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] The present invention relates to a roll-shaped paper towel containing pulp fibers and synthetic fibers.

Background Art

[0002] In recent years, roll-shaped paper towels made of thick paper such as hand towel rolls and kitchen towel rolls wound in a roll shape have been commercially available. Paper towels have various uses such as cleaning oil stains around the kitchen, wiping water, and draining water from food. Paper towels are required to have excellent absorbency for water and oil and strength that does not easily tear even when used for cleaning purposes and can withstand continuous use. As a technique for imparting such strength to paper, a technique of water entangling pulp fibers with synthetic fibers has been developed.

[0003] As a prior art document of the technique of water entangling pulp fibers with synthetic fibers, for example, Patent Document 1 discloses a non-woven wipe obtained by subjecting a pulp fiber web and a synthetic fiber web to water entangling treatment, wherein 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 non-woven wipe is 20 to 42 g / m 2 and the composition ratio is 70 to 50% by mass of the pulp fiber web and 30 to 50% by mass of the synthetic fiber web.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of a normal paper towel, it is possible to freely adjust the outer diameter of the core according to the roll length and the roll diameter (also referred to as the winding diameter). However, in the case of a roll-shaped paper towel obtained by winding a high basis weight paper towel containing synthetic fibers, if the outer diameter of the core (core outer diameter) is made too large within a certain range of the roll diameter, the roll length becomes short, resulting in inferior logistics efficiency per roll. In addition, the core is likely to be crushed at the start of winding or during log saw (cutting machine) cutting.

[0006] Therefore, if the roll length is increased and the roll diameter is enlarged, it becomes difficult to hold by hand and is inferior in terms of ease of use as a roll-shaped paper towel product. Conversely, if only the roll length is increased while keeping the roll diameter as it is, it becomes a tightly wound roll, so the core is likely to be crushed during log saw cutting. On the other hand, if the core outer diameter is made too small, in the case of a high basis weight paper towel, the winding of the pickup (the tip portion of the paper towel that first contacts the core when winding in a roll shape) deteriorates.

[0007] From the above, in the case of a high basis weight roll-shaped paper towel, it has been difficult to achieve both high levels of ease of winding of the roll, resistance to core crushing during winding and log saw cutting, ease of winding, ease of use as a product, and good logistics efficiency.

[0008] The present invention has been made in view of such circumstances, and an object thereof is to provide a roll-shaped paper towel with a single ply, high basis weight, and excellent water absorption, in which the core outer diameter is within a certain range, and which has good ease of winding of the roll and resistance to core crushing, is easy to use as a product, and has good logistics efficiency.

Means for Solving the Problems

[0009] The inventors have conducted intensive studies and found that in a one-ply paper towel containing pulp fibers and synthetic fibers and wound into a roll-shaped paper towel, by defining the basis weight of the paper towel, the winding diameter of the roll, the roll density, the outer diameter of the core of the roll, and the ratio of the area of the core's outer diameter to the cross-sectional area of the roll within a predetermined numerical range, it is possible to obtain a roll-shaped paper towel with a one-ply, high basis weight, and excellent water absorption, where the outer diameter of the core is within a certain range, the roll is easy to wind, the core is difficult to collapse, it is easy to use as a product, and the logistics efficiency is good, thereby solving the above problems and completing the present invention. Specifically, the present invention provides the following.

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

[0011] (2) The second aspect of the present invention is the roll-shaped paper towel according to (1), wherein the cross-sectional area of the roll excluding the hollow part from the center of the roll to the core is 30 cm 2 or more and 190 cm 2 or less.

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

[0013] (4) The fourth aspect of the present invention is the roll-shaped paper towel according to (1), wherein the apparent basis weight of the core of the roll is 200 g / m 2 or more and 520 g / m 2 or less.

[0014] (5) The fifth aspect of the present invention is the roll-shaped paper towel according to (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 is 2 N / 25 mm or more and 50 N / 25 mm or less.

[0015] (6) The sixth aspect of the present invention is the roll-shaped paper towel according to (1), wherein the hardness of the core of the roll is 0.4 mm or more and 3.0 mm or less.

[0016] (7) The seventh aspect of the present invention is the roll-shaped paper towel according to (1), wherein the value represented by (the bending strength in the MD direction of the paper towel) × (the hardness of the core of the roll) is 5 or more and 360 or less.

[0017] (8) The eighth aspect of the present invention is the roll-shaped paper towel according to (1), wherein the water absorption per unit area of the paper towel is 210 g / m 2 or more and 520 g / m 2 or less.

[0018] (9) The ninth aspect of the present invention is the roll-shaped paper towel according to (1), wherein the roll length is 7 m or more and 24 m or less.

[0019] (10) The tenth aspect of the present invention is the roll-shaped paper towel according to (1), wherein the paper thickness of the paper towel is 200 μm or more and 1400 μm or less.

[0020] (11) The eleventh aspect of the present invention is the roll-shaped paper towel described in (1), characterized in that the paper towel is a kitchen towel.

Effect of the Invention

[0021] According to the present invention, in a roll-shaped paper towel with a core outer diameter within a certain range, having a single ply, a high basis weight, and excellent water absorbency, it is possible to provide a roll-shaped paper towel that has good roll winding ease and is difficult to crush the core, is easy to use as a product, and has good logistics efficiency.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0023] Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. However, these are presented for illustrative purposes and do not limit the present invention.

[0024] 1. Roll-shaped paper towel Figure 1 is a perspective view showing the entirety of the roll-shaped paper towel 1 of the present invention. The roll-shaped paper towel 1 of the present invention is a roll-shaped paper towel 1 in which a single-ply paper towel 1x containing pulp fibers and synthetic fibers is wound in a roll shape. Further, it is preferable that the paper towel 1x is perforated at equal intervals in the MD direction of the paper towel 1x and across the paper towel 1x in the CD direction (not shown). At this time, the MD (Machine Direction) is the direction in which the paper towel 1x is wound (the direction in which the paper towel 1x is manufactured, also referred to as the flow direction), and the CD (Cross Direction) is the direction orthogonal to the MD direction (also referred to as the width direction). In addition, the paper towel 1x in the present invention can be used as various paper products, and is preferably used for wiping or kitchen towel applications, and more preferably used for kitchen towel applications. Further, the present invention is a paper product used for wiping or kitchen towel applications, but may also be used as a non-woven fabric product.

[0025] As shown in Figure 1, among the surfaces of the paper towel 1x, the surface directed to the outside of the roll is referred to as surface 1a (the surface of the paper towel 1x), and the surface directed to the center of the roll is referred to as back surface 1b (the back surface of the paper towel 1x). In addition, in terms of the amount of synthetic fibers contained in the paper towel 1x due to the water flow entanglement described later, it is preferable that the surface side of the paper towel 1x (that is, the surface 1a side) is more and the back surface 1b side is less.

[0026] (Roll length and roll 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 is inferior when the roll diameter DR is not changed. If the roll length exceeds 24 m, it becomes a solid roll when the roll diameter DR is not changed, and the core collapse during log sawing is likely to occur. Also, 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 becomes too small, resulting in inferior usability as a roll product. If the roll diameter DR exceeds 160 mm, the roll diameter DR becomes too large, resulting in inferior usability as a roll product.

[0027] The roll length is measured as the length of 10 sheets of the paper towel 1x between the perforations of the roll-shaped paper towel 1. Then, the number of sheets of the paper towel 1x in the roll-shaped paper towel 1 is measured, and the roll length is obtained by proportional calculation from the length of 10 sheets and the number of sheets of the paper towel 1x. For example, when the length of 10 sheets is 1.80 m and the number of sheets of the paper towel 1x is 150, it becomes 1.80 m × (150 / 10) = 27 m. Also, the roll diameter DR of the roll is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. The measurement is performed on 10 roll-shaped paper towels 1, and the measurement results are averaged. When there are no perforations, the roll length is measured.

[0028] (Roll width and roll weight) The roll width of the roll-shaped paper towel 1 is preferably 180 mm or more and 350 mm or less, more preferably 210 mm or more and 325 mm or less, and even more preferably 240 mm or more and 300 mm or less. By setting the roll width within the above numerical range, when using the roll-shaped paper towel 1 with a high basis weight and excellent water absorption as in the present application, the area to be used becomes appropriate and a large amount of water can be absorbed. Also, the roll weight of the roll-shaped 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 setting the roll weight within the above numerical range, a roll-shaped paper towel 1 that is easy to handle as a product can be obtained. Note that the roll weight is the weight of one roll per 275 mm of roll width excluding the core (the paper tube of the core). When the roll width is not 275 mm, it is converted to the weight per 275 mm by proportional calculation.

[0029] (Roll density) The roll density of the roll-shaped paper towel 1 is 0.05 g / cm 3 or more and 0.19 g / cm 3 or less, and 0.07 g / cm 3 or more and 0.17 g / cm 3 or less is preferable, and 0.09 g / cm 3 or more and 0.15 g / cm 3 or less is more preferable. When the roll density is less than 0.05 g / cm 3 , the logistics efficiency per roll is inferior. When the roll density exceeds 0.19 g / cm 3 , it becomes a solid roll, and the core is likely to be crushed during log saw cutting.

[0030] The roll density is expressed as (roll mass) ÷ (roll volume). The roll mass is the mass of the roll-shaped paper towel 1 per 275 mm of roll width. The roll volume is expressed as [{cross-sectional area of the outer diameter (winding diameter DR) part of the roll} - (cross-sectional area of the outer diameter part of the core)] × roll width (converted to 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 outer diameter of the core is 49 mm, the roll density = 0.13 g / cm 3 . When there is no core in the roll-shaped paper towel 1, the diameter of the central hollow part is defined as the outer diameter DI of the core.

[0031] (Cross-sectional area) The cross-sectional area of the roll of the roll-shaped paper towel 1 excluding the hollow part from the center of the roll to the core is 30 cm 2 or more and 190 cm 2 or less is preferable, 60 cm 2 or more and 140 cm 2 or less is more preferable, 80 cm 2 or more and 115 cm 2It is more preferable that it is as follows. When the cross-sectional area is less than 30 cm 2 if it is less than that, the winding diameter DR becomes small, and it is inferior in terms of ease of use as a roll product. When the cross-sectional area exceeds 190 cm 2 if it exceeds that, the winding diameter DR becomes large, and it is inferior in terms of ease of use as a roll product. The hollow part from the center of the roll to the core means the hollow part from the center of the roll to the outer diameter of the core.

[0032] 2. Core (Apparent basis weight and weight of the core) In addition, the core (paper tube of the core) in the roll-shaped paper towel 1 of the present invention is formed by stacking a plurality of sheets of base paper, and it is more preferable that two sheets are stacked. At this time, the apparent basis weight of the core (the basis weight of the core formed by stacking a plurality of sheets of base paper) is 200 g / m 2 or more and 520 g / m 2 or less is preferable, 260 g / m 2 or more and 460 g / m 2 or less is more preferable, 320 g / m 2 or more and 420 g / m 2 or less is even more preferable. When the apparent basis weight is less than 200 g / m 2 the core becomes too soft, so core collapse is likely to occur during winding and log saw cutting. When the apparent basis weight exceeds 520 g / m 2 the core becomes too hard, so when the roll is used and then the core is folded and discarded, it becomes difficult to fold, etc., and it is inferior in terms of ease of use of the roll product. The apparent basis weight of the core is measured in accordance with JIS P 8124. In addition, although a known adhesive can be used when stacking two cores, it is preferable to use a PVAC (polyvinyl acetate) - based emulsion. By setting the adhesive to 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 with good winding ease of the roll as in the present application and difficulty of core collapse can be obtained. Further, the weight of the core (the paper tube of the core) is preferably 6.5 g or more and 17.5 g or less, more preferably 7.5 g or more and 16 g or less, and even more preferably 9 g or more and 14 g or less. The weight of the core (the paper tube of the core) is the weight per 275 mm of the roll width. When the roll width is not 275 mm, it is converted to the weight per 275 mm by proportional calculation.

[0033] (Core outer diameter) The core outer diameter DI, which is the outer diameter of the core (the paper tube of the core) 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. When the core outer diameter DI is less than 25 mm, the winding around the core of the pickup deteriorates when made into a roll. When the core outer diameter DI exceeds 55 mm, the logistics efficiency per roll is inferior, and the core is likely to be crushed during winding or log saw cutting. The core outer diameter DI is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. The measurement is performed on 10 roll-shaped paper towels 1, and the measurement results are averaged. Also, in the case of a roll-shaped paper towel 1 without a core, the diameter of the hollow portion at the center of the roll-shaped paper towel 1 is regarded as the core outer diameter DI.

[0034] (Area of the core outer diameter) The area of the core outer diameter DI in the roll-shaped paper towel 1 of the present invention is 5 cm 2 or more and 24 cm 2 or less, preferably 8 cm 2 or more and 18 cm 2 or less, more preferably 10 cm 2 or more and 14 cm 2 or less. When the area is less than 5 cm 2 , the winding around the core of the pickup deteriorates. When the area exceeds 24 cm 2 , the logistics efficiency per roll is inferior. In addition, for the roll-shaped paper towel 1, the value represented by ((the area of the core outer diameter DI of the roll) / (the cross-sectional area of the roll excluding the cavity from the center of the roll to the core)) × 100 is preferably 5 or more and 40 or less, more preferably 7 or more and 20 or less, and even 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 around the pickup core. If the value exceeds 40, the logistics efficiency per roll is inferior.

[0035] (Firmness of the core) Furthermore, the firmness of the core in the roll-shaped paper towel 1 of the present invention is preferably 0.4 mm or more and 3.0 mm or less, more preferably 0.6 mm or more and 2.3 mm or less, and even more preferably 0.7 mm or more and 1.5 mm or less. If the firmness of the core is less than 0.4 mm, the core becomes too hard, resulting in inferior usability as a roll product, such as being difficult to fold when discarding the core after using the roll. If the firmness of the core exceeds 3.0 mm, core collapse is likely to occur during winding and log saw cutting. The firmness of the core is measured as follows using a compression tester (Handy Compression Tester KES-G5 manufactured by Kato Tech Co., Ltd.). First, place the core horizontally on a hard table so that the axis is horizontal. Next, push the compression head (area 2.0 cm 2 ) of the above KES-G5 into the center of the core outer surface from above under the condition of a speed of 10 mm / min. Let the pushing depth when the pressure of the compression head pushing the roll is 0.5 gf / cm 2 be T a , and the pushing depth when the pressure is 250 gf / cm 2 be T b . Then, (T b -T a ) is defined as the firmness of the core. A larger value means that the core is more likely to be crushed. The measurement is performed 5 times using 5 cores (measuring once for each core), and the measurement results are averaged.

[0036] 3. Paper towel In the roll-shaped paper towel 1 of the present invention, the paper towel 1x contains synthetic fibers and pulp fibers. Examples of the synthetic fibers include nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, polystyrene, etc. However, in order 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 is no limitation on the non-woven fabric used as the synthetic fiber, but a spunbond non-woven fabric is preferred. By using a polypropylene spunbond non-woven fabric, even a paper towel 1x with a high basis weight as in the present application is easy to wrap around the pickup. Also, the usability as the roll-shaped paper towel 1 is improved. In addition, as the pulp fibers, general pulp fibers such as softwood kraft pulp (NBKP) and hardwood kraft pulp (LBKP) can be used. 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, still more preferably NBKP:LBKP = 90:10 to 100:0, and most preferably NBKP:LBKP = 100:0. As NBKP, for example, fibers composed 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.

[0037] At this time, the proportion (content ratio) of synthetic fibers in the paper towel 1x is preferably 5% or more and 50% or less, more preferably 9% or more and 41% or less, and still more preferably 12% or more and 28% or less. If the proportion of synthetic fibers is less than 5%, the strength becomes too weak, making it difficult to reuse the paper towel 1x and inferior in usability as a product. If the proportion of synthetic fibers exceeds 50%, the water absorbency is inferior. Also, the proportion (content ratio) of pulp fibers in the paper towel 1x is preferably 50% or more and 95% or less, more preferably 59% or more and 91% or less, and still more preferably 72% or more and 88% or less. If the proportion of pulp fibers is less than 50%, the water absorbency is inferior. If the proportion of pulp fibers exceeds 95%, the strength becomes too weak, making it difficult to reuse the paper towel 1x and inferior in usability as a product.

[0038] Furthermore, it is preferable that the paper towel 1x contains a general wet strength agent. The content rate of the wet strength agent (in terms of solid content (active ingredient)) is preferably 0.05% or more and 1.0% or less, more preferably 0.10% or more and 0.5% or less, and still more preferably 0.20% or more and 0.40% or less with respect to the pulp fibers (bone-dry). By setting the content rate of the wet strength agent within the above numerical range, it is possible to obtain the roll-shaped paper towel 1 with a high basis weight and excellent water absorbency as in the present application. Also, if necessary, a heat stabilizer, a lubricant, etc. can be blended in the paper towel 1x within a range that does not impair the object of the present invention. Examples of the heat stabilizer include phenolic stabilizers such as BHT (2,6-di-t-butyl-4-methylphenol).

[0039] (Basis weight) The basis weight (total basis weight of synthetic fibers and pulp fibers) of the paper towel 1x is 40 g / m 2 or more and 150 g / m 2 or less, and preferably 48 g / m 2 or more and 110 g / m 2 or less, and more preferably 55 g / m 2 or more and 80 g / m 2It is more preferable that the basis weight of the paper towel 1x is 40 g / m 2 If it is less, the water absorbency as the roll-shaped paper towel 1 is inferior. If the basis weight of the paper towel 1x exceeds 150 g / m 2 the winding around the core of the pickup deteriorates.

[0040] Also, the basis weight of the synthetic fiber contained in the paper towel 1x is preferably 4 g / m 2 or more and 40 g / m 2 or less, more preferably 7 g / m 2 or more and 30 g / m 2 or less, still more preferably 10 g / m 2 or more and 20 g / m 2 or less. If the basis weight of the synthetic fiber is less than 4 g / m 2 the strength becomes too weak, making it difficult to reuse the paper towel 1x and inferior in usability as a product. If the basis weight of the synthetic fiber exceeds 40 g / m 2 the strength becomes too strong, so the winding around the core of the pickup deteriorates. Also, core collapse during winding is likely to occur. Furthermore, the basis weight of the pulp fiber contained in the paper towel 1x is preferably 33 g / m 2 or more and 120 g / m 2 or less, more preferably 38 g / m 2 or more and 90 g / m 2 or less, still more preferably 45 g / m 2 or more and 75 g / m 2 or less. If the basis weight of the pulp fiber is less than 33 g / m 2 the water absorbency is inferior. If the basis weight of the pulp fiber exceeds 120 g / m 2 the basis weight increases and the winding around the core of the pickup deteriorates. Note that the basis weight of the paper towel 1x is measured based on JIS P 8124. However, since it is difficult to measure the basis weights of the synthetic fiber and the pulp fiber individually after the water flow entanglement described later, for example, they are measured by the following method.

[0041] First, prepare 0.1 M aqueous acetic acid solution and 0.1 M aqueous sodium acetate solution. Mix approximately 830 g of 0.1 M aqueous acetic acid solution and approximately 160 g of 0.1 M aqueous sodium acetate solution to adjust the pH to 4, and use this as the acetic acid buffer solution. Add cellulase Onozuka p1500 (manufactured by Yakult Pharmaceutical Industry Co., Ltd.) to this acetic acid buffer solution so that the added amount is 1% by weight. Put 50 ml of the acetic acid buffer solution added with cellulase Onozuka p1500 and 1 x 0.5 g of paper towel into a vial and tightly cap it. Next, after shaking at 180 rpm and 40 °C for 24 hours, collect the synthetic fiber from the vial and measure the mass of the synthetic fiber. From the mass of 1 x (0.5 g) of the paper towel (including synthetic fiber and pulp fiber) and the mass of the collected synthetic fiber, calculate the basis weight of each of the synthetic fiber and the pulp fiber according to the following formula. Basis weight of synthetic fiber = Basis weight of 1 x paper towel × (mass of synthetic fiber / mass of 1 x paper towel) Basis weight of pulp fiber = Basis weight of 1 x paper towel × [(mass of 1 x paper towel - mass of synthetic fiber) / mass of 1 x paper towel]

[0042] (Paper thickness) The paper thickness of 1 x paper towel 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. If the paper thickness is less than 200 μm, the water absorption as a roll of paper towel 1 is inferior. If the paper thickness exceeds 1400 μm, the basis weight of 1 x paper towel increases, and the winding around the core of the pickup deteriorates. 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 measuring head diameter of 30 mm. Place the sample between the measuring head and the measuring table, and read the gauge when the measuring head is lowered at a speed of 1 mm or less per second. Also, repeat the measurement 10 times and average the measurement results. The measurement is performed by stacking 3 sheets of 1 x paper towel and dividing the value by 1 / 3 to obtain the paper thickness value.

[0043] (DMDT and DCDT) The dry machine direction tensile strength DMDT (Dry Machine Direction Tensile Strength) of the paper towel 1x based on 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 still more preferably 20 N / 25 mm or more and 50 N / 25 mm or less when dried. If DMDT is less than 8 N / 25 mm, it becomes difficult to reuse the paper towel 1x and it is inferior in terms of ease of use as a product. If DMDT exceeds 75 N / 25 mm, the winding around the core of the pickup deteriorates. Also, the core is likely to be crushed during winding.

[0044] Also, the dry cross direction tensile strength DCDT (Dry Cross Direction Tensile Strength) of the paper towel 1x based on JIS P 8113 is preferably 2 N / 25 mm or more and 50 N / 25 mm or less, more preferably 4 N / 25 mm or more and 40 N / 25 mm or less, and still more preferably 5 N / 25 mm or more and 25 N / 25 mm or less when dried. If DCDT is less than 2 N / 25 mm, it becomes difficult to reuse the paper towel 1x and it is inferior in terms of ease of use as a product. If DCDT exceeds 50 N / 25 mm, the winding around the core of the pickup deteriorates. Also, the core is likely to be crushed during winding. DMDT and DCDT are measured based on JIS P 8113 as described above. As the measurement conditions, the speed is 300 m / min, the test piece width is 25 mm, and the distance between the grippers is 100 mm. If it is not possible to secure a distance of 100 mm between the grippers due to the relationship between the perforation interval and the sheet width, it may be shortened appropriately.

[0045] (Sheet length and bending resistance) 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 the sheet length being within the above numerical range, a roll-shaped paper towel 1 with good ease of winding of the roll and difficulty of core collapse can be obtained. The sheet length is a value measured for the length in the MD direction of one paper towel 1x between the perforations of the roll-shaped paper towel 1. Also, the bending stiffness in the MD direction 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 are low, resulting in inferior water absorption. If the bending stiffness exceeds 130 μN·m, the paper towel 1x becomes too hard, resulting in poor winding around the pick-up core.

[0046] The bending stiffness in the MD direction of the paper towel 1x is measured using an L&W Bending Tester (manufactured by Lorentzen & Wettre) in accordance with the method described in ISO 2493. For a test piece with a width of 38 mm and a length of 100 mm taken from the paper towel 1x, the measured value when the bending angle is 15 degrees and the bending length (span of the specimen stage) is 10 mm is taken as the bending resistance (load), and the bending stiffness (μN·m) is obtained by the following calculation formula. Bending stiffness (μN·m) = 60 × Bending resistance (mN) × Bending length 10 (mm) 2 ÷ (π × Bending angle 15 (°) × Sample width 38 (mm)) In addition, when a test piece with a length of 100 mm cannot be taken, the length of the test piece can be shortened. Also, the test piece should not include perforations, but may include perforations when it is necessary to include them to ensure the size of the test piece.

[0047] Furthermore, in the paper towel 1x, the value represented by (the bending strength of the paper towel 1x in the MD direction) × (the hardness of the roll core) 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 the paper towel 1x becomes small, resulting in poor water absorbency. If the value exceeds 360, core collapse is likely to occur during winding and log saw cutting of the roll-shaped paper towel 1.

[0048] (Emboss) The roll-shaped paper towel 1 (paper towel 1x) of the present invention is preferably embossed, and preferably embossed by a roll winder. The shape of the emboss alone can be used without particular limitation, such as circular, elliptical, rectangular, square, floral pattern, polygonal, character, line, logo, etc. However, to obtain a paper towel 1x with a high basis weight and excellent water absorbency as in the present application, a hexagonal shape is preferable. Also, the depth of the emboss is preferably 0.07 mm or more and 1.8 mm or less, more preferably 0.2 mm or more and 1.2 mm or less, and even more preferably 0.3 mm or more and 0.8 mm or less. By the depth of the emboss being within the above numerical range, the paper thickness and bending strength of the paper towel 1x can be adjusted, and the usability as the roll-shaped paper towel 1 is improved.

[0049] The depth of the emboss is measured using a microscope. As the microscope, the product name "One-shot 3D Measurement Macroscope VR-3100" manufactured by KEYENCE Corporation can be used. As the software for observing, measuring, and image analyzing the microscope image, the product name "VR-H1A" can be used. Also, the measurement conditions are measurement under the conditions of a magnification of 12 times and a field area of 24 mm × 18 mm. The measurement magnification and field area may be appropriately changed depending on the size of the emboss to be obtained.

[0050] Figure 2 shows the height profile on the X-Y plane by a microscope, and the height of the paper towel surface is represented by shading. The hexagonal part with shading different from the periphery in Figure 2 indicates individual embosses. The depth of the emboss is obtained by measuring the height difference of the above emboss using the above microscope. Note that the measurement is performed on the surface 1a side of the paper towel 1x. Also, at the time of measurement, three turns of the paper towel 1x are removed from the roll-shaped paper towel 1, and the measurement is performed in the state of the paper towel 1x using the fourth turn of the paper towel 1x. Also, if there is a perforation, avoid measuring it. First, draw a line segment AB as shown in Figure 2 to obtain the height profile in Figure 3. Note that the line segment AB may be drawn so as to cross the emboss. Also, the line segment AB is drawn in the width direction (CD direction) of the paper towel 1x. However, if the interval between the embosses 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 representing the unevenness of the actual sample surface of the paper towel 1x, but it also includes noise (sharp peaks caused by fiber lumps on the surface of the paper towel 1x, fibers extending like whiskers, or parts without fibers). When calculating the height difference of the unevenness, it is necessary to remove such noise peaks. Therefore, the (measurement) cross-sectional curve S in FIG. 3 is used with the filter size of the weighted average radio button set to ±12, and the smoothed cross-sectional curve W in FIG. 4 is obtained. Note that smoothing using the filter of the weighted average radio button can be automatically obtained by using the above analysis software. Then, in the graph shown in FIG. 4, the average value of the maximum values of the vertical axes of the convex portion H1 of the graph and the convex portion H2 adjacent to the convex portion H1 is calculated, and the minimum value of the vertical axis in the concave portion D1 sandwiched between the convex portion H1 and the convex portion H2 is obtained. The numerical value obtained by subtracting the minimum value from the average value of the maximum values thus obtained is set as the provisional embossing depth. Then, as shown in FIG. 4, the same measurement is performed for a total of two consecutive locations on the cross-sectional curve (a total of two consecutive locations, the concave portion D1 and the concave portion D2 sandwiched between the convex portion H2 and the convex portion H3) (two measurement results are obtained at this time). After that, the same measurement as above is performed at each position where the roll-shaped paper towel 1 is rotated three times by 90 degrees each in the flow direction of the paper towel 1x (the measurement positions in the flow direction are a total of four locations), and the average value of a total of eight locations (2×4) is finally adopted as the embossing depth.

[0051] (Water absorption capacity) In the roll-shaped paper towel 1 of the present invention, the water absorption capacity per unit area (1 m 2 per) of the paper towel 1x is preferably 210 g / m 2 or more and 520 g / m 2 or less, more preferably 260 g / m 2 or more and 430 g / m 2 or less, and even more preferably 310 g / m 2 or more and 400 g / m 2 or less. If the water absorption capacity per unit area is less than 210 g / m 2 , the water absorbency of the roll-shaped paper towel 1 is inferior. If the water absorption capacity per unit area exceeds 520 g / m 2 , the basis weight of the paper towel 1x increases, and the winding around the pickup core deteriorates. Moreover, 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, a roll-shaped paper towel 1 with a high basis weight and excellent water absorbency, good roll winding ease, and low core crushing tendency can be obtained. In addition, the water absorption of each paper towel 1x is measured as follows.

[0052] First, collect the paper towel 1x, cut it using a template with a square of 7.6 cm (3 inches) on one side to produce 200 test pieces in the shape of a rectangle with a side length of 7.6 cm. Then, measure the mass of the test piece 200 before water absorption with an electronic balance. And set the test piece 200 on the 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 moisture). Next, pour 2 cm deep of distilled water into a commercially available bathtub, and immerse the test piece 200 set on the holder 220 in the distilled water for 2 minutes. After immersing for 2 minutes, take out the test piece 200 together with the holder 220 from the distilled water, and as shown in Fig. 5, attach a strip 210 to one corner 200d of the test piece 200. The strip 210 is cut from the same paper towel 1x as the sample to be measured to a size of 2 mm in width × 15 mm in length, and attached to a portion 6 mm from the corner 200d of the test piece 200 towards the center. Next, hang the holder 220 and the test piece 200 on a rod installed in an empty water tank with the corner 200a opposite to the corner 200d facing up, close the lid of the water tank, and leave it for 10 minutes. Then, take out the holder 220 and the test piece 200 from the water tank, remove the strip 210 and the holder 220, and measure the mass of the test piece 200 with an electronic balance. From the mass change of the test piece 200 before and after immersion in distilled water, calculate the water absorption of distilled water per unit area (g(water) / m 2 (paper towel). Furthermore, divide 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)) / Grammage (g (paper towel) / m 2 (Paper towel)) = Calculate the water absorption per unit weight (g (water) / g (paper towel)). The measurement is performed 5 times for each sample, and the average value is adopted. Note that this measurement is performed in accordance with JIS P 8111 method under the conditions of temperature 23 ± 1°C and humidity 50 ± 2%. Also, distilled water is maintained at 23 ± 1°C.

[0053] 4. Manufacturing method of paper towel and roll-shaped paper towel As a manufacturing method of the paper towel 1x and the roll-shaped paper towel 1, when the paper towel 1x is a kitchen towel containing synthetic fibers and pulp fibers, for example, (1) laminating pulp fibers on a predetermined spunbond non-woven fabric and water entangling, (2) heat embossing treatment using matched steel, (3) perforation processing, and (4) roll winding processing can be carried out in this order. At this time, in the (1) water entangling of the manufacturing method, by water entangling pulp fibers with synthetic fibers, a non-woven fabric containing synthetic fibers and pulp fibers is obtained. Regarding the method of water entangling, for example, it is preferably carried out by the method described in Japanese Patent Laid-Open No. 2018-193634.

[0054] As described above, the present invention has been described using embodiments. Needless to say, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. Also, it is obvious from the description of the claims that forms with such changes or improvements can also be included in the technical scope of the present invention.

Examples

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

[0056] (1) Laminating pulp fibers onto a spunbond nonwoven fabric of polypropylene and subjecting them to hydroentanglement, (2) heat embossing treatment using matched steel, (3) perforation, and (4) roll winding processes, the roll-shaped paper towels of Examples 1 to 26 and Comparative Examples 1 to 9 described in Tables 2 to 4 were produced. Note that only Example 26 was made into a roll-shaped paper towel without a core. Regarding the roll-shaped paper towels of all examples and comparative examples, the above-described respective parameters were measured and the following respective evaluations were performed. All the measurement results and evaluations are shown in Tables 2 to 4.

[0057] Wrapping around the core of the pickup: Regarding the wrapping around the core of the pickup, the evaluation was performed as follows. The wrapping around the core is weak and it easily dissociates from the core during winding, or the paper towel gets wrinkled. : × The wrapping around the core is slightly weak and it is likely to dissociate from the core during winding, or the paper towel is likely to get wrinkled. : △ The wrapping around the core is good without problems, it is difficult to dissociate from the core during winding, and the paper towel is also difficult to get wrinkled. : ○ The wrapping around the core is good without problems, it hardly dissociates from the core during winding, and the paper towel does not get wrinkled either. : ◎

[0058] Difficulty of core crushing (during winding): Regarding the crushing of the core during the winding of the roll-shaped paper towel, the evaluation was performed as follows. The core is greatly crushed during winding. : × The core is slightly crushed during winding. : △ The core is hardly crushed during winding. : ○ The core is not crushed at all during winding. : ◎

[0059] Difficulty of core crushing (during log saw cut): Regarding the crushing of the core during the log saw cut of the roll-shaped paper towel, the evaluation was performed as follows. The core is greatly crushed during log saw cut. : × The core is slightly crushed during log saw cut. : △ The core is hardly crushed during log sawing: ○ The core is not crushed at all during log sawing: ◎

[0060] Ease of use of roll products: Regarding the ease of use of roll paper towels as products, the evaluation was conducted as follows. The roll diameter is too large or too small, making it difficult to use: × The roll diameter is slightly too large or slightly too small, making it slightly difficult to use: △ The roll diameter is slightly larger or slightly smaller, but there is no problem with ease of use: ○ The roll diameter is of appropriate size and easy to use: ◎

[0061] Logistics efficiency: Regarding the logistics efficiency of roll paper towels, the evaluation was conducted according to the criteria in Table 1.

Table 1

[0062] Water absorption: Regarding the water absorption of paper towels, based on the water absorption per unit area of the paper towels measured by the above measurement method, the evaluation was conducted as follows. The water absorption is 159 g / m 2 or less: ×× The water absorption is 160 g / m 2 or more and 209 g / m 2 or less: × The water absorption is 210 g / m 2 or more and 259 g / m 2 or less: △ The water absorption is 260 g / m 2 or more and 309 g / m 2 or less: ○ The water absorption is 310 g / m 2 or more: ◎

[0063]

Table 2

[0064]

Table 3

[0065]

Table 4

[0066] As shown in Tables 2 to 4, all of the roll-shaped paper towels of Examples 1 to 26 were strongly wound around the pickup core, were less likely to have the core crushed during winding or log saw cutting, were excellent in ease of use and logistics efficiency, and had good water absorbency. On the other hand, the roll-shaped paper towels of Comparative Examples 1 to 9 were either weakly wound around the pickup core, the core was likely to be crushed during winding or log saw cutting, were inferior in ease of use and logistics efficiency, or were inferior in water absorbency. From the above, the roll-shaped paper towel of the present invention is a roll-shaped paper towel having a core outer diameter within a certain range, being 1-ply, having a high basis weight, and being excellent in water absorbency, and is excellent in ease of winding of the roll and difficulty of core crushing, is easy to use as a product, and has good logistics efficiency.

Explanation of Signs

[0067] 1 Roll-shaped paper towel 1a Surface 1b Back surface 1e Edge of the outermost winding of the paper towel 1x Paper towel 200 Test piece 200a, 200d Corners 210 Strip 220 Holder

Claims

1. A single-ply paper towel containing pulp fibers and synthetic fibers, which is a roll-shaped paper towel wound up in a roll shape, The basis weight of the paper towel is 40 g / m ２ or more and 150 g / m ２ or less, and The winding diameter of the roll is 75 mm or more and 160 mm or less, and the roll density is 0.05 g / cm ３ or more and 0.19 g / cm ３ or less, and the core outer diameter of the roll is 25 mm or more and 55 mm or less, wherein the value represented by ((the area of the core outer diameter of the roll) / (the cross-sectional area of the roll excluding the cavity from the center of the roll to the core)) × 100 is 5 or more and 40 or less. The roll-shaped paper towel is characterized by this.

2. The cross-sectional area of the roll, excluding the cavity from the center of the roll to the core, is 30 cm ２ or more and 190 cm ２ or less, and the roll-shaped paper towel according to claim 1, characterized in that.

3. The roll-shaped paper towel according to Claim 1, wherein the bending stiffness in the MD direction of the paper towel is 10 μN·m or more and 130 μN·m or less.

4. The apparent basis weight of the core of the roll is 200 g / m ２ or more and 520 g / m ２ or less, and the roll-shaped paper towel according to claim 1, characterized in that.

5. The roll-shaped 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 is 2 N / 25 mm or more and 50 N / 25 mm or less.

6. The roll-shaped paper towel according to Claim 1, wherein the hardness of the core of the roll is 0.4 mm or more and 3.0 mm or less.

7. The roll-shaped paper towel according to Claim 1, wherein the value represented by (the bending stiffness in the MD direction of the paper towel) × (the hardness of the core of the roll) is 5 or more and 360 or less.

8. The water absorption per unit area of the paper towel is 210 g / m ２ or more and 520 g / m ２ or less, and the roll-shaped paper towel according to claim 1, characterized in that.

9. The roll-shaped paper towel according to Claim 1, wherein the winding length of the roll is 7 m or more and 24 m or less.

10. The roll-shaped paper towel according to Claim 1, wherein the paper thickness of the paper towel is 200 μm or more and 1400 μm or less.

11. The roll-shaped paper towel according to Claim 1, wherein the paper towel is a kitchen towel.

Images