Paper towel roll and paper towel manufacturing method

Abstract

The present invention provides a paper towel roll and a method for manufacturing the same, which reduces glue residue caused by strike-through during manufacturing while providing excellent water absorption and usability of the sheet. [Solution] A paper towel roll is formed by winding a paper towel sheet into a roll shape, in which sheets having an embossed pattern on at least the surface plies, are laminated such that the product has 3 or more plies and, when the adhesive layer formed by glue is used as the reference, there are 2 or more sheets on the surface side of the adhesive layer, wherein the total basis weight of the sheets on the surface side of the adhesive layer in the paper towel sheet is 22 g / m². 2 More than 48g / m 2 The basis weight per ply of the paper towel sheet is 33 g / m². 2 More than 72g / m 2 The following is true, and the water absorption per unit area is 390 g / m². 2 More than 720g / m 2 The following paper towel rolls and methods for manufacturing the same are provided.

Description

Technical Field

[0001] The present invention relates to a paper towel roll and a method for manufacturing a paper towel.

Background Art

[0002] Various paper towel sheets and paper towel rolls obtained by winding the sheets in a roll shape have been developed and sold.

[0003] In recent years, the length of the sheet in a single roll of paper towels has been increasing. In addition to the increased length, high-quality products are also required to have qualities such as texture and tear resistance.

[0004] Among such high-quality products, paper towel sheets obtained by the so-called TAD (Through Air Drying) papermaking technique (hereinafter, also referred to as the "TAD papermaking method") using through-air drying are attracting attention because they are bulky, have a soft texture, and are excellent in water absorption.

[0005] As a prior art document related to a paper towel roll, for example, in Patent Document 1, a paper towel roll obtained by adhesively treating a sheet provided with an embossing pattern with glue and winding the laminated two-ply paper towel sheet in a roll shape is disclosed. The paper towel sheet has a pattern of irregularities derived from a papermaking process different from the embossing pattern, and the basis weight of the two-ply is 30 g / m 2 to 54 g / m 2 Hereinafter, the paper thickness is 1.3 mm / 10 sheets or more and 5 mm / 10 sheets or less, the water absorption per 1 m 2 of the two-ply is 220 g or more and 600 g or less, the winding length of the paper towel roll is 14 m or more and 44 m or less, and the winding diameter is 110 mm or more and 189 mm or less.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] On the other hand, because the paper towels produced by TAD have high water absorption and absorbency, as shown in Figures 5(b) and 5(c), when there is only one ply 1xx between the embossing roll 50 and the adhesive layer 1xy formed by glue, the glue easily penetrates when bonding the plies together, and a mixture of glue and paper dust (glue residue) tends to accumulate on the embossing roll after passing through the sheet (this phenomenon is called strike-through). This increases the frequency of cleaning the embossing roll, resulting in lower productivity.

[0008] Therefore, as shown in Figure 5(a), by making the sheet 3 plies (3 sheets of ply 1xx) or more, and making the sheet between the embossing roll 50 and the adhesive layer 1xy (1xy is not a paper towel) 2 plies (2 sheets of ply 1xx) or more, strike-through can be prevented. Increasing the number of plies also increases the gaps between the plies, improving water absorption.

[0009] However, simply increasing the number of plies would result in a larger (higher) total basis weight, leading to excessively high costs, and the sheet would become harder, resulting in a less pleasant user experience.

[0010] Conversely, reducing the basis weight per ply can lead to poor water absorption and an increased likelihood of strike-through, due to the reduced amount of sheet between the embossing and the glue.

[0011] Furthermore, as shown in Figure 5(d), if the sheet itself is made of 1 ply (one sheet of ply 1xx), the problems caused by the glue are eliminated, but the water retention in the gaps between the sheets is impaired, resulting in inferior water absorption. Also, if the basis weight is increased too much (made too high) to obtain the same level of water absorption, the sheet becomes hard and the feel is inferior.

[0012] Therefore, paper towels produced using conventional TAD papermaking technology have difficulty meeting all the requirements regarding operational reliability (strike-through), absorbency, and usability.

[0013] This invention has been made in view of these circumstances, and aims to provide a paper towel roll and a method for manufacturing a paper towel roll that reduces glue residue caused by strike-through during manufacturing while providing excellent water absorption and usability of the sheet. [Means for solving the problem]

[0014] The inventors conducted diligent research and discovered that, in a paper towel roll wound into a roll, a paper towel sheet is made by laminating sheets in which an embossed pattern is applied to at least the surface plies, such that the product has 3 or more plies, and the sheets on the surface side of the adhesive layer formed by the glue applied to bond the plies together are 2 or more plies, and the total basis weight of the sheets on the surface side of the adhesive layer in the paper towel sheet is within a predetermined range, and furthermore, the basis weight per product ply and the water absorption per unit area of ​​the product ply are both within predetermined ranges, thereby reducing glue residue due to strike-through during manufacturing, and creating a kitchen towel roll with excellent water absorption and usability, thus solving the above problems and completing the present invention. In other words, the present invention provides the following.

[0015] (1) A first aspect of the present invention is a paper towel roll wound into a roll shape, in which a paper towel sheet is formed by laminating sheets having an embossed pattern on at least the surface plies, such that the product has 3 or more plies and, with respect to the adhesive layer formed by glue applied to bond the plies together, there are 2 or more sheets on the surface side of the adhesive layer, wherein the total basis weight of the sheets on the surface side of the adhesive layer in the paper towel sheet is 22 g / m². 2 More than 48g / m 2is as follows, and the basis weight per product ply of the paper towel sheet is 33 g / m 2 or more and 72 g / m 2 or less, and the water absorption per unit area in the product ply is 390 g / m 2 or more and 720 g / m 2 or less, which is a paper towel roll.

[0016] (2) The second aspect of the present invention is the paper towel roll described in (1), wherein the paper towel sheet has a pattern of irregularities derived from a papermaking process different from the embossing pattern.

[0017] (3) The third aspect of the present invention is the paper towel roll described in (1) or (2), wherein the paper thickness of the paper towel sheet is 1.7 mm / 10 plies or more and 4.9 mm / 10 plies or less.

[0018] (4) The fourth aspect of the present invention is the paper towel roll described in (1) or (2), wherein the specific volume of the paper towel sheet is 8 cm 3 / g or more and 23 cm 3 / g or less.

[0019] (5) The fifth aspect of the present invention is the paper towel roll described in (1) or (2), wherein the tensile strength DMDT in the MD direction when the product ply of the paper towel sheet is dry is 900 cN / 25 mm or more and 2400 cN / 25 mm or less.

[0020] (6) The sixth aspect of the present invention is the paper towel roll described in (1) or (2), wherein the tensile strength DCDT in the CD direction when the product ply of the paper towel sheet is dry is 800 cN / 25 mm or more and 1650 cN / 25 mm or less.

[0021] (7) A seventh aspect of the present invention is a paper towel roll according to (1) or (2), characterized in that the embossing pattern includes line embossing, dot embossing, or both.

[0022] (8) An eighth aspect of the present invention is a method for manufacturing a paper towel roll, in which sheets having an embossed pattern on at least the surface plies are laminated such that the product has 3 or more plies and, with respect to the adhesive layer formed by glue applied to bond the plies together, there are 2 or more sheets on the surface side of the adhesive layer, wherein the total basis weight of the sheets on the surface side of the adhesive layer in the paper towel sheet is 22 g / m². 2 More than 48g / m 2 The basis weight per ply of the paper towel sheet is 38 g / m². 2 More than 67g / m 2 The following is the water absorption per unit area in the product ply: 390 g / m² 2 More than 720g / m 2 The following is a method for manufacturing paper towel rolls, characterized in that drying by TAD is performed in the papermaking process of the paper towel sheet. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a paper towel roll and a method for manufacturing a paper towel roll that reduces glue residue caused by strike-through during manufacturing while providing excellent water absorption and usability of the sheet. [Brief explanation of the drawing]

[0024] [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. [Figure 5] This is a cross-sectional view showing an example of paper towel sheet lamination. [Modes for carrying out the invention]

[0025] 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.

[0026] 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 a paper towel sheet made of three sheets stacked together, the product ply will be 3 plies. In addition, the paper towels (rolls, sheets) in this invention include kitchen towels and various types of paper towels (for wiper use).

[0027] <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 wound into a roll shape, in which sheets having an embossed pattern 10 applied to at least the surface plies are laminated such that the product has 3 or more plies and, when the adhesive layer formed by the glue applied to bond the plies together is used as the reference, there are 2 or more sheets on the surface side of the adhesive layer. Preferably, the paper towel sheets 1x have perforations in the roll width direction at approximately equal intervals in the roll winding 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.

[0028] 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, as well as rolls of other sanitary paper.

[0029] (Roll length and roll diameter) The length of the paper towel roll 1 is preferably 18m or more at the lower limit, more preferably 20m or more, and even more preferably 24m or more. The upper limit is preferably 48m or less, more preferably 42m or less, and even more preferably 38m or less. If the roll length is less than 18m, and the roll diameter DR remains the same, the basis weight of each paper towel sheet increases, making the sheets stiffer and worsening the user experience. If the roll length exceeds 48m, and the roll diameter DR remains the same, the roll density increases, resulting in a tighter roll, crushed embossing, and inferior user experience.

[0030] The roll length is measured as follows: First, measure the length of 10 sheets of paper towels 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 1.80m and the number of sheets is 150, then 1.80m × (150 / 10) = 27m. If paper towel roll 1 does not have perforations, measure the roll length directly.

[0031] The winding diameter DR of the paper towel roll 1 according to this embodiment is preferably 127 mm or more at the lower limit, more preferably 135 mm or more, and even more preferably 140 mm or more. The upper limit is preferably 175 mm or less, more preferably 165 mm or less, and even more preferably 157 mm or less. If the roll diameter DR is less than 127mm, and the roll length remains the same, the roll density will increase instead, resulting in a tighter roll, crushed embossing, and a poor user experience. If the roll diameter DR exceeds 175mm, and the roll length remains the same, the basis weight per paper towel sheet will increase instead, making the sheet stiffer and inferior to use.

[0032] The roll diameter DR is measured using a Diameter Rule manufactured by Muratec KDS Co., Ltd. Three paper towel rolls are measured, and the results are averaged.

[0033] (Roll width and roll mass) The roll width (sheet width) of paper towel roll 1 is preferably 150 mm or more at the lower limit, more preferably 200 mm or more, and even more preferably 250 mm or more. The upper limit is preferably 380 mm or less, more preferably 340 mm or less, and even more preferably 300 mm or less. If the roll width is less than 150mm, the sheet area decreases, resulting in lower water absorption per sheet. If the roll width exceeds 380mm, the sheets become too large, resulting in a less pleasant user experience.

[0034] Furthermore, the roll mass of the paper towel roll 1 is preferably 200g or more at the lower limit, more preferably 240g or more, and even more preferably 260g or more. The upper limit is preferably 680g or less, more preferably 660g or less, and even more preferably 640g or less. If the roll weight is less than 200g, and the roll length remains the same, the basis weight of each paper towel sheet will decrease, resulting in poorer absorbency. If the roll weight exceeds 680g, and the roll length remains the same, the basis weight of each paper towel sheet will increase, making the sheets stiffer and less comfortable to use.

[0035] The roll mass shall be the mass per 280 mm of roll width, excluding the paper tube 2 (core) of paper towel roll 1. If the roll width is not 280 mm, the mass shall be converted to a mass per 280 mm using proportional calculation.

[0036] (Roll density) The roll density of the paper towel roll 1 according to this embodiment has a lower limit of 0.05 g / cm³. 3 Preferably, it is 0.07 g / cm³ or more. 3 It is more preferable that the concentration be greater than or equal to 0.09 g / cm³. 3 It is even more preferable that the values ​​be greater than or equal to the above. Furthermore, the upper limit is 0.16 g / cm³. 3 Preferably, it is 0.15 g / cm³. 3 It is more preferable that the following is the case: 0.13 g / cm³ 3 The following is even more preferable: Roll density is 0.05 g / cm³ 3 If the roll density is less than 0.16 g / cm³, the basis weight of each paper towel sheet will decrease, resulting in poorer absorbency, even if the roll volume remains the same. 3 If it exceeds this limit, and the roll volume remains the same, the basis weight of each paper towel sheet increases instead, making the sheets harder and resulting in a less pleasant user experience.

[0037] 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 280 mm roll width is 551 g, the winding diameter DR is 150 mm, and the outer diameter DI of the paper core is 44 mm, then roll density = 551 g ÷ [{3.14 × (150 mm ÷ 2 ÷ 10) 2 -3.14 × (44mm ÷ 2 ÷ 10) 2} × (280 mm ÷ 10) = 0.12 g / cm 3 This is the result.

[0038] (winding density) The winding density of the paper towel roll 1 according to this embodiment has a lower limit of 0.40 m / cm². 2 Preferably, it should be 0.45 m / cm 2 It is more preferable that the rate is 0.50 m / cm² or higher. 2 It is even more preferable that it be greater than or equal to the above. Furthermore, the upper limit is 0.80 m / cm. 2 Preferably, it is 0.75 m / cm 2 It is more preferable that the following is the case: 0.70 m / cm 2 The following is even more preferable: Winding density is 0.40 m / cm 2 If the roll diameter DR is less than 0.80 m / cm², the basis weight of a 1x paper towel sheet will decrease, resulting in poor water absorption. 2 Beyond a certain point, the material becomes tightly wound, the embossing is crushed, and the user experience deteriorates.

[0039] 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, in the case of a winding length of 27m, 2 plies, winding diameter DR 150mm, and paper core outer diameter DI 39mm, the winding density = (27m × 2) ÷ {3.14 × (150mm ÷ 2 ÷ 10)} 2 -3.14 × (39mm ÷ 2 ÷ 10) 2} = 0.33 m / cm 2 This is the result.

[0040] (Paper tube outer diameter) Furthermore, the outer diameter DI of the paper tube 2, which is the outer diameter of the core of the paper towel roll 1 of the present invention, is preferably 28 mm or more at the lower limit, more preferably 33 mm or more, and even more preferably 40 mm or more. The upper limit is preferably 58 mm or less, more preferably 53 mm or less, and even more preferably 40 mm or less. If the outer diameter DI of the paper core is less than 28 mm, the R (diameter) becomes larger, increasing the rate of winding defects when winding the paper towel sheet 1x onto the paper core 2. If the outer diameter DI of the paper core exceeds 58 mm, and the winding diameter DR remains unchanged, the winding density increases instead, resulting in a tight winding, crushing of the embossing, and a poor user experience.

[0041] 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 outer diameter of the cavity in the core portion is measured.

[0042] Furthermore, the paper tube 2 is made by stacking multiple sheets of base paper, and it is preferable that it is made of two sheets. Bleached kraft pulp (BKP) is preferred as the pulp fiber contained in the base paper. 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 core of the paper towel roll 1 will be easily crushed, resulting in poor operability. In this case, it is preferable that the BKP contained includes 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, requiring greater force when cutting with a log saw, which makes the core more prone to crushing and worsens operability.

[0043] <Paper towel sheets> The paper towel sheet 1x according to this embodiment preferably contains wet pulp. Furthermore, the wet pulp content is preferably 50% or more. If the wet pulp content is less than 50%, the water absorption of the paper towel sheet 1x will be poor. While there is no specific upper limit set for the wet pulp content, if it is too high, the strength of the paper towel sheet 1x tends to increase, which may result in a poor user experience. The wet pulp content in a paper towel sheet 1x is more preferably 70% or more, and even more preferably 90% or more.

[0044] Furthermore, the pulp includes bleached softwood kraft pulp (NBKP) and bleached hardwood kraft pulp (LBKP). The preferred mass ratio of bleached softwood kraft pulp (NBKP) to bleached hardwood kraft pulp (LBKP) in a paper towel sheet 1x is NBKP:LBKP = 40-90% by mass:10-60% by mass. If the mass ratio of NBKP is too low, the paper towel sheet 1x will tear easily. If the mass ratio of LBKP is too high, the paper towel sheet 1x will tear easily. In a paper towel sheet 1x, the mass ratio of bleached softwood kraft pulp (NBKP) to bleached hardwood kraft pulp (LBKP) is more preferably NBKP:LBKP = 50-85% by mass:15-50% by mass, and even more preferably NBKP:LBKP = 60-80% by mass:20-40% by mass.

[0045] Furthermore, for pulp processing, NBKP is preferably beaten, while LBKP is preferably not beaten. In addition, other pulps (such as recycled pulp) may be included in a ratio of preferably 20% by mass, more preferably 10% by mass, even more preferably 5% by mass, and most preferably 0% by mass, relative to the ratio of NBKP to LBKP.

[0046] (Basic weight) The basis weight per ply of the paper towel sheet 1x according to this embodiment is 33 g / m². 2More than 72g / m 2 The following applies: The basis weight per ply is 33 g / m². 2 If the basis weight is less than 72g / m², the absorbency of a 1x paper towel sheet will be poor. 2 Beyond a certain point, the strength of the paper towel sheet increases, but the user experience deteriorates. The basis weight per ply of a 1x paper towel sheet has a minimum value of 45 g / m². 2 Preferably, it is 51 g / m² or more. 2 It is more preferable that the value is greater than or equal to the above. Furthermore, the upper limit is 66 g / m². 2 Preferably, it is 61 g / m² 2 The following is more preferable:

[0047] Furthermore, as shown in Figure 5(a), the total basis weight of the sheets (ply 1xx) on the surface 1a side of the adhesive layer 1xy in the paper towel sheet 1x is 22 g / m². 2 More than 48g / m 2 The following applies: The total basis weight is 22 g / m². 2 If the total basis weight is less than 48 g / m², the absorbency of the paper towel sheet will decrease, making it more likely for strike-throughs to occur. 2 Beyond a certain point, the strength of the paper towel sheet increases, but the user experience deteriorates. Furthermore, in a paper towel sheet 1x, the total basis weight of the sheets (ply 1xx) on the surface 1a side from the adhesive layer 1xy has a lower limit of 30 g / m². 2 Preferably, it is 34 g / m² or more. 2 It is more preferable that the value is greater than or equal to the above. Furthermore, the upper limit is 44 g / m². 2 Preferably, it is 40 g / m 2 The following is more preferable:

[0048] Furthermore, the basis weight per ply of a 1x paper towel sheet has a minimum value of 11 g / m². 2 Preferably, it is 15 g / m 2 It is more preferable that the amount be greater than or equal to 17 g / m². 2It is even more preferable that the value be greater than or equal to the above. Furthermore, the upper limit is 24 g / m². 2 Preferably, it is 22 g / m 2 It is more preferable that the following is the case: 20 g / m 2 It is even more preferable that the basis weight per ply is 11 g / m². 2 If the basis weight is less than 24 g / m², the absorbency of a 1x paper towel sheet will be poor. 2 Beyond a certain point, the strength of the paper towel sheet increases, but the user experience deteriorates. The basis weight of a paper towel sheet 1x is measured in accordance with JIS P 8124. The basis weight of the product ply is calculated using the paper towel sheet 1x as is, while the total basis weight of the sheets on the surface 1a side (ply 1xx) beyond the adhesive layer 1xy is calculated by peeling off the paper towel sheet 1x on the surface 1a side beyond the adhesive layer 1xy and summing the basis weights of each ply 1xx. The basis weight per ply is calculated by dividing the basis weight of the product ply by the number of product plies.

[0049] (paper thickness) The paper thickness of a 1x paper towel sheet is preferably between 1.7 mm / 10 plies and 4.9 mm / 10 plies. If the paper thickness is less than 1.7 mm / 10 plies, the water absorption of the 1x paper towel sheet will be poor. If the paper thickness exceeds 4.9 mm / 10 plies, the specific volume will increase if the basis weight remains the same, making it easier for strike-throughs to occur. Furthermore, the paper thickness of the paper towel sheet 1x is more preferably 2.0 mm / 10 plies or more at the lower limit, and even more preferably 2.5 mm / 10 plies or more. The upper limit is more preferably 4.0 mm / 10 plies or less, and even more preferably 3.0 mm / 10 plies or less.

[0050] 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. The sample used for measurement is 10 plies of a 1x paper towel sheet (for example, if it's 3 plies, 5 sets of product plies are used, and the value is proportionally calculated to equal 10 plies). The measurement is repeated 10 times at different locations, and the average of the measurement results is used as the final paper thickness.

[0051] (Sheet length) The sheet length between perforations (length of one paper towel sheet in the roll winding direction) is preferably 100 mm or more at the lower limit, more preferably 130 mm or more, and even more preferably 150 mm or more. The upper limit is preferably 260 mm or less, more preferably 250 mm or less, and even more preferably 240 mm or less. If the sheet length is less than 100mm, the sheet area decreases, resulting in poor absorbency per sheet of paper towel. If the sheet length exceeds 260mm, the paper towel is too long, resulting in a poor user experience.

[0052] (specific volume) The specific volume of one paper towel sheet is 8 cm³. 3 / g or more 23cm 3 It is preferable that the specific volume is 8 cm³ or less. 3 If the amount is less than / g, the absorbency of a 1x paper towel sheet will be poor. Also, the specific volume is 23cm³. 3 When the weight exceeds / g, the gaps in the paper towel sheet become larger, making it easier for strikes to pass through. The specific volume of one paper towel sheet has a lower limit of 9 cm³. 3 It is more preferable that it be 12cm or more / g. 3 It is even more preferable that the value be 20cm or more.3 It is more preferable that it be less than or equal to / g, and 17cm 3 It is even more preferable that it be less than or equal to / g. The specific volume is calculated by dividing the paper thickness per ply of a 1x paper towel sheet by the basis weight per ply (paper thickness per product ply = basis weight per product ply), and the volume per unit (g) (cm³). 3 It is represented as ).

[0053] (DMDT and DCDT) The Dry Machine Direction Tensile Strength (DMDT) of the product ply of a paper towel sheet 1x in the MD direction when dry is preferably between 900 cN / 25 mm and 2400 cN / 25 mm. If the DMDT is less than 900 cN / 25 mm, the strength of the paper towel sheet 1x will be low, resulting in a lower basis weight and making strike-through more likely. Also, if the DMDT exceeds 2400 cN / 76 mm, the sheet will become too hard, resulting in a poor user experience for the paper towel sheet 1x. Furthermore, the DMDT of the product ply of the paper towel sheet 1x is more preferably 1000 cN / 25 mm or more at the lower limit, and even more preferably 1100 cN / 25 mm or more. The upper limit is more preferably 2150 cN / 25 mm or less, and even more preferably 1950 cN / 25 mm or less.

[0054] Furthermore, the Dry Cross Direction Tensile Strength (DCDT) of the product ply of the paper towel sheet 1x when dry is preferably 800 cN / 25 mm or more and 1650 cN / 25 mm or less. If the DCDT is less than 800 cN / 25 mm, the strength of the paper towel sheet 1x will be low, resulting in a lower basis weight and making strike-through more likely. Also, if the DCDT exceeds 1650 cN / 25 mm, the sheet will become too hard, resulting in a poor user experience for the paper towel sheet 1x. Furthermore, for each paper towel sheet (1x), the DCDT of the product ply is more preferably 900 cN / 25 mm or higher at the lower limit, and even more preferably 1000 cN / 25 mm or higher. The upper limit is more preferably 1550 cN / 25 mm or lower, and even more preferably 1400 cN / 25 mm or lower. The DMDT and DCDT of the product ply of a 1x paper towel sheet shall be measured in accordance with JIS P 8113. The paper towel sheet shall be measured in its original product ply form.

[0055] (WCDT) Furthermore, the Wet Cross Direction Tensile Strength (WCDT) of the product ply of the paper towel sheet 1x when wet is preferably 140 cN / 25 mm or more, more preferably 180 cN / 25 mm or more, and even more preferably 240 cN / 25 mm or more. The upper limit is preferably 420 cN / 25 mm or less, more preferably 380 cN / 25 mm or less, and even more preferably 320 cN / 25 mm or less. If the WCDT is less than 140 cN / 25 mm, the strength of the paper towel sheet 1x will be low, resulting in a lower basis weight and making strike-through more likely. Also, if the WCDT exceeds 420 cN / 25 mm, the sheet will become too hard, resulting in a poor user experience for the paper towel sheet 1x. The WCDT of a 1x paper towel sheet (product ply) will be measured in accordance with the old JIS S 3104 standard. The measurement will be performed on the 1x paper towel sheet as is.

[0056] (Embossed) The paper towel roll 1 (paper towel sheet 1x) of this embodiment is embossed and has an embossed pattern 10. Furthermore, in the present invention, the paper towel sheet 1x is laminated to 3 or more plies after embossing at least the plies on the surface 1a side. When laminating to 3 or more plies, ply bond glue (adhesive) is used and the glue is applied to perform the bonding treatment. By bonding to 3 or more plies in this way, the adhesion between the plies is strengthened, and the paper towel sheet 1x becomes less likely to tear even when wet, as the plies will not peel off. In this case, as shown in Figure 5(a), the sheets (ply 1xx) on the surface 1a side of the adhesive layer 1xy are laminated so that there are 2 or more plies, with respect to the adhesive layer 1xy formed by the glue applied to bond the plies 1xx together. If there are fewer than 2 plies of sheets on the surface 1a side of the adhesive layer 1xy, strike-throughs are more likely to occur.

[0057] Furthermore, it is preferable that the product ply count of a paper towel sheet 1x be 3 plies or more, and most preferably 3 plies. If the product ply count is less than 3 plies, strike-throughs are more likely to occur, and the absorbency of the sheet will be poor.

[0058] Figure 2 shows an example of an embossed pattern 10 applied to a paper towel sheet 1x in the paper towel roll 1 of the present invention. The embossed pattern 10 is not particularly limited, but preferably includes radial embossing 11 and closed-ring structure embossing 12. If radial embossing 11 is not included, the aesthetic appeal of the paper towel sheet 1x as a product will be inferior. If closed-ring structure embossing 12 is not included, the paper towel sheet 1x will have inferior 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.

[0059] The overall shape of the radial emboss 11 is not particularly limited, but it is preferable to have multiple straight line embossings extending outward from the center, or multiple embossings of shapes made up of straight lines. The inclusion of radial embossing 11 in the embossing pattern 10 results in a product with good aesthetic appeal for the paper towel sheet 1x. 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.

[0060] Furthermore, the embossed pattern 10 preferably includes linear embossing 100, and the proportion of linear embossing 100 included in the embossed pattern 10 is preferably 20% or more. If the proportion is less than 20%, the embossed pattern 10 cannot contribute to improving the feel and absorbency, and the paper towel sheet 1x will have inferior feel and absorbency. Furthermore, the proportion of line-shaped embossing 100 included in the embossing pattern 10 is more preferably 50% or more, and even more preferably 90% or more.

[0061] In this case, line-shaped embossing 100 refers to embossing with a thickness of 0.1 mm or more and 4 mm or less, and a length of 5 mm or more. The ratio of 100% line-shaped embossing is calculated as follows: First, divide any 100mm x 100mm area on the embossed surface of the paper towel sheet 1x into 10mm squares. Then, calculate the proportion of the linear embossed area 100 using the following formula. If a single square contains both linear and dot embossing, use the square with the larger proportion of embossing. (Number of squares containing linear embossing / Number of squares containing any type of embossing) × 100 = Percentage of linear embossing (%)

[0062] Furthermore, it is preferable that the embossed pattern 10 includes dot-shaped embossing 13. In this case, it is preferable that the embossed pattern 10 includes line-shaped embossing 100, dot-shaped embossing 13, or both, but it is more preferable that it includes both.

[0063] Furthermore, there are no particular restrictions on whether the back surface 1b of the paper towel sheet 1x is embossed, as long as it has a pattern of irregularities derived from a papermaking process different from the embossed pattern 10 described above. Nested embossing or pin-to-pin embossing may be applied, or it may not be embossed at all, but nested embossing or no embossing is preferred, and more preferably no embossing.

[0064] (Water absorption) In this embodiment, the water absorption capacity per unit area of ​​the product ply of the paper towel sheet 1x is 390 g / m². 2 More than 720g / m 2 The following is the water absorption rate per unit area: 390 g / m² 2 If the value is less than 720 g / m², the absorbency of the paper towel sheet will be poor. 2 If it exceeds a certain limit, and the basis weight remains the same, the specific volume increases instead, making it easier for strike-throughs to occur. Furthermore, the minimum water absorption per unit area for a 1x paper towel sheet is 430 g / m². 2 Preferably, it is 480g / m² or more. 2 It is more preferable that the above values ​​are met. Furthermore, the upper limit is 650 g / m². 2 Preferably, it is 600g / m² 2 The following is more preferable:

[0065] Furthermore, the water absorption per unit mass of the product ply of the paper towel sheet 1x is preferably 8.0 g / g or more at the lower limit, more preferably 8.5 g / g or more, and even more preferably 9.0 g / g or more. The upper limit is more preferably 14 g / g or less, and even more preferably 13 g / g or less. If the water absorption per unit mass is less than 8.0 g / g, the water absorption of the paper towel sheet 1x will be poor. There is no particular upper limit on the water absorption per unit mass, but if it becomes too high, the specific volume will increase instead if the basis weight does not change, making it easier for strike-throughs to occur.

[0066] The method for measuring the water absorption capacity of each paper towel sheet 1x is explained below, with reference to Figure 3. First, take a sheet of paper towels (1x) that has been stacked in two plies, and cut it using a 7.6cm square template to create a rectangular test piece (20) with sides of 7.6cm. Measure the mass of the test piece (20) before water absorption using an electronic balance. Set the test piece (20) 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).

[0067] 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.

[0068] 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). 2By 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 (water g / sheet g, per gram; abbreviated as g / g). Measure each sample 5 times and use the average value. If the product is 3-ply, measure it as is, using the same procedure as for 2-ply.

[0069] <How to manufacture paper towel rolls> A 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. In the paper towel sheet 1x manufacturing (papermaking) process, it is preferable to use the TAD papermaking method (TAD drying).

[0070] In this case, it is preferable that, during the papermaking process, a different uneven pattern originating from the papermaking process (fabric) than the embossed pattern 10 described above is applied to the paper towel sheet 1x. If this uneven pattern is not present, the paper towel sheet 1x will have poor water absorption.

[0071] Furthermore, "originating from the papermaking process" means that in the papermaking process of the paper towel sheet 1x, a pattern of bumps and dips is applied between the headbox 41 of the papermaking machine and the outlet of the Yankee dryer 46. Specifically, in a part of the papermaking process shown in Figure 4, a paper web 40a in the state of pulp slurry is sprayed (supplied) from the headbox 41 between the first fabric (forming fabric) 42 and the second fabric (bumpy fabric) 43, and is drawn onto the second fabric (bumpy fabric) 43 by the forming roll 44, forming a paper web 40b in the state of wet paper. Next, the paper web 40b is dried together with the second fabric (textured fabric) 43 in the through-air dryer 45, resulting in the formation of texture on the dried sheet of paper web 40c. In Figure 4, two through-air dryers 45 are shown, but one unit may suffice. Also, a Yankee hood is shown on the Yankee dryer 46, but the hood is not required. Furthermore, a crepe texture may be applied in the Yankee dryer 46.

[0072] Furthermore, the textured pattern can be changed as needed by altering the fabric pattern (fine pattern, coarse pattern). Changing the textured pattern will alter the specific volume (paper thickness), but it is preferable to select a pattern such that the specific volume in the rolled state falls within the numerical range described above.

[0073] Furthermore, it is preferable that the manufactured paper towel rolls 1 be individually or in multiple individual packages using film or the like for transportation and sale. Preferably, the paper towel rolls 1 are individually packaged in film, and then these individual packages are further multi-packaged into 2 or 3 rolls. More preferably, the number of multi-packaged units is 3 rolls.

[0074] As described above, according to this embodiment, it is possible to provide a paper towel roll and a method for manufacturing the same that reduce glue residue due to strike-through during manufacturing while providing excellent water absorption and usability of the sheet.

[0075] 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]

[0076] Hereinafter, the present invention will be described in detail with reference to examples. Note that the present invention is not limited to the examples shown below.

[0077] (1) TAD papermaking and creping, (2) embossing and laminating, (3) roll winding processes were carried out to produce paper towel rolls of Examples 1 to 7 and Comparative Examples 1 to 5 shown in Table 1. Then, the above-mentioned parameters were measured for all the paper towel rolls of the examples and comparative examples, and the following evaluations were performed. Regarding each of the following evaluations, × was considered as a failure, and △ or above was considered as a pass. Also, for each parameter other than the following evaluations, it was carried out according to the above-mentioned criteria or measurement methods.

[0078] 1. Water absorption of the sheet The water absorption of the paper towel sheet after production was evaluated by the water absorption per unit area at the product price of the paper towel sheet, and it was evaluated in four grades according to the numerical value of the water absorption per unit area. The evaluation criteria are as follows. ◎: The water absorption per unit area is 480 g / m 2 or more ○: The water absorption per unit area is 430 g / m 2 or more and less than 480 g / m 2 △: The water absorption per unit area is 390 g / m 2 or more and less than 430 g / m 2 ×: The water absorption per unit area is less than 390 g / m 2

[0079] 2. Difficulty of strike-through occurrence The difficulty of strike-through occurrence during the production of the paper towel sheet was evaluated by the number of cleaning times of the embossing roll per day of production, and it was evaluated in four grades according to the number of cleaning times of the embossing roll. The evaluation criteria are as follows. ◎: The number of cleaning times of the embossing roll per day of production is less than 2 times ○: The number of cleaning times of the embossing roll per day of production is 2 times or more and 3 times or less​​​ △: The number of times the embossing roll is cleaned per day of production is between 4 and 5 times. ×: More than 6 cleaning cycles of the embossing roll per day of production.

[0080] 3. Ease of use as a product (firmness of the sheet) The firmness of the paper towel sheets after manufacturing was evaluated by 30 monitors, and rated on a four-point scale based on the number of people who felt the sheets were "too firm and had a poor user experience." The evaluation criteria are as follows: ◎: 0-1 person felt that the sheet was too hard and the user experience was poor. ○: 2-4 people felt that the seat was too hard and lacked comfort. △: 5-7 people felt that the seat was too hard and lacked comfort. ×: More than 8 people felt that the seat was too hard and lacked comfort.

[0081] [Table 1]

[0082] As is clear from the results shown in Table 1, the paper towel rolls and paper towel sheets of Examples 1 to 7 had excellent water absorption, were less prone to strike-through during manufacturing, and were easy to use as a product (sheet stiffness). In contrast, the paper towel rolls and paper towel sheets of Comparative Examples 1 to 5 were all inferior in one or more aspects: water absorption, resistance to strike-through, or ease of use as a product (sheet stiffness). Therefore, it has been confirmed that the present invention can provide a paper towel roll and a method for manufacturing the same that reduce glue residue caused by strike-through during manufacturing while providing excellent water absorption and usability of the sheet. [Explanation of symbols]

[0083] 1 paper towel roll 1a surface 1b back side 1e The outermost edge of the paper towel roll 1x Paper Towel Sheet 1xx Ply 1xy adhesive layer 2 Paper tube 10 Embossed Patterns 11. Radial embossing 12 Ring-closed structure embossing 13. Dot-shaped embossing 20 test specimens 20a Corner 21 Holder 40a, 40b, 40c Paper Web 41 Headbox 42,43 Fabric 44 Foaming Roll 45 Through Air Dryer 46 Yankee Hair Dryer 50 embossing rolls 100 Line-shaped embossing

Claims

1. A paper towel roll is formed by winding a paper towel sheet, in which sheets having an embossed pattern on at least the surface plies, are laminated such that the product has three or more plies, and when the adhesive layer formed by the glue applied to bond the plies together is used as a reference, there are two or more sheets on the surface side of the adhesive layer, In the aforementioned paper towel sheet, the total basis weight of the sheet on the surface side of the adhesive layer is 22 g / m². ２ 48g / m or more ２ The following: The basis weight per ply of the aforementioned paper towel sheet is 33 g / m². ２ 72g / m or more ２ The following is true, and the water absorption per unit area in the product ply is 390 g / m². ２ 720g / m or more ２ A paper towel roll characterized by the following:

2. The paper towel roll according to claim 1, characterized in that the paper towel sheet has a pattern of irregularities derived from a papermaking process that is different from the embossed pattern.

3. The paper towel roll according to claim 1 or 2, characterized in that the paper thickness of the paper towel sheet is 1.7 mm / 10 plies or more and 4.9 mm / 10 plies or less.

4. The specific volume of the aforementioned paper towel sheet is 8 cm³. ３ / g or more 23cm ３ A paper towel roll according to claim 1 or 2, characterized in that it is less than or equal to / g.

5. The paper towel roll according to claim 1 or 2, characterized in that the tensile strength DMDT in the MD direction of the product ply of the paper towel sheet when dry is 900 cN / 25 mm or more and 2400 cN / 25 mm or less.

6. The paper towel roll according to claim 1 or 2, characterized in that the tensile strength DCDT in the CD direction of the product ply of the paper towel sheet when dry is 800 cN / 25 mm or more and 1650 cN / 25 mm or less.

7. The paper towel roll according to claim 1 or 2, characterized in that the embossing pattern includes line-shaped embossing, dot-shaped embossing, or both.

8. A method for manufacturing a paper towel roll, in which sheets having an embossed pattern applied to at least the surface plies are laminated such that the product has three or more plies and, when the adhesive layer formed by the glue applied to bond the plies together is used as a reference, there are two or more sheets on the surface side of the adhesive layer, and the paper towel roll is wound into a roll shape, The total basis weight of the sheet on the surface side of the adhesive layer in the paper towel sheet is 22 g / m ２ or more and 48 g / m ２ or less, and The basis weight per ply of the aforementioned paper towel sheet is 33 g / m². ２ 72g / m or more ２ The following is true, and the water absorption per unit area in the product ply is 390 g / m². ２ 720g / m or more ２ The following: A method for manufacturing paper towel rolls, characterized in that drying by TAD is performed in the papermaking process of the aforementioned paper towel sheet.

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