U.S. patent application number 10/534840 was filed with the patent office on 2007-01-18 for wallpaper and method for production thereof.
Invention is credited to Gregor Bossnagel, Wolfgang Braun, Lutz Friedl-Goeppentin, Alexander Scherer.
Application Number | 20070012413 10/534840 |
Document ID | / |
Family ID | 32308524 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070012413 |
Kind Code |
A1 |
Braun; Wolfgang ; et
al. |
January 18, 2007 |
Wallpaper and method for production thereof
Abstract
Wallpaper base containing chemical pulp, filler, chemical
additives, and, as an option, groundwood pulp. Reduction of the wet
expansion is achieved in that the paper has a man-made fiber
content of at least 5 wt-%.
Inventors: |
Braun; Wolfgang; (Forbach,
DE) ; Scherer; Alexander; (Gaggenau, DE) ;
Friedl-Goeppentin; Lutz; (Baden-Baden, DE) ;
Bossnagel; Gregor; (Bruchsal, DE) |
Correspondence
Address: |
ROTHWELL, FIGG, ERNST & MANBECK, P.C.
1425 K STREET, N.W.
SUITE 800
WASHINGTON
DC
20005
US
|
Family ID: |
32308524 |
Appl. No.: |
10/534840 |
Filed: |
October 25, 2003 |
PCT Filed: |
October 25, 2003 |
PCT NO: |
PCT/DE03/03555 |
371 Date: |
September 21, 2006 |
Current U.S.
Class: |
162/129 ;
162/142; 162/146; 162/157.1; 162/158; 162/164.1; 162/169 |
Current CPC
Class: |
D21H 27/20 20130101;
D21H 27/14 20130101; D21H 23/04 20130101 |
Class at
Publication: |
162/129 ;
162/142; 162/146; 162/157.1; 162/158; 162/164.1; 162/169 |
International
Class: |
D21H 27/20 20070101
D21H027/20; D21H 23/04 20070101 D21H023/04; D21F 11/00 20060101
D21F011/00; D21H 13/00 20060101 D21H013/00; D21H 13/24 20070101
D21H013/24; D21H 17/67 20070101 D21H017/67; D21H 21/16 20070101
D21H021/16; D21H 21/18 20070101 D21H021/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2002 |
DE |
102527393 |
Claims
1. Wallpaper base with reduced wet expansion containing chemical
pulp, filler, chemical additives, and, optionally, groundwood pulp,
characterized in that it comprises a layer (3) which contains a
fraction of at least 5 wt-% of man-made fibers.
2. Wallpaper base according to claim 1, characterized in that the
fraction of man-made fibers is no more than 50 wt-%.
3. Wallpaper base according to claim 1, characterized in that the
fraction of man-made fibers is at least 10 wt-% and no more than 30
wt-%, preferably at least 15 wt-% and no more than 25 wt-%.
4. Wallpaper base according to claim 1, characterized in that at
least a part of the man-made fibers are fully-synthetic fibers.
5. Wallpaper base according to claim 4, characterized in that at
least part of the fully-synthetic fibers are polyester fibers.
6. Wallpaper base according to claim 1, characterized in that the
mean length of the man-made fibers is less than 8 mm, preferably
between 3 mm and 8 mm, particularly preferably between 4 mm and 7
mm.
7. Wallpaper base according to claim 1, characterized in that the
fraction of chemical pulp is at least 10 wt-% and no more than 80
wt-%, preferably at least 20 wt-% and no more than 60 wt-%.
8. Wallpaper base according to claim 1, characterized in that the
layer (3) contains a fraction of groundwood pulp of at least 5
wt-%, preferably at least 10 wt-%, and particularly preferably at
least 20 wt-%, and no more than 50 wt-%, preferably no more than 35
wt-%.
9. Wallpaper base according to claim 1, characterized in that the
chemical additives include a fraction of a binding agent.
10. Wallpaper base according to claim 1, characterized in that the
binding agent is anionic.
11. Wallpaper base according to claim 1, characterized in that the
binding agent comprises a polymer, preferably an alkylacrylate,
particularly preferably a butylacrylate.
12. Wallpaper base according to claim 11, characterized in that the
polymer is a copolymer of an alkylacrylate and styrene.
13. Wallpaper base according to claim 9, characterized in that the
fraction of the binding agent is at least 0.5 wt-% and no more than
5 wt-%.
14. Wallpaper base according to claim 9 characterized in that the
chemical additives include an oppositely charged
precipitation-enhancing component.
15. Wallpaper base according to claim 1, characterized in that the
chemical additives include a fraction of a wet-strength agent of at
least 0.5 wt-% and no more than 5 wt-%.
16. Wallpaper base according to claim 1, characterized in that the
chemical additives include a fraction of sizing agent of at least
0.5 wt-% and no more than 5 wt-%.
17. Wallpaper base according to claim 1, characterized in that it
comprises an additional wall-facing lower layer (2).
18. Wallpaper base according to claim 16, characterized in that the
lower layer (2) contains a polymer, preferably a
thermally-crosslinked polymer, particularly preferably a
thermally-crosslinked copolymer.
19. Wallpaper base according to claim 18, characterized in that the
polymer is a copolymer of an alkylacrylate, preferably of
butylacrylate, and, in particular, of styrene.
20. Wallpaper base according to claim 17, characterized in that the
lower layer (2) contains a wax, preferably a paraffin wax.
21. Wallpaper base according to claim 20, characterized in that the
wax fraction of the lower layer is at least 5 wt-% and no more than
30 wt-%.
22. Wallpaper base according to claim 17, characterized in that the
lower layer (2) contains a wet-strength agent preferably at a
fraction of less than 5 wt-%.
23. Method for the manufacture of wallpaper base according to claim
1, in which chemical pulp, filler, chemical additives, and, as an
option, groundwood pulp are guided from a blend chest via a stock
cleaning unit and a headbox to a horizontal screen, characterized
in that a fraction of man-made fibers of at least 5 wt-%, relative
to the solids content of the headbox, is added upstream of the
headbox.
24. Method according to claim 23, characterized in that the
man-made fibers are added to the blend chest in the form of the dry
fibers.
25. Method according to claim 23 wherein an oppositely charged
precipitation-enhancing component is added to the stock stream
subsequent to the addition of the binding agent.
Description
[0001] The term wallpaper base (or "body paper for wallpaper") is
commonly used for paper processed by wallpaper manufacturers by
means of printing or other surface modification to produce a
wallpaper. The paper must have several properties that are
important for wallpaper manufacture, such as, for example, good
printability and a firm, closed surface. Further it must not
generate dust.
[0002] In particular, the invention refers to a wallpaper whose wet
expansion is sufficiently low to render it suitable for a wall
covering procedure, in which aqueous wallpaper adhesive is applied
to the wall rather than the wallpaper ("paste the wall"). This type
of wall covering procedure is simpler and does not require any
soaking time, but requires that the wet expansion (expansion of a
water-saturated paper as compared to the dry paper) of the paper is
very low. Preferably, it should be no more than 0.5%, particularly
preferably no more than 0.3%.
[0003] Since the manufacture of such a paper is associated with
great difficulties, a nonwoven material, also called nonwoven
wallpaper, was developed. Using such nonwovens, it is possible to
meet the requirements specified above, but not all aspects of the
quality are satisfactory. In particular, opacity and embossing
stability are poorer as compared to paper. Processing of nonwovens
is difficult since fibers may be released from the nonwoven
composite during the processing steps involved in wallpaper
production.
[0004] On the basis of the aforementioned, the present invention is
based on the technical problem to provide a wallpaper having the
desired low wet expansion without the disadvantages associated with
the use of a nonwoven material.
[0005] This problem is solved with a wallpaper base containing
chemical pulp, filler, chemical additives, and, as an option,
groundwood pulp, by containing a fraction of man-made fibers of at
least 5 wt-%.
[0006] The inventors have noticed that it is possible to use a
regular paper production procedure on a paper machine with a
horizontal screen to manufacture a paper with a sufficiently high
fraction of man-made fibers to guarantee the desired dimensional
stability. With regard to this issue, there were serious concerns
amongst the experts: [0007] At the high operating speeds of common
horizontal screen paper machines, a suitable orientation of the
fibers in longitudinal and transverse direction must be achieved.
In particular, it is necessary to keep the fibers from excessively
orienting in longitudinal direction since this impairs the
dimensional stability. Moreover, a very uniform distribution of the
fibers including man-made fibers is required in order to obtain a
homogeneous paper. [0008] The water balance is of crucial
significance for paper production. The common fiber ingredients of
paper (mainly chemical pulp fibers) take up large quantities of
water in the vat even before sheet formation occurs. Whereas the
free water quickly flows off in the screen part of the machine, the
bound water remains attached to the fibers and is removed only in
the subsequent compression and drying process. This dehydration
process, which is important in paper production, is disturbed
significantly if man-made fibers rather than chemical pulp fibers
are present in the fiber slush ("stock") guided to the screen part.
[0009] Considerable technical problems had to be expected, in part
related to the fact that man-made fibers are significantly longer
than chemical pulp fibers. This complicates the obligatory cleaning
and separation of interfering ingredients significantly.
[0010] The results obtained by the invention are improved further
by the preferred features described in the following, which concern
both the composition of the wallpaper base and the structure of a
sheet material having at least two layers as well as the method of
its production. The features described may be used either
individually or in combination in order to generate preferred
embodiments of the present invention.
[0011] All specifications of percent fractions made in the
following are expressed in units of weight percent relative to the
total dry mass of the mixture in question.
[0012] The predominant ingredients, in terms of quantity present,
of the wallpaper base according to the invention are chemical pulp,
man-made fibers, and, as an option, groundwood pulp (mechanically
disintegrated wood). Typically, the sum of these fractions is at
least 70%. Preferably, the fraction of man-made fibers is lower
than the fraction of chemical pulp, preferably, the ratio of
man-made fiber:chemical pulp fiber is between 1:2 and 4:5. A
groundwood pulp fraction is not obligatory, but particularly
preferred because it not only leads to lower costs, but also has a
positive impact on the quality. The groundwood pulp fraction can
even be slightly higher than the chemical pulp fraction.
Preferably, the mass ratio of groundwood pulp:chemical pulp is
between 4:2 and 1:2.
[0013] Preferably, the fraction of man-made fibers present in the
wallpaper base according to the invention should not exceed 50%,
whereby fractions of 10% to 30% are preferred and fractions of 15%
to 25% are particularly preferred. At least a fraction of the
man-made fibers should be fully synthetic fibers, preferably
polyester fibers. It is preferable for all fractions mentioned
above to be fully synthetic fibers, in particular, polyester.
[0014] The mean length of the man-made fibers should be less than 8
mm, preferably between 3 mm and 8 mm. The range from 4 mm to 7 mm
is particularly preferred.
[0015] The chemical pulp fraction of the wallpaper base should be
between 10 and 80%, preferably between 20 and 60%. The lower limit
of the groundwood pulp fraction is preferably 5%, preferably 10%,
and particularly preferably 20%. An upper limit of the groundwood
pulp fraction of the paper of 50%, preferably 35%, should not be
exceeded.
[0016] Aside from the three main ingredients mentioned above, the
wallpaper according to the invention contains fillers and
additives. As a filler, for example kaolin is added. The filler
content is preferably between 5 and 20%.
[0017] Amongst the chemical additives, the binding agent used is of
major significance for the success of the invention. A polymer in
the form of an aqueous dispersion has proven its utility. The
polymer preferably contains an alkylacrylate, in particular
butylacrylate. A copolymer of an alkylacrylate and styrene is
particularly suitable.
[0018] Preferably, the chemical additives include two components
with opposite charge which jointly form a binding agent system. A
binding agent system of this type comprises, aside from the binding
agent, an oppositely charged second component which is added after
the binding agent to the stock suspension. This component causes
the binding agent, which is suspended in the suspension, to
precipitate onto the fibers and exert its binding effect. This
component is called "oppositely charged precipitating component".
Preferably, the binding agent is anionic and the precipitating
component is cationic. In practical application, an epichlorhydrine
resin, which also acts as a wet-strength conferring agent, has
proven useful as cationic precipitating component to act jointly
with an anionic binding agent.
[0019] In general, the chemical additives should include, in
addition to a binding agent, a wet-strength conferring agent,
preferably at a fraction of 0.5% to 5%. Another advantageous
chemical additive is a sizing agent at a fraction of 0.5% to
5%.
[0020] All components specified thus far are added to the stock
suspension prior to the formation of sheets and are distributed
homogeneously in the resulting paper.
[0021] The following illustration of the present invention refers
to the figures. In the figures:
[0022] FIG. 1 shows a schematic cross-section of a three-layered
wallpaper base;
[0023] FIG. 2 shows a material flow diagram of a procedure
according to the invention;
[0024] FIG. 3 shows a detailed procedural scheme.
[0025] The wallpaper base 1 shown in FIG. 1 consists of three
layers, namely a wall-facing lower layer 2 (i.e. for gluing the
wallpaper to the wall), a main layer 3, and an outward-facing cover
layer 4 (i.e. facing the room when the wallpaper is glued to the
wall). The main layer 3 consists of a material with the properties
illustrated above.
[0026] The lower layer 2 is formed by a coating applied to the main
layer 3 by means of which the adhesion of the wallpaper on the wall
is improved in a controlled fashion such that the wallpaper not
only adheres to the wall, but also is easy to strip off the wall.
Ideally, it should be possible to strip off the wallpaper
completely in the dry state. These properties shall be attained
(for example in DE-A-2302890) without a need to use specialized
gluing techniques. Rather, the wallpaper shall be suitable for
processing with conventional water-based wallpaper adhesives.
[0027] Preferably, the wall-facing lower layer 2 contains a
polymer, especially a thermally-crosslinked copolymeride. In
particular, an alkylacrylate copolymeride, preferably of
butylacrylate, preferably polymerized with styrene has proven
useful for this purpose. According to another preferred embodiment
of the present invention, the layer 2 contains a wax, preferably a
paraffin wax, whereby the wax fraction of the lower layer should be
between 5% and 30%. It is also advantageous for the lower layer to
contain a wet-strength conferring agent, preferably at a fraction
of less than 5%. All components of the lower layer 2 are mixed and
applied to the main layer 3 using a conventional coating
procedure.
[0028] The cover layer 4 preferably consists of PVC and serves as a
carrier for printing.
[0029] The diagram shown in FIG. 2 illustrates the procedural steps
of the production method of the main layer 3. The components,
chemical pulp 10, groundwood pulp 11, filler 12, and chemical
additives 13 are mixed in a mixing canal 15 and then transported
from there to the blend chest 16. In the preferred embodiment
shown, the man-made fibers 17, preferably provided in the form of
dry fibers, are added separately to the contents of the blend chest
16.
[0030] It is preferred to use fibers supplied as short sections of
a fiber strand, whereby each of the sections contains a large
number of fibers which, with good approximation, are equal in
length (equivalent to the length of the strand sections).
Surprisingly, it was found that the required individualization and
homogeneous distribution of these fibers is attained particularly
well when the fibers are added in the form of the dry fibers to the
contents of the blend chest 16.
[0031] Dilution water 18 is then added to the stock stream
discharged from the blend chest 16. The stream then enters a stock
cleaning unit 19 and is guided from there via a headbox 20 to the
horizontal screen of a wire section 21. The sheet formed there is
then compressed in a press section 22, subsequently dried in a
drying section 23, and finally wound in a winding unit 24.
[0032] The stock cleaning unit 19 preferably contains a
pressure-sorting device called "pressure screen", in which the
stock runs through a slit or punched screen whose dimensions are
optimized to pass the desired fiber components including the
man-made fibers but retain interfering contaminations. According to
another preferred embodiment, a cleaner facility effecting the
desired separation of the components on the basis of their density
is provided.
[0033] The coating with the lower layer 2 can be performed either
online or offline. Usually, the cover layer is applied during the
further course of processing.
[0034] FIG. 3 illustrates a number of additional details of the
preferred method, in particular with regard to the components of
the binding agent system. From the mixing canal 15, the stock is
transported to the blend chest 16, in which the synthetic fibers 17
are added. It is preferable to add the binding agent 13a between
the blend chest 16 and a downstream stock pump 25. The pump 25
pumps the stock into a machine chest 26 and simultaneously affords
good mixing of the binding agent and the other components of the
suspension. The liquid level inside the machine chest 26 is kept
constant by an overflow 27 in order to provide for uniform
hydrostatic pressure at the entry of the downstream pump 28 which
transports the stock to the dilution water container 18. From there
it is transported by means of an additional pump 29 to the cleaning
unit 19. As shown, the precipitating component 13b of the binding
agent system is added to the stock stream as it is discharged from
the machine chest 26, whereby it is advantageous to effect this
ahead of the downstream pump 28 in order to achieve good
mixing.
* * * * *