U.S. patent application number 16/647990 was filed with the patent office on 2020-07-09 for coreless roll of absorbent sheet and method for manufacturing the same.
The applicant listed for this patent is Essity Hygiene and Health Aktiebolag. Invention is credited to Alain Bohn, Yves Enggasser, Frederic Roesch, Nicolas Weisang.
Application Number | 20200217018 16/647990 |
Document ID | / |
Family ID | 60857123 |
Filed Date | 2020-07-09 |
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United States Patent
Application |
20200217018 |
Kind Code |
A1 |
Weisang; Nicolas ; et
al. |
July 9, 2020 |
CORELESS ROLL OF ABSORBENT SHEET AND METHOD FOR MANUFACTURING THE
SAME
Abstract
A coreless roll of an absorbent sheet product such as napkins,
toilet paper, towels, etc., is provided made of a spirally wound
continuous web of absorbent material having a first end and a
second end, wherein a coating composition comprising a nonionic
cellulose ether is coated onto the second end. The coreless roll
has excellent stiffness and resistance to collapsing, as well as
sufficient flexibility and elasticity. Moreover, the coreless roll
has excellent disintegrability in water and can be used up over its
whole length. A process for the manufacture of the coreless roll is
also provided.
Inventors: |
Weisang; Nicolas; (Kunheim,
FR) ; Bohn; Alain; (Kunheim, FR) ; Roesch;
Frederic; (Kunheim, FR) ; Enggasser; Yves;
(Kunheim, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Essity Hygiene and Health Aktiebolag |
Goteborg |
|
SE |
|
|
Family ID: |
60857123 |
Appl. No.: |
16/647990 |
Filed: |
September 29, 2017 |
PCT Filed: |
September 29, 2017 |
PCT NO: |
PCT/IB2017/001405 |
371 Date: |
March 17, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 18/28 20130101;
D21H 27/002 20130101; D21H 27/30 20130101; A47K 2010/3206 20130101;
D21H 19/34 20130101; A47K 10/16 20130101 |
International
Class: |
D21H 27/00 20060101
D21H027/00; B65H 18/28 20060101 B65H018/28; A47K 10/16 20060101
A47K010/16; D21H 27/30 20060101 D21H027/30; D21H 19/34 20060101
D21H019/34 |
Claims
1. A coreless roll of an absorbent sheet product made of a spirally
wound continuous web of absorbent material having a first end and a
second end, the web of absorbent material being wound such as to
define an axial hollow passageway centrally positioned relative to
the coreless roll and extending from one edge to another edge of
the coreless roll and such that the first end is located on the
outer side of the roll and the second end is located at the axial
hollow passageway; wherein the second end of the continuous web of
absorbent material comprises a coating composition comprising a
nonionic cellulose ether.
2. The coreless roll of claim 1, wherein the coreless roll is
obtained by applying the coating composition to the second end of
the continuous web of absorbent material.
3. The coreless roll of claim 1, wherein the nonionic cellulose
ether has a number-average molecular weight of 1,000 to 1,000,000,
preferably of 2,000 to 500,000, more preferably of 3,000 to
200,000, more preferably 5,000 to 100,000.
4. The coreless roll of claim 1, wherein the nonionic cellulose
ether has a viscosity-average molecular weight of 5,000 to
2,000,000, preferably of 10,000 to 1,500,000, more preferably of
30,000 to 1,000,000.
5. The coreless roll of claim 1, wherein the nonionic cellulose
ether has a solubility in water at 25.degree. C. of at least 40
g/l.
6. The coreless roll of claim 1, wherein the nonionic cellulose
ether is an alkyl cellulose ether such as methylcellulose or
ethylcellulose.
7. The coreless roll of claim 1, wherein the nonionic cellulose
ether is a hydroxyalkyl cellulose ether such as hydroxyethyl
cellulose or hydroxypropyl cellulose.
8. The coreless roll of claim 1, wherein the nonionic cellulose
ether is a combination of an alkyl cellulose ether and a
hydroxyalkyl cellulose ether.
9. The coreless roll of claim 1, wherein the coating composition
comprises: (a) at least 50 wt.-%, preferably at least 65 wt.-%,
more preferably at least 80 wt.-% of the nonionic cellulose ether;
(b) not more than 50 wt.-%, preferably not more than 35 wt.-%, more
preferably not more than 20 wt.-% of further additives such as
plasticizers, reinforcing agents, fragrance, and dyes; each based
on the total solids content of the coating composition.
10. The coreless roll of claim 1, wherein the coating composition
is applied as an aqueous solution, wherein the aqueous solution
preferably contains the nonionic cellulose ether in an amount of at
least 0.1 wt.-%, more preferably at least 0.5 wt.-% based on the
total weight of the aqueous solution.
11. The coreless roll of claim 1, wherein the coating composition
is free of polyether polyol and/or free of other saccharides than
the nonionic cellulose ether.
12. The coreless roll of claim 1, wherein the axial hollow
passageway has a circumference and the coating composition is
circumferentially applied and is preferably applied such that the
resulting coating covers at least 50% of the second end, preferably
at least 75%, more preferably at least 95% of the second end.
13. The coreless roll of claim 1, wherein the coating composition
is applied continuously in the machine and axial direction or
intermittently in the machine and/or axial direction.
14. The coreless roll of claim 1, wherein the second end consists
of at least one turn, preferably of at least two turns, preferably
at least three turns, for instance 3 to 50 turns, for instance 3 to
30 turns or 4 to 40 turns, preferably 3 to 30 turns, a turn being
one circumvolution of the spirally wound continuous web about the
axial hollow passageway.
15. The coreless roll of claim 1, wherein the second end consists
of at least 5%, preferably at least 10%, more preferably at least
15% of the entire length of the continuous web of absorbent
material in the machine direction.
16. The coreless roll of claim 1, wherein the amount of nonionic
cellulose ether is from 0.001 to 20 g/roll, preferably 0.005 to 10
g/roll, more preferably 0.005 to 5 g/roll, in particular 0.01 to 2
g/roll.
17. The coreless roll of claim 1, wherein the web of absorbent
material is composed of 1 tissue paper ply or 2 to 6, in particular
2 to 5 superposed tissue paper plies.
18. The coreless roll of claim 1 being in a compressed form.
19. The coreless roll of claim 1, which is an absorbent product
chosen among the group comprising napkins, towels such as household
towels, kitchen towels or hand towels, toilet papers, wipes,
handkerchiefs, and facial tissues, wherein this absorbent product
is preferably a toilet paper.
20. A manufacturing method for manufacturing a coreless roll of an
absorbent sheet product comprising the steps of: conveying a
continuous web of absorbent material having a first end and a
second end, which is preferably composed of 1 tissue paper ply or 2
to 6, in particular 2 to 5 superposed tissue paper plies;
optionally severing the continuous web of absorbent material
substantially transversally to the machine direction to produce
single but coherent sheets; applying a coating composition as
defined in claim 1 to the second end; spirally winding the
continuous web of absorbent material so as to produce a log of web
of absorbent material, the web of absorbent material being wound
such as to define an axial hollow passageway centrally positioned
relative to the log and extending from one edge to another edge of
the log and such that the first end is located on the outer side of
the log and the second end is located at the axial hollow
passageway; and cutting the log into multiple coreless rolls.
21. The manufacturing method of claim 20, comprising the further
step of subjecting the coreless roll to compression in a direction
perpendicular to the axial hollow passageway to produce a coreless
roll in a compressed form.
22. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a national stage entry under 35
U.S.C. .sctn. 371 of, and claims priority to, International
Application No. PCT/162017/001405, filed Sep. 29, 2017, the
disclosure of which is hereby incorporated herein by reference in
its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a coreless roll of an
absorbent sheet product such as napkins, toilet paper, towels, etc.
In an aspect of the present invention, the coreless roll is
provided in a compressed form. The present invention also pertains
to a process for the manufacture of the coreless roll.
BACKGROUND OF THE INVENTION
[0003] Absorbent sheet products in rolled form find extensive use
in modern society. Rolls of toilet paper, towels such as household
(kitchen) towels or hand towels, etc., are staple items of
commerce.
[0004] Rolls of absorbent sheet product for home use (e.g., toilet
paper) typically consist of a continuous web of absorbent material
that is spirally wound around a prefabricated core made of a stiff
material such as cardboard or glued paper. The core defines an
axial hollow passageway, which is centrally positioned relative to
the roll and extends from one edge of the roll to the other edge.
The axial hollow passageway enables the consumer to easily mount
the roll on the spindle of a roll holder. However, the core is
expensive, requires storage space and additional manual handling.
Furthermore, the core remains after use of the absorbent sheet
product, thus increasing the risk of clogging sewage systems.
[0005] To address these concerns, "coreless" rolls and rolls with
water-soluble cores have been developed. Among the important
properties of these products are their resistance to collapsing and
their flexibility/elasticity.
[0006] "Collapsing", as used herein, refers to the phenomenon
occurring when the absorbent sheet product constituting the first
inner turns of the roll (i.e., the turns forming the axial hollow
passageway at winding start) cannot be stably maintained such that
an axial hollow passageway is clearly defined. Coreless rolls are
generally associated with an increased risk of "collapsing".
Collapsing typically occurs in the manufacture process of coreless
rolls when the temporary core is extracted after completing the
winding, or during storage and transport of the finished product.
As a consequence of collapsing, it may become difficult to mount
the roll on the spindle of a roll holder. Furthermore, collapsing
generally creates a feeling of decreased product quality among
consumers.
[0007] A "flexible" roll offers the benefit that it can be provided
in a compressed form, which requires less space during storage and
transport. As a result, storage and transport costs can be
significantly reduced. The roll can be returned from its compressed
(oval) form to the uncompressed (cylindrical) form by applying
pressure along the longer diameter of the compressed (oval) form,
i.e., perpendicular to the axis of the roll.
[0008] However, the absorbent sheet product constituting the first
inner roll turns must be stably maintained when the roll is
returned from the compressed form to the uncompressed form. That
is, the axial hollow passageway must open itself and be clearly
defined when the roll is returned to the cylindrical form. The roll
must hence exhibit substantial flexibility and a certain level of
elasticity, which means that the roll can be returned to its
cylindrical form while reopening the axial hollow passageway in a
clearly defined manner. This requires the first inner turns to
newly and stably maintain the axial hollow passageway. As a result,
there should be no substantially visible difference in appearance
between a roll that has been returned from the compressed form to
the uncompressed form and a roll that has not been previously
subjected to compression.
[0009] Furthermore, the roll can be subjected to deformation forces
during manufacturing, packaging, storage, transport, e.g., radial
forces exerted in the rewinding and/or cutting unit, axial forces
occurring during packaging and/or when packaged roll products are
stacked on pallets for storage/shipment, etc. As a consequence of
deformation forces, the continuous web of absorbent material can be
irreversibly deformed, thus creating a feeling of decreased quality
among consumers. Hence, the roll must also exhibit a certain level
of axial and radial stiffness (sometimes also referred to as
"rigidity") meaning that the roll is less likely to be deformed
and/or damaged during manufacturing, packaging, etc.
[0010] The prior art describes processes for achieving flexible
rolls of absorbent sheet product which can be provided in the
compressed form.
[0011] WO 2009/027874 A1 discloses a roll including a nonwoven
tissue web that is spirally wound around a flexible core. The
flexible core consists of a polymeric sheet of synthetic polymers,
which is attached to the inner layer of the nonwoven tissue web by
means of an attachment mechanism such as an adhesive, heat bonding,
etc. The flexible core is characterized by a higher tensile
strength in the machine direction than that of the nonwoven tissue
web. As a result, the roll exhibits flexibility for packaging and
storage purposes.
[0012] However, the polymer sheet of synthetic polymers is prepared
beforehand, stored, and manually handled. Furthermore, in the frame
of industrial manufacturing, the continuous web of absorbent
material is run at a speed of around 10 m/s. This renders the
incorporation and attachment of the polymer sheet to the inner
layer of the nonwoven tissue web technically complex and difficult
to implement at the running speed required for industrial
manufacturing.
[0013] WO 95/13183 A1 discloses a roll of elongated material having
a core at the center of the roll. The core essentially includes a
number of turns of the elongated material, which are fixed together
by means of a binder such as latex, starch, polyvinyl alcohol, etc.
WO 95/13183 A1 also discloses a process for producing such roll in
the compressed form. More specifically, WO 95/13183 A1 indicates
that a binder solution is sprayed or coated on the first turns of a
conventional winding. After complete winding and removal from the
winding shaft, the roll is immediately compressed to an elliptical
or oval section form. The document teaches that the roll can be
opened from the compressed position by applying pressure on the
"shorter" sides of the ellipse.
[0014] However, the binder as described in WO 95/13183 A1 (e.g.,
latex, starch, polyvinyl alcohol, etc.) produces a stiff core which
includes a number of turns of glued elongated material. Hence, the
resulting core lacks flexibility and shows low elasticity. As a
result, after the roll has been compressed, it is difficult to
reopen the axial hollow passageway in a manner leading to a
well-defined axial hollow passageway.
[0015] Moreover, the first inner turns of elongated material (i.e.,
the turns of elongated material forming the core) are cohesively
maintained together by the binder. The delamination force needed
for separating the first inner turns is generally greater than the
tear strength of the elongated absorbent material. It is hence
difficult to separate the first inner turns without tearing apart
the elongated absorbent material on which the binder is applied. As
a result, it is not possible to use the elongated absorbent
material on its whole length, e.g., up to the last sheet.
[0016] WO 2011/126707 A2 discloses an aqueous adhesive for
roll-shaped paper comprising (A) a saccharide, (B) a viscosity
modifier, and (C) a glycol and/or triol. The adhesive of WO
2011/126707 A2 is said to exhibit good initial adhesiveness while
it is wet and good peeling ability when it has dried. However, the
paper onto which the adhesive is applied exhibits some stiffness.
As a result, the roll-shaped paper product lacks flexibility and,
after the roll has been compressed, it is difficult to reopen the
axial hollow passageway in a manner leading to a well-defined axial
hollow passageway.
[0017] It is desired to provide a coreless roll of an absorbent
sheet product which combines an excellent stiffness (and thus also
resistance to collapsing) with a suitable delamination force but is
also sufficiently flexible and elastic.
[0018] It is also desired to provide a roll of an absorbent sheet
product which can be used over essentially its whole length (i.e.,
essentially up to the last sheet) and prevents sewage systems from
clogging up (disintegration time).
[0019] It is also desired to provide the coreless roll of an
absorbent sheet product in the compressed form wherein, after the
roll has been compressed, the axial hollow passageway can be
reopened in a manner leading to a well-defined axial hollow
passageway.
[0020] It is also desired to provide a process for manufacturing
such coreless roll of an absorbent sheet product.
SUMMARY OF THE INVENTION
[0021] The present invention relates to a coreless roll of an
absorbent sheet product such as napkins, toilet paper, towels, etc.
made of a continuous web of absorbent material having a first end
and a second end. The continuous web of absorbent material is wound
such as to define an axial hollow passageway centrally positioned
relative to the coreless roll and extending from one edge to
another edge of the coreless roll and such that the first end is
located on the outer side of the roll and the second end is located
at the axial hollow passageway.
[0022] The second end of the continuous web of absorbent material
comprises a coating composition comprising a nonionic cellulose
ether.
[0023] The present invention also relates to such coreless roll
which is provided in the compressed form.
[0024] The present invention also relates to a process for the
manufacture of a coreless roll of an absorbent sheet product
comprising the steps of:
[0025] conveying a continuous web of absorbent material having a
first end and a second end, which is preferably composed of 1
tissue paper ply or 2 to 6, in particular 2 to 5 superposed tissue
paper plies;
[0026] applying a coating composition comprising a nonionic
cellulose ether to the second end;
[0027] spirally winding the continuous web of absorbent material so
as to produce a log of web of absorbent material, the continuous
web of absorbent material being wound such as to define an axial
hollow passageway centrally positioned relative to the log and
extending from one edge to the other edge of the log and such that
the first end is located on the outer side of the log and the
second end is located at the axial hollow passageway;
[0028] cutting the log into multiple coreless rolls; and
[0029] optionally subjecting the coreless roll to compression in a
direction perpendicular to the axial hollow passageway to produce a
coreless roll in a compressed form.
[0030] In one aspect of the present invention, the nonionic
cellulose ether has a number-average molecular weight of 1,000 to
1,000,000, preferably of 2,000 to 500,000, more preferably of 3,000
to 200,000, more preferably 5,000 to 100,000.
[0031] In another aspect of the present invention, the nonionic
cellulose ether is an alkyl cellulose ether such as methyl
cellulose or ethyl cellulose. In yet another aspect of the present
invention, the nonionic cellulose ether is a hydroxyalkyl cellulose
ether such as hydroxyethyl cellulose or hydroxypropyl
cellulose.
[0032] The coreless roll of an absorbent sheet product of the
present invention is distinguished by an excellent stiffness and
resistance to collapsing, while being as well sufficiently flexible
and elastic. Moreover, the coreless roll of the present invention
also exhibits excellent disintegrability in water and can be used
up over its whole length.
[0033] The present invention according to an aspect includes the
following exemplary embodiments ("Items"):
1. A coreless roll of an absorbent sheet product made of a spirally
wound continuous web of absorbent material having a first end and a
second end, the web of absorbent material being wound such as to
define an axial hollow passageway centrally positioned relative to
the coreless roll and extending from one edge to another edge of
the coreless roll and such that the first end is located on the
outer side of the roll and the second end is located at the axial
hollow passageway; wherein the second end of the continuous web of
absorbent material comprises a coating composition comprising a
nonionic cellulose ether. 2. The coreless roll of item 1, wherein
the coreless roll is obtained by applying the coating composition
to the second end of the continuous web of absorbent material. 3.
The coreless roll of item 1 or 2, wherein the nonionic cellulose
ether has a number-average molecular weight of 1,000 to 1,000,000,
preferably of 2,000 to 500,000, more preferably of 3,000 to
200,000, more preferably 5,000 to 100,000. 4. The coreless roll of
claim 1 or 2, wherein the nonionic cellulose ether has a
viscosity-average molecular weight of 5,000 to 2,000,000,
preferably of 10,000 to 1,500,000, more preferably of 30,000 to
1,000,000. 5. The coreless roll of any of items 1 to 4, wherein the
nonionic cellulose ether has a solubility in water at 25.degree. C.
of at least 40 g/I. 6. The coreless roll of any of items 1 to 5,
wherein the nonionic cellulose ether is an alkyl cellulose ether
such as methylcellulose or ethylcellulose. 7. The coreless roll of
any of claims 1 to 5, wherein the nonionic cellulose ether is a
hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or
hydroxypropyl cellulose. 8. The coreless roll of any of items 1 to
5, wherein the nonionic cellulose ether is a combination of an
alkyl cellulose ether and a hydroxyalkyl cellulose ether. 9. The
coreless roll of any of items 1 to 8, wherein the coating
composition comprises:
[0034] (a) at least 50 wt.-%, preferably at least 65 wt.-%, more
preferably at least 80 wt.-% of the nonionic cellulose ether;
[0035] (b) not more than 50 wt.-%, preferably not more than 35
wt.-%, more preferably not more than 20 wt.-% of further additives
such as plasticizers, reinforcing agents, fragrance, and dyes;
[0036] each based on the total solids content of the coating
composition.
10. The coreless roll of any of items 1 to 9, wherein the coating
composition is applied as an aqueous solution, wherein the aqueous
solution preferably contains the nonionic cellulose ether in an
amount of at least 0.1 wt.-%, more preferably at least 0.5 wt.-%
based on the total weight of the aqueous solution. 11. The coreless
roll of any of items 1 to 10, wherein the coating composition is
free of polyether polyol and/or free of other saccharides than the
nonionic cellulose ether. 12. The coreless roll of any of items 1
to 11, wherein the axial hollow passageway has a circumference and
the coating composition is circumferentially applied and is
preferably applied such that the resulting coating covers at least
50% of the second end, preferably at least 75%, more preferably at
least 95% of the second end. 13. The coreless roll of any of items
1 to 12, wherein the coating composition is applied continuously in
the machine and axial direction or intermittently in the machine
and/or axial direction. 14. The coreless roll of any of items 1 to
13, wherein the second end consists of at least one turn,
preferably of at least two turns, preferably at least three turns,
for instance 3 to 50 turns, for instance 3 to 30 turns or 4 to 40
turns, preferably 3 to 30 turns, a turn being one circumvolution of
the spirally wound continuous web about the axial hollow
passageway. 15. The coreless roll of any of items 1 to 13, wherein
the second end consists of at least 5%, preferably at least 10%,
more preferably at least 15% of the entire length of the continuous
web of absorbent material in the machine direction. 16. The
coreless roll of any of items 1 to 15, wherein the amount of
nonionic cellulose ether is from 0.001 to 20 g/roll, preferably
0.005 to 10 g/roll, more preferably 0.005 to 5 g/roll, in
particular 0.01 to 2 g/roll. 17. The coreless roll of any of items
1 to 16, wherein the web of absorbent material is composed of 1
tissue paper ply or 2 to 6, in particular 2 to 5 superposed tissue
paper plies. 18. The coreless roll of any of items 1 to 17 being in
a compressed form. 19. The coreless roll of any of items 1 to 18,
which is an absorbent product chosen among the group consisting of
napkins, towels such as household towels, kitchen towels or hand
towels, toilet papers, wipes, handkerchiefs, and facial tissues,
wherein this absorbent product is preferably a toilet paper. 20. A
manufacturing method for manufacturing a coreless roll of an
absorbent sheet product comprising:
[0037] conveying a continuous web of absorbent material having a
first end and a second end, which is preferably composed of 1
tissue paper ply or 2 to 6, in particular 2 to 5 superposed tissue
paper plies;
[0038] optionally severing the continuous web of absorbent material
substantially transversally to the machine direction to produce
single but coherent sheets;
[0039] applying a coating composition as defined in any of items 1
to 16 to the second end;
[0040] spirally winding the continuous web of absorbent material so
as to produce a log of web of absorbent material, the web of
absorbent material being wound such as to define an axial hollow
passageway centrally positioned relative to the log and extending
from one edge to another edge of the log and such that the first
end is located on the outer side of the log and the second end is
located at the axial hollow passageway; and
[0041] cutting the log into multiple coreless rolls.
21. The manufacturing method of item 20, further comprising:
[0042] subjecting the coreless roll to compression in a direction
perpendicular to the axial hollow passageway to produce a coreless
roll in a compressed form.
22. Use of the coreless roll of any of item 1 to 19 as toilet
paper, household towel, kitchen towel, hand towel, wipe, facial
tissue, handkerchief or napkin.
[0043] Where the present description refers to "preferred"
embodiments/features, combinations of these "preferred"
embodiments/features shall also be deemed as disclosed as long as
this combination of "preferred" embodiments/features is technically
meaningful.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 is a schematic drawing showing a perspective view of
a coreless roll according to an embodiment of the present
invention.
[0045] FIG. 2 is a schematic drawing showing a lateral view of a
coreless roll according to an embodiment of the present invention.
The second end as represented in FIG. 2 has three turns.
[0046] FIG. 3 is a schematic drawing of the second end of an
unwound continuous web of absorbent material according to an
embodiment of the present invention. The grey shading in FIG. 3
represents the coating composition which is applied continuously
onto the second end.
[0047] FIGS. 4a and 4b are schematic drawings of the second end of
an unwound continuous web of absorbent material according to an
embodiment of the present invention. The grey shading in FIGS. 4a
and 4b represents the coating composition which is applied
intermittently onto the second end, as stripes and dots,
respectively.
[0048] FIGS. 1 to 4b give a survey on the terminology used with
respect to the coreless roll of embodiments of the present
invention. In FIGS. 1 to 4b the following reference numbers
represent: [0049] (1) Coreless roll [0050] (2) Spirally wound
continuous web of absorbent material [0051] (3) Axial hollow
passageway [0052] (4) Edge [0053] (5) First end [0054] (6) Second
end [0055] (7) Coating composition [0056] (8) Perforation line
[0057] FIG. 5 is a schematic drawing showing a cross-section view
of a converting machine (9) illustrating the manufacturing of
coreless rolls according to one embodiment of the invention. FIG. 5
shows the application of the coating composition onto the
continuous web of absorbent material by spraying.
[0058] FIG. 6 is a schematic drawing showing a cross-section view
of a converting machine (9) illustrating the manufacturing of
coreless rolls according to another embodiment of the invention.
FIG. 6 shows the application of the coating composition onto the
continuous web of absorbent material by roll-coating.
[0059] FIGS. 7a, 7b and 7c are schematic drawings of an apparatus
(dynamometer) (39) and a shaft assembly (40)-(43) suitable for
measuring the intersheet adhesion (delamination force) of a tissue
paper roll (44) according to the present invention. The dimensions
in FIGS. 7a-7c are given in mm.
DETAILED DESCRIPTION OF THE INVENTION
1. Coreless Roll
[0060] The coreless roll of an absorbent sheet product of the
present invention according to one embodiment is made of a spirally
wound continuous web of absorbent material having a first end and a
second end.
[0061] The continuous web of absorbent material may be made of a
base tissue paper which can be obtained by the Conventional Wet
Press or the Through Air Drying (TAD) manufacturing method or other
manufacturing methods. As used herein, "base (raw) tissue paper"
("tissue paper web") means the one-ply base tissue as obtained from
the tissue machine. The base tissue paper has a low basis weight,
in the range of 8 to 60 g/m.sup.2, preferably 10 to 30
g/m.sup.2.
[0062] The term "ply" as used herein refers to the one or more
plies of tissue paper in the final tissue paper product (e.g.,
toilet paper) as is/are obtained after processing ("converting")
one or more base tissue paper webs.
[0063] Based on the underlying compatibility of the production
processes (wet forming), "tissue" production is counted among the
papermaking techniques. The production of tissue is distinguished
from paper production by its extremely low basis weight and its
much higher tensile energy absorption index.
[0064] The tensile energy absorption index is arrived at from the
tensile energy absorption in which the tensile energy absorption is
related to the test sample volume before inspection (length, width,
thickness of sample between the clamps before tensile load). Paper
and tissue paper also differ in general with regard to the modulus
of elasticity that characterizes the stress-strain properties of
these planar products as a material parameter.
[0065] A tissue's high tensile energy absorption index results from
outer or inner creping. The former is produced by compression of
the paper web adhering to a dry cylinder as a result of the action
of a crepe doctor or in the latter instance as a result of a
difference in speed between two wires ("fabrics"). This causes the
still moist, plastically deformable paper web to be internally
broken up by compression and shearing, thereby rendering it more
stretchable under load than an uncreped paper. A high tensile
energy absorption index can also be achieved by imparting to the
tissue a 3D structure by means of the wires themselves. Most of the
functional properties typical of tissue and tissue products result
from the high tensile energy absorption index (see DIN EN 12625-4
and DIN EN 12625-5).
[0066] Typical properties of tissue paper include the ready ability
to absorb tensile stress energy, their drapability, good
textile-like flexibility, properties which are frequently referred
to as bulk softness, a high surface softness, a high specific
volume with a perceptible thickness, as well as high liquid
absorbency and, depending on the application, a suitable wet and
dry strength as well as an interesting visual appearance of the
outer product surface. These properties allow tissue paper to be
used, for example, as cleaning cloths (e.g., household towels),
sanitary products (e.g., toilet paper, hand towels) and wipes
(e.g., cosmetic wipes, facial tissues).
[0067] According to one embodiment of the present invention, the
continuous web of absorbent material is preferably composed of 1
tissue paper ply or 2 to 5 superposed tissue paper plies.
[0068] The tissue paper can be produced from paper-making fibers
according to "Conventional Processes" as in the manufacture of "Dry
Crepe Tissue" or "Wet Crepe Tissue" or "Processes for Structured
Tissue" such as the Through Air Drying (TAD) manufacturing method,
the manufacture of uncreped through-air dried (UCTAD) tissue, or
alternative manufacturing methods, e.g., the Advanced Tissue
Molding System (ATMOS) of the company Voith, or Energy Efficient
Technologically Advanced Drying eTAD of the company Georgia
Pacific, or Structured Tissue Technology SST of the company Metso
Paper. Hybrid processes like NTT (New textured Tissue) which are
alterations of the conventional processes can be used, too.
[0069] The conventional dry crepe manufacturing method
comprises:
[0070] pressing and drying the wet paper fibers as a sheet on a
large-diameter, heated cylinder (also called Yankee dryer); and
[0071] subsequently detaching and creping the sheet of dried paper
fibers by means of a metal blade applied against said cylinder,
across its direction of rotation.
[0072] The creping operation creates undulations in the sheet
across its direction of travel. The creping operation increases the
thickness of the sheet, and confers elasticity and gives touch
(soft touch) properties to the sheet.
[0073] The TAD manufacturing method comprises:
[0074] molding the sheet of wet paper fibers on a fabric; and
[0075] subsequently drying the sheet, at least partly, by means of
a current of hot air passing through it.
[0076] Subsequently, the dried sheet may be creped.
[0077] Further, in the manufacture of a tissue web (as preferred
embodiment of the continuous web of absorbent material to be used),
a process as described in WO 2016/173641 A1 (title: "Tissue paper
comprising pulp fibers originating from Miscanthus and method for
manufacturing the same", incorporated herein by reference) can be
used. Specifically, reference is made is to the description below
according to item 3 and details of the TAD process (e.g.,
3-D-shaped fabric, permeable drying cylinder, etc.) disclosed
therein. The parameters described in this passage are also valid
for the use of the ATMOS technology.
[0078] Once the tissue paper has been manufactured, a distinct
manufacturing operation called converting operation is typically
employed to form the tissue paper product (i.e., the paper towel,
toilet tissue rolls, bathroom tissue, wiping tissue, kitchen tissue
rolls, handkerchiefs, etc.).
[0079] In one further embodiment of the continuous web of absorbent
material the absorbent material is a "nonwoven material". The term
"nonwoven" is very common in the art and can be further defined in
the manner described in ISO 9092:2011, also for the purpose of the
present invention. Typical nonwoven manufacturing techniques
include the air-laid technology, spun-laid technology, dry-laid
technology, and wet-laid long fibers technology. The nonwoven web
used according to this embodiment can be a single ply or multi-ply
web.
[0080] According to one aspect of this embodiment, the absorbent
nonwoven-based web used in the coreless roll of the invention
comprises cellulosic fibers. In this case, the content of the
cellulosic fibers, based on the total weight of all fibers present
in the nonwoven web, is at least 20 wt.-%, more preferably at least
50 wt.-%, for instance at least 80 wt.-%. The remaining fibers are
in these cases non-cellulosic fibers such as synthetic fibers.
[0081] The aforementioned paper-making fibers (which can also be
referred to as "cellulosic fibers") can be produced from virgin
and/or recycled paper pulp raw material. The cellulosic fibers
which can be used in the invention typically contain as main
structure-building component the long chain fibrous cellulose
portion which is present in naturally occurring
cellulose-containing cells, in particular those of lignified
plants. Preferably, the fibers are isolated from lignified plants
by digestion steps removing or reducing the content of lignin and
other extractables and optional bleaching steps. The cellulosic
fibers can also stem from non-wood sources such as annual
plants.
[0082] Suitable cellulosic fibers which can be used may be of
regenerated type (e.g., Lyocell), although the use of other types
of pulps is preferred. The pulps employed can be a primary fibrous
material ("virgin fibers") or a secondary fibrous material
(recycled pulps). The pulp can stem from lignin-free or low lignin
sources, such as cotton linters, esparto (alfa) grass, bagasse
(e.g., cereal straw, rice straw, bamboo, or hemp), kemp fibers,
Miscanthus grass fibers, or flax (also referred to as "non-wood
fibers" in the description and the claims). Preferably the pulp is
produced from ligno-cellulosic material, such as softwood (which
typically originates from conifers) or hardwood (typically from
deciduous trees).
[0083] It is possible to use "chemical pulps" or "mechanical
pulps", whereby the use of chemical pulps may be preferred in one
embodiment.
[0084] "Chemical pulps", as used herein, are, according to DIN
6730, fibrous materials obtained from plant raw materials of which
most non-cellulosic components have been removed by chemical
pulping without substantial mechanical post treatment. "Mechanical
pulp", as used herein, is the general term for fibrous material
made of wood entirely or almost entirely by mechanical means,
optionally at increased temperatures. Mechanical pulp can be
subdivided into the purely mechanical pulps (groundwood pulp and
refined mechanical pulp) as well as mechanical pulps subjected to
chemical pre-treatment, such as chemo-mechanical pulp (CMP), or
chemo-thermo mechanical pulp (CTMP).
[0085] According to one embodiment of the present invention,
referring to FIGS. 1 and 2, the continuous web of absorbent
material (2) is spirally wound such as to define an axial hollow
passageway (3) centrally positioned relative to the roll (1), and
which extends from one edge (4) to the other edge (4) of the roll.
As used herein, "axial hollow passageway" means a tubular opening
that extends through the roll along its central axis. The axial
hollow passageway enables the end user to mount the roll on the
spindle of a roll holder. When the roll is mounted on the spindle
of a roll holder, the absorbent material is dispensed from the
first end (located at the outside of the roll) while the roll is
allowed to freely rotate about its central axis. The axial hollow
passageway has a diameter of from 10 mm to 70 mm, preferably from
20 to 50 mm.
[0086] In the present invention according to one embodiment, the
axial hollow passageway (3) extends from one edge (4) to the other
edge (4) of the coreless roll. The coreless roll of the present
invention has a cylinder-shaped circumferential surface and
opposite flat ends (i.e., edges), which are formed when the log
roll is cut into multiple rolls at the end of the winding process.
As used herein, "edge" means the flat portion which is located on
one side of the roll perpendicular to its center axis.
[0087] In the present invention according to one embodiment, the
continuous web of absorbent material (2) has a first end (5) and a
second end (6). The first end (5) is located at the outside of the
roll and the second end (6) is located at the axial hollow
passageway (3). Hence, the continuous web of absorbent material
consists, in the machine direction, of the first end and the second
end and a middle portion located between these ends. The combined
lengths of the first end, the second end and the middle portion
define the length of the continuous web of absorbent material which
forms one roll. In the coreless roll of the present invention
according to one embodiment, the continuous web of absorbent
material web comprises the coating composition described in the
present application. The continuous web of absorbent material web
may be obtained by applying the coating composition to the second
end. This leads to a continuous web of absorbent material web
wherein the remaining portions, i.e., the first end and the middle
portion may be essentially or completely free of coating
composition. The resulting continuous web of absorbent material web
hence can be distinguished from known continuous webs of absorbent
material, e.g., lotioned toilet paper, in which the same coating
composition (e.g., lotion) is applied to the entire continuous
web.
[0088] However, this does not exclude that the coating composition
in the sense of the invention is applied to the second end of the
continuous web of absorbent material while in addition a lotion
(which necessarily differs from the coating composition) is applied
to one side of the entire continuous web of absorbent material.
[0089] Further embodiments of the coreless roll making also use of
the concept of the present invention relate to a continuous web of
absorbent material obtained by applying the coating composition to
the second end thereof wherein a part of the remaining portions,
i.e., the first end and the middle portion, preferably less than
20%, more preferably less than 10%, more preferably less than 5% of
the total area of the remaining portion also carry a coating
composition, such as the same coating composition as applied to the
second end.
[0090] In one embodiment, the second end (6) consists of at least
one turn, preferably at least two turns, more preferably at least
three turns, for instance three to fifty turns, for instance three
to thirty turns or four to forty turns, preferably three to thirty
turns or ten to forty turns. As used herein, "turn" means one
circumvolution of the spirally wound continuous web about the axial
hollow passageway. FIG. 2 shows for instance three turns at the
second end (6) of the web.
[0091] In one further embodiment, the second and (6) consists of at
least 5%, more preferably at least 10%, more preferably at least
15% of the entire length of the continuous web of absorbent
material in the machine direction, and preferably not more than
40%, more preferably not more than 35% of the entire length of the
continuous web of absorbent material in the machine direction.
[0092] In one embodiment, the coreless roll of the present
invention is provided in a compressed form. As used herein,
"compressed form" means a form in which the roll cross section has
an oval shape. When the roll is in the compressed form, the axial
hollow passageway adopts the shape of a thin, typically oval slit
and is no longer able to receive the spindle of a roll holder. As a
result, the roll requires less space and storage and transport
costs can be reduced. The coreless roll of the present invention
can be returned from the compressed form (oval) to the uncompressed
form (cylindrical) by applying pressure along the longer side
(diameter) of the oval-shaped roll, i.e., perpendicular to the axis
of the roll.
2. Coating Composition
[0093] In the present invention according to one embodiment, a
coating composition comprising a nonionic cellulose ether is
applied to the second end of the continuous web of absorbent
material. The nonionic cellulose ether is described in more detail
in section 2.1 below.
[0094] The coating composition can be applied to the continuous web
of absorbent material as an aqueous solution. This means that water
is added to the coating composition and used as solvent for the
nonionic cellulose ether and the further additives, if present. The
aqueous solution of the coating composition preferably contains the
nonionic cellulose ether in a total amount of at least 0.1 wt.-%,
preferably at least 0.5 wt.-%, more preferably at least 1 wt.-%
based on the total weight of the aqueous solution. Further
additives such as plasticizers, reinforcing agents, fragrance,
dyes, etc., may also be present. In this case, the preferred
contents thereof explained below in connection with component (b)
can also be employed (but refer to the total dry content of the
aqueous solution).
[0095] Water may be present in an amount which is greater than 50
wt.-%, and more preferably in an amount greater than 65 wt.-%, more
preferably greater than 80 wt.-%, based on the total weight of the
aqueous solution.
[0096] This aqueous solution of the coating composition can be
applied as it is, preferably at room temperature, to the second
end, e.g., by spraying, roll-coating, or any other suitable
application method known in the art. After the application of the
aqueous solution, the continuous web of absorbent material can be
dried, for instance by longer storage at ambient conditions or
other suitable techniques known in the art.
[0097] In one embodiment, the coating composition usable in the
present invention comprises:
[0098] (a) at least 50 wt.-% of the said nonionic cellulose ether,
preferably at least 65 wt.-%, more preferably at least 80 wt.-%,
more preferably at least 85 wt.-%, more preferably at least 90
wt.-%, more preferably at least 95 wt.-%;
[0099] (b) not more than 50 wt.-%, preferably not more than 35
wt.-%, preferably not more than 20 wt.-%, more preferably not more
than 15 wt.-%, more preferably not more than 10 wt.-%, more
preferably not more than 5 wt.-% of further additives such as
plasticizers, reinforcing agents, fragrance, dyes, etc.;
[0100] each based on the total weight (total dry content) of the
coating composition.
[0101] In one further embodiment, the coating composition consists
of these ingredients in the stated amounts. In one further
preferred embodiment the coating composition consists of the
nonionic cellulose ether.
[0102] In one embodiment, the coating composition of the present
invention is free of polyether polyol and/or free of other
saccharides than the nonionic cellulose ether. The term
"saccharide" is to be understood broadly and includes
monosaccharides, disaccharides, oligosaccharides (at least 3
saccharide units) and polysaccharides such as starch as well as
saccharide-based polymers other than the nonionic cellulose ether,
e.g., carboxymethyl cellulose (CMC).
[0103] In the present invention according to one embodiment, the
coating composition may be applied onto at least one of the two
sides of the continuous web, i.e., the upper and/or the lower side
of the continuous longitudinal web. The "upper" side may be the
side of the continuous web that is oriented towards the outside of
the roll when the web is spirally wound. In one embodiment the
coating composition is applied onto the lower side, i.e., the side
oriented towards the axial hollow passageway.
[0104] The coating composition may be applied onto the continuous
web before it is spirally wound to produce the roll. As a result of
winding, the coating composition is applied circumferentially with
respect to the axial hollow passageway. In the present invention,
the coating composition is preferably applied onto the web such
that, with respect to the total area of the second end (i.e., the
area carrying the resulting coating), at least 50%, preferably at
least 75%, and in particular at least 95% are coated.
[0105] If the coating is applied to the second end of the web
intermittently in the machine and/or axial direction, for instance
with respect to the individual circumvolutions of the web about the
axial hollow passageway, i.e., if one or more circumvolutions are
not fully coated when viewed from the edges of the roll, it is also
preferred that the area carrying the resulting coating constitutes
at least 50% of the total coated area, preferably at least 75%, and
in particular at least 95% of the total area of the second end.
[0106] In the present invention according to one embodiment, the
coating composition can be applied onto the second end of the
continuous web to provide a full or partial coating. As used
herein, "full coating" means a coating that is applied continuously
in the machine and the axial (cross) direction, i.e., the second
end of the web does not include any uncoated portions (see, e.g.,
FIG. 3).
[0107] As used herein, "partial coating" means that the coating
composition is applied onto the continuous web such that it
partially covers the surface of the web (i.e., its second end). A
partial coating occurs for instance if the coating is applied to
the second end of the web intermittently in the machine and/or
axial direction. The coating composition can be applied onto the
web so as to form predetermined coating patterns. There is no
particular limitation to the predetermined coating pattern. The
partial coating may form coherent (e.g., stripes, lines, or waves)
or separate deposits (e.g., dots, squares, circles or any other
geometric shape).
[0108] In one embodiment of a partial coating, the coating is
applied intermittently in the machine and/or axial direction,
e.g.,
[0109] continuously in the machine direction, but intermittently in
the axial (cross) direction, e.g. in the form of one or more
parallel stripes running in the machine direction (see, e.g., FIG.
4a),
[0110] continuously in the axial (cross) direction, but
intermittently in the machine direction, e.g., in the form of one
or more parallel stripes running in the axial direction, i.e., from
one edge of the roll to the other edge,
[0111] intermittently in the machine and axial (cross) direction,
e.g., in the form of parallel stripes crossing each other.
[0112] In one embodiment of a partial coating, the coating is
applied intermittently in the form of dots as shown in FIG. 4b. The
dots can form a regular or irregular pattern, as results, e.g.,
from spraying or roll-coating.
[0113] In one embodiment, the coating composition is intermittently
applied such that it covers at least 35% of the second end surface,
preferably at least 50% of the second end surface, and more
preferably at least 75%, e.g., at least 95% of the total surface of
the second end.
2.1 Nonionic Cellulose Ether
[0114] In embodiments of the present invention, the coating
composition comprises a nonionic cellulose ether to accomplish the
desired technical effects.
[0115] In accordance with an exemplary embodiment of the present
invention, the cellulose ethers to be used are described as
follows. Cellulose ethers are polymers derived from cellulose,
which are formed by substituting (fully or partially) the hydroxyl
groups of cellulose. The use of one etherification agent
(alkylating agent) in the substitution process results in a simple
cellulose ether, whereas using different kinds of agents leads to
mixed cellulose ethers (mixed ethers). The extent of substitution
is described as the degree of substitution (DS) defined as the
average number of hydroxyl groups substituted per anhydroglucose
unit. The DS can vary between >0 and 3. If an etherification
(alkylating) agent such as an alkylene oxide etherification agent
is used, a new hydroxyl group can be generated, and can further
react to give oligomeric chains. In this case, the extent of
substitution is described as the molar substitution (MS) defined as
the average number of moles of etherification agent combined per
mole of anhydroglucose unit.
[0116] The degree of substitution (DS) and the molar substitution
(MS) of (ionic or nonionic) cellulose ethers can be determined by
techniques known in the art, e.g., by .sup.13C NMR or by the Zeisel
gas chromatography (Zeisel-GC) method as described by Hodges et al.
in Anal. Chem., 1979, 51(13), 2172-2176.
[0117] Cellulose ethers are divided into two categories, namely
ionic cellulose ethers and nonionic cellulose ethers. Cellulose
ethers of the ionic type, e.g., sodium carboxymethyl cellulose
(CMC), contain substituents that are electrically charged, whereas
cellulose ethers of the nonionic type, e.g., methyl cellulose,
hydroxypropyl cellulose, etc., carry electrically neutral
substituents. The cellulose ethers used in the present invention
are of the nonionic type.
[0118] Without being bound to any theory, it is believed that
nonionic cellulose ethers provide a fine-tuned degree of adhesion
between the coating composition and the elongated absorbent
material. As a result, it is possible to achieve excellent
stiffness and resistance to collapsing as well as sufficient
flexibility and elasticity. Furthermore, the delamination force can
be maintained in an acceptable range, and hence it is possible to
use the elongated absorbent material on its whole length, i.e., up
to the last sheet. On the other hand, ionic cellulose ethers such
as CMC can adhere strongly to the absorbent material, if they are
used in greater amounts, so that the delamination force needed for
the separating the first inner turns may become greater than the
tear strength of the elongated absorbent material. As a result, it
may become difficult to separate the first inner turns without
tearing apart the elongated absorbent material.
[0119] As used herein, the term "nonionic cellulose ether" is to be
understood broadly and includes all types of cellulose
ethers--e.g., e.g., alkyl cellulose ethers, hydroxyalkyl cellulose
ethers, alkyl hydroxyalkyl cellulose ethers, and mixed ethers
thereof--provided that they are nonionic.
[0120] In one embodiment, the nonionic cellulose ether has a
number-average molecular weight of 1,000 to 2,000,000, e.g., 1,000
to 1,000,000, preferably of 2,000 to 800,000, e.g., 2,000 to
500,000, more preferably of 3,000 to 200,000, more preferably 5,000
to 100,000. The number-average molecular weight of the nonionic
cellulose ether used in the present invention can be determined by
techniques known in the art, such as Gel Permeation Chromatography
(GPC).
[0121] In one embodiment, the nonionic cellulose ether has a
viscosity-average molecular weight of 5,000 to 2,000,000,
preferably of 10,000 to 1,500,000, more preferably of 30,000 to
1,000,000. The viscosity-average molecular weight of the nonionic
cellulose ether used in the present invention can be determined by
techniques known in the art, such as viscometry.
[0122] In one further embodiment, the nonionic cellulose ether is
an alkyl cellulose ether such as methyl cellulose or ethyl
cellulose. As used herein, "alkyl cellulose ether" is to be
understood as a (nonionic) cellulose ether, wherein some of the
hydroxyl groups of cellulose (at least one hydroxyl group in one
individual anhydroglucose unit) are substituted with an alkyl
group, i.e., an linear or branched alkyl group having from 1 to 20
carbon atoms, preferably from 1 to 12 carbon atoms, more preferably
from 1 to 6 carbon atoms, in particular a methyl group, an ethyl
group or a propyl group. Furthermore, as used herein, the
expression "alkyl cellulose ether" is meant to encompass alkyl
cellulose ethers such as methyl cellulose or ethyl cellulose as
well as their mixed ethers such as hydroxyalkyl methyl celluloses,
e.g., hydroxyethyl methyl cellulose.
[0123] In one embodiment, the nonionic cellulose ether is an alkyl
cellulose ether selected from methyl cellulose (MC), mixed ethers
of MC such as hydroxyethyl methyl cellulose (HEMC), hydroxypropyl
methyl cellulose (HPMC) and hydroxybutyl methyl cellulose (HBMC),
ethyl cellulose (EC), mixed ethers of EC such as hydroxyethyl ethyl
cellulose (HEEC), hydroxypropyl ethyl cellulose (HPEC) and
hydroxybutyl ethyl cellulose (HBEC). Preferably, the alkyl
cellulose ether is MC, EC, or HPMC, more preferably MC or EC.
[0124] MC as used herein can have a DS of 1.4 to 2.4, preferably of
1.6 to 2.0. HEMC as preferably used herein can have a (methyl) DS
of 1.3 to 2.2 and a (hydroxyalkyl) MS of 0.06 to 0.5. HPMC as
preferably used herein can have a DS of 1.1 to 2.0 and a MS of 0.1
to 1.0. HBMC as preferably used herein typically has a DS greater
than 1.9 and not more than 2.4 and a MS greater than 0.04 and not
more than 0.6. EC as preferably used herein can have a (ethyl) DS
of 1.0 to 2.5, preferably a DS of 1.1 to 1.5.
[0125] In another embodiment, the nonionic cellulose ether is a
hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or
hydroxypropyl cellulose. As used herein, "hydroxyalkyl cellulose
ether" is to be understood as a (nonionic) cellulose ether, wherein
some of the hydroxyl groups of cellulose are substituted with a
hydroxyalkyl group, e.g., a linear or branched hydroxyalkyl group
having from 1 to 20 carbon atoms, preferably from 1 to 12 carbon
atoms, more preferably from 1 to 6 carbon atoms such as a
(2-)hydroxypropyl group or a hydroxyethyl group.
[0126] In one embodiment, the nonionic cellulose ether is a
hydroxyalkyl cellulose ether selected from hydroxyethyl cellulose
(HEC), hydroxypropyl cellulose (HPC) and hydroxybutyl cellulose
(HBC). Preferably, the hydroxyalkyl cellulose ether is HEC or HPC,
more preferably HPC. HEC as used herein can have a MS of 0.1 to
3.6, preferably of 1.5 to 3.5. HPC as used herein can have a MS of
1.0 to 3.8, preferably of 2.0 to 3.6.
[0127] The definition of "nonionic cellulose ether" as used herein,
also includes a blend (combination) of at least two, e.g., 2, 3 or
4, different nonionic cellulose ethers, especially a blend of an
alkyl cellulose ether and a hydroxyalkyl cellulose ether such as a
blend of MC and HPC.
[0128] In one embodiment, the nonionic cellulose ether exhibits a
solubility in water at 25.degree. C. of at least 40 g/l, preferably
200 g/l, in particular 500 g/l. The solubility of the nonionic
cellulose ether in water ensures that the absorbent sheet product
of the present invention (in particular toilet paper, etc.) has
good flushability and biodegradability. Due to the fairly high
solubility of the nonionic cellulose ether it dissolves upon
contact with water in the sewage system, or at least quickly forms
a dispersion. As a result, sewage systems can be effectively
prevented from clogging up. For other embodiments of the coreless
roll which are normally not disposed via the sewage system such as
napkins, towels, e.g., household towels, kitchen towels or hand
towels, toilet papers, wipes and facial tissues, this feature is
not required.
[0129] In the present invention according to one embodiment, the
amount of nonionic cellulose ether in the coating composition is
set such that the nonionic cellulose ether is applied to the second
end in an amount of from 0.001 to 20 g/roll, preferably 0.005 to 10
g/roll, more preferably 0.005 to 5 g/roll, in particular 0.01 to 2
g/roll. When the amount of nonionic cellulose ether applied to the
second end is less than 0.001 g/roll, the desired properties in
terms of stiffness and resistance to collapsing may not be fully
developed. Conversely, when the amount of nonionic cellulose ether
applied to the second end is greater than 20 g/roll, the roll
exhibits a high stiffness and resistance to collapsing, but
manufacturing costs may become high.
2.2 Additives
Plasticizer
[0130] The coating composition of the present invention may include
a plasticizer, for instance a known plasticizer of an ester type.
The plasticizer may contribute to the film-forming properties of
the coating composition. It is selected such as to be compatible
with the nonionic cellulose ether described above. In one
embodiment, the coating composition of the present invention is
free of plasticizer.
[0131] One type of plasticizer may be used on its own or two or
more types may be used in combination.
[0132] From the viewpoint of stability over time, the content of
the plasticizer in the coating composition of the present invention
is preferably no greater than 20 wt % of the total solids content,
more preferably no greater than 10 wt %, yet more preferably no
greater than 5 wt %.
Strengthening Agent
[0133] The coating composition of the present invention may include
a strengthening agent.
[0134] In one embodiment, the coating composition of the present
invention is free of strengthening chemical additives, such as
strength resins, for instance free of water-soluble cationic or
anionic polymers.
Other Additives
[0135] The composition may comprise as appropriate various types of
known additives as long as the desired effects are not inhibited.
Examples include a fragrance, a colorant, a surfactant, an
anti-scaling agent, and an anti-bacterial agent as well as
inorganic or organic fillers.
[0136] One type thereof may be used on its own or two or more types
may be used in combination.
3. Absorbent Product
[0137] The coreless roll of the present invention has many
applications in the field of sanitary or domestic absorbent
products. In particular, the roll of the present invention can be
an absorbent sheet product chosen among the group consisting of
napkins, towels such as kitchen towels or hand towels, toilet
paper, wipes and facial tissues.
[0138] In the present invention according to one embodiment, the
absorbent sheet product is made of a continuous web of absorbent
material having a first end and a second end, which consists of at
least one ply of base tissue paper with typical basis weight of
from 8 to 60 g/m.sup.2, preferably 10 to 30 g/m.sup.2.
[0139] In one embodiment, the continuous web of absorbent material
is a single ply web made of tissue paper or a multiple-ply web made
of, e.g., 2 to 5 superposed tissue paper plies. To achieve a
multiple-ply absorbent sheet product, the one-ply base tissues are
combined in a converting step to the final ply count, which may be
from, e.g., 2 to 5 depending on the targeted properties of the
final product. The total basis weight of the resulting multiple-ply
web preferably does not exceed 120 g/m.sup.2, and more preferably
is lower than 100 g/m.sup.2, e.g., lower than 90 g/m.sup.2.
[0140] In the present invention according to one embodiment, the
second end of the continuous web is coated with the coating
composition of the present invention (i.e., one comprising a
nonionic cellulose ether as described above) and spirally wound to
achieve a roll of absorbent sheet product, such as a toilet paper
roll. The coating composition can be applied onto the second end by
using techniques known in the art. "Spraying" and "roll coating"
belong to these well-known techniques.
[0141] In the present invention according to one embodiment, the
coating composition is applied onto at least one of the two sides
of the continuous web, i.e., the upper and/or the lower side of the
continuous longitudinal web, or between the base tissue paper plies
forming the web.
[0142] When the web is a multiple-ply web, e.g., one having 2 to 5
superposed tissue paper plies, the coating composition can be
applied onto one or both sides of one or more plies, e.g., onto all
the plies. In one embodiment, the coating composition is applied
onto one of the outer plies of the web, preferably onto the outer
ply which is oriented towards the axial hollow passageway in the
finished absorbent sheet product (i.e., the outer ply which is the
one closest to the axial hollow passageway). The outer ply can be
coated on one or both sides, preferably on its lower side, i.e.,
the side oriented towards the axial hollow passageway.
[0143] The absorbent sheet product of the present invention
according to one embodiment is selected from napkins, towels such
as kitchen towels or hand towels, toilet paper, wipes and facial
tissues. As used herein, "toilet paper" means a soft and strong
base tissue paper, which is used to clean the posterior after using
the toilet (sometimes also referred to as "bathroom tissue").
[0144] The present invention also relates to the use of the
coreless roll as toilet paper, household towel, kitchen towel,
wipe, facial or napkin.
[0145] According to one embodiment, the absorbent sheet product is
a toilet paper composed of 2 to 5 superposed tissue paper plies,
e.g., 2 to 4 tissue paper plies, in which the coating composition
is applied onto at least one outer ply of the continuous web,
preferably on the lower side of the outer ply closest to the axial
hollow passageway.
[0146] The dimensions of the exemplary coreless roll of the present
invention are not limited and depend greatly on the target
absorbent sheet product. An individual roll can for instance have a
diameter (edge diameter) of from 5 cm to 50 cm, preferably from 8
cm to 20 cm. The axial hollow passageway can have a diameter of
from 10 mm to 70 mm, preferably from 20 to 50 mm. The width of the
roll (i.e., distance between one edge to another edge) can range
from 60 mm to 800 mm, preferably from 70 mm to 400 mm, e.g., 80 mm
to 150 mm.
[0147] The continuous web of absorbent material forming the
absorbent sheet product may have a total length in the machine
direction of from 1 m to 60 m, preferably from 1.5 m to 50 m, e.g.,
2 m to 40 m. Optionally, the web can be partially severed in the
machine direction such that it consists of consecutive single but
coherent sheets. A single sheet can have a length (in the machine
direction) of from 80 mm to 300 mm, e.g., 100 mm to 250 mm,
especially of from 100 mm to 200 mm.
4. Process for the Manufacture of Coreless Rolls and Absorbent
Products
[0148] The present invention also relates to a process for the
manufacture of a coreless roll as described before and below, the
process comprising:
(A) conveying a continuous web of absorbent material having a first
end and a second end, which is optionally composed of one tissue
paper ply or 2 to 5 superposed tissue paper plies; (B) applying a
coating composition to the second end; (C) spirally winding the
continuous web of absorbent material so as to produce a log of web
of absorbent material, the web of absorbent material being wound
such as to define an axial hollow passageway centrally positioned
relative to the log and extending from one edge to another edge of
the log and such that the first end is located on the outer side of
the log and the second end is located at the axial hollow
passageway; (D) optionally severing the continuous web of absorbent
material substantially transversally to the machine direction to
produce single but coherent sheets; and (E) cutting the log into
multiple coreless rolls.
[0149] According to one embodiment of the present invention, the
aforementioned process for the manufacture of a coreless roll
further comprises:
(F) subjecting the coreless roll to compression in a direction
perpendicular to the axial hollow passageway to produce a coreless
roll in a compressed form.
[0150] The coreless roll of the present invention can be
manufactured by using a commercially available converting machine.
A suitable converting machine is available, for example, from the
Paper Converting Machine Company (PCMC), Europe.
[0151] The description of the process below referring to machine
modules/units is to be understood as an illustration of a machine
suitable for manufacturing the roll of the present invention
according to one embodiment. The use of other kinds of
machines/units known in the art is also possible.
[0152] In the present invention according to one embodiment,
referring to FIGS. 5 and 6, the process for the manufacture of a
coreless roll comprises the steps of:
(A) Conveying a continuous web of absorbent material (19) having a
first end and a second end.
[0153] The continuous web of absorbent material (19) to be used in
the present invention consists of one or more plies of base tissue
paper having a basis weight of from 8 to 60 g/m.sup.2, preferably
from 10 to 30 g/m.sup.2. The base tissue paper is typically
provided as large parent rolls (15) and (16) having a width of from
1.80 m to 7 m as obtained from the tissue machine. The parent rolls
(15) and (16) are mounted on the unwinding units (10) and (11) of
converting machine (9). The number of parent rolls to be used
corresponds to the ply count in the target absorbent sheet product.
In FIGS. 5 and 6, two parent rolls (15) and (16) each providing one
ply of bathroom tissue (18A) and (18B) are employed to produce a
two-ply toilet paper roll (1). In some aspects, the parent roll(s)
can provide a multi-ply, e.g., 2 or more plies, tissue paper (e.g.,
in the event of a production line with an insufficient number of
unwinders).
[0154] The plies (18A) and (18B) are fed from the unwinding units
(10) and (11) to an embossing unit (12), in which the plies are
superposed and combined (associated) in order to produce a
continuous web of absorbent material (19).
[0155] The embossing unit includes an engraved cylinder (20) and a
mating rubber cylinder (21), both rotating in opposite directions,
and optionally a glue dispenser (not shown). The engraved cylinder
can be engraved with a microstructure pattern combining various
embossing tips. The engraved cylinder can perform a simple- or a
double-level engraving into the superposed plies.
[0156] The glue dispenser, if any, typically includes a vat (a
reservoir for glue), an applicator cylinder and a dipping cylinder.
The applicator cylinder abuts the superposed base tissue plies
against the engraved cylinder. The dipping cylinder (not shown)
picks up the adhesive in the vat and transfers the adhesive to the
applicator cylinder (not shown). The applicator cylinder is
arranged to exercise a determined pressure on the engraved cylinder
at the distal area of protuberances of the embossed web. At said
determined pressure, the adhesive crosses through the web and bonds
the plies. The amount of adhesive used for ply bonding is
preferably from 0.1 g/m.sup.2 to 5.0 g/m.sup.2, preferably from 0.2
g/m.sup.2 to 1.0 g/m.sup.2. An example of a suitable adhesive for
ply bonding is Swift.RTM.tak 1004 available from H. B. Fuller,
Europe.
[0157] The embossing step described above is used to combine plies
of base tissue and, also, to emboss or micro-emboss at least one of
the plies in order to generate esthetical effects or modify the
thickness, the softness, or the suppleness of the resulting
continuous web (19).
(B) Applying a coating composition onto the second end of the
continuous web so as to form a full or partial coating. The coating
composition is applied onto the second end by techniques known in
the art. In the present invention, it is possible to use, amongst
other techniques, spraying or roll coating.
[0158] As used herein, "spraying" means that the coating
composition is applied onto the continuous web in the form of a
dispersion of fine liquid droplets in a gas (i.e., a spray). A
spray is typically formed by using a spray nozzle (spray gun)
having a fluid passage that is acted upon by mechanical forces
which atomize the liquid. The liquid droplets can have a size of
from 1 .mu.m to 1000 .mu.m, e.g., 10 .mu.m to 400 .mu.m.
[0159] The converting machine (9) can be equipped with one or more
spray guns (23A), e.g., 1 to 8 spray guns, which can be placed at
any location of the converting line as long as this is meaningful
in view of the desired results (coatings of second end). The spray
gun(s) (23A) can be placed before the embossing unit (12) such that
the coating composition (22) is applied, e.g., onto an outer ply or
between the plies. Preferably, the spray gun(s) (23A) is/are placed
between the cutting module (27) and the winding module (28) such
that the coating composition (22) is applied onto the lower side of
an outer ply (as shown in FIG. 5).
[0160] The spraying system includes one or more spray gun(s) (23A),
a vat (24) and pipes (25) feeding the coating composition (22) from
the vat to the spray gun(s) (23A). Optionally, the spraying system
is equipped with a heating system (e.g., heating jacket, heat guns,
etc., not shown), which heats the coating composition in the vat
(24), pipes (25) and/or gun(s) (23A) such that the composition is
maintained at a constant temperature during spraying.
[0161] Spray guns suitable for spraying the coating composition of
the present invention are available, e.g., from Walther Spritz- and
Lackiersysteme GmbH, Germany.
[0162] As used herein, "roll coating" means that the coating
composition is directly applied onto the second end by means of an
applicator roll. "Roll-to-roll coating" and "reverse-roll coating"
belong to well-known techniques which can be used in the present
invention. Referring to FIG. 6, the roll-coating system includes
dipping cylinder and applicator cylinders (23B), a vat (24) and
pipes (25) feeding the coating composition (22) from the vat to the
dipping and applicator cylinders (23B). The roll-coating system
includes optionally a heating system as described above (not
shown). The roll-coating system can be placed at any location of
the converting line as long as this is meaningful. The roll-coating
system can be placed, for example, on the embossing unit in a
manner that the applicator cylinder (23B) abuts against the
engraved cylinder (20) or another cylinder (as shown in FIG.
6).
[0163] The spray gun(s) (23A) or the roll-coater (23B) can be
adjusted to apply a continuous coating in the machine and axial
direction or an intermittent coating (e.g., stripes, dots, etc.) in
the machine and/or axial direction.
(C) Spirally winding the continuous web (19) so as to produce a log
of web of absorbent material (34).
[0164] The continuous web (19) is fed from the embossing unit (12)
to the rewinding unit (13) in which the web (19) is spirally wound
so as to produce a log of web of absorbent material (34). The
rewinding unit (13) includes a perforating module (26), a cutting
module (27), a winding module (28) and an extraction module (33).
The rewinding unit (13) winds the continuous web (19) into multiple
logs (34).
[0165] The winding module (28) is arranged to wind the continuous
web (19) so as to produce logs of web (34). The winding module (28)
can be of the peripheral type (center winding) or the surface type
(surface winding). The winding module includes a rolling surface
(29), a first winding roller (30), a second winding roller (31), a
third winding roller (32), and a temporary core supplier (not
shown). The log is formed by winding the continuous web onto a
temporary core (36) which maintains a well-defined axial hollow
passageway. The temporary cores (36) are sequentially provided by
the core supplier through the rolling surface (29) before the
beginning of a new log production cycle. The temporary core (36)
can be made, for example, of plastic or cardboard. A "fugitive
glue" (pick-up glue) can be used to pick up the second end of the
web (19) onto the temporary core (36) at the beginning of a new
production cycle.
[0166] The log (34) is maintained in position during the winding by
the first, second and third winding rollers (30), (31) and (32)
rotating in surface contact with the log (34). One of the winding
rollers (30), (31) and (32) may impose a rotation movement to the
log (surface winding).
[0167] Once the desired log diameter (corresponding to a
substantially defined web length or number of individual sheets) is
reached, the continuous web (19) is cut. The produced log (34) is
separated from the web (19) and subsequently the production of a
new log begins.
[0168] The cutting unit (27) is arranged to cut the web according
to regularly spaced cutting lines substantially transversally to
the machine direction. The cutting of the web occurs at a
transition phase, namely when a first log is finished at the end of
a log production cycle, and before a second subsequent log starts
being wound at the beginning of a new log production cycle.
[0169] The cutting lines (not shown) are lines in the axial
direction made in the thickness of the web (19). Two consecutive
cutting lines define the total web length forming one roll. The
space between two consecutive cutting lines, i.e., the roll length,
is determined depending on the target product. Typically, roll
length and roll diameter are selected depending on, e.g., the
number of plies forming the web, the basis weight of the individual
plies, etc. An individual roll of absorbent sheet product can have
a total web length in the machine direction of from 1 m to 60 m,
preferably from 1.5 m to 50 m, e.g., 2 m to 40 m.
[0170] The produced log (34) is then provided to the extraction
module (33), which is arranged to extract the temporary cores (36)
from the log (34) after the winding of a log is completed. The
temporary cores (36) may be recycled after extraction towards the
core supplier.
[0171] When the coating composition used in the process of the
present invention is an aqueous solution as described hereinabove,
the produced log can be subjected to drying after that the produced
log is separated from the web of absorbent material and before
extraction of the temporary core. The produced log can also be
subjected to drying after extraction of the temporary core.
[0172] The produced log is preferably dried until the tissue paper
forming the log contains an amount of water which does not exceed
10% of the total weight of the log, preferably 5% of the total
weight of the log. For instance, the produced log can be dried by
storing the log at room temperature (20.degree. C. to 25.degree.
C.) and RH (relative humidity) of 10 to 60% for a period of 12
hours.
(D) Optionally severing the continuous web of absorbent material
(19) substantially transversally to the machine direction to
produce single but coherent sheets.
[0173] Before the continuous web (19) is spirally wound by the
winding module (29) as described above, the web (19) reaches the
perforating module (26), if any, which is arranged to provide the
web (19) with regularly spaced perforation lines (8) substantially
transversally to the machine direction, i.e., in the axial
direction, so as to produce single but coherent sheets (as shown in
FIGS. 3, 4a and 4b).
[0174] A perforation line (8) is a line in the axial direction made
in the thickness of the web (19) and comprising alternating
perforated segments and unperforated segments (i.e., two perforated
segments being separated by one unperforated segment or
vice-versa). Each unperforated segment forms an attachment area
between two consecutive portions of the continuous web. Each
perforated segment forms a detachment area between two consecutive
portions of the continuous web. Considering the width of the
individual roll, for example between 10 cm and 30 cm, the length of
said unperforated/perforated segments can be from 1 mm to 15 mm,
preferably from 4 mm to 10 mm. Other kinds of perforation lines are
also possible as long as this is meaningful.
[0175] Two consecutive perforation lines (8) define the individual
sheet length in the finished absorbent sheet product. The space
between two consecutive perforation lines, i.e., the sheet length,
is determined depending on the target product. A single sheet can
have a length in the machine direction of from 80 mm to 300 mm,
e.g., 100 mm to 250 mm. For example, a sheet of bathroom tissue can
have a length of from 80 mm to 200 mm and a towel such as a
household (kitchen) towel or hand towel can have a length of from
80 mm to 300 mm.
(E) Cutting the produced log (34) into multiple coreless rolls
(1).
[0176] After winding, the log (34) is provided to the log cutting
unit (14), in which the log (34) is cut parallel to the machine
direction by multiple log saws (35) into multiple individual rolls
(1). The multiple log saws (35) are regularly spaced in the axial
direction such that the log (34) is cut into multiple individual
rolls (1) having a determined width in the axial direction (i.e.,
distance from one edge to another edge). The width of an individual
roll (1) is from 60 mm to 800 mm, preferably from 70 mm to 400 mm,
e.g., 80 mm to 150 mm.
[0177] A control module (37) is coupled to the perforating module
(26), to the cutting module (27) and to the spraying or
roll-coating system by means of an interface (38). The control
module (37) controls the operation of the perforating module (26)
and the cutting module (27). In particular, the control module (37)
activates the cutting module (27) to sever the web (19) at a
transition phase between two consecutive logs. Furthermore, the
control module (37) controls the operation of the perforating
module (26) out of transition phases.
[0178] In addition, the control module (37) controls the operation
of the spraying or roll-coating system, namely the appropriate
application (spraying or roll coating) of the coating composition
onto the second end of the continuous web (19). The appropriate
application of the coating composition onto the second end can be
controlled by sending, e.g., start/stop signals to the application
(spraying or roll-coating) system, which are determined based on
the length of the target product and the machine parameters, e.g.,
running speed.
[0179] Various rollers (17) are appropriately positioned in order
to control the path of the continuous web (19) along the converting
machine (9), within and between the various units.
(F) Optionally, subjecting the roll to compression in a direction
perpendicular to the axial hollow passageway to produce a coreless
roll in a compressed (oval) form (not shown).
[0180] As used herein, "compression" means that a pressure is
applied on the roll in a direction perpendicular to the axial
hollow passageway so as to produce a roll having an oval cross
section, which requires less storage space. Roll compression occurs
preferably immediately after winding has been terminated. An
appropriate device known in the art can be used to operate the
compression. In the present invention, it is possible to use for
example the two converging synchronically driven conveyor bands
described in WO 95/13183, a pneumatic or hydraulic pressing plate,
or other devices.
[0181] Thereafter, the individual coreless rolls (1) are packaged
and prepared for shipping (not shown).
5. Examples
[0182] The following test methods were used to evaluate the
absorbent materials, the nonionic cellulose ethers and the coreless
rolls produced.
5.1 Basis Weight
[0183] The basis weight was determined according to EN ISO
12625-6:2005, Tissue Paper and Tissue Products, Part 6:
Determination of grammage.
5.2 Caliper
[0184] The measurement is made by a precision micrometer (precision
0.001 mm) according to a modified method based on EN ISO
12625-3:2014, Part 3. For this purpose, the distance created
between a fixed reference plate and a parallel pressure foot is
measured. The diameter of the pressure foot is 35.7.+-.0.1 mm (10.0
cm.sup.2 nominal area). The pressure applied is 2.0 kPa.+-.0.1 kPa.
The pressure foot is movable at a speed rate of 2.0.+-.0.2
mm/s.
[0185] A usable apparatus is a thickness meter type L & W SE050
(available from Lorentzen & Wettre, Europe).
[0186] The tissue paper product to be measured is cut into pieces
of 20.times.25 cm and conditioned in an atmosphere of 23.degree.
C., 50% RH (Relative Humidity) for at least 12 hours.
[0187] For the measurement, one sheet is placed beneath the
pressure plate which is then lowered. The thickness value for the
sheet is then read off 5 seconds after the pressure has been
stabilized. The thickness measurement is then repeated nine times
with further samples treated in the same manner.
[0188] The mean value of the 10 values obtained is taken as
thickness of one sheet ("one-sheet caliper") of the tissue paper
product (e.g., a two-ply toilet paper) measured.
5.3. Number-Average Molecular Weight
[0189] The measurement is made by Gel Permeation Chromatography
(GPC) using a PL-GPC 50 Integrated GPC/SEC System equipped with
three PL aquagel-OH 8 .mu.m columns 7.5.times.300 mm (available
from Agilent Technologies, Europe). The GPC system was calibrated
using a pullulan polysaccharide calibration kit available from
Agilent Technologies (for methyl cellulose) or, depending on the
cellulose ether to be measured, with a suitable calibration kit
such as hydroxyethyl cellulose, hydroxypropyl cellulose and
hydroxypropylmethyl cellulose calibration kits all available from
American Polymer Standards Corporation, USA.
[0190] A sample of the nonionic cellulose ether to be measured was
dissolved in water at a concentration of 2 mg/m L. The sample was
injected (injection volume: 100 .mu.L) and run at a flow rate of
1.0 mL/min and a temperature of 50.degree. C. using an aqueous
buffer solution 0.05M NaH.sub.2PO.sub.4, 0.25M NaCl pH 7 as the
eluent. The retention time (min) of the cellulose ether was
recorded as a peak. The number-average molecular weight Mn of the
cellulose ether was determined by comparing the recorded retention
time with that of standard (calibration) cellulose ethers.
5.4. Viscosity-Average Molecular Weight
[0191] The measurement can be conducted as follows by viscometry
using an Ubbelodhe capillary viscometer equipped with a capillary
having an internal diameter of 0.63 mm (both available from SI
Analytics, Europe).
[0192] A sample solution (concentration C.sub.1=10.0 g/l) of the
cellulose ether in water is prepared and transferred to the
Ubbelodhe capillary viscometer. The viscometer is suspended in a
thermostatic bath for 30 minutes at a temperature of
(25.+-.0.1.degree.) C. The flow time (the time taken for the sample
solution to flow between the two calibrated marks) is measured. The
measurement is repeated five times and the mean value of the five
values obtained is taken as flow time of the sample solution. The
same measurement is reproduced with a sample of water (without
cellulose ether). The Hagenbach-Couette corrections (as provided by
SI Analytics) were subtracted from the measured flow times.
[0193] The relative viscosity z.sub.1 of the sample of the
cellulose ether can be calculated as follows:
z 1 = Flow time of the sample solution Flow time of water
##EQU00001##
[0194] The measurement is repeated using further sample solutions
with concentrations C.sub.2=5.0 g/l, C.sub.3=3.33 g/l and
C.sub.4=2.5 g/l. The relative viscosities z.sub.2, z.sub.3 and
z.sub.4 are obtained.
[0195] The intrinsic viscosity n can be determined graphically by
plotting the relative viscosity (y-axis) against the sample
concentration (x-axis) and extrapolating the theoretical straight
line backwards to zero concentration (the line cuts the y-axis at
the height of the intrinsic viscosity).
[0196] The viscosity-average molecular weight M v of the cellulose
ether can be calculated using the Mark-Houwink-Sakurada equation
(1) and the constants K and a of the cellulose ether as indicated
in Brandrup, J., Immergut, E. H., Grulke, E. A., Polymer Handbook
4.sup.th Edition, John Wiley & Sons, New York 1999
(hydroxyethyl cellulose: K=9.5310.sup.-3 ml/g, .alpha.=0.87).
M _ v = .eta. K .alpha. ( 1 ) ##EQU00002##
5.5. Axial Stiffness
[0197] The measurement is made by a vertical dynamometer equipped
with a 2.5 kN cell. A usable apparatus is a dynamometer type
ZwickiLine Z1.0 (available from Zwick Roell, Europe).
[0198] For the measurement, a roll was placed vertically between
the pressure plates (on one of the two flat edges), and pressure
was applied in a direction parallel to the axis of the hollow
passageway. The roll was compressed between the plates at a
constant speed of 60 mm/min. The compression force was measured and
plotted against the displacement of the cell (y-axis: compression
force; x-axis: cell displacement). The correlation between
compression force and cell displacement was determined by linear
regression in the elastic domain of the graph. The slope of the
linear regression line was taken as the axial stiffness of the
roll.
[0199] The measurement was repeated four times with further
samples, and the mean value of the five values obtained is taken as
the axial stiffness K.sub.ax of the roll.
5.6 Radial Stiffness
[0200] The measurement is made by a vertical dynamometer equipped
with a 200N cell. A usable apparatus is a dynamometer type
ZwickiLine Z1.0 (available from Zwick Roell, Europe).
[0201] For the measurement, the roll to be measured was placed
horizontally between the pressure plates (on the round edge), and
pressure was applied in a direction perpendicular to the axis of
the hollow passageway. The roll was compressed between the plates
at a constant speed of 60 mm/min. The compression force was
measured and plotted against the displacement of the cell (y-axis:
compression force; x-axis: cell displacement). The correlation
between compression force and cell displacement was determined by
linear regression in the elastic domain of the graph. The slope of
the linear regression line was taken as the radial stiffness of the
roll.
[0202] The measurement was repeated four times with further
samples, and the mean value of the five values obtained is taken as
the radial stiffness K.sub.rad of the roll.
5.7 Delamination Force
[0203] The measurement is made by a vertical dynamometer (39)
(ZwickiLine Z1.0) equipped with a shaft assembly (40)-(43), a jaw
(45) and a 50N cell (not shown) as depicted in FIGS. 7a, 7b and
7c.
[0204] For the measurement, the first inner turns of a coreless
roll to be measured (44) were inserted on the upper shaft (41) of
the shaft assembly, the outermost paper sheet was unwound and
placed on the shaft assembly as shown in FIG. 7a, and the outermost
paper sheet was inserted into the jaw (45). The turns were unwound
at a constant speed of 300 mm/min. The delamination force needed
for separating the paper sheets forming the turns was measured and
plotted as a function of the displacement of the cell. The maximal
force and the average force required to delaminate the sample were
recorded within the displacement interval. The delamination force
measurement was then repeated four times with further samples.
[0205] The mean value of the five values of the maximal force
obtained is taken as the delamination force of the first inner
turns.
5.8 Disintegrability
[0206] The disintegrability was determined according to NF
Q34-20:1998, Sanitary and Domestic Articles-Bathroom
Tissue-Determination of Disintegration.
5.9 Starting Materials, Chemicals and Converting Machine
Absorbent Material
[0207] A three-ply base tissue paper (1) (Conventional) having a
basis weight of 55.6 g/m.sup.2
[0208] and a caliper of 0.62 mm (manufactured by SCA) was used as
the continuous web of absorbent material in Reference Example 1 and
Examples 1-3.
[0209] A three-ply base tissue paper (2) (Conventional) having a
basis weight of 53.6 g/m.sup.2 and a caliper of 0.63 mm
(manufactured by SCA) was used as the continuous web of absorbent
material in Reference Example 2 and Examples 4-8.
[0210] The three-ply base tissue papers (continuous webs) (1) and
(2) were prepared with a conventional converting machine by
combining a one-ply base tissue paper to the final ply count (3) as
follows:
[0211] A first unwinding unit provided a first ply of base tissue
from a first parent roll having a width of 0.6 m. A second
unwinding unit provided a second ply of base tissue from a second
parent roll having a width of 0.6 m. A third unwinding unit
provided a third ply of base tissue from a third parent roll having
a width of 0.6 m. The plies of base tissue were fed to an embossing
unit. The base tissues were superposed and combined (associated)
using an adhesive in the embossing unit in order to form a
continuous web of absorbent material. The engraved cylinder
performed a double-level engraving into the superposed absorbent
log base webs. The adhesive used for ply bonding was Swift.RTM.tak
1004 in an amount of 0.5 g/m.sup.2.
[0212] The resulting three-ply continuous web of absorbent material
(1) or (2) was fed to a rewinding unit.
Chemicals
[0213] The chemicals used in the following examples are listed
below:
For the coating composition:
[0214] Methylcellulose from Sigma-Aldrich with viscosity of about
400 cP (2% solution in water at 20.degree. C.) and number-average
molecular weight of about 40,000 (as determined by GPC);
[0215] Hydroxyethyl cellulose from Sigma-Aldrich with
viscosity-average molecular weight of about 90,000 (as determined
by viscometry);
[0216] Hydroxyethyl cellulose from Sigma-Aldrich with
viscosity-average molecular weight of about 720,000 (as determined
by viscometry);
[0217] Hydroxypropyl cellulose from Sigma-Aldrich with
number-average molecular weight of about 10,000 (as determined by
GPC);
[0218] Hydroxypropylmethyl cellulose from Sigma-Aldrich with
hydroxypropoxyl content of about 9% and viscosity of about 15 cP
(2% solution in water at 25.degree. C.);
[0219] Carboxymethyl cellulose Blanose.RTM. 7ECL1 from Ashland.
Adhesives:
[0220] Swift.RTM.tak 1004 from H. B. Fuller (used for ply
bonding);
[0221] Tissue Tak 604 from Henkel ("fugitive glue" used for
winding).
Converting Machine
[0222] A conventional tissue paper converting machine was adapted
to make a toilet paper having three plies. The machine involved two
unwinding units, an embossing unit, a rewinding unit, and a log
cutting unit.
[0223] The embossing unit comprised an engraved cylinder, a mating
rubber cylinder and a glue dispenser. The engraved cylinder was
engraved with a microstructure pattern combining various embossing
tips. The glue dispenser comprised a vat, an applicator and a
dipping cylinder.
[0224] The rewinding unit comprised a perforating module, a cutting
module, a winding module and an extraction module. The perforating
module comprised a perforator roll and a stationary anvil roll. The
cutting module comprised a cutting roll and a stationary anvil
roll.
[0225] The rewinding unit was furthermore equipped with a spraying
system consisting of four spray guns type WA250 (available from
Walther Pilot) having a nozzle diameter of 1.5 mm and working under
a pressure of 1.5, 2.0 or 2.5 bars, a vat and pipes feeding the
coating composition from the vat to the spray guns.
[0226] The spray guns were placed between the cutting module and
the winding module such that the coating composition was
applied/sprayed on the lower side of the continuous web of
absorbent material upstream to a cutting line at the beginning of
the log, thus defining the first web end (i.e., the turns of the
log/roll close to the axial hollow passageway).
[0227] The log cutting unit comprised multiple log saws.
[0228] Various rollers are appropriately positioned in order to
control the path of the absorbent log base webs along the
converting machine, within and between the various units. The
absorbent log base webs travel into the converting machine
according to the machine direction (MD) from the unwinding units,
towards the embossing unit, towards the rewinding unit and towards
the log cutting unit.
[0229] A control module was coupled to the perforating module, the
cutting module and the spray guns by means of an interface. The
control module controlled the operations of the perforating module
and the cutting module, as well as the appropriate spraying of the
coating composition onto the second end.
[0230] The machine speed was kept throughout the trials at 100 m/m
in.
Reference Example 1 (Reference Toilet Paper 1)
[0231] To obtain the desired coreless roll of toilet paper, a
three-ply continuous web of absorbent material (1) (basis weight:
55.6 g/m.sup.2, caliper: 0.62 mm) was produced as described above,
conveyed from the embossing unit and fed to the rewinding unit.
[0232] In the rewinding unit, the continuous web first reached the
perforating module, which pinched the web to provide perforation
lines transversally orientated relative to the machine direction
(MD) and regularly spaced relative to the cross direction (CD). The
size of the perforated segment was 4 mm and the size of the
unperforated segment was 1 mm. The distance between two perforation
lines was 125 mm.
[0233] After pinching, the web of absorbent material reached the
winding module, in which the web was picked up onto a temporary
core (external diameter: 38 mm) using Tissue Tak 604 as "fugitive
adhesive". The web was then wound onto the core to form a log
having a diameter of 120 mm (corresponding to 140 perforated
sheets; approximate total length of the web: 17500 mm).
[0234] The produced log was separated from the web of absorbent
material by the cutting module, which severed the web transversally
relative to the MD. The produced log was stored at 20-22.degree.
C., relative humidity of 50% for a period of 12 hours.
[0235] After storage, the temporary core was extracted from the log
by the extraction module. The produced log was cut parallel to the
MD by multiple log saws into multiple individual rolls having a
width of 99 mm.
Reference Example 2 (Reference Toilet Paper 2)
[0236] A coreless roll was produced in the same manner as described
in Reference Example 1 above except that a three-ply continuous web
of absorbent material (2) (basis weight: 53.6 g/m.sup.2, caliper:
0.47 mm) produced as described above, was conveyed from the
embossing unit and fed to the rewinding unit.
[0237] The produced log having a diameter of 120 mm was cut
parallel to the MD by multiple log saws into multiple individual
rolls having a width of 99 mm.
Example 1 (Toilet Paper with Hydroxypropylmethyl Cellulose)
[0238] A coating composition was prepared by dissolving
hydroxypropylmethyl cellulose (HPMC) with viscosity 15 cP in water
at a concentration of 3.7% by weight. The obtained coating
composition was fed to the spray guns and applied at room
temperature (22.degree. C.).
[0239] To obtain the desired coreless roll of toilet paper, a
coreless roll was produced in the same manner as described in
Reference Example 1 above except that, after pinching/severing and
before winding the web, the coating composition was applied
(sprayed) by means of the spray guns (pressure: 1.5 bars) onto a
length of about 1800 mm (i.e., about 15 sheets) upstream from the
cutting line.
[0240] The amount of HPMC applied onto the second end (length: 1800
mm; i.e., about 10% of the entire web length) was 0.019 g/roll
(solid content of HPMC applied to one individual roll, i.e., after
cutting the log).
Example 2 (Toilet Paper with Hydroxypropylmethyl Cellulose)
[0241] A coreless roll was produced in the same manner as Example 1
above except that the coating composition was applied onto a length
of about 1800 mm at a pressure of 2.5 bars. The amount of HPMC
applied onto the second end (length: 1800 mm) was 0.081 g/roll
(solid content of HPMC applied to one individual roll).
Example 3 (Toilet Paper with Hydroxypropylmethyl Cellulose)
[0242] A coreless roll was produced in the same manner as Example 1
above except that the coating composition was applied onto a length
of about 3500 mm (i.e., about 28 sheets) at a pressure of 2.0 bars.
The amount of HPMC applied onto the second end (length: 3500 mm;
i.e., about 20% of the entire web length) was 0.099 g/roll (solid
content of HPMC applied to one individual roll).
Example 4 (Toilet Paper with Methylcellulose)
[0243] A coating composition was prepared by dissolving
methylcellulose with viscosity 400 cP in water at a concentration
of 2% by weight. The obtained coating composition was fed to the
spray guns and applied at room temperature.
[0244] To obtain the desired coreless roll of toilet paper, a
coreless roll was produced in the same manner as described in the
Reference Example 2 above except that, after pinching/severing and
before winding the web, the coating composition was applied
(sprayed) by means of the spray guns (pressure: 2.5 bars) onto a
length of about 1800 mm (i.e., about 15 sheets) upstream from the
cutting line.
[0245] The amount of MC applied onto the second end (length: 1800
mm) was 0.066 g/roll (solid content of MC applied to one individual
roll).
Example 5 (Toilet Paper with Hydroxyethyl Cellulose M v=90,000)
[0246] A coating composition was prepared by dissolving
hydroxyethyl cellulose having a viscosity-average molecular weight
of 90,000 (HEC90) in water at a concentration of 6% by weight. The
obtained coating composition was fed to the spray guns and applied
at room temperature.
[0247] The coreless roll was produced in the same manner as Example
4 except that the coating composition described above was applied
at a pressure of 1.5 bars. The amount of HEC90 applied onto the
second end (length: 1800 mm) was 0.09 g/roll (solid content of
HEC90 applied to one individual roll).
Example 6 (Toilet Paper with Hydroxyethyl Cellulose M
v=720,000)
[0248] A coating composition was prepared by dissolving
hydroxyethyl cellulose having a viscosity-average molecular weight
of 720,000 (HEC720) in water at a concentration of 4% by weight.
The obtained coating composition was fed to the spray guns and
applied at room temperature.
[0249] The coreless roll was produced in the same manner as Example
4 using the coating composition described above. The amount of
HEC720 applied onto the second end (length: 1800 mm) was 0.03
g/roll (solid content of HEC720 applied to one individual
roll).
Example 7 (Toilet Paper with Hydroxypropyl Cellulose)
[0250] A coating composition was prepared by dissolving
hydroxypropyl cellulose having a number-average molecular weight of
10,000 (HPC) in water at a concentration of 6% by weight. The
obtained coating composition was fed to the spray guns and applied
at room temperature.
[0251] The coreless roll was produced in the same manner as Example
4 using the coating composition described above. The amount of HPC
applied onto the second end (length: 1800 mm) was 0.06 g/roll
(solid content of HPC applied to one individual roll).
Example 8 (Toilet Paper with Hydroxypropylmethyl Cellulose)
[0252] A coating composition was prepared by dissolving HPMC in
water at a concentration of 3.7% by weight. The obtained coating
composition was fed to the spray guns and applied at room
temperature.
[0253] The coreless roll was produced in the same manner as Example
4 except that that coating composition described above was applied
at a pressure of 2.0 bars. The amount of HPMC applied onto the
second end (length: 1800 mm) was 0.042 g/roll (solid content of
HPMC applied to one individual roll).
Comparative Example 1 (Toilet Paper with Carboxymethyl
Cellulose)
[0254] A coating composition was prepared by dissolving
carboxymethyl cellulose (CMC) Blanose.RTM. 7ECL1 (weight-average
molecular weight of about 90,000) in water at a concentration of 5%
by weight. The obtained coating composition was fed to the spray
guns and applied at room temperature.
[0255] The coreless roll was produced in the same manner as Example
4 using the coating composition described above. The amount of CMC
applied onto the second end (length: 1800 mm) was about 0.17 g/roll
(solid content of CMC applied to one individual roll).
[0256] The properties of the toilet paper rolls produced were
evaluated according to the procedures explained hereinbefore.
Specifically, the stiffness properties of the rolls obtained in
Reference Example 1 and Examples 1, 2 and 3 were evaluated. The
results are shown in table 1 below. Moreover, the delamination and
disintegration properties of the rolls obtained in Reference
Example 2, and Examples 4, 5, 6, 7 and 8 were evaluated. The
results are shown in table 2 below.
TABLE-US-00001 TABLE 1 Amount of coating Axial Radial composition
stiffness K.sub.ax. stiffness K.sub.rad. Example (g/roll) (N/mm)
(N/mm) Ref. Example 1 -- 190 0.41 Untreated Example 1 0.019 251
0.43 HPMC-treated 1800 mm Example 2 0.081 279 0.53 HPMC-treated
1800 mm Example 3 0.066 299 0.46 HPMC-treated 3500 mm
TABLE-US-00002 TABLE 2 Delamination Perforation force breakage
and/or Disintegration Example (N) sheets damaged (s) Ref. Example 2
0.16 No 11 Untreated Example 4 0.73 No 20 MC-treated Example 5 0.64
No 12 HEC90-treated Example 6 0.43 No 13 HEC720-treated Example 7
0.47 No 12 HPC-treated Example 8 0.37 No -- HPMC-treated Comp. 1.75
Yes (5 out of 5) 6 Example 1 CMC-treated
[0257] These test data show that the use of a coating composition
according to the present invention has led to an increased
stiffness while the delamination force of the rolls is maintained
in an acceptable range. The coating composition enables to stably
maintain the first inner turns, and therefore the rolls according
to the present invention are not prone to collapsing. This can be
achieved with fairly low total amounts of nonionic cellulose ether.
The rolls according to the present invention can be unwound up to
the last sheet without tearing apart and/or damaging the sheets
(i.e., no occurrence of perforation breakage and/or sheets damage
in the delamination force measurement).
[0258] Furthermore, the good stiffness properties of the rolls
according to the present invention are beneficial during the
manufacturing process wherein the rolls are subjected to radial
compression (e.g., radial force applied by the log saws in the
cutting module), as well as during storage and transport wherein
the rolls are subjected to axial compression, e.g., axial forces
occurring when packaged roll products are stacked on pallets for
storage, shipment, etc.
[0259] On the other hand, the use of a coating composition
containing an ionic cellulose ether (CMC) provided a roll wherein
the sheets of the first inner turns strongly adhere (glue) to each
other. As a result, it was not possible to unwind the roll without
tearing apart and/or damaging the last sheets. The roll of the
reference example (onto which no coating composition was applied)
was prone to collapsing. This leads to issues during packaging and
contributes to a perception of decreased quality among
consumers.
[0260] While the present invention has been illustrated by
description of various embodiments and while those embodiments have
been described in considerable detail, it is not the intention of
Applicants to restrict or in any way limit the scope of the
appended claims to such details. Additional advantages and
modifications will readily appear to those skilled in the art. The
present invention in its broader aspects is therefore not limited
to the specific details and illustrative examples shown and
described. Accordingly, departures may be made from such details
without departing from the spirit or scope of Applicants'
invention.
* * * * *