Paper towel roll

Abstract

To provide a paper towel roll that maintains the strength of the paper towel sheet, offers good wiping comfort and absorbency, and requires less frequent roll replacement. [Solution] A paper towel roll made by winding a paper towel sheet, which consists of two or more layers of sheets, into a roll shape, with a roll length of 155m to 350m, and a basis weight of 11.5g / m² per ply of the paper towel sheet. 2 More than 28.0g / m 2 The following is a water absorption rate per unit area of ​​70 g / m². 2 More than 180g / m 2 The following paper towel rolls are provided, wherein the GMT, which is the square root of the product of DMDT and DCDT, is between 4.5 N / 25 mm and 16.6 N / 25 mm, and the measured stiffness (D), as measured by a tissue softness measuring device TSA, is between 0.5 mm / N and 3.5 mm / N.

Description

Technical Field

[0001] The present invention relates to a paper towel roll.

Background Art

[0002] Paper towel sheets and paper towel rolls formed by winding the sheets into a roll are variously developed and sold.

[0003] In such a mode of a paper towel roll, there is a technique for manufacturing a paper towel roll for cutting and using a sheet electrically or manually by a dispenser provided with a cutter blade.

[0004] As a prior art document regarding a dispenser of a paper towel roll, for example, Patent Document 1 discloses a hand towel dispenser for a flat belt material having a transfer mechanism for forming a loop of a clean belt material suitable for simplified insertion and hand drying, the transfer mechanism having a pivoting module rotatable outwardly about a fixed axis, the transfer mechanism being supported within a side panel, the dispenser being closed with a housing cover and / or the transfer mechanism being started by a manually operable drive element, partially winding the belt material onto an exchangeable roller that conveys the used belt material from the supplied clean material through the supplied loop, the pivoting module (2) in the operating state having bearing points (38) for inserting a removable take-up roller (5) in two mutually facing lateral flanges in the upper region, and a recess (10) being provided for forming an additional loop of the belt material (T’) between the take-up roller (5) and the guides (8, 9, 4) of the belt material (T, T’).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Since the paper towel rolls used in the specialized dispensers described above are used in places different from ordinary homes, such as factories, shops, and hotels, it is desirable to have longer rolls to reduce the frequency of roll replacement.

[0007] In order to prevent tearing when the sheets are pulled out, the paper towel base needs to be stronger than conventional paper towels. However, as a result, the paper towel sheets tend to become harder, and the wiping experience deteriorates.

[0008] Therefore, there is a need for a paper towel roll that maintains strength while providing a good wiping feel and excellent water absorption, achieved by adjusting the paper quality of the base paper.

[0009] This invention has been made in view of these circumstances, and aims to provide a paper towel roll that maintains the strength of the paper towel sheet, has good wiping feel and water absorption, and also requires less frequent roll replacement. [Means for solving the problem]

[0010] The inventors conducted thorough research and found that, in a paper towel roll made by laminating two or more sheets of paper towel material into a roll, the roll length, the basis weight per ply of the paper towel sheet, the water absorption per unit area, and the square root of the product of the tensile strength in the MD direction (DMDT) and the tensile strength in the CD direction (DCDT) when dry, are all within predetermined numerical ranges. Furthermore, by setting the measured value of the stiffness (D) of the paper towel sheet, measured by a tissue softness measuring device (TSA), within predetermined numerical ranges, it is possible to create a paper towel roll that maintains the strength of the paper towel sheet while providing good wiping comfort and water absorption, and also reduces the frequency of roll replacement. This discovery solved the above problems and led to the completion of the present invention. In other words, the present invention provides the following.

[0011] (1) A first aspect of the present invention is a paper towel roll in which a paper towel sheet, of which two or more sheets are laminated, is wound into a roll, the length of the roll being 155m or more and 350m or less, and the basis weight per ply of the paper towel sheet being 11.5g / m² 2 More than 28.0g / m 2 The following is a water absorption rate per unit area of ​​70 g / m². 2 More than 180g / m 2 The following describes a paper towel roll characterized in that the GMT, which is the square root of the product of the tensile strength DMDT in the MD direction and the tensile strength DCDT in the CD direction when dry, is between 4.5 N / 25 mm and 16.6 N / 25 mm, and the measured stiffness (D), which is expressed as the amount of vertical deformation displacement of the sample between the pressing pressures of 100 mN and 600 mN, when the paper towel sheet sample is placed on a sample stage and pressed down from above with pressing pressures of 100 mN and 600 mN respectively using a tissue softness measuring device TSA, is between 0.5 mm / N and 3.5 mm / N.

[0012] (2) A second aspect of the present invention is a paper towel roll as described in (1), wherein the TSA applies a bladed rotor to a sample of the paper towel sheet placed on a sample stage with a pressing pressure of 100 mN, and then rotates it at a rotation speed of 2.0 ( / sec), and when the vibration of the sample stage is measured with a vibration sensor, the intensity of the first spectral maximum peak from the low-frequency side, automatically acquired by the software on the TSA (TS750), is 16 dBV. 2 RMS or higher, 41 dBV 2 It is characterized by being less than or equal to rms.

[0013] (3) A third aspect of the present invention is a paper towel roll as described in (1), characterized in that the paper thickness per ply in the paper towel sheet is 40 μm or more and 140 μm or less.

[0014] (4) A fourth aspect of the present invention is a paper towel roll as described in (1), characterized in that the tensile strength DMDT of the paper towel sheet in the MD direction when dry is 11.0 N / 25 mm or more and 30.5 N / 25 mm or less.

[0015] (5) A fifth aspect of the present invention is a paper towel roll as described in (1), characterized in that the tensile strength DCDT of the paper towel sheet in the CD direction when dry is 2.0 N / 25 mm or more and 9.0 N / 25 mm or less.

[0016] (6) A sixth aspect of the present invention is a paper towel roll according to any one of (1) to (5), characterized in that the water absorption per unit mass of the paper towel sheet is 1.5 g / g or more and 7.0 g / g or less.

[0017] (7) A seventh aspect of the present invention is a paper towel roll according to any one of (1) to (5), wherein the specific volume of the paper towel sheet is 1 cm³ 3 / g or more 8cm 3It is characterized by being less than or equal to / g.

[0018] (8) An eighth aspect of the present invention is a paper towel roll according to any one of (1) to (5), characterized in that the winding diameter of the roll is 100 mm or more and 300 mm or less. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a paper towel roll that maintains the strength of the paper towel sheet, has good wiping feel and water absorption, and requires less frequent roll replacement. [Brief explanation of the drawing]

[0020] [Figure 1] This is a perspective view of a paper towel roll according to one embodiment of the present invention. [Figure 2] This figure shows an example of an embossed pattern applied to a sheet in the paper towel roll of the present invention. [Figure 3] This figure shows a method for measuring the water absorption capacity of a paper towel sheet according to the present invention. [Figure 4] This figure shows a part of the papermaking process for the paper towel sheet of the present invention. [Modes for carrying out the invention]

[0021] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0022] In the context of paper towel sheets, the MD direction refers to the flow direction (Machine Direction) when the paper towel sheet is manufactured, while the CD direction refers to the direction perpendicular to the MD direction (Cross Direction). Furthermore, "product ply" refers to the number of plies in a paper towel sheet. For example, if a paper towel roll is manufactured by winding two sheets of paper towel material together, the product ply count will be 2 plies. In addition, the paper towels (rolls, sheets) in this invention include kitchen towels and various types of paper towels (for wiper use). Unless otherwise specified, the measurement conditions for each parameter are carried out in a room with a temperature of 23°C and a humidity of 50%RH.

[0023] <Paper towel roll> Figure 1 is a perspective view of a paper towel roll 1 according to one embodiment of the present invention. As shown in Figure 1, the paper towel roll 1 according to this embodiment is a paper towel roll 1 in which a paper towel sheet 1x, which is made by laminating two or more sheets, is wound into a roll shape. It is preferable that the paper towel sheet 1x does not have perforations in the roll width direction (not shown). As shown in Figure 1, the surface of the paper towel sheet 1x facing outwards from the roll is referred to as surface 1a (the surface of the paper towel sheet 1x), and the surface facing towards the center of the roll is referred to as back surface 1b (the back surface of the paper towel sheet 1x). 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 paper towel roll 1 include, for example, rolls of kitchen paper (sometimes called paper towels, cooking paper, etc.) used in home kitchens and restaurant kitchens for wiping up moisture or oil and removing dirt, hand towels, wipers, and other rolls of sanitary paper.

[0025] (Roll length and roll diameter) The length of a paper towel roll 1 is between 155m and 350m. If the length is less than 155m, the basis weight of the paper towel sheets 1x will be increased in order to keep the roll diameter DR (described later) within a certain range, resulting in a less comfortable wiping experience. The roll will also need to be replaced more frequently. If the length exceeds 350m, the basis weight of the paper towel sheets 1x will be decreased in order to keep the roll diameter DR (described later) within a certain range, resulting in a less absorbent feel. Furthermore, the length of the paper towel roll 1 is preferably 160m or more at the lower limit, and more preferably 165m or more. The upper limit is preferably 300m or less, and more preferably 280m or less.

[0026] The roll length is measured as follows: First, measure the length of 10 sheets of paper towels (1x) between the perforations of paper towel roll 1. Then, measure the number of sheets in 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 2.5m and the number of sheets is 900, then 2.5m × (900 / 10) = 225m. If paper towel roll 1 does not have perforations, measure the roll length directly.

[0027] In this embodiment, the winding diameter DR of the paper towel roll 1 is preferably 100 mm or more and 300 mm or less. If the winding diameter DR is less than 100 mm, the paper towel sheets 1x become difficult to pull out from the dispenser, resulting in them being more prone to tearing. Also, the frequency of replacing the paper towel roll 1 increases. If the winding diameter DR exceeds 300 mm, the paper towel sheets 1x become difficult to cut with the dispenser, resulting in them being more prone to tearing. Furthermore, the lower limit of the roll diameter DR of the paper towel roll 1 is more preferably 115 mm or more, and even more preferably 130 mm or more. The upper limit is more preferably 250 mm or less, and even more preferably 200 mm or less.

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

[0029] (Roll width and roll mass) The roll width (sheet width) of the paper towel roll 1 preferably has a lower limit of 130 mm or more, more preferably 150 mm or more, and even more preferably 170 mm or more. Also, the upper limit is preferably 400 mm or less, more preferably 350 mm or less, and even more preferably 300 mm or less. When the roll width is less than 130 mm, the water absorption per sheet of the paper towel sheet 1x decreases, resulting in inferior water absorption. When the sheet width exceeds 400 mm, it becomes difficult to cut the paper towel sheet 1x with a dispenser, and as a result, it is more likely to break.

[0030] Also, the roll mass of the paper towel roll 1 preferably has a lower limit of 1000 g or more, more preferably 1100 g or more, and even more preferably 1200 g or more. Also, the upper limit is preferably 3000 g or less, more preferably 2500 g or less, and even more preferably 2000 g or less. When the roll mass is less than 1000 g, the basis weight of the paper towel sheet 1x decreases, resulting in inferior water absorption. When the roll mass exceeds 3000 g, the basis weight of the paper towel sheet 1x increases, resulting in inferior wiping comfort.

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

[0032] (Roll density) The roll density of the paper towel roll 1 according to the present embodiment preferably has a lower limit of 0.10 g / cm 3 or more, and 0.20 g / cm 3It is more preferable that the value be greater than or equal to 0.30 g / cm³. 3 It is even more preferable that the values ​​be greater than or equal to the above. Furthermore, the upper limit is 1.10 g / cm³. 3 Preferably, it is 0.90 g / cm³. 3 It is more preferable that the following is the case: 0.60 g / cm³ 3 The following is even more preferable: Roll density is 0.10 g / cm³ 3 If the density is less than 1.10 g / cm², the paper towel roll becomes too soft, making it difficult to cut the paper towel sheets with the dispenser, and consequently, they tear easily. 3 If the limit is exceeded, the paper towel roll 1 becomes tightly wound, making it difficult to pull out the paper towel sheets 1x from the dispenser, and as a result, they become more prone to tearing.

[0033] Roll density is expressed as (roll mass) ÷ (roll volume). Roll mass is the mass of one paper towel roll per 280 mm roll width. Roll volume is expressed as [{cross-sectional area of ​​the outer diameter (winding diameter DR) portion of the roll} - (cross-sectional area of ​​the outer diameter DI portion of the paper core)] × roll width (converted to per 280 mm). For example, if the roll mass (excluding the paper core) per 200 mm roll width is 1500 g, the winding diameter DR is 150 mm, and the outer diameter DI of the paper core is 42 mm, then roll density = 1500 g ÷ [{3.14 × (150 mm ÷ 2 ÷ 10) 2 -3.14 × (42mm ÷ 2 ÷ 10) 2} × (200 mm ÷ 10) = 0.46 g / cm 3 This is the result.

[0034] (winding density) The winding density of the paper towel roll 1 according to this embodiment has a lower limit of 1.0 m / cm². 2 Preferably, it should be 1.5 m / cm 2 It is more preferable that the value be greater than or equal to 2.0 m / cm 2 It is even more preferable that the above is true. Furthermore, the upper limit is 4.0 m / cm. 2 Preferably, it is 3.5 m / cm 2 It is more preferable that the following conditions are met: 3.0 m / cm2 The following is even more preferable: Winding density is 1.0 m / cm 2 If the winding density is less than 4.0 m / cm², the paper towel roll becomes too soft, making it difficult to cut the paper towel sheets with the dispenser, and consequently, they tear easily. 2 If the limit is exceeded, the paper towel roll 1 becomes tightly wound, making it difficult to pull out the paper towel sheets 1x from the dispenser, and as a result, they become more prone to tearing.

[0035] The winding density is expressed as (winding length × number of plies) ÷ (cross-sectional area of ​​the roll). The cross-sectional area of ​​the roll is expressed as {cross-sectional area of ​​the outer diameter (winding diameter DR) portion of the roll - (cross-sectional area of ​​the outer diameter DI portion of the paper core)}. For example, for a winding length of 200m, 2 plies, winding diameter DR 150mm, and paper core outer diameter DI 42mm, the winding density = (200m × 2) ÷ {3.14 × (150mm ÷ 2 ÷ 10)} 2 -3.14 × (42mm ÷ 2 ÷ 10) 2} = 2.5 m / cm 2 This is the result.

[0036] (Paper tube outer diameter) Furthermore, the outer diameter DI of the paper tube 2, which is the core of the paper towel roll 1 of the present invention, is preferably 25 mm or more at the lower limit, more preferably 35 mm or more, and even more preferably 38 mm or more. The upper limit is preferably 50 mm or less, more preferably 48 mm or less, and even more preferably 46 mm or less. If the paper core outer diameter DI is less than 25 mm, the basis weight of the paper towel sheets 1x will be higher in order to keep the winding diameter DR within a certain range, resulting in a less comfortable wiping feel. If the paper core outer diameter DI exceeds 50 mm, the basis weight of the paper towel sheets 1x will be lower in order to keep the winding diameter DR within a certain range, resulting in a less absorbent feel. In addition, the frequency of replacing the paper towel roll 1 will increase.

[0037] The outer diameter DI of the paper core is measured using a Diameter rule manufactured by Muratec KDS Co., Ltd. Measurement is performed by measuring three paper towel rolls 1 and averaging the results. If there is no paper core 2 in the core, the diameter of the cavity in the core portion is measured and used as the outer diameter DI of the paper core.

[0038] <Paper towel sheets> (Basic weight) The basis weight per ply of the paper towel sheet 1x according to this embodiment is 11.5 g / m². 2 More than 28.0g / m 2 The following is the basis weight per ply: 11.5 g / m² 2 If the basis weight is less than 28.0 g / m², the paper towel sheets will have poor absorbency, be difficult to pull out of the dispenser, and consequently tear easily. 2 Beyond a certain point, the paper towel sheets become less effective at wiping, harder to cut with the dispenser, and consequently more prone to tearing. Additionally, the frequency of replacing the paper towel roll increases. The basis weight per ply of a 1x paper towel sheet has a minimum value of 13.5 g / m². 2 Preferably, it should be 15.5 g / m² or more. 2 It is more preferable that the values ​​be greater than or equal to the above. Furthermore, the upper limit is 26.0 g / m². 2 Preferably, it is 24.0 g / m². 2 The following is more preferable: The basis weight per ply of a 1x paper towel sheet can be measured according to JIS P 8124.

[0039] (paper thickness) The paper thickness per ply of the paper towel sheet 1x is preferably between 40 μm and 140 μm. If the paper thickness per ply is less than 40 μm, the paper towel sheet 1x will have poor water absorption. If the paper thickness per ply exceeds 140 μm, the paper towel sheet 1x will have poor wiping feel, become difficult to cut with a dispenser, and consequently tear easily. In addition, the frequency of replacing the paper towel roll 1 will increase. Furthermore, the paper thickness per ply of the 1x paper towel sheet is more preferably 45 μm or more at the lower limit, and even more preferably 50 μm or more. The upper limit is more preferably 110 μm or less, and even more preferably 90 μm or less.

[0040] The paper thickness of a 1x paper towel sheet can be measured using a thickness gauge (the "PEACOCK" dial thickness gauge manufactured by Ozaki Seisakusho Co., Ltd.). The measurement conditions are a measuring load of 3.7 kPa and a probe diameter of 30 mm. The sample is placed between the probe and the measuring stand, and the gauge is read when the probe is lowered at a speed of 1 mm or less per second. As a sample, a 1x paper towel sheet will be measured in its original product ply count. The measurement will be repeated 10 times at different locations, and the average of the measurement results will be divided by the number of product plies to obtain the final paper thickness per ply.

[0041] (specific volume) The specific volume of 1x paper towel sheet is 1cm³ 3 / g or more 8cm 3 It is preferable that the specific volume is less than or equal to 1 cm³. 3 If the amount is less than 1g, the absorbency of a 1x paper towel sheet will be poor. Also, if the specific volume is 8cm³, 3 If the amount exceeds [amount] / g, a single sheet of paper towels will tear easily during use. Note that the specific volume of a 1x paper towel sheet has a lower limit of 2 cm³. 3 It is more preferable that it be 3cm or more / g. 3 It is even more preferable that the value be 7 cm or more. Also, the upper limit is 7 cm. 3 It is more preferable that it be less than / g, and 6cm 3 It is even more preferable that it be less than or equal to / g. The specific volume of a paper towel sheet 1x is calculated by dividing the paper thickness per ply by the basis weight per ply in a paper towel sheet 1x in the product ply, and the volume per unit (g) (cm³). 3 It is represented as ).

[0042] (DMDT, DCDT, and GMT) The Dry Machine Direction Tensile Strength (DMDT) of a paper towel sheet 1x in the dry state is preferably between 11.0 N / 25 mm and 30.5 N / 25 mm. If the DMDT is less than 11.0 N / 25 mm, the paper towel sheet 1x becomes prone to tearing during use and difficult to pull out of the dispenser, resulting in it being prone to tearing even before use. Conversely, if the DMDT exceeds 30.5 N / 25 mm, the paper towel sheet 1x has a poor feel when wiping hands, becomes difficult to cut in the dispenser, and is prone to tearing. Furthermore, the DMDT of a 1x paper towel sheet is more preferably 12.0 N / 25 mm or higher at the lower limit, and even more preferably 13.0 N / 25 mm or higher. The upper limit is more preferably 29.5 N / 25 mm or lower, and even more preferably 28.5 N / 25 mm or lower.

[0043] Furthermore, the Dry Cross Direction Tensile Strength (DCDT) of the paper towel sheet 1x in the CD direction when dry is preferably 2.0 N / 25 mm or more and 9.0 N / 25 mm or less. If the DCDT is less than 2.0 N / 25 mm, the paper towel sheet 1x will tear easily during use. If the DCDT exceeds 9.0 N / 25 mm, the paper towel sheet 1x will have an inferior feel when wiping hands. Furthermore, the DCDT of a 1x paper towel sheet is more preferably 2.5 N / 25 mm or higher at the lower limit, and even more preferably 3.0 N / 25 mm or higher. The upper limit is more preferably 8.5 N / 25 mm or lower, and even more preferably 8.0 N / 25 mm or lower.

[0044] Furthermore, the Geometric Mean Tensile Strength (GMT) of a 1x paper towel sheet, which is the square root of the product of DMDT and DCDT, is between 4.5N / 25mm and 16.6N / 25mm. If the GMT is less than 4.5N / 25mm, the 1x paper towel sheet is prone to tearing during use. If the GMT exceeds 16.6N / 25mm, the 1x paper towel sheet becomes less comfortable to wipe hands with, difficult to cut with a dispenser, and consequently more prone to tearing. Furthermore, the GMT, which is the square root of the product of DMDT and DCDT for a paper towel sheet 1x, preferably has a lower limit of 5.0 N / 25 mm or more, and more preferably 6.0 N / 25 mm or more. The upper limit is preferably 15.6 N / 25 mm or less, and more preferably 15.1 N / 25 mm or less.

[0045] The DMDT and DCDT of a 1x paper towel sheet are measured in accordance with JIS P 8113. The test is performed with a test specimen width of 25 mm and a tensile speed of 300 mm / min, and measurements are taken with the product ply intact. The GMT, which is the square root of the product of the measured DMDT and DCDT, is also calculated.

[0046] (Embossed) In the paper towel sheet 1x according to this embodiment, when laminating into 2-ply or 3-ply layers, it is preferable to perform ply-up by, for example, knurling (also referred to as edge embossing or contact embossing).

[0047] Furthermore, the surface 1a side of the paper towel sheet 1x may have an embossed pattern 10. By applying the embossed pattern 10 to the surface 1a side, glue can be applied to the embossed protrusions and laminated into two plies. The back side 1b side of the sheet may have an embossed pattern, but it is preferable that it does not have one. By not having an embossed pattern on the back side 1b side, a paper towel sheet 1x (paper towel roll 1) with a good feel for wiping hands can be made.

[0048] Figure 2 shows an example of the embossed pattern 10 in the paper towel roll 1 of this embodiment. The embossed pattern 10 preferably includes radial embossing 11 and closed-ring structure embossing 12, which are formed by linear embossed portions 14. If radial embossing 11 is not included, the paper towel sheet 1x will have a poor feel when wiping hands. If closed-ring structure embossing 12 is not included, the paper towel sheet 1x will have poor water absorption. Furthermore, it is preferable that the radial embossing 11 and the closed-ring structure embossing 12 are arranged alternately at equal intervals. By arranging them alternately at equal intervals, a paper towel sheet 1x with excellent water absorption and ease of use as a product can be obtained.

[0049] The radial embossing 11 is not particularly limited in its overall shape, but it is preferable to have multiple embossing lines extending outward from the center, or embossing shapes made up of straight lines. The inclusion of radial embossing 11 in the embossing pattern 10 makes the paper towel sheet 1x feel superior to the touch when wiping hands. The closed-ring structure embossing 12, like the radial embossing 11, is not particularly limited in its overall shape, but it is preferable that it includes a linear or geometric embossing in the center surrounded by a geometric embossing on the outside to form a closed-ring structure. By including the closed-ring structure embossing 12 in the embossing pattern 10, water is retained inside the embossing, resulting in good water absorption in the paper towel sheet 1x.

[0050] (Water absorption) The water absorption capacity per unit area of ​​the paper towel sheet 1x according to this embodiment is 70 g / m². 2 More than 180g / m 2 The following applies: Water absorption per unit area is 70 g / m². 2 If the absorbency is less than 180 g / m², the absorbency of the paper towel sheets will be poor, and the frequency of changing the paper towel roll will also increase. 2 If it exceeds this limit, a single sheet of paper towels will tear easily during use. The minimum water absorption capacity per unit area of ​​a 1x paper towel sheet is 80 g / m². 2 Preferably, it should be 90 g / m² or more. 2 It is more preferable that the value be greater than or equal to the above. Furthermore, the upper limit is 170 g / m². 2 Preferably, it is 160 g / m². 2 The following is more preferable:

[0051] Furthermore, it is preferable that the water absorption capacity per unit mass of the paper towel sheet 1x is between 1.5 g / g and 7.0 g / g. If the water absorption capacity per unit mass is less than 1.5 g / g, the paper towel sheet 1x will have poor water absorption. If the water absorption capacity per unit mass exceeds 7.0 g / g, the paper towel sheet 1x will tear easily during use. Furthermore, the water absorption per unit mass of a 1x paper towel sheet is more preferably 1.7 g / g or more at the lower limit, and even more preferably 2.0 g / g or more. The upper limit is more preferably 6.0 g / g or less, and even more preferably 5.0 g / g or less.

[0052] The method for measuring the water absorption capacity of each paper towel sheet 1x is explained below, with reference to Figure 3. First, a paper towel sheet 1x stacked on the product ply is taken and cut using a 7.6cm square template to create a rectangular test piece 20 with sides of 7.6cm. The mass of the test piece 20 before water absorption is measured using an electronic balance. The test piece 20 is then placed in a holder 21 (a jig that secures the test piece 20 at three points; the jig is made of a metal that does not absorb moisture).

[0053] Next, fill a commercially available tray with distilled water to a depth of 2 cm, and immerse the test piece 20, which is set in the holder 21, in the distilled water for 2 minutes. After 2 minutes of immersion, remove the test piece 20 and the holder 21 from the distilled water, and hang the holder 21 and the test piece 20 from a rod placed in an empty water tank with the corner 20a facing upwards. Close the lid of the water tank and leave it for 5 minutes.

[0054] Afterward, the holder 21 and test piece 20 are removed from the water bath, the holder 21 is removed, and the mass of the test piece 20 is measured using 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 (water g / sheet m) is determined. 2 , 1m 2 Correct. Abbreviated as g / m 2 Calculate the amount of water absorbed per unit area (water g / sheet m). 2 By dividing this by the basis weight of the product ply of test piece 20, the water absorption per unit area (water g / sheet m) can be calculated. 2 ) / Basis weight (sheet g / sheet m 2 Calculate the water absorption per unit mass (g of water / g of sheet, per gram; abbreviated as g / g). Measure each sample 5 times and use the average value.

[0055] (TSA) Furthermore, using a tissue softness measuring device (TSA), when a sample of 1x paper towel sheets placed on a sample stage is pressed down from above with pressing pressures of 100mN and 600mN without rotating the blade rotor, the measured stiffness (D), which is expressed as the vertical deformation displacement of the sample between pressing pressures of 100mN and 600mN, is between 0.5mm / N and 3.5mm / N. If the measured stiffness (D) is less than 0.5mm / N, the paper towel sheets 1x will have poor feel when wiping hands. If the measured stiffness (D) exceeds 3.5mm / N, the paper towel sheets 1x will tear easily during use. Furthermore, the measured stiffness (D) of the paper towel sheet 1x in TSA is preferably 0.7 mm / N or higher at the lower limit, and more preferably 1.0 mm / N or higher. The upper limit is preferably 3.0 mm / N or lower, and more preferably 2.5 mm / N or lower.

[0056] Furthermore, using TSA, when a bladed rotor was pressed down onto a 1x paper towel sheet sample placed on the sample stage with a pressing pressure of 100mN and then rotated at a rotation speed of 2.0 ( / sec), and the vibration of the sample stage was measured with a vibration sensor, the intensity of the first spectral maximum peak from the low-frequency side, automatically acquired by the software on the TSA (TS750), was 16dBV. 2 RMS or higher, 41 dBV 2 It is preferable that the RMS value is less than or equal to 16 dBV. Maximum peak intensity (TS750): 16 dBV 2 If the RMS is less than 41 dBV, the paper towel sheet (1x) has poor absorbency. 2 Beyond the RMS level, a single sheet of paper towels feels inferior to a regular paper towel in terms of how it dries your hands. Furthermore, the maximum peak intensity (TS750) in the TSA for a 1x paper towel sheet has a lower limit of 17 dBV. 2 It is more preferable that it be rms or higher, and 19 dBV 2 It is even more preferable that the RMS value is greater than or equal to 38 dBV. The upper limit is 38 dBV. 2 It is more preferable that it be less than or equal to rms, and 35 dBV 2 It is even more preferable that the rms value is less than or equal to rms.

[0057] The methods for measuring the intensity (TS750) and stiffness (D) of the maximum peak using the tissue softness measuring device TSA, and the measuring device used, are described in detail, for example, in Japanese Patent Publication No. 2013-236904. For various measurement methods using the tissue softness measuring device TSA, please refer to the above-mentioned patent document. In addition, the intensity (TS750) and stiffness (D) of the maximum peak are basically measured on the surface 1a side of the paper towel sheet 1x.

[0058] <How to manufacture paper towel rolls> A paper towel roll 1 can be manufactured in the following order: (1) papermaking and creping, (2) knurling, and (3) roll winding. In this process, in (1) the papermaking process, the paper quality of the manufactured paper towel sheet, such as basis weight, water absorption, and strength, can be adjusted by appropriately changing the papermaking conditions (pulp composition, chemicals, JW ratio, crepe ratio) and calendering conditions. For details on each condition, please refer to, for example, Japanese Patent Publication No. 2022-072288. In (3) the roll winding process, the winding tightness can be adjusted by the tension of the roll winder and the nip pressure of the embossing roll. Furthermore, the TAD papermaking method may be used in the manufacturing (papermaking) process of paper towel sheets 1x.

[0059] Next, the manufacturing (papermaking) process of a paper towel sheet 1x according to an embodiment of the present invention will be described using Figure 4. Figure 4 shows an example of a paper towel sheet 1x manufacturing apparatus 500. The apparatus 500 in Figure 4 is a fabric press type paper machine that can produce a textured web 103 ((1) base paper made in the papermaking process) using only a pressing mechanism, without using a forced-air drying (TAD) facility for preliminary dewatering. The apparatus 500 comprises a wet section 200 for forming a continuous web, a press section 30 for dewatering and patterning or textured webs, and a drying section 40 for final drying of the web.

[0060] The wet section 200 forms wet paper in a crescent former format and includes a headbox 60 that supplies a paper stock consisting of fibers and water to the forming area, a forming felt 80 and forming wire 90 that dewater a portion of the water in the web, a plurality of guide rolls 100, and a forming roll 70. The headbox 60 discharges a pulp jet in the molding section 50 between the forming wire 90 and the forming felt 80. The forming wire 90 is in an endless loop configuration and travels around multiple guide rolls 100 and forming rolls 70, contacting the forming felt 80 at the forming rolls 70. Consequently, the pulp discharged at position 50 is dewatered by the forming wire 90 to form a fibrous web 101, which is then transported to the press section 30 by the forming felt 80. The forming felt 80 is also in an endless loop configuration and travels around multiple guide rolls 180. The molding section 50 can also be a suction breast roll former.

[0061] The press section 30 comprises a main press 110 and a textured fabric 140. The main press 110 consists of a first press element 120 and a second press element 130. The first and second press elements 120 and 130 are pressed together to form a press nip N1 between them. In the example shown in Figure 4, the main press 110 is a roll press, with the first and second press elements 120 and 130 forming opposing twin rolls. The first press element (roll) 120 is located within the loop of the textured fabric 140, and the second press element (roll) 130 is located within the loop of the forming felt 80, with the forming felt 80 and the textured fabric 140 in contact at the press nip N1. The main press 11 may also be a long nip press or a shoe press (not shown). The textured fabric 140 forms an endless loop and travels around a plurality of guide rolls 150 and a smooth transfer roll 160 facing the drying section 40. When the textured fabric 140 travels around the first press element (roll) 120, it passes through the press nip N1 of the main press 110 and comes into contact with the fibrous web 101 conveyed by the forming felt 80. At the press nip N1, the textured fabric 140 dewaters and textures the fibrous web 101, forming the textured fibrous web 102. The textured fibrous web 102 is then conveyed by the textured fabric 140 to the transfer roll 160. The transfer roll 160 faces the drying cylinder 190 of the drying section 40, which will be described later, and a transfer nip N2 is formed between them. The textured fibrous web 102 that is conveyed to the transfer nip N2 is subjected to drying only, without being pressed or dewatered.

[0062] Furthermore, in the press section 30 (press nip N1), the forming felt 80 acts as a water-receiving press felt 170 that is elastically deformable and compressible in the z-direction (thickness direction). The water-receiving press felt 170 immediately separates the textured fibrous web 102 that has passed through the press nip N1, preventing the web 102 from becoming wet again.

[0063] The drying unit 40 comprises a drying cylinder 190, a crepe doctor 210, and a hood 220 covering the drying cylinder 190. In the example shown in Figure 4, the drying cylinder 190 is a Yankee dryer, but other types of drying units (e.g., air-through dryers, metal drying belts) can be used. Furthermore, the drying unit may be a single unit (e.g., one cylinder as in Figure 4) or may consist of multiple drying units. The surface of the drying cylinder 190 forms a drying surface 201 near the transfer nip N2 for drying the textured fibrous web 102. The crepe doctor 210 is positioned downstream of the drying surface 201 and crepes the textured fibrous web 102 that has been dried by the drying surface 201, thereby obtaining a final web 103 that has been both textured and crepe-coated. Crepe-coating is a known method of mechanically compressing paper in the longitudinal direction (machine running direction) to form wavy wrinkles called crepes, which impart bulkiness, softness, water absorption, surface smoothness, and aesthetics (crepe shape) to the paper. This type of crepe-coating is called dry crepe-coating. There is also wet crepe-coating (performed when the paper is wet, before it dries), but dry crepe-coating is preferred because it tends to produce softness and bulkiness.

[0064] Furthermore, in order to ensure that the web 102 is reliably transferred from the textured fabric 140 to the dry surface 201, it is advisable to apply adhesive to the dry surface 201 using a spray device 230. The spray device 230 can be positioned between the crepe doctor 210 and the transfer nip N2, in a location where the dry surface 201 is exposed. Examples of textured fabric 140 include a mesh-like wire in which metal or synthetic resin (plastic) wires are woven vertically and horizontally as warp and weft threads.

[0065] The paper stock used to manufacture the paper towel sheet 1x according to this embodiment may include pulp and non-wood pulp. In the present invention, in order to obtain the target quality, it is preferable to use wood pulp as the raw material in a mass ratio of NBKP:LBKP = 10:90 to 90:10, more preferably NBKP:LBKP = 20:80 to 80:20, and even more preferably NBKP:LBKP = 30:70 to 70:30. As for the type of wood for LBKP, pulp produced from the genus Eucalyptus of the Myrtaceae family, such as Eucalyptus grandis and Eucalyptus globulus, is preferred.

[0066] Furthermore, while the paper towel sheet 1x according to this embodiment may contain 100% recycled paper pulp, recycled paper pulp has a wide range of quality variations, and increasing the proportion of recycled paper pulp significantly affects the quality of the product, especially its softness. Therefore, it is preferable that the amount of recycled paper pulp is 60% or less by mass relative to the wood pulp.

[0067] In order to maintain a basis weight within the above range while ensuring good wiping performance, it is preferable to beat the pulp fibers using a refiner or the like to adjust their strength. To obtain the target quality, virgin pulp is beaten to reduce the Canadian standard filtration capacity, as measured by JIS P 8121, from 350 mL to 700 mL, more preferably from 400 mL to 600 mL. However, in this invention, simply beating the pulp fibers reduces the paper thickness and water absorption of the sheet; therefore, it is preferable to add a dry strength enhancer and a wet strength enhancer during papermaking. This makes it possible to improve both the strength and water absorption of the sheet simultaneously. In this invention, the paper thickness per 10 plies of sheet is preferably 0.50 mm to 0.70 mm, and more preferably 0.60 mm to 0.65 mm.

[0068] As a dry strength enhancer, it is preferable to use cationized starch, polyacrylamide, carboxymethylcellulose, etc. As a wet strength enhancer, it is preferable to use polyamide epichlorohydrin resin, melamine resin, etc. The amount of dry strength enhancer added is preferably 0% to 1%, and the amount of wet strength enhancer added is preferably 0.1% to 1%.

[0069] As described above, according to this embodiment, it is possible to provide a paper towel roll that has good water absorption, is less prone to holes forming on the surface, and reduces the cost of pulp usage and drying energy during manufacturing, without increasing the basis weight of the sheet.

[0070] 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 obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. Furthermore, it is clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention. [Examples]

[0071] The present invention will be described in detail below with reference to examples. However, the present invention is not limited in any way to the examples shown below.

[0072] Paper towel rolls (kitchen towel rolls) of Examples 1 to 17 and Comparative Examples 1 to 8, shown in Tables 1 and 2, were manufactured through the following processes: (1) papermaking and creping, (2) knurling, and (3) roll winding. The above parameters were measured for all paper towel rolls of the Examples and Comparative Examples, and the following evaluations were performed. For each of the evaluations below, a score of 1 or 2 points was considered a failure, and a score of 3 points or higher was considered a pass. In addition, all parameters other than those evaluated below were measured according to the standards or measurement methods described above.

[0073] 1. Water absorption of the sheet The absorbency of the paper towel sheets after manufacturing was evaluated based on the amount of water absorbed per unit area, and this was rated on a 5-point scale. The evaluation criteria are as follows: 5: Water absorption per unit area is 91 g / m² 2 That's all. 4: Water absorption per unit area is 81 g / m² 2 More than 91g / m 2 less than 3: Water absorption per unit area is 71 g / m² 2 More than 81g / m 2 less than 2: Water absorption per unit area is 61 g / m² 2 More than 71g / m 2 less than 1: Water absorption per unit area is 61 g / m² 2 less than

[0074] 2. Resistance to tearing during use of the sheet The tear resistance of paper towel sheets was evaluated using GMT, which is the square root of the product of DMDT and DCDT of the paper towel sheet. The GMT value was then used to evaluate the sheet on a 5-point scale. The evaluation criteria are as follows: 5: Paper towel sheet GMT is 6.0N / 25mm or higher. 4: Paper towel sheet GMT is 5.5N / 25mm or more and less than 6.0N / 25mm 3: Paper towel sheet GMT is 5.0N / 25mm or more and less than 5.5N / 25mm 2: Paper towel sheet GMT is 4.5N / 25mm or more and less than 5.0N / 25mm 1: Paper towel sheet GMT is less than 4.5N / 25mm

[0075] 3. How the wipe feels to dry your hands The feel of drying hands with a newly manufactured paper towel sheet was evaluated by 30 monitors. They selected either "good feel" or "bad feel," and the evaluation was rated on a 5-point scale based on the number of people who felt the "bad feel." The evaluation criteria were as follows: 5: The number of people who felt that the product didn't feel good to wipe their hands with was 5 or less. 4: 6-10 people felt that the product didn't feel good to wipe their hands with. 3: 11-15 people felt that the product didn't feel good to wipe their hands with. 2: 16-20 people felt that the product didn't feel good to wipe their hands with. 1: More than 21 people felt that the product did not feel comfortable to wipe their hands with.

[0076] 4. Infrequent roll replacement The time between using up one roll of paper towels after manufacturing was evaluated by 30 monitors. They were asked to choose between "frequent replacement" and "frequent replacement," and the evaluation was given on a 5-point scale based on the number of people who felt the replacement frequency was high. The evaluation criteria are as follows: 5: The number of people who felt that the replacement frequency was high was 5 or less. 4: 6-10 people felt that the replacement frequency was high. 3: 11-15 people felt that the replacement frequency was high. 2: 16-20 people felt that the replacement frequency was high. 1: More than 21 people felt that the exchange frequency was high.

[0077] [Table 1]

[0078] [Table 2]

[0079] As is clear from the results shown in Tables 1 and 2, the paper towel rolls and paper towel sheets of Examples 1 to 17 were all good in terms of water absorption, tear resistance during use, feel when wiping hands, and the frequency of roll replacement. In contrast, the paper towel rolls and paper towel sheets of Comparative Examples 1 to 8 were all inferior in one or more of the following aspects: water absorption, tear resistance during use, feel when wiping hands, and the frequency of roll replacement. Therefore, it has been confirmed that the paper towel roll of the present invention can provide a paper towel roll that maintains the strength of the paper towel sheet, has good wiping feel and water absorption, and requires less frequent roll replacement. [Explanation of Symbols]

[0080] 1 paper towel roll 1a surface 1b back side 1e The outermost edge of the paper towel roll 1x Paper Towel Sheet 2 Paper tube 10 Embossed Patterns 11. Radial embossing 12 Ring-closed structure embossing 13. Textured Pattern 14 Linear embossed area 20 test specimens 20a Corner 21 Holder 30 Press Department 40 Drying section 50 Molding section 60 Headbox 70 Foaming Rolls 80 Forming Felt 90 Forming Wire 100, 150, 180 Multiple guide rolls 110 Main Press 120, 130 press elements (rolls) 140 Textured Fabric 160 Transfer Rolls 170 Water-receiving press felt 190 Drying Cylinder 200 Wet part 201 Dry surface 210 Crepe Doctor 220 Food 230 Spray device 101, 102 Fiber web 103 Web 500 Manufacturing equipment

Claims

1. A paper towel roll is made by winding a paper towel sheet, which consists of two or more layers of laminated sheets, into a roll shape. The roll length is between 155m and 350m. The basis weight per ply of the aforementioned paper towel sheet is 11.5 g / m². ２ 28.0g / m or more ２ The following is the water absorption rate per unit area: 70 g / m² ２ 180g / m or more ２ The following conditions apply: The GMT, which is the square root of the product of the tensile strength DMDT in the MD direction and the tensile strength DCDT in the CD direction during drying, is between 4.5 N / 25 mm and 16.6 N / 25 mm. A paper towel roll characterized in that, when a sample of the paper towel sheet placed on a sample stage is pressed down from above with pressing pressures of 100 mN and 600 mN, respectively, using a tissue softness measuring device TSA, the measured stiffness (D), which is expressed as the amount of vertical deformation displacement of the sample between pressing pressures of 100 mN and 600 mN, is 0.5 mm / N or more and 3.5 mm / N or less.

2. When the TSA (Transmission System) applied a bladed rotor to the paper towel sheet sample placed on the sample stage with a pressing pressure of 100 mN, and then rotated it at a rotation speed of 2.0 ( / sec), and the vibration of the sample stage was measured with a vibration sensor, the intensity of the first spectral maximum peak from the low-frequency side (TS750), which was automatically acquired by the software on the TSA, was 16 dBV. ２ rms or higher, 41 dBV ２ The paper towel roll according to claim 1, characterized in that it is less than or equal to rms.

3. The paper towel roll according to claim 1, characterized in that the paper thickness per ply in the paper towel sheet is 40 μm or more and 140 μm or less.

4. The paper towel roll according to claim 1, characterized in that the tensile strength DMDT in the MD direction of the paper towel sheet when dry is 11.0 N / 25 mm or more and 30.5 N / 25 mm or less.

5. The paper towel roll according to claim 1, characterized in that the tensile strength DCDT in the CD direction of the paper towel sheet when dry is 2.0 N / 25 mm or more and 9.0 N / 25 mm or less.

6. The paper towel roll according to any one of claims 1 to 5, characterized in that the water absorption capacity per unit mass of the paper towel sheet is 1.5 g / g or more and 7.0 g / g or less.

7. The specific volume of the aforementioned paper towel sheet is 1 cm³ ３ / g or more 8cm ３ A paper towel roll according to any one of claims 1 to 5, characterized in that it is less than or equal to / g.

8. A paper towel roll according to any one of claims 1 to 5, characterized in that the roll has a winding diameter of 100 mm or more and 300 mm or less.

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