Note: Descriptions are shown in the official language in which they were submitted.
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Decorative Laminate and Method for Producing the Same
This invention relates to a decorative laminate with an abrasion-resistant
surface coating for
laminate bodies that have been or are to be coated with it, especially
laminate floor boards or panels
based on wood materials..
Furthermore, this invention relates to the production of the new decorative
laminate that has
an abrasion-resistant surface coating and that is intended for floor boards,
panels, and the like.
The wide popularity of laminate floors according to EN 13329 is due to, among
others, the
especially good capacity of these floor coverings to be cleaned. This in turn
is a result of the
absence of pores of the surface or the outside of its surface coating, which
is generally labelled with
the technical expression "closed."
Actually "closed" surfaces were made possible in the past by use of so-called
"classic"
overlays. Such classic overlays consist of thin, especially transparent
special papers that are
impregnated with duroplastic resins, such as especially melamine resins. These
papers are located
on or over the surface film and wear film of the decorative web and are
pressed with the latter with
the decorative web and ultimately with the substrate based on a wood-based
material into the
laminate intended for laying of floors and are of decisive importance for ease
of cleaning of
laminate floors. By using classical overlay films, especially in the form of
overlay paper webs,
however, the gloss of the surface or surface layer of the decorative film is
inevitably reduced
because as a result of the presence of the fibers in the overlay film, an
inevitable and clearly
perceptible haziness of lines, patterns, designs, etc., and a certain
attenuation and clouding of the
color and graphic impression of the surface decoration occur.
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If, however, the classic overlay that is present generally in the form of a
coating resin-
impregnated overlay paper is omitted, which has been attempted again and again
for some time, and
which will be considered in more detail below, "open pores" of the surface
layer arise that
ultimately lead to irreversible soiling of the laminate surface that in any
case significantly degrades
the optical effect, which is especially a problem in laminate floors and could
not be avoided in the
past.
Another completely unacceptable consequence of omitting the overlay consists
in the
danger that in the production of laminates for various purposes, and
especially for floors, the
surfaces of the pressing sheets used in the so-called short contact process or
of the pressing belts
used in continuous laminate production are damaged or destroyed. For this
reason, in the past in
daily operating practice with currently conventional high production rates, it
was in fact not
possible to carry out production of highly abrasion-resistant laminates
undisrupted over time
intervals that are as long as possible without using classic overlays that had
proven themselves in
practice, as known in the art. In particular, in spite of various approaches
to solving this serious
problem that arises in abrasion-resistant laminate surfaces without overlay
films, it has not been
possible to date to fully protect the surface-chrome-plated, highly sensitive
pressing sheets or
continuous pressing belts of the production lines against the aforementioned
mechanical damage or
possibly even against destruction by the particles of abrasive substance
protruding from the surface
layer of decorative laminates that have been finished to be abrasion-
resistant.
The fact that numerous attempts have been made to produce surface layers of
laminates that
are lastingly abrasion-resistant for their use and application is not
inherently significant since the
abrasion-resistance values required according to EN 13329 can be achieved to a
comparable degree
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with decorative films without overlay papers when they have been finished only
with particles of
abrasive substances that ensure the required wear resistance. For this reason,
therefore, the use of
classic overlays in the production of laminates for floors is not necessary to
achieve the abrasive
resistance values required by EN 13329. However, the classic overlays, as
stated above, are of quite
decisive importance for the protection of pressing sheets or continuous
pressing belts against the
harmful effect of the particles of abrasive substances contained in the
surface layer of the decorative
laminate to be produced - for the most part they are corundum particles.
Almost all attempts to date to produce decorative films finished to be more
highly abrasion-
resistant by means of continuous pressing belts or pressing sheets without
using classical overlays
have failed due to the surface damage or even destruction of the chrome
plating of the indicated
belts or sheets and/or of the pressing structures impressed on them, caused by
the medium of
abrasive substance that is present in the surface layer and that increases the
abrasion resistance.
Another problem of surface coatings without overlay paper that likewise has
not been
solved to date is that the fibers of the overlay papers reliably prevent later
crack formation in the
setting hard layer of resin precondensates, especially melamine formaldehyde
precondensates, but
that in practice all attempts to bypass the classic overlays with respect to
the desired absence of
cracking have not led to a permanent solution that has in fact been
satisfactory to date.
One approach that may be technologically feasible to dispensing with the
protective overlay
foils or films that are provided for protection of the pressing sheets or
belts in the production of
laminates, e.g., for floors, would be to use so-called structuring papers, as
disclosed in, e.g., DE 101
24 710 Al. The latter would replace the correspondingly structured surfaces of
the pressing sheets
or continuous belts in laminate floor production and in their place impart the
surface structure
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desired in each case to the laminate and protect the chrome-plated continuous
belt itself
As practice has shown, however, the use of structuring papers is associated
with a major
decrease of the quality of the laminates obtained using them, which relates
not only to the
structuring itself As a result of the inhibition of heat transfer from the
pressing sheet or from the
continuous belt of the continuous press that is caused by the intermediate
paper layer, the
production rate is greatly reduced or else the quality of the laminate surface
is greatly degraded as
the feed rate remains the same.
Of course, the problem of cracking furthermore remains unresolved by the use
of
structuring papers.
A large number of processes for producing laminates provided with a surface
coating to
which particles of abrasive substances have been applied, without overlay
paper, film or foil have
become known in the art that differ from one another both with respect to the
composition of the
resin mass and process details in their production in many cases only by
relatively minor differences
or details.
Essentially, the laminate base production process consists in that a fibrous
material web,
especially a paper web provided with some printed decoration, is impregnated
with a
thermosettable resin, more preferably with a possibly modified melamine,
formaldehyde and/or
urea resin, and optionally directly afterwards or even later - optionally with
the interposition of a
possibly multilayer paper web likewise impregnated with a thermosettable resin
- as a decorative
laminate web with an abrasion-resistant surface layer is bonded to a substrate
such as especially a
wood chipboard or fiberboard under the action of heat and pressure. Currently,
the technique
predominates of subjecting the resin of the decorative laminate web and
possibly present core layer
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web(s) in each case only to partial setting and of bonding the laminate that
has been preset in this
way under the action of heat and pressure by means of the resin that is then
cured completely
ultimately to the wood material substrate provided in each case.
As relates to the prior art in the field of producing decorative laminates
with an abrasion-
resistant surface coating without an overlay film, a large number of proposals
have been advanced
for this purpose and in part also implemented, which will be briefly, by no
means even only
approximately completely, discussed below.
Thus, e.g., DE 28 58 182 C2 discloses a decorative web for producing
decorative boards
with high abrasion-resistance in which there is a thin, abrasion-resistant
coating that is located over
the decoration and that contains an abrasion-resistant mineral and furthermore
a binder for the
latter, and the binder is to be compatible with the resin mass used and
permeable to this resin.
The production of a decorative laminate can proceed, as follows from, e.g., DE
2 800 762,
such that first an aqueous suspension of aluminum oxide particles stabilized
with microcrystalline
cellulose is applied to the unimpregnated decorative web, after which drying
takes place. Then,
impregnation with a melamine-formaldehyde resin solution is undertaken, and
finally this
decorative wear web is hot-pressed with a core web and the substrate board. In
such a decorative
web, however, the abrasion-resistant fine mineral particles are displaced by
the microcrystalline
cellulose to the outside or surface, the surface resin layer, and then in part
protrude out of it and thus
cause unwanted roughness of this surface, and, as is much more serious,
increased wear of the
sheets of the pressing tools used in the production of the laminates as a
result of inevitable damage
to the sheet surface. In addition, according to this document, it is necessary
to apply the abrasion-
resistant final coating in a separate procedure, which in any case increases
production costs.
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DE 195 08 797 Cl, in a process for producing a decorative laminate paper,
calls for a
mixture to be produced from melamine resin, a-cellulose, corundum as the
hardening material,
additives and adjuvants as well as water and for it to be applied to the
visible side of a decorative
paper sheet that has already been impregnated with resin in the previous
process step, but that has
been dried to a residual moisture content of a few percent, after which drying
takes place. This type
of process is designed to yield the advantage that the corundum particles on
their extreme tops and
edges that may still be "protruding" out of the desired wear layer are to be
covered with a
continuous resin film, which, however, cannot be fully done in practice. The
jacketing of the hard
material particles desired there at their extreme points, however, was not
achieved in practice, with
which damage to the pressing sheets or plates in hot-pressing of decorative
laminates could never
be completely prevented.
US 3 135 643 A discloses a laminate production method according to which the
decorative
web is first impregnated with a resin suspension, and the latter is coated
still wet with a dispersion
comprising melamine resin, quartz, cellulose, cellulose derivatives and water.
The complete
jacketing of the particles of the abrasive substance with resin that is
essential for protecting the
pressing plates and belts cannot be ensured with this method either, as shown.
EP 472 036 Al discloses a two-stage "wet-in-wet" process for producing
abrasion-resistant
decorative laminates, according to which it is provided that the decorative
web itself in any case
within the framework of the first impregnation with resin is impregnated with
a melamine resin
dispersion containing particles of abrasive material up to a percentage
desired in each case. The
disadvantage of this type of addition of particles of abrasive material
directly onto and into the
paper web of the decorative laminate is that within the decorative cover
layer, the distribution of
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particles is not homogeneous, so that in this first production step, local
stiffening occurs. In a
second step, then the resin dispersion likewise containing the abrasive
substances is applied. The
aforementioned zones of stiffening of the decorative web as a result of
penetration of abrasive
particles into the latter then in any case disrupt the flexibility of the
decorative web in the actual
coating process.
Furthermore, EP 732 449 Al should be mentioned, according to which abrasion-
resistant
laminates are obtained by a decorative paper sheet that is to be coated or a
web of this type first
being impregnated with resin, after which drying to certain residual moisture
content values takes
place, after which then a resin mass containing the particles of abrasive
substance, cellulose, resin
and additives is applied to the impregnation layer that has been partially
dried in this way. The
disadvantage of this coating method is that genuine bonding of the
impregnation resin bodies to the
surface coating resin bodies that contain the particles of abrasive substance,
which bonds can be
mechanically highly loaded, is not achieved.
The processes described in the two patents US 4,713,138 A and US 4,971,855 A
for
producing laminates with abrasion-resistant surface coatings are likewise
subject to the
disadvantages that are inevitable in all known one-step impregnation coatings
with particles of
abrasive material that are known to date. According to the technology
described there, a mixture
containing particles of abrasive material, cellulose and the respective resin
is applied to the paper to
be impregnated, without pretreatment. As a result of the wicking and
absorption action of the
decorative paper that is present "unimpregnated," as a result of its fiber
inhomogeneities,
nonuniform wicking rates at different locations on the paper surface occur, by
which more particles
of abrasive materials are sucked up and bonded wherever faster wicking occurs,
and zones of higher
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surface coverage by these particles than in other areas of the surfaces and
thus the aforementioned
zonal stiffening occur. The ordered mutual alignment of the particles that
otherwise occurs is also
disrupted by the described wicking action, so that in zones of increased
wicking action, for
example, nests of particles form that significantly disrupt the homogeneity of
the properties of the
abrasion-resistant surface of the laminates.
Regarding the aforementioned US 4,713,138, it should furthermore be stated
that the
microcrystalline cellulose there has the purpose of producing a uniform
distribution of particles of
abrasive material in the surface resin layer, which leads, however, to corners
or edges of the
particles that are located near the outer surface of the surface layer
protruding beyond it and thus
being able to damage the surface of the pressing sheets. This US-A also
discloses use of
polyethylene wax as a surface-active component that increases slip.
Addition of certain polyethylene waxes as lubricants in resin compositions for
producing
laminates also follows from US 4,741,946 A; in any case the abrasion values
according to EN 438
of laminates produced according to this US-A are in the region of 150
revolutions and in no case
reach those values that high-quality floor laminates must reach and that are
supposed to be roughly
at least 10,000 revolutions.
US 4,449,137 A and US 4,567,087 A disclose a laminate in which finely
dispersed
polyethylene wax is incorporated in the vicinity of its surface or actually on
its surface. The
objective there is specifically that the wax "blooms" during hot-pressing,
therefore migrates to the
surface. This is achieved there in that the polyethylene wax is applied in its
own working step and
not as a component integrated into the impregnation and coating resin mass.
The use of polyethylene waxes in laminates, especially those with overlay
paper, follows
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furthermore from US 4,139,671 A, in any case there being no particles of
abrasive material there in
the surface layer, and, moreover, with respect to the use of laminates there
for bowling alleys a high
sliding action being desirable, therefore exactly the opposite of those
properties that a floor laminate
must have.
Last but not least, a process developed by the applicant himself for producing
highly
abrasion-resistant decorative laminates according to EP 875 399 B1 should be
mentioned; its
significant feature consists in that a layer containing particles of abrasive
material composed of a
mixture or dispersion of a thermosettable resin is applied to a decorative web
that has been
impregnated with resin beforehand, and the component of the resin decisive for
the properties of the
decorative laminate is formed by use of at least one natural substance that
contains polysaccharides.
In practice, it has been shown that by using these natural substances in the
resin mass in and of
itself, certain improvements compared to the prior art can be achieved,
especially with respect to the
especially desirable protection of the pressing sheets and pressing belts, in
that, however, sporadic
damage to the surfaces of the pressing belts or pressing sheets cannot be
completely eliminated
even by the additives provided according to this EP-B1.
In spite of the host of known suggestions for problem-free production of
laminates with a
surface finished to be abrasion-resistant, there furthermore remains the
challenge of developing a
process for producing decorative laminates with abrasion-resistant surface
finishing that have a
high-quality surface coating that is in fact free of particles of abrasive
material protruding out of the
surface layer without a protective resin coating, so that the aforementioned
unacceptable damage to
the pressing sheets or pressing belts that disrupt production, and possibly
even lead to production
stoppages and in this way cause high costs by "protruding" particles of
abrasive material is almost
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completely precluded.
In view of the difficulties in the production of overlay-free laminates that
to date have not
been resolved to a satisfactory degree under any circumstances, the object of
the invention is to
devise a decorative laminate or substrate body coated with the latter for the
most varied
applications, but especially for floor boards, panels and the like, which on
the visible side that is
used has a surface coating that meets high or extremely high requirements in
its clarity and
decorative reproduction quality and that can be controlled in its wear
properties to the highest
abrasion values. Nevertheless, both with respect to the products to be used
and also the production
process, especially relative to protection of the pressing sheets and belts
that is as complete as
possible, the production process is to be fault-proof and economical, and is
to take place within the
framework of production methods that have been proven in the past in practice,
and is to be able to
be implemented on existing systems without extensive re-arrangements and
modifications at
essentially the same production rates.
It was found in the course of thorough tests that specific incorporation of
quite specific
substance mixtures into the resin matrix that ultimately after curing is to
contain the particles of
hard material that ensure the surface wear resistance of the laminates leads
to unexpectedly high-
quality, optically particular laminates that have especially high service
quality and wearing
properties matched to the use that is desired in each case, with
simultaneously optimum
incorporation of particles of abrasive material. In this connection, not only
do no possible adverse
effects on the production process occur due to, for example, expected problems
with respect to
thermal stability of the adhesive and bonding properties under prolonged
action of heat, and with
respect to mold or press separation properties, but especially also not with
respect to damage to
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pressing sheets and belts by particles of abrasive material that must be
unconditionally
prevented. Rather, a compact and cost-minimized manner of production is made
possible
that leads to decorative laminate products with permanently cracking-
resistant, highly
abrasion-resistant surface coatings, so-called "liquid overlay" coatings.
According to one aspect of the present invention, there is provided a
decorative
laminate with abrasion-resistant surface coating , the laminate having at
least one decorative
web layer of an outside fibrous material web and/or paper web on a visible
side, and
provided with a decoration, wherein the at least one decorative web layer is
impregnated and
coated in a one-step process with a thermoset synthetic mass, the thermoset
synthetic mass
being finished to be abrasion-resistant, wherein particles of at least one-
abrasion resistant
material are distributed in the thermoset synthetic mass, the thermoset
synthetic resin mass
being integral with the at least one decorative web layer and having a closed
or smooth outer
surface, and
wherein the thermoset synthetic mass comprises at least one thermosettable
synthetic
resin from the group of melamine resins, formaldehyde resins and urea resins;
a wax blend based on a polyethylene, polypropylene and/or polyamide polymer or
copolymer, and at least one cross-linked polyvinyl pyrrolide; and
at least one further additive and/or one further adjuvant,
wherein particles of the at least one-abrasion resistant material in the
thermoset
synthetic mass are located only directly on or directly bordering the at least
one decorative
web layer, and wherein the particles of the at least one-abrasion resistant
material are a-
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aluminum oxide and a-corundum and/or tungsten carbide, and a distribution or
covering density of
the particles of the at least one-abrasion resistant material located in the
thermoset synthetic mass
proceeds from having the distribution or covering density of between 80% and
95% directly on the
visible side of the at least one decorative web layer and follows a negative
gradient toward the outer
surface thereof where the distribution or covering density drops to a value of
zero, the outer surface
having a thickness range of from 0.05 to 0.15 mm.
The simultaneous presence of wax(es) and polyvinyl pyrrolidone(s) in the
impregnation and
coating resin mass that leads to unexpected new laminate properties is
critical to the invention.
They are the result of the arrangement of the abrasion-resistant particles of
hard material distributed
in the surface and wear resin layer that could not be specifically achieved in
the past such that the
particles settle in the inherently very thin surface layer to the actual
decorative web surface, collect
and concentrate there and in the immediate vicinity thereof. Only the
following simplified
explanation of this unexpected phenomenon can be tentatively made: The
particles of abrasive
material that are present in relatively high concentrations in the
impregnation coating mass as a
result of the action of the compound of the wax blend and polyvinyl
pyrrolidone in this mass
essentially no longer develop buoyancy, they therefore do not float, and thus
provision has been
made as a result for their no longer protruding out of the surface layer or
wear layer, therefore no
longer above the boundary between the surface resin layer and air space, for
which, as was the case
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in the past, even if the protruding areas, tops, or the like were covered with
a thin film of this
hardened resin mass, there was essentially no protection against displacement
of this thin film in the
production process, and when plates are used, rapid abrasion of this film
occurs, so that exposure of
tops, edges, corners or the like of the particles of abrasive material that
often protrude only in the
micron or submicron range occurs, which, in spite of these inherently small
dimensions, causes
uncontrolled damage that could only be eliminated with relatively high costs
on the surfaces of the
pressure sheets or pressing belts, and surfaces that cannot be cleaned.
What furthermore occurs, surprisingly enough, is the fact that in spite of one-
step
application and impregnation, the disruptive formation of local or zonal
"nests" or "clumps" of
abrasive materials that was described above within the framework of the
explanation of the prior
art, as a result of topographically different wicking properties of the
decorative web that can
ultimately lead to disruptive local stiffening thereof, can no longer be
observed, which likewise
should be attributed to a significant degree to the novel wax blend-PVP
compound that has been
incorporated or integrated into the resin mass.
For the sake of completeness at this point, it is mentioned that the use of
polyvinyl
pyrrolidone(s) (PVP) in resins for laminates for pedestrian surfaces,
therefore for abrasion-resistant
floorboards or the like, was not known in the past. US 5,496,387 A mentions
such use of P'VP only
for resins as binders for abrasive material particles in grinding materials,
and according to this
document, the sedimentation rate of the particles will be reduced, therefore
their settling to a
substrate is prevented.
With respect to the wax blend in the compound, the ratio of polyethylene
and/or
polypropylene -- that is/are present in addition to other components and/or
modifiers and/or
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additives or the like --to polyamide can vary within wide limits of between
0.1 to 10 and
100 to 0.1. The ratio is advantageously in the range of between 50 to 100 and
100 to 50.
Within the framework of the invention, a laminate whose partially set resin
impregnation and coating masses is formed, wherein the wax blend contains a
micronized thermoplastic polymer based on ethylene.
It has been found that the compound and especially the wax blend in the
compound in the resin mass in the laminates according to the invention leads
to a
completely new wood-like feel or touch that causes a feeling of warmth, when
walking
on it with bare feet, that is unknown in previously known laminate floors.
Polyamides in the compound that has been incorporated into the resin mass or
in
its wax components support not only the described new feel, but furthermore
contribute
to increased resistance of the coating, especially also with respect to the
prevention of
cracking.
Both the prevention of cracking that was not achieved with any overlay film-
free
surface coating to date and that can be achieved for the first time according
to the
invention and the novel concentration of particles of abrasive material that
occurs directly
on or in the vicinity of the decorative web surface, therefore in the depth of
the surface or
wear resin layer of the new laminates, should be essentially due to the new
compound in
the set mass of the impregnation and coating resin, the cross linked polyvinyl
pyrrolidone
used together with the wax play an important role. The one cross-linked
polyvinyl
pyrrolide has a molecular weight in a range of from 25,000 to 750,000, and
preferably
from 100,000 to 500,000. It is polymerized into the resin and as a result of
keto-enol
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tautometry of the OH groups has an action that modifies the resin in the
direction of long-
term freedom from cracking and that greatly surpasses the action of the
celluloses used to
date with conventional molecular weight ranges.
According to another aspect of the present invention, there is provided a
decorative
laminate wherein the particles of the at least one-abrasion resistant material
have a
tabular form and comprise at least 40% of the thermoset synthetic mass, and
preferably at
least 80%, and the average grain size of the particles of the at least one-
abrasion resistant
material is in a range of from 10 to 100 jim, and especially from 10 to 50 m.
With respect to the type of particles of abrasive material or hard material
that is to
be especially preferred for preventing the "floating" effect of the particles
of abrasive
material, the use of corundum particles or aluminum oxide particles is
especially
preferred.
One measure that unexpectedly supports the specific "settling effect" of the
particles of abrasive material that has been desired for a long time and that
has now been
achieved according to the invention surprisingly consists in adding spherules
of silicate
material, especially glass, to the resin mass that contains the abrasive
material, with
diameters in a range of from 30 to 100 rim.
The action of the glass spherules can be explained, for example, by the fact
that
they ensure, so to speak, a thickness of the surface or wear layer resin film
between one
another that corresponds to their diameter, which means effective material
coverage for
the particles of abrasive material that as a result of using the above-
described wax-PVP
compound have the inherently unexpected tendency that is used anyway according
to the
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invention to settle within the surface layer toward the decorative web, by
which the
above-explained protrusion of regions of particles of abrasive material that
lie only in the
micron range over the surface level of the surface layer is prevented.
In order both to ensure the absence of cracks in the finished laminates on the
surface over long time intervals and to further support protection of the
pressing sheets
and belts in their production of laminates, the presence of internal
flexibilizing agents
that therefore influence the molecular structure within the resin mass, and/or
external
flexibilizing agents that influence the macroscopically detectable properties
thereof, such
as external flexibilizers, preferably sugar, and/or glycols, such as
diethylene glycol,
and/or internal flexibilizers, such as c-caprolactam and/or p-toluene sulfonic
acide amine,
and/or cross-linking regulators, preferably dicyanodiamide, acetoguanamine,
and/or
benzoguanamine is advantageous.
In particular the sugars mentioned can play an important part within the
impregnation and coating resin mass, specifically because they have 8 free OH
groups
per molecule that are heavily incorporated into the resulting combination of
molecules
when the laminating resin, such as, e.g., melamine resin, condenses, and can
modify
them in the direction in which a possible tendency to residual cracking that
is
exceptionally low anyway is extremely effectively suppressed.
According to another aspect of the present invention, there is provided a
decorative laminate wherein the thermoset synthetic mass contains one or more
resin
modifiers and/or cross-linking regulators.
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The p-toluene sulfonic acid amide furthermore forms an advantageous additional
modifier for the condensation process in the formation of melamine resin,
which can be
attributed to its tautomer properties that lead to the fact that chain breaks
occur within the
framework of resin condensation over a long condensation period, and thus the
formation
of large molecular chains that, as has been found, cause and intensify
cracking to a
significant degree is greatly reduced.
The thermoset synthetic mass additionally contains at least one natural
substance
or substance identical to the at least one natural substance selected from the
group of guar
seed flour, flour(s) of Jerusalem artichoke, chicory and/or dahlia, locust
bean gum flour,
cesa gum, guar gum, gum arabic, carrageen, tragacanth gum, agar agar and/or
xanthenes.
In the meaning of the aforementioned statements, with respect to preventing
damage to the pressing sheets and belts of the production lines, on the one
hand, and the
prevention of cracking in new floor panels or laminates for floor panels in
use, the natural
substances can perform good additional support services.
A quantitative portion of the wax blend contained in the thermoset synthetic
mass
is 0.5 to 2.5% relative respectively to an entirety of the thermoset synthetic
mass without
the at least one-abrasion resistant material.
Further, a quantitative portion of the at least one cross-linked polyvinyl
pyrrolide
contained in the thermoset synthetic resin mass is 1.5 to 12% (and preferably
3% to 8%)
relative respectively to an entirety of the thermoset synthetic mass without
the at least
one-abrasion resistant material.
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A novel process for producing the new, cracking-free laminates finished to be
abrasion-resistant relates to another important subject of the invention.
For a rough assessment, the range of quantitative contents of the primary and
secondary components of the decorative web impregnation and wear layer coating
resin
masses for floor boards, preferably used within the framework of the
invention, is
mentioned below:
0.5 to I% of silane(s),
2.0 to 4% of xanthene,
15 to 30%, especially 20 to 25%, of abrasive or hard material particles,
0.5 to 3% of polyvinyl pyrrolidone(s) (PVP)
0.2 to 1.5% of wax blend: polyethylene wax basis (e.g., from the PORO,
Pointner und
Rothschadl Company, Salzburg)
3 to 10% of sugar (saccharose)
0.3 to 1% of p-toluene sulfonic acid amide
0.1 to 0.5% of hardener
remainder to 100% of melamine resin (emulsion or solution)
By omitting the overlay film that reduced cracking in the past and presumably
due to the composition that has been changed or modified by the new wax-blend-
PVP
compound in the resin masses, significant beneficial changes of a sensory type
in
walking barefoot on the new laminate arise when it is used for floors or floor
boards: the
sensory impression of the "cold" of the melamine resin surface that is typical
for existing
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CA 02538166 2012-08-14
laminate floors known in the art no longer occurs in floors with the "liquid
overlays"
according to the invention that contain the above-described compound in the
resin mass.
The sensory impression of the floor on the user can be best paraphrased with
the
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CA 02538166 2006-03-08
expression "warm underfoot." Until now, in most cases, carpets were generally
laid on laminate
floors with panels or boards produced using conventional technology, at least
in the seating area, in
order to prevent the aforementioned "cold" of known laminates from becoming
noticeable.
When using the laminates according to the invention with the overlay-free
surface or wear
layer formed with the wax blend-PVP compound, it has therefore become possible
for the first time
to produce laminate floors that are warm underfoot according to EN 13329. By
eliminating the
overlay paper, a clear optical impression of the decoration of the new
laminates that are intended
especially for floors that had never been achieved in the past is attained.
Essentially, in this
invention, the effect that could not be achieved to date with any overlay-free
laminate, that is, the
effect of suppression of cracking that has been achieved in fact for the first
time over the service life
of the floor in the surface and wear resin layer, plays a quite important
role.
Example:
The following production steps were carried out in succession, the initial
materials used
being explained below in detail:
The following brief operating instructions were used; the explanations of the
product
designations that appear here and internal abbreviated designations likewise
follow farther below.
Add 2.5 L of silanes Z-6020 (silane) to a mixer half-filled with "Formulation
38" emulsion,
stir at 300 rpm for 5 minutes, add 10 L of "Premix," add 10 L of xanthene
solution, increase rpm to
500 rpm, mix in 50 kg of "ZWSK 220" corundum and 50 kg of "ZWSK 180" corundum,
add 5 kg
of polyvinyl pyrrolidone (PVP), admix 1.2 kg of wax blend, 600 ml of Vxt 3797
Hypersal as a
wetting agent, 29 kg of granulated sugar, 3 kg of paratoluene sulfonic acid
amide and 1.5 L of
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CA 02538166 2006-03-08
hardener H 806. Finally, add "Formulation 38" emulsion to make 420 L, reset
rpm to 300 rpm, and
mix completely within about 5 minutes. A pourable mass with a gelling time of
3 minutes and 40
seconds is obtained.
The application values of the described resin-abrasive particle mixture were
70 g/m2
decorative paper with a final weight of roughly 210-220 g/m2. The resulting
resin-impregnated,
surface-coated decorative web with abrasive particles applied was brought to a
residual moisture
content of from 6% to 6.5%. There would be a risk of agglutination of the
resin film at a residual
moisture content of more than 7%.
The decorative web obtained after partial setting was applied directly on a
"Hymmen" unit
at 37 m/minute of feed to floor panel boards made of fine fiber wood material
and was hot-pressed
at 240 C and a pressure of 20 bar.
More detailed explanations of the components of the resin impregnation and
surface coating
mass produced as just described follow:
"Premix" Prod ucti oi in stru &ions =
At 20 C in a Drais mixer, 4.5 kg of locust bean gum is stifled into 150 L of
VE water at 500
rpm, and after the cooling system is turned off, the mixer rpm is increased to
900 rpm. The solution
becomes more and more viscous after roughly 1.5 hours and heats up as a result
of the friction heat
generated by the rotor-stator stirring tool up to boiling. After roughly 1
hour of cooking time, the
mixer rpm is reduced to 300 rpm, the cooling is turned on, 150 L of VE water
is added, and within
roughly 2 hours, cooling to roughly 40 C takes place. After adding 7.5 kg of
hardener 528 (BASF)
and a subsequent 10 minutes of mixing, then another 120 L of VE water is
added, and finally
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CA 02538166 2006-03-08
cooling continues until 20 C is reached. The solution obtained in this way can
be processed for up
to roughly 1 week.
The "xanthene solution" that is used is a 1% solution of xanthene in water to
which 0.3%
formaldehyde is added to stabilize the solution.
The mixture according to "Formulation 38" is a melamine resin emulsion with
250 kg of
50% melamine resin, 4.8 kg of etherified melamine resin as the modifier, 0.4
kg of Alton MF 179
(WIZ Company, Italy) as the wetting and separating agent, 0.7 kg of Alton 1263
(WIZ Company,
Italy) as a transparency enhancer, 0.3 kg of hardener 529 (BASF, Germany) and
2.0 kg of hardener
806 (KS Deurotex) based on diethanolamine.
"Silane Z 6020" (Dow Chemicals, USA) is an amino silane.
The "ZWSK corundum" used as the abrasive substance (Triebacher Company,
Villach,
Austria) bears this designation due to the special manner of its production,
the attached numbers
220 and 180 designating the average gain size in i_tm.
This "wax blend" is produced as follows: The important components intended for
this
purpose, e.g., based on polyethylene and polyethylene derivative
thermoplastics, or, generally
speaking, polyalkylene or polyalkylene derivative thermoplastics, are cast
into blocks, which are
crushed after cooling, and starting with a certain size are ground or
micronized in a jet mill. Each of
the components is brought to the grain sizes desired in each case, e.g., by
screening, classifying or
the like, and in each case, e.g., two or more different gain size fractions of
the different materials
are mixed with one another in a corresponding ratio to one another. Screening
characteristics and
the component mixing ratios are known to the manufacturer.
The "Hypersal VXT 3797" (Solutia Company, Germany) used in the resin
impregnation and
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CA 02538166 2006-03-08
coating mass is a commercial wetting agent.
The polyvinyl pyrrolidones (PVP) used here, generally called "cross-linked
polyvinyl
pyrrolidones" (BASF, Germany) have the commercial names "Luvicross" and
"Luvicross M" and
contain up to 6.0% of water, 11.0 to 12.8% of nitrogen, 0.5% of ash and less
than 50 mg/kg of
heavy metals. They are supplied in powder form. Their molecular weight can
only be given as an
order of magnitude.
The p-toluene sulfonic acid amide that can be used within the framework of the
invention
and the example is known as a chain stopper and can, as has been found,
contribute to a certain
extent to preventing the above-described, unwanted cracking in the overlay
film-free laminate
surface layer.
The tendency to cracking that could not be completely managed in the past and
that has
already been addressed several times can be further restrained especially
effectively by the
commercial sugar (saccharose) that is intended as the other component that can
be more preferably
used in the resin coating mass (also other disaccharides and oligosaccharides
can be used).
The new floor laminates produced on the basis of the aforementioned data are
characterized
by highly wear-resistant surface films. They can be easily produced within
conventional laminate
pressing times and under the conditions that are otherwise common in laminate
production.
Floor panels that have been hot pressed with a deep-structured decorative
sheet based on the
previous example show outstanding quality: the degree of closing of the
surface and coating resin
film is outstanding. In a "vapor test," no bubbles form and graying does not
occur either. For curing
in a drying oven at 70 and 100 C, even after 24 hours no cracks form, which is
also the case at a
still higher temperature, specifically at 120 C, likewise after 24 hours.
CA 02538166 2006-03-08
When testing the laminate surface by coloring it with graphite, an abrasive
agent grain that
penetrates the outer surface of the resin coating cannot be detected. The
abrasion test yielded
outstanding values of abrasion resistance up to the highest abrasion class,
AC5 according to EN 13
29.
Last but not least, the completely unexpected touch or feel of the products
according to the
invention that is conspicuously pleasant compared to previously known laminate
floors, specifically
a new type of transfer of a feeling of warmth when walking barefoot on the
floor prepared with
panels produced using the new resin impregnation and coating mass that is
comparable to roughly
the feeling of walking on a waxed natural wood parquet floor should be
especially emphasized.
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