Paper towel roll

Abstract

Even with a paper towel roll made by laminating multiple plies of highly absorbent sheets, we can provide a paper towel roll that is compact, has a good volume, and allows for frequent replacement. [Solution] A paper towel roll 1 is made by laminating a paper towel 1x, in which sheets with an embossed pattern on at least one ply are bonded together with plybond glue or water to form a 2-ply or 3-ply layer, and the paper towel 1x has a basis weight of 30.0 g / m² per product ply. 2 More than 56.0g / m 2 The following specific volume is 7.0 cm³ per product ply. 3 / g or more 14.0cm 3 Less than / g, water absorption capacity of 280g / m² per product ply. 2 More than 540g / m 2 The following is a paper towel roll 1 characterized by having a roll diameter of 108 mm or more and 165 mm or less, and a roll length of 18 m or more and 45 m or less.

Description

Technical Field

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

Background Art

[0002] In recent years, various sheet-like paper towels and paper towel rolls obtained by winding this paper towel into a roll have been developed and sold. For paper towels, a sense of volume and water absorption are required. For example, in Patent Document 1, it is disclosed that an absorbent towel paper web obtained by through-air drying (hereinafter also referred to as "TAD") papermaking technology has unevenness derived from the papermaking process, so it is bulky and excellent in water absorption.

[0003] However, the paper towel obtained by the TAD papermaking technology is bulky and excellent in water absorption, but due to its high paper thickness, the roll density is high and the compactness is poor.

[0004] To improve this compactness, the winding length can be shortened, but the replacement frequency becomes frequent and it becomes difficult to use. Also, if the winding diameter is made too small, the sense of volume is inferior. Therefore, if a paper towel obtained by a normal dry crepe machine is used instead of the paper towel obtained by the TAD papermaking technology, it can be made compact, but the water absorption is inferior.

[0005] By the way, when manufacturing a paper towel roll, it is common to perform embossing. For embossing, pri-bond glue or water is applied to the convex part of the emboss, and it is laminated in 2 to 3 plies. When embossing is performed on the base paper obtained by the TAD papermaking technology, although the paper thickness tends to be thin (low), it was still difficult to make it compact.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a paper towel roll in which a plurality of sheets with high water absorption are laminated in multiple plies, which is compact, has a sense of volume, and has a good replacement frequency.

Means for Solving the Problems

[0008] The inventor conducted intensive studies and found that the above problems can be solved by defining the basis weight, specific volume, water absorption, roll diameter, and roll length of a paper towel obtained by laminating at least one ply of a sheet with an embossed pattern adhered with plybond glue or water into 2 or 3 plies and winding it into a roll, thus completing the present invention.

[0009] (1) The first aspect of the present invention is a paper towel roll obtained by winding a paper towel in which at least one ply of a sheet with an embossed pattern is adhered with plybond glue or water and laminated into 2 or 3 plies into a roll, wherein the paper towel has a basis weight of 30.0 g / m 2 or more and 56.0 g / m 2 or less per product ply, a specific volume of 7.0 cm 3 / g or more and 14.0 cm 3 / g or less per product ply, a water absorption of 280 g / m 2 or more and 540 g / m 2 or less per product ply, a roll diameter of 108 mm or more and 165 mm or less, and a roll length of 18 m or more and 45 m or less.

[0010] (2) The second aspect of the present invention is the paper towel roll according to (1), characterized in that the roll density is 0.06 g / cm 3 or more and 0.16 g / cm 3 or less.

[0011] (3) The third aspect of the present invention is the paper towel roll according to (1) or (2), wherein the winding density is 0.29 m / cm 2 or more and 0.76 m / cm 2 or less.

[0012] (4) The fourth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the water absorption amount of the paper towel is 7.0 g / g or more and 13.0 g / g or less per product price.

[0013] (5) The fifth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the paper thickness of the paper towel is 0.31 mm or more and 0.59 mm or less per product price.

[0014] (6) The sixth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the embossing pattern is linear.

[0015] (7) The seventh aspect of the present invention is the paper towel roll according to (1) or (2), wherein the paper towel contains 60% by mass or more of wet pulp.

[0016] (8) The eighth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the end portion of the wound paper towel is adhesively treated to the paper towel roll body.

[0017] (9) The ninth aspect of the present invention is the paper towel roll according to (1) or (2), wherein the sheet has irregularities derived from the TAD papermaking process on the base paper.

[0018] (10) A tenth aspect of the present invention is a paper towel roll as described in (9), characterized in that the base paper is calendered. [Effects of the Invention]

[0019] According to the present invention, even a paper towel roll made by laminating multiple plies of highly absorbent sheets can be provided that is compact, has a substantial feel, and allows for frequent 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 the height profile on the XY plane as measured by a microscope, indicated by varying shades of gray. [Figure 3] This figure shows the height profile on the XY plane as measured by a microscope. [Figure 4] This diagram shows how to determine the depth of an embossed surface. [Figure 5] This figure shows the method for measuring the water absorption capacity of paper towels according to the present invention. [Figure 6] This figure shows a part of the TAD papermaking process for the paper towels 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 this specification, "product ply" refers to the number of plies in a paper towel in its product state, without separating the laminated sheets into individual sheets.

[0023] In this specification, "paper towel roll" (hereinafter also simply referred to as "roll") means a roll product in which paper towels are wound into a roll shape, and "paper towel" means sheet paper before it is wound into a roll of laminated sheets. "Sheet" means sheet paper with an embossed pattern applied to the base paper before lamination, and "base paper" means sheet paper after papermaking before embossing. Furthermore, "cut sheet" means a single sheet of paper cut from a roll along the CD direction of the roll.

[0024] In this specification, the "end of the roll" of a paper towel roll refers to an area of ​​approximately 10 cm in the MD direction from the outermost edge of the roll (1e in Figure 1).

[0025] In this specification, "MD direction" means the direction in which the material flows through the machine, and "CD direction" means the direction perpendicular to the MD direction. Furthermore, in this specification, "MD direction of the roll" means the direction in which the paper towel is wound (Y direction in Figure 1), and "CD direction of the roll" means the direction perpendicular to the direction in which the paper towel is wound (X direction in Figure 1).

[0026] In this specification, an embossed pattern that is "linear" means one that has a thickness of 0.1 mm or more and a length of 5 mm or more.

[0027] <Paper towel roll> One embodiment of the paper towel roll (hereinafter also simply referred to as "roll") 1 according to the present invention will be described with reference to Figure 1. Figure 1 is a perspective view of the roll 1.

[0028] As shown in Figure 1, Roll 1 is a roll made by laminating a paper towel 1x, in which sheets with an embossed pattern (not shown) on at least one ply are bonded together with plybond glue or water to form a 2-ply or 3-ply layer (2 ply in Figure 1), and then winding it into a roll.

[0029] As shown in Figure 1, the paper towel 1x is made up of two layers: a front sheet 1a facing outwards from the roll 1 and a back sheet 1b facing towards the center of the roll. Furthermore, it is preferable that the end of the paper towel 1x is bonded to the roll body with tail seal glue or the like. Additionally, it is preferable that the roll 1 has perforations 1c in the roll width direction at approximately equal intervals along the roll winding direction.

[0030] Uses of Roll 1 include, for example, rolls of kitchen paper (sometimes called paper towels or cooking paper) used in home kitchens or restaurant kitchens for wiping up moisture or oil and removing dirt, hand towels, wipers, and other rolls of sanitary paper.

[0031] <Paper towels> The manufacturing method, specifications, physical properties, and characteristics of paper towel 1x are described in detail below.

[0032] (Paper making method) It is preferable to use base paper obtained by TAD (Through-Air Drying) papermaking technology for paper towel 1x. TAD papermaking technology is a technique in which air drying is performed during the dewatering and drying process of the papermaking process (it is preferable not to press-dewater the wet paper), and by manufacturing using TAD papermaking technology, the base paper can have irregularities derived from the TAD papermaking process, resulting in a bulky, soft paper towel 1x with excellent water absorption.

[0033] (Calendar processing) It is preferable to calender the base paper produced using TAD papermaking technology. Calendering is a processing method in which the produced base paper is passed between metal or resin rollers and pressed while applying heat as needed to flatten the surface of the base paper. This calendering process makes the paper thinner (lower) and improves its smoothness.

[0034] In this invention, calendering allows the paper thickness to be reduced, resulting in improved compactness of the roll 1. Furthermore, it has been confirmed that the water absorption of the paper towel 1x does not decrease significantly even after calendering.

[0035] (raw materials) Paper towel 1x may contain pulp fibers. The pulp fibers preferably consist of wood pulp containing at least one of NBKP (bleached softwood kraft pulp fibers) and LBKP (bleached hardwood kraft pulp fibers), namely BKP. The content is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass. The mass ratio of NBKP to LBKP (NBKP:LBKP) is preferably 40-90% by mass:10-60% by mass. By setting the mass ratio of NBKP to LBKP within the above range, the fiber length contained in the pulp can be made appropriate, resulting in a compact and voluminous paper towel. The mass ratio of NBKP to LBKP is more preferably 50-80% by mass:20-50% by mass, and even more preferably 60-70% by mass:30-40% by mass.

[0036] (Wet pulp content) The proportion of wet pulp fibers in a 1x paper towel (hereinafter also referred to as "wet pulp content") is preferably 60% by mass or more per product ply, more preferably 70% by mass or more, and even more preferably 85% by mass or more. If the wet pulp content is less than 60% by mass, the water absorption will be poor when the basis weight of the 1x paper towel is low.

[0037] Wet pulp refers to wet pulp (sheets) or slush pulp, and is pulp with a solid content of 60% by mass or less, preferably 1% to 50% by mass, more preferably 2% to 20% by mass, and even more preferably 3% to 10% by mass. Dry pulp (sheets) has a solid content of approximately 90% by mass.

[0038] (Irregularities resulting from the TAD papermaking process) It is preferable that the paper towel 1x has irregularities derived from the TAD papermaking process. If it does not have irregularities derived from the TAD papermaking process, the water absorption of the paper towel 1x will be inferior.

[0039] (Number of plies) The number of plies in a paper towel roll is between 2 and 3. If the number of plies is less than 2, the absorbency of the roll is poor; if it exceeds 3 plies, the product's compactness is poor. A ply count of 2 is preferable.

[0040] (Paper thickness per 10 plies) The paper thickness per 10 plies of a 1x paper towel (hereinafter also simply referred to as "paper thickness (10 plies)") is preferably 1.6 mm or more at the lower limit, more preferably 1.8 mm or more, and even more preferably 2.0 mm or more. The upper limit is preferably 2.9 mm or less, more preferably 2.6 mm or less, and even more preferably 2.3 mm or less. If the paper thickness (10 plies) is less than 1.6 mm, the water absorption is poor, and if it exceeds 2.9 mm, the compactness of the roll 1 is poor.

[0041] (Paper thickness per product ply) The paper thickness per product ply of paper towel 1x (hereinafter also simply referred to as "paper thickness (product ply)") is preferably 0.31 mm or more and 0.59 mm or less. If the paper thickness (product ply) is less than 0.31 mm, the water absorption is poor, and if it exceeds 0.59 mm, the compactness of roll 1 is poor. The lower limit of the paper thickness (product ply) is more preferably 0.35 mm or more, and even more preferably 0.40 mm or more. The upper limit is more preferably 0.52 mm or less, and even more preferably 0.46 mm or less.

[0042] The paper thickness shall be the value measured by the following method. The device used shall be a thickness gauge (Dial Thickness Gauge "PEACOCK" manufactured by Ozaki Seisakusho Co., Ltd.). (1) 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. (2) The paper thickness will be measured at 10 points in total: 5 points in the MD direction of 1x paper towel, and 5 points shifted in the CD direction from these 5 points. It is important to measure the paper thickness at 10 different points, but the exact positions are not required. (3) When measuring paper thickness (10 plies), stack 10 plies (5 sets of 2-ply paper towels) and measure, repeating the measurement 10 times and averaging the results. If the product is 3 plies, stack 9 plies (3 sets of 3-ply paper towels) and measure, and calculate the paper thickness per ply from the measurement results to convert to 10 plies. (4) Paper thickness (product ply) is calculated by converting the paper thickness per 10 plies into the number of product plies.

[0043] (Basic weight) The basis weight per ply of a 1x paper towel (hereinafter also simply referred to as "basis weight (ply)") is 30.0 g / m². 2 More than 56.0g / m 2 The following applies: Basis weight (product ply): 30.0 g / m² 2 If it is less than 56.0 g / m², the water absorption is poor. 2 Beyond this limit, the compactness of Roll 1 deteriorates. The lower limit of basis weight (product ply) is 34.0 g / m². 2 The above is preferable, and 38.0 g / m 2 The above is preferable. The upper limit is 50.0 g / m². 2 The following is preferable: 46.0 g / m 2 The following are more preferable. Note that the basis weight is measured according to JIS P 8124.

[0044] (specific volume) The specific volume per product ply of a paper towel (hereinafter also simply referred to as "specific volume (product ply)") is 7.0 cm³. 3 / g or more 14.0cm 3 It is less than / g. The specific volume (product ply) is 7.0 cm³. 3 If the amount is less than / g, the water absorption is poor, 14.0cm 3 If the amount exceeds / g, the compactness of Roll 1 deteriorates. The lower limit of the specific volume (product ply) is 8.0 cm³. 3More preferably 9.0 cm or more per gram. 3 A value of 13.0 cm or more is even more preferable. The upper limit is 13.0 cm. 3 Preferably less than / g, and 12.0cm 3 Less than / g is preferable.

[0045] Specific volume (product ply) is calculated by dividing the paper thickness (product ply) by the basis weight (product ply), and the volume per gram is cm³. 3 It is represented as follows.

[0046] (Embossed pattern) Each paper towel 1x has an embossed pattern on at least one ply. For example, if the product has two plies, the embossed pattern may be applied to either the front sheet 1a or the back sheet 1b as shown in Figure 1. Alternatively, both the front sheet 1a and the back sheet 1b may have separate embossed patterns. If the product has three plies, the embossed pattern may be applied to any of the sheets, but it is preferable, for example, that all three sheets, or the front sheet and the middle sheet, have embossed patterns.

[0047] (Sheet bonding and lamination) For example, as shown in Figure 1, the embossed front sheet 1a and the back sheet 1b are bonded together using plybond glue (hereinafter also simply referred to as "glue") or water to form a 2-ply laminate. The bonding structure involves applying glue or water to the raised embossed areas formed on the front sheet 1a and / or the back sheet 1b to perform the bonding process. Bonding with glue is particularly preferable because it strengthens the bond between the plies, making it less likely for the plies to peel off even when the paper towel 1x gets wet.

[0048] (Plibond glue) The Plybond glue can be any known type, with polyvinyl alcohol (PVOH) and carboxymethylcellulose being preferred, and polyvinyl alcohol being more preferred. Polyvinyl alcohol is a water-soluble polymer obtained by further saponifying polyvinyl acetate, which is obtained by polymerizing vinyl acetate. Therefore, it has excellent adhesion, thermal stability, and oil resistance, and its strong adhesion allows for compact sheet and roll production.

[0049] In addition to polyvinyl alcohol, the product may also contain starch, carboxymethylcellulose (CMC), etc., but it is preferable that it not contain these. Furthermore, the polyvinyl alcohol can be fully or partially saponified, but fully saponified is more preferable.

[0050] The viscosity of the Plybond glue at 20°C is preferably 10 mPa·s or higher at the lower limit, more preferably 20 mPa·s or higher, and even more preferably 30 mPa·s or higher. The upper limit is preferably 200 mPa·s or lower, more preferably 150 mPa·s or lower, and even more preferably 100 mPa·s or lower.

[0051] The lower limit of the concentration of the active ingredient contained in the glue is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0052] (Embossing pattern) The embossing pattern applied to the paper towel 1x is not particularly limited and may be linear or dotted, for example, but a linear embossing pattern is preferred. Compared to a dotted pattern, a linear pattern is easier to compact and has better water absorption.

[0053] If the embossed pattern is linear, it can be a solid line, dashed line, dotted line, or double-dotted line, and the thickness can be any thickness. Furthermore, there are no particular restrictions on the shape of each individual emboss, and they can be circles, ovals, rectangles, squares, floral patterns, etc.

[0054] (Area ratio of the embossed pattern) The area ratio of the embossed pattern on a sheet of paper towel 1x (hereinafter also simply referred to as the "embossed area ratio") is preferably 4% or more, more preferably 6% or more, and even more preferably 8% or more. The upper limit is preferably 38% or less, more preferably 28% or less, and even more preferably 16% or less. If the embossed area ratio is less than 4%, the embossing of paper towel 1x is not sufficiently compressed, resulting in poor compactness of roll 1. In addition, the adhesion of the plies becomes weaker, making it impossible to make the sheet and roll compact. If the embossed area ratio exceeds 38%, the embossing of paper towel 1x is compressed, resulting in poor volume of roll 1.

[0055] The area ratio of the embossing is determined by measuring the area of ​​a 1x sheet of paper towel, which corresponds to the top 10% of the roll 1, using a ruler or measuring tape, and converting it to a ratio per unit area (area ratio). When the embossing is difficult to see or the width of the embossing is narrow, it is preferable to measure the area using a microscope (KEYENCE VR-6100). Note that the top 10% of the roll 1 refers to the 10% portion from the outer part of the roll 1 (the part closest to the roll surface). For example, if the length of the roll 1 is 30m, it refers to the first 3m of use.

[0056] The area ratio of the embossing is determined by the following procedure. (1) Cut out a paper towel 1x along the perforation 1c of roll 1 and cut it into a rectangle E (for example, 100mm x 100mm). Then, prepare a sample by measuring the front sheet 1a and the back sheet 1b while keeping the product ply count the same. (2) If the embossed pattern is linear, the total length of the embossed lines, which are 0.1 mm or thicker and 4 mm or shorter and 5 mm or longer, shall be measured, and the area of ​​the embossed line shall be calculated as "total length (mm) × thickness (mm)". If the thickness of the embossed line is not constant, the area of ​​each individual embossed line shall be calculated as "embossed line length (mm) × thickness (mm)", and then the areas of all embossed lines shall be summed up. (3) If the embossed pattern consists of rectangular dots, the area is calculated from the length and width of each dot. If the pattern consists of circular dots, the area is calculated from the diameter of each dot. This area is then multiplied by the number of dots to obtain the area of ​​the embossing. (4) The ratio of the embossed area to the area of ​​rectangle E is "(total embossed area / sample area) × 100" and this is defined as the embossed area percentage (%). (5) If it is difficult to determine the embossed area ratio, the area ratio of the raised part of the embossing roll used when embossing can be considered as the embossed area ratio.

[0057] The side length of rectangle E can be adjusted as needed depending on the size of the embossed pattern. Furthermore, if a rectangle containing all the embossed patterns includes an adjacent embossed pattern, the length of that adjacent embossed pattern can also be measured and included in the total length.

[0058] (Depth of embossing) The embossing depth (hereinafter also simply referred to as "embossing depth") of the embossed sheet (ply) of paper towel 1x is preferably 0.06 mm or more, more preferably 0.10 mm or more, and even more preferably 0.14 mm or more. The upper limit is preferably 1.05 mm or less, more preferably 0.55 mm, and even more preferably 0.35 mm or less. If the embossing depth is less than 0.06 mm, the volume of roll 1 is inferior, and if it exceeds 1.05 mm, the compactness of roll 1 is inferior.

[0059] Embossing depth is measured using a microscope. The microscope used is the KEYENCE product "One-Shot 3D Shape Measuring Machine Head (One-Shot 3D Measurement Macroscope VR-3100)". For observing, measuring, and analyzing the microscope images, the KEYENCE product "VR-H1A" can be used. Measurement conditions are 25x magnification and a field of view of 12mm x 9mm. The magnification and field of view may be adjusted as needed depending on the desired embossing size.

[0060] (1) Figure 2 shows the height profile on the XY plane as measured by a microscope, with the height of the paper towel 1x surface represented by shades of gray. Linear areas in Figure 2 that differ in shade from the surrounding areas indicate individual embossing. The depth of the embossing is determined by measuring the height difference of the embossing using the microscope described above. The surface to be measured is the surface facing outwards when the sheet (ply) with the embossed pattern is the front sheet 1a, and the surface facing towards the center when it is the back sheet 1b. Also, when measuring, three turns of paper towel 1x are removed from the paper towel roll 1, and the measurement is taken using the fourth turn of paper towel 1x in its product ply state. If there are perforations 1c, they are avoided when measuring.

[0061] (2) Draw line segment AB as shown in Figure 2 to obtain the height profile in Figure 3. Line segment AB should be drawn across the embossing. Line segment AB should be drawn in the width direction (CD direction) of the paper towel 1x, but if the spacing between embossings is narrow, for example, 2 mm or less, and the height of the raised parts described below becomes low, the line segment may be drawn diagonally or in the MD direction. The height profile is a (measured) cross-sectional curve S that represents the surface irregularities of the actual paper towel 1x sample, but it also contains noise (steep peaks caused by fiber clumps on the surface of the paper towel 1x, fibers extending in a whisker-like manner, or areas without fibers), and it is necessary to remove such noise peaks when calculating the height difference of the irregularities.

[0062] (3) Then, the (measured) cross-sectional curve S in Figure 3 is smoothed with a weighted average radio button filter size of ±12 to obtain the cross-sectional curve W in Figure 4. Note that smoothing using a weighted average radio button filter can be obtained automatically using the analysis software described above. Then, in the graph shown in Figure 4, the average of the maximum values ​​on the vertical axis of the convex part H1 and the convex part H2 adjacent to convex part H1 is calculated, and the minimum value on the vertical axis at the concave part D1 sandwiched between convex parts H1 and H2 is found. The value obtained by subtracting the minimum value from the average of the maximum values ​​is taken as the provisional embossing depth.

[0063] (4) Then, as shown in Figure 4, the same measurement is performed at two consecutive recesses on the cross-sectional curve (two consecutive recesses, recess D1 and recess D2) (two measurement results are obtained at this point). Subsequently, the same measurement is performed at each position where the roll 1 of the paper towel 1x is rotated 90 degrees three times in the MD direction (a total of four measurement positions in the MD direction), and the average value of the eight locations (2 x 4) is finally adopted as the embossing depth. Note that the embossed area in Figure 2 is visually confirmed, and the height profile in Figure 3 is checked to determine the recesses and protrusions.

[0064] (5) Note that the paper towel 1x of the present invention has a pattern of irregularities derived from the papermaking process, which is different from the embossed pattern, and therefore there is variation in the height of the convex parts on either side of the recess. For this reason, if the difference in the vertical axis values ​​between the convex parts and the convex parts flanking the recess (for example, the convex parts H3 and H4 flanking the recess D2) is 0.2 mm or more, the measurement should be taken at a location that avoids that area.

[0065] (Sheet length) The length between perforations 1c and adjacent perforations 1c of a paper towel 1x (the length in the Y direction as shown in Figure 1, hereinafter simply referred to as "sheet length") 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 250 mm or less, more preferably 230 mm or less, and even more preferably 210 mm or less. If the sheet length is less than 100 mm, the water absorption per sheet of paper towel 1x will be poor, and if it exceeds 250 mm, the water absorption per sheet will be unnecessarily high.

[0066] (Seat width) The roll width of a 1x paper towel (W shown in Figure 1, hereinafter also simply referred to as "sheet width") 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 sheet width is less than 150 mm, the water absorption per sheet of the 1x paper towel will be poor, and if it exceeds 380 mm, the water absorption per sheet will be unnecessarily high.

[0067] (DMDT) The Dry Machine Direction Tensile Strength (DMDT) of the product ply of a 1x paper towel in the MD direction during dryness is preferably 7.0 N / 25 mm or higher at the lower limit, more preferably 8.0 N / 25 mm or higher, and even more preferably 9.0 N / 25 mm or higher. The upper limit is preferably 14.0 N / 25 mm or lower, more preferably 13.0 N / 25 mm or lower, and even more preferably 12.0 N / 25 mm or lower. If the DMDT is less than 7.0 N / 25 mm, the basis weight of the 1x paper towel will be lower, resulting in poor water absorption. If the DMDT exceeds 14.0 N / 25 mm, the basis weight of the 1x paper towel will be higher, resulting in poor compactness of the roll.

[0068] (DCDT) The dry cross-direction tensile strength (DCDT) of the product ply of a 1x paper towel when dry is preferably 7.0 N / 25 mm or higher, more preferably 8.0 N / 25 mm or higher, and even more preferably 9.0 N / 25 mm or higher. The upper limit is preferably 14.0 N / 25 mm or lower, more preferably 13.0 N / 25 mm or lower, and even more preferably 12.0 N / 25 mm or lower. If the DCDT is less than 7.0 N / 25 mm, the basis weight of the 1x paper towel will be lower, resulting in poor water absorption. If the DCDT exceeds 14.0 N / 25 mm, the basis weight of the 1x paper towel will be higher, resulting in poor roll compactness.

[0069] The DMDT and DCDT of a 1x paper towel are measured in accordance with JIS P 8113, excluding the perforations 1c of the paper towel.

[0070] (DGMT) For a 1x paper towel product ply, the Dry Geometric Tensile Strength (DGMT) is preferably 7.0 N / 25 mm or higher at the lower limit, more preferably 8.0 N / 25 mm or higher, and even more preferably 9.0 N / 25 mm or higher. The upper limit is preferably 14.0 N / 25 mm or lower, more preferably 13.0 N / 25 mm or lower, and even more preferably 12.0 N / 25 mm or lower. If the DGMT is less than 7.0 N / 25 mm, the basis weight of the 1x paper towel will be lower, resulting in poor water absorption. If the DGMT exceeds 14.0 N / 25 mm, the basis weight of the 1x paper towel will be higher, resulting in poor roll compactness.

[0071] DGMT can be calculated using the geometric mean of DMDT and DCDT. DGMT = (DMDT × DCDT) 1 / 2

[0072] (Water absorption capacity per unit area) The water absorption capacity per unit area of ​​a 1x paper towel product ply (hereinafter also simply referred to as "water absorption capacity <per unit area>") is 280 g / m². 2 More than 540g / m 2 The following is the water absorption rate per unit area: 280 g / m² 2 If it is less than 540g / m², the water absorption will be poor. 2 If it exceeds this, the basis weight of one paper towel increases, resulting in less compactness per roll. The lower limit of water absorption per unit area is 320 g / m². 2 The above is preferable, 360g / m 2 The above is preferable. The upper limit is 480 g / m². 2 The following is preferable: 430 g / m 2 The following are preferable.

[0073] (Water absorption capacity <per unit mass>) The water absorption per unit mass of a 1x product ply of paper towel (hereinafter also simply referred to as "water absorption <unit mass>") is preferably 7.0 g / g or more and 13.0 g / g or less. If the water absorption <unit mass> is less than 7.0 g / g, the water absorption is poor, and if it exceeds 13.0 g / g, the specific volume increases as a result, making the compactness of the roll 1 poor. The lower limit of the water absorption <unit mass> is more preferably 8.0 g / g or more, and even more preferably 9.0 g / g or more. The upper limit is more preferably 12.0 g / g or less, and even more preferably 11.0 g / g or less.

[0074] The amount of water absorbed by a 1x paper towel in a dry state is measured according to the following method. (1) Take a 2-ply stacked paper towel 1x and cut it using a 76mm square template to create a rectangular test piece 20 with sides of 76mm (see Figure 5). (2) After measuring the mass of the test piece 20 before water absorption using an electronic balance, the test piece 20 is set in the holder 21 (a jig that fixes the test piece 20 at three points, and the jig is made of a metal that does not absorb water). (3) Fill a commercially available tray with distilled water to a depth of 2 cm, and immerse the test piece 20 set in the holder 21 in the distilled water for 2 minutes. (4) After immersion for 2 minutes, remove the test piece 20 together with the holder 21 from the distilled water, and as shown in Figure 5, 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. (5) After that, remove the holder 21 and the test piece 20 from the water bath, remove the holder 21, and measure the mass of the test piece 20 using an electronic balance. (6) The amount of water absorbed per unit area is calculated from the change in mass of the test piece 20 before and after immersion in distilled water, and is the amount of distilled water absorbed per unit area of ​​the test piece 20 (water g / sheet m). 2 , 1m 2 Correct. Abbreviated as g / m 2 Calculate (assuming this). (7) Water absorption amount <unit mass> is the amount of water absorbed per unit area (water g / sheet m) 2 This is determined by dividing the water absorption per unit area (water g / sheet m²) by the basis weight of the product ply of the test specimen 20. Specifically, the water absorption per unit area (water g / sheet m²) is calculated by dividing the water absorption per unit area by the basis weight of the product ply of the test specimen 20. 2 ) ÷ Basis weight (sheet g / sheet m) 2 Calculate the water absorption amount (per unit mass) (water g / sheet g, per gram; abbreviated as g / g). (8) Measurements are taken five times for each sample, and the average value is used.

[0075] Furthermore, even if the paper towel 1x is 3-ply, it is preferable to measure it as is, using the same procedure as for 2-ply. This measurement should be performed in accordance with JIS P 8111, at a temperature of 23±1℃ and a humidity of 50±2%. The distilled water should also be maintained at 23±1℃.

[0076] <Paper towel roll> The above paper towel 1x is wound into a roll on a paper tube 1d to form a paper towel roll 1.

[0077] (Paper tube) The paper tube 1d (hereinafter also referred to as the "core") located in the center of the roll 1 and used to wind the paper towels 1x into a roll shape is preferably a cylindrical paper tube. The material (paper) used for the paper tube 1d preferably contains bleached kraft pulp (BKP) such as bleached hardwood kraft pulp (LBKP) or bleached softwood kraft pulp (NBKP) as pulp fibers. The pulp content (mass%) of the paper used for the paper tube 1d is preferably LBKP:NBKP of 30:70 to 100:0, more preferably 50:50 to 100:0, and even more preferably 70:30 to 100:0. Furthermore, the paper used for the paper tube 1d is preferably made of multiple sheets stacked together from the viewpoint of strength.

[0078] (Paper tube outer diameter) The outer diameter of the paper tube 1d (DI in Figure 1) 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 46 mm or less. If the outer diameter of the paper tube is less than 28 mm, the roll diameter will be small when a constant roll length is maintained, resulting in a less voluminous feel. If the outer diameter of the paper tube exceeds 58 mm, the compactness of roll 1 will be poor when a constant roll length is maintained.

[0079] The outer diameter of the paper core is measured using a Diameter Rule manufactured by Muratec KDS Co., Ltd. The measurement is performed by measuring three paper towel rolls and averaging the results.

[0080] (Paper tube mass) The lower limit of the mass of the paper core 1d per 280mm roll width is preferably 10g or more, more preferably 12g or more, and even more preferably 13g or more. The upper limit is preferably 25g or less, more preferably 21g or less, and even more preferably 17g or less. If the paper core mass is less than 10g, the outer diameter of the paper core becomes small, resulting in a smaller roll diameter when a constant roll length is maintained, and a less voluminous feel. If the paper core mass exceeds 25g, the outer diameter of the paper core becomes large, and the compactness of the roll 1 is reduced when a constant roll length is maintained.

[0081] (winding diameter) The winding diameter of roll 1 (DR in Figure 1) is between 108 mm and 165 mm. If the winding diameter is less than 108 mm, roll 1 will have less volume, and the frequency of replacement of roll 1 will increase when the winding length is short. If the winding diameter exceeds 165 mm, roll 1 will be less compact. The lower limit of the winding diameter is preferably 113 mm or more, and more preferably 122 mm or more. The upper limit is preferably 156 mm or less, and more preferably 150 mm or less.

[0082] The winding diameter of roll 1 will be measured using a Diameter Rule manufactured by Muratec KDS Co., Ltd. Three rolls of roll 1 will be measured, and the measurement results will be averaged.

[0083] (Length of volume) The minimum winding length of roll 1 is 18m to 45m. If the winding length is less than 18m, roll 1 will have less volume and will require more frequent replacement. If the winding length exceeds 45m, the winding diameter will be larger, resulting in less compactness for roll 1. The minimum winding length is preferably 20m or more, and more preferably 24m or more. The maximum winding length is preferably 40m or less, and more preferably 35m or less.

[0084] The roll length is measured as follows: First, measure the length of 10 cut sheets of paper towel 1x between perforation 1c and the adjacent perforation 1c on roll 1. Then, measure the number of cut sheets on roll 1, and calculate the roll length proportionally from the length of 10 cut sheets and the number of cut sheets. For example, if the length of 10 cut sheets is 1.80m and the number of cut sheets is 150, then 1.80m × (150 / 10) = 27m. If paper towel roll 1 does not have perforations, measure the roll length directly.

[0085] (winding density) The winding density of roll 1 is 0.29 m / cm². 2 More than 0.76m / cm 2 The following is preferable: A winding density of 0.29 m / cm². 2 If the basis weight is less than 0.76 m / cm², the compactness of roll 1 will be reduced. 2If it exceeds this value, the basis weight decreases, resulting in poor water absorption and consequently a less voluminous feel per roll. The lower limit of the winding density is 0.33 m / cm². 2 The above is more preferable, 0.39 m / cm 2 The above is even more preferable. The upper limit is 0.67 m / cm 2 The following is more preferable: 0.60 m / cm 2 The following is even more preferable.

[0086] 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 core)}. For example, in the case of a winding length of 27m, 2 plies, winding diameter DR 150mm, and core outer diameter DI 39mm, 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.

[0087] (Roll weight <without paper core>) The roll mass of roll 1, excluding the paper core 1d per 280 mm roll width (hereinafter also simply referred to as "roll mass <without paper core>"), is preferably 210 g or more at the lower limit, more preferably 230 g or more, and even more preferably 260 g or more. The upper limit is preferably 560 g or less, more preferably 490 g or less, and even more preferably 450 g or less. If the roll mass <without paper core> is less than 210 g, the volume of roll 1 will be inferior, and if the roll length is short, the frequency of replacing roll 1 will increase. If the roll mass <without paper core> exceeds 560 g, the compactness of roll 1 will be inferior.

[0088] (Roll mass <with paper core>) The roll mass of roll 1, including the paper core 1d per 280 mm roll width (hereinafter also simply referred to as "roll mass <with paper core>"), is preferably 225 g or more, more preferably 245 g or more, and even more preferably 275 g or more. The upper limit is preferably 575 g or less, more preferably 505 g or less, and even more preferably 465 g or less. If the roll mass <with paper core> is less than 225 g, the volume of roll 1 will be inferior, and if the roll length is short, the frequency of replacing roll 1 will increase. If the roll mass <with paper core> exceeds 575 g, the compactness of roll 1 will be inferior.

[0089] (Roll density) The roll density of roll 1 is 0.06 g / cm³. 3 More than 0.16g / cm 3 The following is preferable: Roll density of 0.06 g / cm³ 3 If the density is less than 0.16 g / cm³, the compactness of roll 1 will be poor. 3 Beyond this point, the volume of Roll 1 becomes inferior. The lower limit of roll density is 0.07 g / cm³. 3 The above is more preferable, 0.09 g / cm³ 3 The above is even more preferable. The upper limit is 0.15 g / cm³. 3 The following is more preferable: 0.11 g / cm³ 3 The following is even more preferable.

[0090] 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 core)] × roll width (converted to per 280 mm). For example, if the roll mass (without paper core) per 280 mm roll width is 382 g, the winding diameter DR is 150 mm, and the outer diameter DI of the core is 39 mm, then roll density = 382 g ÷ [{3.14 × (150 mm ÷ 2 ÷ 10) 2 -3.14 × (39mm ÷ 2 ÷ 10) 2} × (280 mm ÷ 10) = 0.083 g / cm³ 3 This is the result.

[0091] (Tail seal) It is preferable that the end of the roll of paper towel 1x is bonded to the roll body 1 with tail seal glue or the like (hereinafter simply referred to as "tail seal"). By applying a tail seal, even when using a calendered sheet, the paper thickness recovers and the roll diameter increases, which can prevent the roll 1 from bulging. It is preferable to bond the end of the roll 1 with tail seal glue, but other means may be used as long as they can suppress fluctuations in the roll diameter.

[0092] The tail seal can be formed by a known method. For example, the sheet 1b on the back side of the end portion of the roll 1 is bonded to the sheet 1a on the front side, which is radially inward. The bond is formed by applying tail seal glue to the end of the roll 1 in the roll winding direction (MD direction) along the roll width direction (CD direction). Alternatively, the tail seal glue may be applied to the end of the sheet of the roll 1 along the roll width direction (CD direction).

[0093] (Tail seal glue) While any known tail seal glue can be used, it is preferable to use one or more selected from the group consisting of starch, polyvinyl alcohol, and carboxymethylcellulose, with polyvinyl alcohol being more preferable. By using the above composition of the glue, the tail seal is less likely to peel off during manufacturing and easier to peel off during use.

[0094] <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 manufacturing (papermaking) process, it is preferable to use the TAD papermaking method. Furthermore, it is preferable to perform calendering between (1) papermaking and creping and (2) embossing and bonding.

[0095] In the papermaking process of (1), it is preferable that a pattern of irregularities derived from the TAD papermaking process, which is different from embossing, is applied to the paper towel 1x. Having this pattern of irregularities further increases the water absorption capacity of the paper towel 1x.

[0096] "TAD papermaking process origin" means that in the papermaking process of paper towel 1x, a textured pattern 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 6, pulp slurry 40a is sprayed (supplied) from the headbox 41 between the first fabric (forming fabric) 42 and the second fabric (textured fabric) 43, and is drawn onto the second fabric (textured fabric) 43 by the forming roll 44, forming wet paper 40b. Next, the wet paper 40b is dried together with the second fabric (textured fabric) 43 in the through-air dryer 45, and as a result, texture is formed on the dried sheet 40c. Note that in Figure 6, the through-air dryer 45 is equipped with two units, but one unit may be used. Also, a Yankee hood is shown on the Yankee dryer 46, but the hood is not required. Crepes may also be applied in the Yankee dryer 46.

[0097] Furthermore, the textured pattern can be changed as needed by altering the fabric pattern (fine or coarse). Changing the textured pattern to a finer pattern will reduce water absorption. On the other hand, selecting a coarser pattern will increase the specific volume, resulting in reduced compactness. Therefore, balance is important when selecting the textured pattern.

[0098] It is preferable to calender the base paper produced using TAD papermaking technology. Calendering is preferably performed before embossing. The calendered base paper is passed between metal or resin rollers and pressed while applying heat as needed to flatten the surface of the base paper. This calendering process can reduce the thickness of the base paper, improve its smoothness, and give it a glossy finish.

[0099] As described above, according to this embodiment, even a paper towel roll made by laminating multiple plies of highly absorbent sheets can be provided that is compact, has a sense of volume, and allows for frequent replacement.

[0100] 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]

[0101] 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.

[0102] Paper towel rolls for Examples 1 to 16 and Comparative Examples 1 to 8, shown in Tables 2 to 3, were manufactured through the following processes: (1) TAD papermaking, creping, and calendering; (2) embossing and lamination; 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.

[0103] 1.Water absorption The "water absorption" of manufactured paper towels was evaluated by 30 monitors through a sensory assessment. A single cut sheet, separated by perforations, was used to wipe up 15g of water spilled on a surface from the outermost, central, and innermost parts of a paper towel roll. Monitors evaluated the paper towels using their usual methods, selecting either "the paper towels have excellent water absorption" or "the paper towels have poor water absorption." The evaluation was then categorized into four levels based on the number of people who selected "the paper towels have poor water absorption." The evaluation criteria were as follows: ◎: 0-1 person selected "Paper towels have poor water absorption." ○: 2-4 people selected "Paper towels have poor water absorption." △: 5-7 people selected "Paper towels have poor water absorption." ×: 8 or more people selected "Paper towels have poor water absorption."

[0104] 2. Compactness The "compactness" of the paper towel rolls after manufacturing was evaluated on a four-point scale based on the measured "specific volume" and "winding diameter." The evaluation criteria are shown in Table 1.

[0105] [Table 1]

[0106] 3. Volume The "volume" of the paper towel rolls after manufacturing was evaluated on a four-point scale based on the measured "roll diameter." The evaluation criteria are as follows: ◎: Winding diameter of 122mm or more ○: Winding diameter is 113mm or more and less than 122mm △: Winding diameter is 108mm or more but less than 113mm ×: Winding diameter less than 108mm

[0107] 4. Replacement frequency The "replacement frequency" of paper towel rolls after manufacturing was evaluated on a four-point scale based on the measured "roll length." The evaluation criteria are as follows: ◎: Roll length of 24mm or more ○: Roll length is 20mm or more but less than 24mm △: Roll length is 18mm or more but less than 20mm ×: Roll length is less than 18mm

[0108] The results obtained are shown in Tables 2 and 3.

[0109] [Table 2]

[0110] [Table 3]

[0111] As is clear from the results shown in Tables 2-3, the paper towel rolls of Examples 1-16 all exhibited good water absorption, compactness, volume, and replacement frequency. In contrast, Comparative Examples 1-8 were inferior in any one of the following areas: water absorption, compactness, volume, or replacement frequency.

[0112] From the above, it has been confirmed that the present invention can provide a paper towel roll that is compact, has a sense of volume, and allows for frequent replacement, even if it is a paper towel roll made by laminating multiple plies of highly absorbent sheets. [Explanation of symbols]

[0113] 1: Paper towel roll (roll) 1a: Front sheet 1b: Back side sheet 1c: Perforation 1d:Paper tube 1e: The outermost edge of the paper towel roll 1x: Paper towel 20: Test piece 20a: Corner 21: Holder 40a: Pulp Slurry 40b: Wet paper 40c: Dry sheet 41: Headbox 42: First Fabric (Forming Fabric) 43: Second fabric (textured fabric) 44: Foaming Roll 45: Through-air dryer 46: Yankee Hair Dryer

Claims

1. A paper towel roll is formed by laminating sheets, each having an embossed pattern on at least one ply, with two or three plies by bonding them together with plybond glue or water, and then winding the resulting paper towel into a roll. The aforementioned paper towels Basis weight: 30.0 g / m² per ply product ２ 56.0g / m or more ２ below, Specific volume is 7.0 cm³ per product ply. ３ / g or more 14.0cm ３ / g or less, Water absorption capacity: 280 g / m per ply of product ２ 540g / m or more ２ The following applies: The winding diameter is between 108 mm and 165 mm, and the winding length is between 18 m and 45 m. A paper towel roll characterized by the following features.

2. Roll density is 0.06 g / cm³ ３ 0.16g / cm or more ３ The paper towel roll according to claim 1, characterized in that it is as follows:

3. The roll density is 0.29 m / cm ２ or more and 0.76 m / cm ２ or less, and the paper towel roll according to claim 1 or 2, characterized in that it is as described above.

4. The paper towel roll according to claim 1 or 2, characterized in that the water absorption capacity of the paper towel is 7.0 g / g or more and 13.0 g / g or less per product ply.

5. The paper towel roll according to claim 1 or 2, characterized in that the paper thickness of the paper towel is 0.31 mm or more and 0.59 mm or less per product ply.

6. The paper towel roll according to claim 1 or 2, characterized in that the embossed pattern is linear.

7. The paper towel roll according to claim 1 or 2, characterized in that the paper towel contains 60% by mass or more of wet pulp.

8. The paper towel roll according to claim 1 or 2, characterized in that the end of the roll of the paper towel is bonded to the paper towel roll body.

9. The paper towel roll according to claim 1 or 2, characterized in that the sheet has irregularities derived from the TAD papermaking process applied to the base paper.

10. The paper towel roll according to claim 9, characterized in that the base paper is calendered.

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