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EP-4735243-A1 - WOODEN COMPOSITE BOARD WITH AT LEAST ONE DEPRESSION IMPRINTED INTO THE UPPER SIDE

EP4735243A1EP 4735243 A1EP4735243 A1EP 4735243A1EP-4735243-A1

Abstract

The invention relates to a wooden composite board with a core (1), at least one decorative layer (2) which lies above the core (1) on an upper side (1.1) and below which at least one underlay (4) made of a paper coated with a resin is provided, at least one cover layer (3) which lies above the decorative layer (2), and at least one depression (5) which is imprinted into the upper side (1.1), which wooden composite board is characterized in that the resin is a mixed resin consisting of phenolic resin and melamine resin.

Inventors

  • KALWA, NORBERT
  • Seidack, Georg

Assignees

  • Flooring Technologies Ltd.

Dates

Publication Date
20260506
Application Date
20240628

Claims (13)

  1. 1. Wood-based panel with a core (1), at least one decorative layer (2) lying on an upper side (1.1) above the core (1), under which at least one underlay sheet (4) made of paper coated with a resin is provided, at least one cover layer (3) lying above the decorative layer (2) and at least one recess (5) embossed into the upper side (1.1), characterized in that the resin is a mixed resin of phenolic resin and melamine resin.
  2. 2. Wood-based panel according to claim 1, characterized in that the ratio of phenolic resin to melamine resin is 2:1.
  3. 3. Wood-based panel according to claim 1 or 2, characterized in that the weight of the paper is 80 to 260 g/m 2 and preferably the coating with resin is 60 to 200 g/m 2 .
  4. 4 Wood-based panel according to claim 1 or 2, characterized in that the resin coating is at least 60 g/m 2 , preferably at least 75 g/m 2 , particularly preferably at least 120 g/m 2 .
  5. 5. Wood-based panel according to one of the preceding claims, characterized in that at least one further recess (6) embossed at an angle of 90° transversely to the recess (5) is provided.
  6. 6. Wood-based panel according to claim 5, characterized in that a plurality of recesses (5, 6) running parallel to one another are provided.
  7. 7. Wood-based panel according to one of the preceding claims, characterized in that the recesses (5, 6) have a depth of at least 0.4 mm.
  8. 8. Wood-based panel according to one of the preceding claims, characterized in that the decorative layer (2) consists of a resin-impregnated decorative paper.
  9. 9. Wood-based panel according to claim 8, characterized in that the weight of the decorative paper is 60 to 160 g/m 2 .
  10. 10. Wood-based panel according to one of the preceding claims, characterized in that the covering layer (3) consists of a resin-impregnated overlay paper.
  11. 11. Wood-based panel according to one of the preceding claims, characterized in that the side walls (5.3, 6.3) of the recesses (5, 6) extend from the upper side (1.1) into the depth (T) at an angle a of 20°-60°, preferably 45°.
  12. 12. Wood-based panel according to one of the preceding claims, characterized in that the core (1) is an HDF panel.
  13. 13. Floor panel obtained after dividing the wood-based panel according to one of the preceding claims along the recesses (5, 6) and, if necessary, further machining steps for edge profiling.

Description

Wood-based panel with at least one recess embossed into the top The invention relates to a wood-based panel with a core, at least one decorative layer lying on an upper side above the core, under which at least one underlay sheet made of paper coated with a resin is provided, at least one cover layer lying above the decorative layer and at least one depression embossed into the upper side. A variety of design effects are used in modern laminate flooring to visually enhance the product or to get even closer to the original parquet or real wood flooring. Technical changes are also made to the product to make it easier to use over longer periods of time. Examples of this include the use of digital printers to produce wood reproductions without repeating the decor, improving the connection profiles to prevent water from penetrating, or designing the element edges with bevels. This design element was also borrowed from real wood floors. It has two functions. Firstly, the bevel visually loosens up the installation pattern, and secondly, machine-related height tolerances are concealed. However, the bevel also creates a weak point that makes it easier for water to penetrate the connection area of the floor elements. Although the bevel can be sealed using colored varnishes, this seal is usually not waterproof. This means that if this area is exposed to water frequently, e.g. during maintenance, swelling can occur. In order to avoid this problem, an attempt was made to pre-structure the coating of the wood-based material carriers in a short-cycle press with melamine impregnates in the area that would later become the bevel, using deeply structured embossed sheets. The bevel should then continue to be present as a melamine coating when the side edges are processed or profiled. EP 3 578 383 A1 discloses a method by which a relief is embossed into the top of an HDF board in a first embossing step as at least one strip-shaped depression. First, a coating agent is applied to the top, then a backing sheet made of resin-impregnated paper, then a decorative paper and an overlay paper on top of the decorative paper as an abrasion-resistant layer. This structure is fed into a press and pressed under high pressure and high temperature. During pressing, in a second embossing step, the at least one strip-shaped depression is embossed again without changing the depth. Finally, the pressed HDF board is divided into individual panels by making a saw cut along the depressions. Such panels can be used as floor panels or as wall and ceiling panels. They are often provided with a wood, stone or fantasy decor with a superimposed, three-dimensional surface. In order for a bevel to be clearly visible, the depth of the depression must be between 0.4 and 0.5 mm. Embossing calender rollers can be used to create the depression, which operate under a pressure of up to 600 N/mm 2 and a surface temperature of up to 220°. A short-cycle press with a deeply structured press plate with preferably strip-shaped elevations on the press plate can also be used. The known process does provide the technology for pressing the bevel, but other problems remain. The wood-based panels, especially fiberboards, which form the core and serve as the carrier material, show a so-called spring-back effect when pressed with deeply structured sheets. This means that after pressing, the wood-based panels do not show the structural depth of the sheet, but only about 60% of the embossed structural depth. This is related to the elasticity of the wood-based panels, which is in the short-cycle press and partially expands again after the pressure is released. This makes it necessary to structure the press plates much more deeply in order to create the desired structural depth in the final product. Another problem is that in the areas where the deep structuring takes place, the melamine resin papers used for the at least one underlay sheet, the decor and the overlay tend to tear due to overstretching. Attempts have been made to use strip-shaped impregnates for this purpose, but these are difficult to position on the wood-based panel. Ultimately, the targeting devices on the short-cycle presses are not designed for laying strip-shaped impregnates. The upstream impregnation channels cannot produce such strip-shaped impregnates, which leads to an additional work step after impregnation. It is also often observed that transparency defects appear in the deeply structured areas of the wood-based panel. Microcracks can also be found in the structure. On this basis, a generic wood-based panel is to be improved so that at least one embossed depression is as deep as possible and its depth is at least 0.4 mm, without significantly changing the pressing conditions usually used on a short-cycle press or making significant technical changes to the preliminary products (impregnates, wood-based panels, fiberboards). To solve the problem, a generic wooden tool board is characterized by the fac