Paper towel roll

Abstract

To provide a paper towel roll which is excellent in all of decorativeness, texture, and water absorbency while securing paper strength, and is also excellent in operability.SOLUTION: A paper towel roll obtained by winding a paper towel sheet in which a sheet to which an embossed pattern is imparted is laminated, the paper towel roll having an uneven pattern derived from a papermaking process, the paper towel roll having a root mean square height of 50 μm or more and 110 μm or less in a portion to which the embossed pattern is not imparted, a basis weight per ply of 15. 0g / m2 or more and 30. 0g / m2 or less, a DMDT of 1400cN / 76mm or more and 5900cN / 76mm or less, a DCDT of / 1300cN or more and / or less, a DMDT / DCDT of 0.78 or more and 2.70 or less, and a water absorption amount per unit area of / wetter or more and / wetter or less. 650g 76mm m2 m2 5800cN 250g 76mm, the paper towel roll has a water absorption per unit mass of 7g / g or more and 20g / g or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to paper towel rolls. [Background technology]

[0002] Various types of paper towel sheets and paper towel rolls made by rolling up sheets have been developed and are on sale.

[0003] In recent years, paper towels have become longer in length per roll, but in addition to longer sheets, high-quality products also require quality such as texture and tear resistance.

[0004] Among such luxury products, paper towel sheets obtained using the so-called TAD (Through Air Drying) papermaking technology (hereinafter also referred to as the "TAD papermaking method"), which uses air drying, are attracting attention because the sheets are thick, have a soft texture, and have excellent water absorbency.

[0005] As a prior art document relating to paper towel rolls, for example, Patent Document 1 describes a paper towel roll in which sheets with embossed patterns are glued together and laminated into two plies, and the resulting paper towel sheet is wound into a roll. The paper towel sheet has a concave-convex pattern derived from the papermaking process that is different from the embossed pattern, and the basis weight of the two plies is 30 g / m. 2 More than 54g / m 2 The following is a paper thickness of 1.3 mm / 10 sheets or more and 5 mm / 10 sheets or less, 2 ply, 1 m 2 The paper towel roll is characterized by having a water absorption per roll of 220 g to 600 g, a roll length of 14 m to 44 m, and a roll diameter of 110 mm to 189 mm. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-116768 Summary of the Invention [Problem to be solved by the invention]

[0007] However, paper towel sheets obtained using TAD papermaking technology have surface irregularities resulting from the papermaking process and are bulky, resulting in little inter-fiber bonding and low strength.

[0008] Furthermore, like other paper products, if the paper is manufactured so that the flow occurs in the direction of the pulp fibers (i.e., to create an aspect ratio), the strength in the CD direction of the sheet will be even lower, making the paper more prone to tearing and resulting in a lower quality product.

[0009] Furthermore, when poor drying occurs, small holes are generated in the width direction due to the weak strength in the CD direction, which makes the paper more susceptible to breakage and reduces runnability.

[0010] Possible measures to prevent this decrease in strength in the CD direction include: 1. increasing the sheet basis weight, 2. strengthening the pulp beating, 3. adding strength agents, and 4. bringing the aspect ratio of tensile strength (DMDT / DCDT) closer to 1.0.

[0011] However, if measures 1 to 3 above are taken more than necessary, 1 will increase costs, 2 will decrease the pulp FPR (first pass retention: fiber and chemical retention rate, also known as primary retention rate) of 2 and 3 will decrease the chemical FPR (first pass retention rate), increasing the chemical and fine fiber concentrations in the white water and making the system more susceptible to contamination. As a result, the system will need to be cleaned more frequently, which will ultimately result in a decline in production capacity and higher production costs. Therefore, in order to suppress the decrease in strength in the CD direction of the sheet without changing the cost, the most effective measure is to set the above 4 to an appropriate value.

[0012] However, if the aspect ratio of tensile strength approaches 1.0, the texture of the product (paper towel sheet) tends to deteriorate, making it difficult to maintain the aesthetic appeal of a high-quality product. One way to improve the texture is to reduce the addition rate of paper strength agents, but in that case the paper strength cannot be secured and it becomes more prone to tearing and paper breakage, which reduces runnability.

[0013] The present invention has been made in view of the above circumstances, and aims to provide a paper towel roll that has good decorative properties, texture, and water absorbency while maintaining paper strength, and also has excellent operability. [Means for solving the problem]

[0014] The inventors have conducted extensive research and have found that a paper towel roll can be produced by laminating two or three plies of paper towel sheets, at least one of which has an embossed pattern, and winding them into a roll, and by providing the paper towel sheet with a pattern of protrusions and recesses derived from the papermaking process that is different from the embossed pattern, and by controlling the root mean square height of the surface roughness in the non-embossed portion of the paper towel sheet, the basis weight per ply, the DMDT and DCDT of the two or three plies and their ratios, and the water absorption per unit area and per unit mass within predetermined ranges, thereby achieving a paper towel roll that has good decorative properties, texture, and water absorption while maintaining paper strength and also has excellent runnability, thereby solving the above-mentioned problems and leading to the completion of the present invention.

[0015] (1) A first aspect of the present invention is a paper towel roll obtained by winding up a paper towel sheet, which is formed by laminating two or three plies of sheets, at least one of which has an embossed pattern, into a roll, and the paper towel sheet has an uneven pattern derived from a papermaking process that is different from the embossed pattern, and the root mean square height of the surface roughness of the paper towel sheet in a portion where the embossed pattern is not provided is 50 μm or more and 110 μm or less, and the basis weight per ply of the paper towel sheet is 15.0 g / m 2 More than 30.0g / m 2and the tensile strength DMDT of the 2-ply or 3-ply paper towel sheet in the MD direction when dry is 1400 cN / 76 mm or more and 5900 cN / 76 mm or less, and the tensile strength DCDT of the 2-ply or 3-ply paper towel sheet in the CD direction when dry is 1300 cN / 76 mm or more and 5800 cN / 76 mm or less, and the ratio of the DMDT to the DCDT (DMDT / DCDT) is 0.78 or more and 2.70 or less, and the water absorption per unit area of ​​the 2-ply or 3-ply paper towel sheet is 250 g / m 2 More than 650g / m 2 Hereinafter, the paper towel roll is characterized by having a water absorption per unit mass of 7 g / g or more and 20 g / g or less.

[0016] (2) A second aspect of the present invention is the paper towel roll according to (1), wherein the specific volume of the paper towel sheet is 7 cm 3 / g or more 23cm 3 / g or less.

[0017] (3) A third aspect of the present invention is a paper towel roll according to (1) or (2), characterized in that the thickness of the paper towel sheet is 2.1 mm / 10 plies or more and 4.4 mm / 10 plies or less.

[0018] (4) A fourth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the winding density of the paper towel roll is 0.28 m / cm 2 More than 0.43m / cm 2 It is characterized by the following: [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a paper towel roll that has good decorative properties, texture, and water absorbency while ensuring paper strength, and also has excellent operability. [Brief explanation of the drawings]

[0020] [Figure 1]FIG. 1 is a perspective view of a paper towel roll according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of an embossed pattern imparted to the sheet in the paper towel roll of the present invention. [Figure 3] FIG. 10 is a diagram showing the height profile of a non-embossed portion on the XY plane as viewed under a microscope, using gray scales. [Figure 4] FIG. 1 is a diagram showing a method for measuring the water absorption of a paper towel sheet of the present invention. [Figure 5] 1 is a diagram showing a portion of the papermaking process for the paper towel sheet of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0022] The MD direction of a paper towel sheet is the machine direction in which the paper towel sheet is made, and the CD direction is the direction perpendicular to the MD direction (cross direction). The term "product ply" refers to the number of plies in a paper towel sheet. For example, if a paper towel roll is made by winding a paper towel sheet made of two sheets stacked on top of each other, the product ply will be two plies. In addition, paper towels (rolls, sheets) in this invention also include kitchen towels and various paper towels (for wipers).

[0023] <Paper towel roll> Fig. 1 is a perspective view of a paper towel roll 1 according to one embodiment of the present invention. As shown in Fig. 1, the paper towel roll 1 according to this embodiment is a paper towel roll 1 wound into a roll from a paper towel sheet 1x, which is made by laminating two or three plies of sheets, at least one of which has an embossed pattern 10. Preferably, the paper towel sheet 1x has perforations formed in the width direction of the roll at approximately equal intervals in the winding direction of the roll (not shown). 1, the surface of the paper towel sheet 1x facing the outside of the roll is referred to as surface 1a (surface of the paper towel sheet 1x), and the surface facing the center of the roll is referred to as back surface 1b (back surface of the paper towel sheet 1x). Also, the edge of the paper towel sheet 1x is referred to as the outermost edge 1e of the paper towel roll 1.

[0024] Uses of the paper towel roll 1 include, for example, rolls (kitchen paper rolls) of kitchen paper (sometimes called paper towels, cooking paper, etc.) used in home kitchens and restaurant kitchens to wipe away moisture or oil and remove dirt, as well as rolls of other sanitary paper.

[0025] (winding length and winding diameter) The lower limit of the winding length of the paper towel roll 1 is preferably 18 m or more, more preferably 22 m or more, and even more preferably 27 m or more, and the upper limit is preferably 45 m or less, more preferably 40 m or less, and even more preferably 31 m or less. If the winding length is less than 18 m, the water absorption per roll will be poor. If the winding length exceeds 45 m, the winding density will increase if the winding diameter DR remains the same, and the roll will be pulled tightly, which will make the roll more susceptible to breakage and ultimately reduce operability.

[0026] The roll length is measured as follows. First, measure the length of 10 sheets of paper towel sheets 1x between the perforations on paper towel roll 1. Then, measure the number of sheets on paper towel roll 1, and calculate the roll length proportionally from the length of 10 sheets and the number of sheets. For example, if the length of 10 sheets is 1.80 m and there are 150 sheets, the roll length is 1.80 m x (150 / 10) = 27 m. If paper towel roll 1 does not have perforations, measure the roll length.

[0027] The lower limit of the winding diameter DR of the paper towel roll 1 according to this embodiment is preferably 130 mm or more, more preferably 135 mm or more, and even more preferably 142 mm or more, and the upper limit is preferably 170 mm or less, more preferably 165 mm or less, and even more preferably 156 mm or less. If the reel diameter DR is less than 130 mm, and the reel length remains unchanged, the reel density increases, and the reel is pulled tightly, which increases the likelihood of paper breakage and ultimately reduces operability. If the reel diameter DR exceeds 170 mm, and the reel length remains unchanged, the reel becomes loose, making the paper towel sheet 1x more likely to tear under external pressure.

[0028] The roll diameter DR is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. Three paper towel rolls 1 are measured and the measurement results are averaged.

[0029] (sheet width and roll mass) The sheet width (roll width) of the paper towel roll 1 has a lower limit of preferably 200 mm or more, more preferably 220 mm or more, and even more preferably 260 mm or more, and an upper limit of preferably 340 mm or less, more preferably 320 mm or less, and even more preferably 300 mm or less. If the sheet width is less than 200mm, the sheet area is reduced, resulting in poor absorbency per sheet. If the sheet width is more than 340mm, the area subjected to external pressure per roll increases, making each paper towel sheet more likely to tear.

[0030] The lower limit of the roll mass of the paper towel roll 1 is preferably 250 g or more, more preferably 290 g or more, and even more preferably 320 g or more, and the upper limit is preferably 510 g or less, more preferably 465 g or less, and even more preferably 420 g or less. If the roll weight is less than 250g, and the roll length remains the same, the basis weight of the paper towel sheet 1x will be lower, making it more susceptible to breakage. In the case of a two-ply construction, the absorbency will be poor. If the roll weight exceeds 510g, and the roll length remains the same, the basis weight of the paper towel sheet 1x will be higher, increasing strength, but the texture will be poor.

[0031] The roll mass is the mass per 280mm of sheet width, excluding the paper tube 2 (core) of the paper towel roll 1. If the sheet width is not 280mm, convert it to the mass per 280mm by proportional calculation.

[0032] (roll density) The roll density of the paper towel roll 1 according to this embodiment has a lower limit of 0.04 g / cm 3 It is preferable that the concentration is 0.05 g / cm or more. 3 More preferably, it is 0.06 g / cm or more. 3 The upper limit is more preferably 0.12 g / cm. 3 Preferably, it is 0.11 g / cm or less. 3 More preferably, it is 0.10 g / cm or less. 3 It is more preferable that: Roll density is 0.04g / cm 3If the roll density is less than 0.12 g / cm, the basis weight of the paper towel sheet 1x will be lower and the paper will be more likely to break if the roll volume remains the same. Also, in the case of a two-ply paper towel, the absorbency will be poor. 3 If the roll volume does not change, the basis weight of the paper towel sheet 1x will increase and the strength will also increase, but the texture will be inferior.

[0033] Roll density is expressed as (roll mass) ÷ (roll volume). Roll mass is the mass of a paper towel roll 1 per 280 mm of roll width. Roll volume is expressed as [{cross-sectional area of ​​the roll's outer diameter (winding diameter DR)} - (cross-sectional area of ​​the paper core's outer diameter DI)] × roll width (converted per 280 mm). For example, if the roll mass (excluding the paper core) per 280 mm of roll width is 382 g, the winding diameter DR is 150 mm, and the paper core's outer diameter DI is 39 mm, then roll density = 382 g ÷ [{3.14 × (150 mm ÷ 2 ÷ 10) 2 -3.14×(39mm÷2÷10) 2}×(280mm÷10)]=0.08g / cm 3 This becomes:

[0034] (winding density) The winding density of the paper towel roll 1 according to this embodiment is 0.28 m / cm 2 More than 0.43m / cm 2 It is preferable that the winding density is 0.28 m / cm or less. 2 If the winding density is less than 0.43m / cm, the winding becomes loose and easily crushed when stacked, resulting in poor decorative properties. 2 If the thickness exceeds this, the paper tends to break due to the tension required to wind it tightly, which reduces workability. When cutting with a log saw, the core tends to be crushed, resulting in poor aesthetics. The winding density of the paper towel roll 1 has a lower limit of 0.30 m / cm 2 More preferably, it is 0.32 m / cm or more. 2 The upper limit is more preferably 0.41 m / cm. 2 More preferably, it is 0.39 m / cm or less. 2 It is more preferable that:

[0035] The winding density is expressed as (winding length x number of plies) ÷ (cross-sectional area of ​​the roll). The cross-sectional area of ​​the roll is expressed as {cross-sectional area of ​​the roll outer diameter (winding diameter DR) - (cross-sectional area of ​​the cardboard core outer diameter DI)}. For example, in the case of a winding length of 27 m, 2 plies, a winding diameter DR of 150 mm, and a cardboard core outer diameter DI of 39 mm, the winding density = (27 m x 2) ÷ {3.14 x (150 mm ÷ 2 ÷ 10) 2 -3.14×(39mm÷2÷10) 2}=0.33m / cm 2 This becomes:

[0036] (Paper tube outer diameter) The lower limit of the paper tube outer diameter DI, which is the outer diameter of the paper tube 2 that forms the core of the paper towel roll 1 of the present invention, is preferably 20 mm or more, more preferably 30 mm or more, and even more preferably 38 mm or more, and the upper limit is preferably 60 mm or less, more preferably 55 mm or less, and even more preferably 50 mm or less. If the paper tube outer diameter DI is less than 20 mm, and the reel diameter DR remains unchanged, the reel density will be lower, resulting in a loose reel that is prone to being crushed when stacked, and aesthetic appeal will be poor. If the paper tube outer diameter DI exceeds 60 mm, and the reel diameter DR remains unchanged, the reel density will be higher, and the paper will be pulled to make it tightly reeled, which will make it more likely to break, and as a result, operability will be reduced.

[0037] The outer diameter DI of the paper core is measured using a diameter rule manufactured by Muratec KDS Co., Ltd. Three paper towel rolls 1 are measured and the measurement results are averaged. If the core does not have a paper core 2, the outer diameter of the hollow core part is measured.

[0038] The lower limit of the mass of the cardboard tube 2 is preferably 10 g or more, more preferably 12 g or more, and even more preferably 14 g or more, and the upper limit is preferably 25 g or less, more preferably 20 g or less, and even more preferably 17 g or less. If the mass of the paper tube 2 is less than 10 g, the core is too soft and easily crushed when cut with a log saw, resulting in poor decorative properties. If the mass of the paper tube 2 is more than 25 g, the core becomes hard and requires more force when cut with a log saw, resulting in poor decorative properties.

[0039] The paper tube 2 is made of multiple layers of base paper, preferably two layers. The pulp fiber contained in the base paper is preferably bleached kraft pulp (BKP). The BKP content in the base paper is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. If the BKP content is less than 50% by mass, the decorative properties of the paper towel roll 1 will be poor. In this case, the BKP preferably contains bleached hardwood kraft pulp (LBKP). The LBKP content is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. If the LBKP content is less than 50% by mass, the core becomes hard and requires more force to cut with a log saw, making the core more likely to be crushed and resulting in poor aesthetic appeal.

[0040] <Paper towel sheet> The paper towel sheet 1x according to this embodiment preferably contains wet pulp. The wet pulp content is preferably 50% or more. If the wet pulp content is less than 50%, the water absorbency of the paper towel sheet 1x will be poor. There is no upper limit for the wet pulp content, but if it is too high, the strength of the paper towel sheet 1x will tend to increase, which may result in a poor texture. The wet pulp content in the paper towel sheet 1x is more preferably 70% or more, and even more preferably 90% or more.

[0041] Pulp includes softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP). The mass ratio of softwood bleached kraft pulp (NBKP) to hardwood bleached kraft pulp (LBKP) in the paper towel sheet 1x is preferably 40-100% by mass:0-60% by mass. If the mass ratio of NBKP is too low, the paper towel sheet 1x will be easily torn. If the mass ratio of LBKP is too high, the paper towel sheet 1x will be easily torn. The mass ratio of softwood bleached kraft pulp (NBKP) to hardwood bleached kraft pulp (LBKP) in the paper towel sheet 1x is preferably NBKP:LBKP=50-90% by mass:10-50% by mass, more preferably NBKP:LBKP=60-80% by mass:20-40% by mass.

[0042] As for the pulp treatment, beating is preferably performed for NBKP, and non-beating is preferably performed for LBKP. Furthermore, other pulps (e.g., recycled pulp) may be contained in an amount of preferably 20% by mass, more preferably 10% by mass, even more preferably 5% by mass, and most preferably 0% by mass, based on the ratio of NBKP to LBKP.

[0043] (Basic weight) The basis weight per ply of the paper towel sheet 1x according to this embodiment is 15.0 g / m 2 More than 30.0g / m 2 The basis weight per ply is 15.0 g / m 2 If the weight is less than 30.0 g / m, the paper tends to break during the papermaking process, and if the paper towel sheet 1x is two plies, the absorbency also deteriorates. 2 If the strength of the paper towel sheet exceeds this, the strength will increase, but the texture will deteriorate. The minimum basis weight per ply of a paper towel sheet is 17.0 g / m 2 It is preferable that the content is 19.0 g / m or more. 2 The upper limit is more preferably 28.0 g / m or more. 2 Preferably, it is 25.0 g / m or less. 2More preferably, it is:

[0044] (paper thickness) The paper thickness of the paper towel sheet 1x is preferably 2.1 mm / 10 ply or more and 4.4 mm / 10 ply or less. If the paper thickness is less than 2.1 mm / 10 ply, the water absorbency of the paper towel sheet 1x will be poor. If the paper thickness is more than 4.4 mm / 10 ply, the specific volume will increase if the basis weight remains the same, making the paper towel sheet 1x more prone to tearing. The thickness of the paper towel sheet 1x is preferably 2.4 mm / 10 plies or more, more preferably 2.6 mm / 10 plies or more, and more preferably 4.0 mm / 10 plies or less, more preferably 3.7 mm / 10 plies or less.

[0045] The thickness of a paper towel sheet 1x can be measured using a thickness gauge (a dial thickness gauge called "PEACOCK" manufactured by Ozaki Manufacturing 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 sample is 10 plies of paper towel sheet (5 sets for 2-ply, 3 sets for 3-ply, and the value is proportionally calculated to 10 plies). The measurement is repeated 10 times at different points, and the average of the measurement results is used as the final paper thickness.

[0046] (seat length) The sheet length between perforations (the length of the paper towel sheet 1x in the direction of winding the roll) has a lower limit of preferably 100 mm or more, more preferably 130 mm or more, and even more preferably 150 mm or more, and an upper limit of preferably 250 mm or less, more preferably 220 mm or less, and even more preferably 210 mm or less. If the sheet length is less than 100 mm, the sheet area is reduced, resulting in poor absorbency per paper towel sheet.If the sheet length exceeds 250 mm, the paper towel sheet is too long, making it less user-friendly as a product.

[0047] (specific volume) The specific volume of one paper towel sheet is 7cm 3 / g or more 23cm 3 / g or less. 3 If the specific volume is less than 23 cm3, the paper towel sheet 1x will have poor absorbency. 3 If the density exceeds 1 / g, the voids in the paper towel sheet 1x will become larger and the sheet will tear more easily. The specific volume of one paper towel sheet is limited to 9 cm 3 / g or more is more preferable, and 11cm 3 / g or more is more preferable. The upper limit is 22 cm 3 / g or less is more preferable, and 17cm 3 The specific volume is calculated by dividing the paper thickness per ply of 1x paper towel sheet by the basis weight per ply (the paper thickness per product ply is the basis weight per product ply) to obtain the volume (cm 3 ) per unit (g). 3 )

[0048] (DMDT and DCDT) The dry machine direction tensile strength (DMDT) of the paper towel sheet 1x when dry for two or three plies is 1400 cN / 76 mm or more and 5900 cN / 76 mm or less. If the DMDT is less than 1400 cN / 76 mm, the paper towel sheet 1x is prone to tearing and breakage during the papermaking process, resulting in reduced operability. If the DMDT exceeds 5900 cN / 76 mm, the texture of the paper towel sheet 1x deteriorates. The lower limit of the DMDT of the 2-ply or 3-ply paper towel sheet 1x is preferably 1900 cN / 76 mm or more, more preferably 2100 cN / 76 mm or more, and the upper limit is preferably 5200 cN / 76 mm or less, more preferably 4500 cN / 76 mm or less.

[0049] Furthermore, the dry cross direction tensile strength (DCDT) of the paper towel sheet 1x when dry for two or three plies is 1300 cN / 76 mm or more and 5800 cN / 76 mm or less. If the DCDT is less than 1300 cN / 76 mm, the paper towel sheet 1x is prone to tearing and is prone to breakage during the papermaking process, resulting in reduced operability. If the DCDT exceeds 5800 cN / 76 mm, the texture of the paper towel sheet 1x deteriorates. The DCDT of the 2-ply or 3-ply paper towel sheet 1x preferably has a lower limit of 1800 cN / 76 mm or more, more preferably 2000 cN / 76 mm or more, and an upper limit of 5100 cN / 76 mm or less, more preferably 4400 cN / 76 mm or less.

[0050] Furthermore, the ratio of DMDT to DCDT (DMDT / DCDT) is 0.78 or more and 2.70 or less. If the ratio is less than 0.78, the DCDT content is too high, resulting in increased strength but poor texture, while if the DMDT content is too low, the paper towel sheet 1x will tear easily. If the ratio is greater than 2.70, the DMDT content is too high, resulting in increased strength but poor texture, while if the DCDT content is too low, the paper towel sheet 1x will tear easily. The lower limit of the ratio of DMDT to DCDT (DMDT / DCDT) is preferably 0.82 or more, more preferably 0.86 or more, and the upper limit is preferably 2.10 or less, more preferably 1.85 or less.

[0051] The DMDT and DCDT of 2-ply or 3-ply paper towel sheets are measured in accordance with JIS P 8113. The ratio (DMDT / DCDT) is calculated from the measured DMDT and DCDT. If the paper towel sheet is 3-ply, the measurement is also performed in accordance with JIS P 8113, except that the conditions are changed to 3-ply.

[0052] (Embossed) The paper towel roll 1 (paper towel sheet 1x) of this embodiment is embossed and has an embossed pattern 10. Furthermore, the paper towel sheet 1x of the present invention is formed by embossing at least one ply and then laminating it to form two plies. When laminating two plies, it is preferable to apply glue using, for example, plybond glue. By laminating two plies in this manner, the adhesion between the plies is strong, and the paper towel sheet 1x is less likely to tear or peel off even when wet. Furthermore, water may be used instead of plybond glue, or a mixture of glue and water may be used. If the paper towel sheet 1x does not have the embossed pattern 10, the entire surface of the paper towel sheet 1x would be coated with plybond glue, resulting in a poor texture.

[0053] The ply on the front surface 1a side of the paper towel sheet 1x preferably has an embossed pattern 10. By providing the embossed pattern 10 on the front surface 1a side, glue can be applied to the embossed convex portions and the two plies can be laminated together. The sheet on the back surface 1b side may have (or have) an embossed pattern, but preferably does not have (or do not have). By not having an embossed pattern on the back surface 1b side, the paper towel sheet 1x (paper towel roll 1) can have an excellent texture.

[0054] FIG. 2 is a diagram showing an example of an embossed pattern 10 in the paper towel roll 1 of this embodiment. The embossed pattern 10 preferably includes radial embossments 11 and closed-ring structure embossments 12. If the radial embossments 11 are not included, the aesthetic appeal of the paper towel sheet 1x as a product will be poor. If the closed-ring structure embossments 12 are not included, the water absorbency of the paper towel sheet 1x will be poor. It is also preferable that the radial embossments 11 and the closed-ring structure embossments 12 are alternately arranged at equal intervals. By alternately arranging the radial embossments 11 and the closed-ring structure embossments 12 at equal intervals, the paper towel sheet 1x can have excellent water absorbency and be easy to use as a product.

[0055] Although there are no particular limitations on the overall shape of the radial embossments 11, it is preferable that the embossed pattern 10 has a plurality of linear embossments extending outward from the center or a plurality of embossments in the form of a straight line. By including the radial embossments 11 in the embossed pattern 10, the aesthetic appeal of the paper towel sheet 1x as a finished product is improved. Like the radial embossments 11, the overall shape of the closed-ring structure embossments 12 is not particularly limited, but it is preferable that the closed-ring structure embossments include a linear or geometric embossment provided in the center and a geometric embossment that surrounds the central embossment to form a closed ring. When the embossment pattern 10 includes the closed-ring structure embossments 12, water is retained inside the embossments, improving the water absorbency of the paper towel sheet 1x.

[0056] Furthermore, the embossed pattern 10 preferably includes linear embossed portions 100, and the proportion of linear embossed portions 100 included in the embossed pattern 10 is preferably 20% or more. If the proportion is less than 20%, the embossed pattern 10 will not contribute to improving the feel and water absorbency, and the paper towel sheet 1x will have poor feel and water absorbency. The proportion of the linear embossed portions 100 contained in the embossed pattern 10 is more preferably 50% or more, and even more preferably 90% or more.

[0057] In this case, the linear embossed portion 100 refers to an embossment having a thickness of 0.1 mm to 4 mm and a length of 5 mm or more. The proportion of the linear embossed portion 100 is determined as follows. First, any 100mm x 100mm area on the surface of the paper towel sheet 1x with the embossed pattern 10 is divided into 10mm squares. Then, the proportion of the linear embossed portion 100 is calculated using the following formula. Note that if a single square contains both linear embossing and dot embossing, the square with the larger embossing occupancy is used. (Number of squares containing linear embossing / Number of squares containing any embossing) x 100 = Percentage of linear embossing in 100 (%)

[0058] Furthermore, there are no particular restrictions on whether the back surface 1b of the paper towel sheet 1x has an embossed pattern 10, as long as it has a pattern of protrusions and recesses resulting from the papermaking process that is different from the embossed pattern 10 described below. Nested embossing or pin-to-pin embossing may be applied, or no embossing may be applied, but nested embossing or no embossing is preferred, and no embossing is more preferred.

[0059] The root mean square height Sq of the surface roughness of the paper towel sheet 1x in the portion not provided with an embossed pattern (hereinafter also referred to as the non-embossed portion) is 50 μm or more and 110 μm or less. If the root mean square height Sq of the surface roughness is less than 50 μm, the unevenness of the surface 1a becomes shallow and the pulp is not dispersed, resulting in poor texture of the paper towel sheet 1x, poor aesthetics, and poor water absorbency. If the root mean square height Sq of the surface roughness is more than 110 μm, the unevenness of the surface 1a becomes deep, making the paper towel sheet 1x more prone to tearing. The root mean square height Sq of the surface roughness of the non-embossed portion of the paper towel sheet 1x has a lower limit of preferably 58 μm or more, more preferably 65 μm or more, and an upper limit of preferably 103 μm or less, more preferably 95 μm or less.

[0060] The root mean square height Sq of the surface roughness of the non-embossed portion is measured using a microscope. A microscope manufactured by KEYENCE, product name "One-Shot 3D Shape Measuring Instrument VR-6100," can be used. Software for observing, measuring, and analyzing microscope images, product name "VR-6000 Analysis Application," can be used. Measurement conditions are a magnification of 38x and a field of view of 8mm x 6mm. The measurement magnification and field of view can be changed as appropriate depending on the desired size of the embossment.

[0061] FIG. 3 is a diagram showing the height profile of the non-embossed portion on the XY plane as viewed under a microscope, using gray scales. Filters are set for the image obtained, shown in Figure 3. Specifically, by setting an S-filter (low-pass filter), components with a scale smaller than the cutoff wavelength are removed from the image, and by setting an L-filter (high-pass filter), components with a scale larger than the cutoff wavelength are removed. Here, the S-filter is set to 500 μm, and the L-filter is set to 8 mm. By selecting the S-filter and L-filter, the root-mean-square height Sq is automatically calculated.

[0062] For the non-embossed portion, remove three wraps of paper towel sheet 1x from paper towel roll 1, and use the fourth wrap of paper towel sheet 1x to measure the sheet without changing the number of plies. Also, if there are perforations, avoid those when making the measurement. Measurements are taken at two locations in the roll width direction W of paper towel roll 1, and then rotate paper towel roll 1 three times in the roll winding direction, each time taking the same measurement as above (for a total of four measurement locations in the roll winding direction). The average value of the eight locations (2 x 4) is ultimately used as the root mean square height Sq. The measurement location is the area on the back surface 1b of the paper towel sheet 1x where the embossed pattern 10 is formed on the front surface 1a of the paper towel sheet 1x and where the ply is not adhered by the ply bond glue.

[0063] (Water absorption) The water absorption per unit area of ​​the 2-ply or 3-ply paper towel sheet 1x according to this embodiment is 250 g / m 2 More than 650g / m 2 The water absorption per unit area is 250g / m 2 If the thickness is less than 650g / m, the absorbency of the paper towel sheet 1x will be poor. 2 If the basis weight does not change, the specific volume increases instead, making the paper towel sheet 1x more likely to tear. The lower limit of the water absorption per unit area for 2-ply or 3-ply paper towel sheets is 300 g / m 2 It is preferable that the weight is 340 g / m or more. 2 The upper limit is more preferably 620 g / m or more. 2 Preferably, it is 600 g / m or less. 2 More preferably, it is:

[0064] Furthermore, the water absorption per unit mass of the 2-ply or 3-ply paper towel sheet 1x is 7 g / g or more and 20 g / g or less. If the water absorption per unit mass is less than 7 g / g, the water absorption of the paper towel sheet 1x will be poor. If the water absorption per unit mass is more than 20 g / g, and the basis weight remains unchanged, the specific volume will increase instead, making the paper towel sheet 1x more prone to tearing. The water absorption per unit mass of the two-ply or three-ply paper towel sheet 1x preferably has a lower limit of 8.0 g / g or more, more preferably 8.5 g / g or more, and an upper limit of 14 g / g or less, more preferably 13 g / g or less.

[0065] The method for measuring the amount of water absorption of each paper towel sheet 1x will be described below with reference to FIG. First, a two-ply paper towel sheet 1x is taken and cut using a square template with each side measuring 7.6 cm to prepare a rectangular test piece 20 with each side measuring 7.6 cm. The mass of the test piece 20 before water absorption is measured using an electronic balance. The test piece 20 is set in a holder 21 (a jig that fixes three points of the test piece 20, and the jig is made of a metal that does not absorb water).

[0066] Next, distilled water is poured into a commercially available tray to a depth of 2 cm, and the test piece 20 set in the holder 21 is immersed in the distilled water for 2 minutes. After immersion for 2 minutes, the test piece 20 is removed from the distilled water together with the holder 21, and the holder 21 and test piece 20 are hung from a rod placed in an empty water tank with the corner 20a facing up, and the lid of the water tank is closed and left for 5 minutes.

[0067] Thereafter, the holder 21 and the test piece 20 are taken out of the water tank, the holder 21 is removed, and the mass of the test piece 20 is measured with an electronic balance. From the change in mass of the test piece 20 before and after immersion in distilled water, the amount of distilled water absorbed per unit area of ​​the test piece 20 (g of water / sheet m 2 , 1m 2 Hit. Abbreviated as g / m 2 ) is calculated. Furthermore, the water absorption per unit area (g of water / sheet m 2 ) by the basis weight of the product ply of the test piece 20 to obtain the water absorption per unit area (water g / sheet m 2 ) / basis weight (sheet g / sheet m 2 ) = Water absorption per unit mass (g of water / g of sheet, per 1g. Abbreviated as g / g). Measurements are taken five times for each sample and the average value is used. If the product is a 3-ply product, measurements are taken as a 3-ply product using the same procedure as for a 2-ply product.

[0068] <Manufacturing method for paper towel rolls> The paper towel roll 1 can be manufactured, for example, in the following order: (1) papermaking and creping, (2) embossing and bonding, and (3) roll winding. Note that the TAD papermaking method is preferably used in the manufacturing (papermaking) process of the paper towel sheet 1x.

[0069] At this time, in the papermaking process, it is preferable that a concave-convex pattern 13 derived from the papermaking process (fabric), which is different from the above-mentioned embossed pattern 10, is formed on the paper towel sheet 1x, as shown in Figure 2. Without this concave-convex pattern 13, the paper towel sheet 1x will have poor water absorbency.

[0070] Note that "originating from the papermaking process" means that, in the papermaking process for paper towel sheet 1x, an uneven pattern is imparted between head box 41 of the papermaking machine and the outlet of Yankee dryer 46. Specifically, in a part of the papermaking process shown in Figure 5, paper web 40a in a pulp slurry state is sprayed (supplied) from head box 41 to between first fabric (forming fabric) 42 and second fabric (uneven fabric) 43, and is pulled onto second fabric (uneven fabric) 43 by forming roll 44, forming paper web 40b in a wet paper state. Next, the paper web 40b is dried together with the second fabric (concave-convex fabric) 43 in a through-air dryer 45, resulting in the formation of concave-convex patterns on the paper web 40c, which is in a dried sheet state. Although two through-air dryers 45 are shown in FIG. 5, a single unit may be used. Although a Yankee hood is shown on the Yankee dryer 46, the hood may be omitted. Furthermore, creping may be performed in the Yankee dryer 46.

[0071] The uneven pattern 13 can be changed as needed by changing the fabric pattern (fine pattern, coarse pattern). Changing the uneven pattern 13 changes the specific volume (paper thickness), but it is preferable to select a pattern that will bring the specific volume in the rolled state within the above-mentioned numerical range.

[0072] As described above, according to this embodiment, it is possible to provide a paper towel roll that has good aesthetics, texture, and water absorbency while ensuring paper strength, and also has excellent operability.

[0073] 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]

[0074] 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.

[0075] The paper towel rolls of Examples 1 to 20 and Comparative Examples 1 to 6 shown in Tables 3 and 4 were manufactured through the steps of (1) TAD papermaking and creping, (2) embossing and lamination, and (3) roll winding. The paper towel rolls of all Examples and Comparative Examples were measured for the above-mentioned parameters and evaluated as follows. For each of the following evaluations, 1 point was considered a failure and 2 points or more was considered a pass. Furthermore, each parameter other than the following evaluations was measured according to the standards or measurement methods described above.

[0076] 1. Paper towel sheets are tear-resistant The tear resistance of the manufactured paper towel sheets was evaluated by the DMDT and DCDT of two or three plies of the paper towel sheet, and the DMDT and DCDT values ​​were used to evaluate the tear resistance on a four-point scale. The evaluation criteria are shown in Table 1 below. [Table 1]

[0077] 2. The texture of paper towel sheets The texture of the paper towel sheets after production was evaluated by 30 monitors, who evaluated the texture on a 4-point scale based on the number of people who felt that the sheets were "stiff and had poor texture." The evaluation criteria were as follows: 4: 0-1 people felt that the seat was stiff and had poor texture 3: 2-4 people felt that the seat was stiff and had poor texture. 2: 5-7 people felt that the seat was stiff and had poor texture. 1: Eight or more people felt that the seat was stiff and had poor texture.

[0078] 3. Cosmetic properties of paper towel sheets The cosmetic appearance of the paper towel sheets after production was visually inspected by 30 monitors, who evaluated the sheet on a four-point scale based on the number of people who felt that the sheet texture and core shape were poor and the cosmetic appearance was poor. The evaluation criteria were as follows: 4: 0-1 people felt that the sheet texture and core shape were poor and the aesthetic appeal was poor. 3: 2-4 people felt that the sheet texture and core shape were poor and the aesthetic appeal was poor. 2: 5-7 people felt that the sheet texture and core shape were poor and the aesthetic appeal was poor. 1: Eight or more people felt that the sheet texture and core shape were poor and the aesthetic appeal was poor.

[0079] 4. Absorbency of paper towel sheets The absorbency of the paper towel sheet after production was evaluated by the amount of absorbed water per unit area and per unit mass for two or three plies of the paper towel sheet, and was evaluated on a four-point scale based on the values ​​of the amount of absorbed water per unit area and per unit mass. The evaluation criteria are shown in Table 2 below. [Table 2]

[0080] 5. Less likely to break during the papermaking process When manufacturing paper towel rolls using the TAD papermaking process, the reduction in paper breaks was evaluated compared to when the same paper towel sheets were manufactured using the conventional TAD papermaking process, and the results were rated on a four-point scale based on the "reduction rate in the number of paper breaks per hour." The evaluation criteria were as follows: 4: "Reduction rate of number of paper breaks per hour" is 10% or more 3: "Reduction rate of number of paper breaks per hour" is 5% or more but less than 10% 2: "Reduction rate of number of paper breaks per hour" is 0% or more but less than 5% 1: The "reduction rate of paper breaks per hour" is less than 0% (including cases where it has increased)

[0081] [Table 3]

[0082] [Table 4]

[0083] As is clear from the results shown in Tables 3 and 4, the paper towel rolls and paper towel sheets of Examples 1 to 20 were good in tear resistance, texture, decorative properties, water absorbency, and resistance to paper breakage during the papermaking process. In contrast, the paper towel rolls and paper towel sheets of Comparative Examples 1 to 6 were all poor in any of tear resistance, texture, decorative properties, water absorbency, and resistance to paper breakage during the papermaking process. Therefore, it was confirmed that the paper towel roll of the present invention can provide a paper towel roll that has good aesthetics, texture, and water absorbency while maintaining paper strength, and also has excellent operability. [Explanation of symbols]

[0084] 1 paper towel roll 1a surface 1b back side 1e The outermost edge of a paper towel roll 1x Paper Towel Sheet 2 Paper tube 10 Embossing Pattern 11 Radial Embossing 12 Closed ring structure embossing 13 Concave and Convex Pattern 20 test specimens 20a Corner 21 Holder 40a, 40b, 40c Paper web 41 Headbox 42,43 Fabric 44 Forming roll 45 Through Air Dryer 46 Yankee Dryer 100 Linear embossed part

Claims

1. A paper towel roll is formed by winding up a paper towel sheet in a roll, the paper towel sheet being formed by laminating two or three plies of a sheet having an embossed pattern on at least one ply, The paper towel sheet has a concave-convex pattern derived from a papermaking process that is different from the embossed pattern, the root mean square height of the surface roughness of the paper towel sheet in the portion where the embossed pattern is not provided is 50 μm or more and 110 μm or less; The paper towel sheet has a basis weight per ply of 15.0 g / m ２ 30.0g / m or more ２ is as follows: The paper towel sheet has a tensile strength DMDT in the MD direction when dry for 2 or 3 plies of 1400 cN / 76 mm or more and 5900 cN / 76 mm or less, a tensile strength DCDT in the CD direction when dry for 2 or 3 plies of 1300 cN / 76 mm or more and 5800 cN / 76 mm or less, and a ratio of DMDT to DCDT (DMDT / DCDT) of 0.78 or more and 2.70 or less, The water absorption per unit area of ​​the two-ply or three-ply paper towel sheet is 250 g / m ２ 650g / m or more ２ Hereinafter, a paper towel roll characterized in that the water absorption per unit mass is 7 g / g or more and 20 g / g or less.

2. The specific volume of the paper towel sheet is 7 cm ３ / g or more 23cm ３ 10. The paper towel roll of claim 1, wherein the surface roughness is 0.1 / g or less.

3. 3. The paper towel roll according to claim 1, wherein the paper towel sheet has a thickness of 2.1 mm / 10 plies or more and 4.4 mm / 10 plies or less.

4. The winding density of the paper towel roll is 0.28 m / cm ２ 0.43m / cm or more ２ 3. The paper towel roll of claim 1 or 2, characterized in that:

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