U.S. patent application number 09/980419 was filed with the patent office on 2003-07-24 for paper for producing panels and paper-making method.
Invention is credited to Dohring, Dieter, Stutz, Josef.
Application Number | 20030138600 09/980419 |
Document ID | / |
Family ID | 8164360 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030138600 |
Kind Code |
A1 |
Dohring, Dieter ; et
al. |
July 24, 2003 |
Paper for producing panels and paper-making method
Abstract
The invention relates to a method for making paper, which is
characterized in that the paper is impregnated with an
acrylate-containing dispersion or mixture and the
acrylate-containing dispersion or mixture is forced into the paper.
The paper so produced can be used to produce boards, especially
floor panels even if said panels have only a mass per unit area of
15 to 35 g/m.sup.2, thereby reducing the costs of production of
such panels.
Inventors: |
Dohring, Dieter;
(Lampertswalde, DE) ; Stutz, Josef; (Nicosia,
CY) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
8164360 |
Appl. No.: |
09/980419 |
Filed: |
March 1, 2002 |
PCT Filed: |
March 30, 2001 |
PCT NO: |
PCT/EP01/03661 |
Current U.S.
Class: |
428/143 ;
162/135; 162/158; 162/164.6; 162/169; 162/181.2; 162/181.6;
162/183; 428/341 |
Current CPC
Class: |
B32B 17/02 20130101;
Y10T 428/24372 20150115; B32B 27/34 20130101; B32B 27/36 20130101;
B32B 7/12 20130101; D21H 17/37 20130101; D21H 27/28 20130101; B32B
2260/028 20130101; B32B 2419/04 20130101; B32B 27/10 20130101; B32B
2260/046 20130101; B32B 29/06 20130101; Y10T 428/273 20150115; B44C
5/0469 20130101; D21H 27/22 20130101; B32B 2307/4026 20130101; B32B
2367/00 20130101; B32B 2377/00 20130101 |
Class at
Publication: |
428/143 ;
162/158; 162/169; 162/135; 162/164.6; 162/181.2; 162/181.6;
162/183; 428/341 |
International
Class: |
D21H 017/03; D21H
017/66; D21H 017/56; D21H 019/00 |
Claims
1. Method of manufacturing a paper, characterised in that the paper
is impregnated with an acrylate-containing dispersion or
mixture.
2. Method according to claim 1, characterised in that the
acrylate-containing dispersion or mixture is pressed into the
paper.
3. Method according to one of the foregoing claims, characterised
in that the acrylate-containing dispersion or mixture contains
water, in which acrylate particles are dispersed, and preferably
resin, in particular an amino resin.
4. Method according to one of the foregoing claims, characterised
in that colour pigments such as aluminium silicate, calcium
carbonate, TiO.sub.2, Al.sub.2O.sub.3 or magnesium silicate are
added to the acrylate-containing mixture or dispersion.
5. Method according to one of the foregoing claims, characterised
in that the paper is conducted through rollers which are pressed
together, the acrylate-containing dispersion or mixture being
continuously applied to at least one roller and preferably
distributed on the roller with a doctor blade.
6. Method according to one of the foregoing claims, characterised
in that the paper is de-aerated before the acrylate-containing
dispersion or mixture is pressed into it and for this purpose in
particular is steeped on one side in the acrylate-containing
dispersion or mixture.
7. Method according to one of the foregoing claims, characterised
in that the paper weight amounts to at least 15 grams per square
metre and/or does not exceed an upper limit of 60 g/m.sup.2,
preferably of 40 g/m.sup.2.
8. Method of manufacturing a tile, in which paper is impregnated in
accordance with one of the foregoing claims and a laminate system
which comprises the paper and a carrier plate is pressed with the
application of heat.
9. Method of manufacturing a tile according to the preceding claim,
in which the laminate system includes a decorated or patterned
paper onto which a mixture of amino resin and abrasion-resistant
particles is applied, preferably by spraying, before the pressing
step.
10. Method of manufacturing a tile according to the preceding
claim, in which fibres and/or spheres made of polyester, polyamide
or glass are applied to the abrasion-resistant particles before the
pressing step.
11. Paper characterised by acrylate which is present at least
predominantly in the interior of the paper.
12. Paper according to the preceding article claim, produced in
accordance with one of the foregoing method claims.
13. Paper according to one of the preceding article claims,
characterised by a paper weight of 15 to 60 g/m.sup.2, preferably
up to 40 g/m.sup.2.
14. Paper according to one of the preceding article claims,
characterised by colour pigments which are present in the interior
of the paper.
15. Paper according to one of the preceding article claims,
characterised in that it displays no delamination on the conclusion
of the performance of a standardised steam test, in which the paper
is exposed to steam for two hours.
16. Tile, in which the paper according to one of the preceding
article claims is used.
17. Tile according to the preceding claim, in which a surface of
the tile is provided with abrasion-resistant particles such as
corundum or silicon carbide particles and preferably with fibres
and/or spheres made of polyester, polyamide or glass.
18. Tile according to one of the two preceding claims,
characterised in that the tile is a flooring panel.
Description
[0001] The invention relates to a method of making a paper for
tiles as well as a paper produced according to the method. The
invention relates further to panels, in the manufacture of which
the paper is used, as well as an associated method of
manufacture.
[0002] A tile according the invention can be further processed to
form a panel. A panel, for example known from the publication EP
090 6994 A1 is as a rule an elongated thin tile, which can be
joined laterally, i.e. at its longer and shorter sides, to further
panels, for example through tongues and grooves. Panels joined
together in this way are used in particular as floor coverings or
as wall coverings.
[0003] A tile is produced according to the state of the art,
amongst other ways, as follows. A paper impregnated with resin,
which is called "counter-pull paper" is prepared. A carrier plate
is placed over the counter-pull paper. A further resin-impregnated
paper is arranged above the plate. The two papers are pressed
together with the plate at temperatures around 200.degree. C. to
form the tile.
[0004] The paper which is arranged above the plate is generally
provided with decoration or a pattern which determines the
appearance of the tile as viewed from above.
[0005] Particles of SiC or grains of corundum can be rolled onto
the side having the decoration before the pressing step, in order
to obtain a tile having a particularly resistant surface. In
addition a layer of cellulose is applied to the side having the SiC
particles or the corundum.
[0006] The paper with the printed decoration is called patterned
paper. The cellulose layer is identified as "overlay".
[0007] The patterned paper is arranged with the overlay above the
carrier plate. The patterned paper is then present between the
carrier plate and the overlay. Subsequently the counter-pull paper,
carrier plate, patterned paper and overlay are pressed together at
a temperature within the range of 200.degree. C. When the laminate
system is taken from the press the result is a tile which has on
one face a pattern with a particularly hard surface.
[0008] Panels having the desired dimensions and with lateral
tongues and grooves can be produced from the tiles by sawing and
milling. The panels are used in particular as floor coverings.
[0009] The carrier plate gives the panel mechanical stability. The
decoration on the patterned paper determines the appearance of the
subsequent wall or floor surface. The layer of corundum or
SiC.sub.2 provides good resistance to abrasion and the like. The
counter-pull paper opposes distortion of the carrier plate. The
overlay protects one surface of the press from the otherwise
projecting hard grains of SiC.sub.2 or corundum grains.
[0010] The papers used in the state of the art generally have a
weight above 70 g per square metre. If the above-mentioned value is
not reached, the paper is not sufficiently resistant to tearing in
order to be able to handle the mechanical loads imposed during
production of the tiles. The paper is furthermore so thin that it
is too transparent to be capable of being used as patterned
paper.
[0011] It is true that a high weight of paper has the drawback that
the consumption of material is correspondingly high. In this
connection it is not only the actual weight of the paper that has
to be taken into account but also the resin with which the paper is
impregnated in order to be able to start the production of a tile.
The higher the weight of the paper, the more resin is required for
impregnating the paper. The cost of manufacture of the paper is
correspondingly increased.
[0012] In order to obtain a thin paper which is resistant to
tearing, a synthetic resin mixture is painted onto pre-impregnated
paper. This synthetic resin mixture does not penetrate the paper
but represents an additional layer which is next to the paper. The
underside of the paper is as a rule provided with a self-adhesive
layer. The resulting paper is known under the definition "finish
film" and can be stuck onto plates or tiles.
[0013] An aim of the invention is the manufacture and treatment of
a paper which is substantially resistant to tearing and in
appearance from the optical point of view more colour-covering in
comparison with the state of the art stated in the introduction. An
aim of the invention is the production and treatment of economical
tiles or plates in which the paper according to the invention is
employed.
[0014] According to the method the paper is impregnated with an
acrylate-containing dispersion or mixture. In comparison to an
impregnation which is performed only with a resin, the paper
impregnated in accordance with the method is substantially more
resistant to tearing. The paper can have a weight per unit area of
for example 30 g/m.sup.2 and despite this is capable of handling
the mechanical loads imposed in the production of a tile in the
manner stated in the introduction. In fact tests have shown that
the mechanical strength of the paper according to the invention is
so high that the speed of impregnation in the resin-impregnation
stage provided for production of the tiles can be raised from the
current 40 to 60 m/min to 120 m/min. Correspondingly small--in
comparison with the state of the art cited in the introduction--is
the consumption of the paper material and impregnating medium.
[0015] The acrylate-containing dispersion or mixture contains water
in which the acrylate particles are dispersed. Suitable acrylates
are therefore those which have good dispersing qualities.
[0016] In a preferred embodiment of the invention the
acrylate-containing dispersion or mixture is pressed into the paper
for the purpose of impregnation. For this purpose the paper is for
example conducted through rollers which are pressed together. The
acrylate-containing dispersion or mixture is continuously applied
to one roller. When the paper leaves the rollers the dispersion or
the mixture has been pressed into the paper.
[0017] It is important that the dispersed acrylate or the mixture
is not simply painted onto the paper as then the dispersed acrylate
or the mixture would not have penetrated the paper or would have
penetrated it insufficiently. By the pressing step it is ensured
that the dispersion or the mixture penetrates into the paper and so
the paper achieves the desired improved strength. Furthermore the
paper is then provided with the dispersion or the mixture in such a
way that during the further treatment to produce a tile
additionally introduced resin does not penetrate the paper or at
least does so only to a relatively minimum extent.
[0018] In a preferred embodiment of the method the paper is a
de-aerated before the acrylate-containing dispersion or mixture is
pressed in for impregnating. For this purpose the paper is steeped
in particular on one side with the acrylate-containing dispersion
or mixture. In this way the air present in the paper is replaced by
the dispersion or the mixture.
[0019] In one embodiment of the invention a resin-acrylate mixture
or dispersion, in particular an amino-resin-acrylate mixture is
used for the impregnation. With such a mixture or dispersion
weights of paper to a lower limit of about 15 g per square metre
can be achieved. Papers produced in such a way are, with a suitable
mixture ratio, sufficiently resistant to tearing in order to be
able to be employed in the production of tiles for example as a
printed base paper. It can be left to the expert in the art to find
out suitable mixture ratios by conducting a few tests.
[0020] The paper should not exceed an upper limit of 60 g/m.sup.2,
preferably 40 g/m.sup.2, in order to achieve sufficiently high cost
advantages. Optimum values currently lie between 25 and 35
g/m.sup.2.
[0021] In a preferred embodiment of the invention colour pigments,
for example aluminium silicate, calcium carbonate, TiO.sub.2,
Al.sub.2O.sub.3 or magnesium silicate are added to the mixture. In
this way the translucency is greatly reduced.
[0022] The paper impregnated with the use of colour pigments can be
very well introduced as the patterned paper because of its opacity
to light and high covering ability.
[0023] In one preferred embodiment of the invention the
acrylate-containing dispersion or mixture is pressed into the
de-aerated paper from both sides. It has been found that the paper
is then filled out from the middle with the acrylate-containing
dispersion or mixture. Such impregnated paper is suitable in a
particularly good manner for the production of the tiles mentioned
in the introduction.
[0024] The paper produced in accordance with the method is
distinguished from the finish films in a particular by the fact
that the acrylate is present in the paper and not simply wholly or
largely on the surface. The resistance to delamination is
substantially greater than in the finish films mentioned in the
introduction, as steam tests indicate. In the steam test paper is
exposed to steam for two hours. In conventional papers delamination
takes place, in contrast to that according to the invention.
[0025] The paper which is claimed can then be introduced as
counter-pull paper or patterned paper in the production of a tile
in the manner stated in the introduction.
[0026] In one embodiment of the method patterned paper is provided
on one side not only with abrasion-resistant particles such as
silicon carbide or corundum particles, but in addition with fibres
and/or spheres. The fibres or spheres, in contrast to the
abrasion-resistant particles, comprise soft materials such as
polyester, polyamide or glass. The fibres and/or spheres protect a
pressing belt from damage during the pressing of a laminate system
which includes the patterned paper. It is possible to dispense with
the provision of an overlay above a layer of abrasion-resistant
particles. In this way it is possible to save around one third of
the costs which are involved in the impregnation of the patterned
paper as well as the application of a layer with the overlay in the
state of the art.
[0027] The impregnation of the patterned paper includes in
particular the following steps. The patterned paper is steeped in
resin, in particular amino resin and abrasion-resistant particles
are applied to one side having the pattern. Subsequently the fibres
and/or spheres are applied to this. The result is achieved that the
fibres and/spheres form a protective covering layer over the
abrasion-resistant particles in a press.
[0028] Before the application and of the fibres or spheres the
process can be performed as follows.
[0029] A layer of an amino resin with abrasion-resistant particles
in a special dispersion is sprayed onto the patterned paper in
addition, whereby the final weight per unit area--in relation to
the dry weight of the raw paper--amounts to 100% to 250%. Spraying
on the dispersion has been found to be advantageous, as can be seen
from the publication WO 00/44984. It is subsequently advantageous
to secure the sprayed-on dispersion by smoothing and uniform
distribution using rollers.
[0030] The above-mentioned dispersion preferably comprises 100
parts of an amino resin, 20 to 95 parts of abrasive, and therefore
abrasion-resistant, material, 0.5 to 2.5 parts of a silane adhesion
promoter, 5 to 25 parts of a flow-promoting agent, 0.1 to 0.4 parts
of a cross-linking medium, 0.05 to 0.4 parts of a separating medium
and of an amino resin hardener.
[0031] As the amino resin in particular a melamine resin is used,
as flow-promoting agent for example polyglycol ether,
.epsilon.-caprolactam or butanediol and an abrasive substance, for
example silicon carbide having an average particle size of 60 to
160 .mu.m or aluminium oxide in the form of corundum or out of the
melt with a particle size of 60 to 160 .mu.m. Also any desired
mixture of silicon carbide and aluminium oxide can be provided.
[0032] The subsequent application of fibres and/or spheres
preferably takes place as follows. A mixture of a resin with the
fibres or the spheres is produced and the mixture is applied to the
patterned paper in the manner described above. The provision of a
mixture further improves the protection in a press, as then also
the additional resin assists in the protection.
[0033] The thicknesses of the fibres or the diameters of the
spheres are preferably chosen so that during the pressing of a
corresponding laminate system for producing tiles the corundum or
silicon carbide particles are kept away from the corresponding
surface of the press. In this way damage resulting from hard
silicon carbide or corundum particles is avoided.
[0034] The average diameter of the spheres is preferably greater
than the average diameter of the fibres when both fibres and
spheres are used. The spheres then ensure the desired protective
spacing between the abrasion-resistant particles and for example a
press belt. The fibres in particular ensure securing of the resin
and oppose the formation of tears.
[0035] The respective active surface of a press is protected by the
invention in an improved and particularly economical manner from
damage by abrasion-resistant particles, for example hard corundum
or silicon carbide particles. The maintenance of the active
surfaces in a press--for example a press belt of a so-called double
belt laminating installation--takes place at correspondingly longer
intervals of time, so that costs and production down-times
associated with the maintenance schedules are reduced. Overall,
significant cost savings are obtained.
[0036] Typical fibre lengths amount to at least 0.5 mm, but
preferably at least a few millimetres, for example 2 mm, 4 mm or 5
mm. The longer the fibre, the better it is able to protect the
surface of a tile from the formation of tears. An upper limit on
the fibre length is provided in particular by the associated rise
in viscosity. In the case of a resin-fibre mixture having too high
a viscosity it can no longer be worked. The diameter of the fibres
lies for example at a few tens of .mu.m or even 100 .mu.m or
more.
[0037] A typical diameter of the spheres lies between 30 and 200
.mu.m. Thereby on the one hand the desired spacing is achieved
between the corundum or silicone carbide particles and a
corresponding surface in a press. On the other hand the spheres are
small enough not to be perceived by the naked eye.
[0038] The optical impression is not adversely affected by the
fibres or spheres if they have the stated sizes and are embedded in
the resin.
[0039] The fibres or spheres are preferably made of polyester,
polyamide or glass. These materials meet the characteristics which
are needed during production as well as after manufacture. During
production they are sufficiently stable in their behaviour.
Polyesters, polyamides or glass are sufficiently soft materials in
the sense of the invention in order to avoid damage to a pressing
device. In a finished tile a sufficient transparency is given by
the stated materials so that the optical impression of the pattern
is not adversely affected. The materials preferably make possible
relatively large workable fibre lengths which significantly exceed
the lengths of fibres made of cellulose employed according to the
invention. The rise in viscosity with increasing fibre length of
synthetic polymers such as polyester fibres, polyamide fibres or
glass fibres is in fact small in comparison with the increasing
fibre lengths of cellulose fibres.
[0040] Accordingly sufficient fibres can be introduced whereby a
press is better protected from damage in comparison with short
cellulose fibres. This is particularly the case when the fibres are
present in the form of a fleece, as set out further below.
[0041] The fibres and/or spheres can be made of various materials.
Thus for example polyester fibres, polyamide fibres and glass
fibres can be employed equally well.
[0042] Fibres are preferred to spheres as in this way the formation
of tears in the surface is avoided. Spheres are therefore
preferably used as a back-up. Accordingly, as spheres preferably
use is made of hollow balls of glass for reinforcing the protective
action, the balls in particular having a diameter of 30 to 200
.mu.m for the reasons mentioned above.
[0043] The patterned paper claimed preferably has a solids content
weight of 25 to 35 g/m.sup.2. The fibre content then amounts in
particular to 5 to 100 g/m.sup.2. In addition for the reinforcement
preferably up to 80 g/m.sup.2 of spheres, in particular microglass
hollow spheres, are provided.
[0044] In a further preferred embodiment the fibres are present in
the form of a fleece. The fibres are so-to-speak woven into one
another. A fleece reinforces and protects in a particularly
effective manner. The danger of the formation of tears is further
reduced and thereby the danger of damage to the respective engaged
surface. In the application of a resin-fibre mixture the resin is a
particularly well secured by the fleece during pressing. The resin
then assists particularly well in the protection in a pressing
device.
[0045] In the case where a fleece is provided, the protective
action is further improved by the introduction of spheres.
[0046] The invention is further explained in conjunction with the
following example:
[0047] Paper having a weight of 30 g/m.sup.2 is moistened on one
side with an acrylate-containing dispersion. The dispersion
contains the following components: 770 g of a commercially
available acrylate dispersion having a solids content of 50% by
weight, 225 g of a commercially available urea formaldehyde
impregnating resin having a solids content of 50% by weight as well
as 5 g of a urea resin hardener. The mixture is finely agitated and
brought into use.
[0048] The moistened paper is conducted through mutually
pressed-together rollers. The rollers have a surface made of hard
rubber. The stated dispersion is uniformly applied to the rollers
and distributed uniformly on the surface with the aid of doctor
blades.
[0049] The acrylate-containing mixture is present in the interior
of the paper which leaves the rollers. This paper is dried and can
subsequently be employed for the production of tiles.
[0050] For the production of patterned or decorated paper colour
pigments in addition, and in fact 250 g titanium dioxide slurry
with a solids content of 70% by weight and 50 g magnesium silicate,
are added to the dispersion. The paper is then at least as opaque
as a conventionally produced paper having a weight of 70
g/m.sup.2.
[0051] The tiles produced using the papers in the manner stated in
the introduction were tested in accordance with EN 438. In this
test all standard norm values were fully met. In particular the
steam test was successfully completed.
[0052] The decorated or patterned paper is preferably used in the
manufacture of a tile as follows. A mixture of amino resin and
corundum particles is sprayed uniformly on the decorated surface.
15 g/m.sup.2 of corundum is thereby introduced. The now wet paper
web is conducted to a suspension drier. A temperature of
170.degree. C. prevails in the drier. Onto the decorated upper
surface of the web which has been thus treated there is applied in
a metered manner a mixture of a commercially available amino resin
and polyester fibres. The solids content of the applied material
amounts to 70 g/m.sup.2. The fibre content in the mixture is 30% by
weight. The average length of the fibres is 5 mm. The mean diameter
is 80 .mu.m. Subsequently a second drying step is carried out at
160.degree. C., until the residual moisture content amounts to 7%.
The decorated or patterned paper impregnated in this way is
employed further in the manner stated in the introduction, in order
to form a tile and in particular to form a panel for flooring.
Likewise paper in accordance with the invention is used as the
counter-pull paper. 150 g/m.sup.2 of resin can be saved in this way
in comparison with the state of the art. However the paper
according to the invention also offers advantages over the state of
the art even when he paper weight is very high, amounting for
example to 150 g/m.sup.2.
* * * * *