U.S. patent application number 10/570951 was filed with the patent office on 2007-05-24 for decorative laminate and method for producing the same.
Invention is credited to Alois Gruber, Leonhard Schitter.
Application Number | 20070116927 10/570951 |
Document ID | / |
Family ID | 34229715 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070116927 |
Kind Code |
A1 |
Schitter; Leonhard ; et
al. |
May 24, 2007 |
Decorative laminate and method for producing the same
Abstract
The invention relates to a decorative laminate with an
abrasion-resistant surface coating for laminate floor boards or the
like, which is characterized in that the thermoset resin mass that
forms the resin impregnation of the decorative web and the
abrasion-resistant surface resin layer that is materially integral
with it with a closed surface is formed with a thermosettable
synthetic resin and conventional additives and/or adjuvants, the
synthetic resin mass as a component containing a mixture integrated
into the resin mass or such a compound of at least one wax or wax
blend based on a polyalkylene polymer and at least one polyvinyl
pyrrolidone, in that the particles of the abrasion-resistant hard
material in the surface layer are concentrated essentially only
directly bordering the decorative web surface and in the vicinity
thereof, and in that the covering density of the particles of
abrasive material located in the surface layer in the
same--proceeding from a high value directly on the decorative
web--toward the outer surface of the surface layer, following a
steep negative gradient, drops to a value of zero.
Inventors: |
Schitter; Leonhard;
(Hallwang, AT) ; Gruber; Alois; (Buermoos,
AT) |
Correspondence
Address: |
MILLEN, WHITE, ZELANO & BRANIGAN, P.C.
2200 CLARENDON BLVD.
SUITE 1400
ARLINGTON
VA
22201
US
|
Family ID: |
34229715 |
Appl. No.: |
10/570951 |
Filed: |
September 8, 2004 |
PCT Filed: |
September 8, 2004 |
PCT NO: |
PCT/AT04/00306 |
371 Date: |
December 6, 2006 |
Current U.S.
Class: |
428/143 |
Current CPC
Class: |
Y10T 428/24372 20150115;
B32B 2260/046 20130101; B32B 2317/12 20130101; B32B 27/20 20130101;
B32B 21/06 20130101; B32B 29/00 20130101; D21H 27/28 20130101; B44C
5/0476 20130101; B32B 2391/00 20130101; B32B 2419/04 20130101; D21H
17/51 20130101; B44C 5/043 20130101; B32B 2307/554 20130101; B32B
2260/026 20130101; D21H 17/67 20130101 |
Class at
Publication: |
428/143 |
International
Class: |
E01F 9/04 20060101
E01F009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2003 |
AT |
A 1407/2003 |
Claims
1. Decorative laminate with abrasion-resistant surface coating for
laminate bodies coated or to be coated therewith, especially
laminate floor boards or panels based on wood materials, the
laminate being formed with at least one layer of an outside fibrous
material web and/or paper web (decorative web) on the visible,
useful side, provided with a suitable decoration and impregnated
with a (partially) thermoset synthetic resin, which web is
impregnated and coated with a thermoset or partially thermoset mass
finished to be abrasion-resistant based on at least one
thermosettable synthetic resin from the group of melamine resins,
formaldehyde resins and urea resins, and furthermore a wax based on
a thermoplastic polymer, to which mass at least one further
additive and/or one further adjuvant has been added, in the
thermoset or partially thermoset resin mass of the decorative web
that forms the surface or wear layer on the decorative web,
particles of at least one abrasion-resistant hard material,
especially .alpha.-aluminum oxide and .alpha.-corundum and/or
tungsten carbide, being distributed, characterized in that the
thermoset or partially thermoset resin mass that forms the resin
impregnation of the body of the decorative web and the highly
abrasion-resistant surface resin layer with a closed or smooth
outer surface, which is applied in a one-step process, and which is
integral or materially integral with the web, is formed with at
least one of the aforementioned thermosettable synthetic resins and
the additives and/or adjuvants that are known in the art and that
are conventional for laminate impregnations and coatings, the
synthetic resin mass as a component important to improved useful
properties and to permanent freedom from cracking of the surface
layer containing a mixture integrated into the resin mass or such a
compound of at least one wax or wax blend based on a polyethylene,
polypropylene and/or polyamide polymer or copolymer and at least
one polyvinyl pyrrolidone, and the particles of the
abrasion-resistant hard material, especially Al.sub.2O.sub.3
particles or corundum particles and/or tungsten carbide particles,
in the surface layer are located essentially only directly on or
directly bordering the decorative web or on its visible side or
surface and in the immediate vicinity thereof and are concentrated
there, and the distribution or covering density of the particles of
abrasive material located in the surface layer of the decorative
laminate in the same--proceeding from a high value, especially
between 80% and 95%, directly on the decorative web and on its
visible side or surface and in the immediate vicinity
thereof--toward the outer surface of the surface layer, preferably
within a thickness range of the surface resin layer of from 0.05 to
0.15 mm, following a steep negative gradient, drops essentially to
a value of zero.
2. Decorative laminate according to claim 1, wherein the wax blend
in the compound in the (partially) set resin mass is a wax blend
based on micronized (thermoplastic) polymers based on ethylene from
the Poro Company, Salzburg, Austria, especially one with the
commercial designation "PORO 100. "
3. Decorative laminate according to claim 1, wherein the polyvinyl
pyrrolidone of the compound contained in the (partially) set resin
mass has a molecular weight in the range of from 25,000 to 750,000,
preferably from 100,000 to 500,000.
4. Decorative laminate according to claim 1, wherein the aluminum
oxide particles or corundum particles contained in the surface
layer of the laminate have a tabular form in significant portions,
especially at least 40%, preferably at least 80%, and their average
grain size is in the range from 10 to 100 .mu.m, especially from 10
to 50 .mu.m.
5. Decorative laminate according to claim 1, wherein in the surface
layer of the laminate, in addition to the abrasion-resistant hard
material particles, there are spheroidal silicate spherules,
preferably glass spherules, with diameters in the range of from 30
to 100 .mu.m.
6. Decorative laminate according to claim 1, wherein the
(partially) set resin mass that forms the impregnation of the
decorative web and its surface layer contains resin modifiers, such
an external flexibilizers, preferably sugar, and/or glycols, such
as diethylene glycol, and/or internal flexibilizers, such as
.epsilon.-caprolactam and/or p-toluene sulfonic acid amide, and/or
cross-linking regulators, preferably dicyanodiamide,
acetoguanamine, and/or benzoguanamine.
7. Decorative laminate according to claim 1, wherein the
(partially) set resin mass that forms the impregnation of the
decorative web and its surface layer additionally contains at least
one natural substance or substance identical to nature 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 xanthene, but
preferably locust bean gum flour and/or xanthene.
8. Decorative laminate according to claim 1, wherein the
quantitative portion of the wax or wax blend in the compound
contained in the (partially) set resin mass is 0.5 to 2.5% relative
respectively to the entire (partially) set resin mass without the
abrasion-resistant hard material particles.
9. Decorative laminate according to claim 2, wherein the
quantitative portion of the polyvinyl pyrrolidone(s) of the
compound contained in the (partially) set resin mass is 1.5 to 12%,
preferably 3 to 8%, relative respectively to the entire (partially)
set resin mass, but without the abrasion-resistant hard material
particles.
10. Process for producing decorative laminates with an
abrasion-resistant surface or wear layer for laminate bodies coated
therewith, especially floor boards or panels based on wood
materials, the laminate being formed with at least one layer of an
outside fibrous material web and/or paper web (decorative web) on
the visible, useful side, provided with a suitable decoration and
impregnated with a (partially) thermoset synthetic resin, which web
is impregnated and surface-coated with a thermoset mass finished to
be abrasion-resistant based on at least one thermosettable
synthetic resin, to which at least one thermoplastic polymer-based
wax and furthermore at least one additive or adjuvant is added, in
the (partially) thermoset synthetic resin mass of the decorative
web that forms the surface layer of the decorative web, particles
of at least one abrasion-resistant hard material, especially
.alpha.-aluminum oxide and .alpha.-corundum and/or tungsten carbide
being distributed, according to claim 1, wherein a fibrous material
web or paper web printed with the respectively intended decoration
is impregnated in a one-step process with a mass of a
thermosettable resin that contains conventional components as well
as further additives and/or adjuvants and abrasion-resistant hard
material particles, and is coated with simultaneous formation of a
surface or wear resin layer that forms a closed or smooth outer
surface, which is materially-integral or integral with the resin
impregnation of the decorative web, and within which the particles
of the abrasion-resistant hard material, especially Al.sub.2O.sub.3
particles or corundum particles and/or tungsten carbide particles,
settle essentially directly to and into the immediate vicinity of
the surface of the decorative web and collect there in a high
concentration and the distribution density of the particles of
abrasive material located in the surface layer of the decorative
layer in the same, proceeding from a high value directly to or on
the surface of the decorative web and in the immediate vicinity
thereof, toward the outer surface--following a steep negative
gradient--drops essentially to a value of zero, for impregnation
and coating of the fibrous material web or paper web, a resin mass
being used that as a component that is important--for improved
production and useful properties and for permanent freedom from
cracking of the surface layer of the laminate--contains a mixture
integrated into it or such a compound of a micronized wax or such a
wax blend based on a polyethylene, polypropylene and/or polyamide
polymer or copolymer and with at least one polyvinyl pyrrolidone,
and wherein after impregnation and surface coating of the
decorative web that takes place simultaneously with it, the
conventional (partial) curing of the decorative web or--after
appropriate moisture removal--with or without interposition of a
supporting web that is to be placed underneath the decorative
web--direct application of the coated decorative web impregnated
with the described resin mass to a wood material substrate in a
board or panel form, preferably to floor boards or panels, takes
place.
11. (canceled)
Description
[0001] 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, according to the preamble of
claim 1.
[0002] 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.
[0003] 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."
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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 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.
[0008] 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.
[0009] 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.
[0010] 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
A1. 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
desired in each case to the laminate and protect the chrome-plated
continuous belt itself.
[0011] 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.
[0012] Of course, the problem of cracking furthermore remains
unresolved by the use of structuring papers.
[0013] 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.
[0014] 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 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] DE 195 08 797 C1, in a process for producing a decorative
laminate paper, calls for a mixture to be produced from melamine
resin, .alpha.-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.
[0019] U.S. Pat. No. 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.
[0020] EP 472 036 A1 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 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.
[0021] Furthermore, EP 732 449 A1 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.
[0022] The processes described in the two patents U.S. Pat. No.
4,713,138 A and U.S. Pat. No. 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 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.
[0023] Regarding the aforementioned U.S. Pat. No. 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.
[0024] Addition of certain polyethylene waxes as lubricants in
resin compositions for producing laminates also follows from U.S.
Pat. No. 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.
[0025] U.S. Pat. No. 4,449,137 A and U.S. Pat. No. 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.
[0026] The use of polyethylene waxes in laminates, especially those
with overlay paper, follows furthermore from U.S. Pat. No.
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.
[0027] 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-B 1.
[0028] 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
completely precluded.
[0029] 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.
[0030] 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 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.
[0031] The subject matter of this invention is thus 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, of the
initially named type according to the preamble of claim 1.
[0032] The important features of the new laminate material are
summarized in the characterizing portion of claim 1.
[0033] 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 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.
[0034] 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.
[0035] 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. U.S. Pat. No.
5,496,387 A mentions such use of PVP 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.
[0036] 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 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.
[0037] Within the framework of the invention, a laminate whose
partially set resin impregnation and coating masses is formed with
a special wax blend in the compound according to claim 2 is
especially preferred.
[0038] 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.
[0039] 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.
[0040] 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 polyvinyl
pyrrolidone used together with the wax with the characteristics
named in claim 3 playing an important role. It is polymerized into
the resin and as a result of keto-enol 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.
[0041] 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 the corundum named in claim 4 is especially preferred.
[0042] 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 according to claim 5.
[0043] 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 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.
[0044] 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, which are named in claim 6, and furthermore also the
cross-linking agents named there, is advantageous.
[0045] In particular the sugars mentioned in this claim 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.
[0046] The p-toluene sulfonic acid amide furthermore named in claim
6 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.
[0047] 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 named in claim 7 can perform good additional
support services.
[0048] Within the framework of the resin masses used to obtain the
new decorative laminates that in fact remain permanently free of
cracks, favorable quantitative ratios of the wax blend and
polyvinyl pyrrolidone in the compound can be found in the two
claims 8 and 9.
[0049] A novel process for producing the new, cracking-free
laminates finished to be abrasion-resistant as defined initially
according to the preamble of claim 10 that comprises the features
and measures named in the characterizing portion of this claim
relates to another important subject of the invention.
[0050] Finally, within the framework of the invention, claim 11
names the resin masses that are to be more advantageously used and
that due to their properties with respect to improvement of
protection of pressing sheets and belts and suppression of cracking
contain the especially preferred components and additives named
there.
[0051] 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 1% 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)
[0052] 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 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 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.
[0053] 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
[0054] The following production steps were carried out in
succession, the initial materials used being explained below in
detail:
[0055] The following brief operating instructions were used; the
explanations of the product designations that appear here and
internal abbreviated designations likewise follow farther
below.
[0056] 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 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.
[0057] The application values of the described resin-abrasive
particle mixture were 70 g/m.sup.2 decorative paper with a final
weight of roughly 210-220 g/m.sup.2. 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%.
[0058] 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.degree. C. and a pressure of 20 bar.
[0059] More detailed explanations of the components of the resin
impregnation and surface coating mass produced as just described
follow:
"Premix" Production Instructions:
[0060] At 20.degree. C. in a Drais mixer, 4.5 kg of locust bean gum
is stirred 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.degree. 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 cooling continues
until 20.degree. C. is reached. The solution obtained in this way
can be processed for up to roughly 1 week.
[0061] 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.
[0062] 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.
[0063] "Silane Z 6020" (Dow Chemicals, USA) is an amino silane.
[0064] 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 grain size in .mu.m.
[0065] 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 grain 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.
[0066] The "Hypersal VXT 3797" (Solutia Company, Germany) used in
the resin impregnation and coating mass is a commercial wetting
agent.
[0067] 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.
[0068] 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.
[0069] 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).
[0070] 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.
[0071] 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.degree. C., even after 24 hours no cracks form, which
is also the case at a still higher temperature, specifically at
120.degree. C., likewise after 24 hours.
[0072] 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.
[0073] 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.
* * * * *