FR2890593A1 - Agglomerated wooden panel for covering external face of floors, comprises a layer of ligno-cellulosic material covered by an acrylic protective film on one of its sides - Google Patents

Abstract

The agglomerated wooden panel for covering external face of floors, comprises a layer of ligno-cellulosic material covered by an acrylic protective film on one of its sides. Lateral sides of the panel are covered by a hydrophobic substance such as silicone, paraffin, and a fluorinated substance. The panel is in the sandwich form. The panel is arranged in an order of kraft paper layer, wooden layer, and optionally decorative layer. The panel is arranged in the order of the paper layer and the decorative layer. The agglomerated wooden panel for covering external face of floors, comprises a layer of ligno-cellulosic material covered by an acrylic protective film on one of its sides. Lateral sides of the panel are covered by a hydrophobic substance such as silicone, paraffin, and a fluorinated substance. The panel is in the sandwich form. The panel is arranged in an order of kraft paper layer, wooden layer, and optionally decorative layer. The panel is arranged in the order of the paper layer and the decorative layer. The panel is arranged in the order of the paper layers, which are placed between two decorative layers. The panel is arranged in the order of optionally decorative layer, the wooden layer, the paper layer, the wooden layer, and optionally the decorative layer. The protective film comprise multi-layers comprising a surface and an adhesive layers. The adhesive layer is disposed on one side of the panel. Fluorinated polymer is in the form of an aqueous emulsion. The fluorinated polymer is optionally modified by the acrylic polymer. An independent claim is included for a process.

Description

The invention relates to a panel consisting of one or more

  layer (s) of (ligno) cellulosic material and covered by a protective film. This type of panel is widely used in everyday life, especially in the

  exterior cladding of facades. This is usually a sandwich panel.

  The panel is covered with a protective film to protect it from bad weather and UV radiation. It is often a mono- or bilayer film comprising a layer of an acrylic material.

  When the panel is placed outside, the rainwater or the ambient humidity can infiltrate by at least one of the lateral faces of the panel, which can cause a detachment of the protective film and also a bleaching of the film side side faces that are exposed to water or moisture. The detachment of the film, even minimal, is harmful because it involves an exposure, so a less protection, a part of the panel.

  The Applicant has solved the problem of delamination and / or bleaching by applying to at least one of the lateral faces of the panel a hydrophobic substance.

  The prior art European application EP 1199157 A1 discloses a sandwich panel coated with a transparent / translucent acrylic multilayer film on at least one of its faces.

  European application EP 1388414 A1 describes a sandwich panel coated with a two-layer PMMA / PVDF film or monolayer based on a PMMA / PVDF mixture.

  FIG. 1 shows a panel 1 having the shape of a parallelepiped comprising one or more layer (s) of (ligno) cellulosic material 3 covered on one of its faces by a protective film 2. The four lateral faces, referenced 4, 4 ', 4 "and 4"' are covered by a hydrophobic substance.

  Figure 2 shows a stack 5 of panels 1 and illustrates one of the means for applying the hydrophobic substance. A technician 6 sprays on the side faces 4 of the panels 1 a hydrophobic substance.

Brief description of the invention

  The invention relates to a panel comprising at least one layer of (ligno) cellulosic material covered on at least one of its faces by a protective film, characterized in that at least one of the lateral faces of the panel is covered by a hydrophobic substance.

  Preferably, the hydrophobic substance is an emulsion of a fluoropolymer, preferably modified with an acrylic polymer.

  The invention also relates to a process consisting in applying to at least one of the lateral faces of the panel a hydrophobic substance. Preferably, the hydrophobic substance is sprayed.

  Detailed description of the invention

  (Ligno) cellulosic material means a lignocellulosic or cellulosic material.

  Regarding the panel, it comprises at least one layer of a (ligno) cellulosic material. The panel may have a parallelepiped shape as shown in FIG. 1. However, the invention is not limited only to parallelepiped panels but can be applied to other shapes. Thus, for example the panel may have a wedge shape.

  The (ligno) cellulosic material can be: É wood; Paper, preferably kraft paper; É agglomerated wood.

  It may be a panel comprising a single layer such as a solid wood panel or a chipboard. A chipboard consists of wood particles (in different forms: sawdust, chips, fibers, ...) treated with at least one thermosetting resin and subjected to high pressure and temperature. It may also be a panel comprising several identical or different layers of material (x) (ligno) cellulosic (s). We often speak in this case of sandwich panel.

  The panel may also include at least one layer of an elastomeric material or a foam whose function is to improve the sound insulation of the panel. It may also include at least one counterbalancing layer whose function is to mechanically stabilize the panel to prevent buckling or deformation of the panel.

  To promote adhesion between the layers, they are impregnated with a glue so that an intermediate layer of glue, usually thin, is disposed between the layers that must adhere. Preferably, the glue is a thermosetting glue, for example of the phenolic or melaminic type.

  Examples of sandwich panels are given in EP 1388414 A1, EP 1199157 A1 or GB 2307882 A. Thus example 1 of EP 1199157 A1 describes a panel comprising in the following order: a layer of phenolic kraft paper of grammage 180/290 g / m2 a layer of glue; a layer of wood; a decorative layer composed of a stained cellulose film and a cellulose film impregnated with melamine and having a silica filler.

  Another example of a sandwich panel comprises in order a layer of paper, a layer of wood and optionally a decorative layer or a layer of paper and a decorative layer. Another example of a sandwich panel optionally comprises a decorative layer, a layer of wood, a layer of paper, a layer of wood and optionally a decorative layer. Another example of a sandwich panel comprises in the order of a decorative layer, a layer of wood and a decorative layer. The protective film is applied on the wood layer or on the decorative layer. A paper layer can also be replaced by a stack of several layers of paper. Preferably, the paper used is kraft paper.

  The decorative layer may be unicoloured or have a printed pattern. It may be one or more cellulose film (s) or printed paper. It may also be a layer of thermosetting glue loaded with pigments.

  The adhesion between the layers is ensured by means of a glue. Preferably, the glue is a thermosetting glue of the phenolic or melaminic type. A layer of glue, often thin, is therefore arranged between the layers.

  We can still give examples of sandwich panels that are marketed. PRODEMA's BAQ + panel is described on the company's website as a high-density board consisting of a cellulose fiber core impregnated with thermosetting phenolic resins and a layer of natural wood. The PRODEMA MAD panel is described as a panel consisting of a core of wood plywood impregnated with thermosetting phenolic resins and a layer of natural wood. The PARKLEX 1000 panel from GUREA is described on the company's website as a high-density wood laminated panel made internally of wood or paper fibers treated with thermoset phenol resins and very strongly pressed at raised temperatures and a layer of natural wood. The protective film is applied against the wood layer.

  The panel is for example used in the coating of exterior or interior facades or the realization of floors. It preferably has a thickness of between 1 and 60 mm, advantageously between 10 and 60 mm.

  The panel is often protected on at least one of its faces by a protective film. The protective film provides protection against: UV rays; É chemicals; É atmospheric agents (humidity, salt spray, etc.); Mushrooms and molds; Graffiti; É fire.

  The film provides stability of color and appearance over time. The film is usually applied to the panel by hot pressing. The compression is carried out under a pressure generally between 2 and 30 MPa and hot at a temperature generally between 100 and 160 C.

  As regards the protective film, it may be monolayer or bilayer. An example of a monolayer protective film is an acrylic film comprising a PMMA homo- or copolymer. PMMA means a homopolymer of methyl methacrylate (MMA) or a copolymer of MMA containing at least 50% by weight of MMA and at least one comonomer copolymerizable with MMA. As examples of comonomers, mention may be made, for example, of alkyl (meth) acrylates, acrylonitrile, butadiene, styrene and isoprene. Examples of alkyl (meth) acrylates are described in KIRK-OTHMER, Encyclopedia of Chemical Technology, 4th edition in Vol. 1, pp. 292-293 and in Vol. 16 pages 475-478. Advantageously, the PMMA may contain 0 to 20% by weight and preferably 5 to 15% of methyl acrylate and / or ethyl acrylate. PMMA can be functionalized, that is to say it contains, for example, acid, acid chloride, alcohol, anhydride functions. These functions can be introduced by grafting or by copolymerization. Advantageously it is an acid function provided by the (meth) acrylic acid comonomer. Two neighboring acrylic acid functions may dehydrate to form an anhydride. The proportion of functions can be from 0 to 15% by weight of the PMMA including the possible functions. The MVI (melt volume index or melt volume melt index) of the PMMA can be between 2 and 15 cm3 / 10 min measured at 230 C under a load of 3.8 kg.

  An example of a multilayer protective film comprises: a surface layer comprising, by weight, from 0 to 100 parts, advantageously from 50 to 100 parts, preferably from 70 to 100 parts of a fluorinated polymer for respectively from 0 to 100 parts, advantageously from 0 to 50 parts, preferably 0 to 30 parts of a PMMA, and E an adhesive layer comprising from 50 to 100 parts of a PMMA, from 0 to 50 parts of a fluoropolymer, from 0 to 50 parts a shock modifier and 0 to 5 parts of a UV absorber, the adhesive layer being disposed on at least one of the faces of the panel.

  Other examples of multilayer films are given in EP 1382640 or EP 1566408.

  The fluoropolymer is preferably a PVDF homopolymer or a copolymer comprising at least 50% by weight of VDF (vinylidene fluoride, CH2 = CF2) and at least one comonomer copolymerizable with VDF. Advantageously, the comonomer is fluorinated, it can be chosen for example from vinyl fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE); perfluoro (1,3-dioxole); perfluoro (2,2-dimethyl-1,3-dioxole) (PDD). Preferably, the optional comonomer is chosen from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and tetrafluoroethylene (TFE).

  HFP is the preferred comonomer.

  Advantageously, the PVDF has a viscosity ranging from 100 Pa.s to 2000 Pa.s, the viscosity being measured at 230 ° C., at a shear rate of 100 μl using a capillary rheometer.

  Indeed, these PVDF are well suited to extrusion and injection. Preferably, the PVDF has a viscosity ranging from 300 Pa.s to 1200 Pa.s, the viscosity being measured at 230 C, at a shear rate of 100 s 1 using a capillary rheometer.

  The impact modifier is, for example, a core-shell copolymer which is in the form of fine particles having an elastomer core and at least one thermoplastic shell, the particle size is generally less than the pm and advantageously between 50 and 300 nm. By way of example of nuclei, mention may be made of homopolymers of isoprene or butadiene, copolymers of isoprene with at most 30 mol% of a vinyl monomer and copolymers of butadiene with at most 30% by weight. moles of a vinyl monomer. The vinyl monomer may be styrene, alkylstyrene, acrylonitrile or an alkyl (meth) acrylate. Another family of cores consists of homopolymers of an alkyl (meth) acrylate and copolymers of an alkyl (meth) acrylate with at most 30 mol% of a monomer selected from another (meth) ) alkyl acrylate and a vinyl monomer. The alkyl (meth) acrylate is advantageously butyl acrylate.

  The vinyl monomer may be styrene, alkylstyrene, acrylonitrile, butadiene or isoprene. The core of the core-shell copolymer may be crosslinked in whole or in part. It suffices to add at least difunctional monomers during the preparation of the nucleus, these monomers may be chosen from poly (meth) acrylic esters of polyols such as butylene di (meth) acrylate and trimethylolpropane trimethacrylate. Other difunctional monomers are, for example, divinylbenzene, trivinylbenzene, vinyl acrylate and vinyl methacrylate. The core may also be cross-linked by grafting or as a comonomer during the polymerization, unsaturated functional monomers such as unsaturated carboxylic acid anhydrides, unsaturated carboxylic acids and unsaturated epoxides. Mention may be made, for example, of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate.

  The bark or barks are homopolymers of styrene, alkylstyrene or methyl methacrylate or copolymers comprising at least 70 mol% of one of these monomers and at least one comonomer selected from the other monomers above another alkyl (meth) acrylate, vinyl acetate and acrylonitrile. The bark may be functionalized by introducing, by grafting or as comonomer during the polymerization, unsaturated functional monomers such as unsaturated carboxylic acid anhydrides, unsaturated carboxylic acids and unsaturated epoxides. Mention may be made, for example, of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate.

  By way of example, mention may be made of core-shell copolymers having a polystyrene bark and core-shell copolymers having PMMA bark. There are also core-shell copolymers with two barks, one made of polystyrene and the other outside PMMA. Examples of copolymers and their method of preparation are described in the following patents US 4180494, US 3808180, US 4096202, US 4260693, US 3287443, US 3657391, US 4299928, US 3985704, US 5773520.

  Advantageously, the core represents, by weight, 70 to 90% of the core-shell copolymer and the 10% bark. By way of example of copolymer, mention may be made of the one consisting of (i) from 75 to 80 parts of a core comprising in moles at least 93% of butadiene, 5% of styrene and 0.5 to 1% of divinylbenzene and ii) from 25 to 20 parts of two barks of essentially the same weight, one of polystyrene and the other of PMMA. By way of other example, mention may be made of those having a poly (butyl acrylate) or copolymer core of butyl acrylate and butadiene and a PMMA bark.

  All these core-shell copolymers are sometimes called soft / hard because of the elastomeric core.

  There are also other types of core-shell copolymers such as hard / soft / hard that is to say they have in this order a hard core, soft bark and hard bark. The hard parts may consist of the above soft / hard bark polymers and the soft part may consist of the above soft / hard core polymers. There may be mentioned, for example, those constituted in this order: of a copolymer core of methyl methacrylate and ethyl acrylate, and of a bark made of a copolymer of butyl acrylate and styrene, a bark copolymer of methyl methacrylate and ethyl acrylate.

  There are still other types of core-shell copolymers such as hard (kernel) / soft / medium hard. Compared to the previous ones, the difference comes from the outer bark "mi dur" which consists of two barks. one intermediate and the other external. The intermediate bark is a copolymer of methyl methacrylate, styrene and at least one monomer selected from alkyl acrylates, butadiene and isoprene. The outer bark is a PMMA homopolymer or copolymer. For example, those made in this order.

  É of a copolymer core of methyl methacrylate and ethyl acrylate, É of a bark copolymer of butyl acrylate and styrene, E of a bark copolymer of methyl methacrylate, butyl acrylate and styrene, E of a bark copolymer of methyl methacrylate and ethyl acrylate.

  The protective film may also be a polyester film, PET type for example.

  As regards the UV absorber, this is described for example in US Pat. No. 5,256,472. Benzotriazoles and benzophenones are advantageously used. By way of example, TINUVIN 213 or TINUVIN 109 can be used and, preferably, TINUVIN 234 from Ciba Specialty Chemicals.

  As regards the hydrophobic substance, it may be a silicone, a paraffin, a fluorinated substance such as an oligomer or a fluorinated polymer or a perfluoroether. Preferably, the fluorinated substance is in a liquid form when it is to be applied. The fluoropolymer is preferably in the form of an aqueous emulsion so that it can be easily applied, for example by spraying, and without having to use a solvent.

  It may be for example an emulsion of a PVDF homo- or copolymer. PVDF can be advantageously modified with an acrylic polymer. One way of modifying the PVDF by an acrylic polymer is to polymerize at least one acrylic monomer in the presence of a PVDF latex. The acrylic monomer is chosen from (meth) acrylates and (meth) acrylic acid. Preferably, the (meth) acrylate is a C1-C10 ester, more preferably C1-C4. For example, it is ethyl (meth) acrylate, propyl, butyl, amyl, isobutyl, 2-ethylhexyl, hydroxyethyl, glycidyl. The acrylic monomer and the PVDF latex are brought into contact in the presence of at least one radical initiator, at least one surfactant and optionally a transfer agent. The proportion of acrylic monomer latex is from 10 to 200 parts, preferably from 20 to 100 parts per 100 parts of PVDF latex.

  The surfactant may be of anionic, cationic, nonionic or amphoteric type. It is possible to add to the mixture to be polymerized a solvent whose function is to swell the latex particles.

  Preferably, the glass transition temperature of the PVDF is less than 25 ° C. Preferably, the size of the latex particles is less than 250 nm.

  Examples of modified PVDF can be found in WO 9901505 A1 and WO 9903900 A1.

  The aqueous emulsion of the fluoropolymer, optionally modified with the acrylic polymer, may contain additives such as: thickening agents such as, for example, Rheolate 288; Wetting agents such as BYK 346 or BYK 348; É acidic or basic compounds whose role is to stabilize the emulsion.

  The hydrophobic substance is applied to the side face (s) exposed to water or moisture. In some cases, if the four side faces are exposed, it is the four faces that are covered by the hydrophobic substance.

  The role of the hydrophobic substance is to avoid peeling and / or bleaching of the film by the action of moisture. Another function of the hydrophobic substance is to protect the side faces of the panel (which are therefore not protected by the protective film) against UV rays, chemicals, atmospheric agents (humidity, salt spray, etc.). fungi and molds. The use of a protective film to cover the side faces is hardly possible when the faces are too thin to be covered with a film.

  The invention also relates to a method of applying a hydrophobic substance to at least one of the side faces of a panel. The hydrophobic substance can be applied to a stack of panels. The panels can be stacked as shown for example in Figure 2. In the case of the aqueous emulsion of the fluoropolymer, it may be useful to provide an additional step of allowing the water to evaporate. emulsion.

  The hydrophobic substance may be applied by means of a brush or by spraying, for example by means of a spraying system usually used for paints.

Claims (18)

claims   1. Panel comprising at least one layer of a (ligno) cellulosic material covered on at least one of its faces by a protective film characterized in that at least one of the lateral faces of the panel is covered by a hydrophobic substance .   2. Panel according to claim 1 characterized in that it is a wooden panel.   3. Panel according to one of claims 1 or 2 characterized in that it is a chipboard.   4. Panel according to claim 1 characterized in that it comprises in order a layer of paper, a layer of wood and optionally a decorative layer.   5. Panel according to claim 1 characterized in that it comprises in order a layer of paper and a decorative layer.   6. Panel according to claim 1 characterized in that it comprises in order optionally a decorative layer, a wood layer, a paper layer, a wood layer and optionally a decorative layer.   7. Panel according to claim 1 characterized in that it comprises in order a decorative layer, a layer of paper and a decorative layer.   8. Panel according to one of claims 4 to 7 characterized in that the paper layer consists of a stack of several layers of paper.   9. Panel according to one of claims 4 to 8 characterized in that the paper is kraft paper.   10. Panel according to any one of claims 1 to 9 5 characterized in that the protective film is an acrylic film comprising a PMMA homo- or copolymer.   11. Panel according to any one of claims 1 to 9 characterized in that the protective film is a multilayer film comprising: a surface layer comprising, by weight, from 0 to 100 parts, advantageously from 50 to 100 parts, preferably from 70 to 100 parts of a fluoropolymer for respectively from 0 to 100 parts, advantageously from 0 to 50 parts, preferably from 0 to 30 parts of a PMMA, and E an adhesive layer comprising from 50 to 100 parts of a PMMA, from 0 to 50 parts of a fluorinated polymer, from 0 to 50 parts of a shock modifier and from 0 to 5 parts of a UV absorber, the adhesive layer being disposed on at least one of the faces of the sign.   12. Panel according to claim 11 characterized in that the fluoropolymer is a PVDF homopolymer or copolymer comprising at least 50% by weight of VDF and at least one comonomer copolymerizable with VDF.   13. Panel according to any one of claims 1 to 12 characterized in that the hydrophobic substance is a silicone, a paraffin, a fluorine substance.   14. Panel according to claim 13 characterized in that the fluorinated substance is an oligomer or a fluorinated polymer or a perfluoroether.   15. Panel according to claim 14 characterized in that the fluoropolymer in the form of an aqueous emulsion.   16. Panel according to one of claims 14 or 15 characterized in that the fluoropolymer is a PVDF homo- or copolymer, optionally modified with an acrylic polymer.   17. A method of applying a hydrophobic substance as defined in any one of claims 13 to 16 on at least one of the side faces of a panel as defined in any one of claims 1 to 12.   18. The method of claim 17 characterized in that the hydrophobic substance is sprayed.