US-20260125582-A1 - PARTIALLY CURED COATED SHEET

US20260125582A1US 20260125582 A1US20260125582 A1US 20260125582A1US-20260125582-A1

Abstract

A sheet includes a support layer and a coating layer on a side of the support layer. The coating layer is partially cured. The coating layer has carbon-carbon double bonds. The relative amount of carbon-carbon double bonds is higher at the surface of the coating layer than at the contact surface of the coating layer with the support layer. Methods are disclosed to manufacture such sheets; and to produce a decorative panel using such sheets.

Inventors

Benjamin Clement
Sam LEDEGEN
Marijn SEYNAEVE

Assignees

UNILIN, BV

Dates

Publication Date: 20260507
Application Date: 20251229

Claims (17)

1 . A coating composition, wherein the coating composition comprises one or more oligomers, wherein the one or more oligomers are selected from urethane acrylates, aliphatic urethane acrylates, methacrylates, or combinations thereof; one or more than one photo-initiator; one or more than one thermo-initiator; an acrylate monomer; a methacrylate diluent.
2 . The coating composition of claim 1 , wherein the oligomers comprise acrylates and methacrylates.
3 . The coating composition of claim 1 , wherein the coating composition comprises the one or more than one photo-initiator in a combined amount between 0.05 and 3 percent by weight of the coating composition.
4 . The coating composition of claim 1 , wherein the coating composition is provided for use in a method comprising the steps of providing a support layer, applying the coating composition on the support layer; and partially curing the coating by means of UV-radiation.
5 . The coating composition of claim 4 , wherein in partially curing the coating by means of UV-radiation, thereby obtaining a sheet comprising a support layer and a coating layer on a side of the support layer; the coating layer is partially cured; the coating layer comprises carbon-carbon double bonds, and wherein the relative amount of carbon-carbon double bonds is higher at the surface of the coating layer than at the contact surface of the coating layer with the support layer.
6 . The coating composition of claim 1 , wherein the methacrylate diluent comprises methacrylate diluents with functionality higher than 2 .
7 . The coating composition of claim 1 , wherein the methacrylate diluent comprises methacrylate diluents with functionality higher than 3 .
8 . The coating composition of claim 1 , wherein the acrylate monomers comprise acrylate monomers having functionality higher than 2 .
9 . The coating composition of claim 1 , wherein the acrylate monomers comprise acrylate monomers having functionality higher than 3 .
10 . The coating composition of claim 1 , wherein the one or more than one type of thermo-initiator comprises peroxide.
11 . The coating composition of claim 10 , wherein the peroxide is selected from benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxy-3,5,5-trimethylhexanoate or 1,1-di(t-amylperoxy)-cyclohexane.
12 . The coating composition of claim 1 , wherein at least part of the one or more than one thermo-initiator have a one hour half-life temperature higher than 90° C.
13 . The coating composition of claim 1 , wherein the thermo-initiators comprise a first group of thermo-initiators and a second group of thermo-initiators, wherein the first group of thermo-initiators provides between 10% by weight and 50% by weight of the combination of the first group of thermo-initiators and the second group of thermo-initiators, wherein the second group of thermo-initiators provides between 50% by weight and 90% by weight of the combination of the first group of thermo-initiators and the second group of thermo-initiators; wherein the thermo-initiators of the first group of thermo-initiators have a one hour half-life temperature which is at least 10° C. lower than the thermo-initiators of the second group of thermo-initiators.
14 . The coating composition of claim 1 , wherein the coating composition comprises additives, wherein the additives are selected from additives increasing the scratch resistance of the coating layer, antimicrobial agent or additives providing easy to clean surfaces to the coating layer, or combinations thereof.
15 . The coating composition of claim 1 , wherein the coating composition comprises particles that provide scratch resistance and/or taber resistance.
16 . The coating composition of claim 1 , wherein the coating composition comprises a plasticizer.
17 . The coating composition of claim 1 , wherein the coating composition comprises a hindered amine light stabilizer, a UV-absorber, or both.

Description

BACKGROUND This invention relates to partially cured coated sheets and to methods to make such sheets. The invention further relates to methods to thermally press the sheets onto a substrate in order to obtain a decorative panel having an embossed surface. The invention aims to provide panels with a substrate and a top layer applied thereto having a decor layer, for example a decor layer that comprises printing. Such panels for use as floor panels are widely known per se, for example from WO97/47834. The floor panels disclosed in WO97/47834 relate among others to floor panels with a substrate that is chiefly composed of an HDF sheet with a laminate layer pressed directly onto it that comprises one or more paper sheets impregnated with melamine resin, preferably also including a paper sheet with printing in for example a wood or stone motif, specifically a so-called decorative paper. The above-mentioned melamine resin forms among others a translucent wear layer above the decorative paper, but the transparency or translucency leaves much to be desired. The bottom of the substrate can comprise a backing layer or balancing layer, also based on a paper sheet impregnated with melamine resin. This backing layer provides a compensating effect for residual tensile stresses present in the cured melamine resin of the top layer. It remains possible to form extremely deep structures in the curing melamine surface. So-called white mountains frequently occur. These are zones in which inclusions are concentrated in the melamine surface. These primarily occur at sites in which deep indentations or structures are implemented. It is known that the melamine surface of such a laminate panel gives rise to clicking sounds in the use thereof. Multiple solutions to this problem are known from the prior art. WO03/016655 discloses the application of a sound-damping layer such as a cork layer under the melamine layer. It is known from WO2010/088769 to provide the melamine layers with a coating of a flexible monomer. WO2009/101217 and WO2010/070474 give examples of laminate panels wherein the top layer is composed, instead of melamine resin, mainly of polyvinyl chloride. WO2010/070474 discloses panels with a printed decor layer that can be formed on the substrate and is finished with a transparent polyvinyl chloride layer. Furthermore, a method is known from WO01/47726 of finishing panels with a printed decor layer with a UV (ultraviolet) curing or electron beam curing acrylate resin. The relatively high amount of photo-initiators required in curing by UV radiation has a detrimental influence on the quality of the surface obtained. The molecules that are used as photo-initiators are criticized because of the health risks they entail to humans. In panels in which the top layer is composed entirely of polyvinyl chloride (PVC), a loss of scratch resistance is observed in comparison to the conventional melamine surface. In addition, the PVC layer must be configured to be considerably thicker than a melamine layer in order to obtain comparable wear resistance. The nature and thickness of the PVC layer give rise to a plastic-like appearance of the floor panel, especially in cases where imitation of a product such as wood, stone or ceramic is intended. The relief that can be obtained in a PVC layer is unsharp, which detracts from the realistic appearance of the imitation obtained. In panels in which the top layer is obtained from UV cured or electron beam cured acrylate, such as in WO01/47726, favorable surface properties are achieved. The relief that can be obtained in such a top layer is limited in that structural films must be applied, for example such as in EP2019735. US2017/008334 relates to a method for producing a decorative panel. The method results in an impression of a structuring, with a lacquer-containing top layer. The method comprises several steps. A carrier is provided. A decoration is applied onto at least a partial region of the carrier. A lacquer-containing top layer is applied onto the decoration. The lacquer-containing top layer is partially hardened, wherein a partial hardening of the top layer is realized while forming a hardening gradient. The hardening gradient is established in the direction of the thickness of the top layer such that the surface region of the top layer is hardened comparably stronger than the deeper-lying region of the top layer. After the partial hardening of the top layer, the top layer is provided with a structuring. The structuring is realized at least partially by a negative structuring. The lacquer-containing top layer is final hardened. SUMMARY The object of the present invention is to provide improvements over the prior art, especially is solving problems related to the prior art. The first aspect of the invention is a sheet. The sheet comprises a support layer, and a coating layer on a side of the support layer. The coating layer is partially cured. The coating layer comprises carbon-carbon