Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1049714 K-2285
REMOVABLE PAPER
This invention relates to paper for wallpaper and posters, which
can readily be removed when desired from the wall or other surface to
which it has been applied.
It is often desirable, or even necessary, to remove a sheet of
paper, which has been stuck on by means of a water-soluble adhesive,
for example a pasted-on wallpaper or a poster, from the surface after
several days, weeks or years. As is known, this work is difficult,
time-consuming and produces dirt. Normally the paper to be removed
is wetted and after some time removed from the underlying surface with
a painter's trowel or a similar device. In doing this floors and clothing,
in particular carpeted floors, are frequently soiled. This method of
operation is also not possible if the sheet-like material which has been
stuck on is water-repellent. Today, however, wallpapers are frequently
; -- washable or 100% washable. For these reasons there is a need for wall-
paper and also poster material which can be completely removed in a
simple manner from the papered wall or other papered surfaces even if
the paper is not wetted through with water. -
It has been proposed to stick onto a wall which is to be wall-
papered a lining paper which is composed of paper which is provided on
one side with an adhesive-repellent finish, or to line the wall with -
layers of foamed polystyrene. In both cases the result is that the wall-
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paper which is stuck on can be later removed from the wall,if necessary,
without difficulties. These methods have the disadvantage that in addi- ~-
tion to the actual wallpapering it is necessary to pretreat the wall,
which increases the cost of papering. The same applies to the other
proposed method of painting the wall to be wallpapered with an emui-
sion or dispersion which has the property of forming a coating from -
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lQ49714
which a wallpaper which has been stuck on also can be easily removed
later. Also known are the so-called splittable paper wallpapers, which
are composed of two layers of paper loosely adhering together and
therefore split into two layers when removed from the wall, so that the
layer with the printet wallpaper pattern is removed and the other layer
remains on the wall as a kind of waste sheet over which it is possible
to wallpaper again. This method has the disadvantage that either after
wallpapering several times ~here are several waste layers on the wall
which have to be removed at some time and are therefore all the more
difficult to remove, or that for subsequent wallpaperings it is neces-
sary to use non-splitting wallpapers which clearly has its disadvan-
tages. It also has been proposed to apply to the side of a wallpaper
; which is to be pasted, a layer of an emulsion of a mixture of wax and
a thermoplastic material, and in this manner to provide it with the ;
necessary adhesiYe-repelling finish. The production of this adhesive-
repellent coating is relatively expensive, however, in particular because
from a wet paper web first of all a finished dry wallpaper has to be
produced and this then has to be dried ag~in after the emulsion has
been applied.
The presenlt invention provides a paper comprising ~wo fibrous
layers matted into each other to havo their fibers interfelted or en-
tangled with each other, one layer being fibrous and containing 0.5 to
5%, based on the weight of the fibers, of a thermoplastic material
flocculatet from an aqueous dispersion with 40% to 80% by weight of -
the fibers being polyolefin fibers and 20 to 60% by weight of cellulose
fibers the other layer being composed of cellulosic fibers.
To mat the two layers, the paper is preferably produced in a
papor-Dn}ing r~chine in ~hich ~ebs Df the t~o Daterials are produced
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separately and after the sheet-forming process and the dewa~ering pro-
cess they may be joined together by couching. Advantageously an
Inverform*paper making machine is used for the manufacture of the paper.
This machine has a Fourdrinier with as many pulp feeders arranged in
series in the direction of movement of the web as the material to be
produced has layers. As a result individual pulp compositions may be
applied in any sequence. Advantageously the adhesive-repellent layer ~.
is applied to the other .layer which is a.lready laid on the endless wire.
One fibrous .layer of the paper according to the invention corre- .
sponds in composition to a customary wallpaper crude paper and con-
tains, for example, mechanical wood pulp and/or cellulose fibers, ce-
menting agent and if necessary a filler in the customary proportions for
example as stipulated in DIN sheet 6730. The other layer basical.ly may
. be of the same composition but may differ from the customary composition
in the type of fibers used and in addition in the presence of a relatively
small quantity of flocculated thermoplastic natural or synthetic material~ ::
Of the fibers contained in that layer, 40 to 80% byweight, and prefer-
ably approximately 60% by weight are composed of polyolefin based
. fibers and 20 to 60% by weight, preferably approximately 40% by weight, .
are composed of ce.llulose fibers.
l The preferred po.lyolefin fibers are those of polyethylene or poly-
propy.lene. Polyolefin fibers may be produced according to the pro-
cesses described in German Offenlegungsschrift (DOS) 1,951,576, and -
, DOS 2,117,370. Preferably, the polyethylene or polypropylene fibers
, produced according to the process of DOS 2,117,370, are used, these
. having a very large surface area, namely of more than 1 square m per g, ....
and they yield a particularly securely felted layer of paper. A very
advantageous composition of polyolefin fibers, from which an adequately
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stable suspension of fibers may be produced, is described in DOS
2,208,555. The compositions described therein are preferably used
for the productionof the polyolefin fiber-containing layer of the paper
according to the invention.
The thermoplastic materials which may be synthetic, regener-
ated or natural materials, flocculated from dispersions, present in the
polyolefin-containing layer are preferably flocculated from emulsifier-
free natural or synthetic latices, for example based on butadiene-
styrene copolymers, natural rubber, polychloroprene or butadiene-
polyacrylonitrile copolymers. The use of an emulsifier-free dispersion
of a copolymer of ethylene and a salt of a singly unsaturated acyl-
amido-N-sulfonic acid, is particularly advantageous. These are prefer-
ably alkali salts of the formula R CH = C(R2)-CONMe-SO3Me, in which
R1 and R2, which may be the same or different, denote hydrogen or an
organic radical with 1 to 10 carbon atoms and Me denotes an alkali
metal, in particular potassium. The preparation of such ethylene co-
polymers is described in DOS 1,720,667. The dispersion,of which the
preparation is clescribed in Example 9 of this Offenlegungsschrift, is
preferably used.
The ~ddition of the dispersion of thermoplastic particles to the
paper pulp and the flocculation of the particles advantageously does not
occur until after the pulp has been milled and after the milled puLp has
3 been mixed with the polyolefin fiber suspension. As a result of the
flocculation, for example with aluminum sulfate, the copolymer remains
on the screen of the paper-making machine after the formation and de-
, watering of the sheet, almost completely in the form of flakes finely
divided in the paper.
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The weight per unit area of the paper layer having the normal
composition depends upon the desired quality of the paper. For simple
wallpapers for example, it is approximately 50 to 65 g per square m.,
for better wallpapers 80 to 100 g per square m., and for heavier wall-
papers above 110 g per square m. For reasons of cost, the fibrous
material used for this layer is mechanical wood pulp mixed with cellu-
lose fibers. In addition there are the usual glueing or cementing agents.
For demanding uses, this fibrous layer may be composed of tough, long-
fibered fibrous material which is completely wood-free. The weight per
unit area of the paper layer on which the invention is primarily based
is generally 5 to 100 g per square m, and preferably 5 to 30 g per square
m. Also, the proportion of fibers contained in it apart from the proportion
of polyolefin fibers may be composed to a smaller or greater extent of
mechanical wood pulp.
The two-layer paper according to the invention may be cemented
in known manner to any substrate, e.g., a wall, with aqueous paste.
It is possible to use any product, for example those commercially avail-
able, for the paste, for example starch or starch derivatives, cellulose
ether, polyvinyl alcohol and mixtures of these substances. The paper
may be, however, provided, on the side formed by the polyolefin fiber- -
containing fibrous layer, by coating or dusting according to the electro- --
static principle, with water-activatable materials, such as water-
soluble cellulose ethers, water-soluble or water-swellable starch de-
rivatives or polyvinyl alcohol or a mixture of any two or more of the
above-mentioned substances. Such an application preferably should be
- in the range of 10 to 100 g per square m, in particular 10 to 30 g per
square m, in weight. Paper produced in this manner can be stuck on
without applying an adhesive and before sticking on requires only acti-
' vation by water.
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Wallpapers and posters prepared from the paper of the invention
when applied to walls are joined to the pasted surface by means of ad-
hesives mixed with water in such a manner that, after the adhesive has
dried, they hang securely on the wall and, if desired, may be later
removed from the wall by hand, without soaking or any other pretreat-
ment, in complete webs or at least in large pieces, after a part has been
lifted from the wall, with or without an instrument, so as to be able to
take hold of the paper.
The following example further illustrates the invention.
Layer 1: Base wallpaper paper (weight per unit area 80 g/sq. m):
70% by weight of mechanical wood pulp,
30% by weight of bleached pine sulfate celLulose,
15% by weight (based on mechanical wood pulp plus
cellulose) of kaolin,
coarse milling, and full cementing.
LaYer 2: Adhesive repelling layer (weight per unit area 20 g/sq. m):
60% by weight of polyolefin fibers,
40% by weight of bleached pLne sulfate cellulose,
5% by weight (based on the polyolefin fibers) of a 30 to
40% by weight dispersion of ethylene copolymer,
` flocculated with sufficient aluminum sulfate to
reach pH 4 . 5 .
It will be obvious to those skilled in the art that many modifi-
cations may be made within the scope of the present invention without
departing from the spirit thereof, and the invention includes all such
modifications .
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