Abstract:
A process for producing a veneer is disclosed wherein a layer made from a polyolefin, a copolymeric polyolefin or both is applied to a veneer sheet using heat and/or pressure. A veneer produced using this process is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a process for producing a veneer and to a product produced in this way.  
           [0003]    2. Description of the Related Art  
           [0004]    In order to restrain as far as possible the use of high-value timbers, it is nowadays usual to cover the surfaces of a wide variety of articles, e.g. of furniture, with wood veneer.  
           [0005]    The object of the invention is to provide a veneer which makes operations easy and cost-effective, retains the aesthetic impression of the high-quality timber and can accept chemical and physical stresses.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    The novel process for producing a veneer of this type comprises the steps of  
           [0007]    a) applying to a veneer sheet a layer made from the group consisting of a polyolefin, a copolymeric polyolefin and a mixture of polyolefin and copolymeric polyolefin and  
           [0008]    b) bonding to one another the veneer sheet and the material of the layer.  
           [0009]    A veneer sheet is therefore to be understood here as a conventional veneer made from timber, e.g. from a high-value timber. The product produced according to the invention, i.e. the veneer in the sense of this application, is then the veneer sheet processed in the manner described above, i.e. a product in which the wood veneer sheet has been penetrated by the above-mentioned polyolefins or copolymeric polyolefins, etc.  
           [0010]    This gives a veneer which has significantly better shapeability than conventional veneer sheets. This opens up a broad range of applications for veneers and also allows dramatic simplification of operations with veneers compared with the prior art.  
           [0011]    Preference is given to application by pressure in step (b) at pressures of from 5 to 20 bar. Temperatures preferred for the application by pressure are in the range from 150 to 200° C.  
           [0012]    A particularly preferred embodiment of the invention provides that ESI is used as the layer which, with pressure and/or heat, penetrates the wood veneer sheet. ESI is an ethylene-styrene interpolymer supplied by Dow Chemical under this name. It is a copolymeric polyolefin. Its properties with respect to the present invention are in particular very good adhesive bonding performance (with pressure and temperature), good shapeability, good capability for decoration by the “release” method and good coatability.  
           [0013]    Further preferred embodiments of the invention are described in the dependent claims.  
           [0014]    A particularly preferred embodiment of the invention provides that the layer to be applied by pressure to the wood veneer sheet has at least two sublayers with different proportions of ethylene and styrene, where the sublayer initially facing the wood comprises more ethylene than does the sublayer initially facing away from the wood.  
           [0015]    A veneer produced according to the invention is preferably further processed by being clamped, in the final shape (structure) desired, into an injection moulding machine and being back-moulded with plastic in a manner known per se. This gives a stable high-quality product with a surface which is of high quality and which is in particular aesthetically attractive. The surface has good coatability and capability for decoration. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The invention is described below by way of example, using the drawing. This shows:  
         [0017]    [0017]FIG. 1 is a diagram illustrating the novel process using a veneer sheet and a layer lying thereupon;  
         [0018]    [0018]FIG. 2 is a diagram of a preferred working example of the polyolefin layer to be processed; and  
         [0019]    [0019]FIG. 3 is a diagram of a veneer produced according to the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    A veneer sheet  10  is firstly prepared from timber.  
         [0021]    A layer  12  is applied to the wood veneer sheet  10 . The layer  12  is composed, for example, of a polyolefin and/or of a copolymeric polyolefin or of a mixture comprising at least one of these constituents.  
         [0022]    The material ESI is preferred for the layer  12 , that is to say an ethylene-styrene interpolymer (supplied as ESI by Dow Chemical). The advantageous properties of this material have been mentioned above.  
         [0023]    Depending on the use intended, the thickness of the wood veneer sheet  10  is, for example, in the range from 200 μm to 1 mm.  
         [0024]    The thickness of the layer  12  applied, made from ESI for example, is preferably from 20 to 200 μm, depending on the thickness and the desired properties of the veneer to be produced.  
         [0025]    The layer  12  is then applied by pressure to the veneer sheet  10 , whereupon the material of the layer  12  penetrates into the porous wood of the veneer sheet  10 . The pressures used may be in the range from 5 to 20 bar. The temperatures which prevail are preferably in the range from 150 to 200° C.  
         [0026]    This gives a veneer which is easy to shape and has good mechanical, physical and chemical properties.  
         [0027]    [0027]FIG. 2 shows a particular embodiment of the layer  12  for use with a wood veneer sheet  10  as in FIG. 1 (the wood veneer sheet  10  is not shown again in FIG. 2). The layer  12  as in FIG. 2 is composed of two sublayers  12   a  and  12   b . ESI is the material intended for both layers. The lower sublayer  12   a  of the layer  12  comprises more ethylene than does the upper sublayer  12   b . During further processing of the layer  12 , the lower sublayer  12   a  is undermost when applied to the wood veneer sheet  10 . When pressure and temperature are applied, as described above, the ethylene then penetrates more effectively into the porous wood material of the veneer sheet  10 . The higher styrene concentration in the upper sublayer  12   b  gives the resultant veneer better surface properties.  
         [0028]    The two layers  12   a  and  12   b  may be extruded, for example, by a coextrusion process know per se.  
         [0029]    [0029]FIG. 3 illustrates diagrammatically the veneer  10 ′ produced in this way, i.e. the veneer sheet  10  with the polyolefins or copolymeric polyolefins, in particular ESI, or mixtures of these, which have penetrated the veneer sheet. The layer  12  does not have to penetrate completely homogeneously into the veneer sheet  10 . It is perfectly acceptable for there to be a concentration gradient in the final product in the direction of the arrow P in FIG. 3. This applies in particular if the layer  12  used has a number of sublayers and different components which intentionally differ in their penetration into the wood material.  
         [0030]    The invention has been described with reference to preferred embodiments which are merely illustrative of the present invention and not restrictive thereof. Obvious modifications and alterations of the present invention may be made without departing from the spirit and scope of the present invention. The scope of the present invention is defined by the appended claims and equivalents thereto.