Method for Producing Panels and Panel Produced Using the Method
Specification
Method for producing panels and panel produced using the method
The invention relates to a method for producing panels which are cut out of a large format
support board with a core of derived timber product.
EP 1 454 763 A2 discloses a method for finishing a wooden board or a board of derived
timber product, especially MDF or HDF board with a top and a bottom, in which first of all a
sealing layer of melamine resin is applied to the top of the board, a decoration is imprinted onto the
sealing layer and then a protective layer of melamine resin is applied to the decoration. Then the
structure of the board is compressed under the action of temperature until the protective layer and
the sealing layer bond are connected to one another with the inclusion of the imprinted decoration.
DE 195 32 819 Al discloses a method for producing a board of derived timber product with
an optically configurable surface in which a base dye, sealing, a print base and a decorative print are
applied in succession to the board of derived timber product. The print base is built up out of a base
tint or base coat of lacquer sealing and a surface lacquer. By means of engraving cylinders, a
decorative print is imprinted on the print base for example in two-color printing. Finally, a
multilayer acrylate UV lacquer which can be cured by means of UV light can be applied to this
print.
DE 197 51 115 Al discloses a method for coating of a panel in which at least one colored

layer is applied to the surface, by means of a printing method, especially by means of screen
printing. In this case the surface can be untreated, ground or pretreated, especially lacquered. Finally
the applied colored layer can be covered by a coating with varnish.
In the use of direct printing technology, therefore direct imprinting of the individual layers
on the support board, as a result compared to conventionally produced panels the thickness of the
finished laminate panels is reduced by omitting the paper layers. This leads to problems in assembly
line production when the large-format coated boards are then divided to produce the panels. To
ensure that individual panels do not drop out due to insufficient thickness from DIN 13329, high
quality assurance must be pursued; this on the one hand slows down production, and on the other
hand also increases production costs. Ultimately irritation among dealers and/or end consumers
occurs since the stack height of directly coated boards deviates visibly from conventionally coated
boards.
In known board production, conventionally HDF boards are used as support boards whose
surface is ground off by roughly 0.3 mm. On the top and the bottom of the support board a press
skin is formed which is also called a press patina or rotting layer. The press skin is formed in the
molding of the fiber cake and is produced by a hot surface of the pressure plates or belts of the
press. The press skin has a thickness of roughly 0.3 mm. Since the press skin is completely ground
off and roughly 0.1 mm of the core material is ground off for reducing the peak to valley height on
the surface of the support board before further coating, the boards must be made thicker by a
corresponding grinding additive; this adversely affects production costs. In order to manufacture a
standard floor laminate which has been produced by means of direct printing technology with a
thickness of 6 mm, the support board must have at least a thickness of 6.1 mm.

The press skin must be ground off because the action of heat in its region in hot pressing is
so high that the adhesive sets too quickly, by which glue bridges partially break and which make the
applied layer sensitive. This breaking of the glue bridges makes finished panels susceptible to
raising of the decorative and wearproof layers which have been applied to the support board. This
raising is called delamination; it can occur under normal loading and can be of a change in
magnitude which is typical of derived timber products as a result of climatic fluctuations.
There is therefore a great demand for wearproof laminate panels which are within the
thickness tolerance in the aforementioned standard. Furthermore there is a demand for a resource-
saving method for production, in which extra costs from additional method steps and/or due to
additional materials are largely avoided.
Proceeding from this problem formulation the initially described method for producing
panels, especially floor panels, will be improved.
To solve this problem the method is characterized by the following steps:
a) making available a large-format, press blank support board of derived timber product
which at least on its top has a press skin which has been formed in its production,
b) grinding some of the press skin off the top of the support board,
c) applying a base coat of a liquid resin based on melamine to the top of the support board,
the resin diffusing at least in part into the upper edge layer of the support board and penetrating and
coating the remaining area of the press skin at least in part,
d) drying the base coat,
e) applying a primer to the base coat,
f) drying the primer,

g) applying at least one water-based lacquer with dye pigments added for producing a
decoration,
h) drying the decoration,
i) applying a seal of at least one melamine-based resin with wear resistant particles and
cellulose fibers added,
j) drying the seal,
k) applying a base coat of a melamine-based liquid resin to the bottom of the support board,
the resin diffusing at least in part into the lower edge layer of the support board,
1) drying the base coat,
m) applying a contacting layer to the bottom of the support board,
n) molding the laminar structure under the action of pressure and temperature,
o) dividing the support board into panels of the desired width and length,
p) attaching connecting means and interlocking elements to opposing side edges for glueless
joining and interlocking of several panels into a composite floor which has been laid floating.
This method can save almost 5% of material, by which wood, glue, and portions of the
energy necessary for processing are saved. A standard 6 mm laminate panel can be produced from a
support board which is 5.8 mm thick. In a conventional production method the support board must
have a thickness of 6.1 mm.
Because the support board can be made thinner, the speed of the hot press and thus also its
yield (amount/unit of time) rise. Since the press skin is not completely ground off, not only is
handling time eliminated, which reduces production time, but also accruing costs for the grinding
belts are less. Since the layer of maximum raw thickness is almost preserved, the hot pressing can
be done with less pressure and/or with a higher speed. The adjustment window for hot pressing for
optimization of yield consequently becomes greater.
The penetration of resin into the upper layer of the support board on the one hand
compensates for the properties of the remaining press skin and at the same time forms a good
substructure for a decoration and a wearproof layer. In practice it has been shown that the danger of
delamination in floor panels which have been produced as claimed in the invention is low. The
quality was significantly improved.
Preferably the support board is an MDF, HDF or particle board.
The thickness of the support board preferably has a thickness of 5.8 mm and the press skin
has especially preferably a thickness of roughly 0.2 mm.
Preferably the press skin on the top of the support board is ground off by roughly 0.1 mm.
In this way it is possible for the base coat to penetrate through the press skin to a depth of roughly
0.1 mm.
The wear resistant particles are preferably corundum particles in the sealing layer.
After dividing, a plurality of panels can be packaged into a bundle.
A floor panel with a core of derived timber product, especially of MDF, HDF or chips is
characterized by the following features:
a) a top, a bottom and two pairs of opposite side edges,
b) the top and the bottom of the core have a press skin which has formed during molding,
c) the press skin on the top is thinner than the press skin on the bottom,
d) on the top of the core a base layer, a primer layer, at least one decorative layer and one
wearproof layer are applied,
e) a base layer and a contacting layer layer are applied to the bottom of the core,
f) the base layer has penetrated at least partially into the press skin on the top.
The base layer consists preferably of a melamine resin. The press skin on the top is roughly
0.1 mm thinner than on the bottom; this is preferably set by grinding off. The remaining thickness
of the press skin on the top is preferably 0.1 mm.
The wearproof layer in addition to the cellulose fibers as wear resistant particles has
preferably corundum particles.
The method as claimed in the invention will be explained below by way of example for a 6
mm floor laminate which satisfies DIN 13329.
First of all, a large-format, press blank support board of MDF, HDF or chip material with a
thickness of roughly 5.8 mm is made available. The support board on its top and its bottom is
provided with a press skin which has formed as a result of the hot press sheets during molding of
the fiber cake or particle cake. On the top of the support board the press skin is ground off first of
all by roughly 0.1 mm. Then the ground surface is primed with a melamine-based liquid resin. The
resin diffuses with its curable components at least partially into the upper edge layer and penetrates
the remaining region of the press skin by roughly 0.1 mm. This coats the press skin.
Then a drying process is carried out. A primer layer is applied to the dried base coat and
then dried. At least one water- based lacquer with dye pigments added for producing a decoration is
applied to the dry primer layer. The decoration can be uni-colors, wood grain, a tile mirror or a
fantasy decoration. Natural stone decorations are conceivable. After the applied decorative layer has
been dried, sealing with at least one resin to which wear resistant particles and cellulose fibers have
been added is applied. The resin is based on melamine. Then the applied seal is dried and then the
bottom of the support board is primed with a melamine-based liquid resin, the resin diffusing at
least in part into the lower edge layer and optionally the lower press skin. The base coat is then
completely dried and a liquid synthetic resin layer is painted onto the bottom of the support board as
a contacting layer. Then this laminar structure is molded under the action of pressure and
temperature.
The large-format support board which has been finished in this way is then cut into panels
of the desired size. Then the opposite side edges of the divided panels with the joining means and
interlocking elements corresponding to one another are profiled so that several identically made
panels can be joined to one another and can be interlocked to one another in order to produce a
composite floor which is laid floating.
A plurality of divided panels is packaged in the conventional manner into a bundle and if
necessary warehoused.
The drawing shows an extract of a raw density profile of an HDF board for use for a floor
coating. The region labeled 1 is the region which has been ground off in conventional boards. In
this connection it is the so-called rotting layer (press skin) which has been completely ground off.
The region labeled 2 is the region which is ground off the press skin as claimed in the invention in
order to grind the top of the support board flat (leveling) because the top is not completely flat due
to the press tolerance. The region labeled 3 is the region which is coated by applying the base coat
and by penetration of the resin into this layer. In the diagram the raw density is given in kg/m3 and
the board thickness is given in mm. It is clearly recognizable that the raw density within the press
skin rises quickly into a region above 1000 kg/m3 and then drops again in the core toward the core
middle.

We claim:
1. Method for producing panels with the following steps:
a) making available a large-format, press blank support board of derived timber product
which at least on its top has a press skin which has been formed in its production,
b) grinding some of the press skin off the top of the support board,
c) applying a base coat of a liquid resin based on melamine to the top of the support board,
the resin diffusing at least in part into the upper edge layer of the support board and penetrating and
coating the remaining area of the press skin at least in part,
d) drying the base coat,
e) applying a primer to the base coat,
f) drying the primer,
g) applying at least one water-based lacquer with dye pigments added for producing a
decoration,
h) drying the decoration,
i) applying a seal of at least one melamine-based resin with wear resistant particles and
cellulose fibers added,
j) drying the seal,
k) applying a base coat of a melamine-based liquid resin to the bottom of the support board,
the resin diffusing at least in part into the lower edge layer of the support board,
l) drying the base coat,
m) applying a contacting layer to the bottom of the support board,

n) molding the laminar structure under the action of pressure and temperature,
o) dividing the support board into panels of the desired width and length,
p) attaching connecting means and interlocking elements to opposing side edges for glueless
joining and interlocking of several panels into a composite floor which has been laid floating.
2. Method as claimed in Claim 1, wherein the support board is an MDF, HDF or particle
board.
3. Method as claimed in one of Claims 1 or 2, wherein the press skin has a thickness of
roughly 0.2 mm.
4. Method as claimed in one of Claims 1 to 3, wherein the press skin is ground off by
roughly 0.1 mm.
5. Method as claimed in one of the preceding claims, wherein the base coat penetrates the
press skin to a depth of 0.1 mm.
6. Method as claimed in one of the preceding claims, wherein the wear resistant particles are
corundum particles.
7. Method as claimed in one of the preceding claims, wherein a plurality of panels are
packaged into a bundle.
8. Panel with a compressed core of derived timber product, especially of MDF, HDF or
particles with the following features:
a) a top, a bottom and two pairs of opposite side edges,
b) the top and the bottom of the core have a press skin which has formed during molding,
c) the press skin on the top is thinner than the press skin on the bottom,
d) on the top of the core a base layer, a primer layer, at least one decorative layer and one
wearproof layer are applied,
e) a base layer and a contacting layer layer are applied to the bottom of the core,
f) the base layer has penetrated at least partially into the press skin on the top.
9. Panel as claimed in Claim 8, wherein the base layer consists of a melamine resin.
10. Panel as claimed in Claim 8, wherein the press skin on the top is roughly 0.1 mm
thinner than on the bottom.
11. Panel as claimed in one of Claims 8 to 10, wherein the press skin on the top is at least
partially ground off.
12. Panel as claimed in Claim 11, wherein the press skin has a thickness of roughly 0.1 mm.
13. Panel as claimed in Claim 8, wherein the wearproof layer has cellulose fibers and wear
resistant particles, preferably corundum particles.

The invention relates to a method for producing panels,
characterized by the following steps: a) providing a large-
format, press blank particle board made of wood material
comprising a press skin created during production at least on
the top side thereof; b) grinding off a part of the press skin
from the top side of the particle board; c) applying a base coat
made of a liquid melamine-based resin to the top side of the
particle board, wherein the resin diffuses at least partially
into the top edge layer of the particle board, and at least
penetrates and treats the remaining area of the press skin; d)
drying the base coat; e) applying a primer over the base coat;
f) drying the primer; g) applying at least one water-based paint
enriched by pigments for generating a decoration; h) drying the
decoration; i) applying a seal made of at least one melamine-
based resin enriched with wear-resistant particles and cellulose
fibers; j) drying the seal; k) applying a base coast made of a
liquid melamine-based resin to the bottom side of the particle
board, wherein the resin diffuses at least partially into the
bottom edge layer of the particle board; l) drying the base
coat; m) applying a counterpart to the bottom of the particle
board; n) pressing the layer construction under the effect of
pressure and temperature; o) cutting the particle board into
panels of the desired width and length; p) applying binding
agents and locking elements to opposite side edges for binding
and locking a plurality of panels into a floating laid composite
floor.