Rolled paper towel

Abstract

To provide a rolled paper towel in which easiness to wind up a roll and unlikeliness for the core to collapse is excellent, which is easy to use as a product, and has excellent physical distribution efficiency in the rolled paper towel in which a core outer diameter is within a fixed range, and which has high basis weight in 1 ply and excellent water absorption.SOLUTION: In a rolled paper towel, paper towel in 1 ply containing pulp fiber and synthetic fiber is wound up in a rolled shape. Basis weight of the paper towel is between 40 g / m2 and 150 g / m2, a winding diameter of the roll is between 75 mm and 160 mm, roll density is between 0.05 g / cm3 and 0.19 g / cm3, and a core external diameter of the roll is between 25 mm and 55 mm, and value shown by ((area of a roll core external diameter) / (cross sectional area of the roll except a hollow part from the center of the roll to the core))×100 is between 5 and 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION The present invention relates to a roll of paper towels comprising pulp fibers and synthetic fibers. [Background technology]

[0002] BACKGROUND ART In recent years, rolled paper towels, such as hand towel rolls and kitchen towel rolls, which are made by winding thick paper into a roll, have become commercially available. Paper towels have a variety of uses, including cleaning oil stains around the kitchen, wiping with water, and draining food. Paper towels are required to have excellent absorbency for water and oil, and to be strong enough to withstand continuous use without easily tearing when used for cleaning. To impart such strength to paper, a technology has been developed that involves hydroentangling pulp fibers with synthetic fibers.

[0003] As a prior art document on the technology of hydroentangling pulp fibers with synthetic fibers, for example, Patent Document 1 describes a nonwoven fabric wiper obtained by hydroentangling a pulp fiber web and a synthetic fiber web, in which the average fiber length of the pulp fibers contained in the pulp fiber web is 1.0 to 5.0 mm, and the basis weight of the nonwoven fabric wiper is 20 to 42 g / m 2 The nonwoven fabric wiper is characterized in that the composition ratio is 70 to 50 mass % of a pulp fiber web and 30 to 50 mass % of a synthetic fiber web. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-193634 Summary of the Invention [Problem to be solved by the invention]

[0005] With regular paper towels, the outer diameter of the core can be freely adjusted to match the roll length and diameter (also called the roll diameter), but with rolled paper towels made from high-basis-weight paper towels containing synthetic fibers, if the outer diameter of the core is too large within a certain range of roll diameter, the roll length will become shorter, resulting in poor logistics efficiency per roll.In addition, the core is more likely to be crushed when starting to wind or when cutting with a log saw (cutting machine).

[0006] Therefore, if the reel length is increased and the reel diameter is increased, the paper towel roll becomes difficult to hold, making it less user-friendly to use. Conversely, if the reel diameter is left the same and only the reel length is increased, the reel becomes tightly wound, making the core more susceptible to crushing when cut with a log saw. On the other hand, if the core outer diameter is made too small, in the case of high-basis-weight paper towels, the pickup (the tip of the paper towel that first comes into contact with the core when wound into a roll) will not wrap well.

[0007] For these reasons, it has been difficult to achieve a high level of compatibility between the core outer diameter, logistics efficiency, resistance to core crushing during winding and log saw cutting, ease of winding, and ease of use as a product when it comes to high-basis-weight roll paper towels.

[0008] The present invention has been made in view of the above circumstances, and its object is to provide a roll-shaped paper towel having a core outer diameter within a certain range, a single ply with a high basis weight and excellent water absorbency, which is easy to wind into a roll and resistant to core crushing, is easy to use as a product, and has good logistics efficiency. [Means for solving the problem]

[0009] The inventors have conducted extensive research and have found that, in a roll-shaped paper towel in which one ply of paper towel containing pulp fibers and synthetic fibers is wound into a roll, by specifying the basis weight of the paper towel, the winding diameter of the roll, the roll density, the outer diameter of the roll core, and the ratio of the area of ​​the outer diameter of the core to the cross-sectional area of ​​the roll within predetermined numerical ranges, it is possible to produce a roll-shaped paper towel in which the core outer diameter is within a certain range, has a high basis weight and excellent water absorbency, is easy to wind into the roll, is resistant to core crushing, is easy to use as a product, and has good logistics efficiency, thereby solving the above-mentioned problems and leading to the completion of the present invention. Specifically, the present invention provides the following:

[0010] (1) A first aspect of the present invention is a roll-shaped paper towel in which one ply of paper towel containing pulp fibers and synthetic fibers is wound into a roll, and the basis weight of the paper towel is 40 g / m 2 More than 150g / m 2 The roll diameter is 75 mm or more and 160 mm or less, and the roll density is 0.05 g / cm 3 More than 0.19g / cm 3 Hereinafter, the rolled paper towel is characterized in that the outer diameter of the roll core is 25 mm or more and 55 mm or less, and the value shown by ((area of ​​the outer diameter of the roll core) / (cross-sectional area of ​​the roll excluding the hollow portion from the center of the roll to the core)) x 100 is 5 or more and 40 or less.

[0011] (2) A second aspect of the present invention is a roll-shaped paper towel according to (1), wherein the cross-sectional area of ​​the roll, excluding the hollow portion from the center of the roll to the core, is 30 cm 2 over 190cm 2 It is characterized by the following:

[0012] (3) A third aspect of the present invention is a roll-shaped paper towel according to (1), characterized in that the bending stiffness of the paper towel in the MD direction is 10 μN·m or more and 130 μN·m or less.

[0013] (4) A fourth aspect of the present invention is the rolled paper towel according to (1), wherein the apparent basis weight of the core of the roll is 200 g / m 2 More than 520g / m 2 It is characterized by the following:

[0014] (5) A fifth aspect of the present invention is the rolled paper towel described in (1), characterized in that the DMDT of the paper towel is 8 N / 25 mm or more and 75 N / 25 mm or less, and the DCDT is 2 N / 25 mm or more and 50 N / 25 mm or less.

[0015] (6) A sixth aspect of the present invention is the rolled paper towel according to (1), characterized in that the core of the roll has a hardness of 0.4 mm or more and 3.0 mm or less.

[0016] (7) A seventh aspect of the present invention is a roll-shaped paper towel according to (1), characterized in that the value obtained by multiplying (the bending stiffness of the paper towel in the MD direction) by (the hardness of the core of the roll) is 5 or more and 360 or less.

[0017] (8) An eighth aspect of the present invention is the rolled paper towel according to (1), wherein the water absorption per unit area of ​​the paper towel is 210 g / m 2 More than 520g / m 2 It is characterized in that

[0018] (9) A ninth aspect of the present invention is the rolled paper towel according to (1), characterized in that the roll length is 7 m or more and 24 m or less.

[0019] (10) A tenth aspect of the present invention is the rolled paper towel according to (1), characterized in that the thickness of the paper towel is 200 μm or more and 1400 μm or less.

[0020] (11) An eleventh aspect of the present invention is the rolled paper towel according to (1), characterized in that the paper towel is a kitchen towel. [Effects of the Invention]

[0021] According to the present invention, a roll-shaped paper towel having a core outer diameter within a certain range, a single ply with a high basis weight and excellent water absorption, is provided that is easy to wind into a roll, is resistant to core crushing, is easy to use as a product, and has good logistics efficiency. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view showing the entire roll of paper towels of the present invention. [Figure 2] FIG. 1 is a diagram showing a height profile on the XY plane as observed by a microscope using shading. [Figure 3] FIG. 1 is a graph showing a height profile on the XY plane obtained by a microscope. [Figure 4] FIG. 1 is a diagram showing how to determine the embossing depth for the embossed rolled paper towel of the present invention. [Figure 5] FIG. 1 is a diagram showing a method for measuring the water absorption of the roll-shaped paper towel of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the form for carrying out the present invention (hereinafter referred to as the embodiment) will be described in detail with reference to the drawings. However, these are presented for the purpose of illustration only and are not intended to limit the present invention.

[0024] 1. Rolled paper towels 1 is a perspective view showing the entire paper towel roll 1 of the present invention. The paper towel roll 1 of the present invention is a paper towel roll 1 in which one ply of paper towel 1x containing pulp fibers and synthetic fibers is wound into a roll. The paper towel 1x is preferably provided with perforations (not shown) that are evenly spaced in the MD direction of the paper towel 1x and that run across the paper towel 1x in the CD direction. In this case, the MD (Machine Direction) direction is the direction in which the paper towel 1x is wound (the direction in which the paper towel 1x is manufactured, also called the flow direction), and the CD (Cross Direction) direction is the direction perpendicular to the MD direction (also called the width direction). The paper towel 1x of the present invention can be used as various paper products, and is preferably used as a wiper or kitchen towel, more preferably as a kitchen towel. Furthermore, although the present invention is a paper product used as a wiper or kitchen towel, it may also be used as a nonwoven fabric product.

[0025] 1, the surface of the paper towel 1x facing the outside of the roll is referred to as surface 1a (surface of the paper towel 1x), and the surface facing the center of the roll is referred to as back surface 1b (back surface of the paper towel 1x). Note that, due to hydroentanglement, as described below, it is preferable that the amount of synthetic fibers contained in the paper towel 1x be high on the surface side of the paper towel 1x (i.e., the surface 1a side) and low on the back surface 1b side.

[0026] (winding length and winding diameter) The roll length of the roll-shaped paper towel 1 is preferably 7 m or more and 24 m or less, more preferably 10 m or more and 22 m or less, and even more preferably 13 m or more and 18 m or less. If the roll length is less than 7 m, the logistics efficiency per roll will be poor if the roll diameter DR is not changed. If the roll length exceeds 24 m, the roll will be tightly wound if the roll diameter DR is not changed, and core collapse will be more likely to occur when cutting with a log saw. The roll diameter DR of the roll-shaped paper towel 1 is 75 mm or more and 160 mm or less, preferably 100 mm or more and 140 mm or less, and more preferably 108 mm or more and 130 mm or less. If the roll diameter DR is less than 75 mm, the roll diameter DR is too small, making the roll product less user-friendly. If the roll diameter DR is more than 160 mm, the roll diameter DR is too large, making the roll product less user-friendly.

[0027] The roll length is determined by measuring the length of 10 paper towels 1x between the perforations on the roll of paper towels 1. Then, the number of paper towels 1x on the roll of paper towels 1 is measured, and the roll length is calculated proportionally from the length of 10 sheets and the number of paper towels 1x. For example, if the length of 10 sheets is 1.80m and there are 150 paper towels 1x, the roll length is 1.80m x (150 / 10) = 27m. The roll diameter DR is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. The measurement is performed on 10 rolls of paper towels 1, and the measurement results are averaged. If there are no perforations, the roll length is measured.

[0028] (roll width and roll weight) The roll width of the rolled paper towel 1 is preferably 180 mm to 350 mm, more preferably 210 mm to 325 mm, and even more preferably 240 mm to 300 mm. By keeping the roll width within the above range, when using the rolled paper towel 1 of the present invention, which has a high basis weight and excellent water absorption, the area used is appropriate and it can absorb a large amount of water. The roll weight of the rolled paper towel 1 is preferably 100 g or more and 580 g or less, more preferably 180 g or more and 450 g or less, and even more preferably 220 g or more and 400 g or less. By keeping the roll weight within the above numerical range, a rolled paper towel 1 that is easy to handle as a product can be obtained. The roll weight is the weight of one roll per 275mm of roll width, excluding the core (core paper tube). If the roll width is not 275mm, it will be converted to the weight per 275mm by proportional calculation.

[0029] (roll density) The roll density of rolled paper towel 1 is 0.05 g / cm 3 More than 0.19g / cm 3 less than 0.07 g / cm 3 More than 0.17g / cm 3 Preferably, it is 0.09 g / cm or less. 3 More than 0.15g / cm 3 It is more preferable that the roll density is 0.05 g / cm or less. 3 If the roll density is less than 0.19 g / cm, the logistics efficiency per roll will be poor. 3 If it exceeds this value, the winding will be tight and the core will be easily crushed when cutting with a log saw.

[0030] The roll density is expressed as (roll mass) ÷ (roll volume). The roll mass is the mass of the rolled paper towel 1 per 275 mm of roll width. The roll volume is expressed as [{cross-sectional area of ​​the roll outer diameter (winding diameter DR)} - (cross-sectional area of ​​the core outer diameter)] × roll width (converted per 275 mm). For example, if 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 = 0.13 g / cm 3 If the rolled paper towel 1 does not have a core, the diameter of the hollow part in the center is the core outer diameter DI.

[0031] (cross-sectional area) The cross-sectional area of ​​the roll of paper towel 1, excluding the hollow area from the center of the roll to the core, is 30 cm 2 over 190cm 2 Preferably less than 60cm 2 More than 140cm 2 Preferably less than 80cm 2 More than 115cm 2It is more preferable that the cross-sectional area is 30 cm or less. 2 If the cross-sectional area is less than 190 cm, the winding diameter DR will be small, making the roll product less user-friendly. 2 If the diameter exceeds this, the winding diameter DR becomes large, and the roll product becomes less user-friendly. Note that the hollow portion from the center of the roll to the core means the hollow portion from the center of the roll to the outer diameter of the core.

[0032] 2. Core (Apparent basis weight and weight of core) The core (core paper tube) of the rolled paper towel 1 of the present invention is made of a plurality of layers of base paper, preferably two layers. In this case, the apparent basis weight of the core (basis weight of the core made of a plurality of layers of base paper) is 200 g / m 2 More than 520g / m 2 Preferably, it is 260 g / m or less. 2 More than 460g / m 2 More preferably, it is 320 g / m or less. 2 More than 420g / m 2 It is more preferable that the apparent basis weight is 200 g / m or less. 2 If the apparent basis weight is less than 520 g / m, the core will be too soft and will be prone to being crushed during winding and cutting with a log saw. 2 If the core exceeds this value, the core will be too hard, making it difficult to break when folding and discarding the core after using the roll, and the roll product will be less user-friendly. The apparent basis weight of the core is measured in accordance with JIS P 8124. The glue used to bond the two cores together can be any known glue, but it is preferable to use a PVAC (polyvinyl acetate) emulsion. By using glue with the above composition, it becomes easier to adjust the hardness of the core (described later) within a predetermined range, and a roll-shaped paper towel 1 can be obtained that is easy to wind into a roll and has good resistance to core crushing, as in the present application. Furthermore, the weight of the core (core paper tube) is preferably 6.5g or more and 17.5g or less, more preferably 7.5g or more and 16g or less, and even more preferably 9g or more and 14g or less. The weight of the core (core paper tube) is the weight per 275mm of roll width. If the roll width is not 275mm, it is converted to the weight per 275mm by proportional calculation.

[0033] (Core outer diameter) The core outer diameter DI, which is the outer diameter of the core (core paper tube) of the roll-shaped paper towel 1 of the present invention, is 25 mm or more and 55 mm or less, more preferably 32 mm or more and 47 mm or less, and even more preferably 36 mm or more and 42 mm or less. If the core outer diameter DI is less than 25 mm, the pickup will not wrap around the core well when rolled. If the core outer diameter DI exceeds 55 mm, the logistics efficiency per roll will be poor and the core will be more likely to be crushed during winding or cutting with a log saw. The core outer diameter DI is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. Measurements are made on 10 rolls of paper towels 1, and the measurement results are averaged. In the case of a roll of paper towels 1 without a core, the diameter of the hollow space in the center of the roll of paper towels 1 is considered to be the core outer diameter DI.

[0034] (Core outer diameter area) The area of ​​the core outer diameter DI of the rolled paper towel 1 of the present invention is 5 cm 2 More than 24cm 2 Preferably less than 8cm 2 More than 18cm 2 It is more preferable that it is less than 10cm 2 More than 14cm 2 More preferably, the area is 5 cm or less. 2 If the area is less than 24cm, the pickup will not wrap around the core properly. 2 If it exceeds this, the logistics efficiency per roll will be poor. Furthermore, the value of the roll-shaped paper towel 1, calculated by ((area of ​​the outer diameter DI of the roll core) / (cross-sectional area of ​​the roll excluding the hollow portion from the center of the roll to the core)) × 100, is 5 or more and 40 or less, preferably 7 or more and 20 or less, and more preferably 9 or more and 16 or less. If the value is less than 5, the core becomes too small, resulting in poor winding of the pickup around the core. If the value exceeds 40, the logistics efficiency per roll is poor.

[0035] (Core hardness) Furthermore, the core hardness of the roll-shaped paper towel 1 of the present invention is preferably 0.4 mm to 3.0 mm, more preferably 0.6 mm to 2.3 mm, and even more preferably 0.7 mm to 1.5 mm. If the core hardness is less than 0.4 mm, the core becomes too hard and is difficult to break when folding and discarding after use of the roll, making the roll product less user-friendly. If the core hardness exceeds 3.0 mm, the core is more likely to be crushed during winding and cutting with a log saw. The hardness of the core is measured using a compression tester (handy compression tester KES-G5 manufactured by Kato Tech Co., Ltd.) as follows: First, the core is placed horizontally on a hard table so that the axis is horizontal. Next, a compression tool (area 2.0 cm) of the KES-G5 is placed on the center of the outer surface of the core. 2 ) is pressed from above at a speed of 10 mm / min. The pressure with which the compression element presses the roll is 0.5 gf / cm 2 The indentation depth at this time is T a , pressure is 250gf / cm 2 The indentation depth at this time is T b As, (T b -T a ) is the hardness of the core. A high value indicates that the core is more likely to be crushed. Measurements are taken five times using five cores (one measurement per core), and the results are averaged.

[0036] 3. Paper towels In the roll-shaped paper towel 1 of the present invention, the paper towel 1x contains synthetic fibers and pulp fibers. Examples of synthetic fibers include nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene. However, to obtain a paper towel 1x with a high basis weight and excellent water absorbency as in the present invention, polyethylene and polypropylene are preferred, and polypropylene is more preferred. There are no restrictions on the nonwoven fabric used as the synthetic fiber, but spunbond nonwoven fabric is preferred. By using a polypropylene spunbond nonwoven fabric, even a paper towel 1x with a high basis weight as in the present invention can easily wrap around a pickup. Furthermore, the ease of use of the roll-shaped paper towel 1 is improved. Pulp fibers may be general pulp fibers such as softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP). The ratio of NBKP to 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. Preferred NBKP fibers are those made from, for example, radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. It is also possible to use NUKP instead of NBKP, and LUKP instead of LBKP.

[0037] In this case, the proportion (content) of synthetic fibers in the paper towel 1x is preferably 5% to 50%, more preferably 9% to 41%, and even more preferably 12% to 28%. If the proportion of synthetic fibers is less than 5%, the strength will be too weak, making it difficult to reuse the paper towel 1x and resulting in poor usability as a product. If the proportion of synthetic fibers exceeds 50%, the water absorbency will be poor. Furthermore, the proportion (content) of pulp fibers in the paper towel 1x is preferably 50% to 95%, more preferably 59% to 91%, and even more preferably 72% to 88%. If the proportion of pulp fibers is less than 50%, the water absorbency will be poor. If the proportion of pulp fibers exceeds 95%, the strength will be too weak, making it difficult to reuse the paper towel 1x and resulting in poor usability as a product.

[0038] Furthermore, the paper towel 1x preferably contains a common wet strength agent. The content of the wet strength agent (in terms of solids (active ingredients)) relative to the pulp fiber (bone dry) is preferably 0.05% to 1.0%, more preferably 0.10% to 0.5%, and even more preferably 0.20% to 0.40%. By keeping the wet strength agent content within the above numerical range, a rolled paper towel 1 with high basis weight and excellent water absorbency, as in the present application, can be obtained. If necessary, the paper towel 1x may contain a heat stabilizer, a lubricant, etc., as long as the purpose of the present invention is not impaired. Examples of heat stabilizers include phenolic stabilizers such as BHT (2,6-di-t-butyl-4-methylphenol).

[0039] (Basic weight) The basis weight of one paper towel (total basis weight of synthetic fiber and pulp fiber) is 40 g / m 2 More than 150g / m 2 or less, 48 ​​g / m 2 More than 110g / m 2 Preferably, it is 55 g / m or less. 2 More than 80g / m 2It is more preferable that the basis weight of one paper towel is 40 g / m or less. 2 If the basis weight of the paper towel roll 1 is less than 150 g / m, the water absorbency of the paper towel roll 1 will be poor. 2 If it exceeds this, the pickup will not wrap around the core as well.

[0040] The basis weight of the synthetic fiber in 1 paper towel is 4 g / m 2 More than 40g / m 2 Preferably, it is 7 g / m or less. 2 More than 30g / m 2 More preferably, it is 10 g / m or less. 2 More than 20g / m 2 It is more preferable that the basis weight of the synthetic fiber is 4 g / m or less. 2 If the weight is less than 40g / m, the strength will be too weak, making it difficult to reuse one paper towel, and the product will be less user-friendly. 2 If the strength exceeds this, the pickup will not wrap around the core properly, and the core will be easily crushed during winding. Furthermore, the basis weight of the pulp fiber contained in one paper towel is 33 g / m 2 More than 120g / m 2 Preferably, it is 38 g / m or less. 2 More than 90g / m 2 More preferably, it is 45 g / m or less. 2 More than 75g / m 2 It is more preferable that the basis weight of the pulp fiber is 33 g / m or less. 2 If the basis weight of the pulp fiber is less than 120 g / m, the absorbency is poor. 2 If it exceeds this value, the basis weight becomes too large and the pickup does not wrap around the core as well. The basis weight of paper towel 1x is measured in accordance with JIS P 8124. However, since it is difficult to measure the basis weight of the synthetic fiber and pulp fiber individually after hydroentanglement, as described below, they are measured, for example, by the following method.

[0041] First, prepare a 0.1 M acetic acid solution and a 0.1 M sodium acetate solution. Mix approximately 830 g of the 0.1 M acetic acid solution with approximately 160 g of the 0.1 M sodium acetate solution to adjust the pH to 4. This is the 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 one paper towel were placed in a vial and tightly capped. After shaking at 180 rpm and 40°C for 24 hours, the synthetic fiber was sampled from the vial and its mass was measured. The basis weights of the synthetic fiber and pulp fiber were calculated using the mass (0.5 g) of one paper towel (including synthetic fiber and pulp fiber) and the mass of the sampled synthetic fiber using the following formula: Synthetic fiber basis weight = Basis weight of 1 paper towel x (mass of synthetic fiber / mass of 1 paper towel) Pulp fiber basis weight = Basis weight of 1 paper towel x [(mass of 1 paper towel - mass of synthetic fiber) / mass of 1 paper towel]

[0042] (paper thickness) The thickness of the paper towel 1x is preferably 200 μm or more and 1400 μm or less, more preferably 400 μm or more and 1200 μm or less, and even more preferably 500 μm or more and 1000 μm or less. A paper thickness of less than 200 μm results in poor absorbency for the rolled paper towel 1. A paper thickness of more than 1400 μm results in a high basis weight of the paper towel 1x, which leads to poor winding around the pickup core. The paper thickness is measured using a thickness gauge (a 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 placed between the probe and the measuring table, and the gauge reading when the probe is lowered at a speed of 1 mm per second or less. The measurement is repeated 10 times and the results are averaged. The measurement is performed by stacking three paper towels 1x, and the value is divided by three to obtain the paper thickness value.

[0043] (DMDT and DCDT) The dry machine direction tensile strength (DMDT) of the paper towel 1x in the dry state according to JIS P 8113 is preferably 8 N / 25 mm or more and 75 N / 25 mm or less, more preferably 13 N / 25 mm or more and 65 N / 25 mm or less, and even more preferably 20 N / 25 mm or more and 50 N / 25 mm or less. If the DMDT is less than 8 N / 25 mm, the paper towel 1x becomes difficult to reuse, resulting in poor usability as a product. If the DMDT exceeds 75 N / 25 mm, the pickup will not wind well around the core. Furthermore, the core is more likely to be crushed during winding.

[0044] Furthermore, the dry cross direction tensile strength (DCDT) of the paper towel 1x in the dry state according to JIS P 8113 is preferably 2 N / 25 mm to 50 N / 25 mm, more preferably 4 N / 25 mm to 40 N / 25 mm, and even more preferably 5 N / 25 mm to 25 N / 25 mm. If the DCDT is less than 2 N / 25 mm, the paper towel 1x becomes difficult to reuse, resulting in poor usability as a product. If the DCDT exceeds 50 N / 25 mm, the pickup core does not wrap well. Furthermore, the core is more likely to be crushed during winding. DMDT and DCDT are measured based on JIS P 8113 as mentioned above, but the measurement conditions are a speed of 300 m / min, a test piece width of 25 mm, and a distance between grips of 100 mm. If it is not possible to ensure a distance of 100 mm between grips due to the spacing of the perforations or the sheet width, the distance may be shortened as appropriate.

[0045] (Sheet length and bending stiffness) The sheet length of the paper towel 1x is preferably 160 mm or more and 330 mm or less, more preferably 180 mm or more and 305 mm or less, and even more preferably 200 mm or more and 280 mm or less. By having the sheet length within the above numerical range, it is possible to obtain a roll-shaped paper towel 1 that is easy to wind into a roll and has good resistance to core crushing. The sheet length is the actual measurement value of the length in the MD direction of one paper towel 1x between perforations in the roll-shaped paper towel 1. Furthermore, the bending stiffness in the MD of the paper towel 1x is preferably 10 μN·m or more and 130 μN·m or less, more preferably 17 μN·m or more and 100 μN·m or less, and even more preferably 20 μN·m or more and 50 μN·m or less. If the bending stiffness is less than 10 μN·m, the basis weight and paper thickness of the paper towel 1x will be low, resulting in poor water absorption. If the bending stiffness exceeds 130 μN·m, the paper towel 1x will be too stiff, resulting in poor winding around the pickup core.

[0046] The bending stiffness in the machine direction of a paper towel 1x is measured using an L&W bending tester (manufactured by Lorentzen & Wettre) in accordance with the method described in ISO 2493. A test piece 38 mm wide and 100 mm long taken from a paper towel 1x is bent at a 15-degree bend angle and a 10 mm bend length (span of the sample stage). The bending stiffness (μN·m) is calculated using the following formula: Bending stiffness (μN·m) = 60 × bending resistance (mN) × bending length 10 (mm) 2 ÷(π × bending angle 15 (°) × sample width 38 (mm)) If it is not possible to obtain a 100 mm long test specimen, the length of the test specimen may be shortened. The test specimen should not include perforations, but if perforations are necessary to ensure the size of the test specimen, they may be included.

[0047] Furthermore, for paper towel 1x, the value obtained by multiplying (bending stiffness in the MD direction of paper towel 1x) by (hardness of the core of the roll) is preferably 5 or more and 360 or less, more preferably 10 or more and 210 or less, and even more preferably 15 or more and 75 or less. If the value is less than 5, the basis weight of paper towel 1x will be small, resulting in poor water absorbency. If the value exceeds 360, core crushing will be more likely to occur when the roll-shaped paper towel 1 is wound and cut with a log saw.

[0048] (Embossed) The rolled paper towel 1 (paper towel 1x) of the present invention is preferably embossed, and this is preferably done using a roll winder. The shape of the embossment itself can be any shape, including circle, oval, rectangle, square, floral pattern, polygon, letter, line, logo, etc., without particular limitation. However, to obtain a paper towel 1x with a high basis weight and excellent water absorbency as in the present invention, a hexagonal shape is preferred. The embossing depth is preferably 0.07 mm to 1.8 mm, more preferably 0.2 mm to 1.2 mm, and even more preferably 0.3 mm to 0.8 mm. By having the embossing depth within the above range, the thickness and bending stiffness of the paper towel 1x can be adjusted, making the rolled paper towel 1 easier to use.

[0049] The depth of the embossment is measured using a microscope. The microscope used can be a Keyence One-Shot 3D Measuring Macroscope VR-3100. The microscope image observation, measurement, and image analysis software can be the VR-H1A. The measurement conditions are a magnification of 12x and a field of view of 24mm x 18mm. The measurement magnification and field of view can be changed as needed depending on the desired size of the embossment.

[0050] Figure 2 shows a height profile on the XY plane taken with a microscope, with the height of the paper towel surface represented by shading. The hexagonal areas in Figure 2 that are shaded differently from the surrounding area 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 paper towel 1x. Furthermore, when measuring, three wraps of paper towel 1x are removed from the rolled paper towel 1, and the fourth wrap of paper towel 1x is used to measure the paper towel in its state. Furthermore, if there are perforations, they are measured while avoiding them. First, a line segment AB is drawn as shown in Figure 2, and the height profile shown in Figure 3 is obtained. Line segment AB should be drawn across the embossments. Line segment AB is drawn in the width direction (CD) of the paper towel 1x. However, if the spacing between embossments is, for example, 2 mm or more, the line segment may be drawn diagonally or in the machine direction. The height profile is a (measured) cross-sectional curve S that represents the unevenness of the actual sample surface of the paper towel 1x. However, it also contains noise (steep peaks due to fiber clumps, whisker-like fibers, or fiber-free areas on the surface of the paper towel 1x). Therefore, when calculating the height difference of the unevenness, it is necessary to remove such noise peaks. Therefore, the (measured) cross-sectional curve S in Figure 3 was smoothed using the weighted average radio button filter size of ±12 to obtain the cross-sectional curve W in Figure 4. Note that smoothing using the weighted average radio button filter can be achieved automatically using the analysis software described above. Then, in the graph shown in Figure 4, the average of the maximum values ​​on the vertical axis of the convex portion H1 and the convex portion H2 adjacent to the convex portion H1 was calculated, and the minimum value on the vertical axis of the concave portion D1 sandwiched between the convex portions H1 and H2 was determined. The value obtained by subtracting the minimum value from the average of the maximum values ​​thus obtained was used as the provisional embossing depth. Then, as shown in Figure 4, similar measurements were performed at two consecutive locations on the cross-sectional curve (the concave portion D1 and the concave portion D2 sandwiched between the convex portions H2 and H3) (two consecutive measurement results were obtained at this point). Then, the rolled paper towel 1 is rotated three times by 90 degrees in the direction of the flow of the paper towel 1x, and the same measurement as above is taken at each position (a total of four measurement positions in the direction of the flow), and the average value of the total eight positions (2 x 4) is finally adopted as the embossing depth.

[0051] (Water absorption) In the rolled paper towel 1 of the present invention, the amount of the paper towel 1x per unit area (1 m 2 per unit) has a water absorption capacity of 210g / m 2 More than 520g / m 2 Preferably, it is 260 g / m or less. 2 More than 430g / m 2 More preferably, it is 310 g / m or less. 2 More than 400g / m 2 It is more preferable that the water absorption per unit area is 210 g / m or less. 2 If the water absorption per unit area is less than 520 g / m, the water absorption capacity of the rolled paper towel 1 will be poor. 2 If the paper towel exceeds this value, the basis weight of the paper towel 1x will increase, and the paper towel will not wrap around the pickup core well. Furthermore, the water absorption per unit weight (per 1 g) of the paper towel 1x is preferably 3.0 g / g or more and 8.0 g / g or less, more preferably 3.5 g / g or more and 7.5 g / g or less, and even more preferably 4.0 g / g or more and 7.0 g / g or less. By having the water absorption per unit weight within the above numerical range, it is possible to obtain a roll-shaped paper towel 1 that has a high basis weight and excellent water absorption, is easy to wind into a roll, and is resistant to core crushing. The water absorption of each paper towel is measured as follows.

[0052] First, 1x paper towel is taken and cut using a square template with each piece measuring 7.6 cm (3 inches) to prepare a rectangular test piece 200 with each side measuring 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, and the jig is made of a metal that does not absorb water). Next, a commercially available tray is filled with distilled water to a depth of 2 cm, and the test specimen 200 set in the holder 220 is immersed in the distilled water for 2 minutes. After immersion for 2 minutes, the test specimen 200 and holder 220 are removed from the distilled water, and a band 210 is attached to one corner 200d of the test specimen 200 as shown in Figure 5. The band 210 is made by cutting a 2 mm wide x 15 mm long piece of paper towel, the same size as the sample to be measured, and attaching it to a section 6 mm from corner 200d toward the center of the test specimen 200. Next, the holder 220 and test specimen 200 are hung from a rod installed in an empty water tank with the corner 200a opposite corner 200d facing up, and the lid of the water tank is closed and left for 10 minutes. Thereafter, the holder 220 and test specimen 200 are removed from the water tank, the band 210 and holder 220 are removed, and the mass of the test specimen 200 is measured using 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 per unit area of ​​the test piece 200 (g (water) / m 2 (paper towel). In addition, the water absorption per unit area (g(water) / m 2 (paper towel)) by the basis weight of the test piece 200 to obtain the water absorption per unit area (g(water) / m 2(Paper towel)) / basis weight(g(Paper towel) / m 2 Calculate the amount of water absorbed per unit weight (g (water) / g (paper towel)) = g (water) / g (paper towel)). Measurements are taken five times for each sample, and the average value is used. This measurement is performed in accordance with JIS P 8111 at a temperature of 23±1°C and humidity of 50±2%. The distilled water is kept at 23±1°C.

[0053] 4. Method for manufacturing paper towels and rolled paper towels As for the manufacturing method of paper towel 1x and rolled paper towel 1, if paper towel 1x is a kitchen towel containing synthetic fibers and pulp fibers, it can be manufactured, for example, in the following order: (1) laminating pulp fibers onto a specified spunbond nonwoven fabric and hydroentangling, (2) heat embossing with a matched steel, (3) perforation processing, and (4) roll winding processing. In this case, in the (1) hydroentanglement step of the manufacturing method, the synthetic fibers are hydroentangled with the pulp fibers to obtain a nonwoven fabric containing the synthetic fibers and the pulp fibers. The hydroentanglement method is preferably performed by the method described in JP 2018-193634 A, for example.

[0054] 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. It will be apparent 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 such modifications and improvements can also be included within the technical scope of the present invention. [Example]

[0055] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0056] The rolled paper towels of Examples 1 to 26 and Comparative Examples 1 to 9 listed in Tables 2 to 4 were produced through the following steps: (1) laminating pulp fibers onto a polypropylene spunbond nonwoven fabric and hydroentangling, (2) heat embossing with a matched steel, (3) perforation, and (4) roll winding. Only Example 26 was a coreless rolled paper towel. The roll-shaped paper towels of all Examples and Comparative Examples were measured for the above-mentioned parameters and evaluated as follows. All measurement results and evaluations are shown in Tables 2 to 4.

[0057] Winding of the pickup around the core: The winding of the pickup around the core was evaluated as follows. The paper towel does not wrap around the core tightly enough, so it comes off easily when wound up, or the paper towel gets wrinkled. The wrapping around the core is a little weak, so it tends to come off the core when wound up, and the paper towel tends to wrinkle. : △ The paper wraps around the core well, is not easily separated from the core when wound up, and does not wrinkle easily. The paper wraps around the core well, hardly comes off the core when wound up, and there are no wrinkles in the paper towel.

[0058] Resistance to core crushing (when wound): The resistance to core crushing when a roll of paper towels was wound was evaluated as follows. The core is crushed significantly during winding: × The core gets crushed a little when winding: △ The core is hardly crushed during winding: ○ The core is not crushed at all when winding:◎

[0059] Resistance to core crushing (when cut with a log saw): The resistance to core crushing when cutting rolled paper towels with a log saw was evaluated as follows. Core is crushed when cutting with a log saw: × The core is slightly crushed when cutting with a log saw: △ The core is hardly crushed when cutting with a log saw: The core is not crushed at all when cutting with a log saw:◎

[0060] Usability of roll product: The ease of use of roll paper towels as a product was evaluated as follows. The roll diameter is too large or too small, making it difficult to use: × The roll diameter is a little too large or a little too small, making it a little difficult to use. The roll diameter is slightly larger or smaller, but it doesn't affect ease of use. The roll diameter is just right and easy to use:

[0061] Logistics Efficiency: The logistics efficiency of rolled paper towels was evaluated according to the criteria in Table 1. [Table 1]

[0062] Water absorbency: The water absorbency of the paper towel was evaluated as follows based on the amount of water absorbed per unit area of ​​the paper towel measured by the above-mentioned measuring method. Water absorption capacity: 159g / m 2 Below:×× Water absorption capacity: 160g / m 2 More than 209g / m 2 Below: × Water absorption capacity: 210g / m 2 More than 259g / m 2 Below:△ Water absorption capacity: 260g / m 2 More than 309g / m 2 Below:○ Water absorption capacity: 310g / m 2 That's all:◎

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] As shown in Tables 2 to 4, the rolled paper towels of Examples 1 to 26 all wrapped tightly around the pickup core, were less likely to be crushed during winding or log saw cutting, and were easy to use, had excellent logistics efficiency, and also had good water absorbency.On the other hand, the rolled paper towels of Comparative Examples 1 to 9 either wrapped weakly around the pickup core, were easily crushed during winding or log saw cutting, were poor in ease of use and logistics efficiency, or had poor water absorbency. As described above, the roll paper towel of the present invention is a single-ply roll paper towel with a high basis weight and excellent water absorbency, with a core outer diameter within a certain range, and is easy to wind into a roll and resistant to core crushing, making it easy to use as a product and providing good logistics efficiency. [Explanation of symbols]

[0067] 1 roll of paper towels 1a surface 1b back side 1e The outermost edge of a paper towel roll 1x paper towel 200 test specimens 200a, 200d corner 210 Obi 220 Holder

Claims

1. A rolled paper towel in which one ply of paper towel containing pulp fibers and synthetic fibers is wound into a roll, The paper towel has a basis weight of 40 g / m ２ 150g / m or more ２ is as follows: The bending stiffness of the paper towel in the MD direction is 10 μN m or more and 122 μN m or less, The paper towel has a thickness of 400 μm or more and 1200 μm or less, The roll diameter is 75 mm or more and 160 mm or less, and the roll density is 0.05 g / cm ３ 0.19g / cm or more ３ Hereinafter, the core outer diameter of the roll is 25 mm or more and 55 mm or less, A rolled paper towel characterized in that the value shown by ((outer diameter area of ​​the roll core) / (cross-sectional area of ​​the roll excluding the hollow portion from the center of the roll to the core)) x 100 is 5 or more and 40 or less.

2. The cross-sectional area of ​​the roll, excluding the hollow area from the center of the roll to the core, is 30 cm ２ 190cm or more ２ 2. The roll of paper towels according to claim 1, characterized in that:

3. The apparent basis weight of the core of the roll is 200 g / m ２ More than 520g / m ２ 2. The roll of paper towels according to claim 1, characterized in that:

4. 2. The rolled paper towel according to claim 1, wherein the DMDT of the paper towel is 8 N / 25 mm or more and 75 N / 25 mm or less, and the DCDT of the paper towel is 2 N / 25 mm or more and 50 N / 25 mm or less.

5. 2. The rolled paper towel according to claim 1, wherein the core of the roll has a hardness of 0.4 mm or more and 3.0 mm or less.

6. 2. The rolled paper towel according to claim 1, wherein the value of (bending stiffness in the MD direction of the paper towel) x (hardness of the core of the roll) is 5 or more and 360 or less.

7. The water absorption capacity of the paper towel per unit area is 210 g / m ２ More than 520g / m ２ 2. The roll of paper towels according to claim 1, characterized in that:

8. 2. The rolled paper towel according to claim 1, wherein the roll length is 7 m or more and 24 m or less.

9. 2. The roll of paper towels according to claim 1, wherein the paper towels are kitchen towels.

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