JP7654138B2 - Kitchen Towel Roll - Google Patents

Description

The present invention relates to a kitchen towel roll.

In recent years, products made of thick paper wound into rolls, such as hand towel rolls and kitchen towel rolls, have become commercially available.

The problem with paper kitchen towel roll sheets (hereafter referred to as kitchen towel sheets) is that they cannot be reused; once they have been used to wipe away moisture and dirt, it is difficult to squeeze out the moisture or remove the dirt from them from a durability standpoint, so they end up being thrown away at that point.
On the other hand, kitchen towel sheets made from nonwoven fabric containing synthetic fibers are highly durable and can be reused by rinsing off dirt with water, but they have a low water absorption capacity and cannot wipe away large amounts of water.

To address these problems, a technology for hydroentangling pulp fibers with synthetic fibers has been developed and is attracting attention.
As an example of a prior art document on the technology of hydroentangling pulp fibers with synthetic fibers, Patent Document 1 discloses a nonwoven fabric wiper obtained by hydroentangling a pulp fiber web and a synthetic fiber web, characterized in that the average fiber length of the pulp fibers contained in the pulp fiber web is 1.0 to 5.0 mm, the basis weight of the nonwoven fabric wiper is 20 to 42 g/ ^m2 , and the composition ratio is 70 to 50 mass% of the pulp fiber web and 30 to 50 mass% of the synthetic fiber web.

JP 2018-193634 A

In kitchen towel sheets manufactured by hydroentangling pulp fibers with synthetic fibers as described above, in order to increase the water absorption capacity, it is necessary to increase the amount of pulp fibers and increase (higher) the basis weight. However, if the amount of pulp fibers is increased, it becomes difficult to hydroentangle the entire pulp fibers, and the unentangled pulp fibers are likely to turn into paper powder (note that kitchen towel sheets made of 100% pulp fibers produce more paper powder because the pulp fibers are not hydroentangled with the synthetic fibers). For this reason, it has been difficult to produce kitchen towel sheets and kitchen towel rolls containing synthetic fibers and pulp fibers that have a high water absorption capacity and little paper powder.

The present invention was made in consideration of these circumstances, and its purpose is to provide a kitchen towel roll that is reusable, has a high water absorption capacity, produces little paper dust, and has a roll length of at least a certain level.

The inventors conducted extensive research and discovered that in a single-ply embossed kitchen towel roll containing synthetic fibers and pulp fibers, by setting the basis weight of the kitchen towel sheet, the depth of the embossing, and the winding length of the roll within predetermined numerical ranges, it is possible to produce a kitchen towel roll that is reusable, has high water absorption, and produces little paper dust, thereby solving the above-mentioned problems and completing the present invention.
Specifically, the present invention provides the following:

(1) A first aspect of the present invention is a kitchen towel roll comprising one ply of an embossed kitchen towel sheet containing synthetic fibers and pulp fibers, wound into a roll, characterized in that the kitchen towel sheet has a basis weight of 50 g/ ^m2 or more and 200 g/ ^m2 or less, the embossing depth is 0.1 mm or more and 2 mm or less, and the roll length is 5 m or more and 24 m or less.
(2) A second aspect of the present invention is the kitchen towel roll according to (1), characterized in that the roll density of the roll is 0.06 g/ ^cm3 or more and 0.19 g/ ^cm3 or less.
(3) A third aspect of the present invention is a kitchen towel roll according to (1) or (2), characterized in that the water absorption of the kitchen towel sheet per ^m2 is 270 g or more and 600 g or less, and the water absorption per gram is 2.5 g or more and 5.7 g or less.
(4) A fourth aspect of the present invention is a kitchen towel roll as described in any one of (1) to (3), characterized in that the kitchen towel sheet has a CD tensile strength (DCDT) of 4 N/25 mm or more and 80 N/25 mm or less when dry, and the ratio (DMDT/DCDT) of the MD tensile strength (DMDT) of the kitchen towel sheet when dry to the CD tensile strength (DCDT) of the kitchen towel sheet when dry is 1.2 or more and 4.5 or less.
(5) A fifth aspect of the present invention is a kitchen towel roll according to any one of (1) to (4), characterized in that the tensile strength in the MD direction (DMDT) of the kitchen towel sheet when dry is 15 N/25 mm or more and 115 N/25 mm or less.
(6) A sixth aspect of the present invention is a kitchen towel roll according to any one of (1) to (5), characterized in that the synthetic fiber content in the kitchen towel sheet is 5% or more and 45% or less, and the pulp fiber content is 55% or more and 95% or less.
(7) A seventh aspect of the present invention is a kitchen towel roll according to any one of (1) to (6), characterized in that the ratio of the wet MD tensile strength (WMDT) of the kitchen towel sheet to the dry MD tensile strength (DMDT) ((WMDT/DMDT) x 100(%)) is 50% or more and 95% or less.
(8) An eighth aspect of the present invention is a kitchen towel roll according to any one of (1) to (7), characterized in that the ratio of the wet CD tensile strength (WCDT) of the kitchen towel sheet to the dry CD tensile strength (DCDT) ((WCDT/DCDT) x 100 (%)) is 43% or more and 89% or less.
(9) A ninth aspect of the present invention is a kitchen towel roll according to any one of (1) to (8), characterized in that the kitchen towel sheet has a paper thickness of 0.45 mm or more and 1.8 mm or less.
(10) A tenth aspect of the present invention is a kitchen towel roll according to any one of (1) to (9), characterized in that the breaking elongation in the CD direction of the kitchen towel sheet is 50% or more and 100% or less.
(11) An eleventh aspect of the present invention is a kitchen towel roll according to any one of (1) to (10), characterized in that the breaking elongation in the MD direction of the kitchen towel sheet is 20% or more and 65% or less.
(12) A twelfth aspect of the present invention is a kitchen towel roll according to any one of (1) to (11), characterized in that the synthetic fibers have a basis weight of 8 g/ ^m2 or more and 55 g/ ^m2 or less, and the pulp fibers have a basis weight of 38 g/ ^m2 or more and 160 g/ ^m2 or less.

The present invention provides a kitchen towel roll that is reusable, has a high water absorption capacity, produces little paper dust, and has a certain roll length or greater.

FIG. 1 is a perspective view showing an entire kitchen towel roll of the present invention. FIG. 1 is a diagram showing a height profile on an XY plane by a microscope using shading. FIG. 1 is a graph showing a height profile on an XY plane obtained by a microscope. FIG. 2 is a diagram showing how to determine the embossing depth for the embossing of the kitchen towel roll of the present invention. FIG. 2 is a diagram showing a method for measuring the water absorption of the kitchen towel roll of the present invention.

The following describes in detail the form for carrying out the present invention (hereinafter, "embodiment") with reference to the drawings. However, these are presented for illustrative purposes and are not intended to limit the present invention.

1. Kitchen towel roll Fig. 1 is a perspective view showing the appearance of a kitchen towel roll 1 of the present invention. The kitchen towel roll 1 of the present invention is a kitchen towel roll 1 in which one ply of embossed kitchen towel sheet 1x containing synthetic fibers and pulp fibers is wound into a roll shape. Note that the kitchen towel sheet 1x is preferably perforated in the width direction at equal intervals in the machine direction (not shown).
The sheet 1x in the present invention can be used as various roll products other than kitchen towels, and is preferably used as a wiper, hand towel or kitchen towel, and most preferably as a kitchen towel.

As shown in FIG. 1, the surface of kitchen towel sheet 1x that faces the outside of the roll is called surface 1a (surface of kitchen towel sheet 1x), and the surface that faces the center of the roll is called back surface 1b (back surface of kitchen towel sheet 1x). It is preferable that the amount of synthetic fibers contained in kitchen towel sheet 1x due to hydroentanglement, which will be described later, is high on the surface side of kitchen towel sheet 1x (i.e., surface 1a side) and low on back surface 1b side.

(Roll length and diameter)
The roll length of the kitchen towel roll 1 is 5 m or more and 24 m or less, preferably 7 m or more and 20 m or more, and more preferably 8 m or more and 16 m or less. If the roll length is less than 5 m, it will not be the roll length required for a normal kitchen towel roll, and if the roll length exceeds 24 m, the basis weight must be lowered instead, resulting in poor water absorption.
The roll diameter DR of the kitchen towel roll 1 is preferably 105 mm to 155 mm, more preferably 110 mm to 140 mm, and even more preferably 115 mm to 130 mm. If the roll diameter DR is less than 105 mm, the roll length will not be greater than that required for a normal kitchen towel roll, and if the roll diameter DR exceeds 155 mm, the roll will be too large to use, and the high basis weight will result in a lot of paper dust.

The winding length is measured by measuring the length of 10 sheets of kitchen towel sheets 1x between perforations of kitchen towel roll 1. Then, the number of sheets of kitchen towel roll 1 is measured, and the winding length is calculated by proportional calculation from the length of 10 sheets and the number of sheets. For example, if the length of 10 sheets is 1.80 m and the number of sheets is 150, the winding length is 1.80 m x (150/10) = 27 m. If the kitchen towel roll 1 does not have perforations, the winding length can be measured by actual measurement. The roll winding diameter DR is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. The measurement is performed by measuring 10 kitchen towel rolls 1, and the measurement results are averaged.
In addition, the length between the perforations (the length of the sheet in the machine direction) is preferably 110 mm to 360 mm, more preferably 160 mm to 310 mm, and even more preferably 210 mm to 260 mm. By keeping it within this range, when using the kitchen towel roll 1 with a high water absorption capacity as in the present application, the area used is appropriate and a large amount of water can be absorbed.

(Roll width and roll weight)
The roll width of the kitchen towel roll 1 is preferably 150 mm to 380 mm, more preferably 200 mm to 350 mm, and even more preferably 250 mm to 300 mm. By setting the roll width within this range, when using the kitchen towel roll 1 with a high water absorption capacity as in the present application, the area used becomes appropriate and a large amount of water can be absorbed.
The roll weight of the kitchen towel roll 1 is preferably 170 g to 460 g, more preferably 250 g to 410 g, and even more preferably 280 g to 360 g. If the roll weight is less than 170 g, the roll length required for a normal kitchen towel roll will not be achieved, and if the roll weight exceeds 460 g, the basis weight of the kitchen towel sheet 1x will be high, resulting in a large amount of paper powder.
The roll mass is the mass of one roll per 275 mm of roll width, not including the core (paper tube). If the roll width is not 275 mm, it is converted to the mass per 275 mm by proportional calculation.

(Core outer diameter)
Furthermore, the core outer diameter DI, which is the outer diameter of the core of the kitchen towel roll 1 of the present invention, is preferably 30 mm or more and 60 mm or less, more preferably 34 mm or more and 55 mm or less, and even more preferably 37 mm or more and 50 mm or less. If the core outer diameter DI is less than 30 mm, the core will be too small and difficult to use when rolled, and if the core outer diameter DI exceeds 60 mm, the core will be too large and difficult to use when rolled.
The core outer diameter DI is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. Ten kitchen towel rolls 1 are measured, and the measurement results are averaged.

(Roll Density)
The roll density of the kitchen towel roll 1 is preferably 0.06 g/ ^cm3 or more and 0.19 g/ ^cm3 or less, more preferably 0.09 g/ ^cm3 or more and 0.17 g/cm3 or ^less , and even more preferably 0.11 g/ ^cm3 or more and 0.15 g/ ^cm3 or less. If the roll density of the kitchen towel roll 1 is less than 0.06 g/ ^cm3 , the roll length will be shortened by winding the roll softly to ensure the embossing depth, and if the roll density of the kitchen towel roll 1 exceeds 0.19 g/ ^cm3 , the embossing depth will be shallow and paper powder will increase.

The roll density is expressed by (roll mass)÷(roll volume). The roll mass is the mass of the kitchen towel roll 1 per 275 mm of roll width. The roll volume is expressed by [{cross-sectional area of the roll outer diameter (winding diameter DR) portion}-(cross-sectional area of the core outer diameter portion)]×roll width (converted per 275 mm). For example, when the roll mass (excluding the core) per 275 mm of roll width is 337 g, the winding diameter is 119 mm, and the core outer diameter is 49 mm, the roll density is 0.13 g/cm ^3. In addition, when the kitchen towel roll 1 does not have a core, the diameter of the central hole is taken as the core outer diameter DI.

2. Kitchen towel sheet The kitchen towel sheet 1x of the present invention contains synthetic fibers and pulp fibers as described above. Examples of synthetic fibers include nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, polystyrene, etc., but in order to obtain a kitchen towel sheet 1x with a high basis weight and a predetermined embossing as in the present invention, polyethylene and polypropylene are preferred, and polypropylene is more preferred. In addition, general pulp fibers such as softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP) can be used as the pulp fibers. The content ratio of NBKP and LBKP in the pulp fibers is preferably NBKP:LBKP=50:50 to 100:0, more preferably NBKP:LBKP=70:30 to 100:0, even more preferably NBKP:LBKP=90:10 to 100:0, and most preferably NBKP:LBKP=100:0. As the NBKP, for example, fibers made of radiata pine, slash pine, southern pine, lodgepole pine, spruce and Douglas fir are preferred. Note that NUKP can be used instead of NBKP, and LUKP can be used instead of LBKP.
In this case, the synthetic fiber content in the kitchen towel sheet 1x is preferably 5% to 45%, more preferably 9% to 38%, and even more preferably 12% to 28%. If the synthetic fiber content is less than 5%, it is difficult to hydroentangle the pulp fibers as described below, resulting in a large amount of paper powder in the kitchen towel sheet 1x, and if the synthetic fiber content exceeds 45%, the water absorption capacity of the kitchen towel sheet 1x is poor.
The pulp fiber content in the kitchen towel sheet 1x is preferably 55% or more and 95% or less, more preferably 62% or more and 91% or less, and even more preferably 72% or more and 88% or less. If the pulp fiber content is less than 55%, the water absorption capacity of the kitchen towel sheet 1x is poor, and if the pulp fiber content exceeds 95%, the kitchen towel sheet 1x will produce a lot of paper powder.

Furthermore, the kitchen towel sheet 1x preferably contains a general wet strength agent. The content of the wet strength agent (in terms of solids (active ingredients)) is preferably 0.05% to 1.0% of the pulp fiber (bone dry), more preferably 0.10% to 0.50%, and even more preferably 0.20% to 0.40%. By setting the content of the wet strength agent to the above range, it is possible to obtain a kitchen towel roll 1 having a high basis weight and a predetermined embossing, as in the present application.
If necessary, the kitchen towel sheet 1x may contain a heat stabilizer, a lubricant, etc., within the scope of the present invention. Examples of the heat stabilizer include phenolic stabilizers such as BHT (2,6-di-t-butyl-4-methylphenol).

(grammage)
The basis weight of the kitchen towel sheet 1x is 50 g/m2 or ^more and 200 g/ ^m2 or less, preferably 60 g/m2 or ^more and 170 g/m2 or ^less , and more preferably 100 g/ ^m2 or more and 140 g/ ^m2 or less. If the basis weight of the kitchen towel sheet 1x is less than 50 g/ ^m2 , the water absorption capacity of the kitchen towel sheet 1x is poor, and if the basis weight of the kitchen towel sheet 1x is more than 200 g/ ^m2 , the kitchen towel sheet 1x will produce a lot of paper powder.

The synthetic fiber contained in the kitchen towel sheet 1x preferably has a basis weight of 8 g/m2 or ^more and 55 g/m2 or ^less , more preferably 12 g/m2 or ^more and 45 g/ ^m2 or less, and even more preferably 15 g/m2 or ^more and 38 g/ ^m2 or less. If the synthetic fiber has a basis weight of less than 8 g/ ^m2 , it is difficult to hydroentangle the pulp fiber as described below, resulting in a large amount of paper powder in the kitchen towel sheet 1x, and if the synthetic fiber has a basis weight of more than 55 g/ ^m2 , the kitchen towel sheet 1x has poor water absorption.
Furthermore, the basis weight of the pulp fibers contained in the kitchen towel sheet 1x is preferably 38 g/m2 or ^more and 160 g/ ^m2 or less, more preferably 45 g/ ^m2 or more and 140 g/ ^m2 or less, and even more preferably 60 g/ ^m2 or more and 120 g/ ^m2 or less.
If the basis weight of the pulp fibers is less than 38 g/ ^m2 , the water absorption capacity of the kitchen towel sheet 1x will be poor, and if the basis weight of the pulp fibers exceeds 160 g/ ^m2 , the kitchen towel sheet 1x will produce a lot of paper powder.
The basis weight of the kitchen towel sheet 1x is measured in accordance with JIS P 8124. However, since it is difficult to measure the basis weights of the synthetic fibers and pulp fibers individually after hydroentanglement, which will be described later, they are measured, for example, by the following method.

First, prepare a 0.1 M acetic acid solution and a 0.1 M sodium acetate solution. Mix about 830 g of the 0.1 M acetic acid solution and about 160 g of the 0.1 M sodium acetate solution to make the pH 4, and use this as an acetate buffer solution. Add cellulase Onozuka P1500 (manufactured by Yakult Pharmaceutical Co., Ltd.) to this acetate buffer solution so that the amount added is 1 wt %.
50 ml of acetate buffer containing cellulase Onozuka P1500 and 0.5 g of kitchen towel sheet 1x are placed in a vial and tightly capped. After shaking for 24 hours at 180 rpm and 40°C, the synthetic fibers are collected from the vial and the mass of the synthetic fibers is measured. The basis weights of the synthetic fibers and pulp fibers are calculated from the mass (0.5 g) of kitchen towel sheet 1x (including synthetic fibers and pulp fibers) and the mass of the collected synthetic fibers using the following formula.
Synthetic fiber basis weight =
Basis weight of kitchen towel sheet 1x × (mass of synthetic fibers / mass of kitchen towel sheet 1x)
Basis weight of pulp fiber =
Basis weight of kitchen towel sheet 1x × [(mass of kitchen towel sheet 1x − mass of synthetic fiber) / mass of kitchen towel sheet 1x]

Furthermore, when it is difficult to measure using the above method, the basis weight is calculated by subtracting the basis weight of the synthetic fibers used from the basis weight of the pulp fibers. However, since the basis weights of the raw fabric (base paper) after hydroentanglement and the embossed kitchen towel sheet 1x differ (the basis weight is lower after embossing), the final basis weights of the synthetic fibers and pulp fibers are determined by making the following corrections.
For example, if the synthetic fiber has a basis weight of 26 g/ ^m2 , the base paper after hydroentanglement has a basis weight of 128 g/ ^m2 , and the kitchen towel sheet 1x after embossing has a basis weight of 125 g/ ^m2 , then the synthetic fiber has a basis weight of 26×125/128=25 g/ ^m2 , and the pulp fiber has a basis weight of 125−25=100 g/ ^m2 .

(Paper thickness and specific volume)
The thickness of the kitchen towel sheet 1x is preferably 0.45 mm or more and 1.8 mm or less, more preferably 0.55 mm or more and 1.45 mm or less, and even more preferably 0.75 mm or more and 1.2 mm or less. If the thickness is less than 0.45 mm, the water absorption of the kitchen towel sheet 1x is poor, and if the thickness exceeds 1.8 mm, the amount of paper powder of the kitchen towel sheet 1x increases. The paper thickness is measured using a thickness gauge (dial thickness gauge "PEACOCK" manufactured by Ozaki Seisakusho Co., Ltd.). The measurement conditions are a measurement load of 3.7 kPa, a probe diameter of 30 mm, a sample is placed between the probe and the measuring table, and the gauge is read when the probe is lowered at a speed of 1 mm or less per second. The measurement is repeated 10 times and the measurement results are averaged. The measurement is performed by stacking three kitchen towel sheets 1x, and the value is reduced to 1/3 to obtain the paper thickness value.
The specific volume of the kitchen towel sheet 1x is preferably 5 ^cm3 /g or more and 15 ^cm3 /g or less, more preferably 6 ^cm3 /g or more and 13 ^cm3 /g or less, and even more preferably 7 ^cm3 /g or more and 11 ^cm3 /g or less. If the specific volume is less than 5 ^cm3 /g, the water absorption capacity of the kitchen towel sheet 1x is poor, and if it exceeds 15 ^cm3 /g, the kitchen towel sheet 1x produces a lot of paper powder. The specific volume is expressed as the volume ^cm3 per unit g, obtained by dividing the paper thickness of the kitchen towel sheet 1x by the basis weight.

(Embossed)
The kitchen towel roll 1 (kitchen towel sheet 1x) of the present invention is embossed, and is preferably embossed by a roll winder. The shape of the embossed unit can be a circle, an ellipse, a rectangle, a square, a floral pattern, a polygon, a letter, a line, a logo, or the like, without any particular limitation, and a hexagonal shape is preferred to obtain a kitchen towel sheet 1x having a high basis weight and a predetermined embossing as in the present invention.
The depth of the embossing is 0.1 mm to 2 mm, preferably 0.3 mm to 1.5 mm, and more preferably 0.5 mm to 1.0 mm. If the depth of the embossing is less than 0.1 mm, the unevenness of the embossing is small, making it impossible to scrape off paper dust with the embossed part (concave), or the contact area increases when wiping something with the sheet because the embossing is shallow, resulting in more paper dust. If the depth exceeds 2 mm, the roll must be wound loosely to ensure the depth of the embossing, resulting in a shorter winding length of the kitchen towel roll 1.

The depth of the embossing is measured using a microscope. As a microscope, a product name "One Shot 3D Measuring Macroscope VR-3100" manufactured by KEYENCE Corporation can be used. As software for observing, measuring and analyzing microscope images, a product name "VR-H1A" can be used. The measurement conditions are a magnification of 12 times and a field of view area of 24 mm x 18 mm. The measurement magnification and field of view area may be changed as appropriate depending on the desired size of the embossing.

FIG. 2 shows a height profile on the XY plane by a microscope, and the height of the sheet surface is represented by shading. The hexagonal parts in FIG. 2, which are shaded differently from the surroundings, represent individual embossments. The depth of the embossment is determined by measuring the height difference of the embossment using the microscope. The measurement is performed on the surface 1a side of the kitchen towel sheet 1x. In addition, at the time of measurement, three revolutions of the kitchen towel sheet 1x are removed from the kitchen towel roll 1, and the fourth revolution of the sheet is used to perform the measurement in the sheet state. In addition, if there are perforations, the measurement is performed while avoiding the perforations.
First, a line segment AB is drawn as shown in FIG. 2 to obtain a height profile as shown in FIG. 3. The line segment AB may be drawn so as to cross the embossment. The line segment AB is drawn in the width direction of the kitchen towel, but if the distance between the embossments is, for example, 2 mm or more, the line segment may be drawn in an oblique direction or in the flow direction. The height profile is a (measured) cross-sectional curve S that represents the unevenness of the actual sheet sample surface, but it also contains noise (steep peaks due to fiber clumps on the sheet surface, fibers that grow in a whisker-like shape, or areas without fibers), and it is necessary to remove such noise peaks when calculating the height difference of the unevenness.
Therefore, the (measured) cross-sectional curve S in FIG. 3 is smoothed by setting the filter size of the weighted average radio button to ±12 to obtain the cross-sectional curve W in FIG. 4. The smoothing using the filter of the weighted average radio button can be obtained automatically by using the above-mentioned analysis software. Then, in the graph shown in FIG. 4, the average value of the maximum values on the vertical axis of the convex part H1 and the convex part H2 adjacent to H1 is calculated, and the minimum value on the vertical axis of the concave part D1 sandwiched between H1 and H2 is obtained. The value obtained by subtracting the minimum value from the average value of the maximum values thus obtained is set as the provisional emboss depth. Then, as shown in FIG. 4, the same measurement is performed on a total of two consecutive points on the cross-sectional curve (a total of two consecutive points of D1 and the concave part D2 sandwiched between H2 and the convex part H3) (two measurement results are obtained at this point). The kitchen towel sheet 1x is then rotated 90 degrees in the flow direction three times, and the same measurements as above are taken at each position (a total of four measurement positions in the flow direction), and the average value of the total eight positions (2 x 4) is ultimately used as the embossing depth.

(Water absorption amount)
In the present invention, the water absorption of the kitchen towel sheet 1x per ^m2 is preferably 270 g to 600 g, more preferably 310 g to 560 g, and even more preferably 360 g to 490 g. If the water absorption per ^m2 is less than 270 g, the water absorption of the kitchen towel sheet 1x is inferior, and if it exceeds 600 g, the kitchen towel sheet 1x produces a lot of paper powder.
In addition, the water absorption per gram of the kitchen towel sheet 1x is preferably 2.5 g to 5.7 g, more preferably 2.9 g to 5.3 g, and even more preferably 3.3 g to 4.8 g. If the water absorption per gram is less than 2.5 g, the water absorption per gram of the kitchen towel sheet 1x is inferior.
The water absorption of each of the kitchen towel sheets 1x is measured as follows.

First, a kitchen towel sheet 1x is taken and cut using a square template with each piece being 7.6 cm (3 inches) to prepare a rectangular test piece 200 with each side being 7.6 cm. Thereafter, the mass of the test piece 200 before water absorption is measured using an electronic balance. Then, the test piece 200 is set in a holder 220 (a jig that fixes three points of the test piece 200, the jig being made of a metal that does not absorb water).
Next, distilled water is poured into a commercially available tub to a depth of 2 cm, and the test piece 200 set in the holder 220 is immersed in the distilled water for 2 minutes. After immersion for 2 minutes, the test piece 200 is taken out of the distilled water together with the holder 220, and a band 210 is attached to one corner 200d of the test piece 200 as shown in FIG. 5. The band 210 is made by cutting the same kitchen towel sheet 1x as the sample to be measured into a size of 2 mm wide x 15 mm long, and attaching it to a part 6 mm from the corner 200d of the test piece 200 toward the center. Next, the holder 220 and the test piece 200 are hung on a rod installed in an empty water tank so that the corner 200a facing the corner 200d is on top, and the lid of the water tank is closed and left for 10 minutes. Then, the holder 220 and the test piece 200 are taken out of the water tank, the band 210 and the holder 220 are removed, and the mass of the test piece 200 is measured with an electronic balance. From the change in mass of the test piece 200 before and after immersion in distilled water, the amount of distilled water absorbed by the test piece 200 per ^m2 (g(water)/ ^m2 ( sheet )) is calculated. Furthermore, the amount of water absorbed per ^m2 (g(water)/ ^m2 ( sheet ))/basis weight (g(sheet)/m2(sheet))=the amount of water absorbed per ^gram (g(water)/ ^g ( sheet )) is calculated by dividing the amount of water absorbed per m2 (g(water)/ ^m2 ( sheet ))) by the basis weight of the test piece 200. The measurement is performed five times for each sample, and the average value is used.
The measurement is performed according to JIS P 8111 at a temperature of 23±1°C and a humidity of 50±2%. The distilled water is kept at 23±1°C.

(DMDT and DCDT)
The tensile strength DMDT (Dry Machine Direction Tensile Strength) in the MD direction of the kitchen towel sheet 1x when dry based on JIS P 8113 is preferably 15N/25mm or more and 115N/25mm or less, more preferably 20N/25mm or more and 100N/25mm or less, and even more preferably 35N/25mm or more and 80N/25mm or less. The tensile strength DCDT (Dry Cross Direction Tensile Strength) in the CD direction when dry is preferably 4N/25mm or more and 80N/25mm or less, more preferably 6N/25mm or more and 65N/25mm or less, and even more preferably 10N/25mm or more and 50N/25mm or less. If the DMDT is less than 15 N/25 mm or the DCDT is less than 4 N/25 mm, the strength of the kitchen towel sheet 1x is insufficient and it is easily torn, making it difficult to reuse.If the DMDT exceeds 115 N/25 mm or the DCDT exceeds 80 N/25 mm, the basis weight becomes high and the amount of paper powder in the kitchen towel sheet 1x increases.
In this case, the MD direction and CD direction refer to the manufacturing direction (machine direction) of the kitchen towel sheet 1x during production, and the CD direction is a direction perpendicular to the MD direction.

In addition, the ratio (DMDT/DCDT) of the tensile strength in the MD direction when dry (DMDT) to the tensile strength in the CD direction when dry (DCDT) of the kitchen towel sheet 1x is preferably 1.2 to 4.5, more preferably 1.4 to 4.0, and even more preferably 1.6 to 3.5. If the ratio is less than 1.2, the proportion of synthetic fibers will be high, resulting in poor water absorption. If the ratio exceeds 4.5, the DCDT will be low, and the kitchen towel sheet 1x may tear easily, making it difficult to reuse.

(WMDT and WCDT)
The tensile strength WMDT (Wet Machine Direction Tensile Strength) in the MD direction of the kitchen towel sheet 1x when wet based on the old JIS S 3104 is preferably 13N/25mm or more and 100N/25mm or less, more preferably 18N/25mm or more and 85N/25mm or less, and even more preferably 25N/25mm or more and 73N/25mm or less. In addition, the tensile strength WCDT (Wet Cross Direction Tensile Strength) in the CD direction when wet is preferably 3N/25mm or more and 65N/25mm or less, more preferably 4N/25mm or more and 55N/25mm or less, and even more preferably 9N/25mm or more and 45N/25mm or less. If the WMDT is less than 13 N/25 mm or the WCDT is less than 3 N/25 mm, the kitchen towel sheet 1x will be easily torn and difficult to reuse. If the WMDT is more than 100 N/25 mm or the WCDT is more than 65 N/25 mm, the basis weight will be high, resulting in more paper powder in the kitchen towel sheet 1x.

In addition, the ratio (WMDT/WCDT) of the tensile strength in the MD direction when wet (WMDT) to the tensile strength in the CD direction when wet (WCDT) of the kitchen towel sheet 1x is preferably 1.3 to 4.6, more preferably 1.5 to 4.1, and even more preferably 1.7 to 3.6. If the ratio is less than 1.3, the proportion of synthetic fibers will be high, resulting in poor water absorption. If the ratio exceeds 4.6, the kitchen towel sheet 1x will be easily torn and difficult to reuse.

Furthermore, the ratio of the tensile strength in the MD direction (WMDT) when wet to the tensile strength in the MD direction (DMDT) when dry of the kitchen towel sheet 1x ((WMDT/DMDT) x 100 (%)) is preferably 50% or more and 95% or less, more preferably 65% or more and 93% or less, and even more preferably 70% or more and 91% or less. Similarly, the ratio of the tensile strength in the CD direction (WCDT) when wet to the tensile strength in the CD direction (DCDT) when dry of the kitchen towel sheet 1x ((WCDT/DCDT) x 100 (%)) is preferably 43% or more and 89% or less, more preferably 60% or more and 86% or less, and even more preferably 65% or more and 83% or less. If the ratio of (WMDT/DMDT) is less than 50% or the ratio of (WCDT/DCDT) is less than 43%, the kitchen towel sheet 1x becomes easily torn and difficult to reuse. If the ratio of (WMDT/DMDT) exceeds 95% or the ratio of (WCDT/DCDT) exceeds 89%, the result is a high proportion of synthetic fibers, resulting in poor water absorption.

(Elongation at break)
The breaking elongation in the MD direction of the kitchen towel sheet 1x is preferably 20% or more and 65% or less, more preferably 28% or more and 53% or less, and even more preferably 33% or more and 48% or less. The breaking elongation in the CD direction of the kitchen towel sheet 1x is preferably 50% or more and 100% or less, more preferably 60% or more and 95% or less, and even more preferably 70% or more and 90% or less. By setting the breaking elongation in the MD direction or CD direction of the kitchen towel sheet 1x within the above range, a kitchen towel roll 1 that can be reused, has a large water absorption amount, and has little paper powder can be obtained. The breaking elongation in each direction of the kitchen towel sheet 1x is measured based on JIS P 8113.

3. Manufacturing Method of Kitchen Towel Sheet and Kitchen Towel Roll Kitchen towel sheet 1x and kitchen towel roll 1 can be manufactured, for example, by (1) laminating pulp fibers onto a specified spunbond nonwoven fabric and hydroentangling it, (2) embossing treatment, and (3) rolling up the fabric.
At this time, in (1) hydroentanglement, pulp fibers are hydroentangled with synthetic fibers to obtain a nonwoven fabric containing synthetic fibers and pulp fibers. The hydroentanglement method is preferably performed by, for example, the method described in JP 2018-193634 A. In addition, in (2) embossing, it is preferable to perform a thermal embossing treatment using a matched steel (steel match) with a roll winder. The embossing pattern is preferably a hexagonal shape.

Although the present invention has been described above using embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments and examples. It will be clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. Furthermore, it is clear from the claims that forms incorporating such modifications or improvements can also be included in the technical scope of the present invention.

The present invention will be described in detail below with reference to examples. Note that the present invention is not limited to the examples shown below.

The kitchen towel rolls of Examples 1 to 15 and Comparative Examples 1 to 7 shown in Table 2 were produced through the steps of (1) hydroentanglement, (2) embossing, and (3) roll winding. A commercially available 2-ply kitchen towel roll was also prepared. The above-mentioned parameters were measured for all the above examples, comparative examples, and commercially available kitchen towel rolls, and the following evaluations were performed. Although not specifically listed as parameters in Table 2 below, the calendar conditions were standardized, so that kitchen towel sheets with a high basis weight tend to have a low specific volume.
Amount of paper dust: A sensory evaluation of the amount of paper dust was conducted by 30 people. When using the kitchen towel sheet and kitchen towel roll to wipe dishes, the amount of paper dust that adhered to the hands or to the wiped dishes was evaluated as follows: Particularly excellent (significantly less): 5 points, Excellent (less): 4 points, Good (no problem): 3 points, Poor (more): 2 points, Particularly poor (significantly more): 1 point. The average value of the 30 people was calculated and rounded off to one significant digit.

Water absorption: The amount of water absorption was measured by the method described above, and the measured values were evaluated as shown in Table 1 below.

Winding length: The winding length was measured and evaluated as follows.
Less than 4m: 1 point 4m to 5m: 2 points 5m to 7m: 3 points 7m to 8m: 4 points 8m or more: 5 points

As shown in Table 2, the kitchen towel rolls of Examples 1 to 16 all had excellent water absorption, sufficient winding length, and little paper dust. On the other hand, the kitchen towel rolls of Comparative Examples 1 to 7 had little water absorption, were short winding length, or had a lot of paper dust.
As described above, the kitchen towel roll of the present invention can provide a reusable kitchen towel roll that has a large water absorption capacity, produces little paper dust, and has a certain or greater roll length.

1 Kitchen towel roll 1a Surface 1b Back surface 1e Edge of outermost roll of kitchen towel sheet 1x Kitchen towel sheet 200 Test piece 200a, 200d Corner 210 Band 220 Holder

Claims (3)

A kitchen towel roll is a one-ply kitchen towel sheet made of a nonwoven fabric obtained by hydroentangling synthetic fibers with pulp fibers and then embossing the nonwoven fabric, the kitchen towel sheet being wound into a roll.
The synthetic fiber has a basis weight of 13 g/m2 or ^more and 45 g/m2 or ^less , and the pulp fiber has a basis weight of 48 g/m2 ^or more and 135 g/m2 ^or less,
The kitchen towel sheet has a basis weight of 61 g/m2 ^or more and 158 g/m2 ^or less ,
The content of the synthetic fiber in the kitchen towel sheet is 10% or more and 36% or less, and the content of the pulp fiber is 64% or more and 86% or less,
The kitchen towel sheet has a tensile strength in the MD direction (DMDT) when dry of 21.4 N/25 mm or more and 91.0 N/25 mm or less;
The kitchen towel sheet has a CD tensile strength (DCDT) of 6.0 N/25 mm or more and 58.0 N/25 mm or less when dry;
The kitchen towel sheet has a breaking elongation in the MD direction of 29% or more and 52% or less,
The kitchen towel sheet has a breaking elongation in the CD direction of 64% or more and 92% or less,
The kitchen towel sheet has a wet tensile strength (WMDT) in the MD direction of 18.8 N/25 mm or more and 81.0 N/25 mm or less;
The wet tensile strength (WCDT) of the kitchen towel sheet in the CD direction is 4.9 N/25 mm or more and 48.5 N/25 mm or less;
The depth of the embossment formed by the embossing is 0.33 mm or more and 1.44 mm or less ,
The kitchen towel roll has a roll length of 7.3 m or more and 19.8 m or less ,
The kitchen towel roll has a roll density of 0.10 g/cm3 ^or more and 0.16 g/cm3 ^or less . 2. The kitchen towel roll according to claim 1 , wherein the kitchen towel sheet has a water absorption of 270 g or more and 600 g or less per ^m2 and a water absorption of 2.5 g or more and 5.7 g or less per gram. 3. The kitchen towel roll according to claim 1 , wherein the kitchen towel sheet has a paper thickness of 0.45 mm or more and 1.8 mm or less.