Roller toilet paper

Abstract

This invention provides a roll of toilet paper that is a long-length product, allowing for visual confirmation of a well-designed pattern, and has few wrinkles or creases, resulting in a smooth surface. This problem is solved by a roll of toilet paper with a winding diameter of 90-120 mm, consisting of two layers of toilet paper wound together. The weight per unit area of ​​each layer of toilet paper is 11.0-14.0 g / m². 2 The paper is 60-90 μm thick and has embossed texture. It has a pattern formed by full-page printing on one side. The pattern has a first solid portion and a second solid portion of different colors. The total area of ​​the pattern portion is 8-20%, the total area of ​​the first solid portion is 2.0-4.0%, and the total area of ​​the second solid portion is 6.0% or more. In the toilet paper roll, the toilet paper is wound on a paper tube with the printed pattern side as the outer layer side and a length of 65-90 m and a winding density of 0.83-2.05.

Description

Technical Field

[0001] This invention relates to roll toilet paper, which is made by winding toilet paper into a roll shape. Background Technology

[0002] Toilet paper rolls are a daily necessity, and due to limited space in bathrooms, the length of the roll is an important factor for consumers when deciding to buy.

[0003] Regarding the winding length of toilet paper rolls, in popular household products, two-ply toilet paper rolls, also known as double-layer toilet paper, are typically around 25m long, while single-ply toilet paper rolls, also known as single-layer toilet paper, are typically around 50m long. However, in recent years, longer products with winding lengths of 1.5 to 3 times that of toilet paper rolls have become increasingly popular (see Patent Document 1 below).

[0004] In order to achieve a roll diameter suitable for use in commonly used household toilet paper holders, the toilet paper needs to have a low basis weight, and in addition, the paper thickness needs to be reduced and the roll needs to be rigidly wound.

[0005] However, in conventional two-ply toilet paper rolls of approximately 25m or one-ply toilet paper rolls of approximately 50m, patterns and designs are printed on the toilet paper using ink (see Patent Document 2 below). This toilet paper roll has an excellent design.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-064664

[0009] Patent Document 2: Japanese Patent Application Publication No. 2008-188070 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, in long-size toilet paper rolls, as mentioned above, it is necessary to make the toilet paper low in basis weight, and also to make the paper thinner and rigidly wound. Therefore, if patterns are printed, ink bleed-through will occur, and sometimes unnecessary ink bleeding will occur on the back side.

[0012] In addition, because the ink is applied to the thinner base paper and the paper roll is hardened, paper breaks are more likely to occur during manufacturing, and wrinkles or creases are more likely to form.

[0013] Furthermore, because the ink is applied to thinner paper, the ink-applied areas have a noticeable hardness, and sometimes it is difficult to perceive smoothness.

[0014] Furthermore, since toilet paper rolls are made by stacking multiple layers of toilet paper, in long-sized products, the patterns of the lower layers of toilet paper are over-visualized, sometimes failing to express the desired design based on the patterns.

[0015] Therefore, the main objective of this invention is to provide toilet paper rolls that are easy to manufacture in long-size products, free of wrinkles or creases, with visually recognizable patterns and a smooth surface that is easy to feel.

[0016] Methods for solving problems

[0017] The first solution to the above-mentioned problem is a roll of toilet paper, which is a roll of toilet paper with a winding diameter of 90mm to 120mm made by rolling two layers of toilet paper, characterized in that...

[0018] The weight per unit area of ​​one layer of the toilet paper is 11.0 g / m². 2 ~14.0g / m 2 The toilet paper has a thickness of 60μm to 90μm.

[0019] The toilet paper has an embossed texture.

[0020] The toilet paper has a pattern formed by full-page printing on one side.

[0021] The pattern has a first solid portion and a second solid portion with different colors.

[0022] The proportion of the total area of ​​the patterned portion is 8% to 20%.

[0023] The proportion of the total area of ​​the first solid portion is 2.0% to 4.0%.

[0024] The proportion of the total area of ​​the second solid portion is 6.0% or more.

[0025] In the roll toilet paper, the toilet paper is wound onto a paper tube with a length of 65m to 90m and a winding density of 0.83 to 2.05, with the side printed with the pattern being the outer layer side.

[0026] The second method is to use the toilet paper from the first method mentioned above,

[0027] The ten-point average roughness [RzJIS] of the outer layer of toilet paper is 0.025 to 0.320 mm.

[0028] The third method is to incorporate the toilet paper from the first or second method mentioned above into the roll of toilet paper.

[0029] Toilet paper is a double-layered, double-embossed toilet paper made by laminating two sheets of paper with a concave side on one side and a convex side on the other side, with their concave side facing outwards.

[0030] The fourth method is to include, in the toilet paper rolls produced by the first to third methods mentioned above,

[0031] The roll density of the toilet paper is 0.1–0.3 g / cm³. 3 .

[0032] The fifth method is to include, in the toilet paper rolls produced by the first to fourth methods mentioned above,

[0033] The porosity of the toilet paper roll is 3-20%.

[0034] The effects of the invention

[0035] According to the present invention, a roll of toilet paper is provided, which is a long-size product and is easy to manufacture, without wrinkles or creases, with visually recognizable well-designed patterns, and thus the smoothness of the surface is easily felt. Attached Figure Description

[0036] Figure 1 This is a perspective view of a toilet paper roll according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the measurement sequence of whiteness and color difference in this invention.

[0038] Figure 3 This is a diagram used to illustrate the pattern printing of the present invention.

[0039] Figure 4 This is a diagram illustrating an example of an embossed pattern used in this invention. Detailed Implementation

[0040] Next, the toilet paper roll of the present invention will be described with reference to the accompanying drawings. For example... Figure 1 As shown, the toilet paper roll 1 of the present invention is a toilet paper roll in which two layers of strip toilet paper 10 are wound in a roll shape around a paper tube (also called a core) 20.

[0041] The winding diameter L2 (diameter) of the toilet paper roll 1 of the present invention is 90 to 125 mm, preferably 110 to 120 mm. If the winding diameter is 90 to 125 mm, it is easy to install in a general holder. Here, the winding diameter L2 is a value measured using a caliper manufactured by MURATEC-KDS Co., Ltd. or an equivalent instrument. The measured value is the average value obtained by measuring three points at different positions in the width direction. It should be noted that the roll width L1 of the toilet paper roll in this embodiment is not limited, but is preferably 100 to 130 mm. Furthermore, the outer diameter L3 of the paper tube is not limited, but is preferably 34 to 42 mmφ.

[0042] The toilet paper roll of the present invention is characterized in that, regarding the toilet paper, the unit area weight of one layer is 11.0 to 14.0 g / m³. 2 The toilet paper has a thickness of 60-90 μm and has an embossed texture. It has a pattern formed by full-page printing on one side. The pattern has a first solid portion and a second solid portion of different colors. The total area of ​​the pattern portion accounts for 8-20%, the total area of ​​the first solid portion accounts for 2.0-4.0%, and the total area of ​​the second solid portion accounts for more than 6.0%. The toilet paper is wound on a paper tube with a length of 65-90 m and a winding density of 0.83-2.05, with the side with the printed pattern as the outer layer.

[0043] The toilet paper roll of the present invention, by having these structures, prevents ink bleed-through during printing patterns, reduces unnecessary ink bleeding on the back side, and minimizes paper breaks during manufacturing. Furthermore, the absence of wrinkles or creases prevents the pattern on the underlying toilet paper from being overly visually discernible, allowing for a distinctive design. Additionally, the stiffness of the ink-imprinted areas is less noticeable, resulting in a smooth feel.

[0044] In the toilet paper roll of the present invention, the thickness of one layer of the wound toilet paper is 60 to 90 μm, preferably 60 to 85 μm. If the thickness of one layer is 60 to 90 μm, sufficient strength and softness as toilet paper can be achieved, and when a length of 65 to 90 m is wound onto a paper tube, it is easy to set the winding diameter L2 (diameter) to a range of 90 to 120 mm. Furthermore, under the pattern printing conditions of the present invention, it is easy to form toilet paper rolls that do not exhibit ink bleed-through, do not produce unwanted ink bleeding on the back side, and are less prone to paper breakage during manufacturing.

[0045] The paper thickness was measured as follows: After conditioning the test piece for at least 8 hours under JIS P 8111 (1998) conditions, it was measured under the same conditions using a dial-type thickness gauge (thickness measuring instrument) "PEACOCK G type" (manufactured by Ozaki Corporation) in a single-layer state. Specifically, after confirming that there was no debris or dust between the plunger and the measuring stage, the plunger was lowered onto the measuring stage, causing the scale of the dial-type thickness gauge to move and align with the zero point. Then, the plunger was raised to place the sample on the measuring stage, and the plunger was slowly lowered while reading the scale. During measurement, the plunger was simply placed without pressing it. The plunger terminal is a metal terminal with a 10mm diameter circular flat surface that contacts the paper plane perpendicularly. The load during paper thickness measurement was approximately 70gf. The paper thickness was set as the average value obtained from 10 measurements. It should be noted that measurements were performed even on toilet paper with embossed textures. In this case, the measurement is performed with the entire concave portion within the measuring stage. Damage caused by the concave or convex shape during measurement can be ignored. Therefore, the difference in paper thickness caused by the damage to the concave portion can be disregarded in this paper thickness measurement.

[0046] The unit area weight of one layer of the toilet paper of the present invention is 11.0 to 14.0 g / m². 2 The preferred concentration is 11.5–13.5 g / m³. 2 More preferably, it is 12.0–13.0 g / m³. 2 If it is 11.5~14.0g / m 2 The range of values ​​can be easily adjusted to the winding density and porosity of the toilet paper rolls of the present invention. Furthermore, regarding the dry tensile strength or wet tensile strength in the toilet paper rolls of the present invention, it can be appropriately adjusted using known methods within a range that does not impair the effectiveness of the present invention.

[0047] The toilet paper of the present invention has an embossed texture. Embossing the toilet paper makes it softer, and the surface texture enhances its wiping properties for feces. Furthermore, the embossed texture creates an uneven surface, making it difficult to visually discern the underlying pattern, resulting in excellent design flexibility.

[0048] In particular, the toilet paper of the present invention can be single-embossed with embossing based on a two-layer process, but double-embossing is preferred, where two sheets with a concave portion formed on one side and a convex portion formed on the other side are stacked with their concave portions facing outwards. Double-embossed toilet paper is easier to form with the winding density and winding stiffness of the present invention. Furthermore, double embossing easily creates gaps between the layers, making it more difficult to visually identify the pattern of the lower layer through the paper surface, thus resulting in excellent design. In addition, double embossing has concave portions on both sides, eliminating or minimizing the difference between the front and back sides of the stacked sheets. Furthermore, the fact that both sides are concave means that since the user touches the gently angled dome portions between the concave portions with their fingertips, and touches both sides with multiple fingers, the dome portions on both sides provide a soft feel to the fingertips, and due to the soft pulp material and the formation of the gently angled dome portions, the surface feels very smooth to the fingertips. Therefore, even when the pattern is created solely through full-page printing, the patterned area is unlikely to become rigid. Furthermore, double embossing allows for easy elongation relative to stretching in the sheet's extension direction, thus making it particularly less prone to wrinkles or creases caused during manufacturing.

[0049] The specific pattern of the embossing is not limited. Appropriate embossing patterns can be used, such as micro-embossing, dot-matrix embossing, or design embossing. However, it is preferable to configure the embossing in a way that does not degrade the visual recognizability of the printed pattern. For example, it is preferable to have a pattern in which the substrate unrelated to the pattern is perceived, and the recesses are simply arranged regularly. As a more specific example, it is preferable to regularly arrange quadrilaterals, triangles, polygons, circles, ellipses, and quadrilateral stars formed by extending the four corners of quadrilaterals in both the vertical and horizontal directions. Such a pattern allows the concept of the embossed pattern to remain independent of the concept of the printed pattern, enabling a sense of design through collaboration.

[0050] Regarding particularly preferred patterns based on embossed recesses (convexities), such as Figure 4 As shown, on the paper surface as a whole, the bottom surface is a square recess 51 with a diagonal L5 × diagonal L5 = 1.0~1.5 × 1.0~1.5mm. Figure 4 A), or an approximate square formed by extending the four corners of the square outwards from the diagonal (A) Figure 4B) The recesses 51 are arranged in a grid pattern with a center interval L6 of 4.5 to 5.5 mm and an angle of 45° relative to the width direction. Furthermore, between each recess 51, there is a valley line portion 53 extending from the square corners of the recesses to each other. Preferably, the valley line portions 53 are arranged in a gradually flattening arc-shaped cross-section, with the square corners of the recesses 51 being the deepest and the middle between the recesses being the shallowest. This embossed pattern does not reduce the design flexibility of the printed pattern, thus easily improving softness or fluffiness, and consequently improving the wiping properties of feces. In addition, the valley line portions 53 at a 45° angle towards the width direction disperse the tension during winding, resulting in extremely clear embossed texture in the winding length of the toilet paper roll of the present invention, and reducing the likelihood of wrinkles.

[0051] Here, the preferred embossing density of the present invention is 3 to 25 embossings / cm². 2 Preferably 4 to 20 per cm 2 If it is 3-25 per cm 2 The embossing density, in particular, is achieved through the synergy between the design based on embossing and the design based on the printed pattern of this invention. Even when the total area of ​​the patterned portion is less than 10% and the total area of ​​the second solid portion is 6.0%, the printed pattern does not easily give an impression of cheapness, and the improvement in design is readily apparent. Embossing density is measured using a ONESHOT 3D measuring microscope VR-3200 or equivalent instrument manufactured by KEYENCE Co., Ltd., and image analysis software "VR-H2A" or equivalent software. Measurements are performed at 12x magnification and a field of view area of ​​24mm × 18mm. The area encompassing the embossing group comprising multiple units of the embossed pattern is measured, and the number of embossed pieces within that area is counted. "The area encompassing the embossing group comprising multiple units" refers to a closed partition that can constitute the smallest unit, or several times the smallest unit, of the embossed pattern that divides the toilet paper surface into an equal area. Embossing density (pieces / mm²) is defined as follows: 2 The magnification and field of view area can be calculated by dividing the area of ​​the embossed area (including the number of embossed units) by the area of ​​the embossed area (including the area of ​​the embossed units). However, the magnification and field of view area can be adjusted appropriately according to the size of the embossing (recesses).

[0052] On the other hand, regarding the toilet paper of the present invention, it is preferable that the ten-point average roughness [RzJIS] of the outer layer side is 0.025 to 0.320 mm. More preferably, it is 0.025 to 0.315 mm. If the ten-point average roughness [RzJIS] is set within this range, printing friction is less likely to occur, printing clarity becomes better, and design is easier to achieve. The ten-point average roughness [RzJIS] is measured using an ONESHOT 3D measuring microscope VR-3200 or equivalent instrument manufactured by KEYENCE Co., Ltd., and image analysis software "VR-H2A" or equivalent software. The measurement is performed at a magnification of 12x and a field of view area of ​​24 mm × 18 mm. However, the magnification and field of view area can be appropriately changed according to the size of the embossing (recess). For the ten-point average roughness [RzJIS], measurements are performed by taking three-dimensional images and analyzing the data at arbitrary locations, avoiding areas with ink-applied patterns, in the absence of embossing, in the presence of embossed recesses, in locations avoiding recesses, and especially in locations where recesses are regularly arranged, particularly in the middle of adjacent recesses. The profile measured by the line roughness measurement is measured and analyzed in the paper transport direction. The measurement parameters are "composite parameter RzJIS". Regarding the measurement location for toilet paper rolls, the outermost part of the toilet paper roll reflects the smoothness of the surface, but accuracy is reduced; therefore, it is set to an arbitrary location within a range of 29% to 31% from the outermost point where it begins to be used. Furthermore, the measurement value is the average of 10 points, and the measurement sample can be fixed to the measuring table in a way that does not affect the measurement value.

[0053] Furthermore, regarding the toilet paper of the present invention, it is preferable that the number of creases is 35 to 50 per 10 mm. A crease count of 35 to 50 per 10 mm is more preferably 37 to 48 per 10 mm, and even more preferably 39 to 45 per 10 mm. With this number of creases, the surface smoothness is easily perceived, especially in the printing of the pattern of the present invention described above, where the hardness imparted by the ink is less noticeable, and the overall smoothness is easily perceived. This number of creases can be adjusted by the wrinkling rate during the manufacturing of the base paper, the presence or absence of calendering treatment, and the calendering pressure. It should be noted that the number of creases is measured using a ONESHOT 3D measuring microscope VR-3200 or equivalent instrument manufactured by KEYENCE Co., Ltd., and image analysis software "VR-H2A" or equivalent software. The measurement is performed at a magnification of 12x and a field of view area of ​​24 mm × 18 mm. However, the magnification and field of view area can be appropriately changed depending on the size of the embossing (recess). For the number of wrinkles, measurements were taken by capturing three-dimensional images and analyzing the data at arbitrary locations, avoiding areas with ink-applied patterns, in the absence of embossing, in locations avoiding embossed recesses, especially in locations where recesses are regularly arranged, and particularly at locations in the middle of adjacent recesses. The contour line measured by line roughness measurement was designated as perpendicular to the paper transport direction for measurement and analysis. The measurement parameter used was "line roughness". The number of peaks within a 10mm measurement distance of the obtained measurement cross-section curve was taken as the number of wrinkles. Regarding the measurement location for toilet paper rolls, the outermost part of the toilet paper roll reflects the smoothness of the surface, but accuracy is reduced; therefore, it was set to an arbitrary location within a range of 29% to 31% from the outermost point of use. Furthermore, the measurement value was the average of 10 points, and the measurement sample could be fixed to the measuring table in a way that did not affect the measurement value.

[0054] The toilet paper roll of the present invention has a pattern printed on one side of the toilet paper and is wound onto a paper tube such that the side with the pattern printed on it is the outer layer side. That is, the toilet paper roll of the present invention has a pattern only on the outer layer side. By printing the pattern on the outer layer side, the pattern can be reliably and directly visually identified from the outside.

[0055] Furthermore, regarding toilet paper rolls, since toilet paper is multi-layered, there is a concern that if the pattern on the lower layer (one or more layers below) is visible, the pattern on the lower layer may be mixed with the pattern on the outer surface and be visually identifiable. However, the toilet paper of the present invention is two-layered, with an unprinted layer sandwiched between the inner and outer layers. Therefore, if the pattern is formed only on the outer layer within the unit area weight and paper thickness range specified in the present invention, the pattern on the outer surface can be sufficiently visually identified, while the pattern on the lower layer is difficult to visually identify. Especially when double embossing creates gaps between the layers, the pattern on the lower layer is difficult to visually identify. In addition, to ensure that the pattern exists only on the outer layer side, it is sufficient to roll the paper with the printed side facing outwards.

[0056] The patterns of this invention are formed by printing and do not include patterns colored during the papermaking stage by supplying dyes or the like to the papermaking raw materials. The specific design of the pattern is not particularly limited. For example, examples can be shown of shapes drawn by appropriately selecting one or more patterns from plants such as flowers, trees, and grass; living things such as people, animals, fish, shellfish, and insects; nature such as mountains, rivers, seas, clouds, forests, and trees; planets and satellites such as the moon, sun, and stars; and man-made objects such as cars, airplanes, and trams. The area of ​​a pattern is not limited, but is preferably 10.0 mm². 2 ~918mm 2 The pattern is easily visually recognizable, its excellent design is readily apparent, and the amount of ink in a single pattern area does not become excessive, thus preventing bleed-through and easily demonstrating the effects of the invention.

[0057] The pattern of this invention is formed solely through full-page printing. Furthermore, the proportion of the total area of ​​the patterned portion is 8-20%, preferably 8-10%. The proportion of the total area refers to the proportion of the patterned portion relative to the area of ​​one side of the toilet paper. It should be noted that in toilet paper with printed patterns, the pattern is repeated at a predetermined interval due to the manufacturing process; therefore, the method for calculating the proportion of the total area of ​​the patterned portion is as follows: starting from the end of the toilet paper excluding the end seal, 10 sheets are cut into 50cm units as samples. The proportion of the area of ​​the patterned portion relative to the area of ​​one side of each sheet (width of toilet paper × 50cm) is calculated and set as the average value of the 10 sheets. The area of ​​the patterned portion in the sample is measured by optical scanning of the sample using known software.

[0058] If the proportion of the total area of ​​the patterned portion is 8 to 20%, the toilet paper will not feel hard due to the application of ink during use. In particular, it can prevent wrinkles or creases from occurring when manufactured with the tension required for other roll structures of the present invention, such as the winding length and winding diameter.

[0059] Furthermore, the pattern of the toilet paper of the present invention specifically has a first solid portion and a second solid portion of different colors. That is, it has a full-page printing area with two or more colors. Additionally, there can be multiple first solid portions. Additionally, there can be multiple second solid portions. The first solid portion in the present invention is one or more areas printed with a single ink, forming a complete area from a single printing plate. The second solid portion in the present invention is one or more areas printed with a different ink than the first solid portion, forming a complete area from a single printing plate different from the first solid portion. By having full-page printing areas with two or more colors, excellent design is easily achieved.

[0060] In the pattern of the toilet paper of the present invention, the proportion of the total area of ​​the first solid portion is 2.0% to 4.0%, and the proportion of the total area of ​​the second solid portion is 6.0% or more. By setting the proportion of the total area of ​​the first solid portion to 2.0% to 4.0% and the proportion of the total area of ​​the second solid portion to 6.0% or more, the pattern can be clearly identified, and it is not easy for ink to show through, thus ensuring design integrity. In addition, the toilet paper as a whole does not become stiff, and it is less likely to produce the aforementioned wrinkles or creases during manufacturing. Furthermore, when combined with other structures of the present invention to produce roll toilet paper, the solid portion is not excessively identified through the non-patterned portion of the toilet paper located on the outer surface side, thereby becoming a roll toilet paper that is easily recognizable as the desired concept.

[0061] Here, the thickness of one layer of the toilet paper of the present invention is 60-90 μm. Thus, with a relatively low single-layer thickness, and particularly a low weight per unit area, if halftone printing is used to print over a total area of ​​approximately 2.0-4.0%, the printing pressure will not be sufficiently applied to the sheet, resulting in ink not adhering to the sheet and unclear printed areas. Furthermore, this applies to areas where one of the patterns includes the aforementioned 10.0 mm. 2 ~918mm 2 This is prone to occur when the area is large. To improve ink adhesion, simply increasing the pressure is sufficient, but increasing the pressure between the toilet paper and the printing plate slows down the operation speed and worsens operability. Furthermore, the thickness of the toilet paper may decrease. Moreover, if excessive pressure is applied, ink may seep into the layer opposite to the printing surface, causing bleed-through. Regarding the toilet paper of the present invention, while forming a pattern only with full-page printing, the proportion of the total area of ​​the first solid portion is set to 2.0% to 4.0%, and the proportion of the total area of ​​the second solid portion is set to 6.0% or more. This improves operability stability and reduces bleed-through issues. Additionally, due to the aforementioned double embossing or weight per unit area, the stiffness disappears, and wrinkles or creases are less likely to occur.

[0062] The pattern on the toilet paper of the present invention is preferably printed by flexographic printing (letterpress printing) based on water-based inks. However, gravure printing such as photogravure printing and offset printing can also be used. In particular, when water-based inks are used, the pattern can be sufficiently vivid when the viscosity is 10 to 50 cps, the carrier is 30 to 60% by mass, and the water content is 70 to 40% by mass, while wrinkles or creases are less likely to occur even when water permeates the paper. It should be noted that the viscosity is a value measured using a type B viscometer.

[0063] The line count of the anilox roller used when printing the pattern of the present invention is not limited, but is preferably 250 to 600 lines per inch, more preferably 250 to 500 lines per inch. This is suitable for forming the pattern of the present invention.

[0064] In the toilet paper roll of the present invention, the toilet paper having the above-described pattern is wound onto a paper tube with a length of 65 to 90 m and a winding density of 0.83 to 2.05. Regarding the winding length of 65 to 90 m, this is more than twice as long as the conventional 2-ply product (approximately 25 m) for general household use. It should be noted that the winding length is measured while the toilet paper roll is being wound without applying tension. For example, the measurement can be performed while folding back in a zigzag pattern every 5 m from the start of winding.

[0065] Furthermore, the toilet paper roll of the present invention has the aforementioned winding length and a winding density of 0.83 to 2.05. Preferably, it is 0.95 to 1.45, and particularly preferably 1.00 to 1.30. The winding density of the present invention is a value calculated as actual cross-sectional area / theoretical cross-sectional area. Actual cross-sectional area refers to the value calculated as winding length × paper thickness. On the other hand, theoretical cross-sectional area refers to the value calculated as (winding diameter / 2) × (winding diameter / 2) × π - (outer diameter of paper tube / 2) × (outer diameter of paper tube / 2) × π. That is, it is the area obtained by subtracting the area of ​​the open end side of the paper tube from the area of ​​the end face. With the aforementioned winding length, especially when the winding density is in the range of 0.83 to 2.05, it is easy to manufacture, with very few wrinkles or creases. In addition, when the roll is held by hand at the circumference of the roll, it feels moderately taut, indicating sufficient winding length, without becoming excessively soft, and is not easily felt to be too stiff. If the value exceeds 2.05, it tends to feel stiffer compared to the actual winding length. On the other hand, if it is less than 0.83, the softness of the spool is overly perceived relative to the winding length, making it difficult to achieve a sufficient feel.

[0066] Regarding the toilet paper roll of the present invention, it is preferable to have the above-mentioned winding density, and the roll density is 0.10 to 0.30 g / cm³. 3 More preferably, it is 0.10–0.25 g / cm³. 3Roll density is expressed as (roll mass) ÷ (roll volume). Roll mass is the mass of toilet paper per 114mm of roll width. Roll volume is expressed as [{cross-sectional area of ​​the roll's winding diameter (diameter) L2} - (cross-sectional area of ​​the paper tube's outer diameter L3)] × roll width (converted to 114mm). Roll density also serves as an indicator of the degree to which toilet paper is wound in a roll—whether it is tightly and stiffly wound or loosely wound. If it is too loose, excessive deformation such as paper flying out near the tube can easily occur; conversely, if it is too stiff, it will give the impression of being hard when held in the hand.

[0067] Furthermore, in the toilet paper roll of the present invention, by making the toilet paper double-embossed as described above and having a specified unit area weight, and by making the proportion of the total area of ​​the patterned portion 8 to 20%, the proportion of the total area of ​​the first solid portion 2.0 to 4.0%, and the proportion of the total area of ​​the second solid portion 6.0% or more, the pattern can be fully identified, and since it is only full-page printing and show-through is unlikely, wrinkles or creases are minimal. That is, when the winding length is long and the winding density is high, it is necessary to increase the tension to wind the toilet paper onto the paper tube in order to form a toilet paper roll. In patterned toilet paper, the paper elongation is different in the printed portion where ink is applied and the non-printed portion where ink is not applied. Therefore, if the tension is increased, the toilet paper is prone to wrinkles or creases when it is formed into a toilet paper roll. However, in the toilet paper roll of the present invention, this problem can be solved. In particular, it provides toilet paper rolls with excellent pattern recognition and no see-through printing, and which feel sufficiently soft when held in the hand, without any wrinkles or creases.

[0068] Furthermore, regarding the toilet paper roll of the present invention, it is preferred that the porosity is 3-20%. The porosity (%) of the present invention refers to the value calculated as (actual porosity of the entire roll) / (theoretical roll volume) × 100 (actual porosity of the entire roll). The actual porosity of the entire roll is calculated as (actual cross-sectional area (cm²)). 2 The theoretical roll volume is calculated as (winding length (cm) × 2 × paper thickness (1 layer, cm)) × (roll width (cm)). The porosity (actual porosity of the entire roll, %) is calculated based on (theoretical roll volume (cm²)). 3 Actual roll volume (cm³) 3 Theoretical roll volume (cm³) 3Calculated by multiplying the value by 100 (%). For the roll width L1, it can be set to approximately 100-130 mm. The porosity is an indicator of the degree of space within the toilet paper roll, representing the degree of spatial tightness. This indicator is adjusted by embossing, paper thickness, and winding stiffness. With thicker paper, the porosity increases, but this can lead to situations where the embossing is too deep and hard, making it difficult to crush, or where the paper layer itself is too thick; in either case, it will feel stiff. In this invention, a higher porosity tends to make the roll feel stiffer, while a lower porosity tends to make it feel softer. It should be noted that when the porosity exceeds 20%, the print becomes noticeably transparent, sometimes making it difficult to visually identify the roll design; when the porosity is below 3%, the print may sometimes appear unclear due to printing friction.

[0069] Furthermore, regarding the toilet paper of the present invention, it is preferable that the whiteness of the unprinted portion is 80% or more, and the color difference ΔE between the Lab value obtained by directly measuring the printed portion of the lower layer and the Lab value obtained by measuring the printed portion of the upper layer of toilet paper through the unprinted white portion is (ΔL). 2 +(Δa) 2 +(Δb) 2 ) 1 / 2 The value is in the range of 2.20 or lower. More preferably, it is less than 2.00. More preferably, the color difference ΔE′ between the Lab value obtained by measuring the patterned white portion of the unpatterned white portion of the upper tissue paper and the Lab value of the unpatterned white portion of the upper tissue paper is 6.0 or lower. If the whiteness, ΔE, and ΔE′ are such, then... Figure 3 As shown, the pattern 40 of the lower layer, seen through the unprinted white portion of the upper layer of toilet paper, is not visually recognized too clearly, but rather vaguely. At the same time, the pattern of the upper layer is clearly visible. Therefore, the contrast between the directly visually recognizable patterns 41 and 42 and the lower layer pattern 40 visible through the white portion of the toilet paper creates a unique and characteristic design. In particular, with a pattern printing rate of 8-20%, the pattern area is not too large, allowing for a suitable appreciation of the effect created by the contrast between the directly visually recognizable printed portion, the white portion, and the printed portion visible through the upper layer.

[0070] Here, the measurement order of whiteness and color difference ΔE and ΔE′ in this invention is as follows: Figure 2As shown, five sheets of white cardboard 31 are stacked on a horizontal measuring table, and the sample 33, which is to be measured, is stacked on top of it. Then, the unpatterned portion of toilet paper 34, selected from the same roll of toilet paper as the sample 33, is stacked on top of it in such a way that the patterned portion 32, which is to be measured, is covered. Then, a sheet of white cardboard 35 having a window removal portion 36 with a 20 mm φ is stacked on top of it, so that the patterned portion 32, which is to be measured, is located within the window removal portion 36.

[0071] Then, using a spectrophotometer, the whiteness and Lab value of the patterned portion being measured are taken from the portion 36 removed from the window via toilet paper 34 (the Lab value obtained by measuring the unpatterned white portion of the upper layer of toilet paper is measured). Next, the toilet paper 34 overlapping the patterned portion 32 is removed without moving the measurement area, and the whiteness and Lab value of the patterned portion being measured are taken using a spectrophotometer (the Lab value obtained by directly measuring the patterned portion of the lower layer is measured). Next, the sample is further removed, and the whiteness and Lab value of the top layer of white cardboard 31 with 5 sheets overlapping are measured using a spectrophotometer (the Lab value of the unpatterned white portion of the upper layer of toilet paper is measured) (blank value). It should be noted that the spectrophotometer is a Nippon Denshoku Kogyo Co., Ltd. PF 7000 spectrophotometer / color difference meter or an equivalent instrument. The color differences ΔE and ΔE′ are calculated based on the measured Lab values.

[0072] The number of colors constituting the pattern on the toilet paper of the present invention is not limited as long as it is two or more. From the viewpoints of cost, equipment, and the ease with which the toilet paper absorbs at low densities, two to three colors are preferred. Most preferably, it consists of two colors from the first solid portion and the second solid portion. Furthermore, when measuring the Lab value of the above pattern, if there are multiple colors in a pattern, it is possible to measure all portions of each different color, and all of the measured values ​​are within the above-mentioned range.

[0073] The fibers of the toilet paper of the present invention are not limited, but preferably consist of 70-100% virgin pulp and 0-30% waste paper pulp. If waste paper pulp is blended, it can be manufactured at a lower cost compared to the case consisting of 100% virgin pulp. Furthermore, regarding waste paper pulp, in the process of recycling pulp from waste paper, compared to the pulp fibers before recycling, waste paper pulp tends to have finer fibers. This fiber property prevents the paper from becoming thicker and denser, making it easier to improve paper strength. On the other hand, if waste paper pulp is excessively blended, the softness and other hand feel will decrease. Therefore, considering the characteristics of waste paper pulp, its blending ratio can be set within the range of 0-30% by mass. Additionally, while the type of waste paper pulp is not limited, waste paper pulp made from milk carton waste paper and high-quality waste paper is particularly preferred. These are blended with a large amount of softwood sulfate pulp (NBKP) from the raw materials, thus easily resulting in good paper strength.

[0074] The pulp used can be either softwood sulfate pulp (NBKP) or hardwood sulfate pulp (LBKP). The preferred blending ratio is NBKP:LBKP of 20:80 to 50:50. NBKP can also be derived from milk carton waste paper. Furthermore, regarding toilet paper manufactured using fiber materials composed of virgin pulp and the aforementioned high-quality waste paper pulp, the mechanical pulp from waste paper must be 5% by mass or less, the ash content 3% by mass or less, and the whiteness approximately 80-85%.

[0075] [Elongation at Length of Winding (%)]

[0076] On the other hand, the winding length elongation of the toilet paper roll of the present invention is preferably 1.0 to 3.6%, more preferably 1.6 to 3.3%, and particularly preferably 2.0 to 3.0%. The winding length elongation represents the elongation of the sheet that is stretched and wound inside the roll.

[0077] Regarding the measurement of winding length elongation, it is calculated based on the winding length L0 and the sheet length L1 (m) within the roll, using the winding length elongation (%) = (L1-L0) / L0… [Equation 1]. Here, the winding length L0 (m) is calculated using the following method: For the winding length, the number of sheets is counted in sheets divided by the perforation lines. The first group consists of the second sheet following the outermost rolled sheet (the first sheet), including the tail seal of the roll, up to the sixth sheet. Thereafter, the sheets are continuously cut in groups of five, and the sheet dimensions are actually measured. For the final group, the final group of the innermost roll is selected with two sheets excluding the pick-up section. This final group is designated as the nth group. When actually measuring the sheet dimensions, five consecutive sheets (groups) are placed on a flat surface and measured using a JIS 1 grade metal ruler. First, the average group length is calculated. The average group length is calculated as: Average group length (m) = {Length of group 1 + Length of group 2 + ... + Length of group n} ÷ n ... [Equation 6]. The winding length L0 is calculated as: L0(m) = (Average group length) × n + (Average group length / 5) × {1 + (Number of innermost rolled sheets not including the pickup section)} ... [Equation 7]. It should be noted that the sheet lengths of the tail sealing section and pickup section cannot be accurately measured due to residual adhesive or wrinkles; therefore, they are converted to the average sheet length (average group length / 5) for calculation.

[0078] The sheet length L1 (m) inside the roll represents the winding length of the sheet inside the roll, which is determined by the following steps.

[0079] (1) Use a pen or similar tool to draw a straight line on the side of the roll, starting from the outermost surface of the roll, passing through the central axis of the paper tube, and continuing to the paper tube. Align the mark (pen) on the outermost surface of the roll with the outermost end of the sheet.

[0080] (2) Unwind the roll and count the number of marks made with a universal pen at the ends of the sheet width, which is taken as the number of overlapping layers of the sheet in the roll (2 layers). For the sheet portions that do not include the pick-up section, calculate the number of layers as (number of sheets that are not in a group × average sheet length) ÷ [(paper tube diameter r) × π], and sum them up to get the number of sheet layers P.

[0081] (3) Cross-sectional area of ​​the roll S (cm²) 2 =π / 4 × (wound diameter R) 2 -(paper tube diameter r) 2 …[Equation 2], S is composed of cm 2 Units are used. The winding diameter R and the paper tube diameter r are expressed in cm.

[0082] (4) In addition, when the thickness of the sheet in the roll is set as T (mm), the area of ​​the sheet rolled into a roll and stacked is called the cross-sectional area of ​​the roll. Therefore, T (mm) = 1 / 2 × (Rr) / (P × 10)... [Equation 3]

[0083] (5) Furthermore, S(cm) 2 = Length of sheet in roll L1(m) × T(mm) × 10… [Formula 4], where T(mm) represents the thickness of the sheet in roll.

[0084] (6) Therefore, the length of the sheet inside the roll is L1(m) = S(cm). 2 ) / (T(mm)×10) [Formula 5]

[0085] Therefore, substituting [Equation 2] and [Equation 3], we can obtain L1 = π / 2 × (R + r) × P ÷ 100 … [Equation 6].

[0086] Thus, the winding length elongation (%) in [Equation 1] represents the elongation (%) of the sheet that is stretched and wound within the roll. The greater the elongation (%), the more the sheet is stretched within the roll.

[0087] If the elongation rate (%) of the winding length is less than 1.0%, the sheet has high tensile stiffness and is difficult to stretch. Therefore, the paper will feel stiff, and due to its tensile stiffness, the embossing needs to be deeper and stronger to prevent the embossing from being crushed, resulting in a rough surface. If the elongation rate (%) of the winding length is greater than 3.6%, the sheet has too low tensile stiffness and the sheet is easy to stretch. Therefore, the paper becomes too soft, resulting in a loss of thickness and a sense of security. Furthermore, due to its low tensile stiffness, the sheet stretches, and the embossing also stretches, causing the embossing to be crushed and resulting in reduced clarity and a poor appearance.

[0088] Example

[0089] Next, regarding the embodiments and comparative examples of the toilet paper rolls of the present invention, the "smoothness of the sheet material," "smoothness of the roll surface," "proof of bleed-through," "design," and "printing clarity (including the presence or absence of printing friction)" were confirmed. The composition, physical properties, and test results of the toilet paper rolls of each example are shown in Table 1 below. Comparative Example 5 and Example 6 are examples of rolling single-embossed toilet paper. Other embodiments and comparative examples are examples of rolling double-layer double-embossed toilet paper, wherein the double-layer double-embossed toilet paper is formed by stacking two sheets of material with a concave portion formed on one side and a convex portion formed on the other side through embossing, with their concave portion forming surfaces facing outwards. The embossing pattern in each example is set as follows: Figure 4 The arrangement of the recessed portion of (B). The pattern is... Figure 3The pattern shown is based on the combination of flowers and leaves, and the area of ​​each pattern is adjusted according to the proportion of the total area.

[0090] The smoothness of the toilet paper sheet was evaluated as follows: Two sheets of toilet paper were collected from a roll, with each adjacent perforation line considered as one interval. The subjects touched the toilet paper at these two intervals and rated the smoothness of the sheet surface on a scale of 1 to 5. Regarding the evaluation criteria, for smoothness, "satisfactory" was assigned 5, "slightly satisfactory" was assigned 4, "neither satisfactory" was assigned 3, "slightly unsatisfactory" was assigned 2, and "unsatisfactory" was assigned 1. The values ​​in Table 1 are averages rounded to one place. The number of subjects was 30.

[0091] The smoothness of the toilet paper roll surface was evaluated by having participants physically touch the outer circumference of the roll and rate it on a scale of 1 to 5. Regarding the evaluation criteria, for smoothness, "satisfactory" was assigned 5, "slightly satisfactory" 4, "neither satisfactory" 3, "slightly unsatisfactory" 2, and "unsatisfactory" 1. The values ​​in Table 1 are averages rounded to one place. The number of participants was 30.

[0092] For the prevention of ink bleeding, subjects visually observed the back side (non-printed area) corresponding to the printed portion of the outer periphery of the toilet paper roll. Regarding the ink bleeding towards the back side (non-printed side) of the toilet paper, subjects scored the ink bleeding according to an evaluation criterion: "No ink bleeding observed at all" as 5, "No ink bleeding observed" as 4, "Neither" as 3, "Slight ink bleeding observed" as 2, and "Ink bleeding observed" as 1. The values ​​in Table 1 are averaged and rounded to one place. The number of subjects was 30.

[0093] For the design aspect, participants visually observed the pattern on the outer circumference of a toilet paper roll and judged its balance between the patterned and white areas, the perspective of the underlying pattern, and other factors. Evaluations were based on a rating scale of 5 for "Excellent," 4 for "Excellent," 3 for "Neither," 2 for "Somewhat Cheap," and 1 for "Feeling Very Cheap." Table 1 shows values ​​rounded to one place. The number of participants was 30.

[0094] For print clarity, the evaluation was conducted as follows: Participants visually observed the printed portion of the outer surface of a toilet paper roll. For the printed portion (the ink transfer area), a rating scale was used: "no friction and clear" = 5, "slight friction but generally clear" = 4, "some friction but generally clear" = 3, "partial friction and slightly less clear" = 2, and "overall printing friction and not clear" = 1. The values ​​in Table 1 are averages rounded to one place. The number of participants was 30.

[0095] [Table 1]

[0096]

[0097] Examples 1 to 6 use thinner paper for longer dimensions, yet possess sufficient design potential with the pattern occupying more than 8% of the total area, and are full-page printing while preventing bleed-through. The evaluation is particularly high in the case of double embossing. In contrast, Comparative Example 1 is only a single-color full-page print, and the pattern occupies 7% of the total area, resulting in a very low evaluation of design potential. Furthermore, the evaluation of print sharpness is also low. Comparative Example 3 also has a low evaluation of design potential. Comparative Example 4 has a low evaluation of design potential. This is related to the fact that the pattern is printed only with a single-color full-page print. Additionally, it can be considered that printing flowers and leaves in the same color also has an impact. Furthermore, the evaluation of print sharpness (printing friction) is low. With the pattern occupying 21% of the total area and a wide printing range, printing friction was confirmed, thus lowering the evaluation. Bleed-through was also confirmed. In Comparative Example 2, the proportion of the total area of ​​the pattern is within the scope of the present invention, but by replacing the second solid portion with halftone printing, the proportion of the total area of ​​the pattern is slightly increased, but the evaluations of bleed-through and print sharpness are low. Furthermore, in Comparative Examples 2 to 4, the weight per unit area was relatively large, and the flexibility of the sheet and roll was rated poorly. In Comparative Example 6, replacing the second solid portion with halftone printing resulted in a smaller proportion of the total area of ​​the pattern, but the evaluation of bleed-through and print sharpness was low. Operability was poor.

[0098] On the other hand, in Comparative Example 5, the weight per unit area was relatively large in the case of single embossing. The smoothness of the sheet and the smoothness of the roll surface were rated poorly, as were the print clarity and bleed-through. This is attributed to surface roughness.

[0099] In particular, in terms of print sharpness, the ten-point average roughness (Rz JIS) is within the scope of the present invention and the results are good in the case of double embossing.

[0100] As described above, the toilet paper rolls of the present invention are easy to manufacture even when they are long and thin, without wrinkles or creases, and have visually recognizable patterns with excellent design, thus becoming toilet paper rolls with a smooth surface that is easy to feel.

[0101] Label Explanation

[0102] 1…Toilet paper roll; 10, 34…Toilet paper; 20…Paper tube (core); L1…Width of toilet paper roll; L2…Wrapping diameter of toilet paper roll; L3…Outer diameter of paper tube; 31, 35…Whiteboard paper; 32…Pattern portion; 33…Sample; 36…Window removal portion; 40…Pattern of lower layer; 41…First solid portion of upper layer; 42…Second solid portion of upper layer; 51…Recess; 53…Valveline portion.

Claims

1. A type of toilet paper roll, comprising two layers of toilet paper wound to a diameter of 90mm to 120mm, characterized in that, The weight per unit area of ​​one layer of the toilet paper is 11.0 g / m². 2 ~14.0g / m 2 The toilet paper has a thickness of 60μm to 90μm. The toilet paper has an embossed texture. The toilet paper has a pattern on one side formed solely through full-page printing. The pattern has a first solid portion and a second solid portion based on full-page printing, both with different colors. The proportion of the total area of ​​the patterned portion is 8% to 11%. The proportion of the total area of ​​the first solid portion is 2.0% to 4.0%. The proportion of the total area of ​​the second solid portion is 6.0% to 7.5%. In the roll toilet paper, the toilet paper is wound on a paper tube with a winding density of 0.83 to 2.05, with the side printed with the pattern as the outer layer, for a winding length of 65m to 90m.

2. The toilet paper roll according to claim 1, wherein, The ten-point average roughness [RzJIS] of the outer layer of toilet paper is 0.025 mm to 0.320 mm.

3. The toilet paper roll according to claim 1, wherein, Toilet paper is a double-layered, double-embossed toilet paper made by laminating two sheets of paper with a concave side on one side and a convex side on the other side, with their concave side facing outwards.

4. The toilet paper roll according to claim 2, wherein, Toilet paper is a double-layered, double-embossed toilet paper made by laminating two sheets of paper with a concave side on one side and a convex side on the other side, with their concave side facing outwards.

5. The toilet paper roll according to any one of claims 1 to 4, wherein, The roll density of the toilet paper is 0.1 g / cm³. 3 ~0.3g / cm 3 .

6. The toilet paper roll according to any one of claims 1 to 4, wherein, The porosity of the toilet paper roll is 3% to 20%.

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