Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
1999-12-30
2004-08-10
Jackson, Monique R. (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S326000, C428S524000, C428S530000, C428S535000, C428S537100, C264S109000, C264S112000, C156S062200, C156S244110, C156S307400
Reexamination Certificate
active
06773799
ABSTRACT:
The present invention relates to a process for manufacturing a decorative mainly isometric thermosetting laminate, a decorative thermosetting laminate obtained by the process, and use thereof.
Products clad with thermosetting laminates are quite common nowadays. They are most often used where the demand for abrasion resistance is great but also where resistance towards different chemical substances and moisture is required. Floors, floor skirtings, work tops, table tops, doors and wall panels can serve as an examples of such products. The thermosetting laminate is most often made from a number of base sheets and a decorative sheet placed closest to the surface. The decorative sheet may be provided with the desired decor or pattern. Thicker laminates are often provided with a core of particle board or fibre board where both sides are covered with sheets of thermosetting laminate. The outermost sheet is, on at least one side, most often a decorative sheet.
One problem with such thicker laminates is that the core is much softer than the surface layer which is made from paper impregnated with thermosetting resin. This will cause a considerably reduced resistance towards thrusts and blows compared to a laminate with a corresponding thickness made of paper impregnated with thermosetting resin only.
Another problem with thicker laminates with a core of particle board or fibre board is that these normally will absorb a large amount of moisture, which will cause them to expand and soften whereby the laminate will warp. The surface layer might even, partly or completely come off in extreme cases since the core will expand more than the surface layer. This type of laminate can therefore not be used in damp areas, such as wet rooms, without problem.
The problems can be partly solved by making the core of paper impregnated with thermosetting resin as well. Such a laminate is most often called compact laminate. These compact laminates are, however, very expensive and laborious to obtain as several tens of layers of paper have to be impregnated, dried and put in layers. The direction of the fibre in the paper does furthermore cause a moisture and temperature difference relating expansion. This expansion is two to three times as high in the direction crossing the fibre than along the fibre. The longitudinal direction of the fibre is coinciding with the longitudinal direction of the paper. One will furthermore be restricted to use cellulose as a base in the manufacturing though other materials could prove suitable.
The above problems have through the present invention been solved whereby a flexible process for the manufacturing of a mainly isometric thermosetting laminate has been achieved where the process easily can be adapted regarding cost efficiency, impact resistance, rigidity, density, moisture absorption, expansion, mould resistance and fire resistance. The invention relates to a process for the manufacturing of a decorative mainly isometric thermosetting laminate comprising an isometric core, a primary surface layer and optionally a secondary surface layer. The invention is characterised in that 85 parts by weight of preferably organic particles, which particles have an average particle size in the range of 5-3000 &mgr;m, preferably 5-2000 &mgr;m, are mixed with 15-85 parts by weight, preferably 22-37 parts by weight, of a thermosetting resin in the form of a powder which resin is selected from the group of phenol-formaldehyde resins, melamine-formaldehyde resins, urea-formaldehyde resins or mixtures thereof. The mixing takes place in for example an extruder where the mixture is kneaded powerfully so that friction heat is formed. It is also possible to use a calendar mill for the same purpose. The friction heat is not allowed to exceed 150° C., preferably below 110° C., most preferably below 90° C. The thermosetting resin is thereby bonding to or impregnating the particles by becoming soft. The particles that possibly are joined by the thermosetting resin are divided and an agglomerate of thermoplastic resin and particles is formed. The agglomerate has an average particle size of 200-3000 &mgr;m and a resin content of 10-50% by weight, preferably 20-30% by weight.
The particle/resin mixture is thereafter dried to a water content below 10% by weight, preferably below 5% by weight.
The dried particle/resin mixture is thereafter evenly distributed on a carrier, a pressing belt of a continuous laminate press or on a press plate of a discontinuous laminate press. The dried particle/resin mixture is thereafter continuously or discontinuously compressed at a temperature of 60-120° C., preferably 80-100° C. and a pressure of 15-400 bar, preferably 30-120 bar so that the particle/resin agglomerate flow out without completely curing the resin. A pre-fabricate to an isometric core is hereby obtained. The core pre-fabricate is then fed between the press belts of a continuous laminate press, or is placed on a press plate of a discontinuous laminate press, together with a primary surface layer which is provided with a decorative layer, and optionally a secondary layer and is thereafter continuously or discontinuously compressed at a temperature of 120-200° C., preferably 140-180° C. and a pressure of 15-300 bar, preferably 30-150 bar so that the resin cures, whereby a decorative thermosetting laminate provided with an isometric core is obtained.
According to another alternative the above achieved dried particle resin/mixture is evenly distributed on a carrier, a press belt of a continuous laminate press or on a discontinuously compressed at a temperature of 120-200° C., preferably 140-180° C. and a pressure of 15-300 bar, preferably 30-150 bar so that the resin cures, whereby an isometric core is formed. The core is provided with a primary surface layer and optionally a secondary surface layer in connection to or after the pressing.
A pressure in the range 15-70 bar is usually used in a continuous pressing process while a pressure in the range of 50-400 bar is used in discontinuous pressing.
The particles are suitably completely or partly constituting of wood parts or fruit parts from plants, whereby the wood parts for example include saw dust, wood powder or finely chopped straw while the fruit parts suitably consists of some kind of cereal in the form of flour, for example corn wheat or rice flour. The particles may also completely or partly consist of recycled material such as waste paper, cardboard or rejects from thermosetting laminate manufacturing. The particles may furthermore be completely or partly made of lime. The particles are thereby selected by the characteristics they will give the finished laminate. Mixtures of different particles will also give favourable characteristics. The particles are suitably dried to a water content of below 10% by weight, preferably below 6% by weight, before the mixing.
The dried particle/resin mixture is preferably distributed so that the difference in particle weight per area unit of the surface of the intended core doesn't exceed 10%, preferably below 3%. The particle/resin mixture is for example distributed on a press plate to a discontinuous multiple opening press. The press plate can be provided with a detachable frame which surrounds the prospective core. The frame might alternatively be attached to the press plate whereby the frame and the plate forms a tray. A second press plate with dimensions smaller than the inner dimensions of the frame is placed on top of the distributed particle/resin mixture in the alternatives where a frame is used. A number of press plates provided with frames and containing particle/resin mixture with a second press plate on top are placed on top of each other and are moved to the laminate press. The second press plate is cancelled in cases where a press plate without frame is used. The procedure otherwise corresponds to the above described procedure with a frame.
The dried particle/resin mixture can also be pressed in a continuous laminating procedure. The particle/resin mixture is then distributed on, for exampl
Andersson Thord
Persson Stefan
Rasmusson Dennis
Sjöstedt Börje
Decorative Surfaces Holding AB
Jackson Monique R.
Stevens Davis Miller & Mosher L.L.P.
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