EP3181314B1 - Method for producing an osb with a smooth surface and an osb - Google Patents

Description

The invention relates to a method for producing an OSB in which long, glued with an adhesive wood chips (strands) are oriented in at least three layers scattered, the orientation of the wood chips in adjacent layers offset by preferably 90 ° and then the scattered layers under high Pressure and temperature are pressed to a plate desired thickness, the adhesive hardens.

Such a plate is for example from the EP 1 136 636 A1 known. An OSB board is characterized in that it has, from layer to layer, intersecting strands, alternating longitudinally and transversely of the ground plan. The strands have a length of 70 to 200 mm, a width of 6 to 30 mm and a thickness of 0.3 to 1.2 mm. The material used is softwood or hardwood, the wood content in the finished board being between 90% and 98%. The orientation of the chips in the individual layers is realized by successive scattering units.

The well-known OSB (Oriented Strand Board) is used as formwork panel. In order to achieve a smooth surface, fibers or chips are sprinkled on the last beach layer, which should compensate for the unevenness of the surface of the core in order to achieve a flat surface as possible. This fine cover layer consists of a wood fines material, which was obtained after a Siebmaschenweite which is smaller than 0.5 mm. On the Feinspäneschicht a paper layer is placed and in a short-cycle press All layers are pressed together, wherein under pressure and heat, a flow of the core is achieved and thus an adhesion between the phenolic paper and the core takes place.

The EP 1 847 385 A1 discloses a building panel having a core of glued and compressed wood chips or wood fibers and two cover layers covering the core to the top and bottom. The core consists of a multilayer OSB board. For the production, wood-plastic composite material, which consists of a wood fiber-plastic mixture with a thermoplastic content of 80%, is spread on a forming belt with a first spreading head. Several layers of OSB strands are sprinkled onto this layer and then a further cover layer of a wood-plastic composite material is scattered. These scattered layers are finally pressed in a press under high pressure and temperature to a building board.

In the from the DE 10 2013 003 947 A1 Known method is a finished, the support layer forming support plate coated with a wood-plastic composite coating material, for example in the form of granules on at least one of its two surfaces, and then the coating material and the support plate are pressed together.

From the EP 2 801 675 A1 a wood fiber insulation board is known, which is coated with a lamination of a multi-component film. The air-impermeable film is placed on the wood fibers and the structure is then calibrated in a continuous furnace at a temperature of 100 ° C to 170 ° C.

In the US 4,364,984 A discloses an OSB having a five-layered structure wherein the lower and upper cover layers have substantially finer chips relative to the strands of the core.

The DE 10 2011 076 655 A1 discloses a plant for the production of wood-based panels, with which a Pressgutmatte is scattered, which is compressed in the course of transport to the press by means of a device on its narrow sides transverse to the production direction.

On this basis, the object of the invention is to provide an alternative method for producing an OSB with a smooth surface.

To solve the problem, the generic method is characterized by the fact that on the last scattered layer of long wood chips a pre-compressed mat of thermoplastic fibers and wood fibers is applied and melting the plastic fibers during pressing and the wood fibers (with the molten plastic) into the between the long wood chips ( Strands) formed spaces are pressed so that forms a smooth surface on the plate after pressing.

Preferably, the plastic fibers made of polypropylene (PP) or polyethylene (PE).

It is advantageous if the synthetic fibers have a core with a first softening temperature and a jacket surrounding the core with a second softening temperature. Then, a mixture of wood fibers and thermoplastic synthetic fibers are first processed into a mat and pretreated in a Thermobondingofen. Then, when the second softening temperature is lower than the first softening temperature, the clad of the plastic fibers (bi-component fibers) melts and creates tie points in the matrix of plastic and between plastic and wood fibers. Such pretreated mats are conventionally used as wood fiber insulating materials.
This pretreated mat can then be densified and then preferably has a thickness of 5 mm at a basis weight of 650 to 700 g / m ² , preferably 675 g / m ² .

The proportion of plastic in the mat is 5 to 15% by weight, preferably 5 to 10% by weight, in particular 5% by weight or 10% by weight.
A WPC mat can also be used. In WPC (wood-plastic compound) the plastic content is increased compared to the wood fiber content. For this purpose, the proportion of plastic in the mat is 30 to 70% by weight and preferably 56% by weight.

The pretreated mat then preferably has a thickness of 15 mm and a basis weight of 1,400 to 1,600 g / m ² , preferably 1,500 g / m ² .

On the mat of precompressed synthetic fibers and wood fibers, a paper layer can be placed, which is preferably impregnated with synthetic resin, wherein the synthetic resin in particular preferably has a phenol content of 50% by weight.

The paper layer preferably has a basis weight of 550 g / m ² .

It is advantageous if the pressed plate is actively cooled.

An OSB produced by the process is characterized by at least three layers of oriented spread long wood chips in which the orientation of the wood chips in adjacent layers is different, and at least one of wood fibers and a thermoplastic plastic covering layer forming a smooth top, wherein the layers of long wood chips have hardened adhesive. The plastic content in the cover layer is 5 to 15% by weight. It is particularly advantageous if the plastic fraction in the top layer is preferably 5 to 10% by weight, preferably 5 or 10% by weight. The adhesive used is preferably polymeric methylene diisocyanate (PMDI), which crosslinks by a polyaddition reaction.

To further smooth the top, the top layer can be covered by a layer of paper.

Figur 1 -

die schematische Darstellung einer OSB-Plattenherstellungsanlage;

Figur 2 -

die vergrößerte Darstellung gemäß Sichtpfeil II aus Figur 1;

Figur 3 -

die schematische Darstellung einer alternativen OSB-Plattenherstellungsanlage;

Figur 4 -

die vergrößerte Darstellung gemäß Sichtpfeil IV aus Figur 3;

Figur 5 -

die schematische Darstellung einer weiteren OSB-Plattenherstellungsanlage;

Figur 6 -

die vergrößerte Darstellung gemäß Sichtpfeil VI aus Figur 5.

With the help of a drawing, the invention will be described in more detail below. Show it:

FIG. 1 -

the schematic representation of an OSB board manufacturing plant;

FIG. 2 -

the enlarged view according to viewing arrow II FIG. 1 ;

FIG. 3 -

the schematic representation of an alternative OSB board manufacturing plant;

FIG. 4 -

the enlarged view according to viewing arrow IV FIG. 3 ;

FIG. 5 -

the schematic representation of another OSB plate manufacturing plant;

FIG. 6 -

the enlarged view according to viewing arrow VI FIG. 5 ,

First, long wood chips (strands) having a length of 70 to 200 mm, a width of 6 to 30 mm and a thickness of 0.3 to 1.2 mm are scattered to a lower cover layer 1. On this lower cover layer 1, a middle layer 2 of long chips is scattered, wherein the chips are offset in the middle layer 2 with respect to the lower cover layer 1 by substantially 90 °. That is, when the chips are oriented in the lower cover layer 1 in the longitudinal direction (transporting direction T), the strands in the middle layer 2 are oriented transversely thereto, that is, they run in the transverse direction. On the middle layer 2, an upper cover layer 3 of long wood chips is scattered, which have the same orientation as the strands in the lower cover layer 1. The wood chips are glued with an adhesive.

As adhesives come phenol-formaldehyde binder (PF), urea-formaldehyde binder (MF), melamine-urea-formaldehyde binder (MUF) or melamine-urea-phenol-formaldehyde binder (MUPF). PDMI is also suitable as an adhesive. Within an OSB, two different binders can also be used as an adhesive. In the middle layer, the chips can be glued, for example, with PDMI and in the outer layers with MUF or MUPF binder. Preferably, PMDI is used as the adhesive.

On the upper cover layer 3, a pre-compressed mat 4 is placed from a mixture of wood fibers and thermoplastic synthetic fibers. The mat 4 is preferably wound on a roll which is arranged on a device 5 for unwinding the mat 4. The cake consisting of the layers 1, 2, 3, 4 is transported in a hot press 20, which is designed as a Conti press. At a pressing temperature between 190 ° C - 240 ° C, the layer structure is pressed to an OSB 10 desired thickness.

Due to the different thicknesses and lengths or widths of the strands, cavities are formed in the individual layers 1, 2, 3 which leave depressions on the upper side of the upper cover layer into which the fibers and the molten plastic of the mat 4 are pressed, so that the in FIG. 2 shown smooth surface 7 sets.

The plastic fibers are so-called bi-component fibers. They consist of a core and a shell surrounding the core, whose softening temperature is lower than that of the core. A mixture of wood fibers and plastic fibers is formed into a mat which is precompressed and treated in a thermobonding furnace. The mantle of the bi-component fibers melts and forms points of attachment in the matrix of plastic and also between plastic and wood fibers. The preparation of such mats is known. These are usually used as wood fiber insulation materials. Subsequently, the treated in the thermobonding mat 4 is post-compacted until a thickness of about 5 mm at a basis weight of 650 to 700 g / m ² , preferably sets 675 g / m ² . The percentage of plastic in the mat 4 is 5 to 15% by weight. The plastic fraction is preferably 5 to 10% by weight, in particular 5 or 10% by weight.

At the in FIGS. 3 and 4 illustrated embodiments is placed on the mat 4 made of plastic and wood fibers still a paper web 6, which is also handled by a roll used in an unwinding 8. The paper web 6 is preferably impregnated (impregnated) with a phenolic resin, the phenol content in the synthetic resin being about 50% by weight. The paper web 6 has a basis weight of 550 g / m ² . The structure consisting of the layers 1, 2, 3, 4, 6 is also pressed in a Conti press to an OSB 10 of desired thickness, wherein the smoothness of the top 7 is determined by the fineness of the paper. The paper can be smooth or textured. With a structured surface, for example, when the OSB 10 is to be used as shuttering panel, the visible surfaces of the cast concrete can be optically selectively influenced.

At the in FIGS. 5 and 6 In the embodiment shown, the mat 4 made of wood fibers is a so-called WPC mat, that is to say a wood-plastic composite (WPL = Wood Plastic Compound), in which preferably the plastic proportion outweighs the proportion of wood fiber. The layers 1, 2, 3 are constructed identically to the previously described embodiments. The mat 4 has a plastic content of 30 to 70% by weight, ie 70 to 30% by weight of wood fibers. Preferably, the plastic content is 56% by weight and the wood fiber content is consequently 44% by weight. This mat 4 has a weight per unit area of 1,400 to 1,600 g / m ² and in particular 1,500 g / m ² . Its pre-compressed thickness is about 15 mm. The structure of the layers 1, 2, 3, 4 is conveyed through in the transport direction T by a Conti-press 20 and actively cooled down by a cooling device 30 at the end of the Conti-press 20 to a rapid solidification of the plate 10 and a delay of the upper Layer 4 to prevent. By recooling, the wood-plastic composite is cooled down so far that the wood-plastic composite dissolves from the steel strip of the Conti press. The bonding of the wood-plastic composite to the OSB becomes active.

If the plastic content is 10 to 15% by weight, the OSB board can be used as a tongue and groove plate for industrial floors. If the plastic content is 30 to 70% by weight, it can be used as a roof panel with a water-repellent functional layer and / or an optional slip-resistant effect. The smooth upper side 7 opens up further fields of application for the OSB 10. For example, panels can be used in furniture construction, because further coatings can also be applied to the surface. The further coatings can be lacquer or else melamine resin papers as well as HPL / CPL. Also, such panels can be used in the interior of a roof truss, and the plate can be used as the insulation between the rafters holding panel. Due to the smooth surface of the panels can be painted immediately, so that a previously required plasterboard can be omitted.

During active cooling of the panel, it is possible to emboss a structure in the surface to create slip resistance when the panel is to be used as a roof panel.

LIST OF REFERENCE NUMBERS

1

lower cover layer

2

middle class

3

upper cover layer

4

Layer / mat

5

Facility

6

Layer / paper web

7

top

8th

unwinding

10

Board / OSB

20

Conti-Press

30

cooling device

T

transport direction

Claims (15)

1. Method for producing an OSB panel in which long wood chips coated with an adhesive are spread in an oriented manner in at least three layers (1, 2, 3), wherein the wood chips in adjacent layers (1, 2, 3) are aligned in an offset manner and subsequently the spread layers (1, 2, 3) are compressed under high pressure and temperature to form a panel (10) of desired thickness, the adhesive hardening in the process, wherein a pre-compacted mat (4) composed of thermoplastic fibres and wood fibres is applied to the layer (3) of long wood chips that was spread last and on compression the plastics fibres melt and the wood fibres are pressed into the interstices formed between the long wood chips, with the result that a smooth surface (7) forms on the panel (10) after the pressing.
2. Method according to Claim 1, characterized in that the plastics fibres are composed of polypropylene or polyethylene.
3. Method according to Claim 2, characterized in that the plastics fibres have a core having a first softening temperature and a jacket surrounding the core and having a second softening temperature.
4. Method according to Claim 3, characterized in that the second softening temperature is lower than the first softening temperature.
5. Method according to any of the preceding claims, characterized in that the mat (4) composed of wood fibres and plastics fibres has a thickness of 5 mm.
6. Method according to Claim 5, characterized in that the mat (4) has a mass per unit area of 650 to 700 g/m², preferably 675 g/m².
7. Method according to Claim 5 or 6, characterized in that the proportion of plastic in the mat is 5% to 15% by weight, preferably 5% to 10% by weight, particularly preferably 5% or 10% by weight.
8. Method according to Claim 5 or 6, characterized in that the fraction of plastic in the mat (4) is 30% to 70% by weight, preferably 56% by weight.
9. Method according to Claim 8, characterized in that the mat (4) composed of wood fibres and plastics fibres has a thickness of 15 mm.
10. Method according to Claim 8 or 9, characterized in that the pre-compacted mat (4) has a mass per unit area of 1400 to 1600 g/m², preferably 1500 g/m².
11. Method according to any of the preceding claims, characterized in that a paper layer (6) is applied to the pre-compacted mat (4).
12. Method according to Claim 11, characterized in that the paper layer (6) has been soaked with synthetic resin, wherein the synthetic resin preferably has a phenol content of 50% by weight.
13. Method according to Claim 12, characterized in that the paper layer has a mass per unit area of 550 g/m².
14. Method according to any of the preceding claims, characterized in that the pressed panel (10) is actively cooled.
15. Method according to any of the preceding claims, characterized in that the wood fibres are pressed with the molten plastic into the interstices.

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