U.S. patent application number 10/543191 was filed with the patent office on 2006-06-01 for method for creating a fibrous substance suspension used for producing a tissue web or hygiene web.
This patent application is currently assigned to Voith Paper Patent GmbH. Invention is credited to Klaus Dolle.
Application Number | 20060113051 10/543191 |
Document ID | / |
Family ID | 32694951 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060113051 |
Kind Code |
A1 |
Dolle; Klaus |
June 1, 2006 |
Method for creating a fibrous substance suspension used for
producing a tissue web or hygiene web
Abstract
Method and device for producing a fibrous suspension used for
producing a tissue web or hygiene web. The fibers contained in the
fibrous suspension are, in an online process, directly loaded with
a filler in the tissue preparation line by a chemical precipitation
reaction.
Inventors: |
Dolle; Klaus; (Kisslegg,
DE) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
Voith Paper Patent GmbH
Heidenheim
DE
|
Family ID: |
32694951 |
Appl. No.: |
10/543191 |
Filed: |
January 20, 2004 |
PCT Filed: |
January 20, 2004 |
PCT NO: |
PCT/EP04/50027 |
371 Date: |
August 29, 2005 |
Current U.S.
Class: |
162/181.2 ;
162/181.4 |
Current CPC
Class: |
D21H 17/70 20130101;
D21H 17/675 20130101; D21C 9/004 20130101 |
Class at
Publication: |
162/181.2 ;
162/181.4 |
International
Class: |
D21H 17/67 20060101
D21H017/67 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2003 |
DE |
103 02 783.1 |
Claims
1-34. (canceled)
35. A method for creating a fibrous suspension for producing a
tissue web or a hygiene web, comprising: directly loading fibers
contained in a fibrous suspension with a filler through a chemical
precipitation reaction in an online process in a tissue material
preparation line.
36. The method of claim 35, wherein crystalline precipitation
product particles are produced in the online process.
37. The method of claim 36, wherein the crystalline precipitation
product particles comprise calcium carbonate.
38. The method of claim 35, wherein the loading of the fibers
comprises adding at least one of calcium oxide and calcium
hydroxide; and the chemical precipitation reaction is initiated
through carbon dioxide or a gas containing carbon dioxide.
39. The method of claim 38, wherein crystalline precipitation
product particles are produced without the introduction of mixing
energy.
40. The method of claim 35, further comprising feeding the fibrous
suspension to a treatment unit comprising at least one of a
fluffer, refiner, and disperser.
41. The method of claim 40, wherein the loading of the fibers
occurs before feeding the fibrous suspension to the treatment
unit.
42. The method of claim 40, wherein the loading of the fibers
occurs after feeding the fibrous suspension to the treatment
unit.
43. The method of claim 40, wherein the treatment unit is usable as
a reactor for the chemical precipitation reaction.
44. The method of claim 38, wherein calcium hydroxide in liquid
form is added to the fibrous suspension.
45. The method of claim 38, wherein calcium hydroxide in dry form
is added to the fibrous suspension.
46. The method of claim 40, wherein the fibrous suspension has a
stock consistency in the range of approximately 5% to approximately
60% during feeding.
47. The method of claim 46, further comprising adding calcium
hydroxide to the suspension before the feeding of the fibrous
suspension to the treatment unit.
48. The method of claim 47, wherein the fibrous suspension has a
stock consistency in the range of approximately 15% to
approximately 35% during feeding.
49. The method of claim 38, wherein the carbon dioxide or the gas
containing carbon dioxide is added at a temperature in the range of
approximately -15.degree. C. to approximately 120.degree. C.
50. The method of claim 48, wherein the carbon dioxide or the gas
containing carbon dioxide is added at a temperature in the range of
approximately 20.degree. C. to approximately 90.degree. C.
51. The method of claim 35, wherein crystalline precipitation
product particles with a rhombohedral form are produced in the
online process.
52. The method of claim 35, wherein crystalline precipitation
product particles with a scalenohedral form are produced in the
online process.
53. The method of claim 35, wherein spherical crystalline
precipitation product particles are produced in the online
process.
54. The method of claim 40, wherein the treatment unit comprises a
disperger with two plates disposed opposite to one another and
rotating relative to one another.
55. The method of claim 53, wherein the two plates comprise a rotor
and stator.
56. The method of claim 54, wherein crystalline precipitation
product particles are produced in the online process; and the
dimensions of the crystalline precipitation product particles are
influenced in the treatment unit.
57. The method of claim 36, wherein maximum dimensions of the
crystalline precipitation product particles are in the range of
approximately 0.05 .mu.m to approximately 5 .mu.m.
58. The method of claim 56, wherein the maximum dimensions of the
crystalline precipitation product particles are in the range of
approximately 0.3 .mu.m to approximately 2.5 .mu.m.
59. The method of claim 35, wherein crystalline precipitation
product particles with a rhombohedral form are produced in the
online process, said particles having an edge length of
approximately 0.05 .mu.m to approximately 2 .mu.m.
60. The method of claim 35, wherein crystalline precipitation
product particles with a scalenohedral form are produced in the
online process, said particles having an edge length of
approximately 0.05 .mu.m to approximately 2 .mu.m and a diameter of
approximately 0.01 .mu.m to approximately 0.5 .mu.m
61. The method of claim 53, further comprising: diluting the
fibrous suspension with water in a radially outer area of the
treatment unit.
62. The method of claim 40, wherein the fibrous suspension guided
through the treatment unit has a stock consistency of approximately
0.1% to approximately 50%.
63. The method of claim 61, wherein the fibrous suspension guided
through the treatment unit has a stock consistency of approximately
5% to approximately 35%.
64. The method of claim 35, further comprising: maintaining a
substantially constant supply of carbon dioxide or a gas containing
carbon dioxide into the fibrous suspension.
65. The method of claim 35, further comprising: adding carbon
dioxide or a gas containing carbon dioxide to the fibrous
suspension at a pressure of approximately 0.1 bar to approximately
6 bar.
66. The method of claim 64, further comprising: adding the carbon
dioxide or the gas containing carbon dioxide at a pressure of
approximately 0.5 bar to approximately 3 bar.
67. The method of claim 35, further comprising: regulating or
controlling a pH value of the fibrous suspension by regulating or
controlling a supply of carbon dioxide, such that substantially all
base materials of the chemical precipitation reaction are converted
to reaction products.
68. The method of claim 66, further comprising: establishing the pH
value in a range of approximately 6 to approximately 10.
69. The method of claim 67, further comprising: establishing the pH
value in a range of approximately 7 to approximately 8.5.
70. The method of claim 66, further comprising: introducing energy
for the chemical precipitation reaction in a range of approximately
0.3 kWh/t to approximately 8 kWh/t.
71. The method of claim 69, wherein the energy is in a range of
approximately 0.5 kWh/t to approximately 4 kWh/t.
72. The method of claim 35, further comprising: adding dilution
water to the fibrous suspension to obtain a diluted fibrous
suspension with a stock consistency of approximately 0.1% to
approximately 16%.
73. The method of claim 71, wherein the diluted fibrous suspension
has a stock consistency of approximately 2% to approximately
6%.
74. The method of claim 53, wherein a radially outer edge portion
of a rotating portion of the treatment unit has a circumferential
speed of approximately 20 m/s to approximately 100 m/s.
75. The method of claim 73, wherein the circumferential speed is
approximately 40 m/s to approximately 60 m/s.
76. The method of claim 53, wherein the two plates are separated by
a gap of approximately 0.5 mm to approximately 100 mm.
77. The method of claim 75, wherein the gap is approximately 25 mm
to approximately 75 mm.
78. The method of claim 53, wherein the two plates have a diameter
of approximately 0.5 m to approximately 2 m.
79. The method of claim 35, wherein the chemical precipitation
reaction has a reaction time of approximately 0.01 minute to
approximately 1 minute.
80. The method of claim 35, wherein the chemical precipitation
reaction has a reaction time of approximately 0.1 seconds to
approximately 10 seconds.
81. The method of claim 37, further comprising: washing out free
calcium carbonate not deposited on or in the fibers.
82. A tissue product made from the fibrous suspension according to
claim 35.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a U.S. National Stage of
International Patent Application No. PCT/EP2004/050027 filed Jan.
20, 2004, and claims priority under 35 U.S.C. .sctn. 119 of German
Patent Application No. 10302783.1 filed Jan. 24, 2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method for creating a fibrous
suspension used for producing a tissue web or a hygiene web. It
further relates to tissue products made from a fibrous suspension
produced according to such a method.
[0004] 2. Discussion of Background Information
[0005] The production of tissue requires large amounts of water,
determined by the extremely low consistency or stock consistency of
the fibrous suspension to be fed to the relevant paper or tissue
machine. In addition, tissue is produced with a very low basis
weight between 8 and 40 g/m.sup.2, depending on the respective
final product, such as, e.g., cellulose wadding (8 to 30
g/m.sup.2), hygiene tissue (14 to 25 g/m.sup.2), hygiene paper (8
to 30 g/m.sup.2), napkin paper (20 to 30 g/m.sup.2) and towel paper
(20 to 40 g/m.sup.2).
[0006] Furthermore, these products have a low beating degree, which
is necessary to ensure an adequate dewatering and drying of the web
to be produced. However, as is generally known, the beating makes a
major contribution to the mechanical properties of the final
product. As a result, the low beating degree often conflicts with
the requirements regarding mechanical properties.
[0007] In most cases, tissue products are produced from a bleached
sulfite or sulfate fibrous suspension, sometimes mixed with
bleached wood pulp and/or recovered fibrous paper stock (e.g., wet
broke, broke, recovered paper, etc.) and/or some type of fibrous
suspension in a single-cylinder or fourdrinier Yankee machine. This
applies regardless of whether the respective tissue product
contains filler that was produced through a beating process or
another production process. The material used with the conventional
process is currently either precipitate material or another
material such as calcium carbonate, talc, TiO.sub.2, silica,
etc.
[0008] In order to achieve the strongest possible bonding of the
fillers to the fiber surface with a respective replacement of
fibrous material by filler material, the corresponding treatment
has recently been conducted through a so-called "Fiber Loading.TM."
process, as described in U.S. Pat. No. 5,223,090. In such a "Fiber
Loading.TM." process, at least one additive, such as, e.g., a
filler, is deposited on the wetted fiber surfaces of the fibrous
material. The fibers can thereby be loaded, e.g., with calcium
carbonate. To this end, calcium oxide and/or calcium hydroxide is
added to the moist, disintegrated fiber material in such a way that
at least a part thereof combines with the water present in the
fiber material. The fiber material thus treated is subsequently
treated with carbon dioxide.
[0009] As described in U.S. Pat. No. 6,413,365 B1 and DE 101 07 448
A, a disperger is used that can also be used at the same time as a
reactor for the chemical precipitation reaction.
SUMMARY OF THE INVENTION
[0010] The present invention discloses a method of creating a
fibrous suspension with which the efficiency and cost-effectiveness
of the production of corresponding tissue or hygiene products is
further optimized.
[0011] This invention provides a method for producing a fibrous
suspension used for the production of a tissue web or a hygiene
web, in which method the fibers contained in the fibrous suspension
are directly loaded with a filler in an online process in the
tissue material preparation line through a chemical precipitation
reaction.
[0012] According to the present invention, conventional fillers are
replaced by a filler produced through a chemical precipitation
reaction according to the "Fiber Loading.TM." process. Such a
fibrous suspension has a higher drainability and a lower beating
degree. Moreover, the fibers loaded with filler according to the
present invention have a lower water retention value. The
respective tissue product can be produced more cost-effectively
because the water of the fibrous suspension can be removed much
more quickly and the tissue web can be dried more quickly. With
loading the fibers according to the "Fiber Loading.TM." process,
higher values result in terms of drainability with the same beating
degree, so that a higher beating degree can be achieved, which
means better mechanical properties for the final product. The lower
water retention or better drainability and better drying prove to
be an advantage in particular when the respective final product is
subsequently printed.
[0013] With the corresponding treatment through a "Fiber
Loading.TM." process, crystalline precipitation product particles
can be produced in the online process.
[0014] The precipitation product is preferably calcium carbonate.
According to a preferred embodiment of the invention, to load the
fibers of the fibrous suspension, calcium oxide and/or calcium
hydroxide is added and the precipitation is initiated through
carbon dioxide or a gas containing carbon dioxide (for example,
flue gas or the like). The crystalline precipitation product
particles are produced in the respective gas atmosphere preferably
without the introduction of mixing energy.
[0015] To load the fibers, calcium carbonate is deposited on the
wetted fiber surfaces by adding calcium oxide and/or calcium
hydroxide to the moist fiber material, whereby at least part
thereof can combine with the water of the fibrous material. The
fiber material is then treated with carbon dioxide or a gas
containing carbon dioxide. The calcium carbonate (CaCO.sub.3)
obtained can form a suspension around and between the fibers.
[0016] The term "wetted fiber surfaces" can apply to all the wetted
surfaces of the individual fibers. This includes cases in which the
fibers are loaded with calcium carbonate both on their outer
surface and in their interior (lumen).
[0017] Accordingly, the fibers are loaded with the filler calcium
carbonate, the deposition on the wetted fiber surfaces being
carried out by a so-called "Fiber Loading.TM." process, as
described as such in U.S. Pat. No. 5,223,090. In this "Fiber
Loading.TM." process, the carbon dioxide reacts with the calcium
hydroxide to form water and calcium carbonate.
[0018] The fibrous suspension is preferably fed to a treatment unit
comprising a fluffer, a refiner, a disperger and/or the like. The
treatment unit can have, e.g., a structure such as is described in
U.S. Pat. No. 6,413,365 B1 and DE 101 07 448 A.
[0019] The fibers of the fibrous suspension can be loaded with
filler before or after the treatment unit comprising a fluffer, a
refiner, a disperger and/or the like. According to the invention,
the treatment unit comprising a fluffer, a refiner, a disperger
and/or the like can be used at the same time as a reactor for the
chemical precipitation reaction. In this respect, the invention can
be embodied, e.g., as described in U.S. Pat. No. 6,413,365 B1 and
DE 101 07 448 A.
[0020] The calcium hydroxide can be added to the fibrous suspension
in liquid form or in dry form.
[0021] A preferred embodiment of the method according to the
invention provides that the fibrous suspension, e.g., the fibrous
suspension mixed beforehand with calcium hydroxide, is fed to the
treatment unit comprising a fluffer, a refiner, a disperger and/or
the like with a stock consistency that lies in the range of
approximately 5 to approximately 60% and preferably in a range of
approximately 15 to approximately 35%.
[0022] The carbon dioxide or the gas containing carbon dioxide can
be added before, after and/or into the treatment unit.
[0023] The carbon dioxide or the gas containing carbon dioxide is
added at a temperature that lies in a range of approximately -15 to
approximately 120.degree. C., and preferably in a range of
approximately 20 to approximately 90.degree. C.
[0024] With the "Fiber Loading.TM." process, individual
precipitation product particles can be produced which are deposited
on or in the fibers at equal intervals. In the gas zone provided
for carrying out the precipitation reaction, the separate,
individual fibers can be exposed to the respective gas atmosphere,
whereupon the corresponding precipitation reaction occurs and
directly after that the calcium carbonate (CaCO.sub.3) is
obtained.
[0025] According to the invention, crystalline precipitation
product particles with a rhombohedral form, a scalenohedral form
and/or spherical crystalline product precipitation particles can be
produced. The respective amount of crystalline precipitation
product particles depends on the respective temperature range for
the fibrous suspension and the carbon dioxide and, e.g., on the
proportion of calcium hydroxide in the fibrous suspension.
[0026] According to the invention, a treatment unit is used in the
form of a disperger with two plates opposite to one another and
rotating relative to one another, preferably in the form of a
disperger with a rotor and a stator. Such a disperger can, for
example, have a structure such as the disperger described in U.S.
Pat. No. 6,413,365 B1 and DE 101 07 448 A.
[0027] In such a treatment unit, the dimensions of the crystalline
precipitation product particles can be influenced in the desired
manner. For example, a desired distribution of crystalline
precipitation product particles in the fibrous suspension can be
achieved. Preferably, only low shearing forces are generated in the
respective treatment unit.
[0028] Accordingly, when passing through the treatment unit,
crystalline precipitation product particles can be produced, the
maximum dimensions of which lie in a range of approximately 0.05 to
approximately 5 .mu.m and preferably in a range of approximately
0.3 to approximately 2.5 .mu.m.
[0029] Depending on the respective type of paper, crystalline
precipitation product particles with a rhombohedral form with a
respective edge length in a range of approximately 0.05 to
approximately 2 .mu.m, or crystalline precipitation product
particles with a scalenohedral form with a respective length in a
range of approximately 0.05 to approximately 2 .mu.m and a
respective diameter in a range of approximately 0.01 to
approximately 0.5 .mu.m can be produced.
[0030] According to the invention, the fibrous suspension is
diluted with water, preferably in a radially outer area of the
treatment unit comprising two plates rotating relative to one
another. The further radially outwards the fibrous suspension
reaches on the rotor disk, the lower the respective shear or
shearing force in view of the fed dilution water.
[0031] The stock consistency of the fibrous suspension guided
through the treatment unit is in a range of approximately 0.1 to
approximately 50% and preferably in a range of approximately 5 to
approximately 35%.
[0032] According to the invention, a constant feed of carbon
dioxide or gas containing carbon dioxide is provided. The carbon
dioxide or the gas containing carbon dioxide is added, e.g., under
a pressure in a range of approximately 0.1 to approximately 6 bar,
and preferably in a range of approximately 0.5 to approximately 3
bar.
[0033] A corresponding pressure in the carbon dioxide supply line
can be provided by which the gas, i.e., the carbon dioxide or the
gas containing carbon dioxide, is fed, e.g., to form a gas ring
that can also be produced, e.g., in the treatment unit. As with a
garden hose, the pressure is increased as a higher water quantity
is required. Since the carbon dioxide is a compressible gas, the
respective amount of gas can also be increased accordingly in order
to ensure a complete precipitation reaction.
[0034] According to a preferred embodiment of the invention, in the
course of the chemical precipitation reaction, an essentially
complete conversion of the base materials (i.e., calcium oxide or
calcium hydroxide and carbon dioxide) into the reaction products
(i.e., calcium carbonate and water) is ensured by regulating or
controlling the pH value of the fibrous suspension. This is
preferably accomplished via the supply of carbon dioxide or gas
containing carbon dioxide. A pH value can be established which lies
in a range of approximately 6 to approximately 10, and preferably
in a range of approximately 7 to approximately 8.5. Corresponding
values can be provided in particular for the final reaction.
[0035] The energy introduced for the chemical precipitation
reaction lies in a range of approximately 0.3 to approximately 8
kWh/t, and preferably in a range of approximately 0.5 to
approximately 4 kWh/t.
[0036] Sufficient dilution water for mixing with the fibrous
suspension is added so that a stock consistency of the diluted
fibrous suspension results in a range of approximately 0.1 to
approximately 16%, and preferably in a range of approximately 2 to
approximately 6%.
[0037] The fibrous suspension can then be exposed to atmospheric
pressure and fed to a following machine or it can be placed in a
container or box. The fibrous suspension can then be fed, e.g., to
the next process equipment that follows in the process for
producing a tissue or hygiene web.
[0038] The treatment unit is preferably operated such that its
rotating plate or rotor has a circumferential speed at the radially
outer edge in a range of approximately 20 to approximately 100 m/s,
and preferably in a range of approximately 40 to approximately 60
m/s.
[0039] The width of the gap between the two plates of the treatment
unit rotating relative to one another is in a range of
approximately 0.5 to approximately 100 mm, and preferably in a
range of approximately 25 to approximately 75 mm.
[0040] In the treatment unit, the diameter of the two plates
rotating relative to one another, or of the rotor and the stator,
is in a range of approximately 0.5 to approximately 2 m.
[0041] The reaction time for the chemical precipitation reaction is
in a range of approximately 0.01 min to approximately 1 min, and
preferably is approximately 0.1 s to approximately 10 s.
[0042] If necessary, free calcium carbonate that is not deposited
in and/or on the fibers can be washed out.
[0043] A pressure container is not necessary.
[0044] According to the invention, the following parameters affect
the chemical precipitation reaction: fibrous suspension, calcium
oxide and/or calcium hydroxide in liquid or dry form, carbon
dioxide, gas zone, rotor, stator, crystals produced in a gas
atmosphere without introducing mixing energy, mixing at low
shearing force, no pressure container.
[0045] According to the invention, individual crystalline
precipitation product particles can be produced which are deposited
on or in the fibers at equal intervals in the manner necessary to
meet the requirements of the respective tissue product. The
particle sizes described above, for example, can be produced.
[0046] After the "Fiber Loading.TM." process has been completed,
the following advantages result regarding the stock properties for
the tissue product:
[0047] The fibrous suspension treated according to the "Fiber
Loading.TM." process has a higher drainability or a lower beating
degree. The respective values can lie, e.g., in a range of 5 to
approximately 100 ml CSF or in a range of approximately 0.2 to
approximately 15.degree. SR, depending on the drainability or the
beating degree. Furthermore, the fibers loaded accordingly have
lower water retention values, which can lie, e.g., in a range from
approximately 2 to approximately 25%, depending on the respective
furnish. Tissue paper can now be produced in a more cost-effective
manner, since water can be removed much more quickly from the
fibrous suspension and the tissue web can be dried more
quickly.
[0048] For tissue applications for which no specific filler content
is necessary, the free precipitated calcium carbonate, i.e., the
calcium carbonate not deposited in or on the fibers, can be removed
by a washing process before the fibrous suspension is fed to the
respective tissue machine or, if necessary, before the beating
process. As a result, the fibers remain covered with calcium
carbonate, which provides the advantage that the dewatering is
facilitated and the drying accelerated, thereby resulting in a
lower re-moistening of the final tissue product.
[0049] The "Fiber Loading.TM." process can be performed before
beating, after beating or during beating, depending on the
requirements of the respective final product.
[0050] Since a higher drainability results with an equal beating
degree when the fibers are loaded with a precipitation product, a
greater beating is possible, which leads to better mechanical
properties of the final product.
[0051] Lower water retention and better drying are an advantage, in
particular if the respective product is subsequently printed.
[0052] According to the invention, there is provided a method for
creating a fibrous suspension for producing a tissue web or a
hygiene web by directly loading fibers contained in a fibrous
suspension with a filler through a chemical precipitation reaction
in an online process in a tissue material preparation line.
[0053] According to the invention, the crystalline precipitation
product particles are produced in the online process. The
crystalline precipitation product particles comprise calcium
carbonate. The maximum dimensions of the crystalline precipitation
product particles are in the range of approximately 0.05 .mu.m to
approximately 5 .mu.m, and preferably in the range of approximately
0.3 .mu.m to approximately 2.5 .mu.m. The invention includes
washing out free calcium carbonate not deposited on or in the
fibers.
[0054] According to the invention, the loading of the fibers
includes adding at least one of calcium oxide and calcium
hydroxide, and the chemical precipitation reaction is initiated
through carbon dioxide or a gas containing carbon dioxide. The
crystalline precipitation product particles may be produced without
the introduction of mixing energy. Calcium hydroxide in liquid form
or in dry form may be added to the fibrous suspension. The carbon
dioxide or the gas containing carbon dioxide is added at a
temperature in the range of approximately -15.degree. C. to
approximately 120.degree. C., preferably in the range of
approximately 20.degree. C. to approximately 90.degree. C.
[0055] According to the invention, crystalline precipitation
product particles with a rhombohedral form may be produced in the
online process, the particles having an edge length of
approximately 0.05 .mu.m to approximately 2 .mu.m. Crystalline
precipitation product particles with a scalenohedral form may be
produced in the online process, the particles having an edge length
of approximately 0.05 .mu.m to approximately 2 .mu.m and a diameter
of approximately 0.01 .mu.m to approximately 0.5 .mu.m. Spherical
crystalline precipitation product particles may be produced in the
online process.
[0056] The invention includes feeding the fibrous suspension to a
treatment unit comprising at least one of a fluffer, refiner, and
disperger. The loading of the fibers may occur before or after
feeding the fibrous suspension to the treatment unit. The treatment
unit is usable as a reactor for the chemical precipitation
reaction.
[0057] According to the invention, the fibrous suspension has a
stock consistency in the range of approximately 5% to approximately
60% during feeding, preferably in the range of approximately 15% to
approximately 35%. The invention includes adding calcium hydroxide
to the suspension before the feeding of the fibrous suspension to
the treatment unit.
[0058] According to the invention, the treatment unit comprises a
disperger with two plates disposed opposite to one another and
rotating relative to one another. The two plates comprise a rotor
and stator. A radially outer edge portion of a rotating portion of
the treatment unit has a circumferential speed of approximately 20
m/s to approximately 100 m/s, preferably approximately 40 m/s to
approximately 60 m/s. The two plates are separated by a gap of
approximately 0.5 mm to approximately 100 mm, preferably
approximately 25 mm to approximately 75 mm. The two plates have a
diameter of approximately 0.5 m to approximately 2 m.
[0059] According to the invention, crystalline precipitation
product particles are produced in the online process and the
dimensions of the crystalline precipitation product particles are
influenced in the treatment unit.
[0060] The invention includes diluting the fibrous suspension with
water in a radially outer area of the treatment unit.
[0061] According to the invention, the fibrous suspension guided
through the treatment unit has a stock consistency of approximately
0.1% to approximately 50%, preferably approximately 5% to
approximately 35%.
[0062] The invention includes maintaining a substantially constant
supply of carbon dioxide or a gas containing carbon dioxide into
the fibrous suspension. The invention further includes adding
carbon dioxide or a gas containing carbon dioxide to the fibrous
suspension at a pressure of approximately 0.1 bar to approximately
6 bar, preferably approximately 0.5 bar to approximately 3 bar.
[0063] The invention includes regulating or controlling a pH value
of the fibrous suspension by regulating or controlling a supply of
carbon dioxide, such that substantially all base materials of the
chemical precipitation reaction are converted to reaction products.
The invention further includes establishing the pH value in a range
of approximately 6 to approximately 10, preferably in the range of
approximately 7 to approximately 8.5. The invention further
includes introducing energy for the chemical precipitation reaction
in a range of approximately 0.3 kWh/t to approximately 8 kWh/t,
preferably in the range of range of approximately 0.5 kWh/t to
approximately 4 kWh/t.
[0064] The invention includes adding dilution water to the fibrous
suspension to obtain a diluted fibrous suspension with a stock
consistency of approximately 0.1% to approximately 16%, preferably
approximately 2% to approximately 6%.
[0065] According to the invention, the chemical precipitation
reaction has a reaction time of approximately 0.01 minute to
approximately 1 minute, preferably approximately 0.1 seconds to
approximately 10 seconds.
[0066] According to the invention, there is provided tissue product
made from the fibrous suspension according to the disclosed
method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] Two embodiments of the invention are shown purely by way of
example in a simplified diagrammatic representation in FIGS. 1 and
2.
[0068] FIG. 1 shows a diagrammatic representation of a first
embodiment of the invention.
[0069] FIG. 2 shows a diagrammatic representation of a second
embodiment of the invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0070] FIG. 1 shows an exemplary embodiment in which the fibrous
suspension 10 is first fed to the "Fiber Loading.TM." process 12
and subsequently is treated accordingly in a treatment unit 14
comprising, e.g., a refiner or the like. Subsequently, free calcium
carbonate can be washed out in a washing step 16, if necessary. As
described above, such a washing step 16 can be omitted. The fibrous
suspension 10 is subsequently fed to a tissue machine 18, where the
desired tissue or hygiene web 20 (and the respective final tissue
product) is obtained.
[0071] The exemplary embodiment shown in FIG. 2 differs from that
in FIG. 1 only in that the fibrous suspension 10 first is fed to
the treatment unit 14 comprising, e.g., a refiner or the like, and
then to the "Fiber Loading.TM." process. The washing step 16 is not
obligatory in this case either.
[0072] In both cases, the fibers contained in the fibrous
suspension 10 are directly loaded in an online process with a
filler in the tissue material preparation line by a chemical
precipitation reaction. Crystalline precipitation product particles
are produced in the online process. The precipitation product is
preferably calcium carbonate. Calcium oxide and/or calcium
hydroxide is added to the fibrous suspension to load the fibers.
The precipitation is then initiated through carbon dioxide or a gas
containing carbon dioxide (e.g., flue gas or the like). The
crystalline precipitation product particles are produced in the
respective gas atmosphere without the insertion of mixing energy.
The fibrous suspension can be fed to a treatment unit 14 comprising
a fluffer, a refiner, a disperger and/or the like. The fibers of
the fibrous suspension 10 can be loaded with filler before or after
the treatment unit 14. The treatment unit 14 can, at the same time,
act as a reactor for the chemical precipitation reaction.
LIST OF REFERENCE NUMBERS
[0073] TABLE-US-00001 10 Fibrous suspension 12 "Fiber Loading .TM."
process 14 Treatment unit 16 Washing step 18 Tissue machine 20
Tissue or hygiene web
* * * * *