PLANAR MATERIAL AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The invention relates to a planar material, comprising lignocellulose fibers and binding agents. In order to provide a planar material that using fibers has reduced swelling, it is provided that the proportion of the binding agent has more than 50 wt % of the planar material. The invention also comprises a method for producing the planar material.

Claims

1. A method for producing a planar material, comprising lignocellulose fibers (5) and binding agents, wherein the proportion of the binding agent with an optionally used plasticizing additive is more than 50 wt % of the planar material (1), wherein the plasticizing additive is not used as the main component of the binding agent, comprising the steps of: providing lignocellulose fibers (5), providing the binding agent, wherein the binding agent has melamine resin, formaldehyde resin, phenol resin, methylene diphenylisocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PDMI), polyurethane, or mixtures of the aforementioned binding agents as well as optionally a liquid plasticizing additive, applying the binding agent, optionally with the plasticizing additive to the fibers (5), wherein the plasticizing additive is applied with the binding agent to the fibers, forming a fiber cake from the fibers provided with binding agent and optionally with the plasticizing additive, pressing the fiber cake in a press while curing the binding agent to create a planar material (1).

2. The method according to claim 1, wherein acrylate, styrene acrylate, polyurethane, polyvinyl acetate, ethylene vinyl acetate, mono- or diethylene glycol are added as the plasticizing additive of the planar material.

3. The method according to claim 2, wherein the plasticizing additive is used as a solid in a ratio of maximally 1:1, in relation to the solid of the binding agent.

4. The method according to claim 2, wherein the plasticizing additive is applied to the fibers before or after the binding agent or is mixed with the binding agent before being applied to the fibers and is then applied to the fibers.

5. The method according to claim 1, wherein a continuous or a discontinuous press, in particular a hot press, is used for producing the planar material.

6. The method according to claim 1, wherein the pressing temperature is 140° C. to 220° C., preferably 160° C. to 180° C.

7. The method according to claim 1, wherein the pressing pressure is 0.3 N/mm.sup.2 to 5.5 N/mm.sup.2.

8. The method according to claim 1, wherein the pressing duration is 6 seconds/mm of board thickness to 60 seconds/mm of board thickness.

9. The method according to claim 1, wherein the fibers are provided wet, partially dried or dry with binding agent and optionally with the agent for plasticizing, wherein, when applying the binding agent and optionally the agent for plasticizing, the fibers are subsequently dried.

10. A planar material, produced according to the method according to claim 1 in a press, comprising lignocellulose fibers (5) and binding agents, wherein the binding agent has melamine resin, formaldehyde resin, phenol resin, methylene diphenylisocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PDMI), polyurethane, or mixtures of the aforementioned binding agents, and wherein the proportion of the binding agent with an optionally used plasticizing agent is more than 50 wt % of the planar material (1), and wherein the plasticizing agent is applied with the binding agent to the fibers.

11. The material according to claim 10, wherein the material (1) comprises natural fibers, synthetic fibers, inorganic or organic fibers, or mixtures of fibers.

12. The material according to claim 11, wherein the organic, natural fibers comprise lignocellulose fibers from renewable raw materials.

13. The material according to claim 11, wherein the synthetic fibers comprise fibers made of thermoplastic material.

14. The material according to claim 11, wherein the inorganic fibers comprise fibers made of mineral, ceramic, or glass materials.

15. The material according to claim 10, wherein the proportion of binding agent in relation to atro wood is more than 101 wt %.

16. The material according to claim 10, wherein the planar material (1) has an aggregate, non-hygroscopic or non-swelling fillers.

17. The material according to claim 16, wherein mineral, ceramic, synthetic, or glass particles are used as the aggregate.

18. The material according to claim 10, wherein the planar material (1) has hydrophobing agents.

19. A use of a planar material according to claim 10, wherein the planar material (1) is used in interior finishing as a floor board or floor laminate, as a wall or ceiling board, as a furniture board, when finishing damp and wet rooms, in outdoor construction as a facade board or for roofing, for stables, for terrace construction, including decking or outdoor flooring, and outdoor structures.

20. (canceled)

21. (cancelled)

22. The method according to claim 1, wherein the binding agent is provided in liquid form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Details of the invention are explained below with regard to exemplary embodiments. It is shown in:

[0043] FIG. 1 a schematic representation of a planar material according to the invention.

DETAILED DESCRIPTION

[0044] The figure shows a planar material 1 with an upper face 2 and a lower face 3 as well as an edge 4. The material has fibers 5 that are embedded in binding agent. The proportion of binding agent is more than 50 wt % of the planar material. There is therefore more binding agent than fiber 5. Natural, synthetic, organic, and inorganic fibers can be used as the fibers, both individually and in a mixture. Hygroscopic fibers such as wood, cellulose, or linen fibers can also be used. Melamine is preferably used as the binding agent, often in combination with formaldehyde or phenol but also in a mixture with PMDI. Examples of combinations of fibers and binding agent are described below.

Exemplary Embodiment 1

[0045] For the experiment whose results are shown in Table 1 below, lignocellulose fibers, in this case coniferous wood fibers, were used. The fibers were produced from steamed wood chips through defibration in a refiner. Alternatively, any other lignocellulose fibers or mixes of such fibers can be used. The coniferous wood fibers are used with a moisture of 120% before gluing; before pressing, they are dried with the binding agent located thereon to a residual moisture of 8%, i.e., a ton of fibers contains 80 kg of water.

[0046] For this experiment, more than 100 wt %, in the present case 108 wt %, of binding agent in relation to atro wood is used, here a binding agent comprising melamine-formaldehyde resin (MF resin). The melamine-formaldehyde resin (MF resin) used in the binding agent had a solids concentration of 60% (measured at 60 min/120° C.). Thus, 180 grams of liquid binding agent, containing 108 g of MF resin, were applied to 100 grams of atro fiber material (atro wood), taking into account the liquid content (108 g at 60% solids concentration=180 g). “Atro wood” here refers to lignocellulose fibers that have been dried at 105° C. to a constant weight. “Atro wood” is a typical reference measure for formulations containing lignocellulose fibers. The other exemplary embodiments are based on the absolute use of the binding agent.

[0047] Furthermore, 1.2 wt % paraffin in relation to atro wood is used.

[0048] The binding agent is applied to the lignocellulose fibers in four passes; 27 wt % is applied to the fibers per pass. The liquid binding agent is sprayed through nozzles in a known device for gluing fibers. The spray mist created by the nozzles condenses on the surface of the fibers that pass the spray mist, e.g., fall downwards from above through the spray mist of binding agent.

[0049] Drying the glued fibers in means for drying comes after the device for gluing fibers, for example a hot air tunnel or duct that applies heated air to the fibers. The goal of drying is not to completely remove all the liquid, but to dry the binding agent to an extent that it no longer sticks. The reactivity of the binding agent during curing under the effect of pressure and/or temperature should not be negatively impacted by the drying.

[0050] After drying, the fibers can be stored, or glued or processed further. First comes a second pass through the device for gluing, in which again 27 wt % MF resin is sprayed onto the fibers, which are already preglued after the first pass. The glued fibers are also dried after the second pass until they no longer adhere or stick to each other. In the same way, a third and fourth pass through the device for gluing and the means for drying are performed. Alternatively, the 110 wt % binding agent can also be applied to the fibers in one or two passes, or alternatively also in five or more passes. The amount of binding agent applied to the fibers per pass can vary from pass to pass.

[0051] After each pass, a part of the glued fibers is removed and processed to form a planar material with a thickness of 7 mm. This occurs by scattering a fiber cake, which is pressed in a known continuously operating double-belt press at 180° C. and a pressure of 2.5 N/mm.sup.2 with a pressing during of 15 s/mm. The board created in this way has a thickness of 5.5 mm and a density of 1050 kg/m.sup.3. As a reference, on one hand, a planar material produced under the same conditions without an increased addition of binding agent is examined (Table 1, pass 0).

[0052] The planar material produced in this way is examined for swelling in accordance with DIN 317 and for edge swelling in accordance with DIN 13329. The swelling in thickness is determined at an edge of the material as an absolute change in mm in relation to the starting thickness of 7 mm and also as a relative change (%).

TABLE-US-00001 TABLE 1 Swelling in thickness for a planar material, thickness 7 mm, binding agent use increasing from 0 to 108 wt % Pass no. 0 1 2 3 4 Difference, absolute (mm) 1.47 0.50 0.25 0.21 0.12 Difference, relative (%) 22.92 7.45 3.82 3.05 1.83

[0053] In the planar material without the addition of a binding agent (pass 0), the swelling in thickness according to Table 1 is, as expected, at a maximum at nearly 23%. Each pass, in which 27 wt % MF resin is applied each time, reduces the swelling in thickness at the edge of the planar material. An exceedingly low value of 1.83% edge swelling is achieved when 108 wt % binding agent in relation to atro wood is used.

Exemplary Embodiment 2

[0054] For the fiber proportion of the planar material in exemplary embodiment 2, a 50:50 mixture of different fibers, in this case, for example, wood fibers and carbon fibers, alternatively, for example, recycled paper fibers and fiberglass fibers, alternatively mineral fibers and cellulose fibers, is used. The natural fibers (wood, recycled paper, cellulose fibers) here are preferably dried before gluing; the fibers can be mixed before or after the gluing and the optional drying of the binding agent. Both variants allow a homogeneous mix of glued fibers to be produced, which can then be scattered to form a fiber cake. Otherwise, exemplary embodiment 2 is identical to exemplary embodiment 1 with regard to the use of the binding agent and the use of paraffin.

Exemplary Embodiment 3

[0055] Exemplary embodiment 3 relates to a mixture of fibers and binding agent in which 50 parts of polyethylene fibers and 20 parts of carbon fibers and 10 parts of aggregate, for example glass, mineral or ceramic particles, form the fiber proportion, which is glued with 115 wt % binding agent, in this case, for example, with MF resin. The fiber/aggregate/binding agent mix is otherwise treated as in exemplary embodiment 1.

Exemplary Embodiment 4

[0056] A board made of fibers and binding agent should be produced that can be used for producing a floor covering and can in particular be coated with a decorative surface, in particular either with synthetic resin-impregnated papers or by painting. 40 wt % fibers with a density of approx. 550 kg/m.sup.3 and 55 wt % of a binding agent, in this case an MF resin with a melamine proportion of more than 60%, are used. In addition, 5 wt % other materials are used, in this case 1.5 wt % paraffin and 3.5 wt % gray dye. The dye is used to give the planar material a uniform color.

[0057] The planar material with the composition mentioned above is produced on an industrial continuous press and compared to HDF boards that have been produced from the same fiber material but with a binding agent proportion of 15 wt % and have a density of 880 kg/m.sup.3.

TABLE-US-00002 TABLE 2 Comparative experiments on swelling of an HDF board and a board according to the invention Transverse Edge Board tensile Swelling swelling, thickness Binding Density strength of raw coated Experiment (mm) agent (%) (kg/m.sup.3) (N/mm.sup.2) board (%) (%) Standard 6   15% 880 >1.4 18-22 14-18 HDF Planar 5.8 137.5% 1050 >4.5 0.1-.03 1.0-1.2 material

[0058] Table 2 above shows the two boards in comparison, with the board thickness given in mm as a gross value (before sanding) and the density in kg/m.sup.3. The boards were each evaluated according to transverse tensile strength (DIN EN 319), swelling (measured in accordance with EN 317), and edge swelling (measured in accordance with EN 13329).

[0059] The board according to the invention can be more strongly compressed than a fiber board due to the high fiber proportion. The use of binding agent is approx. 9 times higher than with the HDF board according to the prior art. The planar material according to the invention has a transverse tensile strength that is three times higher and a swelling of the raw board that is reduced by a factor of 100. After laminating the upper face and the lower face, the “coated” edge swelling is measured. Only the edges are still accessible to the effect of water since the upper face and lower face of the board are sealed by the lamination and are no longer accessible to the water. This test is especially meaningful for floor coverings because the edges of the floor panels typically cannot be sealed and thus are subject to water. In this case, an edge swelling for the board material according to the invention that is reduced to a tenth in comparison to a known HDF board is shown. Both the HDF board and the planar material according to the invention were produced on the same industrial production system.