U.S. patent application number 17/426870 was filed with the patent office on 2022-04-07 for tissue paper.
The applicant listed for this patent is DAIO PAPER CORPORATION, TOHOKU UNIVERSITY. Invention is credited to Kazuo HOKKIRIGAWA, Minoru IWASAKI, Kei SHIBATA, Sachiko TAKAHASHI, Noritada TOMIOKA, Takeshi YAMAGUCHI, Shuta YASUI.
Application Number | 20220106740 17/426870 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-07 |
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United States Patent
Application |
20220106740 |
Kind Code |
A1 |
TOMIOKA; Noritada ; et
al. |
April 7, 2022 |
TISSUE PAPER
Abstract
To provide a non-moisturizing high-grade type tissue paper
having excellent softness. The problem is solved by a 3-ply tissue
paper having a basis weight of 12.0 g/m.sup.2 or more per ply,
having a paper thickness of 200 to 265 .mu.m for three plies,
having a water content of 4.0 to 9.0% by mass, containing 0.15 to
0.45% by mass of an oily component to be extracted with diethyl
ether, and having a bending rigidity of less than 0.006 gfcm/cm in
CD (Cross Direction) and a bending recovery force of less than
0.005 gfcm/cm in CD.
Inventors: |
TOMIOKA; Noritada;
(Fuji-shi, Shizuoka, JP) ; IWASAKI; Minoru;
(Fuji-shi, Shizuoka, JP) ; YASUI; Shuta;
(Fuji-shi, Shizuoka, JP) ; TAKAHASHI; Sachiko;
(Fuji-shi, Shizuoka, JP) ; HOKKIRIGAWA; Kazuo;
(Sendai-shi, Miyagi, JP) ; YAMAGUCHI; Takeshi;
(Sendai-shi, Miyagi, JP) ; SHIBATA; Kei;
(Sendai-shi, Miyagi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIO PAPER CORPORATION
TOHOKU UNIVERSITY |
Shikokuchuo-shi, Ehime
Sendai-shi, Miyagi |
|
JP
JP |
|
|
Appl. No.: |
17/426870 |
Filed: |
January 30, 2020 |
PCT Filed: |
January 30, 2020 |
PCT NO: |
PCT/JP2020/003437 |
371 Date: |
July 29, 2021 |
International
Class: |
D21H 27/00 20060101
D21H027/00; A47K 10/16 20060101 A47K010/16; D21H 27/30 20060101
D21H027/30 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2019 |
JP |
JP2019-018169 |
Claims
1. A 3-ply tissue paper, comprising 0.15 to 0.45% by mass of an
oily component to be extracted with diethyl ether, wherein the
tissue paper has a basis weight per ply of 12.0 g/m.sup.2 or more,
a paper thickness for three plies of 200 to 265 .mu.m, a water
content of 4.0 to 9.0% by mass, a bending rigidity of less than
0.006 gfcm/cm in machine direction, and a bending recovery force of
less than 0.005 gfcm/cm in machine direction.
2. The tissue paper according to claim 1, which has a dry tensile
strength of 300 to 440 cN in cross direction and a dry tensile
strength of 130 to 200 cN in machine direction.
3. The tissue paper according to claim 1, wherein a polyol is not
externally applied.
4. The tissue paper according to claim 1, comprising no glycerin.
Description
TECHNICAL FIELD
[0001] The present invention relates to a tissue paper.
BACKGROUND ART
[0002] A tissue paper includes a moisturizing tissue in which a
moisturizer containing a polyol is imparted to a base paper and a
non-moisturizing tissue in which a moisturizer is not imparted to a
base paper. The non-moisturizing tissue does not increase the
amount of water due to hygroscopicity of a polyol, provides a firm
feeling and a thick feeling, provides a dry use feeling with less
stickiness, and has an advantage that a moisturizer is not
transferred onto the skin.
[0003] In addition, the non-moisturizing tissue includes a
general-purpose type 2-ply tissue having a basis weight of about 12
g/m.sup.2 per ply and placing importance on price, which is called
a general-purpose tissue, and a tissue belonging to a product group
having a higher basis weight than the general-purpose tissue,
having a high price, and considered to be a high-grade product like
the moisturizing tissue.
[0004] Conventionally, in order to exhibit softness and smoothness
as a high-grade product while having a high basis weight and a
large thickness, the latter non-moisturizing tissue paper has
reduced the density of paper, and has exhibited a cushioning
property particularly in a thickness direction.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: JP 2017-113223 A
SUMMARY OF INVENTION
Technical Problem
[0006] However, when the density of paper is reduced, the
cushioning property in the thickness direction is improved, but
fibers on a surface are sparse and roughness is also increased.
Therefore, it is difficult to further improve softness and
smoothness by simply reducing the density of paper. In addition,
when the density of paper is excessively reduced, strength tends to
be insufficient and a firm feeling tends to be lowered.
Furthermore, when a large amount of a bulking agent is used in
order to reduce the density of paper, for example, peelability from
a dryer during papermaking is likely to deteriorate
disadvantageously.
[0007] On the other hand, a tissue having a high water content like
the moisturizing tissue easily exhibits softness, but reduces such
an advantage that the tissue has excellent softness while giving a
dry use feeling unique to the non-moisturizing tissue, and also
reduces a firm feeling.
[0008] Therefore, a main object of the present invention is to
provide a non-moisturizing tissue paper having better softness and
smoothness, also providing a firm feeling, and having a high basis
weight.
Solution to Problem
[0009] A first means for solving the above problem is
[0010] a 3-ply tissue paper, including 0.15 to 0.45% by mass of an
oily component to be extracted with diethyl ether,
[0011] wherein the tissue paper has a basis weight per ply of 12.0
g/m.sup.2 or more, a paper thickness for three plies of 200 to 265
.mu.m, a water content of 4.0 to 9.0% by mass,
[0012] a bending rigidity of less than 0.006 gfcm/cm in machine
direction, and a bending recovery force of less than 0.005 gfcm/cm
in machine direction.
[0013] A second means is
[0014] the tissue paper according to the first means,
[0015] which has a dry tensile strength of 300 to 440 cN mm in MD
(machine direction), and
[0016] having a dry tensile strength of 130 to 200 cN mm in CD.
[0017] A third means is
[0018] the tissue paper according to the first means, to which a
polyol is not externally applied.
[0019] The fourth means is
[0020] the tissue paper according to the first means,
[0021] containing no glycerin.
Advantageous Effects of Invention
[0022] The above present invention provides a non-moisturizing
tissue paper having better softness and smoothness, also providing
a firm feeling, and having a high basis weight.
BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 is a graph illustrating results of a sensory
evaluation in Examples according to the present invention,
Comparative Examples, and Conventional Examples.
DESCRIPTION OF EMBODIMENTS
[0024] Hereinafter, an embodiment of the present invention will be
described.
[0025] The number of plies of a tissue paper according to the
present invention is three, and the basis weight thereof per ply is
12.0 g/m.sup.2 or more. The basis weight per ply is preferably 13.0
g/m.sup.2 or more. As for a non-moisturizing high-grade product,
the basis weight of a 2-ply product is 14.0 g/m.sup.2 or more per
ply, and in particular, the basis weight is often within a range of
14.0 to 17.0 g/m.sup.2. This is because when the basis weight is
less than 14.0 g/m.sup.2, it is difficult to exhibit a thick
feeling and a bulky feeling, and a difference from a low-priced
general-purpose product is hardly felt. In the present embodiment,
by increasing the number of plies to three, a thick feeling can be
provided even when the basis weight is within a range of 12.0
g/m.sup.2 or more, which is lower than 14.0 g/m.sup.2 and
corresponds to the range of a general-purpose product in a case of
a 2-ply product. In addition, a gap between two plies is formed to
enhance a cushioning property, and a high-grade feeling can be
sufficiently provided as compared with a low-priced general-purpose
product. Here, the higher an upper limit of the basis weight per
ply, the better the thick feeling. When the basis weight is
excessively high, it is difficult to exhibit softness, although not
being necessarily limited. In the case of the 3-ply tissue paper
according to the present embodiment, it is desirable that the basis
weight is 14.6 g/m.sup.2 or less, and more preferably 14.0
g/m.sup.2 or less. In the present embodiment, by using the 3-ply
tissue paper, a thick feeling and a cushioning property can be
provided even if the basis weight is in a slightly low range,
unlike a 2-ply tissue paper. In addition, by using the 3-ply tissue
paper, a firm feeling is enhanced. The paper thickness of the 3-ply
tissue paper is 200 to 265 .mu.m. In the above range of basis
weight, the density is moderately low, and a cushioning property is
easily felt in combination with a gap between the plies.
[0026] Here, the basis weight in the present invention means a
value measured according to JIS P 8124 (1998). The paper thickness
means a value obtained by sufficiently subjecting a test piece to
humidity control under conditions of JIS P 8111 (1998), and then
measuring the paper thickness using a dial thickness gauge
(thickness measuring instrument) "PEACOCK G type" (manufactured by
Ozaki MFG. Co., Ltd.) under the same conditions. Specifically, the
paper thickness is measured by confirming that there is no rubbish,
dust, or the like between a plunger and a measuring table, placing
the plunger on the measuring table, moving a scale of the dial
thickness gauge to adjust a zero point, then raising the plunger,
placing a sample on a test table, lowering the plunger slowly, and
reading the current gauge. At this time, the plunger is just
placed. A terminal of the plunger is made of metal, and a circular
plane thereof with a diameter of 10 mm strikes perpendicularly to a
paper plane, and a load is about 70 gf when the paper thickness is
measured. The paper thickness is an average of values obtained by
performing the measurement 10 times.
[0027] On the other hand, the tissue paper according to the present
invention has a water content of 4.0 to 9.0% by mass. The tissue
paper according to the present invention preferably has a water
content of 4.0 to 8.0% by mass. The water content here is measured
as follows. Two sets of samples are taken from a measurement target
and are subjected to humidity control for three hours in a constant
temperature and humidity room at 23.degree. C. and 50%. Each of the
samples is put in a weighing bottle, the weighing bottle is sealed,
and the mass thereof is measured. Subsequently, the weighing bottle
is placed in a dryer adjusted to 105.+-.3.degree. C. with a lid of
the weighing bottle removed, and the sample is dried for four
hours. The weighing bottle is covered with the lid in the dryer,
and then removed from the dryer. The temperature is caused to
naturally drop to room temperature. 15 to 20 minutes later, the
mass of the weighing bottle containing the sample is measured.
Next, the water content is calculated from a formula of water
content (% by mass)=((mass of weighing bottle+sample before
drying)-(mass of weighing bottle+sample after drying))/((mass of
weighing bottle+paper before drying)-(mass of weighing
bottle))).times.100. Here, when a difference in water content (% by
mass) between the two samples is within 1.0% by mass, an average
value thereof is adopted as the water content (% by mass) of the
sample. Note that the water content is expressed in % with one
decimal place. Meanwhile, when the difference in water content
between the two sets of samples exceeds 1.0% by mass, the test is
performed again.
[0028] The tissue paper according to the present invention has a
water content of 4.0 to 9.0% by mass. When the water content is
within this range, a high-grade feeling with a thick feeling can be
felt while dryness is felt. Here, in order to set the water content
to 4.0 to 9.0% by mass, it is desirable to use a non-moisturizing
tissue in which a moisturizer is not externally applied to a base
paper. The moisturizing tissue generally has a water content of
more than 10.0% by mass. If the non-moisturizing tissue in which a
moisturizer is not externally applied to a base paper is used, it
is easy to set the water content to the above water content. Note
that the moisturizer is an externally added chemical that enhances
the water content due to hygroscopicity of a polyol such as
glycerin, 1,3-butylene glycol, propylene glycol,
3-methyl-1,3-butanediol, 1,3-propanediol, or
2-methyl-1,3-propanediol.
[0029] Furthermore, it is desirable that the tissue paper according
to the present invention contains no glycerin. It is desirable that
glycerin is not contained as an internal additive. Glycerin
enhances the water content due to high hygroscopicity thereof, but
easily exhibits stickiness when glycerin is contained. Furthermore,
it is desirable that the tissue paper according to the present
invention does not contain a trivalent or higher valent polyhydric
alcohol These compounds are oily components, but exhibit
stickiness.
[0030] The tissue paper according to the present invention
characteristically contains 0.15 to 0.45% by mass of an oily
component to be extracted with diethyl ether. The tissue paper
preferably contains 0.21 to 0.35% by mass of an oily component. The
tissue paper more preferably contains 0.23 to 0.30% by mass of an
oily component. Diethyl ether effectively extracts oil and fat
which are low polar substances. Pulp, which is a main raw material
of the tissue paper, does not contain an oily component. Therefore,
the oily component according to the present invention is derived
from an internal additive, particularly an internally added
softener, and contained in the tissue paper. Note that as a tissue
paper containing an oily component, there is a tissue paper to
which an oily component such as silicone or polysiloxane is applied
by external addition. However, the above range is a range in which
it is difficult to uniformly apply the oily component by external
addition, and a range in which it is difficult to exhibit an effect
in application by external addition. The inventors have found that
the content of an oily component in the range of 0.15 to 0.45% by
mass is a high content not found in a conventional non-moisturizing
tissue regardless of whether a tissue paper is a general-purpose
type with a low basis weight or a high-grade type with a high basis
weight. When the content of an oily component is less than 0.15% by
mass, an effect of improving softness and smoothness is small. When
the content of an oily component exceeds 0.45% by mass, cost is
high and manufacturing is difficult.
[0031] The tissue paper according to the present invention contains
a large amount of an oily component derived from an internal
additive and to be extracted with diethyl ether. That is, the
tissue paper according to the present invention contains a large
amount of an oily component covering a surface of pulp fibers, and
exhibits high smoothness of the surface due to the film of the oily
component and high softness due to a strong action of weakening a
hydrogen bond between pulp fibers. Furthermore, the tissue paper
according to the present invention contains a large amount of an
oily component covering a surface of pulp fibers, and therefore
retains moisture of pulp by an emollient effect. That is, the oily
component itself does not have a hygroscopic effect, but does not
impair the effect of retaining moisture absorbed by the pulp fibers
themselves, and does not excessively lower moist feeling.
[0032] Here, in order to obtain a high content of an oily
component, the addition amount of a softener containing oil and fat
may be increased, or the oil and fat in the softener may be
increased. However, the oil and fat to be extracted with diethyl
ether are low polar substances. Therefore, generally, even if the
addition amount of the softener is simply increased, a fixing ratio
to the fibers is unlikely to be increased. In addition, an adhesion
ratio to a dryer may be reduced and workability may be
deteriorated. Therefore, in order to increase the fixing ratio of
oil and fat to be extracted with diethyl ether to the fibers, it is
preferable to increase chances of contact between pulp and oil and
fat. For example, it is only required to set the concentration of
an active component in a weak cationic acidic softener containing a
nonionic activator and a cationic activator to a low concentration
of 25 to 35% by mass, to set a viscosity thereof to 500 mPas or
less, and to supply the softener in a dispersed state to a paper
raw material slurry at appropriate places of papermaking equipment
such as a machine chest or a seed box.
[0033] The use amount of the softener is adjusted depending on the
kind of the softener, but is about 0.2 to 0.5% by mass with respect
to the total weight of the pulp fibers. When the use amount is less
than 0.2% by mass, a sufficient softening effect is not be
necessarily obtained. When the use amount exceeds 0.5% by mass, a
fixing ratio is not necessarily increased.
[0034] The kind of the softener is not necessarily limited, but a
combination of a cationic surfactant and a nonionic surfactant is
preferable as described above. In addition, an emollient component
such as a higher alcohol, a fatty acid ester, or an acylamino acid
ester can be added within a range that does not impair the action
and effect of the present invention. In addition, a small amount of
a moisturizer or the like can be added within a range that does not
impair the action and effect of the present invention, but the
moisturizer or the like does not include an externally added
polyol.
[0035] Specific examples of the emollient component include avocado
oil, almond oil, olive oil, camellia oil, sesame oil, rice bran
oil, safflower oil, soybean oil, corn oil, rapeseed oil, apricot
kernel oil, persic oil, peach kernel oil, castor oil, sunflower
oil, grape seed oil, cottonseed oil, coconut oil, wheat germ oil,
rice germ oil, evening primrose oil, hybrid sunflower oil,
macadamia nut oil, meadow foam oil, hazelnut oil, palm kernel oil,
palm oil, coconut oil, cocoa butter, shea fat, wood wax, mink oil,
turtle oil, egg yolk oil, beef tallow, milk fat, lard, horse oil,
jojoba oil, carnauba wax, candela wax, rice bran wax, orange roughy
oil, beeswax, shellac, lanolin, montan wax, squalene, squalane, a
hydrocarbon such as liquid paraffin, paraffin, microcrystalline
wax, petrolatum, soft liquid isoparaffin, hydrogenated
polyisobutylene, ozokerite, ceresin, .alpha.-oleinphine oligomer,
polybutene, or polyethylene, lauric acid, myristic acid, palmitic
acid, stearic acid, behenic acid, hydroxystearic acid, oleic acid,
linoleic acid, ethylhexanoic acid, isostearic acid, isopalmitic
acid, isotridecanoic acid, isononanoic acid, pentadecanoic acid,
lauryl alcohol, stearyl alcohol, cetearyl alcohol, behenyl alcohol,
cetanol, oleyl alcohol, lanolin alcohol, cholesterol,
isocholesterol, sitosterol, stigmasterol, isostearyl alcohol,
octyldodecanol, hexyldecanol, isopropyl myristate, isopropyl
palmitate, butyl stearate, ethyl oleate, cetyl palmitate, myristyl
myristate, octyldodecyl myristate, octyldodecyl oleate, cholesteryl
stearate, cholesteryl hydroxystearate, tricaprin, trimyristin,
trioctanoin, isopropyl isostearate, ethyl isostearate, cetyl
ethylhexanoate, stearyl ethylhexanoate, glyceryl triethylhexanoate,
glyceryl triethylhexanoate, trimethylolpropane triethylhexanoate,
pentaerythryl tetraethylhexanoate, glyceryl triisostearate,
trimethylolpropane triisostearate, pentaerythtyl tetraisostearate,
pentaerythryl triisostearate, isocetyl isostearate, octyldodecyl
dimethyloctanoate, myristyl lactate, cetyl lactate, trioctyldodecyl
citrate, and diisostearyl malate. These compounds can be used
singly or in combination of two or more kinds thereof.
[0036] The cationic surfactant can be appropriately selected from a
quaternary ammonium salt, an amine salt, an amine, and the like.
Particularly, a preferable cationic surfactant is a quaternary
ammonium salt, which is preferably used. Specific examples of the
quaternary ammonium salt include dilauryldimethylammonium chloride,
distearyldimethylammonium chloride, dimyristyldimethylammonium
chloride, dipalmityldimethylammonium chloride, and
distearyldimethylammonium chloride.
[0037] As the nonionic surfactant, an ester type, an ether type, an
ester ether type, an alkanolamide type, an alkyl glycoside, and the
like can be used. Examples of the ester types include a sorbitan
fatty acid ester, diethylene glycol monostearate, diethylene glycol
monooleate, glyceryl monostearate, glyceryl monooleate,
[0038] propylene glycol monostearate,
N-(3-oleyloxy-2-hydroxypropyl) diethanolamine, polyoxyethylene
hydrogenated castor oil, polyoxyethylene sorbit beeswax,
polyoxyethylene sorbitan sesquistearate, polyoxyethylene
monooleate, and polyoxyethylene monolaurate. Examples of the ether
type include a polyoxyethylene alkyl ether and a polyoxyethylene
alkylphenyl ether, and specific examples thereof include
polyoxyethylene cetyl ether and polyoxyethylene lauryl ether.
[0039] Here, the ratio of an oily component to be extracted with
diethyl ether in the present invention is measured by a quick
residual fat extraction device OC-1 manufactured by Intec Co., Ltd.
or its equivalent machine or compatible machine. In this device, a
sample is put in an attached test tube having an extraction port at
a lower portion thereof, and when a solvent is supplied thereto, an
extraction liquid drops from the extraction port into a heated
aluminum pan located below, and only the solvent evaporates. The
mass of an extract is determined from a difference in the mass of
the aluminum pan between before and after dropping of the
extraction liquid, and an oily component in the sample can be
measured quickly and easily. Then, the ratio of the extract can be
calculated from the mass of the extract and the mass of the sample.
In the present invention, as the sample, two sets of tissue paper
in which one set includes three plies are used, and the amount of
diethyl ether used is 10 cc. Pushing with a push rod is started 60
seconds after addition of diethyl ether.
[0040] On the other hand, the tissue paper according to the present
invention has a bending rigidity of less than 0.006 gf-cm/cm in
machine direction and a bending recovery force of less than 0.005
gfcm/cm in machine direction. Values in these ranges are low for a
3-ply non-moisturizing tissue paper having a high basis weight of
12.0 g/m.sup.2 or more per ply. The tissue paper according to the
present embodiment contains a large amount of an oily component,
has a bond between fibers weakened, and therefore exhibits
remarkable characteristics in physical properties relating to a
paper strength in machine direction of the paper. The bending
rigidity in machine direction and the bending recoverability in
machine direction indicate values when a sample is bent at a right
angle to a flow direction of the sample, and a bending rigidity in
MD and a bending recoverability in MD indicate values when a sample
is bent parallel to a flow direction of the sample. The bending
rigidity in machine direction and the bending recovery force in
machine direction are indicators of bending in a direction
orthogonal to a crepe ridge. Therefore, when the bending rigidity
in machine direction and the bending recovery force in machine
direction are low, the tissue paper is supple and easily gives a
feeling of softness. Note that the bending rigidity in machine
direction and the bending recovery force in machine direction
according to the present invention are values measured by a pure
bending tester KES-FB2-A manufactured by Kato Tech Co., Ltd., or
its equivalent machine or a measuring device having a compatible
function therewith. At the time of measurement, a sample that has
been subjected to humidity control for three hours or more in a
constant temperature and humidity room at 23.degree. C. and 50% is
used, the size of the sample is 200.times.200 mm, the number of
measurements is N=5, and an average value thereof is used as a
measurement value. The bending rigidity correlates with softness
and rigidity felt by a person when the person bends an object. The
larger a value of the bending rigidity is, the more rigid a tissue
paper is. The smaller a value of the bending rigidity is, the
softer a tissue paper is. The bending recovery force correlates
with recoverability (elasticity) felt by a person when the person
bends an object and restores the object to an original state. The
larger a value of the bending recovery force, the poorer the
recoverability. The smaller a value of the bending recovery force,
the poorer the recoverability.
[0041] Furthermore, it is desirable that the tissue paper according
to the present invention has a dry tensile strength of 300 to 440
cN in MD and a dry tensile strength of 130 to 200 cN in machine
direction. A particularly preferable dry tensile strength in
machine direction is 150 to 180 cN. When the dry tensile strength
in MD is within a range of 300 to 440 cN, the dry tensile strength
is sufficient. On the other hand, a 3-ply tissue paper is easily
torn during use when the dry tensile strength in machine direction
is less than 130 cN. When the dry tensile strength in machine
direction exceeds 200 cN, an effect of improving softness is hardly
felt. The tissue paper according to the present invention has a low
dry tensile strength particularly in machine direction. The dry
tensile strength in MD is a paper strength in a direction in which
a crepe is stretched, and therefore the strength is easily adjusted
by the crepe. Note that a preferable crepe ratio during manufacture
of the tissue paper according to the present invention is 15 to
28%. Meanwhile, the dry tensile strength in machine direction is a
paper strength in a direction orthogonal to MD in which the crepe
is stretched, and therefore largely depends on a bond between
fibers and has an influence on a feeling of softness. The dry
tensile strength in machine direction according to the present
invention is slightly low as a 3-ply tissue paper, and this seems
to be because the ratio of an oily component to be extracted with
diethyl ether is large and therefore a hydrogen bond between fibers
is weakened. In the tissue paper according to the present
invention, the dry tensile strength particularly in MD is in a
general range, but the dry tensile strength particularly in machine
direction is slightly low, and therefore a feeling of softness is
easily felt. Note that the dry tensile strength according to the
present invention refers to a value measured at a sample width of
25 mm on the basis of the tensile test of JIS P 8113 (1998). A
known dry paper strength agent can be used in the adjustment of the
dry tensile strength of the present invention. As described above,
the tissue paper according to the present invention has a weak dry
tensile strength in machine direction as a 3-ply non-moisturizing
high-grade type tissue paper with a high basis weight. Furthermore,
the tissue paper according to the present invention has a lower
bending rigidity in machine direction and a lower bending recovery
force in machine direction than a conventional non-moisturizing
high-grade type tissue paper with a high basis weight, and
therefore has excellent softness and smoothness.
[0042] It is desirable that pulp fibers in the tissue paper
according to the present invention are obtained by blending
softwood kraft pulp (NBKP) and hardwood kraft pulp (LBKP).
Particularly, the pulp fibers preferably include only NBKP and
LBKP, and a blending ratio is preferably NBKP:LBKP=20:80 to 80:20.
Particularly, it is desirable that the blending ratio is
NBKP:LBKP=30:70 to 60:40. Paper strength, softness, and the like
can be adjusted by the blending ratio between NBKP and LBKP. In
addition, the tissue paper according to the present invention can
contain known fibers such as chemical fibers, kenaf fibers, and
cotton fibers within a range that does not impair the effect of the
present invention.
Examples
[0043] Next, for Examples of the tissue paper according to the
present invention and Comparative Examples, physical property
values were measured, and a sensory test was performed.
Composition/physical property values in each example are as
illustrated in Table 1 below. A method for measuring each of the
physical property values is as described above. In Comparative
Example 1, the paper thickness, bending resistance, and bending
recovery amount are not within the ranges of the present invention,
and the amount of extracted oil is within the range of the present
invention. Comparative Examples 2 to 5 are each a 2-ply high-grade
type having a basis weight of 14.0 g/m.sup.2 or more per ply.
[0044] In Examples 1 and 2, a weak cationic acidic softener
containing a nonionic activator and a cationic activator was used
as a softener at a low concentration of 25 to 35% by mass and a
viscosity of 500 Pa s or less so as to increase a fixing ratio. The
use amounts of the softener in Examples 1 and 2 were 0.35% by mass
and 0.40% by mass in terms of pulp mass ratio, respectively. Pulp
fibers in Examples 1 and 2 are 100% virgin pulp and do not contain
used paper pulp.
[0045] In the sensory test, evaluation was made as follows. The
sample in Comparative Example 2, which is a commercially available
product, was used as a reference sample. In Comparative Example 1,
softness and smoothness were highly evaluated in advance, and the
amount of an oily component to be extracted with diethyl ether was
the highest among those in Comparative Examples. As an evaluation
method, the reference sample was evaluated with 4 points, and the
samples in the other examples were evaluated with 1 to 7 points in
comparison with the reference sample. Note that as rough criteria,
criteria of 1 point: much worse than the reference sample
(unfavorable), 2 points: worse than the reference sample
(unfavorable), 3 points: slightly worse than the reference sample
(unfavorable), 4 points: the same as the reference item, 5 points:
slightly better than the reference item (favorable), 6 points:
better than the reference item (favorable), and 7 points: much
better than the reference item (favorable) were presented to test
subjects.
[0046] Regarding evaluation of smoothness, one set of tissue paper
was folded in half in cross direction, the half-folded sample was
placed on a horizontal table with a smooth surface, and smoothness
was judged when an index finger was slid once in machine direction
from an end to an end. Softness, moist feeling, and preference were
evaluated by free touch to one set of tissues by a test subject.
There were 11 test subjects, and each of the numerical values in
the table is an average of values obtained from the test subjects.
Note that FIG. 1 illustrates a graph of the results.
TABLE-US-00001 TABLE 1 Comparative Comparative Comparative
Comparative Comparative Example 1 Example 2 Example 1 Example 2
Example 3 Example 4 Example 5 Quality Amount of extracted 0.260
0.250 0.200 0.100 0.070 0.066 0.040 of product oily component paper
[% by mass] Water content 6.8 7.2 4.0 6.5 6.2 6.0 6.4 [% by mass]
Number of plies 3 3 3 2 2 2 2 [ply] Basis weight [g/m.sup.2] 13.3
13.6 12.8 14.7 16.1 14.9 15.1 Paper thickness 240 243 274 178 200
161 179 (one set) [.mu.m] Dry tensile strength 370 385 249 286 289
291 239 (MD) [cN] Dry tensile strength 162 168 85 87 98 112 85 (CD)
[cN] Pure B (Bending rigidity) 0.003 0.005 0.011 0.006 0.006 0.009
0.006 bending MD [gf cm/cm] test B (Bending rigidity) 0.002 0.003
0.009 0.007 0.006 0.007 0.007 CD [gf cm/cm] 2HB (Bending 0.004
0.004 0.008 0.008 0.008 0.012 0.007 recoverability) MD [gf cm/cm]
2HB(Bending 0.002 0.002 0.008 0.006 0.004 0.005 0.006
recoverability) CD [gf cm/cm] Sensory Smoothness 4.2 4.3 2.5 4.0
4.1 3.3 4.1 evaluation Softness 5.5 5.3 3.0 4.0 3.8 3.0 3.5 (N =
15) Thick Feeling 5.5 5.6 3.0 4.0 4.2 3.6 4.0 Moist feeling 5.3 5.1
2.3 4.0 3.3 3.0 4.5 Taste 5.5 5.3 2.1 4.0 4.0 3.5 3.5
[0047] As the results are illustrated in Table 1, it can be
confirmed that in Examples, the amount of the extracted oily
component is large and that the oily component is fixed. Meanwhile,
the samples in Examples each have a water content equal to those in
Comparative Examples, and are not hygroscopic unlike a polyol. In
addition, the physical property value of bending rigidity in
machine direction is low, indicating that bending resistance of one
sheet of tissue is low. The physical property value of bending
recoverability in machine direction is low, indicating that bending
recoverability of one sheet of tissue is favorable. The results of
the sensory evaluation in Examples are very good not only in
comparison with Comparative Example 2 using the reference sample
but also in comparison with all the other Comparative Examples.
[0048] In addition, in Comparative Example 1, the basis weight is
slightly low, the paper thickness is higher than that of the
present invention, and the density is excessively low. When the
density is excessively low in this way, the dry tensile strength in
MD and CD is lowered, but the bending recoverability and the
bending rigidity are not sufficiently lowered, and evaluation for
softness and smoothness is not enhanced. It is considered that this
is because the bending rigidity is increased due to a large
influence of the large paper thickness of one sheet of tissue. When
the results in Examples of the present invention are compared with
the results in Comparative Example 1, Examples of the present
invention have low bending recoverability and bending rigidity,
particularly have low bending recoverability in machine direction
and low bending rigidity in machine direction, and are
significantly highly evaluated in sensory evaluation.
[0049] Furthermore, when Examples are compared with Comparative
Examples 2 to 4, Comparative Examples 2 to 4 each have two plies,
and the total basis weight and the paper thickness are higher in
Examples. However, in Examples, the amount of extracted oil is
large, the bending recoverability and the bending rigidity in
machine direction are low, and the sensory evaluation is high.
Moreover, the dry tensile strength is high.
[0050] As described above, the 3-ply tissue paper according to the
present invention provides a non-moisturizing tissue paper having
better softness and smoothness, also providing a firm feeling and a
thick feeling, and having a high basis weight.
* * * * *