date: 2023-03-03
Anticipated expiration: 2036-11-24
Also published as: DE102015120653B4; DE102015120653A1; CN106808555A

Abstract

The invention relates to a method for producing a multilayered material sheet, wherein at least one two-layered dispersion mat is produced on a revolving forming belt and is pressed in a press to form a material sheet, wherein the dispersion provided with a binding agent is spread by means of a spreading device in layers, and at least one further covering layer of straw, which is thinner than the layers, is spread. The method comprises the following steps: for the cover layer, drying the straws as straw pieces in a dryer; crushing the dried straw slices into straw particles in a crushing device; directing the straw particles through an air separator to separate out foreign matter; mixing the straw particles with a binder in a gluing device and finally; the straw particles are sieved in a wind spreading box and spread in a graded layer structure into a cover layer of a spread mat. The invention also relates to a device for producing a material sheet and to the material sheet itself.

Description

Method and device for producing a multilayered material sheet and material sheet

Technical Field

The invention relates to a method for producing a multilayered material sheet and to a device for producing a multilayered material sheet.

The invention also relates to a multilayered material sheet.

Background

The production of slabs from straw or slabs with straw components is already known. DE 102007029697A1 shows one possible application of straw to lightweight structural panels. EP1159113B1 shows in detail the preparation of straw and the use of different proportions in a five-layer multilayered material sheet. The current applications have been successfully implemented.

Straw is understood in the context of the present invention to be the threshed and dried stems and leaves of cereals, oil plants, fiber plants or legume fruits. Typically, straw is added to the agricultural arable area of land after harvesting as a source of humus and nutrients. At the same time, direct or indirect heat utilization in thermal power plants or biomass plants is also common. Furthermore, as has been seen in the aforementioned prior art, the industry producing boards of material has shown an interest in using straw as a substitute for wood when producing boards of material, but there are technical limitations.

The problem is that lightweight panels with a high proportion of straw in the intermediate layer cannot be coated orderly with a suitable film system (melamine paper), since, for coating and coating of lightweight panels with melamine paper (these film systems) in a short-cycle press, in addition to the required heat input, a relatively high specific pressure is required in order to transmit the heat orderly and, if possible, the feel, on the one hand, and for a sufficiently firm connection between the film system and the surface of the material panel, on the other hand. For lightweight boards made of straw, there is no back pressure required and sufficient in the cladding press, which can lead to the adhesive bond built up inside the material board being destroyed. Thereby resulting in a defective material sheet and/or a defective coating.

A disadvantage is also that it is laborious to separate the mineral foreign bodies (small stones, sand, dust) in a preliminary process. However, unlike wood feeding, these foreign materials are increasingly carried or supplied together in straw. These foreign bodies can cause difficulties in the subsequent processing and in the hardening and tempering step, in particular for the outer covering layers of the material sheet. The mineral material located on the outside causes increased wear of the raw material plate in the grinding path. This is accompanied by porous surfaces which are produced by abrasive mineral particles and which are problematic for direct painting or digital direct printing on the board surface. Due to the coarse pore surface, the proportion of covering material (primer, liquid coating) required rises significantly. Typical coatings with the aid of film systems or with melamine paper also lead to unsatisfactory results in the case of conditioned material sheets whose surface is influenced by pockets which are visible as a result of the pressure during the coating process or by the mineral constituents penetrating the roll under the surface ("telegraphing").

Disclosure of Invention

The object of the invention is to provide a method and a device for producing a multilayered material sheet and a material sheet with a straw component, which material sheet has advantages with respect to the current state of the art with regard to the process and the required equipment. Furthermore, a material sheet should be provided which, despite the presence of the straw component, has a coatable and aesthetically pleasing surface.

The invention is based on a method for producing a multilayered material sheet, in which at least one two-layered dispersion mat is produced on a revolving forming belt and is pressed in a press to form a material sheet, wherein the dispersion provided with a binder is dispersed into one layer by means of a dispersing device, and substantially fibers, chips and/or splinters are used, and at least one further coating layer of straw is dispersed, which is thinner than the other layers.

The task proposed for this method is solved by:

a) Aiming at the covering layer, the rice straw is used as rice straw pieces to be dried in a dryer,

b) Crushing the dried straw pieces into straw particles in a crushing device,

c) The straw particles are guided through an air separator to separate foreign matter,

d) Mixing the straw particles with a binder in a gluing device and finally

e) The straw particles are sieved in a wind distribution box and distributed in a graded layer structure as a cover layer of a spread mat.

The invention recognizes that a fine and coatable surface of straw can be provided on the one hand by means of a correspondingly designed wind sifting device. In particular, it is now possible to dispense with the costly grinding of wood-based raw materials, but instead to provide a low-cost surface with straw, which is even suitable for digital direct printing preferably on the primer to be applied. Furthermore, with this method, virtually inseparable foreign bodies, for example dust or sand, with a diameter of less than 1 mm in the scattering mat or in the material plate can be suppressed, so that these foreign bodies no longer cause problems on the surface of the material plate or in the coating. And simultaneously can avoid: the surface grinding required after the production of the material sheet will be more expensive due to the presence of foreign bodies.

In an advantageous manner, the straw is now dried before being comminuted in order to avoid clogging of the screen in the comminution apparatus.

Preferably, in one design, the cover layer of the scattering mat is produced during the wind scattering in the wind scattering box, wherein at the surface of the scattering mat there are thinner straw parts, on both sides of the (middle) layer there are thicker straw parts, and possibly minerals or other foreign bodies in the area of the thicker straw parts, preferably abutting the (middle) layer.

Alternatively or in combination, the coarse fraction can be separated from the straw particles in a screening device for another comminution in a comminution device.

Alternatively or in combination, the fines fraction can be separated from the straw particles in a screening device for heat utilization.

Preferably, a hammer mill or a vertical mill is used as the comminution device and/or a flat or roller screen is used as the screening device.

Alternatively or in combination, pellets, fruits and especially mineral foreign bodies, preferably having a size of more than 1 mm, can be separated as foreign bodies in the air separator.

Alternatively or in combination, the straw, preferably the coarse fraction leaving the screening device, may be mixed into the bulk material for the (intermediate) layer.

With respect to the apparatus, the invention proceeds from a known apparatus for producing a multilayered material sheet, the known apparatus comprising:

-an endless revolving forming belt for carrying a mat of scattering material,

-a spreading device for producing a layer of a mat of spread material on a forming belt from the spread material provided with binder, and

-a press for pressing the spread mat into a material board.

The task of providing a new plant according to the invention is solved by the plant furthermore comprising plant parts arranged in a sequential order for the treatment of straw:

-a dryer for drying the pieces of straw,

-comminuting means for comminuting the dried straw pieces into straw particles,

an air separator for separating foreign matter from straw particles,

-a gluing device for mixing straw particles with a binder, and

-a wind spreading box for sortingly spreading the straw particles into a thinner cover layer of the spread mat relative to the (other) layers, the cover layer having a graded layer structure.

In a preferred embodiment of the plant, a sifting device is arranged downstream of the comminution device for separating a coarse fraction from the straw particles for returning to the comminution device and/or for separating a fine fraction from the straw particles for heat utilization in the energy plant.

Alternatively or in combination, a flat screen or a roller screen can be arranged as a screening device and/or a hammer mill or a vertical mill can be arranged as a comminution device in the plant.

It is particularly preferred that the air separator is adapted to separate pellets, fruits and especially mineral foreign bodies as foreign bodies, preferably foreign bodies having a size of more than 1 mm.

The invention is based on the following in respect of known material sheets with a multilayer structure: the material sheet has at least one layer consisting essentially of fibers, chips and/or shreds and a further covering layer consisting of straw particles mixed with a binder, which is thinner than the layer.

The solution for the material sheet according to the invention is characterized in that the cover layer has a sorted structure, wherein thin straw parts are arranged close to the surface and thicker straw parts are arranged close to the (thicker) layer. The thicker straw fraction is thereby arranged approximately between the remaining cover layer and the (intermediate) layer.

It is particularly preferred that the mineral or other foreign matter is arranged in a thicker straw portion or adjacent to a (thicker) layer.

It is particularly preferred that the (thicker) layer is arranged as an intermediate layer between the two cover layers.

In a further embodiment of the material plate, melamine or a film system containing melamine can be arranged on the surface.

Alternatively or in combination, it can be provided that the (intermediate) layer can be mixed proportionally with straw, straw flakes and/or straw particles. The (intermediate) layer is preferably produced from wood-based particles, chips or chips and is spread. Advantageously, straw may also be used here as an alternative, wherein it should be noted that the resistance of the (intermediate) layer must be sufficient to enable the coating process without damaging the material sheet.

Preferably, the straw particles used for the cover layer incorporate MDI as a binder.

A particularly preferred process for producing the material sheet according to the invention is characterized by the following sequence of process steps:

the rice straw pieces are dried in a dryer,

pulverizing the straw pieces into straw particles in a grinding mill,

straw particles are sieved, wherein too coarse straw particles are either crushed again or fed to the intermediate layer, while too fine sieved straw particles are burnt off.

The straw particles are air separated to separate out pellets (rice grains, wheat grains, minerals, preferably over 1 mm in diameter),

the remaining straw particles are glued,

the straw particles are subjected to wind dispersion for at least one cover layer,

pressing a spread mat consisting of at least two layers into a material board,

polishing the surface of the material sheet, and

the surface is coated with a film system and/or melamine.

It should also be noted that the first layer generally refers to a layer known from the prior art. The layer may be produced from wood or wood-like material (with or without plastic additives) and is usually provided with a binder. The layer may also proportionally contain straw. Usually, the layer, which is mostly arranged between two cover layers, is produced from fibers, chips or shreds.

In this respect, it is not meant that the first layer must also be the first layer on the forming belt, but that the "first" layer is a thicker layer and the "second" layer is a thinner layer. The number of layers can also vary in general, wherein it is emphasized that the invention is to be understood as meaning a thin covering layer as the layer lying on the outside, wherein the covering layer forms an outwardly facing surface on at least one side of the material sheet being pressed, which surface can be conditioned with a film or the like.

The apparatus is suitable for carrying out the method, but can also be operated independently.

Drawings

In the sole figure, the method process for producing a multilayered material sheet is schematically illustrated according to one embodiment and according to a schematic apparatus structure.

Detailed Description

Straw is previously pulverized or has been supplied as straw pieces 1, and is dried in a dryer 2. In contrast to wood, straw is comminuted in a comminution apparatus 3 and subsequently separated as straw particles in a screening apparatus 5 into at least two fractions. The coarse fraction 6 can be fed again to the comminution device 3 or, for example, as an alternative to the spread 20 for the layer 22. Preferably, the fine fraction 7 is also separated off in the screening device 5 and is burned off or used in other ways, for example in an energy plant 19.

The remaining amount of straw particles 8 is then fed to an air separator 9, where minerals and other foreign bodies 10 are separated out, and the cleaned straw particles 8 are delivered to a cyclone separator (not shown) to separate out separator air or to a gluing device 11. It is technically necessary to separate foreign bodies 10 with a diameter of less than 1 mm from a quantity of straw particles 8, wherein the technical and economic expenditure rises disproportionately with respect to the cleaning power.

Next, the production of the three-layer spread mat 23 to be pressed into the three-layer material sheet 23 is explained. For this purpose, the straw particles 8 are separated behind the gluing device 11 and fed to two diametrically opposite wind distribution boxes 12, which each produce a cover layer 21. Between the two wind distribution boxes 12, one (or if possible a plurality of) distribution devices 13 is arranged, which distribution devices 13 use the prepared distribution cloth 20 for the layer 22 and in this case arrange them as an intermediate layer, wherein the layer 22 is made on the lower covering layer 21 or on the forming belt 14. The forming belt 14, which circulates endlessly, has in this embodiment an advancing direction 26 and thus passes under the scattered equipment parts and receives the first cover layer 21 from the first (right) wind scattering box 12, subsequently the layer 22 as an intermediate layer from the scattering device 13 and then the second cover layer 21 from the second (left) wind scattering box 12. The three layers are applied to a forming belt 14, which essentially produces a spread mat 23 and which, after variable pre-treatments (wetting, spraying, heating, pre-compacting), not shown further, can be delivered to a continuously operating press 15, which presses the spread mat 23 into an endless material web 27. After the continuously operating press 15, the material web 27 is separated into material sheets 18 by means of a separating device 16 (usually a diagonal saw). These material plates 18 can be tempered in the coating press 17 after the cooling time or directly afterwards and a surface coating preferably containing melamine is obtained.

Instead of the continuously operating press 15, a rotary press may be arranged, which presses the scattering mat in sections or presses the scattering mat 23 divided into mat sections.

The spreading mat 23 and the material plate 18 have a schematic cross-sectional circle in the plane of the forming belt 14, which is shown enlarged above in a circular cross-section 28. The enlargement in the cross section 28 is intended to show the layer structure of the spreading mat 23 and thus also to show the layer structure of the material sheet 18; the forming belt 14 is not drawn. The sorted layer structure of the upper (first) cover layer 21, in which the straw portions 24 are arranged close to the surface 4, can be seen from the upper surface 4. The straw particles of the coarse straw portion 25 are arranged in layers of flow in the direction of the middle of the plate, preferably characterized by wind sifting. The stratification of the flow is shown in the drawing only in three different grain sizes of the straw particles 8.

The flow-approaching transition, which is characteristic for the wind distribution box, and the corresponding arrangement in the upper cladding 21 are essentially achieved in this way: the left-hand (second) wind distribution box 12 acts in its wind direction in the direction of advance 26 and the fine straw particles thus end up on the forming belt 14 in their direction. In an advantageous manner, the mineral or remaining foreign bodies 10 first fall onto the (intermediate) layer 22 directly after delivery into the wind distribution box 12 and are approximately covered with respect to the surface 24 by the subsequently distributed straw particles 8. The necessary (intermediate) layer 22 is spread mechanically in a preferred and usual manner, but may also have a sorted layer depending on the application given by the user.

By arranging the two wind spreading boxes 12 opposite to each other, the wind direction in the right (first) wind spreading box is opposite to the advancing direction 26 of the forming belt 14, the cover layer 21 on the forming belt 14 starts with a thin straw portion 24 (lower surface 4) and a thicker straw portion 25 is finally located above it. Since the minerals or other foreign bodies 10 are now scattered as "last" in the direction of advance 26, they are located above the coarse straw particles 8 of the coarse straw portion 25 or at least adjacent to the (intermediate) layer 22.

List of reference numerals:

1. rice straw sheet

2. Drying machine

3. Crushing device

4. Surface of

5. Screening device

6. Coarse fraction

7. Details of

8. Straw particles

9. Air separator

10. Foreign matter

11. Gluing device

12. Wind cloth box

13. Dispensing device

14. Molding belt

15. Press machine

16. Separating device

17. Cladding press

18. Material sheet

19. Energy plant

20. Dispersion for 22

21. Covering layer

22. Layer(s)

23. Spreading material pad

24. Straw part (thin)

25. Straw part (Thick)

26 14 forward direction of travel

27. Strip of material

28. Cross section.

Claims

1. A method for producing a multilayered material sheet, at least one two-layered dispersion mat (23) being produced on an endlessly revolving forming belt (14) and being pressed in a press (15) to form a material sheet (18), wherein a dispersion cloth (20) provided with a binder is dispersed by means of a dispersing device in layers (22) and fibers, chips and/or splinters of wood or wood-like material are applied to the layers (22), wherein

Spreading at least one further cover layer (21) consisting of straw, which is thinner than the layer (22), wherein the material for the cover layer (21) is prepared separately from the spreading cloth (20),

characterized in that the following steps are carried out in successive processes or in successive order of the plant components:

a. drying the covering layer (21) in a dryer (2) with straw as straw pieces (1),

b. crushing the dried straw slices (1) into straw particles (8) in a crushing device (3),

c. guiding the straw particles (8) through an air separator (9) to separate out foreign matter (10),

d. mixing the straw particles (8) with a binder in a gluing device (11) and finally,

e. the straw particles (8) are screened in a wind distribution box (12) and distributed in a graded layer structure as a cover layer (21) of a distribution mat (23) so that the coarser straw fraction (25) is arranged close to the layer (22).

2. A method according to claim 1, characterised in that during the spreading of the wind, a covering layer (21) of the spread mat (23) is created in the wind spreading box (12), wherein at the surface (4) of the spread mat (23) there are thinner straw parts (24), on both sides of the layer (22) there are thicker straw parts (25), and mineral or other foreign bodies (10) are located in the area of the thicker straw parts (25).

3. A method as claimed in claim 1 or 2, characterized in that the coarse fraction (6) is separated from the straw particles (8) in a screening device (5) for another comminution in the comminution device (3).

4. A method as claimed in claim 1 or 2, characterized in that the fine portions (7) are separated from the straw particles (8) in a screening device (5) for heat utilization.

5. The method as claimed in claim 1 or 2, characterized in that a hammer mill or a vertical mill is used as the comminution device (3) and/or a flat or roller screen is used as the screening device (5).

6. Method according to claim 1 or 2, characterized in that pellets of a size greater than 1 mm are separated as foreign bodies (10) in the air separator (9).

7. A method as claimed in claim 1 or 2, characterized in that straw is mixed into the scattering material (20).

8. A method according to claim 2, characterized in that the mineral or other foreign matter (10) abuts the layer (22) in the region of the coarser straw portion (25).

9. Method according to claim 1 or 2, characterized in that mineral foreign matter having a size of more than 1 mm is separated as foreign matter (10) in the air separator (9).

10. Method according to claim 1 or 2, characterized in that fruits having a size of more than 1 mm are separated as foreign matter (10) in the air separator (9).

11. A method according to claim 3, characterised in that the coarse fraction (6) leaving the screening device is mixed into the loose material (20).

12. An apparatus for producing a sheet of multilayered material, comprising:

-an endless revolving forming belt (14) for carrying a mat (23) of spread material,

-a spreading device (13) for producing a layer (22) of a spread mat (23) on the forming belt (14) from a spread (20) provided with a binder, the spread (20) using fibres, chips and/or chips of wood or wood-like material,

-a press (15) for pressing a mat (23) of spread material into a material sheet (18),

and furthermore comprises equipment parts arranged in a sequential order for processing the straw separately from the bulk material (20):

-a dryer (2) for drying the straw pieces (1),

-comminuting means (3) for comminuting the dried straw pieces (1) into straw particles (8),

-an air separator (9) for separating foreign matter (10) from the straw particles (8),

-a gluing device (11) for mixing the straw particles (8) with a binder, and

-a wind spreading box (12) for sortingly spreading straw particles (8) into a thinner cover layer (21) of a spread mat (23) relative to the layer (22), the cover layer having a graded layer structure such that thicker straw portions (25) are arranged close to the layer (22).

13. An apparatus as claimed in claim 12, characterized in that a screening device (5) is arranged after the comminution device (3) for separating a coarse fraction (6) from the straw particles (8) for return to the comminution device and/or for separating a fine fraction (7) from the straw particles (8) for heat utilization in an energy device (19).

14. The apparatus of claim 12 or 13,

a flat screen or a roller screen and/or a screen is arranged as the screening device (5)

A hammer mill or a vertical mill is arranged as the comminution device (3).

15. The apparatus according to claim 12 or 13, characterized in that the air separator (9) is adapted to separate out the pellets as foreign matter (10).

16. The apparatus according to claim 12 or 13, characterized in that the air separator (9) is adapted to separate the fruit as foreign matter (10).

17. The apparatus according to claim 12 or 13, characterized in that the air separator (9) is adapted to separate out mineral foreign matter as foreign matter (10).

18. The apparatus according to claim 12 or 13, characterized in that the air separator (9) is adapted to separate out foreign bodies (10) having a size greater than 1 mm.

19. A material sheet, characterized in that the material sheet has a multilayer structure and at least one layer (22) of fibres, chips and/or fragments of wood or wood-like material and a further cover layer (21) of straw particles (8) mixed with a binder, which is thinner than the layer (22), the cover layer (21) having a sorted structure, wherein the thinner straw parts (24) are arranged close to the surface (4) and the thicker straw parts (25) are arranged close to the layer (22), and mineral or other foreign matter (10) is arranged in the thicker straw parts (25) or adjacent to the layer (22).

20. A material sheet according to claim 19, characterised in that the layer (22) is arranged as an intermediate layer between two cover layers (21).

21. A material sheet according to claim 19 or 20, characterized in that melamine or a film system containing melamine is arranged on the surface (4).

22. A material sheet according to claim 19 or 20, characterised in that the layer (22) is proportionally mixed with straw, straw flakes (1) and/or straw particles (8).